• Journal of Korean Society for Atmospheric Environment
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• v.17 no.2
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• pp.213-222
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• 2001

Cylindrical type ceramic filers, that is 60 O.D$\times$10t$\times$600L and 60 O.D$\times$10t$\times$1,000L were manufactured by vacuum forming processes using ceramic ray materials. For cylindrical type ceramic filters, porosity and bulk density were measured for, 80 to 90% and 0.3 to 0.4 g/㎤, respectively at uniform pore size of 41 to 45${\mu}{\textrm}{m}$. Bench scale candle filters (60$\psi$ $\times$10t$\times$600L) were tested using different dusts collected from many industries including chemical processing, glass processing and metal manufacturing pants. Collection efficiencies found out to range from 99.87% to 99.90%, while resistance coefficients from 1.1$\times$10(sup)11/$m^2$ to 1.7$\times$10(sup)11/$m^2$ . Full scale low density ceramic filters (60$\psi$ $\times$10t$\times$1,000L) were also tested at 1 atm, $600^{\circ}C$ to reveal the filtration efficiency, conditioning, and resistance coefficients using two different types of dust as chemical processing and metal refined processing. Darcys law resistance coefficients were measured to range 1.44$\times$10(sup)11/$m^2$ to 2.74$\times$10(sup)11/$m^2$, and collection efficiencies on the range 99.84 to 99.96%, Finally, results of long term performance test showed that filters were conditioned after 170hrs. Experimental conditions for effective filtration were examined under the condition 10 cm/sec face velocity, 3kg/$\textrm{cm}^2$ pulsing pressure, 5 min filtration cycle, and 300msec pulse opening time.

• Journal of Korean Neurosurgical Society
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• v.29 no.5
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• pp.659-663
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• 2000

The motality rate of acute subdural hematoma(ASDH) associated with closed head injury is high in spite of recent advances in neurosurgery. Many variables in regard to outcome of ASDH have been assessed. But among them, intracranial pressure(ICP) control and the time interval between injury and operative evacuation are the only things that can be affected by doctor. We introduced a simple method to the management of ASDH for reducing the time interval between injury and operation. When the immediate decompressive operation of ASDH was impossible by any causes, we made a burr hole at the center of hematoma, usually on 2-3cm above temporal squama and 1-2cm behind coronal suture under local anesthesia before main operation. Partial hematoma evacuation was achieved through the burr hole and it was effective in preventing further worsening of patients neurological status before main operation. Prompt hematoma evacuation through the burr hole seemed to be effective in delaying secondary ischemic brain damage and made easy to closing the dura opening and replacement of the bone flap at the end of main decompressive operation. This easy method may reduce the time interval between injury and operation. We represent surgical technique with two cases of ASDH managed with this simple method.

• Tunnel and Underground Space
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• v.28 no.4
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• pp.372-386
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• 2018

The air quality near the backfilled site area is significantly deteriorated during and even after the curing period of the backfill materials. Hazardous gases such as NH3 and CO2 may leak out prolongedly from the mined-out sites backfilled with the composite carbonate-based material; leakage can be observed at the underground working sites as well as on the surface. At operating mines, underground gas leakage will severely aggravate the workplace environment. The ventilation schemes should supply sufficient air to dilute the contaminated air, and control the toxic gas leakage and dispersion. This study shows the applicability of pressurization ventilation system to control gas leakage and dispersion at the backfilled underground mine site.

• The Korean Journal of Malacology
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• v.28 no.3
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• pp.277-291
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• 2012

Aquaculture is challenged by a number of constraints with future efforts towards sustainable production. Global climate change has a potential damage to the sustainability by changing environmental surroundings unfavorably. The damaging parameters identified are water temperature, sea level, surface physical energy, precipitation, solar radiation, ocean acidification, and so on. Of them, temperature, mostly temperature elevation, occupies significant concern among marine ecologists and aquaculturists. Ocean acidification particularly draws shellfish aquaculturists' attention as it alters the marine chemistry, shifting the equilibrium towards more dissolved CO2 and hydrogen ions ($H^+$) and thus influencing signaling pathways on shell formation, immune system, and other biological processes. Temperature elevation by climate change is of double-sidedness: it can be an opportunistic parameter besides being a generally known damaging parameter in aquaculture. It can provide better environments for faster and longer growth for aquaculture species. It is also somehow advantageous for alleviation of aquaculture expansion pressure in a given location by opening a gate for new species and aquaculture zone expansion northward in the northern hemisphere, otherwise unavailable due to temperature limit. But in the science of climate change, the ways of influence on aquaculture are complex and ambiguous, and hence are still hard to identify and quantify. At the same time considerable parts of our knowledge on climate change effects on aquaculture are from the estimates from data of fisheries and agriculture. The consequences may be different from what they really are, particularly in the temperature region. In reality, bivalves and tunicates hung or caged in the longline system are often exposed to temperatures higher than those they encounter in nature, locally driving the farmed shellfish into an upper tolerable temperature extreme. We review recent climate change and following environment changes which can be factors or potential factors affecting shellfish aquaculture production in the temperate region.

• Korean Journal of Organic Agriculture
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• v.27 no.3
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• pp.271-288
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• 2019

It has continuously promoted to scale up the agricultural management body in order to cope with the market-opening pressure such as the UR negotiation, the DDA negotiation, and more conclusions of FTAs and to enhance the competitiveness of our agriculture. This study evaluated the factors associated with production organization participation centered on environmentally-friendly agriculture farmers in order to improve the production efficiency of environmentally-friendly agriculture in the aspect of production. In order to achieve this objective, this study evaluated the factors that contributed to participating in an organization using the bivariate probit model focusing on environmentally-friendly agriculture farmers in Chungnam. This study examined the validity and reliability of the study model through exploratory factor analysis. The results of factor analyses identified four factors: "distribution", "production", "organization operation", and "social capital". The results of the bivariate probit model showed that distribution significantly affected production activities and distribution, organization operation, agricultural income, and gender significantly influenced sale activities. Environmentally-friendly production organization had not been able to provide the productive support that was needed for local farmers to produce environmentally-friendly agricultural products in a region. Additionally, farming education did not provide the information needed by the farmers. Although producers had a network within a production organization, it was operated mainly for administrators. Therefore, participants felt somewhat lacking. This study identified the level of organization of producer organizations in Chungnam area, where environmentally-friendly agriculture is well activated. This study suggested implications for future production organization participation by evaluating factors affecting participation quantitatively.

• Fire Science and Engineering
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• v.22 no.4
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• pp.20-26
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• 2008

The performance of natural smoke ventilators in High-rise buildings was analyzed by investigating the stack effect depending on the wind velocities using CONTAMW tool. The results showed that the opening of smoke ventilators can influence on the stack effect in the building thus moving the position of the neutral plane toward the opened smoke ventilators. The outside wind velocities can move up the neutral plane toward the top of the building thus increasing pressure differentials at the bottom of the building. The smoke ventilators can maintain its normal performance without outside wind, however, strong outside wind can prevent natural smoke exhaust due to the infiltration of outside air at the ventilators.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.6
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• pp.70-77
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• 2011

A ventilation-relief valve performs as a safety-valve assembly for the liquid-propellant feeding system of space launch vehicle. This valve plays a role of relieving the vaporized propellants from propellant tanks during the filling and storing stages of propellants. Also it regulates to maintain the pressure of ullage volume of on-board propellant tanks within the safety-margin during the flight. The simulation model of ventilation-relief valve is designed with AMESim to predict and evaluate the dynamic characteristics and pneumatic behaviors of valve. To validate a valve simulation model, the simulation results of the opening and closing pressures and their operating durations of valve by AMESim analysis are compared with the results of mathematical methods. In addition, the results of internal flow simulation with FLUENT are utilized to improve the accuracy of valve-modeling. This study will serve as one of reference guides to enhance the developmental efficiency of ventilation-relief valves with the various operating conditionss, which shall be used in Korea Space Launch Vehicle-II.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.6
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• pp.1-6
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• 2011

An experimental study has been conducted to scrutinize into the influence of ultrasonic standing wave field on the variation of methane/air premixed flame structure. Visualization technique utilizing the Schlieren method is employed for the observation of premixed flame propagation. The shape of flame front and local flame velocity are measured according to the variation of reactants pressure and chamber opening/closing condition. The flame fronts affected by the standing wave are clearly distorted but the vertical locations of frontal dents do not undergo any appreciable change. The influence of standing wave on the flame front becomes more prominent as the flame propagates downward. It is found that the propagation velocity of flame front with excitation of standing wave is greater than the case without the excitation. It is eventually revealed that the flame is deformed to lotus-shaped one by the vivid interaction of ultrasonic standing-wave with the reflected wave coming from the right side.

• YAKHAK HOEJI
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• v.41 no.2
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• pp.241-246
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• 1997

The effect of potassium channel openers, SKP-450, SKP-818 and lemakalim have been compared in rat heart and aorta. In rat isolated heart, SKP-450 had a greater negative inotrop ic effect than lemakalim and KR-30818 against left ventricular developed pressure (LVDP) and double product of heart rate and LVDP (DP). In addition, SKP-450 had a greater effect than lemakalim and KR-30818 in increasing coronary flow, indicating a more potent vasodilating effect in coronary artery. Negative inotropic effect and coronary vasodilating effect of SKP-450 and SEP-818 were significantly reduced by 10 min-perfusion with $10^{-6}M$ glyburide, a selective blocker of ATP-sensitive potassium channel. In rat aorta, SKP-30450 and SKP-30818 as well as lemakalim induced powerful concentration-dependent relaxations against norepinephrinc-induced tone ($EC_{50},\;{\mu}M$ : SKP-30450, $0.107{\pm}0.009$; SKP-30818, $0.476{\pm}0.022$ ; lemakalim, $0.565{\pm}0.039$ ). These relaxant effects were significantly reduced by pretreatment with glyburide. In sununary, SKP-30450 and SKP-30818 showed greater negative inotropic and vasorelaxant effect than lemakalim in rat aorta with order of potency of SKP-30450 > SKP-30818 > lemakalim. These actions are suggested to be mediated at least in part by a mechanism which involves the opening of ATP-sensitive potassium channel.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.974-981
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• 2007

Seoul Metro has operated the air cooling equipment established in a machine room of a station building to improve our services focused on our customers who use Seoul Metro during the summer season. However, a new set of problems has arisen with the cooling tower to support a heat exchange of cooling water. One of them is loss of efficiency in the air conditioner. The leading cause of this problem is that we use an underground type of the cooling tower. As the machine room of a station building is located in the underground of inner city because of the nature of the subway, it is difficult to establish the cooling tower on the ground. The underground structure of the No. $1{\sim}4$ subway line is unsuitable for the location requirements of the underground type of the one because it has a limited space to set up the air cooling equipment, for example, the cooling tower and a ventilating opening. As a result of such an unfavorable condition, the cooling tower doesn't work efficiently and the warmth of cooling water because of insufficiency of a heat exchange and a refrigerator's technical obstacle such as a high-temperature and a high-pressure has arisen. Accordingly, the efficiency of the air conditioning is getting lower and lower. Another problem is too wasteful with water. Each station uses the water over 30 tons every day with waterworks to replenish the cooling tower such as a evaporation, a scattering and a distribution of water. Nevertheless, the more an air conditioner increase, the more the use of water supply increase. For this reason, we can't help wasting an enormous amount of water and discharging the congelation of a low temperature(about $15^{\circ}C$) occurred in a heat exchanger inside an air conditioner. The purpose of this study is to analyze the utility of congealing water to improve efficiency of the air cooling equipment and save energy as a supplementary water for the cooling tower.