• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.4
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• pp.53-63
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• 2002

The high speed wind tunnel test for the study of the basic aerodynamic characteristics of the rocket with twin strap-on boosters was performed using ADD trisonic wind tunnel on the Mach number range of 0.4~4.0. The 6 % scale model of the early design version of Korean sounding rocket was tested. The tested configurations were core only, core/fins, core/boosters and core/boosters/fins. The effects of core length, gap between core and booster, and bank angle were investigated.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1288-1289
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• 2015

본 논문은 고속 주행하는 소형의 수중 운동체의 롤 제어기에 대한 연구를 정리한 결과이다. 모형 PMM 시험의 롤 관련 유체력 계수 값의 오차가 커서 실해역 시험에서 시뮬레이션 결과와는 다른 진동현상이 발생하였으나, 시험 결과를 이용한 튜닝과정을 통하여 안정적인 롤 제어 성능을 획득할 수 있었다.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.874-882
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• 2008

To test the current collection characteristics between overhead contact lines and pantograph in a real speed scale costs too much, therefore, it is very difficult to be realized especially in a high speed region. As a alternative, the speed scale-downed tests is proposed. In this paper, the experimental methodology and effectiveness of the speed scale-downed tests are discussed through the dynamic simulation evaluations. To get a more precise test results to the real speed scale test in the 1/2 and 1/4 speed scale-downed tests, various experimental conditions are discussed. Throughout the simulation in a various conditions the effectiveness are evaluated.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.1
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• pp.65-76
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• 1996

A screw propeller is usually accepted as a propulsor of many kinds of ships. However, for high speed vessels, screw propeller has large cavitation area on the blades so propeller efficiency is decreased and erosion can be happened. To avoid this problem, supercavitating propeller and waterjet are generally used for high speed vessels. In this paper, we introduced the self-propulsion test procedure which has been developed for high speed vessels in Hyundai Maritime Research Institute. The model ship used in experiment represents catamaran about 5.3 m in length. To minimize the experimental errors, two impellers were driven by a single motor. Thrust was calculated by converting the measured pressure to flow rates at the nozzle exit. The test procedure is composed of resistance test, self propulsion test and analysis. In order to measure the pressure, pressure tabs were installed around the nozzle exit and connected to the pressure sensor by vinyl tube.

• Journal of Korea Ship Safrty Technology Authority
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• s.37
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• pp.12-23
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• 2014

본 연구에서는 최근 증가하는 해양레저 수요 및 관심에 따른 대응을 위하여 고속레저 선박을 개발하고 이에 따른 국내 레저선박 건조기술 축적 및 경쟁력 향상을 목적으로 하였다. 따라서 선형 및 도면 개발도 중요하지만 이러한 내용들을 수요자들에게 홍보할 수 있는 정보변환알림시스템 및 홍보영상 매뉴얼도 함께 개발하였다. 따라서 연구 결과물을 통해 수요자 의견을 보다 쉽고 정확하게 반영하여 보트의 제품화를 하도록 하고 이를 통해 경쟁력을 높일 수 있도록 하였다.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.4
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• pp.1-8
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• 1995

This paper is presented determination of the hull form factors about a high speed coastal fishing boat using Fuzzy modeling. That is, the estimation curves of total resistance & EHP(Efficiency Horse Power) are induced by Fuzzy modeling algorithm from data of accumulated hull form factors and are compared with the results of model test. Also, the estimation curves of total resistance & EHP are utilized efficiently in determination the hull form factors about a high speed coastal fishing boat.

• Journal of Navigation and Port Research
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• v.38 no.6
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• pp.585-591
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• 2014

The primary objective of the current work is to predict speed performance of the medium patrol boat over $F_N=0.5$ employing experimental materials based on the CFD before model tests. In other words, the predicted brake powers according to ship speeds are assessed satisfying the main engine capacity. The subject ships are selected the two different stern hull forms. The flow computation are conducted considering free surface and dynamic trim using a commercial CFD code(STAR-CCM+). The resistances of the bare-hull are obtained from CFD. Wave patterns, pressures and limiting streamlines on the hull and velocity distribution in the propeller plane for the two hull forms are compared using CFD. The effective powers of the object ships are assessed based on CFD. Resistance increase according to the attached appendages and quasi-propulsive efficiency are employed the experimental datas. Speed performance prediction method concerning high speed vessels like a medium patrol boat is developed employing CFD and experimental data.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.39-46
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• 2023

In this study, the dynamic behavior of friction bearings of PSC (Pre-Stressed Concrete) box train continuous bridge was numerically analyzed at 10 km/h intervals up to 600 km/h according to the increasing speed of the next-generation high-speed train. A frame model was generated targeting the 40-meter single-span and two-span continuous PSC box bridges in the Gyeongbu High-Speed Railway section. The interaction forces including the inertial mass vehicle model with 38 degrees of freedom and the irregularities of the bridge and track were considered. It was calculated the longitudinal displacement, cumulative sliding distance and displacement speed of the bridge bearings at each running speed so that compared with the dynamic behavior trend analysis of the bridge. In addition, long-term friction test standards were applied to evaluate the durability of friction plates.

• Journal of the Korean Society for Railway
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• v.11 no.4
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• pp.384-389
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• 2008

The ballast, one of track components, plays an essential role as intermedium in transmitting train load to subgrade safely, and the deterioration of ballast directly effects the growth of track irregularity. In this study, we determined the main factor of ballast deterioration was miniature of ballast gravel caused MTT (Multiple Tie Tamper) works and accumulated traffic loads. To estimate the deterioration characteristics of ballast, we carried out field test (Chap.2) through track construction for test and the model test (Chap.3) simulating the actual operation environment, have done a comparative analysis with the sample's result (crushing rate) of high-speed railroad running actually.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.5
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• pp.601-608
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• 2019

In this study, the effect of hull appendages on the high-speed catamarans with reverse bow shapes is compared and analyzed by numerical analysis and circulating water tank model test. The reverse bow shape showed an improved wave shape by shifting the generation position of forward divergent wave to the stern direction and was effective in resistance and stable running posture (Kim et al., 2019). In the model test results of the running performance as the wave patterns and the change of the running posture due to the fin fitted with the inner side of the inverted bow and the interceptor, 1) Trim characteristics of the inverted bow 2) Improvement of superposition of inner wave by Fin 3) The trim control by the fin and the interceptor is considered to be effective in reducing the impact of the two hull connection decks (wetdeck).