• 한국화재소방학회논문지
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• 제31권2호
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• pp.9-16
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• 2017

본 연구는 단면형태 및 단면크기에 따라 무피복 및 무용접 조건에서 CFT기둥의 내화성능을 평가하기 위하여 내화실험을 실시하였다. 실험결과, 슬롯형 CFT기둥(${\square}500$)은 무피복 조건에서 180분 이상의 내화성능을 발휘하였다. 슬롯형 CFT기둥(${\square}300$)은 무피복 조건에서 125분의 내화성능을 발휘하였고, 이때 변형률을 분석한 결과 슬롯형 CFT 기둥이 용접형 CFT기둥에 비해 연성파괴를 하는 것으로 나타났다. 또한 용접형 CFT기둥이 내화성능을 상실한 시점에서 중심부 온도는 슬롯형 CFT기둥에 비해 높게 나타났다. 따라서 슬롯접합이 콘크리트 내부온도에 미치는 영향은 크지 않은 것으로 판단된다.

• 플랜트 저널
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• 제9권4호
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• pp.26-30
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• 2013

유동가속부식에 의해 배관이 파손된 500 MW급 A 복합발전소 배열회수보일러 저압증기발생기 배관을 모델로 삼아 배관급수 내의 용존산소 부족이 유동가속부식의 주요 원인임을 도출하고 용존산소를 증가시키기 위해 적용된 하이드라이진 차단 수처리에 대한 적용효과를 분석하였다. 수처리 적용 1년 후 급수의 용존산소는 0.15 ppb에서 3~5 ppb로 상승되고, 산화환원전위도 -245 mV에서 170 mV로 산화성으로 상승되었다. 또한 유동가속부식에 의한 부식생성물인 철분함유량은 18.5 ppb에서 5~7 ppb로 감소되었다. 따라서 하이드라이진 차단 수처리로 급수의 용존산소가 증가되며 유동가속부식에 의한 배관의 부식생성물인 철분함유량이 감소됨을 확인하였다.

• 한국철도학회논문집
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• 제12권4호
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• pp.457-464
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• 2009

디젤 엔진 매연 필터의 입구부와 배출 가스 배출을 위한 배기관 연결을 직선 또는 곡선으로 형태로 연결하였을 때의 DPF 입구 유속 분포를 $STAR-CD^{(R)}$ 전산해석 프로그램을 사용하여 시뮬레이션하였다. 곡관의 형상을 나타내는 3 종류의 수치해석 용 격자 모델을 사용하여 DPF 입구에서의 유속 분포를 시뮬레이션 하였다. 피토관을 2차원 이송장치에 탑재하고 위치를 이동시키며 측정한 유속 분포와 동일한 조건에서 시뮬레이션한 결과와 비교하였다. DPF 입구와 $90^{\circ}$의 곡관이 연결된 조건에서 CFD 해석을 수행한 결과 입구 단면에서의 유속 분포가 말발굽 형태를 나타내었으며 최대 유속값이 DPF 중심축에서 약간 벗어난 위치에서 나타나고 있다. 이러한 CFD 해석결과는 실험 결과와 비교적 잘 일치하였다.

• 셀메드
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• 제2권2호
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• pp.20.1-20.5
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• 2012

$Gynura$ $segetum$ (Lour.) Merr. ($Compositae$) is a well recognized medicinal plant in Indonesia and Malaysia. It is believed to have an anticoagulant effect and is used in treating snake-bites, inflammations and other skin afflictions. This study was carried out to evaluate the antimicrobial effects of $Gynura$ $segetum$ leaves extracts and its fractions. The chemical compositions of the active extracts were also determined. The antimicrobial activities of different solvent extracts of leaves of $Gynura$ $segetum$ were evaluated using the agar well-diffusion method. The Minimum Inhibitory Concentration (MIC) of the active subfractions was determined by the tube dilution method. Gas Chromatography-mass spectrometry (GC-MS) analysis was carried out to identify the chemical compositions of the active extracts. The ethyl acetate fraction and its subfraction E4 performed potent antimicrobial activities and fifteen known chemical constituents were identified by GCMS analysis as 4-vinylphenol, 1-tetradecene, phenol, 2,4-bis(1,1-dimethylethyl), 1-hexadecene, E-15-heptadecenal, hexadecanoic acid, 1,2-benzenedicarboxylic acid, dibutyl ester, 1-docosene, octadecanoic acid, 1-eicosene, cyclotetracosane, 1,2-benzenedicarboxylic acid, bis(2-ethylhexyl)ester, butanedioic acid, monomethyl ester, niacin and 4-hydroxy-benzoic acid. The results of this study suggested a connection between the antimicrobial activities and the chemical structures. The plant may be used as a potential source for antimicrobial agents.

• 대한기계학회논문집A
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• 제35권2호
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• pp.175-181
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• 2011

최근 컴퓨터비전을 이용하여 부품의 치수를 정확하게 그리고 빠르게 측정하고자 하는 연구가 많이 진행되고 있다. 하지만 컴퓨터비전의 경우 조명이 완벽하지 않으면 노이즈가 많이 발생하는 경우가 있다. 실제 산업현장에서는 기계들 간의 간섭에 의해 완벽한 조명을 구현하기 어렵기 때문에 노이즈를 피하기 어렵다. 본 논문에서는 튜브의 내경 반지름 측정 시 문제가 되는 노이즈를 효과적으로 제거하고 반지름 측정의 정밀도를 향상시키기 위한 컴퓨터 비전 측정 알고리즘을 제안한다. 표준편차가 최소가 되는 중심점을 이용하여 노이즈를 제거하고 이 때 발생되는 원호상의 불연속 문제는 원호 연결 알고리즘으로 해결하였다. 제안된 알고리즘의 성능은 노이즈가 추가된 원과 실제 튜브의 영상을 이용한 실험을 통해 증명하였다. 15%의 수준의 노이즈가 추가된 원의 반경을 구하는 실험에서도 1.4% 수준의 오차를 보여주어 본 알고리즘의 유용성을 확인할 수 있었다.

• Healthcare Informatics Research
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• 제24권4호
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• pp.292-299
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• 2018

Objectives: The aim of the present study was to assess the frequency of use, and preferences regarding information and communication technologies (ICTs) among Ecuadorian patients with chronic kidney disease (CKD) undergoing hemodialysis. Methods: We conducted an anonymous cross-sectional survey-based study from January 2016 to April 2017, involving 393 patients with end-stage renal disease from 9 hemodialysis centers, in which they rated their use and preferences of various ICTs through a modified version of the Michigan Questionnaire. The questionnaire collected information regarding demographics, patients' interest in obtaining health-related information through ICTs, and interest in using ICTs as a potential way to communicate with their healthcare providers. A chi-square test for association and adjusted regression analyses were performed. Results: Among all patients who participated, 64.3% reported owning a cellphone, with less than a third reporting active Internet connection. The most used ICT for obtaining information about CKD and/or hemodialysis was web-based Internet, followed by YouTube. SMS was rated the highest to receive and seek health-related information, followed by Facebook. Younger age and higher levels of education were associated with a higher overall usage of ICTs. Finally, more than half of the patients reported interest in using WhatsApp for communicating with their healthcare providers. Conclusions: Understanding the preferences of ICTs among patients with CKD undergoing hemodialysis could help to improve their outcomes through the potential uses and benefits of ICTs. Further research is needed to assess their role in improving the care of patients with chronic diseases.

• 공학교육연구
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• 제24권1호
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• pp.34-45
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• 2021

This research is a case study about "Critical Thinking and Debate Education" class which was done for freshmen at the engineering college of "S" Women's University. Real time remote classes through LMS and ZOOM were the most effective tools under on-line circumstances, considering the fact that video lectures only cannot cultivate students' capabilities of critical thinking and communication. Throughout the analysis on students' self-reflection journals and lecture evaluations, this paper examined considerable future points and the pros and cons of "Critical Thinking and Debate Education" under online presentation and discussion situation. As research outputs, students told they could feel less nervousness and anxiety when they exercise and have a presentation because they could choose familiar space for them. In addition, students also told that they feel comfortable about both self-feedback and peer evaluation, repeatedly seeing the recorded video clip. However, on the contrary, sometimes students felt uncomfortable due to unstable internet connection through the online classes, and they also were regretful about the missing chances of interaction between a teacher and students and of intimate exchanges among students. They also told they had felt a kind of limit of enhancing their presentation skills just in front of the monitor. Considering these outcomes, this research paper points out that online education needs to be proceeded by strengthening multi layered feedback to students with the build-up of a non-face-to-face stable educational infrastructure, application of online instructional strategy, and utilization of YouTube platform and video contents. Through this research paper, I hope the new system of encompassing on/off line "Critical Thinking and Debate Education" and effective teaching and learning method can be developed soon by strengthening the strength of online education.

• Steel and Composite Structures
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• 제43권3호
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• pp.327-340
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• 2022

A vast amount of experimental and analytical research has been conducted related to the seismic behavior and performance of concrete filled steel tubular (CFT) columns. This research has resulted in a wealth of information on the component behavior. However, analytical and experimental data for structural systems with CFT columns is limited, and the well-known behavior of steel or concrete structures is assumed valid for designing these systems. This paper presents the development of an analytical model for nonlinear analysis of composite moment resisting frame (CFT-MRF) systems with CFT columns and steel wide-flange (WF) beams under seismic loading. The model integrates component models for steel WF beams, CFT columns, connections between CFT columns and WF beams, and CFT panel zones. These component models account for nonlinear behavior due to steel yielding and local buckling in the beams and columns, concrete cracking and crushing in the columns, and yielding of panel zones and connections. Component tests were used to validate the component models. The model for a CFT-MRF considers second order geometric effects from the gravity load bearing system using a lean-on column. The experimental results from the testing of a four-story CFT-MRF test structure are used as a benchmark to validate the modeling procedure. An analytical model of the test structure was created using the modeling procedure and imposed-displacement analyses were used to reproduce the tests with the analytical model of the test structure. Good agreement was found at the global and local level. The model reproduced reasonably well the story shear-story drift response as well as the column, beam and connection moment-rotation response, but overpredicted the inelastic deformation of the panel zone.

• 한국컴퓨터정보학회논문지
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• 제27권12호
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• pp.111-119
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• 2022

본 연구는 빅데이터 분석을 이용하여 코로나19 전후의 3D가상패션에 대한 인식의 변화를 알아보기 위하여 코로나19 발생 전인 2017년 1월1일부터 발생 이후인 2022년 10월30일까지 소셜미디어 네이버, 다음, 구글, 유튜브에서 추출한 3D 가상패션 관련 주요 단어들을 대상으로 텍스톰을 이용하여 빅데이터 자료를 수집하였다. 수집된 단어는 정제 과정을 거친 후 워드클라우드, 단어의 빈도, 연결중심성, 네트워크 시각화와 CONCOR 분석을 실시하였다. 3D 가상패션을 키워드로 32,461개의 단어를 추출하여 분석한 결과 패션, 가상, 기술의 출현빈도와 중심성이 가장 높게 나타났으며 디지털, 디자인, 의상, 활용, 제조의 출현빈도도 높게 나타났다. 이를 통해 3D 가상패션이 기술의 발달과 더불어 산업 전반에 활용되고 있음을 알 수 있었다. 특히 코로나19 이후 가장 부각되는 주요 단어는 메타버스와 3D 교육으로서 패션산업에서의 요구도가 높게 나타나고 있다.

• 한국압력기기공학회 논문집
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• 제18권2호
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• pp.37-42
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• 2022

An influence analysis on multiple steam generator tube rupture (mSGTR) followed by an unmitigated station blackout is performed to compare the plant responses according to the number of ruptured u-tubes under the assumption of a total of 10 ruptured u-tubes. In all calculation cases, the transient behaviour of major thermal-hydraulic parameters, such as the discharge flow rate through the ruptured u-tubes, reactor header pressure, and void fraction in the fuel channels is found to be overall similar to that of the base case having a single SG with 10 u-tubes ruptured. Additionally, as the conditions of low-flow coolant with high void fraction in the broken loop continued, causing the degradation of decay heat removal, the peak cladding temperature (PCT) would be expected to exceed the limit criteria for ensuring nuclear fuel integrity. However, despite the same total number of ruptured u-tubes, because of the different connection configuration between the SG and pressurizer, a difference is foud in time between the pressurizer low-level signal and reactor header low-pressure signal, affecting the time to trip the reactor and to reach the PCT limit. The present study is expected to provide the technical basis for the accident management strategy for mSGTR transient conditions of CANDU-6 plants.