• Animal Systematics, Evolution and Diversity
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• 제13권1호
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• pp.29-36
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• 1997

한국산 기름종개속 어류중 Cobitis taenia complex의 집단간 유전적 차이에 따른 종 분화 여부를 밝히고자 6개 집단을 대상으로 mitochondrial DNA(mtDNA)의 RFLP분석을 실 시하였다. C. taenia complex mtDNA를 10개의 6-base cutting 제한효소로 처리한 다음 그 절편 양상을 비교, 분석한 결과 6개 집단 공히 mtDNA 의 전체 genome 크기는 약 17.0$\pm$ 0.5Kbp였으며 공동절편수(F)에서 C. t. taenia 2개집단과 C. t. stria와 C. t. lutheri 4개 집단 간의 F값은 평균 0.263으로 차이가 있었으나, C. t. striata 와 C. t. lutheri 사이는 F=0.569로 가깝게 나타났다. 염기치환율 (p)에 있어 C. t. taenia는 C. t. striata 및 C. t. lutheri와 평균 p=0.082로 뚜렷한 종간차이를 보였으나, C. t. striata와 C. t. lutheri 집단들은 p=0.033으로 매우 가까운 유사성을 나타내었다. MtDNA 분석결과 C. taenia complex 중 C. t. taenia는 완전히 종분화가 이루어진 별종으로, C. t. striata와 C. t. lutherisms 아직 종수준의 분화가 이루어지지 않은 아종으로 분류함이 타당하다고 사료된다.

• 암석학회지
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• 제11권3_4호
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• pp.121-137
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• 2002

옥천변성대의 변성진화사를 밝히기 위한 연구는 지난 수십여년간 많은 학자들에 의해 수행되어 왔다. 그 결과 옥천변성대의 변성조건이 약 $490-630^{\circ}C$, 4.2-9.4 kbar에 해당되는 중온-중압형에 속함이 밝혀졌고, 또한 시계방향의 압력-온도-시간 경로를 경험했음이 알려졌다. 이러한 결과는 드러스트 나페에 의해 옥천변성대의 지각 두께가 증가했음을 지시한다. 그러나 변성작용에 관련된 조산운동을 규명하는데는 여러 가지 어려움이 남아 있다 특히 변성시기에 대한 논란은 오랫동안 거듭되어 왔으며, 최근의 연구 결과는 옥천변성대의 최고변성작용 시기를 석탄기와 페름기의 경계 부근인 약 300-280 Ma로 규정짓는다 따라서 옥천변성대와 태백산분지는 별개의 지구조구로서 서로 다른 진화 과정을 겪었으리라 추정되며, 이들은 약 250-220 Ma사이에 봉합되어 옥천대를 형성했을 가능성이 있다. 이와 같은 결과는 옥천대의 진화과정에 대한 기존의 생각과 일부 배치되며 새로운 지체구조적 파라다임을 요구한다. 또한 옥천대가 일본의 히다연변대-히다변성대에 대비될 수 있음을 시사한다.

• 대한수학회지
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• 제49권2호
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• pp.265-291
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• 2012

In this paper, we consider the regularity theory and the existence of smooth solution of a degenerate fully nonlinear equation describing the evolution of the rolling stones with nonconvex sides: $\{M(h)=h_t-F(t,z,z^{\alpha}h_{zz})\;in\;\{0<z{\leq}1\}{\times}[0,T] \\ h_t(z,t)=H(h_z(z,t),h)\;{on}\;\{z=0\}$. We establish the Schauder theory for $C^{2,{\alpha}}$-regularity of h.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.291-294
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• 2005

The microstructure evolution of Alloy 718 during the direct age(DA) process was predicted using the recrystallization model and finite element analysis. The DA process of Alloy 718 was performed in two-step forging using capsulated cylindrical billets of 122mm in diameter and 180mm in height. In order to evaluate the microstructural change during the forging, a dynamic recrystallization model of Alloy 718 was implemented onto the user-subroutine of the commercial FEM code. The prediction of microstructure evolution in DA processed Alloy 718 pancake was compared with experimental results.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.781-782
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• 2009

• Progress in Superconductivity
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• 제3권2호
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• pp.140-145
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• 2002

An enhancement of the c-axis differential conductance around the zero-bias voltage near the superconducting transition temperature $T_{c}$ has been observed in $Au/Bi_2$$Sr_2$$CaCu_2$$O_{8+x}$ junctions. We attribute such an enhancement to the Andreev reflection (AR) between the surface Cu-O bilayer with suppressed superconductivity and the next superconducting Cu-O bilayer. The continuous evolution of the differential conductance, from gap like depression to an AR-like peak structure, around the zero-bias voltage points to weakening of the barrier strength of the nonsuperconducting layer between adjacent Cu-O bilayers as temperature approaches $T_{c}$ from below. The peak structure disappeared just below the bulk $T_{c}$ value of underdoped Bi2212 single crystals, whereas it survived up to ~1 K above $T_{c}$ in Junctions prepared on slightly overdosed crystals. According to a recently proposed theoretical consideration, a wider temperature range of the AR a bone $T_{c}$ is expected in the underdoped regime when phase-incoherent preformed pairs emerge in the pseudogap state. Our result is in contradiction to the preformed pair scenario. scenario.o.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2008년도 High Temperature Superconductivity Vol.XVIII
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• pp.89-89
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• 2008

• Animal Bioscience
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• 제36권7호
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• pp.991-1002
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• 2023

Objective: This study aimed to elucidate the underlying gene regions responsible for productive, phenotypic or adaptive traits in different ecological types of Tibetan sheep and the discovery of important genes encoding valuable traits. Methods: We used whole-genome resequencing to explore the genetic relationships, phylogenetic tree, and population genetic structure analysis. In addition, we identified 28 representative Tibetan sheep single-nucleotide polymorphisms (SNPs) and genomic selective sweep regions with different traits in Tibetan sheep by fixation index (Fst) and the nucleotide diversity (θπ) ratio. Results: The genetic relationships analysis showed that each breed partitioned into its own clades and had close genetic relationships. We also identified many potential breed-specific selective sweep regions, including genes associated with hypoxic adaptability (MTOR, TRHDE, PDK1, PTPN9, TMTC2, SOX9, EPAS1, PDGFD, SOCS3, TGFBR3), coat color (MITF, MC1R, ERCC2, TCF25, ITCH, TYR, RALY, KIT), wool traits (COL4A2, ERC2, NOTCH2, ROCK1, FGF5, SOX9), and horn phenotypes (RXFP2). In particular, a horn-related gene, RXFP2, showed the four most significantly associated SNP loci (g. 29481646 A>G, g. 29469024 T>C, g. 29462010 C>T, g. 29461968 C>T) and haplotypes. Conclusion: This finding demonstrates the potential for genetic markers in future molecular breeding programs to improve selection for horn phenotypes. The results will facilitate the understanding of the genetic basis of production and adaptive unique traits in Chinese indigenous Tibetan sheep taxa and offer a reference for the molecular breeding of Tibetan sheep.

• 소성∙가공
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• 제10권1호
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• pp.35-41
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• 2001

The high temperature deformation behavior of SCM 440 can be characterized by the hot torsion test in the temperature ranges of $900^{\circ}C$~$1100^{\circ}C$ and strain rate ranges of 0.05/sec~5/sec. The aim of this paper is to establish the quantitative equation of the volume fraction of dynamic recrystallization (DRX) as a function of processing variables, such as strain rate ($\varepsilon$), temperature (T), and strain ('$\varepsilon$). During hot deformation, the evolution of microstructure could be analyzed from work hardening rate ($\theta$). For the exact prediction of dynamic softening mechanism the critical strain ($\varepsilon_c$), the strain for maximum softening rate ($\varepsilon^*$ and Avrami' exponent (m') were quantitatively expressed by dimensionless parameter, Z/A, respectively. The transformation-effective strain-temperature curve for DRX could be composed. It was found that the calculated results were agreed with the experimental data for the steel at any deformation conditions.

• 대한수학회보
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• 제53권4호
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• pp.1113-1122
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• 2016

Let (M, g(t)) be a compact Riemannian manifold and the metric g(t) evolve by the Yamabe flow. In the paper we derive the evolution for the first eigenvalue of geometric operator $-{\Delta}_{\phi}+{\frac{R}{2}}$ under the Yamabe flow, where ${\Delta}_{\phi}$ is the Witten-Laplacian operator, ${\phi}{\in}C^2(M)$, and R is the scalar curvature with respect to the metric g(t). As a consequence, we construct some monotonic quantities under the Yamabe flow.