• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.4
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• pp.903-910
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• 2016

As smart mobile devices having touchscreens are growingly deployed, a pattern lock system, which is one of the graphical password systems, has become a major authentication mechanism. However, a user's unlocking behaviour leaves smudges on a touchscreen and they are vulnerable to the so-called smudge attacks. Smudges can help an adversary guess a secret pattern correctly. Several advanced pattern lock systems, such as TinyLock, have been developed to resist the smudge attacks. In this paper, we study an automated smudge attack that employs machine learning techniques and its effectiveness in comparison to the human-only smudge attacks. We also compare Android pattern lock and TinyLock schemes in terms of security. Our study shows that the automated smudge attacks are significantly advanced to the human-only attacks with regard to a success ratio, and though the TinyLock system is more secure than the Android pattern lock system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.6
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• pp.2595-2618
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• 2018

In this paper, we investigate secure communication with the presence of multiple eavesdroppers (Eves) in a two-tier downlink dense heterogeneous network, wherein there is a macrocell base station (MBS) and multiple femtocell base stations (FBSs). Each base station (BS) has multiple users. And Eves attempt to wiretap a macrocell user (MU). To keep Eves ignorant of the confidential message, we propose a physical-layer security scheme based on cross-layer cooperation to exploit interference in the considered network. Under the constraints on the quality of service (QoS) of other legitimate users and transmit power, the secrecy rate of system can be maximized through jointly optimizing the beamforming vectors of MBS and cooperative FBSs. We explore the problem of maximizing secrecy rate in both non-colluding and colluding Eves scenarios, respectively. Firstly, in non-colluding Eves scenario, we approximate the original non-convex problem into a few semi-definite programs (SDPs) by employing the semi-definite relaxation (SDR) technique and conservative convex approximation under perfect channel state information (CSI) case. Furthermore, we extend the frame to imperfect CSI case and use the Lagrangian dual theory to cope with uncertain constraints on CSI. Secondly, in colluding Eves scenario, we transform the original problem into a two-tier optimization problem equivalently. Among them, the outer layer problem is a single variable optimization problem and can be solved by one-dimensional linear search. While the inner-layer optimization problem is transformed into a convex SDP problem with SDR technique and Charnes-Cooper transformation. In the perfect CSI case of both non-colluding and colluding Eves scenarios, we prove that the relaxation of SDR is tight and analyze the complexity of proposed algorithms. Finally, simulation results validate the effectiveness and robustness of proposed scheme.

• Physical Therapy Korea
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• v.10 no.3
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• pp.127-140
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• 2003

The purpose of this study was to determine the factors affecting on the home treatment stress in the CP (cerebral palsy) children's mothers. Direct interviews were conducted from March 17 with April 4, 2003 with 97 mothers of CP children. The average level of stress from home treatment felt by mothers with CP children was $16.97{\pm}4.04$. Stress-levels were especially high in mothers who were not satisfied with the treatment outcome (p<.05) and whose acceptance of disability was low (p<.01). Stress felt by mothers was low when their health status was high (p<.05). A physical burden was shown to have a significant correlation with the stress of the mothers during the home treatment (p<.01). Mothers with a child of Level 2 disability had lower levels of stress than those with a child of Level 4 or 5 disability (p<.01). The level of stress was higher in mothers who lagged in acquiring technical sufficiency (p<.05). Multiple regression analysis showed that one factor affecting the stress felt by mothers with CP children was the degree of acceptance of the disability (p<.01). Programs that can reduce the stress levels of mothers with CP children through home treatment and secure social systems such as professional help and economic compensation, need to be developed. Active policies should be established and executed for these mothers since stress felt by mothers significantly affects the consistency and effectiveness of treatment provided at home.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.345-349
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• 2002

A great need for comprehensive solutions for the promotion of construction technology, and it can be true through active societies. Corresponding to these needs, it is need to prepare globalization by gathering and concentrating societies quote ability, through these efforts, it is possible to ensure research effectiveness and to secure competitive position in consisting regional network like Asian Pacific Economic Cooperation, APEC. This research analyzes and suggests are enrolled in The Korean Federation of Science and Technology Societies (KOFST) to find reasonable solutions for international engineer's mutual certification and growth of domestic construction related societies. This study also analyzes department structure and relationship of Civil engineering and construction related societies. This paper suggests reasonable development strategy, governmental policy and roles of construction related societies by analyzing multi dimensional problem set.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.2
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• pp.182-190
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• 2011

This paper proposes a LVRT (Low Voltage Ride Through) control strategy which should be satisfied by grid-connected wind power system when grid faults occur. The LVRT regulation indicates rules or actions which have to be executed according to the voltage dip ratio and the fault duration. Especially the wind power system has to support the grid with specified reactive current to secure the grid stability when voltage reduction ratio is over 10%. The LVRT regulation in this paper is based on the German Grid Code and full-scale variable speed wind power conversion system is considered for LVRT control strategy. The proposed LVRT control strategy satisfies not only LVRT regulation but also makes power balance between wind turbine and power system through additional DC link voltage regulation algorithms. Because it is impossible to control grid side power when the 3-phase to ground fault occurs, the DC link voltage is controlled by a generator side inverter using the DC link voltage control strategy. Through the simulation and experiment result, the proposed LVRT control strategy is evaluated and its effectiveness is verified.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.9
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• pp.405-412
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• 2013

Current web has evolved to a mashed-up format according to the change of the implementation and usage patterns. Web services and user experiences have improved, however, security threats are also increased as the web contents that are not yet verified combine together. To mitigate the threats incurred as an adverse effect of the web development, we need to check security on the combined web contents. In this paper, we propose a scheduling method to detect malicious web pages not only inside but also outside through extended links for secure operation of a web site. The scheduling method considers several aspects of each page including connection popularity, suspiciousness, and check elapse time to make a decision on the order for security check on numerous web pages connected with links. We verified the effectiveness of the security check complying with the scheduling method that uses the priority given to each page.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.2
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• pp.121-132
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• 2018

Along with climate change, it is reported that the extreme climate events such as severe drought could cause difficulties of agricultural water supply. To minimize such damages, it is necessary to secure the agricultural water resources by using or saving the amount of irrigation water efficiently. The objectives of this study were to develop paddy water management scenarios and to evaluate their effectiveness on water saving. Three water management scenarios (a) deep irrigation with ponding depth of 20~80 mm (control, CT), (b) no/intermittent irrigation until paddy cracks (water management A, WM-A), and (c) intermittent irrigation with ponding depth under 20 mm (water management B, WM-B) were developed. Water saving effects were analyzed using monitored data from experimental paddy fields, and agricultural water supply was analyzed on a reservoir-scale using MASA model. The observed irrigation amounts were reduced by 21 % and 17 % for WM-A and WM-B compared to CT, respectively, and mainly occurred by the increase of effective rainfall. The simulation results showed that water management scenarios could reduce irrigation by 21~51 % and total inflow by 10~24 % compared to CT. The long-term simulated water level change of agricultural reservoir resulted in the decrease of dead level occurrence for WM-A and WM-B. The study results showed that WT-A and WT-B have more benefit than CT in the aspect of agricultural reservoir water supply.

• The Journal of the Korea Contents Association
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• v.18 no.8
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• pp.483-493
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• 2018

Through the improvement of the Labor Relations Act, the Social Insurance Act, and the Artists Welfare Act for occupational status and rights of artists, the character of workers, joining exception in the Employment Insurance Act, and applying exception in the National Health Insurance Act and the National Pensions Act should be recognized. For this, the scope of workers should be expanded through the interpretation of the court and legislation of the Labor Relations Act, and supporting range of social insurance should be expanded by applying exception in the National Health Insurance Act and joining exception in the Employment Insurance Act for artists who are currently excluded. Artists' compensation insurance that is an optional entry system and paid entirely by artists need to have effectiveness of the system through insurance support. The Artists Welfare Act also needs to be revised to strengthen legal protection for artists and it is important to secure finances for artists' welfare projects. The standard contract should be mandatory and a career certification system for artists should be established so that artists who need welfare benefits can not be omitted.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.6
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• pp.602-611
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• 2004

Servo system has commonly adapted PI controller with fixed gains, because of its simplicity and determinative relationship among the parameters. The fixed gains PI system may be applied well to some operation conditions, but not non-linearities, complex and time variant operation conditions. For solving these problems, another conventional method, 'variable gun schedule according to speed', is published. The value of gain is determined according to the absolute value of the mover real speed. In this paper, FSTPIC(Fuzzy Self-Tuning PI Controller) is proposed based on various experiences to rapidly reduce speed error and to secure a good speed response characteristics. The effectiveness of proposed algorithms is demonstrated by comparing to two conventional gain systems via 4-quadrant operation.

• Journal of Convergence for Information Technology
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• v.8 no.1
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• pp.43-51
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• 2018

The purpose of this study was to develop a mentoring program to support the professional growth of new nurses and to check the effectiveness. This mentoring program was developed by research teams and mentoring professionals based on Benner's theory. The data was analyzed using SPSS 18.0 program. The average of satisfaction of mentoring program in the mentees is 4.31 higher than mentor as 3.77. The highest scored item was 'need of mentoring program', the lowest one was 'mentoring program period and number of meetings'. Finally based on the results of the research, the duration of the mentoring program was changed to the six months. A steady support of the organizational policy about mentoring program is required to secure an outstanding nursing workforce.