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.

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.

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.

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.

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.

온동터널 화재 시험

박원희(Won-Hee Park),이덕희(Duck-Hee Lee),윤경범(Kyung-Beom Yoon) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12

The Ondon tunnel is not used now where is one of the tunnels in the Janghang line which is from Cheonan to Iksan. The length of the tunnel is 214 m. The location of the fire source is center of the tunnel and the pool fire with heptane is for the fire source. Mock tests are carried out for the various fire sizes, the height and obstructed/open condition of the source. Temperature of the top of the tunnel is measured.

터널 환경측정 시스템 개발 및 측정 I

박원희(Park, Won-Hee) 한국산학기술학회 2015 한국산학기술학회논문지 Vol.16 No.12

터널에 온도, 습도, 풍향, 풍속 등의 환경 데이터를 실시간으로 측정하여 전송 및 화재감지기의 경년시험 등을 수행할 수 있는 시스템을 개발하였다. 개발된 터널 환경측정 시스템은 철도터널 중 금정터널, 솔안터널 및 서울지하철 4호선 터널 등 국내 3개의 대표 터널 현장에 설치가 되어 약 1년 이상 터널환경이 측정되었으며 안정적으로 운용되었다. 또한 서울지하 철 4호선 과천선 본선터널에 설치된 2기의 개발된 터널 환경 측정시스템으로부터 측정된 결과를 분석하였다. 개발된 터널 환경측정 시스템은 무선 통신망을 이용하여 터널 환경을 24시간 연속으로 안전적으로 분석가능하며 터널뿐만 아니라 여러 분야에 활용이 가능할 것이다. We developed a system that can collect and transmit real-time environmental data such as temperature, humidity, wind direction, and wind speed, and equipment performing aging tests on fire detectors. This system was installed in three representative sites of railway tunnels in South Korea such as Gumjung, Solan, Seoul Subway Line 4 tunnels. The systems showed a stable performance and collected environmental data for over a year. We analyzed environmental data collected by two of our developed systems installed in the running tunnels of Gwacheon Line of Seoul Subway Line 4. The developed system was capable of safely analyzing tunnel environments for 24 h straight using a wireless communication network, and has potential for use in a variety of fields other than tunnels.

터널 환경 측정 시스템 개발 및 측정 II -금정터널 측정결과 분석

박원희(Park, Won-Hee),조영민(Cho, Youngmin) 한국산학기술학회 2016 한국산학기술학회논문지 Vol.17 No.4

본 논문은 터널 환경 측정 시스템 개발 및 측정 I -개발 시스템 및 지하철터널 측정- [1]의 후속논문이다. 일반적인 철도터널 형태를 보이는 20.3 km 연장의 고속철도 복선터널인 금정터널에 환경측정장치를 설치하여 약 1년간 환경 측정한 결과에 대하여 논하였다. 월별 터널 내의 온도 및 상대습도에 대하여 측정한 결과를 분석하였으며, 겨울과 여름의 특정 일을 선택하여 측정결과를 분석하였다. 월별 온도의 경우, 터널 내부의 온도가 여름에는 외기의 온도와 거의 유사하였으나, 겨울에 는 현저하게 높았다. 지중 온도가 연중 일정한 상황에서 여름에는 터널이 외기의 영향을 많이 받아 외기와 유사한 온도를 나타냈으나, 겨울에는 지열과 열차에서 발생하는 열 등에 의해 온도가 더 높은 것으로 보인다. 또한 측정장치의 설치 위치별 환경 특성에 대하여 분석하였다. 터널 내부에서는 외기와 바로 연결되어 있는 수직구와 사갱이 본선에 비하여 온도와 상대습 도의 변화가 심하게 나타났는데, 이는 수직구와 사갱이 외기와 바로 연결되어 있어 외기의 영향을 더 많이 받기 때문이다. 이러한 분석 결과는 터널의 환기나 공기질 개선, 온열환경 개선 등의 연구에 폭넓게 사용될 수 있을 것으로 기대된다. This paper is a follow-up paper to the publication, "Development of Tunnel-Environment Monitoring System and Its Installation I - Monitoring System and Measurement in Subway Tunnel" [1]. An environment monitoring system was installed in the 20.3-km-long Gumjung tunnel, which has the general structure of a high-speed double-track railway tunnel. Data were collected for approximately one year. Monthly and daily data were obtained and analyzed for the temperature and relative humidity in summer and winter months. This paper discusses the environmental characteristics at different positions in the tunnel. The results are expected to be widely used in studies on tunnel ventilation and the improvement of air quality and thermal environments.

지하철 본선터널 화재시험

박원희(Won-Hee Park),김동운(Dong-Un Kim),이덕희(Duck-Hee Lee),정우성(Woo-Sung Jung),김학범(Hag-Bum Kim),이동찬(Dong-Chan Lee) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11

지하철 본선터널에서 고온 연기시험을 수행하였다. 고온의 화재연기를 모사하기 위하여 약 1.5㎿의 열방출율의 알콜팬과 연기발생장치를 이용하였다. 화재발생후 9분후에 터널내에 설치된 휀이 순차적으로 작동하여 화재연기가 제어되는지를 확인하였다. 제연 성능 검토를 위하여 풍향, 풍속, 온도, 연기농도 등을 측정하였고 위치별로 화면을 취득하여 분석하였다. Hot smoke test is done in a subway tunnel. Alcohol pans of 1.5㎿ and smoke generators are used for generating hot smoke. The fans equipped with the tunnel are successively run 9 min after smoke generation. Hot smoke is well controlled by fans. Air flow direction and speed, temperature, smoke optical density are measured and many video cameras are used for recording smoke movement in the tunnel.

철도차량 바닥구조물 내화성능 수치 평가

박원희(Won-Hee Park),이덕희(Duck-Hee Lee),정우성(Woo-Sung Jung) 한국철도학회 2011 한국철도학회 학술발표대회논문집 Vol.2011 No.10

Fire resistance of a floor of a railcar is prescribed in the「Guidelines of standard of railcar safety (Minister of Land Transport and Maritime Affairs 2010)」. A floor of a railcar should retain its fire resistance for 15 or 20 minutes according its risk level. To evaluate fire resistance of the floor materials which are composed of ceramic board or aluminum foam with weight lightening fire resistance of railcar floor is numerically analyzed.