• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2001.11a
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• pp.301-310
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• 2001

본 연구는 내화성능을 가진 수막보호유리벽을 실제 건축물에 적용하는데 있어서 필수적으로 고려해야 할 가상시나리오 중에서 수막이 유리면을 보호하기 이전에 유리면에 근접되어 있는 화염으로부터 방출되는 복사열이 유리면이 가열된 상태에서 수막이 형성될 경우 유리면의 온도가 급속히 냉각됨으로서 발생할 수 있는 급냉파열특성을 규명하기 위해 실험한 연구로서 가열면온도범위에 따라 유리면에$150^{\circ}C$이상 $250^{\circ}C$이하에서 수막이 형성될 경우 급냉파열은 일어나지 않았으나 일반유리는 $100^{\circ}C$이상 $150^{\circ}C$이하에서 급냉파열이 일어남을 확인하였다. 즉 방화구획벽에 적용가능한 수막형성유리벽의 유리가 강화유리인점을 착안하면 수막의 도포이전에 강화유리면의 온도가 $250^{\circ}C$까지 올라가기 전에는 수막을 유리면에 접촉하여도 유리면의 급냉파열이 일어나짐 않음을 확인할 수 있었다. 이점은 일정한 구획내에서 유리면의 직근에 설치된 감지기에 의해 수막형성시스템의 가동을 할 경우 급내파열형상이 발생하지 않는 온도범위를 설정할 때 중요한 데이터로 활용가능하다. 결과적으로 국부복사열에 의하여 온도범위를 설정할 때 중요한 데이터로 활용가능하다. 결과적으로 국부복사열에 의하여 유리면의 온도가 급냉파열현상을 일으키는 한계온도에 이르기 전에 유리벽체 상부의감지기의 작동이 필수적으로 일어날 수 있음을 증명한다면 수막을 이용한 유리벽체를 일정시간이상의 내화성능이 요구되는 방화구획의 수직부재로 활용하는데 있어서 걸림돌이 되는 급냉파열에 대한 우려를 종식시키는데 이바지할 수 있다.l류 11.56%, acid류 38.87%, hydrocarbon류 2.89%, ester류 0.80%, 총 70.32%가 확인되었다. Alcohol류에서 linalool가 3.78%, acid류에서는 caproic acid류가 14.40%, carbonyl류에서 2-hydroxy-4-methoxyacetophenone이 2.99%, hydrocabon류에서는 aromadendrene가1.59% 그리고 ester류에서는 methyl palmitate가 0.43%으로 가장 많이 함유하고 있었다.0ppm에서 약 25.6%흡수되었고 ferric citrate 100ppm은 24.7%, ferrous sulfate는 19.7%흡수되었다. ILC를 첨가하지 않은 100ppm 철분염 용액은 ferrous sulfate를 제외하고는 흡수도가 감소되었다. 철분 결핍된 쥐에게 gavage 방법에 의하여 철분강화우유를 투여하였을 때 철분 25ppm 시료에서는 ferrous sulfate가 12.5%로 가장 높았고 ferrous lactate는 8.1%, ferric citrate는 6.5% 흡수되었다. 철분 100ppm수준에서는 흡수율이 낮아져 ferrous sulfate는 25ppm 시료보다 절반이하 수준이었다. Ferric citrate는 차이가 거의 없었으며 ferrous lactate는 70%수준이었다. 이상의 결과에서 철분강화우유에 사용하기 적합한 철분염은 ferrous lactate, ferric citrate였는데 특히 ferrous lactate는 제품의 이화학적 품질, 생이용성 측면 모두에서 가장 좋은 것으로 나타났다.다 높았으며, 1회당 평균 8.1$\pm$5.1개의 난포란을 회수하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.658-663
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• 2018

Current measuring methods for air quality are based on ground measurement networks and satellite data. New methods of collecting evidence with advanced sensors are needed because current methods have limitations in collecting evidence for the illegal emission of air pollutants at narrow areas or specific sites. This study analyzed the possibility of using an ultraviolet hyperspectral sensor to measure the concentration of nitrogen dioxide and sulfur dioxide. Two types of spectra were used: simulated spectra for gases with various concentrations using a radiative transfer model and observed spectra for each gas for a concentration. To understand the possibility of using a hyperspectral sensor, the differences between the simulated spectra and the observed spectra were analyzed, and the variation of simulated spectra were then analyzed according to the concentration. The results showed good agreement between observed spectra and simulated spectra. In addition, the absorption depth at specific wavelengths in the simulated spectra had a very strong correlation with the gas concentration. The gas concentration could be estimated using the hyperspectral sensor. In the future, validation would be needed to estimate the gas concentration through observations of various concentrations of gases using a hyperspectral sensor.

• Journal of the Korean Solar Energy Society
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• v.27 no.2
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• pp.71-78
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• 2007

The heat transfer characteristics of solar tower receivers are experimentally investigated with receiver shapes. Generally, these become different according to the shapes and materials of the volumetric air receiver. In order to study these effects, the apparatus adopting laminated mesh and honeycombs as the volumetric air receiver is proposed. The receiver consists of laminated mesh (diameter; 100 mm, thickness; 1 mm), honeycombs (diameter; 100 mm, thickness; 30 mm) inserted into ceramic tube (inside diameter; 100 mm, outside diameter; 120 mm, length: 1000 mm). To apply heat to the receiver, an electric heater is used. To find out the heat transfer characteristics of the laminated mesh, the air temperatures are obtained by installing 3 thermocouples on each layer, dividing ceramic tube into 4 layers. Also, a radiative shield is installed to measure the only air temperature. The data for laminated mesh and honeycomb thickness of 30, 60, 90 mm are obtained. The results show that the temperature of layer 3 is higher than those of layer 2 and layer 1.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.6
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• pp.665-680
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• 1997

The specific absorption rate (SAR) distributions in various models of the human head have been analyzed when the models are exposed to 350 MHz and 900 MHz plane waves. The numerical analysis is performed with the finite-difference time-domain (FDTD) method. A homogeneous sphere including a cylinderical neck, a homogeneous head shaped model, and a heterogeneous realistic model are used as models of human head. The incident plane wave used for these calculations is propagating from the front to the back or from the back to the front of the head model, with its E-field vector orientation being parallel to the major length of the body. The specific findings are: 1) the average SARs of the three models are similar mutually but the local SARs of them differ greatly mutually; 2) the power is deposed more deeply in the head at 350 MHz, which is roughly the resonant frequency of a human head, than at 900 MHz; 3) for a plane wave propagating from the back, "hot spot" is found in the neck region, not in the head; 4) for a plane wave propagating from the front, "hot spot" is found in the nose at 900 MHz, and in the upper part of the lip and the jaw region at 350 MHz.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.1
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• pp.35-41
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• 2008

The radiative heat loss from a receiver of a dish solar collector is numerically investigated. The dish solar collector considered in this paper consists of a receiver and multi-faceted mirrors. In order to investigate the performance comparison of dish solar collectors, six different mirror arrays and four different receivers are considered. A parabolic- shaped perfect mirror of which diameter is 1.40 m is considered as the reference for the mirror arrays. The other mirror arrays which consist of twelve identical parabolic-shaped mirror facets of which diameter are 0.405 m are suggested for comparison. Their reflecting areas, which are 1.545 $m^{2}$, are the same. Four different receiver shapes are a conical, a dome, a cylindrical, and a unicorn type. The radiative properties of the mirror surfaces and the receiver surfaces may vary the thermal performance of the dish solar collector so that various surface properties are considered. In order to calculate the radiative heat loss in the receiver, two kinds of methods are used. The Net Radiation Method that is based on the radiation heat balance on the surface is used to calculate the radiation heat transfer rate from the inside surface of the receiver to the environment. The Monte-Carlo Method that is the statistical approach is adopted to predict the radiation heat transfer rate from the reflector to the receiver. The collector efficiency is defined as the results of the optical efficiency and the receiver efficiency. Based on the calculation, the unicorn type has the best performance in receiver shapes and the STAR has the best performance in mirror arrays except the perfect mirror.

• Journal of Space Technology and Applications
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• v.1 no.3
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• pp.356-363
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• 2021

It was common knowledge in textbooks that images acquired using mid-infrared ray were not suitable for measuring temperature near room temperature. But a recent satellite image using a mid-infrared sensor show the possibility that the result measured using the mid-infrared sensor can also measure the temperature near room temperature. In this paper, the possibility and accuracy of extraction room temperature information from satellite images with mid-infrared sensors are reviewed. The mid-infrared satellite image reviewed in this paper showed the temperature of room temperature well, and regarding the reliability as an absolute value of the measured temperature, the effect of the heat transfer amount due to the direct reflection of sunlight on the surface and the effect of the infrared absorption amount absorbed in the atmosphere can be seen as a relatively small or constant value. However, the problem of uncertainty in the radiation coefficient due to physical properties, which is the limit of the non-contact thermometer, remained a problem to be solved.

• Resources Recycling
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• v.12 no.6
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• pp.32-37
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• 2003

For the reduction of electromagnetic biological effects from cellular phones, the electrical field radiation from cellular phone antenna is reduced by using partial ferrite material added on the phone case as ground plane. On the given properties (permittivity, permeability and conductivity) of ferrite material, the characteristics of monopole antenna is analysed depending on the variation of ferrite added configuration(thickness and shape). According to this analysis, the design method and direction to minimize the biological effects to human head is proposed in 1.7 GHz band PCS phones. For the exact analysis involving the permittivity, per-meability and conductivity of ferrite material, FDTD numerical method is used.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.3
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• pp.157-166
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• 2009

The pulverized coal combustion behavior in the coal fired utility boiler has been investigated with the CFD and process analysis techniques. The used commercial software were CFX and PROATES, and these were coupled each other to get more reliable boundary condition set-up, resulting in more reliable solution. For two cases which were the actual operation condition of A power plant, the calculated values from the coupled CFD and process analysis for thermal energy system were compared with the plant data, and the good agreements were obtained for Case 1 and 2. The calculated temperature distributions on the surface of heat exchangers were compared with the plant data for the steam temperatures across heat exchangers, and these explained the actual operating situation very well. The temperature deviation across the final superheater tube, which was believed to be the main cause of the frequent tube failure, were also explained very well with the calculated distributions of gas temperature and radiation on the plane of the final superheater.

• Journal of ILASS-Korea
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• v.18 no.4
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• pp.209-214
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• 2013

The present study aims to determine the optimized shape for the maximum electric energy production of building integrated photovoltaic system (BIPV) noise barrier through numerical analysis. The shape of BIPV noise barrier is one of the important factors in determining angle difference between direction vector of the sun and normal vector of the sound barrier surface. This study simulated numerically the flow and thermal fields for different angles in the range from $90^{\circ}$ to $180^{\circ}$, and from the results, the amount of isolation onto noise barrier surface was estimated along the angle between ground and top side of noise barrier. The commercial CFD code (Fluent V. 13.0) was used for calculation. It was found that the maximum amount of insolation per unit area was 19.6 MJ for $105^{\circ}$ case during a day in summer and was estimated 12.4 MJ in $150^{\circ}$ case during a day in winter. The results of the summer and winter cases showed the different tendency and this result would be useful in determining the appropriate shape of noise barrier which can be mounted under various circumstances.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.225-228
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• 2007

The objective of this study is to characterize design parameters of rocket igniters for composite, double base and nitramine propellant. Arc image furnace and fiber optics surface reflectometer were used to measure ignition delay time and reflected optical energy of several compositions of composite, double base and nitramine base rocket propellant at different pressure levels each other. The order of ignitability was double base > composite > Nitramine propellants at initial pressure of over 75 psia. The highest ignition energy was needed to ignite nitramine propellant, however, as the pressure increased up to the range of $75{\sim}400$ psia as the ignition delay time decreased abruptly. The absorbtion of radiation energy could be increased by the addition of small amount of opacifiers as carbon black, ZrC, WC and burning catalyst.