A5101758131- Gear and Bearing Dynamics Analysis
- Ship Hydrodynamics and Maneuverability
- Mechanical Engineering and Vibrations Research
- Engineering Applied Research
- Tribology and Lubrication Engineering
- Maritime Transport Emissions and Efficiency
- Mechanical stress and fatigue analysis
- Aerospace and Aviation Technology
- Advanced machining processes and optimization
- Vehicle Noise and Vibration Control
- Topology Optimization in Engineering
- Numerical methods in engineering
- Nonlinear Waves and Solitons
- Differential Equations and Numerical Methods
- Electric and Hybrid Vehicle Technologies
- Stability and Control of Uncertain Systems
- Quantum chaos and dynamical systems
- Radio Wave Propagation Studies
- Electromagnetic Simulation and Numerical Methods
- Fatigue and fracture mechanics
- Cavitation Phenomena in Pumps
- Radiative Heat Transfer Studies
- Elasticity and Wave Propagation
- Aerospace Engineering and Energy Systems
- Control Systems and Identification
Seoul National University
2015-2024
Gyeongsang National University
2012
Abstract Wind turbines are eco-friendly energy sources that generate electricity from wind power. Among their various components, gearboxes constitute the most critical loss owing to longest downtime. To guarantee durability, a flexible pin was designed based on original straddle-mounted for enhanced tooth load sharing and distribution in planetary gear set (PGS) of turbine gearbox (WTGB). The improved durability evaluated by calculating mesh factor face contact stress comparing these values...
We develop a program for predicting bearing performance, including the maximum contact stress, power loss, minimum lubricating film thickness, static safety factor, and dynamic life, an optimal design high-speed angular ball bearings in aircraft gearboxes using optimization algorithms. A is developed to predict performance by calculating loads displacements of individual balls based on bearing’s kinematic equilibrium equations. Next, with non-dominated sorting genetic algorithm III...
As the demand for agricultural electric vehicles increases, it is becoming important to conduct noise reduction in consideration of characteristics an powertrain. This study was conducted optimize shape design gearbox housing radiated vehicle gearbox. The and vibration were measured considering gearbox, which radiates high-frequency pure tone noise. main source by structural identified considered when modeling loading conditions numerical analysis. To improve reliability, finite element (FE)...
This study investigates the optimization of hull form a tanker, considering operational efficiency in waves, accordance with recent Energy Efficiency Design Index regulation. For this purpose, total resistance and speed loss ship under representative sea conditions were minimized simultaneously. The was divided into three components: calm water resistance, added due to wind, waves. first two components calculated using regression formulas, last component estimated strip theory, far-field...
We report that the crystallinity of C70 is improved significantly if CuI used as a templating layer, leading to remarkable enhancement hole mobilities from 8.32 × 10(-6) 3.26 10(-5) cm(2)/(V s). As result, use layer in C70-based solar cells with low donor concentration resulted significant improvement fill factor 0.51 0.57 and power conversion efficiency 5.56% 6.23% under simulated AM 1.5G, 1 sun irradiation. This result demonstrates effective at improving fullerene derivatives well materials.
Abstract In this study, gearbox radiated noise was successfully reduced through housing shape optimization. First, dynamic and structural–acoustic coupled analysis models of an agricultural UTV were developed. Then, the test equipment configured to match that simulation model, a conducted. The results showed errors within 0.1 dB for vibration 0.2 dB(A) noise, indicating reliable. design then optimized using topology optimization based on developed coupling model. sound pressure level around...
본 연구에서는 프로펠러의 형상 및 환경 요소의 영향에 따른 추력값을 빠르게 계산할 수 있는 프로그램을 개발하였다. 여기서 유도 요소를 계산하기 위해서, 카와다에 의해 소개된 준-무한 나선와류 모델을 이용하였다. code의 구조는 Wrench의 프로펠러 양력선 이론에 기초하여 제작되었으며, 추력, 파워 효율 등의 공력값을 있다. 1차적인 프로그램의 신뢰성 검증을 위해 NACA 보고서의 시험 결과와 비교 시행하였다. 2차적인 위해서는, 회전속도와 전진 속도에 변화를 주면서 아음속 풍동 시험을 수행하였다. In this study, a program has been coded to evaluate propeller thrust rapidly following the effects of shapes and environmental facts. At time, Semi-infinite Helical Vortices model is used predict induction factor...
In this study, a multi-objective optimal design of planetary gear set was performed considering mass, power loss, and transmission error. particular, the results were analyzed from novel perspective. The implemented methodology minimizes vibration with respect to seven macro-geometry variables. peak-to-peak static error (PPSTE) each pair corresponds excitation source set, reducing PPSTE helps minimize vibration. Thus, calculated using time-varying mesh stiffness obtained through an...
This study deals with wave-induced unsteady pressure on a ship moving constant forward speed in regular head waves. Two different numerical methods are applied to solve wave–ship interaction problems: Rankine panel method which adopts velocity potential, and Cartesian-grid solves the momentum mass conservation equations under assumption of inviscid incompressible fluids. Before comparing l1ocal distributions, computational validated for global quantities, such as motion responses added...
아음속-초음속 패널법(panel method)을 이용하여 항공기의 정적 안정성 미계수와 동적 미계수 및 조종미계수를 예측할 수 있는 프로그램을 개발하였다. 사용된 코드는 소스(source)와 말굽 와류(elementary horse shoe vortex)의 분포를 사용하고, 그 분포의 크기는 얇은 물체 근사(thin body approximation)을 적용하여 간략히 한 경계 조건을 계산하였다. 항공기에 부착된 좌표계에서 준정상(quasi-steady) 해석을 통해서 항공기 3축의 댐핑 계수를 예측하였다. 개발된 삼각날개(delta-wing)의 중립점(neutral point), 롤, 피치 계수의 이론치와 비교하여 검증하였다. 마지막으로 F-18의 정적, 조종 미계수를 풍동 시험치와 계산치에 개발한 코드의 정확성과 유용성을 확인하였다. A computer program that can estimate static, dynamic stability and control...
In this paper Hartley functions are used to approximate the solutions of continuous time linear dynamical system. The function and its integral operational matrix first presented, an efficient algorithm solve Stein equation is proposed. based on compound inverse sum matrices. Using structure Hartley's matrix, full order should be solved in terms pure algebraic equations, which reduces computation remarkably. Finally a numerical example illustrated demonstrate validity proposed algorithm.
A Haar wavelet based numerical method for solving singularly perturbed linear time invariant system is presented in this paper. The reduced pure slow and fast subsystems are obtained by decoupling the differential matrix equations converted into algebraic Sylvester via technique. operational of integration its inverse utilized to reduce computational solution equations. Finally a example given demonstrate validity applicability proposed method.
십자형 낙하산은 원형 낙하산에 비해 제작상의 이점과 비용상의 이점이 있지만, 비정상 상태의 조건에 대해 많은 제약을 가지고 있다. 본 연구는 낙하산의 단점을 개선하여 더 나은 형태의 낙하산을 개발하는데 목적을 두고 있으며, Reefing을 통해 이러한 단점들을 개선 할 수 있을 것이라 기대하고 공력 특성 중에 성능에 가장 크게 작용하는 항력, 안정성, 진동에 풍동 시험을 진행 하였으며, Reefing 효과로 인해 변화되는 형태와 성능들에 연구 있었다.공력 계수를 얻기 위한 풍동시험은 6분력 피라미달 밸런스와 전방 고정부에 설치된 로드셀에 의해 측정이 되었다. 4개의 제작하였고, 각각의 값들을 비교하였다. line ratio에 따라 공력계수들의 변화를 알 있었다. 또한 reefing 효과에 separation edge가 발생되어 안전성 향상을 확인할 연구를 기존 단점인 안정성을 향상시켜 다양한 분야에서 새로운 낙하산이 사용될 기대된다. Cruciform parachute has...
풍동에서 측정된 공력자료에는 풍동벽면의 영향으로 인하여 불가항력적인 오차가 포함되어 있다. 벽면영향이 없는 공력자료를 얻기 위해서는 이러한 원하지 않는 벽면효과를 제거 하여야 한다. 유선곡률 효과는 유선의 곡률이 자유 흐름의 것과 다르기 때문에 발생한다. 고정익 항공기에 사용되고 있는 전통적인 효과를 보정방법인 Glauert의 보정방법은 회전익 적용이 적절하지 않다. 본 논문에서는 로터에 적절한 후류모델을 사용하는 Heyson의 보정방법을 사용하여 로터축 기울어짐 각과 동압을 보정하였다. Heyson 보정방법의 결과를 Glauert 결과와 비교하였다. Aerodynamic data measured in a wind tunnel has inevitable errors due to the presence of walls. These unwanted interference effects must be corrected for wall free aerodynamic data....