• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12B
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• pp.1075-1082
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• 2008

A greedy forwarding algorithm is one of the most suitable solutions for routing in vehicular ad-hoc networks. Compared to conventional routing protocols for mobile ad-hoc networks, greedy forwarding based routing protocols maintain only local information of neighbors instead of per-destination routing entries, and thus they show better performance in highly-mobile vehicular ad-hoc networks. With greedy forwarding, each node learns its geographical position and periodically broadcasts a beacon message including its position information. Based on the position information, each node selects a neighbor node located closest to the destination node as the next forwarder. One of the most serious problems in greedy forwarding is the lost link problem due to the mobility of nodes. In this paper, we propose a new algorithm to reduce the lost link problem. The proposed algorithm aims to find an efficient and stable routing path by taking account of the position of neighbors and the last beacon reception time. Our simulation results show that the proposed algorithm outperforms the legacy greedy algorithm and its variants.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6A
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• pp.600-610
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• 2010

In this paper, a multicast mechanism is proposed for intermittently disconnected networks where the nodes move forward in formation or within a limited area. The proposed scheme extends the well-known tree-based multicast routing mechanism called MAODV by modifying the tree construction and data delivery scheme. Especially, an algorithm is introduced which determines the flooding hop count k estimating the degree of the movement of children in the tree. The performance evaluation was done by the simulation and the proposed scheme was compared with MAODV and two multicast routing schemes for DTN (Disruption Tolerant Network) including the Epidemic routing and ST-multicast. The evaluation results show that our scheme improves the original MAODV from the aspect of tree reconstruction events and message delivery ratio. Compared with the Epidemic routing scheme, our scheme achieves 85% message delivery ratio with less than 50% message delivery overhead.

• Restorative Dentistry and Endodontics
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• v.36 no.2
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• pp.114-118
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• 2011

Objectives: This study was aimed to examine the patients' perception and satisfaction with the results of endodontic microsurgery which was apicoectomy with retrofilling. Materials and Methods: A questionnaire was given to 109 patients, who were recalled after a minimum of 3 months upon endodontic microsurgery in the Department of Conservative Dentistry, Yonsei University. A contingency table and correlation analysis were used to determine if there were any correlations between age/gender and the patients' responses (p = 0.05). Results: Approximately 60% of respondents answered they had never heard of surgical endodontic procedures. 63.3% of respondents chose the surgical option because they wanted to keep their natural teeth. If the patient required the same procedure on another tooth later, 100 out of 109 respondents answered they would choose microsurgery instead of extraction. Most patients (82.57%) appeared to be satisfied with the surgical procedure. Conclusions: Endodontic microsurgery consisting of apicoectomy and retrofilling seems to appeal to majority of patients as a satisfactory and valuable treatment choice.

• Journal of Environmental Impact Assessment
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• v.28 no.3
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• pp.287-298
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• 2019

This study found that wildlife crossing created through environmental impact assessments didn't reduce the number of wildlife accidents on the road by review of "A Study on the Legal and Institutional Review for Reproving Bio-Mobile in Environmental Impact Assessment(2018)". Specific considerations to be reviewed at each stage of the environmental impact assessment consultation were presented for practical site application. Therefore, in this study, the consultation steps for environmental impact assessment were presented in five stages, including planning, design, construction, monitoring, maintenance and management, and detail of the items to be reviewed by public officer. It will be able to prevent loss of habitats and improve biodiversity by improving the practice and institutional problems that were planned and designed at the time of construction.

• Journal of Digital Convergence
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• v.16 no.11
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• pp.471-476
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• 2018

The purpose of this article is to understand the causes and consequences of the formation and division process of the family relationship and the meaning of the restoration of the family relationship that appeared for the baby-boomer generation, the eco-boomer generation, and the subsequent generation which represent the reality of the time involved. The research method is based on a family that reflects the current age in the drama "My Golden Life" which showed the highest audience rating in the first half of 2018. As a result, the burdens, conflicts, and responsibility of the generations about family relations appeared as unilateral relations. It cut off the entangled relationship and dismantled it. However, the disconnection of the relationship played a role in recovering the subjectivity of the individual from the bridle of the family. As it turned out, the restoration of the family relationship was possible in the bi-directional relationship after the self-esteem and identity of the individual was established first.

• Journal of Advanced Navigation Technology
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• v.26 no.2
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• pp.119-124
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• 2022

The international gnss service (IGS) provides real-time service (RTS) orbit and clock correction applicable to the broadcast ephemeris of GNSS satellites. However, since the RTS correction cannot be received if the Internet connection is lost, the RTS correction should be predicted and used when a signal interruption occurs in order to perform stable precise point positioning (PPP). In this paper, PPP was performed by predicting orbit and clock correction using a long short-term memory (LSTM) algorithm in real-time during the signal loss. The prediction performance was analyzed by implementing the LSTM algorithm in RPI (raspberry pi), the processing speed of which is not high. Compared to the polynomial prediction model, LSTM showed excellent performance in long-term prediction.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.4
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• pp.525-533
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• 2023

Due to the topographical characteristics of Busan, which has many mountainous areas, there is a shortage of available land, and even the Gyeongbu Line railroad crosses the city center, hindering the disconnection of living areas and urban development. Accordingly, the need for multi-dimensional development has been raised to secure land, and recently, interest has been increasing in connecting cities divided by the undergroundization of the Gyeongbu Line railway and making efficient use of land. In this study, the development type was analyzed through the case of multi-dimensional development of land, and the development direction for each three-dimensional development type was set based on the results of the multi-dimensional development of four areas (Sasang Station, Gupo Station, Gaya Station, and Busanjin Station). In addition, reflecting the regional characteristics of the target area and the ongoing urban regeneration project, we will propose a design plan for horizontal and vertical space utilization of the railway site through multi-dimensional development through the efficient land use.

• Journal of KIISE:Information Networking
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• v.31 no.1
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• pp.81-90
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• 2004

A Mobile Ad Hoc Network (MANET) is a collection of wireless mobile nodes dynamically self-organizing in arbitrary and temporary network topologies without the use of any existing network infrastructure. The AODV (Ad Hoc On-Demand Distance Vector) Protocol is one of the typical reactive routing protocols, in that mobile nodes initiate routing activities only in the presence of data packets in need of a route. In this paper, we focus upon the local repair mechanism of AODV. When a link is broken, the upstream node of the broken link repairs the route to the destination by initiating a local route discovery process. The process involves the flooding of AODV control messages in every node within a radius of the length from the initiating node to the destination. In this paper, we propose an efficient local repair scheme for AODV called AFLRS (AODV-based Fast Local Repair Scheme). AFLRS utilizes the existing routing information in the intermediate nodes which have been on the active route to the destination before a link break occurs. AFLRS can reduce the flooding range of AODV control messages and the route recovery time because it can repair route through the intermediate nodes. For the performance evaluation of the proposed AFLRS, we have simulated the local repair mechanisms by using NS2 and AODV-UU. The performance results show that AFLRS can achieve faster route recovery than the local repair mechanism of AODV.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.268-275
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• 2018

The purpose of this study is to investigate what items are needed for reemployment according to the life cycle of women and to provide basic data to address the career discontinuity of women. The study selected five women currently unemployed living in Daejeon who were taking classes related to entrepreneurship at the Cultural Center and the Women Resource Development Center. The data collection period was from October to December, 2017, and collected from in depth interviews. An open-ended interview was used to explore the content of the interview process. The results of the study are as follows: Support policies for women with career disruptions should, above all, be given priority over career support to ensure that currently employed women do not quit their jobs due to marriage, childbirth or childcare. In addition, there is a need to improve the relevant systems and to implement vocational education and training programs so that women with career discontinuity can reenter the labor market. To do this, it is necessary to establish and support career planning in order to understand the effects of women's lifecycles and to support women's economic activity.

• Korean Journal of Childcare and Education
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• v.11 no.6
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• pp.37-58
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• 2015

The purpose of the study was to analyze the effects of both young children's gender and temperament and their teachers' teaching efficacy and teacher-child interactions on peer play interactions. For this purpose, the data from the 2012 Panel Study on Korean Children were analyzed using analyses of variances and correlation co-efficiencies. In addition, analyses of hierarchical regression, with young children's temperament and teacher-related factors (teaching efficacy and teacher-child interactions) as the independent variables and three sub-factors of peer play interactions (play interaction, play disruption, play disconnection) as the dependent variables, were conducted. The results showed that young children's temperament, teacher efficacy, teacher-child interactions, and peer play interactions differed by gender and significantly correlated. Young children's temperament and teacher-child interactions significantly affected young children's peer play interactions, and the effect of teacher-child interactions was larger than the effect of temperament by 2~2.5 times. The results proved the importance of early childhood teachers' roles in the development of young children's peer interactions with consideration of differences based on children's gender and temperament. With the results given, implications and suggestions for further research were discussed.