• 대한산업공학회지
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• 제40권4호
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• pp.388-395
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• 2014

Nowadays unmanned ground systems are used in supporting of surveillance and explosive ordnance disposal. Also, we expect that will be used to remarkably enhance combat capability through network-based cooperative operations with other combat systems. In order to effectively develop those unmanned systems, we needs a systematic method to analyze combat effectiveness and validate required operation capabilities. In this paper, we propose a practical approach to simulate remote-operated unmanned ground systems by using OneSAF, an US-Army simulation framework. First of all, we design a simulation model of unmanned system by integrating with core components for wireless communications and remote control of mobility and fire. Next, we extend OneSAF functionality to create communication links that connects a remote controller with an unmanned vehicle and define a simulated behavior to operate unmanned vehicles via the communication links. Finally, we demonstrate the feasibility of the proposed model within OneSAF and summarize system effectiveness analysis results.

• 한국포장학회지
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• 제11권1호
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• pp.11-16
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• 2005

Fruits are subjected to complex dynamic stresses in the transportation environment. During a long journey form the production area to markets, there is always some degree of vibration present. Vibration inputs are transmitted from the vehicle through the packaging to the fruit. Inside, these cause sustained bouncing of fruits against each other and container wall. These steady state vibration input may cause serious fruit injury, and this damage is particularly severe whenever the fruit inside the package is free to bounce, and is vibrated at its resonance frequency. The determination of the resonant frequencies of the fruit may help the packaging designer to determine the proper packaging system providing adequate protection for the fruit, and to understand the complex interaction between the components of fruit when they relate to expected transportation vibration inputs. The first frequency of the pear in packaged freight be stacked in resonance frequency band of the pear packaged freight was increased from the bottom to the top of the stack but the second frequency of that in resonance frequency band of the pear was decreased. This indicated that the high damage score of the pear in bottom tier in vibration test was due to higher acceleration level in resonance frequency band of the pear.

• 비파괴검사학회지
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• 제27권6호
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• pp.556-562
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• 2007

This paper presents the use of a novel fiber optic accelerometer system to monitor ambient vibration (both wind-induced one and vehicle-induced) of a real bridge structure. This sensor system integrates the $Moir\'{e}$ fringe phenomenon with fiber optics to achieve accurate and reliable measurements. A low-cost signal processing unit implements unique algorithms to further enhance the resolution and increase the dynamic bandwidth of the sensors. The fiber optic accelerometer has two major benefits in using this fiber optic accelerometer system for monitoring civil engineering structures. One is its immunity to electromagnetic (EM) interference making it suitable for difficult applications in such environments involving strong EM fields, electrical spark-induced explosion risks, and cabling problems, prohibiting the use of conventional electromagnetic accelerometers. The other is its ability to measure both low- and high-amplitude vibrations with a constantly high resolution without pre-setting a gain level, as usually required in a conventional accelerometer. The second benefit makes the sensor system particularly useful for real-time measurement of both ambient vibration (that is often used for structural health monitoring) and strong motion such as earthquake. Especially, the semi-strong motion and the small ambient one are successfully simulated and measured by using the new fiber optic accelerometer in the experiment of the structural health monitoring of a real bridge.

• Earthquakes and Structures
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• 제12권4호
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• pp.457-468
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• 2017

When studying the vibration of a suspension bridge based on the traffic-bridge coupled system, most researchers ignored the contribution of the pavement response. For example, the pavement was simplified as a rigid base and the deformation of pavement was ignored. However, the action of deck pavement on the vibration of vehicles or bridges should not be neglected. This study is mainly focused on establishing a new methodology fully considering the effects of bridge deck pavement, probabilistic traffic flows, and varied road roughness conditions. The bridge deck pavement was modeled as a boundless Euler-Bernoulli beam supported on the Kelvin model; the typical traffic flows were simulated by the improved Cellular Automaton (CA) traffic flow model; and the traffic-pavement-bridge coupled equations were established by combining the equations of motion of the vehicles, pavement, and bridge using the displacement and interaction force relationship at the contact locations. The numerical studies show that the proposed method can more rationally simulate the effect of the pavement on the vibrations of bridge and vehicles.

• International Journal of Railway
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• 제8권1호
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• pp.10-14
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• 2015

Due to the characteristics of the vehicle structure, the magnetic levitation train has a confined bottom space thus a study on miniaturization and weight reduction of auxiliary power unit is essential. This auxiliary power unit is an essential device used for illumination, air conditioning, heating and air brake equipment excluding the motor. The previous auxiliary power unit for magnetic levitation train has used the hard switching having a high switching frequency with heavy loss in order to reduce the size of filter reactor and transformer but the reduction in volume was not significant. In this paper, by reducing the loss, reducing the size of the cooling unit and by increasing the switching frequency using the soft switching of resonant converter, it has miniaturized and reduced the weight of filter reactor and transformer which occupy significant space in the auxiliary power unit. This study has verified the performance of 50KVA grade prototype through simulated interpretation and analysis, and compared the size and weight of auxiliary power unit of the previous magnetic levitation train.

• 한국멀티미디어학회논문지
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• 제24권10호
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• pp.1346-1357
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• 2021

The drone technology, which is receiving a lot of attention due to the 4th industrial revolution, requires an Unmanned Aerial Vehicles'(UAVs) flight path search algorithm for automatic operation and driver assistance. Various studies related to flight path prediction and recommendation algorithms are being actively conducted, and many studies using the A-Star algorithm are typically performed. In this paper, we propose an Optimal 3D Flight Path Recommendation System for unmanned aerial vehicles. The proposed system was implemented and simulated in Unity 3D, and by indicating the meaning of the route using three different colors, such as planned route, the recommended route, and the current route were compared each other. And obstacle response experiments were conducted to cope with bad weather. It is expected that the proposed system will provide an improved user experience compared to the existing system through accurate and real-time adaptive path prediction in a 3D mixed reality environment.

• 정보보호학회논문지
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• 제31권5호
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• pp.889-899
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• 2021

본 논문은 블록체인 기술에서 탈중앙화된 시스템 접근 방식을 활용하여 차량 인터넷(IoV)에서 신뢰할 수 있는 데이터 공유 체계를 제안한다. 스마트 계약에 기초한 인센티브 메커니즘을 채택하여, 차량은 올바른 교통 정보 메시지를 정직하게 공유함으로써 시스템으로부터 특정한 보상을 받게 된다. 이후 차량은 평판 등급을 생성하여 수신되는 모든 정보 메세지를 검증함으로서 메시지에 대한 신뢰성을 유지한다. 한편 네트워크 성능을 분석하기 위해 이산 이벤트 시뮬레이터를 사용하여 IoT 네트워크를 시뮬레이션하였고, 인센티브 모델은 분산형 접근 방식의 이더리움 스마트 계약을 활용하여 설계하였다.

• Steel and Composite Structures
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• 제43권4호
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• pp.501-509
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• 2022

Cracks are common defects in concrete structures. Thus far, crack inspection has been manually performed using the contact inspection method. This manpower-dependent method inevitably increases the cost and work hours. Various non-contact studies have been conducted to overcome such difficulties. However, previous studies have focused on developing a methodology for non-contact inspection or local quantitative detection of crack width or length on concrete surfaces. However, crack depth can affect the safety of concrete structures. In particular, although macrocrack depth is structurally fatal, it is difficult to find it with the existing method. Therefore, an experimental investigation based on non-contact infrared thermography and multivariate machine learning was performed in this study to estimate the hidden macrocrack depth. To consider practical applications for inspection, an experiment was conducted that considered the simulated piloting of an unmanned aerial vehicle equipped with infrared thermography equipment. The crack depths (10-60 mm) were comparatively evaluated using linear regression, gradient boosting, and random forest (AI regression methods).

• International Journal of Computer Science & Network Security
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• 제23권5호
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• pp.13-20
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• 2023

In connected vehicles, drivers are exposed to attacks when they communicate with unauthenticated peers. This occurs when a vehicle relies on outdated information resulting in interactions with vehicles that have expired or revoked certificates claiming to be legitimate nodes. Vehicles must frequently receive or query an updated revoked certificate list to avoid communicating with suspicious vehicles to protect themselves. In this paper, we propose a scheme that works on a highway divided into clusters and managed by roadside units (RSUs) to ensure authenticity and preserve hidden identities of vehicles. The proposed scheme includes four main components each of which plays a major role. In the top hierarchy, we have the authority that is responsible for issuing long-term certificates and managing and controlling all descending intermediate authorities, which cover specific regions (e.g., RSUs) and provide vehicles with short-term pseudonyms certificates to hide their identity and avoid traceability. Every certificate-related operation is recorded in a blockchain storage to ensure integrity and transparency. To regulate communication among nodes, security managers were introduced to enable authorization and access right during communications. Together, these components provide vehicles with an immediately revoked certificate list through RSUs, which are provided with publish/subscribe brokers that enable a controlled messaging infrastructure. We validate our work in a simulated smart highway environment comprising interconnected RSUs to demonstrate our technique's effectiveness.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.238-247
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• 2023

The present work represents a technical guideline for decommissioning a disused teletherapy machine model Theratron-780 and contains category one ⁶⁰Co radioactive source. The first section predicts the dose rate from the source in case of normal and radiological emergency situations via FLUKA-MC simulation code. Moreover, the dose assessment for the occupational during the whole process is calculated and compared to the measured values. A suggested cordoned area for safety and security in a radiological emergency is simulated. The second section lists the whole process's technical procedures, including (preview, dismantle, securing, transport and storage) of the disused teletherapy machine. Results show that the maximum obtained accumulated dose for occupational were found to be 24.5 ± 4.9 μSv in the dismantle and securing process in addition to 3.5 ± 1.8 μSv during loading on the transport vehicle and unloading at the storage facility. It was found that the measured accumulated dose for workers is in good agreement with the estimated one by uncertainty not exceeding 5% in normal operating conditions.