• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.6
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• pp.120-131
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• 2019

Recently, the level of fine dust and ultrafine dust has reached its highest level, threatening the public's health. If the air purifier was not operated indoors, natural ventilation would not be possible. In this study, photocatalyst is applied to building materials to purify air in a passive manner. In order to use photocatalyst for LEFC(Light Emotion Friendly Concrete), it is necessary to secure self-consolidating capability. Therefore, self-consolidating performance was evaluated by slump test, J-ring test and L-box test with UHPC materials applied. Based on these results, the mixture proportion was determined, and the mechanical performance was evaluated by compressive and flexural tests. Concrete blocks were constructed with a fabrication method that improved the existing process of making LEFC. Also, the concrete block was emptied as a way to reduce the use of expensive photocatalyst. Finally, in order to identify the distribution of TiO₂, an EDS analysis was performed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.725-730
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• 2011

A 2-way solenoid valve regulates to maintain the pressure of ullage volume of propellant tanks when the command is given by control system for the liquid-propellant feeding system of space launch vehicle. The simulation model of solenoid valve for pressurization is designed with AMESim to verify the designs and evaluate the dynamic characteristics and pneumatic behaviors of valve. To validate a valve simulation model, the simulation results of their operating durations of valve by AMESim analysis are compared with the results of experiments. Using the model, we analyze performance of valve; opening/closing pressure, operating time on various design factors; shape of control valve seat, basic valve seat, rate of sealing diameter. This study will serve as one of reference guides to enhance the developmental efficiency of ventilation-relief valves with the various operating conditions, which shall be used in Korea Space Launch Vehicle-II.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.4
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• pp.321-327
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• 2007

In an apartment house that is generally air-tight and well insulated, the combustion gas from cooking devices is the major source of air pollution in the kitchen. It spreads throughout the house affecting the overall Indoor all quality. In this study, the performance of the kitchen range hood which employs air induction and air curtain was investigated by numerical simulation. The results are compared with that of two other kitchen range hoods which are in general use. The two general types of range hoods considered in the present calculations are box and plate type range hoods. The former has a large capture space between the filter and suction duct, while the latter has little. It was found that the capture efficiency of the kitchen range hood with air induction and air curtain Is higher than that of the general types of range hoods by 20% approximately The reason may be because the air induction and the air curtain block the air stream escaping from the front and the side part of range hoods effectively and because an additional fan for air induction and air curtain increases suction flow rates.

• KIEAE Journal
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• v.13 no.5
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• pp.43-50
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• 2013

Recent researches on plant factory system deal with the convergence of lighting technology, agricultural technology inclusive to the high-tech industries worldwide in order to respond to the decreasing crop harvest due to global warming and abnormal weather phenomena. However, the fundamental performance standard is not currently being introduced in the case of plants factory and its commercialization is not activated because of high initial investment and operating cost. Large portion of the initial investment and operating cost of a plant factory is ascribed to artificial light sources and thermal control facilities, therefore, innovation should be provided in order to improve the economics of the plant factory. As an alternative, new plant factory could harness solar thermal and geothermal systems for heating, cooling and ventilation. In this study, a natural light dependent multi-layer plant factory's thermal environment was analyzed with two-dimensional numerical methods to elicit efficient operation conditions for optimized internal physical environment. Depending on the supply air temperature and airflow rate introduced in the facility, the temperature changes around the crops was interpreted. Since the air supplied into the plant factory does not stay long enough, the ambient temperature predicted around the plating trays was not significantly different from that of the supplied air. However, the changes of airflow rate and air flow pattern could cause difference to the temperature around the planting trays. Increasing the amount of time of air staying around the planting trays could improve energy performance in case the thermal environment of a natural light based multi-layer plant factory is considered.

• Journal of the Society of Disaster Information
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• v.12 no.2
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• pp.144-149
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• 2016

Nowaday, most of the low-rise concrete structures which have less than five stories were built before the intensified seismic code was established 2005. According to the fact that our country is not a safety zone ay more, studies are need to reinforce the seismic performance of that structures. The basic frame of low-rise structure are consist of beams and columns with partition walls, therefore that are very weak about secondary wave of earthquake because of the high stiffness. The partition wall are consist of open channel for sunlight or ventilation and intermediate wall. The intermediate walls will enhance the stiffness of columns, but will cause shear failure with short column effects because of the reduced effective depth. But we don't have studies and adequate design code for partition wall effects, therefore some more studies are need for these facts.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.4
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• pp.436-441
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• 2009

An air filter is a device to remove dust from the air supplied to the automotive engine. A requirement for the optimum air filter is to improve the capability to remove particles from the air it takes in, that is the efficiency and amount of dust collection. By removing dust from the air, the air filter prevents the engine cylinder from wear, reduces ventilation resistance, and thus improves engine output and guarantees intake performance. In order to guarantee such air filter performance, it is very important to properly seal the air filter. For passenger cars made in Korea, the air filters are fabricated with steel caps as their frames are large and their engine capacity is big. Recently however, European countries and Japan started using urethane for manufacturing the air filter, so that all foreign-made cars now have urethane filters. The urethanes used for air filters are applied in two ways: One is to use soft urethane for both top and bottom of the air filter and the other is to use soft urethane for the top and hard urethane for the bottom. Each of these method has unique problems. In this study, hard urethane is used for both top and bottom of the filter in order to improve those problems and increase the sealing efficiency. Especially for the top, NBR (rubber mold) is pre-settled in tough urethane and then the urethane is solidified through foaming, which makes it possible to develop a solid and double-sealed filter.

• Korean Journal of Community Nutrition
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• v.12 no.3
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• pp.310-321
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• 2007

Effective and systematic sanitation management programs are necessary to prevent foodborne disease outbreaks in school foodservice operations. The purpose of this study was to identify the elements to improve in order to ensure the safety of school food service by evaluating sanitation management practices implemented under HACCP-based programs. The survey was designed to assess the level of hygiene practices of school food service by using an inspection checklist of food hygiene and safety. Fifty-four school foodservice establishments considered as poor sanitation practice groups from two year inspections by Seoul Metropolitan Office of Education were surveyed from September to December in 2005. Inspection checklists consisted of seven categories with 50 checkpoints; facilities and equipment management, personal hygiene, ingredient control, process control, environmental sanitation management, HACCP system and safety management. Surveyed schools scored $68.0{\pm}12.42$ points out of 100 on average. The average score (% of compliance) of each field was 10.7/20 (53.3%) for facilities and equipment management, 7.4/11 (67.2%) for personal hygiene, 7.4/11 (74.1%) for ingredient control, 22.4/32 (69.8%) for process control, 8.9/12 (73.8%) for environmental sanitation management, 4.2/7 (59.7%) for HACCP systems management, and 7.2/8 (89.7%) for safety management, respectively. The field to be improved first was the sanitation control of facilities and equipment. The elements to improve this category were unprofessional consultation for kitchen layout, improper compartment of the kitchen area, lacks of pest control, inadequate water supply, poor ventilation system, and insufficient hand-washing facilities. To elevate the overall performance level of sanitation management, prerequisite programs prior to HACCP plan implementation should be stressed on the school officials, specifically principals, for the integration of the system.

• Journal of the Korean housing association
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• v.17 no.2
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• pp.125-134
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• 2006

The tightness of windows have devoted to the improvement of thermal insulation and energy saving in buildings. But it is known that this tightness causes some side effects such as low ventilation, low capacity to humidity and temperature control and these are not profitable for inhabitants. To act on these side effects, Korean traditional windows which are composed of Han-Ji(Koreand traditional paper) and Chang-Sal(Korean traditional wooden frame) have been studied to get a reasonable solutions for these problems. In this study, to compare the thermal and humidity control performance of current window(12 mm pair) and Korean traditional windows, frames which are made of existing window and Korean traditional windows are adapted to scale model house and then humidity and temperature of in and out of scale model house are measured and analysed. The results of this study are followings ; 1) When Korean traditional window charges 20cm(1/8 of total window area) from total window area, Han-Ji window has higher thermal insulation than that of existing window in daytime. There is the most big thermal difference when double faced with double-ply Han-Ji window is placed to mock-up house. In night-time, the temperature difference is very small so this means that Korean traditional window is good to cover direct sunlight in daytime and reduce the temperature of balcony. One faced with one-ply han-Ji window has the best humidity penetration performance among three type of Korean traditional windows. 2) When Korean window area enlarged to 40cm(1/4 of total window area), the function of 40cm width Han-Ji window is higher than that of 20cm's. This means that enlargement of Han-Ji window cover direct sunlight more and is more efficient in humidity penetration.

• Journal of the Korean Solar Energy Society
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• v.27 no.2
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• pp.111-119
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• 2007

The annual mean temperature of South Korea has risen by $1.3^{\circ}C$ for last 100 years by urbanization and industrialization. Especially, the frequency of unusual hot weather in summer increases for a long time and the frequency of unusual cold weather in winter clearly decreases. In recently, The considerable portion of curtain wall system is appled to building skin in domestic. As related to this, the Korea Institute of Construction Technology devised the box typed double skin facade(It is occasionally called as FDFS : Functional Double Facade System) as an alternative that reflects the distinctive local climate and saves cooling energy. Two mock-ups($49m^*4.9m$) applied to single skin(curtain wall) and double skin each were monitored under the outdoor condition. Therefore, the characteristics of natural ventilation and cooling energy consumption of each window had been analyzed in real time. The results of this study are summarized as follow, Analysis of the experiment on an air conditioner: the indoor temperature of the chamber with FDFS is lower than that of the chamber with single skin facades by $3{\sim}6$ degrees(C). A temperature variation of about $1{\sim}2$ degrees between the 0.2m and 1.7m height of the mock-up occurs in FDFS, while that of about maximum 7 degrees occurs in single skin facade at noon with abundant intensity of solar accident. Also, 67 percent of energy consumption for air conditioning has been saved.

• Journal of ILASS-Korea
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• v.25 no.4
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• pp.162-169
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• 2020

The worldwide focus on reducing the emissions, fuel and lubricant consumption in T-GDI engines is leading engineers to consider the crankcase ventilation and oil mist separation system as an important means of control. In today's passenger cars, the oil mist separation systems mainly use the inertia effect (e.g. labyrinth, cyclone etc.). Therefore, this study has investigated high efficiency cylinder head-integrated oil-mist separator by using a compact multi-impactor type oil mist separator system to ensure adequate oil mist separation performance. For this purpose, engine dynamometer testing with oil particle efficiency measurement equipment and 3D two-phase flow simulation have been performed for various engine operating conditions. Tests with an actual engine on a dynamometer showed oil aerosol particle size distributions varied depending on operating conditions. For instance, high rpm and load increases bot only blow-by gases but the amount of small size oil droplets. Submicron-sized particles (less than 0.5 ㎛) were also observed. It is also found that the impactor type separator is able to separate nearly no droplets of diameter lower than 3 ㎛. CFD results showed that the complex aerodynamics processes that lead to strong impingement and break-up can strip out large droplets and generate more small size droplets.