• Journal of Power Electronics
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• v.18 no.5
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• pp.1336-1346
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• 2018

Wide band gap semiconductor devices such as SiC MOSFETs are becoming the preferred devices for high frequency and high power density converters due to their excellent performances. However, the proportion of the switching loss that accounts for the whole inverter loss is growing along with an increase of the switching frequency. In view of the third quadrant working characteristics of a SiC MOSFET, synchronous rectification discontinuous pulse-width modulation is proposed (SRDPWM) to further reduce system losses. The SRDPWM has been analyzed in detail. Based on a frequency domain mathematical model, a quantitative mathematical analysis of the harmonic characteristic is conducted by double Fourier transform. Meanwhile, a switching loss model and a conduction loss model of inverter for SRDPWM have been built. Simulation and experimental results verify the result of the harmonic analysis of the double Fourier analysis and the accuracy of the loss models. The efficiencies of the SRDPWM and the SVPWM are compared. The result indicates that the SRDPWM has fewer losses and a higher efficiency than the SVPWM under high switching frequency and light load conditions as a result of the reduced number of switching transitions. In addition, the SRDPWM is more suitable for SiC MOSFET converters.

• Journal of Engineering Education Research
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• v.9 no.2
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• pp.52-70
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• 2006

Systems Engineering(SE), as a special discipline evolved from multidisciplinary and interdisciplinary design knowledges and practical lessons learned from development practices, is required to develop today's ever-growing large complex systems. As computer speed and analytic sophistication accelerate their applications, modern society's needs have become increasingly varied and complex. Rapid advances in Systems Engineering and its education programs among the developed countries demonstrate their needs as an alternative to what is lacking from traditional disciplinary engineering to meet new challenges of our changing social environments. Systems Engineering is an interdisciplinary approach that includes both management and technical processes. Its processes, methods, and tools are used to evolve, define, and verify an integrated, life-cycle balanced set of system solution that satisfy customer needs and requirements. The process methodology offers a top-down comprehensive, iterative and recursive problem solving process which includes the stating the problems, investigating the alternatives, architecting and modeling the system, integrating and operating the system, assessing and re-evaluating the system performances. The purpose of this paper is to research the cases of SE educational programs for both domestic and other developed countries and to propose recommendations for the domestic SE educational programs in the future.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.1
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• pp.1-7
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• 1998

A total of 120 pigs $(L\;{\times}\;LW\;{\times}\;D)$ averaged 14.16 kg of body weight were reared under six dietary treatments to evaluate the effects of amino acid supplementation on their performances. Treatments were 1) 18% CP diet (control); 2) 15% CP+0.28% Lys (B, 15L); 3) B+0.06% Met (15LM); 4) B+0.13% Thr (15LT) ; 5) B+0.06% Met+0.13% Thr (15LMT); 6) B+0.06% Met+0.13% Thr+0.05% Trp (15LMTT). Each treatment had 4 replicates with 5 pigs per replicate. The daily weight gains were statistically similar in 15LMT, 15LMTT and control groups. Threonine and methionine supplementation resulted in improved growth performance and nutrient digestibilities, while tryptophan supplementation had little beneficial effect. However, the best feed conversion was found in the control group. Dry. matter and CP digestibilities were improved in the 15LMT and 15LMTT groups. Gross energy, crude fat and phosphorus digestibilities were not affected by the treatment. Among the 15% CP groups, nitrogen digestibility showed the tendency to be increased as the more synthetic amino acids were added. Dry matter and nitrogen excretions were significantly reduced by feeding low protein, amino acid fortified diets, while phosphorus excretion was not influenced. Essential amino acids digestibility was higher in 15LT, 15LMT and 15LMTT groups and lower in the control. The 15LT group showed the best lysine digestibility, and methionine digestibilities were higher in all treated groups than control one. Threonine digestibilities higher in 15LT 15LMT, and 15LMTT than the control. The result shows that threonine and methionine should be added to the diet containing 15% CP diet, fortified with lysine to get same performance of 18% CP diet.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.8
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• pp.1234-1240
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• 1999

The nutritive value of rumen contents and barley mixture (4:1 w/w; RCB) was evaluated and the effect of their feeding on growth performances in Najdi lambs was studied. A metabolism trial was conducted with 16 rams divided into four dietary groups. The diets were: a whole-mixed control diet and three diets where RCB was incorporated at the rates of 25, 50 and 100%, replacing an equal amount of control diet. The results showed that there was a depression (p<0.05) in DM digestibility for the 100% RCB diet in comparison with other diets. The digestibility of CP was higher(p<0.05) for the 25% RCB diet as compared to the control diet; there was a trend for a small (p>0.05) decrease in digestibility as level of RCB increased. Lambs in all studied diets were in positive nitrogen balance; the differences between diets were not significant. A total of 45 lambs were allotted into three groups and used to evaluate the effect of dietary inclusion of RCB (0, 25 and 50%) on growth performance and carcass traits. Daily DM intake, final body weight, carcass weight and dressing percentage were not different among treatments. Average weight gain and ether extract (EE) in 9-11th control joint were higher (p<0.05) in lambs fed control diet than those fed RCB diets. The substitution of RCB for 50% of control diet exhibited 11.8% reduction in feeding cost for each kg of body weight gain.

• International Commerce and Information Review
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• v.18 no.2
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• pp.85-103
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• 2016

This study deals with a research on Korean American economy and Korean banks operated in California where a large percentage of Korean residents in the U.S. is concentrated. Using date published by U.S. Census and the Federal Deposit Insurance Corporation (FDIC), quantitative analyses have been performed on the asset, employment, market share and other features of selected Korean American financial institutions. Also, each bank's status of financing and asset management are reviewed through the analysis of its balance sheets. The outcome of analysis on the status of Korean American banks are summarized as follows: First, Korean American banks are shown to be growing to become major banks with equivalent scale as mainstream banks. Second, the recently improved fundamentals of Korean American banks are identified. Third, the operational performances of Korean American banks are verified to be similar to the average of Californian banks.

• Information Systems Review
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• v.8 no.3
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• pp.245-259
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• 2006

In order to utilize BSC as an operational tool for communicating strategies across the hierarchies of the organization, a growing number of companies have tried to link BSC processes with other PI tools. Company D has carried out the SEM project to identify the causal structure between innovation activities and performance management in 2005 and 2006. The company synthesizes BSC and 6 Sigma methodologies at the BU level, and the new process made it possible to manage performances and make decision more "realistic" on the basis of information technologies. We expect that this study provide organizations, which have difficulties streamlining the performance management processes at the strategic level and those of operational level, with implications for realizing more "execution-oriented" RTE.

• Journal of Internet Computing and Services
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• v.18 no.1
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• pp.153-160
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• 2017

Due to the endeavors and performances of many IT firms, as well as the government supports, the IT capability of Korea was ranked in the top 8th position by Huawei in 2015. Specifically, as far as the wire & wireless network and Internet speed, Korea has taken pride in possessing the competitive advantage. However, many academic and practical experts began to point out the lack of systematic research management on Internet. The purpose of the study is to identify various research issues on Internet and to verify their appropriateness. In addition, the study examined their recent trends and provided the prospect of the future Internet-related researches. Consequently, the finding indicates that the rigorous endeavors and outcomes for each proposed research issue have been resulted in and will be continued. The study anticipates the growing demands of researches in the fields of future network, multimedia application, big data, artificial intelligence, and Internet security.

• The Korean Journal of Applied Statistics
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• v.27 no.5
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• pp.717-729
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• 2014

Projection pursuit classification tree uses a 1-dimensional projection with the view of the most separating classes in each node. These projection coefficients contain information distinguishing two groups of classes from each other and can be used to calculate the importance measure of classification in each variable. This paper reviews the variable importance measure with increasing interest in line with growing data size. We compared the performances of projection pursuit classification tree with those of classification and regression tree(CART) and random forest. Projection pursuit classification tree are found to produce better performance in most cases, particularly with highly correlated variables. The importance measure of projection pursuit classification tree performs slightly better than the importance measure of random forest.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.6
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• pp.55-62
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• 2015

An importance of infrastructures' protection against crash or blast loading has been an emerging issue as structures are becoming much bigger and population densities in downtown are growing up. However, there exists no such a standard to evaluate the protection performance of construction material itself. Prior to building standards for protection assessment techniques, this study performed gas-gun propelled projectile impact tests with series of contact-type monitoring systems to investigate the applicability of each sensing type. Through the impact tests, failure modes and protection performances of both normal concrete and UHPC (Ultra High Performance Concrete) reinforced by steel fibers were also evaluated. The results showed that LVDT could be applicable for the impact test among contact-type sensors and UHPC with fibers had a remarkable potential to improve protection against impact loading.

• Journal of Digital Convergence
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• v.18 no.8
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• pp.97-102
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• 2020

In this paper, the concept of the diversified cultural tourism industry in Korea and China was summarized and the research direction was suggested. Also, the characteristics and status of the cultural tourism industry were analyzed. As a characteristic of the cultural tourism industry in both Korea and China, it exhibited similar cultural tourism forms such as performances, theme parks, festivals, and museums. Korea had a unique cultural tourism form called Hallyu cultural tourism, and China is also a rare cultural arts complex in Korea. And has developed cultural tourism. The strength of the Korean culture and tourism industry is that it is rich in cultural resources and possesses many assets with cultural contents, and the strength of the Chinese culture and tourism industry is that it has abundant tourism resources and huge economic power. As such, Korea and China with many similarities were found to be a country with high interest and potential in the cultural tourism industry, which is growing into a high value-added industry in the future. In addition, in order to continuously and stably develop the cultural tourism industry, continuous efforts and interests and proper research must be conducted so that the two countries can coexist with each other.