• Title, Summary, Keyword: Sectional dimension

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CERTAIN CLASS OF QR-SUBMANIFOLDS OF MAXIMAL QR-DIMENSION IN QUATERNIONIC SPACE FORM

  • Kim, Hyang Sook;Pak, Jin Suk
    • Honam Mathematical Journal
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    • v.35 no.2
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    • pp.147-161
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    • 2013
  • In this paper we determine certain class of $n$-dimensional QR-submanifolds of maximal QR-dimension isometrically immersed in a quaternionic space form, that is, a quaternionic K$\ddot{a}$hler manifold of constant Q-sectional curvature under the conditions (3.1) concerning with the second fundamental form and the induced almost contact 3-structure.

Effects of Cross-Sectional Dimension and Moisture Profile of Small Specimens on Characteristics of Ultrasonic Wave Propagation (목재의 단면적과 수분경사가 초음파 전달 특성에 미치는 효과)

  • Kang, He-Yang;Lee, Kwan-Young
    • Journal of the Korean Wood Science and Technology
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    • v.28 no.2
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    • pp.19-24
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    • 2000
  • Effects of the cross-sectional dimension and moisture profile of wood specimens on the ultrasonic sound velocities of radiata pine heartwood and sapwood. Each moisture profile model specimen was made by composing five wood pieces with various moisture contents. As the cross-sectional dimensions decreased the ultrasonic velocities of both heartwood and sapwood decreased by 4~8%. In the ultrasonic signals transmitted through the specimens low frequency components more dominated than high frequency components as the dimension of cross section increased. The specimens with the same average MCs and different moisture profiles showed different ultrasonic velocities. By plotting the ultrasonic velocities against the average moisture contents of the inner three pieces of the moisture profile model specimens it was revealed that three distinct plot patterns existed.

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SECTIONAL CURVATURE OF CONTACT C R-SUBMANIFOLDS OF AN ODD-DIMENSIONAL UNIT SPHERE

  • Kim, Hyang-Sook;Pak, Jin-Suk
    • Bulletin of the Korean Mathematical Society
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    • v.42 no.4
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    • pp.777-787
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    • 2005
  • In this paper we study (n + 1)-dimensional compact contact CR-submanifolds of (n - 1) contact CR-dimension immersed in an odd-dimensional unit sphere $S^{2m+1}$. Especially we provide necessary conditions in order for such a sub manifold to be the generalized Clifford surface $$S^{2n_1+1}(((2n_1+1)/(n+1))^{\frac{1}{2}})\;{\times}\;S^{2n_2+1}(((2n_2+1)/(n+1)^{\frac{1}{2}})$$ for some portion (n1, n2) of (n - 1)/2 in terms with sectional curvature.

Generic submanifolds of a quaternionic kaehlerian manifold with nonvanishing parallel mean curvature vector

  • Jung, Seoung-Dal;Pak, Jin-Suk
    • Journal of the Korean Mathematical Society
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    • v.31 no.3
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    • pp.339-352
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    • 1994
  • A sumbanifold M of a quaternionic Kaehlerian manifold $\tilde{M}^m$ of real dimension 4m is called a generic submanifold if the normal space N(M) of M is always mapped into the tangent space T(M) under the action of the quaternionic Kaehlerian structure tensors of the ambient manifold at the same time.The purpose of the present paper is to study generic submanifold of quaternionic Kaehlerian manifold of constant Q-sectional curvature with nonvanishing parallel mean curvature vector. In section 1, we state general formulas on generic submanifolds of a quaternionic Kaehlerian manifold of constant Q-sectional curvature. Section 2 is devoted to the study generic submanifolds with nonvanishing parallel mean curvature vector and compute the restricted Laplacian for the second fundamental form in the direction of the mean curvature vector. As applications of those results, in section 3, we prove our main theorems. In this paper, the dimension of a manifold will always indicate its real dimension.

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REAL n-DIMENSIONAL QR-SUBMANIFOLDS OF MAXIMAL QR-DIMENSION IMMERSED IN QP(n+p)/4

  • Kim, Hyang-Sook;Kwon, Jung-Hwan;Pak, Jin-Suk
    • Communications of the Korean Mathematical Society
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    • v.24 no.1
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    • pp.111-125
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    • 2009
  • The purpose of this paper is to study n-dimensional QR-submanifolds of (p-1) QR-dimension immersed in a quaternionic projective space $QP^{(n+p)/4}$ of constant Q-sectional curvature 4 and especially to determine such submanifolds under the additional condition concerning with shape operator.

A New Model for the Analysis of Non-spherical Particle Growth Using the Sectional Method (구간해석방법을 통한 새로운 비구형 입자성장해석 모델)

  • Jeong, Jae-In;Choi, Man-Soo
    • Proceedings of the KSME Conference
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    • pp.416-421
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    • 2000
  • We have developed a simple model for describing the non-spherical particle growth phenomena using modified 1-dimensional sectional method. In this model, we solve simultaneously particle volume and surface area conservation sectional equations which consider particles' irregularities. From the correlation between two conserved properties of sections, we can predict the evolution of the aggregates' morphology. We compared this model with a simple monodisperse-assumed model and more rigorous two dimensional sectional model. For the comparison, we simulated silica and titania particle formation and growth in a constant temperature reactor environment. This new model shows a good agreement with the detailed two dimensional sectional model in total number concentration, primary particle size. The present model can also successfully predict particle size distribution and morphology without costing very heavy computation load and memory needed for the analysis of two dimensional aerosol dynamics.

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Vibration Characteristic Analysis of a Duel-cooled Fuel Rod according to the Cross-sectional Dimensions and the Span Length (이중냉각 연료봉의 단면치수와 스팬길이에 따른 진동특성해석)

  • Lee, Kang-Hee;Kim, Jae-Yong;Lee, Yung-Ho;Yoon, Kyung-Ho;Kim, Hyung-Kyu
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.9
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    • pp.819-825
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    • 2007
  • Vibration characteristics of an duel-cooling cylindrical fuel rod, which was proposed as a candidate design of fuel's cross section for the ultra-high burnup nuclear fuel, according to the cross-sectional dimensions and the number of supports or the span length were analytically studied. Finite element(FE) modeling for the annular cross sectional fuel was based on the methodology, that have been proven by the test verification, for the conventional PWR nuclear fuel rod. A commercial FEA code, ABAQUS, was used for the FE modeling and analysis. A planar beam element (B21) that uses a linear interpolation was used for the fuel rod and a linear spring element for the spring and dimple of the SG. Natural frequencies and mode shape were calculated according to the preliminary design candidates for the fuel's cross sectional dimension and the number of span. From the analysis results, the design scheme of the annular fuel compatible to the present PWR nuclear reactor core was discussed in terms of the number of supports and fuel's cross section.

A Study on the Effects of Cross-sectional Dimension Change of Brake Pad Specimen on the Uncertainty of the Compressive Strength (제동 패드의 압축강도시편의 단면치수변화가 압축강도 불확도에 미치는 영향 분석)

  • Park, Soo Hong;Park, Jin Kyu;Kim, Si Wan;Park, Chan Kyoung
    • Journal of the Korean Society for Railway
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    • v.17 no.4
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    • pp.223-227
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    • 2014
  • The brake pad is one of the basic brake elements of a railway vehicle. It accomplishes braking action by friction between a pad and a brake disc. Because the brake pad must endure specified high pressure, the compressive strength is managed as the main performance factor. The standards for measuring the compressive strength of brake pads are KRS, KRCS, and KRT. These standards specify the size of the test piece for measuring compressive strength as $20mm{\times}10mm{\times}15mm$ ($W{\times}D{\times}H$). To reduce the uncertainty of the compressive strength, factors of uncertainty were analyzed. The results show that changing the dimensions of the cross section was useful to reduce the uncertainty. The uncertainty due to the new cross-sectional dimension shows the effectiveness of reducing uncertainty.

A New Model for the Analysis of Non-Spherical Particle Growth (새로운 비구형 입자 성장 해석 모델)

  • Jeong, Jae-In;Choi, Man-Soo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.24 no.7
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    • pp.1020-1027
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    • 2000
  • A simple model for describing the non-spherical particle growth phenomena has been developed. In this model, we solve simultaneously particle volume and surface area conservation sectional equations that consider particles' non-sphericity. From the correlation between two conserved properties of sections, we can predict the evolution of the aggregates' morphology. This model was compared with a simple monodisperse-assumed model and more rigorous two-dimensional sectional model. For comparison, formation and growth of silica particles have been simulated in a constant temperature reactor environment. This new model showed good agreement with the detailed two-dimensional sectional model in total number concentration and primary particle size. The present model successfully predicted particle size distribution and morphology without costing very heavy computation load and memory needed for the analysis of two dimensional aerosol dynamics.

Optimum Design of Prestressed Concrete Girder Railway Bridge (프리스트레스트 콘크리트 거더 철도교의 최적설계)

  • Lee Jong-Min;Seo Dong-Joo;Lee Tae-Gyun;Lee Joung-Sun;Cho Sun-Kyu
    • Journal of the Korean Society for Railway
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    • v.8 no.3
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    • pp.267-275
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    • 2005
  • Prestressed concrete girder(PSC girder) bridges have been used widely at the railway as well as highway because they are great in the functional and economical efficiency. Also they have the advantage of convenience of design and construction. However it could be easily verified that the section of PSC girder is excessive design, which has much redundancy against design loads. Thus, in this paper the formulation of the optimum design for PSC girder railway bridge is suggested and dominant design variables and constraints are inquired as performing the optimum design. In order to effective optimum design, design variables are formulated as PSC girder sectional dimension and girder space. The objective is adopted as total cost of PSC girder railway bridge. Also, constraints are formulated according to Korean railway design specification and considering construction-ability such as PS anchorage and girder space. Using the proposed optimum design system, optimum PSC girder railway bridge design has been performed. And from the results of analysis it is suggested to denote the optimum section which satisfies the structural safety and economical efficiency all together.