• 제목/요약/키워드: equivalent depth

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Design Charts and Simplified Formulae for Anchored Sheet Pile Wall- Using Equivalent Beam Analysis for Fixed End Supported Wall - (앵커식 널말뚝벽의 설계용 도표와 간편식- 고정지지 널말뚝의 등가보 해석을 사용하여 -)

  • 김기웅;원진오;백영식
    • Journal of the Korean Geotechnical Society
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    • 제16권1호
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    • pp.19-30
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    • 2000
  • The major design parameters of the anchored sheet-pile wall include the determination of required penetration depth, the force acting on the anchor, and the maximum bending moment in the piling. Blum solved the fixed earth supported wall using the equivalent beam method, assuming that the wall can be separated into upper and lower parts of the point of contraflexure. Design charts help designer by simplifying the design procedure. But they have some difficulties under some Geotechnical and geometrical conditions. For example, the conventional design charts can compute design parameters only when the ground water table exists above the dredge line. In this paper, the design charts which can be used for the ground water table existing under the dredge line are presented. And simplified formulae are developed by regression analysis. It is found that simplified formulae are not only very useful for the practice of design but also they can evaluate the result of numerical methods or design charts.

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Fracture Behavior of Concrete and Equivalent Crack Length Theory (콘크리트의 파괴거동규명과 등가균열(等價龜裂)길이 이론확립(理論確立)에 관한 연구)

  • Oh, Byung Hwan
    • KSCE Journal of Civil and Environmental Engineering Research
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    • 제7권2호
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    • pp.59-68
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    • 1987
  • Several series of fracture tests were conducted to explore the fracture characteristics and to determine the fracture energy of concrete. A stable three-point bend test was employed to generate the load-deflection curves. The fracture energy may then be calculated from the area under the complete load-deflection curve. The initial notch-to-beam depth ratio (${\alpha}_0$/H) was varied from zero to 0.6. The prediction formula for the fracture energy of concrete is also derived and is found to depend on the tensile strength and aggregate size. The proposed fracture energy formula can be used for the fracture analysis of concrete structures. The present study also devises an equivalent crack length concept to predict the maximum failure loads of concrete beams. A simple formula for the equivalent crack length is proposed.

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A Study of Quantitative Snow Water Equivalent (SWE) Estimation by Comparing the Snow Measurement Data (적설 관측자료 비교를 통한 정량적 SWE 산출에 관한 연구)

  • Ro, Yonghun;Chang, Ki-Ho;Cha, Joo-Wan;Chung, Gunhui;Choi, Jiwon;Ha, Jong-Chul
    • Atmosphere
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    • 제29권3호
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    • pp.269-282
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    • 2019
  • While it is important to obtain the accurate information on snowfall data due to the increase in damage caused by the heavy snowfall in the winter season, it is not easy to observe the snowfall quantitatively. Recently, snow measurements using a weighing precipitation gauge have been carried out, but there is a problem that high snowfall intensity results in low accuracy. Also, the observed snowfall data are sensitive depending on wind speed, temperature, and humidity. In this study, a new process of quality control for snow water equivalent (SWE) data of the weighing precipitation gauge were proposed to cover the low accuracy of snow data and maximize the data utilization. Snowfall data (SWE) observed by Pluvio, Parsivel, snow-depth meter using laser or ultrasonic, and rainfall gauge in Cloud Physics Observation Site (CPOS) were compared and analyzed. Applying the QC algorithm including the use of number of hydrometeor particles as reference, the increased SWE per the unit time was determined and the data noise was removed and marked by flag. The SWE data converted by the number concentration of hydrometeor particles are tested as a method to restore the QC-removed data, and show good agreement with those of the weighing precipitation gauge, though requiring more case studies. The three events data for heavy snowfall disaster in Pyeongchang area was analyzed. The SWE data with improved quality was showed a good correlation with the eye-measured data ($R^2$ > 0.73).

Study of the Correlation and Ocular Components in Preschool Children (취학전 어린이들의 안광학 성분 측정 및 상관성 분석)

  • Jeon, Soon-Woo;Hwang, Hye-Kyung;Lee, Sun Haeng;Park, Chun-Man
    • Journal of Korean Ophthalmic Optics Society
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    • 제15권3호
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    • pp.201-206
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    • 2010
  • Purpose: This study was to know the correlation among the dimensions of ocular components and refractive error on kindergarten children. Methods: The subjects were 80 preschool students who had no eye diseases. The refraction, corneal diopter, corneal radius, inter-pupillary distance, axial length, anterior chamber depth and dominant eye were measured and analysed. Results: It was shown that the highest correlation was between the axial length and the corneal diopter (r=-0.674, p=0.000). The ratio of height, weight and axial length (AL) to Corneal radius (CR) ratio were positively correlated with the axial length (r=0.351, r=0.408, r=0.488). The spherical equivalent of the refractive error and the corneal diopter were negatively correlated with the axial length (r=-0.302, r=-0.674). The anterior chamber depth and the corneal diopter were positively correlated with the AL/CR ratio (r=0.422, r=0.280). The spherical equivalent of the refractive error and the corneal radius were negatively correlated with the AL/CR ratio. Conclusions: It was shown that the AL/CR ratio was a very important indicator for diagnosing the refractive error of the preschoolers.

Development of Site Classification System and Modification of Design Response Spectra Considering Geotechnical Characteristics in Korea

  • Kim, Dong-Soo;Yoon, Jong-Ku
    • Journal of the Earthquake Engineering Society of Korea
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    • 제11권4호
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    • pp.65-77
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    • 2007
  • Site response analyses were performed based on equivalent linear technique using 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. 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 with reasonable standard deviations compared to site classification based on $V_{S30}$. Finally, new site classification system and modification of design response spectra are recommended considering geotechnical characteristics in Korea.

Study on Model Test Technique of Deepwater Moorings: A Hybrid Modeling of A OTEC Mooring System (심해계류 모형시험 기법 연구: OTEC 계류시스템의 혼합형 모델링)

  • Hong, Sup;Kim, Jin-Ha;Hong, Seok-Won;Hong, Sa-Young;Jalihal, Purnima
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 한국해양공학회 2001년도 추계학술대회 논문집
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    • pp.97-102
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    • 2001
  • This paper describes an investigation how to carry out model tests of deepwater moorings exceeding the basin depth range. A hybrid mooring model, a combination of mooring lines scaled model and a couple of linear springs, is taken into account as an equivalent substitute of a full depth mooring system. Such an idea is applied to the model test of an OTEC mooring system to be installed in 1000m deep ocean. A 1/25 scaled model test of surface vessel and the upper part of mooring system is performed at ocean engineering basin. Possibility and limitation of the hybrid mooring modeling is discussed.

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Experimental and Numerical Simulation Studies of Low-Velocity Impact Responses on Sandwich Panels for a BIMODAL Tram

  • Lee, Jae-Youl;Shin, Kwang-Bok;Jeong, Jong-Cheol
    • Advanced Composite Materials
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    • 제18권1호
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    • pp.1-20
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    • 2009
  • This paper describes the results of experiments and numerical simulation studies on the impact and indentation damage created by low-velocity impact subjected onto honeycomb sandwich panels for application to the BIMODAL tram. The test panels were subjected to low-velocity impact loading using an instrumented testing machine at six energy levels. Contact force histories as a function of time were evaluated and compared. The extent of the damage and depth of the permanent indentation was measured quantitatively using a 3-dimensional scanner. An explicit finite element analysis based on LS-DYNA3D was focused on the introduction of a material damage model and numerical simulation of low-velocity impact responses on honeycomb sandwich panels. Extensive material testing was conducted to determine the input parameters for the metallic and composite face-sheet materials and the effective equivalent damage model for the orthotropic honeycomb core material. Good agreement was obtained between numerical and experimental results; in particular, the numerical simulation was able to predict impact damage area and the depth of indentation of honeycomb sandwich composite panels created by the impact loading.

Therapeutic results and safety of postoperative radiotherapy for keloid after repeated Cesarean section in immediate postpartum period

  • Kim, Ju-Ree;Lee, Sang-Hoon
    • Radiation Oncology Journal
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    • 제30권2호
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    • pp.49-52
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    • 2012
  • Purpose: To evaluate the effectiveness and safety of postoperative radiotherapy for the treatment of keloid scars administered immediately after Cesarean section. Materials and Methods: A total of 26 postpartum patients with confirmed keloids resulting from previous Cesarean sections received either 12 or 15 Gy radiotherapy. The radiotherapy was divided into three 6 MeV electron beam fractions administered during the postpartum period immediately following the final Cesarean section. To evaluate ovarian safety, designated doses of radiation were estimated at the calculated depth of the ovaries using a solid plate phantom and an ionization chamber with the same lead cutout as was used for the treatment of Cesarean section operative scars and a tissue equivalent bolus. Results: In total, the control rate was 77% (20 patients), while six (23%) developed focally elevated keloids (ranging from 0.5 to 2 cm in length) in the middle of the primary abdominal scar. Five patients experienced mild hyperpigmentation. Nonetheless, most patients (96%) were satisfied with the treatment results. The estimated percentage of the applied radiation doses that reached the calculated depth of the ovaries ranged from 0.0033% to 0.0062%. Conclusion: When administered during the immediate postpartum period, postoperative electron beam radiotherapy for repeated Cesarean section scars is generally safe and produces good cosmetic results with minimal toxicity.

Flexural ductility of prestressed concrete beams with unbonded tendons

  • Au, F.T.K.;Chan, K.H.E.;Kwan, A.K.H.;Du, J.S.
    • Computers and Concrete
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    • 제6권6호
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    • pp.451-472
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    • 2009
  • Based on a numerical method to analyse the full-range behaviour of prestressed concrete beams with unbonded tendons, parametric studies are carried out to investigate the influence of 11 parameters on the curvature ductility of unbonded prestressed concrete (UPC) beams. It is found that, among various parameters studied, the depth to prestressing tendons, depth to non-prestressed tension steel, partial prestressing ratio, yield strength of non-prestressed tension steel and concrete compressive strength have substantial effects on the curvature ductility. Although the curvature ductility of UPC beams is affected by a large number of factors, rather simple equations can be formulated for reasonably accurate estimation of curvature ductility. Conversion factors are introduced to cope with the difference in partial safety factors, shapes of equivalent stress blocks and the equations to predict the ultimate tendon stress in BS8110, EC2 and ACI318. The same equations can also be used to provide conservative estimates of ductility of UPC beams with compression steel.

Depth Map Using New Single Lens Stereo (단안렌즈 스테레오를 이용한 깊이 지도)

  • Changwun Ku;Junghee Jeon;Kim, Choongwon
    • Journal of the Korea Institute of Information and Communication Engineering
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    • 제4권5호
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    • pp.1157-1163
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    • 2000
  • In this paper, we present a novel and practical stereo vision system that uses only one camera and four mirrors placed in front of the camera. The equivalent of a stereo pair of images are formed as left and right halves of a single CCD image by using four mirrors placed in front of the ten of a CCD camera. An object arbitrary point in 3D space is transformed into two virtual points by the four mirrors. As in the conventional stereo system, the displacement between the two conjugate image points of the two virtual points is directly related to the depth of the object point. This system has the following advantages over traditional two camera stereo that identical system parameters, easy calibration and easy acquisition of stereo data.

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