• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.82-89
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• 2004

To secure stability and availability of Rammed Aggregate Pier method as the foundation of a structure, the shear strength characteristics according to the area replacement ratio of RAP and the relative density of in-situ ground was studied through soil laboratory tests and large direct shear tests in a model ground. As a result, the internal friction angle tends to increase in proportion to in-situ relative density(Very Loose, Loose, Medium) in composite ground formed by the same area replacement ratio of RAP and also increase in proportion to increasing the area replacement ratio(30, 40, 50%) of RAP in the same ground condition. Furthermore, the comparative analysis between the experimental value and theoretical value of the shear strength is carried out.

• Geomechanics and Engineering
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• 제36권2호
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• pp.167-181
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• 2024

The soil-structure relative stiffness is a key factor affecting the seismic response of underground structures. It is of great significance to study the soil-structure relative stiffness for the soil-structure interaction and the seismic disaster reduction of subway stations. In this paper, the dynamic shear modulus ratio and damping ratio of an inhomogeneous soft soil site under different buried depths which were obtained by a one-dimensional equivalent linearization site response analysis were used as the input parameters in a 2D finite element model. A visco-elasto-plastic constitutive model based on the Mohr-Coulomb shear failure criterion combined with stiffness degradation was used to describe the plastic behavior of soil. The damage plasticity model was used to simulate the plastic behavior of concrete. The horizontal and vertical relative stiffness ratios of soil and structure were defined to study the influence of relative stiffness on the seismic response of subway stations in inhomogeneous soft soil. It is found that the compression damage to the middle columns of a subway station with a higher relative stiffness ratio is more serious while the tensile damage is slighter under the same earthquake motion. The relative stiffness has a significant influence on ground surface deformation, ground acceleration, and station structure deformation. However, the effect of the relative stiffness on the deformation of the bottom slab of the subway station is small. The research results can provide a reference for seismic fortification of subway stations in the soft soil area.

• 한국농공학회지
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• 제33권3호
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• pp.51-62
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• 1991

A comprehensive laboratory investigation of the liquefaction characteristics of Jumunjin standard sand. Seoul sand and Hongsung sand was peformed by the undrained cyclic triaxial compression test under different relative densities, confining pressures and cyclic deviator stresses. The results obtained are as follows ; 1. Liquefaction potential was dominated by the stress ratio at a given number of cycle. That is, the number of cycle required to cause initial liquefaction became samller as the stress ratio increased. 2. Liquefaction potential of a sand was infliuenced by initial relative density or void ratio. Under a given relative density. liquefaction potential of Jumunjin standard sand and Seoul sand was smaller than that of Hongsung sand. 3. The pore pressure ratio of Hongsung sand was the smallest three under a given relative density and stress ratio, and it showed higher value when the cyclic stress and the shear strain were high. 4. An excessive pore pressure ratio not found when initial shear was smaller than 0.01%, and the pore pressure ratio started to increase when initial shear became greater than 0.01%. 5. Soil texture is an important factor to cause liquefaction, and liquefaction potential decreased a the mean grain size decreased. however the sand having fine grain such as Hongsung sand showed somewhat higher liquefaction potential. 6. Based on the analysis of the specimens whose number of the cycles to cause liquefaction was 8~12, it was found that the relationship between density and stress ratio was linear. The curves for Hongsung sand was steeper than the other. 7. From the above results and the method suggested by Seed-Idriss, it may be considered that the damages by Hongsung earthquake was not directly caused by liquefaction.

• 한국방사선학회논문지
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• 제6권6호
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• pp.499-505
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• 2012

개인피폭선량계인 열형광선량계(TLD)와 광자극형광선량계(OSLD)를 진단방사선 영역에서 사용할 때 에너지와 조사 횟수, 투시촬영 시간, 산란선 노출 일 수 등에 따라 측정값이 차이가 있는지를 상대비와 상대비 간격으로 알아보았다. 에너지에 따라서는 TLD의 상대비($1.81{\pm}0.41$)가 OSLD의 상대비($1.40{\pm}0.26$)보다 높았고, 조사 횟수에 따라서는 TLD의 상대비($2.10{\pm}0.10$,)보다 OSLD의 상대비($2.33{\pm}0.09$)가 더 높았다. 투시촬영 시간에 따른 상대비와 산란선 노출일수에 따른 상대비는 두 선량계가 유의한 차이가 없었으나 산란선 노출일수에 따른 상대비의 간격이 0.2 이내로 나타나 직접선의 상대비 간격보다 좁았다. 이는 직접선의 측정결과보다 산란선의 측정에 있어 TLD와 OSLD의 결과값에 신뢰가 높다고 할 수 있다. 따라서 방사선 피폭상황에 따라 선량계 간에 상대비가 다소 차이가 날 수 있음을 인지하고, 경우에 따라서는 두 가지 선량계를 이용하여 교차평가를 함으로써 선량 측정 결과값에 대한 신뢰성을 높일 수 있을 것이다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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• pp.517-524
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• 2001

In this study, the effect of relative density and fine contents(Finer then # 0.08mm sieve) on liquefaction phenomenon in reclaimed land by hydraulic hammer compaction is analyzed. For more site-specific studies, reclaimed land in Inchon International Airport is selected and the cyclic triaxial tests are performed on disturbed samples. In cyclic triaxial tests, the characteristics of reclaimed land in Inchon International Airport are considered sufficiently. The liquefaction resistance stress ratio ($\tau$$\ell$/$\sigma$v') can be defined by relative density 40, 50, 60, and 70% and also by fine contents : 0, 10, 20, 30, and 40% under relative density (D$\_$r/) 50% used disturbed samples. From tile result of comparing tile cyclic triaxial tests, it is shown that the liquefaction strength of soil increases with increases of relative density and fine contents. Fspecially fine contents is the main factor affecting the liquefaction potential. In addition, the liquefaction resistance stress ratio is reduced by the increase of fine content and tile ratio of change is steep until fine contents 20% and that is flexible during the range of fine contents 20% to 40%. Through this study, it is proved that the soil characteristics (fine contents 5∼20%) of the reclaimed land in Inchon International Airport flays an important role in the reduction of liquefaction potential.

• Journal of Biosystems Engineering
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• 제31권5호
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• pp.410-415
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• 2006

This study was performed to develop thin layer drying equations for green rice. Thin layer drying tests of green rice were conducted at three temperature levels of 30, 40, $50^{\circ}C$ and two relative humidity levels of 30, 50% respectively. The measured moisture ratio were fitted to the selected four drying models (Page, Thompson, Simplified diffusion and Lewis model) using stepwise multiple regression analysis. The overall drying rate increased as the drying air temperature and as relative humidity was increased, but the effect of temperature increase was dominant. Half response time (Moisture ratio=0.5) of drying was affected by both drying temperature and relative humidity Drying rate was mainly affected by relative humidity at drying temperature of $50^{\circ}C$. The results of comparing coefficients of determination and root mean square error of moisture ratio for four drying models showed the Page model was found to ft adequately to all drying test data.

• 한국환경과학회지
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• 제23권10호
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• pp.1731-1743
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• 2014

The time variations in relative humidity observed at the Gangjeong (Goryeong) Reservoir in the Nakdong River over a one-year period (September 2012-August 2013) were analyzed with the Bowen ratio. The thermal vertical scale of the reservoir was also evaluated following Yamamoto's method. The study's results showed that the relative humidity at the reservoir was higher than that of the Daegu Meteorological Observatory (inland) all year round. The difference was slightly larger at nighttime (17-20 %) than at daytime (13-15 %) in all seasons except summer. The quantitative order of latent heat flux was summer, spring, autumn, and winter. This finding signifies that the thermal vertical scale of the reservoir corresponds to that of a shallow lake. The Bowen ratio was smallest at midday of the summer season. In other words, the net radiation energy was converted more as latent heat flux than sensible heat flux during a higher temperature period.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2007년도 춘계학술대회논문집
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• pp.285-297
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• 2007

As the demands of environment protection increase, the pulp mold container is developed to substitute for the plastic cushion materials like EPS(expanded poly styrene). The water-absorbing ratio, tensile strength and compressive strength of pulp mold are important factors to evaluate its shock absorbing characteristics. The study was performed to investigate the effects of the mechanical property changes on the various conditions of temperature and relative humidity for pulp mold containers made of mixed materials on ONP(old newspaper) and OCC(old corrugated container). This study also is evaluated the optimized mixing ratio of materials for making pulp mold by analyzing the changes of physical properties according to a various procured temperature and relative humidity conditions. The results show that the water absorption ratio of sample increased significantly, and tensile strength decreased $20{\sim}30%$, compressive strength decreased $10{\sim}20%$ by increasing relative humidity condition. And the results show that the ONP 50% and OCC 50% was optimized mixing ratio according to the samples.

• 서비스연구
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• 제4권2호
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• pp.37-47
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• 2014

서비스산업은 국가 경제의 지속가능한 성장을 뒷받침할 핵심 분야이다. 그러나 아직 우리 경제에서 서비스산업의 발전은 선진국 수준에 미치지 못하고 있다. 서비스업에 대한 최근의 통계가 이를 뒷받침하고 있다. 본 논문은 지역별로 국내 서비스산업의 현황을 사업체수 및 종사자수 통계를 중심으로 비교분석한 것이다. 이를 위해 16개 시 도 지역에 대한 전국 사업체조사 자료를 토대로 수도권, 강원권, 충청권, 호남권, 영남권, 제주권 등 6개 광역권으로 분류하여 이들 지역에 있어서 전체 산업에 대한 서비스산업에서의 사업체수 및 종사자수의 상대비율을 비교분석하고, 또한 각 권역에 있어서 시도별로 사업체수 및 종사자수의 상대비율을 비교분석한다. 지역별 비교를 위해서 사용한 자료는 2006년부터 2012년 동안 최근 7년간의 전국사업체조사 자료이며, 이 자료를 통해 6개 권역에 대한 서비스산업에서의 사업체수 및 종사자수의 상대비율을 계산하였다. 그리고 각 권역에 속한 시도 지역에 대해서도 그 상대비율들을 계산하여 지역별로 비교분석하였다.

• 서비스연구
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• 제2권2호
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• pp.23-33
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• 2012

서비스업에서의 고용률 및 전체 고용률에 대한 상대비율이 최근 수년 동안 매우 많이 변화되었다. 이러한 변화는 지역적으로 매우 큰 차이를 보이고 있으며 특히, 수도권 지역과 수도권 이외 지역과의 차이가 매우 크게 나타나고 있다. 본 연구의 주요 결과로서 서비스업에서의 평균 고용률은 수도권이 가장 높은 것으로 나타났다. 그리고 서비스업에서 고용률의 시기별 변화는, 수도권은 지속적으로 개선되는 추세를 보인 반면에 수도권 이외의 지역은 서로 다른 양상이 나타나고 있다. 또한, 서비스업에서 고용률의 상대비율은 수도권과 강원권이 다른 권역에 비해 상대적으로 가장 높게 나타나고 있으며 시기별 변화도 이 두 권역이 다른 권역에 비해 상대적으로 증가하는 추세를 보이고 있다. 마지막으로 서비스업에서의 평균 고용률이나 상대비율을 시도별로 비교해 보면 광역시가 도 지역에 비해 상대적으로 높게 나타나고 있으나, 시기별 변화를 비교해 보면 각 권역마다 서로 다른 양상을 보이는 것으로 나타났다.