• 산업공학
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• 제12권1호
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• pp.10-18
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• 1999

Job shop manufacturing environments are using the concept of cellular manufacturing systems(CMS) which has several advantages in reducing production lead times, setup times, work-in-process, etc. Utilizing the similarities between cell-machine, part-machine, and the shape/size of parts, CMS can group machines and parts resulting in improved efficiency of this system. However, when grouping machines and parts in machine cells, there inevitably occurs exceptional elements(EEs), which can not operate in the same machine cell. Minimizing these EEs in CMS is a critical point that improving production efficiency. Constraints in machine duplication cost, machining process technology, machining capability, and factory space limitations are main problems that prevent achiving the goal of maintaining an ideal CMS environment. This paper presents an algorithm that minimizes EEs under the constraints of machine duplication cost and factory space limitation. Developing exceptional operation similarity(EOS) by cell-machine incidence matrix and part-machine incidence matrix, it brings the machine cells that operate the parts or not. A mathematical model to minimize machine duplication is developed by EOS, followed by a heuristic algorithm in order to reflect dynamic situation resulting from minimizing exceptional elements process and the mathematical model. A numerical example is provided to illustrate the algorithm.

• 산업경영시스템학회지
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• 제18권34호
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• pp.91-97
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• 1995

This paper presents a possible application of artificial neural network in CM system design. CM systems can be designed based on product lines, part characteristics or part routines. GT(Group Technology) which uses part characteristics to design cells is widely applied, however, the identification of the part-machine families is the fundamental problem in the design process. A heuristic procedure using SOFM which requires only part-machine incidence matrix is proposed in this research. Comparison studies on ZODIAC and ROC with SOFM model are done and the results are discussed and summarized in this paper.

• 산업경영시스템학회지
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• 제22권50호
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• pp.45-54
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• 1999

Cellular manufacturing(CM) is a manufacturing philosophy and strategy for improving both productivity and flexibility. Cell formation(CF), the first and key problem faced in designing an effective CM system, is a process whereby parts with similar design features or processing requirements are grouped into part families, and the corresponding machines into machine cells. In this paper, a sophisticated fuzzy mixed-integer programming model is proposed to simultaneously form manufacturing cells and minimize the total costs of dealing with exceptional elements. Also, we will proposed a new method to solve the cell formation problem in the fuzzy environment.

• 산업경영시스템학회지
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• 제21권46호
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• pp.59-72
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• 1998

This study is concerned in manufacturing cell formation with operation sequences. Operation sequences must be reflected for manufacturing cell formation anyway, because the primary aim of cellular manufacturing system is to minimize the inter-cell flows, and inter-cell flows are differed by operation sequences. In this study we propose flow-similarity(FS) of reflecting both inter-machine similarity and direct/indirect flow, and then apply the modified P-median model for grouping machines. We also use machine cell-part handling frequency(CPH) so as to be assigned parts to the machine cells having the most CPH. We confirm this approach through an application example. The performance of this approach(FS-model) is evaluated and compared with P-median model and F-model through computational experiments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권9호
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• pp.2805-2817
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• 2024

This study focuses on the performance of device-to-device (D2D) communications in underlay cellular networks by analyzing key metrics such as successful transmission probability, coverage probability, and throughput. Under the homogeneous Poisson point process (PPP) spatial distribution of full-duplex (FD)-D2D users in cellular networks, stochastic geometry tools are used to derive approximate expressions for D2D users' coverage probability and throughput. In comparison to the conventional half-duplex (HD) communication mode, when the self-interference cancellation factor β reaches -95 dB, there is a substantial improvement in the throughput of FD-D2D users, nearly doubling their gain. Additionally, experimental results demonstrate that the Newton iterative algorithm can be used to optimize the targeted signal-to-interference-plus-noise-ratio (SINR) threshold of users within the range of (10, 20) dB.

• 산업경영시스템학회지
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• 제39권3호
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• pp.83-89
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• 2016

The group formation problem of the machine and part is a critical issue in the planning stage of cellular manufacturing systems. The machine-part grouping with alternative process plans means to form machine-part groupings in which a part may be processed not only by a specific process but by many alternative processes. For this problem, this study presents an algorithm based on self organizing neural networks, so called SOM (Self Organizing feature Map). The SOM, a special type of neural networks is an intelligent tool for grouping machines and parts in group formation problem of the machine and part. SOM can learn from complex, multi-dimensional data and transform them into visually decipherable clusters. In the proposed algorithm, output layer in SOM network had been set as one-dimensional structure and the number of output node has been set sufficiently large in order to spread out the input vectors in the order of similarity. In the first stage of the proposed algorithm, SOM has been applied twice to form an initial machine-process group. In the second stage, grouping efficacy is considered to transform the initial machine-process group into a final machine-process group and a final machine-part group. The proposed algorithm was tested on well-known machine-part grouping problems with alternative process plans. The results of this computational study demonstrate the superiority of the proposed algorithm. The proposed algorithm can be easily applied to the group formation problem compared to other meta-heuristic based algorithms. In addition, it can be used to solve large-scale group formation problems.

• 한국레이저가공학회지
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• 제11권4호
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• pp.29-34
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• 2008

Ultraviolet laser micromachining has increasingly been applied to the electronics industry where precision machining of high-density, multi-layer, and multi material components is in a strong demand. Due to the ever-decreasing size of electronic products such as cellular phones, MP3 players, digital cameras, etc., flexible printed circuit board (FPCB), multi-layered with polymers and metals, tends to be thicker. In present, multi-layered FPCBs are being mechanically cut with a punching die. The mechanical cutting of FPCBs causes such defects as burr on layer edges, cracks in terminals, delamination and chipping of layers. In this study, the laser cutting mechanism of FPCB was examined to solve problems related to surface debris and short-circuiting that can be caused by the photo-thermal effect. The laser cutting of PI and FCCL, which are base materials of FPCB, was carried out using a pico-second laser(355nm, 532nm) and nano-second UV laser with adjusting variables such as the average/peak power, scanning speed, cycles, gas and materials. Points which special attention should be paid are that a fast scanning speed, low repetition rate and high peak power are required for precision machining.

• 제어로봇시스템학회논문지
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• 제13권5호
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• pp.499-506
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• 2007

The tiny camera module used in a modern cellular phone requires precise assembly processes. To meet the requirement of high resolution and functionality, the number of parts used in a camera module becomes larger and larger. As the market grows rapidly, an automatic camera phone assembly process is required. However, diverse production line and short life cycle make it difficult to build an affordable assembly line. To attack this problem, a flexible and expandable lens assembly system is proposed. To save the manufacturing line set-up time, modular concept is adopted. Also, each module is designed to have intelligence to simplify the set-up process. The assembly system is built up on the standard flat-form that includes a vibration free base, air and electric supplies, and electronic controllers, etc. Furthermore, the assembly cell has the capability of handling tiny, thin, or transparent parts which are very difficult to identify without machine vision.

• 산업경영시스템학회지
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• 제20권44호
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• pp.171-178
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• 1997

본 연구는 셀루라 제조방식을 갖고 있는 대기업에서의 예방보전에 관한 연구이다. 특히 24 시간운영하는 생산시스템을 갖고있으며, 보전요원이 충분한 업종이나 기업을 연구대상으로 하였다. 새로운 예방보전 절차를 제시하고 하나의 셀을 모델링하였다. 이 모델을 대상으로 시뮬레이션기법을 사용하여 기존에 절차와 비교분석하였다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1997년도 추계학술대회발표논문집; 홍익대학교, 서울; 1 Nov. 1997
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• pp.11-14
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• 1997

Flexibility and efficiency in producing a large number of productions in small-to-medium lot sizes are necessary to be competitive. Many firms are concerned about cellular manufacturing system(CMS) to surmount the abrupt change in management environment and to innovate their manufacturing systems. The purpose of this study 1) align BPR with CMS, 2) present the methodology for constructing a CMS and 3) apply to a firm ad verify it. The results of this paper are to present 1) the systematic methodology for constructing CMS at first in our country, 2) the methodology integrating managerial aspects, technological aspects and behavioral aspects, 3) the customer-oriented methodology based on customer value.