• Structural Engineering and Mechanics
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• 제28권6호
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• pp.677-694
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• 2008

A vibration power minimization model is developed, based on the mobility matrix method, for a vibration isolation system consisting of a vibrating source placed on an elastic support structure through multiple resilient mounts. This model is applied to investigate the design optimization of an X-Y motion stage-based vibration isolation system used in semiconductor wire-bonding equipment. By varying the stiffness coefficients of the resilient mounts while constraining the dynamic displacement amplitudes of the X-Y motion stage, the total power flow from the X-Y motion stage (the vibrating source) to the equipment table (the elastic support structure) is minimized at each frequency interval in the concerned frequency range for different stiffnesses of the equipment table. The results show that when the equipment table is relatively flexible, the optimal design based on the proposed vibration power inimization model gives significantly little power flow than that obtained using a conventional vibration force minimization model at some critical frequencies. When the equipment table is rigid enough, both models provide almost the same predictions on the total power flow.

• 상하수도학회지
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• 제10권1호
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• pp.69-77
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• 1996

To evaluate the change of the groundwater flow and the water table response resulting from urbanization, two cases of the transient three-dimensional numerical simulations were performed. Variations of the groundwater flow system caused by withdrawals were analyzed. Two cases of infiltration rates were applied in this study to verify the water table changes. One is the rate under the circumstance during 1994 and the other is the revised rate. The numerical results from this study indicated that groundwater flow was influenced by human impacts. Groundwater flow has been concentrated to Taegu Textile Complex area where had large amount of pumping. Water table so far decreased -2.76m a year due to withdrawals. Water tables of many points were increased more than 30cm when the surface was reformed by infiltrating the rainfall. It was appeared that the improvement of surface to recharge the precipitation was very important to preserve and manage for the groundwater.

• 한국식생활문화학회지
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• 제28권1호
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• pp.41-47
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• 2013

The purpose of this study is to obtain basic materials to complement the 'time series table serving' by analyzing external color elements. We selected traditional Korean restaurants in two five-star hotels and two famous traditional Korean style restaurants and analyzed their colors and the coloration of the Korean table settings. The results are as follows. By using strong luminosity contrast, restaurant A made its customer focus on the food and used red as the principal point (highlighted) color. Desserts, which have small dimensions, were served in 'Buncheong' ware with 'bakji' method, which has strong contrast; this broke the color balance. The use of small patterned dishes with 'johwa' method would achieve color harmony. Restaurant B used a stronger color for the tables than the foods, making the point color inconspicuous. Lowering the brightness and saturation of the table color would be beneficial. In restaurant C, thick green napkins provided the point color, making the atmosphere of the restaurant dull and dark and interfering with the overall bright atmosphere of the restaurant. Using lower saturation, high luminosity, and yellowish colors would bring harmony to the overall atmosphere. In restaurant D, the point colors were divided into three groups; their diversification during the entire course of the meal made the flow of the meal more natural. However, the use of the violet color, which gives a cold feeling, in the middle of the meal courses broke the overall flow of warm color in the meal. Considering the already-present contrast between red and green, it would be better not to use the violet chrysanthemum in the course of the meal. As mentioned above, there are several issues in terms of the color arrangement, the usage of table pads, and the natural flow of colors. Those issues indicate the necessity for an overall plan for the banquet table set-up in terms of color.

• 한국농공학회지
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• 제19권4호
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• pp.4533-4543
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• 1977

The purpose of this study was to investigate and compare flow discharges of rectangular, V-notch and trapezoidal type of cutthrooat flumes, and the published data for trapezoidal parshall flumes. And the trapezoidal cutthroat flumes were also compared in their accuracy of discharge measurements for various convergence ratios in the inlet section and divergence ratios in the outlet section. Five flumes were studied, and all the flumes were 45cm long with flat-bottom and were made of well-finished transparent acryl plate of 3mm thickness. One rectangular, one V-notch and three trapezoidal types were numbered 1 to 5 as shown in Fig. III-1. The measured depth of water was ranged from 5 to 20cm. The results obtained in this study are summarized as follows: 1. The general discharge equations for tested prototypes are listed for free flow in Table IV-1 and for submergence flow in Table IV-4. 2. In both free and submerged flow, the accuracy of the discharge formula obtained by this test is highly significant at 1% level as shown in Table IV-2 and Table IV-6. The accuracy of disharges measured depends upon the convergence and divergence ratios in the trapezoidal types: the less the ratios of convergence as well as divergence, the lower the accuracy. 3. Submergence ratios tend to increase in the order of flume number except flume No. 4. This implies that trapezoidal cutthroat flumes are more acceptable than rectangular or V-notch ones for free flow. 4. The transition submergence for the trapezoidal Parshall flumes ranges from 80-85 percent, which is slightly higher than the tested flume. However, the trapezoidal cutthroat flume No. 5 has higher transition submergence ratio, ranging from 73-78 percent, than other trapezoidal ones. The difference between the trapezoidal Parshall flumes and the trapezoidal cutthroat flumes in transition submergence seems small enough to be ignored in their field use. 5. Trapezoidal cutthroat flume is simple and economical to construct in existing openchannels whose shapes are generally trapezoidal. In order to obtain the best rating accuracy, flume No. 3 among the tested trapezoidal types is recommended, because it shows the highest accuracy for both free and submerged flow.

• 인터넷정보학회논문지
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• 제22권2호
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• pp.11-17
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• 2021

소프트웨어 정의 네트워킹(SDN)은 스위치의 데이터 플레인에서 컨트롤 기능을 분리해 프로그램 가능한 네트워크 관리법을 제시하는 차세대 네트워킹 기술이다. 하지만 SDN 스위치는 패킷 포워딩에 쓰이는 플로우 테이블의 부족한 용량으로 인해, 플로우 엔트리를 충분히 수용하지 못하는 문제가 있다. 이는 플로우 테이블의 오버플로우 등을 야기해 네트워크 성능을 저하시킬 수 있으므로, 본 논문은 비활성화된 플로우를 적시에 방출해 플로우 테이블 사용량을 최적으로 유지할 수 있는 정책을 제안한다. 특히, 사용자 데이터그램 프로토콜(UDP) 플로우 엔트리들의 정보를 주기적으로 샘플링하여 비활성화된 엔트리들이 조기에 방출될 수 있도록 한다. 트래픽에 기반한 실험을 통하여, 우리는 본 정책이 Random, FIFO 정책과 비교해 오버플로우 및 플로우 재설치 발생 횟수를 크게 감소시키는 것을 확인할 수 있었다.

• Nuclear Engineering and Technology
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• 제44권1호
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• pp.71-78
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• 2012

In many semi-empirical analyses of flow boiling heat transfer, an annular flow is often assumed as a model flow and the local liquid film thickness is a key parameter in the analysis. This work considers a simple electrical conductance technique to estimate the local liquid film thickness in two-phase annular flows. In this approach, many electrodes are mounted flush with the inner wall of the pipe. Voltage differences between two neighboring electrodes for concentric annular flows with various liquid film thicknesses are obtained before the main experiments and logged in a look-up table. For an actual application in the annual flow, voltage differences of neighboring electrodes are measured and then corresponding local film thicknesses are determined by the interpolation of the look-up table. Even though the proposed technique is quite simple and straightforward, the numerical and static phantom experiments support its usefulness.

• 한국항공우주학회지
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• 제38권4호
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• pp.342-351
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• 2010

UAV는 임무 수행을 위한 INS 장비와 광학 장비를 갖추고 있다. 이 논문에서는 UAV를 위한 알고리즘으로 칼만 필터와 광류를 이용하는 영상기반 자세추정 알고리즘을 제안한다. 광류는 UAV에 장착된 카메라의 영상으로부터 획득하며 UAV의 자세는 광류를 통해 측정된다. 이 논문에서 UAV 자세의 추정과 낮은 신뢰성을 보완하기위해 칼만 필터를 사용한다. 그리고 실험을 통해 알고리즘을 검증하였다. Rate table과 실제 비행영상을 이용하여 실험 하였으며, 본 논문에서 UAV의 자세 추정 알고리즘 검증 결과를 보였다. Rate table 실험에서 오차는 2도 이내였으며, AHRS를 통해 측정한 결과와 비슷한 경향을 보인다. 그러나 실제 비행 영상 실험에서 최대 Yaw 오차는 21도였으며, 최대 Pitch 오차는 7.8도로 나타났다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.95-96
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• 2023

In this study, the table flow of fiber reinforced cement composites mixed with CNTs dispersed differently according to the dispersion method was evaluated. The mixture was composed of plain mixture according to the presence or absence of ultrasonic dispersion and PCE-based dispersants A and B of 0.5% and 1.0%, respectively, CNT was mixed with 0.03% of cement weight and fiber was mixed with 1.5% of total volume. As a result of the experiment, NC-A0.5 showed a fluidity similar to that of P without CNT. The fluidity of NC-A0.5 and P-N showed a similar tendency, which is considered to be due to the distribution of evenly dispersed CNT particles without agglomeration between cement particles due to the dispersant. NC-B0.5 showed a similar level of firmness to P-U, but after hitting 250 mm, B Agent seems to have a significant effect on liquidity improvement.Both NC-A1.0 and NC-B1.0 seem to have increased flow due to excessive dispersion.

• 물과 미래
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• 제22권3호
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• pp.289-298
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• 1989

A review is made of transient phenomena ralation to flow in the vadose zone. Reviewed topics include rapid water table response to rainfall, pulsating flow due to pressure perturbations in the vasoes zone, and the wave-like propagation of increased soil moisture caused by intermittent rainfall. As a basis of interpreting these phenomena, zoning of the vadose zone into a residual water zone, an unsaturated capillaty zone, and a saturated capillary zone are proposed. Possible implications with respect to hydrological processes relating to these phenomena are discussed.

• 지질공학
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• 제13권1호
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• pp.51-65
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• 2003

불포화대에서 저밀도 비수용성유체의 이동과 분포를 모의하기 위하여 STOMP(Subsurface Transport over Multiple Phase) 시뮬레이터를 이용하였다. 균질한 매질에서의 저밀도 비수용성유체의 이동은 조립질 매질에서 빠르고, 세립질 매질에서는 불포화대에 더 많이 잔류한다. 조립질 매질 내에 세립질층이 존재할 경우, 이 층이 지하수면으로부터 멀수록 저밀도 비수용성유체가 불포화대에 더 많이 잔류된다. 조립질 매질에 세립질 또는 더 조립질인 매질이 렌즈 상으로 존재하는 경우에는 저밀도 비수용성유체가 이들 렌즈를 통과하지 못한다. 불균질한 렌즈가 존재할 때의 저밀도 비수용성유체의 분포를 초기조건으로, 지하수면의 변동에 따른 저밀도 비수용성유체의 이동을 모의하였다. 지하수위의 변동에 따라 불포화대에 잔류되어 있던 저밀도 비수용성유체의 수직방향 이동이 증가되었다. 특히, 지하수면의 하강 시 저밀도 비수용성유체가 조립질 렌즈를 통해 이동하나, 세립질 렌즈를 통해서는 이동하지 못한다. 일련의 수치실험의 결과로부터 유류 등의 저밀도 비수용성유체의 오염분포는 매질의 불균질성 그리고 지하수위 변동과 같은 수리지질학특성에 의해 크게 영향을 받을 수 있음을 알 수 있다.