• Journal of Microbiology and Biotechnology
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• 제19권4호
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• pp.378-386
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• 2009

A sequential optimization strategy, based on statistical experimental designs, is employed to enhance the production of alkaline protease by a Bacillus pseudofirmus local isolate. To screen the bioprocess parameters significantly influencing the alkaline protease activity, a 2-level Plackett-Burman design was applied. Among 15 variables tested, the pH, peptone, and incubation time were selected based on their high positive significant effect on the protease activity. A near-optimum medium formulation was then obtained that increased the protease yield by more than 5-fold. Thereafter, the response surface methodology(RSM) was adopted to acquire the best process conditions among the selected variables, where a 3-level Box-Behnken design was utilized to create a polynomial quadratic model correlating the relationship between the three variables and the protease activity. The optimal combination of the major medium constituents for alkaline protease production, evaluated using the nonlinear optimization algorithm of EXCEL-Solver, was as follows: pH of 9.5, 2% peptone, and incubation time of 60 h. The predicted optimum alkaline protease activity was 3,213 U/ml/min, which was 6.4 times the activity with the basal medium.

• Journal of Information Processing Systems
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• 제12권1호
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• pp.73-82
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• 2016

In cognitive radio networks (CRNs), the performance of the transmission control protocol (TCP) at the secondary user (SU) severely drops due to the mistrigger of congestion control. A long disruption is caused by the transmission of primary user, leading to the mistrigger. In this paper, we propose a cross-layer approach, called a CR-aware scheme that enhances TCP performance at the SU. The scheme is a sender side addition to the standard TCP (i.e., TCP-NewReno), and utilizes an explicit cross-layer signal delivered from a physical (or link) layer and the signal gives an indication of detecting the primary transmission (i.e., transmission of the primary user). We evaluated our scheme by implementing it onto a software radio platform, the Universal Software Radio Peripheral (USRP), where many parts of lower layer operations (i.e., operations in a link or physical layer) run as user processes. In our implementation, we ran our CR-aware scheme over IEEE 802.15.4. Furthermore, for the purpose of comparison, we implemented a selective ACK-based local recovery scheme that helps TCP isolate congestive loss from a random loss in a wireless section.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.139.2-140
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• 2003

Ornithogalum showing mosaic symptoms were collected from the isolated field of National Plant Quarantine Service in Sengrimmyon of Kyungnam province. Electron microscopic examination of negatively strained preparation was filamentous particle of 740nm in lenght. Indirect-ELISA determined that the virus was serologically related to potyvirus. A single major protein band of Mr 30,000 was observed after sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Indicator plant test showed masaic, necrotic local lesion and sunken areas in leaves of Nicotiana clevelandii and Tetragonia expansa, while the others of indicator plants did not infect. An enzyme-aided purification protocal was used, which eliminated a highly viscous mucilage from extracts of the Omithogalum. Total RNA extracted from infected Omithogalum leaves were amplified of 411b.p fragment in reverse transcription (RT)-PCR when primers specilic for the coat protein gene. An isolate of Omithogalum mosaic virus (OrMV) of the genus Potyvirus was identified as the casual agent of the disease on the basis of electron microscopic, biological and serological reaction.

• 한국지능시스템학회논문지
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• 제10권2호
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• pp.94-102
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• 2000

본 논문에서는 미지의 비선형 계통에 대한 동적 퍼지모델 기반 고장 검출 및 진단(FDI) 계통 설계 기법을 제시한다. 비선형 계통에 대한 일반적인 모델 기반 FDI 계통에서는 선형화된 모델을 이용하고 있다 이러한 방법은 계통에 대한 정확한 수학적 모델을 요구하게 되어 복잡한 비선형 계통에의 적용시 많은 어려움이 있다 제안되는 FDI계통에서는 미지의 비선형 계통을 다수의 선형 모델을 갖는 동적 퍼지모델 형태로 식별한다. 잔차벡터는 온라인 알고리즘에 의해 추정되는 파라미터의 변동치와 비선형 계통의 동작 영역을 나타내는 퍼지 규칙들의 소속값들로 구성된다. 계통의 고장 검출 및 진단은 잔차벡터와 고장종류간의 관계를 학습한 신경망 분류기에 의해 수행된다. 제안된 FDI 계통 설계법을 이용하여 2 탱크 계통에 대한 FDI 계통을 설계하고 시뮬레이션 연구를 통하여 그 유용성을 보였다.

• 대한기계학회논문집B
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• 제21권1호
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• pp.49-56
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• 1997

Heat-transfer enhancement is seeked through modifications of fin surface. Real life plate-fin heat exchangers have complex three-dimensional geometries. Fins can have arrays of dimples and are attached to rows of penetrating tubes. To isolate the effect of surface modification, we model the real flow by a two-dimensional channel flow with a dimple on one side. The flow is analysed by solving the incompressible Navier-Stokes equation by a finite volume method on a generalized boundary-fitted coordinate. Results show a trapped vortex inside the dimple for all cases computed. Local maximum of Nusselt number occurs near the downstream end of the dimple, due to such a vortex. Location of the vortex does not change with respect to the wall temperature change, but moved downstream when Reynolds number increases. This, together with the results that in all cases vortex core is somewhat downstream of the dimple center, suggests that the mean flow above continuously feeds the kinetic energy to the recirculating flow. Heat transfer enhancement and pressure losses are studied through analysing the relevant dimensionless parameters like, Nusselt number and friction factor. In all cases computed, dimpled channel flow experiences less pressure loss than two-dimensional Poiseuille flow.

• 한국군사과학기술학회지
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• 제12권3호
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• pp.333-343
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• 2009

Tactical Information Communication Network(TICN) is a concept-type integrated Military Communication system that enables precise command control and decision making by unifying the diversified military communication network and conveying diverse range of battle field information on real-time, at right place at right time. TICN is designed to advance into high speed, large capacity, long distance wireless relay transmission. To support mobility in battlefield environments, the application of Ad-hoc networking technology to its wireless communication has been examined. Ad-hoc network is consist of mobile nodes and nodes in the network depends on the cooperation of other nodes for forwarding of packets. In this context, some non-cooperating nodes may delay forwarding of packets or drop the packets. This may hamper the network as a whole and disrupt communication between the cooperating nodes. To solve this problem, we present a solution with a Node Weight Management Server(NWMS), which manages each node's weight according to its behavior in local area. When the NWMS detects misbehaving node, it increases the node's weight. If the node's weight exceeds a predefined threshold then the NWMS broadcasts the node's information into network to isolate the misbehaving node from the network. These mechanisms show that they are highly effective and can reliably detect a multitude of misbehaving node.

• The Plant Pathology Journal
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• 제20권2호
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• pp.131-134
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• 2004

A strain of Cucumber mosaic virus (CMV) was isolated from a weed, water chickweed (Stellaria aquatica), growing in the pepper field in Chunchon, Korea. This isolate, CMV-Sa, was differentiated from other CMVs based on biological properties and nucleotide sequence analysis of the coat protein (CP) gene. CMV-Sa showed different reactions to all the tested plants, except Capsicum annuum and Cucumis sativus, when compar-ed with those of CMV-Mf (subgroup I) and CMV-PaFM (subgroup II). Remarkably, in Nicotiana tabacum cvs. Samsun, Xanthi-nc and Ky-57, CMV-Sa induced local necrotic ring spots on the inoculated leaves and venal wave pattern and mosaic on the upper leaves. RNA analysis, serology, and RT-PCR of CP gene showed that CMV-Sa belonged to subgroup I of CMV. However, restriction enzyme analysis of the cDNA using AluI, HhaI, HincII, HindIII, HinfI and MspI showed that CMV-Sa was distinct from that of CMV-Mf. Based on comparison of the nucleotide of CP gene and deduced amino acid sequences between other CMV strains, CMV-Sa was closely related to CMV-Mf with 93.7% and 97.2 % identity, respectively.

• Journal of Species Research
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• 제9권3호
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• pp.198-203
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• 2020

The goal of this study was to isolate and identify wild yeasts from soil samples. The 15 wild yeast strains were isolated from the soil samples collected in Pocheon city, Gyeonggi Province, Korea. Among them, four yeast stains were unrecorded, and 11 yeast stains were previously recorded in Korea. To identify wild yeasts, microbiological characteristics were observed by API 20C AUX kit. Pairwise sequence comparisons of the D1/D2 domain of the 26S rRNA were performed using Basic Local Alignment Search Tool(BLAST). Cell morphology of yeast strains was examined by phase contrast microscope. All strains were oval-shaped and polar budding and positive for assimilation of glucose, 2-keto-ᴅ-gluconate, N-acetyl-ᴅ-glucosamine, ᴅ-maltose and ᴅ-saccharose (sucrose). There is no official report that describes these four yeast species: one strain of the genus Kodamaea in the family Metschnikowiaceae and three strains of the Hannaella in the family Bulleribasidiaceae. Kodamaea ohmeri YI7, Hannaella kunmingensis YP355, Hannaella luteola YP230 and Hannaella oryzae YP366 were recorded in Korea, for the first time.

• Journal of Microbiology and Biotechnology
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• 제21권7호
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• pp.697-702
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• 2011

A strain of the cyanobacterium Arthrospira was isolated from Lake Chahannaoer in northern China and was characterized according to microscopic morphology, photosynthetic oxygen-evolving activity, growth rate, and nutritional profile. Compared with thermophilic Arthrospira species occurring naturally in tropical and subtropical lakes, this isolate is mesophilic and grows optimally at ${\sim}20^{\circ}C$. The total protein, fatty acid, phycocyanin, carotenoid, and chlorophyll a contents were 67.6, 6.1, 4.32, 0.29, and 0.76 grams per 100 grams of dry weight, respectively. The strain is rich in polyunsaturated fatty acids (PUFAs). An essential omega-3 fatty acid, docosahexaenoic acid (DHA), was detected, and ${\gamma}$-linolenic acid (GLA) and DHA accounted for 28.3% of the total fatty acid content. These features of this newly isolated strain make it potentially useful in commercial mass culture in local areas or as a biofuel feedstock. It is also an alternative resource for studying the metabolic PUFA pathways and mechanisms of cold stress tolerance in cyanobacteria.

• 정보보호학회논문지
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• 제19권5호
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• pp.71-80
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• 2009

애드혹 네트워크는 통신에 참여하는 모든 노드가 서로간에 서비스를 제공하는 모바일 노드들로 구성된 네트워크이다. 하지만 네트워크에 일부 비정상행위 노드가 존재한다면 많은 위협에 직면하게 된다. 그러므로 애드혹 네트워크의 안전성을 보장하기위해 비정상행위 노드의 탐지 및 배제가 필요하다. 이 문제를 해결하기 위해, 본 논문에서는 지역내 각 노드의 가중치를 관리하는 노드 가중치 관리 서버를 사용한다. 노드 가중치 관리서버는 비정상행위 노드가 발견되었을 경우 해당 노드의 가중치를 증가시키고, 가중치가 임계치를 초과하였을 경우, 네트워크내에서 이를 고립시키기 위해 해당 노드의 정보를 전파한다. 이 방법은 매우 효율적이고, 다수의 비정상행위 노드를 신뢰성 있게 탐지함을 보여준다.