• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1081-1094
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• 2014

The strut-tie model approach has proven to be effective in the ultimate analysis and design of structural concrete with disturbed regions. For the reliable analysis and safe design of the structural concrete, however, the effective strengths of concrete struts must be determined accurately. In this study, the equations of the effective strengths of concrete struts, which are useful for the three types of determinate and indeterminate strut-tie models of reinforced concrete corbels, were proposed. The effects of shear span-to-effective depth ratio, the vertical-to-horizontal force ratio, and flexural and horizontal shear reinforcement ratios were reflected in the development of the proposed equations. To examine the appropriateness of the proposed and existing equations, the ultimate strengths of 243 reinforced concrete corbels tested to failure were evaluated by using the three types of corbel strut-tie models.

• Journal of the KSME
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• v.49 no.12
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• pp.32-35
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• 2009

가속시험은 사용조건보다 가혹한 시험조건을 사용하여 짧은 시간에 제품의 수명을 평가한다. 이 글에서는 가속시험에 활용되는 가속모델에 대한 개발절차와 유효성 검증방법을 간단하게 소개하고자 한다.

• The Science & Technology
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• v.5 no.1 s.33
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• pp.26-28
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• 1972

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.476-477
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• 2006

최근 IT산업의 눈부신 성장과 고성능 전자소자가 개발됨에 따라 전력계량분야에서도 많은 변화가 있었다. 전자소자를 사용하여 다양한 기능들을 구현할 수 있는 전자식전력량계가 이미 10여년 전부터 도입하여 운용하고 있으며, 다양한 요금제도를 통한 전력사용의 합리화 및 수요관리, 원격검침 등에 기여하고 있다. 전자식전력량계는 현행 관련법령에 따라 전력량계의 검정유효기간이 7년으로 규정되어 있어 검정유효기간의 조정에 대한 필요성이 제기되어 왔다. 검정유효기간은 제품의 수명과 경제적 교체주기에 따라 결정할 사안이므로 이에 대한 기초자료로 활용하고자 가속열화시험 등 몇 가지 수명예측기법을 이용하여 현재 운영중인 전자식전력량계의 수명을 예측하고 그 결과를 제시하고자 한다.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.118-119
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• 2013

마이크로그리드 독립 운전 모드시 분산전원 기반의 인버터 병렬 운전은 인버터가 전압원과 같이 정의됨에 따라 계통과의 연결없이 병렬 연결된 인버터가 전체 부하를 담당해야 하는 의무를 가진다. 이때 드룹 방식은 병렬형 인버터 각각에 적용됨으로써 전체 부하 분담성능을 향상시킨다. 하지만 각 분산전원과 PCC단을 연결하는 선로 임피던스가 불평형 이거나 서로 다른 R/X 비를 가지고 있을때 유도성 선로에 적용을 목적으로 하는 기존의 드룹 방식을 사용하면 유효전력 분담은 어느 정도의 효력을 보이지만 무효 전력 분담에 있어서 오차가 발생하게 된다. 이와 반대로 저항성 선로에 적용을 목적으로 하는 드룹 방식을 적용하면 무효 전력 분담은 잘 이루어지지만 유효 전력 분담은 서로 다른 선로 임피던스 전압 강하로 인해 오차가 발생하게 된다. 따라서 본 논문에서는 PSIM을 활용하여 고, 중, 저전압 마이크로그리드 뿐만 아니라 R성분이 매우 지배적인 초저전압 마이크로그리드에 각기 다른 드룹 방식을 적용할때의 영향을 분석하고 이에 제안된 선로 임피던스를 고려한 기준 전압 조정텀을 추가하여 유효, 무효 전력 분담 오차를 개선하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.05a
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• pp.172-174
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• 2018

기존선형과 저항을 최소화하는 최적선형에 대한 에너지효율 성능을 평가하는 것이다. 설계 흘수와 설계 선속을 고려하여 대상선박의 선수부 형상을 검토하였다. 실제 운항 상태에서 대상선박의 저항성능을 평가하였다. 상용 전산유체역학(CFD) 코드와 수조 모형시험 자료는 유효마력 평가를 위해 사용되었다. 실제 운항 상태를 고려하여 최소저항을 가지는 최적선형을 제시하였다. 기존선형과 최적선형에 대하여 3가지 선속에서 유효마력을 추정하였다. 최적선형의 저항성능은 기존선형과 비교하여 볼 때 설계속도(12노트)에서 약 6% 향상된 결과를 보여 주었다. 준추진효율 계수(ETAD, ${\eta}D$)는 모형시험 자료를 활용하였다. 에너지 효율 성능은 년간 운항일수, 벙커C유 가격, 1일 연료사용량 그리고 연료소비계수를 바탕으로 작성되었다.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.9
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• pp.217-224
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• 2019

Recently, sensor networks are built and used on many kinds of fields such as home, traffic, medical treatment and power grid. Sensing data manipulation on these fields could be a serious threat on property and safety. Thus, a proper way to block sensing data manipulation is necessary. In this paper, we propose IoT(Internet of Things) sensing data validation mechanism based on data obfuscation and variance analysis to remove manipulated sensing data effectively. IoT sensor device modulates sensing data with obfuscation function and sends it to a user. The user demodulates received data to use it. Fake data which are not modulated with proper obfuscation function show different variance aspect with valid data. Our proposed mechanism thus can detect fake data by analyzing data variance. Finally, we measured data validation time for performance analysis. As a result, block rate for false data was improved by up to 1.45 times compared with the existing technique and false alarm rate was 0.1~2.0%. In addition, the validation time on the low-power, low-performance IoT sensor device was measured. Compared to the RSA encryption method, which increased to 2.5969 seconds according to the increase of the data amount, the proposed method showed high validation efficiency as 0.0003 seconds.

• Journal of the Korean Association of Geographic Information Studies
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• v.16 no.3
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• pp.91-102
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• 2013

The purpose of this study is to suggest the way of effective use of spatial data in Busan metropolitan city. To do so, information systems and spatial data established in each department are analyzed. Spatial data distribution networks scattered around the nation are integrated to the national spatial information clearinghouse and the service is expanded for the public and the private sectors to participate. Information systems supplied by the central government are 22 and information systems operating in the Busan Metropolitan City are 168. In addition, there are also 295 types of the thematic maps in 11 fields related to the environment, road transportation, livestock, and etc. For systems integration and management system, an integrated information management and linkage system is required in the near future. In the next logical step, generation of metadata, experiments for effective utilization of spatial data, and construction of the data center should be necessary.

• Journal of the Korean Society for Library and Information Science
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• v.55 no.3
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• pp.343-372
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• 2021

The purpose of this study is to select keywords that can recommend books by personality type, and to test whether the chosen keywords can be actually used in the categorization and customized recommendation of books for each personality type. To achieve the research goal, this study chose books that match the level of fifth and sixth grade elementary school students and first grade middle school students and commissioned an expert group to categorize the books into groups that are preferred by each personality type. As a result of the classification, half of the books in which more than five experts agreed showed high consensus. In addition, the results of classifying books by personality type with keywords extracted by the automatic word extraction system by collecting the book review data of the selected books were similar to the results of the final judgement by the expert group, except for a few books. In conclusion, this study proved that it is possible to classify and recommend books that are likely to be preferred by different personality types using review keywords.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.390-396
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• 2019

This study was undertaken to analyze factors influencing the emotional labor and emotional intelligence of a dental hygienist on organizational effectiveness. The study was conducted between September 4, 2018 to December 7, 2018, enrolling a total of 233 dental hygienists living in the Jeollabuk-do province. The data were analyzed by independent t-test, one-way ANOVA, $Scheff{\acute{e}}$ test, Pearson's correlation coefficient, and stepwise multiple regression, using SPSS 18.0. The regression model obtained was F=138.917, P<0.05, with an explanatory percentage of 58.2. Emotional labor (${\beta}=0.608$) was determined to be the most influential variable among independent variables, and other factors affecting the organizational effectiveness of a dental hygienist include the highest level of education, career, and emotional intelligence. We conclude that in order to improve organizational effectiveness among dental hygienists, it is necessary to establish an effective plan for reducing emotional labor and promote emotional intelligence.