• 한국안전학회지
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• 제38권1호
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• pp.87-92
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• 2023

The number of unmanned light rail train operators is continuously increasing in Korea. In a failure event during an operation due to the nature of the unmanned operation, recovery is performed based on the remote control. However, if remote recovery is not feasible, safety personnel arrive at the train to resume the train operation. There are regulations on safety personnel and the suspension time of the train operation. However, there is currently no rule for safety personnel deployment. Currently, railway operating organizations operate in three scenarios: safety personnel on board trains, stationed at stations, and deployed at major stations. Four major factors influence the downtime for each emergency response scenario. However, these four influencing factors vary too much to predict results with simple calculations. In this study, four influencing factors were considered as random variables with high uncertainty. In addition, the Monte Carlo method was applied to each scenario for the safety personnel deployment to predict train service downtime. This study found a 17% difference in train service suspension by safety personnel deployment scenario. The results of this study can be used in setting service goals, such as standards for future safety personnel placement and frequency of service interruptions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권11호
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• pp.3030-3049
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• 2023

With the development and wide application of hybrid network computing modes like cloud computing, edge computing and fog computing, the customer service requests and the collaborative optimization of various computing resources face huge challenges. Considering the characteristics of network environment resources, the optimized deployment of service resources is a feasible solution. So, in this paper, the optimal goals for deploying service resources are customer experience and service cost. The focus is on the system impact of deploying services on load, fault tolerance, service cost, and quality of service (QoS). Therefore, the alternate node filtering algorithm (ANF) and the adjustment factor of cost matrix are proposed in this paper to enhance the system service performance without changing the minimum total service cost, and corresponding theoretical proof has been provided. In addition, for improving the fault tolerance of system, the alternate node preference factor and algorithm (ANP) are presented, which can effectively reduce the probability of data copy loss, based on which an improved cost-efficient replica deployment strategy named ICERD is given. Finally, by simulating the random occurrence of cloud node failures in the experiments and comparing the ICERD strategy with representative strategies, it has been validated that the ICERD strategy proposed in this paper not only effectively reduces customer access latency, meets customers' QoS requests, and improves system service quality, but also maintains the load balancing of the entire system, reduces service cost, enhances system fault tolerance, which further confirm the effectiveness and reliability of the ICERD strategy.

• 신재생에너지
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• 제20권1호
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• pp.61-69
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• 2024

This study investigates the barriers to the deployment of solar thermal and ground source heat pump (GSHP) from the perspective of consumers and businesses, as well as evaluates priorities for improving the barriers via expert AHP evaluation. From a consumer's perspective, the overall satisfaction with solar thermal is significantly lower than that with PV and needs to be improved at the installation and use stages. GSHP needs to be improved at the prior-information search stage. From a business perspective, the non-distinction between heat and electricity in mandatory installations in public buildings, the difficulty in assessing the value of heat, and high initial costs impede the deployment. Based on the result of AHP analysis, the priorities for improving the barriers to the wide utilization of solar thermal are evaluated in the order of economic feasibility, policy, acceptability, and technology, where high installation cost is shown to be the greatest barrier. Barriers for GSHP are evaluated in the order of policy, acceptability, economic feasibility, and technology, where policy means improvement is evaluated as the most important factor in promoting the deployment of GSHP.

• Journal of Chest Surgery
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• 제43권6호
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• pp.769-773
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• 2010

전신저혈압은 흉부대동맥질환의 스텐트 그라프트 치료에 전통적으로 많이 이용되어 왔으나, 혈관확장제를 이용한 혈압강하는 심박출량을 증가시킬 수 있으며 이로 인해 스텐트 그라프트의 전개 시 바람자루효과가 발생할 수 있다. 빠른 심실유도는 자동제어방식으로 일시적인 심박출량의 정지를 유도하여 심정지 지속시간이 제어 가능하고, 스텐트 그라프트 전개 시 대동맥 손상을 최소한으로 줄일 수 있다는 장점이 있다. 본원에서는 흉부대동맥궁 하방에 발생한 주머니동백자루 환자에게 빠른 심실유도하에 Valiant Captivia 스텐트 그라프트를 이용하여 효과적으로 혈관내 스텐트 그라프트 시술을 하였기에 문헌 고찰과 함께 보고하는 바이다.

• 대한산업공학회지
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• 제34권2호
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• pp.223-234
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• 2008

Mobile multi-hop relaying (MMR) technology is being considered as a promising solution capable to enhance coverage, user throughput, and system capacity of the current wired backbone dependent wireless access networks. Since the relaying nodes do not need a wired backbone access, MMR technology offers easy and low-cost deployment, flexible cell planning, and adaptive traffic handling performance. In this paper, we investigate performance and cost effectiveness of the MMR technology deployment in the IEEE802.16j based WiBro/WiMAX systems. We first introduce standardization activities and research issues of MMR WiBro/ WiMAX systems. Since the coverage extension problem may occur in metropolitan areas as well as suburban or rural areas where user density is relatively low or moderate, we introduce several MMR topologies and analyze cost-effectiveness of MMR based coverage extension with respect to the user traffic density. Then, we argue cost effect on MMR technology deployment and throughput performance, Finally, we introduce further study issues including sectorized base station based MMR deployment approaches and the single and multi-frame structure MMR approaches.

• 한국통신학회논문지
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• 제33권10B호
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• pp.894-903
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• 2008

일반적으로 센서들의 위치는 감시 정찰 센서 네트워크의 적용 범위, 데이터 전송 비용, 그리고 자원 관리에 영향을 미치기 때문에, 최적의 위치에 센서를 배치해야 한다. 그러나 산악 지대나 도심 지역과 같은 실 환경에 센서 노드를 배치할 경우, 센서에 영향을 미치는 다양한 지형 및 기후 요소들을 고려하기 어렵다. 따라서 이러한 다양한 환경에 센서를 배치할 경우 감시 영역 측면에서 목표 대상을 효율적으로 탐지할 수 있는 센서 배치 방법이 필요하다. 이를 위해 본 논문에서는 센서 배치와 관련된 다양한 기후와 지형 등의 환경 요소들을 분석하고, 이들 영향 요소들이 센서 노드 배치 시 활용될 수 있도록 정량화한다. 이를 바탕으로 센서 탐지 영역 측면에서 정량화된 영향 요소들을 고려함으로써 보다 실효적인 센서 배치 방법론을 제안한다. 또한 본 논문에서 제안한 센서 배치 방법론을 따르는 센서 배치 관리 시스템을 구현함으로써 제안된 방법론의 타당성을 입증한다.

• Journal of Preventive Medicine and Public Health
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• 제46권5호
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• pp.226-236
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• 2013

Objectives: The aim of this study was to examine the levels of serum 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and evaluate their association with age, body mass index, smoking, military record-based variables, and estimated exposure to Agent Orange in Korean Vietnam veterans. Methods: Serum levels of TCDD were analyzed in 102 Vietnam veterans. Information on age, body mass index, and smoking status were obtained from a self-reported questionnaire. The perceived exposure was assessed by a 6-item questionnaire. Two proximitybased exposures were constructed by division/brigade level and battalion/company level unit information using the Stellman exposure opportunity index model. Results: The mean and median of serum TCDD levels was 1.2 parts per trillion (ppt) and 0.9 ppt, respectively. Only 2 Vietnam veterans had elevated levels of TCDD (>10 ppt). The levels of TCDD did not tend to increase with the likelihood of exposure to Agent Orange, as estimated from either proximity-based exposure or perceived self-reported exposure. The serum TCDD levels were not significantly different according to military unit, year of first deployment, duration of deployment, military rank, age, body mass index, and smoking status. Conclusions: The average serum TCDD levels in the Korean Vietnam veterans were lower than those reported for other occupationally or environmentally exposed groups and US Vietnam veterans, and their use as an objective marker of Agent Orange exposure may have some limitations. The unit of deployment, duration of deployment, year of first deployment, military rank, perceived self-reported exposure, and proximity-based exposure to Agent Orange were not associated with TCDD levels in Korean Vietnam veterans. Age, body mass index and smoking also were not associated with TCDD levels.

• 한국항공우주학회지
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• 제45권12호
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• pp.1007-1012
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• 2017

본 연구에서는 우주 안테나 설계용 형상기억 폴리머 시편의 전개 시험을 수행하였다. Poly(cyclooctene)을 dicumyl peroxide를 이용하여 가교시켜 PCO 형상기억 폴리머를 제조하고, 이를 이용하여 지름이 120 mm인 전개형 안테나의 축소 모델을 제작하였다. 전개 성능 시험을 위하여 원형 형태의 형상기억 폴리머 시편을 반으로 접어 임시 형상을 만든 후 두 개의 히터로 형상기억 폴리머의 유리 전이 온도보다 $15^{\circ}C$ 높은 온도로 시편을 가열하였다. 먼저 시편을 수평 설치하여 전개 실험을 수행하였다. 시편의 전개 영상을 디지털 카메라를 사용하여 촬영한 후 트래커 프로그램을 이용하여 분석하였다. 중력의 효과를 최소화하기 위하여 수직 설치하여 다시 실험을 수행하였다. 두 실험의 결과를 비교하여 형상기억 폴리머 시편의 전개 성능을 고찰하였다.

• 인터넷정보학회논문지
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• 제21권1호
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• pp.211-219
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• 2020

본 논문에서는 4차산업의 혁명의 핵심 기술 중 사물 인터넷 (Internet of Things)과 드론(Drone)을 접목시킨 드론 인터넷(Internet of Drones)에 대해서 연구하였다. IoD 기술은 실제 전장에서 실제 전장과 C4ISR 작전을 효율적이고 경제적으로 운영하는데 특히 중요하다. 본 연구는 드론의 제한된 배터리 용량과 군의 드론 전사 육성 및 도입, 운용에 따른 예산 책정 기준 부재에 따른 문제점을 해결하는데 목표가 있다. 이에 따라 드론 투입 작전 상황 발생 시 임무 지역 (Mission area)이 정해지고 그에 따른 임무 지점 (Hovering point)과 임무 완료 제한시간이 정해질 경우, 최소한 몇 대의 작전 드론을 투입하여야 가장 경제적이고 효율적인 작전 운용이 가능한지 작전 투입 드론의 대수를 최적화해주는 DFDO(Drone Force Deployment Optimization) 알고리즘을 제안한다.

• Smart Structures and Systems
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• 제20권2호
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• pp.163-173
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• 2017

Structural health monitoring (SHM) of civil infrastructure using fiber Bragg grating sensor networks (FBGSNs) has received significant public attention in recent years. However, there is currently little research on the health-monitoring technology of high-piled wharfs in coastal ports using the fiber Bragg grating (FBG) sensor technique. The benefits of FBG sensors are their small size, light weight, lack of conductivity, resistance corrosion, multiplexing ability and immunity to electromagnetic interference. Based on the properties of high-piled wharfs in coastal ports and servicing seawater environment and the benefits of FBG sensors, the SHM system for a high-piled wharf in the Tianjin Port of China is devised and deployed partly using the FBG sensor technique. In addition, the health-monitoring parameters are proposed. The system can monitor the structural mechanical properties and durability, which provides a state-of-the-art mean to monitor the health conditions of the wharf and display the monitored data with the BIM technique. In total, 289 FBG stain sensors, 87 FBG temperature sensors, 20 FBG obliquity sensors, 16 FBG pressure sensors, 8 FBG acceleration sensors and 4 anode ladders are installed in the components of the back platform and front platform. After the installation of some components in the wharf construction site, the good signal that each sensor measures demonstrates the suitability of the sensor setup methods, and it is proper for the full-scale, continuous, autonomous SHM deployment for the high-piled wharf in the costal port. The South 27# Wharf SHM system constitutes the largest deployment of FBG sensors for wharf structures in costal ports to date. This deployment demonstrates the strong potential of FBGSNs to monitor the health of large-scale coastal wharf structures. This study can provide a reference to the long-term health-monitoring system deployment for high-piled wharf structures in coastal ports.