• 대한교통학회지
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• 제20권4호
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• pp.19-26
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• 2002

본 연구는 자전거 교통시설의 설계 및 운영을 적절히 수행하기 위해서 반드시 필요한 자전거 교통류의 기본 특성에 대한 기초자료를 실험과 현장조사를 통하여 수집하고, 제시된 값의 교통시설 설계 및 운영에 대한 활용방안을 제안하는 것을 목적으로 하였다. 본 연구는 자전거 교통류의 가장 기본이 되는 연속류 상태를 대상으로 속도-밀도-교통량의 관계와 용량값, 단속류 상태에서의 포화교통류율에 대한 결과값과 방법론을 제시하였으며, 곡선 반경에 따른 속도의 변화에 대한 조사와 자전거의 주행영역에 대한 조사도 실시하였다. 조사결과 연속류 시설의 경우 실험조건하에서의 교통용량은 약 5000대/시/차로이며, 단속류 시설의 경우 포화교통류율은 실험조건하에서 약 3000대/시/차로의 값을 보이는 것으로 나타났다. 곡선을 주행하는 자전거의 경우 반경이 증가할수록 속도의 증가가 발생하나 반경이 20m를 기준으로 반경의 증가여부에 상관없이 자전거의 속도는 더 이상 증가하지 않음을 보였다. 자전거가 통행시 자전거 당 차지할 수 있는 면적에 따른 주행의 용이성을 자전거 운전자의 주행 영역으로 표시하였는데 점유면적이 0.96m$\times$2.47m 이하일 경우 자전거 운전자는 충돌의 위험을 느끼게 되며, 2.21m$\times$4.1m 이상일 경우에는 쾌적한 상태에서의 통행이 가능한 것으로 조사되었다.

• Journal of Chest Surgery
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• 제38권7호
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• pp.504-506
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• 2005

심강내관상동맥은 전체 관상동맥우회술 환자 중 약 $0.2\~0.3\%$에서 발견되며, 국내에서는 아직 보고된 바 없는 극히 드문 관상동맥기형의 일종이다. 수술 전 관상동맥조영술을 통하여 진단하기 어렵고, 관상동맥우회술 후에 우심실로부터의 출혈이 발생할 수 있으므로 우심실절개 부위의 견고한 봉합이 필요하다. 기존의 증례 보고에 따르면 외과용거즈(pledget)를 이용한 수평매트리스봉합(horizontal mattress suture)이 추천되기는 하나 주위의 심근을 압박하여 관상동맥가지 및 관통동맥의 협착을 유발할 수 있어, 단순단속봉합(simple interrupted suture)을 이용하고도 수술 후 별다른 합병증 얼이 호전된 예를 경험하였기에 보고하는 바이다.

• Journal of Chest Surgery
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• 제18권4호
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• pp.537-541
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• 1985

Recently, we met a 12 year old female patient who suffered from bacterial endocarditis and pericarditis which were complicated by patent ductus arteriosus. She was admitted to our hospital because of dyspnea, fever, headache, and generalized ache for 10 days. The initial diagnosis was bacterial endocarditis and pericarditis complicated by patent ductus arteriosus and congestive heart failure. At first, we tried to treat the patient medically with digitalis, diuretics, and massive antibiotics. On echocardiography large amount of pericardial fluid was accumulated mainly right anterior aspect and also noted a large vegetation at pulmonary valve area. With vigorous medical treatment including repeated pericardiocentesis, the patient showed no improvement. So we decided to perform pericardiectomy for elimination of the most probable septic focus. On operation, we encountered an unpredicted event, the pericardium was thickened, distended, and its surface showed pulsating which meant connecting to systemic circulation. We decided to close the operative wound and reoperate her under cardiopulmonary bypass later. On the next day, we operated her under cardiopulmonary bypass later. On the next day we operated her under cardiopulmonary bypass. The operative findings were ruptured main pulmonary artery about 1.5cm in diameter on its ventral portion, the blood from the ruptured main pulmonary artery was filled up the localized pericardial sac due to previous pericarditis. Through the ruptured main pulmonary artery, we also found 0.5cm diametered patent ductus arteriosus. With the aid of partial cardiopulmonary bypass and inserting 24F ballooned Foley catheter at aorta, pericardiectomy was performed first. After completion of the pericardiectomy, total cardiopulmonary bypass was established. With minimum pump flow [0.3L/min/m2] the PDA was closed with two Teflon-felted 4-0 Prolene interrupted sutures. The ruptured main pulmonary artery was also closed using thickened pericardium with three Teflon-felted 4-0 Prolene interrupted sutures. The operation was successful and postoperative course was uneventful. She was discharged on the 16th POD. We report this case as a very rare secondary complication of bacterial endocarditis complicated by patent ductus arteriosus.

• 대한교통학회지
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• 제23권3호
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• pp.109-123
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• 2005

본 논문에서는 지방부 간선도로에서 제공되는 단속류 구간통행시간 정보의 체계적인 수집 분석을 위해 현재 일부 국도에서 운영중인 차량번호판 매칭방식 AVI(자동차량인식장치 : Automated Vehicle Indentification)로부터 수집된 자료의 적합성분석 및 단속류 구간통행시간 자료의 적정집락간격(optimal aggregation interval)산정을 위한 통계적 결정방법을 연구하였다. 연구결과 차량번호판 매칭방식 AVI 수집자료는 통과위주의 대표차로상에서만 수집되기 때문에 차로간의 속도차가 크게 나타나는 단속류 구간에서는 전차로에 대한 통행시간 수집자료와 교통특성에 차이가 있으므로 현재의 차량번호판 매칭방식 ANI 표본수집 자료를 통해 산출된 구간통행기간을 구간의 대표값으로 적용하는 데에는 문제가 있어 이에 대한 추가적인 검토가 필요하다는 결론을 얻었다. 그리고, 단속류 구간의 통행시간 정보제공을 위한 수집자료의 적정집락간격 결정방법으로 점추정과 구간추정방법을 적용하여 모형을 개발하고, 이 모형을 적용한 결과 점추정모형이 구간추정모형보다 집락간격결정에 민감하고 보다 정확한 적정집락간격 선정이 가능한 것으로 밝혀졌으며, 단속류 구간의 적정집락간격은 5분으로 산정되어 현재 적용되고 있는 단속류 구간 5분 집락간격은 적정한 것으로 판단된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1536-1537
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• 2011

The high-voltage circuit breaker plays an important role in the electrical system because there has been a need for suitable switching devices capable of initiating and interrupting the flow of the electric fault current. It continues as the contacts recede from each other and as the newly created gap is bridged by a plasma. The arc plasma happens inside the insulation nozzle of SF6 self-blast interrupter which is newly developed as the next-generation switching principle. The ablation of PTFE nozzle is caused by this high temperature medium, the PTFE vapor from the nozzle surfaces flows toward the outlets and the pressure chamber. The vapor makes the pressure of the chamber increased by heat and mass transfer from the arcing zone. Because the rate of ablation depends on the magnitude of applied current, it decreases when the current goes to zero. The compressed gas inside the chamber flows reversely toward the arc plasma during this moment. According to this principle, the arc can be cooled down and the fault current can be interrupted successfully. In this study, we calculate arc plasmas and thermal-flow characteristics caused by fault current interruption inside a SF6 self-blast interrupter, and to investigate the effect of PTFE ablation on the whole arcing history.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.365-368
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• 2002

The design of industrial arc plasma systems is still largely based on trial and error although the situation is rapidly improving because of the available computational power at a cost which is still fast coming down. The desire to predict the behavior of arc plasma system, thus reducing the development cost, has been the motivation of arc research. To interrupt fault current, the most enormous duty of a circuit breaker, is achieved by separating two contacts in a interruption medium, $SF_{6}$ gas or air etc., and arc plasma is inevitably established between the contacts. The arc must be controlled and interrupted at an appropriate current zero. In order to analyze arc behavior in $SF_{6}$ gas circuit breakers, a numerical calculation method combined with flow field and electromagnetic field has been developed. The method has been applied to model arc generated in the Aachen nozzle and compared the results with the experimental results. Next, we have simulated the unsteady flow characteristics to be induced by arcing of AC cycle, and conformed that the method can predict arc behavior in account of thermal transport to $SF_{6}$ gas around the arc, such as increase of arc voltage near current zero and dependency of arc radius on arc current to maintain constant arc current density.

• 한국자동차공학회논문집
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• 제12권5호
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• pp.136-145
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• 2004

In companion paper, the composition and structure of the traffic environment is derived. Rules to regulate agent behaviors and the frameworks to communicate between the agents are proposed. In this paper, the model of a driver agent which controls a vehicle agent is constructed. The driver agent is capable of having different driving styles. That is, each driver agent has individual behavior settings of the yielding index and the passing index. The yielding index can be defined as how often the agent yields in case of lane changes, and the passing index can be defined as how often the agent passes ahead. According to these indices, the agents overtake or make their lanes for other vehicles. Similarly, the vehicle agents can have various vehicle dynamic models. According to their dynamic characteristics, the vehicle agent shows its own behavior. The vehicle model of the vehicle agent contains the nonlinear subcomponents of engine, torque converter, automatic transmission, and wheels. The simulation has proceeded for an interrupted flow model. The result has shown that it is possible to express the characteristics of each vehicle and its driver in a traffic flow, and that the change of the traffic state is closely related with the distance and the signal delay between intersections. The system developed in this paper shows the effectiveness and the practical usefulness of the traffic simulation.

• 한국소음진동공학회논문집
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• 제20권7호
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• pp.611-619
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• 2010

The paper deals with the proper design of GGH(gas-gas heater) panel elements of desulfurization equipments in a thermoelectric power plant. When fossil fuels such as coal, petroleum et cetera are burnt to ashes, sulfur oxide compounds are produced, and calcareous sludges are deposited at GGH panel elements. In this case, operation of a power plant equipments is interrupted, and a tremendous economic loss comes into existence. One of the purposes of the paper is to find flow velocity distributions and regions of depositions when calcareous sludges pile up on the GGH panel elements through the fluid analysis. In the fluid analysis, flow velocity and position distributions of particles between GGH panel elements are demonstrated according to time variation for ammonia and calcium hydroxide particles.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.402-407
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• 2001

This paper reports a result of numerical heat transfer analysis for heat spreader with various ribs. Four different ribs are compared in this study. In general, the heat transfer on a vertical plate is enhanced when a rib is attached as the surface area increases, and the growth of the boundary layer is interrupted. However, for a low flow less than 0.1m/s, it is observed that the heat transfer is sensitive to the height of a rib: it decreases as the height increases. Among the four ribs, the H-shaped rib showed better performance than other ribs.

• 한국산업융합학회 논문집
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• 제6권4호
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• pp.339-345
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• 2003

The purpose of this thesis is to develop a simulation model to estimate link travel speed applicable to urban street transportation planning for interrupted traffic flow, influenced by signalized intersection. This link travel speed model is expected to be a better and more than previous studies.