• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1169-1176
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• 2010

The RF front-end for L1/L2 dual-band Global Positioning System(GPS) receiver is presented in this paper. The RF front-end(down-converter) using low IF architecture consists of a wideband low noise amplifier(LNA), a current mode logic(CML) frequency divider and a I/Q down-conversion mixer with a poly-phase filter for image rejection. The current bleeding technique is used in the LNA and mixer to obtain the high gain and solve the head-room problem. The common drain feedback is adopted for low noise amplifier to achieve the wideband input matching without inductors. The fabricated RF front-end using $0.18{\mu}m$ CMOS process shows a gain of 38 dB for L1 and 41 dB for L2 band. The measured IIP3 is -29 dBm in L1 band and -33 dBm in L2 band, The input return loss is less than -10 dB from 50 MHz to 3 GHz. The measured noise figure(NF) is 3.81 dB for L1 band and 3.71 dB for L2 band. The image rejection ratio is 36.5 dB. The chip size of RF front end is $1.2{\times}1.35mm^2$.

• Journal of the Korean Data and Information Science Society
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• v.28 no.6
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• pp.1229-1244
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• 2017

In recent years, as demand for data-based analytical methodologies increases in various fields, optimization methods have been developed to handle them. In particular, various constraints required for problems in statistics and machine learning can be solved by convex optimization. Alternating direction method of multipliers (ADMM) can effectively deal with linear constraints, and it can be effectively used as a parallel optimization algorithm. ADMM is an approximation algorithm that solves complex original problems by dividing and combining the partial problems that are easier to optimize than original problems. It is useful for optimizing non-smooth or composite objective functions. It is widely used in statistical and machine learning because it can systematically construct algorithms based on dual theory and proximal operator. In this paper, we will examine applications of ADMM algorithm in various fields related to statistics, and focus on two major points: (1) splitting strategy of objective function, and (2) role of the proximal operator in explaining the Lagrangian method and its dual problem. In this case, we introduce methodologies that utilize regularization. Simulation results are presented to demonstrate effectiveness of the lasso.

• Korea and Global Affairs
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• v.2 no.1
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• pp.113-136
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• 2018

The purpose of this study is to start from the recognition of the problem of why the sanctions of the international community could not indicate a great effect. In order to find answers to this question, this study focuses on China's aid to North Korea and analyzes the determinants of support for North Korea. Despite a tough international community's sanctions against North Korea, China has taken a dual stance on sanctions and support for North Korea. As for this dual attitude of China, this study approaches the internal and external situation of the support to the North with the rationale for the Two-level game theory. China's sanction against North Korea could be divided into two categories: external factors and domestic factors. These factors include strengthening supremacy in China, checking the US, playing a responsible role in China, securing resources in North Korea, sustaining stable growth in China, maintaining the legitimacy of China's socialist political system, and spreading the Beijing consensus. Based on the analysis of these factors, it could be expected that China's aid for North Korea will be official, informal, or continuous, and it will be difficult for the North to stop supporting North Korea or deteriorating North Korea- China relations.

• Journal of Korea Technology Innovation Society
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• v.18 no.4
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• pp.667-692
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• 2015

The study examined the Korean medicine industry from the perspective of the innovation system theory of each business, while it concentrated on the conflict between traditional Korean medicine and Western medicine, which have a major influence on the innovation system of Korean medicine industry, rather than the innovation system itself. The Korean healthcare system is a dual system of Western and Korean medicine, yet the definitions of Western medical practices and Korean medical practices are ambiguous. Thus the distinction of dual system depends on judicial precedents, and the innovation of Korean medicine has been inhibited due to the excessive emphasis placed on the Western medical practice in both healthcare system and pharmaceutical system. First of all, the usage of most medical devices derived from the development of modern medical engineering is not permitted in the Korean medicine industry, on the basis that most of the medical devices were originated from the Western medicine field. Secondly, new drugs using natural substances, once approved by the drug administration, cannot be prescribed by the Korean medicine industry although they are developed based on Korean medicine. Thirdly, the major safety issues on herbal medicine are about hazardous materials in medicinal herbs and liver toxicity of prescribed herbal medicine. The problem of hazardous materials can be solved by appropriate quality and safety tests in the cultivation and importation process. Whereas the Korean medicine circles points out that the liver toxicity issue is only a unilateral condemnation by the Western medicine circles.

• Journal of vocational education research
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• v.35 no.6
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• pp.113-141
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• 2016

The apprenticeship training is given as a solution of the youth unemployment problem. The apprenticeship is a system that companies hire and instruct trainees and is implemented in various countries. In Korea, there is a Korean work-learning dual system which is managed by the government rather than the company itself. This Study analyzed Germany, Switzerland and Austria's apprenticeship training system and compared common factors of apprenticeship system, a trainer in company and cost-benefit analysis. The result of the study can be shown as follows. First, Germany operates practical training, meanwhile Switzerland and Austria provide a pre-education course before students enter the upper-secondary VET course. Second, Germany and Switzerland give a single type apprenticeship training, whereas Austria runs a modularization system, which enables students to specify their skills and improves clarity. Third, social partners as well as the government, states, companies/schools actively participate in apprenticeship. Fourth, there is a suitable trainer's qualification system in all countries. Finally, Germany and Austria's companies cause larger cost than benefit in apprenticeship. On the other hand, Switzerland gets larger net-benefit than cost. We can give implications to the Korean work-learning dual system based on this study.

• Journal of Preventive Medicine and Public Health
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• v.55 no.3
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• pp.263-272
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• 2022

Objectives: Infections with hepatitis B, C, and D virus (HBV, HCV, and HDV) are a major public health problem and lead to serious complications such as cirrhosis and hepatocellular carcinoma. We aimed to determine the seroprevalence of hepatitis B surface antigen (HBsAg), anti-HCV, anti-HDV immunoglobulin G, alpha-fetoprotein (AFP), and dual and triple hepatitis virus infections in Mongolia. Methods: A total of 2313 participants from urban and rural regions were randomly recruited for this cross-sectional study. A questionnaire was used to identify the risk factors for hepatitis virus infections, and the seromarkers were measured using immunoassay kits. Results: Among all participants, the prevalence of HBV, HCV, and HDV was 15.6%, 36.6%, and 14.3%, respectively. The infection rates were significantly higher in females and participants with a lower education level, rural residence, older age, and a history of blood transfusion. HBV and HCV co-infection was found in 120 (5.2%) participants and HBV, HCV, and HDV triple infection was detected in 67 (2.9%) participants. The prevalence of elevated AFP was 2.7%, 5.5%, and 2.6% higher in participants who were seropositive for HBsAg (p=0.01), anti-HCV (p<0.001), and anti-HDV (p=0.022), respectively. Elevated AFP was more prevalent in participants co-infected with HBV and HCV (5.8%, p=0.023), HBV and HDV (6.0%, p<0.001), and triple-infected with HBV, HCV, and HDV (7.5%) than in uninfected individuals. Conclusions: Nearly half (49.8%) of the study population aged ≥40 years were infected with HBV, HCV, or HDV, and 22.4% had dual or triple infections.

• Journal of radiological science and technology
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• v.35 no.1
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• pp.1-7
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• 2012

Dual Energy X-ray Absorptiometry(DEXA) is commonly used to diagnose Osteoporosis. The errors of DEXA bone density operation are caused by operator, bone mineral density meter, blood testing, patient. We focus on operator error then study about how much influence operator's region of intest(ROI) in bone testing result. During from March to July in 2011. 50 patients ware selected respectively from 30, 40, 50, 60, and 70 age groups who came to Korea University Medical Center(KUMC) for their Osteoporosis treatment. A-test was performed with usually ROI and B-test was performed with most widely ROI. Then, We compare A-test and B-test for find maximum difference of T-score error which occurred operator ROI controlling. Standard deviation of T-score of B-test showed 0.1 higher then A-test in femur neck. Standard deviation of B-test showed 0.2 higher then A-test in Ward's area which in Greater trocanter and Inter trocanter. Standard deviation of B-test showed 0,1 lower then A-test in L-1. Bone density testing about Two hundred patients results are as follow. When operator ROI was changed wider than normal ROI, bone density of femur was measured more higher but bone density of L-spine was measured more lower then normal bone density. That means, sometime DEXA bone density testing result is dependent by operator ROI controlling. This is relevant with the patient's medicine and health insurance, thus, tester always keep the size of ROI for to prevent any problem in the patient.

• Journal of Digital Convergence
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• v.11 no.2
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• pp.235-242
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• 2013

Reputation systems aggregate users' feedback after the completion of a transaction and compute the "reputation" of products, services, or providers, which can assist other users in decision-making in the future. With the rapid growth of online e-Learning content providing services, a suitable reputation system for more credible e-Learning content delivery has become important and is essential if educational content providers are to remain competitive. Most existing reputation systems focus on generating ratings only for user reputation; they fail to consider the reputations of products or services(item reputation). However, it is essential for B2C e-Learning services to have a reliable reputation rating mechanism for items since they offer guidance for decision-making by presenting the ranks or ratings of e-Learning content items. To overcome this problem, we propose a novel collaborative filtering based reputation rating method. Collaborative filtering, one of the most successful recommendation methods, can be used to improve a reputation system. In this method, dual information sources are formed with groups of co-oriented users and expert users and to adapt it to the reputation rating mechanism. We have evaluated its performance experimentally by comparing various reputation systems.

• The Journal of Fisheries Business Administration
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• v.44 no.3
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• pp.47-60
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• 2013

A study on the seamen's demand - supply has been focused on early 1990s, and never studied yet since 2007. Because previous studies related to the seamen are very different in conditions the environments around the fishery recently. It is serious problem that the number of domestic semen are decreasing continually. To depend on foreign seamen because of lacking of domestic seamen should be linked closely with the fishing industry environment in our country. Therefore, this study is limited to domestic seamen. Lacking recent domestic seamen, it is the most likely to rise imbalance between demand - supply in the future. Through medium and long term its analysis based on data, we are willing to discover various political subjects for seamen's welfare, the training of manpower, education, etc. To solve these issues, it can be made institutional changes as follows ; First, it is necessary policy-making related the deteriorating employment situation based on its analysis of medium and long term for seamen. Second, it is necessary to overcome a dual system for its management for seamen. Third, it is necessary to improve problems of statistics data for fishery and build a statistical system for seamen. Also, it will be improved a insurance system under 5 ton and strengthen the function for Korean seamen welfare and employment center and must be urgently countermeasures for the minimal unemployment rate through a content development and management of home page. Finally, it will be supplied reliably seamen to improve a practice system for apprentices according to the international regulations(STCW-F) for fishery students.

• Journal of Korean Academy of Nursing Administration
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• v.5 no.2
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• pp.317-336
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• 1999

Official nursing education of Korea under Japanese rule began in order to make the communication possible among Japanese medical men and Korean patients. It could generate high standard nurses from the beginning. Nurses licensure began in 1914 and the graduates of official nursing schools could get nurses licensure without further test. Official nursing education became the standard of R.N. education. The curriculum emphasized on Japanese and ethics first, and in order to produce nurse, practice second. In 1920 the shortage of nurse became serious problem, so the Japanese colonial authorities set up 5 official nursing school in large scale. In 1922 they revised the relevant laws and regulations to make the nursing licensure pass all over Japanese ruling area. 8-year preliminary education and 2 year curriculum became standard of official nursing education after then. Other nursing schools should satisfy this standard to let their graduate get nurses licensure without further test. Curriculum was revised to satisfy the dual goal of 'good housewife' and 'good nurse'. Every official nursing school tried to raise educational standard Nursing science was specialized and more emphasis was put on the occupational education. From the late 1930s, Japanese desperately needed additional manpower to replenish the dwindling ranks of their military and labor forces. They tried to produce more nurses by increase nursing school. Students had to do wartime work instead of study. Younger students could enter nursing school, and general school could produce R.N. In conclusion, nursing education of Korea under Japanese rule was determined by the official nursing education. The Japanese colonial authorities lead the official nursing education. It made nursing education fixed early and produced high standard R.N. But it made nursing education withdraw in late Japanese rule period. Nursing education of Korea began quite weak in the need of nursing and Korea herself. The weakness became a subject of nursing education of Korea after Japanese rule to produce better R.N..