3D 콘크리트 프린팅용 시멘트 복합재료의 레올로지 특성 연구

이건우(Lee, Keon Woo),임동규(Lim, Dong Gyu),최명성(Choi, Myoung Sung) 한국콘크리트학회 2019 한국콘크리트학회 학술대회 논문집 Vol.31 No.2

핵심역량기반 대학교육에 대한 빅데이터 분석

이건우(Keon-Woo Lee),최승연(Seung-Yeon Choi) 학습자중심교과교육학회 2022 학습자중심교과교육연구 Vol.22 No.15

목적 본 연구는 빅데이터에 대한 네트워크 분석을 통해 핵심역량기반 대학교육에 대한 사회적 담론을 살펴보고자 하였다. 방법 이를 위해 빅데이터분석 분석 솔루션 Textom을 활용하였다. 먼저 웹에서 ‘대학’+‘핵심역량’을 키워드로 데이터를 수집하였으며, 네트워크 분석 프로그램인 UCINET을 활용하여 분석을 실시하였다. 수집데이터는 1, 2차 정제과정을 통해 추출단어의 빈도수를 바탕으로 핵심키워드 100개를 선정하였으며, 1-모드 매트릭스를 작성한 후 네트워크 분석 및 Concor분석을 실시하였다. 결과 연구결과, 첫째, 빈도분석결과 ‘핵심역량’, ‘대학’, ‘연구’, ‘학생’, ‘교육’ 등의 키워드가 높은 출현빈도를 나타냈다. 둘째, 중심성 분석결과 중심성이 급격히 증가한 키워드는 ‘장학신청’, ‘프로그램’, ‘강화’로 나타났다. 셋째, Concor분석 결과 군집은 4개로 형성되었으며, 각 2개의 대군집과 소군집이 형성되는 것으로 나타났다. 결론 빅데이터 네트워크에서 드러난 핵심역량기반 대학교육은 대학의 발전과 역할, 대학의 진단과 평가, 장학제도, 변화와 대응의 측면에서 사회적 담론을 이끌어내고 있으며, 이 같은 결과는 핵심역량기반의 대학교육을 성장⋅발전시켜 나가는데 방향과 시사점을 제공하는데 의미를 가진다. Objectives This study attempted to examine the social discourse on core competency-based university education through network analysis of big data. Methods For this purpose, Textom, a big data analysis analysis solution, was used. First, data were collected from the web with keywords ‘university’ + ‘core competency’, and analysis was conducted using UCINET, a network analysis program. For the collected data, 100 key keywords were selected based on the frequency of extracted words through the first and second refining processes, and a 1-mode matrix was created and then network analysis and Concor analysis was performed. Results as a Results First, as a result of frequency analysis, keywords such as ‘core competency’, ‘university’, ‘research’, ‘student’, and ‘education’ showed a high frequency of appearance. Second, as a result of centrality analysis, the keywords for which centrality increased rapidly were ‘scholarship application’, ‘program’, and ‘reinforcement’. Third, as a result of Concor analysis, 4 clusters were formed, and 2 large and small clusters were formed each. Conclusions The core competency-based university education revealed in the big data network is leading to social discourse in terms of the development and role of the university, the diagnosis and evaluation of the university, the scholarship system, and change and response. It has meaning in providing directions and implications for growth and development.

화염안정기 형상이 램제트 연소실에서의 슬롯 막냉각 특성에 미치는 영향

이건우(Keon Woo Lee),송지운(J Song),조형희(Hyung Hee Cho),황기영(Ki Young Hwang) 한국추진공학회 2008 한국추진공학회 학술대회논문집 Vol.2008 No.5

본 연구에서는 화염 안정기 형상이 램제트 연소실에서의 단열 막냉각 효율에 미치는 영향에 대하여 실험을 수행하였다. 램제트 연소실 입구의 경사진 확장면의 끝에 화염안정기 형상을 설치하여 화염안정기에 의해 발생된 난류 유동이 다단 슬롯에 영향을 끼치도록 실험 장치를 구성하여, 화염안정기 형상을 탈부착 시키면서, 슬롯 출구 하류에서의 단열 막냉각 효율을 측정하였다. 화염 안정기를 설치하였을 경우 화염안정기에 의해 발생된 유동의 높은 전단력과 난류강도로 급격히 주유동과 혼합되어, 화염안정기가 설치되지 않은 경우에 비해 전체적으로 냉각 성능이 감소함을 결과를 통해 확인하였다. This experimental study has been conducted to investigate the effect of the flame holder on the multi-slot film cooling in the ramjet combustor. The turbulent wake which is generated by the flame holder on the entrance of the coolant flow path affects on the slot. Adiabatic film cooling effectiveness on the downstream wall of the slot exit are measured. The results show that the film cooling performance is rapidly decreased after the slot exit by shear layer and high turbulence intensity between separated flows and coolant flows.

3D프린터의 유치원 현장적용을 위한 빅데이터 분석 및 델파이 조사 분석

이건우(Lee, Keon-Woo),유구종(Yoo, Gu-Jong) 한국열린유아교육학회 2019 열린유아교육연구 Vol.24 No.2

본 연구는 빅데이터 분석을 통해 3D프린터에 대한 소셜미디어의 사회적 인식을 분석하여 통합네트워크화 하고, 이를 토대로 2차에 걸친 델파이 조사 연구에 기반하여 3D프린터의 유치원 현장적용에 대한 방안을 모색하기 위해 수행되었다. 이를 위해 ‘3D프린터+유아’, ‘3D프린터+교육’을 검색어로 최근 3년간 국내 소셜미디어 온라인 상의 텍스트 데이터를 수집하여 분석하였다. Textom을 통해 텍스트를 수집 및 정제하였으며, UCINet6를 사용하여 시각화 하였다. 또한 전문패널을 선정하여 2차에 걸친 델파이 조사를 실시하였다. 연구결과는 다음과 같다. 첫째, 3D프린터에 대한 인식의 주요 키워드 분석 결과, 상위 20개의 단어를 통해 동시출현 빈도와 주요발생지역을 파악하였다. 둘째, 1차 델파이 조사결과 3D프린터에 대한 인식은 필요성, 문제점, 요구의 3가지 범주로 나타났다. 셋째, 2차 델파이 조사결과 3D프린터를 유치원 현장에 적용하기 위해서는 비용절감, 유치원 현장의 인식개선, 교육적 효과 검증이 선행되어야 한다는 응답이 가장 높은 비율로 나타났다. 이러한 연구결과에 기초하여 3D프린터의 유치원 현장적용을 위한 방안을 논의하였다. This study aims to explore ways to apply 3D printers in kindergarten through two-time Delphi survey, which is based on the unified network of social perception appeared in social media towards 3D printers through big data analysis. For this, ‘3D Printer + Infant’ and ‘3D Printer + Education,’ as a search terms, were collected and analyzed online text data of domestic social media were collected over the past three years. Text was collected and refined through Textom and then visualized using UCINet6. Based on this, the Commission selected experts in infant education policy and evaluation, experts in child education administration, and experts in infant education field as expert panels and sought ways to apply 3D printers to kindergarten on-site through a two-stage Delphi survey. The data of the Delphi survey conducted in two rounds were analyzed through frequency analysis and technical statistics, and reliability and feasibility were presented, and The results of the study are as following. First, the main keyword analysis of recognition of 3D printers selected the top 20 words to discover frequency of simultaneous appearance and central occurrence area. Second, the first Delphi survey revealed that the recognition of 3D printers was in three categories: necessity, problem, and demand. Third, the second Delphi survey found that the highest percentage of respondents said that in order to apply 3D printers to kindergarten sites, cost reduction, improvement in awareness of kindergarten sites, and verification of educational effects must precede. Based on these findings, a plan for field application of 3D printers to kindergartens is discussed.

3D 프린팅용 복합재료 개발을 위한 시멘트 페이스트 레올로지 특성 연구

이건우(Lee, Keon Woo),이동규(Lee, Dong Gyu),최명성(Choi, Myoung Sung) 한국콘크리트학회 2019 한국콘크리트학회 학술대회 논문집 Vol.31 No.1

사회적 할인율을 고려한 국내육상풍력발전 단지의 LCOE 분석

이건우(Lee Keon-Woo),고경남(Ko Kyung-Nam) 한국태양에너지학회 2020 한국태양에너지학회 논문집 Vol.40 No.1

A study on estimation of the Levelized Cost of Energy (LCOE) was conducted for the Korean onshore wind farms. The LCOE was estimated on the basis of the actual wind farm data from Data Analysis, Retrieval Transfer system (DART) run by Financial Supervisory Service. Recently, social discount rate of Korea dropped from 5.5% to 4.5%, which was taken into account for this study. The onshore wind farms studied accounted for 42% of all the onshore wind farms of South Korea. Capital Expenditure (CapEx) and Operation Expenditure (OpEx) were calculated from the actual data, while Capacity Factors (CFs) were obtained from the wind farms of five provinces. Their distributions were estimated using Maximum Likelihood Estimation method, and then Monte Carlo Simulation (MCS) was performed for estimating LCOE, Levelized Fixed Cost (LFC), and Levelized Variable Cost (LVC). As a result, the LCOEs at the two discount rates, 4.5 and 5.5%, were 142 and 152 $/㎿h, respectively, which were lower than that of financially viable onshore wind project of Korea. The 1% drop of social discount rate was estimated to result in a 10 $/㎿h decrease in LCOE and a 4 $/㎿h in LFC, which can be an advantage for wind project investors.

상층각막성형술과 LASIK 의 고도근시 교정효과

이건우(Keon Woo Lee),최태훈(Tae Hoon Choi),이하범(Ha Bum Lee) 대한안과학회 1998 대한안과학회지 Vol.39 No.8

재순환 영역이 램제트 연소실에서의 열전달 특성에 미치는 영향

이건우(Keon Woo Lee),오민근(Min Keun Oh),조형희(Hyung Hee Cho),함희철(Hee Chul Ham),황기영(Ki Young Hwang) 한국추진공학회 2007 한국추진공학회지 Vol.11 No.6

건설재료의 안전적 제어를 위한 표준물질 (Standard Reference Materials) 도출

이동규,이건우,최명성,Lee, Dong Kyu,Lee, Keon Woo,Choi, Myoung Sung 한국안전학회 2017 한국안전학회지 Vol.32 No.5

The purpose of this study is to develop standard reference materials for safety control of construction materials considering the required performance of standard materials including flow performance incorporating particles. The flow characteristics of concrete are very complicated depending on mixing proportions of constituent materials, admixtures, amount of mixing, type of mixer, time of mixing, temperature and so forth. Uncertainties and multidimensional properties of concrete have been evaluated through various studies but there are few researches for the development of standard reference material. In this study, based on the rheological concept, the flow performance of construction materials was evaluated to understand the properties of standard reference materials and was finally obtained representing materials which simulate the standard reference materials.

모듈형 LNG 저장탱크용 콘크리트 충전성능 가이드라인 제시

이동규,이건우,박기준,김성욱,박정준,김영진,최명성,Lee, Dong Kyu,Lee, Keon Woo,Park, Gi Joon,Kim, Sung Wook,Park, Jung Jun,Kim, Young Jin,Choi, Myoung Sung 한국안전학회 2018 한국안전학회지 Vol.33 No.2

Recently, the use of composite steel plate concrete structural modules filled with concrete between steel plates of complex internal structure, in which a large amount of studs are installed, is increasing in order to reduce the weight and to increase workability of structures such as LNG storage tanks. However, in Korea, there is no systematic criterion for evaluating the construction performance of composite steel plate concrete structural modules. Therefore, in this study, we propose a filling guideline of concrete for composite steel plate structural module. For this purpose, high filling performance concrete with general strength range was formulated and tested for filling ability and permeability for each formulation. Rheology analysis was performed to quantitatively evaluate the flow characteristics of concrete. The reliability of $T_{500}$ and plastic viscosity was evaluated to reflect the results of each test, and a guideline for high filling concrete satisfying the reliability of 0.9 or more was derived by reflecting the results of the study on the relationship between the $T_{500}$ and plastic viscosity. Through final fill-box test, filling performance was verified and guidelines were suggested.