• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1997년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 1997
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• pp.159-166
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• 1997

The purpose of this thesis is to derive a theoretical model of the hysteretic resistance of the visco-elastic damper based on test results of harmonic excitation and to investigate of the basis of theory and experiment the effect of vibration control and response characteristics of portal frames degree vibration systems provided with the damper. The behaviour of a visco-elastic degree under dynamic loading is idealized by a model of the theory of visco-elasticity, i.e. a four-parameter model formed as a parallel combination of Maxwell fluid and Kelvin-Voigh models and its constitutive equation is derived. The model parameters are determined for a tested damper from the datas of harmonic excitation tests. The theoretical model of the damper is incorporated in equation fo motion of single degree of freedom. A computer program for solving the equation is written using Runge-kuttas's numerical integration scheme. Using this analysis program test cases of the earthquake excitation are simulated and the results of the simulation are the results of the simulation are the results of the simulation are compared with the test results.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.519-526
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• 2003

In this paper, a Fiber Bragg Grating (FRG) sensor system is described and FBGs are well-suited for long term and extremely severe experiments, where traditional strain gauges fail. In the system, a reflect wave-length measurement method which employs a tunable light source to find out the center wave-length of FBG sensor is used. We apply the FBG system to nuclear energy Power Plant for structural integrity test to measure the displacement of the structure under designed pressure and to check the elasticity of the structure by measuring the residual strain. The system works very well and it is expected that it can be used for a real-time strain. temperature and vibration detector of smart structure.

• 한국정밀공학회지
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• 제13권4호
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• pp.53-60
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• 1996

In the conventional linear elasticity, sound speed is determined by only elastic modulus and density of the medium. In actual, however, sound speed depends on the stress and this dependency becomes nonlinear as the stress increases. These phenomena can be introducing nonlinear elastic modulus. In this paper, relationships between nonlinear elastic modulus up to 4th order and the internal status of materials are discussed through computer simulations and experiments. For the measurement of sound speed, a new type of measurement system using ultrasonic wave is proposed on the basis of ultrasonic pulse echo method which has been generally used in nondestructive ultrasonic test equipment. In order to confirm the stress dependency of sound speed, several experiments are carried out for alumina specimen.

• 한국해양공학회지
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• 제27권3호
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• pp.29-35
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• 2013

The exploration areas for maritime resources such as oil and natural gas have gradually moved to deep sea areas. It has become difficult to use existing fixed marine structures, which are very costly to build, because that have reached the uppermost economic limit. Therefore, floating marine structures and flexible marine structures are preferred. In particular, slender bodies such as risers and pipes are important parts of ocean depth marine structures. These slender bodies have more flexible structural characteristics in deep water areas because their overall length becomes longer and thediameter/length slenderness ratio gets smaller. In addition, the dynamic behavior of slender bodies becomes complicated as external forces such as tides and waves act on it directly. In this study, in order to solve these problems, we performed model tests in a 2-D wave basin using flexible slender bodies with different modulus of elasticity values. As a result, we compiled statistics and compared the behaviors of flexible slender bodies with respect to the effect of the modulus of elasticity. We expect that the results could be used as reference data for the design of structures with flexible elements.

• Computers and Concrete
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• 제25권6호
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• pp.551-563
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• 2020

This paper investigates the artificial neural network (ANN) to predict the dimensionless parameters for the maximum contact pressures and contact areas of a contact problem. Firstly, the problem is formulated and solved theoretically by using Theory of Elasticity and Integral Transform Technique. Secondly, the contact problem has been extended based on the ANN. The multilayer perceptron (MLP) with three-layer was used to calculate the contact distances. External load, distance between the two quarter planes, layer heights and material properties were created by giving examples of different values were used at the training and test stages of ANN. Program code was rewritten in C++. Different types of network structures were used in the training process. The accuracy of the trained neural networks for the case was tested using 173 new data which were generated via theoretical solutions so as to determine the best network model. As a result, minimum deviation value (difference between theoretical and C++ ANN results) of was obtained for the network model. Theoretical results were compared with artificial neural network results and well agreements between them were achieved.

• 동아시아식생활학회지
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• 제8권2호
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• pp.162-173
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• 1998

The effect of soybean addition to the preparation of Jeung-Pyun(Korean fermented rice cake) and the fermentational characteristics of Jeung-Pyun dough were determined. Jeung-Pyun dough composed of rice 100g, soybean 20g, water 40g, salt 0.8g, sugar 15g and Tak-ju 30g was fermented for up to 20hours. the numbers of total microbes, yeasts and lactic acid bacteria in the dough during fermen-tation increased rapidly during 5 hours of fermentation, but Leuconostoc mesenteroides during 7 hours of fermentation, Generally, there were many more microbes in the Jeung-Pyun dough with soybeans than in the Jeung-Pyun dough with rice. The volume of 7 hour fermented Jeung-Pyun was most massive, especially in the soybean added Jeung-Pyun. 1% dextran-added rice Jeung-Pyun, the volume of steamed cake was increased more than that of rice Jeung-Pyun, but is was not as bulky as in the soybean-added cake. In the sensory evaluation of the test cake products, the 7 hour fermented cake was preferred by nost. As for instrumental characteristics, the 7 hour feremented Jeung-Pyun showed the lowest values for hardness and elasticity, brittleness and chewiness. The rice Jeung-Pyun showed were stored at 2$0^{\circ}C$ the hardness, brittleness and cohesiveness of rice Jeung-Pyun were respectively increased rapidly after 5 days of storage. The cohesiveness, elasticity, brittleness, chewiness, gumminess of both rice Jeung-Pyun and soybean-added Jeung-Pyun were decreased with storage time.

• 한국기계가공학회지
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• 제17권2호
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• pp.137-144
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• 2018

This study describes the 3D design and analysis of a composite insulation boom of an aerial work platform for electric work. Structural analysis of the composite insulation boom was performed using ANSYS and the total deformation, equivalent stress, and normal elasticity were investigated at 150 mm, 500 mm, 1,000 mm, and 1,500 mm using a mounted strain gauge. The results of the analysis and test were similar in a linearly increasing slope and the difference in the strain value was about 10%. This difference depends on the compressive force in the manufacturing process.

• 한국잠사곤충학회지
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• 제51권1호
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• pp.41-47
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• 2013

In this study, silkgland powder of silkworm were investigated to see possibility for cosmetic powder materials. To test possibility as a baby powder cosmetics, total content rate of amino acids, DPPH free radical scavenging assay, MTT assay, and clinical trial were done. According to the result of the analysis of the amino acids of silkgland powder, serin (26.77%) content was the highest and asparatic acid (15.47%), and glycine (9.62%) were followed. DPPH free radical scavenging activity of silkgland powder was lower than vitamin C by 82.3% and 97%, respectively, which is relatively good. And the moisture and elasticity effect were increased in silkgland powder compared to control cosmetics by 210% and 185%, relatively. Thus, these results suggest that silkgland powder of silkworm may have beneficial properties as a material for cosmeceuticals.

• 대한토목학회논문집
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• 제10권4호
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• pp.113-122
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• 1990

도로(道路)의 노반(路盤)에 교통하중(交通荷重)이 반복해서 가해질 경우 흙 구조물의 설계기준을 얻기 위해 현장시험이 행해지고 있으나, 본 연구는 지금까지 잘 알려지지 않은 흙의 동력학적(動力學的) 성질(性質), 특히 반복응력(反復應力)을 받을 때의 성질을 규명한 것으로 유변학적(流變學的) 모델 해석에 의해 흙의 항복응력(降伏應力) 탄성계수(彈性係數)를 구하고 이에 대한 반복응력재하의 영향에 대해서 고찰(考察)한 것이다. 항복응력(降伏應力)은 재하횟수가 많을 수록 경화(硬化) 효과(效果)가 현저하므로 그 값이 크고, 어느 재하횟수에 달하면 한계치에 접근한다. 또한 탄성계수(彈性係數)는 반복응력이 작은 경우에는 재하횟수가 많을수록 현저하게 증가하고, 반복응력이 커지면 반대로 감소한다.

• 기술혁신학회지
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• 제6권3호
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• pp.279-297
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• 2003

The purpose of this paper is to analyze the determinants of company R＆D investment with zero observations by using the data of R＆D Scoreboard published by Ministry of Science and Technology(2002). Conventional parametric approach to dealing with zero investments is not robust to heteroscedastic and/or non-normal error structure. Thus, this study applies symmetrically trimmed least squares(STLS) estimation as a semi-parametric approach to dealing with zero R&D investments. The result of specification test indicates the semi-parametric approach outperforms the parametric approach significantly. Moreover, the results of the study provide various implications as summarized below. The R&D investment of IT company is larger than that of non-IT company. The R&D investment has a positive relation to foreigners' investment ratio. The higher degree of financial self-reliance is, the larger the R&D investment is. Firm size variables such as sales amount and the number of workers are positively related to R&D investment. The sales elasticity of R&D investment is larger than one. However, the workers elasticity of R&D investment is smaller than one.