• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.501-506
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• 2020

In this experimental study, we have analyzed aerodynamic performance of the four representative types of passenger car vehicles, different types of side window angles, different types of engine hood angles, and the angle difference of the roof line in order to comprehensively analyze how the aerodynamic performance varies with different shape of vehicle. Experiment results showed that the rear window falling at aa certain angle lowered aerodynamic performance, angle difference of the lowered roof line did not affect aerodynamic performance, and the back window line falling at certain angles had no visible effect on aerodynamic performance. Back window line leaning towards front side may help enhance styling aesthetics, but aerodynamic performance decreased. In case of rear diffuser installation, aerodynamic performance also decreased.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.2
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• pp.95-103
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• 2018

As a guideline for desulfurization and dehumidification pretreatment facility for optimizing utilization of biogas, the $H_2S$ concentration is set at 150 % which can be treated with iron salts, dehumidification is the optimum value for generator operation, and the relative humidity applied at the utilization of biogas in EU is set at 60 %. We have set up the generator facility guidelines to optimize utilization of biogas. The appropriate amount of biogas should be at least 90 % of the total gas generation, and the capacity of generator facility should be set at 20~30 %. In order to equalize the pressure of the incoming gas the generator, a gas equalization tank should be installed and the generator room average temperature should be kept at $45^{\circ}C$ or less. Since the gas is not produced at a certain methane concentration in the digester, the efficiency is lowered. Therefore, it is required to install an air fuel ratio control system according to the change in methane concentration. Therefore, it is necessary to compensate for the disadvantages of biogasification facilities of organic waste resources and optimize utilization of biogas and improve operation of facilities. This study was conducted to optimize biogas utilization of type of organic waste(containing sewage sludge and food waste, animal manure), investigate the facilities problem and propose design, operation guidelines such as pre-treatment facilities and generators.

• Geophysics and Geophysical Exploration
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• v.9 no.4
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• pp.304-315
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• 2006

We have examined the applicability of f-k analysis to the GPR direct wave measurement for water content to characterize vadose zone condition. When the vadose zone consists of a dry surface layer over wet substratum, we obtained f-k spectra where most of the energy is bounded by the air and dry soil velocities. In this case, dry soil velocity was successfully estimated by using high frequency data. On the other hands, when wet soil overlies dry substratum, the f-k spectra show a contrasting response where most of the energy travels with the velocity bounded by dry and wet soil velocities. In this case, the radar waves are trapped and guided within wet soil layer, exhibiting velocity dispersion. By adopting modal propagation theory, we could formulae a simple inversion code to find two layer's dielectric constants as well as layer thickness. By inverting the velocity dispersion curve obtained from f-k spectra of synthetic modeling data, we could obtain good estimates of dielectric constants of each layer as well as first layer thickness. Moreover, we could obtain more accurate results by including the higher mode data. We expect this method will be useful to get the quantitative property of real subsurface when the field condition is similar.

• 건축구조
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• v.17 no.3
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• pp.41-47
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• 2010

현대산업사회에서는 혁신적인 디자인, 초대형, 장스팬 등 구조엔지니어링이 필요한 다양한 건축물들이 시공되고 있으며, 포스트텐션 공법은 이러한 기술적 요구를 수용하는데 있어 좋은 해결방법의 하나로 적용이 늘어나고 있는 공법이다. 이에 본지에서는 지난호(3월)의 "포스트텐션 공법의 소개"에 이어 경제성을 비교분석하여 포스트텐션 공법적용의 장점을 소개하고자 한다. 경제성 비교에서는 공법에 사용되는 인건비와 재료비 등의 직접비용을 제외한 공기, 유지관리, 해제 등 다양한 요소들이 고려되며, 각 건물의 특성에 따라 달라지므로 명확한 경제성 분석을 하기는 힘들다. 그러므로 본 기사에서는 포스트텐션 공법의 경제성에 영향을 주는 요소들을 분석하고, 각 구조 공법의 상대비용을 비교하여 포스트텐션 공법 적용을 위한 가이드라인을 제공하고자 한다.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1164-1169
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• 2008

The miniaturization of the Air Handling Unit (AHU) has become an actual need because of the restriction of the using space on the vessel. In modern AHU’s construction, in which the fan section is at the end part of the ship, it’s very difficult to select a suitable capacity of evaporators, because the fan motor emits heat. Thus, the AHU structure has been changed as the fan section has been set before the cooling coil to get temperature values similar to the designed amount. Also, the air guider is installed in order to maintain equal air distribution after it passed the fan section. So, it is possible for air to equally pass the cooling coil. It is investigated three different geometries to find the best performance. Also, It is compared with the numerical and experimental results. The study found the case 3 gives the best results. The results of this study show the possible application of the new design.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.11a
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• pp.292-293
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• 2018

여가생활과 건강에 대한 관심이 증대함에 따라 웰니스와 휴양과 관련한 컨텐츠가 요구되면서 산림치유, 해양치유와 같은 헬스 투어리즘에 대한 관심이 높아지고 있다. 산과 바다를 모두 갖고 있는 우리나라의 경우 치유산업의 발전가능성이 충분하고 치유자원 발굴, 효능에 관련된 연구도 진행되고 있다. 해양치유시설은 프로그램에 맞게 제어 가능한 실내에 비해 옥외활동에는 가능한 시간, 기후가 한정되어 있으며 지역특성에 따라 달리 적용되어야 함에도 불구하고 아직 명확한 기준이 미비하다. 이에 본 연구는 해양치유 옥외활동에 적합한 기후환경 가이드라인 개발을 위해 온열환경, 풍환경, 공기환경 및 체감온도, 불쾌지수와 같은 생활지수와 같은 항목을 정리하고 해당 데이터를 활용하여 옥외활동을 할 수 있는 시간, 기후 등 판단기준을 작성하고자 한다.

• Proceedings of the Safety Management and Science Conference
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• 2008.11a
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• pp.247-258
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• 2008

우리나라는 2000년에 제조물책임법이 제정하여 2002년 7월 1일부터 시행하였으며, 제조물의 제조, 설계, 표시등의 결함으로 인하여 발생한 손해에 대한 제조업자 등의 손해 배상책임을 규정하고 소비자의 결함 입증부담 경감과 피해자의 보호를 도모하자 하고 있다. 제조물의 표시등의 결함은 지시결함이나 경고결함에 관한 것으로 제조자는 그 위험에 의한 사고를 방지 회피할 수 있도록 소비자에게 정보를 제공하여야 하나 이를 이행하지 않아 발생된 결함이다. 본 논문에서는 A사(社)의 공기정화기 B모델 사용설명서에 나타난 정보제공사항을 주의 경고표시 가이드 등에 따라 검토하였으며, 그 결과 일부 지시 및 경고사항에서 보완해야할 사항이 발견하였다. 보완사항은 제안사항으로 기업내부 에서 처리하되 전문성이 부족한 분야는 외부의 PL전문가의 협력하에 바람직한 개선안이 도출될 수 있을 것이다.

• Journal of Bio-Environment Control
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• v.18 no.3
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• pp.215-224
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• 2009

A survey on the actual state of heating, cooling, ventilation, and air-flow and experimental measurement of temperature and humidity distribution in tomato greenhouse were performed to provide fundamental data required in the development of air-flow control technology. In single-span plastic houses, which account for most of 136 tomato greenhouses surveyed, roof windows, ventilation and air-flow fans were installed in a low rate, and installation specs of those facilities showed a very large deviation. There were no farms installed greenhouse cooling facilities. In the hot air heating system, which account for most of heating type, installation specs of hot air duct showed also a large deviation. The exhaust air temperature and wind speed in hot air duct also were measured to have a big difference depending on the distance from the heater. We are using the maximum difference as indicator to determine whether temperature distribution is uniform. However if the temperature slope is not identical in greenhouse, it can't represent the uniformity. We analyzed relation between the maximum difference and the uniformity of temperature and humidity distribution. The uniformity was calculated using the mean and standard deviation of data from 12 measuring points. They showed high correlation but were represented differently by linear in the daytime and quadratic in the nighttime. It could see that the uniformity of temperature and humidity distribution was much different according to greenhouse type and heating method. The installation guidelines for ventilation and air-flow fan, the spread of greenhouse cooling technology for year-round stable production, and improvement of air duct and heating system, etc. are needed.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.985-988
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• 2008

Maglev is a system that a train runs levitated above a rail. Therefore it is very important to maintain a constant levitation gap for achieving serviceability and ride comfort. This study is a cooperation research subject of the 3-1 subject, performance improvement of maglev track structures, of the Center for Urban Maglev Program in Korea, started in 2006. The aim of this study is development of rapid constructions of bridge superstructure for maglev. At present, precast deck is widely used because of its superiority to cast-in-place concrete on quality and the term of works. The research group suggested basic systems of maglev guideway with PSC-U type and trapezoidal open steel box type girder, and precast deck, cooperating with Korea Railroad Research Institute, the managing institute of the 3-1 subject. In this study, full-scale structure was fabricated for structural safety evaluation of precast decks and rail, and a static performance test of those structures was performed.

• Journal of Animal Environmental Science
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• v.17 no.3
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• pp.155-162
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• 2011

This study was conducted to suggest the measurement procedure and to build up national greenhouse gas inventory database of animal agricultural sector by assessing methane and nitrous oxide emissions according to IPCC guidelines for national greenhouse gas inventory report in order to correspond to the Climate Change Convention. Ten house-made steady-state Half dome floating chambers were used to collect air samples emitted from slurry stored in the pit under the slat. Those chambers were spread out in order that air samples might represent the whole area of slurry under the slat. Fresh air was pumped into the chambers by $5{\sim}9{\ell}/min$ and air inside the chambers was sampled by $1{\ell}/min$. Surplus air by the higher flow rate of fresh air than sampling flow rate was passed through a hole on the top of chambers. Nitrous oxide fluxes measured from 10 locations would be negligible as concentrations between background air and sampled air from the chambers were within the error range. However, mean $CH_4$ fluxes were $0.15{\sim}1.02mg/m^2{\cdot}s$. The application of continuous greenhouse gas measurement techniques would be preferred if the patterns of greenhouse gas emissions are considered.