• Title/Summary/Keyword: Ground Condition

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The Comparision of the Static Balance, Contact Area, and Plantar Pressure of Flexible Flat Foot According to Elastic Taping

  • Hyeon-Seong Joo;Sam-Ho Park;Myung-Mo Lee
    • Physical Therapy Rehabilitation Science
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    • v.11 no.4
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    • pp.421-429
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    • 2022
  • Objective: The purpose of this study was to compare and analyze the effects of arch support taping on static balance, static/dynamic foot contact area, and ground reaction force during walking according to the types of elastic tapes with mechanical elasticity differences. Design: Cross-sectional study Methods: Twenty-six participants selected for flexible flat feet through the navicular drop test were randomly assigned to non-taping, Dynamic-taping, and Mechano-taping conditions. Static balance and foot contact area were compared in the standing posture according to arch support taping conditions, and foot contact area and ground reaction force were compared during walking. Results: There was no significant difference in static balance according to the taping condition in the standing position, but the foot contact area in the Mechano-taping condition showed a significant decrease compared to the non-taping condition (p<0.05). The foot contact area during walking significantly decreased in the Dynamic-taping and Mechano-taping conditions (p<0.05), but there was no significant difference between the ground reaction force. Conclusions: Based on the results of this study, it was confirmed that among the types of elastic taping, arch support taping using dynamic taping and Mechano-taping has the effect of supporting the arch with high elastic recovery. Any type of elastic tape can be used for arch alignment in flexible flat foot.

Measurement of Retaining Tensile Load with the Relative Displacement Detector of Ground Anchors (상대변위측정기를 이용한 지반앵커의 보유인장력 측정)

  • Jeong, Hyeon-Sik;Han, Kwang-Suk;Lee, Yeong-Saeng
    • Journal of the Korean Geotechnical Society
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    • v.33 no.10
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    • pp.59-69
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    • 2017
  • The tension load of the ground anchor inserted in the ground gradually changes over time. In this regard the change of the initial tension load is primarily decreased by the fixation condition of the fixing head and the mechanical characteristics of the tensile material. The subsequent additional tension load is a time-dependent loss mostly due to the fixing conditions of the bonded length and the surrounding ground properties of the field. In this paper, therefore, a measurement system using a relative displacement detector that can relatively easily measure the change of tension load is discussed. As a result of the review, it was confirmed that the results using the relative displacement detector are similar to those of the real scale model test, and it was also confirmed that similar results were obtained with the result of the pull-out test conducted on the ground anchors fixed to weathered rocks condition. In addition, a pull-out test was conducted on the test anchors whose initial tension load loss was relatively large and through this test pull-out behavior of the tension type ground anchors was verified.

An iterative boundary element method for a wing-in-ground effect

  • Kinaci, Omer Kemal
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.6 no.2
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    • pp.282-296
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    • 2014
  • In this paper, an iterative boundary element method (IBEM) was proposed to solve for a wing-in-ground (WIG) effect. IBEM is a fast and accurate method used in many different fields of engineering and in this work; it is applied to a fluid flow problem assessing a wing in ground proximity. The theory and the developed code are validated first with other methods and the obtained results with the proposed method are found to be encouraging. Then, time consumptions of the direct and iterative methods were contrasted to evaluate the efficiency of IBEM. It is found out that IBEM dominates direct BEM in terms of time consumption in all trials. The iterative method seems very useful for quick assessment of a wing in ground proximity condition. After all, a NACA6409 wing section in ground vicinity is solved with IBEM to evaluate the WIG effect.

Design of the Ground Resistance Measuring System to the Earth-Noise

  • Jung Min-Jae;Joo Hyung-Jun;Lee Ki-Hong;Oh Sung-Up;Jung Jae-Ki;Seong Se-Jin
    • Proceedings of the KIPE Conference
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    • 2001.10a
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    • pp.566-570
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    • 2001
  • Generally, grounding systems are responsible for the safe operation of a power system. Their performance guarantees equipment protection and personnel safety under condition of the limited ground potential rise and touch voltages as well as step voltages under ground fault conditions. Therefore, it is necessary to measure the ground resistance frequently for checking the performance of grounding system, In this paper the ground resistance measuring system using digital signal processor and high-performance L-C resonant band pass filter is presented. The signal current magnitude for measuring ground resistance in this system is $10^{-1}[A]\;to\;5\times10^{-2}[A]$ and the current frequency is 30[Hz].

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The Effect and the Limitation of Driven-right-leg Ground on Indirect-contact ECG measurement (간접접촉 심전도 측정에서의 오른발구동 접지의 효과와 한계)

  • Lim, Yong Gyu
    • Journal of Biomedical Engineering Research
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    • v.39 no.2
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    • pp.103-108
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    • 2018
  • This study reviews the common-mode noise model of indirect-contact ECG measurement which uses capacitive electrode and capacitive ground, and shows the reason of the large common-mode noise in indirect-contact ECG. And then, this study shows driven-right-leg ground in indirect-contact ECG measurement, and reviews how the driven-right-leg ground reduces the common-mode noise. This study then analyzes the relation between the effective area of the indirect-contact ground and the gain of the driven-right-leg circuit. This study introduces the output voltage saturation of the driven-right-leg circuit, which occurs frequently in indirect-contact ECG measurement with the condition of the high ground impedance. This study then shows the effect of the driven-right-leg circuit saturation on the common-mode noise.

A Study on the Shear Strength Characteristics of Composited Ground applying RAP Method by Large Direct Shear Test (대형직접전단시험에 의한 RAP 복합지반의 전단강도 특성 연구)

  • Chun, Byung-Sik;Seo, Deok-Dong;Kim, Jong-San
    • Proceedings of the Korean Geotechical Society Conference
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    • 2004.03b
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    • pp.82-89
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    • 2004
  • To secure stability and availability of Rammed Aggregate Pier method as the foundation of a structure, the shear strength characteristics according to the area replacement ratio of RAP and the relative density of in-situ ground was studied through soil laboratory tests and large direct shear tests in a model ground. As a result, the internal friction angle tends to increase in proportion to in-situ relative density(Very Loose, Loose, Medium) in composite ground formed by the same area replacement ratio of RAP and also increase in proportion to increasing the area replacement ratio(30, 40, 50%) of RAP in the same ground condition. Furthermore, the comparative analysis between the experimental value and theoretical value of the shear strength is carried out.

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NUMERICAL STUDY ON WIND TUNNEL GROUND PLATE WITH A PRESSURE CONTROL DEVICE (압력 조절 장치를 갖는 풍동 지면판에 관한 수치해석적 연구)

  • Lee, M.J.;Kim, C.W.
    • Journal of computational fluids engineering
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    • v.15 no.4
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    • pp.53-59
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    • 2010
  • Preliminary design of a ground plate, a device installed close to the aircraft model for wind tunnel test to simulate the ground effect, was performed by a numerical simulation. A two-dimensional numerical study was performed initially to decide the optimal leading edge and flap configurations. Then, three-dimensional studies were conducted to decide the optimal flap deflection angle for pressure distribution reduction since the plate and the plate supporting system generate static pressure difference between the upper and lower flow regions. Three-dimensional simulation additionally studied the effect of the clearance between the plate and the wind tunnel side wall. For the efficiency of computation, half model was simulated and a symmetric boundary condition was applied on the center plane. Based on the preliminary design, a ground plate was designed, manufactured and tested at the Korea Aerospace Research Institute(KARI) wind tunnel. The measured pressure differences versus flap deflection angle agreed well with the predicted results.

Evaluation of Stability about Lateral Soil Movement of Bridge Abutment Constructed on Soft Ground (연약지반 위에 시공되는 교대의 측방유동에 대한 안정성 평가)

  • Yoo, Nam-Jae;Kim, Dong-Gun;Jeon, Sang-Hyun
    • Journal of Industrial Technology
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    • v.30 no.B
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    • pp.25-32
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    • 2010
  • In this paper stability about lateral soil movement of bridge abutment constructed on the soft ground, reinforced with the sand compaction pile (SCP) and the preconsolidaton methods, was evaluated by using the centrifuge testing facility which stress conditions in field could be reconstructed in the laboratory. The layouts of model such as ground condition, sand compaction piles and abutment was determined on the basis of similitude law with the reduced scale of 1/200. Construction sequences of installing SCP, preparing reclaimed ground, preconsolidating ground and building the piled bridge abutment were reconstructed during centrifuge modelling and measurements of movement were followed in each sequence. From analyzing the results of measuring movements of the model abutment and the ground, measured lateral movement of model abutment was found to be within the allowable value so that stability of abutment against lateral sliding was secured.

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Frost Heaving in Artificial Ground Freezing

  • 생뢰효박
    • Proceedings of the Korean Geotechical Society Conference
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    • 1994.03b
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    • pp.13-46
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    • 1994
  • Artificial ground freezing methods have been applied to geotechnical construction projects for stabilizing earth materials and controlling water seepage into the ground. However, this can result in frost heaving and causes the same engineering problems as encountered with the natural freezing of soil. In natural freezing, the ground freezes from the surface downward. When artificial ground freezing is applied at a deep location, however, freezing is limited locally. The soil condition differs between them as follows: Natural freezing - unsaturated and without overburden pressure. Artificial freezing -- saturated and under overburden pressure. The authors investigated the practical application of artificial ground freezing and examined the frost behaviour of a saturated soil under overburden pressure. This paper presents the results obtained from experiments concerning frost heaving and discusses frost heaving at the freezing site.

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A Study on Development of a Ground-Source Heat Pump System Utilizing Pile Foundation of a Building (건물 기초를 이용한 지중열 공조시스템의 개발에 관한 연구 (2))

  • Ryozo, Ooka;Hwang, Suk-Ho;Kentaro, Sekine;Yosuke, Shimawaki;Nam, Yu-Jin
    • Proceedings of the SAREK Conference
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    • 2005.11a
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    • pp.155-160
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    • 2005
  • To purpose of this research is to develop the numerical model for simulating performance of ground heat exchanger with high prediction accuracy. This paper describes the development of a numerical model that simulates the heat transfer between ground and circulation water in ground heat exchanger. Furthermore, we propose the estimating technique of soil properties, such as thermal conductivity, heat capacity and hydraulic conductivity, based on ground investigation. Comparison between experiment and numerical analysis based on the model developed above was conducted under the condition of the experiment in 2004. The result of analysis agreed well with the experimental result.

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