PAN계 탄소섬유의 제조 및 탄화 조건에 따른 특성 분석

이현재,원종성,임성찬,이태상,윤준영,이승구,Lee, Hyun Jae,Won, Jong Sung,Lim, Sung Chan,Lee, Tae Sang,Yoon, Jun Young,Lee, Seung Goo 한국섬유공학회 2016 한국섬유공학회지 Vol.53 No.2

In this study, PAN (polyacrylonitrile)-based carbon fiber was prepared under different carbonization conditions. Carbonization of oxi-PAN fiber was performed under four different temperature conditions. Changes in the characteristics of these carbon fibers prepared under each condition were studied using various analyses. Crystalline characteristics of carbon fiber such as crystallinity and crystal size were analyzed using X-ray diffraction (XRD) and Scherrer's equation, based on the XRD patterns, respectively. The tensile strength and modulus of these carbon fibers were measured through a tensile test. Thermal characteristics were analyzed using a thermogravimetric analyzer (TGA). The result showed that the crystal size and crystallinity of the carbon fibers increased with carbonization temperature. Furthermore, both mechanical strength and thermal resistance were also observed to improve with carbonization temperature. Finally, a relationship between carbonization temperature, thermal properties, and mechanical properties of the carbon fibers was derived.

S-Hippuryl Thioglycolyl Glycine : A New Chromogenic Substrate for Dipeptidyl Carboxypeptidases

이현재,Lee Hyun-Jae Korean Chemical Society 1975 대한화학회지 Vol.19 No.4

Dideptidyl carboxypeptidases와 angiotenisn-coverting enzyme의 새로운 기질불질로서 thiol ester 인 S-Hippuryl thioglycolyl glycine을 합성하였으며, 이 기질에 의한 간편하고도 예민한 효소 활성도의 정량방법을 제시하였다. 이 경우 효소반응 생성물인 thioglycolyl glycine은 반응계중에 첨가한 5,5-dithio-bis-(2-nitrobenzoic acid), DTNB와 쉽게 반응하여 410nm에서 강한 흡광스펙트럼을 갖는 5-thio-2-nitrobenzoic acid(${\varepsilon}M=1.36{\times}10^4$)을 형성함으로서 효소의 새로운 미량정량 방법으로 이용 가치가 크다고 본다. A spectrophotometric assay technique is descriead for the measurement of free SH-groups in the enzyme reaction mixture. The method utilizes a new substrate, S-hippuryl-thioglycolyl-glycine(S-Hip-thioglycol-Gly) which is the basis for a convenient assay of angiotensin-converting enzyme and other dipeptidyl carboxypeptidases. This substrate contains an appropriately located thioester linkage that is hydrolyzed by the converting enzyme and other dipeptidyl carboxypeptidases. One of the products, thioglycolyl glycine, is readily measured by reaction with Ellman's reagent, 5,5'-dithio-bis-(2-nitrobenzoic acid), DTNB, to produce 5-thio-2-nitrobenzoic acid which has a strong absorption band at 410 nm. The method is sensitive (${\varepsilon}M = 1.36{\times}10^4$ at 412 nm) and can be applied as a continuous recording with DTNB present in the enzymatic reaction mixture.

Histidylleucine Hydrolyzing Enzyme : A Dipeptidase From Hog Lung

이현재,박중근,Hyun-Jae Lee,Jung-Keun Park Korean Chemical Society 1975 대한화학회지 Vol.19 No.5

돼지의 폐(lung)로 부터 histidylleucine dipeptide를 가수분해 시키는 효소를 추출 정제 하였으며, 정제된 효소의 비활성도는 $1.6{\mu}moles$/min/mg protein(약 50배 정제)이었다. 이 새로운 dipeptidase의 분자량은 sucrose density gradient 원심침강법에 의하여 측정한 결과 약 80,000 daltons이었으며 효소의 기질 물질로서 요구되는 조건은 방향족 잔기를 갖는 dipeptide를 필요로 하나 histidylleucine을 기질로 사용하였을 경우 $K_m$ 값은 $2{\times}10^{-4}M$이었다. 본문에서는 이효소의 일반적 특성과 그 밖의 생리학적 및 생화학적 기능에 관하여 검토하였다. An enzyme capable of hydrolyzing histidylleucine was purified 50 fold from hog lung. The final preparation hydrolyzed $1.6{\mu}moles$ of histidylleucime per minute per mg of protein. The $K_m$ of the enzyme for the enzyme was found to be $2{\times}10^{-4}M$. The enzyme was required a number of free dipeptides for the substrate specificity, and was inhibited by EDTA and 1,10-phenan-throline. The molecular weight of the enzyme was estimated to be 80,000 daltons from sucrose density gradient sedimentation analysis. The corrected $s_{20,w}$ value was 5.3 S.

딥 러닝 기반의 초해상도 이미지 복원 기법 성능 분석

이현재,신현광,최규상,진성일,Lee, Hyunjae,Shin, Hyunkwang,Choi, Gyu Sang,Jin, Seong-Il 대한임베디드공학회 2020 대한임베디드공학회논문지 Vol.15 No.2

Convolutional Neural Networks (CNN) have been used extensively in recent times to solve image classification and segmentation problems. However, the use of CNNs in image super-resolution problems remains largely unexploited. Filter interpolation and prediction model methods are the most commonly used algorithms in super-resolution algorithm implementations. The major limitation in the above named methods is that images become totally blurred and a lot of the edge information are lost. In this paper, we analyze super resolution based on CNN and the wavelet transform super resolution method. We compare and analyze the performance according to the number of layers and the training data of the CNN.

자연계와 인간 시리즈(II)-자연에 대한 사랑의 화해

이현재,Lee, Hyeon-Jae 한국자연공원협회 1989 한국자연공원 Vol.44 No.-

인삼 유효성분에 관한 생화학적 및 약리학적 연구

이현재,한태룡,김수자 ( Hyun Jae Lee,Tae Ryong Hahn,Soo Ja Kim ) 생화학분자생물학회 1979 BMB Reports Vol.12 No.2

The biochemical efficacy of Panax ginseng was studied with the methanolic extract of ginseng by a new biochemical approach employing a rabbit muscle creatine phosphokinase (CPKase, EC 2.7, 3.1). The study included both effects of ginseng extract on the in vitro activity of CPKase and on tle tissue levels of phosphocreatine and ATP by in vivo administration. In this study, the activity of CPKase was measured in both directions of its reversible reactions with the corresponding coupled enzyme systems, and it was demonstrated that ginseng extract causes a marked acceleration in the rate of the in vitro activity of CPKase up to about two fold and shows a hyperbolic saturation curve in its concentration dependent relative activity profile of CPKase. In addition, from the in vivo experiment with mice, it was also demonstrated that the administration of ginseng extract orally causes an increase in the tissue level of phosphocreatine and thus prevents the decrease in the tissue content of phosphocreatine which goes along with a period of fasting the animals. From the results, it was also suggested that ginseng extract may affects on the energy-linked cellular metabolic reactions by promoting the activity of CPKase and thus causes an efficient utilization of high-energy phosphates for many cellular metabolic activities under the stressful conditions.

광 박테리아 색소체의 고정화에 의한 인위적 광 화학 반응조의 제조 및 응용

이현재,이동희,김수자 ( Hyun Jae Lee,Dong Hee Lee,Soo Ja Kim ) 생화학분자생물학회 1981 BMB Reports Vol.14 No.3

The bacterial chromatophores prepared from R. rubrum was immobilized by polyacrylamide entrapment to provide an efficient photosynthetic reactor for the generation of ATP and the reducing powers. The optimum yield of the immobilized chromatophores was obtained at the monomer concentration of 7.5% with its one-tenth amount of the crossfinking agent, The stability of chromatophores was improved markedly by the immobilization. The immobilized chromatophores showed the broad pH and temperature optimum at the pH range of 6.0 to 8.0 and at 40∼45℃, respectively, The temperature dependent deactivation constants for the native and immobilized chromatophores were estimated to be about 3.5×10-2 and 8.7×10-` per min, respectively, at 40℃. By immobilization, the original chromatophore activities including photophosphorylation of ADP and photoreduction of NAD^+ were increased markedly and the operational stability was also improved. The Km values of the photophosphorylation by the immobilized chromatophores were estimated to be 4.6×10^(-4) M and 2.7×10^(-3) M for ADP and inorganic phosphate, respectively, which were about 15 to 30 times higher than those for the native chromatophores, In addition, in the case of the succinatelinked photoreduction of NAD^+, the immobilization of chromatophores resulted in a marked stimulation, especially by the presence of KCN and oligomycin. Several other properties related to the photochemical reactions mediated by the immobilized chromatophores were also studied and compared with those of the native chromatophores.

조선수리업종 석면노출 근로자들의 흉부방사선상 석면관련 폐질환 소견의 발생양상

이현재,홍영습,손지언,이영일,김상훈,임형준,김정만,김준연,Lee Hyun Jae,Hong Young Seoub,Son Ji Eun,Lee Young Ill,Kim Sang Hoon,Im Hyoung June,Kim Jung Man,Kim Joon Youn 한국생명과학회 2006 생명과학회지 Vol.16 No.1

모 조선수리업에 근무하는 1,086명 중 석면에 노출되는 작업공정에 10년 이상 근무한 근로자 118명을 대상으로 단면조사연구를 수행하였다. 연구대상자들에 대해 흥부방사선검사, 폐기능검사와 미국의 산업안전보건청 석면표준, 의학적 감시 프로그램(OSHA asbestos standard, medical surveillance program)에 따라 국내 실정에 맞게 일부 편집한 설문조사를 시행하였고 아울러 이들의 작업장에 대한 작업환경측정 자료도 분석하였다. 흉부방사선검사상 석면관련 폐질환 소견의 유병율은 118명의 근로자중 16명으로 $13.6\%$였다. 흉부방사선검사상 정상군에 비해 석면관련 폐질환 유소견군에서 유의한 요인들은 폐기능검사상 이상소견, 기침, 가래, 호흡기 질환의 과거력, 근무력이었다. 본 연구 결과를 통해 볼 때 폐기능검사 소견상 이상소견, 기침과 가래의 임상증상을 호소하거나 호흡기질환의 과거력, 20년 이상의 근무력이 있는 근로자에 대해서는 석면관련 폐질환의 엄격한 관리가 필요할 것으로 생각된다. 그리고, 본 연구에서 관련성 여부를 완전히 배제할 수 없었던 요인들에 대해서는 향후 광범위한 전향적 연구를 통하여 연관성을 규명하여 석면노출 사업장의 의학적 감시 프로그램에 적극 활용되기를 기대한다. There was cross-sectional study on investigating the factors related asbestos-related disease on chest radiograph of workers exposed to asbestos in ship repair. According to Occupational Safety & Health Administration asbestos standard, medical surveillance, chest radiologic study, pulmonary function test and medical questionnaire are performed in 118 subjects exposed to asbestos for 10 years or more in ship repair. The sixteen out of 118 subjects $(13.6\%)$ were observed asbestos-related disease finding on chest radiography. Significant factors related to those finding on chest radiography were abnormal pulmonary function test, cough, sputum, past history of respiratory disease, work duration. Workers with Significant factors related asbestos-related disease finding on chest radiography should be managed on a strict program. Further, factors unrelated with asbestos-related disease finding on this study should be evaluated prospectively for medical surveillance program of workers exposed to asbestos.

수중 수제(날개형)를 이용한 만곡하천 제방침식 제어 기술

이현재,최철희,백중철,박상덕,Lee, Hyeon-Jae,Choe, Cheol-Hui,Baek, Jung-Cheol,Park, Sang-Deok 한국수자원학회 2018 물과 미래(한국수자원학회지) Vol.51 No.8

자연계와 인간 시리즈(I)-자연.양생.양기

이현재,Lee, Hyeon-Jae 한국자연공원협회 1989 한국자연공원 Vol.43 No.-

날로 병들어가는 자연과 인간성의 건전한 회복을 촉구하는 일은 오늘의 당면한 우리의 과제입니다. 본지는 뜻있는 필진의 찬동을 얻어 이번호부터 본시리즈를 연재하게 되었습니다. 본회회원은 물론 전국애독자의 관심과 투고를 바라마지 않습니다.