• 한국IT서비스학회:학술대회논문집
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• 2006.05a
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• pp.249-254
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• 2006

소프트웨어 스트리밍[1][2]은 프로그램 설치 및 실행을 위하여 서버로부터 데이터 전송이 진행중인 동안에도 PC, PDA, 휴대용 개인 컴퓨터, 휴대 전화 등과 같은 데스크 탑 또는 이동 연산장치 상에서 미설치 소프트웨어의 실행이 즉각적으로 이루어지도록 하는 기능이다. 즉, 소프트웨어 스트리밍 기술을 사용하면 사용자가 다운로드, 압축해제, 인스톨과 시스템 재구성이라는 일련의 과정이 완료될 때까지 기다릴 필요 없이 최소한의 다운로드 후에 해당 소프트웨어가 곧바로 실행될 수 있도록 해준다. 이러한 스트리밍 시스템을 사용하면 사용자는 다양한 공개 또는 상업용 응용프로그램을 광범위하게 지원하는 사용자 투명성을 가진 가상 소프트웨어 컴퓨팅 환경을 만들 수 있다. 본 논문에서는 리눅스 환경에서 설계 구현된 Software On-Demand(SOD) 스트리밍 시스템을 소개하고, SOD 스트리밍 시스템의 성능평가 소프트웨어를 사용하여 SOD 스트리밍 시스템의 성능을 측정한다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04b
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• pp.499-501
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• 2004

교육의 새로운 방향은 가상 학교나 WBI와 같은 교육적 활용분야로 확대되고 있으나, e-Learning 상에서 이뤄지는 평가의 응시자에 대한 신뢰 확보는 어려운 상황이다. 기존의 인증이란 사용자가 E와 Password를 타인에게 공개하지 않는 한 본인임을 인증하였다. 하지만 온라인상에서 시험 응시자는 본인의 ID와 Password를 타인에게 알려주어 대리시험이 가능하게 함은 물론 시험문제의 공유 또는 다수의 응시자가 한 곳에 모여 문제를 풀어 감으로서 평가에 대한 신뢰도에 의문을 갖지 않을 수 없게 되었다. 이에 인터넷으로 원격조정이 가능한 PC카메라와 얼굴인식 프로그램 그리고 원격제어프로그램을 이용하여 응시자를 인증함으로써 부정행위를 원천적으로 봉쇄하고, 감독자가 언제 어디서나 웹을 통하여 쉽게 감독할 수 있도록 LMS 기능의 보완이 요구된다. 본 논문을 통해서는 채팅기능을 통한 상호 대화가 가능하고 응시 장면을 동영상으로 압축 저장하여 사후 감독이 가능토록 함으로서 e-Learning상에서의 평가 및 학사관리의 공정성 및 신뢰도를 높일 수 있는 방안을 제시하였다.

• Journal of the Korean Institute of Gas
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• v.22 no.5
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• pp.24-30
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• 2018

In the case of arctic area long-distance natural gas transmission pipeline, it is necessary to construct capable facilities to maintain the gas pressure because the gas pressure is reduced according to the pipeline characteristics and route conditions. In order to maintain the proper NG pressure, it is necessary to secure economy considering the cost of main equipments of the compressor station, construction and operation cost when the compression ratio is shortened or increased by constructing the distance of the compressor station. Therefore, In this study, preliminary study on construction of arctic area long-distance transmission pipeline was reviewed and conduct conceptual design by constructing main equipments process that can reduce the construction cost of the compressor station in arctic area. In particular, in order to evaluate economic feasibility of the long-distance transmission pipeline in arctic area, the virtual area for Yakutsk~Aldan region(Russia) was supposed. The total pipeline length of the virtual is 533km, The scenarios for the location of the compressor station presented. The capacity estimated about the main equipments of the compressor station. As a result, the economic evaluation method reviewed which can minimize the construction cost of the compressor station.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.06a
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• pp.253-256
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• 2022

실사 영상 기반의 메타버스 환경을 구축하기 위한 다수의 카메라를 통한 영상 취득 및 부호화, 전송 기술이 활발히 연구되고 있고, 이를 위해 영상 압축 표준화 단체인 moving picture experts group (MPEG) 에서는 MPEG immersive video (MIV) 표준을 개발하였다. 하지만, 현재 널리 사용되는 가상 현실 영상을 스트리밍 가능한 장비의 연산 능력으로는 MIV 기반 몰입형 영상을 스트리밍 시 복호기 동기화 문제가 발생할 수 있다. 따라서 본 논문은 저사양 및 고사양 장비에서 적응적으로 복호기 개수를 조절 가능한 geometry packing 기법을 MIV 의 참조 소프트웨어인 test model for immersive video (TMIV)에서 구현한다. 제안하는 패킹 기법은 지오메트리 영상을 패킹하여 텍스쳐 영상과 같은 높이를 가지도록 한 후 각각 단일 서브픽쳐 (subpicture) 로 부호화한다. 이후 부호화된 서브픽쳐들에 적응적으로 비트스트림 병합이 적용되어 장비의 복호기 사양에 대응한다.

• Journal of Korean Society for Geospatial Information Science
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• v.19 no.2
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• pp.3-8
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• 2011

Recently, the demand for enterprise for service map providing and portal site services of a 3D virtual city model for public users has been expanding. Also, accuracy of the data, transfer rate and the update for the update for the lapse of time emerge are considered as more impertant factors, by providing 3D information with the web or mobile devices. With the latest technology, we have seen various 3D data through the web. With the VRML progressing actively, because it can provide a virtual display of the world and all aspects of interaction with web. It offers installation of simple plug-in without extra cost on the web. LiDAR system can obtain spatial data easily and accurately, as supprted by numerous researches and applications. However, in general, LiDAR data is obtained in the form of an irregular point cloud. So, in case of using data without converting, high processor is needed for presenting 2D forms from point data composed of 3D data and the data increase. This study expresses urban LiDAR data in 3D, 2D raster data that was applied by compressing algorithm that was used for solving the problems of large storage space and processing. For expressing 3D, algorithm that converts compressed LiDAR data into code Suited to VRML was made. Finally, urban area was expressed in 3D with expressing ground and feature separately.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.1
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• pp.95-104
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• 2003

This paper deals with the analytic and FEM analyses of sloshing frequency response of incompressible, invicid and irrotational flow in two dimensional rectangular tank. We use Laplace equation based on potential theory as governing equation. For small amplitude sloshing motion, the linearized free surface condition was applied and the analytic solution as obtained by the separation of variables. To simulate the effect of the energy dissipation due to viscous damping, artificial viscous coefficient is introduced and the divergence of response at resonance frequencies may be avoided by this coefficient. This problem was solved by FEM using 9-node elements in order to predict the maximum amplitude of sloshing response. Numerical results of free surface height, fluid pressure and fluid force show good agreement with those by analytic solution. After verifying the test FEM program, we analyze the frequency response characteristics of sloshing to the fluid height.

• Journal of Korean Society of Steel Construction
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• v.29 no.1
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• pp.13-24
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• 2017

System buckling analysis is usually used to determine the critical buckling load in the buckling design of cable-stayed bridges. However, system buckling analysis may yield unexpectedly large effective lengths of the members subjected to a relatively small axial force. This paper proposes a new method to determine reasonable effective lengths of girder and tower members in steel cable-stayed bridges using fictitious axial forces. An improved inelastic buckling analysis with modified tangent modulus is also presented. The effective lengths of members in example bridges calculated using the proposed method are compared with those obtained using the conventional buckling analysis method. The proposed method provides much more resonable effective lengths of the members. When girder and tower members are built with HSB800 steel instead of conventional steel, the effective lengths of the members under a small axial force slightly decreases in the inelastic buckling analysis without fictitious axial forces, while the proposed method that considers fictitious axial forces provides almost no changes in such lengths.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.1
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• pp.27-33
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• 2009

Shock tube flow measurement has been often hampered a finite opening time of diaphragm, but there is no systematic work to investigate its effect on the shock tube flow. In the present study, both the experimental and computational works have been performed on the shock tube flows at low pressure ratios. The computational analysis has been performed using the two-dimensional, unsteady, compressible Navier-Stokes equations, based upon a TVD MUSCL finite difference scheme. It is known that the present computational results reproduce the experimental data with good accuracy and simulate successfully the process of diaphragm opening as a function of time. The concept of an imaginary center is introduced to quantify the non-centered expansion wave due to a finite opening time of diaphragm. The results obtained show that the diaphragm opening time is reduced as the initial pressure ratio of shock tube increases, leading to the effect of a finite opening time of diaphragm to be more remarkable at low pressure ratios.

• Journal of the Korea Institute of Building Construction
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• v.19 no.1
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• pp.39-46
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• 2019

A three-dimensional flow simulation model for high flow concrete was developed using Incompressible Smoothed Particle Hydrodynamics (ISPH), which can solved Navier-Stokes equation with the assumption of a fluid to be incompressible. For the simulation, a computer program code for ISPH was implemented with MATALB programming code. A piecewise cubic spline function was used for the kernel function of ISPH. Projetion method was used to calculate the velocity and pressure of particles as a function of time. Fixed ghost particle was used for wall boundary condition. Free surface boundaries were determined by using virtual density of particles. In order to validate the model and the code, the simulation results of slump flow test, $T_{500}$ test and L-box test were compared with experimental ones. The simulation results were well matched with the experimental results. The simulation described successfully the characteristics of the flow phenomenon according to the change of the viscosity and yield stress of high flow concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.1
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• pp.183-192
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• 2008

Generally, application of steel pipe pile as deep foundation member needs special requirement for the connection method between steel pipe pile and concrete footing. Even though two types of connection method are suggested in the korea highway bridge code, type-B method is prevalent. In this study, vertical, lateral, and tension loading test are done for two types of type B connection to review stress concentration, formation and behavior of imaginary RC column in the footing. Welding type and hook type as the connection method are considered in this study. Test results show that welding type have the more reserve capacity than hook type and the specimens connected by the welding type behave as the imaginary RC column in the footing. However, the specimens connected by the hook type did not behave as the imaginary RC column in the footing but behave as the hinge.