• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 추계학술발표회논문집(1)
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• pp.522-527
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• 1997

A total of 386 critical flow data points from 19 runs of 27 runs in the Marviken Test were selected and compared with the predictions by the correlations based on the critical flow scaling parameters. The results show that the critical mass flux in the very large diameter pipe can be also characterized by two scaling parameters such as discharge coefficient and dimensionless subcooling( $C_{d, ref}$ and $\Delta$ $T^{*}$$_{sub}$). The agreement between the measured data and the predictions are excellent.t.ons are excellent.t.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.903-906
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• 2005

The purpose of this paper is to investigate free vibrations and critical loads of the uniform Beck's columns with a tip spring, carrying a tip mass. The ordinary differential equation governing free vibrations of such Beck's column subjected to a follower force is derived based on the Bernoulli-Euler beam theory. Both the divergence and flutter critical loads are calculated from the load-frequency curves that are obtained by solving the differential equation numerically. The critical loads are presented in the figures as functions of various non-dimensional system parameters such as the mass moment of inertia and spring parameter.

• 한국콘텐츠학회논문지
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• 제14권4호
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• pp.355-367
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• 2014

본 연구는 온라인 게임의 기존 이용자 유지 및 신규 이용자 유치 방안을 제시하고자 온라인 게임 이용자들의 긍정적 구전에 미치는 요인과 그 구조에 대해 밝히는 것을 목적으로 한다. 기존 연구에서는 게임의 속성이나 이용자의 속성이 온라인 게임 이용의도에 미치는 영향에 주로 초점이 맞춰져 있었다. 하지만 네트워크 기반으로 이용자 간 커뮤니케이션을 동반하는 온라인 게임의 특성상 개별 소비자의 이용뿐만 아니라 확산을 통한 일정 수준의 소비자 확보가 온라인 게임 시장에서 성공의 핵심 요인이다. 즉, 게임 이용자가 증가할수록 게임 이용자가 얻게 되는 가치가 증가할 것이라는 네트워크 외부성을 고려해야 한다. 따라서 본 연구는 온라인 게임의 사회규범적 특성 및 크리티컬 매스의 특성이 온라인 게임에 대한 태도 및 구전의도에 미치는 영향을 규명하고자 하였다. 연구결과 사회규범적 특성과 크리티컬 매스의 특성은 온라인 게임에 대한 태도에 유의한 양(+)의 영향을 미치는 것으로 확인되었다. 또한 사회규범적 특성과 태도는 이용자의 구전의도에 유의한 양(+)의 영향력을 직접적으로 미치는 것으로 밝혀졌다. 이러한 결과는 이용자 확보를 위해 긍정적 구전 확산을 원하는 온라인 게임 기업들에게 사회규범 및 크리티컬 매스의 활용 방안에 대한 실무적 시사점을 제시한다.

• Tuberculosis and Respiratory Diseases
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• 제76권3호
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• pp.131-135
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• 2014

Low-grade endometrial stromal sarcoma (ESS) is an uncommon gynecologic malignancy of mesodermal origin. Pulmonary metastasis of low-grade ESS can occur years and decades after the treatment of the primary disease. Low-grade ESS is frequently mistaken as benign uterine neoplasm like uterine leiomyoma, which can potentially lead to a misdiagnosis. We present a case of a 42-year-old woman with low-grade ESS, that initially presented as an incidental lung mass with multiple pulmonary nodules, seven years after an uterine myomectomy. A $6.9{\times}5.8cm-sized$ intrapelvic mass suspected of uterine origin was discovered while searching for potential extrathoracic primary origin. A pelviscopy and simultaneous thoracoscopic lung biopsy were conducted for pathologic diagnosis. Finally, the diagnosis was confirmed as low-grade ESS with lung metastasis based on the histopathologic examination with immunohistochemical stain, which was showed positive for CD10 and hormone receptor markers (estrogen and progesterone receptors) in both pelvic and lung specimens.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.801-804
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• 2006

The purpose of this paper is to investigate the stability of stepped cantilever columns with a tip mass of rotatory inertia and a translational spring at one end. The column model is based on the Bernoulli-Euler theory which neglects the effects of rotatory inertia and shear deformation. The governing differential equation for the free vibration of columns with stepwise variable cross-section and subjected to a subtangential follower force is solved numerically using the corresponding boundary conditions. And the bisection method is used to calculate the critical divergence/flutter load. The frequency and critical divergence/flutter load for the stepped column with a single step are presented as functions of various non-dimensional system parameters: the segmental length parameter, the section ratio, the subtangential parameter, the mass, the moment of inertia of the mass, and the spring parameter.

• 한국경영과학회지
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• 제27권2호
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• pp.81-96
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• 2002

Telecommunication services are distinctive in that their adoptions are influenced by network effect resulting in 'the late take-off phenomenon' and the 'critical mass' problem. In this paper we examined, so called, 'the late take-off phenomenon' in the diffusion process of telecommunication services. We compared the parameters of the diffusion process of consumer durables with those of fax services in the US and Korea. By analyzing the parameters of a new diffusion model based on the threshold model proposed by Markus, we found that 'the late take-off phenomenon' resulted from the low heterogeneity of the threshold distribution for the potential adopters. A simulation approach was proposed for the theoretical implication of the 'critical mass' problem in the start-up telecommunications services.

• Nuclear Engineering and Technology
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• 제32권1호
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• pp.17-33
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• 2000

A mechanistic model based on wall-attached bubble coalescence, previously developed by the authors, was extended to predict a vow high critical heat flux (CHF）in highly subcooled flow boiling, especially for high mass flux and small tube diameter conditions. In order to take into account the enhanced condensation due to high subcooling and high mass velocity in small diameter tubes, a mechanistic approach was adopted to evaluate the non-equilibrium flow quality and void fraction in the subcooled water flow boiling, with preserving the structure of the previous CHF model. Comparison of the model predictions against highly subcooled water CHF data showed relatively good agreement over a wide range of parameters. The significance of the proposed CHF model lies in its generality in applying over the entire subcooled flow boiling regime including the operating conditions of fission and fusion reactors.

• Wind and Structures
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• 제5권5호
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• pp.407-422
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• 2002

Passive control of the flutter condition of suspension bridges using a combined vertical and torsional tuned mass damper (TMD) system is presented. The proposed TMD system has two degrees of freedom, which are tuned close to the frequencies corresponding to vertical and torsional symmetric modes of the bridge which get coupled during flutter. The bridge-TMD system is analyzed for finding critical wind speed for flutter using a finite element approach. Thomas Suspension Bridge is analyzed as an illustrative example. The effectiveness of the TMD system in increasing the critical flutter speed of the bridge is investigated through a parametric study. The results of the parametric study led to the optimization of some important parameters such as mass ratio, TMD damping ratio, tuning frequency, and number of TMD systems which provide maximum critical flutter wind speed of the suspension bridge.

• Tuberculosis and Respiratory Diseases
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• 제49권5호
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• pp.633-638
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• 2000

기관지 모균증은 드문 질환으로 돌출된 종괴로 발현된 경우는 특히 드물다. 저자들은 당뇨환자에서 종괴형태로 발현되어 우측 주기관지를 폐색시키는 기관지 모균증을 발견하였다. 경직성 기관지술로 모군 종괴를 제거하여 임상적으로 호전시킨 후 적극적으로 전신적 Amphotereicin B 투여와 폐절제술을 동반하여 완치한 1예를 경험하여 이를 보고하는 바이다.

• Tribology and Lubricants
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• 제18권6호
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• pp.377-383
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• 2002

The tribological role of mass transfer layer was studied with silver coatings under various ranges of load and sliding speed. Silver coating was performed with a functionally gradient coating method. Tests were per-formed in dry sliding conditions, using a ball-on-disk contact configuration, at the load of 0.0196-17.64 N and the sliding speed of 20-1,000 mm/s in ambient air. Optical microscope and EPMA analyses showed that contact surfaces were covered with the mass transfer layers of agglomerated wear particles depending upon the contact conditions, and they greatly influenced the tribological characteristics of the surfaces. However, the formation of mass transfer layer was suppressed as the sliding speed increased, and above a critical sliding speed, no mass transfer layer was able to form. For building up a general framework of triboiogical behavior of the coated silver films, all test data were summarized on a map whose axes are contact pressure and sliding speed.