• Journal of Sensor Science and Technology
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• v.29 no.1
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• pp.27-32
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• 2020

This study proposes a pixel-patterning method for organic light-emitting diodes (OLEDs) based on thermal transfer. An infrared lamp was introduced as a heat source, and glass type donor element, which absorbs infrared and generates heat and then transfers the organic layer to the substrate, was designed to selectively sublimate the organic material. A 200 nm-thick layer of molybdenum (Mo) was used as the lightto-heat conversion (LTHC) layer, and a 300 nm-thick layer of patterned silicon dioxide (SiO₂), featuring a low heat-transfer coefficient, was formed on top of the LTHC layer to selectively block heat transfer. To prevent the thermal oxidation and diffusion of the LTHC material, a 100 nm-thick layer of silicon nitride (SiN_x) was coated on the material. The fabricated donor glass exhibited appropriate temperature-increment property until 249 ℃, which is enough to evaporate the organic materials. The alpha-step thickness profiler and X-ray reflection (XRR) analysis revealed that the thickness of the transferred film decreased with increase in film density. In the patterning test, we achieved a 100 ㎛-long line and dot pattern with a high transfer accuracy and a mean deviation of ± 4.49 ㎛. By using the thermal-transfer process, we also fabricated a red phosphorescent device to confirm that the emissive layer was transferred well without the separation of the host and the dopant owing to a difference in their evaporation temperatures. Consequently, its efficiency suffered a minor decline owing to the oxidation of the material caused by the poor vacuum pressure of the process chamber; however, it exhibited an identical color property.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.3
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• pp.7-17
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• 2014

Power electronics modules are semiconductor components that are widely used in airplanes, trains, automobiles, and energy generation and conversion facilities. In particular, insulated gate bipolar transistors(IGBT) have been widely utilized in high power and fast switching applications for power management including power supplies, uninterruptible power systems, and AC/DC converters. In these days, IGBT are the predominant power semiconductors for high current applications in electrical and hybrid vehicles application. In these application environments, the physical conditions are often severe with strong electric currents, high voltage, high temperature, high humidity, and vibrations. Therefore, IGBT module packages involves a number of challenges for the design engineer in terms of reliability. Thermal and thermal-mechanical management are critical for power electronics modules. The failure mechanisms that limit the number of power cycles are caused by the coefficient of thermal expansion mismatch between the materials used in the IGBT modules. All interfaces in the module could be locations for potential failures. Therefore, a proper thermal design where the temperature does not exceed an allowable limit of the devices has been a key factor in developing IGBT modules. In this paper, we discussed the effects of various package materials on heat dissipation and thermal management, as well as recent technology of the new package materials.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.5
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• pp.709-715
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• 1996

In order to estimate the carrying capacity of oyster culture ground in Kamak Bay, primary productivity was calculated using the ecosystem model. The allowable maximum oyster production, namely, the carrying capacity of Kamak Bay was estimated by using the annual phytoplankton production and conversion coefficient to oyster meat. On the environmental conditions of oyster culture period from lune, 1994 to March, 1995, phytoplankton production, the allowable maximum oyster production were estimated to be 181,594 tons of carbon and 287,033 tons of oyster meat, respectively. The allowable maximum oyster production was estimated to be 15,443 tons in the actual culture ground where oyster culture facilities are installed in Kamak Bay. In 1994 4,532 tons of actual oyster meat production was equivalent to ra. $29\%$ of carrying capacity, and in 1987 it was 14,592 tons equivalent to ca. $95\%$.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.5
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• pp.473-478
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• 2013

In this paper, we develop the Heavy Rain Advisory Decision Model based on intelligent neuro-fuzzy algorithm RBFNNs by using KLAPS(Korea Local Analysis and Prediction System) Reanalysis data. the prediction ability of existing heavy rainfall forecasting systems is usually affected by the processing techniques of meteorological data. In this study, we introduce the heavy rain forecast method using the pre-processing techniques of meteorological data are in order to improve these drawbacks of conventional system. The pre-processing techniques of meteorological data are designed by using point conversion, cumulative precipitation generation, time series data processing and heavy rain warning extraction methods based on KLAPS data. Finally, the proposed system forecasts cumulative rainfall for six hours after future t(t=1,2,3) hours and offers information to determine heavy rain advisory. The essential parameters of the proposed model such as polynomial order, the number of rules, and fuzzification coefficient are optimized by means of Differential Evolution.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.12
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• pp.1724-1727
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• 2001

A trial was conducted to evaluate the growth performance and carcass characteristics of LW ${\times}$ Mukota $F_1$ crosses when fed diets containing graded levels of maize cob meal. Sixteen LW ${\times}$ Mukota $F_1$ crossbred pigs of approximately 4.5 months of age, were randomly allocated to four diets that contained 0, 100, 200 and 300 g maize cobs/kg, which corresponded to 276.4, 360.3, 402.9 and 523.5 g NDF/kg, respectively. The pigs were fed ad libitum for 14 weeks. The diets were formulated to contain similar levels of energy (ca. 9MJ ME/kg) and protein (ca.160 g CP/kg). Average daily feed intake (ADFI), daily gain (ADG) and feed conversion ratio (FCR) were monitored for 14 weeks. At slaughter, the cold dressed weight (CDM) and backfat thickness (BFT) were determined. There was no significant linear relationship (p>0.05) between level of cob inclusion and ADFI. The ADG decreased as level of maize cobs increased (p<0.001). The pigs that were on 300 g cobs/kg had the highest FCR (p<0.05) as compared to pigs on the other three diets. No differences (p>0.05) were observed in the CDM between pigs that were fed diets that had 0 and 100 g maize cobs/kg. In addition, pigs on 100 and 200 g cobs/kg diets had the same CDM (p>0.05). The diet that contained 300 g cobs/kg gave the lowest (p< 0.001) CDM. Both BFT parameters showed a decrease (p<0.05) as level of maize cobs increased. An increase in CDM was associated with an increase in BFT (p<0.001), with the correlation coefficient between K7.5 and CDM being 0.84 (p<0.001). It can, therefore, be concluded that crossbred pigs perform well on diets containing up to 200 g/kg maize cobs.

• Journal of the Korean Society of Hazard Mitigation
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• v.1 no.1 s.1
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• pp.127-138
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• 2001

Although Carbon/Carbon Composites(CFRCs) have excellent mechanical properties at high temperature, the disadvantage of combustion in air restricts their applications. Thus a lot of investments have been studied to improve the drawback of CFRCs. In this study, SiC used as a thermal protective coating material possesses almost the same expansion coefficient compared to that of carbon, so SiC was coated on 4D (directional) CFRCs by Pack-Cementation process. For the 4D CFRCs coated with SiC, optical microscopy observations were performed to estimate the coating mechanism involved and TGA tests were also performed to evaluate the improvement of combustion resistance. And their high temperature combustion properties were investigated by the arc torch plasma test. From the results, it is found that the mechanical properties and high temperature combustion properties of the 4D(directional) CFRCs coated with SiC were much better than bare 4D CFRCs.

• Journal of Korean Society of Transportation
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• v.27 no.4
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• pp.41-53
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• 2009

For 5 years and 6 months, ranging from January 2003 to June 2008, SPSS 12.0 Statistical Program was used to analyze the overall analysis, analysis of center line encroachment, analysis of signal violations, analysis of drinking while intoxicated, analysis of driving without license, analysis of two-wheel vehicle, analysis of pedestrian, analysis of safety equipment, analysis of traffic publicity or education and automobile registration accounts, and casualty of traffic accidents that are determined as having statistical implication based on the statistics available from the policy to take a look at traffic accident in the Daejeon area, and there were some meaningful results. With the proof that there is a certain level of ratio for the correlations between traffic control and traffic accident that the effect of traffic control has shown with certain time interval. The relationship of traffic control and the casualty of traffic accident has very low coefficient of correlations that it is not statistically noticeable that traffic control of the police has almost no effect in preventing traffic accident. This is a display of the fact that the conversion of direction for traffic safety measure undertaken to this point is rather urgent that there is a dire need of establishing the effective alternatives.

• Journal of Korean Society on Water Environment
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• v.28 no.6
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• pp.813-818
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• 2012

BOD and COD are currently used for water quality indices, but adoption of TOC for TMDL (Total Maximum Daily Load) is being suggested. Estimation of TOC using existing BOD and COD data is very important to diagnosis water quality trend when TOC is used for water quality index of organic matter in the future. The relationships between BOD COD and TOC in runoff from paddy fields were investigated during 2008-2011. The observed mean concentration of EMCs (Event Mean Concentration) for BOD, COD, TOC were 3.87, 10.97, 7.26 mg/L respectively. The correlation coefficients between BOD-TOC and COD-TOC were 0.42, 0.73, respectively. The coefficient of determination of regression equation for BOD-TOC and COD-TOC were 0.18, 0.53 respectively. Even though, conversion of COD data to TOC seems to be rather reliable than that of BOD-TOC, further monitoring is recommended to ensure better interpretation of relationship among BOD, COD and TOC.

• Journal of Korea Water Resources Association
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• v.37 no.6
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• pp.499-507
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• 2004

In this study, the fully coupled SWAT-MODFLOW model is developed by using the type of embedment MODFLOW in SWAT. Since SWAT model has semi distributed features, its groundwater component can't consider distributed parameters such as hydraulic conductivity, storage coefficient and spatially variable natures such as distribution of groundwater heads and pumping rate and so forth. The main purpose of this study is to overcome these limitations. This linkage is completed considering the interaction between stream network and aquifer to reflect boundary flow. To correspond HRU in SWAT to grid in MODFLOW, HRU-GRID conversion tool using DEM is newly suggested. As groundwater recharge of MODFLOW can be estimated accurately by SWAT model, the reliability of groundwater discharge and total runoff of watershed could be greatly enhanced.

• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.580-587
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• 1994

The oxidative coupling of methane was studied kinetically using $Na^+(50wt%)/MgO$ catalyst at 710, 730, 750, 770 and $790^{\circ}C$ in a fixed bed flow reactor at the atmospheric pressure under differential conversion conditions. Through curve fitting, it was found that the Langmuir-Hinshelwood type mechanism was fitted to this reaction rather than Rideal-Redox type or Eley-Rideal type mechanism. Therefore, it was proposed that the $O_2{^-}$ or $O_2{^{2-}}$ species on the surface was related to the production of $CH_3{\cdot}$. The estimated activation energy of $CH_3{\cdot}$ production was about 39.3kcal/mol. Moreover, as the result of curve fitting, the stoichiometric coefficient of $O_2$ for the production of $CH_3{\cdot}$ to produce $CO_x$was approximately 1.5. Accordingly, it could be concluded that the $CH_3O_2{\cdot}*$ was prouduced through the partial oxidation of $CH_3{\cdot}$ with the surface oxygen.