• Korean Journal of Optics and Photonics
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• v.11 no.2
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• pp.73-79
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• 2000

We measure a beam diameter of scan and sub-scan direction of LSD (Laser Scanning Urnt) which uses $fheta$ lens produced by injecLion molding method as a scanning lens. While the measured beam diameter in scan direction, which is $62muextrm{m}$ to $68\mu\textrm{m}$, shows similar size comparing to the design beam diameter, the sub-scan beam diameter shows sIzable beam diameter deviation as much as 37 11m ranging from $78\mu\textrm{m}$ to $115\mu\textrm{m}$. Injection molding lens has the surface figure error due to the shrinkage III the cooling time and the internal distortion (birefringence) due to the uneven cooling conditIOn so that these bring about wavefront aberration (i.e., the enlargement of beam size), and are eventually expre~sed as the deterioration of the pdnting image. In this paper. we first measure and analyze beam diameter, birefringence (polanzation ratio), and asphedcal figure error of mIens in order to know the principle cause of the beam diameter deviation in sub-scan directIOn. And Lhen. through the analysis of a designed depth of focus and a calculated field curvature (imaging position of the optical axis directIon) using the above figure elTor data, we know Lhat the birefringence IS the main factor of sizable beam diameter deVIation in sub-scan direction. ction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.415-421
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• 2021

This study analyzed the effect on the cooling performance of the channel shape of a heat sink for an insulated gate bipolar transistor (IGBT). A serpentine channel was used for this analysis, and the parameter for the analysis was the number of curves. The analysis was conducted using computational fluid dynamics with the commercial software ANSYS fluent. One curve in the channel improved the heat dissipation performance of the heat sink by up to 8% compared to a straight-channel heat sink. However, two curves in the channel could not improve the heat discharge performance further. Instead, the two curves caused a higher pressure drop, which induces parasitic loss for the pumping of coolant. The pressure drop of the two-curve channel case was 2.48-2.55 times larger than that of a one-curve channel. This higher pressure drop decreased the heat discharge efficiency of the heat sink with two curves. The discharge heat per unit pressure drop was calculated, and the result of the straight heat sink was highest among the analyzed cases. This means that the heat discharge efficiency of the straight heat sink is the highest.

• Journal of the Korean Geotechnical Society
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• v.39 no.7
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• pp.69-76
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• 2023

Cavity causes settlement and its remediation after an accident results in significant time and economic losses. This study aims to experimentally evaluate the prospect of using infrared camera to detect and measure underground subsidence. Emissivity is necessary to detect the energy emitted from an object and accurately assess temperature using an infrared camera. The emissivity in laboratory tests is fixed to evaluate a reasonable distance between the infrared camera and the object, and temperature values are assessed at various distances. In field experiments, the cavity of the field experiment is simulated using a PVC pipe with a diameter of 5 cm, artificially buried at depths of 5 and 25 cm from the surface. The infrared camera measurements are taken from 4 PM to 3 PM of the next day (a total of 23 h). The analysis included the time-series temperature distribution and the cooling rate index assessment, which represents the temperature change rate per unit of time. The results showed that various temperature trends are observed depending on the location of the subsidence. This study demonstrates that the infrared camera can be used to assess the condition of the subsurface.

• Journal of the Korean Solar Energy Society
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• v.34 no.5
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• pp.89-99
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• 2014

The determination of the solar and thermal performance of fenestration is required for the evaluation of fenestration energy performance, estimating building load. Presently, there exist several methods for determining the thermal transmission(U-value) and solar heat gain coefficient (SHGC) of fenestration system. These method are commonly grouped under calculation or experimental methods. While U-value testing and calculation methods have been long established, SHGC has been evaluated only by the method of calculation under the lack of any established testing method. However, it is difficult to assess the exact SHGC for various types of fenestration with sun-shading or other solar control systems. The purpose of this study was to evaluate the effect of interior venetian blind and roll screen on the SHGC of glazing system. SHGC has been evaluated by the KS L 9107 test method and exiting calculation method for precise comparison of the energy performances of various shading devices. In this research, the test sample consists of three different types of double glazing unit with venetian blind and roll screen. Slat angles of venetian blind were changed to $-45^{\circ}$, $0^{\circ}$, and$-45^{\circ}$. For the roll screen, measurements were taken with the roll screen in the closed position. In result, the venetian blind reduced SHGC by 21.2~28.4% at $45^{\circ}$, when compared to the double glazing unit. The roll screen reduced SHGC by 34.4~41.7% at closed. The differences between the measured and calculated SHGC were found to range between 0.001(0.2%) and 0.047(11.1%) for all test cases. For the cases of venetian blind $-45^{\circ}$, $0^{\circ}$ and $45^{\circ}$, the deviation ratio were 3.6~9.8%, 1.1~2.6%, 4.2~11.1%, respectively. For the case of roll screen, the deviation ratio were 4.1~5.7%.

• Journal of Radiation Protection and Research
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• v.28 no.2
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• pp.109-116
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• 2003

Based on the necessity to evaluate the activation products inventory during decommissioning lot domestic nuclear power plants, a preliminary estimation of the activation products inventory for Kori unit 1, which is getting close to the end of lifetime, was carried out with ANISN and ORIGEN2 code. In order to calculate neutron nux using ANISN code, the reactor was divided into 9 zones from core to bioshield concrete for radial direction. Also :he cross-section of main nuclides were calibrated with neutron flux in the reactor pressure vessel(RPV) region. The results showed that 95 % of tile total radioactivity in RPV from reactor shutdown to 10 years came from the nuclides of $^{55}Fe,\;^{59}Ni,\;^{63}Ni\;and\;^{60}Co$. And the total radioactivity with cooling of more than 50 years after decommissioning was no more than 0.2 % of at the time of shutdown. Considering the weight of RPV is 210 tons, the total radioactivity of RPV reached to $5.25{\times}10^{6}GBq$ at shutdown time. As compared with the total radioactivity of bioshield concrete at reactor shutdown time, the radioactivity after tooling more than 10 years was below 1 %.

• Korean Chemical Engineering Research
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• v.59 no.1
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• pp.60-67
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• 2021

This study presented techno-economic analysis of a 500 MWe oxy-coal power plant with CO2 capture. The power plant included a circulating fluidized-bed (CFB), ultra-supercritical steam turbine, flue gas conditioning (FGC), air separation unit (ASU), and CO2 processing unit (CPU). The dry flue gas recirculation (FGR) was used to control the combustion temperature of CFB. One FGR heat exchanger, one heat exchanger for N2 stream exiting ASU, and a heat recovery from CPU compressor were considered to enhance heat efficiency. The decrease in the temperature difference (ΔT) of the FGR heat exchanger that means the increase in heat recovery from flue gas enhanced the electricity and exergy efficiencies. The annual cost including the FGR heat exchanger and FGC cooling water was minimized at ΔT = 10 ℃, where the electricity efficiency, total capital cost, total production cost, and return on investment were 39%, 1371 M$, 90 M$, and 7%/y, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.89.1-89.1
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• 2011

According to green growth's policy, green-home dissemination's projects are promoting. Among them, stationary fuel cell systems are receiving attention due to high efficiency and clear energy. But it need absolutely to develop cost down technologies and improve system durability for commercialization of the fuel cell system. To achieve this objectives, in 2009, the Korean Government and "Korea Institute of Energy Technology Evaluation and Planning(KETEP)" launched into the strategic development project of BOP technology for practical applications and commercializations of stationary fuel cell systems, named "Technology Development on Cost Reduction of BOP Components for 1kW Stationary Fuel Cell Systems to Promote Green-Home Dissemination Project". This paper introduces a summary of improved BOP performances that has been achieved through the 2nd year development precesses(2010.06~2011.05) base on 1st year development precesses(2009.06~2010.05). The major elements for fuel cell systems are cathode air blowers, burner air blowers, preferential oxidation air blowers, fuel blowers, cooling water pumps, reformer water pumps, heat recovery pumps, mass flow meters, electrical valves, safety valves and a low-voltage inverter. Key targets of those elements are the reduction of cost, power consumption and noise. Invert's key targets are development the low -voltage technologies in order to reduce the number of unit cell in fuel cell system's stack.

• Journal of Korean Society on Water Environment
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• v.25 no.1
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• pp.58-68
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• 2009

Low impact development (LID) technique is relatively new concept to reduce surface runoff and pollutant loading from land cover by attempting to match predevelopment condition with various integrated management practices (IMPs). In this study, computational model for designing and evaluating LID, named LIDMOD, was developed based on SCS-CN method and applied at Andong bus terminal to evaluate LID applicapability and design retention/detention area for volume or peak flow control. LIDMOD simulated with 21 years simulation period that yearly surface runoff by post-development without LID was significantly higher than that with LID showing about 2.8 times and LID could reduce efficiently yearly surface runoff with 75% reduction of increased runoff by conventional post development. LIDMOD designed detention area for volume/peak flow control with 20.2% of total area by hybrid design. LID can also efficiently reduce pollutant load from land cover. Pollutant loads from post-development without LID was much higher than those from pre-development with showing 37 times for BOD, 2 times for TN, and 9 times for TP. Pollutant loads from post-development with LID represented about 57% of those without LID. Increasing groundwater recharge reducing cooling and heating fee, creating green refuge at building area can be considered as additional benefits of LID. At the point of reducing runoff and pollutant load, LID might be important technique for Korean TMDL and LIDMOD can be useful tool to calculate unit load for the case of LID application.

• Journal of the Korean Home Economics Association
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• v.27 no.1
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• pp.39-46
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• 1989

Mung bean starch gel (Mook) and gel made from starch of cowpea are similar properties in texture. In order to elucidate the similarity between these two starch gels, some physicochemical properties of cowpea starch were compared with those of mung bean starch. Water bildings capacity of cowpea starch (183.6%) was a little low than that of mung bean starch (184.2%). The solobility, swelling power and optical transmitance of the cowpea starch showed a smiliar pattern to mung bean starch, but cowpea starch had a little lower solubility than mung bean starch. Amylogram of mung bean strach (4, 5, 6, 7%) shoved no peak viscosity but cowpea starch (4, 5, 6%) showed peak viscosity and both starches showed high viscosities when cooling. Cowpea and mung bean starches had the blue value of 0.41 and 0.47, the alkali number of 8.4 and 8.0, the amylose content of 30.5 and 32.1%, the molecular weight of amylose of 30,000 adn 29,258 and glucose unit per segment of amylopectin of 27.6 and 26.8 respectively. The shape of cowpea and mung bean strach granules were round and elliptical, and the mean vlalue of major axis, minor axis and the ratio of these were 20.7 and 21.8 ${\mu}{\textrm}{m}$, 14.6 and 14.4 ${\mu}{\textrm}{m}$ and 1.42 and 1.51, respectively. The extent of retrogradation determined by the glucoamylase digestion method and syneresis showed that cowpea starch gel was larger than that syneresis showed than cowpea starch gel was larger than that of mung bean starch gel. The redults of X-ray diffraction studies showed A pattern for two starches, Diffraction peak of gels disappeared with gelatinization of starches but that of two starch gels storaged for 2 days at 5$^{\circ}C$ showed a similar patterm.

• KIEAE Journal
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• v.14 no.2
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• pp.87-98
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• 2014

This study is to identify quantitatively the function of carbon dioxide emissions reduction due to temperature and energy reduction according to direct carbon dioxide storage, shade provision, and evaportanspiration of urban park. According to the result of study, landscape tree indicated high carbon dioxide storage effect compare to bush, in which broadleaf tree indicated higher storage function than coniferous tree. It is believed to be the storage of carbon dioxide can be increased by increasing the composition rate of forest plants in the urban park. According to the direct estimation result of carbon dioxide storage in terms of example area, storage of carbon dioxide is estimated to be "seoul a zone" $476,818.8kg{\cdot}CO_2/m^2yr$, "anyang b zone" $186,435.7{\cdot}CO_2/m^2yr$, "daejeon c zone" $262,826{\cdot}CO_2/m^2yr$, "kwangju d zone" $231,657.8{\cdot}CO_2/m^2yr$. The carbon dioxide storage per unit area estimated to be "seoul a zone" $3.4{\cdot}CO_2/m^2yr$, "anyang b zone" $5.0{\cdot}CO_2/m^2yr$, "daejeon c zone" $2.6{\cdot}CO_2/m^2yr$, "kwangju d zone" $5.6{\cdot}CO_2/m^2yr$. The result of indirect carbon dioxide reduction effect estimated to be "seoul a zone" $291,603.4{\cdot}CO_2/m^2yr$, "anyang b zone" $165,462.4{\cdot}CO_2/m^2yr$, "daejeon c zone" $141,719.2{\cdot}CO_2/m^2yr$, "kwangju d zone" $154,803.4{\cdot}CO_2/m^2yr$. Carbon dioxide reduction potential amount through the urban park was increased to 1.6 times to 1.8 times when calculated to the indirect effect.