• Journal of Biosystems Engineering
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• v.26 no.3
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• pp.245-252
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• 2001

This study was carried out to investigate the effect of three factors(dynamic load, inflation pressure and multiple passes of the tire) on the contact pressure and the soil stresses under the tire. A series of soil bin experiment was conducted with a 6.00R14 radial-ply tire for sandy loam soil. Tire contact pressure at soil surface and soil stresses at 10cm and 20cm soil depth were measured for the three levels of dynamic load(1.17kN, 2.35kN and 3.53kN), for the three levels of tire inflation pressure(103.42kPa, 206.84kPa and 413.69kPa), and for five different number of passes(1, 2, 3, 4 and 5 pass). The following results were drawn from this study 1) As dynamic load, inflation pressure and number of passes of the tire increased, tire contact pressure at soil surface and soil stresses at 10cm and 20cm soil depth increased accordingly. Thus increased in dynamic load, inflation pressure and number of passes of the tire would increase soil compaction. 2) The effect of three different factors, or dynamic load, inflation pressure and number of passes of the tire, decreased as the soil depth increase. Consequently, it was found that the soil compaction at a shallow depth in soil is larger than that at deep place in soil. 3) The increase of dynamic load and number of passes increased soil stress exponentially, but the increase of inflation pressure increased soil stress linearly. The effect of tire inflation pressure on soil stress was relatively less than that of the dynamic load. Therefore, it was concluded that dynamic load is more important factor affecting soil compaction in comparison to the inflation pressure of tire.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.1
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• pp.1-8
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• 1992

A method analizing contact pressure between plate and elastic half space is presented by using F.E.M. With the method, the pressure intensities at surface nodes of half space cae be directly calculated by using flexibility matrix of half space. The method is originally presented by Y.K. Cheung et al.(3) Insted of Y.K. Cheung's method, which use a conception of equi-contact pressure area around each surface nodes of half space in the noded rectanqular element area. We use the equi-contact pressure area around the Gaussian integration points of half space surface in the noded isoparametric element area. Numarical examples are presented and compared with other's studies.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.7
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• pp.619-626
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• 2007

The analysis of the frictional energy of the rubber block with contact to the surface is necessary to study the wear for rubber. It is important to define the relationship of the frictional energy and wear, as the most theory of the wear of rubber product is based on the frictional energy of rubber block. To predict the life of the rubber block, the most of research has been focused on the use of the finite element analysis or the actual experiments which need the many time and expensive costs.Therefore, this research is achieved the successful results of the analysis to the frictional energy by analytic method. This frictional energy is function of the material properties, the shape of block, the vertical and horizontal load and the block moving speed. The analytical results are compared with the test results of this paper which can be used for the analysis of the friction behavior for the wear estimation of the rubber products.

• Journal of the Korean Geosynthetics Society
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• v.14 no.1
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• pp.33-41
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• 2015

In this study, laboratory tests (flow, unit weight, unconfined compressive strength and bleeding tests) were performed to evaluate engineering properties of treated soil to improve pipe mixing method. As result, flow and bleeding properties are proportional to the water contents. The unit weight and unconfined compressive strength is decreased as the water contents increased. Comparing equipments contact pressure with bearing capacity of the mixed soil for dozer, backhoe and belt conveyor are immediately appliable. The applicable water content range is estimated from 80% to 200% by pipe mixing method using cement. Also, The design chart is developed from the results.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.4
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• pp.91-102
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• 1987

In this study, the finite element method using 8-node isoparametric element is developed theoretically and simulated to see the deformation of soil and plate, when the circular plate resting on Boussinesq's soil type is loaded axisymmetrically. The results of numerical analysis using the Mohr-Coulomb yield criterion, and experimental analysis are approximative, assuming that soil is elasto-plastic medium. The paper shows that the plastic zone of soil medium is displayed at the near the edge of plate at the first place; when the plastic zone of soil medium is linked around central axis, the external load is termed by critical load, and then the contact pressure changes abruptly, in this case it is approved to be the risk of shear failure.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.6
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• pp.546-555
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• 2001

In this paper filtering techniques to reduce the adverse effects of motor leads on high-frequency PWM inverter fed AC motor drives are presented. The filter was designed to keep the motor terminal from the cable surge impedance to reduce overvoltage reflections ringing and the dv/dt, di/dt, at the motor terminals. Specially the output filter is used to limit the rate of the inverter output voltage and reduce common mode noise to the motor, The performance of the output filter is evaluated through simulations and experiment on PWM inverter-fed AC motor drive. An experimental PWM drive system reduction of conducted EMI was implemented on an available TMS320C31 microprocessor control board Finally, experimental result shows inverter output filter reduces more common mode voltage than low pass filter also reduce overoltage and ringing at the motor terminal.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.99-99
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• 2010

최근 집속이온빔을 이용한 미세회로 교정, MEMS 공정 및 이온 도핑 등에 대한 연구개발이 활발히 이루어지고 있다. 기존에 널리 사용되었던 액체 금속 이온 소스의 경우 비교적 큰 angular divergence 및 Ga 이온 소스에 의한 오염이 문제시 되고 있어 이를 대체할 수 있는 가스 이온 소스에 대한 연구를 진행하였다. 본 연구에서 사용된 가스 이온 소스는 2 turn 안테나(1/4 inch Cu tube)가 감긴 반경 4 cm 석영관 내부에 Ar 가스를 주입 후 RF(13.56MHz)-ICP 타입 방전을 이용하였다. 운전 압력은 $10^{-5}\;Torr$ 범위이며 인가된 RF 전력은 최대 150 W이다. 석영관 내 발생된 플라즈마로부터 Ar 이온을 인출하기 위해 2단 인출 전극 구조가 사용되었으며 상단 전극에 고전압이 인가되고 하단 전극이 접지되는 형태이다. 2단 인출 전극의 최대 인출 전압은 10 kV, 상단 및 하단 전극의 구멍 크기는 각각 0.3 mm, 2 mm이다. 이온빔의 퍼짐을 최소화하기 위해 전극 간 공간 내 이온 거동 전산모사를 통해 전극 구조를 설계하였으며 이를 통해 최대 $30\;mA/cm^2$의 이온 전류 밀도 값을 얻을 수 있었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.399-409
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• 2018

The mechanically stabilized earth wall (MSEW) of the IPM bridge is an important structure that constitutes the bridge, and supports the horizontal earth pressure and approach slab. Therefore, it is necessary to carefully analyze the settlement of MSEW of the IPM bridge. This study examined the settlement according to the height and ground stiffness on the MSEW on the IPM Bridge. According to the design guideline, the IPM Bridge (2016) was designed to have a height of 4.0 ~ 10.0m and the elastic settlement was calculated. The base area and the grounding pressure of the MSE wall increased linearly with the height, and the elastic settlement also increased linearly. In addition, the stiffness of the foundations satisfying the allowable settlement of the approach slab is a N value of 35 or more. The settlement of finite element analysis was estimated to be smaller than the elastic settlement, and the stiffness of the foundation ground satisfied the allowable settlement of the approach slab above N value of 20. Because the elastic settlement of the MSEW of the IPM Bridge was overestimated, it will be necessary to examine it carefully by finite element analysis.

• Journal of Biomedical Engineering Research
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• v.25 no.5
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• pp.335-342
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• 2004

This paper describes a trans-admittance scanner for breast cancer detection. A FPGA-based sinusoidal waveform generator produces a constant voltage. The voltage is applied between a hand-held electrode and a scan probe placed on the breast. The scan probe contains an 8x8 array of electrodes that are kept at the ground potential. Multi-channel precision digital ammeters using the phase-sensitive demodulation technique were developed to measure the exit current from each electrode in the array. Different regions of the breast are scanned by moving the probe on the breast. We could get trans-admittance images of resistor and saline phantoms with an anomaly inside. The images provided the information on the depth and location of the anomaly. In future studies, we need to improve the accuracy through a better calibration method. We plan to test the scanner's ability to detect a cancer lesion inside the human breast.

• International Journal of Highway Engineering
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• v.8 no.3 s.29
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• pp.143-153
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• 2006

The differences in the stress distribution and the critical stresses in concrete pavement systems were analyzed when the dual-wheel single-, tandem-, and tridem-axle loads were applied at the interior and the edge of the pavement. The effects of the concrete elastic modulus, slab thickness, foundation stiffness, and tire contact pressure were investigated. The stresses under the interior loads were calculated using the transformed field domain analysis and stresses under the edge loads were obtained using the finite element method. The critical stresses under the interior and the edge loads were compared with respect to various parameters and the equations to predict the ratio between the stresses under the edge and the interior loads were developed and verified. From this study, it was found that the trends of the changes in the critical concrete stresses under the interior and the edge loads were very similar and the critical stress locations under those loads were identical. The critical stress ratio, which was obtained by dividing the critical stress under the edge loads into that under the interior loads, decreased with increasing the number of axles. That ratio became larger as the concrete elastic modulus increased, the slab thickness increased, the foundation stiffness decreased, and the tire contact pressure increased.