• 한국추진공학회지
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• 제15권6호
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• pp.26-37
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• 2011

30톤급 액체로켓엔진 연소기의 개발 기술을 바탕으로 75톤급 기술검증용 내열재 연소기를 제작하였다. 내열재 연소기의 수력학적 특성은 저유량 조건의 수류시험과 점화시험을 통해 점검하였고, 시험결과 수력학적 기능이 양호함을 보여 주었다. 정적조건의 작동성 측면에서 점화링을 이용한 측면 점화방식 역시 적합한 점화기능을 보여 주었다. 그러나 동특성 측면에서 나타나는 특정 주파수의 생성 및 소멸 현상을 이해하기 위한 면밀한 검토가 요구된다. 이를 위해서는 75톤급 연소기의 정격조건에서 연소 시험이 가능한 대형 연소시험설비가 조속히 구축되어야 할 것이다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.69-73
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• 2009

75톤급 액체로켓엔진 연소기의 1/2.5-scale 연소기의 시험 결과를 기술하였다. 연소기의 연소압력은 60 bar, 추진제 유량은 약 89 kg/s 그리고 노즐 팽창비는 12이다. 연소성능 및 재생냉각 성능, 연소기의 내구성 확인을 위한 수회의 설계점 연소시험과 저압조건에서의 작동성 및 연소성능을 검증하기 위한 시험이 수행되었다. 모든 연소시험은 하드웨어의 손상 없이 성공적으로 수행되었다. 본 시험결과는 향후 75톤급 연소기의 저압 연소 조건에서의 시험 가능성을 제시하고, 설계점 조건에서의 연소성능을 예측하는 기본 데이터로 활용될 수 있을 것이다.

• 한국의류학회지
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• 제29권8호
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• pp.1176-1187
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• 2005

The purpose of this study was to evaluate the efficiency of cooling vests developed for farm workers harvesting red pepper in summer. The study was performed using the following two steps: 1) Climatic chamber test, 2) Field test. For the chamber test, a work environment was simulated as $33^{\circ}C$ and $65\%$RH, and the thermo-physiological and subjective responses were measured with and without cooling vests. Twelve young males participated as subjects. For the field test, three farmers participated while harvesting red pepper on the form, in summer. The measurements used were same as in the chamber test. Subjects were tested without any cooling vests, as a control. They were tested wearing vests with 2 frozen gel packs (CV2: Cooling area, $308cm^2$), and vests with 4 frozen gel packs (CV4: Sooting area, $616cm^2$). As a result of the chamber test, rectal temperature($T_{re}$) and mean skin temperature( $T_{sk}$) were lower in both CVs than in Control, and this tendency was statistically significant in CV4 (p<.05). Clothing microclimate temperature ($T_{clo}$) and total sweat rate (TSR) were significantly lower when wearing cooling vests (p<.05) Heart rate (HR) was also lower in wearing cooling vests than in Control, and the speed of recovery to the comfort level was faster when the subjects wore cooling vests. In addition, subjects felt 'less hot, less humid, and less uncomfortable' in both CVs than in Control. Field tests showed a similar tendency with the chamber tests. In particular, wearing the cooling vest was effective in restraining the raise of $T_{clo}$ on the back. It can be concluded that the cooling vest was effective in alleviating heat strain and discomfort in both the chamber test and the field test, despite the cooling area of the cooling vest being just $3.4\%$ of the body surface area ($616cm^2$).

• 자동차안전학회지
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• 제11권4호
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• pp.50-56
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• 2019

Recently, automobile industries have developed ADAS, smart cars, connected cars, automated driving systems, which use a variety of sensor systems - ultrasonics, cameras, lidars and radars - and communication systems. It is necessary to examine the electromagnetic immunity of vehicles equipped with those systems. The electromagnetic immunity tests are carried out in an electromagnetic semi anechoic chamber, which is cut off from the outside. It is difficult to create test environments in which the radar sensor systems of vehicles work properly in the test chamber. In this study, test jigs were designed and tested and as a result they are shown to be effective to create test environments for electromagnetic immunity tests of vehicles equipped with radar sensors. We also proposed additional safety standards for immunity tests of vehicles with radar systems that currently do not exist.

• 자동차안전학회지
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• 제12권4호
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• pp.7-12
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• 2020

Recently, automobile industries have developed ADAS, smart cars, connected cars, automated driving systems, which use a variety of sensor systems - ultrasonics, cameras, lidars and radars - and communication systems. It is necessary to examine the electromagnetic immunity of vehicles equipped with the sensor systems due to the fact that the normal operation of those systems is very important to the safety of the vehicles. The electromagnetic immunity tests are carried out in an electromagnetic semi anechoic chamber, which is cut off from the outside. It is difficult to create test environments in which the camera sensor systems of vehicles work properly in the test chamber. In this study, test jigs were designed and tested and as a result they are shown to be effective to create test environments for electromagnetic immunity tests of vehicles equipped with camera sensors. We also proposed additional safety standards for immunity tests of vehicles with camera systems that currently do not exist.

• 설비공학논문집
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• 제23권5호
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• pp.375-382
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• 2011

Semi volatile organic compounds (SVOCs) are used as plasticizers in building materials, interior materials, furniture, consumer electronics. etc. In the home, these SVOCs mix together with house dust. There is thus concern over the health effects of SVOCS in the home, there is a risk that they ini1uence childhood asthma and allergies. It is difficult to measure SVOCs emission rates from building materials or household appliances utilizing the usual test chamber methods, because the boiling points of SVOCs are higher and they are apt to adhere to the surface of the test chamber used. In this study, we introduce FLEC chamber method, passive sampler method and micro chamber method, which are used in Germany and Japan in order to measure SVOCs emission rates. Characteristic, merits and demerits of test methods are also considered.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계 학술대회논문집(수송기계편)
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• pp.101-104
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• 2005

This study presents experimental results from the performance test of a scaled reverberation chamber for measurement of sound insulation of panels. Experimental investigations were conducted in various parameters such as tunneling effect source locations, and maximum sound transmission loss. It is evident that the tunneling effect which means the variation with specimen location on the test frame gives rise to more than 3 dB deviation. One of the objective of this study that compares measured results between a real reverberation chamber and a simplified test apparatus, by using a specimen of a sandwich panel. It shows qualitatively resonable agreement from which one can find a potential to provide a design tool.

• 한국항해학회지
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• 제20권3호
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• pp.107-115
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• 1996

With the rapid advance of electronic equipments and the frequent, use of them, the electromagnetic environments including EMC or EMI problems are very complicated. The radiation of electromagnetic waves from electronic equipments has strictly been controlled by the authorities concerned from many years ago. Though it is the most proper to test EMI or EMC in the open area test site, we have used the anechoic chamber in place of the test site because of its various restrictions. To achieve the purpose, in this paper, the performances of a few anechoic chambers according to absorbing materials are analyzed for horizontal and vertical polarizations respectively. Furthermore, the calculated and the measured site attenuations in semi-anechoic chamber made with ferrite grid are compared. The obtained results are to be valuable for designing an anechoic chamber.

• 전기전자학회논문지
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• 제16권4호
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• pp.290-296
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• 2012

본 논문에서는 반무반사실내에서 반사체와 시간영역 측정을 이용한 반사파의 효과적인 억제 기술을 제안하고 있다. 제안한 기법을 이용하여 측정 영역상에 전기장의 균일도를 향상시켜 완전 무반사실과 유사한 안테나 측정환경을 구현할 수 있었다. 구현한 측정환경의 성능은 측정을 통하여 검증하였으며 소형 VHF대역 안테나 측정에 사용 가능할 것으로 판단된다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.427-430
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• 2008

Electroforming is one of the key technologies for the regenerative thrust chamber of the rocket engine. To use nickel electroforming method for the thrust chamber, direct electroforming of nickel on cupper and the welding method between different materials are needed. Minimizing the internal stress is one of the important factor for making thick electroforming,. Also minimizing contamination(ex. Sulfur containing compound) is another important factor for the stability of quality. This paper includes advanced methods for thick nickel electroforming, those of strength test results and EDS/EPMA inspection results. Advanced for electroforming process makes the achievement of Electro-beam welding between Inconel718(Manifold) and Nickel Electroforming. This paper also includes the influence of the electroforming precipitation angle on strength. Thus advanced electroforming improvement processes and the test results make achievement for manufacturing of the regenerative thrust chamber with direct nickel thick electroforming on cupper materials.