• Journal of the Korean Geotechnical Society
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• v.23 no.3
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• pp.123-131
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• 2007

A series of CIDC triaxial tests and cone penetration tests in calibration chamber were performed to investigate the relationship between state parameter and normalized cone resistance far dredged Busan sand. From the results of the triaxial tests, the critical state line of Busan sand was established, and the critical state parameters found to be $M=1.39(\phi_{cs}=34^{\circ}),\;\Gamma=1.07$ and $\lambda=0.068$. By analyzing the state parameters and corresponding cone resistances for calibration chamber specimens, the relationship between normalized cone resistance and state parameter for Busan sand was defined as $(q_c-p)/p'=27.6\exp(-10.9\Psi)$. This relationship was also shown to be independent of the stress history. From the comparison of the slope of the normalized cone resistance, m, and the normalized cone resistance at $\Psi=0$, $\kappa$, with those of various sandy soils from over the world, the relationship of m and $\kappa$ with $\lambda_{ss}$ of Busan sand was concluded to show a good agreement with the result published previously, while Busan sand had the largest $\kappa$ among the soils with similar $\lambda_{ss}$ values.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.42-50
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• 2006

역들의 공간적 분포가 불균질하고 역의 크기가 큰 역암의 경우 암석 전체를 대표하는 물성치($E_m,\;c,\;\Phi$ 등) 구하기 위해서는 매우 큰 시험기기가 필요하다. 따라서 커다란 역을 포함하는 역암의 경우 직접 암석실내시험을 통한 물성치 산정은 현실적으로 거의 불가능하다. 이러한 문제를 극복하기 위하여 이 연구에서는 개별요소법을 이용하여 역암의 물성치를 산출하는 방법을 제안한다. 그 방법은다음과 같다. (1) 역암내의 역의 물성과 기질부의 물성을 각각 실내실험을 통하여 파악한 후 이들 (2) 두 물질의 거동양상을 구현할 수 있는 개별요소집합체의 개별요소간의 물성을 결정한다. (3) 역의 함량, 크기 모양 공간적 분포양상등의 역암 조직과 유사한 개별요소 수치해석시료를 만든 후, (4) 이를 수치 해석실험 (이축압축실험)에 사용한다. 이러한 수치해석실험을 통해 현재까지 만들어진 결과는 다음과 같다. 첫째, 역의 강도가 기질의 강도보다 높은 역암의 경우, 역의 양이 증가할수록 일축압축강도, 내부 마찰각, 점착력이 증가하지만 증가 양상은 선형이 아니다. 탄성계수의 경우 역의 양과 상관 없이 변화하지 않는다. 둘째, 역과 기질 사이 표면의 점착력이 약할 경우 이러한 표면에서 최초 미세 균열이 형성되기 시작하므로 이 점착력은 물성치를 산출하는 중요한 인자이다. 따라서, 향후 이에 대한 자세한 연구가 필요하다고 판단된다. 결론적으로,설계 또는 시공시 직접시험에 의한 물성치의 파악이 어려운 역암 또는 직접시험을 위해 대량의 시료를 필요로 하는 함력 미고결지층, 핵석층, 풍화암과 같은 시료의 물성치는 별도로 측정된 물성들 (예, 역과 기질)을 이용한 개별요소법을 통해 구할 수 있다.로 나타났다.TEX>, DIN/DIP비 표층수 $23.91\pm3.42$, 저층수 $23.43\pm3.38$이었으며, 전반적으로 해역별 수질기준 I등급 내지는 II등급을 유지하고 있었고, 공간적으로는 외해측으로 갈수록 외해수와 혼합 확산되어 양호한 수질을 나타내었다. 장기적인 변동특성은 세그룹으로 구분되어진다.기 실험결과 용출용매로 증류수와 해수를 이용했을 때, 제강 슬래그에서 용출되는 납, 구리, 카드뮴, 수은의 용출 경향의 차이를 확인할 수 있었고 이에 따라서, 납, 구리, 카드뮴의 용출 유해성은 낮기 때문에 해양구조물로의 제강슬래그 유효이용은 적합할 것으로 판단되었다.im80%$로 계산되었다. 열형광선량계로 측정된 방사선량은 각각 1.8, 1.2, 0.8, 1.2, 0.8 (70 cm 거리) cGy로 측정되었으며, 환자의 복부 표면에서의 서베이메터를 이용한 측정량은 10.9 mR/h였다. 차폐구조물의 사용 시 전체 치료 동안에 태아선량은 약 1 cGy 정도로 평가되었다. 결론 : AAPM Report No.50의 자료에 따르면, 임산부의 방사선 치료 시 태아의 방사선 피폭선량은 5 cGy 이하일 경우에 방사선 피폭에 따른 태아의 위험이 거의 없는 것으로 제시되고 있다. 본원에서 차폐 구조물을 설치하였을 경우에 측정된 태아선량은 약 1 cGy로 측정되었고, 고안된 차폐구조물은 태아에 도달하는 방사선량을 감소시키기에 적합한 설계임이 입증되었다. 아니라 일반종합병원에서도 CTX-M형 ESBL 생성 E. coli와 K. pneumoniae가 존재하며 확산 중임을 시사한다. 앞으로 CTX-M형 ESBL의 만연과 변종 CTX-M형 ESBL의 출연을 감시하기 위한

• 기술발표회
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• s.2006
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• pp.320-328
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• 2006

In this test, there was two dimensional model loading test implemented for analysis with respect to the problem of evaluating bearing capacity and the application range on the dredged and reclaimed ground. It was got following conclusion through comparison of button's and Brown&Meyerhof"s equation with experimental result that was obtained by 2 dimensions model loading test. For the difference between average undrained shear strength by 2/3B of loading board width and under 2/3B is more than ${\pm}$ 50%, application of Nc(coefficient of bearing capacity was used in that case $\phi$=0 analysis is considered in the single layer) was declined. Brown&Meyerhof(1969)'s equation was underestimated comparing with loading test result, while Button(1953)'s equation was overestimated comparing with loading test result applied dividing as double layers of upper dessication layer and lower soft layer about dredged and reclaimed ground. Also, bearing capacity factors, Nc that was calculated by using button's equation was estimated greatly about 1.7 times more than bearing capacity factors, Nc that was calculated by using Brown&Meyerhof's equation. Bearing capacity factors, Nc that was calcuated by using Brown&Meyerhof's and Button's equation was evaluated each 2.3-3.6 times, 1.3-2.1 times smaller than bearing capacity factors, Nc5.14 that was calcuated by using Meyerhof's equation in case of unit layer.

• Journal of the Korean Geotechnical Society
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• v.24 no.12
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• pp.65-73
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• 2008

In the current practice for slope stability problem in Japan, the shear strength, $\tau$, mobilized along the failure surface is usually estimated based on an empirical approximation in which the cohesion, c, is assumed to be equal to the soil thickness above the supposed slip surface, d(m). This approximation is advantageous in that the result of stability analysis is not influenced by the designers in charge. However, since the methodology has little theoretical background, the cohesion may often be grossly overestimated, and conversely the angle of shear resistance, $\phi$, is significantly underestimated, when the soil thickness above the supposed slip surface is quite large. In this paper, a case record of natural slope failure that took place in Hyogo Prefecture in 2007, is described in detail for the case in which the shear strength along the collapsed surface was carefully examined in a series of direct shear box (DSB) tests by considering the effects of in-situ shear stress along the slip surface. It is demonstrated that the factor of safety agrees with that of in-situ conditions when the shear strength from this kind of DSB test was employed for the back-analysis of the slope failure.

• Explosives and Blasting
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• v.9 no.1
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• pp.3-13
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• 1991

The cautious blasting works had been used with emulsion explosion electric M/S delay caps. Drill depth was from 3m to 6m with Crawler Drill ${\phi}70mm$ on the calcalious sand stone (soft -modelate -semi hard Rock). The total numbers of test blast were 88. Scale distance were induced 15.52-60.32. It was applied to propagation Law in blasting vibration as follows. Propagtion Law in Blasting Vibration $V=K(\frac{D}{W^b})^n$ were V : Peak partical velocity(cm/sec) D : Distance between explosion and recording sites(m) W : Maximum charge per delay-period of eight milliseconds or more (kg) K : Ground transmission constant, empirically determind on the Rocks, Explosive and drilling pattern ets. b : Charge exponents n : Reduced exponents where the quantity $\frac{D}{W^b}$ is known as the scale distance. Above equation is worked by the U.S Bureau of Mines to determine peak particle velocity. The propagation Law can be catagorized in three groups. Cubic root Scaling charge per delay Square root Scaling of charge per delay Site-specific Scaling of charge Per delay Plots of peak particle velocity versus distoance were made on log-log coordinates. The data are grouped by test and P.P.V. The linear grouping of the data permits their representation by an equation of the form ; $V=K(\frac{D}{W^{\frac{1}{3}})^{-n}$ The value of K(41 or 124) and n(1.41 or 1.66) were determined for each set of data by the method of least squores. Statistical tests showed that a common slope, n, could be used for all data of a given components. Charge and reduction exponents carried out by multiple regressional analysis. It's divided into under loom over loom distance because the frequency is verified by the distance from blast site. Empirical equation of cautious blasting vibration is as follows. Over 30m ------- under l00m ${\cdots\cdots\cdots}{\;}41(D/sqrt[2]{W})^{-1.41}{\;}{\cdots\cdots\cdots\cdots\cdots}{\;}A$ Over 100m ${\cdots\cdots\cdots\cdots\cdots}{\;}121(D/sqrt[3]{W})^{-1.66}{\;}{\cdots\cdots\cdots\cdots\cdots}{\;}B$ where ; V is peak particle velocity In cm / sec D is distance in m and W, maximLlm charge weight per day in kg K value on the above equation has to be more specified for further understaring about the effect of explosives, Rock strength. And Drilling pattern on the vibration levels, it is necessary to carry out more tests.