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The Impact of Inventory Parameters on Supply Chain Performance

산업공학과 제조통합자동화 실험실

2001.8.14 화발표 : 김해중

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The impact of inventory and flow planning parameters on supply chain performance

:An exploratory study

Ram Ganeshan, Tonya Boone, School of Business, College of William and Mary, Williamsburg, USA

Alan J. Stenger.Department of Business Logistics, Penn State University. USA

<Int. J. Production Economics 71 (2001) 111~118>

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Contents

Inventory parameters 설정

가설 설정

Simulation 을 통한 가설 검정

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Introduction

Research in Inventory Determining optimal inventory policies Positioning of inventory in the supply chain Analyzing the costs and benefits of technology and information

sharing Inventory-related advantages of product postponement

Objectives of studyImpact of selected inventory parameters

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Inventory planning parameters

i) Forecast methodology - Forecast error

ii) The mode of communication between echelons

- DRP(Distribution Resource Planning)

- ROP(Reorder Point)

iii) The planning frequency - How open the product or material requirements are re-computed

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Supply chain performance parameters

i) Observed service level - proportion of demand satisfied at the DCs from inventory

- Overall service level: volume-weighted average of each service level

ii) Supply chain cycle time

- the time spent by the product as raw material, WIP, or a finished good

- The time spent as inventory and the time spent in transit

iii) Return on investment - Profit contribution as the proportion of the total investment

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Hypothesis(1/3)

Impact of forecast error or methodology Before : De Bodt, Van Wassenhove

not supply chain, but a single site in the network

First hypothesis

Null: The forecast errors have no effect on cycle time and service levels

Alternative: Increasing forecast errors will increase the cycle time and decrease observed service levels.

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Hypothesis(2/3)

Impact of flow planning methodology DRP procedure gives the higher level of visibility in planning

product requirements DRP plans for the exact distribution needs

Second hypothesis

Null: The DRP and the ROP methodology have the same effect on the observed service level in the supply chain

Alternative: The DRP methodology achieves a higher level of observed service level than the ROP in the supply chain.

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Hypothesis(3/3)

Impact of replanning frequency Before : Sridharan, Berry

increasing replanning frequency -> decreasing stability

not supply chain, but a horizon MRP(one site)

Third hypothesis

Null: The replanning frequency has no effect on the cycle time or the service level

Alternative: A decrease in replanning frequency will increase cycle time and decrease observed service level

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Methodology

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Case study and network design

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Simulation

Forecast demand DCj, time period t

XFjt = XSjt + є

ii) Output

- Service level

- Inventory level

Forecast error

- normally distributed ~(θ,σ2)- σ2 =aAjb Aj: average period sales at DCj

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Experiment result

b=0.8

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Experiment result

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Conclusions

Forecasting errors and the re-planning frequency

service, ROI Cycle time

DRP service

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Discussion

분산분석의 한계 ( 검정만 가능 ) 을 넘어서는 평가방법 ?

예 ) 민감도 분석

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DRP(Distribution Resource Planning)

개념 Andre J. Martin 에 의해 고안된 (MRP 개념 창안자 ) 어떤 제품을 얼마만큼 언제 어디 (Source Site) 에서 어디 (Receiving Site) 로

이동시켜야 하는 지를 계획하는 것 .

목적 고객과 가장 가까운 곳에서 수요데이터를 얻고 , 수요를 예측하여 이를

생산계획의 수립에 빠르게 반영 운송 계획을 통한 유통망상 재고의 획기적인 감소

등장배경 과잉재고 재고고갈 낮은 고객서비스 과다한 물류비용 빠른 기업환경의 변화

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DRP

필요한 데이터 운송제품의 무게 , 부피 운송자원의 종류 , 용량 Site 월력 (Calendar) 운송 네트워크 운송 비용

MRP 와의 비교 MRP: 한 Site 에서 수요와 현재고에 대한 정보를 기준으로 생산량 /

구매량과 시점을 결정 , BOM, Routing

DRP: 여러 Site 상 (Distribution Network) 에서 각 Site 별로 수요 , 재고 , 생산량 / 구매량과 시점을 결정 , Bill of Distribution

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DRP 전개 예 (1/3)

고객의 수요를 예측 , 수급계획 수립

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DRP 전개 예 (2/3)

DRP Record- 서울대리점 , 부산대리점

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DRP 전개 예 (3/3)

DRP Record – 남한 물류센터

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