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>

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.

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.

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

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.

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.

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.

Cyclosulfamuron과 Pyribenzoxim의 莖葉處理에 따른 논 雜草 防除效果에 관한 硏究

金健敏,金武成,盧泳德 慶熙大學校 1997 論文集 Vol.26 No.-

Experiments were carried out to evaluate weed control performance of Cyclosulfamuron and Pyribenzoxim by foliar application, especially for direct seeded rice. In addition, the combinations of the herbicides and water managements were tested for the improvement of the herbicidal activity. Herbicidal effect of Cyclosulfamuron was excellent for B. tripartita, B, frondosa, fair or fairly good for A. indica, and C. cerotinus, and good for E. crus-galli, L. prostrata, S. juncoides, and A. keisak. Herbicidal effect of Pyribenzoxim was excellent for B. tripartita, B. fonndosa, A. keisak, and A. indica, fairly good for E. crus-galli, L. prostrata and poor for s. juncoides, and C. cerotinus. The foliar treatment of two herbicides were the most effective when irrigated 3 days after treatments. The herbicidal effects became poor when saturated condition was maintained, especially E. crus-galli and S. jucoides. Both Cyclosulfamuron and Pyribenzoxim were very effective for the control of B. tripartita and frondosa even under very low concentrations. But the higher rates of Pyribenzoxim are to be used for the better control of E. crus-galli and L. prostrata. Combination treatments of the two herbicides could extended the weed control spectrum. In addition the combination treatments had some positive effects in controlling L. prostrata, S. juncoides and A. keisak