• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.06a
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• pp.815-817
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• 2022

포인트 클라우드는 다수의 포인트로 구성된 3차원 미디어 콘텐츠로, 기존의 2차원 미디어에 비해 방대한 크기를 가진다. 이러한 포인트 클라우드 데이터를 효과적으로 소비하기 위해서는 포인트 클라우드 데이터를 압축하는 것이 필수적으로 요구된다. 이에 따라, 국제 표준화 기구 The Moving Picture Experts Group (MPEG)에서는 2차원 비디오 코덱 기반의 포인트 클라우드 압축 방안인 V-PCC 압축 방안과, V-PCC 비트스트림을 저장하고 전송하기 위한 ISOBMFF 캡슐화 방안에 대한 표준화가 진행되고 있다. V-PCC는 기존의 2차원 비디오 코덱을 이용하기 위해 3차원 포인트 클라우드 데이터를 투영하여 2차원 패치를 생성하고, 생성된 패치를 2차원 그리드에 배치하여 2차원 이미지를 생성한다. 이 때, 생성되는 2차원 이미지는 패치의 모양 차이와 인코딩의 효율성 때문에 Group of Picture(GOP)마다 다른 크기를 갖는다. 이러한 이미지 크기의 차이는 반복적인 디코더 초기화를 유발하여 송신기와 수신기 모두에 큰 부담을 발생시킨다. 이에 본 논문에서는 비트레이트와 메타데이터를 적응적으로 제어하여 V-PCC 비트스트림을 반복적인 디코더 초기화 없이 안정적으로 송수신 하기 위한 Global grid 기반 V-PCC 전송 방안을 제안한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.10
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• pp.745-752
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• 2020

A numerical study was carried out to evaluate the aerodynamic characteristics of the supersonic grid fins installed on SpaceX Falcon 9. The unit-grid-fin concept was utilized for more efficient and simpler 3-D steady flow calculations. Pre- and post-correction processes that accounted the interference effects by the angle of attack of the missile, the influences of the outer frame of the grid fin and the connecting rods were improved in the study, and it was demonstrated that the present correction method was more accurate as compared to previous studies. Finally, the present approach was applied to evaluate the aerodynamic characteristics in transonic/supersonic flights of SpaceX Falcon 9 with various angle of attacks.

• Journal of the Korean Geotechnical Society
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• v.25 no.11
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• pp.75-86
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• 2009

This paper presents the results of a numerical investigation on load carrying capacity of geogrid-encased stone columns to use as load carrying column(s) supporting a foundation load. A validated 3D stress-pore pressure coupled model that can effectively show rapid drainage capability of stone columns and encasement effect of geogrid was adopted and a parametric study was carried out on a number of influencing factors. It is shown that the geogrid encased stone columns can be effectively used as foundation load supporting columns in soft ground. The results of numerical investigation were presented so that the relationship between the load carrying capacity of geogrid-encased stone columns and the influencing factors can be identified. Practical implications of the findings are also discussed.

• Information and Communications Magazine
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• v.31 no.6
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• pp.64-68
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• 2014

본고에서는 수자원관리의 새로운 패러다임인 스마트워터그리드에 대한 간략한 소개와 연구단에서 개발되는 기술의 확산을 위한 추진 전략을 알아본다. 스마트워터그리드 연구단은 51개의 참여기업과 303명의 참여 연구원이 크게 3개의 세부로 나뉘어 연구를 진행한다. 1세부는 신도시 수자원 연계활용을 위한 지능형 수자원 확보 기술 개발을, 2세부는 수자원 최적 활용을 위한 지능형 유역물관리 플랫폼 개발을, 3세부에서는 Smart Water Grid 맞춤형 ICT기반물정보 관리 기술 개발을 목표로 하고 있다. 이렇게 개발되는 기술의 확산을 위해 크게 5가지의 전략을 펼치고 있다. 기술실증화 전략인 Pilot-Plant와 Demo-Plant 설계 및 운영, 표준분류체계, 국제표준화 ITU-T FG-SWM, 제7차 세계물포럼, 국제기술협력을 위한 국제컨퍼런스 개최가 연구단의 전략이다. 특히, 스마트워터그리드라는 새로운 패러다임을 국제적인 이슈로 상정하기 위하여 국제표준화 기구인 UN-ITU에 SWM(Smart Water Management) 주제로 FG(Focus Group)을 신설하였다. ITU-T는 전기 통신 분야의 국제기구로서 신기술이 개발될 때부터 기술표준화를 제시하고, 제품의 수출입에 영향력을 미치기에 많은 전기전자통신 업계의 주요 관심분야이기도 하다. SWG연구단에서도 SWM차원에서 SWG기술이 향후 세계시장에서 선진기술들과 비교경쟁력을 갖출 수 있도록 국제표준화를 위한 노력을 기울이고 있다. 또한, 2015년에 개최될 세계 제 7차 물포럼에서 SWG기술을 시연하고, 홍보하는 활동을 통해 대한민국의 우수한 IT기술이 물산업의 중심에서 돋보일 것이라 전망된다.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.4
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• pp.41-50
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• 1994

An iterative time marching procedure for solving incompressible viscous flows has been applied to the flow around a propeller. This procedure solves three-dimensional Navier-Stokes equations on a moving, body-fitted, non-orthogonal grid using first-order accurate scheme for the time deivatives and second-and third-order accurate schemes for the spatial derivatives. To accelerate iterative process, a multigrid technique has been applied. This procedure is suitable for efficient execution on the current generation of vector or massively parallel computer architectures. Generally good agreement with published experimental and numerical data has been obtained. It was also found that the multigrid technique was efficient in reducing the CPU time needed for the simulation and improved the solution quality.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.10 s.175
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• pp.31-38
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• 2005

• Journal of the Korean Geosynthetics Society
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• v.5 no.1
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• pp.15-23
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• 2006

Sand Compaction Pile and Stone Column method have been used in widely during several decades as a technique to reinforce soft soils and increasing ultimate bearing capacity, accelerate consolidation settlement of the foundation ground. Stone column method, making a compaction pile using crushed stone, is a soft ground improvement method. However, stone column method is difficult to apply to the ground which is not mobilized enough lateral confine pressure because no bulging failure resistance. Hence, in present study, development the geogrid reinforced stone column system for settlement reduction and wide range of application of stone columns. To develop this system, triaxial compression tests were conducted for evaluation which is about behavior characteristics of stone column on replacement rate and confine pressure. Then, 3-dimensional numerical analysis were evaluated for application of the GRSC (geogrid reinforced stone column) system as evaluate behavior characteristics and settlement reduction effect of stone column reinforced by geogrid on types and reinforcing depth change of geogrid.

• Journal of the Korean Geosynthetics Society
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• v.6 no.1
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• pp.17-25
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• 2007

This study presents a modeling approach for geogrid-encased stone column(GESC) method which is widely used in Europe as an alternative to conventional pile foundations. Several benefits of using the stone column method include sound performance, low cost, expediency of construction, and liquefaction resistance, among others. Recently, geosynthetic-encased stone column approach has been developed to improve load carrying capacity through increasing confinement effect. The aim of this research is to establish a systematic approach for modeling of GESC and to form a database for the fundamentals of GESC. This paper presents details of 3D modeling of GESC together with the general behavior of GESC.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.9B
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• pp.1416-1427
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• 2010

Except for some fields, Smart Grid-related technology in Korea is considered to be below the level of developed countries. Under this situation, this study is conducted to look into IT technology related to Smart Grid and draw prospective IT R&D fields in the Smart Grid Industry. To seek out prospective IT R&D fields, the two-stage process evaluating economics, political property, and technical validity. According to the result, four fields of (1) sensor, (2) information protection, (3) AMI middleware, (4) electricity management are selected as prospective fields. The sensor and AMI middleware fields focus on development of key technology, so the strategy that launches leading products in global market faster than other countries(Focusing & First Mover Strategy). The information protection felid is divided into the safety technology for the felid electricity network and the personal & corporate information protection technology, and therefore the R&D Sharing strategy is efficient. For the electricity management filed, a strategic alliance for developing component technology of Grid is desirable.

• Journal of the Korean Geotechnical Society
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• v.24 no.12
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• pp.93-101
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• 2008

This paper presents the results of numerical investigation on support mechanism of geogrid-encased stone columns for use in soft ground improvement. A number of cases were analyzed using a 3D stress-pore pressure coupled model that can effectively model construction sequence and drainage as well as reinforcing effects of geogrid-encased stone columns. The results indicated that the geogrid encasement provides additional confinement effect that reduces vertical stress in the soft ground, thus resulting in less excess pore water pressures and associated settlement. Also revealed was that such a confinement effect depends on encasement length and stiffness of geogrid. It is also shown that there exist critical encasement length and stiffness of geogrid for a given condition.