• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.4
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• pp.53-62
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• 2010

In VANETs (Vehicular Ad hoc NETwork), conditional anonymity must be provided to protect privacy of vehicles while enabling authorities to identify misbehaving vehicles. To this end, previous systems provide a mechanism to revoke the anonymity of individual messages. In VANET, if we can trace the movement path of vehicles, it can be useful in determining the liability of vehicles in car accidents and crime investigations. Although route tracing can be provided using previous message revocation techniques, they violate privacy of other vehicles. In this paper, we provide a route tracing technique that protects privacy of vehicles that are not targeted. The proposed method can be employed independently of the authentication mechanism used and includes a mechanism to prevent authorities from abusing this new function.

• Journal of Surface Science and Engineering
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• v.55 no.1
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• pp.1-8
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• 2022

Titanium dioxide (TiO₂) is one of the most intensively investigated materials in materials science. Mostly, TiO₂ has been used in the form of nanoparticles, but recently new highly ordered TiO₂ nanotubes (U-tube) has been introduced and applied to various applications due to their one-dimensional charge path way. In the present paper, we described the formation process and physical properties of U-tube then, gave examples of applications in sequence. Firstly, in photocatalysis, U-tube was used with Au/Pt co-catalysts and showed enhanced photogenerated H₂ efficiency compared to bare TiO₂. Secondly, photoelectrochemical performance of U-tube was evaluated with different heat-treatment temperatures. As a further application, two different types of electrical cell (Ti-TiO₂-Pt and Ti-TiO₂-Pt_NP) was configurated to observe memristive behavior of U-tube. Both cells behaved as switching electrodes and follow a memristive movement in the high and low resistance state extremely well with high reproducibility.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.6
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• pp.586-595
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• 2022

In this paper, we propose a formation control algorithm for multi-USVs according to COLREGs. First, we applied the Dynamic Window Approach algorithm that can reflect the kinematic characteristics for the path movement of USVs. Then, we propose a virtual structure-based virtual leader-follower method that applies the advantages of leader-follower and virtual structure methods among conventional formation control algorithms for stability. Next, we proposed a collision avoidance algorithm according to all COLREGs when encountering an opposing ship by adding COLREGs situational conditions to the virtual leader, and finally confirmed the feasibility of the proposed method through simulation.

• Ocean and Polar Research
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• v.44 no.2
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• pp.161-177
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• 2022

Microalgae can attach to the surface of ships and then spread to various areas by means of ship transport. The introduction of invasive species through ships is recognized as a marine problem worldwide. Identification of attached microalgae is necessary to investigate such movement between countries through ships. In the present study, through analytical methods we reviewed research data to identify the taxa of domestic attached microalgae and assess the ecological impacts of such microalgae. A total of 87 genera and 153 species (143 species of diatoms, 10 species of cyanobacteria, and 4 genera of dinoflagellates) were identified as native attached microalgae in Korea, and diatoms accounted for 93% of the total. Most of these attached microalgae were identified through research on natural substrates such as seaweeds and bedrock, and some were also identified through experiments using artificial adherent plates. To date, there is no information on microalgae attached to international ships and introduced into Korea. Molecular genetic analysis and systematic management through on-site sampling of international ships, microscopic analysis, and meta-barcoding are necessary to assess the inflow and spread path of hull-attached marine alien species and evaluate the risk they pose to the domestic ecosystem.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.547-548
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• 2009

The development of USN(Ubiquitous Sensor Network) technology is creating numerous application areas. Although a network configuration with fixed sensors was the norm in the past, the coexistence of mobile and fixed sensor nodes is a new trend. Fixed sensor networks focused on the energy efficiency of nodes, but the latest studies consider guaranteeing the mobility of nodes and maintaining their connectivity, while remaining energy efficient at the same time. This paper proposes a routing protocol for a mobile ad-hoc sensor network that improves the mobility, connectivity and energy efficiency of nodes while allowing for the management and maintenance of a large number of nodes even in a complex communication environment where mobile and fixed nodes coexist. An algorithm for multi-hop multi-paths, a technique for topology reconfiguration by node movement prediction and vibration sensors, path setting for a large number of nodes, and efficient data transfer technology have been introduced to implement the modified LEAHC-AOMDV protocol. Furthermore, the excellence of this protocol was verified through a comparative experiment with the conventional LEACH protocol.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.689-692
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• 2021

This paper is a prior study to improve the efficiency of offloading based on mobile agents to optimize allocation of computing resources and reduce latency that support user proximity of application services in a Fog/Edge Computing (FEC) environment. We propose an algorithm that effectively reduces the execution time and the amount of memory required when extracting optimal moving patterns from the vast set of spatio-temporal movement history data of moving objects. The proposed algorithm can be useful for the distribution and deployment of computing resources for computation offloading in future FEC environments through frequency-based optimal path extraction.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.05a
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• pp.40-41
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• 2023

This paper introduces the design of detection, recognition, and tracking algorithms for VTS radar image-based objects. The detection of objects in radar images utilizes artificial intelligence technology to determine the presence or absence of objects, and can classify the type of object using AI technology. Tracking involves the continuous tracking of detected objects over time, including technology to prevent confusion in the movement path. In particular, for land-based radar, there are unnecessary areas for detection depending on the terrain, so the function of detecting and recognizing vessels within the region of interest (ROI) set in the radar image is included. In addition, the extracted coordinate information is designed to enable various applications and interpretations by calculating speed, direction, etc.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.3
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• pp.239-249
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• 2001

The purpose of this study is to evaluate the relationship of the factors which could be influenced by orthognathic surgery especillay SSRO. We measured the amounts of the maximum opening, lateral movements, maximum velocity and pattern of mandibular path during the opening and closing of mandible at the following times ; preoperative, 1 month after operation, 6 months after operation respectively using MKG. And the results were compared according to the categorized subgroups. Following results were obtained : 1. The change of the amounts of mandibular lateral movement and maximum opening velocity were statistically different between male and female (p<0.05), but the others were not. 2. According to the method of operation, there was no difference in the change of the mandibular movements between the group of SSRO and SSRO plus LeFort I osteotomy (p>0.05). 3. According to the amounts of mandibular movement, the recovery of left lateral movement of the group of $6{\sim}10mm$ was better than the other groups (p<0.05). 4. In the frontal pattern of the opening and closing of the mandible, the complex deflected type (F5), simple deflected type (F4), complex deviated type (F3), simple deviated type (F2), straight type (F1) were obtained in order at the time of preoperative, simple deflected type, simple deviated type, complex deviated type, straight type, complex deflected type in order at the time of 1 month after surgery, and the result at the time of 6 months after surgery was the same with that of the time of preoperative. In the sagittal pattern, non-coincident type (S2) was predominant at the time of preoperative, and coincident type (S1) was predominant at the time of 1 month after surgery. After 6 months, the result was also the same with that of the preoperative in sagittal pattern. 5. There was not a statistical difference in the change of the mandibular movement between group of presence of the preoperative TMJ symptoms and non-presence group (p>0.05). 6. There was not a statistical difference in the change of the mandibular movement between repositioning device applied group and non-applied group (p>0.05). 7. Sixty three percents of the patients who had preoperative TMJ symptoms were improved after surgery and preoperative TMJ symptoms were more improved after operation in the repositioning device non-applied group statistically (p<0.05).

• The KIPS Transactions:PartC
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• v.14C no.2
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• pp.139-146
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• 2007

Mobile Sensor Network(MSN) is actively studied due to the advent of mobile sensors such as Robomote and Robotic Sensor Agents(RSAs), However, existing studies on MSN have mainly focused on coverage hole problem which occurs in Stationary Sensor Network(SSN). To address coverage hole problem, these studies make mobile sensors move temporarily so that they do not make the best use of the mobility of mobile sensors, Thus, a mechanism utilizing the continuous movement of mobile sensors is proposed to improve the network coverage performance. However, this mechanism is presently immature and does not explain how to make routing path and send data from mobile sensors to a sink node, Therefore, to efficiently make routing path and send data from mobile sensors to a sink node, we propose a communication protocol for mobile sensor network where mobile sensors continuously move. The proposed protocol deploys not only mobile sensors but also stationary sensors which send sensing data to a sink node instead of mobile sensors. Simulation results show that the proposed protocol improves the performance in terms of network coverage and traffic overhead, compared to conventional SSN protocols.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.6
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• pp.1083-1091
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• 2016

This research uses public transportation card data to analyze the inter-regional transfer times, transfer frequencies, and transfer resistance that passengers experience during transit amongst the metropolitan public transportation modes. Currently, mode transfers between bus and rail are recorded up to five times during one transit movement by Trip Chain, facilitating greater comprehension of intermodal movements. However, lack of information on what arises during these transfers poses a problem in that it leads to an underestimation of transfer resistances on the Trip Chain. As such, a path choice model that reflects passenger movements during transit activities is created, which attains explanatory power on transfer resistance through its inclusion of transfer times and frequencies. The methodology adopted in this research is to first conceptualize the idea of metropolitan public transportation transfer, and in the case that mode transfers include the city-rail, to newly conceptualize the idea of transfer resistance using transportation card data. Also, the city-rail path choice model within the Trip Chain is constructed, with transfer time and frequency used to reevaluate transfer resistance. Further, in order to align bus and city-rail station administrative level small-zone coordinates to state and regional level mid-zone coordinates, the big node methdod is utilized. Finally, case studies on trip chains using at least one transfer onto the city-rail is used to determine the validity of the results obtained.