• 대한산업공학회지
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• 제33권2호
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• pp.166-173
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• 2007

In this paper, we propose a model-based approach to estimating production parameters of semiconductor FAB equipment. For FAB scheduling, for example, we need to know equipment's production parameters such as flow time, tact time, setup time, and down time. However, these data are not available, and they have to be estimated from material move data such as loading times and unloading times that are automatically collected in modern automated semiconductor FAB. The proposed estimation method may be regarded as a Bayes estimation method because we use additional information about the production parameters. Namely, it is assumed that the technical ranges of production parameters are known. The proposed estimation method has been applied to a LCD FAB, and found to be valid and useful.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2000년도 춘계학술대회
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• pp.97-110
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• 2000

Production schedule and realization quantity of Large type bus [929(HD), 928, 928-A(SD), 937E/L, 937/L,] were analyzed in order to intruoduce FMS(Flexible Manufacturing System) appropriate for varities of customer desire and multi-item, small lot production. And this paper is aimed to propose introduction method of FMS, analyzing zig tools change times and idle times with production line and workers as an object. According to analysis results, only simple spec., depending on bus type, changed with decrease in production. For 929(HD), 928,928-A(SD), 937Eh, 937/L bus type, there was no harmony between schdule and realization. Therefore, it caused many difficulties in part supply. And there was loss of manpower and reduction of productibility due to idle time of process with bus type change. Production processes were operated inefficiently because tact time exceeded or shortaged of allow time.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.651-657
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• 1996

Industrial products are getting more and more complex. The number of parts or components and the variety of manufacturing processes are increasing. This leads to rapid product oriented machine tools. The process integrated CNC lathe is one of the these machine tools which can produce numerous parts and various machining processes and reduce the lead time and non-machining time. Therefore this study deals with the design technique of a process-intergated CNC lathe which can reduce the tact time and production cost by the speed-up of the tooling system and the high-speed machining oriented construction of 2 spindles and 2 turrets.

• 한국공작기계학회논문집
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• 제18권2호
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• pp.144-153
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• 2009

It is widely known that no-slip assumptions are often violated on regular basis in micrometer- or nanometer-scale fluid flow. In the case of cavity-filling process of nanoimprint lithography(NIL), slip phenomena take place naturally at the solid-to-liquid boundaries, that is, at the mold-to-polymer or polymer-to-substrate boundaries. If the slip or partial slip phenomena are promoted at the boundaries, the processing time of NIL, especially of thermal-NIL which consumes more tact time than that of UV-NIL, can be significantly improved. In this paper it is aimed to elucidate how the cavity-filling process of NIL can be influenced by the slip phenomena at boundaries and to what degree those phenomena increase the process rate. To do so, computational fluid dynamics(CFD) analysis of cavity filling process has been carried out. Also, the effect of mold pattern shape and initial thickness of polymer resist were considered in the analysis, as well.

• 한국시뮬레이션학회논문지
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• 제12권1호
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• pp.21-34
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• 2003

This paper deals with a case study of workload analysis of an operator in an automatic line for machining the race of ball bearing. Eleven machines and three hoppers are installed in the line which is operated by an operator. The elements of operation are separated into machine controlled elements, operator controlled elements and machine/operator controlled elements. In order to analyze the system, time and motion studies are used for gathering input data for the simulation model. The first objective of this study is to evaluate whether the workload of operator is reasonable or not. The second objective is to increase throughput by reducing tact time and the last one is to increase frequencies of inspection by reducing interval. Thus we suggest some ideas for improvement, and as a result, the throughput is improved about 9%. In spite of the increasing of throughput, the allowance of operator is also increased about 4%.

• 한국산학기술학회논문지
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• 제13권2호
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• pp.562-574
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• 2012

기존 대부분의 연구에서 사용하고 있는 시뮬레이션 검증 기법은 통계적 분석기법으로, 총 처리량이나 자원 이용률의 평균 및 분산을 통해 분석하여 왔다. 그러나 이러한 방식은 모델의 개별적인 요소들에 대한 신뢰성을 보장하기 어려웠다. 이를 해결하기 위해 제시된 방법이 가중 F-measure를 사용한 검증이다. 하지만 가중 F-measure는 Tact time 값 하나에 대해 하나의 클래스를 할당하기 때문에 수많은 Tact time 값들을 갖는 복잡한 시스템에 적용하기 어려운 문제를 가지고 있다. 한편, 가중치의 범위가 정해져 있지 않기 때문에 평가기준(Threshold)의 선정에 있어서 어느 정도의 수준이 만족할만한 수준인지 정하기가 어려웠다. 따라서 본 논문에서는 이러한 문제점을 개선하기 위해 군집분석을 적용한 가중 F-measure를 제시한다. 군집의 클래스화를 통해 클래스의 수를 현저히 줄일 수 있고 다양한 시스템으로의 적용 또한 가능해진다. 또한 객관성을 저하시키지 않는 범위 내에서 최소한의 가중치를 부여하는 방식으로 가중치의 범위를 지정하여 검증 방법을 향상시켰다. 이를 입증하기 위해 국내 'L사'의 LCD공정설비를 대상으로 시뮬레이션 모델링 및 환경을 구축하였고, 그 결과를 통해 타당성을 증명하였다.

• 한국경영공학회지
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• 제23권4호
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• pp.87-103
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• 2018

This paper introduces the method to develop two main types of the fuzzy OEE (Overall Equipment Effectiveness) models via triangular membership function for measuring uncertainty. The fuzzy OEE includes model type 1 and model type 2. The model type 1 is used when the theoretical machine speed only reflects the time loss whereas model type 2 is used when the actual machine speed reflects both time and speed loss. Model type 2 has shown to perform a lower availability rate and a higher performance rate compared to model type 1. In addition, the fuzzy UPH (Unit Per Hour) which is derived from using the fuzzy OEE is presented to satisfy demand uncertainty. The fuzzy UPH can easily measure the fuzzy tact time and cycle time by reciprocating itself. Finally, this study demonstrates the fuzzy OEE models using IVIFS (Interval-Valued Intuitionistic Fuzzy Set) based on the characterization via membership function, non-membership function and hesitant function. For the purpose of analyzing the fuzzy system OEE, the OEE for each machine of plant structure is considered triangular interval-valued intuitionistic fuzzy number. Regardless of plant structure, the validity degree of fuzzy membership function of system OEE decreases when the number of machine with worst value of the validity degree increases. Corresponding examples are presented in this paper for practitioner to understand the applicability and practicability of the proposed fuzzy OEE methods.

• 대한기계학회논문집
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• 제18권8호
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• pp.2016-2025
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• 1994

A hierarchical planning strategy for dextrous manipulation of multifingered hands with soft finger contact model is proposed. Dextrous manipulation planning can be divided into a high-level stage which specifies the position/orientation trajectories of the fingertips on the object and a low-level stage which determines the contact forces and joint trajectories for the fingers. In the low-level stage, various nonlinear optimization problems are formulated according to the contact modes and integrated into a manipulation planning algorithm to find contact forces and joint velocities at each time step. Montana's contact equations are used for the high-level planning. Quasi-static simulation results are presented and illustrated by employing a three-fingered hand manipulating a sphere to demonstrate the validity of the proposed low-level planning strategy.

• 한국공작기계학회논문집
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• 제10권3호
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• pp.1-6
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• 2001

An analytical thermal model of HESG(higt efficiency speed grinding) is presented, in which the heat flux to workpiece in grinding zone is modeled as time dependent and moves along a slope decided by contact chord(approximation of con-tact arc). By matching the maximum surface temperature of workpiece derived from this model to the maximum surface temperature of grinding wheel composite as done in Lavins simple thermal model, the relation of maximum surface tem-perature and energy partition of workpiece to grinding speed is obtained. In high speed grinding, as wheel speed increases, energy partition decreases with no regard to table speed.

• 한국산업안전학회:학술대회논문집
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• 한국안전학회 2003년도 춘계 학술논문발표회 논문집
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• pp.564-571
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• 2003

현대 산업사회는 첨단 산업기술의 발전으로 많은 생산시설이 자동화되고, 작업형태 또한 생산성을 높이기 위한 택트타임(tact time) 분석으로 작업이 더욱 세분화되고 있으며, 이로 인해 작업자의 특정 신체부위만 집중적으로 사용하는 단순 반복작업이 크게 증가하고 있다. 그 결과 작업자가 어깨, 허리, 손목 등에 통증을 호소하는 근골격계질환이 계속 증가하는 추세에 있다. 노동부 자료[1]에 의하면 근골격계질환자 수가 2000년 1,009명, 2001년 1,598명이고 2002년 상반기만 1,069명으로 점차 증가 추세를 보이고 있으며, 2002년 한해 동안만 ○○중공업 253명, ○○조선 158명, ○○자동차 78명의 근골격계질환자가 발생하여 산업재해 판정을 받음으로써, 이로 인한 노동력 상실 및 막대한 비용 손실로 인해 심각한 사회적인 문제로 대두되고 있다[2].(중략)