• The Transactions of the Korea Information Processing Society
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• v.6 no.11
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• pp.3116-3123
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• 1999

Current disk systems are generally designed to reduce read traffic more effectively. Hence, write traffic of the I/O workload could potentially become a bottleneck of the disk system performance. In order to overcome this problem without much cost, this paper presents using outermost-zone track of multi-zoned recording disk as a secondary disk cache. The proposed disk cache improves the disk system performance by following exploitations: speed difference between block transfer and track transfer, difference in transfer rate between outermost-zone tracks and inner tracks, reduction in the seek time caused by decreasing the number of disk cache tracks, and idle period during burst accesses. In addition, it does not waste the disk space because it allocates the caching space by the cylinder unit. The simulation results show that the proposed system improves 2.54∼3.11 times better in terms of average response time for write operations than existing disk systems..

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.4
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• pp.279-285
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• 2020

An open-end winding (OEW) permanent magnet synchronous motor with dual inverters can synthesize large voltages for a motor with the same DC link voltage. This ability has the advantage of reducing the use of DC/DC boost converters or high voltage batteries. However, zero-sequence voltage (ZSV), which is caused by the difference in the combined voltage between the primary and secondary inverters, can generate a zero-sequence current (ZSC) that increases system losses. Among the methods for eliminating this phenomenon, combining voltage vector eliminated ZSV cannot be accomplished by the conventional Pulse Width Modulation(PWM) method. In this study, a PWM carrier generation method using functionalization to generate a switching pattern to suppress ZSC is proposed and applied to analyze the control influence of the center-zero vector in the switching sequence about the current ripple.

• Hwankyungkyoyuk
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• v.11 no.2
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• pp.1-13
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• 1998

The purpose of this study is to investigate thel present situation and to analyze the needs and problems of the $\ulcorner$Environment$\lrcorner$ subject in secondary school of the current 6th curriculum in Korea and to indicate the directions of improvement environmental education. The first step of this research was to review the related literature and the result indicated that the number of secondary schools that selected $\ulcorner$environment$\lrcorner$ subject and the teachers who have $\ulcorner$environment$\lrcorner$ certification of a second-major has increased yearly but it shows much difference by regions. The second step was questionnaire surveys on 60 $\ulcorner$Environment$\lrcorner$ teachers in secondary school. According to the survey, 65% of teachers are not certificated and 50% of teachers have no self-confidence of teaching. And most of teachers thought it was difficult to select the modules out of textbook and teachers had difficulties such as the lack of appropriate reference materials and instructive experience of their own instructive experience of active researches. The third step was the questionnaire survey on a students group(606) learning the $\ulcorner$environment$\lrcorner$ subject and a students group(621) without the $\ulcorner$environment$\lrcorner$ subject in secondary school. The group learning $\ulcorner$environment$\lrcorner$ subject showed significantly higher scores than those of the group without $\ulcorner$environment$\lrcorner$ subject in most items. And among the students having $\ulcorner$environment$\lrcorner$ subject, the first year students achieved the highest score, and it revealed that the teaching was most effective to them. The suggestions based on the results of this study are as follows. First, the uncertifiable teachers currently teaching $\ulcorner$environment$\lrcorner$ subject should be given priority to the second-major certificate training program ; which are diverse in contents according to differences of majors and levels. Second, specific and practical re-training programs for the certificated teachers teaching the subject are needed. Third, considerable and continual adjustment of the textbook yearly is required in addition to regular curriculum amendment. Fourth, the more efficient and actual teaching.learning methods of $\ulcorner$environment$\lrcorner$ subject education that can attract students' interest must be developed. Fifth, it is most desirable to have first year students select the subject.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.6
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• pp.313-316
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• 2006

A method for evaluation of the linearity of both the ratio error and phase angle error in the current transformer(CT) comparison measurement equipment has been developed by employing the standard resistors with negligible AC-DC resistance difference less than $10^{-5}$. The non-reactive standard resistors for the linearity check of the system are used as the external burden connected with the secondary of CT under test. These burdens consist of nine standard resistors, with the nominal resistance of $0.01{\Omega},\;0.1{\Omega},\;0.2{\Omega},\;0.4{\Omega},\;0.6{\Omega},\;1{\Omega},\;2{\Omega},\;4{\Omega}$, and $10{\Omega}$. For linearity check, the developed method has been applied in the CT comparison measurement equipment belonging to the industry.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.2
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• pp.238-244
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• 2010

In this paper, we studied electrical characteristics of internal converter type of LED lamps for road and street lighting. We surveyed electro-technical regulations and KS(Korean industrial standards) about LED luminairs. Waveforms of voltage and current, thermal distributions, insulation resistances between live parts and exposed conductive parts, and flame test of cover of LED lamps were experimented and analyzed. In regulations, insulation resistance between live conductors and exposed conductive parts should be greater than $0.2M{\Omega}$ in case nominal voltage of wiring is 220V. In KS codes, the value of insulation resistance should be greater than $2M{\Omega}$ while applying DC 500V or DC 100V. In the result of this study, waveforms of primary voltage and current were distorted. There was difference in waveforms of secondary voltage and current according to composition of converter. Mostly, insulation resistances were measured high more than regulation and code value but some measured points were measured badly($0.0M{\Omega}$). Cover of LED lamps was ignited easily. We expect that the results of this study would be helpful for revision of regulations and national codes for the electrical safety of LED road and street lighting.

• The Mathematical Education
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• v.44 no.4 s.111
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• pp.509-524
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• 2005

The purpose of this study is to investigate the current state of the contents of the mathematics education that are implemented for 3-10 grade students in Korea. To satisfy the purpose of the study, we conducted a nationwide questionnaire to get opinions from students on the relevance of the mathematics curriculum. 4,158 elementary school students, 4,571 middle school students, and 1,653 high school students participated in this survey. Many students feel that the quantity is relevant, so the requirement of reduction in quantity is a little. Also secondary students feel that mathematics is difficult and this condition becomes more serious in proportion as grade. Finally we noticed the difference between sexes, grades, and tracks of studying in every question.

• Korean Journal of Health Education and Promotion
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• v.32 no.2
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• pp.15-26
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• 2015

Objectives: This study performed to analyze general characteristics, environmental factors, and health promoting lifestyle by smoking behavior among university students. Methods: In 2011, interview survey was conducted with 700 Korean students of university and college in located 7 metropolitan cities and the biggest province (Gyeonggido). To examine the factors related to smoking behavior, it collected environmental factors, health promoting lifestyle, and mental health. Multiple logistic regression analysis for survey data identified the difference of smoking behavior. Results: The 20.4% of university students was current smoker. Smoking rate of male was higher than that of female. The university students residing in Seoul and surrounding areas were less likely to have smoking behavior than them residing in local areas. In multiple regression models, difference by gender, academic year, college level, college type, region, secondary smoking exposure time, health status, monthly drinking, alcohol use disorder, and eating breakfast remained significantly (p<0.01, p<0.05). Conclusion: Future efforts should be focused on association between health risk factors and environment factors in physical, mental, and social aspects. To achieve this, we will need to provide the integrated health promotion program to decrease smoking problems of university students.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.1
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• pp.79-87
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• 2022

Recently, as the awareness of the necessity of entrepreneurship education has spread in secondary education, the competency of educators in the field of education has become more important. This study tried to derive the priority of education needs by exploring the competency of educators to practice entrepreneurship education and the result from analysis of the difference in importance and performance. For conducting the analysis, this study conceptualized entrepreneurship education competency based on the TPACK (Technological Pedagogical Content Knowledge) model and developed a questionnaires to measure those competencies. Using TPACK and developed questionnaires, a survey was conducted on 217 secondary school teachers who were interested in entrepreneurship education, and derived the difference between importance-level and current-level was analyzed with a t-test. As a result of the study, for all sub-factors of TPACK, the mean of importance-level was higher than the mean of current-level, indicating that educational prescription was required. Also, as a result of analysis of Borich's requirements and The Locus for Focus Model, it was found that the factor with the highest priority in education was CK(Content Knowledge). Based on the results of study, implications for strengthening competencies for entrepreneurship educators were derived.

• Journal of Internet Computing and Services
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• v.16 no.2
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• pp.117-125
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• 2015

The information about protein structure gives the clues for the function of protein. It is needed for the improvement for the efficacy and fast development of protein drugs. So, the studies visualizing the structure of protein effectively increase. Most studies of visualization focus on the structural prediction for protein or the improvement on the rendering speed. However, studies of information delivery depending on the form of protein visualization are very limited. The major objective of this study is to analyze the information representation goodness-of-fit for the patterns of the hybrid visualization with primary and secondary structures of protein. Those hybrid visualizations included the patterns which updated current representative visualization services, Chimera, PDB and Cn3D. Information factor to analyze information representation goodness-of-fit is assorted by protein primary structure, secondary protein structure, the location of amino acid and ratio information about protein secondary structure, based on the result of subject-analysis. Subject is the group of experts who are involved in protein drug development over 5 years. The result of this study shows the meaningful difference in the information representation goodness-of-fit by the patterns of hybrid visualization and proves the difference in the information by the pattern of visualization.

• Journal of the Korean Society of Safety
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• v.38 no.5
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• pp.1-7
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• 2023

This study analyzes the operational characteristics of 311 aged and non-aged residual current circuit breakers (RCCBs) in low-voltage consumer contexts. It investigates the influence of external temperature and harmonics based on the rated current multiples. To simulate temperature variations, a convectional oven was used around the circuit breakers. Additionally, the generation of harmonic reference signals and data measurement for overcurrent experiments were conducted using NI SCXI, myDAQ, and LabVIEW. An observation revealed that as the ambient temperature increased, the operating time of RCCBs decreased in the time delay region. This was attributed to the faster response or bending of the bimetal, which is the tripping element. However, aged RCCBs encountered challenges with tripping outside the protective curve. The operating time of the circuit breakers exhibited an acceleration influenced by the order and content of harmonic currents, potentially leading to malfunctions. Aged RCCBs demonstrated faster operating times than their non-aged counterparts. However, the difference in operating time varied based on the manufacturer's and operating environment of the RCCBs. Frequent malfunctions of RCCBs can result in power outages. In cases where these circuit breakers fail to operate, they can lead to secondary damages, including electrical fires and shocks. Consequently, it is imperative to consider the operating environment of RCCBs and provide appropriate replacement cycles to mitigate these risks.