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Yoo, Hye Sook,Eah, Jae-Yong,Kim, Jong Soo,Kim, Young-Jun,Min, Mi-Sook,Paek, Woon Kee,Lee, Hang,Kim, Chang-Bae Korean Society for Molecular Biology 2006 Molecules and cells Vol.22 No.3
<P>DNA barcoding, an inventory of DNA sequences from a standardized genomic region, provides a bio-barcode for identifying and discovering species. Several recent studies suggest that the sequence diversity in a 648 bp region of the mitochondrial gene for cytochrome c oxi- dase I (COI) might serve as a DNA barcode for identify- ing animal species such as North American birds, in- sects and fishes. The present study tested the effective- ness of a COI barcode in discriminating Korean bird species. We determined the 5' terminus of the COI bar- code for 92 species of Korean birds and found that spe- cies identification was unambiguous; the genetic differ- ences between closely related species were, on average, 25 times higher than the differences within species. We identified only one misidentified species out of 239 specimens in a genetic resource bank, so confirming the accuracy of species identification in the banking system. We also identified two potential composite species, calling for further investigation using more samples. The finding of large COI sequence differences between species confirms the effectiveness of COI barcodes for identifying Korean bird species. To bring greater reliability to the identification of species, increased in- tra- and interspecies sampling, as well as supplementa- tion of the mitochondrial barcodes with nuclear ones, is needed.</P>
Wrinkling control of inflatable booms using shape memory alloy wires
Yoo, Eun-Jung,Roh, Jin-Ho,Han, Jae-Hung Institute of Physics Publishing 2007 Smart materials & structures Vol.16 No.2
<P>An inflatable boom is a fundamental structural part of inflatable space structures maintaining the expected configuration of the whole system, supporting external loads and guaranteeing the efficiency of the membrane surface. The inflatable structure is a thin film structure compactly packaged and expanded to the desired configuration by the internal gas pressure. But the structures can be easily distorted and even collapsed by wrinkling. In this study, the behavior of an inflatable boom structure is investigated numerically and experimentally. To achieve a better bending strength, the methodology to control the wrinkling growth and the deformed configuration of the inflatable boom structure with a shape memory alloy (SMA) wire actuator is developed. To understand the nonlinear behavior of an inflatable boom due to wrinkling, the structure is numerically modeled using the ABAQUS finite element program with a wrinkling algorithm developed based on the Miller–Hedgepeth membrane theory. To verify the present analysis method, the inflatable boom made of Kapton film is examined by the bending tests with various internal pressures. To delay the growth of wrinkling that rapidly deteriorates the bending strength of the inflatable boom, a SMA wire actuator is applied. SMA wires are attached on the edge of the inflatable boom and generate a recovery force to remove wrinkling and restore the deformation of the boom. </P>
류재흥(Jae Hung Yoo),정종철(Jong Cheol Jeong) 한국지능시스템학회 2001 한국지능시스템학회논문지 Vol.11 No.9
본 논문은 분류 문제의 훈련 패턴으로부터 형성되는 커널 공간의 저밀도 표현을 가능하게 하는 커널 방법에 대한 새로운 학습방법론을 제안한다. 선형 판별 함수에 대한 기존의 학습법 중에서 이완 절차가 SVM(Support Vector Machine) 분류기와 동등하게 선형분리 가능 패턴분류 문제의 최대 마진 분리 초평면을 얻을 수 있다. 기존의 이완 절차는 지원 벡터에 대한 필요 조건을 만족한다. 본 논문에서는 학습 중 지원 벡터를 확인하기 위한 충분 조건을 제시한다. 순차적 학습을 위하여 기존의 SVM을 확장하고 커널 판별함수를 정의한 후에 체계적인 학습방법을 제시한다. 실험 결과는 새 방법이 기존의 방법과 동등하거나 우수한 분류 성능을 갖고있음을 보여준다. In this paper, a new learning methodology for kernel methods that results in a sparse representation of kernel space from the training patterns for classification problems is suggested. Among the traditional algorithms of linear discriminant function, this paper shows that the relaxation procedure can obtain the maximum margin separating hyperplane of linearly separable pattern classification problem as SVM(Support Vector Machine) classifier does. The original relaxation method gives only the necessary condition of SV patterns. We suggest the sufficient condition to identify the SV patterns in the learning epochs. For sequential learning of kernel methods, extended SVM and kernel discriminant function are defined. Systematic derivation of learning algorithms is introduced. Experiment results show the new methods have the higher or equivalent performance compared to the conventional approach.
액체 로켓 터보 펌프 터빈의 천이 열전달 및 구조 해석
유재한(Jae-Han Yoo),최지훈(Ji-Hoon Choi),이인(In Lee),한재흥(Jae-Hung Han),전성민(Seong-Min Jeon),김진한(Jin-Han Kim) 한국항공우주학회 2004 韓國航空宇宙學會誌 Vol.32 No.3
유한요소법을 이용하여 액체 로켓 엔진 터보 펌프 터빈의 천이 열전달 및 구조 해석이 수행되었다. 해석 모델은 3차원 8절점 등매개변수 솔리드 요소로 구성되었으며, 전체 모델의 1/80만이 해석되었다. 열 스파이크를 포함하는 시동 조건과 정상상태에서의 하중이 고려되었다. 블레이드 면 위의 열전달 계수는 상용 열유동 해석 프로그램인 Fluent를 이용하였다. 개발된 유한 요소 코드를 이용하여 시동 및 정상상태에서 천이 열전달 응답을 구하였다. 또한, 원심력과 열하중이 가해질 때, 최대 응력 및 슈라우드의 변위를 구하였다. Thermal and structural finite element analyses were performed for the turbopump turbine bladed disk model with shroud of a liquid rocket engine. The only 1/80 part model was analyzed which consists of 3D eight node isoparametric solid elements. The applied loading history consists of a startup condition with a thermal spike and a steady state. Heat transfer coefficient on the blade was predicted using the commercial Navier-Stokes solver, Fluent. Transient thermal responses during startup and steady states were calculated using a 3D finite element code developed. Maximum stress and shroud tip displacement under the influence of centrifugal and thermal loading were also determined.