• Aerospace Engineering and Technology
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• v.11 no.1
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• pp.68-77
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• 2012

Flow characteristics of base region of small scaled 4 nozzle clustered engine has been analyzed with CFD approach along with the tests of numerical methods. The numerical test shows that Spalart-Allmaras turbulence model is appropriate for the present research. Plumes expanded from nozzles exits collide with each other and make high pressure stagnation region. Some of collided plumes expand again reversely into the base region with supersonic speeds. The reversed plume in the base region goes out to the outer region through the minimum vent area formed by the nearest nozzle exterior surfaces. But different from the empirical theory, the minimum vent area does not play a role of throat. Additionally the temperature of the nozzle inner surface strongly affects the temperature of the reversed plumes.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.808-812
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• 2008

Recently, the buildings have been likely to shape Super Tall trend. Therefore, the exterior parts of the buildings come to be changed. Instead of early heavy wall structure, it is changed to light wall concept of curtain wall system. However, the curtain wall system causes lots of loads due to the external surrounding factors of building. In particular, due to the densely built-up condition in Korea, the generation of dew condensation is getting severer Since there has been no standardized process that reviews this generation of dew condensation, it is very urgent for us to prepare the reviewing process for the dew condensation for construction business managers. The purpose of this study is to assess dew condensation function of the curtain wall and provide the basic data for the provision of the future dew condensation review process by comparing and analyzing the range of generation of dew condensation as well as temperature distribution according to the change of relative humidity at the identical temperature by selecting the Unitized system and Stick system which are the representative types of curtain wall system.

• KIEAE Journal
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• v.16 no.4
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• pp.71-77
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• 2016

Purpose : The energy saving in a residential building (apartment) sector is known as one of the effective solution of energy reduction. In South Korea, the government has recently reinforced regulations associated with the energy performance of buildings. However, there is a lack of research on the methods for the energy performance diagnosis that is used to analyze the wall thermal performance of the existing apartments. Because a reliable diagnosis is necessary to save the building energy, this study analyzed wall thermal performance of an existing apartment in Seoul. Method : This paper applied two methods for analysis of the thermal insulation performance; HFM(Heat Flow Meter) method and ASTR(Air-Surface Temperature Ratio) method. The HFM method is suggested by ISO9869-1 code to measure the thermal performance. The ASTR method is proposed by this study for the simplified In-situ measurement and it uses three temperature data (interior wall surface, interior and exterior air) and the overall heat transfer coefficient. This study conducted the experiment of an existing apartment in Seoul using these methods and analyzed the results. Furthermore, the energy simulation tool of the building was used to suggest retrofit of the building based on the results of measurements. Result : The error rate of HFM method and ASTR method was analyzed in about 17 to 20%. As the results of comparison between the initial design values of the wall and the measured values, the 26% degradation of insulation thermal performance was measured. Lastly, the energy simulation tool of the building shows 10.8% energy savings in accordance with the construction of suggested retrofit.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3800-3805
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• 2012

Infrared(IR) reflective black cool pigment and paint which is used for interior/exterior materials(IR reflectance >30%) to prevent heat island effect and to increase energy efficiency were studied. Cool pigment was synthesized using mixture of $Fe_2O_3$ and $Cr_2O_3$ with calcination from 900 to $1,200^{\circ}C$. Cool paint was prepared by formulation of cool pigment, acrylic resins, and other additives. Results showed that optimum color fixation of pigment obtained by mole ratio of Fe to Cr was 0.9 with calcination temperature at $1,000^{\circ}C$. The cool paint formulated by 20% pigment and 1.5% dispersive additive with $125{\mu}m$ thickness of coated layer showed optimum IR reflectance. Temperature difference on surface between cool paint and ordinary paint(STD) was $36.5^{\circ}C$ and IR reflectance(TSR) was 39.3% at wavelength from 700 to 2,500nm. And color change was not detected during 500hrs weathering test.

• Journal of the FoodService Safety
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• v.2 no.2
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• pp.59-66
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• 2021

The results of the inspection based on the sanitation checklist and the measurement of refrigerator/freezer temperature, illuminance, and ATP were conducted at 12 school foodservices in Daiyue-district, Taian-city, Shandong Province, China, at the same time, and the results were as follows. Five items of 'Use sterilized cutting boards', 'Use sterilized knives', 'Use worktable after sterilization', 'Use sink after sterilization', 'Sterilize the interior/exterior of the refrigerator regularly' in the checklist inspection were found not to be performed (0%). Two items of 'Disinfect hands after washing', 'Equipped with hand sterilizer' and 'Sterilize the kitchen areas regularly' were investigated as being performed only in one foodservice (8%). The average illuminance of the receiving stand were 373.08±106.35 Lux, 8% when the standard (540 Lux or higher) was complied with, the average refrigerator temperature were 7.06±0.82℃, 38.9% when the standard (-2 to 5℃) was observed 8% of cases complying with the standard (below -18℃) at -8.56±0.76℃ were investigated. As a result of ATP measurement, the surfaces of knife edge, cutting board, refrigerator door handle, worktable, and sink, which are not sterilized at all, were not suitable (accept ratio 0%), sterilized food plate (accept ratio 54.2%) and utensil for preserved food (accept ratio 75%) had a relatively high accept ratio. China's hygiene regulations should be revised in the direction of strengthening disinfection practices for facilities, equipment, and the environment, and hygiene measures such as education on disinfection and preparation of economical disinfection methods should be established.

• Journal of the Korea Institute of Building Construction
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• v.12 no.4
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• pp.442-450
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• 2012

In this study, fire resistance and residual strength were examined after the addition of PF fiber and bonding fireproofing gypsum board to a high strength concrete-model column of 50 MPa grade. At the beginning of the experiment, all the properties of base concrete appeared to satisfy the target range. In terms of the internal temperature record, a trend of slightly high temperature was shown when the fireproofing gypsum board was not bonding, and when the fireproofing gypsum board was bonding, as PF content increased gradually, the temperature was gradually lowered. In terms of the relationship, as time elapsed a low temperature was shown when fiber was mixed, and when the board was bonding, the trend of lower temperature could be confirmed. Meanwhile, in terms of spalling property, a severe explosive fracture was generated at PF 0%, and falling off was prevented as the fiber content was increased; however, discoloration and a multitude of cracks were discovered, and when the board was bonding, the trend in which the exterior became satisfactory when the content was increased emerged. In terms of the residual compressive strength, measuring of strength could not be performed at PF 0% without bonding of board, and the strength was increased as the fiber content was increased; however, there was a decrease in strength of about 30 ~ 40%, and in the case of PF 0% with the bonding of board, the strength could be measured; however, about an 80% decrease in strength was shown, and only about a 10 ~ 20% decline in strength was displayed, as the range of decrease was reduced as the fiber content was increased. Considering all of these factors, it was determined that a more efficient enhancement of fire resistance was obtained when two methods are applied in combination rather than when the PF fiber content and bonding of fireproofing gypsum board are utilized individually.

• Journal of the Korean Institute of Landscape Architecture
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• v.38 no.5
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• pp.12-20
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• 2010

The purpose of this study is to evaluate human thermal comfort by spatial structure and to explore solutions to improve the thermal environment of a small urban space. The study site was Korea University campus. Thermal conditions were measured to evaluate the quality of the thermal environment in each type of space within the study site. Micrometeorology measurements, analysis of space characteristics for using fish-eye lens photography, and thermal comfort modeling through the use of collected meteorological data, such as temperature and humidity, were performed. Results showed that the level of thermal comfort for humans differs depending on the types of space within the study site. Thermal comfort is better in open spaces than enclosed in the aspect of radiative mean temperature, Predicted Mean Vote(PMV), and Physiologically Equivalent Temperature(PET). This fact is probably due to shadows or buildings or trees that may block solar radiation. Thus, it is necessary to consider the spatial arrangements of buildings and trees to enhance openness and ventilation in the space. Paving materials and exterior building materials should also be selected to lower the radiant temperature. Given these results, a quantitative evaluation on human thermal comfort could propose a way to plan user comfortable small urban spaces. Study methods used and results provided in the study can promote a better way for urban space planning direction to improve environmental quality.

• Fire Science and Engineering
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• v.26 no.6
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• pp.92-98
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• 2012

In this sturdy, large experimental (ISO 13785-2) was performed to analyze the building materials used in fire retardant materials for aluminum composite panel and in general properties. As a results, maximum temperature in the case of the general materials was measured in 210 seconds $1,021^{\circ}C$, the retardant materials was measured in 1,200 seconds early $1,190^{\circ}C$. The retardant material of aluminum composite panel, Fire behavior if the ignition is slow and the general materials in aluminum composite panel, fire ignition and combustion at the same time was growing rapidly. The general materials and flame-retardant material of aluminum composite panel was an obvious difference to the combustion ignition but after ignition combustion mode showed a similar pattern of the rapidly vertical spread of flame. The results of this study, in order to reduce the risk of aluminum composite panels for fire and the retardant materials used for ignition the slow should be actively encouraging. Also after the ignition, there is an urgent need to put out a fire in exterior materials for extinguishing facilities.

• Journal of Energy Engineering
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• v.21 no.3
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• pp.243-248
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• 2012

In this study, The report analysed the characteristics of power drop and damage of surface in solar cell through high temperature and humidity test. The solar cells were tested during the 1000hr in $85^{\circ}C$ temperature and 85% humidity conditions, that excerpted standard of PV Module(KS C IEC-61215). An analysis of the cell surface through EL(Electroluminescence), the cell has partly change of surface in yearly. Single-crystalline Solar cell efficiency is decreased from 17.7% to 15.6% and decreasing rate is 11.9%. On the other hand, Poly-crystalline Solar cell efficiency is decreased from 15.5% to 14.0% and decreasing rate is 9.3%. A comparison of the fill factor for analysis of electro characteristic in yearly, Single-crystalline Solar cell efficiency is decreased from 78.7% to 78.1% and decreasing rate is 4.7%. On the other hand, Poly-crystalline Solar cell efficiency is decreased from 78.1% to 76.7% and decreasing rate is 1.8%. Single-crystalline has more bigger power drop than poly-crystalline by the silicon purity and silicon atom arrangement. Also, FF decreasing rate has more bigger drop than efficiency decreasing rate for the reason that the damage of surface by exterior environmental factor is the more influence in cell than other reason that is decreasing FF by damage of p-n junction.

• Journal of the Korean Wood Science and Technology
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• v.33 no.6 s.134
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• pp.95-100
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• 2005

The using amount of preservative-treated wood equipments has been increased. Specially, chromate copper arsenate (CCA) has been widely used to exterior wood. We are faced to the disposal problem after service period of CCA treated wood due to its toxic heavy metals. For the disposal of end-used treated wood, land-filling and incinerating methods are mainly applied. The essential problem of incinerating is an arsenic release into atmosphere. Low pyrolysis is suggested as the methods of protecting arsenic release during incineration. The heavy metals were recovered after combustion of the treated wood at the low temperature which arsenic can not released. The recovery amounts of effectiveness compounds was determined in various solvents (citric acid, nitric acid, sulfuric acid, acetic acid, phosphoric acid) and different temperature (300, 400, $500^{\circ}C$). The higher temperature was applied, the more copper was recovered. The chromium was difficult to be recovered on the carbonized CCA treated wood at 0.5% acid concentration. The recovery mass of arsenic decreased on the higher combustion treated wood. The recovery of chromium was difficult due to the chemical change of the chromium arsenate during pyrolysis.