• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2017년도 추계학술발표회
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• pp.41-41
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• 2017

• Safety and Health at Work
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• 제4권2호
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• pp.111-116
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• 2013

Background: The aim of this study was to evaluate the quality of the Second Korean Working Conditions Survey (KWCS), focusing on its validity and reliability. Methods: The external validity was evaluated by the assessment of sampling procedures and the response rate, in order to investigate the representativeness of the sample. The content validity was evaluated by the assessment of the development of the questionnaire, and the consistency of questions for the selected construct. The test-retest method was used to evaluate the reliability by means of a phone call survey of 30% of the respondents, who were randomly selected. The respondents' satisfaction regarding the survey procedures and interview time were analyzed to evaluate the quality of survey data. Results: The external validity was assured by an acceptable sampling procedure, rigid multi-stage stratified cluster random sampling. The content validity was also guaranteed by a reasonable procedure for the development of the questionnaire with a pretest. The internal consistency of the questions for work autonomy was maintained, with 0.738 of Cronbach's alpha. The response rate of 36% was lower than that of the European Working Conditions Survey (EWCS), with a contact rate of 66%, compared to 76% for the EWCS. The matching rates of the five retested questions were more than 98% reliable. Conclusion: The quality of the second KWCS was assured by the high external and content validity and reliability. The rigid sampling procedure and development of the questionnaire contributed to quality assurance. The high level of reliability may be guaranteed by the sophisticated field survey procedures and the development of a technical manual for interviewers. The technical strategies for a high response rate should be developed for future surveys.

• 한국대기환경학회지
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• 제32권5호
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• pp.513-525
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• 2016

To propose an effective ensemble methods in predicting $PM_{10}$ concentration, six experiments were designed by different ensemble average methods (e.g., non-weighted, single weighted, and cluster weighted methods). The single weighted method was calculated the weighted value using both multiple regression analysis and singular value decomposition and the cluster weighted method was estimated the weighted value based on temperature, relative humidity, and wind component using multiple regression analysis. The effects of ensemble average methods were significantly better in weighted average than non-weight. The results of ensemble experiments using weighted average methods were distinguished according to methods calculating the weighted value. The single weighted average method using multiple regression analysis showed the highest accuracy for hourly $PM_{10}$ concentration, and the cluster weighted average method based on relative humidity showed the highest accuracy for daily mean $PM_{10}$ concentration. However, the result of ensemble spread analysis showed better reliability in the single weighted average method than the cluster weighted average method based on relative humidity. Thus, the single weighted average method was the most effective method in this study case.

• 한국콘텐츠학회논문지
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• 제12권7호
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• pp.425-436
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• 2012

본 연구는 국내 주요 항공사 승무원을 대상으로 업무 특성상 일시적 해외 체류 시 라이프 스타일과 여가유형을 조사하는 것을 목표로 하고 있다. 본 연구에서는 선행연구를 바탕으로, 객실승무원의 근무 실정에 맞는 라이프스타일과 여가활동 내용을 발췌하여 설문항목을 작성하였다. 분석방법은 수집된 데이터를 바탕으로 내적일관성을 확인하는 신뢰도 분석과 요인분석을 실시하였으며, 라이프스타일은 문화체험 지향형, 성공 추구형, 사교성 지향형, 인간다움 추구형, 유행 추구형, 쇼핑 선호형, 건강지향형의 7개 요인이 추출되었다. 또한 여가유형은 휴식형, 스포츠형, 관광활동형의 3개 요인이 추출되었다. 라이프스타일에서 추출된 요인들을 군집 분석 한 결과, 군집1은 소극적 라이프스타일 형, 군집2는 적극적 라이프스타일 형, 군집3은 자아만족 라이프스타일 형으로 분석되었다. 항공사 객실승무원의 라이프스타일 유형분석은 직장인의 짧은 해외 출장 시 여가시간을 잘 활용할 수 있는 근간을 제시할 수 있을 것이다.

• 한국산학기술학회논문지
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• 제20권11호
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• pp.1-6
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• 2019

실시간 전송을 위한 많은 멀티미디어 응용들은 멀티캐스트로 전송하는 것이 효율적이다. 멀티캐스트 전송에서는 전송의 신뢰성을 높이기 위하여 네트워크 상태에 따른 멀티캐스트 그룹관리 방법과 손실된 패킷을 복구하기 위한 방법이 중요하다. 본 논문에서는 대규모 멀티캐스트 그룹에서 손실된 패킷을 효율적으로 복구하기 위한 방법을 제안한다. 제안 방법에서는 손실된 패킷을 복구하기 위하여 멀티캐스트 도메인들을 복구 클러스터(RC:Recovery Cluster, 이하 RC)로 구성하였다. 많은 멀티캐스트 응용에서는 손실된 패킷을 복구하기 위하여 송신자에게 재전송을 요청한다. 이런 방법에서는 재전송에 따른 패킷 지연시간이 증가하고 요청 메시지를 처리하기 위한 오버헤드가 발생한다. 제안방법에서는 이런 문제점을 개선하기 위하여 RC를 이용하였다. RC는 많은 MD로 구성되고, MD에는 오버레이 멀티캐스트 송신자와 클러스터 호스트(CH:Cluster Host, 이하 CH)들이 있다. CH들을 이용한 패킷 복구를 위하여 메시지를 블록으로 분할하고, 하나의 블록을 다시 여러 세그먼트로 분할한다. 패킷 손실이 발생하면 CH들은 실시간으로 정보를 공유하고 세그먼트 정보를 통하여 손실된 세그먼트들을 동시에 복구하도록 한다. 시뮬레이션 결과는 제안방법이 기존방법보다 패킷 복구비율이 약 50% 향상되었음을 보여준다.

• 한국조리학회지
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• 제18권4호
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• pp.47-58
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• 2012

본 연구는 부산지역 K대학교 학생들을 대상으로 식생활 라이프스타일유형에 따른 군집을 도출하고 각 집단과 외식선택속성과 비만도와의 차이를 고찰하고자 연구를 진행하였다. 연구의 목적을 달성하기 위하여 통계프로그램 PASW Statistic 18.0(Predictive Analytics Software)을 이용하여 빈도분석, 요인분석 및 신뢰도분석, t-test, ${\chi}^2$-test, 비 계층적 군집분석과 ANOVA을 실시하였다. 남자 대학생들의 평균키는 175.59 cm, 체중은 69.53kg이고, 여자 대학생들의 평균키는 162.81 cm, 체중은 53.42kg으로 나타내었다. 남학생 체질량지수를 저체중이 1.7%, 정상체중은 64.6%, 과체중 19.7%이고, 비만은 14.0%로 나타났다. 여학생 체질량지수는 저체중이 22.9%. 정상체중은 62.7%, 과체중이 8.5%, 비만은 5.9%를 나타내었다. 식생활라이프스타일 항목은 건강추구, 안전성추구, 분위기추구, 미각추구, 서양음식추구요인으로 추출되었고, 외식선택속성은 음식의 질과 서비스, 합리적인가격, 접근성과 분위기, 먹어본 경험 요인으로 추출되었다. 식생활라이프스타일은 군집1은 [식생활 무관심형 집단] 군집2는 [건강지향형 집단] 군집3은 [건강무관심형 집단]으로 군집 명을 부여하였다. 식생활라이프스타일 군집과 외식선택속성 요인간의 차이분석에서 군집1은 먹어본 경험에서 높은 평균값을 나타내었고, 군집2는 음식과 서비스의 질에서 높은 평균값을 나타내었고, 군집3은 접근선과 이미지에서 높은 평균값을 나타내었다.

• 디지털산업정보학회논문지
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• 제11권3호
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• pp.69-77
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• 2015

MANET is composed of only the mobile nodes have a limited transmission range. The dynamic topology by the frequent movement of nodes makes routing difficult and is also cause exposed to security vulnerabilities. In this paper, we propose the security routing technique consisted of mechanism of two steps in order to respond effectively to attack by the modification of the routing information and transmit secure data. The hierarchical structure is used and the authentication node that issues the key of the nodes within each cluster is elected in this proposed method. The authentication node manages key issues and issued information for encrypting the routing information from the source node. The reliability value for each node is managed to routing trust table in order to secure data transmission. In the first step, the route discovery is performed using this after the routing information is encrypted using the key issued by the authentication node. In the second step, the average reliability value of the node in the found path is calculated. And the safety of the data transmission is improved after the average reliability value selects the highest path. The improved performance of the proposed method in this paper was confirmed through comparative experiments with CBSR and SEER. It was confirmed a better performance in the transmission delay, the amount of the control packet, and the packet transmission success ratio.

• 한국의류산업학회지
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• 제10권6호
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• pp.890-899
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• 2008

This study aimed to identify the effects of service quality of internet shopping malls on consumer satisfaction and word of mouth intention. The data were obtained from questionnaires completed by 345 people aged between 20 and 39 living in Busan. The SPSS package was used for data analysis whose methods included factor analysis, ANOVA, cluster analysis and regression analysis. The results of this study were as follows: First, the service quality factors were determined to be reliability, diversity, convenience, accuracy & communicability. Differences among the groups divided by service quality factors were found to be meaningful in consumer satisfaction and word of mouth intention. Second, reliability, diversity, convenience & accuracy significantly affected consumer satisfaction, however all the service quality factors significantly effected word of mouth intention. Finally, consumer satisfaction, reliability, diversity, accuracy & communicability had an significant effect on word of mouth intention. It would be helpful for the managers of internet shopping malls that consumers can be satisfied with right fashion products and efficient inter-communication based on trustfulness in the long-term relationship.

• Journal of Power Electronics
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• 제14권5호
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• pp.946-956
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• 2014

Cascaded H-Bridge (CHB) converters can be directly connected to medium-voltage grids without using transformers and they possess the advantages of large capacity and low harmonics. They are significant tools for providing grid connections in large-capacity renewable energy systems. However, the reliability of a grid-connected CHB converter can be seriously influenced by the number of power switching devices that exist in the structure. This paper proposes a fault-tolerant control strategy based on double zero-sequence voltage injection and DC voltage optimization to improve the reliability of star-connected CHB converters after one or more power units have been bypassed. By injecting double zero-sequence voltages into each phase cluster, the DC voltages of the healthy units can be rapidly balanced after the faulty units are bypassed. In addition, optimizing the DC voltage increases the number of faulty units that can be tolerated and improves the reliability of the converter. Simulations and experimental results are shown for a seven-level three-phase CHB converter to validate the efficiency and feasibility of this strategy.

• International Journal of Advanced Culture Technology
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• 제8권4호
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• pp.212-219
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• 2020

We conducted this study to identify the accommodation applications users' lifestyle types and the composition factors for consumers' accommodation applications selection attributes and to identify the difference in the selection attributes perception of accommodation applications between groups classified by user's lifestyle types. According to the study, 6 factors were derived as the accommodation applications users' lifestyle types and were named social/leisure-oriented type, fashion-seeking type, culture-seeking type, self-examining type, self-centered type, family-oriented type. Also 6 factors were derived as the accommodation applications selection attributes and were named convenience, interactivity, economic efficiency, transaction reliability, product reliability and informativeness. Valid clusters were divided into four groups and were named culture/tourism group, self-examining group, passive and cautious group and Social and practicality-seeking group. Most of the selection attributes perception of accommodation applications between groups had statistically significant differences(p<.05), except for some items of transaction reliability. Based on the results of this study, we should strive to establish effective marketing strategies that reflect differences in the selection attributes perception of the accommodation application between groups classified by users' lifestyle types.