• Title/Summary/Keyword: Effective Area Ratio

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Effect of the Orifice Area Ratio on the Exit Flow of a Multi-Perforated Tube (다공튜브 오리피스 면적비 변화가 출구유동에 미치는 영향)

  • Lee, Sang-Kyoo;Lee, Jee-Keun
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.25 no.6
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    • pp.317-323
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    • 2013
  • A multi-perforated tube indicates the existence of multiple holes of various shapes on the surface of a long cylinder-type or rectangular tube, and a hole installed on the surface is called an orifice, as it is relatively small in size, compared with the surface area of the tube. In this study, the flow characteristics of a circular multi-perforated tube with many orifices on the surface were investigated experimentally and numerically. The volume flowrate issuing from each orifice, discharge angle, effective flow area ratio, and the flow fields around the orifices were measured and visualized, with the variation of the orifice area ratio, at the same blockage ratio. The volume flowrate distributions along the flow direction of the multi-perforated tube tends to be more uniform, as larger orifices were positioned at the inlet side of the multi-perforated tube, compared with no orifice area change along the flow direction.

A STUDY OF THE NORMAL & ABNORMAL OCCULSAL PATERNS IN ADULTS USING THE SUPERIMPOSED RUBBER PATTERN METHOD (Superimposed Rubber Pattern법에 의한 성인 정상 및 비정상 교합자의 교합 양상에 관한 연구)

  • Choi, Dae-Gyun;Lee, Sung-Bok;Kwon, Young-Hyuk;Choi, Boo-Byung
    • The Journal of Korean Academy of Prosthodontics
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    • v.33 no.3
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    • pp.467-491
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    • 1995
  • In order to analyze the occlusin of intercuspation with maximun bite force, fifteen healthy adult subjects with the ages 23 to 27 were studied(Group1 ; 5-normal occlusion with Angle's Class1, Group2 ; 5-Angle's Class2 malocclusion, Group3 ; 5-Angle’s Class3 malocclusion). Head Position was fixed with occlusal plane paralleling to horizontal line and occlusal registration r cord was made with polyether rubber impression material(Ramitec, ESPECo. West Germany). After all subject were trained for maximum intercuspation at least 5 times, occlusal registration procedure was repeated for this study. Lower posterior rubber occlusal registration records were sliced with 1mm thickness using precision metal sliding channel(Hitachi Ind. Co., Japan). Gross sectional drawings were traced from occluding view of upper and lower posterior teeth on the rubber slices using digitizer, and superimposed for the determination of each drawing distance(Superimposed Rubber Pattern Method). Based on superimposed rubber pattern drawings, total area of occlusal view, sum of each area of the 5 divided occlusal contact provinces and its ratio, total area and number of occlusal contact area were determined to elucidate occlusal stability in the normal and abnormal occlusion groups. The data were analysed by t-test(p=0.05) to determine statistical significance. The obtained results were as follows : 1. Group1 showed the largest standard area with occlusal view of the lower posterior teeth and Group3 showed the smallest area. There was a significant difference between Group2 and Group3(p=0.025), and Gropu1 was not statistically different for both Group2 and Group3. 2. Means and ratio of the under 2.0mm area(D) and ratio showed $197.49mm^2$, 59.76% in Group1, $188,69mm^2$, 56.10% in Group2, and $174.23mm^2$, 55.76% in Group3. The results that Group1 has the most area/ratio and Group3 has the least area/ratio can be considered Group1 is the most advantageous for masticatory effective area, and Group3 is the least adnantageous. 3. Means and ratio of the under 1.0mm area(C) were $198.96mm^2$, 42.65% in Group1, 123.06$mm^2$, 46.58% in Group2, and $92.24mm^2$, 29.52% in Group3. These data means that Group1 is the most advantageous in terms of masticatory effective area and Group3 is the least. 4. Means and ratio of the under 0.5mm area(B) were $86.68mm^2$, 26.68% in Group1, $62.98mm^2$, 18.71% in Group2, and $36.44mm^2$, 11.66% in Group3. These can also be considered Group1 is the most advantageous for masticatory effective area and occlusal stability. 5. Means and ratio of the under 0.05mm area(A) were $30.92mm^2$, 9.21% in Group1, $14.31mm^2$, 4.25% in Group2, and $7.59mm^2$, 2.43% in Group3. The area ratio of the each subject group was(4.1) : (1.9) : (1)and the data of the under 0.05mm area has the intimate relationship with inter-group and intra-group data/ratio. 6. First molar showed the most occlusal contact points in all subject group and Group1 showed somewhat uniformly distributed occlusal contact point except first premolar. In Group2, all contact point in posterior teeth showed significantly reduced distribution except first molar. Group3 showed evenly distributed contace points in first and second molars.

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Variation of Stress Concentration Ratio with Area Replacement Ratio for SCP-Reinforced Soils under Quay Wall (치환율에 따른 안벽구조물 하부 SCP 복합지반의 응력분담비)

  • 김윤태
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.16 no.1
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    • pp.18-26
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    • 2004
  • In order to accelerate the rate of consolidation settlement, to reduce settlement, and to increase bearing capacity for soft ground under quay, sand compaction pile method (SCP) has usually been applied. SCP-reinforced ground is composite soil which consists of the sand pile and the surrounding soft soil. One of main important considerations in design and analysis for SCP-reinforced soils is stress concentration ratio according to area replacement ratio. In this paper, the numerical analysis was conducted to investigate characteristics of stress concentration ratio in composite ground. It was found that stress concentration ratio of composite ground is not constant as well as depends on several factors such as area replacement ratio, depth of soft soil, and consolidation process. The values of stress concentration ratio increase during loading stage due to stress transfer of composite soil, and reach up to 2.5∼12 according to area replacement ratio at the end of construction. After the end of consolidation, however, these values are converged to 2.5 to 6.0 irrespective of area replacement ratio due to increase in effective stress of soft soil during consolidation process.

Analysis of Sediment Yields at Watershed Scale using Area/Slope-Based Sediment Delivery Ratio in SATEEC (SATEEC 시스템을 이용한 면적/경사도에 의한 유달률 산정 방법에 따른 유사량 분석)

  • Park, Younshik;Kim, Jonggun;Kim, Narnwon;Kim, Ki-sung;Choi, Joongdae;Lim, Kyoung Jae
    • Journal of Korean Society on Water Environment
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    • v.23 no.5
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    • pp.650-658
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    • 2007
  • The Universal Soil Loss Equation (USLE) has been used in over 100 countries to estimate potential long-term soil erosion from the field. However, the USLE estimated soil erosion cannot be used to estimate the sediment delivered to the stream networks. For an effective erosion control, it is necessary to compute sediment delivery ratio (SDR) for watershed and sediment yield at watershed outlet. Thus, the Sediment Assessment Tool for Effective Erosion Control (SATEEC) was developed to compute the sediment yield at any point in watershed. In this study, the SATEEC was applied to the Sudong watershed, Chuncheon Gangwon to compare the sediment yield using area-based sediment delivery ratio (SDRA) and slope-based sediment delivery ratio (SDRS) at watershed outlet. The sediment yield using the SDRA by Vanoni, SYA and the sediment yield using the SDRS by Willams and Berndt, SYS were compared for the same sized watersheds. The 19 subwatersheds was 2.19 ha in size, the soil loss and sediment yield were estimated for each subwatershed. Average slope of main stream was about 0.86~3.17%. Soil loss and sediment yield using SDRA and SDRS were distinguished depending on topography, especially in steep and flat areas. The SDRA for all subwatersheds was 0.762, however the SDRS were estimated in the range of 0.553~0.999. The difference between SYA and SYS was -79.74~27.45%. Thus site specific slope-based SDR is more effective in sediment yield estimation than area-based SDR. However it is recommended that watershed characteristic need to be considered in estimating yield behaviors.

An Experimental Study on the Damping Capacity of Lead Rubber Bearing with High Lead-plug Area Ratio (납-플러그 면적비가 큰 LRB의 감쇠능력에 관한 실험적 연구)

  • Choi, Jung-Ho;Kim, Woon-Hak
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.13 no.3 s.55
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    • pp.217-224
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    • 2009
  • Many engineering researches are performed to ensuring structural safety from earthquake. In this study, the damping capacity of LRB(lead rubber bearing) with high lead-plug area ratio was examined by hysteresis loop from experiments. The displacement controlled tests were performed for 12 specimens designed in 2 types by lead-plug area ratio as main parameter. Each coupled specimens were tested by 3 times sinusoidal loads with different loading velocities. From the experimental results, LRB with high lead-plug area ratio has sufficient damping ratio for reducing horizontal seismic load to structures.

Permeable Coastal Pavement Structure for Shore Protection and Removal of Non-point Source Pollutants (연안재해 방지 및 비점오염원 유출저감을 위한 투수블록의 특성 연구)

  • Choi, Yun-Shik;Kim, Jong-Yeong;Han, Sangsoo;Kwon, Soonchul
    • Journal of Ocean Engineering and Technology
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    • v.33 no.6
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    • pp.597-606
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    • 2019
  • Due to climate change, coastal areas are being flooded with torrential rain, typhoons, and tsunamis. In addition, non-point source pollutants (NPSs) that accumulated on the ground, streets, and buildings during the dry season are washed off by rain and stormwater runoff, which adds to the damage associated with environmental pollution, e.g., pollution that makes its way into the ocean. Recently, low impact development (LID) has been considered as a means of controlling water circulation and NPSs. In the coastal area, permeable blocks have been constructed mainly to reduce the flood damage caused by waves. Some important design factors that must be considered to ensure long-term performance are the permeability coefficient, clogging, and the efficiency of the removal of total suspended solids (TSS), but currently there are no standardized design criteria or testing techniques that are used worldwide. Herein, we analyzed the permeability coefficient and the TSS removal efficiency tendency according to the permeability area ratio with an easily-detachable, permeable block filled with calcinated yellow soils as the filter media. Our lab-scale tests indicated that, when the permeability area ratio was 25%, the reduction of the permeability coefficient after clogged was 11%, which was a significant decrease compared to other cases. Permeability persistence increased when the permeability area ratio increased from 50% to 75%. The TSS removal efficiency decreased as the permeability area ratio increased. Our pilot-scale test indicated that the TSS removal efficiency was more than 80% higher in all cases. We also found that the permeability persistence was excellent as the permeability area ratio increased, and, in actual construction, it is effective to set 5.3% of the total area as permeable area in terms of permeability and economic feasibility.

Effective Absorption Capacity of Highly Absorptive Materials using Isothermal Calorimetry, Considering the Effect of Specific Surface Area (등온열량계를 사용한 고흡수성 재료의 유효흡수율 측정: 비표면적의 영향)

  • Lee, Bo Yeon
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.34 no.2
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    • pp.49-56
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    • 2018
  • The use of highly absorptive materials in cement-based materials is increasing for internal curing purpose. However, calculation of correct absorption capacity of such materials is not easy, which leads to change in the effective water-to-cement ratio of cement paste by either absorbing or releasing water. In this study, effective absorption capacity of a highly absorptive material was found using isothermal calorimetry. Moreover, the effect of specific surface area was investigated. It was found that the method was capable of finding effective water absorption capacity of activated carbon fiber. For the activated carbon fiber used in this research, the effect of specific surface area was negligible because the high BET surface area was due to micropores less than 1nm, which does not affect the rate of hydration curve. Thus, the effective absorption capacity of such materials can be found successfully using this method.

Measurement of Effective and Total Impervious Ratio and Its Usage for Watershed Management (유효 및 총불투수율의 산정과 유역관리에서의 활용방안)

  • Choi, Ji-Yong;Koh, Eun-Ju
    • Journal of Environmental Policy
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    • v.7 no.3
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    • pp.121-140
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    • 2008
  • The impervious cover ratio has been used as an important measure for tracing water environment characteristics in watershed. Impervious cover is divided into total impervious cover and effective impervious cover, and its size varies depending on the land use characteristics of a watershed. Total impervious cover can be easily measured using existing land use maps or land cover map, while it takes a considerable amount of time and labor to measure the effective impervious cover, as water flow should be identified at each site. This study is intended to calculate the total impervious cover and effective cover of a sample site, compare their characteristics, and find a method to apply effective and total impervious cover ratios toward watershed management. The analysis of the sample site showed that the effective impervious cover rate(39.7%) was less than the total impervious cover rate(43%). This suggests that it would be acceptable, in terms of time and cost, if total impervious cover is applied as the representative impervious cover ratio of a watershed considering that it was used as basic data to analyze the effect that impervious cover has on the water environment.

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Analysis of Changes in Land Use and Pollution Load for the Unit Watersheds of Total Maximum Daily Loads (총량관리 단위유역의 토지이용 변화 및 오염물질 배출형태 분석)

  • Park, Jun Dae;Oh, Seung Young;Choi, Ok Youn
    • Journal of Korean Society on Water Environment
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    • v.30 no.2
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    • pp.128-137
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    • 2014
  • The land use of the unit watersheds should be maintained appropriately in order to keep the load allotment stable for the management of Total Maximum Daily Loads (TMDLs). This study classified the land area in four types and analyzed the use of each land type and its changing pattern by calculating the occupation and conversion ratios for the unit watersheds in three river basins. The forest land showed the greatest occupation ratio with 63.0%, followed by the farm land with 23%, the other area with 8.0% and the site area with 6.0% in 2003. The occupation ratio of the site and the other area increased by 0.4% and 0.2% respectively, and that of the farm and the forest land decreased by 0.4% and 0.2% respectively in 2007. The conversion ratio for the site area ranged from 1.65% to 1.97%, for the farm land from -0.47% to -0.33%, for the forest land from -0.10% to -0.04% and for the other area from 0.17% to 1.97%. It can be inferred that the decrease in the farm and the forest land contributed to the increase in the site area and that the increase in the other area was mainly made by the decrease in the forest land. It could be more effective to take into account the changes in the site area and in the forest land in the process of developing the TMDL plans.

Development of Food Waste Fermentation System by Low Water-Ratio Salt Minimization (절수 염분제거에 의한 음식물류 폐기물 퇴비화 시스템 개발)

  • Han, Doo-Hee
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.6 no.2
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    • pp.189-194
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    • 2005
  • The food wastes recycling system should be constructed before 2005 in the city area. In order to manufacture the good compost, salt remaining rate should be minimized. We studied the effective method of minimizing salt ratio by diluting with low water ratio. We got the salt remaining ratio less than 0.3% by effective fragmentation method, and we applied the IR heating in order to make good compost.

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