• Proceedings of the Membrane Society of Korea Conference
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• 1999.10b
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• pp.85-88
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• 1999

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.309-314
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• 2012

Flame flickering occurs mainly because of the buoyancy force for pool fires under ambient air. The cup-burner flame was used for experimental investigation of the effect of the oxidizer velocity on the gravitational instability. The results showed that the flickering frequency decreased with increasing oxidizer velocity. The frequency-buoyancy relation with nondimensional variables coincided with that of the buoyant flume and pool fires when the characteristic velocity was defined as the difference between the fuel and oxidizer velocities, which implies that the origin of the gravitational instability is the Kelvin-Helmholtz instability in the shear layer. The effect of the oxidizer composition on the instability was also examined through nitrogen dilution in the oxidizer stream. As the concentration of inert gas increased, the length of the blue flame increased and lift-off behavior was observed. The oscillation frequency was independent of the dilution ratio, but was related to the local flame structure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3C
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• pp.286-292
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• 2006

Both composition and XOR are operations widely used to enhance security of cryptographic schemes. The more number of random permutations we compose (resp. XOR), the more secure random permutation (resp. random function) we get. Combining the two methods, we consider a generalized form of random function: $SUM^s - CMP^c = ({\pi}_{sc} ... {\pi}_{(s-1)c+1}){\oplus}...{\oplus}({\pi}_c...{\pi}_1)$ where ${\pi}_1...{\pi}_{sc}$ are random permutations. Given a fixed number of random permutations, there seems to be a trade-off between composition and XOR for security of $SUM^s - CMP^c$. We analyze this trade-off based on some upper bound of insecurity of $SUM^s - CMP^c$, and investigate what the optimal number of each operation is, in order to lower the upper bound.

• Journal of Trauma and Injury
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• v.27 no.1
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• pp.1-4
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• 2014

Occipito-atlanto-axial subluxation is a type of high cervical injury. Misdiagnosis of this instability might cause several complications, including neurologic deficits. A radiologic evaluation must be performed and specific parameters that imply cervical instability must be confirmed. Full understanding of these parameters may prevent not only delayed diagnosis but also unexpected complication. We report a case of delayed detection of a cervical instability and emphasize the role of proper diagnosis.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.96-97
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• 2000

최근 기능성 생리활성물질로서 각광을 받고있는 chitooligosaccharide의 제조방법은 염산, 황산 등을 이용한 화학적 분해법과 효소를 이용하는 생물학적 방법을 들 수 있다. 화학적 분해법은 비용을 적게들여 쉽게 저분자 올리고당을 만들 수 있으나, 올리고당의 수율이 낮고 저중합도의 올리고당이 많이 생성되며, 원료의 불안전성으로 인해 인체에 유해한 부반응 물질을 생성시키는 문제점이 보고되고 있다(Choi. et al.,1997). (중략)

• Information and Communications Magazine
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• v.17 no.10
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• pp.24-35
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• 2000

최근 빠른 속도로 확산된 인터넷 사용은 전자상거래와 인터넷 사업의 필수 인프라인 정보보호에 관한 관심을 고조시키고 있다. 전자상거래를 이용함에 있어 불안전성은 구조적인 문제, 발달된 해킹기술, 보안에 관한 사용자 인식 부종 등 여러 가지가 문제에 기인한다. 본 논문에서는 전자상거래에서 발생할 수 있는 위협 및 취약 요소들과 그에 따른 보안 요구사항을 살펴보고 이에 대한 솔루션으로서 연구, 개발되고 있는 정보보호 기술을 소개하고자 한다. 그리고 각 솔루션들에 남아있는 과제들을 정리해 봄으로써 전자상거래를 위한 정보보호 기술이 앞으로 나아갈 방향을 제시해 보고자 한다.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.23-24
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• 2016

본 논문은 모듈러 멀티레벨 컨버터(MMC)에서 인버터로 사용할 경우 스위칭이 시작할 때, 과도상태에서 발생하는 돌입전류로 인해 시스템 제어의 불안전성을 야기한다. 따라서 이 전류를 저감하기 위해 제안한 등가회로 모델링, 제어를 MATLAB 시뮬레이션을 통하여 돌입전류에 대한 논의와 크기 저감을 확인하고자 한다.

• Journal of Korean Orthopaedic Sports Medicine
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• v.6 no.1
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• pp.13-18
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• 2007

Lateral ankle instability is one of common injury in sports medicine. Already many studies were done with scientific data and clinical relationship. This review article wants to discuss about controversial subject of ankle instability. It will be conducted more precise diagnosis and treatment.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.5
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• pp.613-620
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• 1985

An analysis on the thermal instability of horizontal Blasius flow in the form of longitudinal vortices has been carried out by introducing the 3-dimensional spatial dependence of the disturbance quantities. The stability problem has been simplified significantly by considering the limiting case of infinite Prandtl number and by skilfully replacing the boundary conditions at infinity with the interface conditions at the edge of the thermal boundary layer (or by simply confining the thermal disturbances in the thermal boundary layer). The advantage of this approach is that the critical values marking the onset of thermal instability can be readily obtained as solutions of the eigenvalues problems formulated by a 6*6(or a 5*5) determinant. Present analysis provides reasonable explanations on the existing experimental and theoretical data. Especially, the heat transfer correlation based on the present analysis agrees well with the existing experimental data.

• Journal of the Korean Arthroscopy Society
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• v.7 no.2
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• pp.127-136
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• 2003

Posterolateral instability of the knee occurs more commonly in association with an injury to anterior and posterior cruciate ligament and combined injuries are severe injuries that result in significant functional instability and articular cartilage degeneration. Reconstruction of the anterior and posterior cruciate ligament without an appropriate treatment of posterolateral corner injury result in failure of the reconstructed cruciate ligaments. Meticulous physical examinations, imaging studies, lower limb alignment and gait pattern should be evaluated. Acute grade III isolated or combined injury of the posterolateral corner is best treated within three weeks by direct repair, or augumentation, or reconstruction. The appropriate surgical method or combined methods are selected among the several methods of posterior and posterolateal reconstruction, and all injuried posterolateral and cruciate ligament structures are anatomically reconstructed simultaneously or by stages. If a varus alignment and varus thrust is disclosed in chronic posterolateral instability of knee, soft tissue reconstructions laterally are highly unlikely to be able to correct tile problem. It is appropriate that valgus osteotomy should be done before soft tissue reconstruction and reevaluate the posterolateral instability about 6 months later.