• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.12 s.255
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• pp.1196-1202
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• 2006

A MEMS methanol reformer was fabricated and its performance was evaluated in the present study. Catalytic steam reforming of methanol was selected because the process had been widely applied in macro scale reformers. Conventional Cu/ZnO catalyst that was prepared by co-precipitation method to give the highest coating quality was used. The reactor structure was made by bonding three layers of glass wafers. The internal structure of the wafer was fabricated by the wet-etching process that resulted in a high aspect ratio. The internal surface of the reactor was coated by catalyst and individual wafers were fusion-bonded to form the reactor structure. The internal volume of the microfabricated reactor was $0.3cm^3$ and the reactor produced exhaust gas with hydrogen concentration at 73%. The production rate of hydrogen was 4.16 ml/hr that could generate power of 350 mW in a typical PEM fuel cell.

• Journal of Distribution Research
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• v.7 no.2
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• pp.21-44
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• 2003

The entry of large discount stores into small cities such as Choonchun or Wonju have had a profound impacts on the businesses of small-sized retailers. The impacts of the entry by large discount store will be much larger than those of the entry by department store or other small-scale retailers. Most of research studies on the competitive retail structure focused on the change of retailing in the advanced countries dynamically and investigated macro-trends in sales and market share. As a result, they tend to overlook the micro aspects of consumers" perception and actual behaviors. Furthermore, they tend to limit their research scopes to relatively competitive retailers not to overall competitive structures. In this study, we analyze the overall competitive structures by investigating the retailers" characteristics, perceptions of consumers on retailers and actual purchase of products across different types of retailers We could obtain competitive retail structure. Based on that, we discuss the strategies on the revitalization and enhancement of small-sized retailers" productivities.

• Journal of the Korean Regional Science Association
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• v.10 no.2
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• pp.7-16
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• 1994

With the advent of local autonomy in the 1990s, the polemic issue of decentralizing the central government power will undoubtedly come to the fore. The purpose of this study is to reconsider the government functions both at the central and local levels, paritcularly in the fields of urban planning administration. Those policy guidelines administration. Those policy guidelines employed such delegations include : 1) leaving detailed land use regulations to the discretion of local governments; 2) increasing role of local administrations and people regarding development projects; 3) promotion of urban developers as well as public and private partnership; 4) simplifying the procedure related to development applications. In this context, the role of the central government should be redefined; macro-scale policymaking to cope with on-going globalization trends; area-wide coordination among various local bodies ; providing planning standards and information; straining manpower and operation of urban development funds and subsidies.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.516-519
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• 1996

Sub-assembly in ship manufacturing is a sequence of filet joint welding of stiffeners on metal panels and the process is different depending on companies. In this paper, we introduce a new intelligent robotic system of the sub-assembly process in Samsung Heavy Industry, where one shift of 22m * 9m workspace includes one to ten panels and each panel includes up to 10 stiffeners. The inherent problems such as several hundreds of different panels, unstructured task environment and the large scale do not allow a fixed automation, but needs highly intelligent versatile automation. The robotic system is composed of four 14DOF macro-mini robots and a task recognition system. Application of this system has verified the task specification such as low temperature environment(-10.deg. C) and productivity is satisfied successfully.

• Korea-Australia Rheology Journal
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• v.21 no.4
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• pp.245-268
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• 2009

Recent developments in dilute polymer solution rheology are reviewed, and placed within the context of the general goals of predicting the complex flow of complex fluids. In particular, the interplay between the use of polymer kinetic theory and continuum mechanics to advance the microscopic and the macroscopic description, respectively, of dilute polymer solution rheology is delineated. The insight that can be gained into the origins of the high Weissenberg number problem through an analysis of the configurational changes undergone by a single molecule at various locations in the flow domain is discussed in the context of flow around a cylinder confined between flat plates. The significant role played by hydrodynamic interactions as the source of much of the richness of the observed rheological behaviour of dilute polymer solutions is highlighted, and the methods by which this phenomenon can be incorporated into a macroscopic description through the use of closure approximations and multi scale simulations is discussed.

• Transactions of Materials Processing
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• v.16 no.5 s.95
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• pp.348-353
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• 2007

The propagation of a macro-scale crack and the accompanying transformation zone around it was visualized in an Y-TZP ceramic using a mechano-luminescence (ML) technique. The technique allows realistic fractures that take place catastrophically in actual applications to be realistically stimulated. Unlike conventional quasi-static R-curves, the ML technique on a relatively fast time frame permitted a so-called quasi-dynamic R-curve in the crack speed range from 50 to 140 m/sec. to be measured. Effective toughening then commenced and the applied stress intensity factor increased to 27 $MPa{\sqrt{m}}$. The transformation zone height obtained from the ML observations was in good agreement with that predicted by the Marshall model, and coincided with previously observed results for quasi-static conditions by Raman spectorscopy and x-ray analysis.

• Interaction and multiscale mechanics
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• v.2 no.1
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• pp.1-14
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• 2009

This paper proposes an interaction field concept based on the field theory of plasticity. Relative deformation between two arbitrary scales, e.g., macro and micro fields, is defined which can be implemented in the crystal plasticity-based constitutive framework. Differential geometrical quantities responsible for describing dislocations and defects in the interaction field are obtained, based on which dislocation density and incompatibility tensors are further derived. It is shown that the explicit interaction exists in the curvature or incompatibility tensor field, whereas no interaction in the torsion or dislocation density tensor field. General expressions of the interaction fields over multiple scales with more than three scale levels are derived and implemented into the present constitutive equation.

• 한국연소학회:학술대회논문집
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• 2006.04a
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• pp.181-188
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• 2006

Operation parameters for large scale industrial facility such as iron making plant are carefully selected through elaborate tests and monitoring rather than through a mathematical modeling. One of the recent progresses for better energy utilization in iron ore sintering process is the distribution pattern of fuel inside a macro particle which is formed with fines of iron ore, coke and limestone. Results of model tests which have been used as a basis for the improved operation in the field are introduced and a theoretical modeling study is presented to supplement the experiment-based approach with fundamental arguments of physical modeling, which enables predictive computation beyond the limited region of tests and adjustment. A single fuel particle model along with one-dimensional bed combustion model of solid particles are utilized, and thermal processes of combustion and heat transfer are found to be dominant consideration in the discussions of productivity and energy utilization in the sintering process.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.649-654
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• 2003

This paper is focused on the research of the ultra precision linear motor by using piezo stack actuators. The development of linear motor which can be controlled nano or micro scale is necessary for the precision manufacturing. Self-moving-cell principle is used for the design of linear motor Self-moving-cell linear motor is consisted of three cell structures, and each cell has two shells and one piezo-stack actuator. Each cell can do clamping and moving by two shell structures. The shell structure deformation by piezo stack actuator can move the linear motor by losing the clamping between the shall and guideway. This paper presents the design, manufacturing and test of the motor.

• International Journal of Contents
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• v.3 no.3
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• pp.20-25
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• 2007

Standards impact the economy in various ways. Moreover, intense competition exists between a variety of standards in this era of globalization. This paper quantifies the economic effect of multiple standards in the Information Communications and Technology (ICT) sector. Thus, it identifies and specifies which standard applies when economic gains exist. A model is developed which quantifies the magnitude of the economic effect of multiple standards as compared with a single standard or no standard. The model allows for both the micro- and macroeconomic gains from standardization to be quantified. Preliminary estimates indicate that at the macro level the multiple standards multiplier is approximately three. That is for every dollar invested, the gain is on the order of three dollars. Although not as robust. preliminary results indicated a similar economic gain at the micro level Overall, multiple standards dominate a single standard. This paper applies the model to IMT-2000, an example of multiple standards, to demonstrate this approach to quantify the standards economic effect.