• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.6
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• pp.519-529
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• 2010

In the present study, unsteady calculations have been performed to simulate flows around a UH-60A full configuration including main rotor, fuselage, and tail rotor. A flow solver developed for helicopter aerodynamic analysis was used for the simulation of the complete helicopter in high-speed and low-speed forward flight. Unsteady vibratory loads on the main rotor blades were compared with flight test and other calculated data for the assessment of the present flow solver. Aerodynamic interaction of the three components of the helicopter was investigated by comparing with the results of main-rotor-alone, main rotor and fuselage, and tail-rotor-alone configurations. It was found that the existence of the fuselage has an effect on the normal force distribution of the main rotor by varying downwash distribution on the rotor disc, and tip vortices trailed from the main rotor strongly interact with the tail-rotor.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.4
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• pp.477-486
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• 2010

During sailing by wind-driven thrust on the sail, a catamaran sailing yacht generates leeway and heeling. For predicting sail force, a model test was carried out according to running attitude. Through the model test, drag and side force of the real ship was predicted. A purpose of this study is to find sail force to C.E from changed attitude during running direction. By balance of hull and sail, a heeling force of designed sail is predicted. Also through heeling force and driving force, total sail force and direction from C.E are considered with changed mast including leeway and heeling.

• Proceedings of the Korean Institute of Landscape Architecture Conference
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• 2016.03a
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• pp.25-26
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• 2016

• Proceedings of the Korean Institute of Landscape Architecture Conference
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• 2023.04a
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• pp.105-106
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• 2023

• Proceedings of the Korean Institute of Landscape Architecture Conference
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• 2021.10a
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• pp.71-72
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• 2021

• Journal of the Society of Naval Architects of Korea
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• v.37 no.2
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• pp.30-37
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• 2000

The roll damping characteristics of the three models of a 3ton class fishing vessel, that is the bare hull, hull with bilge keels, and hull with bilge keels and a central wing are investigated by the free roll tests in head waves in a towing tank with the variations of the forward speed, initial angle and OG. The wave length variations are also included. The experimental results are compared with the numerical results of mathematical modellings by the energy method for these three models and the energy dissipation patterns are also compared. The roll damping speed increases, the effect of the waves on the roll damping of the models with the additional devices is negligible due to the much increased damping caused by the lift increase.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.2
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• pp.95-105
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• 2018

Increasing cruise speed is an important issue for the development of the next generation rotorcraft. Among several concepts proposed by previous research, the rotorcraft with ducted fan demonstrates its possibility of high-speed flight. In this study, numerical simulations are conducted to investigate the aerodynamic and flow characteristics of multi-ducted fan in forward flight. The aerodynamic efficiency around front ducted fan is determined by interaction between free-stream velocity and the induced velocity. While flow characteristics of rear ducted fan are dominantly influenced by the front ducted fan. Separation in the front ducted fan occurs faster than that of rear ducted fan, and the separation at duct inlet induces an increase of fan thrust. As a result of interaction effect between each ducted fan, relatively aligned inflow enters to the rear ducted fan. Therefore, thrust of the rear fan is decreased steadily before separation, and sudden changes of thrust in fans occur simultaneously. Due to the pressure decrease on lower surface, the normal force of rotorcraft is reduced with forward speed.

• Venture DIGEST
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• s.73
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• pp.10-11
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• 2005

‘정보 검색’과‘게임’을 양대 축으로 삼아 인터넷 산업의 척후병 역할을 감당하고 있는 NHN. 젊은 생각과 앞선 기술력을 바탕으로 정상의 자리를 지키고 있는 NHN의 최휘영 대표는 올해부터 국내 사업 부문을 맡아 새로운 도약을 위해 역량을 집중하고 있다. 디지털라이프 실현을 향해 떨리는 가슴으로 한걸음씩 전진하고 있는 최대표에게서 설레는 고백을 들어본다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.530-531
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• 2009

• KOREAN POULTRY JOURNAL
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• v.53 no.10
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• pp.116-118
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• 2021

올해 1월 농협목우촌 사장으로 취임한 정종대 대표이사는 코로나-19로 급변하는 유통 식품 트렌드 속에서 쉽지 않은 여건이지만, 목우촌 사업의 새로운 활로를 찾기 위해 공격경영, 따뜻한 경영을 바탕으로 미래산업 대응력 강화에 초점을 맞춰 전진하고 있다. 정종대 대표이사를 만나 취임 후 농협목우촌 사업성과와 앞으로 추진 계획에 대해 들어보았다.