침지방법에 따른 지오폴리머의 압축강도 변화 메커니즘

김학민,김유택,Kim, Hakmin,Kim, Yootaek 한국결정성장학회 2022 한국결정성장학회지 Vol.32 No.2

This study was performed to investigate the mechanism of the change in compressive strength of autoclave cured geopolymers. Specimens were immerged in distilled water, 2M, 8M, and 14M alkaline solutions for 3, 7, and 21 days. The change in the specimens immersed in a short period of time was not significant, but the compressive strength of the specimens immersed in the distilled water and 8M alkali solution) for 21 days increased more than twice as much as before immersion because of additional geopolymerization. However, compressive strength decreased due to the alkaline aggregate reaction when alkaline solution was supplied more than a certain level of concentration. Therefore, immersing the specimens for more than 21 days in the distilled water or 8M alkaline solution would be desirable for the improvement of compressive strength of autoclave cured specimens.

지오폴리머의 침지 후 물성변화

김학민,김유택,Kim, Hakmin,Kim, Yootaek 한국결정성장학회 2021 한국결정성장학회지 Vol.31 No.6

This study was started to investigate why autoclave curing (AC) specimen showed an improvement in compressive strength after immersion in water for a long time, although AC specimen did not showed a high initial compressive strength unlike our expectations. Distilled water and alkaline solutions were used for immersion and three different curing methods were engaged. It was expected that the compressive strength would be improved after immersion in alkaline solutions; however, there was little difference in compressive strength after 21 day immersion because both new crystallites produced by additional geopolymerization and expansion caused by the alkaline aggregate reaction may prevent the additional improvement in compressive strength. It was concluded that in order to secure the long-term commonality and underwater stability of the geopolymers, it is desirable aging geopolymers while immersing it underwater for more than 21 days after curing using an autoclave.

침지 후 경량 지오폴리머의 압축강도 변화

김학민,김유택,Kim, Hakmin,Kim, Yootaek 한국결정성장학회 2021 한국결정성장학회지 Vol.31 No.4

Lightweight geopolymers were fabricated by using IGCC (integrated gasification combined cycle) slag and Si sludge which are classified as general wastes (recyclable resources). Three curing methods were tried to investigate the changes in compressive strength and density according to the curing method and immersion time. Immersion period was tried up to 21 days to observe long-term performance in water. Compressive strength of the specimens cured in oven decreased abruptly with an increase in immersion time. Compressive strength of the specimen cured in autoclave was low after 3 and 7 day immersion; however, increased rapidly after 21 day immersion. On the contrary, compressive strength of the specimen cured in autoclave and oven was high but substantially decreased after 21 day immersion. Conclusively, it was speculated that oven curing is effective for the compressive strength development at early age; however, autoclave curing is more desirable for the long-term performance in water.

A Study on Optimal Cutting Condition of EPS Foam Cutting Based on Collimated CO₂ Laser Beam

김학민(Hakmin Kim),심준혁(Joonhyeok Sim),정상열(Sangyeol Jeong),홍대희(Daehie Hong) Korean Society for Precision Engineering 2019 한국정밀공학회지 Vol.36 No.9

배전계통의 수용가의 누설전류 제거장치 개발에 관한 연구

김학민(Hakmin Kim),최종재(Jongjae Choi),한창희(ChangHee Han),최재석(Jaeseok Choi) 대한전기학회 2024 대한전기학회 학술대회 논문집 Vol.2024 No.10

에멀젼연료 충돌분무의 거동특성에 관한 연구

김학민(Hakmin Kim),염정국(Jeongkuk Yeom) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.신뢰성 No.-

정부R&D예산지출의 변동요인 분석: 일본의 수출규제 사례를 중심으로

김학민(Kim, Hakmin),임복희(Im, Bokheui),박윤환(Park, Yoonhwan) 서울행정학회 2020 한국사회와 행정연구 Vol.31 No.3

정부의 지출은 기본적으로 정책변동의 영향을 받기 때문에 정책의 내용을 결정하는 요인이 무엇인가에 대한 관심은 중요하다. 특히, 정부R&D예산지출은 국가의 경제발전을 위한 투자이며 정책의 추진 방향에 따라 국가경쟁력에 영향을 미치게 되므로 외부의 환경적 변화를 이해하고 이를 반영한 기획과 의제설정은 매우 중요한 것이다. 본 연구는 정책결정요인론적 관점에서 2019년 7월에 발생한 일본의 수출규제라는 사건을 바탕으로 정부R&D부문의 정책결정과정에서 정책의 내용을 결정하는 환경적 요인이 무엇인가를 밝히는데 목적이 있다. 이를 위해 빅데이터 분석기법 중 하나인 LDA(Latent Dirichlet Allocation)기법의 토픽모델링(Topic modeling)을 활용하여 뉴스기사와 정부문서를 대상으로 정책단절의 발생시점 즉, 비점증적인 변화를 보이는 단절시기를 이끌었던 요인들을 분석하였다. 분석결과, 정부R&D예산지출의 변동을 가져온 환경적 요인은 ‘대통령의 정책의지’, ‘국회의 관심’, ‘정책의제의 우선순위’, ‘국민의 여론’, ‘기술의 자립화’, ‘산업화’라는 가치로 도출되었다. 본 연구는 정부R&D지원 정책의 기획과 의제 설정에 있어서 원천기술의 확보를 통해 기술과 생산의 단절을 극복하고, 4차 산업혁명시대에 대응하기 위한 산업생태계의 재정비와 같은 정책패러다임의 일대전환이 필요하다는 점을 환기시키고 있다. 이는 미래관련 정책결정과 예산배분의 효율성을 증진시키는데 기여하는 정책적 함의도 기대할 수 있을 것이다. Since government spending is basically affected by policy changes, it is important to pay attention to what factors determine the content of the policy. Especially, Government R&D budget expenditure is an investment for the country’s economic development, and it affects the national competitiveness according to the direction of policy implementation. Therefore, it is very important to understand external environmental changes and reflect them on planning and agenda setting. From a policy-determining factor theory perspective, the purpose of this study is to clarify what are the environmental factors that determine the content of policy in the policy-making process of the government R&D sector based on the incident of Japanese export regulation that occurred in July 2019. To this end, using topic modeling of LDA (Latent Dirichlet Allocation), one of the big data analysis methods, is used to target the time of policy disruption, that is, the time of disruption showing non-incremental changes, for news articles and government documents. The factors that led were analyzed. Analysis, The environmental factors that led to the fluctuations in government R&D budget expenditure were ‘the president’s policy will,’ ‘the National Assembly’s interest,’ ‘priority of the policy agenda,’ ‘public opinion’, ‘technology independence’, and ‘industrialization’. It was derived as a value. This study aims to overcome the disruption of technology and production through securing source technologies in planning and setting agendas for government R&D support policies, and a major shift in policy paradigm such as reorganizing the industrial ecosystem to respond to the era of the 4th industrial revolution. It is a reminder of the need. This can be expected of policy implications that contribute to improving the efficiency of future-related policy decisions and budget allocation.

과학기술의 지식창출과 경제적 성과의 결정요인 분석: 과학기술분야 정부출연연구기관을 중심으로

김학민(Kim, Hakmin),박윤환(Park, Yoonhwan) 서울행정학회 2021 한국사회와 행정연구 Vol.32 No.2

본 연구에서는 국가차원의 지식창출 및 확산, 그리고 활용을 통한 지식가치의 제고를 위해 정부출연연구기관의 지식창출 역량과 창출된 지식이 경제적 성과에 연결되는 흐름을 살펴보았다. 이를 위해 과학기술의 지식창출을 결정하는 요인과 경제적 성과인 기술료 징수액을 결정하는 요인이 무엇인지를 도출하고, 그에 따른 정책적 함의를 제시하였다. 영향 요인들은 크게 지식창출, 혁신기반, 기관특성으로 범주화시켜 구성하였으며, 분석방법으로는 패널 데이터를 이용한 선형회귀모형 추정방법으로 Pooled OLS와 Panel GLS 모형을 활용하였다. 분석결과, 과학기술의 지식창출에는 정부출연금 비중, 연구자 비중, 외국인 연구자 비중, 기초기술연구 특성 여부, 기관의 소재지, 기관장 연임여부, TLO 조직의 인력과 예산비중이 유의미한 요인으로 도출되었으며, 경제적 성과인 기술료 징수액의 결정요인으로는 특허 활용성, 특허 생산성, 정부출연금 비중, 연구자 비중, 정규직 연구자 비중, 기초기술연구 특성 여부, 기관의 소재지가 유의미한 요인으로 도출되었다. In this research, in order to create and disseminate knowledge at the national level, and to improve the value of knowledge through its utilization, the knowledge-creating ability of government-affiliated research institutes and the flow of the created knowledge are connected to economic results. I examined. Therefore, we derived the factors that determine the creation of knowledge of science and technology and the factors that determine the amount of technical fees collected, which is an economic achievement, and presented the policy implications associated with it. The influential factors were broadly classified into knowledge creation, innovation base, and institutional characteristics, and the analysis method used the Pooled OLS and Panel GLS models in the estimation method of the linear regression model using panel data. As a result of the analysis, in order to create knowledge of science and technology, the ratio of government investment is the ratio of researchers, the ratio of foreign researchers, whether it is a characteristic of basic technology research, the location of the institution, and whether to reappoint the director. , The ratio of personnel and budget of TLO organization is derived by significant factors, and the factors that determine the amount of technical fee collection, which is an economic result, are patent utilization, patent productivity, and the ratio of government investment by researchers. The ratio, the ratio of full-time researchers, whether it is a characteristic of existing basic technology research, and the location of the institution were derived as meaningful factors.

Manufacturing Automation System of Freeform Concrete Formwork Using S-LOM Method

심준혁(Joonhyeok Sim),김학민(Hakmin Kim),박건우(Kyunwoo Park),김찬우(Chanwoo Kim),홍대희(Daehie Hong) Korean Society for Precision Engineering 2020 한국정밀공학회지 Vol.37 No.1

오픈소스를 이용한 Windows기반 PC 정보 수집 시스템 개발

송중호(Jungho Song),김학민(Hakmin Kim),윤진(Kim Jin Yoon) 한국정보과학회 2015 한국정보과학회 학술발표논문집 Vol.2015 No.12