• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.390-390
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• 2022

도시 생활용수 수요는 생활 수준 향상, 도시화 등으로 지속적 증가 추세에 있으며, 최근 기후변화, 시설 노후화, 도시화, 그리고 수질 오염 등의 문제들에 직면해 있다. 이는 물 부족을 심화시켜 현행 상수도시스템에서 한정적인 수자원을 배분하는데 어려움을 가중시킨다. 이를 해결하기 위해 스마트워터그리드 기술이 상수도시스템에 도입이 되면서 지능형 상수도 계량기를 이용한 개별 소비자들의 물 소비량 자료를 보다 정밀하게 실시간으로 모니터링 할 수 있게 되었다. 실시간 실측을 바탕으로 한 물 소비량 자료는 미래 용수 수요 예측과 수운영 관리에 도움을 줄 수 있다. 한편 생활용수는 용도 또는 요금 부과 기준에 따라 가정용, 업무용, 영업용, 욕탕용, 그리고 공업용으로 분류할 수 있다. 미국과 호주 등에서는 용도 분류에 따른 모니터링 강화로 절수 방안을 개발하여 물 부족에 대비하고 있다. 우리나라도 비 가정용수(가정용수를 제외한 용수들)를 체계적으로 분류하기 위한 선행 연구들이 이뤄졌으나 분류체계가 표준화되지 않았는데, 이는 용도에 따른 개별 소비자들의 소비 특성 분석이 충분히 선행되지 않았기 때문이며, 아직까지 많은 지자체에서 물 소비량을 월 단위로 인력검침 하는데 의존하고 있어, 충분한 물 소비량 자료가 부족했기 때문이다. 본 연구에서는 영종도 112 블록에 구축된 스마트워터그리드 파일롯플랜트 527개 개별 소비자들로부터 2018년 1월 1일부터 2020년 1월 1일까지 1시간단위로 수집된 물 소비량 자료를 이용하여, 개별 소비자들의 일평균 첨두 소비량과 발생 시간, 관경, 요일, 계절에 따른 물 수요 특성 분석을 수행했다. 이 때 수집된 자료의 결측치 및 오측치를 보정하여 자료의 신뢰성을 높이고자 했다. 분석결과는 용도별 물 수요 특성을 보다 잘 이해할 수 있게 도와주며, 비가정용수의 용도별 분류에 기초자료로 사용될 수 있을 것이라 사료된다.

• Journal of the Korean Geographical Society
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• v.48 no.6
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• pp.879-896
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• 2013

The assessed land values and housing prices have been widely utilized as a basic information for the land and house trades and for evaluating governmental and local taxes. However, there exists a price difference in actual markets between the assessment level and assessed land values or housing prices. This paper emphasizes the spatial mismatch between the assessed land values and housing market prices and particularly addresses the following two aspects by focusing on spatial effects of the modifiable areal units, which would substantially affect the estimation of the assessed land values and housing prices. First, we examine the spatial distributions of the assessed land values and housing market prices, and the gap between those prices, on the basis of the aggregated spatial units(i.e., aggregation districts). Second, we explore the scale effect of the MAUP(modifiable areal unit problem) generally embedded in estimating the prices of the sampled standard lands and houses, and calibrating the correction index for the land values and housing prices for the individuals. For the application, we analysed the land values and housing prices in Seoul utilizing GIS and statistical software. As a result, some spatial clusters that the housing market prices are significantly higher than the assessed land values were identified at a finer geographic level. Also, it was empirically revealed that the statistical results from the regression of regional variables on the assessed land values for the individuals are significantly affected by the aggregation levels of the spatial units.

• Journal of the Korean Geotechnical Society
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• v.24 no.2
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• pp.67-75
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• 2008

It is interesting to note that distinct element method has been used extensively to model the response of micro and discontinuous behavior in geomechanics. Impressive advances related to response of distinct particles have been conducted and there were difficulties in considering fluid effect simultaneously. Current distinct element methods are progressively developed to solve particle-fluid coupling focused on fluid flow through soil, rock or porous medium. In this research, numerical simulations of fluid injection into particulate materials were conducted to observe cavity initiation and propagation using distinct element method. After generation of initial particles and wall elements, confining stress was applied by servo-control method. The fluid scheme solves the continuity and Navior-Stokes equations numerically, then derives pressure and velocity vectors for fixed grid by considering the existence of particles within the fluid cell. Fluid was injected as 7-step into the assembly in the x-direction from the inlet located at the center of the left boundary under confining stress condition, $0.1MP{\alpha}\;and\;0.5MP{\alpha}$, respectively. For each simulation, movement of particles, flow rate, fluid velocity, pressure history, wall stress including cavity initiation and propagation by interaction of flulid-paricles were analyzed.

• Journal of Korean Society of Transportation
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• v.29 no.3
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• pp.73-82
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• 2011

Recent advancement in traffic surveillance systems has allowed the researchers to obtain more detailed vehicular movement such as individual vehicle trajectory data. Understanding the characteristics of interactions between leading and following vehicles in the traffic flow stream is a backbone for designing and evaluating more sophisticated traffic and vehicle control strategies. This study proposes a methodology for estimating rear-end crash potential, as a probabilistic measure, in real-time based on the analysis of vehicular movements. The methodology presented in this study consists of three components. The first predicts vehicle position and speed every second using a Kalman filtering technique. The second estimates the probability for the vehicle's trajectory to belong to either 'changing lane' or 'going straight'. A binary logistic regression (BLR) is used to model the lane-changing decision of the subject vehicle. The other component calculates crash probability by employing an exponential decay function that uses time-to-collision (TTC) between the subject vehicle and the front vehicle. The result of this study is expected to be adapted in developing traffic control and information systems, in particular, for crash prevention.

• Broadcasting and Media Magazine
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• v.8 no.3
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• pp.40-52
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• 2003

T-Commerce는 한 마디로 TV를 통한 e-commerce이다. 그러나 단어가 주는 간단함과는 달리 기존의 e-commerce나 m-Commerce가 가졌던 전통적 상거래 개념으로부터의 혁명성을 한 차원 더 뛰어넘는 엄청난 잠재력과 변화력을 가지고 있는 새로운 개념이자 현상이다. 즉, e-commerce가 갖고 있는 개별성, 즉시성, 상호작용성, 다매체성의 장점 위에 욕구의 충동성, 편의성 및 고감도성이 결합된 새로운 경제문화행위 방식이라 할 수 있다. 우리에게 너무도 친숙한 TV방송의 디지털화를 통한 방송과 통신의 융합현상으로 방송 산업의 형태도 빠르게 변화되고 있다. 이러한 시장의 확대는 데이터 방송의 양방향 서비스인 T-Commerce에 대한 새로운 서비스를 가능하게 하는 기술과 성공적인 사업모델에 대한 실질적인 준비가 전제되어야만 가능하다. 본 고에서는 T-Commerce 비즈니스 모델과 전략에 따른 기술에 관하여 논하고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12A
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• pp.1171-1180
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• 2010

In wireless sensor networks, reliable event detection is one of the most important research issues. For the reliable event detection, previous works usually assume the events are only individual objects such as tanks and soldiers. Recently, many researches focus on detection of continuous objects such as wild fire and bio-chemical material, but they merely aim at methods to reduce communication costs. Hence, we propose a reliable continuous object detection scheme. However, it might not be trivial. Unlike individual objects that could be referred as a point, a continuous object is shown in a dynamic two-dimensional diagram since it may cover a wide area and it could dynamically alter its own shape according to physical environments, e.g. geographical conditions, wind, and so on. Hence, the continuous object detection reliability can not be estimated by the indicator for individual objects. This paper newly defines the reliability indicator for continuous object detection and proposes an error recovery mechanism relying on the estimation result from the new indicator.

• Journal of Korean Society of Transportation
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• v.28 no.5
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• pp.31-41
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• 2010

The objective of this paper is to evaluate production efficiency of the commercial road freight transportation industry using quarterly actual data by individual truck drivers from January 2005 to September 2009. In addition, this study analyzes various impact factors that influence production efficiency, including regulatory factors (e.g., entrust management system and multi-level transactions). For this purpose, this study uses data envelopment analysis and a truncated Tobit model. As a result, production efficiency of the general freight sector is higher than those of the other two sectors. Also, production efficiency in the steel goods sector ranks the highest; meanwhile, production efficiency in the oil goods sector ranks the lowest. In particular, production efficiency indicators of the commercial road freight transportation industry fluctuate with time by a small margin, and have an upward tendency on the whole. Finally, some policy implications are given to promote production efficiency of the commercial road freight transportation industry.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.39-42
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• 2003

The issues on the interconnection of telecommunications network are recently prevailed in the IT industry. In this study, we classify the network interconnection system into two categories: two way-same price model and two way-different price model. The purpose of this paper is to analyze economic characteristics of optimal settlement system according to each model. One of the most important policy implications we derive through this study is that symmetry between enterprises is required for policy maker or regulatory agency to set an efficient settlement system under two way-same price model, but that symmetry is not necessarily required under two way-sane price model.

• Proceedings of the Korea Technology Innovation Society Conference
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• 2003.11a
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• pp.41-53
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• 2003

The issues on the interconnection of telecommunications network are recently prevailed in the IT industry. In this study, we classify the network interconnection system into two categories: two way-same price model and two way-different price model. The purpose of this paper is to analyze economic characteristics of optimal settlement system according to each model. One of the most important policy implications we derive through this study is that symmetry between enterprises is required for policy maker or regulatory agency to set an efficient settlement system under two way-same price model, but that symmetry is not necessarily required under two way-same price model.

• Progress in Medical Physics
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• v.20 no.4
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• pp.277-289
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• 2009

Recently, functional MRI has been used to investigate the neurobiological mechanisms of acupuncture and the specificity of acupoint. The group data tend to be regarded as more important than the individual data in the most of previous studies. This study was designed to investigate the effect of the variability of individual data on the group results. A functional MRI (fMRI) of the whole brain was performed in fifteen healthy subjects during placebo and acupuncture stimulations at the ST36 acupoint. After remaining at rest for 30 seconds, the acupuncture was inserted and twisted at the rate of 2 Hz for 45 seconds and then the acupuncture was removed immediately. This process was repeated three times. Individual and group analyses were performed by voxel-based analyses using SPM2 software. Visual inspections of the activation and deactivation maps from individual sessions have shown the large variability across fifteen subjects. This means that the group data reflected the brain activation responses of only a few subjects. We suggest that the individual data should be presented to demonstrate the effect of acupuncture.