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Al-Mg-Si계 알루미늄 합금 판재 마찰교반접합부의 결정 방위 분포에 대한 용접후열처리의 영향
이광진,Lee, Kwang-Jin 대한용접접합학회 2009 대한용접·접합학회지 Vol.27 No.6
Friction stir welding (FSW) was carried out for Al-Mg-Si series aluminum alloys which are being used for automotive body structure. Consequently, Post weld heat treatment (PWHT) was applied to the friction stir welds to evaluate the effect of the paint baking process which is one of the automotive fabrication process on friction stir welded zone (FSWZ) in 443K for 1.2Ks. Grain structure and its crystal orientation distribution was measured about both the as welded specimens and the post weld heat treated specimens. An optical microscope (OM) and an field emission scanning electron microscope (FE-SEM) was used for observing the grain structure and measuring its crystal orientation distribution, respectively. Changes on the grain structure and its crystal orientation distribution were not detected. From the present results, it was confirmed that the paint baking process after FSW do not affect on the grain structure and its crystal orientation distribution of FSWZ. The comprehensive investigations will be performed for various automotive aluminum alloys manufactured by different processes, in the future.
이광진,김형자,Kwang-Jin, Lee,Hyung-Ja, Kim 한국기계가공학회 2004 한국기계가공학회지 Vol.3 No.3
The sub-surface stress field beneath the spur gear's contact surface in lubricated condition has been analysed. The surface pressure was obtained by the elasto-hydrodynamic lubrication analysis using the accurate geometric clearances around the contact region of the teeth. The sub-surface stress field was calculated by using the Love's rectangular patch solution. The analysis results show that the sub-surface stress distribution is quite dependent on the surface pressure distribution. The pattern of sub-surface stress field is similar to that of the external load. The depth where the maximum effective stress occurs is not proportional to the intensity of the external load.
A6061-T6/AZ31 이종금속 마찰교반접합부의 기계적 특성에 미치는 툴 삽입 위치의 영향
이광진,김상혁,Lee, Kwang-Jin,Kim, Sang-Hyuk 대한용접접합학회 2012 대한용접·접합학회지 Vol.30 No.5
Butt-joints of A6061-T6 and AZ31 plates were successfully manufactured by using a friction stir welding method. Off-set free joints and off-set joints were fabricated to investigate the effect of the tool plunge position on the mechanical properties of the joints. Hardness test, tensile test and charpy impact test was performed to evaluate the mechanical properties of the joints. Off-set condition resulted in increase of mechanical properties of the joints. The variation of the hardness distribution in the SZ was also stabilized in the off-set condition. Tensile strength of the off-set joint was about 85% against to that of the AZ31 base metal. Impact absorption energy by Charpy-Impact-Test of the off-set joint also increased by almost 2 times against to that of the AZ31 base metal.
마찰교반용접(FSW) 및 마찰교반처리(FSP)의 최신 연구개발 동향
이광진,Lee, Kwang-Jin 대한용접접합학회 2013 대한용접·접합학회지 Vol.31 No.2
The latest research & development trend on friction stir welding and friction stir processing technologies presented in the international symposium, 'Friction Stir Welding & Processing VII'. Papers and presentations about high temperature materials such as advanced high strength steel, stainless steel and titanum alloy shoot up this year. Papers on modeling of metal flow and control of process parameters also increased. The FSP technologies for manufacturing of carbon materials reinforced metal matrix composites were reported, too.
이광진,김상혁,권의표,손규송,Lee, Kwang-Jin,Kim, Sang-Hyuk,Kwon, Eui-Pyo,Son, Kyu-Song 대한용접접합학회 2014 대한용접·접합학회지 Vol.32 No.2
Friction stir welding (FSW) was successfully performed about 900MPa grade Twinning Induced Plastisity (TWIP) steel. A PCBN tool with convex-type shoulder was applied. Optimal process conditions were deduced. Microstructure and mechanical properties such as hardness, tensile strength and impact absorbed energy were observed and evaluated, respectively. An optical microscope (OM) and a field emission scanning electron microscope (FE-SEM) was selected for observing the grain structure.
이광진,정영수,Lee, Kwangjin,Jung, Youngsoo 한국건설관리학회 2016 건설관리 : 한국건설관리학회 학회지 Vol.17 No.6
과거 1960~70년대에 급격한 경제발전으로 인하여 국내에는 수많은 건물이 건설되었으며, 특히 2000년 이후에는 대형화, 첨단화된 수많은 건물들이 건설이 되고 있다. 이러한 건물의 전 생애주기 비용 (Life Cycle Cost) 중, 운영 및 유지관리 단계 비용은 전체의 약 85%를 차지 (Teicholz 2004)하고 있어 건축물에 대한 효율적인 자산관리가 강조된다. 하지만 운영 및 유지관리 단계에서 필요한 정보들은 초기 기획 단계부터 설계, 시공 단계를 넘어오면서 각각의 정보들의 호환이 부족하다. 단계를 거듭할수록 정보에 대한 가치는 증가하지만 정보의 상호 호환의 부족으로 인하여 비효율적인 부분이 발생하고 있다 (Foster 2011). 본 연구에서는 먼저 발주자 관점에서 자산관리의 주요 업무기능을 3개의 대분류와 19개의 중분류로 도출하였다. 다음으로는 도출한 항목들을 바탕으로 자산관리 업무량의 비중, 자산관리 업무별 소요 데이터의 비중, 그리고 생애주기 단계별로 발생하는 데이터의 비중에 대한 평가방법론을 제안함으로써, 효율적인 운영 및 유지관리를 위한 방안을 제안하였다. 마지막으로, 제안된 방법론은 공공 및 민간 기업의 사례를 바탕으로 적용성을 검토하였다. In the 1960s and 1970s when Korea experienced rapid economic growth, a considerable number of buildings were constructed in the country. And since 2000, a large number of sizable and complex buildings have been being built. Specifically, as the operation and maintenance cost alone accounts for 85% of the life cycle cost of a building, efficient Facility Management (FM) is required. However, data needed in the operation and maintenance phase are not sufficiently exchangeable with data created in other phases like the planning, design and construction phases. The upper phase has higher value of data but data exchange rate is low, resulting in inefficiency. To this end, this research derived major business functions for facility management: three categories and 19 detailed functions in classification from owner's perspective. Based on the derived items, this research proposes a methodology to evaluate the 'FM Workload', 'Facility Management (FM) Data', and 'FM Data Created in Engineering and Construction Phases' thereby analyzing plans for efficient operation and maintenance. The applicability of proposed methodology was tested by examining real-world cases of public and private companies.
On-line Screening HPLC-ABTS<sup>+</sup> Assay을 이용한 산청목으로부터 Salidroside의 분리 및 생물활성 분석
이광진,송나영,마진열,Lee, Kwang Jin,Song, Na-Young,Ma, Jin Yeul 한국생물공학회 2014 KSBB Journal Vol.29 No.2
Acer tegmentosum was a traditional Korean herbal medicine showing various pharmacological activities. In this work, A. tegmentosum were extracted with boiling water and then successively partitioned with dichloromethane, ethyl acetate, n-butyl alcohol (n-BuOH), and water. Salidoside, the target compound, was purified in n-BuOH phase using a chromatography method. For the analysis of salidoside, TLC and LC-MS were used as well as on-line screening $HPLC-ABTS^+$ assay with three different wavelength of 254, 280, and 320 nm. An amount of 1.34 g of salidoside were obtained in n-BuOH phase fromAcer tegmentosum was a traditional Korean herbal medicine showing various pharmacological activities. In this work, A. tegmentosum were extracted with boiling water and then successively partitioned with dichloromethane, ethyl acetate, n-butyl alcohol (n-BuOH), and water. Salidoside, the target compound, was purified in n-BuOH phase using a chromatography method. For the analysis of salidoside, TLC and LC-MS were used as well as online screening $HPLC-ABTS^+$ assay with three different wavelength of 254, 280, and 320 nm. An amount of 1.34 g of salidoside were obtained in n-BuOH phase from 3 kg of dry biomass. The on-line screening $HPLC-ABTS^+$ assay is rapid and efficient tool to search bioactivity from A. tegmentosum. 3 kg of dry biomass. The on-line screening $HPLC-ABTS^+$ assay is rapid and efficient tool to search bioactivity from A. tegmentosum.
정규모집단에서 다섯수치요약의 피셔 정보행렬에 관한 연구
이광진(Kwang-jin Lee) 한국자료분석학회 2022 Journal of the Korean Data Analysis Society Vol.24 No.3
메타분석 과정에서 보면 대부분의 개별연구들은 {표본평균, 표본표준편차; 표본크기} 형태의 정보를 제공하고 있다. 이는 모수에 대한 추정값과 이의 표준오차, 신뢰구간, 가설검정의 근거가 된다. 그러나 일부에서는 다섯수치요약인 {최소값, 제1사분위수, 중위수, 제3사분위수, 최대값; 표본크기}의 정보만 주어진 것들이 있다. 이런 경우 메타정보의 최대 활용을 위해서는 우선 정보의 통일화 작업이 선행되어야 한다. 대부분 {표본평균, 표본표준편차; 표본크기}의 형태로 통일시킨다. 이미 여러 선행연구들에서 정규모집단 가정 하에서 다섯수치요약 정보로부터 모평균과 모표준편차를 추정하는 여러 방법들이 제시되어 왔다. 이 방법들의 성능비교 연구들 중에서 최근 Lee(2022)는 최대우도추정법을 제안하며 그의 우수성을 보인 바 있지만 이 추정값의 표준오차의 특성들에 관한 연구들은 제시하지 못하였다. 이에 본 연구에서는 정규모집단 가정 하에서 다섯수치요약 정보에 근거한 최대우도추정값의 표본오차 추정을 위해 로그우도함수, score함수, 피셔 정보행렬을 대수적으로 먼저 유도하고, 이를 이용하여 R에서 쉽게 이들을 쉽게 계산하는 함수를 만들었다. 이를 이용한 모의실험을 통해 최대우도추정값의 표준오차 추정값의 특성을 파악하였다. 아울러 다섯수치요약 정보들의 관찰된 피셔 정보행렬들을 계산한 후 충분통계량인{표본평균, 표본표준편차; 표본크기}에 담긴 정보행렬들과 비교하고 상대효율을 살펴보았다. In the meta-analysis, most individual research provide information in the form of {sample mean, sample standard deviation; sample size}. This is the basis for the estimate of the parameter, its standard error, confidence interval, and hypothesis test. However, in some cases, only ‘five-number summary’ information {minimum, first quartile, median, third quartile, maximum; sample size} is given. In this case, for maximum utilization of meta-information, the work of unifying information must be preceded. In most cases, it is transformed in the form {sample mean, sample standard deviation; sample size}. Several previous studies have already suggested several methods of estimating the population mean and population standard deviation from the five-number summary under the assumption of a normal population. In performance comparison studies of these methods, Lee(2022) recently proposed the maximum likelihood estimation method and showed the superiority of it, but studies on the characteristics of the standard error of the estimates were not presented. Therefore, in this study, in order to estimate the standard error of the maximum likelihood estimate(mle) based on the five-number summary, the log-likelihood function, the score function, and the Fisher information matrix(FIM) are first derived algebraically under the assumption of a normal population, and using these we create a function that computes them easily in R. Through a simulation using these, the characteristics of the standard error of the mle are identified. In addition, after estimating the FIM of the five-number summary, it was compared with the FIM of sufficient statistics and the relative efficiency was examined.