• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.8
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• pp.1551-1559
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• 2015

Recently, the performance of smart devices is almost similar to that of the existing PCs, thus the users of smart devices can perform similar works such as messengers, SNSs(Social Network Services), smart banking, etc. originally performed in PC environment using smart devices. Although the development of smart devices has led to positive impacts, it has caused negative changes such as an increase in security threat aimed at mobile environment. Specifically, the threats of mobile devices, such as leaking private information, generating unfair billing and performing DDoS(Distributed Denial of Service) attacks has continuously increased. Over 80% of the mobile devices use android platform, thus, the number of damage caused by mobile malware in android platform is also increasing. In this paper, we propose android based malware detection mechanism using time-series analysis, which is one of statistical-based detection methods.We use auto-regressive moving-average model which is extracting accurate predictive values based on existing data among time-series model. We also use fast and exact malware detection method by extracting possible malware data through Z-Score. We validate the proposed methods through the experiment results.

• Physical Therapy Korea
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• v.11 no.2
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• pp.35-45
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• 2004

The purpose of this study was to investigate the correlation and characteristics between electromyographic (EMG) activities of lower leg muscles and the posturographic assessment of static balance control in normal adults. Twenty-four young, healthy adults(12 males, 12 females) participated in the study. Center of pressure (COP) parameters were obtained using force platform as total path distance, total sway area, X mean frequency and Y mean frequency for 20 seconds in the following conditions: (1) comfortable standing with eyes opened or closed, (2) uncomfortable standing (feet together) with eyes opened or closed, (3) virtual moving surround delivered using Head mount display (HMD) with four different moving patterns. The virtual moving patterns consisted of close-far, superior-inferior tilting (pitch), right-left tilting (roll), and horizontal rotation (yaw) movements. Surface electromyographic activites were recorded on the tibialis anterior, peroneus longus, medial and lateral heads of gastrocnemius muscles under each condition. Correlation between the posturographic measures and EMG activities were evaluated. Total path distance and total sway area of COP were significantly increased during uncomfortable standing. EMG activity of tibialis anterior was significantly more during uncomfortable standing and virtual moving surround stimulation than during comfortable standing. Total path distance and sway area of COP during comfortable standing with closed eyes showed significant positive correlation with the EMG activities of the lateral head of gastrocnemius muscle. Total path distances and total sway area of COP during muscle. Total path distances and total sway area of COP during presentation of virtual moving surround also had significant positive correlations with EMG activities of the lateral head of gastrocnemius muscle under close-far movement.

• Journal of the Korea Society of Computer and Information
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• v.24 no.12
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• pp.67-74
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• 2019

In this paper, we design and implement an analytics platform based on bulk cargo DTG data for crackdown on overloaded trucks. DTG(digital tachograph) is a device that stores the driving record in real time; that is, it is a device that records the vehicle driving related data such as GPS, speed, RPM, braking, and moving distance of the vehicle in one second unit. The fast processing of DTG data is essential for finding vehicle driving patterns and analytics. In particular, a big data analytics platform is required for preprocessing and converting large amounts of DTG data. In this paper, we implement a big data analytics framework based on cargo DTG data using Spark, which is an open source-based big data framework for crackdown on overloaded trucks. As the result of implementation, our proposed platform converts real large cargo DTG data sets into GIS data, and these are visualized by a map. It also recommends crackdown points.

• Journal of Korea Multimedia Society
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• v.9 no.10
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• pp.1322-1331
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• 2006

Concurrency control is one of the important factors to maintain consistent conditions of a game because most participants of the game should be shared information to play the game through a distributed network system. replay delay times should establish in every event and the received event should be saved and performed simultaneously for Concurrency Control. However, it is not easy to practice the event with same speed in environment having various moving speed. Therefore, expansion have to be provided. In other words, one of the most important factors of a game's efficiency is the process of bandwidth and delay. the process of concurrency control method based on scalable prediction for Multi-platform games would minimize the loss rate of a event and then would improve the interaction capacity of a game. It also might get reliability between clients. This paper analyzes some problems in terms of a layout of a game that integrates a cable and a wireless system. In addition, this paper provides methods to expand bandwidth and delay that might be an obstacle of a On-line game and to ensure reliability between a server and a client.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.5
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• pp.49-63
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• 2019

Crowdedness management at subway platforms is essential to improve services, including the prevention of train delays and ensuring passenger safety. Establishing effective crowdedness mitigation measures for platforms requires accurate estimation of the congestion level. There are temporal and spatial constraints since crowdedness on subway platforms is assessed at certain locations every 1-2 years by hand counting. However, smart cards generate real-time big data 24 hours a day and could be used in estimating congestion. This study proposes a model based on data from transit cards to estimate crowdedness dynamically. Crowdedness was defined as demand, which can be translated into passengers dynamically moving along a subway network. The trajectory of an individual passenger can be identified through this model. Passenger flow that concentrates or disperses at a platform is also calculated every minute. Lastly, the platform congestion level is estimated based on effective waiting areas for each platform structure.

• The Journal of the Acoustical Society of Korea
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• v.13 no.2
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• pp.30-37
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• 1994

Since the morden targets are of high speed and getting quiet in both active and passive mode, the necessities of developing advanced SONAR system capable of performing target motion analysis (TMA) and target classification are evident. In order to develop such a system, the scattering mechanism of complex bodies needs to be, some extent, fully understood and modeled. In this paper, MOving Spread Target(MOST) signal simulation model is presented and discussed. The model is based on the highlight distribution method, and simulates pulse elongation of spread target, doppler effect due to kinematics of the target as well as SONAR platform, and distribution target strength of each highlight point (HL) with directivity. The model can be used in developing and evaluating advanced SONAR system through system simulation, and can also be used in the development of target state estimation algorithm.

• Journal of the Korean association of regional geographers
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• v.13 no.1
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• pp.32-42
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• 2007

In Sagye coast of Andeok-myeon, southwestern Jeju, shore platform of noncohesive Hamori Formation, marine terrace deposit of round gravels, coastal dune composed of shell sand and volcanic sand, and back lake are linked closely with each other. In this paper, the formation process of Sagye coastal geomorphic system analysed by using OSL dating method is as follows: Firstly, Hamori Formation is a horizontal stratum filed up of tuff reworked by submarine volcanic eruption during 3$\sim$7.6 ka BP. Hollow at the boundary between Hamori Formation' flat and Kwangheak Basalt's gentle slope become a back lake when block is appeared over the sea level by uplift. Secondly, while Hamori Formation was laid below sea level, gravels which had been broken and abraded at southwestern rocky coast composed of Kwangheak basalt or been transported through the small stream from adjacent hillslope were deposited in rapid flow environment. Thirdly, deposition of round gravels was ceased by earth uplift, and shore platform was constructed by abrasion process of energy of swash moving forward. As altitude of shore platform is equal to high tidal level of spring tide, compared it with present high tidal level of study area, earth is uplifted about 105m since shore platform was formed. Fourthly, much sandy sediments transported from offshore bottom covered shore platforms and marine terrace deposits. Lighter sediments among sandy sediments was blown to back, formed secondary sand dune since about 500 year.

• Physical Therapy Korea
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• v.3 no.3
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• pp.1-11
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• 1996

The purpose of this study were to evaluate and compare the balance ability at different conditions in normal 20 to 29 years old on unstable platform, KAT 2000(Breg, Inc., Vista, CA. 1994). Static and dynamic BI(balance index) were measured 3psi and 5psi surface conditions. Static tests were done on right and left leg separately, then both legs together with the feet apart 20cm with the eyes opened and closed. Dynamic tests were done on both legs together with apart 20cm with the eyes opened. A dynamic test was performed in which the subject moved platform in a circular manner to chase a moving object on a computer screen. Seventy healthy students(average 21.6 years, male, female) were tested. In this study applied the paired t-test and correlation to determine the statistical significance of result. The results were as follow: 1) The mean static balance index of the Rt leg was $119.9{\pm}75.72$ on 3psi surface condition with the eyes opened, and that of the Lt leg was $224.3{\pm}121.16$. 2) The mean static balance index of the Rt leg was $93.1{\pm}24.16$ on 5psi surface condition with the eyes opened, and that of the Lt leg was $180.5{\pm}61.76$. 3) The mean static and dynamic balance index of both legs were $76.4{\pm}31.86$, $2187.6{\pm}696.99$ on 3psi with the eyes opened, and $68.3{\pm}14.82$, $1938.7{\pm}525.41$ on 5psi respectively. 4) The mean static balance index of the Rt leg was $517.8{\pm}220.87$ on 3psi surface condition with the eyes closed, and that of the Lt leg was $588.6{\pm}204.81$. 5) The mean static balance index of the Rt leg was $271.9{\pm}192.151$ on 5psi surface condition with the eyes closed, and that of the Lt leg was $363.4{\pm}98.97$. 6) The mean static balance index of both legs was $332.6{\pm}137.31$ on 3psi surface condition with the eyes closed, and that of the 5psi was $288.5{\pm}133.07$. 7) The balance index on 3psi surface condition was significantly higher than that of 5psi (p<0.05, p<0.01). 8) The balance index with the eyes closed was significantly higher than that of the eyes opened (p<0.05). 9) The balance index on the left leg was significantly higher than that of the right leg (p<0.05, p<0.01). 10) There was no correlation between static balance index and dynamic balance index. 11) Therewas no correlation between weight or height and balance index.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.7
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• pp.680-687
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• 2012

One of the frequent problems in the stabilized gimbal system is the rejection of disturbances associated with moving components. Very often such disturbances have non-linear characteristics. In a typical gimbal system, each gimbal and platform are connected by a mutual bearing which induces inevitable friction. Particularly, the non-linear Coulomb friction causes position errors as well as slow responses that lead to unfavorable performance. In this paper, a modified PID controller that is augmented by Coulomb friction estimator is presented. Through constantly estimating the Coulomb friction torque, it is applied to the output of the existing PID controller. The effectiveness of the proposed controller is evaluated through a series of experiments.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.12
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• pp.2386-2391
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• 2011

Tracking and detecting targets by the millimeter wave seeker is affected by moving of platform. In order to perform the tracking performance, stabilization of a millimeter wave seeker which consists of 2-axis gimbals was considered in this study. The feasibility of the analysis and the 2-axis gimbal servo system modeling design were verified along with some simulation results.