• Proceeding of EDISON Challenge
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• 제5회(2016년)
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• pp.593-597
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• 2016

항공기의 비행 안정성을 판별하기 위해서는 정적(static)안정성과 동적(dynamic)안정성을 모두 고려해야 한다. 본 연구는 EDISON_CFD의 KFLOW_EDISON_2D3DOF, 2D_Com_P해석자를 이용해 2차원익형의 정적(static)계수와 동적(dynamic)계수를 구해 항공기 전체형상의 정적 안정성 및 동적 안정성을 분석하였다. 그 중 2015년도 인간 동력 항공기대회 건국대학교 참가 기체를 예시로 연구를 진행하였다. 주익 익형 SG6043과 미익 익형 NACA0012을 EDISON_CFD를 이용하여 각 익형의 모멘트계수를 구하고 그 결과값을 이용하여 기체의 무게중심에 대한 각 익형의 감쇠계수를 계산하였다. 그리고 주익과 미익의 면적비율과 코드길이의 비율을 고려해 전체 항공기형상의 안정성과 비행 형태를 분석하였다.

• Journal of Electrical Engineering and Technology
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• 제9권2호
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• pp.441-451
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• 2014

This article addresses an efficient heuristic-based approach to assign static shunt capacitors along radial distribution networks using the artificial bee colony algorithm. The objective function is adapted to enhance the overall system static voltage stability index and to achieve maximum net yearly savings. Load variations have been considered to optimally scope the fixed and switched capacitors required. The numerical results are compared with those obtained using recent heuristic methods and show that the proposed approach is capable of generating high-grade solutions and validated viability.

• Physical Therapy Korea
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• 제15권4호
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• pp.18-26
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• 2008

The present study was aimed at investigating the postural control ability of volleyball players with functional ankle instability. The subjects were 26 male volleyball players were divided into 2 groups (13 subjects with functional ankle instability and 13 subjects with ankle stability) who could evaluate Questionnaire. All the male participants were tested by a Balance Master System. This study were to measure of static balance ability, dynamic balance ability, motor function the difference between functional ankle instability group and control group. Ankle instability group and stable group in postural sway ($^{\circ}/sec$) on film surface with eye closed in modified clinical test sensory interaction on balance, and left unilateral stance with eye opened and closed were significantly different (p<.05). The ankle instability group and stable group in limit of stability were significantly different (p<.05). The ankle instability group and stable group in left/right rhythmic weight shirt were significantly different (p<.05). The ankle instability group and stable group in turn time (sec) & turn sway ($^{\circ}$) during step/quick turn and end sway ($^{\circ}/sec$) in tandem walk were significantly different (p<.05). This study showed that volleyball players with functional ankle in stability were effected postural control ability by static balance & dynamic balance ability. Further study is needed to measure various athletic with functional ankle instability for clinical application.

• The Journal of Korean Physical Therapy
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• 제28권4호
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• pp.221-226
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• 2016

Purpose: This study was conducted to evaluate the effects of neck and trunk stabilization exercise on static and dynamic balance in older adults. Methods: A total of 30 older adults participated in this study. Participants were randomly assigned to the neck and trunk stabilization exercise group (NTSG) (n=15) or the trunk stabilization exercise group (TSG) (n=15). The NTSG performed a trunk stabilization exercise added to a neck stabilization exercise that included biofeedback. Both groups received training for 30 minutes per day three times per week for eight weeks. The anterior, posterior limit of stability and sway length was used to measure static balance ability, while the timed up and go (TUG) test was used to measure dynamic balance ability. Results: Participants showed significant differences in sway length, anterior limit of stability, posterior limit of stability, and the results of the TUG test between their pre- and post mediation evaluations (p<0.05). The NTSG showed a more significant increase than the TSG (p<0.05). Conclusion: According to the results of this study, both exercises effectively improved static and dynamic balance ability. However, the neck and trunk stabilization exercise is more efficient for increasing the balance ability of older adults.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• 제38권7호
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• pp.655-663
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• 2010

DUP (direct underside pressurization) is a device that can considerably increase lift, reduce take-off speed and minimize hump drag when a WIG effect vehicle takes off on the water surface. A 3-dimensional numerical investigation of a WIG effect vehicle with DUP is performed to analyze aerodynamic characteristics and the static height stability. The model vehicle, named Aircat, consists of a propeller in the middle of a fuselage, an air chamber under the fuselage, Lippisch-type wings and a large horizontal T-tail. The lift is mainly increased by the stagnation of the accelerated air coming into the air chamber through the channel in the middle of the fuselage. However, the accelerated air increases drag as well as reduces static height stability.

• Proceedings of the KIEE Conference
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.187-189
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• 1999

Accurate load models allow more precise calculations of power system stability, This paper presents new static voltage stability index considering the load models. Also, We apply the load models for the existent voltage stability indices, and evaluate them.

• Journal of Electrical Engineering and Technology
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• 제1권3호
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• pp.313-319
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• 2006

This paper addresses improving the voltage stability limit of interface flow between two different regions in an electric power system using the Static Synchronous Series Compensator (SSSC). The paper presents a power flow analysis model of a SSSC, which is obtained from the injection model of a series voltage source inverter by adding the condition that the SSSC injection voltage is in quadrature with the current of the SSSC-installed transmission line. This model is implemented into the modified continuation power flow (MCPF) to investigate the effect of SSSCs on the interface flow. A methodology for determining the interface flow margin is simply briefed. As a case study, a 771-bus actual system is used to verify that SSSCs enhance the voltage stability limit of interface flow.

• Journal of Advanced Marine Engineering and Technology
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• 제24권2호
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• pp.63-71
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• 2000

This paper deals with a systematic approach to GA-PI controller design for static VAR compensator(SVC) using genetic algorithm(GA) to improve system stability. Genetic algorithms(GAs) are search algorithms based on the mechanics of natural selection and natural genetics. To verify the validity of the proposed method, investigated damping ratio of the eigenvalues of the electro-mechanical modes system with and without SVC. Also, we considered dynamic response of terminal speed deviation and terminal voltage deviation by applying a power fluctuation at heavy load, normal load and light to verify the robustness of the proposed. Thus, we proved usefulness of GA-PI controller design to improve the stability of single machine-bus with SVC system.

• Journal of Advanced Marine Engineering and Technology
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• 제35권5호
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• pp.690-699
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• 2011

A numerical model analysis was performed to analyze the stability of the mooring lines of an automatic submersible fish cage system in waves and currents. The fish cage system consisted of a 12-angled rigid frame, net cage, cover net, 12 upper floats, 12 tanks(for fixed and variable ballast), mooring lines, anchors, and a control station. Simulations were performed with the cage at the surface of the water and at a depth of 20 m. A Morison equation type model was used for simulations of the system in two configurations. The force parameters described both regular and random waves, with and without currents, and their values were input to the model. Mooring tension calculations were conducted on the mooring lines, grid lines and lower bridle lines of the cage. The stability of the mooring lines was checked under both static and dynamic conditions.

• Journal of Institute of Control, Robotics and Systems
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• 제11권11호
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• pp.913-919
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• 2005

An advanced method of Relaxed Static Stability (RSS) is utilized for improving the aerodynamic performance of modem version supersonic jet fighter aircraft. The flight control system utilizes RSS criteria in both longitudinal and lateral-directional axes to achieve performance enhancements and improve stability. Standard CLDA (Control Law Design and Analysis) process is provided that reduce the development period of the flight control system. In addition, if this process is employed in developing flight control laws, it reduces the trial and error development and verification of control laws. This paper details the design process of developing a flight control law for the RSS aircraft, utilizing military specifications, linear and nonlinea, analysis using XMATH and ATLAS(Aircraft, Tim Linear and Simulation), handling quality tests using the HQS (Handling Quality Simulator), and real flight test results to verify aircraft dynamic flight responses.