• Journal of Positioning, Navigation, and Timing
• /
• 제4권1호
• /
• pp.17-23
• /
• 2015

With the increase in the risk of GPS jamming, the development and application of anti-jamming GPS techniques have been actively performed. As the objective performance verification of developed techniques is important, equipment development for verification and discussion on anti-jamming performance test method and procedure have also been conducted. However, most tests are related to the specification of equipment and therefore detailed procedure of the performance verification of an anti-jamming system needs to be developed. In this study, requirements for anti-jamming performance verification were described, and test configurations and performance evaluation items depending on three kinds of test methods (lab test, basic outdoor test, and chamber test) were suggested for anti-jamming performance verification.

• 한국해양공학회지
• /
• 제6권1호
• /
• pp.43-51
• /
• 1992

The hydrodynamic performance of a floating-type OWC (Oscillating Water Column) chamber is studied numerically and experimentally in this study. The numerical approach based on two-dimensional linear theory of floating wave absorber was attempted to design an efficient wave energy absorber, while model test was performed in a wave basin to test a performance of designed model and validate the reliability of developed numerical code. The focus of study is placed mainly on the experimental study to evaluate the principal characteristics of the designed OWC chamber in regular waves. The effects of the variation of wave height on OWC device and of air pressure inside chamber are also presented. Finally, the measured results were compared with computed ones, and it was shown that the designed chamber works with high efficiency $(\eta_H>1$ over most of wave lengths covered by present study. It is therefore concluded that the developed code is capable of being successfully employed to design OWC chambers at various ocean environments, even though there exist some minor discrepancies between measured and computed results.

• 전기학회논문지
• /
• 제59권1호
• /
• pp.152-159
• /
• 2010

This paper describes the actual application of a feedback control loop as a means for minimizing turbine impulse chamber pressure variation during the turbine steam valve tests at a 1,000 MW nuclear power plant. The chamber pressure control loop was implemented in the new digital control system which was installed as a replacement for the old analog type control system. There has been about 40MW of the generator output change during the steam valve tests, especially the high pressure governing valve tests, because the old control system had not the impulse chamber pressure control so the operators had to compensate steam flow drop manually. The process of each valve test consists of a closing process and an reopening process and the operators can make sure that the valves are in their sound conditions by checking the valves movement. The control algorithm described in this paper contributed to keep the change in megawatt only to 6MW during the steam valve tests. Thereby, the disturbance to reactor control was reduced, and the overall plant control system's stability was greatly improved as well.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2006년도 제26회 춘계학술대회논문집
• /
• pp.151-155
• /
• 2006

Bodner-Partom 점소성 모델을 이용하여 액체로켓 연소기 재생냉각 챔버의 구조해석을 수행하였다. 구조해석에 사용한 점소성 모델의 재료상수를 구하기 위하여 구리합금에 대하여 변형률 속도를 변화시켜 인장시험을 상온 및 고온에서 수행하였다. 점소성 모델의 재료상수는 구리합금의 변형률 속도 시험 데이터로부터 구하여 사용하였으며 점소성 모델의 구현은 상용유한요소 해석 프로그램인 Marc의 사용자 서브루틴을 이용하여 구현하였다. 구조해석 결과 냉각 채널은 압력에 의한 영향보다 열하중에 의하여 대부분의 변형이 발생하며 연소기의 작동조건에서 냉각 채널의 안정성 여부를 확인할 수 있었다.

• 한국추진공학회지
• /
• 제10권4호
• /
• pp.69-76
• /
• 2006

Bodner-Partom 점소성 모델을 이용하여 액체로켓 연소기 재생냉각 챔버의 구조해석을 수행하였다. 구조해석에 사용한 점소성 모델의 재료상수를 구하기 위하여 구리합금에 대하여 변형률 속도를 변화시켜 인장시험을 상온 및 고온에서 수행하였다. 점소성 모델은 상용유한요소 해석 프로그램인 Marc의 사용자 서브루틴을 이용하여 구현하였다. 구조해석 결과 냉각 채널은 압력에 의한 하중보다 열하중에 의하여 대부분의 변형이 발생하며 연소기의 작동조건에서 냉각 채널의 구조적인 안정성 여부를 확인할 수 있었다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 추계학술대회
• /
• pp.216-221
• /
• 2003

A thermal vacuum chamber is mainly used to simulate thermal environments of a test satellite in satellite orbits in which daily temperature variations range from 80K to above 400K depending on solar radiation under the vacuum below $10^{-4}$ torr. The test facility is quite complex and consists of expensive parts. So any modification of control software is discouraged in fear of unexpected system failure. The purpose of this study is to develop a realtime dynamics model of the thermal vacuum chamber in view of controller design and simulate its electrical inputs and outputs for interface with a PLC (programmable logic controller). A PLC program that was used in the thermal vacuum chamber is applied to the realtime simulator. The realized simulator dynamics is found to be quite similar to that of the thermal vacuum chamber and serve to an appropriate plant to verify the control performance of a programmed PLC.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2010년도 제34회 춘계학술대회논문집
• /
• pp.10-13
• /
• 2010

75톤급 기술검증용 연소기 시제의 저압 연소시험을 수행하였다. 기술검증용 연소기의 설계 연소압력은 60 bar, 추진제 유량은 243.6 kg/s이다. 그러나 국내 연소시험설비의 여건상 연소압력 30 bar, 추진제 유량 121.8 kg/s의 저압 조건에서의 연소기 작동성 및 연소성능을 검증하기 위한 시험을 수행하였다. 모든 연소시험은 하드웨어의 손상 없이 성공적으로 수행되었다. 본 시험결과는 향후 75톤급 연소기의 설계점 조건에서의 연소성능을 예측하는 기본 데이터로 활용될 수 있을 것이다.

• 한국생산제조학회지
• /
• 제8권5호
• /
• pp.108-114
• /
• 1999

The thermal environmental chamber has been using in maintaining weather condition keeping thermal capacity under heating and cooling load fluctuation and for the performance testing of cooling system or air-conditioner on artificial envi-ronment. In ordder to make the various environmental conditions in the thermal environmental chamber the proper cooling system is necessary to eliminate the heating load produced inside the chamber and to maintain the designed environmental condition. For this reason the optimal design of cooling system and the prediction of performance is also required. This paper describes the prediction of performance of cooling system in the thermal environmental chamber with the capacity of 37,000kcal/hr which is developed for the test of performance in heating mode of heat pump system, In the results this paper is trying to develop simulation program on the base of mathematical models and which can be applied effectively to the optimal design of cooling system and prediction of performance to the inside and outside change of envi-ronmetal load.

• Journal of Mechanical Science and Technology
• /
• 제18권6호
• /
• pp.1010-1018
• /
• 2004

This study presents the methodological aspects of combustion instability modeling and provides the numerical results of the model (sub-scale) combustion chamber, regarding geometrical dimensions and operating conditions, which are for determining the combustion stability boundaries using the model chamber. An approach to determine the stability limits and acoustic characteristics of injectors is described intensively. Procedures for extrapolation of the model operating parameters to the actual conditions are presented, which allow the hot-fire test data to be presented by parameters of the combustion chamber pressure and mixture (oxidizer/fuel) ratio, which are customary for designers. Tests with the model chamber, based on the suggested scaling method, are far more cost-effective than with the actual (full-scale) chamber and useful for injector screening at the initial stage of the combustor development in a viewpoint of combustion instabilities.

• 한국산학기술학회논문지
• /
• 제15권7호
• /
• pp.4588-4594
• /
• 2014

본 연구에서는 연약지반에서의 경량콘크리트포장을 적용할 때의 안전성 평가를 위해 실제 포장체 사이즈의 1/30으로 축소한 모형을 이용하여 모래지반에서 실험을 실시하였다. 모형토조를 이용하여 지반을 조성하였고, 표준 말뚝재하시험(완속재하시험방법)을 이용하였다. 수직하중이 적용되는 말뚝기초의 슬래브의 중심에서 가까운 순으로 Case A, Case B, Case C로 구분하였고, 각각의 말뚝의 간격은 8cm로 하였다. 말뚝기초 모형시험결과 사질토지반에서 수직하중을 1.5kg에서 12kg로 증가시킬 때 포장체가 전체적으로 침하하였고, 최대 침하량은 0.4mm로 측정되었다. Case A의 경우 압축력을 받는 것으로 나타났으며, Case B는 수직하중이 증가함에 따라 말뚝에 압축력과 함께 인장력도 같이 받는 것으로 보이며, Case C는 하중단계가 증가할수록 인장변형이 증가하는 경향을 나타내었다.