• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.2C
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• pp.49-60
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• 2012

In this study, the behaviors of friction pile groups are investigated using 3D finite element (FE) analysis. The emphasis was quantifying on the shear load transfer (f-w) characteristics of pile groups and the shaft group effects. A framework for determining the f-w curve is proposed based on both theoretical analysis and field load test database. Through comparisons with case histories and FE results, it is shown that the proposed f-w curve is capable of predicting the behavior of a friction pile in deep soft clay. Additionally, a numerical analysis that takes into account the group efficiency factors were performed for major parameter on group pile-soil interaction, such as the pile spacing, pile arrangement, soil condition, and location of pile cap. Based on these results, the shaft group efficiency factors were also proposed.

• Journal of the Korean Geotechnical Society
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• v.29 no.7
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• pp.17-36
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• 2013

In this paper, the empirical relations of skin friction and end bearing resistance with the results of site investigation in soft rock are proposed through the analysis of bi-directional pile load tests of rock socketed drilled shafts performed at large offshore bridge foundations and high-rise building projects (13 test piles in 4 projects). The site investigation and drilling for bi-directional pile load tests were performed at the centers of test piles, and f-w curves for skin friction and q-w curves for end bearing were plotted based on load-transfer measurements. From the above curves, the empirical relations of skin friction and end bearing resistance with the results of site investigation depending on the mobilized displacement are determined by multiple regression analysis and compared with previous studies. Since the f-w and q-w curves of rock-socketed piles in Korea show hardening behavior according to mobilized displacement, the developed empirical relations by the mobilized displacement are more reasonable than those of previous studies which could not consider the mobilized displacement and suggested the ultimate capacity with unconfined compressive strength only. Particularly, the developed equations correlated with unconfined compressive strength show the best correlations among the equations correlated with other parameters.

• Journal of the Korean Geotechnical Society
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• v.27 no.10
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• pp.55-67
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• 2011

The shear load distribution and deformation of offshore friction piles are investigated using experimental tests and a numerical analysis. Special attention is given to the soil-pile interaction of axially loaded pile. A framework for determining the f-w curve is proposed based on both theoretical analysis and experimental load test data base. A numerical analysis that takes into account the proposed f-w curves was performed for major parameters on pile-soil interaction such as the pile diameter, the pile length, and the soil condition. Based on the analysis, it is shown that the proposed f-w method is capable of predicting the behavior of a friction pile in deep soft clay. Through comparisons with case histories and finite element results, it is found that the proposed f-w curves are more appropriate and realistic m representing the pile-soil interaction of axially loaded piles in deep soft clay than that of existing f-w method.

• Journal of Korean Society of Transportation
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• v.19 no.6
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• pp.119-129
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• 2001

본 연구는 국내의 화물차(이하 트럭) 특성, 도로 조건과 주행 저항이 고려된 트럭 성능 곡선 산출식의 매개변수를 추정하기 위하여 수행되었다. 이를 위해 국내 대표트럭을 선정하고 경사지 진입속도를 산출하였다. 국내 대표트럭의 선정은 자동차 등록현황 자료를 토대로 하여 트럭 중량/마력비에 대한 누적 분포를 작성하고 이 중에서 주요 차종(적재 중량 11톤 이상)의 총중량은 과적 검문소 자료로 보정하여 이루어졌다. 경사지 진입속도는 도별 평지부 직선 구간을 한 곳씩 선정하여 4차로도로와 2차로도로에서 수집되는 자료를 분석하여 산출하였다. 트럭 성능 곡선 산출식을 정립하기 위해 오르막 한계속도$(V_x)$ 산출식을 정리한 뒤 총중량(W), 엔진성능(P), 경사도(G)는 독려 변수로 k, $f_{rc}$, $f_{rv}$, $\Phi$는 매개변수로 설정하였다. 현장조사를 통해서 오르막 한계속도에 도달한 트럭의 총중량과 엔진성능, 속도, 경사도 등의 자료를 수집하여 매개변수 산출에 이용하였다. 마지막으로 추정된 매개변수를 이용하여 트럭 성능 곡선을 도출하였다.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.187-196
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• 2005

Since the allowable bearing capacities of piles in weathered/fractured rock are mainly governed by settlement, the load-displacement behavior of pile should be known accurately. To predict pile head settlement at the design stage, the exact understanding of the load-transfer mechanisms is essential. Therefore, in this research, the load-transfer mechanism of drilled shaft socketed into weathered rock was investigated. For the investigation, five cast-in-place concrete piles with diameters of 1,000 mm were socketed into weathered gneiss. The static axial load tests and the load-transfer measurements were performed to examine the axial resistant behavior of the piles. A comprehensive field/laboratory testing program on weathered rock at the Held test sites was also performed to describe the in situ rock mass conditions quantitatively. And then, the effect of rock mass condition on the load transfer mechanism was investigated. The f-w (side shear resistance-displacement) curve of the pile in moderately weathered rock reached to yielding point at a for millimeter displacements, and after yielding point, the rate of resistance increment dramatically decreased. However, the f-w curve in the highly/completely weathered rock did not show the obvious yielding point, and the resistance gradually increased showing the hyperbolic pattern until relatively high displacement (>15 mm). The q-w (end bearing resistance-displacement) curves showed linear response at least until the base displacement of approximately 10 mm, regardless of rock mass conditions.

• Journal of the Korean Geotechnical Society
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• v.25 no.9
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• pp.29-43
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• 2009

As computational technologies have been developed, the load transfer analysis method using load transfer curves is widely performed. Now the load transfer analysis methods are widely used in our country. But most of the curves using in the analysis have been developed in foreign countries. In this study we gathered the data of in situ pile load tests on domestic nine sites in order to derive load transfer curves of driven steel pipe piles. Then we derived average lines of $f/f_{max}$-w/D curves for sandy and clayey soils respectively, which are expressed by hyperbolic function. And the results using these curves and the results using TZPile 2.0 (Analysis program of pile) were compared and analyzed with the results of pile load tests on domestic 3 sites in order to ascertain the applicability of the curves. The results show that the load-settlement relations using the curves in this study are more similar to the measured data and more conservative than those using TZPile 2.0.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.146.2-146.2
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• 2012

2008년부터 2012년에 걸친 관측기간 동안 총 21일간 관측하여 AA UMa의 BVRI 광도 곡선을 획득하였다. AA UMa의 I 필터 광도 곡선은 이번에 처음으로 얻어진 것이다. 또한 극심시각을 추가적으로 획득하기 위하여 2005 ~ 2008년까지 총 8일간 AA UMa의 극심 부근의 측광관측을 수행하였고, SuperWASP에서 공개하는 AA UMa의 측광 자료를 수집하여 총 31개의 새로운 극심시각을 결정하였다. 우리의 새로운 극심시각을 포함하여 83년 동안의 AA UMa 극심시각을 수집하여 총 250개의 극심시각으로 주기 변화연구를 수행하였다. 그 결과 AA UMa 계는 $3.30{\times}10^{-11}d/yr$의 영년 주기 증가 위에 58.7년의 주기적인 변화가 겹쳐 발생한다. 주기적인 변화의 원인이 제3천체에 의해 발생한다고 가정했을 때 제3천체의 최소 질량은 $0.28M_{\odot}$이다. 이전 연구자의 광도곡선(Meinunger(1976), Wang et al.(1988), Lee et al(2011))을 수집하여 우리의 광도곡선(2008, 2012)과 함께 각각 주기변화가 보정된 통일된 기산점을 사용하여 광도곡선을 분석하였다. 모든 광도곡선에서 0.75 위상에서 밝기가 더 어두워지는 O'Connell effect가 발생하였고, 일부 광도곡선은 부식에서 식의 깊이가 주식보다 깊어지는 시기를 가진다. 이는 스펙트럼 유형이 F0-F5보다 만기형 별에서 흑점이 부식의 깊이에 영향을 주어 주식보다 깊어지는 AC Boo, TY UMa 등에서 보여 지는 특징이다. 우리는 WD 프로그램을 이용하여 광도곡선 중 B-V 색지수 그래프에서 식 이외부분에서 변화가 적고 광도곡선의 O'Connell effect의 크기가 작은 2008 광도곡선으로 광도해를 결정하였다. 전형적인 TY UMa형 별과 같이, 우리의 광도해 역시 W-subtype의 결과를 나타낸다. 결정된 광도해를 다른 광도곡선에도 적용시켜 광도곡선에 나타나는 흑점의 영향을 살펴보았다. 마지막으로 주기 분석 결과와는 달리 제 3천체의 광도는 검출 되지 않았다.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.19 no.2
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• pp.125-129
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• 1983

It is customary to assume that the resistance of a jull at uniform speed may be regarded as the sum of viscous and wavemaking component resistance, or C sub(i)=C sub(v)+C sub(w), where C sub(v) is regarded as a function of Reynolds Number R and C sub(w) a function of Froude Number F. Formulae have been obtained for ∂C sub(w)/∂R, ∂C sub(v)/∂F which may be relevant in seeking theoretical grounds for possible interaction between viscous and wavemaking component resistances. The values of ∂C sub(w)/∂R are small. In general they are smaller than corresponding values of ∂C sub(v)/∂R. But although these values are small it does not follow that they are entirely negligible. The Froude assumption that the rate of change of C sub(w) with R is zero must bel regarded as incorrect.

• Journal of Life Science
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• v.9 no.6
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• pp.733-736
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• 1999

The doubly altered mutant tryptophan synthase $\alpha$-subunits, in which Thr 24 was replaced by Ser, Leu or Lys in addition to F139W substitution, were purified. Urea-induced unfolding equilibrium curves of these proteins, monitored by fluorescence intensity of tryptophan, show that the alterations of residue 24 resulted in marked changes in folding properites, suggesting the importance of this residue in folding of this protein.

• Nuclear Engineering and Technology
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• v.5 no.1
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• pp.38-43
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• 1973

The spin-rotation constants of the proton and tile fluorine nucleus in C $H_4$, Si $H_4$, Ge $H_4$, C $F_4$, Si $F_4$ and Ge $F_4$ were determined experimentally by the molecular beam magnetic resonance method. From the Hamiltonian and the high field approximation, the quantized energy level is given by the following equation. W $m_{I}$ $m_{J}$=- $g_{I}$ $m_{I}$H- $g_{J}$ $m_{J}$H- $C_{av}$ $m_{I}$ $m_{J}$, where $c_{av}$ is one third of the trace of the C tensor. In the nuclear resonance experiment, the proton and the fluorine nuclear resonance curves consist of many unresolved lines given by v=- $g_{J}$H- $C_{av}$ $m_{I}$, and a Gaussian approximation is made to correlate $c_{av}$ to the experimentally obtained half-width of the resonance curve. In the rotational resonance experiment, the five resonance peaks as predicted by v=- $g_{I}$H- $c_{av}$ $m_{I}$, $m_{I}$=0, $\pm$1 and $\pm$2, were all observed. The magnitude of car was determined by measuring the frequency distance between two adjacent peaks. The sign of $c_{av}$ was determined by the side peak suppression technique. The technique is described, and the sign and magnitude of the spin-rotation constant cav are summarized as following: for C $H_4$ -10.3$\pm$0.4tHz(from the rotational resonance), for SiH +3.71$\pm$0.08kHz(from the nuclear resonance), for Ge $H_4$+3.79$\pm$0.13kHz(from the nuclear resonance), for C $F_4$, -6.81$\pm$0.08kHz(from the rotational resonance), for Si $F_4$, -2.46$\pm$0.06kHz(from the rotational resonance), and finally for Ge $F_4$-1.84$\pm$0.04kHz(from the rotational resonance).onal resonance).esonance).