• Journal of Korea Water Resources Association
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• v.34 no.5
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• pp.533-542
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• 2001

In order to establish drought policy, the estimation of drought period for each drought situation should be preceded. Non-linear Water Balance Model(NWBM) and palmer Drought Severity Index (PDSI) can be used for analysis of drought period. As a water balance method considering moisture transfer between land surface and atmosphere, NWBM can be used to estimate transition time between dry and wet period induced by stochastic fluctuations. PDSI is also water balance method to show drought severity comparing actual precipitation with climatically appropriate precipitation based on precipitation and potential evapotranspiration. In this study, the drought periods are estimated using NWBM and PDSI for the Han River Basin. The drought periods according to the soil moisture estimated by NWBS and the drought periods according to drought severity index estimated by PDSI show similar trend. The estimated drought period from extreme drought to wet condition for the Han River Basin is about 3years.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.1
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• pp.49-57
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• 2008

One of the most important design concerns for undersea tunnels is to establish design water load and flow rate. These are greatly dependent on the hydraulic factors such as water head, cover depth, hydraulic boundary conditions. In this paper, the influence of the hydraulic design factors on the ground loading and the inflow rate was investigated using the coupled finite element method. A horse shoe-shaped tunnel constructed 30 m below sea bottom was adopted to evaluate the water head effect considering various water depth for varying hydraulic conditions and relative permeability between lining and ground. The effect of cover depth was analysed for varying cover depth with the water depth of 60 m. The results were considered in terms of pore water pressure, ground loading and flow rate. Ground loading increases with an increase in water head and cover depth without depending on hydraulic boundary conditions. This points out that in leaking tunnels an increase in water depth increases seepage force which consequently increases ground loading. Furthermore, it is identified that an increase in water head and cover depth increases the rate of inflow and a decrease in the permeability ratio reduces the rate of inflow considerably.

• Geophysics and Geophysical Exploration
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• v.10 no.3
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• pp.211-218
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• 2007

In this study, vertical electrical sounding (VES) data and ordinary kriging are used to identify the alluvial depth of each area that Korea Resources Corporation (KORES) conducted groundwater survey at Miryang area in Gyeongsangnam-do and Pocheon area in Gyeonggi-do from 2003 to 2004. To verify the applicability of VES data to ordianry kriging, regression analysis of VES data versus drillhole data is conducted. Comparing the alluvial depth distributions using ordinary kriging with existing drillhole data, the result shows that the depth distributions are reasonably depicted along with the topography and the basin. So, the ordinary kriging of VES data is useful to identify the alluvial depth distributions.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1944-1945
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• 2011

본 논문은 심도각 범위를 고려한 무인 잠수정(autonomous underwater vehicles: AUVs)의 타카키-수게노 (Takagi-Sugeno: T-S) 퍼지 모델 기반 강인 심도 제어기의 설계 기법을 제안한다. 무인 잠수정의 비선형 시스템은 Sector nonlinearity 기법을 이용하여 T-S 퍼지 시스템으로 모델링된다. 리아푸노프(Lyapunov) 함수를 이용하여 무인 잠수정의 성능을 보장하는 선형 행렬 부등식(Linear matrix inequality: LMI) 형태의 강인 제어기 설계 조건은 유도된다. 또한 무인 잠수정의 심도각 범위를 고려하여 입력 및 출력에 제한 조건을 포함한다. 모의 실험을 통해 제안된 기법의 심도 제어 성능을 검증한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2322-2328
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• 2013

The aim of this study was to quantify the sedative effects of high spinal anesthesia, according to patient age, by also evaluating respiratory and hemodynamic changes. A prospective study was performed in 60 patients who were electively scheduled for lower limb or lower abdominal surgery. They were allocated into one of 2 groups according to their age: older age (51-80 years) and young age (20-50 years). In all groups, the lowest intraoperative bispectral index (BIS) values significantly lower than preoperative values. Patients in the older age group had significantly lower intraoperative BIS values than younger patients. The sedative effect of high spinal anesthesia is greater in older patients than in young patients, with an increase in respiratory instability. Our study showed a negative correlation between age and lowest BIS value; the lowest BIS value was reduced in older patients.

• Geophysics and Geophysical Exploration
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• v.3 no.3
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• pp.88-93
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• 2000

The present study may be summarized as follows. By means of a pole-pole electrical survey, major geological features, i.e, fresh rocks, fractured & weak & saturated rocks, fresh water bearing aquifer, were successfully delineated in the surveyed area of a granite region in Korea. The subsequent Schlumberger sounding and drilling confirmed the existence of the acquifer at 60 m depth as expected. But one more minor acquifer which does not show up in the resistivity depth section was met at 100 m depth. A simple forward modelling leads the authors to believe that any other electrode configuration, e.g., Wenner, Schlumberger, dipole-dipole, pole-dipole, would not detect the deeper aquifer. Under these circumstances, further studies remain to be done in connection with the spatial resolution in the vertical direction.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.319-322
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• 2002

그라우팅으로 지반 개량된 조간대 퇴적층의 지층구조를 규명하기 위한 방법으로 전기비저항탐사, 굴절법 탄성파탐사, 지하레이더탐사를 실시하였다. 연구대상 지반의 10m 전후 심도에서 해수의 영향을 받는 수평의 저비저항대가 발달하며, 저비저항대는 모래가 우세한 지층에 해당한다. 지반의 탄성파 속도는 1~3km/sec의 범위로 조간대의 미고결 퇴적층과 비교할 때 매우 높은 속도에 보여준다. 지반의 높은 속도는 지반 개량의 효과로 판단된다. 지하레이더탐사에서 퇴적층의 구성 물질에 따라 교반 정도가 달지는데 모래층은 퇴적물과 주입제의 교반이 잘 이루어져 불규칙한 반사면으로 나타나며, 점토층은 교반이 불량하여 개량된 부분은 주상으로 관찰된다. 물리탐사의 결과와 시추조사를 대비할 때 지반 개량은 기반암까지 시행되었으며, 양호한 암반을 지시하는 고비저항대와 고속도층은 내륙으로 갈수록 깊은 심도를 보여준다. 이것은 지반 개량 이전의 기반암 심도와는 상반되는 것으로 지반 개량의 효과는 해안방면의 지층에서 잘 나타난다.

• Journal of the Korea Computer Graphics Society
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• v.24 no.5
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• pp.1-10
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• 2018

In this paper, we present a non-photorealistic rendering technique that automatically delivers a stylized abstraction of a photograph with DoF(Depth of field). Our approach is a new filtering method that efficiently classifies DoF regions using RGB channels and automatically adjusts the color abstraction and extracted line quality based on this classification. This DoF-based filtering is simple, fast, and easy to implement and significantly improves the abstraction performance in terms of feature enhancement and stylization.

• Journal of Oral Medicine and Pain
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• v.24 no.4
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• pp.387-396
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• 1999

구취를 주소로 내원한 환자 중 구취의 치료 후 객관적인 구취의 감소가 인정되는 데도 불구하고, 계속해서 구취를 호소하며 만족해 하지 못하는 환자들의 심리적 특성을 알아보고자 하였다. 구취를 주소로 서울대학교 치과병원 구강진단과 구취클리닉에 내원하여 검사 및 치료를 시행한 환자 중, 치료 전 객관적 구취의 소견을 보였으나, 치료 후 할리미터 수치의 객관적인 감소를 보이는 40명의 구취 환자를 대상으로 하였다. 치료 전, 모든 환자들은 자신의 주관적 구취 심도 및 그로 인한 불편감 정도를 표시하였고, 간이정신진단검사 (SCL-90-R)를 시행하였으며 할리미터를 이용하여 구강내 휘발성황화합물의 농도를 측정하였다. 치료 후, 구강내 휘발성황화합물의 농도, 주관적 구취 심도 및 불편감 정도를 재측정하였다. 주관적 구취 심도의 감소 정도에 따라 환자들을 두 군으로 분류하여 할리미터 수치와 불편감 정도 및 간이정신진단검사항목을 비교, 분석하였다; A군-주관적 구취 심도가 평균값 이상으로 감소한 환자군; B군-주관적 구취 심도가 평균값 이하로 감소한 환자군. 1. 치료 전후 모두에서 주관적 구취 심도와 휘발성황화합물 농도 사이에는 유의한 상관관계가 없었으며 주관적 구취 심도의 감소 정도 또한 휘발성황화합물의 감소 정도와 상관관계가 없었다. 2. 치료 전 휘발성황화합물의 농도는 치료 후 휘발성황화합물의 감소치와 유의한 상관관계를 보였다 (p < 0.01). 3.구취로 인한 불편감 정도는 주관적 구취 심도와 유의한 상관관계를 보였으며 (p < 0.01), 치료 후 A군에서는 유의하게 감소 (p < 0.01) 하였으나, B군에서는 유의한 감소를 보이지 않았다. 4. B군은 A군에 비하여 간이정신진단검사 항목 중 대인예민성과 우울증의 항목에서 유의하게 높은 수치를 보였다 (p < 0.05).

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.1 s.53
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• pp.45-57
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• 2007

The mean shear wave velocity to the depth of 30 m (Vs30) derived from the western Vs is the current site classification criterion for determining the design seismic ground motion taking into account the site amplification potential. In order to evaluate the Vs30 at a site, a shear wave velocity (Vs) Profile extending to at least 30 m in depth must be acquired from in-situ seismic test. In many cases, however, the resultant depth of the Vs profile may not extend to 30 m, owing to the unfavorable field condition and the limitation of adopted testing techniques. In this study, the Vs30 and the mean shear wave velocity to a depth shallower, than 30 m (VsDs) were computed from the Vs profiles more than 30 m in depth obtained by performing various seismic tests at total 72 sites in Korea, and a correlation between Vs30 and VsDs was drawn based on the computed mean Vs data. In addition, a method for extrapolating the Vs profile from shallow depth to 30 m was developed by building a shape curve based on the average data of all Vs profiles. For evaluating the Vs30 from the shallow Vs profiles, both the methods using VsDs and shape curve result in less bias than the simplest method of extending the lowermost Vs equally to 30 m in depth, and are usefully applicable particularly in the cases of the Vs profiles extending to at least 10 m in depth.