• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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• pp.226-227
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• 2018

Recently, as the interest of the government and the public on energy saving has increased, the airtightness of buildings has been improved to improve the insulation performance of buildings. However, indoor air pollution due to increase of pollution source in indoor space and lack of ventilation is increasing and interest in indoor air quality is increasing. In 2003, the Ministry of Environment enacted and promulgated the Act on Indoor Air Quality Control in Multi-use Facilities. Radon is a naturally occurring radioactive inert gas with colorless, tasteless and odorless nature. The concentration is high in a room where radon can not escape. Although lononggas is naturally occurring, it is not interested in living environment, but it is easily inhaled through human body through respiration and causes lung cancer in long-term exposure. Therefore, this study intends to carry out an experiment for the reduction of radon gas, which is the first carcinogen in indoor air pollution sources.

• Journal of Advanced Marine Engineering and Technology
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• 제13권2호
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• pp.64-77
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• 1989

In this study, the experiments were carried out for the purpose of establishment of aluminium cementation to steel surface by diffusible heat treatment after making the coated film onto the substrate by arc spray method. Also, the microstructure and mechanical properties of the cementation layer produced by this study were inspected for various heat treatment and spraying conditions. Main results obtained are as follow ; 1. The coating film characteristics which have excellent errosion-resistance, high temperature oxidation-resistance are obtained by aluminium penetration heat treatment after making the sprayed aluminum coating film onto the steel substrate. 2. Aluminium diffusion penetration takes place at higher temperature than 660.deg.C, and the more heat treatment time and the higher heat treatment temperature adopted, the deeper diffusion layer obtained. 3. Insert gas arc spraying using argon gas as the carrier gas higher improvement of mechanical property than that of compressed air environment. 4. The coating film characteristics appeared to be improvement of adhesive property, porosity plugging effect by heat treatment in air environment.

• 에너지공학
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• 제22권4호
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• pp.370-375
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• 2013

본 연구에서는 1981년부터 2012년까지의 시계열 자료를 이용하여 도시가스의 수요함수를 추정하고자 한다. 도시가스의 수요함수는 수용가의 도시가스 수요행태에 대한 정보를 제공하여 가격과 같은 주요 정책변수의 효과를 사전적으로 진단하는 데, 그리고 수요예측을 하는 데 유용하게 활용된다. 시계열 데이터를 효과적으로 활용하기 위하여 내생시차변수 모형을 활용하였고, 수요함수의 모수에 대한 강건한 추정치를 얻기 위해 최소자승법 추정법을 사용하였다. 단기 가격탄력성 및 소득탄력성은 각각 -0.522 및 0.874로 추정되었으며 유의수준 1%에서 통계적으로 유의하였다. 단기 가격탄력성은 가격에 비탄력적인 도시가스수요의 특징을 보여주고 있으며, 단기 소득탄력성 역시 비탄력적으로 추정되어 소득 증감에 따라 도시가스의 수요가 크게 변화지 않음을 알 수 있다. 반면, 장기 가격탄력성 및 소득탄력성은 각각 -2.155 및 3.607로 나타나 탄력적임을 알 수 있다.

• KIEAE Journal
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• 제17권4호
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• pp.67-74
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• 2017

Purpose: As the recent climate environment changes so rapidly, environmental problems such as hot weather and fine dust have occurred, and interest in environmental policies and technology development is increasing in countries around the world. Similarly in the Architecture, researches to reduce greenhouse gas emissions and to reduce energy application are actively conducted. Looking at previous studies, it is analyzed that the electric VRF is more energy efficient than the gas engine VRF. However, energy costs have changed due to recent price hikes and discounts on gas charges due to high electricity consumption in summer. Method: In this study, the actual building of Gas Engine VRF system was modeled using SketchUp program, and EnergyPlus was used to simulate actual building. Also, Electric VRF system was simulated, and compared with Gas Engine VRF system. Result: The total secondary energy requirement of Electric VRF system was 19.6% less than that of the Gas Engine VRF system, But when analyzing with primary energy requirement, EHP used 15.8% more energy. CO2 emissions were also estimated to be 16.9% more EHP. Energy costs were 14.8% more in Electric VRF systems, because their electricity charges are 0.6 to 160% more expensive than gas charges.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2006년도 총회 및 춘계학술발표회
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• pp.54-56
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• 2006

Single-well-gas-sparging tests were developed and evaluated for assessing the feasibility of in-situ aerobic cometabolism of trichloroethylene (TCE), using propane as a growth substrate. To evaluate transport characteristics of dissolved solutes [sulfur hexafluoride (SF6) or bromide (non-reactive tracers), propane (a growth substrate), ethylene, propylene (nontoxic surrogates to probe for CAH transformation activity), and DO], push-pull transport tests were performed. Mass balance showed about 90% of the injected bromide and about 80% of the injected SF6 were recovered, and the recoveries of other solutes were comparable with bromide and slightly higher than SF6. A series of Gas-Sparging Biostimulation tests were performed by sparging propane/oxygen/argon/SF6 gas mixtures, and temporal ground water samples were obtained from the injection well under natural gradient 'drift' conditions. The decreased time for propane depletion and the longer time to deplete SF6 as a conservative tracer indicate the progress of biostimulation. Gas-Sparging Activity tests were performed. .Propane utilization, DO consumption, and ethylene and propylene cometabolism were well demonstrated. The stimulated propane-utilizers cometabolized ethylene and propylene to produce ethylene oxide and propylene oxide, as cometabolic by-products, respectively. Gas-Sparging Acetylene Blocking tests were performed by sparging gas mixtures including acetylene to demonstrate the involvement of monooxygenase enzymes. Gas substrate degradation was essentially completely Inhibited in the presence of acetylene, and no production of the corresponding oxides was also observed. The Gas-Sparging tests supports the evidences that the successive stimulation of propane-oxidizing microorganisms, cometabolic transformation of ethylene and propylene by the enzyme responsible for methane and propane degradation.

• 한국가스학회지
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• 제21권1호
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• pp.72-79
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• 2017

극한지 천연가스 배관의 운전온도 범위는 가스 공급을 최적화하고 운전동안 극한지 환경에 대한 충격을 최소화하기 위해 기본적으로 제어되어야 한다. 배관에 흐르는 가스의 온도는 Joule-Thomson 효과와 배관과 토양의 열전달에 의존한다. 따라서 본 연구에서는 매설 천연가스 배관의 열전달과 Joule-Thomson 효과를 상세히 고려하였다. 토양온도는 $0{\sim}-20^{\circ}C$, 총괄열전달계수는 $0{\sim}5.5W/m^2K$로 가정하였다. 토양온도와 총괄열전달계수 변화에 따른 배관 길이방향의 가스온도 변화와 압력손실을 동시에 계산하였다. 또한, 본 연구에서는 HYSYS 프로그램을 사용하여 토양온도와 총괄열전달계수에 따른 상변화와 하이드레이트 생성을 예측하였다.

• 센서학회지
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• 제18권1호
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• pp.72-76
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• 2009

The sensing system was designed and fabricated to investigate the ferment environment of soybeans. $NH_3$ gas was saturated after about 7 h and $CO_2$ gas was reached the peak after about 8 h in the inoculation of Bacillus subtilis. However, times that $CO_2$ gas and $NH_3$ gas were reached maximum value without Bacillus subtilis were about 15 h and 18 h, respectively. The sample that inoculated Bacillus subtils had deeper taste than one without it. We found that the peak time of $CO_2$ gas means the starting time of fermentation. If we control the operating time after the start of fermentation, it is expected to make a suitable Chungkukjang to individual preference.

• 정보통신설비학회논문지
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• 제9권4호
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• pp.147-152
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• 2010

Gas sensor array can be widely applied to atmosphere environment, quality control of food, and medical fields etc. So for the commercialization and popularization of sensor technology, this paper looked into the method to provide users with general purpose smart phone and gas sensor array linked together. The reviewed system can detect unknown gas in the air and inform users using smart phone by arraying 8 kinds of common use gas sensor. This system is composed of the sensor module, communication module between sensor array and smart phone application software. In this paper, this prototype system demonstrate convincingly that the application of Gas sensor array to smart phone is a good outlook.

• 한국분말재료학회지
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• 제26권1호
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• pp.28-33
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• 2019

The gas sensor is essential to monitoring dangerous gases in our environment. Metal oxide (MO) gas sensors are primarily utilized for flammable, toxic and organic gases and $O_3$ because of their high sensitivity, high response and high stability. Tungsten oxides ($WO_3$) have versatile applications, particularly for gas sensor applications because of the wide bandgap and stability of $WO_3$. Nanosize $WO_3$ are synthesized using the hydrothermal method. As-prepared $WO_3$ nanopowders are in the form of nanorods and nanorulers. The crystal structure is hexagonal tungsten bronze ($MxWO_3$, x =< 0.33), characterized as a tunnel structure that accommodates alkali ions and the phase stabilizer. A gas detection test reveals that $WO_3$ can detect acetone, butanol, ethanol, and gasoline. This is the first study to report this capability of $WO_3$.

• 천문학회보
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• 제45권1호
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• pp.61.1-61.1
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• 2020

We examine the HI gas kinematics and distribution of galaxy pairs in group or cluster environment from high-resolution Australian Square Kilometre Array Pathfinder (ASKAP) WALLABY pilot observations. We use 22 well-resolved galaxies in the Hydra cluster of which 4 galaxies are visually identified as pairs and others are isolated ones. We perform profile decomposition of HI velocity profiles of the galaxies using a new tool, BAYGAUD which enables us to separate a line-of-sight velocity profile into an optimal number of Gaussian components based on Bayesian MCMC techniques. All the HI velocity profiles of the galaxies are decomposed into kinematically cold or warm gas components with their velocity dispersion, 4~8 km/s or > 8 km/s, respectively. We derive the mass fraction of the kinematically cold gas with respect to the total HI gas mass, f = log10(M_cold / M_HI), of the galaxies and correlate them with their dynamical mass. The cold gas reservoir of the paired galaxies in the Hydra cluster is found to be relatively higher than that of the isolated ones which show a negative correlation with the dynamical mass in general.