• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.4 s.346
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• pp.13-21
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• 2006

An mobile ad hoc network(MANET) is a collection of wireless computers (nodes), communicating among themselves over multi-hop paths, without the help of any infrastructure such as base stations or access points. Prior research in MANET has generally studied the routing problem in a non-adversarial setting, assuming a trusted environment. In this paper, we design and evaluate the Secure Zone Routing Protocol(T-ZRP), a secure ad hoc network routing protocol is based on the design of the hash chain. In order to support use with nodes of limited CPU processing capability, and to guard against Denial-of-Service attacks in which an attacker attempts to cause other nodes to consume excess network bandwidth or processing time, we use efficient one-way hash functions and don't use asymmetric cryptographic operations in the protocol. Proposed algorithm can safely send to data through authentication mechanism and integrity about routing establishment.

• The Journal of the Korea Contents Association
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• v.11 no.12
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• pp.774-784
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• 2011

The purpose of this study, which was conducted as a part of investigations for vitalizing the School Sheriff system proposed as a means to prevent school violence and promote school safety, was to survey recognition of elementary school parents toward the School Sheriff system and present an improvement scheme for the system. For the study, we selected as the research object a set of parents whose children attended schools with School Sheriffs and then sampled 200 parents out of them with cluster random sampling, before analyzing 189 finally. Validity of the questionnaire is verified by expert council and factorial analysis, and reliability by reliability analysis. Statistical means including chi-square test, t-test and F-test are used. The result of the study as follows : First, necessity of the School Sheriff system varies by individual characteristics. Second, recognition toward the system itself varies by individual characteristics. Third, recognition toward the role that should be played by School Sheriffs varies by individual characteristics. Fourth, there is a difference in perceiving the role and activity of School Sheriffs, Fifth, whether the system helped improving school safety varies by individual characteristics. Sixth, the satisfaction from the School Sheriffs.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.4
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• pp.336-344
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• 2012

It is very important to salvage the vessel and seafarer rapidly and efficiently when maritime accident occurred, as maritime accident has a bad effect on vessel, seafarer and shipping industry as well as the whole community itself. Especially, marine salvage in relation to the accident involving huge marine pollution and loss of life will be regarded as a more important process because the accident would result more severe damages. However, domestic marine salvage forces are weaker than other country's, and private marine salvage company has poor technical and commercial base even though the Korea Coast Guard and Navy have relatively more modernized equipments and squad. Thus, it is very important to promote marine salvage operation capacity because it is related with the national security as well as the national economy. In this regard, this study examines the promoting method of marine salvage including its public and private section from the perspectives of law and systemic revision.

• Journal of Korean society of Dental Hygiene
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• v.9 no.3
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• pp.545-557
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• 2009

Objectives : This study was to investigate the use of mouth-guards and maxillofacial injuries and to examined the relationship among variables in athletes group. Methods : The subjects were 459(86.5%), who were 18 years or older with mean age of 20.7 years. Data was collected using a self administrated questionnaire from May 25 to June 15, 2009. We surveyed maxillofacial injuries(temporo-mandibular disorders contained) and mouth-guards usage and confidence concerning mouth-guards in athletes. The data were analysed with chi-square analysis, fisher's exact test and logistic regression using the SPSS 15.0 windows. Results : Prevalence of body or maxillofacial injuries experiences was 54.5% for athletes and 47.1% for non-athletes groups(p>0.05). The other hand, the incidence temporo-mandibular disorders was 67.0% for athletes and 49.8% for non-athletes groups(p<0.05). The experience of the use of mouth-guards was 83.3% for athletes and 78.8% for non-athletes, there were not significant differences between athletes and non-athletes groups (p>0.05). Risk factors found to be significantly related to the occurrence of maxillofacial injury were: unused mouth-guards(OR=2.83), no rules for use of mouth-guards(OR=2.46). Conclusions : Based on the findings, maxillofacial injuries experience is highly associated with mouth-guards usage, not only athletes also general people should be educated on the use of mouth-guard in order to reduce the incidence of maxillofacial injuries.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.2
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• pp.200-207
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• 2017

The purpose in having a control surface on ships is to control the motion of the ship. The control surface may be composed entirely of a single movable surface or of a combination of fixed and movable portions. A control surface has one sole function to perform in meeting its purpose, and that is to develop a control force in consequence of its orientation and movement relative to the water. The forces and moments generated as a result of this rotation and angle of attack then determine the manoeuvring characteristics of the ship. In this paper, two-dimensional flow characteristics of a flapped rudder and a water-blowing control rudder were accomplished respectively by PIV method in a circulating water channel. Model test has been carried out with different angles of attack of main foil (NACA 0012) and flap's deflection angles to predict the performance of the flapped rudder and the water-blowing control rudder. The 2-frame particle tracking method has been used to obtain the velocity distribution in the flow field. $Re{\fallingdotseq}3.0{\times}10^4$ has been used during the whole experiments and measured results have been compared with each other.

• The Journal of the Korea Contents Association
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• v.19 no.2
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• pp.121-134
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• 2019

The areas be affected maritime police authority of the Republic of Korea, are largely classified as inland waters, territorial waters, exclusive economic zone and continental shelf(hereinafter referred to as "domestic sea area") and high seas. Of these, the maritime police authority in domestic sea area follows a municipal law that accommodates the United Nations Convention on the Law of the Sea(UNCLOS). In addition, this Convention shall apply on the high seas. Meanwhile, on the high seas, foreign vessels other than domestic vessels are allowed to be subject to limited jurisdiction only for the anti-mankind criminal acts, such as piracy etc. this is in accordance with the principle of "Freedom of the high seas" and "maritime flag state," under this Convention. However, the illegal acts of foreign vessels that threaten the security of coastal states and the safety of ships on the high seas can cause many types of crimes other than anti-mankind criminal acts, and the jurisdiction of the coastal states exercised may lead to conflicts between countries. Therefore, this article would like to suggest a plan for institutional improvement to maintain international maritime order on the high seas and secure maritime police authority in coastal states.

• Journal of Navigation and Port Research
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• v.45 no.4
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• pp.204-211
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• 2021

The Maritime Domain Awareness system is a component that is necessary to enhance the awareness of all situations occurring at sea in relation to security, safety, economy, and the environment. To establish a marine situation recognition system that is currently being introduced in major maritime countries after approval by the International Maritime Organization's Maritime Safety Committee in 2010, operational measures should be established. For the purpose of establishing a technological foundation for the efficient construction of a Korean maritime situation recognition system, this study analyzed the status of each system (RADAR, VHF, and V-PASS, etc.) and proposed the application of data and communication standards.

• New & Renewable Energy
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• v.18 no.2
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• pp.73-81
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• 2022

This study was aimed at designing a condenser, as a component of the organic Rankine cycle system for ships. The condenser was manufactured through press molding to achieve a bent shape to enhance the heat transfer performance, considering the shape of the heat transfer plate used in a brazing plate heat exchanger. The heat transfer plate was made of copper-nickel alloy. The required heat transfer rate for the condenser was 110 kW, and the maximum number of layers was set as 25, considering the characteristics of high-temperature brazing. Computational fluid dynamics techniques were used to perform the thermal fluid analysis, based on the ANSYS CFX (v.18.1) commercial program. The heat transfer rate of the condenser was 4.96 kW for one layer (width and length of 0.224 and 0.7 m, respectively) of the heat transfer exchanger. The fin efficiency pertaining to the heat transfer plate was approximately 20%. The heat flow analysis for one layer of the heat exchanger plate indicated that the condenser with 25 layers of heat transfer plates could achieve a heat transfer rate of 110 kW.

• Convergence Security Journal
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• v.14 no.6_1
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• pp.89-98
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• 2014

Simultaneously with the founding of the Joseon military system was reformed. On the basis of Koryo's '2gun 6wie(二軍 六衛)' reorganized into '10wie 50ryong(10衛 50領)'. But the de facto central military power was in Euhungqingunwie(義興親軍衛) that is Lee Seong-gye's Elite Guard. In addition to these make up the backbone of the central forces that were Siwiepae(侍衛牌). Also a anti-legislation Seongzhongaima(成衆愛馬) was also presented. But soon the military command and military systems will start to repair. First, reform of military command system of the unified command system shall be established for the Euhungqingunwie(義興親軍衛). And Jeongdojeon has strengthened the military education and training. But, for the establishment of Military command system the most important was the reform of the private soldier. Military systems also have been systematized. shipwie(十衛) was changed to the shipsa(十司) in Taejo. After, they are expanded to shipyisa(十二司) in Sejong. And, the Gabsa(甲士) were returned. In addition, various special branch of the army, Byelsiwie(別侍衛), Naegumewie(內禁衛), gyumsabok(兼司僕) etc, are increased and founded.

• Korean Security Journal
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• no.41
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• pp.123-151
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• 2014

The purpose of this study was focused on the relationship between private guards' job embeddedness and dual commitment. In this study, job embeddedness is selected as an independent variable and dual commitment is selected as a dependent variable one. job embeddedness was divided into three sub-factors such as "fit", "links", and "sacrifice", and dual commitment is again composed with organizational commitment, and career commitment. Moreover sex, age, academic background, service period, and income were selected as a control variable. To test the hypotheses, survey data from private guards in Kyungpook are collected and analyzed. Principal component method is used to see which items cluster together in each factor and to calculate factor scores. Multiple regression analysis identifies several factors which have significant effects on dual commitment. Key finding can be summarized as follow. Fist, the factor of "fit" have significant effects on organizational commitment, and career commitment. Second, the factor of "links" have significant effects on organizational commitment, and career commitment. Third the factor of "sacrifice" have significant effects on organizational commitment, and career commitment. Finally, when all the variables with significant effects are included in the final model, "links" disappear, while "fit" and "sacrifice" remain statistically significant. Based on these finding, this study suggests some policy issues to promote private guards' dual commitment.