• 대한기계학회논문집A
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• 제34권8호
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• pp.1015-1021
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• 2010

본 연구에서는 반응소결 탄화규소(RS-SiC)의 제조공정 중에서 C/SiC 복합 비율(0.1, 0.3, 0.4, 0.5, 0.6, 0.7, 1.0)이 외부입자충격 손상 거동에 미치는 영향을 평가하였다. 충격시험은 공기총(air-gun)을 사용하였으며, 직경 2 mm 강구를 113 m/s, 122 m/s, 180 m/s의 충격속도로 RS-SiC 판재($20\times20\times3$ mm)에 충격시켜 발생된 링크랙의 직경 변화 및 콘크랙의 발생 거동을 SEM 영상으로 평가하였다. 결과적으로 RS-SiC에 발생한 링크랙의 최대직경이 충격속도가 증가함에 따라 대체로 증가하였지만, C/SiC 복합 비율에 따라서는 급격한 변화를 보였다. 이는 C/SiC 복합 비율에 따라 잔류 Si 함량 및 굽힘강도 변화의 영향으로 볼 수 있다. 특히 C/SiC 복합 비율이 0.4~0.5 범위에서 콘크랙이 발생됨에 따라 링크랙에서 콘크랙의 발생으로 변화되는 충격손상 메커니즘의 임계영역으로 판단할 수 있다. 아울러 콘크랙의 발생 임계영역을 고려할 때, RS-SiC 최적 제조 공정으로서 C/SiC 혼합 비율을 최대 0.3으로 하는 것이 효과적이다.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2008년도 International Meeting of the Microbiological Society of Korea
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• pp.23-25
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• 2008

Serum complement proteins comprise an important system that is responsible for several innate and adaptive immune defence mechanisms. There were three well described pathways known to lead to the generation of a C3 convertase, which catalyses the proteolysis of complement component C3, and leads to the formation of C3 opsonins (C3b, iC3b and C3d) that fix to bacteria. A pivotal step in the complement pathway is the assembly of a C3 convertase, which digests the C3 complement component to form microbial-binding C3 fragments recognized by leukocytes. The spleen clears microorganisms from the blood. Individuals lacking this organ are more susceptible to Streptococcus pneumoniae. Innate resistance to S. pneumoniae has previously been shown to involve complement components C3 and C4, however this resistance has only a partial requirement for mediators of these three pathways, such as immunoglobulin, factor B and mannose-binding lectin. Therefore it was likely that spleen and complement system provide resistance against blood-borne S. pneumoniae infection through unknown mechanism. To better understand the mechanisms involved, we studied Specific intracellular adhesion molecule-grabbing nonintegrin (SIGN)-R1. SIGN-R1, is a C-type lectin that is expressed at high levels by spleen marginal-zone macrophages and lymph-node macrophages. SIGN-R1 has previously been shown to be the main receptor for bacterial dextrans, as well as for the capsular pneumococcal polysaccharide (CPS) of S. pneumoniae. We examined the specific role of this receptor in the activation of complement. Using a monoclonal antibody that selectively downregulates SIGN-R1 expression in vivo, we show that in response to S. pneumoniae or CPS, SIGN-R1 mediates the immediate proteolysis of C3 and fixation of C3 opsonins to S. pneumoniae or to marginal-zone macrophages that had taken up CPS. These data indicate that SIGN-R1 is largely responsible for the rapid C3 convertase formation induced by S. pneumoniae in the spleen of mice. Also, we found that SIGN-R1 directly binds C1q and that C3 fixation by SIGN-R1 requires C1q and C4 but not factor B or immunoglobulin. Traditionally C3 convertase can be formed by the classical C1q- and immunoglobulin-dependent pathway, the alternative factor-B-dependent pathway and the soluble mannose-binding lectin pathway. Furthermore Conditional SIGN-R1 knockout mice developed deficits in C3 catabolism when given S. pneumoniae or its capsular polysaccharide intravenously. There were marked reductions in proteolysis of serum C3, deposition of C3 on organisms within SIGN-$R1^+$ spleen macrophages, and formation of C3 ligands. The transmembrane lectin SIGN-R1 therefore contributes to innate resistance by an unusual C3 activation pathway. We propose that in the SIGN-R1 mediated complement activation pathway, after binding to polysaccharide, SIGN-R1 captures C1q. SIGN-R1 can then, in association with several other complement proteins including C4, lead to the formation of a C3 convertase and fixation of C3. Therefore, this new pathway for C3 fixation by SIGN-R1, which is unusual as it is a classical C1q-dependent pathway that does not require immuno globulin, contributes to innate immune resistance to certain encapsulated microorganisms.

• 한국세라믹학회지
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• 제32권10호
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• pp.1194-1202
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• 1995

The influences of TiC additions to the α-SiC on microstructural, mechanical, and electrical properties were investigated. Electrical discharge machinability of SiC-TiC composites was also studied. Samples were prepared by adding 30, 45, 60 wt.% TiC particles as a second phase to a SiC matrix. Sintering of SiC-TiC composites was done by hot pressing under a vacuum atmospehre from 1000 to 2000℃ with a pressure of 32 MPa and held for 90 minutes at 2000℃. Samples obtained by hot pressing were fully dense with the relative densities over 99% except 60wt.% TiC samples. Flexural strength and fracture toughness of the samples were increased with the TiC content. In case of SiC samples containing 45 wt.% TiC, the fracture toughness showed 90% increase compared to that of monolithic SiC sample. The crack propagation and crack deflection were observed with a SEM for etched samples after Vicker's indentation. The electrical resistivities of SiC-TiC composites were measured utilizing the four-point probe. The electrical dischage machining of composites was also conducted to evaluate the machinability.

• 한국식품과학회지
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• 제15권2호
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• pp.164-169
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• 1983

들깨기름의 트리-글리세리드조성(組成)을 밝히기 위하여 TLC에 의하여 시료유(試料油)로부터 트리-글리세리드를 분리하고, 이것을 ${\mu}-Bondapak\;C_{18}$ column을 사용한 HPLC에 걸어 PN별(別)로 트리-글리세리드를 분획(分劃)하였으며, 각획분(各劃分)을 분취(分取)하여 GLC로 아실 탄소수별(炭素數別)로 분획(分劃)하였다. 또한 PN별(別) 획분(劃分)의 지방산조성(脂肪酸組成)을 GLC에 의하여 분석하였다. 이들 분석 결과로부터 들깨기름을 구성하는 트리-글리세리드조성(組成)을 산정(算定)하였는데 그 수(數)는 15종류이며, 그 중 주요(主要)한 트리-글리세리드 및 그 비율은 다음과 같다. 즉, $(C_{18:3},\;C_{18:3},\;C_{18:3},\;68.0%)$, $(C_{18:2},\;C_{18:3},\;C_{18:3},\;6.7%)$, $(C_{18:1},\;C_{18:2},\;C_{18:3},\;5.9%)$, $(C_{16:0},\;C_{18:3},\;C_{18:3},\;4.3%)$, $(C_{18:1},\;C_{18:2},\;C_{18:3},\;3.8%)$, $(C_{18:1},\;C_{18:1},\;C_{18:3},\;3.2%)$, ($C_{16:0},\;C_{18:2},\;C_{18:3},\;2.0%)$, $(C_{18:2},\;C_{18:2},\;C_{18:3},\;1.5%)$ 및 $(C_{16:0},\;C_{18:1},\;C_{18:3},\;1.0%)$ 등이다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권5호
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• pp.1801-1816
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• 2014

Because HTTP-related ports are allowed through firewalls, they are an obvious point for launching cyber attacks. In particular, malware uses HTTP protocols to communicate with their master servers. We call this an HTTP-based command and control (C&C) server. Most previous studies concentrated on the behavioral pattern of C&Cs. However, these approaches need a well-defined white list to reduce the false positive rate because there are many benign applications, such as automatic update checks and web refreshes, that have a periodic access pattern. In this paper, we focus on finding new discriminative features of HTTP-based C&Cs by analyzing HTTP activity sets. First, a C&C shows a few connections at a time (low density). Second, the content of a request or a response is changed frequently among consecutive C&Cs (high content variability). Based on these two features, we propose a novel C&C analysis mechanism that detects the HTTP-based C&C. The HAS-Analyzer can classify the HTTP-based C&C with an accuracy of more than 96% and a false positive rate of 1.3% without using any white list.

• 생명과학회지
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• 제12권2호
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• pp.208-212
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• 2002

온도 기울기 전기영동장치를 이용하여 d(CXG)와 d(GXC) 염기의 열 안정성을 결정하는데 사람의 $\varepsilon$-글로빈 DNA조각을 사용하였다. 염기 쌍의 안정성은 이웃하는 염기서열에 의한 수소결합과 base stocking 상호작용에 의존한다. 염기 쌍의 안정성은 d(CXG) d(CYG)의 경우에 T.AG.A = A.G>C.T>T.C>C.A>A.C이다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.27-31
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• 2001

Hi-Nicalon SiC fiber reinforced SiC composites (SiC/SiC) have been fabricated by the reaction sintering process. Braided Hi-Nicalon SiC fiber with double interphases of BN and SiC was used in this composite system. The microstructures and the mechanical properties of reaction sintered SiC/SiC composites were investigated through means of electron microscopies (SEM, TEM, EDS) and bending tests. The matrix morphology of reaction sintered SiC/SiC composites was composed of the SiC phases that the composition of the silicon and the carbon is different. The TEM analysis showed that the residual silicon and the unreacted carbon were finely distributed in the matrix region of reaction sintered SiC/SiC composites. Reaction sintered SiC/SiC composites also represented proper flexural strength and fracture energy, accompanying the noncatastrophic failure behavior.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.102-105
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• 2005

The mechanical properties of $SiC_f/SiC$ composites reinforced with continuous SiC fiber have been investigated in conjunction with the detailed analysis of their microstructures. Especially, the effect of test temperature on the characterization of $SiC_f/SiC$ composites was examined. In this composite system, a braiding Hi-Nicalon SiC fibric was selected as a reinforcement. $SiC_f/SiC$ composites have been fabricated by the reaction sintering process, using the complex matrix slurry with a constant composition ratio of SiC and C particles. The characterization of $RS-SiC_f/SiC$ composites was investigated by means of SEM, EDS and three point bending test. Based on the mechanical property-microstructure correlation, the high temperature applicability of $RS-SiC_f/SiC$ composites was discussed.

• Journal of Plant Biology
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• 제37권1호
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• pp.111-124
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• 1994

본 연구에서는 C. foetida complex 및 그 근연종들에서 나타나는 형태 변이 양상을 수리분류학적으로 분석하여, 각 분류군의 타당성을 검토하고 그 한계 및 분류학적 위치를 명확히 설정하고자 하였다. 본 complex 및 근연종들의 주요 식별형질에 대한 주성분분석과 유집분석을 수행한 결과, C. foetida에 기재되어 있는 종하위 분류군들은 C. foetida var. foetida, C. foetida var. micrantha 및 C. foetida var. velutina의 3변종으로 정리하는 것이 타당한 것으로 밝혀졌다. 또한 C. brachycarpa, C. frigida, C. heracleifolia, C. yunnanensis는 각각 독립된 종으로 인식하는 것이 합당한 것으로 판명되었으며, C. heracleifolia는 주로 잎의 형태 및 털의 특징에 의해 var. heracleifolia 및 var. bifida의 2변종으로 구분되는 것으로 나타났다. 한편, C. mairei 및 C. foetida var. foliolosa는 C. foetida var. velutina와, C. foetida var. longbracteata 및 C. foetida var. bifida는 C. frigida와 각각 동일한 분류군인 것으로 밝혀졌다.

• 한국응용곤충학회지
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• 제51권4호
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• pp.343-348
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• 2012

복숭아혹진딧물에 기생하는 목화면충좀벌의 발육기간, 머미율, 번데기 사망률, 성비를 20, 25, 30, $25^{\circ}C$ 인큐베이터에서 수행하였다. 실험을 위하여 피망잎이 놓인 콤팩트샤레를 사용하였다. 각각의 4개 온도에서 발육단계별로 복숭아혹진딧물을 사육하였고 기생을 유도하기 위하여 12시간 동안 목화면충좀벌에 제공하였다. 목화면충좀벌의 알에서 성충까지 발육기간은 $20^{\circ}C$ 18.3일, $25^{\circ}C$ 14.7일, $30^{\circ}C$ 10.4일, $35^{\circ}C$ 9.3일이었다. 복숭아혹진딧물에 기생한 목화면충좀벌의 머미율은 $20^{\circ}C$와 $25^{\circ}C$, 1령과 2령에서 가장 높았으나 $30^{\circ}C$와 $25^{\circ}C$에서는 3령충에서 84.4~85.0%로 가장 높았다. 목화면충좀벌의 기주섭식률은 $20{\sim}35^{\circ}C$까지 각각 12.5%, 17.3%, 16.0%, 10.9%였다. 목화면충좀벌 암컷의 성비는 온도별로 각각 49%, 46%, 69%, 60% 였다.