• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권6호
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• pp.1063-1079
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• 2010

Vehicle ad hoc networks (VANET) are one of the most important technologies to provide various ITS services. While VANET requires rapid and reliable transmission, packet transmission in VANET is unstable because of high mobility. Many routing protocols have been proposed and assessed to improve the efficiency of VANET. However, topology-based routing protocols generate heavy overhead and long delay, and position-based routing protocols have frequent packet loss due to inaccurate node position. In this paper, we propose a position-based routing repair algorithm to improve the efficiency of VANET. This algorithm is proposed based on the premise that AODV (-PGB) can be used effectively in VANET, if the discovery, maintenance and repair mechanism of AODV is optimized for the features of VANET. The main focus of this algorithm is that the relay node can determine whether its alternative node exits and judge whether the routing path is disconnected. If the relay node is about to swerve from the routing path in a multi-hop network, the node recognizes the possibility of path loss based on a defined critical domain. The node then transmits a handover packet to the next hop node, alternative nodes and previous node. The next node repairs the alternative path before path loss occurs to maintain connectivity and provide seamless service. We simulated protocols using both the ideal traffic model and the realistic traffic model to assess the proposed algorithm. The result shows that the protocols that include the proposed algorithm have fewer path losses, lower overhead, shorter delay and higher data throughput compared with other protocols in VANET.

• 산업경영시스템학회지
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• 제42권3호
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• pp.89-94
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• 2019

K1A1 tank commander's primary thermal sight is a device that enables tank commanders to detect, identify, aim and track the target by observing targets in all directions during day, night and in situations of smokescreen and fog through $360^{\circ}$ rotation independent from the gunner's primary thermal sight and stabilizing the line of sight even under the vibrations occurring when the tank is standstill and moving. The main function of this device is to detect and process visible and thermal images and deliver the final images to the tank commander. One of the core parts to that end is the observation window (daytime/thermal image window). This core part is mounted at the entrance of the optical path for observing the target and plays the role of making visible light during the daytime and infrared light during the night pass through the target and transmitting the resultant images to the internal optical system of the tank commander's primary thermal sight. Such core parts have been selected as depot maintenance items so that they are replaced by new parts instead of being recycled when they are subjected to maintenance in most cases. That is, the military budget is wasted because such parts are replaced by new parts despite that they can be recycled for maintenance. Therefore, this study proposed a mounting tool for polishing and coating observation windows (daytime and thermal image window) using planar polishing equipment and DLC (Diamond-Like Carbon) coating equipment. In addition, this study presented an amendment (proposal) of the Depot Maintenance Work Request (DMWR) already published to verify the performance of recycled products including the establishment of inspection standards for recycling processes.

• 한국해안·해양공학회논문집
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• 제28권2호
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• pp.63-72
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• 2016

경사제 피복재와 같은 항만 구조물의 유지관리 계획에서 중요한 최적 정밀점검시기를 쉽게 결정할 수 있는 RRP(Renewal Reward Process)기반 기대할인비용모형인 추계학적 결정모형을 개발하였다. PIM(Periodic Inspection and Maintenance)과 CBIM(Condition-Based Inspection and Maintenance) 정책을 동시에 적용하여 이전 모형들의 한계성을 극복할 수 있는 수학적 모형을 수립하였다. 또한 모형에 연속복리계수를 도입하여 점검 및 보수보강과 관련된 비용들의 시간에 따른 가치변화를 고려하였다. 먼저 파괴율 함수가 일정한 조건에서 해석해를 유도하고, 분포함수에 따른 영향 등 다각적 민감도 분석을 수행하여 본 연구에서 유도된 해석해가 기존에 제시된 해석해를 포함하며 적용성이 더 우수함을 확인 할 수 있었다. 추계학적 확률과정을 이용하는 경우에도 본 연구에서 수립된 모형은 경사제 피복재와 같은 구조물의 추계학적 누적피해도의 비선형성을 올바로 해석할 수 있다. 특히 MCS(Monte-Carlo Simulation) 기반 표본경로기법을 사용하여 모형의 피해강도함수의 계수들을 비교적 쉽게 산정할 수 있었다. 마지막으로 본 연구에서 개발된 추계학적 결정 모형을 경사제 피복재에 만족스럽게 적용하였다. 누적피해의 거동 특성, 사용한계의 수준 그리고 구조물의 중요도에 따라 단위시간당 기대 총 비용이 최소가 되는 경사제의 피복재의 최적 정밀점검 시점을 비교적 쉽게 결정할 수 있었다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권12호
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• pp.602-607
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• 2003

We show three-dimensional distribution of voltages resulted from the leakage current originated from outdoor electrical facilities in a submerged area. In case these facilities are grounded by the neutral line multiple grounding method, the existence of ungrounded electrical facilities can cause a disastrous effect on near-by passengers. In order to investigate this situation, we installed a real-scale test field for the experiment type I (for the leakage current path between a enclosure grounded electrical facility and another enclosure grounded one), and that for the experiment type II (for the leakage current path between a enclosure grounded electrical facility and another ungrounded one). For both cases, we carried out three-dimensional monitoring of the voltage distribution while varying additional conditions such as the exposure of the underground cables and the finishing of cable connection part. The result shows that a disastrous effect on human safety can arise from the leakage current without a pertinent measure for the construction and maintenance of outdoor electrical facilities.

• Journal of Construction Engineering and Project Management
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• 제3권2호
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• pp.21-34
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• 2013

Various risk factors affect construction projects. Due to the uncertainties created by risk factors, actual activity durations frequently deviate from the estimated durations in either favorable or adverse direction. For this reason, evaluation of schedule uncertainty is required to make decisions accurately when managing construction projects. In this regard, this paper presents a new computer simulation model - the Repetitive Schedule Risk Analysis Model (RSRAM) - to evaluate unit-based repetitive building project schedules under uncertainty when activity durations and risk factors are correlated. The proposed model utilizes Monte Carlo Simulation and a Critical Path Method based repetitive scheduling procedure. This new procedure concurrently provides the utilization of resources without interruption and the maintenance of network logic through successive units. Furthermore, it enables assigning variable production rates to the activities from one unit to another and any kind of relationship type with or without lag time. Details of the model are described and an example application is presented. The findings show that the model produces realistic results regarding the extent of uncertainty inherent in the schedule.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제5권3호
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• pp.222-229
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• 2005

This paper presents a self-organizing scheme for multi-agent swarm systems based on coupled nonlinear oscillators (CNOs). In this scheme, unicycle robots self-organize to flock and arrange group formation through attractive and repulsive forces among themselves. The main result is the maintenance of flexible and scalable formation. It is also shown how localized distributed controls are utilized throughout group behaviors such as formation and migration. In the paper, the proposed formation ensures safe separation and good cohesion performance among the robots. Several examples show that the proposed method for group formation performs the group behaviors such as reference path following, obstacle avoidance and flocking, and the formation characteristics such as flexibility and scalability, effectively.

• 건축역사연구
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• 제31권4호
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• pp.29-44
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• 2022

This thesis is a study to Haengnang(行廊, a series of buildings) of Sijeon(市廛, licensed markets), which was built along with palaces, Jongmyo(宗廟) and roads in order to establish Hanyang(漢陽) as the capital of Joseon (朝鮮). Sijeon, built on Jongno and Namdaemun-ro, the main roads in Hanyang, created two-row lands on both sides of the road, and formed Pimat-gil as an inner road between the Jeonbang and Doga. The formation of the city proceeded along with the maintenance of the water path, and the situation of the water path parallel to the flow of Sijeon was achieved. The Sijeon building was a spatial structure managed by independent rooms as a result of reflecting the unique operation method of Sijeon. The Sijeon of Hanyang had an impact on the formation of land, architecture, roads, and waterways, and acted as a major factor in determining the urban spatial structure of Hanyang City.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권3호
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• pp.1022-1034
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• 2023

Various aspects of artificial intelligence (AI) have become of significant interest to academia and industry in recent times. To satisfy these academic and industrial interests, it is necessary to comprehensively investigate trends in AI-related changes of diverse areas. In this study, we identified and predicted emerging convergences with the help of AI-associated research abstracts collected from the SCOPUS database. The bidirectional encoder representations obtained via the transformers-based topic discovery technique were subsequently deployed to identify emerging topics related to AI. The topics discovered concern edge computing, biomedical algorithms, predictive defect maintenance, medical applications, fake news detection with block chain, explainable AI and COVID-19 applications. Their convergences were further analyzed based on the shortest path between topics to predict emerging convergences. Our findings indicated emerging AI convergences towards healthcare, manufacturing, legal applications, and marketing. These findings are expected to have policy implications for facilitating the convergences in diverse industries. Potentially, this study could contribute to the exploitation and adoption of AI-enabled convergences from a practical perspective.

• 한국조경학회지
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• 제37권5호
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• pp.78-89
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• 2009

지난 10년간 한국골프산업은 매년 20~30개의 골프장을 새롭게 개장하였다. 한국골프장경영협회의 자료에 따르면 2009년 현재 한국에는 18홀을 하나의 골프장으로 계산했을 경우 약 320여 개의 골프장이 있다고 한다. 전 세계 골프장 약 34,000여 개 중 절반 이상인 18,000개가 미국에 있고, 영국, 일본, 호주, 남아프리카공화국 등 골프가 대중화 되어 있는 나라에 나머지 대부분이 있어 한국도 어느새 골프 선진국 반열에 올라 있다고 할 수 있다. 하지만 이에 반해 한국의 골프장공사는 골프선진국과 비교하여 많이 뒤쳐져 있다. 양적인 급성장에 질적인 성장이 따라 가지 못한 이유라고 할 수 있다. 골프장 공사 중, 서구 골프 선진국에는 일반화 되어 있으나 한국에는 알려지지 않은 공법을 많이 찾을 수 있는데, 그 중 하나가 콘크리트 카트도로이다. 골프 선진국의 대표인 국가인 미국에서는 약 80% 이상의 골프장의 카트도로가 콘크리트인 반면에 한국은 일반적으로 아스팔트를 사용하고 있다. 따라서 본 연구는 일반화 되어 있는 아스팔트 카트도로와 콘크리트 카트도로의 장단점, 특히 공사적인 측면, 운영적인 측면, 유지관리적인 측면 등으로 구분해 연구하여 콘크리트의 저렴한 유지관리비, 긴 상품의 수명, 조형의 아름다움과 같은 장점을 강조하였다. 이에 반해 콘크리트의 단점인 시공에 필요한 제한된 환경, 겨울철 시공의 문제점도 발견할 수 있었다. 카트도로 재료의 장단점에 대한 본 연구는 카트도로 재료 선택을 위한 올바른 가이드라인이 될 것을 기대해 본다.

• 대한기계학회논문집A
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• 제35권6호
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• pp.629-633
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• 2011

항공기, 철도, 선박과 같은 대형 시스템들은 전기, 기계적으로 매우 복잡한 구조를 가졌으며 부품의 수명만을 고려한 기존의 유지보수에서 탈피하여, 고장분석의 시스템화를 통해 장치의 고유수명과는 관계없이 발생 가능한 우발고장도 대처할 수 있는 신뢰성 기반의 유지보수체계를 연구하여야 한다. 본 연구에서는 선행연구로 필요한 복합 시스템의 신뢰도 계산방법에 관한 연구이다. 복합 시스템의 신뢰도를 효과적으로 계산하기 위해 시스템의 RBD(Reliability Block Diagram)를 구성하고 인접행렬을 사용하여 RBD(Reliability Block Diagram)를 행렬로 표현한다. 또한 RBD(Reliability Block Diagram)행렬을 통하여 신뢰도 경로행렬과 고장열거 행렬을 구성하여 시스템의 신뢰도를 계산한다. 본 연구에서 제안한 알고리즘은 자동화, 시스템화가 가능하며 현재 개발하고 있는 신뢰도 정보관리 시스템 및 신뢰성 기반 유지보수 시스템에서 활용될 것이다.