천연 갈변 억제제 개발을 위한 양파,사과 및 감귤 과피 추출물의 항산화 및 갈변 저해 효과

장민선 ( Min Sun Chang ),안세진 ( Se Jin An ),정문철 ( Moon Cheol Jeong ),김동만 ( Dong Man Kim ),김건희 ( Gun Hee Kim ) 한국식품영양학회 2011 韓國食品營養學會誌 Vol.24 No.3

This study was carried out to investigate antioxidative properties of various extracts and antibrowning effects of extracts in apple slices were investigated by ΔE value and PPO relative activity. Apples were cut into 1.5 ㎝ thickness and they were dipped in 1% extract solutions(OW: water extracts of onion, OE: 80% EtOH extracts of onion, AW: water extracts of apple, AE: 80% EtOH extracts of apple, MW: water extracts of mandarin orange peel, ME: 80% EtOH extracts of mandarin orange peel) for 1 min. OW showed higher than the other treatments for total phenolic contents(94.35 ㎎/g), PPO inhibition(74.00%). And the highest DPPH free radical scavenging activity(40.27%) measured in ME. ΔE value of apple slices dipped in MW was 2.37 whereas ΔE value of apple slices dipped in AW was 12.12. These results suggest that onion and mandarin orange peel extracts should be a potential source for controlling browning during storage of apple slices.

Bioconversion of ginsenoside Rc into Rd by a novel α-L-arabinofuranosidase, Abf22-3 from Leuconostoc sp. 22-3: cloning, expression, and enzyme characterization.

Liu, Qing-Mei,Jung, Hae-Min,Cui, Chang-Hao,Sung, Bong-Hyun,Kim, Jin-Kwang,Kim, Song-Gun,Lee, Sung-Taik,Kim, Sun-Chang,Im, Wan-Taek N.V. Swets en Zeitlinger 2013 Antonie van Leeuwenhoek Vol.103 No.4

<P>A novel α-L-arabinofuranosidase (Abf22-3) that could biotransform ginsenoside Rc into Rd was obtained from the ginsenoside converting Leuconostoc sp. strain 22-3, isolated from the Korean fermented food kimchi. The gene, termed abf22-3, consisting of 1,527 bp and encoding a protein with a predicted molecular mass of 58,486 Da was cloned into the pMAL-c2x (TEV) vector. A BLAST search using the Abf22-3's amino acid sequence revealed significant homology to that of family 51 glycoside hydrolases. The over-expressed recombinant Abf22-3 in Escherichia coli BL21 (DE3) catalyzed the hydrolysis of the arabinofuranoside moiety attached to the C-20 position of ginsenoside Rc under optimal conditions of pH 6.0 and 30 C. This result indicated that Abf22-3 selectively converts ginsenoside Rc into Rd, but did not catalyze the hydrolysis of glucopyranosyl groups from Rc or other ginsenosides such as Rb1 and Rb2. Over-expressed recombinant enzymes were purified by two steps with amylose-affinity and DEAE-cellulose chromatography and then characterized. The kinetic parameters for α-L-arabinofuranosidase showed apparent Km and Vmax values of 0.95 0.02 μM and 1.2 0.1 μmol min(-1) mg of protein(-1) against p-nitrophenyl-α-L-arabinofuranoside, respectively. Using a purified MBP-Abf22-3 (10 μg/ml), 0.1 % of ginsenoside Rc was completely converted to ginsenoside Rd within 20 min.</P>

Cu-SiO₂촉매상에서 메탄올의 메틸포메이트로의 탈수소 반응에 관한 연구

김경림,박해경,설용건,이태희,전민기 연세대학교 산업기술연구소 1990 논문집 Vol.22 No.2

Cu-SiO₂촉매상에서 구리의 함량을 달리하며 메탄올을 반응물질로 하여 탈수소 반응을 고정층 연속흐름 반응기에서 행하였다. 조작조건의 범위는 온도 175∼250℃, 압력 ?? 접촉시간 0.013∼0.043g.cat.hr/mL이었다. 구리의 함량에 따라 전화율과 선택도가 달라지고 구리의 함량이 1.5wt.%일 때 메틸포메이트로의 수율이 가장 좋았다. 최적 조작 조건은 온도와 접촉시간이 각각 225℃, 0.033g.cat.hr/mL 부근이었다. 이온 교환법으로 제조된 1.5wt.% Cu-SiO₂촉매상에서 메탄올의 탈수소 반응의 활성화 에너지는 3.73kcal/mol이었다. The dehydrogenation of methanol to methylformate was studied over Cu-SiO₂catalyst prepared by ion-exchange method with the change of copper content in a fixed bed, continuous flow reactor. The ranges of experimental conditions were : at the temperature between 175℃ and 250℃, pressure at ??, and contact time between 0.013 and 0.043g.cat.hr/mL. Conversion and selectivity were changed with Cu content and yield of methylformate showed the highest value with 1.5wt.% Cu. The optimum conditions were 225℃, 0.033g.cat.hr/mL for reaction temperature and contact time, respectively. The activation energy of dehydrogenation of methanol to methylformate was 3.73kcal/mol over 1.5wt.% Cu-SiO₂.

페라이트-마르텐사이트 복합 조직강의 피로한도에 미치는 마르텐사이트 조직형태의 영향

김민건,지정근 강원대학교 산업기술연구소 2000 産業技術硏究 Vol.20 No.B

A study has been made on the behavior of microscopic fatigue crack growth at the stress level of the fatigue limit with ferrite-martensitic structures. For the above purpose, two types of the microstructures were prepared ; one is the microstructure having the ferrite encapsulating the islands of second phase martensite(FEM), the other is the microstructure with the martensite encapsulating the islands of ferrite(MEF). It has been pointed out that the fatigue limits of these microstructures are related to the critical stress at which the microcrack in the MEF microstructure in which the critical crack length would be restricted within the second phase spacing in contrast with the FEM microstruture. However, the fatigue tests shows that no appreciable difference of the fatigue limits among them were recognized. Also, it turned out from the metallographic observations that the micro crack path is very much affected by the microstructures, so that the microcracks grow according to the 3-dimentional situation of its microstructures.

銅 表面의 화학 腐蝕에 의한 蝕刻 패턴 연구

김민건,서봉원 강원대학교 산업기술연구소 2000 産業技術硏究 Vol.20 No.B

In order to observe the pattern forming of copper plate and chemical corrosion reaction, a study on the effect of the process parameters on the formation of micro-pattern by a photochemical etching of copper plate was carried out. The results are as follows : 1) Etching rate increases as the concentration of etchant increases under the regular condition of the temperature by the increasing of diffusion rate to surface. 2) Etching rate increases as the temperature of etchant increases by the fast acting of the material delivery of diffusion to surface under the regular condition of concentration. 3) It was found that etching speed increases as the material delivery of convection rising increased when the aeration speed of etchant increases. This result was from the fact acted by the material delivery of convection rising rather than material delivery of diffusion to the surface.

CRACK 開口變位에 기초한 微小疲勞크랙 전파法則의 考察

김민건,지정근 江原大學校 産業技術硏究所 1993 産業技術硏究 Vol.13 No.-

Bending fatigue tests were carried out on the specimenes with tow different strength levels in order to investigate small crack growth rate. The main results obtained are as follows : (1) Small crack growth law, da/dn = Cσ?a is useful several materials, but is not the rule applicable to all cases generally. (2) When da/dn in several specimens are equal. COD near the crack tip are also nerarly equal. (3) Crack tip opening displacement (CTOD) is the main factor to control the small crack growth rate, and da/dn ? CTOD comes into being between the two. Accordingly, da/dn = c(σ?/σ)?a? shows the small crack growth rate being reflected crack closure phenomenon.

저사이클 피로수명에 영향을 미치는 구상흑연주철의 흑연입자수의 영향

김민건,이병현,유병호 강원대학교 산업기술연구소 2000 産業技術硏究 Vol.20 No.B

Low cycle fatigue life of spheroidal graphite cast iron is determined by the morphological parameters of internal graphite. The aim of this study is to clarify the effect of the number of nodular grain of spheroidal graphite cast iron on low cycle fatigue life. Two specimens that have identical average nodular grain size by changing nodular grain volume fraction and different number of nodular grain count was tested. In this paper, the parameter governing fatigue life through fatigue test, the number of nodular grain seriously affect fatigue life and nodular grain size is no longer governing parameter of it.

임계정류피로크랙의 하한계 전파조건의 정량적 고찰

김민건 江原大學校 産業技術硏究所 2010 産業技術硏究 Vol.30 No.B

Since the propagation of a short fatigue crack is directly related to the large crack which causes the fracture of bulk specimen, the detailed study on the propagation of the short crack is essential to prevent the fatigue fracture. However, a number of recent studies have demonstrated that the short crack can grow at a low applied stress level which are predicted from the threshold condition of large crack. In present study, the threshold condition for the propagation of short fatigue crack is examined with respect to the micro-structure and cyclic loading history. Specimens employed in this study were decarburized eutectoid steels which have various decarburized ferrite volume fraction. Rotating bending fatigue test was carried out on these specimens with the special emphasis on the "critical non-propagating crack length" It is found that the reduction of the endurance limit of their particular micro-structures can be due to the increase of the length of critical non-propagating crack, and the quantitative relationship between the threshold stress σ_(wo) and the critical non-propagating crack length Lc can be written as σ_(wo)^(m) · Lc = C where m,C is constant. Further experiments were carried out on cyclic loading history on the length of critical non-propagating crack. It shown that the length of critical non-propagating crack is closely related to cyclic loading history.

SNCM강의 피로균열의 발생 및 전파속도에 미치는 질화처리의 영향

김민건,이상호 강원대학교 산업기술연구소 2003 産業技術硏究 Vol.23 No.A

Effect of nitriding on fatigue crack imtiation and growth rate has been studied on SNCM. Specunens were nitnded for 15 hr at 860℃. The fatigue limit of nitrided specunens was superior to that of annealed(860℃. 15 hr) specimens. Based on detailed observations of slip band and micro crack initiation, it is concluded that the excellent fatigue limit of nitrided specunens is attnbuted to improved slip initiation resistance by nitriding The charactenstic of fatigue crack growth rate of nitrided specimens was investigated and compared with those of annealed specunens It was found that by nitriding the crack growth rate was markedly decreased and the threshold stress intensity factor range was improved. It is concluded that the excellent fatigue limit of nitnded specunens is also attributed to unproved fatigue crack growth rate and threshold stress intensity factor range by nitriding

섬진강수계에서 심미학적 필요유량

김민환,송창수,박병균 호남대학교 산업기술연구소 2001 산업기술연구논문집 Vol.9 No.-

본 연구에서 섬진강 수계의 주요지점에 대해 심미학적 필요유량을 결정하였다. 심미학적 필요유량은 하천의 주요경관과 더불어 하천의 수면폭, 유속, 수심, 유량과 같은 수리특성을 만족해야 한다 주요지점의 심미학적 필요유량은 다음과 같다. 섬진강 본류에 위치한 쉼터휴게소, 두가세월교, 압록유원지의 필요유량은 각각 15.21CMS, 29.9CMS, 40.39CMS이고, 남원국민관광단지와 태안교의 필요유량은 각각 9.0CMS, 8.71CMS로 평가되었다. In this study, aesthetic necessary discharge is determined in Sumjin River system. It is satisfying to hydraulic characteristics - the width of river, velocity, water depth, and discharge with main scenery of river. As a result of this study, Suimtea Resort, Dugasewol Bridge and Aprok Resort which are located in Sumjin main River have aesthetic necessary discharge of 15.21CMS, 29.9CMS, and 40.39CMS respectively. Those of Namwon National Resort and Taean Bridge are calculated at 9.0CMS and 8.71CMS respectively.