• Korean Security Journal
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• no.29
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• pp.87-113
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• 2011

Korean security industry has history of more than half a century, and it is growing fast. Private security industry contributes not only to livelihood safety, but also to national security. The area of the industry is being expanded. Security Act is closely related to the security industry, and has contributed to the growth of private security industry sector. Security Act of Korea, which was established in 1976, was originally made after Japanese Security Act. But nowadays, Korean Security Act is as systematic as the Japanese act. However, for 10 years, Security Act of Korea has been stagnant, not able to reflect security industries' demand. The writer has contributed to the development of Security Act. In 1995, the writer wrote the basic framework of Security Instructor Qualifications System and drafted Security Act in 2002. There are currently many problems in existing Security Act, but there are four representative problems. (1) No more establishment of new security sector, (2) excessively slack qualification criteria, (3) the education system for guards, (4) the security Instructor examination system. This paper derives problems of current Security Act, and suggests solutions for them. Not only the academic world, but all of us should pay attention to the revision of Security Act.

• Korean Security Journal
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• no.43
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• pp.7-35
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• 2015

The Ministry of Public Safety and Security was established in order to handle all sorts of disasters because of Sewol ferry tragedy and the fundamental reform on the emergency management system will be performed. The establishment of the Ministry of Public Safety and Security is considered as the landmark for the emergency management when it is compared to those in the United States and Japan in terms of the size and the authority. However, there are many tasks to be done for the settlement of the Ministry of Public Safety and Security. More specifically, a real and substantial plan should be prepared because the organization was established without blueprints or detailed implementation plan. This study suggests that all-hazard approach which is the one of the disaster management principles should be applied when the substantial plan is prepared. All possible hazard should be analyzed, assessed, and prioritized. In addition, Based on the results, the effective policies should be established with the consideration of Korean context.

• Korean Journal of Applied Biomechanics
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• v.24 no.2
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• pp.111-119
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• 2014

The purpose of this study was to investigate the effects of localized muscle fatigue and whole body fatigue on postural control during single-leg stance after impairment induced by heel raise and the Harvard step test. Thirty-eight university students (19 men: age, $20.1{\pm}0.2$ yrs; height, $175.0{\pm}5.23cm$; weight, $66.8{\pm}5.6kg$; body mass index, $21.8{\pm}1.7kg/m^2$, 19 women: age, $20.6{\pm}1.1yrs$ ; height, $163.6{\pm}6.7cm$; weight, $58.8{\pm}4.6kg$; body mass index, $22.0{\pm}2.2kg/m^2$) were participated in this study. Subjects performed a series of single-leg postural tasks prior to, following, and 24 hours after completing: heel raise or the Harvard step test. This study showed that the root mean squared distance and velocity in the anteroposterior and mediolateral planes of the center of pressure decreased significantly due to heel raise exercise-induced fatigue. Furthermore, the root mean squared distance in the anteroposterior and mediolateral planes, and the 95% confidence ellipse area of the center of pressure also decreased significantly 24 hours after completing the Harvard step test. In conclusion, this study showed that both heel raise exercise- and Harvard step exercise-induced fatigue affects postural control during single-leg stance in AP and ML planes. Furthermore, this study suggests that changes in the postural control strategy may have occurred after the fatigue protocols during single-leg stance. Also vision can attenuate the postural deficits associated with the fatigues. In order to clarify these results, further studies using other equipment and variables are necessary.

• Korean Journal of Applied Biomechanics
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• v.18 no.3
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• pp.23-31
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• 2008

The purpose of this study was to investigate proper sampling duration while executing quiet stance of feet together position and a preferred foot position with eyes open using COP variables through GRF system. The subjects participated in this study were twenty healthy elderly women individuals($68.9{\pm}6.8$ years). It represented that the sampling duration needed over 20 s in the FTP and over 60 s in the PFP during assessment of quiet stance. The sampling duration shorter than 20 s in the FTP and 60 s in the PFP may not provide the sample showing stability. Inversely if the sampling duration becomes longer, it can distort the sample showing stability. In the future, I expect more studies of the proper sampling duration through various groups and the study of characteristics of participants caused by more sampling duration.

• Journal of the Korean Society of School Health
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• v.28 no.1
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• pp.1-9
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• 2015

Purpose: The purpose of this study is to examine the effect of sleep duration on suicidal ideation in Korean adolescents. Methods: This study used the data drawn from Korea Youth Risk Behavior Web-Based Survey in 2013. A total data of 63,301 adolescents were included in the analysis. Included variables were general characteristics, health status variables, hours of sleep, and suicidal ideation. For sample description weighted percentage and means were used. Rao-Scott ${\chi}^2$ test and simple and multiple logistic regression with dummy variables were conducted with use of SAS 9.2. Results: Among general characteristics and health status variables, gender, grade, school level, school achievement, family's economic status, living with parents, subjective health, happiness, stress, and feeling of despair were found to be significantly related to suicidal ideation. Rates of having suicidal ideation were 22.4% in the case of students with less than 5 hours of sleep and 12.9% in students with 8 or more hours of sleep. After controlling general characteristics and subjectively perceived variables, hours of sleep was still significantly related to suicidal ideation. That is, compared to adolescents with 8 hours or more of sleep, those with less than 5 hours of sleep showed significantly higher risk for having suicidal ideation (adjusted odds ratio: 1.20, p<.001). Conclusion: These findings suggest that short sleep has negative effects on psychological health in adolescents. Particularly, less than 5 hours of sleep has harmful effect on adolescents' increased risk for having suicidal ideation.

• Informatization Policy
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• v.20 no.1
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• pp.85-109
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• 2013

This study presents a model and its implementation methodology assessing not only maturity but also applicability in order to increase the practical usage of open source software(OSS). Since this model measures applicability which can not be assessed by the previous models, it is able to support users in many ways when they introduce OSS for the first time, replace commercial software with OSS, and compare OSS with commercial software. For the purpose of design and implementation of this model, we presented a methodology with 7 phases and conducted a survey to evaluate the appropriateness and reliability of the model. In addition, we proved the practical usability of the model by providing a practical example assessing maturity and applicability of OSS in the area of the infra category on the basis of the methodology. In the future, not only general users but also officers in charge of informatization will be able to select optimal OSS by using this model for industrial application. Therefore, the result of this research is expected to greatly contribute to OSS promotion policy.

• Polymer(Korea)
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• v.29 no.1
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• pp.32-35
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• 2005

In this paper, the carbon nanotubes (CNTs) were ozonized and the positive temperature coefficient (PTC) behaviors of CNTs-filled high-density polyethylene (HDPE) conductive composites were studied. The results of element analysis (EA) and FT-IR indicate that the oxygen-containing functional groups on the CNTs surfaces, such as O-H, C-O, and C＝O groups, were increased with the ozonization. Electrical resistivities of the CNTs/HDPE composites were measured by using a digital multimeter. The resistivity of the composites was increased abruptly near the crystalline melting temperature of the HDPE used as matrix, which could be attributed to the destruction of conductive network by the thermal expansion of HDPE. And, the PTC intensity of the CNTs/HDPE composites was increased with the increase of the ozone treatment time. It was probably due to the growing of maximum volume resistivity of the composites induced by the increased oxygen-containing functional groups in the CNTs surfaces.

• Polymer(Korea)
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• v.29 no.1
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• pp.8-13
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• 2005

Polystyrene (PS) particles containing the phase change material (PCM) were synthesized by miniemulsion polymerization. The polymer particles prepared with different parameters were investigated in terms of average particle size, particle distribution, and latent heat storage of encapsulated paraffin wax (PW) as PCM. The morphology and particle features of PS particles were analyzed by scanning electron microscope and particle size analyzer, respectively. As a result, the diameters of PS particles were adjusted with manufacturing conditions. The stable and spherical PS particles of nanosize were obtained by miniemulsion polymerization, which could be attributed to the prevention of Ostwald ripening by cosurfactant. Thermal properties of PS particle containing PCM were studied by differential scanning calorimetry. From DSC freeze-thaw cycle, PCM coated with PS exhibited the thermal energy storage and release behaviors, and the latent heat was found to be a maximum 145 J/g. It was noted that PS particles containing PCM showed a good potential as a thermal energy storage medium.

• Nuclear Engineering and Technology
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• v.5 no.3
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• pp.191-201
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• 1973

For fast neutron spectroscopy in MeV region, a recoil proton telescope detector was designed and constructed so as to increase in detection efficiency without appreciable deterioration in energy resolution by adopting a special type of recoil proton radiator which is a combination of a ring-shaped vertical radiator and a cone-shaped horizontal radiator at a certain geometry. A neutron stopper was built in the detector system to minimize the background due to direct exposure of the Si(Li) detectors to primary incident neutrons. The detection efficiency and the energy resolution calculated at various neutron energies and geometries are given and these characteristics of the detector system were tested by 14.1 MeV neutrons. As the calculation predicted, the relative detection efficiency in case of the combined radiator system is almost 2.2 times of that for a single, ring-shaped vertical radiator system. The calculated energy resolution is 3.7% FWHM, whereas the measured resolution was 3.9% which means resolution broadening of approximately. 30% was resulted by introducing a combined radiator system into the telescope. Increase in background less than 40% was also observed.

• Nuclear Engineering and Technology
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• v.41 no.6
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• pp.821-830
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• 2009

In this paper, modal testing and finite element modeling results to identify the modal parameters of a nuclear fuel rod as well as its cladding tube are discussed. A vertically standing full-size cladding tube and a fuel rod with lead pellets were used in the modal testing. As excessive flow-induced vibration causes a failure in fuel rods, such as fretting wear, the vibration level of fuel rods should be low enough to prevent failure of these components. Because vibration amplitude can be estimated based on the modal parameters, the dynamic characteristics must be determined during the design process. Therefore, finite element models are developed based on the test results. The effect of a lumped mass attached to a cladding tube model was identified during the finite element model optimization process. Unlike a cladding tube model, the density of a fuel rod with pellets cannot be determined in a straightforward manner because pellets do not move in the same phase with the cladding tube motion. The density of a fuel rod with lead pellets was determined by comparing natural frequency ratio between the cladding tube and the rod. Thus, an improved fuel rod finite element model was developed based on the updated cladding tube model and an estimated fuel rod density considering the lead pellets. It is shown that the entire pellet mass does not contribute to the fuel rod dynamics; rather, they are only partially responsible for the fuel rod dynamic behavior.