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소화노즐의 분무특성에 대한 설계 변수 영향의 수치해석적 연구
이창효(C. H. Lee),정희택(H. T. Chung),한용식(Y. S. Han),김창(C. Kim) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
Numierical investigation has been performaed to simulate the spray characteristics in mist-spray fire suppression nozzles in sense of design parameters. Three key shape factors in nozzle orifices. I.e. diameter, length and exit shape are chosen as simulation parameters. Fluent with the proper modeling was applied as numerical tools. Spray angles, drop size, and jet velocitys are analyzed for each parameters to find the optimal design conditions.
미분무수 소화시스템의 분무 및 소화 특성 예측을 위한 유동장 수치 시뮬레이션
이창효(C. H. Lee),정희택(H. T. Chung),최병일(B. I. Choi),한용식(Y. S. Han),옥영욱(Y. W. Ok) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
In the present study, numerical simulation has been performed to investigate the characteristics of the mist flow through the fire suppression nozzles and influence of water mist on fire suppression mechanism. The commercial CFD software, FLUENT with the proper modeling was applied in both the internal and external flow region of the spray nozzle. Numerical validation was proved by the comparison of the experimental data in the cold condition. The effect of the heat source on the flow fileds in the spray region were computed for the design purpose.
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,
정희택(H. Chung),이창효(C. Lee),정향남(H. Jung),최병일(B. Choi),한용식(Y. Han),옥영욱(Y. Ohck) 한국유체기계학회 2005 유체기계 연구개발 발표회 논문집 Vol.- No.-
In the present study, numerical simulation has been performed to investigate the characteristics of the mist flow through the fire suppression nozzles. The commercial CFD software, FLUENT with the proper modeling was applied in both the internal and external flow region of the spray nozzles. Applications were done to the full cone nozzle for the operation range of the low pressure and high flow-rate. Numerical validation was proved by the comparison of the experimental data. Parametric study of the key design factors was tried to improve the performance.
미분무수 소화 노즐의 분무 특성 예측을 위한 CFD기법의 적용
정희택(H.T. Chung),이창효(C.H. Lee),최병일(B.I. Choi),한용식(Y.S. Han),옥영욱(Y.W. Ock) 한국전산유체공학회 2006 한국전산유체공학회지 Vol.11 No.4
Numerical simulation has been performed to investigate the characteristics of the mist flow through the fire suppression nozzles. The commercial CFD software, FLUENT with the proper modeling was applied for analyzing both the internal and external flow of the spray nozzles. Computations were made for the full cone nozzle in the operation range of the low pressure and high flow-rate. To validate the present computational procedure, numerical results are compared with measurements in terms of K-factor, SMD, axial spray velocity and spray angles. Numerical results suggested that the present numerical model can be used as an adequate tool for a design purpose of mist-spray nozzles.
서영수(Y. S. Seo),이창효(C. H. Lee),김현식(H. S. Kim),정희택(H. T. Chung) 한국동력기계공학회 2007 한국동력기계공학회 학술대회 논문집 Vol.- No.-
In this study, finite element analysis by means of commercial software was performed to evaluate the structural integrity and operability on horizontal centrifugal pump since it is necessary for the horizontal centrifugal pump on nuclear power plants to be verified among FEM analysis, experimental method, combination of analysis and test. The normal mode analysis is carried out to determine dynamic behavior whether rigid or flexible equipment by comparing fundamental frequency with 33hz. the dynamic characteristic such as model shapes and natural frequency is reviewed in terms of possibility of structural resonance. The static stress analysis was carried out during normal, abnormal load conditions such as a seismic event. The stress results are herein demonstrated and evaluated according to material allowable stress which is complying with ASME code.
정인수(I. S. Jung),이영규(Y. G. Lee),이창효(C. H. Lee),정희택(H. T. Chung) 한국동력기계공학회 2009 한국동력기계공학회 학술대회 논문집 Vol.2009 No.6
In the present study, numerical simulation has been performed to investigate the flow characteristics around the injecting nozzles which are the key parts of water mist fire suppression system. In the water mist fire suppression system (WMFSS), the fine mist droplets smaller than 1,000μmissued from the water mist nozzles suppress the fire plume by the direct cooling, oxygen displacement and attenuation of thermal radiation. For simulation of flow characteristics, the commercial CFD software, named as CFX and FLUENT, were used with the proper modeling. CFX was applied for analyzing the internal flow and FLUENT was applied for analyzing the external flow of water mist nozzles. The flow characteristics of the water mist nozzle found out in this study could be used for predicting the performance of the water mist nozzles for the fire suppression system.
성부현,이창효,김정기 漢陽大學校 基礎科學硏究所 1986 基礎科學論文集 Vol.5 No.-
다결정 ??의 자기적인 성질과 Morin전이를 상온에서의 X선 방법과85~300K의 온도범위에서 Mossbauer 효과에 의해서 연구하였다. X선 회절선은 ??가 단일결정상을 나타내며 결정구조는 α-Fe₂O₃와 같은 trigonal구조를 갖는다는 것을 보인다. 또한 초미세자기장의 온도 의존성과 사중극자 분열의 온도에 따른 변화는 본 연구의 온도범위에서는 Morin전이를 나타내지 않으며, 단일 자기상인 약강자성을 갖는다. 초미세자기장의 온도에 따른 변화에 스핀이론을 적용하였다. 그 결과식은 H(T)=543.42(??)이다. 통계역학적 분석에서, 측정된 이성핵이동의 온도의존성을 잘 설명하는 특성온도 ??를 구하였는데, 이 값들은 α-Fe₂O₃에서 철이온 대신에 In이온을 소량 첨가하는 경우에 감소하였다. 또한 각 온도에서의 이성핵이동값이 0.4~0.5mm/s를 나타내므로 ?? 결정에서의 Fe 이온은 +3라고 말할 수 있다. The magnetic properties and the Morin transition of the ?? have been studied by the methods of X-ray at room temperature and Mossbauer effect in the temperature ranges of 85~300K. The X-ray diffraction patterns show that the crystal is a single phase and the crystal structure is same structure is same structure as that of Alpha-Fe₂O₃. The temperature dependence of the magnetic hyperfine field and the quadrupole splitting tell us that the ?? has no Morin transition and is in a weak ferromagnetic phase within the temperature range of 85~300K. The spinwave theory has been applied to the temperature dependence of the magnetic hyperfine field H(T). The relation obtained from the theory is H(T)=542.42(??). According to the statistical analysis of the temperature dependence of isomer shift, the charateristic temperatures ?? decrease in case replacing a small amount of Fe ions by In ions. The values of 0.4~0.5mm/s in isomer shift tell us that the Fe ions of ?? are ferric.
Deep Level Transient Spectroscopy법에 의한 InAs/InP계 양자점구조의 에너지준위 연구
김진석,박희경,김재훈,김은규,이창효 漢陽大學校 自然科學硏究所 2003 自然科學論文集 Vol.23 No.-
MOCVD (metal organic chemical vapor deposition)장치로 자발형성시킨 InAs/Inp계 양자점구조의 에너지 준위를 DLTS(deep level transient spectroscopy) 측정법을 이용하여 연구하였다. InP 기판의 온도 530℃에서 InAs 양자점을 형성한 다음 InP 덮개층 성장시 성장온도에 따른 InAs 양자점의 물성변화를 조사하기 위해 성장온도를 530℃에 고정시킨 경우와 먼저 530℃ 성장하고 다시 620℃의 온도에서 성장시키는 2단계 성장기법으로 성장시킨 두 종류의 시료를 준비하였다. 이들 시료에 대한 DLTS 측정결과 활성화에너지와 운반자방출단면적은 덮개층 성장시 기판온도를 530℃에 고정시킨 시료에서는 E_c-0.56 eV 와 4×10^(-15)㎠으로 각각 나타났으나, 덮개층 성장온도를 530℃ 와 620℃에서 성장시킨 시료에서는 E_c-0.74eV와 2.46×10^(-12)㎠로 더 크게 나타났다. 이는 고온에서 덮개층 성장시 InAs 양자점과 InP 덮개층사이의 inter-diffusion효과로 고려되었다. 한편, E_c-0.56 eV에너지 준위의 운반자 포획장벽높이는 0.18 eV로 나타났다. We studied on the energy levels of self-assembled InAs/InP quantum dot structures which was grown by metal organic chemical vapor deposition by using deep level transient spectroscopy(DLTS) method. The InAs quantum dots were grown on InP substrate at 530℃. During the growth of InP capping layer, the temperature of the first sample was fixed at 530℃ and in the other case, two step growth at temperatures of 530℃ and 620℃ were used. In the first sample, we could get one electron trap level with the activation energy of E_c-0.56 eV and the emission cross section of 4×10^(-15)㎠. This electron trap level was considered as the quantum dot level. On the other hand, in the second sample, the activation energy and the emission cross section were obtained E_c-0.74 eV and 2.46×10^(-12)㎠, respectively. This result considered as the inter-diffusion effect of InAs quantum dot during the growth at high temperature. In addition, the carrier capture barrier height of E_c-0.56 eV electron trap level is 0.18 eV.