• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.313-316
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• 2007

In the present study, the flow field in a square container with various corner rounding is studied to investigate drain flow characteristics. An attempt has been made to understand the mechanism that is responsible for vortex suppressing by the different radius of rounding at the corner. For this purpose, flow visualization studies using PIV (Particle Image Velocimetry) are employed to determine the flow patterns in a square tank. Results are obtained when there is no draining and with draining. The flow field is visualized both in horizontal and vertical planes.

• Journal of Ocean Engineering and Technology
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• v.20 no.2 s.69
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• pp.29-35
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• 2006

The flow patterns around multi-circular cylinders are studies, in order to obtain a global view on the structure of wave control and circulation of sea flow in coastal region. The flow force depends upon the vortex shedding exerted on the structure, especially how the vortex shedding affects the erosion when the structure sets on the sand bottom. Therefore, it is necessary that the flow pattern be hocked. In order to simulate the flow around multi-circular cylinders, the CFX and FLUENT of the computational fluid dynamics (CFD) program were used and compared with the experimental results of the flow visualization installation. The phenomena of flow around the multi-cylinders will be applied to fundamental data for predicting the flow force acting against the structure, erosion and sedimentation around cylinders in arrangement.

• The Transactions of the Korea Information Processing Society
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• v.5 no.12
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• pp.3165-3175
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• 1998

다양한 연구분야에서 웹을 대부분 응용의 프레임워크 또는 GUI 사용하려는 거역할 수 없는 흐름에 발 맞추어 국내에서도 전자상거래와 관련한 법규가 가시화될 전망으로 웹을 이용한 상거래 움직임 또한 더욱 활발할 것으로 보인다. 이와 같이 다양해지는 웹 응용을 위해서는 지금까지의 웹 보안 기술로 부인봉쇄와 같은 보안 서비스를 제공하지 못하고 있다. 본 논문에서는 최근 다양해지는 웹 보안 요구 사항을 만족시키는 프로토콜로 IETF에 의해 제안된 S-HTTP(Secure HTTP, Secure HyperText Transfer Protocol)를 기반으로 하는 웹 시스템인 SecWeb의 개발을 위한 시스템 모델, 구현 환경 및 개발된 시스템 그리고 적용 가능한 시나리오를 기술하였다. 개발된 SecWeb의 대표적인 응용분야로는 전자서명에 의한 부인봉쇄서비스가 중요하게 요구되는 분야들을 생각할 수 있다.

• Information and Communications Magazine
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• v.32 no.7
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• pp.3-8
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• 2015

인터넷의 폭발적인 팽창에 따른 부작용들을 근본적으로 해소하고자 2000년대 후반부터 시작된 미래인터넷(Future Internet)에 관한 연구들이 최근까지 지속적으로 진행 중이다. 또한 새롭게 대두된 융합형(convergent) ICT 자원구성에 맞춘 지속적인 사용자 주도의 인프라 혁신 전략에 기반하여, SDN/NFV/Cloud 통합으로 형성하는 소프트웨어-정의 인프라(Software-Defined Infrastructure: SDI)를 개방형으로 구축하는 흐름이 있다. 즉 구축/운용의 중심이 하드웨어에서 소프트웨어 중심으로 최근 급속하게 전환되는 큰 변화가 ICT 인프라차원에서 본격화하고 있다. 즉 지금까지 논의되었던 여러 미래 인터넷 이슈들을 스마트한 초연결과 사용자 중심 서비스의 관점에서 바라보면서 미래형 ICT 인프라의 바람직한 구축을 서서히 가시화하고 있다. 따라서 본 논문에서는 초연결에 기반하여 값싸고 신속하게 서비스를 실증하기 위해 DevOps(Developers & Operators: 개발/운영 병행체제) 방법론으로 소프트웨어-정의 인프라로 체질을 바꿔가는 개방형 혁신을 살펴본다.

• Fire Science and Engineering
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• v.12 no.3
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• pp.11-20
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• 1998

A new experimental technique using a laser sheet and thermocouples is introduced to evaluate an intuitive criterion for tracking of a smoke front using thermocouples. From synchronized photos of the smoke front along with temperature signals, the intuitive criterion is shown to be acceptable. Smoke visualization by a laser sheet proves to have several advantages over the conventional techniques such as the use of smoke generators.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06c
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• pp.320-322
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• 2012

코 내부의 복잡한 기하학적 형상으로 인해 nasal airway의 분리는 많은 어려움을 겪고 있다. 본 논문은 velocimetry of nasal airflow 와 코 수술 계획을 위하여 3차원 공간에서 nasal airway를 interactive semiautomatic으로 분리하고 시각화하는 방법을 제안한다. 제안하는 방법은 ROI(Region-Of-Interest)와 multi-seed 3d region growing(MS3RG)기법을 적용하여 비강을 분리하며 볼륨렌더링 기법을 이용하여 분리된 영역을 3차원 공간에서 직관적으로 확인 할 수 있다. 또한 분리된 3차원 비강 모델은 유동흐름 실험을 위하여 3차원 프린터를 통해 실제 모형으로 제작 가능하다. 그리하여 CT dataset(512*512*175)을 가지고 매뉴얼 세그멘테이션에서 5시간 정도 걸리던 작업을 반자동 세그멘테이션 방법을 이용할 경우 최대 3분 이내에 분리 작업을 완료할 수 있으며 수치해석 실험 및 물리 실험에 이용할 수 있다.

• Journal of KIISE:Software and Applications
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• v.36 no.11
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• pp.875-890
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• 2009

Metabolimics interprets an organism as a network of functional units and an organism is represented by a metabolic pathway i.e., well-displayed graph. So a software tool for drawing pathway is necessary to understand it comprehensively. These tools have a problem that edge-crossings exponentially increase as the number of nodes grows. To apply automatic graph layout techniques to the genome-scale metabolic flow, it is very important to reduce unnecessary edge-crossing on a metabolic pathway layout. In this paper, we design and implement 2.5D metabolic pathway layout modules. Metabolic pathways are represented hierarchically by making use of the '2-layered layout algorithm' in 3D. It enhances the readability and reduces unnecessary edge-crossings by using 3D layout modules instead of 2D layout algorithms.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.4
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• pp.351-357
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• 2013

In flip chip packaging, underfill process is used to fill epoxy bonder into the gap between a chip and a substrate in order to improve the reliability of electronic devices. Underfill process by capillary motion can give rise to unwanted air void formations since the arrangement of solder bumps affects the interfacial dynamics of flow meniscus. In this paper, the unsteady flows in the capillary underfill process are visualized and then the racing effect and merging of the meniscus are investigated according to the arrangement of solder bumps. The result is shown that at higher bump density, the fluid flow perpendicular to the main direction of flow becomes stronger so that more air voids are formed. This phenomenon is more conspicuous at a staggered bump array than at a rectangular bump array.

• Journal of the Korean Society of Visualization
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• v.14 no.1
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• pp.57-61
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• 2016

We report a finding of fast(exceeding 2,000 K/s) heating of polydimethylsiloxane(PDMS), one of the most commonly-used microchannel materials, under cyclic loadings at high(~MHz) frequencies. A microheater was created based on the finding. The heating mechanism utilized vibration damping of sound waves, which were generated and precisely manipulated using a conventional surface acoustic wave(SAW) microfluidic system, in PDMS. The penetration depths were measured to range from $210{\mu}m$ to $1290{\mu}m$, enough to cover most microchannel heights in microfluidic systems. The energy conversion efficiency was SAW frequency-dependent and measured to be the highest at around 30 MHz. Independent actuation of each interdigital transducer(IDT) enabled independent manipulation of SAWs, permitting spatiotemporal control of temperature on the microchip. All the advantages of this microheater facilitated a two-step continuous flow polymerase chain reaction(CFPCR) to achieve the billion-fold amplification of a 134 bp DNA amplicon in less than 3 min. In addition, a technique was developed for establishing dynamic free-form temperature gradients(TGs) in PDMS as well as in gases in contact with the PDMS.

• Journal of the Korea Society of Computer and Information
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• v.18 no.5
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• pp.95-102
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• 2013

In metabolomics, metabolic pathway is represented by well-displayed graph. Metabolic pathways, especially, have a complex binding structure, which makes the graphical representation hard to visualize. There is a problem that edge crossings exponentially increase as the number of nodes grows. To apply automatic graph layout techniques to the genome-scale metabolic flow of metabolism domains, it is very important to reduce unnecessary edge crossing on a metabolic pathway layout. we proposed a metabolic pathway layout algorithm based on 2-layer layout. Our algorithm searches any meaningful component existing in a pathway, such as circular components, highly connected nodes, and the components are drawn in upper layer. Then the remaining subgraphs except meaningful components are drawn in lower layer by utilizing a new radial layout algorithm. It reduces ultimately reduced the number of edge crossings. This algorithm is the basis of flexible analysis for metabolic pathways.