• 한국지반환경공학회 논문집
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• 제8권3호
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• pp.19-25
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• 2007

쇄석말뚝은 느슨한 사질토지반이나 점토지반에 치환법에 의해 다져진 자갈이나 쇄석을 연약한 지반에 삽입하여 개량하는 공법이다. 쇄석말뚝 공법은 흙과 말뚝 접촉면에서 압밀거동이 다양한 인자에 의해 영향을 받게 되어 정량적인 해석에 많은 어려움이 있다. 본 연구에서는 재하시험을 통해 선단지지 군말뚝의 거동에 대한 다양한 인자의 영향을 조사하였다. 궁극적으로 연약지반의 개량 특성과 설계인자의 영향력을 PR값을 사용하여 평가하였다. 실험결과와 계산된 PR 값으로부터 쇄석말뚝의 침하거동이 근입비나 매트의 설치여부 보다는 말뚝의 직경이나 복합지반의 치환율에 의해 영향을 받고 있음을 알 수 있다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권1호
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• pp.7-15
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• 2015

We have investigated electrical properties of graphene/Ge Schottky barrier diode (SBD) fabricated on Ge film epitaxially grown on Si substrate. When decreasing temperature, barrier height decreased and ideality factor increased, implying their strong temperature dependency. From the conventional Richardson plot, Richardson constant was much less than the theoretical value for n-type Ge. Assuming Gaussian distribution of Schottky barrier height with mean Schottky barrier height and standard deviation, Richardson constant extracted from the modified Richardson plot was comparable to the theoretical value for n-type Ge. Thus, the abnormal temperature dependent Schottky behavior of graphene/Ge SBD could be associated with a considerable deviation from the ideal thermionic emission caused by Schottky barrier inhomogeneities.

• Journal of Computing Science and Engineering
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• 제5권2호
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• pp.121-130
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• 2011

Recent research indicates that transient errors will increasingly become a critical concern in microprocessor design. As embedded processors are widely used in reliability-critical or noisy environments, it is necessary to develop cost-effective fault-tolerant techniques to protect processors against transient errors. The register file is one of the critical components that can significantly affect microprocessor system reliability, since registers are typically accessed very frequently, and transient errors in registers can be easily propagated to functional units or the memory system, leading to silent data error (SDC) or system crash. This paper focuses on investigating the impact of register file soft errors on system reliability and developing cost-effective techniques to improve the register file immunity to soft errors. This paper proposes the register vulnerability factor (RVF) concept to characterize the probability that register transient errors can escape the register file and thus potentially affect system reliability. We propose an approach to compute the RVF based on register access patterns. In this paper, we also propose two compiler-directed techniques and a hybrid approach to improve register file reliability cost-effectively by lowering the RVF value. Our experiments indicate that on average, RVF can be reduced to 9.1% and 9.5% by the hyperblock-based instruction re-scheduling and the reliability-oriented register assignment respectively, which can potentially lower the reliability cost significantly, without sacrificing the register value integrity.

• 한국지반공학회논문집
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• 제16권2호
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• pp.115-123
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• 2000

Piezocone Penetration Test has been performed in the soft ground over the site preparation area at Inchon International Airport(IIA). With the pore pressure dissipation test results, the changes in the permeability and the coefficient of consolidation in clayey soil were checked and the differences of the undrained shear stength verified the soft ground improvement effect from vane test and piezocone test both before and after the improvement. From the results, thin sand seam was found and this caused a big difference in the coefficient of permeability and consolidation. The coefficient of consolidation was high in the upper marine deposit and relatively low in lower marine deposit. It was found that the reduction of void ratio by preloading resulted in the reduction of coefficient of consolidation after the ground improvement. In addition, there were some variations of undrained shear strength when the number of 15 or 18 was used as the coefficient of piezocone(Nkt). However, when the average value of undrained shear strength calculated using Nkt=10 was applied, the result indicated the similar average value with the result of vane test and the increasing rate of strength( Δsu/Δ$\sigma$≒0.38) also showed the similar distribution.

• 한국농공학회논문집
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• 제47권6호
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• pp.47-57
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• 2005

Stress distribution in soils is the very important element to design and to solve the problems of settlement, safety of foundations and trafficability of constructing vehicle in civil engineering. This research presents the comparative estimation of the actual and theoretical measurement on the underground stress of outer layer for each soil after the observation of each top soil layer fur its vertical and horizontal stresses in (1) homogeneous sand ground (2) weak stratum with the sand soil (3) weak stratum with gravel of the soil model, and it also investigates the effect of subsidence of ground by the repeated load. The underground stresses fumed out to be different in the value of theoretical and actual measurement after the trial examination of model. This study has the purpose of suggesting the better construction method of running equipment on weak stratum by comparing the estimated value of trial experiment and theory on underground stress of the weak ground surface area and of raising up the necessity of the continuous research hereafter.

• 소음진동
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• 제2권1호
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• pp.21-31
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• 1992

In the previous paper, we report a practical floor impact sound level prediction method for a heavyweight impact source(Tire), soft impact source such as children jumping and running. According to these results, the calculated value and the measured value correspond comparatively well, regardless of differences in the floor structures. And the floor impact sound for a heavyweight impact source, soft source was strongly influenced by structural factors such as floor slab stiffness and peripheral support conditions. But the floor impact sound for a light impact source (Tapping machine), hard impact source was influenced by resilient layers, composed of multi-layer in floor structures. Thus, In this paper, 4 actual floor structures, all with differing resilient layers, were calculated using impedance method. When these calculation values were compared with the measured values, approximately all the values fell with one rank of the sound insulation grade, reference curve(L curve) by the JIS standard. So, a sample of measured values and calculated values from floor structures is presented to show the accuracy and appropriateness of the impedance method in domestic.

• Journal of Power Electronics
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• 제18권1호
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• pp.45-55
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• 2018

It is usually difficult for dual-active-bridge (DAB) dc-dc converters to operate efficiently at light loads. This paper presents an in-depth analysis of a DAB with triple-phase-shift (TPS) control under the light load condition to overcome this problem. A kind of operating mode which is suitable for light load operation is analyzed in this paper. First, an analysis of the zero-voltage-switching (ZVS) constraints for the DAB converter has been carried out and a reasonable dead-band setting method has been proposed. Secondly, the basic operating characteristics of the converter are analyzed. Third, under the condition of satisfying the ZVS constraints, both the reactive power and the root mean square (RMS) value of the current are simultaneously minimized and a particle swarm optimization (PSO) algorithm is employed to analyze and solve this optimization problem. Lastly, both simulations and experiments are carried out to verify the effectiveness of the proposed method. The experimental results show that the converter can effectively achieve ZVS and improved efficiency.

• Applied Biological Chemistry
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• 제32권4호
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• pp.327-331
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• 1989

염소 처리량에 따른 박력분의 백도 및 pH 그리고 리올로지 특성에 미치는 영향에 대해 실험하였다. 염소 처리한 것과 무처리한 박력분의 표백의 정도는 처리량이 2 oz./cwt.까지 표백효과가 있었으나 그 이상부터는 표백효과가 없었고, pH는 처리량 증가에 따라 점차적으로 낮아졌다. Farinogram 특성에서 염소처리량 증가에 따라 흡수율과 반죽의 안정도가 높아진 반면에 MTI값은 감소하였으며, valorimeter value는 일정하지 않았다. Extensogram 특성에서 저항도, 최대저항도 및 신장저항도는 90분과 135분 동안 방치했을때 무처리한 것이 가장 컸으며, 처리량 1 os./cwt.인 것이 가장 낮았으나 2 oz./cwt. 처리의 경우 그 값이 다시 증가하는 경향을 나타냈다. Amylogram의 최고점도와 최고점도시 온도는 처리량 증가에 따라 점증적으로 상승하였으며, 특히 4 oz./cwt. 처리의 경우 최고 점도가 1,160BU로 급격히 상승하였다.

• 한국지반공학회논문집
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• 제15권6호
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• pp.57-69
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• 1999

오염된 연약지반에 편재하중이 작용하는 경우에 있어서 지반의 소성화에 따른 지지력 결정을 위하여 기존의 이론적인 배경을 고찰하고, 이러한 오염된 연약지반에서 편재하중에 의한 지반의 지지력과 변형에 대한 거동을 연구하기 위하여 모형실험을 통한 실측치를 이용하여 서로 비교.분석하였다. 모형실험은 모형 재하장치인 토조와 재하틀 및 재하판을 제작하여 토조안에 함수비를 일정하게 유지한 상태에서 자연지반의 시료와 오염물질을 점진적으로 증가시킨 지반시료에 일정한 시간간격으로 편재하중을 증가시키면서 침하량과 측방변위량 및 융기량 등을 관찰하였다. 그 결과 한계하중은 실험값이 $Tschebotarioff(q_{cr}=3.0_{Cu)$의 제안값과 $Meyerhof(q_{cr}=(B/2H+\pi/2_{Cu})$의 제안값에 근접하여 $q_{cr}=2.78_{Cu$값을 나타냈고, 극한하중은 Prandtl의 제안값에 근접하여 $q_{ult}=4.84_{Cu}$의 값을 나타냈다

• Clinical and Experimental Reproductive Medicine
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• 제30권2호
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• pp.165-169
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• 2003

Objective: To evaluate the results of CASA systems and to compare its results. Methods: Fifty semen sampales were analysed. Concentration, motility and forward progression were evaluated simultaneously on the same semen samples using Cell Soft System-3000 (CS system) and Sperm Quality Analyzer-V (SQA system). Results: Mean semen volume was $2.8{\pm}1.2\;ml$. Mean value of sperm concentration, motility, forward progression using CS system were $83.4{\pm}45.7{\times}10^6/ml$, $52.3{\pm}16.4%$ and $48.6{\pm}13.4%$, respectively. And mean value of sperm concentration, motility, forward progression using SQA system were $78.2{\pm}42.9{\times}10^6/ml$, $57.0{\pm}24.0%$ and $50.6{\pm}21.9%$, respectively. There were no statistical significancy of sperm concentration, motility, forward progression between the two devices. Conclusion: SQA system variables well correlated with the CS system. As a screening test for semen quality, CS system and SQA system is considered as useful in the management of male infertility.