• Journal of Practical Engineering Education
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• v.15 no.3
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• pp.641-647
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• 2023

In the fintech environment, ensuring secure financial transactions with smartphones requires authenticating the device owner. Smartphone authentication techniques encompass a variety of approaches, such as passwords, biometrics, SMS authentication, and more. Among these, password-based authentication is commonly used and highly convenient for user authentication. Although it is a simple authentication mechanism, it is susceptible to eavesdropping and keylogging attacks, alongside other threats. Security keypads have been proposed to address vulnerabilities in password input on smartphones. One such innovation is a group keypad, resistant to attacks that guess characters based on touch location. However, improvements are needed for user convenience. In this study, we aim to propose a method that enhances convenience while being resistant to eavesdropping and recording attacks on the existing group keypad. The proposed method uses new signs to allow users to verify instead of the last character confirmation easily and employs dragging-to-touch for blocking recording attacks. We suggest diverse positioning methods tailored for domestic users, improving efficiency and security in password input compared to existing methods.

• The Journal of the Acoustical Society of Korea
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• v.29 no.7
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• pp.411-421
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• 2010

A time-reversal mirror (TRM) is useful in diverse areas, such as reverberation ing, target echo enhancement and underwater communication. In underwater communication, the bit error rate has been improved significantly due to the increased signal-to-noise ratio by spatio-temporal focusing. This paper deals with two issues. First, the optimal number of array elements for a given environment was investigated based on the exploitation of spatial diversity. Second, an algorithm was developed to determine the optimal location of the given number of array elements. The formulation is based on a genetic algorithm maximizing the contrast between the foci and area of interest as an objective function. In addition, the developed algorithm was applied to the matched field processing with ocean experimental data for verification. The sea-going data and simulation showed almost 3 dB improvement in the output power at the foci when the array elements were optimally distributed.

• Journal of Distribution Science
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• v.3 no.2
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• pp.29-55
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• 2005

Since discount stores should be operated mostly by the non-human resources regarding the natural characteristics of the business, it is possibly said that their physical environments have been extremely significant. This study attempts to develop the measurement items and construct factors which are especially relevant to the physical environments of the discount stores and examine how the customer satisfaction and intention influence on these construct factors. These provide a useful framework for understanding the problems of measuring and evaluating the physical environments of discount stores. The final factor analysis for each construct factors resulted as four factors, and two categories(amenity and convenience) represented the characteristics of same construct such as the visibility. Then convenience is eliminated, and an attempt was made to add the new variable what is called the visibility. As a result, final construct factors that would be used in this study are made of four items; amenity, accessibility, POP and visibility. This study utilizes the LISREL 8.12 to evaluate the validity of factor structures and measurement model involving the physical environment in discount store. Finally, for the success of the projects, I think that it is necessary to provide comprehensive efforts continuously.

• Journal of the Korean Society for Railway
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• v.17 no.4
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• pp.245-250
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• 2014

This paper, as a study for the serviceability design of railway bridges with concrete track, presents the effects of design parameters of tracks and bridges on the forces acting on the rail supports of the track. To calculate the forces acting on the track, an unequal spacing discrete supported model with different spacing of rail supports was induced. Design parameters are the rail support spacing of expansion joints above abutments or piers of bridges, the distance from the support of a girder to the last rail support on the end of the girder, and the number of additional rail supports. The causes of the displacement of track are axial force, unit vertical displacement, and unit rotation. From the analysis, the maximum compressive force and the maximum uplifting force acting on the rail supports were determined and the effects of the rail support spacing on the forces acting on the track were presented.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.338-343
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• 2004

In Block Matching Algorithm (BMA), a search pattern has a very important affect on the search time and the output quality. In this paper, we propose the HDS( Half Diamond Search) pattern based on the cross center-biased distribution property of a motion vector. At lust, the 4 points in the above, below, left, and right around the search center is calculated to decide the point of the MBD (Minimum Block Distortion). And an above point of the MBD is checked to calculate the SAD. If the SAD is less than the previous MBD, this process is repeated. Otherwise, the left and right points of MBD are calculated to decide the points that have the MBD between two points. These processes are repeated to the predicted direction for motion estimation. Experiments show that the speedup improvement of the proposed algorithm can be up to 23% while maintaining similar image quality.

• Journal of the Korean Chemical Society
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• v.47 no.3
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• pp.273-282
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• 2003

A questionnaire on "atomic models and electron configuration" was performed on 34 of 11th grade and 38 of 12th grade students who took the Chemistry-II course in order to examine the degree of learning achievement. Also eight Chemistry-II textbooks published in the 6th curriculum were analyzed for the similarities and differences in dealing with this topic and possible improvements were discussed in conjunction with the questionnaire. The results of this questionnaire showed that the degree of learning achievement on the topics between two different classes were not much different in general, although a little difference was found. This indicates that the topics have been taught in early 11th grade but subsequent supplemental teaching has not been performed. To study on the topics of "atomic models and electron configuration" effectively and systematically, knowledge on the basic spectroscopy and quantum mechanics should be preceeded. However this could be practically difficult under the current high school curriculum. Therefore It would be necessary to describe the basic concepts for the quantum mechanics and spectroscopy schematically in the "Reference Materials" section of the textbook, even if it is not very long. On the other hand, the Chemistry-II textbooks analyzed in this work reveal, in general, to have the similar organization and explanation modes. However it has been analyzed that a connection between the Bohr and electron-cloud atomic models might be insufficient or position of electrons might be possible to be misunderstood by students in some textbooks.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.1
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• pp.15-25
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• 2010

The objective of this study is to investigate the optimal arrangement of cameras used for the robot's vision control scheme. The used robot's vision control scheme involves two estimation models, which are the parameter estimation and robot's joint angle estimation models. In order to perform this study, robot's working region is divided into three work spaces such as left, central and right spaces. Also, cameras are positioned on circular arcs with radius of 1.5m, 2.0m and 2.5m. Seven cameras are placed on each circular arc. For the experiment, nine cases of camera arrangement are selected in each robot's work space, and each case uses three cameras. Six parameters are estimated for each camera using the developed parameter estimation model in order to show the suitability of the vision system model in nine cases of each robot's work space. Finally, the robot's joint angles are estimated using the joint angle estimation model according to the arrangement of cameras for robot's point-position control. Thus, the effect of camera arrangement used for the robot's vision control scheme is shown for robot's point-position control experimentally.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.684-691
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• 2016

This study defines three types of public parking for commercial business, cultural tours, sales and market areas. We compared the Santa Barbara parking system with Korean examples for use in urban revitalization with a proper planning strategy based on district-specific public parking. The results are as follows: 1. The layout and location of public parking entrances need to consider the urban grid and linkages. 2. Public parking should place emphasis on respecting a district's character and user convenience. 3. The success of public parking extends to revitalization of pedestrian paths at target areas.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.11
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• pp.861-869
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• 2013

We consider an information system where viruses arrive according to a Poisson process with rate ${\lambda}$. The information system has two types of anti-virus operation policies including 'real-time scan' and 'batch scan.' In the real-time scan policy, a virus is assumed to be scanned immediately after its arrival. Consequently, the real-time scan policy assumes infinite number of anti-viruses. We assume that the time for scanning and curing a virus follows a general distribution. In the batch scan policy, a system manager operates an anti-virus every deterministic time interval and scan and cure all the viruses remaining in the system simultaneously. In this paper we suggest a probability model for the operation of anti-virus software. We derive a condition under which the operating policy is achieved. Some numerical examples with various cost structure are given to illustrate the results.

• Journal of Korea Multimedia Society
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• v.12 no.7
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• pp.971-978
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• 2009

The paper is a phase controlled loop antenna for multi-media devices. We developed a phase control loop pattern arrangement methods for loop antenna in mobile devices like as a cell phone and PCS, WCDMA. In the loop antenna pattern, arrange close adhesive the loop antenna pattern $180^\circ$ cycle in wave length, the radiated electro-magnetic wave from close adhesive loop pattern become to coherent wave than the phase controlled loop antenna has high efficiency and high radiation gain. To acquire a wide band width on phase controlled loop antenna, we arrange a multiple phase controlled loop pattern that has a different length each other. Different length for each other loop pattern cause a different frequency that we can acquire a wide band width for loop antenna from close adhesive phase control. In experiment, we designed a CDMA850 mobile multi-media antenna in 20mm$\times$20mm area thickness 0.4mm, the radiation efficiency is over 60% and radiation gain is over 0dBi.