• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.725-732
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• 2011

The vibration resulting from railway operation is transmitted through the tunnel to adjacent buildings and the transmitted vibration radiates structure-borne noise which is causing a lot of public complaints by its negative effects to the buildings near tunnel. This study performed the parametric study about sleeper space and track support stiffness in order to reduce vibration on the concrete track and near structures. In this study, it was compared and performed vibration analysis and field test about these. In addition, as changing the sleeper space and track support stiffness, vibration of the structures was evaluated. Via this study, in terms of reducing the figure of the sleeper space and track support stiffness to the half, as vibrating acceleration transmitted through concrete round is getting reduced, it transmitted through the tunnel was analysed to the same phenomena. In conclusion, suggested track structure into this study, it can be applied to the track structure of existing line, and it is expected to be a new effective anti-vibration method to prevent public complaints.

• Structural Engineering and Mechanics
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• 제48권4호
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• pp.435-453
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• 2013

A new computational approach for the rain load on the transmission tower is presented to obtain the responses of system subjected to the wind and rain combined excitations. First of all, according to the similarity theory, the aeroelastic modeling of high-voltage transmission tower is introduced and two kinds of typical aeroelastic models of transmission towers are manufactured for the wind tunnel tests, which are the antelope horn tower and pole tower. And then, a formula for the pressure time history of rain loads on the tower structure is put forward. The dynamic response analyses and experiments for the two kinds of models are carried out under the wind-induced and wind-rain-induced actions with the uniform and turbulent flow. It has been shown that the results of wind-rain-induced responses are bigger than those of only wind-induced responses and the rain load influence on the transmission tower can't be neglected during the strong rainstorm. The results calculated by the proposed method have a good agreement with those by the wind tunnel test. In addition, the wind-rain-induced responses along and across the wind direction are in the same order of response magnitude of towers.

• 한국공간구조학회논문집
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• 제19권4호
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• pp.95-102
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• 2019

In this study, the reliability of the analysis is evaluated by comparing the average wind pressure coefficient, RMS wind pressure coefficient and wind pressure spectrum with same condition of wind tunnel test which are calculated in the high-Reynolds number range of 1.2×10⁶, 2.0×10⁶ each for the typical curved shape dome structure. And it is examined by the reliability of analysis through Improved delayed detached Eddy Simulation(IDDES), which is one of the hybrid RANS/LES techniques that can analyze the realistic calculation range of high Reynolds number. As a result of the study, it was found that IDDES can be predicted very similar to the wind tunnel test. The distribution pattern of the wind pressure coefficient and wind pressure spectrum showed a similar compared with wind tunnel test.

• Journal of Chest Surgery
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• 제23권1호
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• pp.192-200
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• 1990

The results of conventional operative resection of diffuse subaortic stenosis[tunnel subaortic stenosis] have been less than satisfactory. We have performed modified Konno operation to enlarge the outflow tract of both ventricle with a patch in three patients with diffuse tunnel subaortic stenosis in the department of Thoracic and Cardiovascular Surgery, Seoul National University Children`s Hospital. Preoperative left ventricular aortic pressure gradients were 135 mmHg, 50 mmHg, 80 mmHg respectively in these patients. After right ventriculotomy, the septotomy was done and extended beyond the limit of the stenosis and fibrous and/or muscular tissue was removed from each edge of septal incision. After adequate widening of the tunnel subaortic stenosis with various patches, right ventricle was closed primarily or with prosthetic patches successfully. One patient who was diagnosed as complete atrioventricular septal defect had complete AV block preoperatively and was implanted permanent pacemaker, and others who were sinus rhythm preoperatively have no serious postoperative rhythm disturbance. One patient developed mild postoperative aortic insufficiency and one who had preoperative aortic insufficiency has still same grade of aortic insufficiency after operation. All had good postoperative hemodynamics without any postoperative residual pressure gradient.

• 터널과지하공간
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• 제24권2호
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• pp.120-130
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• 2014

최근 전 세계적으로 여러 건의 대규모 해저터널 건설 사업이 완료되었거나 진행 혹은 계획 중에 있다. 우리나라 역시 한중, 한일 해저터널에 대한 기본 구상이 이루어지고 있으며 동시에 국내 도서 지역을 연결하는 해저터널이 구상 단계에 있다. 국내 기술수준과 해저터널 건설이 갖는 파급효과를 고려할 때, 해저터널 관련 기술의 확보 및 개선이 요구되어진다. 이 논문은 사례연구를 통하여 해저터널이 갖는 특징과 국내외 해 하저터널 건설동향을 분석하였고 해저터널과 관련된 사고 발생 사례를 수집하여 이로부터 요구되는 관련기술에 대하여 정리하였다.

• 한국항공우주학회지
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• 제45권3호
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• pp.212-216
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• 2017

두께비 18% 익형(KARI-11-180)에 대한 공력특성 분석이 전산해석기법을 활용해 수행되었다. 익형주위의 격자는 벽면에서 수직으로 투영하여 경계층 격자를 형성하였고 익형 후방에는 정밀한 후류 예측을 위해 조밀한 격자를 위치하였다. 원방경계까지의 거리는 익형 코드의 100배로 정하였고 익형시험결과와의 비교를 위해 자유류 속도, 익형 코드 및 Reynolds수를 풍동시험과 동일하게 정하였다. 또한 난류 모델은 천이지점 예측이 우수한 transition SST 및 DES 모델을 사용하였다. 3차원 전산해석은 세장비가 2와 5인 익형모델에 대해 수행되었는데 양력은 풍동시험결과보다 높은 값을 항력은 낮은 값을 예측하였다.

• 한국항공우주학회지
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• 제35권1호
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• pp.79-86
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• 2007

회전 발사체용 마그너스 효과 풍동실험 측정장치를 개발하였다. 국방과학연구소 풍동실험실에서는 고속풍동실험에 앞서 지상기능시험과 마그너스 저속풍동실험을 수행하였으며 마그너스 모형은 분당 약 6,000~10,000 회전하였으며, 속도 100 m/sec에서 측정한 마그너스 효과는 무차원 회전특성인자에 대해 선형적인 변화특성을 보였다. 동일형상 모형에 대해 미국 AEDC-4T 풍동에서 기 수행하였던 마그너스 측정결과와의 비교검토를 수행하였다.

• 한국항공우주학회지
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• 제41권5호
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• pp.335-341
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• 2013

풍동시험 중에 발생하는 시스템오차의 변동에 관한 연구를 수행하였다. 회전익 항공기의 기체 공력특성 측정실험에 실험설계 방법론이 적용되었다. 풍동시험 중에 발생하는 시스템오차의 변동에 관한 연구를 수행하였다. 허용 실험오차 내에서 항상 동일한 결과를 얻어야 하는 전제조건에도 불구하고 한 개의 실험시간 블록에서 측정된 힘과 모멘트가 다른 시간블록에서 측정된 것과 상당량 다르게 측정되었다. 실험관련 시스템오차는 존재하지 않는다고 임의로 간주해서는 안되며 이러한 오차의 감소는 랜덤화, 블록화 및 반복화 등의 실험설계원리의 적용을 통해 가능하다.

• 대한조선학회논문집
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• 제44권6호
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• pp.627-634
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• 2007

A bonded plate or a coated part can be debonded by external impact or thermal expansion. To analyse adhesive strength, the blister test is generally adopted. In this paper, a blister test is modelled theoretically and then the stability and bifurcation of the blister are studied under several different cases. The blister is simplified to consist of a pure bending plate attached elastically to the rigid substrate. Expression of the energy release rate is obtained as a form of an explicit function for a circular-type blister or tunnel-type blister grown by controlling the internal pressure or internal volume. Stability and bifurcation are also studied in the frame of the quasi-static evolution. The study shows that the circular- type blister propagates with the first mode of bifurcation and that the tunnel-type blister propagates with a regular wave. It is proved that the waves have the same form on two side lines of the tunnel and that the wave length can be obtained. When the internal pressure is controlled, the blister is unstable, but when the internal volume is controlled, it is stable.

• Geomechanics and Engineering
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• 제7권1호
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• pp.55-73
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• 2014

The theoretical predictions of ground movements induced by tunnelling are usually based on the assumptions that the subsoil has the same soil densities. The theoretical prediction does not consider the impact of different sand soil types on the surface settlement due to tunnelling. The finite elements analysis (FEA) considers stress and strength parameters of the different sand soil densities. The tunnel construction requires the solution of large soil-structure interaction problem. In the present study, the FEA is used to model soil-tunnel system performance based on a case study to discuss surface displacement due to tunnelling. The Greater Cairo metro tunnel (Line 3) is considered in the present study as case study. The surface displacements obtained by surface displacement equation (SDE) proposed by Peck and Schmidt (1969) are presented and discussed. The main objective of this study is to capture the limitations of the parameters used in the SDE based on the FEA at different sand soil densities. The study focuses on the parameters used in the SDE based on different sand soil densities. The surface displacements obtained by the FEA are compared with those obtained by the SDE. The results discussed in this paper show that the different sand soil densities neglected in the SDE have a significant influence on the surface displacement due to tunnelling.