• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.458-461
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• 2009

본 논문에서는 2개의 구조물이 마찰댐퍼로 연결된 연결제진구조물에 대한 지진응답해석을 실시하였다. 연결제진구조물의 지진시의 제진효과를 파악하기 위하여 마찰댐퍼의 복원력특성을 완전탄소성형으로 설정하고 두 구조물의 고유주기 및 연결강성의 변화에 따른 각 지진파별 시간이력지진응답해석을 실시하였다. 또한, 응답해석결과를 바탕으로 마찰댐퍼의 특성지표(연결강성배율 $\alpha$, 항복내력비 $\beta$)를 결정하는 제진성능곡선을 제안하였다. 제진성능곡선을 통한 마찰댐퍼의 특성지표에 근거하여 연결제진구조물에 마찰댐퍼를 효율적으로 사용할 수 있는 최적의 마찰댐퍼량을 결정 할 수 있는 자료를 제시하였다.

• Journal of Welding and Joining
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• v.15 no.6
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• pp.1-12
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• 1997

마찰용접의 실제적인 생산에의 응용은 중요 부품의 용접에 그 적용이 검토 되었지만 마찰용접의 실적이 적었기 때문에 다른각종의 용접법과 용접부 특성을 비교 확인할 정도이었을 뿐 마찰용접을 본격적으로 도입하는 데에는 많은 저항이 있었다. 그러나 각종 시험을 되풀이하고 확고한 근거가 마련된 단계에서도 품질에 대한 불안 이나 일반화되어 있지 않다고 하는 관점에서도 마찰용접이 갖는 매력 때문에 도입이 시도되었다. 따라서 마찰용접품의 관리에 대해서도 비정상적일 정도로 배려를 거듭하 여 초창기에는 전체를 비파괴 시험하거나 sample 파괴시험하는 등의 상당히 번잡한 검사를 거쳤다. 그러나 마찰용접품의 불량률이 격감하였다는 것과 검사결과가 양호 하다는 등 종래의 용접법에 비해 용접부의 품질이 매우 우수하고 또 재현성이 높다는 점이 증명된 이후 흡속히 마찰용접이 각 산업분야에 도입되었다.

• Journal of Energy Engineering
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• v.9 no.2
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• pp.102-108
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• 2000

난류상태로 유동중인 고분자 수용액은 순수 용매만의 경우에 비교할 때 동일유량에서 초기에 높은 마찰 저항감소효과를 보이며, 이러한 마찰저항감소효과는 펌프의 펌핑능력 증대로 큰 경제적 이익을 가져다준다. 그러나, 고분자 수용액은 그 극적인 마찰저항감소효과에도 불구하고 유동중에 가해지는 기계적 에너지, 열에너지 등에 의해서 초기의 높은 마찰저항감소효과를 점차적으로 상실하게 되기 때문에, 고분자 수용액의 퇴화를 완화시키기위한 연구가 필요하다. 따라서 본 연구에서는 기계적 퇴화특성이 비교적 강한 합성고분자와 계면활성제의 농도합계를 100wpm 으로 고정하고 비율을 11가지로 세분화하여 , 1$0^{\circ}C$의 온도에서 유속 1.5m/sec , 3.0m/sec 및 4.5m/sec 에 대한 퇴화경향을 알아보는 실험을 수행하였으며, 각 조건에서 합성고분자와 계면활성제의 적정비율을 관찰하였다. 실험 결과, 각 속도에서 시간에 따른 퇴화경향은 고속에서 기계적 에너지에 대한 퇴화를 볼 수 있었고, 계면활성제와 합성고분자를 혼합하여 첨가했을 경우 저온에서도 퇴화완화효과가 있음을 확인하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.331-337
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• 2016

Several foundation soil conditions below a homogeneous sand slope were assumed and slope stability analyses were conducted to determine the soil condition, in which a stabilizing pile can be used to increase the factor of safety against sliding. The assumed heights of the sand slope were 5m and 10m. For a 5m slope height, a stabilizing pile can be used in the foundation soil with a $15^{\circ}$ internal friction angle and a cohesion of 10kPa. For a 10m slope height, a stabilizing pile can be used in the foundation soil with a $20^{\circ}$ internal friction angle and a cohesion of 10kPa and a stabilizing pile can be used in the foundation soil with a $0^{\circ}$ internal friction angle and 40kPa, 45kPa and 50kPa of cohesion. According to the analysis results of stabilizing pile-reinforced foundation soil, the length of the stabilizing pile and magnitude of the maximum bending moment were strongly affected by the internal friction angle of the foundation soil. The lengths of stabilizing pile, for an internal friction angle of $0^{\circ}$ were 4.6, 8.0 times greater than those with an internal friction angle of $5^{\circ}$. The magnitude of the maximum bending moment of the stabilizing pile for an internal friction angle of $0^{\circ}$ was 24.6 times greater than that for an internal friction angle of $5^{\circ}$. Practically, a stabilizing pile cannot be used for foundation soil with an internal friction angle of $0^{\circ}$. Considering the results derived from this study, the effects of a stabilizing pile can be maximized for soft foundation soil that is embanked with a slow construction speed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.1
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• pp.63-70
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• 1994

This study presents the nonlinear dynamic analysis method of the multi-span continuous bridge considering the friction of the expansion bearings. Also the numerical analysis is performed for estimating the effect of the friction on the seismic response of the multi-span continuous bridge under the longitudinal ground motion compatible to Korean bridge design response spectra. It is found that even small friction coefficient of the expansion bearings has significant effect on reducing the superstructure displacement due to energy dissipation and distributing the inertia force of the superstructure to the substructures due to frictional force. It is observed that such favorable friction effects increase as the friction coefficient increases and the magnitude of the ground motion decreases. Therefore, the friction of the expansion bearings can be effectively used for the safe and economic design of the continuous span bridge with many spans and large superstructure weight under the small to medium scale longitudinal ground motions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4
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• pp.167-177
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• 1992

This study analyses theoretically the bearing capacity of shallow foundation, considering the effect of roughness of base. The new bearing capacity factors based on the concept of limit equlibrium are succesfully derived. The simplified formula corresponding to the newly derived expressions are developed as well. The results of the present study are comparable to the conventional theories i.e., Terzaghi's, Meyerhofs, Vesic's and Yamaguchi's. In conclusion it is recommended that the upper limit of friction angle of soil be ${\varphi}=40^{\circ}$, and the angle of base friction be adquetely used with various ranges of ${\varphi}$ for safe designs and constructions.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.951-956
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• 2010

본 연구에서는 $\bigcirc\bigcirc$화력발전소 회사장에 매립되고 있는 혼합회가 도로성토 및 철도노반 등 성토재로 사용될 수 있는가를 평가하기 위하여 물리적 및 역학적 특성을 평가하였다. 비중, 액소성 시험, 입도분석, XRD 시험, 강열감량시험, 실내투수시험을 통해 물리적 특성을 평가하였고 다짐시험, CBR 시험, 배수삼축압축시험을 실시하여 역학적 특성을 평가하였다. 두 가지 혼합회에 실험한 결과 비중은 2.181~2.189, 투수계수는 $1.32{\times}10^{-4}{\sim}1.89{\times}10^{-4}cm/sec$, 수정CBR은 19.5~21%, 배수마찰각은 $36.43{\sim}41.39^{\circ}$로 평가 되었다. 혼합회의 투수계수는 실트질 흙과 유사한 범위에 있으며 배수마찰각은 상대밀도가 큰 모래질 흙이 보일 수 있는 내부마찰각의 범위를 보였다. 본 연구에서 사용한 혼합회는 도로성토 및 철도노반 등 성토재로 사용할 수 있는 것으로 평가되었다.

• Geotechnical Engineering
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• v.14 no.4
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• pp.103-116
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• 1998

To estimate pure shear strength, 150 sets of triaxial test data were analyzed. The proportional coefficient of shear strength($I_c$) at zero normal stress was nonlinearly decreased as failure coefficient m increases, while the internal friction $\phi_0$ at zero normal stress was nonlinearly increased. The ratio of shear strength $(c/\phi_0)$was inversely proportional to the ratio of the internal friction angles$(\phi/phi_0)$ The shear strength decreased as m increased, while internal friction angle increased. And uniaxial strength was proportional to $c,\phi$ Regression analysis showed that shear strength strongly affects m and $\sigma_c$ The proportional coefficient of shear strength was nonlinearly increased with RMR, while the internal friction angle $(\phi}$was linearly decreased.

• Journal of the Korean Geotechnical Society
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• v.31 no.11
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• pp.33-40
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• 2015

Volcanic rocks in Jeju Island indicate the differences in geological and mechanical characteristics from region to region, and have vesicular structure caused by various environmental factors. In this study, triaxial compressive strength tests were conducted for intact rocks sampled in northeastern onshore and offshore, southeastern offshore and northwestern offshore of Jeju Island. The estimated cohesion and internal friction angle from the results of triaxial compression tests were compared and analyzed with absorption, a parameter representing the vesicular properties of basalts in Jeju Island. As a result, it was found that the relationship between cohesion and absorption could be classified clearly, considering two different linear relationships in bulk specific gravity and absorption. As the absorption increases, the cohesion decreases exponentially. In addition, the internal friction angle decreases almost linearly with increasing in the absorption, regardless of the relationships in bulk specific gravity and absorption.

• Journal of the Korean Geotechnical Society
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• v.28 no.5
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• pp.5-12
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• 2012

Geotextile tube method is the latest application process to construct a variety of civil structures such as river and coastal structures by using geotextile which is a high polymer synthetic fiber. In this paper, laboratory tests and field tests were conducted in order to identify the behavior, stability and application possibility of geotextile tube which prevents the erosion of coastal sand. As a result of large-scale direct shear test, which is one of laboratory tests, the increase in friction angle was shown as the relative density increased, and friction angle of sand/geotextile was larger than that of sand/sand. As a result of field test, the behavior and stability during construction and after construction were identified through measurement, and the effect of preventing erosion was confirmed.