• Journal of Power Electronics
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• 제14권4호
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• pp.641-648
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• 2014

This paper presents the design considerations and analysis for an interleaved boundary conduction mode power factor correction buck converter. A thorough analysis of the harmonic content of the AC line current is presented to examine the allowable voltage gain (K value) for meeting the EN61000-3-2, Class D standard while maximizing efficiency. The results of the harmonic analysis are used to derive the required value of K and therefore the output voltage necessary to meet the class D requirements for a given AC line voltage. The discussed design consideration and harmonic current analysis are verified on a 300W universal line experimental prototype converter with an 80V output. The measured efficiencies remain above 96% down to 20% of the full load. The input current harmonics also meet the IEC61000-3-2 (class D) standard.

• 한국콘텐츠학회논문지
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• 제18권5호
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• pp.579-591
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• 2018

본 연구의 목적은 초등학생의 체육수업태도와 놀이성이 학교행복감에 미치는 영향을 살펴보는 것이다. 자료 수집을 위해, I 광역시의 5개 초등학교 300명의 초등학생에게 설문지가 배포되었으며, 불성실한 응답 자료를 제외한 278부의 설문지가 자료분석에 사용되었다. 자료분석을 위해, 기술분석, 탐색적요인분석, 상관관계분석, 다중회귀분석이 사용되었다. 상관관계분석결과, 모든 연구변인들은 상호간에 정적인 상관관계를 나타내었다. 다중회귀분석결과, 놀이성의 하위요인인 감정표현성은 학교행복감의 모든 하위요인에 정적인 영향을 미치는 것으로 밝혀졌으며, 놀이성의 신체적 활기요인은 학교행복감의 자기존중감, 낙천주의, 그리고 전반적 학교행복감 요인에 정적인 영향을 미치는 것으로 나타났다. 그리고 놀이성의 정신적 자발성 요인은 교사관계 전반적 학교행복감요인에 정적인 영향을 미치는 것으로 나타났다. 또한 체육수업태도는 학교행복감의 모든 하위요인에 정적인 영향을 미치는 것으로 나타났으며, 표준화회귀계수 분석결과, 체육수업태도가 놀이성에 비해 학교행복감에 미치는 영향이 큰 것으로 나타났다. 본 연구는 초등학생의 체육수업 태도 및 놀이성이 학교행복감에 미치는 영향을 살핀 최초의 국내연구로서 의미가 있으며, 국내 초등학생의 행복감 증진을 위한 실증적 자료를 제시한다는 점에서 의의가 있겠다.

• 전자공학회논문지SC
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• 제38권5호
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• pp.59-69
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• 2001

최근에 디지털 선호처리와 전자부품의 발달로 심음 분식에 관한 많은 연구가 진행되고 있다. 그러나 심음 인식, 특히 심음 한주기 전체에 대한 인식연구는 거의 없다. 본 논문에서 심음 전체 한주기에 대한 새로운 인식 방법을 제안하였다. 먼저 주성분 분석을 이용하여 훈련 셋트로 데이터베이스를 구축한다. 데이터베이스는 새로운 심음입력을 인식하는데 이용된다. 심음은 정상심음, 수축전 심잡음, 수축초기 심잡음, 수축 말기 심잡음, 이완 초기 심잡음, 이완 말기 심잡음， 연속적 심잡음으로 분류된다. 실험결과 새로운 인식 방법은 심음의 특징을 인식하는데 효과적이었다. 최대 인식률은 NO의 경우 71%, PS와 ES의 경우 80%, LS의 경우 78%, ED의 경우 87%, LD의 경우 60%, CM의 경우 20% 이었다. 현재의 결과가 실제적으로 심음을 인식하기에는 충분하지 못하였지만 선음 전체 주기를 대상으로 한 연구라는데 의의가 있으며 더 효과적인 데이터베이스를 구축함으로써 인식률을 개선할 수 있다.

• 대한구순구개열학회지
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• 제14권1_2호
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• pp.1-18
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• 2011

Skeletal malocclusion is the result of abnormal dimension and alignment of each skeletal component. Understanding on these mechanisms may help to elucidate the etiology of skeletal malocclusion and to establish population-oriented treatment plans. Attempts to subdivide the Angle's classification have been performed for Class III malocclusion, while few studies have been conducted for Class II malocclusion despite recent growing interests in Class II malocclusion. 200 adults (88 male, 112 female) with skeletal Class II malocclusion were collected and subdivided using cluster analysis, using the measurements representing the dimension and the alignment of each facial skeletal component. The properties of each cluster was grouped within the subjects and a comparison between the subjects and the control group (38 male, 35 female) with normal occlusion was performed. Six clusters were finally recognized in each male and female groups. The clusters in both genders were mainly characterized by the cranial base alignment, dimension of the posterior cranial base, dimension of the mandibular ramus and the degree of mandibular rotation. The results implicate that active treatment of mandible rather than the nasomaxillary complex may be primarily considered for the correction of Korean Class II skeletal pattern.

• 수산해양교육연구
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• 제25권4호
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• pp.878-890
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• 2013

The purpose of this study is to apply the PEOE class model that can enhance students' scientific creative problem-solving ability and self-directed learning ability in the middle school science subject and analyze the effects of it on students' long- and short-term retention, scientific creative problem-solving ability, and self-directed learning characteristics. And the paper has gained the following results: First, according to the result of analysis through the pre-test, post-test, and delay test to examine the effects of PEOE-based class on learners' long- and short-term retention, it is found to be statistically significant in the significant level of .05. In other words, the class using PEOE influences learners' short-term retention significantly, but it is even more effective in transmitting the concept that students acquire into their long-term memory. Second, according to the result of analysis through the pre-test and post-test to examine the effects of PEOE-based class on learners' scientific creative problem-solving ability, it is found to be statistically significant in the significant level of .05 in general. However, 'elaboration' and 'originality', the subfactors of scientific creative problem-solving ability, do not indicate significant effects. Third, according to the result of analysis through the pre-test and post-test to examine the effects of PEOE-based class on learners' self-directed learning characteristics, it is found to be statistically significant in the significant level of .05 as a whole. However, 'openness' and 'future-oriented self-understanding', the subfactors of self-directed learning characteristics, do not exert significant effects. Based on the above study results, it can be concluded that PEOE-based class is more effective for learners' academic achievement in science, scientific creative problem-solving ability, and self-directed learning characteristics than lecture-method instruction regarding the middle school science unit of 'The Properties of Air and Weather Change'.

• Journal of Microbiology and Biotechnology
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• 제9권3호
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• pp.346-351
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• 1999

Tumor cells may alter the expression of proteins involved in antigen processing and presentation, allowing them to avoid recognition and elimination by cytotoxic T cells. In order to investigate whether the major histocompatibility complex (MHC) class I-mediated antigen processing machinery is preserved in human lung cancer cell lines, we examined the expression of multiple components of the MHC class I antigen processing pathway, including transporter associated with antigen processing (TAP), $\beta_2$-microglobulin, MHC class I molecules, and chaperones which have not been previously examined in this context. Row cytometry analysis showed that the cell surface expression of MHC class I molecules was downregulated in all of the cell lines. While some cell lines showed no detectable expression of MHC class I molecules, pulse-chase experiments showed that MHC class I molecules were synthesized in the other cell lines but not transported from the endoplasmic reticulum to the cell surface. Low or nondetectable levels of TAP1 and/or TAP2 expression were demonstrated by Western blot analysis in all of the cell lines, representing a variety of lung tissue types. In some cases, this was accompanied by loss of tapasin expression. Our findings suggest that downregulation of antigen processing may be one of the strategies used by tumors to escape immune surveillance. This study provides further information for designing the potential therapeutic applications such as immunotherapy and gene therapy against cancers.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제35권4호
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• pp.221-228
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• 2009

The purpose of the study was to investigate the characteristics of the pronunciation of Korean vowels in patients with class III malocclusion. 11 adult male patients with class III malocclusion(mean ages 22.3 years) and four adult males with normal occlusion(mean ages 26.5 years) were selected for the analysis of eight Korean monophthongs /ㅣ, ㅔ, ㅐ, ㅏ, ㅓ, ㅗ, ㅡ, ㅜ/. The values and relationships of F1, F2 and F3 were derived from the stable section of target vowel in each sentence, and the analysis using formant plots and vowel triangles' distance and area was conducted to find the features of two groups' vowel distributions. Consequently, it was identified that the pronunciation of males patients with class III malocclusion showed high values of F1 in the low vowels, high values of F2 in the back vowels, and remarkably low position of /ㅏ/. The vowel triangle suggested that the triangle areas of male patients with class III malocclusion were shown wider vertically and narrower horizontally than those of males with normal occlusion. These characteristics could reflect the structural features of class III malocclusion such as the prognathic mandible, low tongue position, and advancement of back position of the tongue.

• 수산해양교육연구
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• 제24권6호
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• pp.977-988
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• 2012

The purpose of this study was to help teachers increase the level of student's school life satisfaction by comparing between the practical data of a group which have an accordant perception for class teacher's discipline style perceived by between teacher him/herself and student with another group which have a discordant perception for class teacher's discipline style perceived by between teacher him/herself and student. For this study, 1460 second grade special high school students in Pusan were selected. And 1273 students and 56 teachers' questionnaires were used for analysis, while 5 questionnaires went uncompleted. T-test and Multiple Regression Analysis were used for compiling statistics of collected data. The results of this study are as follows: First, perceptions about the teacher's discipline style perceived by between teacher him/herself and student were different. Second, the levels of student's school life satisfactions were different by two group. A group which has an accordant perception for class teacher's discipline style perceived by teacher him/herself and student shows the high level of school life satisfaction than B group which has an discordant perception. Last, class teacher's discipline style which affects the level of student's school life satisfaction was different by the two group. These results suggest that to increase the level of student's school life satisfaction, class teachers have to a mutual understanding first, and then approach their students with different discipline style by the level of their interactive relationship with their students.

• 한국콘텐츠학회논문지
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• 제21권8호
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• pp.271-284
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• 2021

본 연구는 현재 대학에서 진행되고 있는 온라인 토의수업의 활용 실태 및 효과에 대해 탐색하고자 하였다. 이를 위해 서울과 경기지역 총 4개 대학에 재학 중인 대학생을 대상으로 온라인 토의수업의 운영 실제와 그 효과에 관한 인식을 진단하는 설문조사를 실시하였다. 수집된 자료는 SPSS 프로그램을 적용하여 빈도분석, 기술통계분석, 교차분석, F검증, T검증, Scheffe 검증을 사용하여 분석하였다. 연구 결과, 첫째, COVID19 사태 이후 대학에서는 '비실시간 녹화수업'과 '실시간 쌍방향 화상수업' 방식이 주로 진행된 것으로 나타났다. 둘째, 온라인수업 방식에서 '실시간 쌍방향 화상수업'은 '토의수업 선호도'에 정적 영향을 주며 더 의미 있는 것으로 나타났다. 셋째, 온라인 토의수업 참여에 대해 대학생들은 창의사고능력 확대를 위한 기반으로 인식하고 있었으며, 토의방식과 절차에 대한 학습자의 충분한 인지과정을 기반으로 하는 원활한 의사소통과 교류를 통한 강화가 더 도움이 된다는 것을 시사해준다.

• 대한치과교정학회지
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• 제45권3호
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• pp.113-120
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• 2015

Objective: This study compared occlusal contact areas of ideally planned set-up and accomplished final models against the initial in class I and II molar relationships at finishing. Methods: Evaluations were performed for 41 post-orthodontic treatment cases, of which 22 were clinically diagnosed as class I and the remainder were diagnosed as full cusp class II. Class I cases had four first premolars extracted, while class II cases had maxillary first premolars extracted. Occlusal contact areas were measured using a three-dimensional scanner and RapidForm 2004. Independent t-tests were used to validate comparison values between class I and II finishings. Repeated measures analysis of variance was used to compare initial, set up, and final models. Results: Molars from cases in the class I finishing for the set-up model showed significantly greater contact areas than those from class II finishing (p < 0.05). The final model class I finishing showed significantly larger contact areas for the second molars (p < 0.05). The first molars of the class I finishing for the final model showed a tendency to have larger contact areas than those of class II finishing, although the difference was not statistically significant (p = 0.078). Conclusions: In set-up models, posterior occlusal contact was better in class I than in class II finishing. In final models, class I finishing tended to have larger occlusal contact areas than class II finishing.