• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 춘계학술대회 논문집
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• pp.49-51
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• 2009

Photonic crystal is a dielectric materials or a set of different dielectric materials with periodic structure of refractive index. Line defect obtained by leaving out a row of rod along the $\Gamma$-X direction. We showed the change of group velocity in waveguide mode and found a small group velocity. Characteristic of the small group velocity described by electric field distribution. As the phase variation, small group velocity confirmed from positive to negative.

• 한국염색가공학회:학술대회논문집
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• 한국염색가공학회 2012년도 제46차 학술발표회
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• pp.100-100
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• 2012

상품성이 떨어지는 B, C급의 Split leather에 감온 기능성 Film을 부착하고, Film 부착 공정에서 유성 접착제의 사용을 배제한 친환경적인 고급 Laminated split leather를 제조 하였다. 온도에 따라 색이 변하는 감온 Microcapsule 염료를 이용한 Film의 색도, Touch감과 신장 등의 최적조건을 찾는 실험으로서 수성 PU 접착제, Wetting&levelling agent, 증점제, 감온 microcapsule 염료를 상온에서 혼합하여 Film을 제조한 다음 수성 PU 접착제와 Urethane용 경화제를 혼합한 접착제를 이용하여 가죽에 부착시켰다. 감온 microcapsule자체의 색도가 떨어지므로 두 번 코팅하는 방법으로 이 문제점을 보완 하였으며, 감온 microcapsule 염료의 함량에 따른 물성 평가를 하였고, 감온 microcapsule 염료를 이용한 Film 공정을 확립 하였다.

• Wind and Structures
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• 제12권5호
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• pp.401-412
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• 2009

A method is applied for the estimation of structural damage of tall slender structures using natural frequency and displacements measurements by GPS. The relationship between the variation in the global stiffness matrix (or in the stiffness of each finite element) and the change in the natural frequencies of the structure is given. In engineering practice the number of frequencies which can be derived by GPS measurement of long-period structures will be equal to one, two or three first natural frequencies. This allows us in initial studies to detect damage with frequency changes based on forward methods in which the measured frequencies are compared with the predicted analytical data. This idea, of health monitoring from possible changes to natural frequencies, or from a statement of excessive displacements is applied to the Stuttgart TV Tower.

• 태양에너지
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• 제19권2호
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• pp.29-36
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• 1999

Heat transfer characteristics of a low temperature latent heat storage system during the heat storage stage was examined for the circular finned tubes using fatty acid which shows the big density difference during melting as phase change materials. The heat storage vessel has the dimension of 530 mm height, 74 mm inside diameter and inner heat transfer tube is 480 mm in height and 13.5 mm outside diameter. Hot water was employed as the heat transfer fluid. During the heat storage stage, it was found that both conduction and natural convection were the major heat transfer mechanism. It was also found that the effect of natural convection on the heat transfer was more significant for the unfinned tube system than that for the finned tube system. The experimentally determined overall heat transfer coefficients were in the range of $50{\sim}250W/m^2K$ and the correlation for natural convection heat transfer as a function of Nusselt and Rayleigh number was proposed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.111.4-111
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• 2001

In this paper, an adaptively tuned dynamic absorber is proposed. The adaptively tuned dynamic absorber is a dynamic absorber whose stiffness is tuned so that the natural frequency of the absorber coincides with the operating or natural frequency estimated by an adaptive algorithm. The feature of this absorber is as follows. It has an electrodynamic device for the stiffness control. Using Lorenz´s force, it changes the stiffness by changing the applied current. The change of stiffness results in the natural frequency shift, because its mass and damping coefficient are fixed. We may reduce the vibration of the overall system by tuning the natural frequency of the dynamic absorber to the resonant frequency of the structure, when the dominant single tone oscilation occurs in the system ...

• 한국농림기상학회:학술대회논문집
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• 한국농림기상학회 2005년도 추계 학술발표논문집
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• pp.168-174
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• 2005

• 한국철도학회논문집
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• 제8권1호
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• pp.21-26
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• 2005

The effects of carbon black on the fatigue lift and the fracture morphology and the carbon black dispersion of the carbon-black filled natural rubbers, for the vibration-proof, were investigated. Different kinds of carbon blacks resulted in different fatigue lift and fracture morphologies, which are classified by micro-scale and macro-scale fracture morphologies. These results be related to the size distribution of carbon black particles, the development of the carbon black agglomerate and the combine forces between the carbon black and the natural rubber.

• Structural Engineering and Mechanics
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• 제29권5호
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• pp.531-550
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• 2008

This paper adopts the numerical assembly method (NAM) to determine the exact solutions of natural frequencies and mode shapes of a multi-span and multi-step beam carrying a number of various concentrated elements including point masses, rotary inertias, linear springs, rotational springs and springmass systems. First, the coefficient matrix for an intermediate station with various concentrated elements, cross-section change and/or pinned support and the ones for the left-end and right-end supports of a beam are derived. Next, the overall coefficient matrix for the entire beam is obtained using the numerical assembly technique of the conventional finite element method (FEM). Finally, the exact solutions for the natural frequencies of the vibrating system are determined by equating the determinant of the last overall coefficient matrix to zero and the associated mode shapes are obtained by substituting the corresponding values of integration constants into the associated eigenfunctions.

• 설비공학논문집
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• 제13권12호
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• pp.1255-1265
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• 2001

A numerical study has been conducted to characterize the transient flow in a utility gas turbine burning natural gas. The solution domain encompasses the supply gas pressure regulator to the combustor of the gas turbine that employs multi-nozzle fuel injectors. Some results produced for verification in the present study agree suite well with the experimental ones. It is found that the total gas flow may decrease noticeably during its combustion mode change, which would be the reason of momentary combustion upset, when a reference case of opening ratios of control valves in the system is applied. Several parameters are then varied in order to make the total gas flow stable over that period of time. Results of this study may be useful to understand the unsteady behavior of combustion system burning natural gas.

• 한국염색가공학회지
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• 제13권4호
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• pp.241-248
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• 2001

Natural indigo dyeing has been used mainly on cellulosic fibers and silk during the course of history in Korea. In order to extend the usage of this one of the most important natural dyes, its dyeability on wool fabrics has been studied to find out the optimum dyeing condition for wool fiber which is susceptible to alkaline medium. The dyeing method used was hydrosulphite vat of extracted dye. K/S values of dyed fabrics were investigated to analyze the dyeability of natural indigo on wool fibers and colors were measured through $L^*,\;a^*,\;b^*$ and Munsell Values. Highest K/S values were obtained at the temperature of 60(C and pH 7 to 8. The Munsell Values for hue of wool fabrics dyed with extracted indigo powder using hydrosulphite vat fell mostly in PB range. As the dyebath pH increased, blueness increased. Different dyeing conditions resulted in change of colors of dyed fabrics due to the difference in amounts of indigotin and indirubin contents within the dyed fiber as shown by HPLC.