평면적 저장 위치 할당 문제에 대한 유전자 알고리즘

박창규(Changkyu Park),서준용(Junyong Seo) 대한산업공학회 2009 대한산업공학회지 Vol.35 No.2

Simulation Experimental Analysis on a Seat Inventory Control Problem for Sequential Multiple Flights with Customer Choice Behavior

박창규(Changkyu Park),서준용(Junyong Seo),홍윤숙(Yunsook Hong) 한국경영과학회 2013 經營 科學 Vol.30 No.1

We conduct the future studies suggested by Park and Seo [3]. They considered a seat inventory control problem in which flights depart sequentially during a similar time-interval and passengers purchase available seats depending on individual customer choice behavior. Customer choice behavior can lead to one among a horizontal shift, a diversion-up, and a booking loss when a desired fare class is unavailable. We investigate how seat availability calculation method, booking limit control mechanism, seat inventory capacity, number of booking class, type of seat demand influence on revenues in an airline industry through thorough computer simulation experiments.

Purchase dependent partial backordering inventory model

Changkyu Park(박창규) 대한산업공학회 2015 대한산업공학회 춘계학술대회논문집 Vol.2015 No.4

Purchase dependence is a frequent phenomenon in retail shops and is characterized by the purchase of certain items together due to their unknown interior associations. Although this concept has been significantly examined in the marketing field (e.g, market basket analysis),it has largely remained unaddressed in operations management Since purchase dependence is an important factor in designing inventory replenishment policies, this paper demonstrates the means of applying it to the partial backordering inventory model.

An EOQ Approach to Purchase-Dependent Demands When Unmet Orders Are Canceled

Changkyu Park(박창규),Minji Sung(성민지) 한국경영과학회 2021 韓國經營科學會誌 Vol.46 No.1

We investigate the inventory models for purchase-dependent demands in the case in which customer orders are canceled if all items in the order are not delivered all at once. The exact objective function of an inventory model is quite difficult to derive when purchase dependence exists. Determining the optimal order quantity and reorder point is also a challenging task. Thus, we first analyze the properties of optimal solutions using an EOQ model to derive the condition of optimal solution. Then, we extend the condition to continuous review models. Through computer simulations, we demonstrate the usefulness of this study’s approach. In general, the inventory model, which considers the purchase dependence, reduces the loss of sales by holding more inventories through more frequent orders, thus eventually minimizing the total cost.

구매종속성이 존재하는 상황에서 부분 부재고 EOQ 모형에 대한 고찰

박창규(Changkyu Park) 한국경영과학회 2015 經營 科學 Vol.32 No.1

Purchase dependence is a frequent phenomenon in retail shops and is characterized by the purchase of certain items together due to their unknown interior associations. Although this concept has been significantly examined in the marketing field (e.g. market basket analysis), it has largely remained unaddressed in operations management. Since purchase dependence is an important factor in designing inventory replenishment policies, this paper demonstrates the means of applying it to the partial backordering inventory model. Through computational analyses, this paper compares the performance of inventory models that either consider or ignore purchase dependence; the results demonstrate that inventory models that ignore purchase dependence incur more average cost per unit time than the model that considers purchase dependence, and the impact of purchase dependence can increase in significance as the item set becomes more closely correlated with regard to order demand.

구매종속성이 재고관리에 미치는 영향

박창규(Changkyu Park),서준용(Junyong Seo) 한국경영과학회 2013 經營 科學 Vol.30 No.3

The purpose of this paper is to illustrate the importance of identifying and considering ‘purchase dependence’ when purchase of an item is dependent on availability of other items demanded in the same order. This paper is the first study to develop an inventory model for purchase?dependent inventory systems. Through simulation experiments, we demonstrate that the developed inventory model incurs less inventory operations cost than other inventory models that ignore purchase dependence. For empirical validation of the developed inventory model, the actual inventory data at the Hyundai Engine Europe Service Center is used. We explain the process of identifying purchase dependencies among items through a data mining technique. The empirical study results in similar results to the simulation experiment, demonstrating that the developed inventory model is applicable to real situations.

Purchase dependent partial backordering inventory model

Changkyu Park(박창규) 한국경영과학회 2015 한국경영과학회 학술대회논문집 Vol.2015 No.4

Purchase dependence is a frequent phenomenon in retail shops and is characterized by the purchase of certain items together due to their unknown interior associations. Although this concept has been significantly examined in the marketing field (e.g, market basket analysis),it has largely remained unaddressed in operations management Since purchase dependence is an important factor in designing inventory replenishment policies, this paper demonstrates the means of applying it to the partial backordering inventory model.

구매 종속성을 고려한 부분 부재고 재고모형

박창규(Changkyu Park) 한국경영과학회 2014 한국경영과학회지 Vol.39 No.1

Retail shops often experience purchase dependence in which some items are purchased together by customers due to their unknown interior associations. This paper develops an inventory model considering partial backordering under purchase dependence and compares the performance of the inventory model that ignores purchase dependence. Computational analyses show that purchase dependence should be incorporated as an important factor of inventory replenishment policy because the impact of purchase dependence can be more significant as the lost portion of the unmet demand orders increases and the item set is more correlated in terms of order demand.

Approximate Calculation of Order Fill Rate under Purchase Dependence

Changkyu Park(박창규) 한국산업경영시스템학회 2017 한국산업경영시스템학회지 Vol.40 No.4

For the competitive business environment under purchase dependence, this paper proposes a new approximate calculation of order fill rate which is a probability of satisfying a customer order immediately using the existing inventory. Purchase dependence is different to demand dependence. Purchase dependence treats the purchase behavior of customers, while demand dependence considers demand correlation between items, between regions, or over time. Purchase dependence can be observed in such areas as marketing, manufacturing systems, and distribution systems. Traditional computational methods have a difficulty of the curse of dimensionality for the large cases, when deriving the stationary joint distribution which is utilized to calculate the order fill rate. In order to escape the curse of dimensionality and protect the solution from diverging for the large cases, we develop a greedy iterative search algorithm based on the Gauss-Seidel method. We show that the greedy iterative search algorithm is a dependable algorithm to derive the stationary joint distribution of on-hand inventories in the retailer system by conducting a comparison analysis of a greedy iterative search algorithm with the simulation. In addition, we present some managerial insights such as : (1) The upper bound of order fill rate can be calculated by the one-item pure system, while the lower bound can be provided by the pure system that consists of all items; (2) As the degree of purchase dependence declines while other conditions remain same, it is observed that the difference between the lower and upper bounds reduces, the order fill rate increases, and the order fill rate gets closer to the upper bound.

구매종속성이 존재하는 상황에서 주문충족율을 계산하는 근사법에 관한 연구

박창규(Changkyu Park),서준용(Junyong Seo) 한국경영과학회 2016 韓國經營科學會誌 Vol.41 No.2

This paper proposes a new approximate approach to calculate the order fill rate and the probability of filling an entire customer order immediately from the shelf in a business environment under purchase dependence characterized by customer purchase patterns observed in such areas as marketing, manufacturing systems, and distribution systems. The new approximate approach divides customer orders into item orders and calculates fill rates of all order types to approximate the order fill rate. We develop a greed iterative search algorithm (GISA) based on the Gauss-Seidel method to avoid dimensionality and prevent the solution divergence for larger instances. Through the computational analysis that compares the GISA with the simulation, we demonstrate that the GISA is a dependable algorithm for deriving the stationary joint distribution of on-hand inventories in the type-K pure system. We also present some managerial insights.