• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.253-260
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• 2004

Many scholars and researchers has been studied for many kinds of soil characteristics, but a lot of part are still unsolved. Cyclic load-induced decreasing characteristics of strength and stiffness of soils are also well not known among them. To know that, the characteristics of five kinds of soils; clay, plastic and non-plastic silt, sand, and a weathered soil are compared with dividing two types as plastic or non-plastic soils through direct simple shear(DSS) test. From the results of DSS test, it is known that decreasing characteristics of strength and stiffness are different according to soil types. The strength of plastic and non-plastic soils increases with increment of plasticity index and decrement of volume decrease potential, respectively. And the decreasing stiffness of plastic and non-plastic soils increases with decrement of plasticity index and increment of volume decrease potential, respectively.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.105-111
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• 2000

If a saturate sand is subjected to ground vibrations it tends to compact and decrease in volume. if drainage is unable to occur the tendency to decrease in volume results in an increase in pore water pressure and if the pore water pressure build up to the point at which it is equal to the overburden pressure the effective stress becomes zero the sand loses its strength completely. This phenomenon is called "Liquefaction" It is associated primarily but not exclusively with saturated cohesion soils. The attention and study on liquefaction have been growing since the earthquake in Niigita Japan in 1964. Many researchers on liquefaction effect have been carried out in many countries under the potential influence of earthquake including Japan. However little research on liquefaction has been reported in Korea because Korea has been considered to be safe from earthquake. The term "liquefaction" is only known among geotechnical engineers,. In this paper overview of liquefaction and the evaluation on the applicability of vibrated crushed-stone pile as a liquefaction prevention method are presented.ethod are presented.

• 한국농림기상학회지
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• 제6권1호
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• pp.18-23
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• 2004

본 연구는 우리나라 중부지방의 소나무 천연 임분을 대상으로 입지환경별 생장 및 수분생리 특성을 파악하여 합리적인 경영방안을 제시하기 위하여 수행되었다. 연구 대상지의 소나무림은 평균 206.5㎥/ha을 나타냈으며, 각 방위별로 본수, 단면적, 재적 등의 임분 통계량을 보면 북사면에서 남사면으로 갈수록 증가하는 경향을 보이고 있지만 연년생장량과 10년 간의 정기평균 생장량은 반대로 남사면에서 가장 낮은 값을 나타내고 있다. 오후 12∼14시 사이에 측정된 최대 수분포텐셜(Ψ$_{w}$)을 각 방위 및 고도별로 구분하며 분석한 결과 소나무는 북사면에서 남사면으로 가면서 수분포텐셜이 낮아지는 경향을 보였으며, 고도별 수분포텐셜은 상부에서 하부로 가면서 증가하였다. 각 방위별 토양 수분함량은 북사면에서 남사면으로 가면서 감소하는 경향을 나타냈고, 토양 수분함량에 따른 소나무의 수분포텐셜은 고도의 음의 상관관계를 나타냈다. 따라서 연구 대상지의 소나무는 남사면과 능선에서 수분 요구도가 높은데, 이는 이곳에서의 많은 증발량에 따른 수분 결핍에 의한 종내 수분 경쟁의 결과로 판단된다..

• Geomechanics and Engineering
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• 제15권6호
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• pp.1135-1141
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• 2018

Volume changes of soils induced by inorganic acids cause severe foundation and superstructure failures in industrial buildings. This study aimed to assess the potential of fly ash to control volume changes in soils under acidic environment. Two soils such as black cotton soil predominant with montmorillonite and kaolin clay predominant with kaolinite were used for the present investigation. Both soils exhibited an increase in swelling subjected to phosphoric acid contamination. Ion exchange reactions and mineralogical transformations lead to an increase in swelling and a decrease in compressibility in black cotton soil, whereas phosphate adsorption and mineral dissolution lead to an increase in swelling and compressibility in case of kaolin clay. Different percentages of Class F fly ash obtained from Ramagundam national thermal power station were used for soil treatment. Fly ash treatment leads to significant reduction in swelling and compressibility, which is attributed to the formation of aluminum phosphate cements in the presence of phosphoric acid.

• 한국지반환경공학회 논문집
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• 제8권4호
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• pp.57-65
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• 2007

토목구조물의 안정성에 영향을 미치는 인자 중 지진에 의한 피해를 들 수가 있다. 최근의 지진 피해 사례를 분석하여 보면 모래와 같은 조립토뿐만 아니라 점성토, 실트 등과 같은 세립토에서도 크고 작은 피해 사례가 보고되고 있다. 이에 본 연구에서는 지진에 의한 기초지반의 강도저하를 평가하는 방법을 조사하기 위하여, 반복단순전단시험기를 이용하여 비배수상태에서 조립토 및 세립토에 반복하중을 작용시켜 지반의 강도저하특성을 조사하고 조립토의 경우에는 여유간극비, 세립토의 경우에는 소성지수를 이용하여 간단한 평가방법을 제안하였다. 분석결과에 따르면 액상화강도를 비교 분석하여 보면 조립토에서는 여유간극비의 증가에 따라 감소하고, 세립토의 경우에는 소성지수가 증가함에 따라 커지는 것을 알았다. 특히, 화강풍화토는 Collapse현상이 발생하여 다른 흙보다 현저한 강도 감소 경향이 나타났다. 간이강도저하 평가방법을 통해서 조립토와 세립토 거의 대부분이 양대수곡선상에서 -0.15 ~ -0.2의 범위내의 비슷한 기울기 내에서 분포하였지만, 화강풍화토와 같은 흙은 강도저하 경향이 -0.3으로 다른 흙보다 크게 나타남을 알 수 있었다. 본 강도저하 평가방법은 추가 연구가 필요하지만, 실무에서 간단하게 적용 가능할 것으로 보인다.

• Journal of Forest and Environmental Science
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• 제24권3호
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• pp.165-169
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• 2008

This study attempts to analyze the relationship between forest volume and age based on 5th NFI data and spectral characteristics of satellite imagery using ASTER sensor in Korea. Forest stand volume and age had the negative correlation with the spectral reflectance in all of the band (Blue, Green, Red, SWIR). With increasing of stand volume and age, spectral reflectance decrease. The spectral reflectance of band1 showed the highest correlation between stand volume and spectral reflectance among the VNIR wavelength. The spectral reflectance band 1, 2 (visible wavelength) and stand age have high correlation compared to other bands. The correlation coefficients between forest volume and vegetation indices have low relationship. This result indicates that the reflectance of blue band may be important factor to improve the potential of optical remote sensing data to estimate forest volume and age.

• International Journal of Oral Biology
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• 제34권3호
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• pp.151-155
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• 2009

The role of $Cl^-$ channels in regulatory volume decrease (RVD) in human salivary gland acinar cells was examined using a whole-cell patch clamp technique. Human tissues were obtained from healthy volunteers or from patients with oromaxillofacial tumors. During the measurements, $K^+$-free solutions were employed to eliminate contamination of whole-cell conductance by $K^+$ currents. When the cells were exposed to a 70% hypotonic solution, outward-rectifying currents, which were not observed in the resting state, were found to have significantly increased both in human labial and parotid gland acinar cells. The amplitudes of the currents were reduced in a low $Cl^-$ bath solution. Furthermore, the addition of $100{\mu}M$ 5-Nitro-2- (3-phenyl propylamino) benzoic acid (NPPB) or $100{\mu}M$ 4,4'-diisothio cyanatostilbene-2,2'-disulphonic acid (DIDS), known to partially block $Cl^-$ channels, significantly inhibited these currents. Its outward-rectifying current profile, shift in reversal potential in a low $Cl^-$ bath solution and pharmacological properties suggest that this is a $Ca^{2+}$-independent, volume activated $Cl^-$ current. We conclude therefore that volume activated $Cl^-$ channels play a putative role in RVD in human salivary gland acinar cells.

• 한국농림기상학회지
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• 제5권4호
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• pp.233-237
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• 2003

본 연구는 우리나라 중부지방의 굴참나무 천연 임분을 대상으로 입지환경별 생장 및 수분생리 특성을 파악하여 합리적인 경영방안을 제시하기 위하여 수행되었다. 연구 대상지의 굴참나무림은 평균 206.5 ㎥/ha을 나타냈으며, 각 방위별로 본수, 단면적, 재적 등의 임분 통계량을 보면 북사면에서 남사면으로 갈수록 증가하는 경향을 보이고 있지만 연년생장량과 10년간의 정기평균 생장량은 반대로 남사면에서 가장 낮은 값을 나타내고 있다. 오후 12∼14시 사이에 측정된 최대 수분포텐셜(Ψw)을 각 방위 및 고도별로 구분하여 분석한 결과 굴참나무는 북사면에서 남사면으로 가면서 수분포텐셜이 낮아지는 경향을 보였으며, 고도별 수분포텐셜은 상부에서 하부로 가면서 증가하였다. 각 방위별 토양 수분함량은 북사면에서 남사면으로 가면서 감소하는 경향을 나타냈고, 토양 수분함량에 따른 굴참나무의 수분포텐셜은 고도의 음의 상관관계를 나타냈다. 따라서 연구 대상지의 굴참나무는 남사면에서 수분 요구도가 높은데, 이는 다른 사면 보다 생육 본수가 많아 종내 경쟁이 심한 결과로 판단된다.

• Radiation Oncology Journal
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• 제36권3호
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• pp.235-240
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• 2018

Purpose: We describe the daily bladder volume change observed by mega-voltage computed tomography (MVCT) during pelvic radiotherapy with potential predictors of increased bladder volume variations. Materials and Methods: For 41 patients who received pelvic area irradiation, the volumes of bladder and pelvic body contour were measured twice a day with pre- and post-irradiation MVCT from the 1st to the 10th fraction. The median prescription dose was 20 Gy (range, 18 to 30 Gy) up to a 10th fraction. The upper and lower margin of MVCT scanning was consistent during the daily treatments. The median age was 69 years (range, 33 to 86 years) and 10 patients (24.4%) were treated postoperatively. Results: Overall bladder volume on planning computed tomography was 139.7 ± 92.8 mL. Generally, post-irradiation bladder volume (POSTBV) was larger than pre-irradiation bladder volume (PREBV) (p < 0.001). The mean PREBV and POSTBV was reduced after 10 fraction treatments by 21.3% (p = 0.028) and 25.4% (p = 0.007), respectively. The MVCT-scanned body contour volumes had a tendency to decrease as the treatment sessions progressed (p = 0.043 at the 8th fraction and p = 0.044 at the 10th fraction). There was a statistically significant correlation between bladder filling time and PREBV (p = 0.001). Conclusion: Daily MVCT-based bladder volume assessment was feasible both intra- and inter-fractionally.

• 한국지하수토양환경학회지:지하수토양환경
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• 제26권6호
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• pp.95-105
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• 2021

Extensive groundwater abstraction has been recognized as one of the major challenges in management of coastal groundwater. The purpose of this study was to assess potential changes of groundwater distribution of northeastern Jeju Island over 10-year duration, where brackish water have been actively developed. To quantitatively estimate the coastal groundwater resources, numerical simulations using three-dimensional finite-difference density-dependent flow models were performed to describe spatial distribution of the groundwater in the aquifer under various pumping and recharge scenarios. The simulation results showed different spatial distribution of freshwater, brackish, and saline groundwater at varying seawater concentration from 10 to 90%. Volumetric analysis was also performed using three-dimensional concentration distribution of groundwater to calculate the volume of fresh, brackish, and saline groundwater below sea level. Based on the volumetric analysis, a quantitative analysis of future seawater intrusion vulnerability was performed using the volume-based vulnerability index adopted from the existing analytical approaches. The result showed that decrease in recharge can exacerbate vulnerability of coastal groundwater resources by inducing broader saline area as well as increasing brackish water volume of unconfined aquifers.