• Title/Summary/Keyword: equivalent depth

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Development of Earthquake Prevention Technique Considering Geotechnical Site Characteristics of Korea (국내 지반조건이 고려된 지진 방재기술 확립 방안;지반분류 방법 개선 방안을 중심으로)

  • Kim, Dong-Soo;Yoon, Jong-Ku;Kim, Kyung-Teak;Cho, Seong-Ha
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.10a
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    • pp.154-162
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    • 2005
  • In this paper, site response analyses were performed based on equivalent linear technique using the shear wave velocity profiles of 162 sites collected around the Korean peninsula. The site characteristics, particularly the shear wave velocities and the depth to the bedrock, are compared to those in the western United States. The results show that the site-response coefficients based on the mean shear velocity of the top 30m ($V_{S30}$) suggested in the current code underestimates the motion in short-period ranges and overestimates the motion in mid-period ranges. Also the current Korean code based on UBC is required to be modified considering site characteristics in Korea for the reliable estimation of site amplification. From the results of numerical estimations, new regression curves were derived between site coefficients ($F_a$ and $F_v$) and the fundamental site periods, and site coefficients were grouped based on site periods in the regions of shallow bedrock. The standard deviations of the proposed method was reasonable compared to site classification based on $V_{S30}$. Finally, new site classification system is recommended based on site periods for regions of shallow bedrock depth in Korea.

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Numerical Study of a Novel Bi-focal Metallic Fresnel Zone Plate Having Shallow Depth-of-field Characteristics

  • Kim, Jinseob;Kim, Juhwan;Na, Jeongkyun;Jeong, Yoonchan
    • Current Optics and Photonics
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    • v.2 no.2
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    • pp.147-152
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    • 2018
  • We propose a novel bi-focal metallic Fresnel zone plate (MFZP) with shallow depth-of-field (DOF) characteristics. We design the specific annular slit patterns, exploiting the phase-selection-rule method along with the particle swarm optimization algorithm, which we have recently proposed. We numerically investigate the novel characteristics of the bi-focal MFZP in comparison with those of another bi-focal MFZP having equivalent functionality but designed by the conventional multi-zone method. We verify that whilst both bi-focal MFZPs can produce dual focal spots at $15{\mu}m$ and $25{\mu}m$ away from the MFZP plane, the former exhibits characteristics superior to those of the latter from the viewpoint of axial resolution, including the axial side lobe suppression and axial DOF shallowness. We expect the proposed bi-focal MFZP can readily be fabricated with electron-beam evaporation and focused-ion-beam processes and further be exploited for various applications, such as laser micro-machining, optical trapping, biochemical sensing, confocal sensing, etc.

Modelling of tension-stiffening in bending RC elements based on equivalent stiffness of the rebar

  • Torres, Lluis;Barris, Cristina;Kaklauskas, Gintaris;Gribniak, Viktor
    • Structural Engineering and Mechanics
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    • v.53 no.5
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    • pp.997-1016
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    • 2015
  • The contribution of tensioned concrete between cracks (tension-stiffening) cannot be ignored when analysing deformation of reinforced concrete elements. The tension-stiffening effect is crucial when it comes to adequately estimating the load-deformation response of steel reinforced concrete and the more recently appeared fibre reinforced polymer (FRP) reinforced concrete. This paper presents a unified methodology for numerical modelling of the tension-stiffening effect in steel as well as FRP reinforced flexural members using the concept of equivalent deformation modulus and the smeared crack approach to obtain a modified stress-strain relation of the reinforcement. A closed-form solution for the equivalent secant modulus of deformation of the tensioned reinforcement is proposed for rectangular sections taking the Eurocode 2 curvature prediction technique as the reference. Using equations based on general principles of structural mechanics, the main influencing parameters are obtained. It is found that the ratio between the equivalent stiffness and the initial stiffness basically depends on the product of the modular ratio and reinforcement ratio ($n{\rho}$), the effective-to-total depth ratio (d/h), and the level of loading. The proposed methodology is adequate for numerical modelling of tension-stiffening for different FRP and steel reinforcement, under both service and ultimate conditions. Comparison of the predicted and experimental data obtained by the authors indicates that the proposed methodology is capable to adequately model the tension-stiffening effect in beams reinforced with FRP or steel bars within wide range of loading.

Estimating Runoff Curve Numbers for Paddy Fields (논의 유출곡선번호 추정)

  • Im, Sang-Jun;Park, Seung-U
    • Journal of Korea Water Resources Association
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    • v.30 no.4
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    • pp.379-387
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    • 1997
  • This study involves field monitoring of hydrlolgic characteristics of paddy fields under common irrigation practice, statistical analysis of maximum retention storage, determination of CNs for antecedent moisture conditions. Curve numbers were estimated from observed rainfall-runoff relationship of two years data. The estimated CN for AMC-II was 78, and the CNs for AMC-I and II were 63 and 88, respectively. A water balance model was used to find the effect of ridge height changes and initial ponding depth in paddy fields on runoff. The probability distribution of initial ponding depth was also investigated. The initial ponding depth follows normal probability distribution. Initial ponding depth corresponding 10%, 50%, and 90% probability were considered to be equivalent to AMC-I, AMC-II, and AMC-III, respectively. Long-term runoff data from paddy fields were simulated by a water balance model using recorded climate data, ridge height and estimated initial ponding depth derived from probability distribution. The estimated CNs using simulated runoff were 70, 79, and 89 for CN-I, CN-II, and CN-III, respectively.

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An Analytical Study on the Embedded Depth of Concrete Poles in Inclined ground (경사지에서 콘크리트 전주의 근입깊이에 대한 해석적 연구)

  • Yoon, Ki-Yong;Kim, Eung-Seok;Lee, Seung-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.2
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    • pp.1164-1169
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    • 2014
  • Overturning of concrete poles are occurred annually due to natural disaster such as a typhoon. The present code for the resisting moment and the safety on overturning of concrete poles in inclined ground is inadequate. In this study, the concept of the code for those in flat ground is applied to calculate the resisting moment in inclined ground using general analysis program L-Pile Plus13.8. According to the analytical results, the resisting moment in inclined ground is rapidly decrease as increasing the slope angle although the embedded depth are added by the additional embedded depth on the code. It is revealed that the capacity in inclined ground is equivalent to that in flat ground if additional embedded depth is increased from 1.5 to 3 times.

Fishing Experiment for Development of Unused Fishery Resources on the Deep Sea Bed of Korean East Sea (동해구 심해 미이용 자원의 어획 시험 연구)

  • Lee, Byoung-Gee;Lee, Ju-Hee;Shin, Hyeong-Il
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.22 no.4
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    • pp.61-70
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    • 1986
  • In accordance with a rapid growth of demani on aquatic animals, researches of the unused fishery resources On the deep sea b~d in the Korean Waters has been and will be required. The authors carried out a series of fishing experiments to investigate the available resources and to find the effective fishing method on the deep sea bed of the Korean East Sea. In the experiments, 19 kinds of traps which are different from each other in shape, mesh size and entrance diameter were used. The fishing experiments w~r;; carried out in four areas of 20Dm, 600.'11, 800m and 1000.'11 deep respectively, by the Pusan 402 (30:) GT) and the Pusan 403 (279GT), the training ships of National Fisheries University of Pusan, during August, 1986. The catc~ were analyzed with the size, the depth and the construction of traps. The results obtained can be summarized as follows: 1. Main species of the catch w~re pink shrimp, Pandalus bolelis, a kind of welks, Buccimum striatissimum and a kind of larg~ crabs. Chiono8cetes japonicus and the another species were few. 2. The CPUE value (expressed by the number of catch per trap in this paper) of pink shrimp was the highest in the depth of 20J-n around, and the value in the depth of 600.'11 or more decreased gradually with an increase of the depth. But, the value of Buccimum straitissimum was much higher in the depth of 6:J:)!1I or more than that in the depth of 200m around. On the other hand, the value of Chion:Jecetes japonjcus was very low in general. 3. The iniividual body size of the catch differed with the depth. Pink shrimps caught in the depth of 200m around were smaller than those in the depth of 600.'11 or more. In contrast with this, Baccimum striatissim:t.m caught in the depth of 200m around were larger than those in the depth of 600.'11 or more. 4. Depending on the selection curve in Ishida's method for the mesh size of trap webbing, the carapace length of pink shrimp and the shell length of Buccimum striatissimum which are equivalent to 100% relative catching efficiency can be estimated about 3.5cm and 6.5cm or so respectively. 5. The number of catch of pink shrimp and Buccimum striatissimum by the 60.'1'1.'11 entrance diameter of trap were less than that by the 90mm, 120mm and 150mm, even thogh the diffierence am~r, g 9:Jmm, 120.'11.'11 and 150:1'.'11 are not so large.

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Behavior of Bearing Capacity for Shallow Foundation on a Sand overlying Clay Depending on Bearing Capacity Ratio (점토층 위 모래지반의 지지력비에 따른 얕은 기초의 지지력 거동)

  • Jung, Min Hyung;Shin, Hyo Hee;Lee, Song
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.1
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    • pp.198-208
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    • 2011
  • When a structure which has relatively low load constructs on soft clay, the bearing capacity of the ground will be improved by sand overlying clay. In this condition, verifying the bearing capacity is difficult from the P.B.T etcetera in the in-situ. So, it is needed to estimate precise bearing capacity in the design process. In this study, 2-dimensional chamber tests and FEM analyses are conducted to evaluate behavior of bearing capacity for shallow foundations on a sand overlying clay. Because depth ratio H/B and bearing capacity ratio $q_c/q_s$ are selected as main factors, height of a sand, undrained shear strength of a clay and width of a loading are designated as variables. Results from chamber tests are very similar with those of FEM analyses. And it shows that punching shear mechanism is more suitable than the equation of Okamura et al.(1998). To make continual application of load spread mechanism, the equivalent load spread angle is proposed for H/B and $q_c/q_s$. Also, the linear regression equation of critical depth ratio Hf is suggested for $q_c/q_s$.

Measurement of Dose Distribution in Small Fields of NEC LINAC 6 MVX Using Films and Tissue Equivalent Phantoms (필름 및 tissue equivalent 팬톰을 이용한 NEC LINAC 6 MVX 소조사면에 대한 선량분포 측정)

  • Suh, Tae-Suk;Park, Dong-Rak;Choe, Bo-Young;Yoon, Sei-Chul;Jang, Hong-Seok;Park, Il-Bong;Kim, Moon-Chan;Bahk, Yong-Whee;Shin, Kyung-Sub
    • Progress in Medical Physics
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    • v.4 no.2
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    • pp.9-17
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    • 1993
  • The purpose of this paper is to develop a simple system to measure dose distribution in small fields of NEC LINAC 6 MVX using film and solid water instead of ion chamber and water phantom. Specific quantities measured include percent depth dose (PDD), off-axis ratio (OAR). We produced square fields of 1 to 3cm in perimeter in 1cm steps measured at SAD of 80cm. The PDD and OAR measured by film was compared with measurement made with ion chamber. We calculated the TMR from the basic PDD data using the conversion formula. The trends of our measured beam data and philips LINAC are similar each other. The measurement for the small field using film and solid water was simple. Hand-made film phantom was especially useful to measure OARs for the stereotactic radiosurgery.

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On the Contact Behavior Analysis and New Design of O-ring Seals

  • Kim, Chung-Kyun;Cho, Seung-Hyun;Kim, Young-Gyu
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.10b
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    • pp.121-122
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    • 2002
  • This paper presents contact behavior of an Polyperfluoroalkoxyethylene(PTFE) ring seals by a non-linear finite element method using the thermomechanical analysis. PTFE elastomer was assumed as odgen model for numerical analysis in FEM commercial code because elastomer has nonlinear behaviour character. The shape effects are investigated for sealing performance of ring seal in boundary conditions which as gas pressure, groove temperature and various O-ring seal models. Also contact stress and equivalent total strain are investicated. An O-ring seals was modeled four shape which are circle, two sunflower and X. The highest contact stress occurs at sunflower-ring seal with groove deapth of 0.35mm. the equivalent total strain of sunflower-ring seal is lower than that of the others under low gas pressure condition but under gas pressure condition over 4Mpa, that of sunflower-ring seal is higher. The calculated FEM results shows that the Sunflower-ring seal with groove depth of 0.35mm has excellent performance compared with other seal models.

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Analysis of the Chip Shape in Turing (I) -Analysis of the Chip Flow Angle- (선삭가공의 칩형상 해석 (I) -칩흐름각 해석-)

  • 이영문;최수준;우덕진
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.1
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    • pp.139-144
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    • 1991
  • Chip flow angle is one of the important factors to be determined for the scheme of Chip Control. Up to now, however, a dependable way to predict the chip flow angle in practical cutting has not been established satisfactorily. In this paper a rather simple theoretical prediction of chip flow angle is tried based on some already widely confirmed hypotheses. The developed equation of chip flow angle contains the parameters of depth of cut d, feed rate f, nose radius $r_{n}$ side cutting edge angle $C_{s}$, side rake angle .alpha.$_{s}$ and back rake angle .alpha.$_{b}$. Theoretical results of chip flow angle given by this study bas been shown in a good agreement with experimental ones.s.s.s.s.