• Korean Journal of Veterinary Service
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• v.38 no.3
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• pp.195-198
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• 2015

Mannheimia haemolytica is an opportunistic bacterium that is widely recognized among the bovine respiratory disease (BRD) complex in cattle. Five Hanwoo with a history of fever, anorexia and dyspnea were died within 2 days in a the middle of summer. Four cattle were pregnant. The cattle house were located in mountainous area but the window for air ventilation was open only one side. In addition, the fecal material for fermentation was located indoor. Air ceiling fan did not work. The indoor temperature was $40^{\circ}C$. After working on air fan, the indoor temperature was still $36^{\circ}C$. On necropsy, there was fibrinous pleuritis with a rich yellowish pleural fluids in the thorax. The cross-section of the lung showed lobar fibrinonecrotic pneumonia with expanded interlobular septa by edema and fibrin. Microscopically, parenchymal necrosis with dense layer of inflammatory cells were observed surrounding interlobular septum. Fibrin and inflammatory cells were filled in the alveoli. Bacteriological cultures of pulmonary tissue showed growth of M. haemolytica. This pneumonia case in Hanwoo suggests that environmental stressors such as high temperature, insufficient air ventilation, and pregnancy be the cause of mannheimoisis. Control of environmental stressor, such as temperature indoor is necessary to prevent BRD caused by M. haemolytica.

• Transactions of the KSME C: Technology and Education
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• v.1 no.1
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• pp.129-138
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• 2013

Constant airflow should be kept in order to operate a constant-fired boiler of thermal power plants. Main Bearing Assembly Unit which rotates the ventilation fan does very important role to maintain constant airflow. However, the demand to the output of power is getting increased while the quality level of coal is getting worse than the initial level of design criteria. Especially cost wise operation considering increasing output and the difficulty to supply good quality coal drive increasing supply of low quality coal. As a result, the service life of Main Bearing Assembly is getting shorter till 2~3 years which is just a half of the life of original design. In this study, what causes to shorten the service life of Main Bearing Assembly Unit is analyzed through the reverse engineering and analysis and how to improve the service life more than two times to current situation is explained.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.34-40
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• 2016

In ventilated seats for cars, air flow is generated by a fan and passed through a foam pad, foam filter, and seat cover. There is a significant loss of air flow in this process, and it is not easy to analyze the amount delivered to the driver. Another difficulty is the geometric complexity of the air flow passage inside the seats. In this paper, the air flow through a foam pad was analyzed. Proper modeling of the bumps in the ventilation mat was found to be important in the analysis. Air flow is lost when it passes through the porous pad foam, which was measured and used to correct the analysis results. The corrected analysis results were in a good agreement with the experimental results. The amount of air flow delivered to a driver was measured using an airflow cone. Only 35.7% of the air flow from the fan was delivered.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.1
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• pp.131-139
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• 2018

Many ship researches have been carried out in connection with the fourth revolution, one of which focuses on EMS(energy management system). The EMS is referred to as systems for managing the energy of ships and include various systems. In this paper, we analyze the energy saving field in ship and propose a ship power energy management system including individual load control systems that can save energy in the engine room. EMS includes individual load control systems of PCS (Pump Control System), ERFCS (Engine Room Fan Control System), LCS (Load Control System), HVACS (Heating, Ventilation, Air conditioning Control System). Proposed EMS primarily conserves energy in the individual load systems of the engine room. Secondly, the integrated monitoring and control system is used to control the power generation system and the power load system to save energy.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.6
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• pp.77-86
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• 2022

Various odor reduction systems are being operated at pig houses to improve livestock odor issues. However, the quantitative evaluation of odor reduction efficiency is not sufficiently conducted. The analysis of factors that affect the reduction efficiency also has not been sufficiently conducted. Therefore, in this study, the reduction efficiency of representative odor reduction facilities (bio-curtain, scrubber) operated by domestic pig houses was evaluated. The odor reduction efficiency was evaluated by sampling the air before and after the odor reduction facility in 6 pig houses. Livestock odors were evaluated for complex odors, ammonia, hydrogen sulfide, and VOC. To find factors for reduction efficiency, temperature, humidity, pH of washing resolution, type of washing water, and ventilation rate was measured. As a result, it was found that the scrubber system had the highest reduction efficiency. The reduction efficiency was found to be affected by the scrubber's washing resolution, filler, operating conditions, and size. Bio-curtains may have problems such as deterioration of fan performance due to ventilation fan load, groundwater pollution, and excessive use of groundwater.

• Journal of Bio-Environment Control
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• v.20 no.3
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• pp.176-181
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• 2011

The fan and pad evaporative cooling system is one of the main cooling methods in greenhouses. Its efficiency is very high, but it has some disadvantages as temperature gradient in greenhouse is large. This study was conducted to reduce the internal temperature gradients in the fan and pad cooling greenhouses. Experiments on cooling performance were carried out in a greenhouse equipped with air duct and integrated fan and pad system as an idea of this study. It showed that the cooling efficiency of an integrated fan and pad system was 75.7% in the first stage and 88.6% in the second stage. When this cooling system was operated for an unshaded and a shaded greenhouse, there were cooling effects of $5.7\sim7.6^{\circ}C$ and $7.4\sim9.7^{\circ}C$ to the control greenhouse, respectively. Maximum temperature differences in a cooling greenhouse, with a length of 18m, were $1.6\sim1.7^{\circ}C$ for shaded conditions and $2.3\sim2.7^{\circ}C$ for unshaded conditions. This greenhouse cooling method, with air duct and integrated fan and pad system, can reduce about 40~50% of the internal temperature gradients in the usual fan and pad cooling greenhouses.

• Fire Science and Engineering
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• v.19 no.1 s.57
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• pp.80-86
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• 2005

In this study effects of the natural wind and the forced smoke ejection by operating the exhaust fan are studied numerically to examine the flow characteristics of the smoke and heat generated from a fire on the platform of an underground subway station. Three different situations, including 1) the case with no natural wind and no exhaust fan operation, 2) the case with natural wind but no exhaust fan operation and 3) the case with no natural wind but exhaust fan operation, are considered for the numerical analyses. The numerical results show that the natural wind causes a rapid spread of the fire along the tunnel resulting in rapid spread of the smoke and heat over the platform which affects the escape. The operation of the exhaust fan also results in the rapid spread of smoke and heat over the platform, but the time required for reaching the safe escaping height of the smoke layer with the exhaust fan operation is much longer than that without the exhaust fan operation. The numerical results also show that the required capacity of the exhaust fan becomes larger when the effect of the natural wind is included.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.6
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• pp.695-701
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• 1998

Researches on unused energy are being continued because of the limited fossil fuel and the destruction of environment. Therefore this study was peformed as follows. The collectable amount of exhausted heat for an air-conditioning was calculated by the subway thermal environment prediction program. And the electric power needed by conventional heat source equipments was compared with one by unused heat source equipments when the exhausted heat was used by heat pump in heating and hot water supplying. The results are summarized as follows; 1) Forced ventilation should be conducted to keep optimal temperature in subway tunnel in summer as well as in winter. According to the simulation, temperature in tunnel was higher than that on the ground in summer when the forced ventilation was conducted only in winter. 2) Ventilating time should be calculated out to the optimal condition for not only saving power of ventilation fan but reusing exhausted heat. By the simulation, it is certain that the exhausted heat should be eliminated in air-conditioning time. 3) The use of exhausted heat source heat pump could save 8% of electric power per hour in comparison with existing heat pump. It was based on a present heat generation and traffic for ventilating time of general air-conditioning, but could be different by ventilating time. 4) As the traffic increases up to 1.5 or 2 times, electric power consumption of the conventional heat pump increases to 11% or 13.5% per mean hour in comparison with that of the exhausted heat source heat pump, though all-day ventilation.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.6
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• pp.588-597
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• 2012

In the present study, the dispersion characteristics of hydrogen leakage from a Fuel Cell Vehicle (FCV) were analyzed by numerical simulation in order to assess the risk of a hydrogen leakage incident in a long road tunnel. In order to implement the worst case of hydrogen leakage, the FCV was located at the center of a tunnel, and hydrogen was completely discharged within 63 seconds. The Leakage velocity of hydrogen was adopted sub-sonic speed because that the assumption of the blockage effect of secondary device inside a vehicle. The temporal and spatial evaluation of the hydrogen concentration as well as the flammable region in a road tunnel was reported according to change of ventilation operating conditions. The hydrogen was blended by supply air form a ventilation fan, however, the hydrogen was discharged to outside in the exhaust air. It is observed that the efficiency way to eliminate of hydrogen is supply air operating condition under the hazardous hydrogen leaking incident. The present numerical analysis can be provided useful information of ventilation under the hydrogen leaking situation.

• Journal of the Korean Society of Safety
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• v.10 no.3
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• pp.96-105
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• 1995

The better industry develops, the more spaces need but in the limited area. Most building become larger and more complicated if the more spaces need in the constant area. And this leads to do underground work in long period generally six(6) months for 6 basement stories due to the selection of TOP DOWN technique. Working environment in this underground area can be problems and should not be overlooked, because air quality in underground spaces become quickly worse. Recently, department name to control construction safety has been changed to ENVIRONMENT & SAFETY TEAM from SAFETY TEAM. This means that it is very important to control against environmental condition at site so much. Overall construction work as well as underground work should conform to the requirement of working environment, particularly against inhabitants around the construction area. Strut protection, one of earth protection method, in case to 40m long strut may become weaker due to thermal stress or its longitudinally compressive strain and the another one, earth anchor protection may not be applied to the site In case of encroaching on vertical underground borderline because of regulation to prohibit it. It is necessary that TOP DOWN technique should be introduced in order to solve the external and internal problem of the site such as difficulty level of the work, potential danger with excavating depth, and shortening workperiod. It is needed that improving way of working condition should be shown and simplified computer simulation program should be also provided for checking pollution level & ventilation, excluding of lighting problem here. Results measured with conformance to the Regulation for Working Environment Measurement, enforced by Ministry of Labor have been applied to the computer program developed here. Sample air taken at unit workplace which was considered as exposing condition of pollutant at breathing point and within a range of behavior of the workers, Identified exposing group in underground work, using Moded Flow Life Finally, three types of ventilation system, type I with blower & ventilator, type II natural supply with mechanical ventilation system, and type I mechanical ventilation with Drivent Fan Unit System are selected for this study.