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        검색결과 591

        41.
        2020.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A γ-aminobutyric acid (GABA) producing microorganism was isolated from Sun-Tae Jeotgal, a Korean traditional fermented seafood. Two thousand presumptive lactic acid bacteria (LAB) isolates were screened for GABA production by thin layer chromatography. One isolate, T118, produced GABA profusely, and identified as Lactobacillus brevis. Growth of Lb. brevis T118 was examined during 120 h cultivation in MRS broth under different conditions. Lb. brevis T118 grew well at 30-37℃, initial pH of 4-7, and up to 5% NaCl (w/v). A gene, gadB, encoding glutamate decarboxylase (GAD) was cloned by PCR. gadC encoding a glutamate/GABA antiporter was cloned and gadC located immediately upstream of gadB, indicating gadCB operon structure. The operon structure was confirmed by reverse transcription (RT)-PCR. gadB was overexpressed in Escherichia coli BL21 (DE3) and recombinant GAD was purified. The size of recombinant GAD was 54.4 kDa by SDS-PAGE, which matched well with the calculated size from the nucleotide sequence.
        4,000원
        42.
        2020.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A new WRKY transcription factor gene was isolated by ESTs screening from a cDNA library of suspension cultured cells of Sweet potato (Ipomoea batatas). The 2,285 bp cDNA fragment, IbWRKY, was sequenced, from which a 505 amino acid residue protein was deduced. A search of the protein BLAST database identified significant similarity to other plant WRKY31 protein sequences. RT-PCR analysis showed expression patterns of IbWRKY31 in various intact tissues and suspension cultured cells of Sweet potato, and in leaves exposed to different stresses. The IbWRKY31 gene was highly expressed in suspension cultured cells. In leaf tissues, IbWRKY31 showed strong expression during salicylic acid and methyl jasmonate treatments. Expression of IbWRKY31 was also induced under various abiotic stress and pathogen infection conditions, such as wounding, H2O2, MV, PEG, NaCl, and bacterial pathogen infection. These results suggest that IbWRKY31 is involved in plant responses to various stress conditions, such as abiotic stresses and pathogen infection through a defense signaling pathway.
        4,000원
        43.
        2020.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In a previous paper, ambient vibration tests were conducted on a cable stayed bridge with resilient-friction base isolation systems (R-FBI) to extract the dynamic characteristics of the bridge and compare the results with a seismic analysis model. In this paper, a nonlinear seismic analysis model was established for analysis of the bridge to compare the difference in seismic responses between nonlinear time history analysis and multi-mode spectral analysis methods in the seismic design phase of cable supported bridges. Through these studies, it was confirmed that the seismic design procedures of the “Korean Highway Bridge Design Code (Limit State Design) for Cable Supported Bridges” is not suitable for cable supported bridges installed with R-FBI. Therefore, to reflect the actual dynamic characteristics of the R-FBI installed on cable-supported bridges, an improved seismic design procedure is proposed that applies the seismic analysis method differently depending on the seismic isolation effect of the R-FBI for each seismic performance level.
        4,000원
        44.
        2020.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, a field bridge test was conducted to find the dynamic properties of cable supported bridges with resilient-friction base isolation systems (R-FBI). Various ambient vibration tests were performed to estimate dynamic properties of a test bridge using trucks in a non-transportation state before opening of the bridge and by ordinary traffic loadings about one year later after opening of the bridge. The dynamic properties found from the results of the tests were compared with an analysis model. From the result of the ambient vibration tests of the cable supported bridge with R-FBI, it was confirmed that the dynamic properties were sensitive to the stiffness of the R-FBI in the bridge, and the seismic analysis model of the test bridge using the effective stiffness of the R-FBI was insufficient for reflecting the dynamic behavior of the bridge. In the case of cable supported bridges, the seismic design must follow the “Korean Highway Bridge Design Code (Limit State Design) for Cable supported bridges.” Therefore, in order to reflect the actual behavior characteristics of the R-FBI installed on cable-supported bridges, an improved seismic design procedure should be proposed.
        4,200원
        48.
        2020.06 구독 인증기관 무료, 개인회원 유료
        In this study, we investigated culturable bacterial abundance in various crops. Total culturable aerobic bacteria in tomato plants were enumerated on NA and it showed that the amounts of viable bacterial cells were changed among the different parts of the plants (roots, stems, and fruits), ranging between log 1 and 4 per g sample. To investigate the bacterial abundance dynamics in different crops, culturable aerobic bacterial cell numbers were enumerated on NA and compared between the samples (tomato fruit, sesame leaf, and green onion) harvested freshly from one field trial (Yangsan, Korea). In this trial, the number of total culturable aerobic bacteria of the samples were 8 times higher in sesame leaves and green onions compared to the tomato fruits in the field. Interestingly, culturable aerobic bacteria on MRS were only found in sesame leaves, whereas lactic acid bacteria were not detected in tomato fruit and green onion samples in this field. We also found that the field location (Yangsan, Gangneung, or Busan) influenced the number of culturable aerobic bacteria on the surface of the crops. Tomato samples freshly harvested from the different field locations were tested and showed that the amounts of culturable aerobic bacteria on NA and MRS agar were significantly different based on the field locations of the samples. Finally, lactic acid bacteria were isolated from all the tomato and sesame leaf samples used in this study, showing 20 and 28 morphological diversity. With these isolates, we will be able to conduct further biological and functional investigation to develop a new probiotic strain originated from the crops in Korea.
        4,000원
        49.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Porcine epidemic diarrhea virus (PEDV) infects all-age pigs and causes enteric diseases. Genetic diversities in isolates been reported from each country, and those diversities highlighted in pathogenicity and vaccine. In this manuscript, we are reporting of new PEDV isolation in Korea, and with genetic characteristics. Our new isolate belongs to G2b and put the name as CNUP6-2018.
        4,000원
        50.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Canine parvovirus type-2 (CPV-2) has been reported worldwide as the main agent associated with acute hemorrhagic enteritis, resulting in high morbidity, especially in young dogs. CPV-2 has three genetic variants, 2a, 2b, and 2c. Here, we report three cases of canine parvovirus enteritis associated with CPV-2a (2 samples) and -2c (1 sample) infections that occurred in three young dogs suffering from enteritis. Isolates from dog diarrheic fecal samples were sequenced by polymerase chain reaction (PCR) and identified as two types of CPV-2a and one type of CPV-2c. This work constitutes the first isolation and genetic characterization of CPV-2c in the Republic of Korea.
        4,000원
        51.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        동소동속종인 팥나방(Matsumuraeses phaseoli)과 어리팥나방(M. falcana)(나비목: 잎말이나방과) 사이에 교잡 가능성을 알아보기 위해서 실험실에서 인위적으로 두 종을 교잡시켰다. 두 종의 암수를 교차하여 교미시켰을 때, F1 잡종세대가 발생하였다. 두 잡종세대 집단을 집단 내 및 집단 간 암수를 교차하여 교미시킨 경우들에서, 팥나방 암컷과 어리팥나방 수컷이 교잡되어 생성된 F1 잡종세대 집단(H집단)의 암컷이 같은 집단의 수컷 혹은 다른 집단의 수컷과 교미되었을 때, F2 후대를 거의 생성하지 못했다. 다른 집단으로 만들어진 F2 세대는 집단 내 교미에서 F3 세대를 생성시켰다. F1 잡종세대 집단 암수와 팥나방 혹은 어리팥나방 암수를 각각 교차하여 교미시킨 역교잡 8개 집단 중에서도 H집단의 암컷과 짝지어진 어미세대 수컷 집단 2개는 전혀 산란하지 못했다. 후대가 생성된 다른 6개 집단은 모두 집단 내 암수 교미에서 역교잡 F2 세대를 생성하였다. 이 결과는 팥나방 암컷과 어리팥나방 수컷이 교미하였을 경우 F1 후대잡종을 생성할 수 있으나, 이 F1 후대잡종 암컷은 불임이 되는 것을 나타냈다. 결과적으로 두 종 사이에 접합후 생식단계에서 부분적인 생식격리가 발생할 수 있는 것을 나타냈다.
        4,000원
        52.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Spatial structure does not have columns and walls installed inside, so they have a large space. There are upper structure and substructure supporting them. The response of seismic loads to the upper structure may be increased or decreased due to the effects of the substructure. Therefore, in this study, the seismic response of the upper structure and the floor response spectrum of the substructure were compared and analyzed according to the height of the substructure in the spatial structure where the LRB was installed. As a result, the possibility of amplification of response was confirmed as seismic waves passed though the substructure, which is likely to increase the response of the upper structures.
        4,000원
        55.
        2019.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Mesenchymal stem cells (MSCs) are capable of differentiating into mesenchymal tissue such as bone, cartilage, muscle, and adipose, and have been isolated and characterized from various species. Deer adipose tissue-derived MSCs (dAD-MSCs) have not been studied and deer bone marrow-derived MSCs (dBM-MSCs) have not been fully characterized. In this study, we firstly isolated MSCs from deer tissues and then compared characteristics of dAD-MSCs and dBM-MSCs. dAD-MSCs and dBM-MSCs exhibited significant increase in proliferation under low-glucose DMEM culture condition during 20 and 10 passages consecutive passages, respectively. Both cells expressed cell surface markers such as CD73, CD90, and CD105, but did not express CD34 and CD45. Two types of cells expressed stemness markers (Oct4, Sox2, and Nanog) and exhibited differentiation potential into mesodermal lineages. Both cells exhibited osteogenic and chondrogenic differentiation potential, but poor adipogenic differentiation potential. Specifically, dAD-MSCs have a greater capacity for chondrogenic differentiation potential compared to dBM-MSCs. Collectively, we successfully isolated dAD-MSCs from deer for the first time. This study suggests that adipose tissue of deer could be used as a source of deer MSCs.
        4,000원
        56.
        2019.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A hybrid mid-story seismic isolation system with a smart damper has been proposed to mitigate seismic responses of tall buildings. Based on previous research, a hybrid mid-story seismic isolation system can provide effective control performance for reduction of seismic responses of tall buildings. Structural design of the hybrid mid-story seismic isolation system is generally performed after completion of structural design of a building structure. This design concept is called as an iterative design which is a general design process for structures and control devices. In the iterative design process, optimal design solution for the structure and control system is changed at each design stage. To solve this problem, the integrated optimal design method for the hybrid mid-story seismic isolation system and building structure was proposed in this study. An existing building with mid-story isolation system, i.e. Shiodome Sumitomo Building, was selected as an example structure for more realistic study. The hybrid mid-story isolation system in this study was composed of MR (magnetorheological) dampers. The stiffnessess and damping coefficients of the example building, maximum capacity of MR damper, and stiffness of isolation bearing were simultaneously optimized. Multi-objective genetic optimization method was employed for the simultaneous optimization of the example structure and the mid-story seismic isolation system. The optimization results show that the simultaneous optimization method can provide better control performance than the passive mid-story isolation system with reduction of structural materials.
        4,000원
        57.
        2019.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A seismic isolation system is one of the most effective control devices used for mitigating the structural responses due to earthquake loads. This system is generally used as a type of base isolation system for low- and mid-rise building structures. If the base isolation technique is applied to high-rise buildings, a lot of problems may be induced such as the movement of isolation bearings during severe wind loads, the stability problem of bearings under large compression forces. Therefore, a mid-story isolation system was proposed for seismic protection of high-rise buildings. Residence-commerce complex buildings in Korea have vertical irregularity because shear wall type and frame type structures are vertically connected. This problem can be also solved by the mid-story isolation system. An effective analytical method using super elements and substructures was proposed in this study. This method was used to investigate control performance of mid-story isolation system for residence-commerce complex buildings subjected to seismic loads. Based on numerical analyses, it was shown that the mid-story isolation system can effectively reduce seismic responses of residence-commerce complex tall buildings.
        4,000원
        58.
        2019.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        식품첨가물등급의 protease를 이용하여 쌀가루로부터 쌀 전분을 분리하는 효소적 쌀전분 분리·정제법을 구축하기 위해 protease의 반응시간, 반응온도와 농도를 요인으로 하여 변형된 23 완전요인설계법에 따라 protease 반응조건들을 설계하고 이에 따른 쌀전분들의 수율을 조사하였다. 설계된 반응조건들에 따라 제조된 쌀전분들의 수율들에 기초한 반응표면분석을 통해 쌀전분 수율에 대한 protease 반응조건들의 영향을 조사하였다. 또한 효소적 분리·정제법에 의한 쌀전분들의 상업적 활용도를 평가하기 위해 알칼리침지법에 의해 제조된 쌀전분(대조군)과 물리화학적 특성을 대해 비교 분석하였다. Protease를 이용한 효소적 분리· 정제법에 의한 쌀전분들의 수율은 대조군보다 낮았지만 그 상대적 순도는 높은 수준을 나타내었다. Protease에 미량 함유되어 있는 amylase 계통의 효소들에 의한 쌀전분의 부분적인 손상이 예상됨에도 1.5% protease를 이용하여 15℃에서 24시간 동안 처리하여 제조된 쌀전분(RST2)의 아밀로오스 함량은 대조군의 것과 유의적인 차이를 보이지 않았다. 용해도는 효소적 분리·정제법에 의한 쌀전분들이 대조군보다 유의적으로 높은 수준을 나타내었다. 팽윤력은 RST2와 0.5% protease를 이용하여 15℃에서 24시간 동안 처리하여 제조된 쌀전분(RST3)이 대조군과 유의적인 차이를 보이지 않았다. 호화온도는 대조군에 비해 효소적 분리 ·정제법에 의한 쌀전분들이 높은 수준을 나타내었으나 호화엔탈피는 유의적으로 낮은 수준이었다. 페이스팅 점도는 대조군에 비해 효소적 분리·정제법에 의한 쌀전분들이 모든 온도프로파일에 있어 낮은 수준을 나타내었다. 이와 같은 결과들은 효소적 분리·정제법에 사용된 protease에 미량 함유되어 있는 amylase 계통의 효소들에 의한 쌀전분의 부분적인 손상과 protease 처리하는 동안 쌀전분에 있어 annealing이 진행된 결과인 것으로 생각된다. 그럼에도 본 연구에서 효소적 분리·정제법에 의해 제조된 쌀전분들은 높은 고형분 함량을 요구하며, 페이스트의 겔화 또는 노화의 진행이 지연되는 특성을 가공식품의 원료로 적합한 것으로 판단된다. 따라서 효소적 분리·정제법에 의한 쌀전분들은 기존의 알칼리 침지법에 의한 쌀전분과는 다른 특성을 보유한 쌀전분 소재로서 활용가능성이 있을 것으로 생각된다. 또한 효소적 분리·정제법은 알칼리 침지법에 비해 쌀전분의 제조 시간을 단축할 수 있으며, 고농도의 염용액을 배출하지 않아 경제적인 방법인 것으로 판단된다.
        4,000원
        59.
        2019.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        최근 한국에서 발생한 Salmonella로 인한 식중독 사고 는 2018년 9월 학교급식에서 제공된 초콜릿 무스 케이크가 원인이 되었다. 이 연구의 목적은 Salmonella Typhimurium이 인위적으로 접종된 무스케이크와 티라미수에서 3M Molecular Detection Assay 2 –Salmonella와 식품공전에 등재된 방법인 분리배지와 real-time PCR을 비교하는 것이었다. 무스케이크 2종과 티라미수 2종 25 g에 225 mL BPW를 넣고 37oC에서 24시간 동안 증균 배양하 였다. 배양 후, 3M Molecular Detection Assay 2 – Salmonella, 분리배지 그리고 real-time PCR로 분석하였다. 초콜릿 무스 케이크를 제외하고 3가지 방법은 유사한 결 과를 보였다. 초콜릿 무스 케이크에서 분리배지와 3M Molecular Detection Assay 2 –Salmonella는 모든 접종수 준에서 동일한 결과를 나타낸 반면 real-time PCR은 104 CFU/25g수준에서 1번의 양성결과를 제외하고 모두 검출 되지 않았다. 초콜릿 무스에 S. Typhimurium을 102 CFU/ 25 g 수준으로 접종하였을때, real-time PCR를 이용한 검출은 15%에서는 부분적인 음성을 나타냈고, 20-100% 함량의 초콜릿 무스에서는 모두 음성이었다. Real-time PCR 로는 chocolate이 15% 이상 함유된 식품에서의 Salmonella 균 검출이 불가능하였지만, LMAP 기반의 3M Molecular Detection Assay 2으로는 chocolate 농도에 관계없이 검출이 가능하였다.
        4,000원
        60.
        2019.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the seismic response is investigated by using a relatively low-rise building under torsion-prone conditions and three seismic loads with change of the location of the seismic isolation system. LRB (Lead Rubber Bearing) was used for the seismic isolator applied to the analytical model. Fixed model without seismic isolation system was set as a basic model and LB models using seismic isolation system were compared. The maximum story drift ratio and the maximum torsional angle were evaluated by using the position of the seismic layer as a variable. It was confirmed that the isolation device is effective for torsional control of planar irregular structures. Also, it was shown that the applicability of the midstory seismic isolation system. Numerical analyses results presented that an isolator installed in the lower layer provided good control performance for the maximum story drift ratio and the maximum torsional angle simultaneously.
        4,000원
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