application of the analytic hierarchy process (ahp) to ... taiwan j for sci22(1):15-28,2007 15...

15Taiwan J For Sci 22(1): 15-28, 2007

Research paper

1) Division of Forest Uti l izat ion, Taiwan Forestry Research Inst i tute , 53 Nanhai Rd. , Taipei 10066,

Taiwan. 行政院農業委員會林業試驗所森林利用組，10066台北市南海路53號。2) Division of Forestry Economics, Taiwan Forestry Research Insti tute, 53 Nanhai Rd., Taipei 10066,

Taiwan. 行政院農業委員會林業試驗所林業經濟組，10066台北市南海路53號。3) School of Forestry and Resource Conservation, National Taiwan University. 1 Roosevelt Rd., Sec. 4,

Taipei 10617, Taiwan. 國立台灣大學森林環境暨資源學系，10617台北市羅斯福路四段1號。4) Corresponding author, e-mail:yujen@tfri .gov.tw 通訊作者。

Received September 2006, Accepted November 2006. 2006年9月送審 2006年11月通過。

Application of the Analytic Hierarchy Process (AHP)to Analyze the Importance of Bamboo Charcoal

Quality Indicators

Yu-Jen Lin,1,4) Jiunn-Cheng Lin,2) Gwo-Shyong Hwang,1) Kuo-Chung Lee3)

【Summary】

In this paper, we proritized the important evaluation dimensions and indicators for bamboo charcoal quality, which were originally suggested put forth in 2005. By applying the analytic hierarchy process (AHP), 7 main uses of bamboo charcoal products, 4 management criteria, and variable numbers of evaluation indicators were structured into an evaluation framework with 4 hierarchy levels. The main results showed that the importance of the sequence of quality evaluation dimensions and indicators of bamboo charcoal products was determined by their uses. It is not necessary to use the same evaluation dimensions and indicators to evaluate the product quality of bamboo charcoal for all its uses. Among the various uses of bamboo charcoal products, its use in the human diet was regarded as most requiring evaluation. The “material supply” was regarded as the most important evaluation criterion in the management sections with respect to each use of bamboo charcoal.Key words: bamboo charcoal, evaluation indicators, analytic hierarchy process (AHP).Lin YJ, Lin JC, Hwang GS, Lee KC. 2007. Application of the analytic hierarchy process (AHP) to

analyze the importance of bamboo charcoal quality indicators. Taiwan J For Sci 22(1):15-28.

研究報告

應用層級分析法分析竹炭品質指標之重要性

林裕仁1,4) 林俊成2) 黃國雄1) 李國忠3)

摘　要

16 Lin et al.―Application of the AHP to analyze bamboo charcoal quality indicators

本研究主要目的在應用層級分析法(AHP)分析竹炭品質評估之評估層面與評估指標之重要性權重

比例。根據層級分析法之操作原則，本研究將竹炭7類主要用途、4項管理層面及不同數量之重要評估

指標建構為具備4層級之評估架構進行分析。根據專家之意見分析結果顯示，在竹炭相關產品多類用途

中，最需要進行品質評估是用於飲食健康類之產品；在管理層面之評估項目中，原料供給被認為是最

重要之評估項目；而各重要品質評估指標之項目與其權重比例則根據竹炭相關產品之用途類別而有差

異，無須一致性採同樣準則進行評估。

關鍵詞：竹炭、評估指標、層級分析法。

林裕仁、林俊成、黃國雄、李國忠。2007。應用層級分析法分析竹炭品質指標之重要性。台灣林業科

學22(1):15-28。

INTRODUCTIONFor most manufacturers nowadays

which exist in an intense and competitive environment, product quality plays an important role in marketing, because products with good quality can enhance competitiveness, and a long-term good relationship can easily be established with customers, both of which are advantageous to the success and profitability of products on the market (Kopalle and Lehmann 1995, Sethi 2000, Lindgreen et al. 2006). Quality has been defined as the perceived superiority or excellence of a product compared with competing alternatives from the perspective of the marketplace (Garvin 1988, Zeithaml 1988, Sethi 2000), and this superiority or excellence can meet or exceed consumers’ expectations (Kopalle and Lehmann 1995, Kahn et al. 2002). Nevertheless, superiority, excellence, and expectations all are subjective and cannot provide practical guidance for measuring quality (Kahn et al. 2002). It is usually difficult to measure product quality using the foregoing definition without distinct evaluation dimensions. Gavin (1988) and Juran and Gryna (1989) suggested 4 dimensions to measure the quality of general consumption products: aesthetics, performance, life, and workmanship. In addition, Sethi (2000) included another dimension, safety, into quality evaluation,

because an unsafe product cannot be considered a quality product. Therefore, for product manufacturers engaged in marketing planning and consumers in terms of safety of use, and even to academic researchers, it is important to develop specific dimensions for quality evaluation, especially for a new product. However, whether the same dimensions are suitable for measuring product quality when a product can be developed for various uses and functions in different fields, and whether it is suitable to use the same weighting ratio for each dimension or factor for different uses need to be determined. In this study, we took a new utility product, bamboo charcoal, as the case and applied the analytic hierarchy process (AHP) to understand the fitness of the same dimensions for different uses and analyze the priority of each factor among the quality evaluation dimensions.

Bamboo charcoal is made from mature bamboo by a carbonization process in which the bamboo is pyrolyzed in charcoal kilns by burning at temperatures of 450~1000℃ with little oxygen (Hu 2002, Hwang et al. 2004, Zhang et al. 2004). High-temperature carbonized bamboo charcoal possesses various properties such as being dense, porous, and rich in natural minerals, having good release in the far-infrared and good

17Taiwan J For Sci 22(1): 15-28, 2007

electric conductivity, etc (Asada et al. 2002, Zhang et al. 2002, Hwang et al. 2004, Zhang et al. 2004). Using these different properties of bamboo charcoal, in addition to the simple use as fuel for barbecuing, many related products have been developed in various fields, such as environmental, healthcare, and industrial uses. In general, these properties are influenced by the carbonizing conditions, e.g., the removal effect for ammonia is better with bamboo charcoal made from Moso bamboo (Phyllostachys pubescens Mazel) carbonized at 500℃ , and for benzene, toluene, indole, skatole, and nonenal, it is better at 1000℃ (Asada et al. 2002); the electrical resistance of bamboo charcoal decreases as the carbonization temperature increases (Asada et al. 2002, Zhang et al. 2002, Hwang et al. 2004, Zhang et al. 2004); there is a positive relationship between the carbonization temperature and the real density of charcoal made from Makino bamboo (P. makinoi Hay), and a negative relationship exists between the real density and electrical resistance (Hwang et al. 2004).

Because it is environmentally friendly and has multi-functional characters, in recent years, bamboo charcoal production and related products with many innovative uses have rapidly increased in Asian markets, especially in Taiwan, Japan, South Korea, and China, which have abundant bamboo resources. Also, bamboo charcoal has become one of the most-promising natural materials for research and development in the near future (Hosokawa 1992). Therefore, in order to propose product quality criteria for the manufacturing process, protect consumer safety, and promote quality evaluation efficiency, we thoroughly analyzed the quality evaluation mechanism of bamboo charcoal products in this study.

MATERIALS AND METHODS

The analytic hierarchy process (AHP) is the main method applied in this study. The AHP is a very useful analytical tool that allows decision making, by dealing with multiple-criteria decision problems in a systematic manner of multiple pairwise comparisons to select or rank complex alternatives, while producing a measure of the judgment with logical consistency which can offer a way to determine whether the decision model is reasonable (Sivarama Prasad and Somasekhara 1990, Apostolou and Hassell 1993). Therefore, the AHP can help decision makers identify and set priorities on the basis of their objectives as well as their knowledge and experience with each problem (Skibniewski and Chao 1992). In this study, the AHP was applied to determine the priority among important indicators in an evaluation hierarchy framework for bamboo charcoal quality.

According to the AHP principle, the evaluation procedure involves 4 steps, as described in detail as follows.

Step 1: A hierarchical framework needs to be structured with different levels that include all attribute elements that reflect the goals of the study; in this study, we evaluated a previously established bamboo charcoal quality evaluation indicator system. The analyzed quality evaluation dimensions and indicators for bamboo charcoal were offered by Lin et al. (2005) using the Delphi technique. In that evaluation, 8 uses of bamboo charcoal products (see Table 1) were divided with respect to 4 management criteria and a variable numbers of evaluation indicators. However, one of the 8 uses - the use for fuel, was not included for evaluation in this study, because it is not a major use among the multi-functional characters of


Table 1. Description of bamboo charcoal usesUse category Explanation

1. For human diet Products with raw bamboo charcoal are in the forms of slices, tubes, powder, or grains. Functions have a direct influence on human dietetic hygiene, e.g., the filtering and purification of drinking water, producing meals, and cooking. Related products include bamboo charcoal cups, coffee stir sticks from bamboo charcoal, etc.

2. For home healthcare

Products are mainly in a granular form and cover the exterior of ventilation materials to produce various appearances. Functions are to promote human health, but are not used directly in the human diet, mainly being used for release in the far-infrared. Related products include bedding ware such as bamboo charcoal pillows, pillow cushions, mattresses, seat cushions, pillow holders, nap pillows, etc.; healthcare ware for sports such as shoe-pads, waist-pads, knee-pads, vests, etc.; and articles for automobiles such as chairs, chair cushions, back cushions, etc.

3. For air purification Products have forms like those used for the human diet. Functions include air deodorizing, humidity adjustment, and mold prevention in spaces such as refrigerators, clothes hampers, shoe cabinets, automobiles, houses, buildings, various rooms, etc. Related products include deodorizer bags, dehumidification bags, and indoor decorative boards of mixed bamboo charcoal, related building materials used for house foundations, etc.

4. For cosmetics and cleaning

Bamboo charcoal in a powdered form is added and mixed in products. Functions include beautifying and cleaning the face and skin. Related products include shampoos, body washes, hand washes, soaps, cleaning lotions, facial masks, bath bags, etc.

5. For crafts and ornaments

Products with bamboo charcoal are used mainly as beautifying materials added to articles of daily life. Functions include space beautification and air purification at the same time. Related products include necklaces, safety pins, gift drops, cell-phone tote bags, drop bags, wind chimes, colored material for flower arrangements, etc.

6. For hi-tech material

Products with bamboo charcoal are used as intermediate products for various applications in hi-tech industries. At present, the related research and development of items are ongoing such as baseboard material for super power-capacitors, high-capacity battery manufacturing, fiber synthesis mixed with bamboo charcoal in textiles, special coatings manufacture, enzyme fixing in biochemical technology, porous carbon materials manufacturing, nano-carbon tubes in biomedical sciences, etc. Because of an extensive range of uses, there are huge differences in the essential qualities of bamboo charcoal required among the various hi-tech industries.

7. For agriculture (farming, forestry, fishing, and livestock)

Products with bamboo charcoal are used in the agricultural industries such as farming, forestry, fishing, and livestock. Related functions and products include improvement of soil properties and structure, compost making, and maintaining the freshness of fruits and vegetables in the areas of agronomy, forestry, and horticulture; filtering and purifying water in aquaculture; deodorizing livestock houses and as feed additives in livestock science; water purification of creeks, rivers, and lakes; etc.

8. For fuel Raw bamboo charcoal is directly burned only to utilize its heat for barbecuing and for warming fuel, and its ash after burning is used for specific purposes.

Source: Lin et al. (2005).

19Taiwan J For Sci 22(1): 15-28, 2007

bamboo charcoal. Therefore, with the 7 main uses of related bamboo charcoal products, we structured an evaluation hierarchy framework with 4 levels as shown in Fig. 1. The top level of the hierarchy is the evaluation objective: a bamboo charcoal quality evaluation indicator system. The second level includes the criteria: the 7 main uses. The third level (subcriteria) includes the 4 evaluation criteria with respect

to management sections: material supply, production technology, product quality, and marketing. The lowest level includes various importance evaluation indicators with respect to each criterion and subcriterion.

Step 2: A questionnaire with the evalua-tion hierarchy framework was submitted to arelated expert group to make all possible pairwise comparisons among the evaluation

Fig. 1. Basic hierarchical framework of this study.


criteria themselves at each level of the hierar-chy and among all evaluation indicators with respect to each evaluation criterion, to form a particular priority matrix using the relative importance scales, in order to measure the relative weights of each evaluation criterion. The importance scale by Saaty (1980) is shown in Table 2.

The related expert group was composed of 15 Taiwanese experts. Nine of these arescholars with PhDs who do related research on bamboo charcoal at universities and research institutes. The other six are manu-facturers of bamboo charcoal with extensive practical experience.

Step 3: The consistency ratios for each level and overall levels were computed to measure the reliability of the evaluation framework. The acceptable level of the consistency ratio using Saaty’s proposal was ≤ 0.1.

Step 4: A series of matrixes beginning at the second level and ending at the lowest level of the hierarchy was computed to obtain an overall measure of the relative importance of a particular evaluation indicator.

RESULTS AND DISCUSSION

The pairwise comparison results for each level in the hierarchy are shown in Tables 3~10 and are described in detail here.1. The consistency ratios of the overall

hierarchy had to be calculated separately for each use of bamboo charcoal due to the different numbers of evaluation indicators in level 4. The calculated results of the consistency ratio for each use are shown on the right side of Table 3. All consistency ratios were less than 0.l and were acceptable for the overall evaluation system according to Saaty’s proposal.

2. The left side of Table 3 shows the results of the priority weighting and sequence after pairwise comparisons of the 7 bamboo charcoal uses in level 2 in the hierarchy. The use for the human diet with a weighting value of 0.2307 with the sequence in the first position was judged to most require a bamboo charcoal quality evaluation framework. This means that the quality of related products of bamboo charcoal in the human diet should be evaluated first.

Table 2. Description of pairwise comparison scales of importance Intensity of Definition Explanation importance 1 Equal importance Two activities contribute equally to the objective 3 Weak importance of one over Experience and judgment slightly favor one activity another over another 5 Essential or strong importance Experience and judgment strongly favor one activity over another 7 Very strong or demonstrated An activity is very strongly favored over another; importance its dominance is demonstrated in practice 9 Absolute importance The evidence favoring one activity over another is of the highest possible order of affirmation 2, 4, 6, 8 Intermediate values between For use when compromise is needed adjacent scale valuesSource: Satty (1980).

21Taiwan J For Sci 22(1): 15-28, 2007

Table 3. Weighted comparisons and sequence of 7 bamboo charcoal uses at level 2 in the hierarchy and their overall consistency ratio levels Use Priority weighting Sequence CIH† RIH† CRH†

1. For human diet 0.2307 1 0.22 4.15 0.052. For home healthcare 0.1413 4 0.26 3.81 0.073. For air purification 0.0986 6 0.24 3.66 0.074. For cosmetics and cleaning 0.1844 2 0.18 3.55 0.055. For crafts and ornaments 0.1796 3 0.19 3.70 0.056. For hi-tech material 0.0388 7 0.23 4.15 0.067. For agriculture 0.1264 5 0.28 3.53 0.08λmax

＊ = 7.6363; CI = 0.1061; CR = 0.0803 < 0.1.† CIH, consistency index of overall hierarchy; RIH, random consistency index of overall hierarchy;

CRH, consistency ratio of overall hierarchy (= CIH/RIH).＊ λmax, maximum eigenvalue of the priority matrix; CI, consistency index = (λmax－n) / (n－1), where

n = number of elements in the matrix; CR, consistency ratio (= CI/RI, RI, random consistency index by Saaty).

Table 4. Weighted comparisons and sequence of evaluation indicators (for the human diet)

Criteria Priority Evaluation indicators Priority Weighted

(Level 3) weighting (Level 4) weighting score Sequence a b a×bMaterial 0.5960 A1. bamboo species 0.3482 0.2075 1supply (1)* A2. age of the bamboo 0.1008 0.0601 5 A3. position in the bamboo culm 0.2470 0.1472 3 A4. elevation where bamboo was grown 0.3040 0.1812 2Production 0.1222 B1. kind of kiln used 0.2131 0.0260 9technology (4) B2. kind of heating energy used 0.3719 0.0454 6

B3. terminal carbonizing temperature 0.0783 0.0096 21 B4. moisture content of the bamboo 0.3367 0.0411 7 when put into the kilnProduct 0.1412 C1. specific surface area (BET) 0.0758 0.0107 18quality (2) C2. true density 0.1554 0.0219 10 C3. pH value 0.0776 0.0109 17 C4. rate of release in the far-infrared 0.0866 0.0122 15 C5. rate of release of negative ions 0.0689 0.0097 20

C6. adsorption capacity for solutions 0.0426 0.0060 24

C7. adsorption capacity for gases 0.0350 0.0049 25

C8. surface color 0.1106 0.0156 13

C9. sound when struck 0.1118 0.0158 12 C10. fixed carbon content 0.0719 0.0102 19 C11. degree of refining 0.0452 0.0064 23 C12. bulk density 0.0567 0.0080 22 C13. product stability 0.0335 0.0047 26


Table 5. Weighted comparisons and sequence of evaluation indicators (for home healthcare)


(Level 3) weighting (Level 4) weighting score Sequence a b a×bMaterial 0.4396 A1. bamboo species 0.5872 0.2581 1supply (1)* A2. age of the bamboo 0.4128 0.1815 2Production 0.1285 B1. terminal carbonizing temperature 0.4873 0.0139 16technology (4) B2. speed of carbonizing temperature 1.3762 0.0392 6 change B3. moisture content of the bamboo 1.8371 0.0523 5 when put into the kiln B4. yield rate 0.8116 0.0231 10Product 0.1361 C1. specific surface area (BET) 0.1456 0.0198 13quality (3) C2. true density 0.1648 0.0224 11 C3. electrical resistance 0.1087 0.0148 15 C4. rate of release of in the far-infrared 0.0449 0.0061 22 C5. rate of release of negative ions 0.0506 0.0069 21 C6. adsorption capacity for gases 0.0557 0.0076 19 C7. sound when struck 0.1382 0.0188 14 C8. fixed carbon content 0.0943 0.0128 18 C9. degree of refining 0.0552 0.0075 20 C10. bulk density 0.1001 0.0136 17 C11. dioxin content 0.0148 0.0020 23 C12. content of harmful heavy metals 0.0135 0.0018 25 C13. accordance with the relevant laws 0.0136 0.0019 24 for food and hygiene

Table 4. Weighted comparisons and sequence of evaluation indicators (for the human diet) (con’t.)


(Level 3) weighting (Level 4) weighting score Sequence a b a×bProduct 0.1412 C14. dioxin content 0.0102 0.0014 27quality (2) C15. content of harmful heavy metals 0.0093 0.0013 28 C16. accordance with relevant laws 0.0089 0.0013 29 for food and hygieneMarketing 0.1407 D1. packaging material 0.4859 0.0684 4 (3) D2. explanation of product use 0.2012 0.0283 8 D3. data of relevant measurements 0.1265 0.0178 11 D4. validity date of product 0.1057 0.0149 14 D5. registration of manufacturer 0.0807 0.0114 16* The sequence of priority weightings of level 3 in the hierarchy.

23Taiwan J For Sci 22(1): 15-28, 2007

Table 5. Weighted comparisons and sequence of evaluation indicators (for home healthcare) (con’t.)


(Level 3) weighting (Level 4) weighting score Sequence a b a×bMarketing 0.2958 D1. brand creation 0.3766 0.1114 3 (2) D2. packaging material 0.2696 0.0797 4 D3. explanation of product use 0.0849 0.0251 9 D4. data of relevant measurements 0.0733 0.0217 12 D5. validity date of product 0.1065 0.0315 7 D6. registration of manufacturer 0.0891 0.0264 8* The sequence of priority weightings of level 3 in the hierarchy.

Table 6. Weighted comparisons and sequence of evaluation indicators (for air purification)


(Level 3) weighting (Level 4) weighting score Sequence a b a×bMaterial 0.4905 A1. bamboo species 0.6538 0.3207 1supply (1)* A2. age of the bamboo 0.3462 0.1698 2Production 0.1546 B1. kind of kiln used 0.3514 0.0543 5technology (3) B2. speed of carbonizing temperature 0.1118 0.0173 12 change B3. moisture content of the bamboo 0.3448 0.0533 6 when put into the kiln B4. yield rate 0.1919 0.0297 9Product 0.1451 C1. specific surface area (BET) 0.1166 0.0169 13quality (4) C2. pH value 0.1907 0.0277 10 C3. rate of release in the far-infrared 0.1299 0.0189 11 C4. rate of release of negative ions 0.0977 0.0142 14 C5. adsorption capacity for solutions 0.0917 0.0133 15 C6. adsorption capacity for gases 0.0454 0.0066 20 C7. fixed carbon content 0.0917 0.0133 16 C8. degree of refining 0.0661 0.0096 18 C9. bulk density 0.0839 0.0122 17 C10. product stability 0.0478 0.0069 19 C11. dioxin content 0.0180 0.0026 22 C12. content of harmful heavy metals 0.0203 0.0029 21Marketing 0.2098 D1. brand creation 0.3951 0.0829 3 (2) D2. explanation of product use 0.2599 0.0545 4 D3. data of relevant measurements 0.1629 0.0342 8 D4. registration of manufacturer 0.1822 0.0382 7* The sequence of priority weightings of level 3 in the hierarchy.


Table 7. Weighted comparisons and sequence of evaluation indicators (for cosmetics and cleaning)


(Level 3) weighting (Level 4) weighting score Sequence a b a×bMaterial 0.4379 A1. age of the bamboo 0.4379 0.4379 1supply (1)*

Production 0.2338 B1. kind of kiln used 0.2668 0.0624 3technology (2) B2. yield rate 0.7332 0.1714 2Product 0.1790 C1. specific surface area (BET) 0.1363 0.0244 11quality (3) C2. pH value 0.0824 0.0147 14 C3. rate of release of negative ions 0.2041 0.0365 5 C4. adsorption capacity for solutions 0.1030 0.0184 12

C5. adsorption capacity for a gases 0.1567 0.0281 8

C6. degree of refining 0.1754 0.0314 7 C7. product stability 0.0821 0.0147 15 C8. dioxin content 0.0217 0.0039 16 C9. content of harmful heavy metals 0.0198 0.0036 17 C10. accordance with the relevant laws 0.0186 0.0033 18 for food and hygieneMarketing 0.1493 D1. brand creation 0.3016 0.0450 4 (4) D2. explanation of product use 0.1800 0.0269 9 D3. data of relevant measurements 0.1057 0.0158 13 D4. validity date of product 0.1738 0.0259 10 D5. registration of manufacturer 0.2390 0.0357 6* The sequence of priority weightings of level 3 in the hierarchy.

Table 8. Weighted comparisons and sequence of evaluation indicators (for crafts and ornaments)


(Level 3) weighting (Level 4) weighting score Sequence a b a×bMaterial 0.4848 A1. age of the bamboo 0.2305 0.1117 4supply (1)* A2. product origin (country) 0.4524 0.2193 1 A3. season harvested 0.3171 0.1537 2Production 0.2082 B1. kind of kiln used 0.2599 0.0541 8technology (2) B2. kind of heating energy used 0.5657 0.1178 3 B3. yield rate 0.1744 0.0363 10Product 0.1532 C1. sound when struck 0.5179 0.0794 5quality (4) C2. hardness 0.4821 0.0739 7Marketing 0.1538 D1. brand creation 0.2570 0.0395 9 (3) D2. packaging material 0.5154 0.0793 6 D3. data of relevant measurements 0.2276 0.0350 11* The sequence of priority weightings of level 3 in the hierarchy.

25Taiwan J For Sci 22(1): 15-28, 2007

Table 9. Weighted comparisons and sequence of evaluation indicators (for hi-tech material)


(Level 3) weighting (Level 4) weighting score Sequence a b a×bMaterial 0.5248 A1. bamboo species 0.2107 0.1106 3supply (1)* A2. age of the bamboo 0.1856 0.0974 4 A3. position in the bamboo culm 0.2127 0.1117 2 A4. elevation where bamboo was grown 0.3909 0.2052 1Production 0.1205 B1. kind of kiln used 0.3025 0.0364 9technology (3) B2. kind of heating energy used 0.5260 0.0634 7 B3. terminal carbonizing temperature 0.0827 0.0100 18 B4. speed of carbonizing temperature 0.0888 0.0107 15 changeProduct 0.1099 C1. pH value 0.1928 0.0212 12quality (4) C2. electrical resistance 0.0414 0.0046 24 C3. ratio of release in the far-infrared 0.0800 0.0088 19 C4. adsorption capacity for solutions 0.0971 0.0107 16 C5. adsorption capacity for gases 0.0796 0.0087 20 C6. sound when struck 0.1393 0.0153 13 C7. fixed carbon content 0.0515 0.0057 21 C8. degree of refining 0.0473 0.0052 23 C9. bulk density 0.0910 0.0100 17 C10. product stability 0.0479 0.0053 22 C11. calorific value 0.1006 0.0111 14 C12. dioxin content 0.0160 0.0018 25 C13. content of harmful heavy metals 0.0154 0.0017 26Marketing 0.2448 D1. brand creation 0.3084 0.0755 5 (2) D2. packaging material 0.3050 0.0747 6 D3. explanation of product use 0.1392 0.0341 10 D4. data of relevant measurements 0.0877 0.0215 11 D5. registration of manufacturer 0.1597 0.0391 8* The sequence of priority weightings of level 3 in the hierarchy.

This result is the same as that of the Delphi technique shown by Lin et al. (2005). The second important use evaluation was for cosmetics and cleaning with a weighting value of 0.1884. The uses for crafts and ornaments, home healthcare, agriculture, air purification, and hi-tech material had relatively lower weighting values of 0.1796, 0.1413, 0.1264, 0.0986, and 0.0388, respectively. The evaluated importance for

hi-tech materials was considered the lowest, which infers that there are huge differences in the essential qualities required of bamboo charcoal among the extensive range of uses in various hi-tech industries. Hi-tech industries should research and evaluate other suitable characters of bamboo charcoal which correspond to their own industry quality requirements.

3. The results of the priority weighting and


sequence after the pairwise comparisons of the 4 evaluation criteria of management sections in level 3 of the hierarchy with respect to use are shown on the left side of Tables 4~10. The sequence results of the priority weightings for uses showed that air purification, hi-tech material, and agriculture had similar results, while material supply > marketing > production technology > product quality. Although the priority weightings of the other 4 uses had different sequence results, the criterion, material supply, was always shown to be the most important with the highest weighting value. This means that material supply was regarded as the most important evaluation criteria in the management sections by Taiwanese experts. This is the so-called general “product quality”, and

in this evaluation framework, it was only one part of the overall dimensions in the management section, so it was not the most important evaluation criterion to be considered. However, it is interesting and worthy of further to study.

4. The results of the priority weighting and sequence of the important evaluation indicators in level 4 of the hierarchy with respect to the criteria for each use and their weighted scores are shown on the right side of Tables 4~10. The sequences of the weighted scores for each evaluation indicator exhibited large differences for each use of bamboo charcoal because the numbers of evaluation indicators were not identical. For example, the use for the human diet which has direct and close effects on human health, required the

Table 10. Weighted comparisons and sequence of evaluation indicators (for agriculture)


(Level 3) weighting (Level 4) weighting score Sequence a b a×bMaterial 0.3775 A1. product origin (country) 0.3775 0.3775 1supply (1)*

Production 0.2132 B1. terminal carbonizing temperature 0.1501 0.0320 7technology (3) B2. speed of carbonizing temperature 0.2036 0.0434 5 change B3. moisture content of the bamboo 0.4553 0.0971 3 when put into the kiln B4. yield rate 0.1910 0.0407 6Product 0.1685 C1. specific surface area (BET) 0.1078 0.0182 11quality (4) C2. true density 0.2750 0.0463 4 C3. pH value 0.1316 0.0222 10 C4. fixed carbon content 0.1897 0.0320 8 C5. bulk density 0.1645 0.0277 9 C6. product stability 0.1058 0.0178 12 C7. content of harmful heavy metals 0.0256 0.0043 13Marketing 0.2407 D1. data of relevant measurements 0.2407 0.2407 2 (2)* The sequence of priority weightings of level 3 in the hierarchy.

27Taiwan J For Sci 22(1): 15-28, 2007

greatest number of importance indicators, and the use for crafts and ornaments which has no direct influence on human health, required the fewest importance indicators. It is not necessary to use the exact same evaluation dimensions and indicators to evaluate the product quality of bamboo charcoal for all its uses. Therefore, the priority weighting and sequence of each important evaluation indicator were dependent on the uses to which the bamboo charcoal is intended.

CONCLUSIONS

The quality of new products has a significant influence on the market success and profitability of manufacturers. Therefore, in order to realize the great potential for bamboo charcoal in the future, it is necessary to develop a quality evaluation mechanism for the production process, which will also provide good safety protection for consumers. This study applied the AHP to conduct a 4-level hierarchical framework for bamboo charcoal quality evaluation and to produce clearly relative importance sequences for each evaluation indicator with respect to the evaluated levels by processing a series of pairwise comparisons. For quality evaluation of the related products of bamboo charcoal, the evaluation dimensions were determined for the use first, then for the management sections, which included material supply, production technology, product quality, and marketing, and last for the various evaluation indicators dependent on each management section. The so-called general “product quality” in this evaluation framework is only one part of the overall picture. The analyzed results showed that use for the human diet was regarded as most in need of evaluation among the related uses of bamboo charcoal

products and it had the greatest number of important evaluation indicators; “material supply” was regarded as the most important evaluation criteria in the management sections with respect to each use of bamboo charcoal; and the number of importance evaluation indicators and their priorities greatly differed depending on the use. It is not necessary to use the exact same evaluation dimensions and indicators to evaluate product quality of bamboo charcoal for all of its uses. The results of this study offer a realistic reference framework for the establishment of bamboo charcoal quality evaluation.

ACKNOWLEDGEMENTS

The authors thank the Taiwan Forestry Research Institute for financial support through grant 94-AS-11.2.2-FI-G4(03). We also thank the 15 experts in this study for their support by replying to the questionnaires.

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