• The KIPS Transactions:PartC
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• v.17C no.6
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• pp.441-450
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• 2010

Recently, a lot of interest is increased in sensor network which gathers various data through many sensor nodes deployed in wired and wireless network environment. However, because of the limitation in memory, computation, and energy of the sensor nodes, security problem is very important issue. In sensor network, not only the security problem, but also computing power should be seriously considered. In this paper, considering these characteristics, we make the sensor network consist of normal sensor nodes and clusterheaders with enough space and computing power, and propose a group key rekeying scheme adopting PCGR(Predistribution and local Collaborationbased Group Rekeying) for secure group communication. In our proposal, we enhance the security by minimizing the risk to safety of the entire network through verifying the new key value from clusterheader by sensor nodes. That is, to update the group keys, clusterheaders confirm sensor nodes through verifying the information from sensor nodes and send the new group keys back to authentic member nodes. The group keys sent back by the clusterheaders are verified again by sensor nodes. Through this mutual authentication, we can check if clusterheaders are compromised or not. Qualnet simulation result shows that our scheme not only guarantees secure group key rekeying but also decreasesstorage and communication overhead.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.6 no.4
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• pp.153-171
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• 2011

The welfare system and the direction of the welfare policy have been unable to escape greatly from the frame of the past against the facts that the external environments of the national economy of the world including Korea have been changing in quick and rapid speed. Such results have caused the issues related with the welfare, economy and society ended in the ideological collision in connection with the goals of the policy, the right agreement between the policies lacked, and the intervention and conflict between the interest group concerning the policy continued. Social policy of Korea in the past had the level of complementing the parts which could not be solved through the growth. Employment creation had been achieved continuously backed up by the high rate of growth. And the low aging level, the young population structure, and the high rate of childbirth had been the structures that made such achievement possible. New economic, social and welfare environment at home and abroad has been requesting new change in welfare policy. Goal of the economic and social policy is to construct the safe economic and social system. And what has been requested has been the formation of the economic and social policy orienting the welfare nation in form of social investment and welfare expansion. Also the direction in strengthening the welfare system of Korea shall have the balance between the protection and activation strength with the necessity of converting to the prevention welfare from the post welfare. Also the public part, market, the 3rd sector and the share of the role of an individual shall be achieved. And what is needed is the achievement of the transfer from the paradigm of residual welfare to the universal welfare. And such improvements of the welfare system will be able to elevate the possible continuity of the system in long term basis through the improvement of the welfare system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.8-15
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• 2018

This article investigates intelligent security integrated platform for real-time crime response and preventive crime prevention. This study analyzed intelligent crime prevention platform elements by analyzing crime prevention system/platform research, intelligent crime prevention research, and case study of municipality integrated operation center crime prevention system. Through this, we developed a practical intelligent security platform, and suggested a linkage with existing municipalities and smart city integrated platform system considering scalability. This enables CCTV monitoring, which is used only for existing post processing, to cope with real-time crime. It is expected that it will be able to solve the incidents in golden-time by grasping the precise position of the complainant not only in the outdoor but also indoors. It is also possible to provide citizen-centered crime-prevention social safety net information sharing service by enhancing citizen participation as well as improving control efficiency. The intelligent security platform has advantages that it is easy to spread the municipality because it is developed considering existing municipal system, smart city integration platform, and linkage and expansion with other security services.

• Nuclear Engineering and Technology
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• v.52 no.4
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• pp.721-733
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• 2020

In nuclear engineering, the occurrence of critical heat flux (CHF) is complicated for rod bundle, and it is much more difficult to predict the CHF when it is in natural circulation under motion condition. In this paper, the dryout-type CHF is investigated for the rod bundle in a natural circulation loop under rolling motion condition based on the coupled analysis of subchannel method, a one-dimensional system analysis method and a CHF mechanism model, namely the three-fluid model for annular flow. In order to consider the rolling effect of the natural circulation loop, the subchannel model is connected to the one-dimensional system code at the inlet and outlet of the rod bundle. The subchannel analysis provides the local thermal hydraulic parameters as input for the CHF mechanism model to calculate the occurrence of CHF. The rolling motion is modeled by additional motion forces in the momentum equation. First, the calculation methods of the natural circulation and CHF are validated by a published natural circulation experiment data and a CHF empirical correlation, respectively. Then, the CHF of the rod bundle in a natural circulation loop under both the stationary and rolling motion condition is predicted and analyzed. According to the calculation results, CHF under stationary condition is smaller than that under rolling motion condition. Besides, the CHF decreases with the increase of the rolling period and angular acceleration amplitude within the range of inlet subcooling and mass flux adopted in the current research. This paper can provide useful information for the prediction of CHF in natural circulation under motion condition, which is important for the nuclear reactor design improvement and safety analysis.

• Journal of Radiation Protection and Research
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• v.19 no.2
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• pp.121-132
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• 1994

This study concerns about the measurement and the investigation of environmental radiation characteristics which the components and the distribution of exposure rates by terrestrial y-rays in Taegu area. $4^{'}{\phi}{\times}4^{'}$ NaI(T1) scintillation detector with a multichannel analyzer was used in the measurement of y-rays as a part of in-situ spectrometry at twenty eight different locations in this area. The conversion into the exposure rate from the measured ${\gamma}-ray$ spectrum has been carried out leading to a net exposure rate and component ones by $^{40}K,\;^{238}U$ series and $^{232}Th$ series products which are known by the major parts in the terrestrial ${\gamma}-rays$ generally. As a result, the average exposure rate by the terrestrial ${\gamma}-rays$ in Taegu area is $9.4{\mu}R/h$ and the distribution of individual exposure rates shows more or less differences between these locations even after the consideration of diurnal and yearly variations which are always involved in these measurements. The component parts of exposure rates are distributed $^{40}K\;2.9{\sim}4.6{\mu}R/h,\;^{238}U$ series $1.2{\sim}3,\;1{\mu}R/h,\;^{232}Th$ series $2.5{\sim}5.0{\mu}R/h$ over the measured locations.

• Korean journal of applied entomology
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• v.43 no.3 s.136
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• pp.211-215
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• 2004

Temperature-fecundity of the melon aphid, Aphis gossypii Glover, was studied at constant temperatures ranging from 15 to $32.5^{\circ}C$ under $60-70\%$ RH and a photoperiod of 16 : 8 (L : D) A life table parameters were constructed using the results. The longevity of A. gossypii gradually increased with decreasing temperature below $27.5^{\circ}C$. Also fecundity increased with decreasing temperature and the highest fecundity was 61.8 nymphs per female at $17.5^{\circ}C$. However. daily fecundity increased with increasing temperatures up to $22.5^{\circ}C$ showing 5.9 nymphs per day and thereafter decreased. Longevity and fecundity of the adult in the greenhouse with an average temperature of $21^{\circ}C$ and $65.6\%$ RH, were 20.0 days and 59.6, respectively, which were longer and higher than those in the growth chamber with similar conditions. net reproductive rate (Ro) was 54.9 at $17.5^{\circ}C$ while intrinsic rate of increase ($r_m$) and finite rate of increase ($\lambda$) were the highest 0.5 and 1.6 at $30^{\circ}C$, respectively. doubling time (DT) and mean generation time (T) were the shortest 1.4 and 6.8 at $30^{\circ}C$ indicating that optimal temperature for the development is $30^{\circ}C$.

• Korean Journal of Social Welfare
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• v.54
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• pp.295-319
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• 2003

The study starts from the critical thought on why most of female-headed single-parent families are under poverty regardless of their hard working. The study is to explore the lives of low-income single-parent families as working poor and to develop comprehensive policies for them out of poverty and other social vulnerability, using the concept of social exclusion which has been broadly introduced in the field of social science. Specifically, the study aims to analyse the process of social exclusion of low-income single-parent households, by comparing the differential lives in the economic, social, political aspects among male-headed dual-parent household, female-headed single-parent household, and poor female-headed lone-parent household who is under the public poverty line. The study was based on the secondary data analysis. A total of 3182 samples(the first 2508, the second 235, and the third 439) were included. Using SAS 6.12, frequency, chi-square, means, and ANOVA were utilized for the statistical analysis. Results show that single mothers, on the whole, are vulnerable population in terms of employment, housing stability and income. Also, low-income households of single mothers are more negatively affected by the IMF economic crisis and carry more pessimism on their future. In comparison with male-headed households, single mothers have fewer support from social insurance as well as family resources and higher burdens of additional caring need for the old, the disabled, and the chronically ill. These findings identify the reality in which female-headed households with dependent children are exposed to the overall social vulnerability and thus are easily trapped into the social disadvantaged. finally, the study suggests the development of comprehensive policies and counter-measurements for low-income female-headed families to be the primary member in our society.

• Korean Journal of Social Welfare
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• v.67 no.4
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• pp.31-50
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• 2015

This study attempted to empirically investigate the determinants of poverty transition of the working poor with disabilities from a dynamic perspective. Analyses were conducted on the data from Panel Survey of Employment for the Disabled(PSED, Year 1-6), included the households with a disabled head of household. The working poor were defined as the household of which income fell below 120% of the absolute poverty line among the households just described. As results, The 6-year mean poverty rate for the working poor with disabilities included in the analysis was 31.4%, approximately three times of the poverty rate of the total population and the working poor with disabilities were found to have greater difficulty with poverty exit once having fell into poverty than all households living in poverty. And it was found that the economic activity factor was the key determinant of in-work poverty. In addition, employment of the working poor with disabilities did not lead straight to poverty exit, and the quality, rather than the status of, employment was the key determinant of poverty exit. The implications of the findings of this study are that it is essential to increase decent jobs, expand the social safety net of the working poor with disabilities and establish poverty reduction measures for each class of the working poor with disabilities to exit from poverty.

• Journal of Navigation and Port Research
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• v.29 no.1 s.97
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• pp.9-15
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• 2005

To design ship channel is one of important factors for planning and developing a port. In most case, the core factors for designing ship channel are the layout and width of channel provided the net underkeel clearance is secured to be safe enough to pass. In this study, Variable Bumper Area(VBA) model is applied to design and assess ship channel. This model reflects ship's particular, ship domain theory, ship speed and mariner's ship handling skill and experience, especially external forces which cause leeway, set and drift and the change of ship maneuvering characteristics. A real time, full mission shiphandling simulator is used to analyze ship dynamic data according to mariner's ship control, external forces, ete. This model defines Domain degree and Domain-index for assessing the efficiency and safety of the channel. The proposed model is applied to Ulsan new port plan which has a channel width of 1.5 times the length of the largest vessel, a radius of 5 times the length of the largest vessel in a curve of 57 degree centerline angle and SBM facility adjacent to the lateral edge of channel. The result of this study shows that the width of the channel and radius of channel curve are suitable for the target ship but the difficulty of ship handling is caused by the large course change and SBM located in the vicinity of channel.

• Korean Security Journal
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• no.20
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• pp.229-248
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• 2009

This research is looking for the private security industry and diagnostic issues and enable our strategy will be presented through SWOT analysis for the management environment of private security industry to ultimately contribute to the private security industry. Along, the purpose of this research is to want to reach key factors which affect the competitiveness of the private security industry. This study was to conduct literature research and surveys. And analyzing literature and data was collected. And determined the status of private security industry by conducted a comprehensive survey with 13 experts is causal. The question investigation hemisphere the question which harmonizes became accomplished in the center. Like this question analyzed the opinion of the identical research participant and 3 times was executed repetitively, and 2 to verify the data through multiple data as a basis for the SWOT analysis of the environment. Accordingly, the following conclusion emerges. First, the private security industry-related legislation will complement the systematic. This is the task of the public security authority and the relationship will be in the direction for improvement. Second, to develop strategies for diversification of products and services through the use of IT. This business what development security services and products based on IT advanced technology can provide a solution to maximize profits to large security companies and to all of the small companies. Third, it should seek ways to make exports that social safety net project based on security technology and capital of Kore for other Asian countries or developing countries in the world.