• 한국전자파학회논문지
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• 제17권9호
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• pp.829-835
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• 2006

본 논문에서는 초고출력용 X-band 카세그레인 반사판 안테나 시스템에서 반사판의 표면 형상을 변형시켜 spill-over가 효과적으로 감소하는 현상에 대하여 이론적인 고찰을 수행하였다. 이러한 구조는 이중의 쌍곡면 부 반사판을 적용함으로써 주 반사판의 크기를 확장하지 않고 급전 혼 안테나에서 방사된 전파 패턴의 확장각을 증가시켜 spill-over특성이 감소되도록 설계하였다. 결과적으로 본 논문에서 제안된 카세그레인 반사판 안테나가 기존의 설계 방법에 의한 반사판 안테나에 비해 약 9 %의 효율 향상과 10 dB의 부엽 레벨 감소가 구현됨을 이론적으로 확인하였다.

• 한국자동차공학회논문집
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• 제25권3호
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• pp.389-396
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• 2017

Restorations of automotive parts have been done ever since the first vehicle was produced. Because the most expensive parts of a vehicle are in the engine system, there have been various restoration methods developed for engine parts. In the case of commercial diesel engines, the fuel injection device is a key and expensive component. It also has a significant effect on vehicle performance. In particular, reduced engine power and increased exhaust gas emissions may result from mechanical damage due to abrasion of the spill valve in the fuel injection system of a diesel engine. In this paper, restoration techniques for damaged parts are applied to restore the abrasion of a spill valve of fuel injection, also called as the "unit injector", of commercial diesel engines. In order to recover the damage, optimized polishing techniques using hard-metal and coating processes are applied. To evaluate restoration techniques for the spill valve, performance and durability tests are performed on a test bench.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2017년도 추계학술발표회
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• pp.136-136
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• 2017

• 한국전자파학회논문지
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• 제29권9호
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• pp.722-730
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• 2018

본 논문에서는 FMCW(frequency modulated continuous wave) 신호기반 SAR 시스템의 스퀸트 각도(squint angle) 설정에 따른 복원영상 내 목표물 분산전력패턴 변화를 예측하기 위한 분석기법에 대해 설명한다. SAR 복원영상 내 목표물 분산 전력패턴은 지면에 투영된 전파진행방향과 합성개구면과 스퀸트 각도가 이루는 방위방향에 따라 일정한 방향으로 변형된 특성을 갖게 되며, 이와 같은 특성변화를 3차원 SAR 기하구조 내에서 분석한다. 스퀸트 설정각도에 따라 변형된 목표물 분산전력패턴은 FMCW 신호모델과 back-projection 알고리즘을 기반으로 한 모의실험을 통해 그 분석결과를 검증한다. 또한, 변형된 분산전력패턴의 예측결과는 SAR 기하구조와 스퀸트 설정각도를 변수로 정리된다.

• Strategy21
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• 통권37호
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• pp.193-241
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• 2015

China, Japan and Korea are the world's top 10 energy consumers, and so very interested in the development of seabed hydrocarbon resources in order to meet their energy demands. The East China Sea is the tri-junction area where three countries' entitlements on the maritime boundaries are overlapped. There are abundant oil reserves in the East China Sea, and therefore competitions among countries are growing to get control of them. Although these countries have concluded the bilateral agreements to jointly develop resources in the East China Sea, they do not function as well. Because joint development and management of seabed petroleum resources can lead to stable development system, and to lower possibility of legal and political disputes, the needs for joint development agreement among three countries are urgent. Meanwhile, Northeast Asian seas are semi-closed seas, which are geographically closed and vulnerable to marine pollution. Moreover there are a lot of nuclear power plants in coastal area, and seabed petroleum resources are being developed. So it is likely to occur nuclear and oil spill accidents. Fukushima nuclear disaster and Bohai Bay oil spill accident in 2011 are the cases to exhibit the potential of major marine pollution accidents in this area. It is anticipated that the risks become higher because power plants and offshore oil platforms are extending gradually. Therefore, the ways to seek the joint marine environmental protection agreement focused on regulation of nuclear power plant and offshore oil platform have to be considered. In this paper, we try to find the way to make joint development and joint environmental protection agreement in Northeast Asian seas. We concentrate on the measure to drive joint development of seabed petroleum deposits in East China Sea's overlap area, despite of maritime delimitation and territorial disputes, and we try to drive joint marine environmental protection system to respond to marine pollution and accidents due to offshore oil platform and nuclear power plants. Through these consideration, we seek solutions to deal with lack of energy, disputes of maritime territorial and boundary delimitation, and marine pollution in Northeast Asia.

• 한국전자파학회논문지
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• 제21권9호
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• pp.979-986
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• 2010

본 논문에서는 합성 개구 레이더(SAR: Synthetic Aperture Radar) 영상에서 SAR 보정용으로 설치된 삼각 전파 반사기(TCR: Trihedral Corner Reflector)의 레이더 단면적(RCS: Radar Cross Section)을 정확하게 추출하는 방법을 연구하고, SAR 보정 정확도를 분석한다. TCR의 이론적 RCS를 geometrical optics(GO)와 physical optics(PO) 방법을 이용하여 이론적으로 계산하고, 측정값과 비교하여 정확성을 검증한다. 이때에 단일 반사는 PO로, 이중 반사는 GO-PO로, 삼중 반사는 GO-GO-PO로 계산하고, 모서리 영향은 PTD(Physical Theory of Diffraction) 방법을 이용하여 이론적 RCS를 정확하게 계산한다. 크기가 다른 5개의 TCR를 설치하고, TerraSAR-X로 그 지역에 대한 위성 영상을 취득하여 그 TCR들에 대한 RCS를 추출한다. 레이더 IRF(Impulse Response Function) 특성에 의해 분산된 전력(power spill)을 모두 구하기 위해 정사각형 모양의 면적(window)을 설정하여 정확하게 RCS를 추출하고, 이 RCS를 이론적 RCS와 비교한다. 면적의 크기와 배경의 레이더 후방 산란 계수 크기에 따른 TCR의 RCS 오차를 계산하며, 최소 적분 면적과 최대 배경 산란계수 크기를 제안한다.

• Nuclear Engineering and Technology
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• 제35권2호
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• pp.91-107
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• 2003

Since DBA(Design Basis Accidents) has been studied rather separately from SA(Severe Accidents) in the conventional nuclear reactor safety analysis, the thermal hydraulics during transition between DBA and SA has not been identified so much as each accident itself. Thus, in this study, the thermal hydraulic behavior from DBA to the commencement of SA has been experimentally and analytically investigated for the long-term cooling phase of LB-LOCA(Large-Break Loss-of-Coolant Accident). Experiments were conducted for both cases of the loop seal open and closed in an integral test loop, named as SNUF (Seoul National University Facility), which was scaled down to l/6.4 in length and 1/178 in area of the APR1400 (Advanced Power Reactor 1400MWe). The core mixture level was a main measured value since it took major role in the fuel heat-up rate, the location of fuel melting initiation and the channel blockage by melting material during SA. Experimental results were compared to MAAP4.03 to assess its model of calculating the core mixture level. MAAP4.03 overestimates the core two- phase mixture level because sweep-out and spill-over and the measures to simulate the status of loop seal are not included, which is against the conservatism. Thus, it is recommended that MAAP4.03 should be improved to simulate the thermal hydraulic phenomena, such as sweep-out, spill-over and the status of loop seal.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.698-701
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• 2007

DAHAN, the first 1 MWe Solar Power Tower system locates north to Beijing where nearby The Great Wall is now under construction with cooperation between China and Korea. Results in predicting the preliminary performance of this central receiver system are presented in this paper. Operating cycles under some typical weather condition days are simulated and commented. These results can be used to assess the impact of alternative plant designs or operating strategies on annual energy production, with the final objective being to optimize the design of central receiver power plants. Two subsystems are considered in the system simulation: the solar field and the power block. Mathematic models are used to represent physical phenomena and relationships so that the characteristics of physical processes involving these phenomena can be predicted. Decisions regarding the best position for locating heliostats relative to the receiver and how high to place the receiver above the field constitute a multifaceted problem. Four different kinds of field layout are designed and analyzed by the use of ray tracing and mathematical simulation techniques to determine the overall optical performance ${\eta}_{field}$ and the spillage ${\eta}_{spill}$.The power block including a Rankine cycle is analyzed by conventional energy balance methods.

• 한국수산과학회지
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• 제36권6호
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• pp.743-748
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• 2003

An oil boom was set up in order to contain diffused oil from spills and for the retrenchment of damage caused by oil Pollution. Therefore, the oil boom anchor needed proper holding power to endure high resistance from flowing streams and to secure the oil boom around the spill, and must dredge directly into the seabed when it is dropped and block oil outflow immediately. This study investigated the holding power of the danforth anchor and the coastal fishing vessel anchor used for oil booms in the KMPRC (Korea Marine Pollution Response Corporation). For each type, a 30 kg and 20 kg anchor were used. The holding power of the danforth anchors were measured by dropping both weights 10 times. However the coastal fishing vessel anchors were dropped only 5 times each, because no substantial differences were found between drops. In the results of the danforth anchors, an anchor awoke occurred in 2 drops of the 30 kg anchor and in 4 drops of the 20 kg anchor, wherein there was no holding power to be measured. With exception to the anchor awoke cases, the maximum holding power of the danforth 30 kg and 20 kg anchors was 250-520 kg and 123-233 kg, respectively. In the case of the coastal fishing vessel anchors of 30 kg and 20 kg, throughout the experiment, there was no occurrence of an anchor awoke. For the 30 kg and 20 kg anchors, the maximum holding power was measured to be 209-230 kg and 155-170 kg, respectively. Therefore, the holding power of the coastal fishing vessel anchor was shown to be much poorer than that of the danforth anchor. However, the holding power of the danforth anchor was very unstable. Due to the occurrences of anchor awoke, there was no holding power and the measurement value of maximum holding power showed too much variation among the drop tests. Also, after the maximum holding power was achieved, anchor awoke occurred easily. In the case of the coastal fishing vessel anchor was much more stabile, because there was no anchor awoke and no instance where holding power failed. Also the maximum holding power was reached quickly and almost no variation occurred among the drop tests.

• 대한안전경영과학회지
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• 제8권1호
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• pp.17-26
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• 2006

Basis frame-work's base in a semiconductor industry have gas, chemical, electricity and various facilities in bring to it. That it is a foundation by fire, power failure, blast, spill of toxicant huge by large size accident human and physical loss and damage because it can bring this efficient, connect with each kind mechanical, physical thing to prevent usefully need that control finding achievement factor of human factor of human action. Large size accident in a semiconductor industry to machine and human and it is involved that present, in system by safety interlock defect of machine is conclusion for error of behaviour. What is not construing in this study, do safety in a semiconductor industry to do improvement. Control human error analyzes in human control with and considers mechanical element and several elements. Also, apply achievement factor using O'conner Model by control method of human error. In analyze by failure mode effect using actuality example.