• 한국지구물리탐사학회:학술대회논문집
• /
• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
• /
• pp.676-683
• /
• 2003

A laboratory experiment using artificial fracture rocks was used to understand the 3-dimensional dispersion of a tracer and the mixing process in a fractured network. In this experiment, 12cm polystyrene foam cubes with two electrodes for monitoring electric conductivity (EC) were used as artificial fractured rocks. Distilled water with 0.5mS/m was used as a tracer in water with 35mS/m and the difference of EC between the tracer and the water was monitored by a multipoint simultaneous measurement system of electrical resistance. The results showed that even if the fracture arrangement pattern was not straight in the direction of the flow, the tracer did not diffuse along individual fractures and an oval tracer plume, which was the distribution of tracer concentrations, tended to be form in the direction of the flow. The vertical cross section of the tracer distribution showed small diffusivity in the vertical direction. The calculated total tracer volume passing through each measurement point in the horizontal cross section showed while that the solute passed through measurement points near the direction of hydraulic gradient and in other directions, the passed tracer volumes were small. Using Peclet number as a criterion, it was found that the mass distribution at the fracture intersection was controlled in the stage of transition between the complete mixing model and the streamline routing model.

• 패션비즈니스
• /
• 제11권1호
• /
• pp.15-25
• /
• 2007

As a part of the study for the materials development of compound feelings, therefore, this study investigated into the effects of the colors of warp and weft on the overall colors of fabrics, along with the visual changes of colors by the measuring angle of both warp and weft, by means of cross-dyeing of cotton/PET union fabrics. First, the dyeing of cotton and PET fabrics individually with the same color, the dyeing of PET fabrics followed by that of cotton fabrics resulted in a small difference in color than the dyeing in the reversed order. Second, in the case of the dyeing of cotton/PET union fabrics with the color of one fiber fixed and that of the other in ten colors, the color of cotton fiber, which is warp, gave much influence. In addition, the color change was remarkable among complementary colors, while it was negligible among adjacent colors. Third, in the case of dyeing of cotton/PET union fabrics with the color of one fiber fixed and that of the other in ten colors, the results were different by the measuring angle. When PET was fixed in green and cotton was dyed in ten colors, color-deepening was observed by the inclination in the direction of warp and weft without the dominance over all colors like cotton. When cotton was dyed in red and PET in ten colors, the color of PET appeared dimly in the horizontal case by the direction of the light, and red appeared as inclined in the direction of warp and weft. This is because of the dominance of cotton color over the overall color, since the density of cotton fiber, the warp of union fabrics, is higher than that of PET, the weft. Thus, this is to be considered in the selection of the warp's color. In view of the above results, the color changes are outstanding when the color of warp dominates the overall color and when the colors of warp and weft are complementary, in comparison with the case when the colors are adjacent. The colors also change by the measuring angle.

• 대한기계학회논문집
• /
• 제8권5호
• /
• pp.442-449
• /
• 1984

본 연구에서는 두 분류가 교우되어 배합이 이루어지는 유동역에서 3차원 방향 에 대하여 평균속도분포, 난류강도분포, 난류전단응력분포, 상관계수의 분포 및 난류 운동에너지와 운동량의 변화 등을 측정 분석하였다.

• Journal of the Korean Wood Science and Technology
• /
• 제50권1호
• /
• pp.1-11
• /
• 2022

To evaluate the bearing strength of red pine cross-laminated timber (CLT) with self-tapping screw (STS), which is widely used as a fastener for connection in CLT building, the bearing test was conducted. Accoring to the STS's diameters (8, 10, 12 mm), the bearing test specimens with half hole were manufactured. Bearing strength was compared and reviewed in consideration of the configuration in STS and the loading direction to the grain of red pine. As a result of the bearing test on the STS's diameter, the yield bearing load increases as the larger diameter of the STS in all directions of the red pine. The bearing strength of the thread part (thread + tip) was higher than the shank part (shank + shank cutter). In compared with the directions to the grain of red pine, the bearing strength of the cross section parallel to the loading direction was the highest, and the tangent section was the lowest bearing strength. The average bearing strength of the loading direction in parallel to the grain was 23.43 MPa, which was about 45% higher than the average 16.16 MPa in perpendicular to the grain. The predicted bearing strength calculated by Eurocode (EN) and Korean Building Code (KBC)'s equation was lower than the experimental value. It is nessesary to propose the new equations of bearing strength reflected the configuration information of STS.

• Journal of Information Technology Applications and Management
• /
• 제22권3호
• /
• pp.105-114
• /
• 2015

This paper presents a fast Time Difference of Arrival (TDOA) estimation for sound source localization. TDOA is the time difference between the arrival times of a signal at two sensors. We propose a partial cross correlation method to increase the speed of TDOA estimation for sound source localization. We do this by predicting which part of the cross correlation function contains the required TDOA value with the help of the signal energies, and then we compute the cross correlation function in that direction only. Experiments show approximately 50% reduction in the cross correlation computation time thereby increasing the speed of TDOA computation. This makes it very relevant for real world surveillance.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2000년도 춘계종합학술대회
• /
• pp.119-123
• /
• 2000

본 논문에서는 광대역특성과 원편파특성을 얻기 위해 급전용 마이크로스트립 라인과 전자기적으로 결합하는 Cross 다이폴로 구상된 안테나를 설계하였다. 다이폴의 길이, 각도, 비유전율, 다이폴과 급전 마이크로스트립 라인과의 간격 둥의 파라미터 스터디를 통해 광대역과 원편파특성을 만족시켰다. 계산을 통해 주빔의 축비가 0.1 dB이하로 좋은 원편파특성을 나타내고 있으며, 정면방향으로의 Cross polarization의 레벨도 약 -58 dB를 보여준다.

• 한국군사과학기술학회지
• /
• 제10권3호
• /
• pp.16-24
• /
• 2007

The high-frequency analysis method of back-scattering cross section spectrum of rotating targets is established. The time history of the back-scattering cross section is calculated using a quasi-stationary approach, based on a physical optics and a physical theory of diffraction, combining an adaptive triangular beam method to consider the shadow effect. And the spectra of back-scattering cross section by the Doppler effect are analyzed applying a simple fast Fourier transform method to its time history. The numerical calculation for rotating targets, such as rotating metal plates and underwater propeller, are carried out. The time history appears to be periodic with respect to the number of wings. The backscattering cross section spectrum level and its frequency shift are dependent on the rotating speed, direction, and the shape of the targets.

• Wind and Structures
• /
• 제1권1호
• /
• pp.59-66
• /
• 1998

The vibrations of bodies subjected to fluid flow can cause modifications in the flow conditions, giving rise to interaction forces that depend primarily on displacements and velocities of the body in question. In this paper the linearized equations of motion for bodies of arbitrary prismatic or cylindrical cross-section in two-dimensional cross-flow are presented, considering the three degrees of freedom of the body cross-section. By restraining the rotational motion, equations applicable to circular tubes, pipes or cables are obtained. These equations can be used to determine stability limits for such structural systems when subjected to non uniform cross-flow, or to evaluate, under the quasi static assumption, their response to vortex or turbulent excitation. As a simple illustration, the stability of a pipe subjected to a bidimensional flow in the direction normal to the pipe axis is examined. It is shown that the approach is extremely powerful, allowing the evaluation of fluid-structure interaction in unidimensional structural systems, such as straight or curved pipes, cables, etc, by means of either a combined experimental-numerical scheme or through purely numerical methods.

• 물과 미래
• /
• 제29권5호
• /
• pp.215-222
• /
• 1996

본 논문에서는 다공성 매질의 특수율이 비정체형인 경우 대수투수계수-수두 교차공분산에 관한 식을 유도하였으며, 이 교차공분산은 수두분포로부터 특수장의 통계학적 특성을 유추하는데(inverse problem) 매우 중요한 역할을 담당한다. 비정체형 대수투수계수는 일정한 선형경향과 정체형인 미소 변동의 합으로 구성되었으며, 2차원 포화대수층에서 정상 유동문제를 추계학적으로 해석하여 수두분포를 얻었고 이로부터 교차공분산을 유도하였다. 투수계수의 상관함수가 가우스분포를 가지고 그 경향이 수두 경사와 평행이거나 직교하는 두 가지 경우에 대하여 교차공분산을 살펴 본 결과, 투수장의 경향이 주 흐름방향과 평행한 경우 흐름방향 쪽만 제외하고는 정체형임이 밝혀졌다. 또한, 흐름방향과 직교하는 쪽으로의 교차공분산은 정체형 모델 결과와 달리 영이 아님를 알 수 있었다. 따라서 지하수 유동이나 오염물질 확산문제를 다룰 경우, 투수계수장에 어떤 경향이 존재한다고 의심될 때에는 반드시 그 경향을 해석과정에 포함시켜야 한다.

• Journal of the Korean Wood Science and Technology
• /
• 제49권5호
• /
• pp.504-513
• /
• 2021

In this study, cross-laminated wood panels were manufactured with four softwoods and three hardwoods with the goal of efficiently predicting the static strength performance using dynamic modulus of elasticity (MOE) and simultaneously revealing the dynamic performance of cross-laminated wood panels. The effect of the density of the species on the dynamic MOE of the laminated wood panels was investigated. Moreover, the static bending strength performance was predicted nondestructively through the correlation regression between the dynamic MOE and static bending strength performance. For the dynamic MOE, the parallel- and cross-laminated wood panels composed of oriental oak showed the highest value, whereas the laminated wood panels composed of Japanese cedar showed the lowest value. In all types of parallel- and cross-laminated wood panels, the density dependence was confirmed, and the extent of the density dependence was found to be greater in the P_⊥ and C_⊥ types with perpendicular-direction laminae in the faces than in the P_∥ and C_∥ types with longitudinal-direction laminae in the faces. Our findings confirmed that a high correlation exists at a significance level of 1% between the dynamic modulus and static bending modulus or bending strength in all types of laminated wood panels, and that the static bending strength performance can be predicted through the dynamic MOE.