• Journal of Power System Engineering
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• v.17 no.4
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• pp.139-146
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• 2013

Because the magnetic bearing supports levitating body without contact, wear, noise and vibration, it is very useful to high revolution machinery. In this paper we selected ATmega 128, a less expensive and widely used micro controller, for control the magnetic bearing system. And we selected the sampling time and the control gain of PID controller through trial-and-error. The control program of the one board controller utilized lookup table to reduce calculation time, and bit shifting for the integer calculation in instead of floating point calculation. As the results, the controller carried out relatively high speed PID control on sampling time 0.25 ms. At last the rotation test for the magnetic bearing system was carried out by 3 phase induction motor and air turbine.

• The Journal of the Convergence on Culture Technology
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• v.7 no.3
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• pp.59-69
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• 2021

The Moon Jae-in administration insisted on reforming the prosecution for the reform of power institutions, and also tried to control the power of the prosecution through the establishment of a high-ranking public officials criminal investigation office. Then, what is the direction of the legal prosecution reform? Above all, it is a logic to drastically reduce the power of the prosecution. How to shrink it? First, it is necessary to control or check the power of prosecution and investigation that the prosecution has. Second, the key to the reform of the prosecution is perhaps to separate personnel rights from power. In order to exclude external pressure from the prosecution's personnel rights, there must be no instruction or intervention from the attorney general. To do this, the prosecutor general must go through various personnel evaluations, such as multi-faceted evaluation. Third, the essence of the High-ranking Officials Criminal Investigations Act is to deal with crimes of prosecutors, judges, police, and members of the National Assembly. It is also the core of the institutional mechanism to cover the corruption of one's family members while holding all the right to investigate, prosecution, and warrant claims, and to check the omnipresent prosecutors who have abused their right to investigate for political purposes. Then, what is necessary for the success of the high-ranking officials criminal investigation office? Above all, We think political neutrality is very necessary. The Ministry of Airborne has a very high authority of the Director. This paper intends to examine the functions and roles of the prosecution and high-ranking officials criminal investigation offices to prevent corruption. We analyzed the contents of the prosecution and the public officials criminal investigation office, and examined the limitations and problems, and the measures to control corruption in public offices.

• Journal of Power System Engineering
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• v.19 no.5
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• pp.52-59
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• 2015

This paper is presented for the free vibration of a conical shell with annular plates or circular plate using the transfer of influence coefficient. The governing equations of vibration of a conical shell, including annular plate, are written as a coupled set of first order differential equations by using the transfer matrix of the shell. Once the transfer matrix of a single component has been determined, the entire structure matrix is obtained by the product of each component matrix and the joining matrix. The natural frequencies and the modes of vibration were calculated numerically for joined conical-annular plates. The validity of the present method is demonstrated through simple numerical examples, and through comparison with the results of finite element method, transfer matrix method and ANSYS. The conclusion show that the present method can accurately obtain natural vibration characteristics of the conical shell with annular or circle end plates.

• Journal of Power System Engineering
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• v.17 no.1
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• pp.50-57
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• 2013

This describes the formulation for the free vibration of joined conical-cylindrical shells with uniform thickness using the transfer of influence coefficient. This method was developed based on successive transmission of dynamic influence coefficients, which were defined as the relationships between the displacement and the force vectors at arbitrary nodal circles of the system. The two edges of the shell having arbitrary boundary conditions are supported by several elastic springs with meridional/axial, circumferential, radial and rotational stiffness, respectively. The governing equations of vibration of a conical shell, including a cylindrical shell, are written as a coupled set of first order differential equations by using the transfer matrix of the shell. Once the transfer matrix of a single component has been determined, the entire structure matrix is obtained by the product of each component matrix and the joining matrix. The natural frequencies and the modes of vibration were calculated numerically for joined conical-cylindrical shells. The validity of the present method is demonstrated through simple numerical examples, and through comparison with the results of previous researchers.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.1
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• pp.83-88
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• 2014

A new shell divider was manufactured according to the principle of the lever in order to improve working efficiency in collecting the gonad of Sea Urchin, Anthocidaris crassispina, around the coast of jeju. It was composed of three parts of a pair of handles for grasping power, a fulcrum and a pair of knives for action with 21cm in length and 13cm in width. The operating efficiency of the shell divider was tested out in three place of Jeju coast. Statistical significances of differences of working time between test groups were calculated according to the t-test with the level of significance. In dividing the shell of sea urchin, the average of about 3 seconds of working time by the shell divider was less than that by a knife. At the result of t-test, the statistical significance in the working time existed between the divider group and the knife group. On the other hand, the working time among the divider operators showed no significant differences. It is concluded that the shell divider is more efficient than a knife in traditional operating.

• Journal of Advanced Navigation Technology
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• v.21 no.5
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• pp.491-500
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• 2017

This paper investigates a low cost dual modular redundancy system based on heartbeat which can be applied to traffic control signal system. Failure of the traffic control signal system can cause traffic confusion and traffic accidents. Therefore safety and reliability of traffic control should be secured using fault tolerance technology. To do this, we configured a redundant board using the open source hardware and the heartbeat technique of Linux HA. The function of the traffic signal control system was verified and the fault recovery time was measured using fault injection test. As a result of the test, the fault recovery time was confirmed to be less than 9 seconds on average, confirming that the reliability target time is satisfied. Based on the results of this study, it is expected that it can be applied to fields requiring high reliability systems such as aviation, space, and nuclear power embedded systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.10
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• pp.2263-2268
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• 2015

This paper describes packet scheduling techniques that can be used to alleviate the impact of interference. The mechanism is consisted of interference estimation and master delay police. Proposed scheduling police is effective in reducing packet loss and delay. Another advantage worth mentioning, are the additional saving s in the transmitter power since packet are not transmitted when channel is bad. This paper gives that scheduling policy works only with data traffic since voice packets need to be sent at fixed intervals. However, if the delay variance is constant and the delay can be limited to a slot, it may be worthwhile to use DM packet for voice.

• Convergence Security Journal
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• v.17 no.1
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• pp.81-88
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• 2017

The purpose of this study is to analyze any hinderance factors for successful attending system of Korean National Assembly and to provide improvement plans of legal systems to ensure security of National Assembly. First, the conceptualization and functions of Korean National Assembly attending system were discussed and related regulations and laws were also examined. Second, hinderance factors, such as sharp increase in 1) illegal behaviors, 2) bring in prohibited items, and 3) possibility of National Assembly terror, for successful attending systems were analysed. Third, improvements of legal system for security enhancement of National Assembly Attending System were discussed: 1) new legislation for providing National Assembly's security officers with special judicial police power is needed to deal with criminal behaviors and to protect human rights, and 2) legal reforms are required to provide right to command to National Assembly's Security Planning Office rather than National Assembly security office under Seoul Metropolitan Police Agency in order to unify commanding system.

• Convergence Security Journal
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• v.11 no.5
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• pp.41-51
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• 2011

The objective of this study is to generally check the present situation of private security industry by analyzing the current situation of private security industry in Korea so as to find which policy base is reflected to amend law by analyzing the amendment process of private security law in order to suggest policy direction of private security industry in Korea. Viewing through amendment process of private security law, enhancing publicity and enterprise are not judged to form any definite policy base. They are merely interpreted to partially reflect enterprise under the strong base of publicity. Such policy base may cause overall stagnation of private security industry. For sound development of private security industry, it is required to get out of the existing policy direction so as to change policy base to the direction of enhancing enterprise of private security industry. The power of police for instruction and supervision should be largely transferred to Korea Security Association so as to cultivate autonomous purifying function of private security industry. Police should strive to develop policy in the level of joint production of security service.

• Journal of the Society of Disaster Information
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• v.19 no.2
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• pp.254-261
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• 2023

Purpose: With the diversification of modern society, it is difficult to predict crime types, and the limitations of the state's functions, such as human limitations and lack of budget, are increasing. Method: However, as the number of private investigation companies that do not use illegal means to solve the request increased, attempts were made to introduce a public detective system that would manage and supervise it and compensate for the gap in public power. Result: However, due to the nature of the Private Investigator system, legislation has not progressed as the National Police Agency and the Ministry of Justice are at odds with existing laws that guarantee existing jobs such as lawyers and credit research. Conclusion: Therefore, this study analyzes the bills related to the authorized detective to the National Assembly, examines major issues such as the scope of work of the authorized detective business, the selection of management and supervisory authorities, and suggests ways to improve the successful settlement of the Private Investigator system.