아웃소싱을 고려한 제품군설계에 관한 최적화 연구

유재욱(Jaewook Yoo),양재영(Jae Young Yang) 한국경영과학회 2019 經營 科學 Vol.36 No.1

A make-or-buy (MOB) decision about some technical attributes in product design and development is the act of choosing between making them in-house or purchasing from an external supplier. In this study, the transaction cost approach is used to reflect the MOB decision to the product line design optimization problem. The problem including the MOB decision is formulated as a multi-objective function model to satisfy three aspects of interest in product design and development as well as a column-dropping rule is proposed as the solution approach. The proposed model and solution approach are illustrated with a tablet pc under multi-segment market, and the sensitivity analysis is performed to study how the proposed model and its solutions respond to the variation for the priority of the objective functions.

적응적 왜곡 거리 계산을 이용한 부화소 기반 영상 확대

유재욱(Jaewook Yoo),박대현(Daehyun Park),김윤(Yoon Kim),김만배(manbae Kim),정인범(Inbum Jung) 한국정보과학회 2007 한국정보과학회 학술발표논문집 Vol.34 No.1B

본 논문에서는 디지털 영상의 해상도를 부화소 기반의 새로운 적응적 선형보간법으로 변경하는 방법을 제안한다. 일반적 선형보간법에서 고정된 위치로 쓰이는 거리계수를 왜곡된 거리 계산에 의한 화소 가중치를 주는 방법으로 개선한다. 이를 계산하기 위하여 최소 평균 자승 에러(minimum mean square error, MMSE)를 이용한다. 원영상과의 차이를 최소화하는 왜곡 거리 계산을 위하여 이웃한 보간 화소와 왜곡거리를 참조하게 된다. 이를 사용하면 복잡도가 높지 않은 효과적인 화소 보간을 할 수 있고 실험 결과 일반적인 보간법과 비교할 때 PSNR(peak signal to noise ratio)과 주관적 화질 면에서 우수함을 알 수 있었다.

중앙창고 입지선정을 위한 회귀분석기반 해법

유재욱(Jaewook Yoo),이동주(Dongju Lee) 한국산업경영시스템학회 2009 한국산업경영시스템학회지 Vol.32 No.2

In continuous review inventory model, (Q, r) system, order quantity(Q) and reorder point(r) should be determined to calculate inventory-related cost that consists of setup, holding, and penalty costs. The procedure to obtain the exact value of Q and r is complex. In this paper, a regression analysis is proposed to get the approximate inventory-related cost without the determination of Q and r in the case that the standard deviation(σ) of the lead time demand is small or that the mean(μ) of the lead time demand is proportional to σ. To save inventory-related cost, central warehouses with (Q, r) system can be built. Central warehouse can provide some stores with products with the consideration of the tradeoff between inventory-related cost and transportation cost. The number and the location of central warehouses to cover all the stores are determined by a regression-based approach. The performance of the proposed approach is tested by using some computational experiments.

경쟁행위 요인과 기업성과 간의 관계에 대한 실증적 연구

유재욱(Jaewook Yoo) 한국인터넷전자상거래학회 2011 인터넷전자상거래연구 Vol.11 No.1

This study examines the relationships between competitive-behaviors attribute and firm performance in Korean life-insurance industry. The findings of a multiple regression analysis of ten-years sample of life-insurance companies in Korea represent that the action frequency has significant positive relations with new business rate whereas the response frequency of them has significant positive relations with persistent business rate. Inconsistent with the hypotheses, however both action- and response-speed did not reveal the positive relations with either of quantity or quality of firms performance. The present study contributes to an under-researched, yet very important area in competitive dynamics. In particular, the findings of this study imply that future study in competitive dynamics should adopt a dynamic approach than static approach in an empirical analysis. They are also valuable to practicing managers in life-insurance firms in Korea by adding their understanding of the ongoing competitive dynamics in the market.

마코프 프로세스와 역대 판매량 실적을 이용한 IT 제품 수명주기 예측 모델링에 관한 연구 -아이폰 사례-

유재욱(Jaewook Yoo) 한국산학기술학회 2021 한국산학기술학회논문지 Vol.22 No.10

오늘날 시장 환경에서 IT 제품의 수명주기는 매우 짧을 뿐만 아니라 한 기업이 개발한 두개 또는 세 개 세대 이상의 제품들이 출시 시점은 다르더라도 같은 시장 세그먼트에서 상당 기간 동안 겹쳐서 시장에 상존하는 상황이 빈번히 발생하고 있다. 본 연구에서는 이와 같이 제품수명주기가 짧고 한 기업이 여러 세대 제품군을 한 시장에 출시하는 시장 환경에서 마코프 프로세스를 이용한 제품수명주기를 예측하는 모델을 제시한다. 본 연구에서 제시한 모델을 실제 사례에 적용하기 위하여 애플의 과거 2007년 3분기부터 2018년 3분기까지 총 45개 분기의 14개 세대 아이폰들의 분기별 글로벌 판매량 데이터 수집하였고 본 연구의 모델이 제대로 적용되도록 세대제품별 판매량 데이터를 추정하였다. 본 연구의 모델의 타당성을 검증하기 위해서 10개의 테스트가 수행되었다. 모델의 성능을 보여주기 위하여 본 연구의 모델이 주는 제품수명주기 상태의 기대값과 실제값인 관측값의 차이를 관측값에 대한 백분율로 측정하였다. 아이폰 사례의 경우 본 연구가 제시한 마코프 프로세스를 이용한 제품수명주기 예측모델은 미래 아이폰의 제품수명주기 상태를 예측하는 성능이 94.28% 였다. In this study, we present a Markov model to predict the product life cycle in today"s market environment where the product life cycle is short, and a company releases multiple generation products in one market. To apply the model presented in this study to an actual case, we collected quarterly global sales data of 14 generations of iPhones. The data were collected from 45 quarters of Apple from the 3rd quarter of 2007 to the 3rd quarter of 2018 . The sales data of each generation product were estimated for proper application. Ten tests were conducted to verify the validity of the model. To demonstrate the model"s performance, we measure the difference between the expected value of the product life cycle state obtained by the model of this work and the actual value of the observation as a percentage of the observed value. In the case of the iPhone, the product life cycle prediction Markov model proposed by this study showed 94.28% performance in predicting the iPhone"s future product life cycle status.

아웃소싱 전략을 활용하는 두 단계 흐름생산라인에서 완료시간의 총합을 최소화하는 일정계획문제

유재욱(Jaewook Yoo),이익선(Ik Sun Lee) 한국경영과학회 2016 經營 科學 Vol.33 No.2

We treats a job scheduling in a 2-machine flow-shop problem with outsourcing strategy allowed. Jobs in the first machine are processed in-house or outsourced to the other companies. In this paper, all the considered jobs are determined to be in-house processed or outsourced. When a job is outsourced, then the firm should pay an outsourcing cost additionally. We want to minimize the sum of the outsourcing costs and the total completion times of finished jobs. In this paper, some solution properties are characterized, and then some heuristic algorithms and a branch-and-bound solution algorithm are derived. This paper evaluates finally the performance of the proposed algorithms during the numerical tests.

소프트웨어 제품라인의 출시 계획을 위한 최적해법

유재욱(Jaewook Yoo) 한국산업경영시스템학회 2012 한국산업경영시스템학회지 Vol.35 No.2

소프트웨어 개발에 있어서 소프트웨어를 시장에 출시하는 계획을 수립하는 것은 소프트웨어를 이루고 있는 기능들을 구현하는 데 제약이 되는 조건들(기술, 자원, 위험, 예산 등)을 만족하면서 계획된 출시기간에 이들 기능들을 할당하는 일이다. 이와 같이 소프트웨어 출시를 계획하는 것은 소프트웨어 제품라인에 대해서 고려할 때 더욱 복잡해진다. 본 연구에서는 소프트웨어 제품라인에 있어서 소프트웨어 출시 계획을 수립하기 위한 문제를 우선순위 제약하의 다수 0-1 배낭문제로 수리 모형화하고, 이를 풀기 위한 최적해법이 개발된다. 최적해법은 동적 계획법이 주가 되고, 문제의 크기를 줄이기 위하여 휴리스틱과 축소방법이 이용된다. Software release planning model of software product lines was formulated as a precedence-constrained multiple 0-1 knapsack problem. The purpose of the model was to maximize the total profit of an entire set of selected features in a software product line over a multi-release planning horizon. The solution approach is a dynamic programming procedure. Feasible solutions at each stage in dynamic programming are determined by using backward dynamic programming approach while dynamic programming for multi-release planning is forward approach. The pre-processing procedure with a heuristic and reduction algorithm was applied to the single-release problems corresponding to each stage in multi-release dynamic programming in order to reduce the problem size. The heuristic algorithm is used to find a lower bound to the problem. The reduction method makes use of the lower bound to fix a number of variables at either 0 or 1. Then the reduced problem can be solved easily by the dynamic programming approaches. These procedures keep on going until release t = T. A numerical example was developed to show how well the solution procedures in this research works on it. Future work in this area could include the development of a heuristic to obtain lower bounds closer to the optimal solution to the model in this article, as well as computational test of the heuristic algorithm and the exact solution approach developed in this paper. Also, more constraints reflecting the characteristics of software product lines may be added to the model. For instance, other resources such as multiple teams, each developing one product or a platform in a software product line could be added to the model.

군집 분석을 활용한 제품 플랫폼 설계를 위한 모듈 공용화

유재욱(Jaewook Yoo) 한국산업경영시스템학회 2014 한국산업경영시스템학회지 Vol.37 No.3

Platform-based product family design is recognized as an effective method to satisfy the mass customization which is a current market trend. In order to design platform-based product family successfully, it is the key work to define a good product platform, which is to identify the common modules that will be shared among the product family. In this paper the clustering analysis using dendrogram is proposed to capture the common modules of the platform. The clustering variables regarding both marketing and engineering sides are derived from the view point of top-down product development. A case study of a cordless drill/drive product family is presented to illustrate the feasibility and validity of the overall procedure developed in this research.

An Exact Solution Approach for Release Planning of Software Product Lines

유재욱(Jaewook Yoo) 한국산업경영시스템학회 2012 한국산업경영시스템학회 학술대회 Vol.2012 No.-

Software release planning in software development is to assign its features to releases in a specified planning horizon,satisfying technology, resource, risk, and budget constraints. The release planning problembecomes more complicated when the concept of software product lines (SPL) is considered. In this research, a precedence-constrained multiple 0-1 knapsack problem regarding SPL characteristics is formulated to maximize the objective function depending on the value of the release, the importance of stakeholders, the urgency of a feature and its value to stakeholders. As the optimization solution approach, dynamic programming model is developed to solve the precedence-constrained multiple 0-1 knapsack problem as well as a heuristic and reduction algorithm are applied to reduce the size of the problem at each stage.

마코프 프로세스를 활용한 다세대 제품군 전략을 위한 제품생명주기 예측 모델

유재욱(Jaewook Yoo) 한국경영과학회 2021 經營 科學 Vol.38 No.2