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김찬희(C. H. Kim),정희택(H. T. Chung),배진수(J. S. Bae),이준호(J. H. Lee),이석순(S. S. Lee) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.11
The piping systems in the steam-driven power engines lie under the cyclic condition of thermal expansion and contraction by superheated steam. These phenomena might cause some severe damages on the pipes and the accessory devices. To avoid these damages, the calculation of the proper strength and the consideration of the reduced resultant forces on the materials are needed. In the present study, numerical investigations on the effects of the thermal deformation of the industrial piping system were performed with comparison of the design data. Commercial software, ABAQUS with the thermal-fluidic loadings based on the design conditions was used for the thermal stress analysis of the piping system and the experimental design was used for the rearrangement of the initially-designed pipe supporters.
김찬희(C. H. Kim),정희택(H. T. Chung),배진수(J. S. Bae) 한국동력기계공학회 2007 한국동력기계공학회 학술대회 논문집 Vol.- No.-
Piping systems in steam-driven power engines are heated and pressurized by superheated steam. In this process, piping systems are deformed by high temperature and high pressure. These deformations occur damage on piping systems itself or peripheral equipment. The present study is aimed at estimating the deformation of piping systems and optimizing the arrangement of pipe supports using finite element method. The rearrangement of the initially-designed pipe supporters is suggested through the comparison of the deformation results.
김찬희(C. H. Kim),정희택(H. T. Chung),배진수(J. S. Bae),정인수(I. S. Jung),이석순(S. S. Lee) 한국동력기계공학회 2009 동력시스템공학회지 Vol.13 No.6
The piping systems in the steam-driven power engines lie under the cyclic condition of thermal expansion and contraction by superheated steam. These phenomena might cause some severe damages on the pipes and the accessory devices. To avoid these damages, the calculation of the proper strength and the consideration of the reduced resultant forces on the materials are needed. In the present study, numerical investigations on the effects of the thermal deformation of the industrial piping system were performed with comparison of the design data. Commercial software, ABAQUS with the thermal-fluidic loadings based on the design conditions was used for the thermal stress analysis of the piping system. From the analysis of the initially-designed pipe supporters, the rearrangement was suggested to improve the piping design.
이동식 미분무수 노즐의 소화 특성에 대한 수치 시뮬레이션
배강열(K. Y. Bae),정희택(H. T. Chung),김형범(H. B. Kim),김찬희(C. H. Kim),이창효(C. H. Lee),김창(C. Kim) 한국동력기계공학회 2007 한국동력기계공학회 학술대회 논문집 Vol.- No.-
In the present study, the numerical investigation on the effects of water mist spray has been carried out for the fire suppression characteristics. The FDS are used to simulate the interaction of fire plume and water mists, and program describes the fire-driven flows using LES turbulence model, the mixture fraction combustion model, the finite volume method of radiation transport for a non-scattering gray gas, and conjugate heat transfer between wall and gas flow. The numerical model is consisted of a rectangular of L×W×H=4.0×4.0×2.5 m and a water mist nozzle that be installed 1.0 m from pool, and the whole walls are assumed the open. In the study, the parameter of simulation has two type that one is consisted of 24 hole on the primary flow surroundings and the other has 8 hole except the primary flow. Finally, the nozzle type that has 24 hole is appeared lower the characteristic of fire suppression than another type because of the flow through many holes is bad impact for the primary flow. The extinguishing time is obtained 65 sec in case of B-type and 170 sec in case of A-type, and B-type showed high effect of fire suppression about 2.6 times than A-type,
오리피스형 분사노즐에서 작동유체의 온도변화에 따른 K-factor에 관한 연구
배강영(K. Y. Bae),김찬희(C. H. Kim),정희택(H. T. Chung),김형범(H. B. Kim) 한국동력기계공학회 2007 한국동력기계공학회 학술대회 논문집 Vol.- No.-
In the present study, the numerical simulation has been performed to investigate K-factor for temperature variation of working fluid in spray nozzle with orifice. The commercial CFD software, Fluent with the proper modeling was applied for analyzing the internal of the spray nozzle. Numerical result for K -factor at 20℃ agrees with the experimental result that it applied n=0.5 within about 7% error. The pressure drop inside nozzle is showed 20% passing swirler, 70% in the region between the outlet of swirler and the orifice and 10% at the outlet of orifice. As the operating pressure is increased, K -factor is decreased by effect of flow resistance at the inlet of swirIer passing it. The temperature increase of working fluid reduced the flow rate according to reducing of density, and average 1.23% decrease is showed in the present research.
SiO<sub>2</sub>/TiO<sub>2</sub>/ZrO<sub>2</sub> 광대역 반사방지막의 제작 및 광학적 특성 분석
강만일,류지욱,김기원,김찬희,백영기,이동현,이성룡,Kang, M.I.,Ryu, J.W.,Kim, K.W.,Kim, C.H.,Baek, Y.K.,Lee, D.H.,Lee, S.R. 한국진공학회 2008 Applied Science and Convergence Technology Vol.17 No.2
$SiO_2/TiO_2/ZrO_2$ broadband anti-reflective multi-layer thin films were prepared at room temperature by RF sputtering system. Optical constants and structural properties on each layer of films were analyzed by spectroscopic ellipsometer and transmittance spectra of the films were measured by $UV-V_{is}$ spectrophotometer in the range of 300$\sim$900 nm. To evaluate the films, we compared the measured and analyzed spectra with designed spectra. We investigated influence of discrepancy of thickness and refractive indices of each layer on changes of the transmittance spectra. It was found that refractive indices and shape of dispersion of deposition materials are more contributed to changes of the transmittance spectra than thickness of layer. RF 스퍼터링 시스템을 이용하여 $SiO_2/TiO_2/ZrO_2$ 광대역 반사방지막을 단계별로 제작하였고, 분광타원계와 $UV-V_{is}$ 분광광도계를 이용하여 박막의 두께, 굴절률 및 투과율 스펙트럼을 300$\sim$900nm의 파장 영역에 걸쳐 측정 및 분석하였다. 측정 및 분석된 박막의 두께, 굴절률 및 투과율 스펙트럼을 설계값과 비교 평가한 결과 각층의 두께, 굴절률의 차이에 따른 투과율의 변화를 분석할 수 있었고, 박막의 두께보다는 굴절률과 굴절률의 분산형태가 투과율의 변화에 더 크게 기여함을 알 수 있었다.
자연과학편 : 운동부하(運動負荷) 후(後) 혈중(血中) 무기질(無機質) · 효소(酵素) · 중성지방(中性脂肪)의 변화(變化)
이명천(MyungChunLee),김재호(JeaHoKim),강신일(ShinIllKang),김찬희(C.H.Kim) 한국체육학회 1986 한국체육학회지 Vol.25 No.2
The purpose of this research was to compare the changes of minerals, ferment, and trig·levels of the athletes group with non-athletes group on plasma after 100 meters swimming and 20 meters subaqueous swimming respectively.The results were obtained.1. At the test of NA, K, CL, CA, P, LDH, SGOT, SGPT, BUN, U.A, and TRIG, all of athletes and non-athletes group skewed normal range.2. After swimming, the changes of NA, CL in non-athletes group were more decreased by 0.2meq / ℓ, 1.75meq / ℓ respectively than those of athletes group. The changes of K in both groups were level with that the rest.3. After swimming, the changes of P in athletes group and non-athletes group were decreased by o.195㎎ / ㎗, 0.4㎎ / ㎗ and the changes of TRIG in athletes group was same as that of the rest. But that of TRIG in non-athletes group was decreased by 1.5㎎ / ㎗.4. After swimming, the changes of LDH, SGOT, SGPT in both groups were increased and the changes of LDH and SGOT in non-athletes group were the highest increase among them by 8.25 unit / ℓ, 3.25unit / ℓ.5. After swimming, the changes of BUN and U.A in all of both groups were increased by 1.5㎎ / ㎗, 0.4㎎ / ㎗.