• Title/Summary/Keyword: Ground loss

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An Experimental Study on the Factors Influencing on the Slump Loss of High Strength Concrete (고강도콘크리트의 유동성 손실에 영향을 미치는 요인에 대한 실험적 연구)

  • 문한영;김기형;문대중
    • Proceedings of the Korea Concrete Institute Conference
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    • 1992.10a
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    • pp.94-99
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    • 1992
  • In this study , some factors such as mix proportion, type and dosage of high range water reducing admixture(HRWR) and natural pozzolanas influencing on the slump loss of high strength concrete(H.S.C) using HRWR were investigated for reducing the slump loss. The acquired results indicated that the slump loss of H.S.C was affected according to cement content, sand percentage and type and dosage of HRWR and fly ash was superior to ground granulated blast furance slag in reducing the slump loss of H.S.C.

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Response Analysis of Block-Bearing Structure due to Tunnel Excavation in Clay Ground (점토지반에서 터널굴착에 따른 상부 블록구조물의 거동분석)

  • Son, Moorak
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.1
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    • pp.175-183
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    • 2014
  • This study investigates the response of structures to tunnelling-induced ground movements in clay ground, varying tunnel excavation condition (tunnel depth and diameter), tunnel construction condition (ground loss), and tunnel ground condition (soft clay and stiff clay). Four-story block-bearing structures have been used because the structures can easily be characterized of the extent of damages with crack size and distribution. Numerical parametric studies have been used to investigate of the response of structures to varying tunnelling conditions. Numerical analysis has been conducted using Discrete Element Method (DEM) to have real cracks when the shear and tensile stress exceed the maximum shear and tensile strength. The results of structure responses from various parametric studies have been integrated to consider tunnel excavation condition, tunnel construction condition, and tunnel ground condition and provide a relationship chart among them. Using the chart, the response of structures to tunnelling can easily be evaluated in practice in clay ground.

A CASE STUDY OF GROUND CAVE-IN DUE TO SUBSURFACE EROSION IN OLD LAND FILL

  • Kuwano, Reiko;Kohata, Yukihiro
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.09c
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    • pp.113-116
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    • 2010
  • Ground cave-in is usually initiated by the formation of cavity within the ground due to soil loss. When the location of the cavity is deep in the ground, the detection of the cavity is not easy. Then it is possible that the hidden cavity expands for a long time to eventually cause sudden large-scale collapse. A case of large scale ground collapse in the old fill ground was studied and described in this paper. The underground cavity appeared to be caused by subsurface erosion deep in the ground and to expand/extend upward till it was ended by the catastrophic ground failure. It highlighted the importance of proper drainage work in a large scale land fill.

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DIVERSITY DESIGN FOR SENSOR DATA ACQUISITION AT COMS SOC

  • Park, Durk-Jong;Koo, In-Hoi;Ahn, Sang-Il
    • Proceedings of the KSRS Conference
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    • 2007.10a
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    • pp.479-481
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    • 2007
  • COMS will transmit its observed data, Sensor Data, through L-Band with linear polarization. To avoid link loss caused by polarization discrepancy between satellite and SOC DATS, the L-Band antenna at SOC DATS should be linearly polarized. However, SOC DATS is supposed to share single antenna with SOC TTC, so the antenna should be circularly polarized. To cope with about 3dB loss, SOC DATS is designed to receive Sensor Data through two orthogonal circular polarizations, RHCP (Right-Hand Circular Polarization) and LHCP (Left-Hand Circular Polarization). Eventually, SOC DATS can obtain 2.6dB of combining gain through diversity combiner in MODEM/BB. This paper presents the verification on the diversity combining of SOC DATS with test configuration and results in depth.

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A Study for DPDT Switch Design with Defected Ground Structure (DGS 구조를 이용한 DPDT 스위치 설계에 관한 연구)

  • An Ka-Ram;Jeoung Myeung-Sub;Lim Jae-Bong;Cho Hong-Goo;Park Jun-Seok
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.54 no.3
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    • pp.132-138
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    • 2005
  • In this paper a DPDT(Double-Pole Double Through) switch with defected ground structure(DGS) is proposed. The equivalent circuit for the proposed switch structure is derived according to based on equivalent circuit of proposed DGS unit structure. The equivalent circuit parameters of DGS unit are extracted by using the circuit analysis method. The on/off operation of the proposed switch is obtained by varying the capacitance of the varactor diode at the defected ground plane. In the case of ON state, the insertion loss of the fabricated DPDT was shown under 1dB. And in OFF state, we found the rejection characteristic over 20dB at the designed frequency 2.45GHz. The experimental results show excellent insertion loss at on state and isolation at off state.

The Fluid Loss and Sealing Mechanisms in Slurry Trench Condition (II) : Finite Element Models of Fluid Loss for a Slurry Trench (Slurry wall 공법에서 안정액의 역할 (II) : 유한요소해석법 적용)

  • Kim, Hak-Moon
    • Journal of the Korean Geotechnical Society
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    • v.18 no.4
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    • pp.249-256
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    • 2002
  • The stability of slurry trench system is closely associated with the characteristics of the filter cake (assumed impervious membrane) transferring the hydrostatic force of slurry to the trench walls. The effectiveness of this assumption in a wide range of trench systems has been examined with the aid of a Finite Element program. Build up of excess porewater pressure in the soil mass behind the filter cake is a function of the slurry density, the properties of filter cake, the ground conditions, time, the geometry of trench and the original ground water level. These factors were all investigated by the Finite Element Method. The most significant factors were found to be the ground conditions and the properties of filter cake.

Analysis of Electrical Performance on Probe Pin (프로브 핀의 전기적 성능 분석)

  • Kim, Moonjung
    • Journal of Software Assessment and Valuation
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    • v.15 no.1
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    • pp.109-114
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    • 2019
  • In this paper, simulations of S-parameter and characteristic impedance for the probe pin are performed and its high-frequency performance is analyzed. The probe pins are arranged with one signal pin in the center and four ground pins on the top, bottom, left and right sides. The insertion loss and return loss of the probe pin are calculated while increasing the separation between the probe pins to 0.35 mm, 0.40 mm, and 0.50 mm, respectively. It is confirmed that the probe pin has different features of the insertion loss due to its periodic resonance phenomenon. Effect of the characteristic impedance on pitch and assignment of the probe pin is also analyzed. It is verified that there are a number of ground pins whose characteristic impedance is close to 50 Ω.

A Study on Surface Settlement Prediction Method of Trenchless Technology Pipe Jacking Method (비개착 강관압입공법의 지표침하 예측방법 연구)

  • Chung, Jeeseung;Lee, Gyuyoung
    • Journal of the Korean GEO-environmental Society
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    • v.16 no.11
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    • pp.29-37
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    • 2015
  • Non-excavation method is needed to secure the stability of existing structures during construction. Therefore, prediction of ground settlement is essential. Causes of settlement when using steel pipe indentation method are leading pipe-steel pipe gap, excessive excavation and soil-steel pipe friction etc. Also they are similar to the causes of settlement when using Shield TBM during construction. In this study, ground settlement during steel pipe indentation is predicted by the Gap Parameter Method and Volume Loss Method which are kinds of Shield TBM prediction Method. and compared with those of prediction methods by conducting field test. As a result, Volume Loss Prediction Method is the most similar to the field tests. However, It is needed to additional studies, such as decision of the factors and adaptability for total settlement predictions of non-excavation method.

Development of the Seepage Flow Monitoring Method by the Hydraulic Head Loss Rate (수두손실률에 의한 침투류 감시기법 개발)

  • Eam, Sung-Hoon;Kang, Byung-Yoon;Kim, Ki-Wan;Koo, Ja-Ho;Kang, Shin-Ik;Cha, Hung-Youn;Jung, Jae-Hyun;Cho, Jun-Ho;Kim, Ki-Soo
    • Journal of the Korean Geotechnical Society
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    • v.26 no.5
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    • pp.37-48
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    • 2010
  • In this study, the seepage flow monitoring method by the hydraulic head loss rate was developed for the purpose of application to offshore construction site enclosed by cofferdams in which seepage force varies periodically. The amount of the hydraulic head loss rate newly defined in this graph was in a range between 0 and 1. The zero of the rate means the existence of flow with no seepage resistance. The 1 of the rate means no seepage flow through the ground. The closer to 1 the coefficient of determinant in the hydraulic head loss graph is, the more the ground through which seepage water flows is stable. The closer to 0 the coefficient of determinant in the hydraulic head loss graph is, the more the ground through which seepage water flows was unstable and the higher the possibilities of existence of empty space or of occurrence of piping on the seepage flow pass in the ground is. The hydraulic head loss graph makes it possible to monitor sensitively the situation of seepage flow state, and the graph helps to understand easily the seepage flow state at the specific section on the whole cofferdam.

Characteristics of the Soil Erosion with the Rainfall and Geotechnical Conditions (강우 및 지반조건에 따른 토양침식 특성)

  • Lee, Myung-Gu;Song, Chang-Seob
    • Journal of The Korean Society of Agricultural Engineers
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    • v.53 no.3
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    • pp.53-58
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    • 2011
  • This study is analyzed the characteristics of the soil erosion with the geotechnical conditions and rainfall conditions, such as the ground slope, the compaction ratio, rainfall intensity and duration of rainfall etc. To this ends, a series of model test are conducted on clayey sands. From the results, the variation of soil loss is analyzed with the geotechnical and the rainfall conditions. The amount of soil loss is decreased as the increase of compaction ratio and is increased as the ground slope, rainfall intensity and the duration of rainfall.