• Journal of Microbiology
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• 제33권4호
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• pp.295-301
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• 1995

An antifungal Pseudomonas stutzeri YPL-1 produced extracellular chitinase and .betha.-1, 3-glucanase that were key enzymes in the decomposition of fungal hyphal walls. These lytic extracellular enzymes markedly inhibited mycelial growth of the phytopathogenic fungus Fusarium solani. A chitinase from P. stutzeri YPL-1 inhibited fungal mycelial growth by 87%, whereas a .betha.-1, 3-glucanase from the bacterium inhibited growth by 53%. Furthermore, co-operative action of the enzymes synergistically inhibited 95% of the fungal growth. The lytic enzymes caused absnormal swelling and retreating on the fungal hyphal walls in a dual cultures. Scanning electron microscopy clearly showed hyphal degradation of F. solani in the regions interacting with P. stutzeri YPL-1. In an in vivo pot test, P. stutzeri YPL-1 proved to have biocontrol ability as a powerful agent in controlling plant disease. Planting of kidney bean (Phaseolus vulgaris L.) seedlings with the bacterial suspension in F. solani-infested soil significantly suppressed the development of fusarial root-rot. The characteristics of a crude preparation of .betha.-1, 3-glucanase produced from P. stutzeri YPL-1 were investigated. The bacterium detected after 2 hr of incubation. The enzyme had optimum temperature and pH of 40.deg.C and pH 5.5, respectively. The enzyme was stable in the pH range of 4.5 to 7.0 and at temperatures below 40.deg.C, with a half-life of 40 min at 60.deg.C.

• E2M - 전기 전자와 첨단 소재
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• 제1권1호
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• pp.35-43
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• 1988

In this study, PLZT ceramics were fabricated by the freeze-drying and normal sintering method. The composition rate of the specimen was selected 9/65/35(La/Zr/Ti) which had good optical and dielectric properties, sintering time was varied 1, 10, 30, 50, 55, 60 and 65(hr) at 1250(.deg.C). After sintering, the optical and dielectric properties were investigated with the grain size. As the result of the experiment, the particle size of the powder prepared by freeze-drying method was less than 1(um). The relative dielectric constant was increased linearly with the sintering time and specimen sintered for 65(hr) had the highest value, 5780. Grain was grown with increasing time, in the case of specimen sintered for 60(hr), the grain size was 8.4(um). Transmittance was increased with the grain size. In the case of 8.4(um) grain size, the transmittance was 56(%). Curie temperature was decreased linearly by the surface-layer effect of space-charge. In the case of grain size, 1.8(um), 8.4(um), curie temperatures were appeared at 100(.deg.C) and 80(.deg.C), respectively.

• 미생물학회지
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• 제29권4호
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• pp.250-257
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• 1991

An obligate methanol-oxidizing bacterium, Methylobacillus sp. strain SK1, which grows only on methanol was isolated from soil. The isolate was nonmotile Gram-negtive rod. It does not have internal membrane system. The colonies were small, whitish-yellow, and smooth. The guanine plus cytosine content of the DNA was 48 mol%. Cellular fatty acids consisted predominantly of large amounts of straight-chain saturated $C_{16:0}$ acid and unsaturated $C_{16:1}$ acid. The major ubiquinone was Q-8, and Q-10 was present as minor component. The cell was obligately aerobic and exhibited catalase, but no oxidase, activity. Poly-.betha.-hydroxybutyrate, endospores, or cysts were not observed. the isolate could grow only on methanol in mineral medium. Growth factors were not required. The isolate was unable to use methane, formaldehyde, formate, methylamine, and several other organic compounds tested as a sole source of carbon and energy. Growth was optimal at 35.deg.C and pH 7.5. It could not grow at 42.deg.C. The doubling time was 1.2h at 30.deg.C when grown with 1.0%(v/v) methanol. The growth was not affected by antibiotics inhibiting cell wall synthesis and carbon monoxide but was completely suppressed by those inhibiting protein synthesis. Methanol was found to be assimilated through the ribulose monophosphate pathway. Cytochromes of b-, c-, and o- types were found. Cell-free extracts contained a phenazine methosulfate-linked methanol dehydrogenase activity, which required ammonium ions as an activator. Cells harvested after the late exponential phase seemed to contain blue protein.ein.

• 마이크로전자및패키징학회지
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• 제18권4호
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• pp.27-32
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• 2011

Tin(II) acetate와 tin(II) chloride의 주석 precursor를 사용하여 상온에서의 강제 환원 반응으로 주석 나노 입자를 합성시켰다. 0.015 g의 동일한 PVP 양을 첨가한 조건에서 PVP의 분자량이 클수록 비정상적으로 큰 입자들의 생성율이 증가되어 입도 범위가 매우 넓은 주석 나노 입자들이 생성됨을 확인할 수 있었다. 합성된 주석 나노 입자를 함유하는 DEG 용액의 DSC 분석 결과 1차 가열에서는 35 nm 미만 특정 크기 입자들의 수가 충분한 경우에서 DEG의 증발 흡열피크 외에도 특정 크기 입자들의 융점 강하 흡열 피크가 구분되게 검출되었다. 1차 DSC 측정 중 용융된 주석 나노 입자들은 서로 접촉하며 뭉쳐지는 현상이 발생하므로 2차 가열시에는 벌크 주석의 용융 피크에 해당하는 $232^{\circ}C$ 흡열 피크만이 관찰되었다.

• 대한기계학회논문집B
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• 제22권4호
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• pp.551-561
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• 1998

This paper was studied to understand the characteristics of heat transfer coefficients and surface temperature distributions around a circular combustion chamber within the heat-intercept duct of kerosene fan heater. The experiment was carried out in the heat-intercept duct of kerosene fan heater attached to the blow-down-type subsonic wind tunnel with a test section of 240 mm * 240 mm * 1200 mm. The purpose of this paper was to obtain the basic data related with normal combustion for new design from conventional kerosene fan heater, and to investigate the effect of surface temperature, local and mean heat transfer coefficients versus flow-rate of convection axial fan according to the variations of heat release conditions from kerosene fan heater during normal combustion. Consequently it was found that (i) the revolution of convection axial fan during combustion had a smaller value than that of non-combustion because of the thermal resistance due to the high temperature in the heat-intercept duct, (ii) the pressure ratio P$_{2}$/P$_{1}$ had a comparatively constant value of 0.844 according to the revolution increase of turbo fan and the heating performance of kerosene fan heater had a range of 1,494 ~ 3,852 kcal/hr, (iii) the local heat transfer coefficient around a circular combustion chamber had a comparatively larger scale in the range of 315 deg. < .theta. < 45 deg. than that in the range of 90 deg. < .theta. < 270 deg. as a result of heat transfer difference between front and back of a circular combustion chamber, and (iv) the mean heat transfer coefficient around a circular combustion chamber increased linearly like a H$_{m}$=95.196Q+104.019 in condition of high heat release according to the increase of flow-rate of axial fan.n.

• 전산구조공학
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• 제9권2호
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• pp.143-151
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• 1996

구조 및 전기적 제약조건을 고려한 전자력 발사기의 최적설계에 대해 연구하였다. 펄스형 대전류가 흐르는 발사기의 단면적이 최소화되었으며 각 요소(레일, 측면벽, 세라믹 및 강철)의 허용응력과 예하중을 고려하였다. 전기적 제약조건은 발사기의 성능을 저하시키는 와전류 효과를 방지하기 위한 세라믹의 두께로 정하였다. 90mm발사기의 설계에서 응력해석과 최적화는 ANSYS코드를 사용하여 수행되었다. 예하중을 받는 최적설계에서는 예하중을 받지 않는 최적설계보다 53%의 단면적이 감소되었다. 레일의 원호각이 45.deg.일때 발사기의 성능이 가장 양호하다. 레일의 원호각이 45.deg.일때 Fahrenthold 연구결과와 비교하여 9%의 변형량 감소와 10.4%의 변형량 감소를 얻었고, 예하중도 186Mpa에서 59.8Mpa로 감소되었다. 연구결과는 설계 요구조건을 충분히 만족시켜 주고 있음을 보여 주었다.

• Journal of Microbiology and Biotechnology
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• 제31권5호
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• pp.659-666
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• 2021

After Candida albicans, Candida glabrata is one of the most common fungal species associated with candidemia in nosocomial infections. Rapid acquisition of nutrients from the host is important for the survival of pathogens which possess the metabolic flexibility to assimilate different carbon and nitrogen compounds. In Saccharomyces cerevisiae, nitrogen assimilation is controlled through a mechanism known as Nitrogen Catabolite Repression (NCR). NCR is coordinated by the action of four GATA factors; two positive regulators, Gat1 and Gln3, and two negative regulators, Gzf3 and Dal80. A mechanism in C. glabrata similar to NCR in S. cerevisiae has not been broadly studied. We previously showed that in C. glabrata, Gln3, and not Gat1, has a major role in nitrogen assimilation as opposed to what has been observed in S. cerevisiae in which both factors regulate NCR-sensitive genes. Here, we expand the knowledge about the role of Gln3 from C. glabrata through the transcriptional analysis of BG14 and gln3Δ strains. Approximately, 53.5% of the detected genes were differentially expressed (DEG). From these DEG, amino acid metabolism and ABC transporters were two of the most enriched KEGG categories in our analysis (Up-DEG and Down-DEG, respectively). Furthermore, a positive role of Gln3 in AAA assimilation was described, as was its role in the transcriptional regulation of ARO8. Finally, an unexpected negative role of Gln3 in the gene regulation of ABC transporters CDR1 and CDR2 and its associated transcriptional regulator PDR1 was found. This observation was confirmed by a decreased susceptibility of the gln3Δ strain to fluconazole.

• 대한의용생체공학회:의공학회지
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• 제43권4호
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• pp.241-250
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• 2022

It is known that chronic pain and injury of upper limb joint tissue in manual wheelchair users is usually caused by muscle imbalance, and the propulsion speed is reported to increase this muscle imbalance. In this study, kinematic variables, electromyography, and ultrasonographic images of the upper limb were measured and analyzed at two different propulsion speeds to provide a quantitative basis for the risk of upper extremity joint injury. Eleven patients with spinal cord injury for the experimental group (G_E) and 27 healthy adults for the control group (G_C) participated in this study. Joint angles and electromyography were measured while subjects performed self-selected comfortable and fast-speed wheelchair propulsion. Ultrasound images were recorded before and after each propulsion task to measure the acromiohumeral distance (AHD). The range of motion of the shoulder (14.35 deg in G_E; 20.24 deg in G_C) and elbow (5.25 deg in G_E; 2.57 deg in G_C) joints were significantly decreased (p<0.001). Muscle activation levels of the anterior deltoid, posterior deltoid, biceps brachii, and triceps brachii increased at fast propulsion. Specifically, triceps brachii showed a significant increase in muscle activation at fast propulsion. AHD decreased at fast propulsion. Moreover, the AHD of G_E was already narrowed by about 60% compared to the G_C from the pre-tests. Increased load on wheelchair propulsion, such as fast propulsion, is considered to cause upper limb joint impingement and soft tissue injury due to overuse of the extensor muscles in a narrow joint space. It is expected that the results of this study can be a quantitative and objective basis for training and rehabilitation for manual wheelchair users to prevent joint pain and damage.

• 한국가금학회지
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• 제50권4호
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• pp.193-202
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• 2023

인플루엔자 A 바이러스(IAVs)는 많은 조류 종의 호흡 기관에 감염되며 사람을 비롯한 다른 동물로 전파될 수 있는 포장된 음극성 역전사 RNA 바이러스이다. 이 연구에서는 이전 연구의 마이크로어레이 데이터를 다시 분석하여 닭에서 공통 및 특이하게 발현되는 유전자(DEG) 및 그들의 생물학적 활동을 식별하였다. 고병원성(HPAIV) 및 저병원성(LPAIV) 인플루엔자 A 바이러스 감염된 닭 세포에서 각각 760개와 405개의 DEG가 발굴되다. HPAIV 및 LPAIV는 각각 670개와 315개의 DEG를 가지고 있으며, 이 중 90개의DEG가 두 바이러스에서 공유된다. HPAIV 감염으로 인해DEG의 기능 주석에 따르면 세포 주기의 기본적인 생물학적 기능과 연관된 다양한 유전자가 발굴되었다. 대상 유전자중에서 CDC Like Kinase 3(CLK3), Nucleic Acid Binding Protein 1(NABP1), Interferon-Inducible Protein 6(IFI6), PIN2 (TERF1) Interacting Telomerase Inhibitor 1(PINX1), 그리고Cellular Communication Network Factor 4(WISP1)의 발현은 polyinosinic:polycytidylic acid(PIC)로 처리된 DF-1 세포에서 변화되었다. 이것은 toll-like receptor 3(TLR3) 리간드인 TLR3 신호에 의해 이러한 유전자의 전사가 조절될 수 있음을 시사하며, 닭에서 AIV의 병리 생리학에 대한 더 나은 이해를 얻기 위해서는 AIV 감염 과정 중에 호스트 반응을 조절할 수 있는 메커니즘을 구명하는 데 더 많은 연구에 초점을 맞추는 것이 필요하다고 사료된다. 이러한 메커니즘에 대한 이해는 신규 치료 전략 개발에 활용될 수 있다.

• 대한전자공학회논문지
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• 제25권11호
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• pp.1373-1379
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• 1988

본 연구에서는 FDM(finite difference method)을 이용한 수치적 방법을 사용하여 MODFET (MO-dulation doped FET)의 전위 분포와 전자 밀도를 이차원적으로 해석하였다. 일차원적 해석 방법에서는 MODFET의 게이트 부분만을 계산하는 반면, 이차원적 해석 방법은 소오스와 드레인 부분도 계산해줌으로써 일차원적 해석 방법에서 무시되는 기생 효과(parasitic effect)를 고려하여 더 정확한 해석이 가능하였다. 결과로서 스페이스(spacer) 두께와 (n)AlGaAs층의 도핑 농도의 변화에 따른 채널내에서 2DEG(2dimensional electron gas)의 단위 면적에 대한 밀도와의 관계를 정량적으로 제시하였으며 스페이서의 두께가 작아지거나 (n)AlGaAs 층의 도핑 농도가 커질수록 MODFET 채널 내의 전자 밀도가 증가함을 확인하였다.