• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.6C
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• pp.241-253
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• 2010

For seismic design of a vertical shaft, three-dimensional Finite Element (FE) analyses were performed to evaluate the accurate response of a vertical shaft and to apply a Response Displacement Method (RDM). Special attention is given to the evaluation of seismic base and response displacement of surrounding soil, estimation of load and loading method. Based on the result, it was found that shear wave velocity of seismic base greater than 1500m/s was appropriate for the seismic design. It was also found that double cosine method which evaluates a response displacement of surrounding soil was most appropriate to consider the characteristic of multi-layered soil. Finally, shape effect of the structure was considered to clarify the dynamic behavior of vertical shaft and it would be more economical vertical shaft design when a vertical shaft was analyzed by using RDM.

• Journal of Astronomy and Space Sciences
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• v.22 no.3
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• pp.249-262
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• 2005

Optimization problems are formulated to calculate optimal impulses for deflecting Earth-Crossing Objects using a Nonlinear Programming. This formulation allows us to analyze the velocity changes in normal direction to the celestial body's orbital plane, which is neglected in many previous studies. The constrained optimization in the three-dimensional space is based on a patched conic method including the Earth's gravitational effects, and yields impulsive ${\Delta}V$ to deflect the target's orbit. The optimal solution is dependent on relative positions and velocities between the Earth and the Earth-crossing objects, and can be represented by optimal magnitude and angle of ${\Delta}V $ as a functions of a impulse time. The perpendicular component of ${\Delta}V $ to the orbit plane can sometimes play un-negligible role as the impulse time approaches the impact time. The optimal ${\Delta}V $ is increased when the original orbit of Earth-crossing object is more similar to the Earth's orbit, and is also exponentially increased as the impulse time reaches to the impact time. The analyses performed in present paper can be used to the deflection missions in the future.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.1
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• pp.17-24
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• 2024

This paper assesses the structural performance of the Daeungbojeon Hall of Magoksa in Gongju, a representative multi-tiered roof traditional timber structure from the Joseon Dynasty, under vertical loads. Employing midas Gen, a structural analysis software, we developed a three-dimensional analysis model closely resembling the actual structure. Static analysis was employed to evaluate the safety and serviceability of the main vertical and horizontal members under vertical loads. While all members met the safety and serviceability criteria, structural weaknesses were identified in the Daelyang of the lower floor, particularly as a transitional beam, necessitating improvement. For the evaluation of dynamic behavior characteristics, eigenvalue analysis was conducted, assuming a relative rotational stiffness of 5% at the main joints. The natural period was determined to be 1.105 seconds, placing it within the category of a Hanok of similar size. The first mode manifested as a translational movement in the forward and backward direction of the building.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2001.05a
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• pp.104-108
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• 2001

복사에 의한 냉난방은, 장시간 재실하는 방이나 소음, 기류에 민감한 장소에 적합하고 에너지 절약면에서도 유효한 냉난방 방식이라고 알려져 있다. 일반적으로 널리 알려져 있는 바닥난방은 실온의 수직분포가 균일함으로서 인체에 쾌적한 난방방식으로 알려져 있다. 이것에 비해, 바닥의외의 벽, 천장을 활용한 냉난방설비의 쾌적성에 대해서는 아직 충분히 검토되고 잇지 않다. 따라서 본 연구는 물순환식 복사 냉난방장치를 이용하여 겨울철의 천장복사난방이 인체에 미치는 생리적, 심리적영향을 밝히고 복사난방의 유용성에 대해서 검토하는 것을 목적으로 한다. 실험은 일본 나라여자대학 인공기후실을 이용하였고, 실험조건은 실온 18$^{\circ}C$, 21$^{\circ}C$, 24$^{\circ}C$ 천장온도 $25^{\circ}C$, 3$0^{\circ}C$, 35$^{\circ}C$의 조건을 조합하여 7조건으로 설정하였다. 또, 상대 습도 40%, 기류속도 0.1m/s 이하로 일정하게 유지시켰다. 생리적반응으로는 피부온14점과 직장온을 30초 간격으로 측정하였고, 혈압, 심박수, 체중, 체지방율을 측정하고 심리적반응으로는 온열감, 쾌적감등의 항목을 10분간격으로 측정하였다.

• Journal of the Korean Vacuum Society
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• v.1 no.3
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• pp.389-394
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• 1992

용액분무법으로 (100) MgO 단결정 기판위에 YBa2Cu3O7-x 초전도박막을 제조하 였다. YBa2Cu3O7-x 초전도 박막의 Y, Ba, Cu 원자의 상대적인 비는 EDX의 검출 한계내에 서 1 : 2 : 3이었고, 이는 분무 용액속의 금속이온의 비와 같았다. YBa2Cu3O7-x 초전도 박 막의 결정구조는 단일 상의 사방구조였으며, 기판에 수직인 c축의 방향으로 grain이 성장되 었고, 격자상수 c0는 11.678$\AA$였다. 95$0^{\circ}C$의 공기중에서 10분간 열처리한 박막의 Tc-on=100K, Tc-zero=80K, Jc=2.5 $\times$ 104A/cm2였고, 95$0^{\circ}C$의 흐르는 산소분위기에서 10분간 열처리한 박막의 Tc-on=103K, Tc-zero=80K, Jc=1.0 $\times$ 105A/cm2였다. 초전도 박막의 미세구 조, grain 크기와 grain 경계폭은 제조후 열처리(post-annealing) 시간과 가스 분위기에 강 한 영향을 받았다.

• Journal of the Korean Chemical Society
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• v.31 no.4
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• pp.352-358
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• 1987

Rate constants for the hydrolysis of para-substituted phenyl N-(p-chlorobenzoyl)chloroformimidate (I) derivatives in 1 : 4 dioxane-water at $25^{\circ}C$ have been determined. Rate data, substituent effect $(\rho\>{\rho}^+)$, product analysis and MO calculation indicate that the uncatalyzed reaction proceeds through an $S_N1$ mechanism involving the formation of azocarbonium ion (II) below pH 3.0, and the base-catalyzed reaction proceeds through an $S_N2$ mechanism via transition state (III) above pH 4.0. The relative stability of four peri planar conformational isomers were (E-ap) > (Z-ap) > (E-sp) > (Z-ap), respectively, and the most stable stereo structures shows that the Y-substituted phenyl group $(C_6H_4-Y)$ occupy vertical $(90^{\circ})$ position on the plane of the benzimidochloroformyl group in (E-ap) conformer. The nucleophilic substitution of water molecule occurs by sigma attack to the activatived azomethine carbon atom of (I) derivatives.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.2
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• pp.114-123
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• 2018

Wind power tower (WPT) has been used to augment the performance of vertical axis wind turbine (VAWT). However, the performance of the WPT depends on several design parameters, such as inner and outer radius, or number of guide walls. Therefore, an experimental study was conducted to investigate efficient design parameters on the WPT. A wind tunnel was utilized and its test section dimension was 2m height and 2.2m width. One story model of the WPT was manufactured with seven guide walls and a VAWT was installed within the WPT. Three different sizes of guide walls were applied to test with various design parameters. The power coefficients were measured along the azimuthal direction in a state of equal inlet velocity in order to compare its performance relatively. The experimental results showed that the gap between the inner radius of the WPT and the rotating radius of the VAWT was a major parameter to improve the performance of VAWT within the WPT.

• Polymer(Korea)
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• v.37 no.5
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• pp.642-648
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• 2013

There is a kind of abnormal noise known to come from the stick-slip mechanism induced by frictional impulses during the sliding of two polymeric plates. In this work, quantitative analysis of abnormal noise is carried out based on experimental results. Some combinations of polymer plates, such as an ABS base-plate contacted to ABS, PP, MIPS, and POM plates, which are well-known materials used in home-appliances, are studied to obtain the best combination of polymer plates in order to reduce the abnormal noise. For the experiments, a rig for the test was set up and a methodology was proposed. In addition, the effects of the surface roughness of the plate, the normal loading force, and the relative sliding speed between the two contact plates were evaluated in order to understand the reason for the abnormal noise. Through this experimental work, the optimal combination of materials was ABS/POM system to reduce the noise in real industrial applications.

• Geophysics and Geophysical Exploration
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• v.11 no.2
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• pp.137-147
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• 2008

Fault rupture directivity of the Odaesan earthquake, which was inferred to be the main cause of the high PGAvalue (> 0.1 g) unusually observed at the near-source region, was analyzed by using the data from the nearby (R < 100 km) dense seismic stations. The Boatwright's method (2007) was adopted for this purpose in which the azimuth and takeoff angle of the unilateral rupture directivity function could be estimated based on the relative peak ground-motions of seismic stations resulting from the nature of the rupture directivity. In this study, the approximate values of the relative peak ground-motions was derived from the difference between the log residuals of the point-source spectral model (Boore, 2003) for the main and secondary events based on the Random Vibration Theory. In this derivation, the spectral difference for a frequency range between the source corner frequencies of main and secondary events was considered to reflect only the effect of the fault directivity. The inversion result of the model parameters for the fault directivity function showed that the fault-plane of NWW-SEE direction dipping steeply to the North with high rupture velocity near upward in SE direction is responsible for the observed high level of ground-motion at the near-source region.

• Journal of Bio-Environment Control
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• v.16 no.4
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• pp.291-296
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• 2007

This study was conducted to investigate the effects of horizontal air flow produced by circulation fans on horizontal and vertical profiles of meteorological factors. The three-dimensional distributions of air speed, air temperature, relative humidity and carbon dioxide $(CO_2)$ concentration were measured with and without the fans in operation. The uniformity of the spatial distribution of meteorological factors decreased as the outside air temperature decreased. In "fans off" condition, spatial variations of $4.7^{\circ}C$ in air temperature, 19% in relative humidity were detected. When the fans were operated, these variations were reduced to 2.2 and 6.3%, respectively. As the fan capacity increased, the difference in air temperature among sampling points decreased. The fan capacity of $0.0104m^3{\cdot}s^{-1}{\cdot}m^{-2}$ was enough to obtain a reasonable air flow in greenhouse. The vertical profiles of air temperature and $CO_2$ concentration were reasonably uniform regardless of measurement height and fan capacity. Further researches on the position of fans to reduce the difference in air temperature along the width and the effects of using a larger number of smaller fans are required.