• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.2
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• pp.153-163
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• 2010

In this paper a frequency response analysis using Krylov subspace-based model reduction and its design sensitivity analysis with respect to design variables are presented. Since the frequency response and its design sensitivity information are necessary for a gradient-based optimization, problems of high computational cost and resource may occur in the case that frequency response of a large sized finite element model is involved in the optimization iterations. In the suggested method model order reduction of finite element models are used to calculate both frequency response and frequency response sensitivity, therefore one can maximize the speed of numerical computation for the frequency response and its design sensitivity. As numerical examples, a semi-monocoque shell and an array-type $4{\times}4$ MEMS resonator are adopted to show the accuracy and efficiency of the suggested approach in calculating the FRF and its design sensitivity. The frequency response sensitivity through the model reduction shows a great time reduction in numerical computation and a good agreement with that from the initial full finite element model.

• Journal of the Korea Concrete Institute
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• v.22 no.6
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• pp.777-786
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• 2010

This paper examines the flexural behavior of full-scale prestressed concrete girders that were constructed of steel fiber reinforced ultra high performance concrete (UHPC). This study is designed to provide more information about the bending characteristics of UHPC girders in order to establish a reasonable prediction model for flexural resistance and deflection for future structural design codes. Short steel fibers have been introduced into prestressed concrete T-girders in order to study their effects under flexural loads. Round straight high strength steel fibers were used at volume fraction of 2%. The girders were cast using 150~190 MPa steel fiber reinforced UHPC and were designed to assess the ability of steel fiber reinforced UHPC to carry flexural loads in prestressed girders. The experimental results show that steel fiber reinforced UHPC enhances the cracking behavior and ductility of beams. Moreover, when ultimate failure did occur, the failure of girders composed of steel fiber reinforced UHPC was observed to be precipitated by the pullout of steel fibers that were bridging tension cracks in the concrete. Flexural failure of girders occurred when the UHPC at a particular cross section began to lose tensile capacity due to steel fiber pullout. In addition, it was determined that the level of prestressing force influenced the ultimate load capacity.

• Journal of Korean Society of Forest Science
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• v.101 no.2
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• pp.185-194
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• 2012

The purpose of this contribution is to develop the framework of a methodology for identifying potential errors in georeferencing and in an application of it using specimens of Ox-Knee, Achyranthes bidentata Blume in Korea. At infraspecific level, uncertainty of identification showed that 41% of A. bidentata var. japonica and 28% of var. bidentata were misidentified, suggesting that the uncertainty level was independent of the reliability of experts' identification. For georeference specimen records, 71 specimens out of total 303 were selected and utilized as occurrence data: Uncertainty was 32.4 km at maximum and was 0.1297 km at minimum (mean = 4,055 m, s.d. = 5,772 m). Var. japonica is common throughout most of the southeastern Korea and west coastal areas, while var. bidentata has been found as far north as Gyeonggi and Gangwon provinces. We modelled the potential distribution of two varieties using Bioclim approach in Korea based on several environmental factors. Our results indicated the most important region for var. japonica lies the west coast ranges and southern area, while for Chungcheongnam-do of potential high diversity occurs for var. bidentata. This study shows that the major factors to determine the distribution patterns of two varieties were thermal factors, rather than precipitation. The Bioclim model using geocode and georeferencing data makes the information increasingly useful and reliable. To improve data quality, it requires full management from data collection to final databases including data cleaning.

• Journal of the Korean Home Economics Association
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• v.17 no.4
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• pp.117-127
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• 1979

This study attempts to shed additional light on the national diffusion process and interaction of welfare services for children and mothers. The central hypothesis examined is the following : In general, the implant of social welfare system is first considered on the characteristics of their own socio-economics , and diffusion prodess of welfare services tends to occur faster in countries with open sicieties than in countries where entry barriers are high and society ranking rigid. The scope of the study is limited in several ways. Attention is concentrated on the agency of woman in the belief that an in-depth case study of one field can yield more insight than a less detailed investigation embracing a number of social welfare systems. The angency of woman is selected for several reasons. a) It is important the agency of woman alone produce more effective than services affecting both the child welfare and women's libertion bradually. Moreover, these services will form the heart of mother's welfare. b) The services of women's agency is gradually wide spread, since a role of government is still negligible before a full realization of economic income. c) The services of women agency is a prime example of a social welfare. d) statistical data and other information are more readily available. One of major findings of our study is the existence of the barriers inhibiting child welfare form " motherhood cult". Despite all the distinct advantages for mother and child , social attitudes appear to be some resistant on child welfare system among men and women even the agenices of women. What is surprised is the extent of the awareness that strategies of women's agency to liberate woman and to increate activities of women involve the strategies to liberate child. The conviction that solving application problems for child welfare in line with the activities of agency by women offer greater freedom and more advantage to mother are not apparent on the data collected from 18 of multi-functional agencies in our country. there are little sign that such agencies cooperate toward attainment of common goals. The intensive early focus of the movement on consciousness raising is a necessary beginning and such efforts by women's organizations would help both in the continuous evolution of women and child. Some of the agencies offer a variety of services to women and children, others are specialized in that they offer fewer services or even only one. Social welfare agenices giving service to children and their families are identified by various names usually women service and child welfare from govern , mental agency and voluntary public agency to foreign aided. What is totally missing , however, is an integrated synthesis of child welfare program Through women's agency. Social changes to occur, but delineation of appropriate and comprehensive social policy is also necessary at this point at this point since efforts, social changes and polices must be well coordianted and focused, as well as mutually supprotive and reinforcing.

• Korean Journal of Health Education and Promotion
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• v.9 no.2
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• pp.72-88
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• 1992

The purpose of the present study was to identify the charateristics and social activities of graduates from a School of Public Health in Seoul and to provide basic information which might contribute to the improvement of new established Schools of Public Health in Korea. The Subjects were composed of 199 persons who graduated from a School of Public Health in Seoul during the period of 1987 through 1989. The response rate was 59.8% (199 graduates). The survey was conducted from December 1st 1991 to the end of February 1992 with a self-administered questionnaire by mail. Descriptive analysis with Chi-square test was employed for analysis. The major results were as follows : 1. 462% of students were the group aged 24-28 and 76.5% of them were married at the time of entrance to the School. 2. The major motives to come to the School were continuous study in a graduate school(41.2%), and strengthening of job opportunities(35.3%). 3. The major expectation of students were to acquire new professional knowledge(31.9%), to improve present work performance(22.7%) and to become an educator(22.7%). 4. 84.9% of students had some kinds of expectation at the entrance to the School, but only 48.8% of them met their expectations they had had. 5. The most preferred subjects were Health Statistics and Epidemiology in order. 6. 59.7% of students insisted that a professor should advise 4-5 students in maximum for a thesis. 7. Students suggested that the candidate for scholarship should he selected from those who had earned high credits in the previous semester(33.6%), who were low economic status(31.l%) or who were recommended by academic adviser(24.4%). 8. 57.1% of students were positive in utilizing their major subjects studied in their current works. 9. Students expressed that if the School of Public Health is to be further developed full-time professors should be added (37.9%) and excellent students be secured (33.6%). 10. After graduation from the school, some of the respondents changed their job placement, the number of persons working in research institutes increased from 6 to 14 persons, those working in educational institutes from 16 to 35, and Ministry of Health and Social Affairs and its affiliated organization from 10 to 13.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.4
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• pp.1-9
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• 2009

In this paper, a small area 12-bit 300MSPS CMOS Digital-to-Analog Converter(DAC) is proposed for display systems. The architecture of the DAC is based on a current steering 6+6 segmented type, which reduces non-linearity error and other secondary effects. In order to improve the linearity and glitch noise, an analog current cell using monitoring bias circuit is designed. For the purpose of reducing chip area and power dissipation, furthermore, a noble self-clocked switching logic is proposed. To verify the performance, it is fabricated with $0.13{\mu}m$ thick-gate 1-poly 6-metal N-well Samsung CMOS technology. The effective chip area is $0.26mm^2$ ($510{\mu}m{\times}510{\mu}m$) with 100mW power consumption. The measured INL (Integrated Non Linearity) and DNL (Differential Non Linearity) are within ${\pm}3LSB$ and ${\pm}1LSB$, respectively. The measured SFDR is about 70dB, when the input frequency is 15MHz at 300MHz clock frequency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.11 s.102
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• pp.1075-1085
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• 2005

The purpose of this paper is to design the architecture for synchronization of MB-OFDM UWB system that is being processed the standardization for Alt-PHY of WPAN(Wireless Personal Area Network) at IEEE802.15.3a and to analyze the implementation loss due to 4 parallel synchronization architecture for design or link margin. First an overview of the MB-OFDM UWB system based on IEEE802.15.3a Alt-PHY standard is described. The effects of non-ideal transmission conditions of the MB-OFDM UWB system including carrier frequency offset and sampling clock offset are analyzed to design a full digital architecture for synchronization. The synchronization architecture using 4-parallel structure is then proposed to consider the VLSI implementation including algorithms for carrier frequency offset and sampling clock offset to minimize the effects of synchronization errors. The overall performance degradation due to the proposed synchronization architecture is simulated to be with maximum 3.08 dB of the ideal receiver in maximum carrier frequency offset and sampling clock offset tolerance fir MB-OFDM UWB system.

• Journal of the Korean Society of Costume
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• v.29
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• pp.171-182
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• 1996

This thesis is concerned with the study of the court attire the typical attire of the ju-dicial world in a point of time that more than 100 years have passed since the introduction of the modern judical system. In recognition of the fact that compiled data of the official uni-form or attire in Korea are insufficient this study placed its signification on the provision of information with focus on attire. As a result of studying court attire in Korea the conclusion was made as follows: Firstly Official attires in Yi Dynasty were divided by wearing embroidered insignia on the breast and the back of an official robe ac-cordint to court rank as well as by wearing Sa-mo in wadded clothes of Dan-ryeong and attaching all sorts of appurtenances including bands and shoes The Minister of Justice was equipped with Ho-pyo Dae-sa-heon equipped with Hae-chi the mayor of Seoul equipped with Un-an In the era of the Kng Young-jo the minister of Justice had no change in its of-ficial robe but the mayer(Pan-yun) of Seoul (Han-sung-bu) had Un-an(wild geese in clouds) changed into Un-hak In the King Ko-jog era the minister of Justice had Ho-pyo changed into Ssang-ho and the mayor of Seoul had Un-hak changed into Ssng-hak on embroideved insignia on the breast and back of an official robe. Laws and regulations concerning court attire began with the In-judgement Full-dress Uni-form Requlation for official-level Clerical Staff below the ordinary staff the Issue No. 14 of the Royal Ordinance in 1906 provided as $\ulcorner$the matter cincerning the Dress Regulation of the Tribunal staff of the Cho-sun Government-General$\lrcorner$the Issue No. 222 of the Royal Ordi-nance in 1911 and changed into$\ulcorner$the Regu-lation on the Dress of Judge Prosecutor At-torney and Law Count Clerk$\lrcorner$the Issue No. 12 of the Supreme Court Rule in 1953 affter the establishment of Korean Government since emancipation from the Japanese rule and into $\ulcorner$the Regulation concerning the Court Attire of Judge and law Court Clerical Staff$\lrcorner$the Issue No. 516 of the Supreme Court Rule in 1966. The judicial system in Korea is the system introduced from the foreign country rather than autogenously developed. And it came to pass through the Japanese colonial period it the beginning that it took root in Korea n was not stabilized in harmony with our native tradition. Accordingly the attare regulation in the judicial system took root in our society by accepting the Japanese attire regulation as it was and judical officials have come to wear the count attire similar to that of the Japanese imperialist era due to its influence though Korean independent goverment was established together with liberation form the Japanese rule. The more regrettable thing is that the current court attire has maintained the form greatly influenced by the U. S. court attire. Fortunately as the judicial circles have recently raised their voices for change in the court attire it has been told that the forma-tion of a meeting for a new court attire has been under way. The birth of the court attire into Which our tradition is sublimated is expected. This study end up with thinking that the must Korean thing is the most global thing in this era that people in the world are clamoring for globalization.

• Communications of Mathematical Education
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• v.34 no.1
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• pp.1-15
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• 2020

Today's healthcare, intelligent robots, smart home systems, and car sharing are already innovating with cutting-edge information and communication technologies such as Artificial Intelligence (AI), the Internet of Things, the Internet of Intelligent Things, and Big data. It is deeply affecting our lives. In the factory, robots have been working for humans more than several decades (FA, OA), AI doctors are also working in hospitals (Dr. Watson), AI speakers (Giga Genie) and AI assistants (Siri, Bixby, Google Assistant) are working to improve Natural Language Process. Now, in order to understand AI, knowledge of mathematics becomes essential, not a choice. Thus, mathematicians have been given a role in explaining such mathematics that make these things possible behind AI. Therefore, the authors wrote a textbook 'Basic Mathematics for Artificial Intelligence' by arranging the mathematics concepts and tools needed to understand AI and machine learning in one or two semesters, and organized lectures for undergraduate and graduate students of various majors to explore careers in artificial intelligence. In this paper, we share our experience of conducting this class with the full contents in http://matrix.skku.ac.kr/math4ai/.

• Investigative Magnetic Resonance Imaging
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• v.21 no.4
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• pp.233-241
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• 2017

Purpose: To report on the current practices in breast magnetic resonance imaging (MRI) in Korea. Materials and Methods: We invited the 68 members of the Korean Society of Breast Imaging who were working in hospitals with available breast MRI to participate in a survey on how they performed and interpreted breast MRI. We asked one member from each hospital to respond to the survey. A total of 22 surveys from 22 hospitals were analyzed. Results: Out of 22 hospitals, 13 (59.1%) performed at least 300 breast MRI examinations per year, and 5 out of 22 (22.7%) performed > 1200 per year. Out of 31 machines, 14 (45.2%) machines were 1.5-T scanners and 17 (54.8%) were 3.0-T scanners. All hospitals did contrast-enhanced breast MRI. Full-time breast radiologists supervised the performance and interpreted breast MRI in 19 of 22 (86.4%) of hospitals. All hospitals used BI-RADS for MRI interpretation. For computer-aided detection (CAD), 13 (59.1%) hospitals sometimes or always use it and 9 (40.9%) hospitals did not use CAD. Two (9.1%) and twelve (54.5%) hospitals never and rarely interpreted breast MRI without correlating the mammography or ultrasound, respectively. The majority of respondents rarely (13/21, 61.9%) or never (5/21, 23.8%) interpreted breast MRI performed at an outside facility. Of the hospitals performing contrast-enhanced examinations, 15 of 22 (68.2%) did not perform MRI-guided interventional procedures. Conclusion: Breast MRI is extensively performed in Korea. The indication and practical patterns are diverse. The information from this survey would provide the basis for the development of Korean breast MRI practice guidelines.