• International Journal of Automotive Technology
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• 제6권5호
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• pp.437-444
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• 2005

Unburned hydrocarbon (UBHC) emissions from gasoline engines remain a primary engineering research and development concern due to stricter emission regulations. Gasoline engines produce more UBHC emissions during cold start and warm-up than during any other stage of operation, because of insufficient fuel-air mixing, particularly in view of the additional fuel enrichment used for early starting. Impingement of fuel droplets on the cylinder wall is a major source of UBHC and a concern for oil dilution. This paper describes an experimental study that was carried out to investigate the distribution and 'footprint' of fuel droplets impinging on the cylinder wall during the intake stroke under engine starting conditions. Injectors having different targeting and atomization characteristics were used in a 4-Valve engine with optical access to the intake port and combustion chamber. The spray and targeting performance were characterized using high-speed visualization and Phase Doppler Interferometry techniques. The fuel droplets impinging on the port, cylinder wall and piston top were characterized using a color imaging technique during simulated engine start-up from room temperature. Highly absorbent filter paper was placed around the circumference of the cylinder liner and on the piston top to collect fuel droplets during the intake strokes. A small amount of colored dye, which dissolves completely in gasoline, was used as the tracer. Color density on the paper, which is correlated with the amount of fuel deposited and its distribution on the cylinder wall, was measured using image analysis. The results show that by comparing the locations of the wetted footprints and their color intensities, the influence of fuel injection and engine conditions can be qualitatively and quantitatively examined. Fast FID measurements of UBHC were also performed on the engine for correlation to the mixture formation results.

• 한국정보통신학회논문지
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• 제8권2호
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• pp.420-429
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• 2004

인체 생리의 부조화에 의한 기능적 이상 진단이 가시화 장비나 임상병리 소견으로도 진단할 수 없는 경우가 있기 때문에, 현대과학과 의공학의 특성을 접목한 EFG(Electro Functio Gram：기능전도) 측정 개념의 진단기술 개발이 요구되고 있다. 따라서 이러한 기능적 진단기술을 이용하여 양ㆍ한방 모든 분야에서 기초 진단기로 사용할 수 있는 재현성과 신뢰성, 편리성을 갖춘 범용의 진단시스템으로 개발하였다. 또한, 한의학적진단 및 치료를 위한 기와 혈의 인체 순환을 진단할 수 있는 사지 8CH(양,음경락), 두부 2CH 동시계측 방법 및 일괄 부착식 전극을 개발하였다. 성인 남자 20명(정상인)을 대상으로 한 임상데이터 분석결과, 인체의 12경락의 상태 및 자율신경계통의 상태를 진단할 수 있어서, 진단장비로써의 유의성을 확인하였다. 따라서, 본 논문에서는 인체 12부위의 음경락 양경락을 측정할 수 있는 H/W 및 S/W을 구현하고, EFG 체계를 구축하여 생체-전기적 반응에 의한 한의학적 진단 시스템을 설계하였다.

• 한국추진공학회지
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• 제22권1호
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• pp.58-65
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• 2018

초고속 비행체의 성능을 향상시키기 위해 비행체 선두부에 대한 연구가 다양하게 수행되고 있다. 본 연구에서는 초음속 영역에서 역분사 공기 제트를 활용하여 유동 특성 및 항력 감소에 대한 실험 연구를 수행하였다. 고속카메라를 활용한 쉴리렌 가시화 방법으로 분사 유동을 가시화 하였으며, 토크센서를 이용해 분사 압력 조건에 따른 항력 변화를 측정하였다. 측정 결과, 분사 압력비 1.58 ~ 1.70 조건에서 비정상 상태의 유동이 정상 상태로 변화하였으며, 역분사 공기 제트의 분사 압력이 높을수록 항력이 감소하는 경향을 보였다.

• Journal of Microbiology and Biotechnology
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• 제33권8호
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• pp.1101-1110
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• 2023

Streptococcus mutans is the primary causative agent of caries, which is one of the most common human diseases. Thus, rapid and early detection of cariogenic bacteria is critical for its prevention. This study investigated the combination of loop-mediated isothermal amplification (LAMP) and microfluid technology to quantitatively detect S. mutans. A low-cost, rapid microfluidic chip using LAMP technology was developed to amplify and detect bacteria at 2.2-2.2 × 10⁶ colony-forming units (CFU)/ml and its detection limits were compared to those of standard polymerase chain reaction. A visualization system was established to quantitatively determine the experimental results, and a functional relationship between the bacterial concentration and quantitative results was established. The detection limit of S. mutans using this microfluidic chip was 2.2 CFU/ml, which was lower than that of the standard approach. After quantification, the experimental results showed a good linear relationship with the concentration of S. mutans, thereby confirming the effectiveness and accuracy of the custom-made integrated LAMP microfluidic system for the detection of S. mutans. The microfluidic system described herein may represent a promising simple detection method for the specific and rapid testing of individuals at risk of caries.

• Korean Chemical Engineering Research
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• 제49권3호
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• pp.361-366
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• 2011

몬테칼로 시뮬레이션 방법을 사용하여 유기화합물의 열역학적 물성을 예측하는 새로운 분자 시뮬레이션 소프트웨어를 개발하였다. 분자 구조, 분자간 포텐셜 에너지 함수와 엄밀한 통계역학적 원리로부터 많은 분자들을 포함한 계의 거동에 대한 확률 분포를 구하고 거시적인 계의 열역학적 물성을 계산한다. 본 연구에서 개발된 소프트웨어 cheMC는 윈도우즈 플랫폼에 기반하여 사용자 접근성이 좋고, 가시화 도구 및 차트 생성 기능 등 직관적인 인터페이스로 시뮬레이션 관리가 쉽다. 분자 시뮬레이션은 기존의 상태 방정식을 사용한 열역학 물성 연구를 보완하고, 향후 그 역할이 점점 더 커질 것으로 기대된다.

• 정보보호학회논문지
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• 제25권6호
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• pp.1495-1502
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• 2015

차량용 블랙박스는 실시간으로 차량의 상태를 기록하는 중요한 데이터 처리 장치로 영상뿐만 아니라 충격량, 속도, 방향과 같은 비영상정보를 함께 저장한다. 비영상정보는 시각적으로 확인할 수 없는 다양한 정보를 담고 있어 차량의 사고 당시 환경과 차량의 상태를 파악하는데 중요한 근거로 활용된다. 그러나 영상정보 만을 다루는 일반적인 디지털 영상장치 포렌식 절차를 이용해 차량용 블랙박스 데이터를 분석을 진행하면 사건해결에 중요한 비영상정보를 활용할 수 없다. 본 논문에서 차량용 블랙박스의 모든 데이터를 추출하고 해석하여 사고 조사 환경에 활용할 수 있는 차량용 블랙박스의 디지털 포렌식 분석 절차를 제안한다. 또한 국내 시판중인 차량용 블랙박스를 선정하여 제시한 분석 절차를 이용하여 분석하였다.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2008년도 정기학술발표대회 논문집
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• pp.68-73
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• 2008

최근 정보화 기반의 공사관리기법은 기존의 수치적 정보관리에서 VR기반의 시각적 정보관리로 변화되고 있다. 본 연구에서는 토목공사의 기획단계, 설계단계, 시공단계에서 VR시스템을 기반으로 사용할 수 있는 기능에 대해 구현절차를 IDEF0모형으로 제시한다. 연구에서 IDEF0모형은 실제 가상건설시스템의 기능으로 토목공사의 각 단계에 적용시켜 실무활용성을 검증하는데 활용하고 있다. 제시된 기능모형에 근거하여 연구에서는 각 단계별로 VR기반 시뮬레이션 기능들을 개발하였다. 개발된 가상건설시스템은 3D객체기반으로 설계정보의 시각적인 효과를 증진시킴으로서 효율적인 설계안의 검토를 가능하게 할 수 있다.

• Journal of Advanced Marine Engineering and Technology
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• 제26권4호
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• pp.464-471
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• 2002

Porosity formation in partial penetration welds by high power lasers is a serious problem in industry. There are two main causes that induce porosity formation. One form of porosity is due to gases (e.g. hydrogen, oxygen) dissolving into the weld pool because of the high temperature and then the rapid solidification traps gases as a bubble in the weld metal. The second problem is voids formed by the keyhole collapsing due to unstable keyhole fluid dynamics. The voids that form at the bottom of the keyhole are relatively large and irregular in shape compared to the gas bubbles; this void formation is the primary concern in this paper. The reduction of voids formed by keyhole collapse is achieved by improving the stability of keyhole. Two methods to improve keyhole stability are discussed in this paper: pulse modulation and beam incident angle. Pulse modulation of the laser beam was performed between 100 Hz and 500 Hz to find out the optimum frequency for the keyhole dynamics. The incident beam angle changed the impact angle of the laser beam to the work surface in a range of 0 to 25 degrees. Glycerin in a semi-solidified state is used as a medium for performing the welding because its transparency allows of visualization of the keyhole.

• International Journal of Contents
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• 제13권1호
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• pp.45-52
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• 2017

Carbon Capture and Storage (CCS) technologies involve three major stages, i.e., capture, transport, and storage. The transportation stage of CCS technologies has received relatively little attention because the requirements for $CO_2$ transport differ based on the industry-related conditions, geological, and demographical characteristics of each country. In this study, we analyzed the properties of $CO_2$ transport using a pipeline. This study has important implications for ensuring the stability of a long-term CCS as well as the large cost savings, as compared to the small cost ratio as a percentage of the entire CCS system. The state of $CO_2$, network topologies, and node distribution are among the major factors that influence $CO_2$ transport via pipelines. For the analysis of the properties of $CO_2$ transport using a pipeline, the $CO_2$ pipeline connections were visualized by the simulator developed by Lee [11] based on the network topologies in $CO_2$ transport. The case of Korean CCS technologies was applied to the simulation.

• International Journal of Automotive Technology
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• 제7권5호
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• pp.519-526
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• 2006

For investigating the effect of fuel stratification on flame propagation, initial flame development and propagation were visualized under different axially stratified states in a port injection SI engine. Stratification was controlled by the combination of the port swirl ratio and injection timing. Experiments were performed in an optical single cylinder engine modified from a production engine and images were captured through the quartz window mounted in the piston by an intensified CCD camera. Firstly in this paper, the characteristics under no port-generated swirl condition, i.e. normal conventional case was studied. Under various stratified conditions, flame images were captured at the pre-set crank angles. These were averaged and processed to characterize the flames propagation. The flame stability was estimated by the weighted average of flame area and luminosity. The stability was also evaluated through the standard deviation of flame area and propagation distance, and mean absolute deviation of propagating direction. Results show that stratification state according to injection timing do not affect on the direction of flame propagation. The flame development and the initial flame stability are strongly dependent on the stratified conditions and the initial flame stability is closely related to the engine stability and lean misfire limit.