• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.76-76
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• 2018

하천에서의 유사이송과 하상변동을 분석하는 대표적인 방법으로는 현장에서 유사량이나 하상고를 측정하여 분석하는 실측에 의한 방법, 수리모형 실험과 수치모형을 이용하는 방법이 있다. 이 중에서 실측에 의한 방법은 시간과 비용의 한계로 수치해석모형을 이용한 연구가 많이 이루어 지고 있다. 현재까지 개발된 다양한 하상변동 수치모형들은 유사이송 상태를 평형 유사이송 상태를 가정하고 개발되어 왔다. 평형 유사이송은 흐름과 하상재료 등의 조건이 발생시킬 수 있는 유사이송능력과 실제 유사이송률이 동일하다고 가정하는 것이다. 그러나, 실제 유사이송에서는 흐름 및 지형 등의 변화에 따라서 지속적으로 새롭게 형성되는 유사이송능력에 실제 유사이송률이 빠르게 도달하지 못하면서 유사이송능력과 유사이송률 사이에 시 공간의 격차가 발생하게 된다. 이러한 상황을 비평형 유사이송이라고 하며 지속적인 하상 상승 및 저하가 발생하는 구간, 댐과 같은 구조물에 의해서 유사의 연속성이 차단되는 구간, 하상재료가 불연속한 구간 등에서 주로 발생하는 것으로 알려져 있다. 비평형 유사이송을 수학적으로 모의하기 위한 대표적인 방법에는 적응거리계수와 회복계수를 이용하는 방법이 있다. 위의 계수들은 흐름 및 하상 특성을 이용하여 공간에 대한 유사이송의 지체현상을 고려하는 방법으로 이를 산정하기 위한 다양한 공식들이 제시되고 있다. 그러나, 각 공식들에 의해서 제시되는 값에 많은 차이가 있는 것으로 알려져 있다. 본 연구에서는 실내실험과 수치실험을 통해서 평형/비평형 유사이송 및 집중형/분포형 적응거리계수를 고려한 모의 결과를 비교하였으며, 적응거리계수 산정공식에 따른 비평형 유사이송 모의 결과를 비교하였다. 본 연구에서 적용한 실내실험에 대해서는 평형 유사이송보다는 비평형 유사이송을 고려한 경우와 비평형 유사이송 공식을 이용하여 적응거리계수를 분포형 매개변수로 이용하는 경우가 실제 하상변동 모의 결과에 더 근접한 수치실험 결과를 제공하는 것으로 나타났다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.657-662
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• 2009

The international society under the internet technology have been declining boundaries of the global economy. After this step, a social revolution will be happen from the ubiquitous technology which gives objects intelligence to serve people. And then it is expected that every part of a city competitive power is defined by both in quality and in quantity of the ubiquitous information unit in the future. On this score, now each nation is trying to set relative services and broadband networks to lead the ubiquitous industry. Therefore this paper analyzed about the progress and prospect of a local U-city plan in our nation. And than we propose a method of configurating broadband self-communication network on the base of cost and utilization Especially we propose a new city development model which use U-city and self-communication network to improve a city competitive power.

• Korean Journal of Remote Sensing
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• v.34 no.6_1
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• pp.1131-1142
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• 2018

The autonomous vehicles are being developed and operated widely because of the advantages of reducing the traffic accident and saving time and cost for driving. The vehicle localization is an essential component for autonomous vehicle operation. In this paper, localization algorithm based on sensor fusion is developed for cost-effective localization using in-vehicle sensors, GNSS, an image sensor and reference images that made in advance. Information of the reference images can overcome the limitation of the low positioning accuracy that occurs when only the sensor information is used. And it also can acquire estimated result of stable position even if the car is located in the satellite signal blockage area. The particle filter is used for sensor fusion that can reflect various probability density distributions of individual sensors. For evaluating the performance of the algorithm, a data acquisition system was built and the driving data and the reference image data were acquired. Finally, we can verify that the vehicle positioning can be performed with an accuracy of about 0.7 m when the route image and the reference image information are integrated with the route path having a relatively large error by the satellite sensor.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.4
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• pp.551-559
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• 2019

Since 2000, many local governments have been trying to introduce trams because of the government's failure to adopt environment-friendly policies and light rail. However, there is no service evaluation system that can maintain and enhance tram users' convenience, safety, and comfort during operation. In addition, the tram characteristics are not reflected in the application of the evaluation system of "management and service evaluation for public transportation operators" which is being implemented to railway operators or bus transportation operators. The purpose of this study is to develop the evaluation criteria of operating service according to tram operation model. First, we reviewed cases related to the evaluation of operating services in roads, buses, railways, and airways. And the evaluation criteria and the evaluation items are presented. This study is expected to help to secure and improve operational service in the operation phase of the tram that will be introduced in the future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.4
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• pp.523-530
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• 2019

Pavement distress and traffic accidents are caused by pot-hole. In addition, direct and indirect damages of road users are increasing, such as loss of life due to personal injury and damage to vehicles. Generally, the asphalt concrete pavements are continuously aging from the production process to the terminal performance period. Aging causes stripping due to cracks and moisture penetration and weakening the pavement structure to induce pot-hole. In this study, adhesion performance and moisture sensitivity were evaluated according to aging degree in order to investigate the effect of aging on asphalt pavement. As a result of the study, the viscosity of the asphalt binder was increased with aging and the bond strength of the aged was increased 2~3 times than that of the unaged. The results of accelerated aging test showed an increases in indirect tensile strength and the increase in the TSR (Tensile Strength Ratio) by 4.2~8.9 %. As a result, it is noted that the anti-stripping and adhesion performances of the aged asphalt concrete are improved compared to the unaged one under the aging conditions of asphalt binder coated on aggregates.

• Journal of the Korea Society of Computer and Information
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• v.26 no.4
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• pp.63-74
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• 2021

Location-based services (LBSs) are expected to process a large number of spatial queries, such as shortest path and k-nearest neighbor queries that arrive simultaneously at peak periods. Deploying more LBS servers to process these simultaneous spatial queries is a potential solution. However, this significantly increases service operating costs. Recently, batch processing solutions have been proposed to process a set of queries using shareable computation. In this study, we investigate the problem of batch processing moving k-nearest neighbor (MkNN) queries in dynamic spatial networks, where the travel time of each road segment changes frequently based on the traffic conditions. LBS servers based on one-query-at-a-time processing often fail to process simultaneous MkNN queries because of the significant number of redundant computations. We aim to improve the efficiency algorithmically by processing MkNN queries in batches and reusing sharable computations. Extensive evaluation using real-world roadmaps shows the superiority of our solution compared with state-of-the-art methods.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.103-103
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• 2016

최근 기후변화에 따른 집중호우로 도시홍수의 피해가 급격히 증가하고 있다. 특히 인구가 밀집하고 교통량이 많은 대도시의 경우 동일한 호우에 대하여 녹지나 농경지 등에 비해 그 피해가 더 심각하다. 일반적으로 홍수 피해의 직접원인은 외수로 인한 피해와 내수로 인한 피해로 크게 구분할 수 있다. 외수피해는 주로 소하천 및 지천의 범람, 제방의 붕괴 등으로 발생한 것이며 내수피해는 배수로, 하수도 및 펌프장의 내수배제능력 부족이 주된 원인이다. 따라서 도시홍수를 효과적으로 방어하기 위해서는 우선적으로 내배수시설의 성능개선이 선행되어야 할 필요가 있다. 이러한 내배수 시설의 성능 개선을 위해서는 현재 기 설치되어 있는 빗물펌프장의 설계 및 내배수 효율에 대한 성능평가가 필요하다. 하지만 현재 국내 펌프설계기준에는 빗물펌프장의 설계 및 운영에 대한 구체적인 성능 평가 방법이 제시되어 있지 않은 실정이다. 만약, 펌프 흡입수조 및 흡입파이프의 형상이 적절하게 설계되지 못한다면 물이 파이프 입구로 부드럽게 흡입되지 못하고 볼텍스 및 스월이 발생하게 된다. 이러한 볼텍스 및 스월은 펌프 입구 쪽으로 물 뿐 아니라 공기를 함께 흡입시킴으로써 펌프의 효율저하, 소음, 진동을 발생시키며 펌프 파손의 원인이 될 수 있다. 따라서 펌프를 설치하기 전 펌프 설치 후에 발생되는 펌프 흡입부 주변의 흐름특성 변화 및 흐름특성이 구조물에 미치는 영향 등을 고려하기 위하여 수리모형실험이 필요한데, 수리모형실험은 많은 시간과 비용이 들어가기 때문에 이를 대체할 수 있는 방안이 요구된다. 그런 이유로 최근에는 수리모형실험 대신 수치모의를 이용하는 경우가 많다. 수치모의의 결과는 수리실험의 결과와 비교, 검증을 거쳐 신뢰성을 얻는다. 본 연구에서는, 3차원 수치모형의 다양한 난류모델을 이용하여 흡입파이프로 물이 유입될 때 흡입부 내, 외의 수심 별 유속 변화를 분석하고, 그 결과를 이용하여 FLOW 3D 모형의 검증을 수행하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.2
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• pp.234-239
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• 2021

Recently, as the installation of a large number of high-performance CCTVs for crime prevention and traffic control has increased rapidly, the problem of increasing system requirements for response to privacy infringement factors and analysis of high-definition image information transmitted from multiple cameras has been actively emerging. Accordingly, there is a need for a method for responding to privacy infringement and a method for efficiently processing surveillance images input from multiple cameras. In this paper, in order to reduce the processing cost of the input image and improve the processing speed, an integrated image is generated by grouping images input from a plurality of cameras. After analyzing the pre-generated integrated video, it detects a preset privacy event or an event that highlights interest. Depending on whether or not an event is detected, you will perform an editing operation corresponding to the event.

• Korean Chemical Engineering Research
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• v.60 no.1
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• pp.34-50
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• 2022

Since the Paris climate agreement, reducing greenhouse gases has been the most important global issue. In particular, it is necessary to reduce fossil fuels in the mobility sector, which accounts for a significant portion of total greenhouse gas emissions. In this paper, we investigated the economic feasibility of green mobility energy supply chains, which supply hydrogen as fuel to hydrogen vehicles based on electricity from renewable energy sources. The design and operation costs were analyzed by evaluating nine scenarios representing various combinatorial possibilities such as renewable energy generation, hydrogen production through water electrolytes, hydrogen storage and hydrogen refueling stations. Simulation calculations were made using Homer Pro, widely used commercial software in the field. The experience gained in this study could be further utilized to construct actual hydrogen energy systems.

• Land and Housing Review
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• v.13 no.3
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• pp.69-81
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• 2022

Unplanned land use, that is, unplanned development, causes various negative externalities. In the past, Korea has experienced significant socio-economic costs due to reckless development centered on the boundary between urban and non-urban areas.. Unplanned land use can be viewed as a result of the interaction of various factors.. Therefore, it is difficult to develop in areas where unplanned land use occurs intensively. It is necessary to strengthen legal and institutional measures so that negative externalities do not persis. In this study, we present a spatial analysis methodology to effectively find spatial clusters where unplanned land use is concentrated. By demonstrating and applying this to individual development activities that occurred in Asan City, we examine the usefulness of information to support decision making when establishing mid-to-long-term growth management strategies at the local government level.