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Enumerating typical abelian prime-fold coverings of a circulant graph
Feng, R.,Kwak, J.H.,Kwon, Y.S. North-Holland Pub. Co ; Elsevier Science Ltd 2009 Discrete mathematics Vol.309 No.8
Enumerating the isomorphism classes of several types of graph coverings is one of the central research topics in enumerative topological graph theory (see [R. Feng, J.H. Kwak, J. Kim, J. Lee, Isomorphism classes of concrete graph coverings, SIAM J. Discrete Math. 11 (1998) 265-272; R. Feng, J.H. Kwak, Typical circulant double coverings of a circulant graph, Discrete Math. 277 (2004) 73-85; R. Feng, J.H. Kwak, Y.S. Kwon, Enumerating typical circulant covering projections onto a circulant graph, SIAM J. Discrete Math. 19 (2005) 196-207; SIAM J. Discrete Math. 21 (2007) 548-550 (erratum); M. Hofmeister, Graph covering projections arising from finite vector spaces over finite fields, Discrete Math. 143 (1995) 87-97; M. Hofmeister, Enumeration of concrete regular covering projections, SIAM J. Discrete Math. 8 (1995) 51-61; M. Hofmeister, A note on counting connected graph covering projections, SIAM J. Discrete Math. 11 (1998) 286-292; J.H. Kwak, J. Chun, J. Lee, Enumeration of regular graph coverings having finite abelian covering transformation groups, SIAM J. Discrete Math. 11 (1998) 273-285; J.H. Kwak, J. Lee, Isomorphism classes of graph bundles, Canad. J. Math. XLII (1990) 747-761]). A covering is called abelian (or circulant, respectively) if its covering graph is a Cayley graph on an abelian (or a cyclic, respectively) group. A covering p from a Cayley graph Cay(A,X) onto another Cay (Q,Y) is called typical if the map p:A->Q on the vertex sets is a group epimorphism. Recently, the isomorphism classes of connected typical circulant r-fold coverings of a circulant graph are enumerated in [R. Feng, J.H. Kwak, Typical circulant double coverings of a circulant graph, Discrete Math. 277 (2004) 73-85] for r=2 and in [R. Feng, J.H. Kwak, Y.S. Kwon, Enumerating typical circulant covering projections onto a circulant graph, SIAM J. Discrete Math. 19 (2005) 196-207; SIAM J. Discrete Math. 21 (2007) 548-550 (erratum)] for any r. As a continuation of these works, we enumerate in this paper the isomorphism classes of typical abelian prime-fold coverings of a circulant graph.
남윤성,김현주,이숙환,곽인평,윤태기,차광열,Nam, Y.S.,Kim, H.J.,Lee, S.H.,Kwak, I.P.,Yoon, T.K.,Cha, K.Y. 대한생식의학회 1999 Clinical and Experimental Reproductive Medicine Vol.26 No.2
Different Y mutation in Yq11 occurring de novo in sterile males were first described 19 years ago. Since the phenotype of the patients was always associated with azoospermia or severe oligospermia, it was postulated that these mutations interrupt a Y spermatogenesis locus in the euchromatic Y region (Yq11) called azoospermia factor (AZF). Recently, it became possible to map AZF mutations to different subregions in Yq11by molecular deletion mapping. This indicated that azoospermia is possibly caused by more than one Y gene in Yq11 and the Yq11 chromatin structure. The frequency of AZF mutations in idiopathic sterile males $(5{\sim}20%)$ may indicate a need for a general screening programme for its analysis in infertility clinic. We have experienced a case of deletion distal to Yq11 region in azoospermic patient. So we report this case with a brief review of literatures.
액체금속로 Y-구조물의 비탄성 열응력 해석 및 손상평가에 관한 유한요소해석
곽대영,임용택,김종범,이형연,유봉,Kwak, D.Y.,Im, Y.T.,Kim, J.B.,Lee, H.Y.,Yoo, B. 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.7
LMFBR(Liquid Metal Fast Breeder Reactor) vessel is operated under the high temperatures of 500-550.deg. C. Thus, transient thermal loads were severe enough to cause inelastic deformation due to creep-fatigue and plasticity. For reduction of such inelastic deformations, Y-piece structure in the form of a thermal sleeve is used in LMFBR vessel under repeated start-up, service and shut-down conditions. Therefore, a systematic method for inelastic analysis is needed for design of the Y-piece structure subjected to such loading conditions. In the present investigation, finite element analysis of heat transfer and inelastic thermal stress were carried out for the Y-piece structure in LMFBR vessel under service conditions. For such analysis, ABAQUS program was employed based on the elasto-plastic and Chaboche viscoplastic constitutive equations. Based on numerical data obtained from the analysis, creep-fatigue damage estimation according to ASME Code Case N-47 was made and compared to each other. Finally, it was found out that the numerical predictio of damage level due to creep based on Chaboche unified viscoplastic constitutive equation was relatively better compared to elasto-plastic constitutive formulation.
Dichromated Gelatin 필름의 홀로그램 회절효율
곽종훈,임용석,이윤우,최옥식,이영락 嶺南大學校 基礎科學硏究所 1996 基礎科學硏究 Vol.16 No.-
Time-dependent diffraction efficiency is measured during hologram formations in a dichromated gelatin film. It is observed that the refractive index modulation is strongly nonlinear with exposure time and intensity. In order to explain the complicated hologram formation dynamics, we present a phenomenological model for photoinduced refractive index changes by assuming that two photochemical reaction centers are responsible for the hologram formations. We also measured the polarization dependent diffraction efficiency for various incident angle.
진공 증착법을 이용한 비정질 As_2S_3박막의 제작 및 투과 스펙트럼을 이용한 광학 상수 결정
우성용,이상조,김지영,김건엽,곽종훈 嶺南大學校基礎科學硏究所 2002 基礎科學硏究 Vol.22 No.-
We fabricated the amorphous chalcogenide As_2S_3 thin film by thermal evaporation. We also measured and analysed the optical constants of refractive index, absorption coefficient, thickness of deposited amorphous As_2S_3 thin film and optical energy gap by simple measurement of transmittance spectrum.
The degree complexity of smooth surfaces of codimension 2
Ahn, J.,Kwak, S.,Song, Y. Academic Press 2012 Journal of symbolic computation Vol.47 No.5
For a given term order, the degree complexity of a projective scheme is defined by the maximal degree of the reduced Grobner basis of its defining saturated ideal in generic coordinates (Bayer and Mumford, 1993). It is well known that the degree complexity with respect to the graded reverse lexicographic order is equal to the Castelnuovo-Mumford regularity (Bayer and Stillman, 1987). However, much less is known if one uses the graded lexicographic order (Ahn, 2008; Conca and Sidman, 2005). In this paper, we study the degree complexity of a smooth irreducible surface in P<SUP>4</SUP> with respect to the graded lexicographic order and its geometric meaning. As in the case of a smooth curve (Ahn, 2008), we expect that this complexity is closely related to the invariants of the double curve of a surface under a generic projection. As results, we prove that except in a few cases, the degree complexity of a smooth surface S of degree d with h<SUP>0</SUP>(I<SUB>S</SUB>(2))<>0 in P<SUP>4</SUP> is given by 2+(degY<SUB>1</SUB>(S)-12)-g(Y<SUB>1</SUB>(S)), where Y<SUB>1</SUB>(S) is a double curve of degree (d-12)-g(S@?H) under a generic projection of S. In particular, this complexity is actually obtained at the monomial x<SUB>0</SUB>x<SUB>1</SUB>x<SUB>3</SUB><SUP>(degY<SUB>1</SUB>(S)-12)-g(Y<SUB>1</SUB>(S))</SUP> where k[x<SUB>0</SUB>,x<SUB>1</SUB>,x<SUB>2</SUB>,x<SUB>3</SUB>,x<SUB>4</SUB>] is a polynomial ring defining P<SUP>4</SUP>. Exceptional cases are a rational normal scroll, a complete intersection surface of (2,2)-type, or a Castelnuovo surface of degree 5 in P<SUP>4</SUP> whose degree complexities are in fact equal to their degrees. This complexity can also be expressed in terms of degrees of defining equations of I<SUB>S</SUB> in the same manner as the result of A. Conca and J. Sidman (Conca and Sidman, 2005). We also provide some illuminating examples of our results via calculations done withMacaulay 2 (Grayson and Stillman, 1997).
Dichromated Gelatin 박막에서의 위상 홀로그램
최옥식,성기영,이영락,곽종훈,임용석 嶺南大學校基礎科學硏究所 1996 基礎科學硏究 Vol.16 No.-
The Simplified method for making dichromated gelatin hologram is presented. Starting with Agfa 8E75HD plates, the complete processing time is just 2 hours and high diffraction efficiency over 80% is obtained.