• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.853-860
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• 2019

In order to meet more severe environmental regulations, oxy-fuel circulating fluidized bed(CFB) boilers or ultra supercritical CFB boilers, which are a kind of process in that solid particles moves similar to fluid, have been developed in the world. In CFB power generation processes, the method to reduce or remove sulfur dioxide is in-situ desulfurization reaction via limestone directly injected into CFB boilers. However, the desulfurization efficiencies have continuously changed because limestones injected into CFB boilers are affected by various operation conditions (Bed temperature, pressure, solid circulating rate, solid holdup, residence time, and so on). In this study, a prediction method with physical and chemical properties of limestone and operation conditions of CFB boiler for in-situ desulfurization reaction in CFB boilers has developed by integrating desulfurization kinetic equations and hydrodynamics equations for CFB previously published. In particular, the prediction equation for in-situ desulfurization was modified by using experimental results from desulfurization reactions of various domestic limestones.

• Journal of Korea Trade
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• v.25 no.2
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• pp.111-133
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• 2021

Purpose - Although remittance payment in international trade settlements has played a bigger role in recent years, scant research is being done. This study is to zero in on analyzing determinants of international trade payments focused on remittance by constructing a payment prediction model. Design/methodology - This study categorizes the types of trade payments into advance remittance, post remittance, linked remittance, letter of credit, and mixed payment, and analyzes these after constructing a logit model. For empirical analysis, 147 survey data were collected for export manufacturers in Korea, and binominal logistic regression analysis was used to analyze the type of payment method the exporter chooses for trade transactions. Findings - The likelihood of choosing advance remittance increased as the exporters had non-recovery experiences with payments, and decreased as the market power of importers increased. The possibility of post remittance increased when the export amount was large and the character of the buyer was reliable. In the case of linked remittance, it was highly likely to be selected when payment efficiency was important in trade settlement. In addition, when competition among companies in the global market is intense and market uncertainty is high, the possibility of using a letter of credit decreases. It was also found that the greater the export amount, the greater the possibility of choosing advance remittance, and even if the transaction period was longer, exporters using a letter of credit continued to use it. Originality/value - Despite the high proportion of remittances in international trade settlements, it has been hard to find studies that reflect the practical characteristics of remittances. This study classified the types of remittance into advance remittance, post remittance, and linked remittance, and built a trade payment prediction model by adding a letter of credit and mixed payment. In addition, the originality of this study is recognized in that a logistic model was constructed and meaningful results were derived.

• Journal of Korean Society on Water Environment
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• v.37 no.2
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• pp.103-113
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• 2021

In this study, an Excel-based model (ROADMOD) was developed to estimate pollutant loading from the road and evaluate BMPs. ROADMOD employs the Chezy-Manning equation and empirical expression for estimating surface runoff, and power function for pollutant buildup, and exponential function for pollutant washoff in SWMM. The results of model calibration for buildup and washoff using observed data revealed a good match between the simulation results and the observed data. The long-term surface runoff and sediment simulated by ROADMOD demonstrated a good match with those by SWMM with 2 ~ 14% of relative error. The shorter sweeping interval (within 8 days) remarkably decreased sediment loads from the road. It was found that the effect of reducing sediment loads from the road was greatly affected not only by the sweeping interval but also by sweeping on the day before a rainfall event. The 48% of removal efficiency of sediment loads from the road was achieved with 26 times of road sweeping per year when sweeping was performed on the day before the rainfall event. A 4-day sweeping interval showed similar removal efficiency (48%) with 96 times of sweeping per year. It is considered that the road sweeping on the day before a rainfall event could maximize the effect of reducing the non-point source pollution from the road with minimization of the number of road sweeping. So, the road sweeping on the day before a rainfall event can be considered as one of the useful and best management practices (BMPs) on road.

• International Area Studies Review
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• v.18 no.3
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• pp.67-88
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• 2014

The Chinese stock market has increasingly strengthened its market power on other stock markets due to rapid growth of its economy. In this context, this study investigated return spillover effect as well as asymmetric volatility spillover effect using a VAR-Bivariate EGARCH model among stock markets(China, US, Japan, Korea). Furthermore, we conjectured the impact of 2008 global financial crisis on the spillover effect of the Chinese stock market. In our empirical results, the Chinese stock market has a weak return spillover effect to other markets(US, Japan, Korea), but after the global financial crisis, its return spillover effect becomes stronger among other stock markets. In addition, the Chinese stock market have strengthened its asymmetric volatility spillover effect on other stock markets after the Global financial crisis. As a result, the Chinese stock market has an strong influence on other stock markets.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.6
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• pp.497-504
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• 2018

Platform Support Vessels operated in the Arctic Ocean support diverse operations of offshore plant in the sea, and the PSV is also needed to support works to exploit the oil and gas in the Arctic Ocean. Both of the ice breaking and the open sea performance have been considered together to secure the enhanced operational performance at the harsh environment in the Arctic Ocean and the open sea as well. In this study, One of the design requirements of a PSV is to guarantee continuous icebreaking performance with 3 knots at 1 m thickness of level ice, where the design draft is 7.5m and the engine power is 13 MW. Three hull forms were designed, and the ice resistance based on empirical formulas was estimated to select the initial hull form having an outstanding performance. The full scale performance of the designed hull forms was predicted by the ice model test conducted in the ice model basin of Korea Research Institute of Ships & Ocean Engineering(KRISO). The analysed results show that the selected hull form satisfies the above design requirement.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.6
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• pp.596-605
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• 2018

Interest in hydrogen, as an energy carrier, has been growing to solve the problems on shortage of fossile fuels and greenhouse gas. According to the standard KGS FU 551 for stationary fuel cell installation, the fuel cell system could be connected up to two common exhausts to one floor. depending on the required power for building or the installation environment in buildings, multiple fuel cell systems could be installed. Afterwards the number of perforations and flues could be decided. Hence, economic efficiency in significantly determined with respect to installation area and the number of fuel cell systems. In addition, the complexity of common vent structure for stationary fuel cell systems could be changed. In this paper, Verification experiments were conducted by connecting the common exhaust system to the fuel cell simulation system and the actual fuel cell system. Humidity and temperature were changed at ON/OFF, but no factors were found to affect performance or system malfunction. Exhaust emissions were also measured to obtain optimized values. We intend to expand the diffusion of stationary fuel cells by verifying safety of common exhaust structure.

• Nuclear Engineering and Technology
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• v.51 no.4
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• pp.987-995
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• 2019

Steam jet condensation is of great importance to pressure suppression containment and automatic depressurization system in nuclear power plant. In this paper, the condensation processes of sonic steam jet in a quiescent subcooled pool are recorded and analyzed, more precise understanding are got in direct contact condensation. Experiments are conducted at atmospheric pressure, and the steam is injected into the subcooled water pool through a vertical nozzle with the inner diameter of 10 mm, water temperature in the range of $25-60^{\circ}C$ and mass velocity in the range of $320-1080kg/m^2s$. Richardson number is calculated based on the conservation of momentum for single water jet and its values are in the range of 0.16-2.67. There is no thermal stratification observed in the water pool. Four condensation regimes are observed, including condensation oscillation, contraction, expansion-contraction and double expansion-contraction shapes. A condensation regime map is present based on steam mass velocity and water temperature. The dimensionless steam plume length increase with the increase of steam mass velocity and water temperature, and its values are in the range of 1.4-9.0. Condensation heat transfer coefficient decreases with the increase of steam mass velocity and water temperature, and its values are in the range of $1.44-3.65MW/m^2^{\circ}C$. New more accurate semi-empirical correlations for prediction of the dimensionless steam plume length and condensation heat transfer coefficient are proposed respectively. The discrepancy of predicted plume length is within ${\pm}10%$ for present experimental results and ${\pm}25%$ for previous researchers. The discrepancy of predicted condensation heat transfer coefficient is with ${\pm}12%$.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.30 no.3
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• pp.116-120
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• 2019

Objectives: This study was conducted to re-validate the clinical efficacy of the Korean Adult Attention-Deficit/Hyperactivity Disorder (ADHD) Rating Scale (K-AARS), which is a self-report scale for ADHD in adults, and to determine the clinical utility and cut-off scores of K-AARS. Methods: The participants were 135 drug naïve adults with ADHD and 144 healthy controls. To diagnose ADHD based on the diagnostic criteria of the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition, two board-certified pediatric psychiatrists interviewed the participants and completed the Mini International Neuropsychiatric Interview. K-AARS was applied to all participants. K-AARS comprises six clinical subscales, one impairment subscale, and one driving behavior subscale. The receiver operating characteristic analysis was conducted to calculate the cut-off scores of K-AARS. Results: All subscale scores, including six clinical subscale, impairment subscale, and driving behavior subscale scores, were found to be significant in distinguishing adults with ADHD from healthy controls. The sensitivity and specificity of the six clinical subscales were 63.0-77.0% and 66.7-79.9%, respectively. The combined total score of the six clinical subscales, had a sensitivity of 80.0% and specificity of 79.9%. Conclusion: The discriminative power of K-AARS for the diagnosis of ADHD in adults was excellent, and K-AARS and the empirical diagnosis of adults can be useful in diagnosing ADHD in adulthood.

• The Research Journal of the Costume Culture
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• v.29 no.1
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• pp.103-120
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• 2021

This study interprets Siberian shaman costumes from the perspective of Siberian shamanism's spiritual culture by combining theoretical and empirical studies. According to the natural environment and language families, the Siberian people are classified into the Altai, Tungus, Ural, and Paleo-Siberian groups. Se Yin's research classifies the spiritual culture of Siberian shamanism as cosmic, spiritual, and nature view. Eliade's research has divided Siberian shaman costumes into form, headdress, and ornament. According to the present study, shaman costume form and decoration reflect the Siberian three-tiered cosmic view, such that the shaman's head, body and feet correspond to the upperworld, middleworld and underworld. In addition, animism, totemism and ancestral worship appear in the shamanism's spiritual view. For example, the costume's form shows the totem of each tribe, while the costume accessories reflect animal worship, plant worship and ancestral worship. Finally, shamanism's nature view mainly manifests through three processes: personification, deification, and ethics. As an intermediary between man and the spirits, shaman use their clothing to reproduce the image of half man and half spirit. The shaman's costumes are deified and considered to have divine power. For example, the animals represented on the costume help the shaman travel through space. Generally, good animals help a shaman enter the upperworld, while animals that help a shaman enter the underworld are considered evil. Also, the number of hanging accessories represents the shaman's ability.

• The Journal of the Korea Contents Association
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• v.21 no.6
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• pp.552-560
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• 2021

With the recent development of the art distribution system, interest in art investment is increasing rather than seeing art as an object of aesthetic utility. Unlike stocks and bonds, the price of artworks has a heterogeneous characteristic that is determined by reflecting both objective and subjective factors, so the uncertainty in price prediction is high. In this study, we used LSTM Recurrent Neural Network deep learning model to predict the auction winning price by inputting the artist, physical and sales charateristics of the Korean artist. According to the result, the RMSE value, which explains the difference between the predicted and actual price by model, was 0.064. Painter Lee Dae Won had the highest predictive power, and Lee Joong Seop had the lowest. The results suggest the art market becomes more active as investment goods and demand for auction winning price increases.