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강바닥판 종리브와 횡리브 교차부의 피로거동에 대한 종리브내 다이아프램의 영향
최동호,최항용,최준혁,Choi, Dong Ho,Choi, Hang Yong,Choi, Jun Hyeok 한국강구조학회 2000 韓國鋼構造學會 論文集 Vol.12 No.3
본 연구에서는 강바닥판의 실물 대형시험체를 제작하여 정적시험 및 피로시험을 실시하였다. 정적 및 영향면 재하시험 결과를 통하여 다이아프램의 유무에 따른 강바닥판 슬릿부의 면내와 면외응력을 검토하였으며, 피로시험결과로부터는 강바닥판의 피로거동, 피로균열의 발생과 진전에 대한 연구를 수행하였다. 다이아프램이 설치된 상세는 설치되지 않은 상세에 비하여 지점조건에 상관없이, 종리브 횡리브 교착부의 종리브측으로는 약 50%의 응력경감효과가 있으나, 횡리브측 하단부에는 오히려 상당히 큰 응력을 야기함을 알 수 있었으며, 피로균열 진전해석결과로부터는 슬릿부의 노치에 의한 초기균열길이가 피로균열성장에 상당한 영향을 끼치고 있음을 알 수 있었다. 측정자료와 FEM 해석을 통하여 공칭응력과 핫스폿응력에 의한 피로강도를 추정한 결과, 다이아프램이 설치되지 않은 상세는 규정된 피로등급에서 안전한 것으로 판단되나 다이아프램이 설치된 상세는 피로등급이하의 거동을 보였다. This study investigates the mechanical behavior on trough rib to crossbeam joint in orthotropic steel plate decks, specially emphasizing on the effect of diaphragm inside trough rib on the fatigue behavior of slit by static and fatigue tests. In particular, the effects of diaphragm on in-plane stress and out-of-plane stress, stress concentration, propagation of fatigue cracks at the silt are studied. With the result of experiment and numerical analysis, we have estimated the fatigue strength using the nominal stress and hot-sport stress. The details with diaphragm have occurred about 50% stress reduction at trough rib part of trough rib to crossbeam joint than the detail without diaphragm, however, the lower parts of crossbeam have occurred much more stress. Initial crack size or slit have an considerable influence on the propagation of fatigue cracks due to V-notch. The fatigue strength category of the details without diaphragm has higher value than fatigue limit, whereas that of the details with diaphragm is estimated lower than fatigue limit.
장대레일 궤도의 온도좌굴 거동에 미치는 열차하중의 영향
최동호,김호배,Choi, Dong Ho,Kim, Ho Bae 한국강구조학회 2000 韓國鋼構造學會 論文集 Vol.12 No.6
The present study investigates the influences of vehicle induced loads on the thermal buckling behavior of straight and curved continuous welded rail (CWR) tracks. Quasi-static loads model is assumed to determine the uplift region, which occurs due to the vertical track deflection induced by wheel loads of vehicle. The lateral loads of vehicle induced by weight, the speed, the superelevation and curvature of track, and other dynamic vehicle track interaction, are included in the ratio of lateral to vertical vehicle load. Parametric numerical analyses are perfomed to calculate the upper and lower critical buckling temperatures of CWR tracks, and the comparison between the results of this work and the previous results without vehicle is also included. 본 연구에서는 궤도의 좌굴해석 및 그 결과를 통해 열차하중이 직선 및 곡선 장대레일 궤도의 온도좌굴 거동에 미치는 영향에 대해 평가하였다. 차량을 고려한 온도좌굴 해석은 바퀴하중하에서 장대레일 궤도의 수직 처짐에 기인한 상향처짐을 결정하기 위해 유사정적 하중모델을 가정하였으며, 차량의 무게와 속도, 궤도의 곡률, 캔트, 그외의 열차와 궤도의 동적인 상호작용으로 인한 횡방향하중은 열차의 수직하중에 대한 수평하중 비에 포함하여 수행하였다. 수치적 해석을 통해 장대레일의 상부 및 하부좌굴온도를 구하였고, 이런 해석결과들을 기존의 열차하중을 포함하지 않은 정적 좌굴해석결과들과 비교하였다.
최동호,이동환,정성철,Choi, Dongho,Lee, Dong Hwan,Jung, Sung-Chul 대한유전성대사질환학회 2005 대한유전성대사질환학회지 Vol.5 No.1
Orthotopic liver transplantation is the treatment of choice for inherited metabolic diseases. However, the supply of donor organs is limiting and therefore many patients cannot benefit from this therapy. In contrast, hepatocytes can be isolated from a single donor liver. They can be transplanted into several recipients, and this procedure may help overcome the shortage of donor livers. A great deal of work with animal models indicates that hepatocytes transplanted into the liver or spleen can survive, function, and participate in the normal regenerative process. Recent clinical studies suggest that hepatocyte transplantation may be useful for bridging patients to whole organ transplantation and for providing metabolic support during liver failure and for replacing whole organ transplantation in certain inherited metabolic diseases. Nowadays, hepatocytes from various stem cells have been regarded as an another cell source for treatment of inherited metabolic diseases. Although cell therapy using stem cells for inherited metabolic disease patient has been accepted only as an experimental trial yet, hepatocytes from stem cells can solve a lot of obstacles in the treatment of inherited metabolic diseases.
최동호,박완순 한국구조물진단유지관리학회 2011 한국구조물진단학회 학술발표회논문집 Vol.2011 No.9
Although the existing formulas are widely used in the field, the total tension force estimated using these formulas is not accurate. The existing formulas do not consider the exact deflection curve, features of nonlinear oscillation, and stretching force due to self-weight. In this study, a new method was developed to calculate the total tension force of the cable. In the new method, the total tension force of the cable consists of the applied axial load and the stretching force due to self-weight. A field test showed that it is necessary to add the stretching force due to self-weight to the estimated axial load and that the new method can be used to calculate the total tension force of cables in cable supported bridges such as the extradosed bridge and the cable stayed bridge.
단자유도 시스템의 선형응답과 비탄성응답에 미치는 PSD함수의 영향
최동호,이상훈,김용식,고정훈,Choi,Dong-Ho,Lee,Sang-Hoon,Kim,Yong-Sik,Koh,Jung-Hoon 한국방재학회 2008 한국방재학회 학술발표대회논문집 Vol.2008 No.1
Acceleration time history (ATH) used in the seismic analysis should envelop a target power spectral density (PSD) function in addition to the design response spectrum in order to have sufficient energy at each frequency for the purpose of ensuring adequate load. Even though design regulations require the ATH used in seismic analysis to meet a target PSD function, the reason that ATHs meet to a target PSD function is not described. Thus, artificial ATHs for high PSD function and artificial ATHs for low PSD function are generated. And then elastic and inelastic single-degree-of-freedom (SDOF) systems are loaded with these artificial time histories as the earthquake load. As a result, linear response and inelastic response of SDOF systems are affected by PSD function.
충돌하중을 받는 U-채널 교량 측보의 구조적 안정성에 관한 연구
최동호,나호성,이광원,Choi,Dong-Ho,Na,Ho-Sung,Lee,Kwang-Won 한국방재학회 2008 한국방재학회 학술발표대회논문집 Vol.2008 No.1
U-Channel Bridge is effective bridge type, because its edge beam performs role of barrier and enables to reduce additional dead loads. Nevertheless, there is possibility of bridge collapse under impact load due to car crash. Also, edge beam must have ability to induce safe driving and prevent falling accidents. Therefore, this study carries out analysis of behavior of edge beam and slab and evaluation of structural stability under impact loads, based on Korean Highway Bridge Design Specifications and AASHTO LRFD Bridge Design Specification. According to analysis result, the maximum stress of edge beam and slab satisfies specification of allowable stress.
최동호,고영찬,권순길,이종선,Choi, Dong-Ho,Ko, Young-Chan,Gwon, Sun-Gil,Lee, Joung-Sun 대한토목학회 2013 대한토목학회논문집 Vol.33 No.3
본 연구에서는 부식이나 보강재가 고려된 비균일한 두께를 가지는 파이프라인에 대하여 일정한 외압을 받을 때의 탄성 좌굴하중을 이론적으로 산정하였다. 길이가 매우 긴 원통형 쉘 구조물인 파이프라인을 단순한 링 구조물로 가정하였고, 고유함수를 유도하여 좌굴 임계하중을 산정하였다. 또한, 두께 변화와 두께가 감소된 구간의 범위에 따른 변수해석을 수행하였다. 이론식에 의해 산정된 좌굴 임계하중 결과를 유한요소해석 결과와 비교하여 검증하였고, 두 결과는 잘 일치함을 알 수 있었다. This paper proposes a theoretical solution of elastic critical buckling load of infinitely long pipelines with non-uniform thickness under external pressure. The non-uniform cross section of pipelines can be considered as corroded or stiffened pipelines so that this paper can be a fundamental research of pipelines that are essential technology for offshore industries. The theoretical solution of pipelines with non-uniform thickness is derived with an assumption that a cylindrical shell under external pressure can be considered as a simple ring. The eigenfunctions are derived to obtain the critical buckling load. The reduced thickness and the reduced range are considered as variables in parametric analysis. The finite element analysis is performed to verify the theoretical solutions and the results of the analytic method and the finite element method are in good agreement.
최동호,김대회,서희원,박수영,Choi. Dong Ho,Kim. Dae Hoi,Seo. Hee Won,Park. Soo Young 한국방재학회 2013 한국방재학회논문집 Vol.13 No.1
화재시 건물내의 연소확대를 방지하기 위한 방화구획 선상, 피난통로, 승강기 탑승 로비 등에는 방화문, 승강기 등을 설치하기 위한 개구부가 위치하게 된다. 건축물에서의 연소확대는 이와 같은 개구부를 통하여 이루어지기 쉬우므로 설치되는 개구부 방호 설비에 대한 관련 기준의 정비 및 보완이 중요하다. 특히 과거와는 달리 건물의 고층화, 대형화에 따라 피난용도로 사용되는 승강기의 용도가 중요시 되고 있으며, 이에 따른 승강기문에 대한 화재안전성이 요구되고 있으며, 또한 방화문 등에 설치되는 방화유리창도 화재시 연소확대방지를 위한 검토가 필요하다. 이에 본 연구에서는 외국의 방화용 승강기문과 방화유리창에 대한 성능기준을 검토하여 국내 관련 성능기준을 설정하기 위한 기초자료를 제시하고자 하였다. The openings for fire doors and elevator doors are installed on fire compartment to stem fire spreading, evacuation passage and elevator hoistway in building. Fire spreading tend to grow through these openings, so it is important to organize the standard related to opening protectives. Unlike in the past, due to being tall and large, the elevator for evacuation is being more important. For this reason, it is required for elevator door to be safe in fire and it is necessary for the glazing installed on fire doors to be reviewed with respect to fire spreading. In this study, foreign performance criterion of the fire elevator door and the fire-protection-rated glazing were reviewed and the base data for improving way about the fire performance criteria were suggested.