• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.242-245
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• 2005

The rotating flow in the space between co-rotating disks is of considerable importance in information storage systems. Hard disk drivers(HDD) in computer are used extensively as data storage capacity. The trend in the computer industry to produce smaller disk drives rotating at higher speed requires an improved understanding of fluid motion in the space between disks. In this study, we have tried LES model for inner-disk flowfield to investigate the flow disturbance and the flow structure driven by co-rotating disks. The boundary pattern between inner region and outer region obtained lobe-shape structure clearly and its number has been validated on experimental data by our previous study. We obtain the spectra of velocity and pressure components with several frequencies. We revealed there are two kinds of disturbances, one is global wave propagation and another is local wave propagation on Ekman boundary layer.

• Journal of the Korean Graphic Arts Communication Society
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• v.30 no.2
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• pp.23-33
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• 2012

With the development of many display technologies currently applied to them in the field of printed electronics, there have been many researches that high resolution printing for thin and uniform pattern. In this paper, printing ink flow properties in the reverse offset mechanism were simulated. The aim of this research is to expect the ink flow behavior between cliches to make fine pattern by a printing technique which is a reverse offset. The simulation results show that almost the same as the experiments and the flow behavior according to the ink film thickness and printing pressure changes could be expected.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.538-543
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• 2000

DS(Differentiated Service)에서는 RSVP와 같이 개별 flow에 대한 QoS제공이 아닌 flow들의 집합(aggregate)으로 차등적인 서비스를 제공하는 방법이다. 확장성을 고려한 이러한 방안은 광역백본망 에서와 같이 수천, 수만의 flow들에 대해 서비스를 제공하고자 할때 flow들을 집합(aggregate)화 하여 차등적인 서비스를 제공하고자 하는 것은 매우 큰 의미가 있다고 할 수 있다. 하지만 DS에서는 Token Bucket 방법을 사용하여 트래픽 스트림을 측정하는 이유로 불특정 flow에 대해 심각한 QoS손실을 야기할 수 있다. 본 논문에서는 자원공유의 공정성을 기여하기 위해 Traffic Conditioner에서 사전 모니터링 방법을 사용하고 이 모니터링 결과를 Weighted Fair Queuing의 파라메터로 사용하여 잉여 자원을 효율적으로 사용하는 방안을 제시한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.04a
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• pp.143-146
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• 2015

Software Defined Network (SDN) separates control plane and data plane to achieve benefits such as centralized management, centralized provisioning, lower device cost and more flexibility. In SDN, scalability is an important issue. Centralized controller can be a bottle neck and many research tried to solve this issue on the control plan. However, scalability issue does not only happen in the control plane, but also happen in the data plane. In the data plane, flow table is an important component and its size is limited. In a large network operated by SDN technology, the performance of the network can be highly degraded because of the size limitation of a flow table. In this paper, we propose a ranking-based flow replacement method, Flow Table Management (FTM), to overcome this problem.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.510-513
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• 2012

본 논문은 하드웨어에 독립적이고 패킷 처리 프로그래밍 개발의 효율성을 높이기 위하여 eFlowC 언어와 eFlowC 컴파일러를 제안한다. eFlowC 언어는 C 언어 기반의 고급언어이다. 그리고 기존의 C 문법에 패킷 처리 관련 기능을 위한 새로운 라이브러리를 추가하였다. eFlowC 컴파일러는 eFlowC 언어로 작성된 프로그램을 입력으로 받는다. 그리고 결과물로 가상 기계 목적 코드를 생성한다. 가상 기계 목적 코드는 언어 번역기의 입력 파일로 언어 번역기를 통하여 다양한 하드웨어 기계어로 번역이 가능하다.

• Journal of Mechanical Science and Technology
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• v.20 no.1
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• pp.125-132
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• 2006

To understand fluid dynamic forces acting on a structure subjected to two-phase flow, it is essential to get detailed information about the characteristics of two-phase flow. Stratified steady and unsteady two-phase flows between two parallel plates have been studied to investigate the general characteristics of the flow related to flow-induced vibration. Based on the spectral collocation method, a numerical approach has been developed for the unsteady two-phase flow. The method is validated by comparing numerical result to analytical one given for a simple harmonic two-phase flow. The flow parameters for the steady two-phase flow, such as void fraction and two-phase frictional multiplier, are evaluated. The dynamic characteristics of the unsteady two-phase flow, including the void fraction effect on the complex unsteady pressure, are illustrated.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.6
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• pp.417-426
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• 2019

Conventional visualization of PM (Particulate Matter)10 flows applies superimposition of concentration distribution maps and wind field maps. This method is efficient for small scale maps where only macro flow trends are of interest. However, in the case of urban areas, local flows are difficult to model at micro level using wind fields, and therefore different methods of flow extraction is deemed necessary. In this study, flow information is extracted and visualized directly from the PM10 density data by using the gravity model. This method has the advantage that additional information such as wind field is not necessary for estimating the intensity and direction of PM10 flow. The extracted spatio-temporal flow patterns of PM10 are analyzed with relation to traffic information.

• Journal of the Korea Society of Computer and Information
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• v.16 no.6
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• pp.41-50
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• 2011

Code obfuscation has been proposed to protect codes in a program from malicious software reverse engineering. It converts a program into an equivalent one that is more difficult to understand the program. Code obfuscation has been classified into various obfuscation technique such as layout, data, control, by obfuscating goals. In those obfuscation techniques, control obfuscation is intended to complicate the control flow in a program to protect abstract information of control flow. For protecting control flow in a program, various control obfuscation transformation techniques have been proposed. However, strategies for effectively applying a control flow obfuscation to program have not been proposed yet. In this paper, we proposed a obfuscation strategy that effectively applies a control flow obfuscation transformation to a program. We conducted experiment to show that the proposed obfuscation strategy is useful for applying a control flow transformation to a program.

• Wind and Structures
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• v.28 no.5
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• pp.285-298
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• 2019

For super long-span bridges, the aerodynamic forces induced by the flow passing the box girder should be considered carefully. And the Reynolds number sensitively of aerodynamic characteristics is one of considerable issue. In the study, a numerical study on the Reynolds number sensitivity of aerodynamic characteristic (flow pattern, pressure distribution and aerodynamic forces) of a twin-box girder were carried out using large eddy simulation (LES) with the dynamic Smagorinsky-Lilly subgrid model. The results show that the aerodynamic characteristics have strong correlation with the Reynolds number. At the leading edge, the flow experiences attachment, departure, and reattachment stages accompanying by the laminar transition into turbulence, causing pressure plateaus to form on the surface, and the pressure plateaus gradually shrinks. Around the gap, attributing that the flow experiences stages of laminar cavity flow, the wake with alternate shedding vortices, and turbulent cavity flow in sequence with an increase in the Reynolds number, the pressures around the gap vary greatly with the Reynold number. At the trailing edge, the pressure gradually recovers as the flow transits to turbulence (the flow undergoes wake instability, shear layer transition-reattachment station), In addition, at relative high Reynolds numbers, the drag force almost does not change, however, the lift force coefficient gradually decreases with an increase in Reynolds number.

• Journal of the Korea Society of Computer and Information
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• v.28 no.7
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• pp.145-153
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• 2023

The aim of this study is to examine the relationship between self-regulated learning, NLR(non-learning-related) behavior, interaction and flow on satisfaction in database classes. To achieve this purpose, this study proposed a research model consisting of self-regulated learning, NLR behavior, interaction, flow and satisfaction. A survey was conducted to test the research hypotheses, and a total of 122 online questionnaires were obtained and used for the final statistical analysis. The main findings of the analysis are as follows: First, flow was consistently identified as a key determinant of satisfaction. Second, self-regulated learning was found to have a significant effect on flow. Third, NLR behavior and interaction were found to mediate the relationship between self-regulated learning and flow. This study provides insights into the role of NLR behavior and interaction in promoting flow and offers implications for understanding how to promote flow.