• 한국수자원학회논문집
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• 제43권1호
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• pp.1-13
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• 2010

본 연구에서는 배수경로 이질성에 의한 격자 기반 지형학적 순간단위도 이론으로 부터 Nash 모형 매개변수를 최초로 동정하였다. 동정된 매개변수는 지표면 유동 및 지형학적 분산을 고려하며, 지리정보체계에 의해 유역의 지형인자들을 손쉽게 추출함으로써 모형의 정확성 및 효용성을 높였다는 점에 의미를 둘 수 있다. 모형의 검증을 위해 동정된 매개변수에 의해 계산된 결과를 실제 관측치와 비교하였다. 계산유출수문곡선과 관측수문곡선의 비교 결과 비교적 잘 일치하는 경향을 보였다. 또한 지표면과 하천의 특성유속에 따른 지체시간 및 분산의 변화양상을 살펴본 결과, 지표면 특성유속에 매우 민감하게 반응함을 알 수 있었다. 따라서 본 모형의 적용시 지표면 특성유속 산정에 세심한 주의가 필요할 것으로 판단된다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제15권6호
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• pp.17-28
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• 2010

As a preliminary survey to improve efficiency of well-based permeable reactive barrier system for groundwater remediation, this site-scale study was carried to identify the flowpaths and controlling factors of plume at a remediation site in Suwon City, Korea. A total of 22 monitoring wells were installed as a grid system in the $4m{\times}4m$ square area by 1-m interval. For the groundwater characterization, various tests were performed including water-level monitoring, water sampling & analysis, pumping and slug tests, and tracer tests. The aquifer appeared to be unconfined with hydraulic conductivities (K) ranging from $2.6{\times}10^{-4}cm/s$ to $9.5{\times}10^{-3}cm/s$. The average linear velocity of groundwater was estimated to be $2.94{\times}10^{-6}m/s$, and the longitudinal dispersivity of a conservative tracer to be $5.94{\times}10^{-7}m^2/s$. Groundwater plume moves preferentially through the high-K zones, and the relatively high ion concentrations along the low-K zones implying deterred groundwater flow. Consequently, the spatial variation of hydraulic conductivity caused by aquifer heterogeneity and anisotropy appears to be the most important factor to maximize the effect of plume treatment system for application of in-situ groundwater remediation techniques.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 춘계학술대회
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• pp.294-296
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• 2017

클라우드 컴퓨팅은 클라우드 노드에서 발생하는 모든 데이터를 클라우드 서버에 업로드하여, 서비스로서 사용자에게 제공하는 역할을 수행하는 컴퓨팅 기법이다. 이는 네트워크의 상황에 따라 실시간으로 서비스를 제공하기에는 어렵다. 그것은 로컬의 영역이 아니라 네트워크를 통하여 원격지로 정보를 전송하고, 클라우드에서 서비스를 제공하기 위해 추가적으로 다운로드를 해야 하기 때문이다. 이에 대한 대안으로 포그 컴퓨팅이 제안되었다. 본 논문에서는 클라우드, 포그 그리고 사용자 간의 효율적인 데이터 교환 기법을 제안하고자 한다. 제안된 포그는 사용자에게 서비스를 제공하고, 데이터를 수집하여 처리하도록 한다. 클라우드는 포그 간의 데이터 교환과 제어의 흐름을 담당하도록 한다. 우리는 이에 대한 데이터의 교환에 필요한 표준 방식을 제안한다. 이를 위한 적용은 BAN(Body Area Network)에서 발생하는 정보를 포그에서 처리 및 서비스를 하고, 클라우드는 중재 역할을 수행하는 시스템으로 한다. 이는 기기 또는 서비스 간에서 발생하는 데이터 이질성을 해결하고, 효율적인 데이터 이동을 제공할 수 있다.

• 한방재활의학과학회지
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• 제31권1호
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• pp.149-163
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• 2021

Objectives This study is to review the effectiveness of exercise after lung cancer surgery. Methods Relevant randomized controlled trials (RCTs) were searched in PubMed database. The systematic review was conducted through flow diagram. The risk of biases were assessed through the Cochrane guideline. Characteristics and outcomes were extracted from each study. Meta-analyses of forced expiratory volume in one second (FEV1), 6-minute walk test (6MWT), quality of life (QoL), pulmonary complications were conducted. Results 14 RCTs were selected. In meta-analysis, exercise improved FEV1 (mean difference [MD] 0.14; 95% confidence interval [CI] 0.04 to 0.25; p=0.009; I2=55%) and mean change of FEV1 (MD 0.11; 95% CI 0.02 to 0.20; p=0.02; I2=0%). Exercise increased the distance of 6MWT, but there was considerable heterogeneity (MD 45; 95% CI 21.16 to 68.83; p=0.0002, I2=89%). There was no differences in QoL scores by 2 questionnaires (European Organisation for Research and Treatment of Cancer quality of life questionnaire, short form-36). Exercise reduced the duration of hospital stay (MD -3.32; 95% CI -5.27 to -1.36; I2=0%; 2 studies) but not duration of chest tube intubation (MD -1.37; 95% CI -2.81 to 0.06; I2=0%) and incidence of pulmonary complications (pooled risk ratio 0.54; 95% CI 0.23 to 1.30; I2=0%). Conclusions Exercise might reduce the duration of hospital stay after lung surgery. There was not enough evidence to prove improvement of lung function, aerobic capacity, muscle strength, QoL, and decline of pulmonary complications. Low-quality risk of bias, different units or estimation of outcome, different exercise type and duration, heterogeneity among studies make the evidence of effectiveness weak. Future researches are required to redeem these defects.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.789-796
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• 2003

A reliability analysis is performed to investigate the influence of the uncertainty from the limited in-situ samples and the inherent heterogeneity of the ground on the probability of piping for the marine embankment near shore. The result are compared with those of the deterministic piping stability analysis performed using the fininte element flow analysis. The random variables used are hydraulic conductivity of the ground subsurface and embankment, and the water level of both internal and external side of the embankment. The probability of piping is most sensitive to the mean and standard deviation of internal water level of the embankment among the random variables included in the reliability analysis. It is found that the lower limits of internal water level which satisfies the allowable proability of piping failure for the embankment studied were E.L(-) 1.83m and E.L(-) 1.48m during and after the construction of the embankment, respectively.

• 한국환경과학회지
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• 제29권1호
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• pp.15-23
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• 2020

The determination of soil characteristics is important in the simulation of rainfall runoff using a distributed FLO-2D model in catchment analysis. Digital maps acquired using remote sensing techniques have been widely used in modern hydrology. However, the determination of a representative parameter with spatial scaling mismatch is difficult. In this investigation, the FLO-2D rainfall-runoff model is utilized in the Yongdam catchment to test sensitivity based on three different methods (mosaic, arithmetic, and predominant) that describe soil surface characteristics in real systems. The results show that the mosaic method is costly, but provides a reasonably realistic description and exhibits superior performance compared to other methods in terms of both the amount and time to peak flow.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2006년도 총회 및 춘계학술발표회
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• pp.282-285
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• 2006

This study is to present the method for estimating groundwater recharge with temporal-spatial variability using the SWAT model which can represent the heterogeneity of the watershed. The SWAT model can simulate daily surface runoff, evapotranspiration, soil storage, recharge, and groundwater flow within the watershed. The model was applied to Musimcheon watershed located in the upstream of Mihocheon watershed. Hydrological components were determined for the period 2001 - 2004, and the validity of the results was tested by comparing the estimated runoff with the observed runoff data at the outlet of the catchment. The results of temporal and spatial variations of recharge were presented, This study suggests that variations in recharge can be significantly affected by subbasin slope as well as land use changes.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2002년도 학술발표회 논문집(II)
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• pp.1027-1033
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• 2002

The solute transport in a two-dimensional heterogeneous porous medium is numerically studied by using a random walk particle tracking (RWPT) method. Lognormally isotropic hydraulic conductivity fields are generated by using the turning band methods with mean zero and four different values of standard deviation. The numerical transport experiments are carried out to investigate the large time and spatial effects of the variable pore velocity field on solute plumes. The behavior of the solute plume through numerical simulations is presented in terms of longitudinal and transverse spatial moments: displacement of center-of-mass, plume spread variance and skewness coefficient. It was observed that the dispersive behavior of the solute plume is strongly affected by the degree of heterogeneity in the flow domain.

• ETRI Journal
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• 제46권3호
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• pp.513-525
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• 2024

Deep neural networks trained on labeled medical data face major challenges owing to the economic costs of data acquisition through expensive medical imaging devices, expert labor for data annotation, and large datasets to achieve optimal model performance. The heterogeneity of diseases, such as Alzheimer's disease, further complicates deep learning because the test cases may substantially differ from the training data, possibly increasing the rate of false positives. We propose a reconstruction-based self-supervised anomaly detection model to overcome these challenges. It has a dual-subnetwork encoder that enhances feature encoding augmented by skip connections to the decoder for improving the gradient flow. The novel encoder captures local and global features to improve image reconstruction. In addition, we introduce an entropy-based image conversion method. Extensive evaluations show that the proposed model outperforms benchmark models in anomaly detection and classification using an encoder. The supervised and unsupervised models show improved performances when trained with data preprocessed using the proposed image conversion method.

• 한국지반공학회논문집
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• 제28권12호
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• pp.65-76
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• 2012

본 연구에서는 수리구조물이 설치된 2층으로 이루어진 포화 기초지반에서의 구속흐름(confined flow)에 대하여 확률론적 침투해석을 수행하였다. 투수계수는 지반의 층상구조에 따라 명확한 변동성을 보일 뿐 아니라 각각의 층 내에서도 공간적인 변동성을 보인다. 따라서 기존의 결정론적 침투해석기법을 층상지반에서의 투수계수의 불확실성과 공간적 변동성을 고려할 수 있도록 확률론적 해석으로 확장하였다. 각 층에 지정된 입력 확률분포함수와 자기상관함수(autocorrelation function)를 따르는 2차원의 랜덤필드를 생성하기 위하여 Karhunen-Lo$\grave{e}$ve 전개법을 사용하였다. 제안된 절차의 적용성을 검토하고 수리구조물 하부의 2층 지반을 통한 흐름에 공간적 불균질성이 미치는 영향을 연구하기 위해 생성된 랜덤필드를 이용하여 Monte Carlo 시뮬레이션을 수행하였다. 해석결과는 층상지반에서의 침투거동 평가에서 지반의 층상구조와 지층내에서의 투수계수의 공간적 변동성에 의한 지반에서의 다양한 침투패턴을 확률론적 해석기법을 통하여 효율적으로 고려할 수 있음을 보여주었다.