• Title, Summary, Keyword: bearing area

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The Friction Characteristics on the Loosening of Bolted Joints (볼트 결합부 풀림에 관한 마찰 특성)

  • Park, Tae-Won;Shin, Gwi-Su;Jiang, Yanyao
    • Journal of the Korean Society of Safety
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    • v.19 no.1
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    • pp.12-17
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    • 2004
  • By using an experimental approach recently developed to determine the torque-tension relationship for bearing frictional characteristics of several typical bolted joints were studied. The experimental approach allows the direct determination of the bearing friction between the nut and its bearing surface. Detailed friction studies were made on the influences of the size and shape of the hole, the use of a slot in a bolted joint, contact area and position, and other factors such as turning speed, coating, and the use of wax on the bearing surface. The contact area and position of the washer have a marginal effect on the bearing friction. The organic coating on the nuts reduces the bearing friction significantly. Nuts with organic coating over a washer with zinc finish provide the smallest and the most consistent bearing friction. The results from the experimental investigation will be helpful for the better design of bolted joints bearing friction. The results from the experimental investigation Will be helpful for the better design of bolted joints.

Experiment on the Effective Helix Area to Determine the Bearing Capacity of Helical Steel Piles (나선형 강관파일의 날개 유효면적 산정을 위한 지지력 실험)

  • Lee, Min-Joo;Kim, Kyoung-Min;Rhim, Hong-Chul;Seo, Gum-Bae
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.25-27
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    • 2010
  • Helical steel piles are being widely used in foundation for the buildings in urban areas because of their high compressive and tensile capacities. Helical steel piles have many advantages; ease installation, a vibration-free and low level of noise process, and so on. However, the most researches are about the capacity of helical steel piles under uplift condition. Therefore, this paper focuses on the capacity under compressive loading according to the soil condition. The bearing capacity of helical steel piles varies with the diameter of the helix and shaft and the bearing area of helical steel piles is not always identical with the sum of helix and shaft area due to the difference of each bearing mechanism. Therefore, the experiment with the parameters of the ratio of helix and shaft diameter and soil condition will be carried out to survey the effective helix area under a given soil condition for the bearing capacity of helical steel piles.

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Analysis for Bearing Capacity of Basalt by Vesicle Area Ratio (현무암 기공면적에 따른 지지력분석)

  • Nam, Kwan-Woo;Kim, Sang-Ho;Kim, Ju-Tae;Park, Gun-Soo;Seo, Seok-Hyun
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.1001-1010
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    • 2009
  • The study that unconfined compression strength of intact rock which is the most important factor to determine the bearing capacity effects discontinuities in rock mass has been carried out actively so far. However, the study which is related to lithological characters such as vesicle which is one of the primary characteristics of Basalt has barely been conducted. On this study, We have analyzed the correlation-ship between vesicle and unconfined compression strength and the effect on the bearing capacity, based on the reviewing on the changes of unconfined compression strength as the amount of vesicle of Basalt. It is impossible to analyze the amount of vesicle of Basalt as measuring unit. So it was analyzed by the ratio of the core sample's surface area and another area that vesicle takes up. Also, unconfined compression strength was calculated by point load test and unconfined compression strength test. The analysis shows that vesicle area ratio and unconfined compression strength have the exponential relationship and vesicle area ration is the factor to determine the bearing capacity of Basalt. It is considered that the reliability of calculating of the bearing capacity of Basalt will be improved as we study the correlation-ship between the vesicle area ratio and rock mass grade hereafter.

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Bearing Capacity and Settlement Characteristics of Weathered Granite Masses in Gyeonggi Area (경기지역 화강 풍화암반의 지지력 및 침하특성에 관한 연구)

  • Kim, Dong-Eun;Huh, Kyung-Han
    • Journal of the Korean Society of Hazard Mitigation
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    • v.5 no.4
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    • pp.37-47
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    • 2005
  • The purpose of this study is to estimate the bearing capacity and settlement characteristics of the weathered granite masses, and on the process to achieve the purpose, in the first place, the weathered degree according to the absorption index was examined and reviewed, then plate bearings test in in-situ depth were tested, and finally the result was compared and examined with the result of the existing, estimate method and pressuremeter test. In order to achieve the purpose of this study, a typical area distributed with weathered granite masses, gyeonggi area, was chosen as a sample site for testing, and in the result, it appeared and found out that the more the weathered degree increases when the plate bearing test are tested, the more the bearing capacity decreases a numerical indexes and the more greatly the width of the decrease of bearing capacity increases around the boundary of specific, weathered degrees. Also, In the result from estimating the bearing capacity of weathered granite masses by the existing, suggested formula, it appeared that there is a tendency that the more the weathered degree increases, the more similar the bearing capacity becomes with the result of plate bearing tests.

Geochemical Correlations Between Uranium and Other Components in U-bearing Formations of Ogcheon Belt (옥천대(沃川帶) 함(含)우라늄지층중(地層中)의 우라늄과 타성분(他成分)과의 상관관계(相關關係))

  • Lee, Min Sung;Chon, Hyo Taek
    • Economic and Environmental Geology
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    • v.13 no.4
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    • pp.241-246
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    • 1980
  • Some components in uranium-bearing formations which consist mainly of black shale, slate. and low grade coal-bearing formation of Ogcheon Belt were processed statistically in order to find out the geochemical correlations with uranium. Geochemical enrichment of uranium, vanadium and molybdenum in low grade coal-bearing formations and surrounding rocks is remarkable in the studied area. Geochemical correlation coefficient of uranium and molybdenum in the rocks displays about 0.6, and that of uranium and fixed carbon about 0.4. Uranium and vanadium in uranium-bearing low grade coals denote very high correlation with fixed carbon, which is considered to be responsible for enrichment of metallic elements, especially molybdenum. Close geochemical correlation of uranium-molybdenum couple in the rocks can be applied as a competent exploration guide to low grade uranium deposits of this area.

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A Model Test Study on the Bearing Capacity of the Crushed Stone Pile (쇄석말뚝의 지지력 특성에 관한 모형시험 연구)

  • 이상익;박용원;김병일;윤길림
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.299-306
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    • 2001
  • Crushed Stone Pile(CSP) is one of the ground improvement methods available to loose sand and clayey ground by forming compacted CSP in the weak soil layer. The effects of this method are enhancement of ground bearing capacity, reduction of settlement and prevention of lateral ground movement in cohesive layer, reduction of liquefaction potential in sandy ground. This study performs model tests in 1.0m${\times}$1.0m${\times}$1.0m and 1.5m${\times}$1.5m${\times}$l.2m model tank to observe bearing capacity of CSP treated ground. The area replacement ratio of CSP composite ground varies 20%, 30% and 40% with square grid pattern. After the composite ground was consolidated under pressure of 0.5kg/$\textrm{cm}^2$ and 1.0kg/$\textrm{cm}^2$, load tests were carried out. The results show that ultimate bearing capacity increases with area replacement ratio and the preconsolidation pressure of ground.

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Development of Design Method of Disconnected Piled Raft Foundation System (기초분리말뚝 공법의 설계기법 개발)

  • Choi, Jung-In;Min, Ki-Hoon;Kim, Sung-Ho;Kwon, Oh-Sung;Kim, Myoung-Mo
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.691-699
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    • 2008
  • In the design of a foundation, settlement of the foundation may exceed allowable design criteria even with a competent bearing stratum. In such a case, a piled-raft foundation system may be adopted using piles as settlement reducing component. In this paper, Disconnected Piled Raft Foundation (DPRF) system, which installs disconnected piles underneath the raft and uses the piles as ground reinforcements, is studied as a cost effective design method against the classical piled-raft foundation system. To this end, large size loading tests were carried out on weathered ground changing area replacement ratio and length of piles. The results indicated that the settlement of the reinforced ground was reduced by 34~87% and the allowable bearing pressure increased by 70% on average from those of the unreinforced original ground, respectively. The correlating formula between the area replacement ratio and the load bearing ratio of piles were derived from the test results and numerical analysis. From the correlation, a design method determining the size and the quantity of the disconnected piles to enhance the bearing capacity of original ground to the desired value was proposed based on one inch settlement criteria.

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ANALYSIS OF FLUID CHARACTERISTICS OF THRUST BEARING ON MILLIMETER-SCALE MICRO GAS TURBINE (초소형 가스 터빈용 스러스트 베어링 내의 유동특성 해석)

  • Seo, J.H.;Baek, J.H.
    • 한국전산유체공학회:학술대회논문집
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    • pp.258-262
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    • 2010
  • Since MEMS based micro actuators or generating devices showed high efficiency per volume, plenty of research are ongoing. Among them, MEMS based millimeter-scale micro gas turbine is one of the most powerful item for replacing chemical batteries. However, due to MEMS manufacturing technique, it is very difficult that makes wide turbine bearing area. It causes low DN number, so sufficient bearing force is hard to achieve. Thus, the most important issue on micro gas turbine is to design the proper bearing which can keep rotor stable during operation. In order to that, micro-scale gas-lubricated bearing is generally used. In this paper, basic feasibility study of thrust bearing of 10mm diameter turbine is described. Thrust bearing is hydrostatic gas-lubricated type. Numerical simulation is performed with ANSYS CFX 11.0 which is commercial numerical tool. Relationship between bearing inlet pressure and mass flow rate and bearing force is figured while changing bearing gap and number of capillaries. The simulation results will be used for further design of micro gas turbine.

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The Effects of Symmetrical Scapular Alignment on Weight Bearing of Hemiplegic Patients During Standing Position (편마비 환자의 견갑골 대칭적 정렬상태가 선 자세에서 체중부하지지율에 미치는 영향)

  • You, Young-Youl;Ann, Chang-Sik
    • The Journal of Korean Physical Therapy
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    • v.21 no.2
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    • pp.23-29
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    • 2009
  • Purpose: This study examined the effects of the symmetrical scapular alignment on the weight bearing of hemiplegic patients in the standing position. Methods: PALM (PALpation Meter) test and Gaitview AFA-50 were used to measure the skeletal alignment of the scapula and the weight bearing loaded on the affected and unaffected sides before and after training. The data was analyzed using a paired t-test on the SPSS 12.0 program for descriptive statistics. A p value <0.05 was considered significant. Results: The mean difference in the scapular alignments on sup. & mid. & inf. area in the hemiplegic side before and after training was $0.93\pm0.50cm$ and $0.58\pm0.43cm$, respectively. There was a significant decrease after training rather than that before (p<0.05). The mean weight bearing on the foot area in the hemiplegic patients before and after training was $9.12\pm5.51N/cm^2$ and $4.36\pm4.11N/cm^2$, respectively,. There was a significant decrease after training rather than that before (p<0.05). The scapuar alignments and weight bearing data on the standing position were grouped around the average (to central point) in the distribution graph. Conclusion: These findings suggest that the symmetrical scapular alignment can serve as an effective means of improving the weight bearing ability of hemiplegic patients.

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An Experimental Study on the Evaluation of Bearing Strength of the Vertical Joint in Precast Concrete Large Panel Structures (대형판 조립식 구조 수직접합부 지압강도 평가에 관한 연구)

  • Chung, Lan;Cho, Seung-Ho;Hwang, Min-Ha
    • Magazine of the Korea Concrete Institute
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    • v.8 no.4
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    • pp.181-189
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    • 1996
  • It is well-known that the hearing strength in vertical joints of precast concrete large panel system is affected by grout compressive strength angle of shear key and bearing area. 21 vertical joint specimens were tested to investigate the effects of these parameters The analysis of test results shows that : 1. The higher be grout compressive strength, the higher will shear strength be. And the bearing strength does not so increase in proportion of bearing area. 2. The shear key with the angle of $20^{\circ}$shows the highest bearing strength among three angle variables of $20^{\circ}$, $25^{\circ}$, $30^{\circ}$.