• Journal of Welding and Joining
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• v.16 no.3
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• pp.44-54
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• 1998

In this study a new arc sensor algorithm for automatic weld seam tracking was proposed, which uses the relative welding current variation according to the tip-to-workpiece distance in GMA welding. Since the new developed arc sensor algorithm is not sensitive to unstable factors of arc signal, the system is expected to get rid of the problems of already existing arc sensor system which include the difficulty of modeling the process for various welding conditions and limitation of application to thick plate welding. Thus the system is applicable not only to thick plate welding but also to thin plate welding. To implement the new arc sensor algorithm the system parameters which include sampling time, averaging range, weighting factor of moving averaging, basic compensation time, and basic compensation distance were determined by experimental analysis. Consequently this system has shown the successful tracking capability for the various welding conditions.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.399-404
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• 2006

Heating and cooling load of ventilation is a very important part of building energy saving. Improving ventilation effectiveness can save building energy consume and supply fresh air to indoor efficiently. So this study measured mulity-zone aiflow and ventilation effectiveness according to ventilation types. Result of measurement show that ventilation effectiveness is depends on ventilation system design rather than ventilation types.

• Journal of Urban Science
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• v.9 no.2
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• pp.13-20
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• 2020

The Recently, several countries have been affected by respiratory diseases, resulting in renewed research interest in their prevention and control. One such example was the 2015 outbreak of Middle East Respiratory Syndrome (MERS) in South Korea and COVID-19. In this study, we performed experiments and simulations based on concentration decay using CO2 as the tracer gas to elucidate the pollutant-removal efficiency for different inlet and exhaust locations and outdoor air-supply ratios. The wall inlet exhibited a higher pollutant-removal efficiency, owing to the upward movement of the air from the lower zone to the upper one. In conclusion, it is recommended that a total air-conditioning plan for isolation rooms be established as well as efficient system operation for pollutant removal and air-flow control to prevent the transmission of infections from the patients to others.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.28 no.6
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• pp.452-462
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• 1999

환기란 실내에 기류분포를 형성함으로써 발생된 오염물질을 제거하고 재실자에게 신선외기를 공급하기 위한 것이다. 실내의 오염농도는 오염 발생원의 특성과 실내의 환기상태에 의하여 결정되며 환기상태는 실내의 기류분포에 의하여 결정된다. 건축물에서 수행되고 있는 각종 오염물질에 대한 농도측정 실험은 환기의 결과로서 나타나는 실내오염의 정도를 파악하기 위한 것으로 환기의 성능 자체를 측정하기 위한 것이 아니다. 또한 실내의 기류속도 측정실험을 통하여 환기상태를 간접적으로 파악할 수 있으나 정량적인 환기 상태를 측정하지는 못한다. 단순히 기류속도가 크고 작음에 따라서 환기상태의 좋고 나쁨을 표현할 수 없기 때문이다. 그림 1은 이와 같은 환기실험에 관련된 3단계의 실험 종류와 이들 간의 상호 상관관계를 보이고 있다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.4
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• pp.348-353
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• 2008

Oxygen isotope has not been used actively in water mass studies because of difficulties on the analysis though it has advantages as a water mass tracer. The most popular method to analysis the oxygen isotope ratio in water samples is equilibration method: isotopic equilibrium of water with $CO_2$ at constant temperature. The precision of oxygen isotope analysis using commercial automatic $H_2O/CO_2$ equilibrator is ${\pm}0.1%o$. This value is not sufficient for studies in open ocean. The object of this study is to improve the analytical precision enough to apply open ocean studies by modification of the instrument. When sample gas is transferred by the pressure difference, the fractionation which is preferential transportation of light isotope can be occurred since the long transportation path between the equilibrator and mass spectrometer. And the The biggest source of error during the analysis is long distance and large volume of the pathway of sample gas between. Therefore, liquid nitrogen trap and high vacuum system are introduced to the system. The precisions of 14 time analysis of same seawater sample are ${\pm}0.081%o$ and ${\pm}0.021%o$ by built-in system and by modified system in this study, respectively.

• Solar Energy
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• v.12 no.1
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• pp.88-94
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• 1992

A small-scale solar collector and tracking system, using a Fresnel lens of $0.5m^2$, and novel compact fluidized-bed solar receiver[FBR] of closed type has been developed for high temperature solar gas heating. The FBR was improved in carrying over of SiC powder and thermo-siphon effect. The maximum outlet air temperature of 1140K and the maximum thermal efficiency of 64% were obtained. The present FBR's operated efficiently at extremely high temperatures in comparison with conventional solar receivers, composed of flat or tubular solid surfaces.

• KIEAE Journal
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• v.4 no.3
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• pp.103-107
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• 2004

This paper aims for evaluating the wind-driven ventilation in basement parking lots of apartment. Wind tunnel tests coupled with tracer gas method were conducted, and classified by wind directions and opening types. The test results showed that, as for wind-driven ventilations, stack type openings were more successful than scuttle vent. Finally, according to Weibull distribution in Seoul, yearly averaged wind-driven ventilation rate was calculated.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05d
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• pp.71-74
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• 1996

원자력시설의 비상사태시 대기중으로 방출된 방사성 물질로부터 주변 주민 및 환경이 받는 영향을 신속·정확하게 평가하고 그 피해를 최소화하기 위해 실시간 방사선 피폭해석 시스템을 개발하였다. 수립된 대기 확산모델의 검증 및 정확도 향상을 위하여 야외 확산실험이 수행되었다. 대기 확산모델의 계산결과와 실험을 통하여 관측된 추적자 가스의 농도 분포를 상호 비교한 바 어느 정도 일치하고 있었다. 그러나 일부 경우에서는 관측된 농도값과 계산된 농도값이 차이를 보이고 있는데, 이는 실험 대상 지역에서 충분한 기상 관측을 수행하지 못하여 시간에 따른 풍속의 변화를 확산모델에 자세히 반영하지 못하였기 때문이었다.

• 사료
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• s.62
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• pp.54-57
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• 2013

차랑 등의 수송연료인 휘발유나 경유에 일정비율을 식물에서 뽑아낸 신재생연료 즉 바이오 연료를 혼합하여 공급하도록 의무화하여 온실가스 배출을 줄이기 위한 신재생연료 혼합의무제도(RFS) 국내 시행방안과 관련한 공청회가 지난 2월 15일 서울교육문화회관에서 지식경제부 주최와 한국석유관리원 주관으로 개최됐다. 정부는 2020년까지 경유나 휘발유에 바이오 디젤 에탄올을 4~5% 섞게 하여 동 기간까지 온실가스 감축목표량 중 8~10%까지 달성한다는 계획을 세워놓고 있다. 하지만 녹색연대 등 민간단체들은 온실가스 감축 효과는 매우 불확실하며 특히 어떤 원료를 쓰느냐에 따라 오히려 기후변화를 악화시킬 수 있다는 주장과 산림훼손, 세계 곡물가 상승, 국내 유가 상승 등 많은 문제점들이 있음을 우려해 강하게 반대를 표명하고 있는 입장이다. 우리 협회에서도 곡물을 이용한 에탄올의 혼합의무가 시행되는 경우 옥수수 등 사료원료가격의 상승으로 가뜩이나 어려운 축산업의 경영상황을 더욱 약화시키게 될 것이 예견되는 바, 동 혼합의무제도의 시행을 적극 반대하는 대 국회 및 정부활동을 전개한 바 있다. 그 결과 지난 4월 17일 국회 지식경제위원회 법률심사소위원회에서는 신재생연료 혼합의무제도의 시행 시기를 2년간 유보하고 혼합의무연료에서 에탄올을 제외시키는 방안을 논의한 바 있어 향후 입법과정에 관심이 모아지고 있다. 이에 따라 본지는 이번 RFS의 국내 시행과 관련하여 어떠한 문제점들이 있는지 관련 업계 종사자의 글을 통해 알아본다.

• Conservation Science in Museum
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• v.3
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• pp.71-78
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• 2001

The airtightness of museum cases in museums was measured by using CO₂ tracing gas, but it has been pointed that it has a problem with measuring the airtightness of a museum case which has a hole inside before it is used or while is being used. So studies tried to come up with alternatives which make it possible to measure the airtightness of a museum case before it is used or while it is being used if necessary by indirectly measuring the airtightness of the museum case without changing its form. Indirect measuring is done by measuring the change of Art-sorb weight and the change of temperature and humidity inside the museum case. Experiments were made for 12 days with three builtin wall case installed at the same place without turning on the lights but with Art-sorb and the data logger of temperature and humidity put into museum case. The change rate was produced with the change of temperature and humidity inside the museum case divided by that of those around museum case. As a result, the temperature change rate of museum case A(0.67) was lower than that of museum case B(0.69) or museum case C(0.79). The humidity change rate of museum case A(0.12) was lower than that of museum case B(0.19) or museum case C(0.72) showing that its airtightness was the best. Also in the direct airtightness measurement by CO₂ tracing gas, the air exchange rate was compared with the humidity change rate by Art-sorb in the indirect measurement.