• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.161-166
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• 2002

The modification factor( k-factor) of equivalent damping ratio utilized in the current state-of-the-practice to account for the imperfection of reinforced concrete structures in hysteresis loop is investigated. From this, it is found that the current modification factor does not include the effect of cyclic loading, one of the important characteristic properties of earthquake loading. This could be taken into account by considering the energy absorption efficiency based on the cummulative plastic deformation. From the study, it is suggested that the current approach for the modification factor for the equivalent damping ratio should be reformed.

• YAKHAK HOEJI
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• v.29 no.3
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• pp.117-123
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• 1985

A clorimetric determination method of pyruvic acid using hydroxylamine was studied. Hydroxylamine was reacted with pyruvic acid to form complex compound in the presence of Cu(II) ion. Optimal conditions for the quantitative analysis were investigated and the structure of complex was examined spectrometrically. The molar ratio (2:1) and the stability constant ($1.88{\times}10^{4}$) of the complex were measured. It was the characteristic feature of this method that the commonly encountered interfering substances such as fructose, glucose and lactic acid do not infuence the measurement of pyruvic acid.

• Computers and Concrete
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• v.9 no.1
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• pp.35-50
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• 2012

The 2D representative volume element (RVE) for softening quasi-brittle materials like concrete is determined. Two alternative methods are presented to determine a size of RVE in concrete subjected to uniaxial tension by taking into account strain localization. Concrete is described as a heterogeneous three-phase material composed of aggregate, cement matrix and bond. The plane strain FE calculations of strain localization at meso-scale are carried out with an isotropic damage model with non-local softening.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.890-891
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• 2015

본 논문에서는 속도 제어를 위한 가변자속 메모리 모터(Variable Flux Memory Motor)의 특성과 감자전류 산정에 대하여 다루었다. 서론에서는 VFMM에 대한 특징 및 설계를 위한 분석 방안을 제시하였으며, 메모리모터의 동작 원리와, 정밀한 해석 방법은 본론을 통하여 자세히 다루었다. 감자전류는 프라이자흐 모델을 이용하여 초기 자석의 자화량을 비선형 적으로 구한 후 인가된 d축 전류에 따른 변화된 자화량 및 기전력 값들을 반복적인 연산을 통하여 신뢰성 있는 감자전류를 산정하였다.

• Journal of the Korean Society of Industry Convergence
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• v.7 no.2
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• pp.215-220
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• 2004

In this paper, some algorithms for robust stabilization of linerar time - invariant single - input - multi output (SIMO) systems subject to parameter perturbatations are presented. At first, the determination algorithm of the largest stable hypersphere in the parameter space of a given characteristic polynomial with its coefficient perturbations near some stable nominal values is presented. These algorithms iteratively enlarge the stability hypersph ere in plant parameter space and can be used to design a controller to stabilize a plant subject to givien range of parameter ecxursions.

• YAKHAK HOEJI
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• v.30 no.2
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• pp.100-103
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• 1986

The second derivative absorption spectra of acetaminophen in commercial tablet forms were measured without prior separation from other pharmaceutical adjuvants. The second derivative spectra of acetaminophen were found to have no influence on the characteristic absorbance band of it. A plot of 25 sets of the ordinate (Z) values with various acetaminophen concentrations mixed in other additives gave a straight line (correlation coefficient, 0.9999) and the slope was 2.901${\times}10^{-2}Z$ value/($\mu\textrm{g}$/ml). The procedures were sufficiently sensitive, precise and economical for the assay of tablets of acetaminophen.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.18 no.36
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• pp.183-191
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• 1995

When designing a warehouse, one has to recognize that the number of racks in a warehouse takes on only integer value in reality. The existing solution procedures based on noninteger values may result in poor outcomes for the design of a warehouse. This paper deals with the determination of the optimal integer for the number of racks that minimize the total material handling cost associated with the warehouse. An optimum search procedure is proposed here and a number of numerical examples are used to evaluate the efficiency of the proposed procedure.

• Journal of Digital Convergence
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• v.14 no.11
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• pp.459-467
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• 2016

This study was conducted to evaluate and identify what factors influence the satisfaction of the users for the fast-growing social network game based on the mobile. To this end, we looked around the variable product characteristic factor, quality and the consumer characteristic factor, user self-determination. Also we surveyed 211 male and female college students. The first finding was that all the sub-factors of the quality factor had positive effects on the satisfaction of the mobile social network games. The second finding was that all the sub-factors of the self-determination factor had positive effects on the satisfaction of the mobile social network games. The third finding was that only the sub-factors of quality had positive relative effects on the satisfaction of the mobile social network games, in the order of playfulness, usability, functionality from the most to the least. The findings of this study are expected to offer meaningful and practical suggestions for the development of high quality game contents for the user convenience, as well as the academic significance, the expansion of game-related area of research through the break from the traditional research trends, technology and engineering point of view and from the PC-based online game.

• Journal of Power System Engineering
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• v.15 no.3
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• pp.65-69
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• 2011

This paper introduces the multi-coil eddy current sensor and its characteristic in magnetic material gas turbine rotor. In the past, magnetic particle inspection method was used for qualitative defect evaluation in magnetic material gas turbine rotor. And the ultrasonic inspection method was used for quantitative defect evaluation. Nowadays, eddy current method is used in magnetic gas turbine rotor inspection due to advanced sensor design technology. We developed multi-coil eddy current sensor for the rotor dovetail inspection. At first, rotor stress is analyzed for the determination of sensor position and number. The sensor coils are designed to cover the stress concentration area of rotor dovetail. We select optimum frequency according to material standard penetration data and experiment results. The rotor mock-up and artificial defects were made for the signal detection and resolution analysis of multi-coil eddy current sensor. The results show that signal detection and resolution capabilities are enhanced in comparison to the commercialized sensor enough for the gas turbine rotor inspection. So, this developed multi-coil eddy current sensor substituted for commercialized one and it applied in real gas turbine rotor inspection.

• Korean Chemical Engineering Research
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• v.47 no.3
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• pp.368-372
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• 2009

A technique to measure the adsorption characteristic of surface area and pore size distribution is proposed and its performance is examined. While the existing equipment utilizes liquid nitrogen, the proposed uses carbon dioxide at the room temperature leading to the small measuring device with easy operation and short measurement time. The performance of the device has been examined with micro-particle carbon cryogel and bamboo activated carbon. The results from the proposed device compared with those of the adsorption apparatus indicate that the measurement of meso-porous material is comparable but micro-porous material gives some error.