이산화탄소-수증기 혼합가스에 대한 파장별 회색가스가중합법에서 회색가스재조합에 대한 연구

박원희,김태국,Park, Won-Hee,Kim, Tae-Kuk 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.2

The WSGG-based narrow band model was employed to solve the radiative transfer equations along isothermal and non-isothermal paths through $CO_2-H_2O-N_2$ gas mixtures at 1 atm. When the WSGGM is applied for arbitrary gas mixtures by considering the multiplication property of transmissivity in overlapping bands, the number of gray gases is significantly increased. To reduce the computation time, three different regrouping methods for the gray gases are tested in obtaining the mean absorption coefficient for each gray gas group. Among them, the regrouping method by minimizing the regrouping error shows the best results. For the isothermal media, 10 gray gases show fairly good agreement with the results by statistical narrow band(SNB) model which are regarded as reference solutions. For non-isothermal media, 20 gray gases show good agreement with reference solutions.

최적화기법을 이용한 철도차량 바닥재의 화염 열유속 및 방사율 예측

박원희,윤경범,Park. Won-Hee,Yoon. Kyung-Beom 한국방재학회 2014 한국방재학회논문집 Vol.14 No.3

철도차량 바닥재로 사용되는 합성 고무를 시편으로 하여 콘 칼로리미터 실험을 수행하고 시편의 표면온도, 발화시간 및 질량감소율을 측정하였다. 측정된 결과를 이용하여 임계열유속 및 발화온도를 산출하고, 반발 입자 군집 최적화 알고리즘을 이용하여 시편 표면에서의 화염에 의한 열유속을 예측하였다. 본 연구에서 최적화된 열유속을 이용하여 계산된 표면온도는 실험에서 측정한 표면 온도와 잘 일치하였다. 본 연구에서 제안한 화염에 의한 열유속을 구하는 방법은 철도차량의 화재 시뮬레이션의 신뢰성 확보에 유용한 도구로 활용될 수 있다. Surface temperatures, ignition times and mass loss rates of the synthetic rubber for railway vehicle flooring are measured for different external heat fluxes by the cone calorimeter. The flame heat flux on the surface can reach the better value by applying the repulsive particle swarm optimization algorithm. During optimization process the critical heat flux and ignition temperature are calculated using measured results. Finally we estimated the optimized flame heat flux. The calculated surface temperatures obtained by using optimized flame heat flux on the surface in this study are matched well with those from the test. The suggested process of determining flame heat flux proposed might be a very useful engineering method for ensuring the validity of a fire simulation for railway vehicles.

ALD로 저온에서 증착된 TiO₂ 박막의 막질에 대한 연구

박원희,신정우,양병찬,박만진,장동영,안지환,Park, Won Hee,Shin, Jeong Woo,Yang, Byung Chan,Park, Man-Jin,Jang, Dong Young,An, Jihwan 한국마이크로전자및패키징학회 2016 마이크로전자 및 패키징학회지 Vol.23 No.2

본 논문은 저온(<$150^{\circ}C$)에서 원자층 증착법(ALD)으로 증착된 $TiO_2$ 박막의 물리적, 화학적 막질에 대한 연구 결과를 보여준다. $TiO_2$의 ALD는 TTIP(Titanium(IV)isopropoxide)와 물을 이용하여 진행되었다. $150^{\circ}C$ 미만에서 증착시, ALD $TiO_2$의 성장률은 약 $0.3{\AA}/cycle$로 증착 온도 및 위치에 상관없이 거의 일정한 성장률을 보였다. 또한 SEM분석에서는 $200^{\circ}C$ 이상에서의 증착과 대조적으로, $150^{\circ}C$ 미만에서 증착된 박막은 부드러운 표면을 보였다. 투과전자현미경(TEM) 분석을 통해 이러한 특징이 저온에서 균질한 비정질의 막이 증착되었기 때문이라는 점을 알 수 있었다. 또한 저온 증착임에도 불구하고 종횡비가 1:75인 고종횡비 구조에도 80% 이상의 형상 적응성을 보였다. 그러나 저온 증착의 영향으로 X-선 광전자 분광기(XPS) 분석을 통해 4~7 at% 정도 함량의 탄소 불순물이 검출됨을 확인하였다. This paper covers the study on the properties of $TiO_2$ film deposited by atomic layer deposition (ALD) using TTIP and water at various temperatures including the low temperature range of <$150^{\circ}C$. At low deposition temperature, ALD $TiO_2$ films showed uniform growth rate per cycle ($0.3{\AA}/cycle$), good uniformity, smooth surface, and homogenous amorphicity. They also showed good conformality of >80% on the trench structure with the high aspect ratio of up to 75. However, relatively high concentration of impurities (C~4-7 at%) in the film was observed due to low deposition temperature.

좁은밴드모델을 이용한 실린더 내의 비회색 가스 복사열전달 연구

박원희,정현성,김태국,Park, Won-Hee,Jung, Hyun-Sung,Kim, Tae-Kuk 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.6

Radiative transfer in energy systems such as furnaces, combustors, boilers and high temperature machineries is a significant mode of heat transfer. Although there are many solution schemes suggested for analysis of radiative transfer in multi-dimensional systems, the applicabilities and accuracies of these schemes have not fully tested for nongray gases. Especially reference data for enclosures of non-orthogonal shapes are not yet enough. In this paper we present some precise radiative transfer solutions for a black walled 3-dimensional cylindrical system filled with nongray gases. The SNB(statistical narrow band) model and the ray-tracing method with the T$_{N}$ quadrature set are used for finding nongray solutions. Although the solution method used in this study is not suitable for engineering purposes, the resulting solutions are proved to be quite accurate and can be regarded as the exact solutions and the results presented in this paper can be used in developing various solution schemes fur radiative transfer by real gas mixtures.s.

임플랜트 지지 보철물에서 고정체의 식립위치와 각도에 따른 삼차원 유한요소법적 응력분석에 관한 연구

박원희,이영수,Park Won-Hee,Lee Young-Soo 대한치과보철학회 2005 대한치과보철학회지 Vol.43 No.1

Statement of problem. The implant prosthesis has been utilized in various clinical cases thanks to its increase in scientific effective application. The relevant implant therapy should have the high success rate in osseointegration, and the implant prosthesis should last for a long period of time without failure. Resorption of the peri-implant alveolar bone is the most frequent and serious problem in implant prosthesis. Excessive concentration of stress from the occlusal force and biopressure around the implant has been known to be the main cause of the bone destruction. Therefore, to decide the location and angulation of the implant is one of the major considering factors for the stress around the implant fixture to be dispersed in the limit of bio-capacity of load support for the successful and long-lasting clinical result. Yet, the detailed mechanism of this phenomenon is not well understood. To some extent, this is related to the paucity of basic science research. Purpose. The purpose of this study is to perform the stress analysis of the implant prosthesis in the partially edentulous mandible according to the different nature locations and angulations using three dimensional finite element method. Material and methods, Three 3.75mm standard implants were placed in the area of first and second bicuspids, and first molar in the mandible Thereafter, implant prostheses were fabricated using UCLA abutments. Five experimental groups were designed as follows : 1) straight placement of three implants, 2) 5$^{\circ}$ buccal and lingual angulation of straightly aligned three implants, 3) 10$^{\circ}$ buccal and lingual angulation of straightly aligned three implants. 4) lingual offset placement of three implants, and 5) buccal offset placement of three implants. Average occlusal force with a variation of perpendicular and 30$^{\circ}$ angulation was applied on the buccal cusp of each implant prosthesis, followed by the measurement of alteration and amount of stress on each configurational implant part and peri-implant bio-structures. The results of this study are extracted from the comparison between the distribution of Von mises stress and the maximum Von mises stress using three dimensional finite element stress analysis for each experimental group. Conclusion. The conclusions were as follows : 1. Providing angulations of the fixture did not help in stress dispersion in the restoration of partially edentulous mandible. 2. It is beneficial to place the fixture in a straight vertical direction, since bio-pressure in the peri-implant bone increases when the fixture is implanted in an angle. 3. It is important to select an appropriate prosthodontic material that prevents fractures, since the bio-pressure is concentrated on the prosthodontic structures when the fixture is implanted in an angle. 4. Offset placement of the fixtures is effective in stress dispersion in the restoration of partially edentulous mandible.

Identity

박원희 ( Park Won Hee ) 한국기초조형학회 2019 한국기초조형학회 작품집 Vol.2019 No.2

대향류화염에서의 회색가스재조합 회색가스가중합법의 적용

박원희(Won-Hee Park),김태국(Tae-Kuk Kim) 한국연소학회 2005 한국연소학회지 Vol.10 No.2

동력차의 전장품 열흐름 해석 사례

박원희(Won-Hee Park),윤수환(Su-Hwan Yun),김학범(Hag-Beom Kim) 한국유체기계학회 2018 유체기계 연구개발 발표회 논문집 Vol.2018 No.7

목재 종류별 연소특성 비교 및 데이터베이스 구축 연구

박원희(Park Won-Hee),조영민(Cho Youngmim),김창용(Kim Chang-Yong),나승은(Na Seungeun),이덕희(Lee Duckhee) 한국방재학회 2018 한국방재학회논문집 Vol.18 No.2

As the domestic production of wood materials continues to increase, the risk of fire by wood is also steadily increasing. In this study, combustiblities of wood used as building material in Korea were investigated. We reviewed the pyrolysis model for creating a combustiblity database of wood. Among them, necessary properties were selected to use simple pyrolysis model which can be used for fire safety design of the building and safety analysis of the railway. The purpose of this study is to compare the characteristics of fire safety according to the type of wood by measuring the heat release rate, effective heat of combustion, maximum heat release rate, specific heat, and thermal conductivity coefficient by using cone calorimeter, differential scanning calorimeter, and thermal conductivity meter. The results of this study are expected to be an important factor in predicting future fire simulations and fire safety. 국내 목재 생산량의 지속적인 증가에 따라 목재에 의한 화재 위험성도 지속적으로 증가하고 있다. 이에 본 연구에서는 국내에서 건축자재로 사용되고 있는 목재를 선정하여 연소특성을 알아보았다. 목재의 연소특성 DB를 작성하기 위한 열분해모델을 검토하였으며 그중 건축물의 성능위주 소방설계 및 철도분야 안전성 분석 등에 활용 가능한 간단한 열분해 모델을 이용하여 이를 위해 필요한 물성을 선정하였다. 콘칼로리미터, 시차주사열량 측정계, 열전도계수 측정기 등을 사용하여 열방출률, 유효연소열, 최대 열방출률, 비열, 열전도 계수 등을 측정함으로써 목재의 종류에 따른 화재 안전도 특성 등을 종합적으로 비교할 수 있도록 하고자 하였다. 본 연구 결과는 향후 화재 시뮬레이션 및 화재 강안전도 예측에 중요한 인자로 활용할 수 있을 것으로 기대된다.

RPSO를 이용한 철도사량 바닥 고무의 반응상수 최적화

박원희(Won-Hee Park) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.5