이산 시간을 고려한 시스템의 교체와 수리 비용 최적화 연구

이진표(Jinpyo Lee) 한국산업경영시스템학회 2020 한국산업경영시스템학회지 Vol.43 No.1

Systems such as database and socal network systems have been broadly used, and their unexpected failure, with great losses and sometimes a social confusion, has received attention in recent years. Therefore, it is an important issue to find optimal maintenance plans for such kind of systems from the points of system reliability and maintaining cost. However, it is difficult to maintain a system during its working cycle, since stopping works might incur users some troubles. From the above viewpoint, this paper discusses minimal repair maintenance policy with periodic replacement, while considering the random working cycles. The random working cycle and periodic replacement policies with minimal repair has been discussed in traditional literatures by usually analyzing cases for the nonstopping works. However, maintenance can be more conveniently done at discrete time and even during the working cycle in real applications. So, we propose that periodic replacement is planned at discrete times while considering the random working cycle, and moreover provide a model in which system, with a minimal repair at failures between replacements, is replaced at the minimum of discrete times KT and random cycles Y. The average cost rate model is used to determine the optimal number of periodic replacement.

Past, Present and Future of Players in Supply Chain of Healthcare Product

Lee, Jinpyo(이진표) 한국SCM학회 2009 한국SCM학회지 Vol.9 No.2

DEA 기법을 활용한 국내 미술관의 소셜 네트워크 서비스 활용도 비교 분석

이진표(Lee, Jinpyo),김승범(Kim, Seungbeom),최병철(Choi, Byungchul) 한국전시산업융합연구원 2020 한국과학예술융합학회 Vol.38 No.1

본 연구는 투입자원 대비 산출물의 효율성을 측정하는 경영기법인 Data Envelopment Analysis (자료포괄분석; 자료포락분석) 기법을 사용하여 대표적인 문화예술기관인 미술관의 소셜 네트워크 서비스 (Social Network Services) 운영 효율성을 비교분석함으로, 최근 문화예술계에서 각광받는 커뮤니케이션 도구인 SNS의 활용방안에 대하여 논의함을 그 목적으로 하고 있다. 비교분석 대상 미술관으로는 국립현대미술관, 서울시립미술관, 대림미술관 (디뮤지엄 포함), 삼성미술관 (Leeum), 소마미술관 총 다섯 개의 국립 및 사립 미술관들이 선정되었고, SNS의 경우 최근 가장 널리 사용되고 있는 인스타그램 (Instagram)의 활용도를 비교분석하였다. 분석 결과, 국립현대미술관과 대림미술관이 투입자원 대비 가장 많은 (1) 팔로워 수와 (2)해시태크 수를 보이며 인스타그램을 가장 효율적으로 활용하고 있는 미술관으로 나타났으며, 삼성미술관, 서울시립미술관, 소마미술관이 순서대로 그 뒤를 이었다. 사립과 국립미술관과의 뚜렷한 차이는 발견되지 않았으나, 콘텐츠의 효율적인 활용이라는 측면에서는 분명한 차이가 있음을 보여줬다. 아울러, 운영효율성의 순위가 인스타그램의 활용기간과도 반드시 일치하지 않음을 보여주었는데, 이는 콘텐츠의 양을 넘어서, 보다 전략적인 접근법이 필요함을 시사한다고 볼 수 있다. 기존의 문화예술기관의 SNS활동에 관한 연구가, SNS의 활용 중요성, 활용현황, 활용방안 등에 주안점을 두고 진행되어온데 반해, 본 연구는 한 단계 더 나아가서, SNS활용의 효율성을 검증한다는 면에서 그 의미가 크다고 볼 수 있다. This study explores the question of how efficiently Korean art museums utilize social network services (SNS) as an instrument to communicate with society and audience. Using Data Envelopment Analysis (DEA) with specific focus on Instagram, we estimate and compare utilization efficiency of Instagram of five Korean art museums in Seoul (National Museum of Modern and Contemporary Art, Seoul Museum of Art, Daelim Museum, Samsung Museum of Art, and Seoul Olympic Museum of Arts). We find that the difference exits in utilization efficiency of Instagram among those five art museums. While no systematic difference between public and private art museums is found, we find that the time and experience in using SNS does not guarantee the utilization efficiency. This findings imply that strategic consideration is requested in utilizing SNS. While previous studies on utilization of SNS in art museum have mainly focused on the importance and utilization methods of SNS, our study makes a contribution to the field by providing the efficiency perspective of SNS in managing art museum.

USN 미들웨어 기반의 u-Healthcare 모니터링 시스템 구현 및 성능평가

이진표(Jinpyo Lee),김의창(Yeichang Kim) 한국인터넷전자상거래학회 2010 인터넷전자상거래연구 Vol.10 No.3

This paper shows the implementation of USN middleware for applying data obtained from heterogeneous sensor nodes to u-Healthcare system. Actually, USN middleware allows abstraction of heterogeneous sensor node, data filtering, event processing and Context-Awareness. USN middleware presented in this paper can maximize the extensibility and the usability of the system. It proceeds like this : 1) obtaining data through environment & bio sensor in sensor network of various environments, 2) transmitting the obtained data to middleware through gateway, 3) transforming the data into the standard format by abstraction, 4) and storing the data in DB of server. Eventually, the data stored in server can be monitored in real time by the user. In this paper, we estimated the usability of u-Healthcare monitoring system through analysing its efficiency. We also tried to improve the efficiency of the system by minimizing the system overhead and response time, analyzed the Memory Usage, CPU Usage, Threads and Classes Usage.

경미한 고장을 수반하는 시스템에 대한 노화 및 예방적 교체 정책

이진표,Lee, Jinpyo 한국산업경영시스템학회 2022 한국산업경영시스템학회지 Vol.45 No.3

The purpose of this study was to propose useful suggestion by analyzing preventive replacement policy under which there are minor and major failure. Here, major failure is defined as the failure of system which causes the system to stop working, however, the minor failure is defined as the situation in which the system is working but there exists inconvenience for the user to experience the degradation of performance. For this purpose, we formulated an expected cost rate as a function of periodic replacement time and the number of system update cycles. Then, using the probability and differentiation theory, we analyzed the cost rate function to find the optimal points for periodic replacement time and the number of system update cycles. Also, we present a numerical example to show how to apply our model to the real and practical situation in which even under the minor failure, the user of system is not willing to replace or repair the system immediately, instead he/she is willing to defer the repair or replacement until the periodic or preventive replacement time. Optimal preventive replacement timing using two variables, which are periodic replacement time and the number of system update cycles, is provided and the effects of those variables on the cost are analyzed.

Application of the BMORE Plot to Analyze Simulation Output Data with Bivariate Performance Measures

이미림,이진표,박민재,Lee, Mi Lim,Lee, Jinpyo,Park, Minjae The Korea Society for Simulation 2020 한국시뮬레이션학회 논문지 Vol.29 No.2

Bivariate measure of risk and error(BMORE) plot is originally designed to depict bivariate output data and related statistics obtained from a stochastic simulation such as sample mean, median, outliers, and a boundary of a certain percentile of simulation data. When compared to the static numbers, the plot has a big advantage in visualization that enables scholars and practitioners to understand the potential variability and risk in the simulation data. In this study, beyond just the construction of the plot to depict the variability of a certain system, we add a chance constraint to the plot and apply it for decision making such as checking the feasibility of systems, comparing performances of the systems on statistical background, and also analyzing the sensitivity of the problem parameters. In order to demonstrate an application of the plot, we employ an inventory management problem as an example. However, the techniques and algorithms suggested in this paper can be applied to any other problems comparing systems on bivariate performance measures with simulation/experiment results. BMORE(Bivariate measure of risk and error) 도표는 본래 확률적 시뮬레이션에서의 이변량 성과 데이터와, 그와 관계된 표본 평균, 중앙값, 이상점, 특정 백분위 내의 결과 데이터의 범위 등과 같은 통계량들을 시각화하기 위해 설계되었으며, 정적인 정보들만 제공하는 것에 비해 사용자들이 시뮬레이션 결과 데이터에 담긴 가변성을 더욱 직관적으로 쉽게 이해할 수 있도록 돕는다. 본 연구에서는 BMORE 도표를 단순히 한 시스템의 가변성을 시각화하기 위한 것이 아닌, 특정 확률적 제약 아래 대상 시스템들의 실행 가능성을 타진하고, 통계적 배경 아래 여러 시스템들의 성과 비교를 행하며, 매개변수들의 민감도 분석을 실시하기 위한 의사결정 도구로써 활용할 수 있음을 보이고 이를 위한 여러 방안을 제안한다. 그 활용 예시를 보이고자 본 연구에서는 간단한 재고 관리 문제를 차용하였으나, 제시된 방안들 자체는 이변량 성과 척도를 가지는 시뮬레이션/실험 데이터를 근거로하여 여러 시스템들을 비교하는 문제라면 어디든 사용될 수 있음을 밝혀둔다.

응급의료센터를 위한 위험기반 운영계획 모델

이미림(Mi Lim Lee),이진표(Jinpyo Lee),박민재(Minjae Park) 한국산업경영시스템학회 2019 한국산업경영시스템학회지 Vol.42 No.2

In order to deal with high uncertainty and variability in emergency medical centers, many researchers have developed various models for their operational planning and scheduling. However, most of the models just provide static plans without any risk measures as their results, and thus the users often lose the opportunity to analyze how much risk the patients have, whether the plan is still implementable or how the plan should be changed when an unexpected event happens. In this study, we construct a simulation model combined with a risk-based planning and scheduling module designed by Simio LLC. In addition to static schedules, it provides possibility of treatment delay for each patient as a risk measure, and updates the schedule to avoid the risk when it is needed. By using the simulation model, the users can experiment various scenarios in operations quickly, and also can make a decision not based on their past experience or intuition but based on scientific estimation of risks even in urgent situations. An example of such an operational decision making process is demonstrated for a real mid-size emergency medical center located in Seoul, Republic of Korea. The model is designed for temporal short-term planning especially, but it can be expanded for long-term planning also with some appropriate adjustments.

생산성 향상을 위한 수요 불확실성하의 듀얼 소싱에 관한 연구: 감자스낵시장 사례

나병수 ( Byungsoo Na ),김진민 ( Jinmin Kim ),이진표 ( Jinpyo Lee ) 한국생산성학회 2016 生産性論集 Vol.30 No.4

The demand for potato in potato snack industry has been gradually increased, but the supply of potato has hardly met such growing demand because of a limited domestic capacity of potato farming. Usually, domestic sourcing is used between June and November, and foreign sourcing from the United States or Australia is used in other periods. A foreign order should be placed prior to 1 year in order to purchase at a low price. However, it is hard to forecast domestic demand and domestic production. Hence, under such uncertainties of domestic demand and production, finding the optimal pre-order quantity is a very important issue in potato snack industry and the productivity of the company is seriously affected by its decision. This research defines the dual sourcing problem in potato snack industry and applies a stochastic programming approach to obtain an optimal pre-order quantity. We analyze five real-world cases according to the amount of domestic demand and supply. We compare the solution of the stochastic programming approach with the expected value solution. In all cases, the stochastic programming solution achieves 2% ~ 4% cost saving than the expected value solution. Its saving corresponds to about one million dollars. Furthermore, in the sensitivity analysis, we examine the change of optimal pre-order quantity and total cost when the late-order quantity increases. The result shows that as the late-order quantity increases, the optimal pre-order quantity should be increased. The contribution of this research is two fold. First, this is the first research to define the dual sourcing problem in potato snack industry using management science. In this research, it is expected to be useful for making decisions on sourcing in agricultural industry. Second, we apply the stochastic programming approach to solve this and our approach can contribute about 3% of cost saving. Although agricultural producers generally have a low operating margin, reduction of costs for raw materials will help to improve total productivity.

세계 주요 천연가스업체의 효율성 및 생산성 분석

김기현(Ki-Hyun Kim),황승준(Seung-June Hwang),이진표(Jinpyo Lee) 대한경영학회 2018 大韓經營學會誌 Vol.31 No.2