MTS-MTO 일렬 생산 시스템에서 수요/생산 통제 전략 및 재고 할당 전략의 통합적 구현

Abstract

This work deals with the issues of MTO product demand and parts production and of parts external demand control, arising in manufacturers which have the facilities to produce products in the make-to-order method and the facilities to produce parts in the make-to-stock method. For efficient operation of the study model of this work, the strategic decision-making about MTO product demand and parts production control, parts inventory rationing should be achieved. This work model takes into consideration two-step production, make-to-order production method, two demand control items, two demand classes (MTO product admission and parts demand), delay inventory at the time of inventory shortage and the process of opportunity loss, demand control and inventory production policy (the function of system state variables and probable production time). This work was intended to investigate MTO product admission, and parts demand and production control in MTS-MTO serial production system and suggest the optimal policy and heuristic. It tried to suggest a simulation model implemented with C language and dealt with the study subjects as follows: First, the study model was based on Markov decision problems (MDP), and numerical analysis was conducted to look into the characteristics of the optimal strategy for product admission control, and parts production and parts external demand control. In addition, this work proposed a heuristic control strategy applicable to non-MDP model, and compared and analyzed the optimal strategy and heuristic one. Secondly, Through numerical analysis, it proposed a demand and production control strategy to be considered in the system operation level. And, sensitivity analysis was conducted from the perspective of time and profit/cost parameters. Thirdly, through simulation research, this work analyzed how the control policy on production time and on volatility of demand process affect corporate profits and how the control strategy in accordance with the changes of management environment affects corporate profits. This study results are presented as follows: First, it was found that the heuristic 1 being executing in the integrated perspective of product/parts production facility was averagely better policy than the heuristic 2 being executed in an individual perspective. In particular, it was found that when MTO product production speed was faster than parts production speed, the policy was more efficient. Secondly, through results of the numerical test on MTO product demand and parts demand/production control for the heuristic 1 and heuristic 2, it was able to gain the results of policy changes in a parameter perspective. Thirdly, on the assumption that parts/product production time and demand distribution follows normal distribution, this work analyzed how volatility of probability process affects the changes in revenues (, ) per MTO product (parts) unit. As a result, it was found that the larger the volatility of MTO product arrival time interval was, and the more increased, the more negatively corporate profits were affected, and that, in the condition that parts demand was constant, the larger MTO product arrival time interval was, and the more increased, the more positively corporate profits was affected. Fourthly, this work looked into how the control strategy in accordance with the changes of management environment affects profits. In the condition that corporate environment was changed, the profits through the changes in the control strategy were compared with those through the non-change in the control strategy. As a result, the profits through the changes in the control strategy in accordance with the changes of management environment were higher on average than those through the non-change in the control strategy. In the global society, companies' competition with one another gets fiercer. In the circumstance, companies struggle to enhance their competition and create brand value. This work is a study model suitable for most Korean manufacturers which relatively lack the activities necessary to establish sustainable management strategies compared to their efforts to secure business competitiveness. Through simulation research, this work is intended to suggest insight to establish the policy on inventory rationing and admission/production control that manufacturers actually face.;본 논문은 고객 주문에 특화된 제품을 생산(make-to-order)하는 시설과 계획 생산(make-to-stock) 방식으로 부품을 생산하는 시설을 보유하고 있는 제조 기업에서 MTO제품 수요 및 부품 생산과 부품 외부 수요 통제 문제를 다루고 있다. 본 논문의 연구모형의 효율적 운영을 위해서는 MTO제품 수요 및 부품 생산 통제, 부품 재고 할당(inventory rationing)에 대한 전략적 의사 결정이 이루어져야 한다. 본 연구 모형은 두 단계 생산, 계획-주문 혼합 생산 방식, 두 개의 수요 통제 품목, 두 수요 계층(MTO제품 수요와 부품 수요), 재고 부족 시 지연재고와 기회 손실 처리, 수요 통제 및 재고 생산 정책(시스템 상태 변수의 함수와 확률적인 생산 시간)을 고려한 모형으로 분류 할 수 있다. 본 논문에서 MTS-MTO 일렬 생산 시스템에서의 MTO제품 수요와 부품 수요 및 생산 통제를 연구하고 최적 정책과 휴리스틱을 제시한다. C언어를 이용한 시뮬레이션 모형을 제시하고 다음과 같은 연구주제를 다루었다. 첫째, 연구모형을 마코프 의사 결정 문제(Markov decision problem, MDP)로 모형화 하고 수치 분석을 통해 MTO제품 수요 통제와 부품 생산 및 부품 외부 수요 통제를 위한 최적 전략의 특성을 파악하였다. 또한, 비 MDP 모형에 적용 가능한 휴리스틱 통제 전략을 제안하고 최적 정책과 휴리스틱을 비교하여 분석하였다. 둘째, 수치 분석을 통해 시스템 운영 수준에서 고려될 수 있는 수요 및 생산 통제 정책을 제시하였다. 시간과 수익/비용 파라미터 관점에서 민감도 분석을 수행하였다. 셋째, 시뮬레이션 연구를 통하여 생산 시간과 수요 프로세스의 변동성이 기업의 수익성에 미치는 영향과 경영 환경의 변화에 따른 통제 전략이 기업의 수익성에 미치는 영향에 대하여 분석하였다. 본 논문에서는 시뮬레이션 연구를 통하여 위에서 제시한 연구 주제에 대한 다양한 수치 실험 결과를 도출하였으며, 실제 제조 기업이 당면한 재고 할당문제 및 수요/생산 통제 정책 수립에 도움을 줄 수 있는 통찰력을 제시하였다. 글로벌 사회에서 기업들의 경쟁은 날이 갈수록 치열해 지고 있다. 이러한 환경 속에서 기업들은 기업의 경쟁력 강화와 브랜드 가치 창출에 힘쓰고 있다. 본 논문은 시장에서의 사업 경쟁력 확보 노력에 비해서 지속 가능한 경영 전략 구축에 필요한 활동에는 상대적으로 부족한 대다수 우리나라 제조 기업에 적합한 연구모형이라고 할 수 있다.