• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.5
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• pp.917-926
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• 2019

At present, TICN has been developed and distributed for military command control. TICN is known as the 3.5G mobile communication technology based on WiBro, which shows technical limitation in the field operation situation. Accordingly, the drone-type base station platform is attracting attention as an alternative to overcome technical limitations such as difficulty in securing communication LoS and limiting expeditious network configuration. In this study, we performed simulation performance evaluation of drone-type base station operation in 28 GHz that is considered most suitable for cellular communication within mmWave frequency band. Specifically, we analyzed the changes in throughput and fairness performance according to radio resource management policies such as frequency reuse and scheduling in multi-cell topology. Through this, we tried to provide insights on the operation philosophy on drone-type base station.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.5
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• pp.3-10
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• 2004

A Wireless Lan has an importance of access control, because we can use wireless Internet via AP(Access Point). Moreover, to use wireless LAN, we will go through authentication process of EAP. DoS(Denial of Service) attack is one of the fatal attack about these AP access and authentication process. That is, if malicious attacker keeps away access of AP or consumes memory of server and calculation ability of CPU and etc. compulsorily in authentication process, legal user can't get any services. In this paper, we presents the way of protection against the each attack that is classified into access control, allocation of resource, attack on authentication protocol. The first thing, attack to access control, is improved by pre-verification and the parameter of security level. The second, attack of allocation of resource, is done by partial stateless protocol. And the weak of protocol is done by time-stamp and parameter of access limitation.

• Journal of Korean Society of Rural Planning
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• v.30 no.2
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• pp.1-11
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• 2024

Farmland transaction prices are affected by various factors such as politics, society, and the economy. The purpose of this study is to identify multiple factors that affect the farmland transaction price due to changes in the actual transaction price of farmland by farmland unit from 2016 to 2020. There are several previous studies analyzed the determinants of farmland transaction prices by considering spatial dependency. However, in the case of land transactions where the time and space of the transaction affect simultaneously, if only spatial dependence is considered, there is a limitation in that it cannot reflect spatial dependence that occurs over time. In order to solve these limitations, To address these limitations, this study builds a spatio-temporal autoregressive model that simultaneously considers spatial and temporal dependencies using farmland transactions in Jinju City as an example. As a result of the analysis, it was confirmed that there was significant spatio-temporal dependence in farmland transactions within the previous 30 days. This means that if the previous farmland transaction was carried out at a high price, it has a spatio-temporal spillover effect that indirectly affects the increase in the price of other nearby farmland transactions. The study also found that various location attributes and socioeconomic attributes have a significant impact on farmland transaction prices. The spatio-temporal autoregressive model of farmland prices constructed in this study can be used to improve the prediction accuracy of farmland prices in the farmland transaction market in the future, and it is expected to be useful in drawing policy implications for stabilizing farmland prices

• Korean Journal of Social Welfare
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• v.54
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• pp.149-176
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• 2003

The purpose of this study is to examine the degree of community integration of visually impaired people who have the limitation of mobility in comparison with another disabled and to find factors affecting community integration. The data were obtained through telephone interview with visually impaired people. The final sample was consisted of 1,004 respondents. The data were analyzed using statistical techniques such as crosstabulation, t-test, and hierarchical regression. In this study, the factors affecting community integration was divided into four dimensions : the attribution to disability, physical functioning, psychology and social support system. The major findings of this study were as follows: First, the factors affecting community integration of visually impaired people were age, education, economic status, social support, information support and participation of rehabilitation service. Second, the factors affecting community integration of the low vision and the blind are the limitation of daily activities and social support. But the factors affecting community integration of the blind are participation of education for braille and that of the low vision are information support and participation of rehabilitation service. Finally, the person losing eyesight since school age were the more limitation of daily activities than the person losing eyesight in babyhood. The factors affect community integration of the former are social support, information support, participation of education for braille, and rehabilitation service. The current findings suggest that intervention and policy aimed at improving social support system and formal services such as education, rehabilitation services should be considered by rehabilitation professionals and policy makers.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.6
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• pp.2730-2747
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• 2016

Due to the limitation of the bandwidth resource and capture resolution of depth cameras, low resolution depth maps should be up-sampled to high resolution so that they can correspond to their texture images. In this paper, a novel depth map up-sampling algorithm is proposed by exploiting the fractal internal self-referential feature. Fractal parameters which are extracted from a depth map, describe the internal self-referential feature of the depth map, do not introduce inherent scale and just retain the relational information of the depth map, i.e., fractal transforms provide a resolution-independent description for depth maps and could up-sample depth maps to an arbitrary high resolution. Then, an enhancement method is also proposed to further improve the performance of the up-sampled depth map. The experimental results demonstrate that better quality of synthesized views is achieved both on objective and subjective performance. Most important of all, arbitrary resolution depth maps can be obtained with the aid of the proposed scheme.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.2
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• pp.91-103
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• 2002

For massive FPGA based emulator, the interconnection architecture and the transmission method of signals between FPGA's are important elements which decide speed of emulation and extendability of emulator. Existing FPGA-based emulation system is faced the problems of which the emulation speed getting slow drastically as the complexity of circuit increases. In this paper, we proposed a new innovative emulation architecture that has high resource usage rate and makes the fast emulation Possible. The emulator with very unique hierarchical ring topology Presented here has merits to overcome FPGA pin limitation by connecting each FPGA into a set of pipelined rings, and it also makes emulation speed at the tens of MHz at least even at system level where the verification complexity can easily exceed the verification capability of designers.

• Korean System Dynamics Review
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• v.16 no.2
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• pp.75-100
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• 2015

The purpose of this study is to analyze causation of Ecosystem service's trade-off(ES trade-off) and to establish baseline data for wise spatial planning and management. In order to understand why and how ES trade-off occurs, systems thinking and causal loops were employed. The causal loop of ecosystem service creation cycle includes profits quantification process, decision making process, spatial planning and management process, and ecosystem services creation process. The profits quantification process has a limitation that all ecosystem service categories were not included in profits quantification, because quantification method for cultural services is insufficient. These problems led to unequal discussion opportunity in decision making process. ES trade-off occurs through transition of ecosystem function in spatial scale and temporal scale. In spatial scale, land-use variation and resource-use variation contribute to change an ecosystem function for different ES category by spatial planning and management. In temporal scale, a change of an ecosystem function for different ES category is influenced by ecological succession, seasonal change and land cover variation, which are parameter from environmental features. This study presented that spatial planning and management should ecosystem service assessment in order to enhance balanced ecosystem services.

• International Journal of Quality Innovation
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• v.4 no.1
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• pp.131-147
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• 2003

This paper considers that a public department under specialized TQM manpower constraints have to implement multiple total quality management (TQM) policies to promote its service performance (fundamental goal) by adopting a centralized sequential advancement strategy (CSAS). Under CSAS, the decision-makers (DMs) start off by focusing specialized TQM manpower on a single policy, then transfer the specialized TQM manpower to the next policy when the first policy reaches the predetermined implementation time limit (in terms of education and training). Suppose that each TQM policy has a different desirous education and training goal. When the desirous goals for all TQM policies are achieved, we say that the fundamental goal will be satisfied. Within the limitation of total implementation period of time for all policies, assume the desirous goals for all TQM policies cannot be achieved completely. Under this premise, the optimal implementation sequence for all TQM policies must be calculated to maximize the weighted achievement of the desirous goal. We call this optimization problem a TQM case of "centralized sequential decision-making problem (CSDMP)". The achievement of the desirous goal for each TQM policy is usually affected by the experience in prior implemented policies, which makes solving CSDMP quite difficult. As a result, this paper introduces the concepts of sequential effectiveness and path effectiveness. The structural properties are then studied to propose theoretical methods for solving CSDMP. Finally, a numerical example is proposed to demonstrate CSDMP′s usability.

• IE interfaces
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• v.17 no.spc
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• pp.11-19
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• 2004

The purpose of this study is to identify the determinants of new venture performance according to years of operation in the view of integrated research framework. We propose the integrated new ventures performance model which is composed of entrepreneur, organization/resources, industrial environment, strategy/foundation process and availability of supporting systems as corresponding variables to new ventures performance. The determinants of new venture performance according to years of operation are identified through the multi-variate statistical analysis such as moderating regression analysis with the data gathered from 110 executives of venture companies. For internal variables, entrepreneur's managerial ability and technical expertise and employee's ability affect venture's performance increasingly as years of operation increases but resource procurement ability affects decreasingly. Related to external variables, years of operation plays positive moderating role on market size growth and supporting system availability, but negative role on government venture policy for venture performances. Though this study has limitation of small sample, limited questionnaire and performance measure, it has managerial contribution of identifying determinants of new venture performance according to years of operation.

• Journal of the Korean Society of Groundwater Environment
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• v.7 no.1
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• pp.8-14
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• 2000

The present day, interest in low flow statistics has been increased, primarily because of the increase in water demands and the contamination of water quality and the limitation of water resource development and the annual water supply stability. The model for estimating low flow statistics is points of this study chosen catchments in the Youngsan basin. For the purpose of this study. the low-flow discharge at 23 points, where absent gauging station is unmeasured and the data is used for the model. Finally, the regional formula to estimate the low flow statistics at the unmeasured point is proposed.