• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4C
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• pp.205-212
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• 2008

In this research, the effect of rock mass weathering on the side shear resistance of drilled shaft socketed into igneous-metamorphic rock was investigated. For that, 23 cast-in-place concrete piles with diameters varying from 400mm to 1,500mm were constructed at four different sites, and the static axial load tests were performed to examine the resistant behavior of the piles. A comprehensive field/laboratory testing program at the field test site was also performed to describe the in situ rock mass conditions quantitatively. The side shear resistance of rock socketed piles was found to have no intimate correlation with the compressive strength of the intact rock. However, the global rock mass strength, which was calculated by the Hoek and Brown criteria, was found to closely correlate to the side shear resistance. The ground investigation data regarding the rock mass conditions (e.g. $E_m$, $E_{ur}$, $p_{lm}$, RMR, RQD, j) were also found to be highly correlated with the side shear resistance, showing the coefficients of correlation greater than 0.75 in most cases. Additionally, the applicability of existing methods for the side shear resistance of weathered granite-gneiss was verified by comparison with the field test data. The existing methods which consider the effect of rock mass condition were modified and/or extended for weathered rock mass where mass factor j is lower than 0.15, and RQD is below 50%.

• 농업기술회보
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• v.47 no.3
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• pp.9-18
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• 2010

농업이 모든 산업의 근간이며 인류의 생존을 좌우하는 필수적 식량생산 수단임을 말할 나위 없으나, 차츰 경지면적도 줄어들고 더욱이 화학비료 위주로 하는 농사법으로 인해서 지력이 저하된 관계로 심각한 농약공해문제가 야기되고 있는 이때에 우리 다같이 이 점에 대해 구제책이 무엇인가를 독농가 여러분과 연구검토 해보고자 제한된 지면을 이용하여 대략적인 소견을 피력하고자 한다.

• KOREAN POULTRY JOURNAL
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• v.19 no.9 s.215
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• pp.39-41
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• 1987

화학비료에 의존한 경작으로 점차 토양은 산성화되고 지력의 저하가 경종농업분야에서 큰문제로 대두되고 있으며 한편에서는 계분의 처리문제로 양계농가의 어려움을 더해가고 있다. 계분을 효율적으로 발효처리한다면 양계농가의 골치거리를 해결할 뿐만 아니라 돈(금)으로 바꿔 경영에 보탬이 되고 국토의 지력상승면에서도 큰 기여를 할 수 있을 것이다. 계분발효의 원리와 방법을 제시한다.

• Polymer(Korea)
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• v.38 no.5
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• pp.620-625
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• 2014

The effect of polyvinyl alcohol/polyamide-epichlorohydrin (PVA/PAE) complex strengthening additive on dry and wet strength and surface properties of paper was investigated. The enhancements of dry and wet strength and dimensional stability were found when PVA/PAE was applied as a complex strengthening additive compared with the cases of applying individual PVA or PAE. This was understood as physical crosslinking between PVA and PAE in the PVA/PAE complex strength additive. This complex strengthening additive also lowered surface roughness and increased sizing. As a result, PVA/PAE complex strengthening additive provided the distinctive gain dot in printed papers.

• Journal of Gifted/Talented Education
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• v.17 no.2
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• pp.280-306
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• 2007

The purpose of this study is to investigate the two assertions of hereditarianism and environmentalism in the intellectual abilities, which is one of the most important factors of giftedness, and thus to discuss and understand giftedness. As the result of various investigations about the two opposing opinions, it is general view that about 50% of the intellectual abilities are endowed by genetic factors, but they are not fixed life long but changed and developed by posterior experiences. In other word, it is said that giftedness itself of which an important factor is intellectual abilities is determined by heredity, but the degree of revelation of the potential faculty is determined by environmental factors. Therefore, the recent major concerns in this field seem to be on how to make unfold most the children's giftedness rather than arguments about the degree of genetic and environmental factors. It can be said that giftedness is sprung up and accelerated only when an excellent genetic factor and a special environmental factor are transacted dynamically and amplified exquisitely.

• Journal of the Korean Geotechnical Society
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• v.29 no.11
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• pp.5-15
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• 2013

The end bearing capacity of rock-socketed drilled shafts under axial loading is investigated by Hoek-cell tests and a numerical analysis. From the test results, it was found that the ultimate end bearing capacity ($q_{max}$) was influenced by pile diameter, rock mass modulus and the spacing of discontinuity. A new ultimate end bearing capacity method is proposed by taking end bearing capacity influence factors, including rock mass discontinuity, based on field data. Through comparisons with other field data, the proposed $q_{max}$ method represents a definite improvement in the prediction of ultimate end bearing capacity of rock-socketed drilled shafts.

• Journal of the Korean Geotechnical Society
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• v.25 no.4
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• pp.77-90
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• 2009

In this study, experimental analysis was performed about lateral load capacity and behavior of laterally loaded-bored rigid piles in muti-layered soil conditions. Lateral pile load tests were performed for muti-layerd soils consisting of different relative density. Ultimated lateral load capacities were measured from lateral load-displacement curves and compared with estimated values using theoretical methods. Bending moments and unit lateral capacity distribution of surrounding piles were measured from attached strain gauges and earth pressure sensors on the pile. It was found that ultimated lateral load capacities were different from the muti-layered soil conditions, and measured values were lower than estimated values. The bending moment distributions of the pile were similar all the time. Unit lateral capacity distributions were a little different from muti-layered soil conditions, but basically similar to the distribution proposed by Prasad and Chari (1999).

• 한국양묘협회지
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• s.17
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• pp.30-36
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• 1989

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.1
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• pp.51-61
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• 2018

Foundation of tower structures such as wind turbine, pylon, and chimney have to resist considerably large overturning moment due to long distance from foundations to load point and large horizontal load. Pile foundations subjected to uplift force are needed to economically support such structure even in the case of rock layer. Therefore, this research performed the laboratory model tests with the variables, W/C ratio and sand proportion, to evaluate the effect of the mix proportion of grouting material on shaft resistance. In the case of cement paste, maximum and residual shaft resistance were distributed in uniform range irrespective of the changes of W/C ratio. However in the case of mortar, they were decreased with increasing W/C ratio, while they were increased and then decreased with increasing sand proportion. In the case of no sand, the maximum shaft resistance was about 540~560kPa regardless of the W/C ratio. When the sand proportion was 40%, it was about 770~870kPa depending on W/C ratio, which was about 40~50% higher than that without sand. The optimum proportion found in this research was around 40% of sand proportion and 80~100% of W/C ratio.

• Journal of the Korean Geotechnical Society
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• v.23 no.4
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• pp.161-167
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• 2007

In this study, ultimate lateral load capacity of piles is analyzed with consideration of lateral stress effect. Based on results obtained in this study, a method for the estimation of ultimate lateral load capacity is proposed. This makes it possible to more realistically estimate the ultimate lateral load capacity under various stress states caused by in-situ soil condition and pile installation process. Calibration chamber test results with various soil conditions were used in the analysis. From the test results, it was found that effect of the lateral stress was greater than that of the vertical stress on the ultimate lateral load capacity of piles. It was also found that, as the relative density increases, displacements required to reach the ultimate state increases, showing relative displacements of around 14% and 18-25% for $D_R$ : 55% and 86%, respectively. Based on results obtained in this study, a methodology for the estimation of ultimate lateral load capacity of piles using correction factors was proposed. Results from proposed method matched well measured results.