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>

變動荷重을 받는 熔接構造材의 疲勞壽命 豫測

김민건,김동열 江原大學校 産業技術硏究所 1998 産業技術硏究 Vol.18 No.-

In this study, about the fatigue life of welded structure material under fluctuation loading, the prediction life which is produced by using the Histogram Recorder System was compared with the experimental life which is produced by the RMC model which is imported by conception of equivalent stress. In thsi result, this is represented few difference by comparing prediction life which is produced by damage analysis depended on Miner's rule, by using the Histogram Recorder System, with experimnetal life which is produced by the RMC load model which is imported by conception of equivalent of stress, therefore fatigue life is easily predicted by using Histogram Recorder System, and result of prediction has equivalent accuracy with other method which is more complex than the Histogram Recorder System. Besides the damage which is produced by stress which is high thirty percentage rank in the stress range of damage inducing, is nearly equal to the damage which is induced the rest of seventy percentage, there fore we can see that damage accumulation which is induced few time overload which is effected welded structure material is great.

산성안개가 내후성강재의 녹형성 및 피로강도에 미치는 영향

김민건,구은희 江原大學校 産業技術硏究所 2002 産業技術硏究 Vol.22 No.B

The purpose of this study is to investigate the effect of acid fog on the rust formation behavior of weathering steel (SMA50) which is used in uncoated bridges. Weathering steel didn't form the passive film under the environment of acid fog(pH5,6), whereas the environment of distilled water formed the protective oxide film. Therefore, the construction of weathering steel under the environment extremely exposed to SOx and NOx which are the main compositions of acid fog is not adequate. Fatigue limits of weathering steel under acid fog environment are remarkably decreased as compared with environment of distilled water. The corrosive constituents in acid fog has piled up the corrosion products on specimen surface and generated the corrosion pits. Because of the high stress concentration arising at this corrosion pit, relatively low fatigue limits were obtained for acid fog specimens.

실린더타입 도어클로저의 구조 및 내구해석

김민건,정구현,박찬원 한국공작기계학회 2004 한국생산제조학회지 Vol.13 No.3

The door closer is a typical system which consists of spring and damper. The door closer is a device to close the door more slowly. The virtual prototypes of cylinder-type door closer are developed. The simulations of virtual prototype are performed to obtain the load history of the guide pin. The structural strength assessment of the guide pin is performed to verify a design safety. The fatigue life and damage of the guide pin are predicted using a FEMFAT 4.3h based on the finite element analysis.

구조용 강재의 부식피로 강도에 미치는 산성안개 및 염화칼슘의 영향

김민건,김명섭 江原大學校 産業技術硏究所 2001 産業技術硏究 Vol.21 No.A

The fatigue strength of SM55C has significantly decreased by 83% compared with atmosphere where distilled exists due to strong erosive action of acid fog. The reason is inferred in a way that strong acid erosive material such as acid fog act and give rise to multi-site crack on the surface. Several fatigue clacks occurred under the acid fog repeat the process of division and unification on the surface and form a long non-propagating crack throughout the circumference of experimented steel. However, in the depth, many parts do not show much trace of unification, and the depth is not as big as the one of normal crack shape. 10% of Cacl2 causes strong erosive reaction to material. Then eventually make the life of fatigue shooter. On the other hand, 20% of Cacl2 beings about oxidized material organic crack closing due to weak erosive reaction.

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.

극저사이클 하중을 받는 구상흑연주철의 초기균열성장에 관한 연구

김민건,임복규,김동열 江原大學校 産業技術硏究所 2002 産業技術硏究 Vol.22 No.A

In this study, extremely low cycle fatigue tests were carried out under push-pull loading conditions using graphite cast iron (GCD). In order to clarify the fatigue fracture mechanism of GCD in an extremely low cycle fatigue regime successive observations of internal fatigue damage were performed. The results obtained are as follows. (1) The process of extremely low cycle fatigue can be classified into three stages which are composed of the generation, growth and coalescence of microvoids inside materials. (2) In an extremely low cycle fatigue regime, microvoids originate from debonding of graphite-matrix interface.

피로한도의 정량평가법과 구상흑연주철에 대한 적용

김진학,김민건 江原大學校 産業技術硏究所 1998 産業技術硏究 Vol.18 No.-

Fatigue tests were performed to examine the 4 parameter method for specimens prepared by various heat treatment which resulted in different mechanical properties. Obtained main results are as follows. Fatigue tests were performed to examine the 4 parameter method for specimens prepared by various heat treatment which resulted in different mechanical properties. Obtained main results are as follows. (1) Samples treated by austempering did not show the expected improvement of fatigue limit although hardness and strength increased. This is attributed to the fact that defect sensitivities of materials increase as increasing of hardness and tensile strength, it is also shown that the graphites acting as stress concentration place become larger by austempering heat treatment than by normal annealing. (2) It is very reasonable to predict the fatigue limit of ductile irons with 4 parameter method based on σ?, H?, ΔK? and √area ?. (3) The half-austempering treatment appeared to be more useful than the full-austempering method to improve the fatigue limit in the spheroidal graphite cast iron with multi defective material.

마이크로홀 드릴링 머신의 개발 및 절삭성능 평가

김민건,유병호 한국공작기계학회 2001 한국생산제조학회지 Vol.10 No.5

In this paper, drill feed mechanism, cutting depth measuring device and sensing buzzer of drill contact were investigated in order to develop the micro-hole drilling machine. Also, measuring device of cutting resistance was developed in order to estimate cutting resistance from change of cutting condition. The results show that extremely-low feed rate(less then 17㎛/s) can be done and cutting depth can be measured by up to 1㎛ with develope drilling machine. Accordingly we could assemble a very cheap micro-hole drilling machine(ø0.05∼0.5mm). Also we got the some properties of cutting performance i.e. under the same condition, cutting torque decreases as increase of spindle speed and rapid feed of drill brings about the inferior cutting state under low spindle speed.