회전하는 하나의 내부 원통에서 서로 다른 반경비가 Taylor-Couette 유동에 미치는 영향

승삼선(Samsun Seung),김상일(Sangil Kim) 대한기계학회 2018 大韓機械學會論文集B Vol.42 No.12

회전하는 하나의 내부 원통이 서로 다른 반경비를 갖는 경우에 Taylor vortex형성에 미치는 영향에 대해 수치해석을 수행하였다. 서로 다른 반경비는 내부 원통 중앙을 기준으로 동일한 폭에 깊이를 달리한 것으로 먼저 반경비가 0.83인 매끈한 내부 원통에 대한 수치계산 결과를 기존의 실험결과와 비교하여, 타당성을 검토하였다. 그런 다음, 내부 원통 중앙에 동일한 홈의 폭에 깊이를 각각 3, 6, 9, 12 mm 달리한 내부 원통에 회전수 25, 100 rpm인 경우의 수치계산 결과와 비교하였다. 그 결과, Taylor vortex는 층류인 경우 내부 원통 양끝에서 생성되기 시작하지만 홈이 있는 경우에는 홈 모서리에서도 이루어짐을 확인하였다. 홈의 깊이와 내부 원통의 회전수에 따라 쌍으로 이루어진 Taylor vortex셀의 폭이 달라졌으며, 회전수가 큰 경우에는 작은 경우보다 Taylor vortex 셀의 폭이 넓어져 개수가 감소하였다. 또한 각각의 Taylor vortex 쌍의 vortex 중심은 이웃하고 있는 vortex 쌍 사이의 vortex 중심보다 더 가깝게 자리하고 있음을 확인하였다. The Taylor-Couette flow in a rotating inner cylinder with different radius ratios has been studied numerically to show the effects of Taylor vortices formation, where different radius ratios refer to the varied depths having the same width based on the center of the inner cylinder. The numerical calculations results are compared with those of the straight inner cylinder. In order to examine the feasibility of the numerical calculations, the numerical results are compared with existing experimental results for a straight inner cylinder. Then, we compare the numerical results in the case of inner cylinders with different radius ratios. Initially, laminar Taylor vortices form at the end walls and corners of the groove. Results show that the widths of pairs of Taylor vortex cells are varied according to the depth and rotational speed of the inner cylinder. In the case involving a higher rotational speed of inner cylinder widths, and the number of pairs of Taylor vortex cells are wide and decreasing than low rotational speed of it. In addition, the vortex centers of each Taylor vortex pair are closer together than the vortex centers between neighboring vortex pairs.

단독 원기둥 주위의 후류유동에 관한 연구

승삼선(Samsun Seung),이재성(Jaesung Lee),김상일(Sangil Kim) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.춘계 No.-

This experimental study is investigated the wake flow around a elastically supported circular cylinder. In this study, the Reynolds Numbers are varied in the region of 1.4×10<SUP>4</SUP>≤Re≤3.2×10<SUP>4</SUP>. Under these conditions we have figured out the process of wake mechanism and moving path of the vortex by measuring the velocity at each position in the wake around a cylinder. Also these facts from wind tunnel test are proved by flow visualization test through water channel. As a result, we have concluded as followings : i) The process(formation→growth→collapse) of vortex in the wake around a cylinder is observed, ii) The vortex efflux angle is about 16~17 degrees under the experimental conditions. These degrees have no concern with velocity change and the existence of flow-induced vibration of a cylinder. iii) The moving path of vortex center is inferred by spectrum analysis of fluctuating velocity behind the cylinder. These are confirmed by doing visualization test.

順接偶然確定條件表現についての一考察 : 室町末期より近世末期までの口語體資料を中心た 실정말기부터 근세말기까지의 구어체 자료를 중심으로

金三順 한국일어일문학회 2003 日語日文學硏究 Vol.47 No.1

本稿は,古代語に確定條件(必然·偶然)を表す「己然形+ば」による形式の消減の(時(期とかかわりのある寶町末期より近代末期までの口語體資料を中心に主に順接偶然確定條件をめぐって史的變??の周 と「たら」の由來(유래)について考察してみた結果,次のように推定することができた. (1)古代語の「己然形+ば」による確定條件が,寶町時代から江戶前期にかけて衰退していくことになったと從來の說については,今回の調査によれば,もっとも??著な變選を見せている時期は,近代中期頃であろうと推定することができた. (2)必然條件は寶町末期から接續形式の多樣化を見せ始め,近代末期頃になれば, 己然形+ば」いよる必然條件は消減の傾向を見せる.一方,偶然條件は近代初期から接續形式の多樣化を見せ始め,近代末期頃までも,「己然形+ば」による偶然條件は依然と健全な姿を見せていることから,「己然形+ば」いよる確定條件は大體近代末期ごろ消減するとは一槪にはいいがたい. (3)偶然條件の「と」の語源は,基本的には寶町初期頃の「とひとしく」から出發したもので,近代末期頃急激な伸張を見せている.一方,「己然形+ば」による偶然條件は,近代初期より次第に衰退の傾向は見せているが,近代末期に至っても「己然形+ば」>「と」>「たら」>「ところが(で,に,へ)>「に」の順お く用いられ,「己然形+ば」「と」「たら」の形式は近世末期頃の主要な偶然條件の接續形式であったといえよう. (4)近代末期に偶然條件として定着する「たら」の由來は,近代末期とりその以前を以って,すでに偶然條件として定着した「たれ+ば」からの音轉と考えられる. 順接假定條件(完了性·非完了性)の役割を擔っていた「未然形+ば」の形式についての史的變??と「なら」「たら」などの由來の問題までは至らあっかた.それらお問題については今後の課題として次同お機會に讓ることにする.

A Genome-Wide Identification of Genes Potentially Associated with Host Specificity of Brucella Species

김경모,김규원,Samsun Sung,김희발 한국미생물학회 2011 The journal of microbiology Vol.49 No.5

Brucella species are facultative intracellular pathogenic α-Proteobacteria that can cause brucellosis in humans and domestic animals. The clinical and veterinary importance of the bacteria has led to well established studies on the molecular mechanisms of Brucella infection of host organisms. However, to date, no genome-wide study has scanned for genes related to the host specificity of Brucella spp. The majority of bacterial genes related to specific environmental adaptations such as host specificity are well-known to have evolved under positive selection pressure. We thus detected signals of positive selection for individual orthologous genes among Brucella genomes and identified genes related to host specificity. We first determined orthologous sets from seven completely sequenced Brucella genomes using the Reciprocal Best Hits (RBH). A maximum likelihood analysis based on the branch-site test was accomplished to examine the presence of positive selection signals, which was subsequently confirmed by phylogenetic analysis. Consequently, 12 out of 2,033 orthologous genes were positively selected by specific Brucella lineages, each of which belongs to a particular animal host. Extensive literature reviews revealed that half of these computationally identified genes are indeed involved in Brucella host specificity. We expect that this genome-wide approach based on positive selection may be reliably used to screen for genes related to environmental adaptation of a particular species and that it will provide a set of appropriate candidate genes.

VCS: Tool for Visualizing Copy Number Variation and Single Nucleotide Polymorphism

Kim, HyoYoung,Sung, Samsun,Cho, Seoae,Kim, Tae-Hun,Seo, Kangseok,Kim, Heebal Asian Australasian Association of Animal Productio 2014 Animal Bioscience Vol.27 No.12

Copy number variation (CNV) or single nucleotide phlyorphism (SNP) is useful genetic resource to aid in understanding complex phenotypes or deseases susceptibility. Although thousands of CNVs and SNPs are currently avaliable in the public databases, they are somewhat difficult to use for analyses without visualization tools. We developed a web-based tool called the VCS (visualization of CNV or SNP) to visualize the CNV or SNP detected. The VCS tool can assist to easily interpret a biological meaning from the numerical value of CNV and SNP. The VCS provides six visualization tools: i) the enrichment of genome contents in CNV; ii) the physical distribution of CNV or SNP on chromosomes; iii) the distribution of log2 ratio of CNVs with criteria of interested; iv) the number of CNV or SNP per binning unit; v) the distribution of homozygosity of SNP genotype; and vi) cytomap of genes within CNV or SNP region.

An approach of orthology detection from homologous sequences under minimum evolution

Kim, Kyung Mo,Sung, Samsun,Caetano-Anollé,s, Gustavo,Han, Jae Yong,Kim, Heebal Oxford University Press 2008 Nucleic acids research Vol.36 No.17

<P>In the field of phylogenetics and comparative genomics, it is important to establish orthologous relationships when comparing homologous sequences. Due to the slight sequence dissimilarity between orthologs and paralogs, it is prone to regarding paralogs as orthologs. For this reason, several methods based on evolutionary distance, phylogeny and BLAST have tried to detect orthologs with more precision. Depending on their algorithmic implementations, each of these methods sometimes has increased false negative or false positive rates. Here, we developed a novel algorithm for orthology detection that uses a distance method based on the phylogenetic criterion of minimum evolution. Our algorithm assumes that sets of sequences exhibiting orthologous relationships are evolutionarily less costly than sets that include one or more paralogous relationships. Calculation of evolutionary cost requires the reconstruction of a neighbor-joining (NJ) tree, but calculations are unaffected by the topology of any given NJ tree. Unlike tree reconciliation, our algorithm appears free from the problem of incorrect topologies of species and gene trees. The reliability of the algorithm was tested in a comparative analysis with two other orthology detection methods using 95 manually curated KOG datasets and 21 experimentally verified EXProt datasets. Sensitivity and specificity estimates indicate that the concept of minimum evolution could be valuable for the detection of orthologs.</P>

상류에 있는 물체의 직경변화에 따라 후류 물체가 받는 영향

김진남(Jinnam Kim),승삼선(Samsun Seung),김상일(Sangil Kim) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.5

This experimental study is carried out the impacts of a downstream cylinder in the wake change on upstream objects diameter. The V-shaped object is located in the upstream of the test section and the circular cylinder included load-cell is located in the downstream. We investigated the velocity distribution of the wake emitted from the upstream object with changing its diameter. Also the fluctuating lift coefficient and Karman-vortex emission frequency are investigated with changing position of downstream cylinder. They are concluded as followings: i) the flow velocity in the wake is smaller than main stream, ii) the lock-in phenomenon is occurred when the upstream objects diameter is bigger than downstream cylinders one, iii) in order to be maximum fluctuating lift force of the downstream cylinder in the wake, the position of the downstream cylinder must be moved with changing diameter of the upstream object together.

HGTree: database of horizontally transferred genes determined by tree reconciliation

Jeong, Hyeonsoo,Sung, Samsun,Kwon, Taehyung,Seo, Minseok,Caetano-Anollé,s, Kelsey,Choi, Sang Ho,Cho, Seoae,Nasir, Arshan,Kim, Heebal Oxford University Press 2016 Nucleic acids research Vol.44 No.d1

<P>The HGTree database provides putative genome-wide horizontal gene transfer (HGT) information for 2472 completely sequenced prokaryotic genomes. This task is accomplished by reconstructing approximate maximum likelihood phylogenetic trees for each orthologous gene and corresponding 16S rRNA reference species sets and then reconciling the two trees under parsimony framework. The tree reconciliation method is generally considered to be a reliable way to detect HGT events but its practical use has remained limited because the method is computationally intensive and conceptually challenging. In this regard, HGTree (http://hgtree.snu.ac.kr) represents a useful addition to the biological community and enables quick and easy retrieval of information for HGT-acquired genes to better understand microbial taxonomy and evolution. The database is freely available and can be easily scaled and updated to keep pace with the rapid rise in genomic information.</P>

서로 다른 두 개의 와류방출 주파수간의 조화형 비선형 간섭

김상일(Sangil Kim),승삼선(Samsun Sueng),이승철(Seung-Chul Lee),김효준(Hyojun Kim) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.5

This study is on the nonlinear interaction between two different vortex shedding frequencies from the cylinder having two diameters. In particular, two different vortex shedding frequencies are made by making the cylinder having two diameters artificially. And the flow velocity fluctuations behind the cylinder are measured three dimensionally. Also, we made a hole of pressure transducer for measuring the pressure on the cylinder surface and measured the pressure of cylinder surface. The pressure signal from the pressure transducer is used as basic signal. The TSC is used for checking the strength of nonlinear interaction between two different vortex shedding frequencies. As a result, it is clarified that; I) frequency distribution behind the cylinder. ii) three dimensional flow state behind the cylinder by calculation of ensemble average. iii) a close connection between the vertical vortex and change of low frequency by nonlinear interaction between two different vortex shedding frequencies from the cylinder having two diameters.

단독 원기둥 주위의 후류유동에 관한 연구

이재성(Jaesung Lee),김상일(Sangil Kim),승삼선(Samsun Seung) 대한기계학회 2015 大韓機械學會論文集B Vol.39 No.11

본 연구는 탄성지지된 단독원기둥의 후류에 관한 실험적연구이다. 본 실험은 1.4x10⁴ ≤ Re ≤ 3.2x10⁴ 의레이놀즈수 범위에서 이루어졌으며, 원기둥 후류의 위치별 유속을 측정하여 후류에서 발생되는 와류의 생성에서 소멸까지의 과정 및 와류의 이동 궤적을 조사한 연구이다. 아울러 강제진동실험장치를 이용한 가시화실험을 통하여 풍동실험에서의 결과를 증명하였다. 그 결과 다음과 같은 결과를 얻었다. 1)흐르는 유체에 존재하는 원기둥의 후류에 생성되는 와류의 생성성장소멸 과정을 확인 할 수 있었다. 2) 와류의 퍼짐각도는 16°~17°가량으로 주류속의 변화와 유력진동의 유무에 상관없이 일정하다. 3) 후류에서 변동 유속의 스펙트럼 분석을 통해 와류의 중심이 이동하는 궤적을 유추할 수 있었고, 가시화 실험을 통해 그것을 확신할 수 있다. This experimental study investigated the wake flow around an elastically supported circular cylinder. In this study, the Reynolds numbers are varied in the region of 1.4x10⁴≤ Re ≤3.2x10⁴. Under these conditions, we have captured the process of the wake mechanism and the moving path of the vortex by measuring the velocity at each position in the wake around the cylinder. Further, these facts from the wind tunnel test are proved by a flow visualization test through a water channel. From the result, we have arrived at the following conclusions : i) The process (formation growth collapse) of vortex is observed in the wake around the cylinder, ii) The vortex efflux angle is approximately 16°~17° under the experimental conditions. These angles have no relationship with the velocity change and the existence of flow-induced vibrations of the cylinder, and iii) The moving path of the vortex center is obtained by spectrum analysis of the fluctuating velocity behind the cylinder. These are confirmed by conducting visualization tests.