• Title/Summary/Keyword: Section technique

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Development of technique for slope hazards prediction using decision tree model (의사결정나무모형을 이용한 급경사지재해 예측기법 개발)

  • Song, Young-Suk;Cho, Yong-Chan;Chae, Byung-Gon
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.09a
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    • pp.233-242
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    • 2009
  • Based on the data obtained from field investigation and soil testing to slope hazards occurrence section and non-occurrence section in crystalline rocks like gneiss, granite, and so on, a prediction model was developed by the use of a decision tree model. The classification standard of the selected prediction model is composed of the slope angle, the coefficient of permeability and the void ratio in the order. The computer program, SHAPP ver. 1.0 for prediction of slope hazards around an important national facilities using GIS technique and the developed model. To prove the developed prediction model and the computer program, the field data surveyed from Jumunjin, Gangneung city were compared with the prediction result in the same site. As the result of comparison, the real occurrence location of slope hazards was similar to the predicted section. Through the continuous study, the accuracy about prediction result of slope hazards will be upgraded and the computer program will be commonly used in practical.

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Switching Component for Broadband Switching Network (광대역 스위칭 네트워크용 스위칭 소자 구조)

  • Kim, D.H.;Seo, W.S.;Sim, C.S.
    • Proceedings of the KIEE Conference
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    • 1987.07b
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    • pp.978-980
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    • 1987
  • This paper presents a scheme of $16{\times}16$ VLSI crosspoint chip as a key Component in future broadband switching network operating at bit rates UP to 140Mbit/s using space division switching technique. First, functional requirements of the chip are investigated in terms of a large switching unit. Then, a regeneration circuit to provide reshaping of previsiously switched signals is presented.

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Optimization Inverse Design Technique for Fluid Machinery Impellers (유체기계 임펠러의 최적 역설계 기법)

  • Kim J. S.;Park W. G.
    • Journal of computational fluids engineering
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    • v.3 no.1
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    • pp.37-45
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    • 1998
  • A new and efficient inverse design method based on the numerical optimization technique has been developed. The 2-D incompressible Navier-Stokes equations are solved for obtaining the objective functions and coupled with the optimization procedure to perform the inverse design. The steepest descent and the conjugate gradient method have been applied to find the searching direction. The golden section method was applied to compute the design variable intervals. It has been found that the airfoil and the pump impellers are well converged to their targeting shapes.

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Flow Survey around Two-Dimensional Circular Cylinder using PIV Technique (PIV를 사용한 2차원 원형 실린더 주위의 유동해석)

  • 박건선;곽영기
    • Journal of Ocean Engineering and Technology
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    • v.18 no.3
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    • pp.1-7
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    • 2004
  • Flaw visualization and velocity field measurement methods have practical applications in the various fluid engineering fields, such as mechanics, ships, and heat fluids. In this study, the basic principles and theoretical methods are used to establish an application technique of Particle Imae Velocimetry(abbreviated to PIV below). Accordingly, the measured results of velocity field distribution of a section inside the Circulating Water Channel (abbreviated to CWC below) are computed using the PIV is presented. The uniformity of velocity distribution of the section in CWC is confirmed, by comparing this PIV data with the existing current meter data. Also, in order to measure the flaw fields of surroundings of 2-dimensional cylinder in the CWC, the flaw visualization technique using the PIV is applied.

Preform Design for Forging of a PIM Connecting Rod (소결분말 콘넥팅로드 단조의 예비성형체 설계)

  • 박종진
    • Journal of Powder Materials
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    • v.2 no.1
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    • pp.19-28
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    • 1995
  • Powder forging is a combined technology of powder metallurgy and precision hot forging. Recently, the technology is developing rapidly because of its economic merits, especially in automotive part manufacturing. In the present study, the finite element technique was developed to predict density variation during P/M forging and the technique was applied to analysis of forging of a P/M connecting rod. Although deformation mode of the connecting rod was quite complex, several sections were selected and analyzed under an assumption of asymmetric or plane strain deformation. It was found that some modifications were necessary on the cross section of the beam portion. Therefore, the cross section was modified repeatedly until a satisfactory result of the analysis was obtained. On the other hand, no modifications were necessary in the ring and the pin portions. It is anticipated that the developed technique can be used to optimize preform design and manufacturing processes in P/M forging, which are highly critical to produce successful products in practice.

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Lateral Drift Control and Resizing Technique for Tall Buildings using Lateral-Stiffness Influence Matrix (횡강성 영향행렬을 이용한 고층건물의 횡변위 제어 및 단면 재산정 방안)

  • 이한주;김치경;김호수
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.15 no.2
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    • pp.271-279
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    • 2002
  • This study develops the module to find the lateral stiffness influence matrix of each story and performs the displacement sensitivity analysis by virtual load method for the efficiency of optimal design using lateral stiffness influence matrix. Also, resizing technique based on the estimated lateral stiffness increment factors is developed to apply directly the results of optimal design. To this end, resizing technique is divided into the continuous and discrete section design methods. And then the relationships between section properties and section size are established. Specifically, an initial design under strength constraints is first performed, and then the lateral load resistant system is designed to control lateral displacements yet exceeding the drift criteria. Two types of 45-story three dimensional structures we presented to illustrate the features of the lateral drift control and resizing technique for tall buildings proposed in this study.

Application of Optimum Design Technique in Determining the Coefficient of Consolidation Using Piezocone Test (피에조 콘 시험을 이용정회원, 한국과학기술원 토목공학과 부교수, 정회원, 한국과학기술원 토목공학과 박사 후 과정한 망일계수 결정시 최적화 기법의 적용)

  • Kim, Yeong-Sang;Lee, Seung-Rae;Kim, Yun-Tae
    • Geotechnical Engineering
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    • v.13 no.4
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    • pp.95-108
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    • 1997
  • For normally consolidated clay, several researchers have developed a number of theoretical time factors to determine the coefficient of consolidation However, depending on the assumptions and analytical techniques, it could considerably vary even for a specific degree of consolidation. In this paper, a method is proposed to determine a consistent coefficient of consolidation over all ranges of degree of consolidation by applying the concept of the Optimum Design Technique. The initial excess pore pressure distribution is assumed to be obtainable by the successive spherical cavity expansion theory. The dissipation of pore pressure is simulated by means of two dimensional linear-uncoupled axisymmetric consolidation analysis. The minimization of the differences between the measured and the predicted excess pore pressures was carried by BFGS unconstrained optimum design algorithm with one dimensional golden section search technique. By analyzing numerical and real field examples, it can be found that the adopted optimum technique gives a consistent and convergent results.

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Experimental Study on the Precast Concrete Joint using Re-bar Debonding and Cutting Technique (철근 비부착 및 절단 기법을 사용한 PC 접합부의 실험적 연구)

  • Yi, Waon-Ho;Moon, Jung-Ho;Lee, Yong-Jae;Lee, Han-Jun
    • Journal of the Korean Society of Hazard Mitigation
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    • v.2 no.4 s.7
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    • pp.131-141
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    • 2002
  • Precast concrete (PC) panels are often used as retaining walls to support soil pressure. In such a case, the panels should be connected at the location where PC panels meet with a buttress. However, it is not easy to provide enough development length for the reinforcing steels due to the limited width of the buttress. If it happens, the width of buttress should be increased as large enough although it is not desirable. The critical section required for providing the development length is always located where the flexural moment is maximum. Thus it is the place the buttress width ends. Also it is the place that the reinforcing steels stressed to maximum. However, it is possible to make differentiate between the maximum moment location and the most stressed location of reinforcing steels. It means that the most stressed location of reinforcing steels, the critical section, can be moved to the other place where the moment is not maximum. New critical location will have less moment than that of buttress width ends. In consequence, the development length would be longer than that of the typical way of construction. Debonding or cutting technique make it possible to reduce the moment strength of a section. Therefore reinforcing steels are debonded or cut to have a desired flexural strength at a desired place. In this study, five test specimens in full scale were erected to examine the effects of critical section movement in PC panel joints. Test parameters were the length variations of debonded and cut reinforcing steels. The test results showed that the debonding or cutting technique could be used to lengthen the development length in the joint of PC panels.

Programmed-release intraosseus anesthesia as an alternative to lower alveolar nerve block in lower third molar extraction: a randomized clinical trial

  • Pol, Renato;Ruggiero, Tiziana;Bezzi, Marta;Camisassa, Davide;Carossa, Stefano
    • Journal of Dental Anesthesia and Pain Medicine
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    • v.22 no.3
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    • pp.217-226
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    • 2022
  • Background: Intraosseous anesthesia is the process by which an anesthetic solution, after penetration of the cortical bone, is directly injected into the spongiosa of the alveolar bone supporting the tooth. This study aimed to compare the effectiveness of the traditional inferior alveolar nerve block (IANB) and computerized intraosseous anesthesia in the surgical extraction of impacted lower third molars, compare their side effects systemically by monitoring heart rate, and assess patients' a posteriori preference of one technique over the other. Methods: Thirty-nine patients with bilaterally impacted third molars participated in this study. Each patient in the sample was both a case and control, where the conventional technique was randomly assigned to one side (group 1) and the alternative method to the contralateral side (group 2). Results: The traditional technique was faster in execution than anesthesia delivered via electronic syringe, which took 3 min to be administered. However, it was necessary to wait for an average of 6 ± 4 min from the execution to achieve the onset of IANB, while the latency of intraosseous anesthesia was zero. Vincent's sign and lingual nerve anesthesia occurred in 100% of cases in group 1. In group 2, Vincent's sign was recorded in 13% of cases and lingual anesthesia in four cases. The average duration of the perceived anesthetic effect was 192 ± 68 min in group 1 and 127 ± 75 min in group 2 (P < 0.001). The difference between the heart rate of group 1 and group 2 was statistically significant. During infiltration in group 1, heartbeat frequency increased by 5 ± 13 beats per minute, while in group 2, it increased by 22 ± 10 beats per minute (P < 0.001). No postoperative complications were reported for either technique. Patients showed a preference of 67% for the alternative technique and 20% for the traditional, and 13% of patients were indifferent. Conclusion: The results identified intraosseous anesthesia as a valid alternative to conventional anesthesia in impacted lower third molar extraction.

Identification of flutter derivatives of bridge decks using stochastic search technique

  • Chen, Ai-Rong;Xu, Fu-You;Ma, Ru-Jin
    • Wind and Structures
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    • v.9 no.6
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    • pp.441-455
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    • 2006
  • A more applicable optimization model for extracting flutter derivatives of bridge decks is presented, which is suitable for time-varying weights for fitting errors and different lengths of vertical bending and torsional free vibration data. A stochastic search technique for searching the optimal solution of optimization problem is developed, which is more convenient in understanding and programming than the alternate iteration technique, and testified to be a valid and efficient method using two numerical examples. On the basis of the section model test of Sutong Bridge deck, the flutter derivatives are extracted by the stochastic search technique, and compared with the identification results using the modified least-square method. The Empirical Mode Decomposition method is employed to eliminate noise, trends and zero excursion of the collected free vibration data of vertical bending and torsional motion, by which the identification precision of flutter derivatives is improved.