• Title/Summary/Keyword: Theoretical

Search Result 21,377, Processing Time 0.04 seconds

해운기업의 국제진출 동기에 대한 이론적 고찰 (A Theoretical Investigation on Global Expansion of Shipping Companies)

  • 정준식
    • 무역상무연구
    • /
    • 제44권
    • /
    • pp.181-210
    • /
    • 2009
  • This paper discusses global expansion and global strategies of shipping firms. Acknowledging the lack of research on global expansion by freight transport companies, this paper employs the resource-focused model, and explores "why shipping companies emerge" and "why the strategic behaviour of shipping companies is different in the global market". Despite there being a plethora of theoretical and empirical studies on the international operations of business organisations, it is acknowledged that researchers have largely neglected the issues regarding the international expansion within the freight transport industry. Identifying the general lack of contemporary studies concerning the international behaviour of shipping firms, this study addresses the important gap in our knowledge in the theoretical manner. The theoretical analysis suggests that the shipping company's internal resources can be a real reason for the international market participation.

  • PDF

강탄성 구역구조 및 구역벽에 관한 연구 (A Study on the Ferroelastic Domain Structure and Domain Walls)

  • 정희태;정세영
    • 한국결정학회지
    • /
    • 제11권1호
    • /
    • pp.34-41
    • /
    • 2000
  • The group-theoretical approach analyzing the domain structure and the domain wall orientations of the ferroelastic crystal was introduced. These theoretical results were investigated by comparing them with the experimental results of several ferroelastic crystals, CsPbCl₃, Pb₃(PO₄)₂, and LiCsSO₄, which were grown by the Czochralski and solution methods, respectively. both results were agreed well and also consistent with those of previous works such s the strain method and the geometrical consideration. The group-theoretical approach showed that the ferroelastic domain walls must be the crystallographical prominent planes with fixed indices and classified by the symmetry elements characterizing the permissible domain walls. So the group-theoretical approach could be suggested as a new method for analyzing the structure of the ferroelastic domain and domain walls.

  • PDF

修正죔맞춤 방법 을 이용한 複合圓통 의 彈性負荷能力 의 증대 (Increments of Elastic Lad Carrying Capacity of Compound Cylinder by Using Modified-Shrink-Fit Method)

  • 정성종;홍창선
    • 대한기계학회논문집
    • /
    • 제7권3호
    • /
    • pp.335-343
    • /
    • 1983
  • Modified-Shrink-Fit(MSF) method of compound cylinder is studied to increase elastic load carrying capacity (ELCC) of pressure vessel. The autofrettage and the shrink-fit processes are used to study the MSF process. Theoretical analyses based on the Tresca yield criterion, Hencky's total strain theory and elastic linearly strain-hardening material are carried out to derive closed form solutions. Experimental results are compared with theoretical results with various diameter ratios between outer (SM45C) and inner (SM20C) bloc cylinder. For various diameter ratios, increments of ELCC have errors in strains vs. internal loading pressures between experimental and theoretical results. But experimental results show good agreements with theoretical results in reyield pressurizing state. The increments of ELCC of compound cylinder manufactured by the MSF process is proved by measuring the residual stresses.

길이방향으로 주름진 원통셸의 진동 해석 (Vibration Analysis of Longitudinally Corrugated Cylindrical Shells)

  • 김영완
    • 한국소음진동공학회논문집
    • /
    • 제26권7호
    • /
    • pp.851-856
    • /
    • 2016
  • In this paper, the free vibration characteristics of longitudinally corrugated cylindrical shells is investigated by the theoretical analysis. The equivalent homogenization model is adapted to investigate the overall mechanical behavior of these corrugated shells. The corrugated element can be represented as an orthotropic material. Both the effective extensional and flexural stiffness of this equivalent orthotropic material are considered in the analysis. To demonstrate the validity of the proposed theoretical approach, the theoretical results are compared with those from 3D finite element analysis using ANSYS commercial code. Some numerical results are presented to check the effect of the geometric properties.

회전운동을 고려한 Cutout이 있는 복합재료 원통셸의 구조진동해석 및 최적설계 (Study on Structural Vibration Analysis and Design Optimization of Rotating Composite Cylindrical Shells with Cutout)

  • 이영신;김영완
    • 소음진동
    • /
    • 제8권3호
    • /
    • pp.467-476
    • /
    • 1998
  • The free vibration analysis and design optimization of the rotating composite cylindrical shells with a rectangular cutout are investigated by theoretical method. The Love's thin shell theory is used to derive the frequency equation. The theoretical results are obtained by application of the energy method employing the Rayleigh-Ritz procedure. The used circumferential vibration modes are trigonometric functions, the axial modes are the beam modal functions chosen to satisfy the prescribed boundary conditions. To check the validity, the theoretical results are compared with experimental, FEM and other theoretical results.

  • PDF

Theoretical and Experimental Analysis of Back-Gated SOI MOSFETs and Back-Floating NVRAMs

  • Avci, Uygar;Kumar, Arvind;Tiwari, Sandip
    • JSTS:Journal of Semiconductor Technology and Science
    • /
    • 제4권1호
    • /
    • pp.18-26
    • /
    • 2004
  • Back-gated silicon-on-insulator MOSFET -a threshold-voltage adjustable device-employs a constant back-gate potential to terminate source-drain electric fields and to provide carrier confinement in the channel. This suppresses shortchannel effects of nano-scale and of high drain biases, while allowing a means to threshold voltage control. We report here a theoretical analysis of this geometry to identify its natural length scales, and correlate the theoretical results with experimental device measurements. We also analyze experimental electrical characteristics for misaligned back-gate geometries to evaluate the influence on transport behavior from the device electrostatics due to the structure and position of the back-gate. The backgate structure also operates as a floating-gate nonvolatile memory (NVRAM) when the back-gate is floating. We summarize experimental and theoretical results that show the nano-scale scaling advantages of this structure over the traditional front floating-gate NVRAM.

외팔보형 IPMC 구동기의 이론적 모델링과 구동특성 (Theoretical Modeling and Dynamic Characteristics of a Cantilever IPMC Actuator)

  • 한대웅;이승엽
    • 대한기계학회:학술대회논문집
    • /
    • 대한기계학회 2008년도 추계학술대회A
    • /
    • pp.1521-1526
    • /
    • 2008
  • IPMC(Ionic Polymer-Metal Comosite) exhibits large deformation, having great attention in many application fields. It generates bending moment by ion exchange polymer film. It can be quickly bended by the applied voltage across the plated electrode of the polymer film. In the present paper, we derive the theoretical modeling and dynamic analysis of bending motions of IPMC actuators using the Euler-Bernoulli beam theory. The theoretical model of a cantilever IPMC actuator estimates the moment produced by the applied voltage. The dynamic characteristics, including natural frequencies and frequency response, are calculated by the theoretical model, and they are compared with the experimental results and finite element analysis. It is shown that the mathematical modeling allows precise estimation to the voltage-driven motion of the cantilever IPMC in air.

  • PDF

The Impact of Acquisition Announcements on Acquiring Firms' Alliance Partners : A Research Review and Compositive Research Model for Retail Industry

  • Koo, Ja-Seung
    • 유통과학연구
    • /
    • 제12권5호
    • /
    • pp.15-26
    • /
    • 2014
  • Purpose - This study addresses an acquisition's impact on a firm's strategic relationship based on findings of existing academic studies and theoretical assertions. Through examining existing research results and theoretical grounds for an acquisition's impact on various stakeholders, this study indirectly approaches the impact on stakeholders including alliance partners. Research design, data, and methodology - This research identified a variety of related theoretical foundations and empirical studies. Research objectives of prior studies mainly focused on merging firms and direct participants of acquisition activity. In addition, academic attention on the impact on rival firms has recently been growing. However, little research on alliance partners was found. Prior studies simultaneously employed event study methodology and cross-sectional analysis to make further theoretical contributions. Results and Conclusions - Based on the findings of prior studies, this research proposed a complementary research model for future academic inquiry into the impact of an acquisition on an alliance partner's return and for predicting an acquisition announcement's effect on alliance partners.

배기 소음기 구조가 삽입손실에 미치는 영향 (The Effect of Insertion Loss on the Element of Exhaust Muffler)

  • 강동림;김영호;전현부기;김의간
    • Journal of Advanced Marine Engineering and Technology
    • /
    • 제24권5호
    • /
    • pp.42-51
    • /
    • 2000
  • The performances of the simple expansion, perforated tube, and conical-connector type as an exhaust muffler are shown in this study. Applying a model in which the method of four-pole parameter is used makes theoretical estimation of the insertion loss. Experiment is performed for the measurement of the insertion loss under four cases according to the variation of the tail pipe length. By comparing the theoretical prediction with the experimental results, the validity of the modeling using the method of four-pole parameter is verified. The personal computer simulation programs for the above mentioned theory on the muffler design have been developed and exhaust sound level measurements have been carried out for simple expansion muffler, conical-connector muffler, perforated tube mufflers and the combined type of conical-connector and simple expansion muffler. The measured results for attenuation characteristics of noise for each muffler are compared with the computed theoretical results to verity the confidence and applicable limits of the theoretical equation derived.

  • PDF