• 한국동물학회지
• /
• 제31권1호
• /
• pp.1-10
• /
• 1988

자매종 R.nigromaculate(참개구리)와 R. plancyi(금개구리)간의 생식적 격리기작을 구명하기 위하여 전라남도 광주시에서 발견된 자연집중 1개체를 포함한 두 종의 형태, 유전적 변이 및 번식시기 등을 조사한 분석한 결과는 다음과 같다. 두 종은 형태,유전,mating call 및 번식시기 등에 뚜렷한 차이가 있었고, 약 350만년 전에 남방계인 R. plancyi에서 R.nigromaculate가 분화되었을 것으로 추정되었다. 잡종 1개체는 전기영동 결과 일대잡종으로 확인되었으며 포란한 정상 난소를 갖고 있는 점으로 미루어 보아 생식이 간으하다고 여기지며, 따라서 postmating isolating mechanism은 불완전하게 생성되었다고 추측된다.

• Wind and Structures
• /
• 제28권2호
• /
• pp.99-110
• /
• 2019

Vortex-Induced-Vibration (VIV) is one kind of the wind-induced vibrations, which may occur in the construction and operation period of bridges. This phenomenon can bring negative effects to the traffic safety or can cause bridge fatigue damage and should be eliminated or controlled within safe amplitudes.In the current VIV studies, one available mitigation countermeasure, the horizontal flow-isolating plate, shows satisfactory performance particularly in PI shaped bridge deck type. Details of the wind tunnel test are firstly presented to give an overall description of this appendage and its control effect. Then, the computational-fluid-dynamics(CFD) method is introduced to investigate the control mechanism, using two-dimensional Large-Eddy-Simulation to reproduce the VIV process. The Reynolds number of the cases involved in this paper ranges from $1{\times}10^5$ to $3{\times}10^5$, using the width of bridge deck as reference length. A field-filter technique and detailed analysis on wall pressure are used to give an intuitive demonstration of the changes brought by the horizontal flow-isolating plate. Results show that this aerodynamic appendage is equally effective in suppressing vertical and torsional VIV, indicating inspiring application prospect in similar PI shaped bridge decks.

• 한국동물학회지
• /
• 제35권3호
• /
• pp.339-343
• /
• 1992

버들치, 버들개의 공서지역에서 2종 사이의 종문제를 명확히 구명하기 위해 883개체를 채집하여 형태형 질과 유전자분석을 실시하여 생식적 격 리기작 여부를 조사한 결과는 다음과 같다. 2종 사이 에 잡종개체가 약 12%( n = 104) 발견되었다. 형 태분류형 질인 측선상부린수( SAL)의 경우 버들개와 버들치가 각각 SAL = 24.25$\pm$1, 32, 16.93 $\pm$ 0.92로 뚜렷한 차이를 나타내었으나 잡종개체는 평균 SAL = 19.56$\pm$1.80으로 중간값을 나타내었다. 잡종개체 중 F2 이상의 잡종개체 비율은 약 2.7%로 Fl(9"yp)에 비해 현저히 낮고, 잡종개체의 출현률이 기 대치보다 낮은 것으로 보아(P < 0.001) 2종간에 자유교배가 되지 않으며 따라서 Predating isolating mechanism이 작용한다고 보며 또한 잡종개체의 치사율이 높은 점으로 보아 이들사이에는 Postdating isolating mechanism도 동시에 작용한다고 사료되며 따라서 이들 2종은 비교적 최근에 분화된 별종임이 재확인 되었다. 되었다.

• Macromolecular Research
• /
• 제15권1호
• /
• pp.31-38
• /
• 2007

Pentamethylcyclopentadienyltitanium trichloride, bis(cyclopentadienyl)titanium dichloride ($Cp_2TiCl_2$), and bis(pentamethylcyclopentadienyl)titanium dichloride were used in the polymerization of styrene without the aid of Group I-III cocatalysts. The properties of the resulting polymer indicated that polymerization was more controlled than in thermal polymerization. The kinetic studies indicated that a lower level of termination is present and that the polymer chain can be extended by adding an additional monomer. To elucidate the mechanism of polymerization, a series of experiments was performed. All results supported the involvement of a radical mechanism in the polymerization using $Cp_2TiCl_2$. The possibility of atom transfer radical polymerization (ATRP) mechanism was investigated by isolating the intermediate species. We could confirm the activation step from the reaction of 1-PEC1 with $Cp_2TiCl$ by detecting the coupling product of the generated active radicals. However, the reversible deactivation reaction competes with other side reactions, and it detection was difficult with our model system.

• 한국군사과학기술학회지
• /
• 제16권3호
• /
• pp.390-397
• /
• 2013

Primary-cultured immune cells are widely used in research to elucidate the mechanism of inflammation including chemotaxis, production of reactive oxygen species, cytokine release and antigen presenting. Mice are one of the species of experimental animals commonly used for such studies. Immune cells can be isolated and cultured from various organs such as bone marrow, peritoneal cavity, lung, spleen. For elaborated experimental studies, immune cells should be elicited with inflammatory substances or proliferated in vitro with special media. This paper details methods of obtaining immune cells from various organs of mice and investigating immune mechanism using isolated immune cells. It contains standard protocols of isolating and culturing immune cells from bone marrow, peritoneal cavity and lymphoid organs. It also covers the methods of investigating immune mechanism such as ELISA, western blotting, confocal microscopy and ELISPOT assay. With the works in this study, we established the standardized isolation and analysis methods of primary-cultured immune cells.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
• /
• pp.1105-1108
• /
• 2008

본 고에서는 화재 시 구조물 콘크리트의 안전성 확보를 목적으로, 폭렬방지대책 및 메커니즘에 대해 고찰 분석한 것으로서, 그 결과를 요약하면 다음과 같다. 1) 국내 외에 알려져 있는 고성능 콘크리트의 폭렬방지 방법으로 함수율 및 C/W를 낮추는 방법,내화피복을 실시하여 고온을 차단하는 방법, 횡구속 실시하여 내부에서 발생되는 횡변위에 저항하는 방법, 섬유를 혼입하여 수증기압을 외부로 배출시키는 방법 등 4가지 방안이 있다. 2) 기존의 폭렬관련 이론과 WPB이론에 의한 폭렬메커니즘 분석을 토대로 폭렬방지 방안을 제안하면 기존 건축물에 한해서는 내화피복을 실시하는 방법이, 신축 건축물에 한해서는 섬유를 혼입하는 방법이 양호한 것으로 판단된다.

• Journal of Ginseng Research
• /
• 제21권3호
• /
• pp.147-152
• /
• 1997

Ginsenosides $Rh_1$ and $Rh_2$ Induced the differentiation of F9 teratocarcinoma stem cells. These agents are structurally similar to the steroid hormones, therefore, we speculated that the steroid receptor (s) or novel nuclear receptor (s) could be involved in the differentiation process induces by them. Based on this speculation, we tried to alone new nuclear receptors with reverse transcription-polymerase chain reaction (RT-PCR) method by isolating RNA from F9 teratocarcinoma cells induced by ginsenosides. By using RT-PCR with degenerated primers from highly conserved DNA binding domain of nuclear receptors, we identified several nuclear receptors. In northern blot analysis we found that these clones are transcriptionally regulated by ginsenoside Rhl or Rh2 treatment. Further characterizations of these clones are needed to identify the mechanism of gene expression, which has an important role in the differentiation of F9 cells induced by ginsenosides.

• 한국동물학회지
• /
• 제30권4호
• /
• pp.417-431
• /
• 1987

Isozyme analysis, morphometric comparison, and artificial hybridization test wereperformed to elucidate the patterns of genic variation, morphological differentiation, genetic incompatibility, and a probable path in speciation between two MDH allelotypes (MM type and MS type) of the Dark Chub Zacco temmincki, a fresh water fish inhabiting in Korean waters. The degree of genic variation of MS type(HD=.023, HG=.021) was twofold higher than that of MM type (HD=.013, HG=.014) but both allelotypes were far less than the average genic variation of fresh water Bish in general. The average genetic similarities among 7 populations of MM type and 6 Populations of MS type were S=.947 and S=.966 respectively, whereas the value between two allelotypes was S=.853. Presumed divergent time of two allelotypes was estimated to be about 700 thousand years ago. Discriminant function analysis based on 18 morphometric characters of 302 specimens representing 12 populations revealed no morphological difference between two allelotypes. Artificial hybridization test indicates that there is an obvious genetic incogpatibility between two allelotypes and therefore it is assumed that isolating mechanism is completed.

• ETRI Journal
• /
• 제30권2호
• /
• pp.194-204
• /
• 2008

The online collection of coarse-grained traffic information, such as the total number of flows, is gaining in importance due to a wide range of applications, such as congestion control and network security. In this paper, we focus on an active queue management scheme called SRED since it estimates the number of active flows and uses the quantity to indicate the level of congestion. However, SRED has several limitations, such as instability in estimating the number of active flows and underestimation of active flows in the presence of non-responsive traffic. We present a Markov model to examine the capability of SRED in estimating the number of flows. We show how the SRED cache hit rate can be used to quantify the number of active flows. We then propose a modified SRED scheme, called hash-based two-level caching (HaTCh), which uses hashing and a two-level caching mechanism to accurately estimate the number of active flows under various workloads. Simulation results indicate that the proposed scheme provides a more accurate estimation of the number of active flows than SRED, stabilizes the estimation with respect to workload fluctuations, and prevents performance degradation by efficiently isolating non-responsive flows.

• 한국콘텐츠학회논문지
• /
• 제10권5호
• /
• pp.45-51
• /
• 2010

복제된 AP가 설치되면 무선 스테이션들이 현재 연결된 정상적인 AP와 연결을 끊으며 그 후 복제된 AP가 정상적인 AP 보다 신호강도가 세다면 복제된 AP와 연결(association)설정이 이루어진다. 이로 인해 무선 스테이션들은 공격으로부터 노출되게 된다. 본 연구에서는 정상적인 AP와 무선 스테이션간의 연결설정이 이루어질 때의 접속 시간과 프레임 시퀀스 번호를 이용하여 복제된 AP와 정상적인 AP를 식별하고 복제된 AP를 차단시켰다. NS-2를 이용한 시뮬레이션의 결과, 본 논문에서 제안하는 메커니즘을 통해 무선 스테이션들의 복제된 AP의 등장을 판별할 수 있게 되어 보다 안전한 무선 랜 환경을 구축할 수 있게 되었다.