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SU2를 이용한 Advanced Rotorcraft 에어포일 유동해석
김태순(Taesoon Kim),김승태(Seungtae Kim),김민우(Minwoo Kim),김준규(Junkyu Kim),지솔근(Solkeun Jee) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
The goal of this study is to numerically investigate the aerodynamic characteristics of an advanced rotorcraft airfoil. A rotorcraft main rotor in the advancing side encounters high-speed flow, whereas, in the retreating side, the rotor needs to avoid dynamic stall for high-thrust or high-speed-forward maneuvers. Consequently, a high drag-divergence Mach number is preferred for the advancing side, and a high lift with good dynamics stall characteristics is critical for the retreating side. The VR-12 airfoil, which satisfies such challenging conditions, was recently developed and has been successfully applied to advanced helicopters. Therefore, the VR-12 airfoil is chosen in the current numerical study. Unsteady Reynolds-averaged Navier-Stokes (URANS) simulation is performed with the Spalart-Allmaras turbulence model. Fully turbulent flow condition for the RANS model is used. The pressure profiles along with integral quantities, including the aerodynamic lift, drag, and moment, are compared with wind tunnel experiments and CFL3D numerical analysis data. Good agreement was achieved across angles of attack for the airfoil.
ON A RIGIDITY OF HARMONIC DIFFEOMORPHISM BETWEEN TWO RIEMANN SURFACES
KIM, TAESOON The Honam Mathematical Society 2005 호남수학학술지 Vol.27 No.4
One of the basic questions concerning harmonic map is on the existence of harmonic maps satisfying a certain condition. Rigidity of a certain harmonic map can be considered as an answer for this kinds of questions. In this article, we study a rigidity property of harmonic diffeomorphisms under the condition that the inverse map is also harmonic. We show that every such a harmonic diffeomorphism is totally geodesic or conformal in two dimensional case.
Some Remarks on the Exsistence of Harmonic Map
Kim, Taesoon 목원대학교 자연과학연구소 1994 自然科學 硏究論文集 Vol.3 No.1
이 논문에서 밀집 다양체 간에 정의된 조화사상의 존재성에 대하여 알려진 결과를 소개하고 새로운 연구 방향을 제시하려한다. 지수적인 조화사상(exponentially harmonic map)을 소개하고 그들과 조화사상의 관계를 상수 에너지 밀도를 이용하여 밝히려 한다. 상수 에너지 밀도를 갖는 조화사상은 조화사상의 균등변화이론에 매우 중요한 도구이므로 이를 이용하여 균등변화이론을 확장해 보고자 한다. This is both a survey and a research article of existence problem for harmonic map between compact manifolds without boundary. We introduce harmonic map and exponentially harmonic map and some relations of them. We find a relation of harmonic map and exponentially harmonic map given by the constancy of energy density. The constant energy density harmonic map is very important in the equivariant theory of harmonic map.
Taesoon Kim,Jun-Haeng Heo 대한토목학회 2006 KSCE journal of civil engineering Vol.10 No.5
The objective of multi reservoir system optimization is to achieve an optimal reservoir operating plan by the effective use of water resources. Many optimization techniques have been applied for the last decades, and researchers have recently interested in the heuristic approaches like evolutionary computation. This study proposes a methodology for applying multi-objective genetic algorithms (MOGAs) to a multireservoir system optimization in the Han River basin. The second generation evolutionary multi-objective technique, NSGA-Ⅱ, is used. The simulation model is applied to the Han River basin and the performance of the model is compared with the historical reservoir operation records. Two different cases are performed to evaluate the applicability of NSGA-Ⅱ. Case 1 shows the basic performance of NSGA-Ⅱ as applied to multireservoir system optimization, and Case 2 presents the methodology to discriminate the critical decision variables. In addition, the alternative releases and storages by NSGA-Ⅱ are compared with the historical releases and storages. Cases 1 and 2 show that NSGA-Ⅱ can be applied to multireservoir system optimization, and the alternative releases and storages computed using the results from NSGA-Ⅱ can be used as the possible reservoir operating plans that supply more water resources to downstream than the historical releases.
김태순(Taesoon Kim),남현석(Hyunsuk Nam),문종성(Jongsung Moon) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4
핵연료집합체는 원자력발전소의 핵연료를 지지하고 있는 중요한 핵심 부품으로서 정상 운전 시뿐만 아니라 지진 및 냉각재상실사고와 같은 가상사고 발생 시에도 안전정지 기능과 냉각성능을 보장할 있어야 한다. 더욱이 최근 세계적으로 지진 발생 빈도가 높아지고 국내에서도 비교적 높은 규모의 지진이 발생함에 따라 핵연료 집합체에 대해서는 설계단계에서 수명말기 조건에서 더욱 취약한 구조로 변하는 특성을 추가로 고려하도록 하는 등 규제요건이 강화되었다. 또한 국내 핵연료집합체 내진해석 시 Westinghouse의 CESHOCK 코드를 사용하고 있어, 해외수출 시 저작권 관련 문제가 발생할 수 있어 CESHOCK 코드에 대한 고유화가 시급한 상황이다. 본 연구에서는 내진설계 기준 강화에 따른 해석 방법론 개선을 위해 상용프로그램 기반의 핵연료집합체 비선형 해석모델을 개발하여, 다양한 충격하중 조건에 따른 핵연료 집합체의 거동을 평가하여 기존 평가 결과와 비교하였다. Nuclear fuel assembly is an important core component supporting the nuclear fuel of a nuclear power plant, and should be designed to ensure the safety shutdown and cooling performance not only during normal operation but also in the event of an earthquake or loss of coolant. Moreover, as the frequency of earthquakes in the world has increased recently and earthquakes of a relatively high scale have occurred in Korea, regulatory guides have been reinforced to design nuclear fuel assemblies by reflecting the end-of-life characteristics. In addition, since CESHOCK code of Westinghouse Electric Company is used for seismic analysis of domestic nuclear fuel assemblies, there is an urgent need for technology uniqueness as it may cause copyright-related problems when exporting overseas. In this study, in order to improve the analysis methodology according to the reinforcement of seismic design standards, a commercial program-based nonlinear analysis model was developed to evaluate the behavior of nuclear fuel assemblies under various impact force conditions and compared with the existed results from CESHOCK code.
김태순 ( Taesoon Kim ),김규형 ( Kyuhyung Kim ) 한국안전학회(구 한국산업안전학회) 2018 한국안전학회지 Vol.33 No.5
A detailed fatigue evaluation procedure was developed to mitigate the excessive conservativeness of the conventional environmental fatigue evaluation method for the pressurizer spray line elbow of domestic new nuclear power plants. The pressurizer spray line is made of austenitic stainless steel, which is relatively sensitive to the environmentally assisted fatigue, and has a low degree of design margin in terms of environmentally assisted fatigue due to the thermal stratification phenomenon on the pipe cross section as a whole or locally. In this study, to meet the environmental fatigue design requirements of the pressurizer spray line elbow, the new environmental fatigue evaluation has been performed, which used the ASME Code NB-3200-based detailed fatigue analysis and the environmental fatigue correction factor instead of the existing NB-3600 evaluation method. As a result, the design requirements for environmentally assisted fatigue were met in all parts of the pressurizer spray line elbow including the fatigue weakened zones by thermal stratification.