• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.3
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• pp.29-45
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• 2017

Ad hoc sensor network is characterized by decentralized structure and ad hoc deployment. Sensor networks have all basic features of ad hoc network except different degrees such as lower mobility and more stringent energy requirements. Existing protocols provide different tradeoffs among some desirable characteristics such as fault tolerance, distributed computation, robustness, scalability and reliability. wireless protocols suggested so far are very limited, generally focusing on communication to a single base station or on aggregating sensor data. The main reason having such restrictions is due to maximum lifetime to maintain network activities. The network lifetime is an important design metric in ad hoc networks. Since every node does a router role, it is not possible for other nodes to communicate with each other if some nodes do not work due to energy lack. In this paper, we suggest an experimental ad-hoc on-demand distance vector routing protocol to optimize the communication of energy of the network nodes.The load distribution avoids the choice of exhausted nodes at the route selection phase, thus balances the use of energy among nodes and maximizing the network lifetime. In transmission control phase, there is a balance between the choice of a high transmission power that lead to increase in the range of signal transmission thus reducing the number of hops and lower power levels that reduces the interference on the expense of network connectivity.

• Tunnel and Underground Space
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• v.17 no.5
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• pp.411-427
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• 2007

Reliability in tunnel analysis is necessary to accomplish technically sound design and economical construction. For this, a thorough understanding of the construction procedure including the ground-support interaction has to be obtained. This paper describes a proper modelling technique to simulate the behavior of the steel fiber reinforced shotcrete (SFRS) which maintain the supporting capability in post-failure regime. The additional supporting effect of the steel support was also verified by 3-D analyses and a new load distribution factor were proposed. The use of the plastic moment limit (PML) alone can eliminate the occurrence of the awkwardly high tensile stress in the shotcrete and can successfully model the post-peak ductile behavior of the SFRS. But with this method, moment is limited whenever the stress caused by moment reaches tensile strength of the shotcrete irrespective of the stress by axial force. Therefore, it was necessary to find a more comprehensive method which can reflect the influence of the moment and axial force. This can be accomplished by the proper use of "liner element" which is the built-in model in FLAC. In this model, the peak and residual strength as well as the uniaxial compressive strength of the SFRS can be specified. Analyses were conducted with these two models on the 2-lane road tunnels excavated in class IV and V rock mass and results were compared with the conventional elastic beam model. Results showed that both models can reflect the fracture toughness of the SFRS which could not be accomplished by the elastic beam model.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.3
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• pp.188-197
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• 1999

In order to estimate the uranium flux from seawater to sediments, we took pore water samples and deployed benthic chambers on seafloor of Chonsu Bay, Korea. The uranium flux across the sediment-water interface was estimated from the pore water to be 0.112-0.566 mg/$m^2yr$, corresponding to a removal flux of $4.3-21.5{\times}10^7$ gU/yr for the entire Yellow Sea. Nutrient fluxes from sediment to bottom water were estimated to be 135.6 mmol/$m^2yr$ for ammonia, 228.2 mmol/$m^2yr$ for nitrate, 36.8 mmol/$m^2yr$ for phosphate and 23.9 mmol/$m^2yr$ for silicate. The redox boundary, based on the distribution of pore water nitrate and solid phase manganese, was located at 3-5 cm below the sediment surface. Phosphate flux obtained by benthic chambers was 28.S mmol/$m^2yr$. On the other hand, estimates of uranium and silicate fluxes were orders of magnitude greater than those based on pore water profiles. Flux estimates on the basis of pore water concentration is believed to have greater reliability than those obtained from benthic chamber data.

• Korean Security Journal
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• no.46
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• pp.63-86
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• 2016

The object of this study is to propose a study on the Private Investigator usage for Cyber Crime. The latest trend of cyber crime is being evolve in sophisticated and complex way over the global, like internet fraud, cyber gambling, hacking and etc. Hence national investigative authority mobilize high specialized skills and method of criminal investigation by each nation. But it is hard to respond in rapid and effective way because of propoor, distribution of group and insufficient of related legal system. Already in other countries, not considerable amount of services are given to private investigators in detection and tracking part which is inefficient by nation. So it has significantly meaningful to compensate the defect and study about private investigator usage as companion of cooperation policing for effectively respond to cyber-crime. The way to effectively deal with the cyber-crime is reevaluate meaning of partnership policing and need of private investigator usage. Also it is to analyze the main issue about introduction of a system and suggest the effective way of introduction. First, legislation of private investigator usage which is based upon partnership policing should be made up. Moreover, to establish the range of private investigator's business and enhance the reliability, it is to propose introduction of leading professional global certificate and license system with sufficient education and test. We are expecting introduction of private investigator usage can improve efficiency of investigation and promote effective countermeasures of cyber-crime.

• Journal of Technologic Dentistry
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• v.34 no.4
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• pp.433-445
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• 2012

Purpose: In order to validate empirically the theoretical model of this study subjects, who were limited in Andong gun, Youngyang gun, Uiseong gun, Bonghwa gun, Chilgok gun, Cheongsong gun according to residence-specified distribution and over aged 65, were focused to the elderly in rural areas with geographical characteristics where they have difficulties in accessibility of dental facilities and dental care. Methods: The collected data were analyzed by the SPSS 19.0 program. First, the frequency analysis was performed for each independent variable and the dependent variable. Second, reliability analysis and correlation analysis were conducted for daily living skills and Biomedical Vigilance. Third, multivariate analysis was performed in terms of and the post-administration management. Fourth, multiple regression analysis was performed to identify the factors affecting the post-management of dentures and the period of using dentures. Results: By results of the multiple regression analysis, the elder the subjects are(${\beta}$ = 0.03), the lower their income activities are(${\beta}$ = -0.18), the smaller their monthly allowances are(${\beta}$ = -0.16), the worse their daily activity skills are(${\beta}$ = -0.12), the more they were mounted their dentures by an unlicensed contractor(${\beta}$ = 0.07), and the more they cost to their dentures(${\beta}$ = 0.14), the longer the period of use dentures are. And the beneficiaries of Basic Livelihood Security(${\beta}$ = -0.14) who got free denture business are shorten the period of using dentures. According to multiple regression analysis for post management of dentures, the independent variables like the health education(${\beta}$ = 0.24), smoking(${\beta}$ = -0.18), periodic oral examination(${\beta}$ = 0.13), dentures mounted by an unlicensed contractor(${\beta}$ = -0.13) are shown statistically significant results. In that study subjects are taking part in health education and non-smokers, they are likely to have more chances to post management for their dentures like periodic oral examination. However the subjects who were weared their denture by an unlicensed contractor get less chance to post management for their dentures. Conclusion: As the elderly who want to wear denture are increasing due to the denture insurance for the elderly, the need for oral health education for the elderly is an urgent request, especially continuos education for the way of use their dentures and follow-up management for the elderly who were already mounted their dentures. And also, the need for more systematic researches is requested for securing objective data.

• The Korean Journal of Emergency Medical Services
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• v.5 no.1
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• pp.147-164
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• 2001

The purpose of this study was to examine the hypothetical model designed to explain the post-traumatic stress and burnout in firefighters. Six exogenous variables such as career, control, impact mobilization frequency, life event, work burden, social support, and four endogenous variables, eg., mobilization impact, coping, post-traumatic stress, burnout were considered for the study. The target population for the distribution of the questionnaire was 428 firefighters in Daejeon, Chungnam Province, Seoul and Kyonggi Province. The data was collected about five weeks, July 12-August 25, 1999. The survey instrument was 8 control items by Seo(1995), 10 life event items by Brugha and Cragg(1990), 20 work burden items by Choi(2000), 12 social support items by Park(1985), post-traumatic stress of 17 items by Foa et al.(1998) and 45 items by Kang(1997). The reliability of the survey instrument and the cronbach's alpha was .62 - .93 level. SAS PC Program and LISREL 8.12a program were used for descriptive statistics and linear structural relationship(LISREL) modeling. Based on the data collected, the following results were obtained. 1. The overall fit of the hypothetical model to the data was good (${\chi}^2=54.65$ [df=17, p=0.000007], RMSEA=0.07, standardized RMR=0.03, GFI=0.98, AGFI=0.91, NFI=0.90, NNFI=0.75). 2. After considering statistical significance and theoretical meaningfulness of paths of the model, a modified model was sought. Compared to the hypothetical model, the modified model has become parsimonious and had a better fit to the data(${\chi}^2=55.90$ [df=20, p=0.0003], RMSEA=0.06, standardized RMR=0.03, GFI=0.98, AGFI=0.93, NFI=0.90, NNFI=0.80). 3. The results of statistical testing of hypotheses were as follows: (1) Work burden, career had a significantly direct effect on mobilization impact. These variables explained 9% of the total variance of mobilization impact. (2) Control, social support, work burden, mobilization impact had a significantly direct effect on coping. These variables explained 15% of the total variance of coping. (3) Control, work burden, social support, coping had a significantly direct effect on post-traumatic stress. These variables explained 49% of the total variance of post-traumatic stress. (4) Coping, post-traumatic stress had a significantly direct effect on burnout. These variables explained 60% of the total variance of burnout.

• Journal of the Korean Institute of Gas
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• v.5 no.3 s.15
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• pp.45-50
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• 2001

Open rack vaporizer (ORV) has been used in liquefied natural gas (LNG) receiving terminal in order to vaporize LNG into natural gas (NG) by heat exchange with seawater The U-type ORV which had been operated with seawater for 14 years is one of the important utilities of the gas production and the weld part of tube connected with header_ pipe had experienced many corrosion problems. To elucidate the cause of corrosion at weld part of vaporizer tube, corrosion potentials were compared by parts. This study concerns on the measurement of corrosion pit depth using non-destructive method and the evaluation of stress distribution in an aspect of safety with finite element analysis. In order to confirm the reliability of galvanic corrosion between weld parts and base metal, the measurement of corrosion potential by parts was conducted for 20 minutes in 3.5$\%$(wt.) NaCl solution. Many non-destructive methods were tried to measure the remaining thickness of vaporizer tube at fields. For general corrosion, tangential radiography test was confirmed as an effective method. In case of a fine corrosion pit, the shape of corrosion pit was reproduced using surface replication method. From collected data, stress distributions were quantitatively evaluated with 2-dimensional finite element method and the diagnostic evaluation on internal pressure of the U-type vaporizer could be made.

• Ocean and Polar Research
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• v.31 no.1
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• pp.31-50
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• 2009

The demarcation of Maritime Boundary is directly related to the expansion of jurisdiction and the securing of resources. Resource diplomacies of the three countries Korea, China and Japan represent a major task for the national administrations : to secure resources as well as to stablize and sustain resources for future national economies. At the sea area around Korea as well, countries are fiercely competing to secure resources and to expand jurisdiction. This is evidenced by the fact that various principles and logics which are beneficial to each own country are presented through international precedents, agreement between countries and the theories of the international law scholars. They say that the conclusion of demarcation of maritime boundary for the Yellow Sea would be easy from the point that there is no dispute related to island dominion in the waters of the Korean Peninsula especially the Yellow Sea, but still we need to have a strategic approach to this issue from the point that the factors used for claiming maritime boundaries may expand the waters of a country over much. For example, the continental shelf boundary in consideration of the distribution of sedimentary deposits in the Yellow Sea which is being raised by China began from the hypothesis that the inflow of sedimentary deposits to the Yellow Sea through the rivers of China represents absolute majority, but the results of the latest studies raised questions on the hypothesis. Especially, the studies done by Martin and Yang revealed that the inflow of sedimentary deposits to the Yellow Sea from the Yellow River is approximately less than 1% of total sedimentary deposits in the Yellow Sea, and also the result of analysis on the causes and counter policy measures on the environment of Bohai, China supports the reliability of the results of such studies. From a legal aspect, the sedimentary deposits of rivers which are claimed by China represent extremely weak ground for the claim for the title of the continental shelf. The siltline claimed by China seems to be based on the Article 76-4-(a)(i) of UNCLOS. This is, however, not the definition on the title of the continental shelf but it is only a technical formula to utilize in a case where a country desires to expand the continental shelf to over 200 nautical miles. Scientific and Technical Guidelines of the Commission on the Limits of the Continental Shelf also confirm this point through the Article 2.1.2 of the Guideline. The only case in which sedimentary deposits of rivers were referred to as concrete demarcation of maritime boundary was in the which was concluded in 1986 between India and Myanmar at the Andaman Sea. In the said case, India acknowledged the boundary up to the isobath of 200m which Myanmar claimed based on the sedimentary deposits of the Irrawaddy River. It has limits as a case for acknowledging the sedimentary deposits, however, because in fact India's acknowledgment was made in exchange for the condition that Myanmar gave up the dominion of two islands which they had been claiming from India up until that time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.817-822
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• 2017

The braking system is one of the most important components in vehicles and machines. It must exert a reliable braking force when they are brought to a halt. Generally, frictional heat is generated by converting kinetic energy into heat energy through friction. As the kinetic energy is converted into heat energy, high temperature heat is generated which affects the mechanical behavior of the braking system. Frictional heat affects the thermal expansion and friction coefficient of the brake system. If the temperature is not controlled, the brake performance will be decreased. Therefore, it is important to predict and control the heat generation of the brake. Various numerical analysis studies have been carried out to predict the frictional heat, but they assumed the existence of boundary conditions in the numerical analysis to simulate the frictional heat, because the simulation of frictional heat is difficult and time consuming. The results were based on the assumption that the frictional heat is different from the actual temperature distribution in a rotating brake system. Therefore, the reliability of the cooling effect or thermal stress using the results of these studies is insufficient. In order to overcome these limitations and establish a simulation procedure to predict the frictional heat, this study directly simulates the frictional heat generation by using a thermal-structure coupling element. In this study, we analyzed the thermo-mechanical behavior of a brake model, in order to investigate the thermal characteristics of brake systems by using the Finite Element method (FEM). This study suggests the necessity to directly simulate the frictional heating and it is hoped that it can provide the necessary information for simulations.

• Journal of the Korean Institute of Landscape Architecture
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• v.41 no.2
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• pp.59-68
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• 2013

This study facility use and satisfaction of the users of Han River Citizen's Park in Ttuksum district in order to provide foundational data necessary for planning and designing to enhance general user satisfaction when building new riverside parks or reorganizing existing riverside parks. In order to do so, the study surveyed and analyzed the user satisfaction of 374 men and women who use Ttuksum district located in Han River Citizen's Park. For this study, data were collected by self-administration method from 374 samples selected by the convenience sampling method. The results are as follows. 1) Users of Ttuksum district than male. The distribution of related accessibility, those residing within 5 kilometers the site it frequently. 2) Use it for walk, relaxation, or exercise. Are often accompanied by friends or family. Also, about the facility use by the purpose of use or characteristics of conpany, the grass square was utilized the most. 3) About user satisfaction with the park facilities in Ttuksum district, it was higher in the grass square(3.95), sport facilities(3.73), and music fountain(3.72) in order. Regarding the specialized park facilities, satisfaction was mostly low except for the music fountain. Also, about the satisfaction with the usability or view, accessibility(4.03) and night view(3.90) were. Based on the results of this study, it to proceed with positive verification processes in the follow-up research order to enhance reliability of those results.