• 한국가구학회지
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• 제29권1호
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• pp.1-7
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• 2018

A study was carried out to observe the 1% aqueous safranine solution flow speed in longitudinal and radial directions of softwood Metasequoia glyptostroboides, diffuse-porous wood Anthocephalus cadamba and ring-porouswood Fraxinus rhynchophylla. In radial direction, ray cells and in longitudinal direction, tracheids, vessel and wood fiber were considered for the measurement of liquid penetration speed at less than 12% moisture contents (MC). The length, lumen diameter, pit diameter, end wall pit diameter and the numbers of end wall pits determined for the flow rate. The liquid flow in the those cells was captured via video and the capillary flow rate in the ones were measured. Vessel in hardwood species and tracheids in softwood was found to facilitate prime role in longitudinal penetration. Anatomical features like the length and diameter, end-wall pit numbers of ray parenchyma were found also responsible fluid flow differences. On the other hand, vessel and fiber structure affected the longitudinal flow of liquids. Therefore, the average liquid penetration depth in longitudinal tracheids of Metasequoia glyptostroboides was found the highest among all cells considered in Anthocephalus cadamba and Fraxinus rhynchophylla In radial direction, ray parenchyma of Metasequoia glyptostroboides was found the highest depth and the one of Fraxinus rhynchophylla was the lowest. The solution was penetrated lowest depth in the wood fiber of Fraxinus rhynchophylla. The large vessel of Fraxinus rhynchophylla was found the lowest depth among the vessels. The solutin was penetrated to the wood fiber of Anthocephalus cadamba higher than the one of Fraxinus rhynchophylla.

• 한국가구학회지
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• 제28권1호
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• pp.88-93
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• 2017

A study was carried out to observe the 1% aqueous safranine solution flow speed in longitudinal and radial directions of softwood Larix kaempferi (Lamb.)Carriere, diffuse-porous wood Betula davurica Pall.. and ring-porouswood Castanea crenata S.etZ. In radial direction, ray cells and in longitudinal direction, tracheids, vessel and wood fiber were considered for the measurement of liquid penetration speed at less than 12% moisture contents (MC). The length, lumen diameter, pit diameter, end wall pit diameter and the numbers of end wall pits determined for the flow rate. The liquid flow in the those cells was captured via video and the capillary flow rate in the ones were measured. Vessel in hardwood species and tracheids in softwood was found to facilitate prime role in longitudinal penetration. Anatomical features like the length and diameter, end-wall pit numbers of ray parenchyma were found also responsible fluid flow differences. On the other hand, vessel and fiber structure affected the longitudinal flow of liquids. Therefore, the average liquid penetration depth in longitudinal tracheids of Larix kaempferi was found the highest among all cells considered in Betula davurica and Castanea crenata, In radial direction, ray parenchyma of Larix kaempferi was found the highest depth and the one of Betula davurica was the lowest. The solution was penetrated lowest depth in the wood fiber of Castanea crenata. The large vessel of Castanea crenata was found the lowest depth among the vessels. The solutin was penetrated to the wood fiber of Betula davurica higher than the one of Castanea crenata.

• 한국컴퓨터정보학회논문지
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• 제17권3호
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• pp.105-111
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• 2012

광용적맥파는 심박과 동맥 혈액의 산소포화도 등을 측정하기 위하여 널리 사용된다. 본 논문에서는 요골동맥에서 780nm와 940nm 적외선 LED를 사용하여 PPG 신호를 측정할 수 있는 모니터링 시스템을 구현하였다. 구현된 시스템은 여러 상황에서 특성이 서로 다른 8종의 LED와 2종의 광전 센서를 조합하여 요골동맥에서 광전용적맥파를 측정하였다. 요골동맥에서 측정된 파형들은 반전되어서 기록된다. 이렇게 반전된 파형은 수축기의 신호는 감소시키고, 확장기의 신호는 증가시킨다. 시스템을 통하여 투과형 방식과 반사형 방식에서 각각의 신호 검출이 적합한 환경과 최적의 센서 조합을 파악하여 모니터링 시스템을 구현하고, 각 조합별 그 결과 피검자의 요골동맥에서 안정적으로 사용할 수 있는 심박신호 측정 시스템을 개발하였다.

• Geomechanics and Engineering
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• 제12권5호
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• pp.771-783
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• 2017

Using a transparent fracture replica with aperture size and water-cement ratio (w/c), the factors affecting the penetration behavior of rock grouting were investigated through laboratory experiments. In addition, the waterproof efficiency was estimated by the reduction of water outflow through the fractures after the grout curing process. Penetration behavior shows that grout penetration patterns present similarly radial forms in all experimental cases; however, velocity of grout penetration showed clear differences according to the aperture sizes and water-cement ratio. It can be seen that the waterproof efficiency increased as the aperture size and w/c decreased. During grout injection or curing processes, air bubbles formed and bleeding occurred, both of which affected the waterproof ability of the grouting. These two phenomena can significantly prevent the successful performance of rock grouting in field-scale underground spaces, especially at deep depth conditions. Our research can provide a foundation for improving and optimizing the innovative techniques of rock grouting.

• 한국가구학회지
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• 제19권2호
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• pp.151-155
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• 2008

An experiment was conducted to observe the 5% CCFZ solution penetration depth through ray parenchyma and ray tracheid of Larix kapempferi. Moisture content was adjusted 28% for both sapwood and heartwood. Even though the moisture content was same, heartwood was 1.3 times less permeable than sapwood and the difference was found statistically significant. Due to anatomical differences between ray parenchyma and ray tracheid, ray parenchyma was about 1.3 times more permeable than ray tracheid. Penetration speed was high initially and it decreased rapidly in course of time.

• Journal of Electrical Engineering and Technology
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• 제11권3호
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• pp.551-559
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• 2016

The present trend of increasing the penetration levels of Distributed Generator (DG) in the distribution network has made the issue of Islanding crucial for the reliable operation of the network. The islanding, if not detected early may lead to the collapse of the system as it can drive the distribution system to the cascaded failure. In this paper, an extensive study of the effect of DG placement and sizing is performed by dividing the system into different zones to obtain a reduced effect of islanding. The siting and sizing of DG is carried out to improve the overall voltage profile or/and reduction in active power loss using two stage Genetic Algorithm (GA). In the first stage a basic knockout selection is considered and the best population is taken for next stage, where roulette selection for crossover and mutation is performed for optimal placement and sizing of DGs. The effect of the islanding, due to load variations is reduced by optimal siting and sizing of DG. The effectiveness of the proposed scheme is tested on the IEEE 33 and 69 radial bus systems and the results obtained are promising.

• 대한기계학회논문집B
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• 제25권5호
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• pp.627-633
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• 2001

Characteristics of a diesel spray impingement with the variation of ambient temperature, wall temperature and ambient pressure were investigated through shadowgraphy method by using high speed camera. The radial penetration of spray was increased with ambient temperature and wall temperature. It is resulted from the decrease of ambient gas density caused by the increase of temperature. The height of spray was also increased with ambient temperature and wall temperature, because the height of stagnate region is noticeably increased, although height of wall jet vortex is decreased. At the same ambient pressure, the area ratio of impinging spray of room temperature environment to high temperature environment was increased, as the temperature difference between room temperature and high temperature increases. And the increment of area ratio was higher at low ambient pressure than high ambient pressure.

• 한국해양공학회지
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• 제35권2호
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• pp.141-149
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• 2021

The A60 class deck penetration piece is a fire-resistance apparatus installed on the deck compartment to protect lives and to prevent flame diffusion in the case of a fire accident in a ship or offshore plant. In this study, the sensitivity of the fire-resistance performance and approximation characteristics for the A60 class penetration piece was evaluated by conducting a transient heat-transfer analysis and fire test. The transient heat-transfer analysis was conducted to evaluate the fire-resistance design of the A60 class deck penetration piece, and the analysis results were verified via the fire test. The penetration-piece length, diameter, material type, and insulation density were used as the design factors (DFs), and the output responses were the weight, temperature, cost, and productivity. The quantitative effects of each DF on the output responses were evaluated using the design-of-experiments method. Additionally, an optimum design case was identified to minimize the weight of the A60 class deck penetration piece while satisfying the allowable limits of the output responses. According to the design-of-experiments results, various approximate models, e.g., a Kriging model, the response surface method, and a radial basis function-based neural network (RBFN), were generated. The design-of-experiments results were verified by the approximation results. It was concluded that among the approximate models, the RBFN was able to explore the design space of the A60 class deck penetration piece with the highest accuracy.

• 터널과지하공간
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• 제32권4호
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• pp.243-253
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• 2022

본 연구에서는 회전식 절삭시험기를 활용하여 TBE (Tunnel Boring Extender)의 굴착효율을 평가하였다. 회전식절삭시험에서 TBE에 의한 굴착과정을 모사하기 위하여 중앙부가 선행 굴착되어 있는 중공형의 암석모사시험체를 모르타르를 이용하여 제작하였다. 회전식 절삭시험기에 설치된 언더커팅 디스크(undercutting disc cutter, UDC)를 이용하여 나선궤적을 따라 암석을 절삭함으로써 TBE에 의한 굴착과정을 모사하였으며, 언더커팅 디스크의 절삭조건을 변화시켜가며 절삭조건들이 커터작용력 및 비에너지에 미치는 영향을 살펴보았다. 시험결과로부터 UDC의 커터작용력은 반경압입깊이와 수직압입깊이가 증가함에 따라 선형적으로 증가하는 경향을 확인할 수 있었으며, 세 방향의 작용력 중 수직력의 비중이 매우 크게 나타났다. 반면 비에너지는 반경방향과 수직방향 압입깊이에 따라 지속적으로 감소하는 경향을 나타내었고, 특히 두 압입깊이의 비에 따라 비에너지가 최소화되는 지점이 나타날 것으로 판단되었다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2000년도 제21회 KOSCO SYMPOSIUM 논문집
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• pp.194-201
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• 2000

This paper is intended to analyze the macroscopic behavior and transient atomization characteristics of the high-pressure gasoline injector in direct-injection gasoline engine. The global spray behavior of fuel injector was visualized by shadowgraph technique. Time-resolved droplet axial and radial velocity components and droplet diameter were measured at many probe positions in both axial and radial directions by a two-component phase Doppler particle analyzer (PDPA). In order to obtain the influence of fuel injection pressure, the macroscopic visualization and experiment of particle measurement on the fuel spray were investigated at 3,5 and 7 MPa of injection pressure under different surrounding pressure in the spray chamber. The results of this work show that the fuel injection pressure of gasoline injector in GDI engine has influence upon the mean droplet diameter, mean velocity of spray droplet, the spray tip penetration, and spray width under the elevated ambient pressure.