반도체 Wafer Fabrication 공정은 무수한 공정과 복잡한 Lot의 흐름 등으로 다른 제조 형태에 비해 효율적인 관리가 대단히 어려운 부문이다. 본 연구는 반도체 Fab을 대상으로 주어진 생산 소요량과 목표 공기를 효율적으로 달성하기 위한 Shift 단위의 생산 일정계획을 대상으로 하였다. 특히, 전 공정 및 장비를 고려하기보다는 Bottleneck인 Photo 공정의 Stepper를 중심으로, 공정을 Layer단위로 묶어, 한 Shift에서 어떻게 Stepper를 할당하고 생산계획을 할 것인가를 결정하기 위한 2단계 방법론을 제시하고, Stepper 할당 및 계획에 필요한 3가지 알고리즘들을 제시하였다. 이 기법들을 소규모의 예제들에 대해 적용한 결과와 최적해와의 비교를 통하여 그 성능을 평가하였다.

In semiconductor manufacturing, the probe process between fabrication and assembly process is constrained mostly by the equipment capacity because most products pass through the similar procedures. The probe process is usually performed in a batch mode with relatively short cycle times. The capability of the probe process can be determined by the optimal combination of the equipments and the products. A probe line usually has several types of equipment with different capacity. In this study, the probe line is modeled in terms of capacity to give the efficient planning and control procedure. For the practical usage, the hierarchical capacity planning procedure is used. First, a monthly capacity plan is made to meet the monthly production plan of each product. Secondly, the daily capacity planning is performed by considering the monthly capacity plan and the daily fabrication output. Simple heuristic algorithms for daily capacity planning are developed and some experimental results are shown.

혼류생산을 위한 반도체 웨이퍼 제조라인 중 엣칭공정의 생산운영대안의 평가를 위한 시뮬레이션 기반의 분석시스템의 개발사례를 소개한다. 엣칭공정의 공정특성 및 작업흐름을 소개하고 생산운영을 위한 의사결정 문제를 설명한다. 생산운영대안의 평가 및 비교를 위해서는 시뮬레이션 모델을 활용한다. 웨이퍼의 회로계층의 수만큼 일련의 제조공정을 반복하는 반복방문 방식의 작업흐름 특성 때문에 생기는 타 공정성과 연관성을 반영하되 엣칭공정의 작업흐름에 초점을 맞추기 위해 엣칭공정 이외의 타공정을 단순화시키는 모델링기법을 사용하였다. 엣칭베이내의 복잡한 작업흐름 및 장비운영제약 조건등을 모델링하기 위해 활용한 객체지향방식의 모델링기법의 적용사례를 소개한다.

본 연구에서는 웨이퍼 팹공정에서 웨이퍼 로트들이 뱃치공정을 위해 확률적으로 도착되는 상황에서 최적 뱃치크기를 결정하는 뱃칭문제를 다루고 있다. 뱃치공정이란 여러 개의 웨이퍼 로트들을 기계의 용량을 넘지 않는 한도 내에서 하나의 뱃치로 구성하여 한꺼번에 가공하는 공정을 말한다. 목적함수는 생산율을 높이고 재공재고 및 사이클타임을 줄이기 위해 웨이퍼 로트들의 평균 대기시간의 최소화를 채택하였다. 문제의 해결을 위해서, 확률적인 상황변동 하에서 실시간 제어를 위해 많이 활용되고 있는 신경회로망 중 다층 퍼셉트론을 이용한 뱃치크기 결정 모델을 제시하였다. 제시한 모델의 효율성을 확인하기 위해 기존에 잘 알려져 있는 최저뱃치크기(MBS) 규칙과 실험, 비교하였다.

This paper deals with an assembly process of the TFT glasses and the color filters in LCD manufacturing. Two specific problems are presented and solved. One is a matching problem to find the best matches between a set of TFT glasses and a set of color filters, which result in the maximum number of good LCD assemblies. A simple mathematical model is constructed for this problem and an optimal solution can be obtained using an existing algorithm. The other is a main problem that requires a determination of an economic lot size of the color filters which are going to be assembled with a given set of TFT glasses. A Bayesian dynamic forecasting model is developed to predict the defective patterns of color filters. Based on the predicted defective rate of color filters, the minimum lot size of the color filters can be determined to minimize the probability of losing good TFT glasses and color filters.

Less researches on AGV(Automated Guided Vehicle) path configurations have been conducted so far while more studies have been placed in determining AGV guide path directions and pick-up/drop-off station locations, and routing/dispatching/scheduling strategies. In practice plenty of concerns fall in preventing deadlock and simplifying AGV system control through an appropriate AGV path configuration. In order to meet those requirements, a new AGV path configuration, inter-loop stocker type is introduced here. The stocker serves as relaying material between loops as well as stocking material. Automated material handling systems using AGVs play an important role in semiconductor industry including TFT LCD and memory/non-memory chip. A practical example of implementing the inter-loop stocker concept successfully in the TFT LCD fab is presented in this paper.

반도체 제조공정에서 패터닝 공정과 박막형성 공정은 매우 중요한 위치를 차지하고 있다. 본 논문의 목적은 위 두가지의 공정을 최적화하기 위한 품질공학적 접근방법을 소개하는데 있다. 특히, 패터닝 공정의 전사성과 박막현상 공정의 두께의 균일성에 관한 문제를 동특성의 문제로 정형화하고 신호인자를 어떻게 설정할 것인가에 관해 논의하였다.

지난 30여 년간 반도체 제조 공정 중 FAB공정에서 칩 수율 모델의 개발과 적용은 반도체생산 계획 및 조업 관리를 위해 반도체 제조사들에게는 중요한 관리 대상이 되어 왔으며 제조업체들은 다양한 수율 모델들을 각 업체의 조건에 맞게 채택, 적용하여 왔다. 집적 기술의 발전은 반도체 칩의 크기에도 변화를 가져와 웨이퍼상의 결점들이 형성하는 클러스터를 설명할 수 있어야 했으며 칩 면적의 증가는 새로운 수율 모델을 개발케 하였다. 본 논문은 반도체 제조 공정에 대한 고찰과 수율 계산에 영향을 미치는 결점의 클러스터 효과 및 결점 크기를 중심으로 하는 치명 확률에 대하여 살펴보고, 포아송 모델에서 파생된 대표적인 칩 수율 모델들에 대한 설명과 칩 면적의 변화에 따른 각 모델별 수율 계산 비교 및 반도체 수율의 이용에 대하여 기술한다.

본 논문은 실험계획법을 반도체 공정 및 소자 시뮬레이터에 적용하여, 시뮬레이션 회수를 최소화하고, 동시에 현장과 유사하게 시뮬레이터 내부 파라미터가 튜닝 될 수 있도록 하는 교정 문제에도 활용된 반도체 공정 최적화 사례를 소개한다. 또한, 일반적 시뮬레이터가 실제 현장과의 차이점으로 갖는 문제인 동일한 입력 값에 대해 항상 같은 출력 값이 산출되는 점을 공정의 규격을 고려해 시뮬레이션 함으로써 현장에서의 재현성을 높이고자 하였다. 이는 $0.8{\mu}m$급 BIMOS 공정의 기본 소자 중 하나의 NPN 트랜지스터의 전류이득(Current Gain : hFE) 특성을 최적화하기 위한 주요 공정조건 결정과 연관된 것이며, 기존 방법에 비해 시뮬레이션 횟수를 줄이는 동시에 현장에 직접 투입되는 검증 로트를 최소화시켜 비용과 시간을 절감할 수 있었다. 또한, 얻어진 추전 조건에서 실제 생산된 검증 로트를 통해 시뮬레이션으로부터 얻어진 결과들이 재현됨으로써 제시된 방법의 유용성을 확인하였다.

본 논문에선 반도체 공정과 각 공정의 문제점 및 중요점을 살펴본 다음 종합품질경영(TQM)기법의 적용에 대해서 고찰하였다. TQM과 방침관리를 소개하고, 반도체 공장 전체의 관리 입장에서 적용할 수 있게 제안하였다. 또한 각 공정에서 사용할 수 있게 기존의 통계적 품질관리 기법중 관리도와 $6{\delta}$ 기법을 반도체 공정에 맞게 수정하여 제안하였다. 또한 반도체 공정의 특성에 맞추어 모든 관리 기법이 동적으로 변화해야 한다는 관점에서 지속적 개선을 소개하고 적용을 추천하였다.

The management of blood inventory is very important within the medical care system. The efficient management of blood supplies and demands for transfusions is of great economic and social importance to both hospitals and patients. For any blood type, there is a complex interaction among the optimal inventory level, daily demand level, daily supply level, transfusion to crossmatch ratio, crossmatch release period, issuing policy and the age of arriving units that determine the shortage and outdate rate. In this paper, we develop an efficient decision rule for blood inventory management in a hospital blood bank which can support efficient hospital blood inventory management using simulation. The primary use of the efficient decision rule will be to establish minimum cost function which consists of inventory levels, period in inventory, outdate and shortage rate for whole blood and various component inventories for a hospital blood bank or a transfusion service. If the administrator compute the mean daily demand for each blood type, the mean daily supply for each blood type, the length of the crossmatch release period and the average transfusion to crossmatch ratio, then it is possible to apply the efficient decision rule to compute the optimal inventory level, inventory period, outdate and shortage rate. This rule can also be used as a decision support system that allows the blood bank administrator to do sensitivity analysis related to controllable blood inventory parameters.

The importance of training for NC, CNC and Machining Center has been greatly increased. This paper presents implementation of a DNC(Direct Numerical Control) operating software for educational system. This system is able to connect 8-32 CNCs to Control PC with RS232 multi-port serial card. Therefore, it allows much efficiency in training even after costs are considered. The KISCO DNC S/W for above system includes various communication functions, communication parameters setting, program editor and user-friendly environment. This software was developed with C and Windows programming. It was proved in function and stability by iterative field tests.

In developing the HMI(Human-Machine Interface) evaluation system for the IVNS(In-Vehicle Navigation System), design guidelines and evaluation methods are the most crucial problems for its use and efficiency. As the part of this system, focused on the final product of the database, subjective mental workload assessment is seriously considered to evaluate the driver's own driving task using the IVNS. This paper suggests the methodology for the ergonomic assessment of the IVNS that corresponds to the subjective measurement of the driver's mental workload by rating his or her own driving task. For this approach, Revision of NASA-Task Load Index(RNASA-TLX) was developed which translated and revised the version of NASA-TLX that is generally accepted an efficient and powerful method for evaluating the in-vehicle information systems. To verify the RNASA-TLX, an experiment was conducted in a real road situation, because the result of the laboratory approach is uncertain and has the differences from the real road test.

The purpose of this study is to develop the program for efficient operation of a multi-functional surface mounting device(SMD) which mount various components on a printed circuit board(PCB). These components are provided by diverse types of feeders such as cassette, stick and tray feeders. The SMD has one or two heads. In the SMD, the positions of PCB and feeders and fixed, and the head moves to pick up a component from a feeder and to mount it on the PCB. The number of lanes occupied by each feeder and the nozzle used for each component can be different. We develop an off-line program to minimize the cycle-time of the SMD by studying the optimal assignment of feeders and the optimal mounting sequence of components. Graphical User Interface(GUI) is also developed. Additionally, we consider the line balancing problem which appears when two SMDs are used sequentially.

Recently, in organizations many decisions are being made by groups. And the organization is changing a lot so are groups. To help decision making of changing groups, we need more flexible and more adaptive GDSS. Therefore one of the critical success factors of GDSS is flexibility and incremental improvement. Prior research on specifying design requirements of GDSS suggests generic design requirements. But they are too general to be incorporated directly into system design, because of the disparity between real group and ideal group that the researchers studied. Many design strategies that start from the generic design requirements thus have contingency variables that changes as the characteristics of group change. From the viewpoint of developers, these variables implicate the desirability of flexibility. To achieve flexibility we need new methodology of design and implementation. Nowadays, object-oriented analysis and design methodologies have been progressed to the point that many systems are being developed through these methodologies. In this paper, a design is proposed using Object-Oriented Modeling Techniques(OMT). Exploiting object-oriented paradigm results in a highly flexible and easily upgradable design.

This paper explains a way of describing the erection sequence using the connecting relationship among blocks of a hull in shipbuilding industry. The information of the adjacent blocks such as upper, lower, right, left, front, rear, and their erection status, etd., is defined and the proper use of this allows us to determine one of the possible erection sequences. The methodology suggested also includes some useful benefits of avoiding insert blocks or maintaining stability in erection process. Further, an algorithm for generating the initial erection network is shown and this network may be a basis for designing daily erection scheduling. Some examples illustrate the procedure developed in this study and the results support the model's fidelity.

The paper provides a methodology to obtain the automaticity indicator of a factory and the sequence of enabling technologies of factory automation. The automaticity indicator is the measure of the current automation status of a factory and can be used as a crucial criteria for the future automation schedule and investment. Although most industries have their own computation methods which usually consider the number of workers in the shop floor, this research covers five evaluation items of automation, such as, production facility, material transfer system, inspection and test system, information system, and flexibility. The detailed evaluation models are developed for each item. Automation sequencing prioritizes the enabling technologies of factory automation on the basis of several criteria which consist of two phases. The first phase includes the automation indicator and the second phase includes six sub-criteria such as production rate, quality, number of workers, capital investment, development duration, development difficulty. For this evaluation, AHP(Analytical Hierarchy Process) is introduced to prevent the decision maker's subject intention. As results of the automaticity indicator and automation sequence, the manager can save time and cost in building constructive and transparent automation plans.

The process of determining the optimal tool path in PCB(printed circuit board) drilling operations is identical with that of solving a TSP(traveling salesman problem). However, the optimal solution will be ruined when a drill bit needs tracking back in its tool paths. The back tracking occurrences shorten a life of the main spindle and result in inaccurate mechanical movements. In this study, the performances of four heuristics(Nearest Neighbor, Convex Hull, Greatest Angle and Most Eccentric Ellipse) are evaluated to obtain feasible tool paths along with less number of back trackings for a large number of holes(more than 2000holes/bit) and to generate corresponding NC codes for a given CNC drill. Also, the operations of these algorithms are visualized to show a user the graphic image of tool visitation with PCB holes on a computer screen.

The purpose of this study is to make an economic analysis of power plant utilities by examining electricity generating costs with environmental consideration. Economic growth has caused pollutant emission, and subsequent environmental pollution has been identified as a very real limit to sustainable development. Considering the enormous role of electricity in the national economy, it is thus very important to study the effect of environmental regulations on the electricity sector. Because power utilities need large investments during construction, operation and maintenance, and also require much construction lead time. Economic analysis is the very important process in the electric system expansion planning. In this study, the levelized generation cost method is used in comparing economic analysis of power plant utilities. Among the pollutants discharged of the electricity sector, this study principally deals with the control activities related only to $CO_2$, and $NO_2$, since the control cost of $SO_2$, and TSP (Total Suspended Particulates) is already included in the construction cost of utilities. The cost of electricity generation in a coal-fired power plant is compared with one in an LNG combined cycle power plant. Moreover this study surveys the sensitivity of fuel price, interest rate and carbon tax. In each case, this sensitivity can help to decide which utility is economically justified in the circumstance of environmental regulations.