12) sistem produksi berbasis proyek

生産システム研究室 2003/12/10

1

Departemen Teknik Industri

SISTEM PRODUKSI BERBASIS PROYEK

Department of Industrial EngineeringInstitut Teknologi Bandung

Jalan Ganesha 10, Bandung 40132

TI3122 PERENCANAAN & PENGENDALIAN PRODUKSI

TI-3131 Perencanaan dan Pengendalian Produksi 2


Definition

Project can usually be defined as a series of related tasks directed toward a major output

The characteristics of a project:It has a specific goal and deadline It is unique or somewhat unfamiliar to the existing workIt contains complex interrelated tasks requiring specialized skillsIt is temporary but critical to the company


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A hierarchical view of the project environment

• .

Program 1 Program x Program n... ...

Project x1 Project x2 Projectxm-1... Project xm

Task x21 Task x22 Task x23 ...

Activityx221

Activityx222

Activityx223 ... Activity

x22q

Task x2p



A hierarchical view of the project environment

• Program: the term commonly used to denote very large and prolonged undertakings.

• Project: the term generally applied to time-phased efforts of much smaller scope and duration than programs. Programs are some time viewed as consisting of a set of project

• Task: an elemental content of a project. A project is normally composed of contiguous arrays of tasks that all contribute to the overall project goal

• Activity: the atom of a project. Activities are smaller than tasks


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Project management (PM)

• Project management (PM) is the process of managing, allocating, and timing resources in order to achieve a given objective in an expedient manner

• The objective may be in terms of time, monetary, or technical results

• PM is the process of achieving objectives by utilizing the combined capabilities of available resources

• PM represents a systematic execution of tasks needed to achieve project objectives



Projectmanagement

Planning

Organizing

Training

Risk management

Scheduling

Optimization

Contractmanagement

Resourcemanagement

Software toolsPerformance

control

Project design

Cost control

Multidimensionality of project management


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• PM covers the following basic functions: Planning, Organizing, Scheduling and Control

• Project planning provides the basis for the initiation, implementation, and termination of a project. It sets guidelines for specific project objectives, project structure, tasks, milestones, personnel, cost, equipment, performance, and problem resolutions

• Project organization specifies how to integrate the functions of the personnel involved in a project. Directing (which involves guiding and supervising the project personnel) is an important aspect of project organization




• Project scheduling is the time phased arrangement of project activities subject to precedence, time, and resource constraints in order to accomplish project objectives. It is often the core of project management efforts because it involves the assignment of time periods to specific tasks within the work schedule


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Project Planning1. Setting goals

2. Defining the project3. Tying needs into timed

project activities4. Orginizing the team

Project scheduling1. Tying resources (people, money,

supplies) to specific activities2. Relating activities to each other

3. Updating and revising on regularbasis

Project controlling1. Monitoring resource, costs,

quality, budgets2. Revising and changing plans

3. Shifting resources to meet time,cost, and quality demands

Before project

Start of the project

During project

ToolsTime and cost estimates

Budget, Cash flowPersonnel

Material abilityEngineering diagram

ToolsGantt Chart, CPM,

PERTCash flow schedules

Tools PERT charts

Reports describing1. budget by department

2. delayed activities3. slack activities4.quality of work

completed



The project of manufacturing

• In a large organization, the manufacturing system may be configured as a multi-project endeavor

• The following figure shows the typical components of a manufacturing enterprise organized as a project

• The project starts with a conceptualization of a product and needs some of distinct tasks for getting the product to the market


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IdeaFeasibility

study

Marketsurvey

Cost

Technologyassessment

Processplanning

Financing

Systemsintegration

Qualityspecs

Training

Operationsplanning

Facilities

Production

Schedule



Project Management Technique:

1. Critical path method (CPM)was developed in 1957 by J.E. Kelly of Remington Randand M.R. Walker of duPont

2. Program Evaluation and review technique (PERT)was developed in 1958 by the Navy with Booz, Allen and Hamilton


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The framework of CPM and PERT

Basic steps:• Define the project and all its significant tasks or

activities• Develop the relationship among the activities. Decide

which activities must precede and which must follow others

• Draw the network connecting all of the activities• Assign time and cost estimates and required resources

to each activity• Compute the longest time path through the network.

This is called the critical path• Use the network to help plan, schedule, monitor and

control the project



The questions answered by CPM or PERT

• When will the entire project be completed?• What are the critical activities in the project, that

is, the ones that will delay the entire project if they are late?

• Which are the noncritical activities, that is, the ones that can run late without delaying the whole project’s completion?

• What is the probability that the project will be completed by a specific date?

• At any particular date, is the project on schedule, behind schedule, or ahead of schedule?


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The questions answered by CPM or PERT

• On any given date, is the money spent equal to, less than, or greater than the budgeted amount?

• Are there enough resources available to finish the project on time?

• If the project is to be finished in a shorter amount of time, what is the best way to accomplish this at the least cost?



Conventions

• Activities: a task that occurs between 2 events• Event arrows and nodes

• Activity-on-Arrow (AOA)Arrows are used to represent activities, while nodes represent starting and ending points of activities

• Activity-on-Node (AON)Nodes represent activities, while arrows represent precedence relationships


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Convention

.

Event

Name and Symbol Description

A point in time, usuallya completion date or astarting date

(node)

Activity

(arrow)

An activity or a certainamount of work required inthe project

Event 1 Event 2 Event 3Activity A Activity B

(network)

A sequence of activitieswith beginning andending events



Example 1

Activity Immediate predecessorA -

B -C AD B

1

3

2

4

A

B

C

D


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Example 2

Beginning event Ending event Activity1 2 1-21 3 1-32 4 2-43 4 3-43 5 3-54 6 4-65 6 5-6



Example 2

.

1

3

2 4

5

6


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Example 3

Activity Immediate Predecessor(s)A -B -C AD BE C, DF DG EH F



Example 3

.

1

3

2

4

5

6

7

A

B

C

D

E

F

G

H

1

2

3

Dummy

4

5

6

7

A

B

C

D

E

F

G

C

Dummy activity


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Critical Path Method (CPM)

CPM is to determine the following quantities for each activity

• ES: Earliest start time. All predecessor activities must be completed before an activity can be started. The ending time of the predecessor activities is the earliest time an activity can be started

• LS: Latest start time. All successor activities must be completed without delaying the entire project This is the latest time an activity can be started without delaying the entire project

• EF: Earliest finish. EF=ES+t• LF: Latest finish. LF=LS+t




• TS: Total slack time. TS is the amount of time an activity may be delayed from its ES without delaying the latest completion of the project. TS=LS-ES or TS=LF-EF

• FS: Free slack time. FS is the amount of time an activity may be delayed from its ES without delaying the starting time of any of its immediate successors

S(j): immediate successors of activity j

)()()()(

jEFiESMinjFSjSi

−⎭⎬⎫

⎩⎨⎧=

∈


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• The critical path is the group of activities in the project thathave a total slack time of zero. This path is critical because a delay in any activity along this path would delay the entire project

• The total project completion time is calculated by adding the time values of those activities on the critical path



Example 4

Activity Duration1-2 21-3 72-3 42-4 33-4 2

1

3

2

4

2

7

3

2

4


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Example 4

.

0

01

2

62

7

93

9

94

2

2

3

7

40

2

0

7

2

6

2

5

7

9

ES, EF

9

7

9

6

LS, LF

7

3

3

1

7

0



Example 4

Activity Duration ES EF LS LF TS1-2 2 0 2 1 3 11-3 7 0 7 0 7 02-3 4 2 6 3 7 12-4 3 2 5 6 9 43-4 2 7 9 7 9 0

• Determine free slack times for the respective activities.


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Program Evaluation and Review Technique (PERT)

One distinguishing PERT and CPM is the use of 3 activities time estimates for each activity in the PERT technique. Only one time factor is given for each activity in CPM. The time estimates are:

a=optimistic timeb=pessimistic timem=most likely timete=expected timev=variance of activity completion time




• The expected time of completion time for activity i

• The variance of completion time for activity i

• The variance of project completion time

64 bmate

++=

2

6⎟⎠⎞

⎜⎝⎛ −

=abvi

∑∈

=pathcriticali

ivV


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Activity a m b1-2 3 4 51-3 1 3 52-4 5 6 73-4 6 7 8

If the expected project completion time is 20 weeks and the project variance is 100 weeks, what is the probability that the project will be finished on or before Week 25?

t v

4 1/93 4/9

6 1/97 1/9



Gantt chart

• When the results of a CPM/PERT analysis are fitted to a calendar time, the project plan becomes a schedule

• The Gantt chart showing planned (or actual) progress of activities is one of the most widely used tools for presenting the schedule

• The horizontal axis indicates the time scale• The horizontal bars/lines represent activities


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Gantt chart

.

Activity

1-3

2-3

2-4

3-4

W1 W2 W3 W4 W5 W6 W7 W8 W9Duration

1-2 2 weeks

7 weeks

4 weeks

3 weeks

2 weeks



Gantt chart

The basic Gantt chart does not show the precedence relationships among activities but it can be modified by linking appropriate lines

Activity

B

C

D

E

W1 W2 W3 W4 W5 W6 W7 W8 W9Duration

A 2 weeks

7 weeks

4 weeks

3 weeks

2 weeks


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Crashing

• Additional resources can reduce activity time for certain activity within the project

• Although it can be expensive to shorten activity times, doing so might be worthwhile

• The questions are:What activities should be shortened?How much will this action cost?Will a reduction in the activity time in turn reduce the time needed to complete the entire project?

• The least expensive method of shortening the entire project should be determined



Cost-time Curves

Time Cost

8 weeks $3007 weeks $4006 weeks $600

Y-Axis

X-Axis

$300

6 days

$500

$600

7 days 8 days

$400

Time (weeks)

Cost


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Cost of reducing activity time

• The objective is to reduce the entire project completion time by a certain amount at the least cost

• If Mi = maximum reduction of time for activity iCi= additional cost associated with reducing activity

time for activity iKi= cost of reducing activity time by one time unit

for activity i i

ii M

CK =

i

ii M

CK =



Determining the least cost

Activity Duration M C K Critical1-2 2 1 $3001-3 7 4 $20002-3 4 2 $20002-4 3 2 $40003-4 2 1 $2000

1

3

2

4

2

7

3

2

4

$300$500$1000$2000$2000

Yes

YesNoNo

NoMin


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Determining the least cost

Activity 1-3 is to be shortened by 1 week in order to reduce the project completion time to 8 weeks

Note that any further reduction in activity time along the critical path would cause the critical path to include activities 1-2, 2-3 and 3-4.



Further Readings

• Badiru, A.B., 1996, Project management in manufacturing and high technology operations, John Wiley and Sons, Inc., New York

• Heizer, J. and Render, B., 1996, Production and operations management, Prentice Hall International Editions, New Jersey

12) sistem produksi berbasis proyek

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