• 한국항공운항학회지
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• 제22권1호
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• pp.108-113
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• 2014

Recently increase in the number of aircraft caused the air traffic congestion and flight delays. If timely action to reform the air traffic system is not taken, these may result in added economic impact. As a result, the air traffic management should be changed in an innovative manner to modernize the existing air traffic control environment. This paper reviews the trends of airspace reforms such as integration of terminal control areas and flexible use of airspace introduced by foreign countries and compares their merits and demerits in order to provide a judgement to adopt the concept in domestic airspace in the future.

• 한국경영과학회지
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• 제24권2호
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• pp.1-15
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• 1999

This research involves the development and evaluation of a work flow control model for a type of flexible manufacturing system(FMS) called a flexible flow line(FFL). The control model can be considered as a kind of hybrid intelligent model in that it utilizes both computer simulation and neural network technique. Training data sets were obtained using computer simulation of typical FFL states. And these data sets were used to train the neural network model. The model can easily incorporate particular aspects of a specific FFL such as limited buffer capacity and dispatching rules used. It also dynamically adapts to system uncertainty caused by such factors as machine breakdowns. Performance of the control model is shown to be superior to the random releasing method and the Minimal Part Set(MPS) heuristic in terms of machine utilization and work-in-process inventory level.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1993년도 추계학술대회발표논문집; 서강대학교, 서울; 25 Sep. 1993
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• pp.118-118
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• 1993

We consider a discrete event dynamic system called periodic job shop, where an identical mixture of items called minimal part set(MPS) is repetitively produced in the same processing order and the primary performance measure is the cycle time. The precedence relationships among events(starts of operations) are represented by a directed graph with rocurront otructure. When each operation starts as soon as all its preceding operations complete(called earliest starting), the occurrences of events are modeled in a linear system using a special algebra called minimax algebra. By investigating the eigenvalues and the eigenvectors, we develop conditions on the directed graph for which a stable steady state or a finite eigenvector exists. We demonstrate that each finite eigenvector, characterized as a finite linear combination of a class of eigenvalue, is the minimum among all the feasible schedules and an identical schedule pattern repeats every MPS. We develop an efficient algorithm to find a schedule among such schedules that minimizes a secondary performance measure related to work-in-process inventory. As a by-product of the linear system approach, we also propose a way of characterizing stable steady states of a class of discrete event dynamic systems.

• 대한안전경영과학회지
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• 제8권6호
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• pp.79-90
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• 2006

Recently the construction of the ERP(Enterprise Resource Planning) system becomes accomplished actively from the many enterprises. But the many problems occur in acquisition of production data which is a fundamental data of system. Also to delay the acquisition of the production result is fatal in the efficient business operation. The construction of the POP(Point of Production) system which acquires production data at real time is become accomplished widely, In the POP system it is most important to acquire the production data which is accurate. But the many enterprises drop the competitive power with acquisition of the data which could not be trusted. In this paper, we analyze these causes and present the method which it can improve the reliability of production data. Also we introduce a real application case.

• 품질경영학회지
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• 제5권1호
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• pp.3-10
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• 1977

The research on the process capability is the basis for quality design, operation standard and so on. In this study, histogram of the measured value for the cutting process and calculation of the capability factor Cp are established, resulting in the classification of 4 grades, and necessary measures for them are presented. The advancement of productivity is the most significant result of this study. The processing time per piece for those stabilized processes having the capability factor 1.33 and above is lessened, and the advancement in quantity capability is made possible permitting dispersion of standard up to the tolerance limit. The exact knowledge of process capability is most important for the quality design system. For the efficient application of this result of the research, a systematic and positive cooperation by the whole company members is needed.

• 정보학연구
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• 제10권3호
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• pp.59-75
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• 2007

Java Card has several applets running on card, and applet can be added easily. Each applet supports different application programs, and includes file system for data management. This paper presents design and implementation of the file system API based on Java Card for the efficient data management in need of the applet. We referred the smart card international standard ISO7816-4 for the file system and used API supported at Java Card. Results show that it is easy to design and operation of file systems during the applet development, also show lighting of applet's source codes and improved access times.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1996년도 춘계공동학술대회논문집; 공군사관학교, 청주; 26-27 Apr. 1996
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• pp.294-296
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• 1996

JIT(just-in-time) 생산시스템은 제조라인의 재공품 재고량을 최소화하고, 필요한 품목을 적시에 필요한 양만큼만 생산하여 공급하는 것을 목적으로 한다. 이러한 시스템은 사용하는 칸반의 수에 따라 single-card kanban system과 two-card kanban system으로 구별할 수 있다. 또한 각 공정이 입력버퍼(input buffer)와 출력버퍼(output buffer)를 갖는 경우와 공정간에 하나의 버퍼를 갖는 경우로 나누어 볼 수 있다. 본 연구는 기계간의 물류(material handling)가 필요한 시점에 즉시 이루어진다는 가정하에 기계간 버퍼가 하나이고, 그 버퍼의 용량이 1인 경우의 single-card kanban의 효율적인 운용방안을 개발하였다. 본 연구의 목적은 생산지시칸반의 회수시기를 적절히 조절하여 생산라인의 이용효율(utilization)을 극대화하고자 하는 것이다. 칸반회수시기 결정을 위한 상황분석의 범위를 10대의 기계로 제한하여 시뮬레이션에 의해 분석하였다. 기존의 칸반운영방식과 생산라인에서의 재고를 최소화하는 운영 알고리듬, 그리고 생산기계의 효율을 최대화할 수 있는 운영 알고리듬을 개발하여 비교.분석하였다.

• 한국경영과학회지
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• 제11권1호
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• pp.36-43
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• 1986

In this study, the fuzzy programming is extended to handle various types of membership functions by transformation of the complicated fuzzy programming problems into the equivalent crisp linear programming problems with single objective. It is well-known that the fuzzy programming problem with linear membership functions (i.e., ramp type) can be easily transformed into a linear programming problem by introducing one dummy variable to minimize the worst unwanted deviation. However, until recently not many researches have been done to handle various general types of complicated linear membership functions which might be more realistic than ramp-or triangular-type functions. In order to handle these complicated membership functions, the goal dividing concept, which is based on the fuzzy set operation (i. e., intersection and union operations), has been prepared. The linear model obtained using the goal dividing concept is more efficient and single than the previous models [4, 8]. In addition, this result can be easily applied to any nonlinear membership functions by piecewise approximation since the membership function is continuous and monotone increasing or decreasing.

• 경영과학
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• 제29권2호
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• pp.143-155
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• 2012

The purpose of this study is to formulate and solve the scheduling problem to heat-treatment process in forging process and apply it to industries. Heat-treatment is a common process in manufacturing heavy forged products in ship engines and wind power generators. Total complete time of the schedule depends on how to group parts and assign them into heat furnace. Efficient operation of heat-treatment process increases the productivity of whole production system while scheduling the parts into heat-treatment furnace is a combinatorial problem which is known as an NP-hard problem. So the scheduling, on manufacturing site, relies on engineers' experience. To improve heat-treatment process schedule, this study formulated it into an MIP mathematical model which minimizes total complete time. Three methods were applied to example problems and the results were compared to each other. In case of small problems, optimal solutions were easily found. In case of big problems, feasible solutions were found and that feasible solutions were very close to lower bound of the solutions. ILOG OPL Studio 5.5 was used in this study.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2000년도 추계종합학술대회
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• pp.585-589
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• 2000

본 논문에서 제안하는 양식 경영 자동화의 표준안은 개인의 경험과 주관적인 판단에 의한 비합리적인 양식장 운영을 개선하여 양식장의 경영 표준안을 제시하는데 그 의의가 있으며 이 표준안은 실제 양식장들이 전통적으로 일지를 기록하고 있다는 것에 기초하여 제작되었다. 제안하는 표준안은 양식장 관리일지 기입만으로 모든 통계자료와 경영상태 판매시점 예측이 가능하며 정보화가 더딘 어업인을 대상으로 고급메뉴와 초급 메뉴를 차별화 하여 사용상의 어려움을 최소화시키고 조작의 간결성을 더하였다.