• Structural Engineering and Mechanics
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• 제32권6호
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• pp.787-809
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• 2009

Recent interest in the use of wireless sensor networks for structural health monitoring (SHM) is mainly due to their low implementation costs and potential to measure the responses of a structure at unprecedented spatial resolution. Approaches capable of detecting damage using distributed processing must be developed in parallel with this technology to significantly reduce the power consumption and communication bandwidth requirements of the sensor platforms. In this investigation, a damage detection system based on a distributed processing approach is proposed and experimentally validated using a wireless sensor network deployed on two laboratory structures. In this distributed approach, on-board processing capabilities of the wireless sensor are exploited to significantly reduce the communication load and power consumption. The Damage Location Assurance Criterion (DLAC) is used for localizing damage. Processing of the raw data is conducted at the sensor level, and a reduced data set is transmitted to the base station for decision-making. The results indicate that this distributed implementation can be used to successfully detect and localize regions of damage in a structure. To further support the experimental results obtained, the capabilities of the proposed system were tested through a series of numerical simulations with an expanded set of damage scenarios.

• 대한산업공학회지
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• 제37권3호
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• pp.180-190
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• 2011

Efficient energy consumption is a critical factor for deployment and operation of wireless sensor networks (WSNs). To achieve energy efficiency there have been several hierarchical routing protocols that organize sensors into clusters where one sensor is a cluster-head to forward messages received from its cluster-member sensors to the base station of the WSN. In this paper, we propose a self-organized clustering method for cluster-head selection and cluster based routing for a WSN. To select cluster-heads and organize clustermembers for each cluster, every sensor uses only local information and simple decision mechanisms which are aimed at configuring a self-organized system. By these self-organized interactions among sensors and selforganized selection of cluster-heads, the suggested method can form clusters for a WSN and decide routing paths energy efficiently. We compare our clustering method with a clustering method that is a well known routing protocol for the WSNs. In our computational experiments, we show that the energy consumptions and the lifetimes of our method are better than those of the compared method. The experiments also shows that the suggested method demonstrate properly some self-organized properties such as robustness and adaptability against uncertainty for WSN's.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권8호
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• pp.2805-2826
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• 2021

In most cases, the routing policy of networks shows a preference for a static one-to-one mapping of communication pairs to routing paths, which offers adversaries a great advantage to conduct thorough reconnaissance and organize an effective attack in a stress-free manner. With the evolution of network intelligence, some flexible and adaptive routing policies have already proposed to intensify the network defender to turn the situation. Routing mutation is an effective strategy that can invalidate the unvarying nature of routing information that attackers have collected from exploiting the static configuration of the network. However, three constraints execute press on routing mutation deployment in practical: insufficient route mutation space, expensive control costs, and incompatibility. To enhance the availability of route mutation, we propose an OpenFlow-based route mutation technique called Polymorphic Path Transferring (PPT), which adopts a physical and virtual path segment mixed construction technique to enlarge the routing path space for elevating the security of communication. Based on the Markov Decision Process, with considering flows distribution in the network, the PPT adopts an evolution routing path scheduling algorithm with a segment path update strategy, which relieves the press on the overhead of control and incompatibility. Our analysis demonstrates that PPT can secure data delivery in the worst network environment while countering sophisticated attacks in an evasion-free manner (e.g., advanced persistent threat). Case study and experiment results show its effectiveness in proactively defending against targeted attacks and its advantage compared with previous route mutation methods.

• 산업경영시스템학회지
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• 제43권4호
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• pp.59-66
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• 2020

In this study, we consider the problem of forecasting the number of inbound foreigners visiting Korea. Forecasting tourism demand is an essential decision to plan related facilities and staffs, thus many studies have been carried out, mainly focusing on the number of inbound or outbound tourists. In order to forecast tourism demand, we use a seasonal ARIMA (SARIMA) model, as well as a SARIMAX model which additionally comprises an exogenous variable affecting the dependent variable, i.e., tourism demand. For constructing the forecasting model, we use a search procedure that can be used to determine the values of the orders of the SARIMA and SARIMAX. For the exogenous variable, we introduce factors that could cause the tourism demand reduction, such as the 9/11 attack, the SARS and MERS epidemic, and the deployment of THAAD. In this study, we propose a procedure, called Measuring Impact on Demand (MID), where the impact of each factor on tourism demand is measured and the value of the exogenous variable corresponding to the factor is determined based on the measurement. To show the performance of the proposed forecasting method, an empirical analysis was conducted where the monthly number of foreign visitors in 2019 were forecasted. It was shown that the proposed method can find more accurate forecasts than other benchmarks in terms of the mean absolute percentage error (MAPE).

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.749-763
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• 2022

The fulcrum of economic development is a sustainable supply of electricity. Nigeria is plagued with blackouts, with one of the lowest per capita electricity consumption in the world (circa. 120 kWh per capita). Hence, policies have been instigated to integrate electricity generation from nuclear power plants (NPP) on or before 2027. However, a critical requirement for NPP generation is the implementation of robust human resource development (HRD) programs. This paper presents the perspective of Nigeria in assessing human resources needs over the entire NPP lifecycle following the milestone approach and employing the IAEA's Nuclear Power Human Resource (NPHR) modeling tool. Three workforce organizations are in focus including the owner/operator, regulators, and construction workers following three decades timeframe (2015-2045). The results indicate that for the study period, a maximum of approximately 9045 personnel (73% construction workers, 24% owner/operator, and 3% regulators) should be directly involved in the NPP program just before the commissioning of the third NPP in 2033. However, this number decreases by about 73% (2465 personnel including 94% operator and 6% regulator) at the end of the study timeframe. The results can potentially provide clarity and guidance in HRD decision-making programs.

• 대한조선학회논문집
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• 제60권4호
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• pp.288-295
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• 2023

This paper deals with the dynamic simulation method for analysis of driving characteristics of aircraft and towing vehicles (TUG) on carrier vessel in wave motions. For prompt deployment in a short period of time, optimization of the movement of carrier aircraft becomes a major issue. In this regards, strategy studies using real-time simulation technology and optimal decision-making technologies are being conducted. In the present work, the dynamic characteristics of carrier aircraft and TUG connected by towbar or towbarless mechanism were investigated by means of multi-body dynamics model. Meanwhile, for real-time simulation, Dugoff's model of tire loads calculation was adopted. Through comparative analysis it was confirmed that the similarity of results between the multi-body contact model and the tire load calculation model can be achieved by coefficients tuning.

• 한국건설관리학회논문집
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• 제25권3호
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• pp.68-82
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• 2024

The planning stage of laser scanning is crucial for acquiring high-quality 3D source data. It involves assessing the target space's environment and formulating an effective measurement strategy. However, existing practices often overlook on-site conditions, with decisions on scanner deployment and scanning locations relying heavily on the operators' experience. This approach has resulted in frequent modifications to scanning locations and diminished 3D data quality. Previous research has explored the selection of optimal scanner locations and conducted preliminary reviews through simulation, but these methods have significant drawbacks. They fail to consider scanner inaccuracies, do not support the use of multiple scanners, rely on less accurate 2D drawings, and require specialized knowledge in 3D modeling and programming. This study introduces an optimization technique for laser scanning planning using 3D simulation to address these issues. By evaluating the accuracy of scan data from various laser scanners and their positioning for scanning a retaining wall structure in a small-scale building, this method aids in refining the laser scanning plan. It enhances the decision-making process for end-users by ensuring data quality and reducing the need for plan adjustments during the planning phase.

• 해양환경안전학회지
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• 제26권5호
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• pp.466-473
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• 2020

해양항공드론은 해양사고의 예방과 대응에 이용할 수 있는 새로운 장비이다. 이러한 해양항공드론을 배치하기 위한 관할구역을 결정하는 것은 정부 의사결정자가 효과적인 정책을 마련하도록 도움을 줄 수 있다. 이 연구의 목적은 F-AHP법과 ARAS법을 이용하여 해양항공드론을 배치하기 위한 적절한 구역을 평가하는 모델을 개발하기 위한 것이다. 그리고 이 제안된 모델의 적용가능성을 확인하기 위해 우리나라 해양경찰청의 관할구역에 적용하였다. 해양항공드론의 배치는 평가요소 사이에 중복이 높은 특징이 있기 때문에 식별된 평가항목의 중요도를 결정하기 위해서 F-AHP법을 이용하였다. 그 결과 해양드론의 배치에 있어서 연안에서의 실종자 항목이 가장 중요한 평가항목으로 나타났다. 또한 이 연구에서 지역 해양경찰서의 우선순위는 하나의 목표(해양사고 50 % 저감)를 고려할 수 있는 ARAS법을 이용하였다. 그 결과로서 목포 해양경찰서 관할구역의 우선순위가 가장 높게 나타났고, 인천, 서귀포, 태안, 완도, 여수, 포항, 통영, 군산, 보령, 제주, 부안, 동해, 속초, 울산, 울진, 부산, 창원, 평택 해양경찰서 관할구역 순으로 나타났다.

• 벤처창업연구
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• 제13권4호
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• pp.35-48
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• 2018

본 연구는 대기업, 중견기업에서 주로 사용되어온 QFD (Quality Function Deployment)를 창업기업에 접목하여 초기성장기의 창업 기업들의 성장 도태, 매출 정체에 대한 해결 방안으로 QFD 교육 훈련 프로그램에 참여하였던 창업 벤처기업들을 그 연구 대상으로 하였다. QFD 교육 훈련과정에서 임직원들이 배웠던 내용을 현업에 실제로 접목하고자 하였는지 즉 교육 훈련 성과가 있는지에 관하여 연구하는 과정에서 학습전이 의도 영향 요인과 그 경로 구조에 학습자의 개인적 특성이 조절 기능을 하는 지에 대해 실증적으로 규명하고자 하였다. 실증분석의 결과는 학습자준비상태와 훈련내용의 타당성인지가 자기 효능감을 통해 학습전이의도에 영향을 미치는 관계에서 학습자의 인구통계학적 특성의 조절효과는 성별이 부분 조절효과, 직급이 조절효과가 있는 것으로 나타났고, 연령과 학력수준, 창업경력은 통계적으로 유의한 결과가 나타나지 않았다. 본 연구의 시사점은 현실에 접목하기 쉽게 실천중심으로 설계된 훈련 프로그램을 진행할 때 프로그램 결과가 그 기업에 직접적으로 성과를 달성하도록 하기 위해서는 창업기업의 의사결정에 큰 영향력을 미치는 대표이사가 참석하도록 의무화하는 것이 훈련 프로그램의 성과를 높이는데 큰 효과가 있다는 것을 실증적으로 규명한 것이다. 이를 통해 창업기업대상 교육 훈련 프로그램을 진행하는 집행 기관의 교육 기획 단계에서 정책적 시사점을 제공하는 것을 목적으로 하였다.

• 자원ㆍ환경경제연구
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• 제31권4호
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• pp.645-668
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• 2022

발전, 수송, 저장, 산업공정 등 에너지 사용 전반에서 탄소중립의 중요한 수단으로 수소에너지가 부각되고 있다. 연료전지 발전소는 수소 생태계에서 가장 빠르게 보급되고 있으며 2050 탄소중립 구현을 위한 핵심적인 발전원 중 하나이다. 하지만 연료전지 발전소의 수익에 영향을 미치는 전력도매가격(SMP)과 신재생에너지 공급인증서(REC) 가격의 높은 변동성은 잠재적 사업자들의 투자시기를 지연시켜 보급에 걸림돌로 작동하고 있다. 본 연구는 실물옵션 방법론을 적용하여 비가역적인 연료전지 발전소의 투자결정에 있어서 SMP와 REC 가격 이중 불확실성이 투자임계가격 수준에 어떠한 영향을 미치는지 분석하였다. 분석 내용은 다음의 3가지로 요약된다. 첫째, 현행 신재생에너지 공급의무화제도(RPS)하에서 사업자에게 전가되는 이중가격 불확실성은 결정론적 가격 대비 투자임계가격을 상당히 증가시켜 현재 가격 수준에서 경제성이 없는 것으로 나타났다. 둘째, REC 가격 변동성을 현재의 절반으로 경감하는 것은 REC 가중치를 한 단위 추가로 부여하는 것 만큼의 투자임계가격 하락 효과를 유발하였다. 셋째, 기존 부생수소 기반 연료전지와 함께 그레이 수소, 그린 수소 기반 투자임계가격을 분석하였으며, 그레이 수소의 경우 탄소배출권 비용이 적용될 경우 그린 수소와 경제성이 상당 부분 좁혀지는 것을 확인할 수 있었다. 본 연구 결과는 현행 RPS 제도가 연료전지 발전소 보급에 저해요소로 작동하며, 보다 비용 효율적이고 안정적인 수소 생태계 구축을 위해서는 정책보완이 필요함을 시사한다.