• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.4
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• pp.101-118
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• 2023

During the COVID-19 pandemic, the utilization rate of neighborhood parks and green spaces increased significantly, and the outbreak served as an opportunity to highlight the values and functions of neighborhood parks and green spaces for urban residents. This study aims to empirically analyze how citizens' movement and the use of neighborhood parks and green spaces changed before and after COVID-19 and examine the social and spatial characteristics that affected these changes. As a research method, first, people's mobility around neighborhood parks and green spaces before and after the COVID-19 pandemic were compared using signal data from telecommunication carriers. Through the analysis of changes in residence time and movement volume, the movement characteristics of citizens after COVID-19 and changes in walking-based park visits were examined. Second, the factors affecting the mobility change in neighborhood parks and green spaces were analyzed. The social and spatial characteristics that affect citizens' visits to neighborhood parks and green spaces before and after COVID-19 were examined through correlation and multiple regression analysis. Subsequently, through cluster analysis, the types of living areas for the post-COVID era were classified from the perspective of the supply and management of neighborhood parks and green spaces services, and directions for improving neighborhood parks and green spaces by type were presented. Major research findings are as follows: First, since the outbreak of COVID-19, activities within 500m of the residence have increased. The amount of stay and walking movement increased in both 2020 and 2021, which means that the need to review the quantitative standards and attractions of neighborhood parks and green spaces has increased considering the changed scope of the walking and living area. Second, the overall number of visits to neighborhood parks and green spaces by walking has increased since the outbreak of COVID-19. The number of visits to neighborhood parks and green spaces centered on the house and the workplace increased significantly. The park green policy in the post-COVID era should be promoted by discovering underprivileged areas, focusing on areas where residential, commercial, and business facilities are concentrated, and improving neighborhood parks and green services in quantitative and qualitative terms. Third, it was found that the higher the level of park green service, the higher the amount of walking movement. It is necessary to use indicators that contribute to improving citizens' actual park green services, such as walking accessibility, rather than looking at the criteria for securing green areas. Fourth, as a result of cluster analysis, five types of neighborhood parks and green spaces were derived in response to the post-COVID era. This suggests that it is necessary to consider the socioeconomic status and characteristics of living areas and the level of park green services required in future park green policies. This study has academic and policy significance in that it has laid the basis for establishing neighborhood parks and green spaces policy in response to the post-COVID era by using various analysis methodologies such as carrier signal data analysis, GIS analysis, and statistical analysis.

• ETRI Journal
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• v.34 no.6
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• pp.847-857
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• 2012

Intrusion detection systems (IDSs) have an important effect on system defense and security. Recently, most IDS methods have used transformed features, selected features, or original features. Both feature transformation and feature selection have their advantages. Neighborhood component analysis feature transformation and genetic feature selection (NCAGAFS) is proposed in this research. NCAGAFS is based on soft computing and data mining and uses the advantages of both transformation and selection. This method transforms features via neighborhood component analysis and chooses the best features with a classifier based on a genetic feature selection method. This novel approach is verified using the KDD Cup99 dataset, demonstrating higher performances than other well-known methods under various classifiers have demonstrated.

• Journal of the Korea Computer Graphics Society
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• v.15 no.1
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• pp.17-23
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• 2009

We present a simple new idea to improve the quality of exemplar based texture synthesis using multiple rotated input exemplars. Our algorithm successfully obtain rotational synthesis feature variations and manages to reduce the artifacts in the results, especially patch seams due to the structure of the exemplars provided which have been inappropriate for previous neighborhood matching synthesis algorithms. Our algorithm is parallel in nature, thus it is possible to implement our algorithm using GPU or multi-core CPU to accelerate synthesis process.

• Journal of the Korean Operations Research and Management Science Society
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• v.41 no.1
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• pp.41-53
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• 2016

Static repositioning is a well-known and commonly used strategy to maximize customer satisfaction in public bike-sharing systems. Repositioning is performed by trucks at night when no customers are in the system. In models that represent the static repositioning problem, the decision variables are truck routes and the number of bikes to pick up and deliver at each rental station. To simplify the problem, the decision on the number of bikes to pick up and deliver is implicitly included in the truck routes. Two relocation-based local search algorithms (1-relocate and 2-relocate) with the best-accept strategy are incorporated into a variable neighborhood search (VNS) to obtain high-quality solutions for the problem. The performances of the VNS algorithm with the effect of local search algorithms and shaking strength are evaluated with data on Tashu public bike-sharing system operating in Daejeon, Korea. Experiments show that VNS based on the sequential execution of two local search algorithms generates good, reliable solutions.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.8 no.2
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• pp.132-139
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• 2008

This paper proposes a scatternet topology formation, self-healing, and self-routing path optimization algorithm based on Relative Neighborhood Graph. The performance of the algorithm using ns-2 and extensible Bluetooth simulator called blueware shows that even though RNG-FHR does not have superior performance, it is simpler and easier to implement in deploying the Ad-Hoc network in the distributed dynamic environments due to the exchange of fewer messages and the only dependency on local information. We realize that our proposed algorithm is more practicable in a reasonable size network than in a large scale.

• Journal of Korea Multimedia Society
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• v.24 no.3
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• pp.406-415
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• 2021

The worldwide spread of the Internet and the digital information revolution have resulted in a rapid increase in the use and transmission of multimedia information due to the rapid development of communication technologies. It is important to protect images in order to prevent problems such as piracy and illegal distribution. To solve this problem, I propose a new digital color image encryption algorithm in this paper. I design a new pseudo-random number generator based on 1D five-neighborhood maximum length cellular automata (FN-MLCA) to change the pixel values of the plain image into unpredictable values. And then I use a 3D chaotic cat map to effectively shuffle the positions of the image pixel. In this paper, I propose a method to construct a new MLCA by modeling 1D FN-MLCA. This result is an extension of 1D 3-neighborhood CA and shows that more 1D MLCAs can be synthesized. The safety of the proposed algorithm is verified through various statistical analyses.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.10
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• pp.3572-3590
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• 2014

Cellular automata (CA) based cryptosystem has been studied for almost three decades, yet most of previously reported researches focus on the symmetric key encryption schemes. Up to now, few CA based public key encryption scheme has been proposed. To fill the gap, in this paper, we propose a new public key encryption scheme based on layered cellular automata (LCA). Specifically, in the proposed scheme, based on the T-shaped neighborhood structure, we combine four one-dimensional reversible CAs (set as the private key) to form the transition rules of a two-dimension CA, where the two-dimension CA is set as the corresponding public key. Based on the hardness assumption of the Decisional Dependent CA problem in LCA, we formally prove the proposed scheme is indistinguishably secure against the chosen-plaintext attack (IND-CPA). In addition, we also use a numeric example to demonstrate its feasibility. Finally, analysis of key space and time efficiency are also carried out along with RSA-1024, and the simulation results demonstrate that our proposed scheme is more efficient.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.469-486
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• 2017

Economy-based urban redevelopment is the main priority in Malaysia, but has resulted in social problems such as gentrification, loss of heritage and identity, inequity, etc. Hence, it is crucial for the government to seek other alternatives rather than being solely reliant on urban redevelopment. Neighborhood renewal is a strategy involving the integration of redevelopment, rehabilitation, revitalization and preservation that aims to improve deprived areas using a more holistic approach. The aim of this paper is to review the neighborhood renewal policies in developed countries and to identify those elements that can be adopted in Malaysia. This study is conducted via a literature review. It was found that neighborhood renewal which integrates people-based, place-based and system-based policies highlights the importance of diversity, thereby aiming for resource optimization, community engagement and urban governance with the focal point of the fair, equity and systematic provision of resources. This paper concluded that neighborhood renewal in Malaysia should be initiated by locals with an emphasis on real local participation and a sustainable funding system. The government and local authorities should be observers rather than implementers.

• Journal of the Korean housing association
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• v.20 no.1
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• pp.71-82
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• 2009

The purpose of our study is empirically to identify residents' satisfaction by multi-family public rental housing and to find out another improvement to solve the housing problems facing the poor in Daegu. As a new way of settling the housing problems for the poor in city, as you know, multi-family public rental housing program was introduced by the Korean government in 2004 but rarely empirically evaluated so far. in the Residents' Satisfaction, There are no evaluation of multi-family public rental housing program except Kim's study (2006). Based on 160 survey data, we evaluated the multi-family Public Rental Housing Program within the framework of affordability in economics, a satisfaction in building and in neighborhood by a statistical method. As a result, we find out that residents on multi-family Public Rental housing are satisfied with the multi-family Public Rental Housing Program by and large. For mitigating the housing and economic problem of the poor more, self-support program as well as assistance in housing are needed and multi-family Public Rental housing Program must include neighborhood program more.

• Journal of the Korean housing association
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• v.27 no.1
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• pp.1-11
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• 2016

Based on residents' survey data in Seoul, this study attempts to empirically answer to four research questions regarding neighborhood relations (NR) which are necessary for community building: How important NR is compared to other social relations, what factors establish NR, how large NR's geographical extent is, and what are major meeting places among neighbors. A series of statistical analyses demonstrates that characteristics of NR vary greatly by family life cycle. In the stage of couple without child, NR has no significant meaning. NR becomes important from the stage of child care, and it is formed through the medium of children, particularly children's schools in the stage of child of elementary school as well as secondary schools. As the result, NR's geographical boundary extends beyond residential block or multi-family housing (apartment) estate while cafe and restaurant serve as dominant meeting places in these life cycle stages. On the contrary, after children are married and leave home, casual encounters resulted from spatial proximity become an important cause of NR. Likewise neighbors' geographical distribution is relatively concentrated within residential block or apartment estate, while community facilities play a role of meeting places as originally planned and designed.