• 대한산업공학회지
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• 제19권2호
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• pp.23-34
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• 1993

Although there are numerous studies that address the problem of optimal machine grouping and part family classification for cellular manufacturing, little research has been reported that studies the conditions where cellular manufacturing is appropriate. This paper, in order to evaluate and compare the job shop with the GT cellular shop, the performance of those shops were simulated by using SIMAN. We tested the effect of independent variables including changes of product demands, intercell flow level, group setup time, processing time variability, variety of material handling systems, and job properties (ratio of processing time and material handling time). And also performance measures (dependent variables), such as machine utilization, mean flow time, average waiting time, and throughput rate, are discussed. Job shop model and GT cellular shop written in SIMAN simulation language were used in this study. These systems have sixteen machines which are aggregated as five machine stations using the macro feature of SIMAN. The results of this research help to better understand the effect of production factors on the performance of cellular manufacturing systems and to identify some of the necessary conditions required to make these systems perform better than traditional job shops. Therefore, this research represents one more step towards the characterization of shops which may benefit from cellular manufacturing.

• Structural Engineering and Mechanics
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• 제85권6호
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• pp.709-716
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• 2023

In this paper, the shape factors of cellular meta-material plates (MMPs) having diverse cell arrays have been determined as the first attempt to finally examine their stability and vibrational frequencies. The MMPs are actually constructed from cylindrical or cubic cellular cores and two face sheets. Sandwich-like MMPs with circular and square holes in the face sheets have been selected in such a way that the effective material properties depend on the cellular architectures. For verifying the frequency results, finite element (FE) simulations are done in Abaqus software. Several graphical results have been represented to explore the effects of cellular architectures on vibrational frequencies and dynamic responses of the MMPs. Also, the deflection-frequency and stability curves in the case of forced vibrations have been plotted for diverse cell arrays.

• 한국정밀공학회지
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• 제16권6호
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• pp.197-208
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• 1999

This paper presents an operation sequence-based approach for determining machine cell layout in a cellular manufacturing environment. The proposed model considers the sequence of operations in evaluating the intercell and intracell movements. In this paper, design of cellular layout has an objective of minimization of total material flow among facilities, where the total material flow is defined as a weighted sum of both intercell and intracell part movements. The proposed algorithm is developed by using genetic algorithm and can be used to design an optimal cellular layout which can cope with changes of shop floor situation by considering constraints such as the number of machine cells and the number of machines in a machine cell.

• Structural Engineering and Mechanics
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• 제16권5호
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• pp.557-580
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• 2003

Laminated composite structures find wide range of applications in many branches of technology. They are much suited for weight sensitive structures (like aircraft) where thinner and lighter members made of advanced fiber reinforced composite materials are used. The orientations of fiber direction in layers and number of layers and the thickness of the layers as well as material of composites play a major role in determining the strength and stiffness. Thus the basic design problem is to determine the optimum stacking sequence in terms of laminate thickness, material and fiber orientation. In this paper, a new optimization technique called Cellular Automata (CA) has been combined with Genetic Algorithm (GA) to develop a different search and optimization algorithm, known as Cellular Genetic Algorithm (CGA), which considers the laminate thickness, angle of fiber orientation and the fiber material as discrete variables. This CGA has been successfully applied to obtain the optimal fiber orientation, thickness and material lay-up for multi-layered composite hybrid beams plates and shells subjected to static buckling and dynamic constraints.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2000년도 추계학술대회 및 정기총회
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• pp.167-170
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• 2000

This paper is concerned with development of a performance evaluation model for material handling system in cellular manufacturing system based on multi-attributes analysis method. We used the AHP(analytic hierarchy process) and fuzzy set ranking methodologies to overcome the special decision problems; those of multi -objective, multi-criterion, and multi-attributes. We proposed a 3-step approaches and we developed a systemic and practical computer program to solve the problems in the proposed methods. Computational experiments are then performed to cellular manufacturing system and show the effectiveness of the proposed model.

• Steel and Composite Structures
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• 제44권5호
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• pp.685-690
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• 2022

In this paper, the equivalent material properties of cellular metamaterials with different types of perforations have been presented using finite element (FE) simulation of tensile test in Abaqus commercial software. To this end, a Representative Volume Element (RVE) has been considered for each type of cellular metamaterial with regular array of circular, square, oval and rectangular perforations. Furthermore, both straight and perpendicular patterns of oval and rectangular perforations have been studied. By applying Periodic Boundary conditions (PBC) on the RVE, the actual behavior of cellular material under uniaxial tension has been simulated. Finally, the effective Young's modulus, Poisson's ratio and mass density of various metamaterials have been presented as functions of relative density of the RVE

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.1083-1088
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• 2004

Zinc air batteries obtain their energy density advantage over the other batteries by utilizing ambient oxygen as the cathode materials, and reusing cathode as recycled form. And specific capacity of zinc powder is as high as 820mAh/g. Our research team succeeded in producing 2.4 Ah class zinc air battery for cellular phone application. In this paper we had studied performance of cathode according to various factors and demonstrated the performance of 2.4 Ah class zinc air battery for cellular phone application.

• 한국전기전자재료학회논문지
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• 제17권9호
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• pp.936-941
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• 2004

In recent years, the rapid growth of portable electronic devices requires the high-energy density characteristics of batteries. Zinc air batteries have specific capacity as high as 820mAh/g. However, Zinc air batteries used for hearing aid applications only so far, because the atmosphere could affect it, and it has weakness in the rate capability. However, recent developments of electrode manufacturing technologies made us to overcome that weakness. And the efforts of applying zinc air batteries to portable electronic devices, especially in cellular phone application have been increased. In this paper, the effects of conducting material and polymer binder in cathode on the electrochemical characteristics were investigated. Our research team succeeded in producing 2.4Ah class zinc air battery for cellular phone application. Its volumetric energy density was 920 wh/l, and gravimetric energy density was 308 wh/kg. The volumetric energy density of our zinc air battery is two times higher than one of lithium secondary battery, and three times higher than that of alkaline manganese battery.

• 콘크리트학회논문집
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• 제15권4호
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• pp.566-573
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• 2003

본 연구에서는 기포콘크리트속에 연속공극율을 증가시켜 흡음률을 높이면서 강도를 증진시킨 강체형 흡음재의 제조를 목적으로 하였다. 실험결과, 기포첨가량을 증가시켜 연속공극률을 높일수록 흡음률이 증가하였으며, 재료두께 5cm인 경우 연속공극률 40%이상에서 평균흡음률 70%이상을 만족하였다. 또한 흡음재 두께의 증가는 중저음영역에서 흡음률 증가를 나타내었으며 평균흡음률 70%이상을 만족하는 기포콘크리트의 비중은 재료두께 5cm에서 0.4이하, 7cm에서 0.6이하로 나타났다. 그리고 평균흡음률 70%이상 만족하는 비중 0.4인 기포콘크리트의 압축강도는 시멘트분말도 3,000$\textrm{cm}^2$/g의 경우 1.37MPa이나, 시멘트분말도 8,000$\textrm{cm}^2$/g에서는 3.34MPa로 증가되었다. 따라서, 연속공극을 갖는 기포콘크리트의 압축강도는 시멘트분말도가 높을수록 증가하는 것으로 사료된다.

• 소성∙가공
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• 제11권8호
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• pp.701-709
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• 2002

Aluminium foam material is highly porous material, which has the complicated cellular structure defined by randomly distributed pores in metallic matrix. This structure gives the characteristic properties which cannot be achieved by any other conventional processes. As the properties of aluminium foam material significantly depend on its porosity, a desired profile of properties can be tailored by changing the foam density. But various defects lead to undesirable effects on the mechanical properties. Mechanical properties are dependent on cell sizes and aspect ratios. Therefore, this paper presents the effects of various processing parameters of various parameters on the mechanical properties. For the sake of this, combined stirring was used to fabricate aluminum foam materials by the parameters. Compression and bending tests were performed to investigate the effects of cell sizes and aspect ratios on the mechanical properties.