• 한국미생물·생명공학회지
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• 제8권3호
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• pp.193-198
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• 1980

한국내 양조장을 둘러싼 미생물 환경 즉 신선한 포도즙, 발효중의 포도즙, 앙금, 숙성중의 포도주 및 병속의 사과주들 속에서 많은 수의 malo-lactic 박테리아가 검출되었다. 이들의 환경 속에서 분리된 1363 주의 malo-lactic 균주들 가운데 우수한 4균주를 선택하여 분류한 결과 Leuconostoc oenos 종에 속하는 3균주인 A-35, B-30, C-13과 Lactobacillus Plantarum종에 속하는 1균주 D-11을 얻었다. 이들 가운데 A-25 균주는 malo-lactic 박테리아로서 널리 이용되고 있는 Leu. oenos ML34와 거의 동등한 사과산 이용능력을 보였다. 실험적인 양조를 통하여 이 A-25 균주의 malo-lactic 효과를 확인하였다.

• Steel and Composite Structures
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• 제44권6호
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• pp.817-828
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• 2022

In this study, considering dissipated energy in fracture process zone (FPZ), a novel criterion based on maximum strain energy release rate (SER) for orthotropic materials is presented. General case of in-plane loading for cracks along the fibers is assumed. According to the experimental observations, crack propagation is supposed along the fibers and the reinforcement isotropic solid (RIS) concept is employed as a superior model for orthotropic materials. SER in crack initiation and propagation phases is investigated. Elastic properties of FPZ are extracted as a function of undamaged matrix media and micro-crack density. This criterion meaningfully links between dissipated energy due to toughening mechanisms of FPZ and the macroscopic fracture by defining stress intensity factors of the damaged zone. These coefficients are used in equations of maximum SER criterion. The effect of crack initiation angle and the damaged zone is considered simultaneously in this criterion and mode II stress intensity factor is extracted in terms of stress intensity factors of damage zone and crack initiation angle. This criterion can evaluate the effects of FPZ on the fracture behavior of orthotropic material. Good agreement between extracted fracture limit curves (FLC's) and available experimental data proves the ability of the new proposed criterion.

• Journal of Microbiology and Biotechnology
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• 제25권7호
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• pp.1093-1100
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• 2015

Acetate and lactate in growth media are detrimental to the production of Thermus maltogenic amylase (ThMA), a heterologous protein, as well as to the growth of recombinant Escherichia coli. Only 50 mM of acetate or 10 mM of lactate reduced 90% of specific ThMA activity. In this study, mutant E. coli strains blocked in the ackA-pta or ackA-pta and ldh pathways were created, characterized, and assessed for their culture performace in 300 L-scale fermentation. The ackApta and ldh double-mutant strain formed significantly less lactate and acetate, and produced a concomitant increase in the excretion of pyruvate (17.8 mM) under anaerobic conditions. The ackA-pta mutant strain accumulated significant acetate but had an approximately 2-fold increase in the formation of lactate. The ackA-pta and ldh double-mutant strain had superior overall performance in large-scale culture under suboptimal conditions, giving 67% higher cell density and 66% higher ThMA activity compared with those of the control strain. The doublemutant strain also achieved a 179% improvement in volumetric ThMA production.

• 한국공간구조학회논문집
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• 제9권2호
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• pp.77-82
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• 2009

ETFE 막재는 Ethylene Tetra Fluoro Ethylene의 약자로 색깔이 없고, 투명한 필름 막이다. ETFE 필름의 장점은 내화학성이 있고, 잘 접히지 않으며, 매우 가볍운 재료라는 것이다. 필름의 두께는 50마이크로 미터에서 300 마이크로 미터 두께가 주로 사용되고, 직포가 없어며 햇빛 투과율이 우수하고 재료의 강도는 다른 막재에 비해서 낮다. ETFE 막재의 인장강도는 40MPa에서 60MPa 정도이고, 인장 변형도는 약 200%에서 400% 정도이다. 본 논문에서는 ETFE 필름 막재의 역학적특성 시험을 수행하였다. 인장 시험으로 부터 인장 변형도, 인장 강도, 응력 변형도 곡선을 구하였고, ETFE 막재의 항복 강도를 결정하여 탄성계수를 구하였다. 그리고 온도하중에 의한 응력-변형도 특성과 반복하중에 대한 필름의 역학적 특성을 분석하였다.

• 한국운동역학회지
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• 제17권1호
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• pp.121-127
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• 2007

Muscle force produced by muscle fibers is transmitted to bones via tendinous structures(aponeuroses and tendon), resulting in joint(s) movement. As force-transmitting elements, mechanical behavior of aponeuroses and tendon are closely related with the function of muscle-tendon complex. The purpose of this study was to determine strain characteristics of aponeuroses for in-vivo human soleus muscle during submaximal voluntary contractions using an advanced medical imaging technique, velocity-encoded phase-contrast magnetic resonance imaging (VE-PC MRI). VE-PC MRI of the soleus muscle-tendon complex was acquired during submaximal isometric plantarflexion contraction-relaxation cycle (n = 7), using 3.0T Trio MRI scanner(Siemens AG, Malvern, MA). From the VE-PC MRI containing the tissue velocity in superior-inferior direction, twenty regions of interest(20 ROI; 10 on the anterior aponeurosis and 10 on the posterior aponeurosis) were tracked. During the isometric plantarflexion contraction-relaxation cycle, velocity and displacement profiles were different between the anterior and posterior aponeuroses, indicating heterogeneous strain behavior along the length of the leg. The anterior aponeurosis elongated while the posterior aponeurosis shortened during the initial phase of the contraction. Moreover, strain behavior of the posterior aponeurosis was different from that of the Achilles tendon. Possible explanation for the observed variations in strain behavior of aponeuroses was investigated with morphological assessment of the soleus muscle and it was found that the intramuscular tendinous structures significantly vary among subjects. In conclusion, the heterogeneous mechanical behavior of the soleus aponeuroses and the Achilles tendon suggests that the complexity of skeletal muscle-tendon complex should be taken into consideration when modeling the complex for better understanding of its functions.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권3호
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• pp.173-178
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• 2003

To improve the erythritol productivity of Penicillium sp. KJ81, mutants were obtained using UV irradiation and NTG treatment Among these mutants, Penicillium sp. KJ-UV29 revealed no morphological changes, yet was superior to the wild strain in the following three points: (1) Penicillium sp. KJ-UV29 produced more erythritol than the wild strain under the same conditions, (2) no foam was produced during cultivation, unlike the wild strain, and (3) the mutant produced a Significantly lower amount of glycerol. Penirillium sp. KJ-UV29 produced as much as 15.1 g/L of erythritol, whereas the wild-type Penirillium sp. KJ81 only produced 11.7 g/L. Penicillium sp. KJ-UV29 only generated 6.1 g/L of glycerol, compared to 19.4 g/L produced by the wild strain. When investigating the optimal culture conditions for erythritol production by the mutant strain Penicillium sp. KJ-UV89, sucrose was identified as the most effective carbon source, and the mutant was even able to produce erythritol in a 70% sucrose-containing medium, although a 30% sucrose medium exhibited the highest productivity. The production of erythritol by Penirillium sp. KJ-UV29 was also significantly increased by the addition of ammonium carbonate, potassium nitrate, and sodium nitrate. Accordingly, under optimal conditions, Penicillium sp. KJ-UV29 produced 45.2 g/L of erythritol in a medium containing 30% sucrose, 0.5% yeast extract, 0.5% (NH$_4$)$_2$C$_2$O$_4$, 0.1% KNO$_3$, 0.1% NaNO$_3$, and 0.01% FeSO$_4$ with 1 vvm aeration and 200 rpm agitation at 37$^{\circ}C$ for 7 days in a 5-L jar fermentor.

• 한국결정성장학회지
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• 제20권5호
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• pp.232-236
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• 2010

SiC 세라믹스는 가볍고, 우수한 고온 강도 및 온도 안정성을 지니고 있어 고온 구조용 디바이스에 많이 응용되고 있다. 본 논문에서는 분자동역학을 이용하여 다양한 온도에서 SiC 결정의 탄성율 특성을 분석하고자 하였다. 이를 위하여 SiC 결정을 모델링하여 구성 원자 사이에 Tersoff 포텐셜을 적용하고, 분자동역학 프로그램인 LAMMPS S/W를 이용하여 상온부터 $1,250^{\circ}C$까지 응력-변위 거동(stress-strain behavior) 및 탄성율 변화를 분석하였다. 본 연구의 결과, SiC 결정은 잘 알려진 바와 같이 저온에서 탄성변형 특성을 보이지만, $1,000^{\circ}C$ 이상의 고온에서 높은 변위를 인가할 경우, 약간의 소성 변형 특성을 보이는 것으로 나타났다. 또한 상온부터 $1,250^{\circ}C$까지 온도가 증가함에 따라 SiC 결정의 탄성율은 약 475 GPa 부터 425 GPa의 범위에서 변화하는 것으로 분석되었다.

• 한국융합학회논문지
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• 제12권11호
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• pp.403-410
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• 2021

본 논문은 대체식품 및 화장품 원료로 사용되는 미강을 발효를 통해 기능성과 경쟁력을 증가시키는 것을 목표로 하였다. 5종류의 누룩에서 분리한 Saccharomycopsis fibuligera 50종의 균주 중 효소 활성이 우수한 6균주와 표준균주를 이용한 발효미강물의 𝛼-amylase, CMCase, 𝛽-glucosidase, protease 등의 효소 활성을 통해 비교한 결과, A8균이 KCTC 7806 균주에 비하여 13.7%, 21.1%, 50.3%, 10.0%의 우수한 효소 활성을 보였다. 발효의 결과지표로서 ABTS, DPPH 검사를 시행한 결과, A8으로 발효한 미강이 KCTC 7806 균주로 발효한 미강에 비하여 1.12배, 1.28배의 항산화능이 있음을 확인하였다. 본 논문으로, S. fibuligera 표준균주인 KCTC 7806 보다 우수한 S. fibuligera A8 균주를 확인할 수 있었다. 또한, 선행연구과제의 항염활성 및 항독성 결과와 더불어 우수한 효소 활성과 항산화능 결과를 통해 S. fibuligera A8 균주를 통한 미강 발효물이 대체식품 및 화장품 원료로서의 기능성과 가격 경쟁력을 증가시킬 수 있음을 확인하였다.

• Journal of Microbiology
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• 제42권3호
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• pp.169-173
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• 2004

Enterobacter cloacae (strain PR2/7), a genetically modified endophyte(GME) in citrus plants, carrying different plasmids (pEC3.0/18, pCelE, pEglA and pGFP), was inoculated into Citrus sinensis seedlings under greenhouse conditions. The impact of this on the indigenous bacterial endophytic community was studied by analyses of 2 different morphologic groups. The germination rates of inoculated seeds were evaluated in greenhouse, and plasmid stability under in vitro conditions. Results demonstrated a great and diverse endophytic community inside plants, and specialization in tissue colonization by some bacterial groups, in different treatments. Shifts in seed germination rate were observed among treatments: in general, the PR2/7 harboring pEglA bacterial- clone significantly reduced seed germination, compared to the PR2/7 harboring pEC3.0/18 clone. This suggests that the presence of the pEglA plasmid changes bacteria-seed interactions. The endophytic community of citrus seedlings changed according to treatment. In seedlings treated with the PR2/7 with pEglA clone, the population of group II decreased significantly, within the context of the total endophytic community. These results indicate that the application of GMEs induces shifts in the endophytic bacterial community of citrus seedlings.

• 한국균학회지
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• 제36권1호
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• pp.51-57
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• 2008

식용과 약용버섯으로서 이용가치가 높은 것으로 알려진 먹물버섯(C. comatus)에 대하여 보다 우수한 인공재배법을 개발하고 자실체의 형태적 특성에 대한 연구 결과는 다음과 같다. 먹물버섯속균 5개 균주 중에서 C. comatus균인 CM 980301 균주를 우량균주로 선발하였으며, 먹물버섯(C. comatus: CM 980301)자실체를 생산하기 위한 우수 배지는 종균용으로 밀곡립배지를 사용하고, 먹물버섯을 볏짚 발효배지에 인공재배 하였을 때 $24{\sim}28^{\circ}C$에서 균배양은 종균 접종 후 15일, 복토 후 13일이 소요되었으며, 원기형성 및 초발이는 $20{\sim}24^{\circ}C$에서 $10{\sim}11$일이 소요되었고, 버섯생육은 $20{\sim}24^{\circ}C$에서 $7{\sim}8$일이 소요되었다. 먹물버섯 (CM 980301)의 수확적기는 갓이 피기 전으로 자실체 경도는 갓 $102{\sim}169\;g/cm^2$, 대 $126{\sim}182\;g/cm^2$으로 단단하였고, 인공재배한 수량성은 $37.7kg/3.3m^2$, 개체중 17.9 g이었다.