• Journal of Internet Computing and Services
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• v.6 no.1
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• pp.27-38
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• 2005

Recently, the rapidly development of computing environments and the spread of Internet make possible to obtain and use of information easily. Immediately, by opposition function the Hacker's unlawful intrusion and threats rise for network environments as time goes on. Specially, the internet consists of Unix and TCP/IP had many vulnerability. the security techniques of authentication and access controls cannot adequate to solve security problem, thus IDS developed with 2nd defence line. In this paper, intrusion detection method using Bayesian Networks estimated probability values of behavior contexts based on Bayes theory. The contexts of behaviors or events represents Bayesian Networks of graphic types. We profiled concisely normal behaviors using behavior context. And this method be able to detect new intrusions or modificated intrusions. We had simulation using DARPA 2000 Intrusion Data.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.4
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• pp.829-838
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• 2015

As the number of smartphone users have increased, many kinds of malwares have emerged. Unlike existing malwares, spyware can be installed normally after user authentication and agreement according to security policy. For this reason, it is not easy to catch spywares involving harmful functionalities to users by using existing malware detection system. Therefore, our paper focuses on study about detecting mainly wiretapping spywares among them by developing a new wiretapping detection model and application. Specifically, this study conducts to find out power consumption on each application and modular and network consumption to detect voice wiretapping so Open Source Project Power Tutor is used to do this. The risk assessment of wiretapping is measured by gathered all power consumption data from Open Source Project Power Tutor. In addition, developed application in our study can detect at-risk wiretapping spyware through collecting and analyzing data. After we install the application to the smartphone, we collect needed data and measure it.

• The KIPS Transactions:PartA
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• v.14A no.2
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• pp.125-132
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• 2007

Recently, in the engineering area, there is an increasing need for researchers at a distance to share the result of the experiment, without having to visit the experiment facilities. Especially in the civil engineering, researchers feel the need for participating in a experiment conducted at a distant location. In addition, it is suggested that high-cost facilities should be used by remote researchers thereby increasing the utilization rate. This paper proposes a remote experiment environment in civil engineering that are being developed in a project called Korea Construction Engineering Development(KOCED), which connects major civil engineering experiment facilities using grid technology, allows researchers to participate in a remote experiment, and has the experiment results shared by remote researchers automatically. Then, based on the suggested environment, we designed a hybrid test facility that involves two physical experiment facility sites and one numerical simulation site that are geographically apart. Then, we implemented its prototype and ran some tests, which showed a possibility of grid-based civil engineering experiment.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.3
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• pp.319-328
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• 2000

The Message-Passing Interface(MPI) is a standard interface for parallel programming environment, based on that application programs run on the processors of a parallel computer. Processor nodes execute processes consisting the program by passing messages to one another. During executing, however, if a fault occurs on a processor node or a process, this will result an inconsistent state, and consequently, the whole program will have to be stopped. To solve this problem, in this paper, we propose a fault-tolerant message passing interface(FT-MPI) by adding a fault manager module to MPI. The proposed FT-MPI does not need any hardware support, and each application program based on MPI can run on the FT-MPI without any modification. The proposed fault tolerance scheme uses the so-called hot-spare process duplication method, and verified by simulations that application programs run despite of any fault with less than 5% overhead on execution time.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.1
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• pp.39-47
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• 2008

Automatic landing performance of UAV can be enhanced by adding Pseudolite(PL) to GPS. However, it is very hard to install and operate PL with confidence because GPS satellites are moving and the landing zone are usually changeable. The coverage and accuracy of combined GPS and PL can be estimated by using simulator and the correct information is very crucial to UAV operation. In this paper, design, implementation and evaluation of GPS/PL simulator for UAV landing are given. A very realistic coverage estimation is obtained using GIS data and ray launching method with considerations of the transmitter power level, altitude of UAV, number and location of PL. The expected accuracy is estimated using DOP and NSP computed using both GPS and PL. The performance of simulator is evaluated by comparing with the results of a real GPS receiver, and the certified simulator shows the required accuracy for UAV landing can be easily met by proper installation of at least 2 PLs.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.12
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• pp.1095-1100
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• 2007

Visibility of the satellite navigation is related to a environmental condition of a receiver. Obstacles like buildings and trees in urban areas can block signals and have effects on accuracy and reliability of positioning. This paper presents a method of creating 3D analysis model of urban canyon of Seoul using three-Dimensional digital map. Analysis techniques of visible satellites with Ray-Polygon Collision Detection and validation of algorithm through field tests are discussed. We have compared and analyzed the visibility of GPS and Galileo with respect to separate and simultaneous tracking in view of DOP (Dilution of Precision) using the 3D GIS digital map.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.6
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• pp.40-48
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• 2013

Recently, many types of electric vehicles including a heavy duty vehicle have been developed and released because of the better fuel economy and less gas products. In this study, research about an electric bus which utilizes the wheel motor drive system was conducted. The wheel motor is a motor connected to the wheel directly only with a simple gear so that the developer can utilize the space efficiently and the whole system efficiency will be better because of simple structure. However, because it is different from former types of vehicles which use the differential gear, the development of the integrated control logic is required in order to meet the vehicle stability and driving performance. The developed control logic is composed with direct yaw moment control, regenerative braking control and slip control logics. It is compared to the control logics which does not consist of direct yaw moment control and slip control when the vehicle is exposed in tough situations. For the unification of the control logic, a few maps were developed and applied to determine the output torque of each motor according to the driving status. As a result, it is shown that the developed control logic is more safe and well follow the target speed than the other control logic applied simulations.

• Journal of Korean Tunnelling and Underground Space Association
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• v.4 no.4
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• pp.343-353
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• 2002

In the past many tunnels have been built to lowest capital investment cost without adequate regard for the cost of operation. But according to increasing the capacity of a ventilation system and to becoming diverse, it is to become more important to come up with the optimal operation stage of ventilation system. In this study, the tunnel ventilation dynamic simulation program had been developed. it is used to calculate the unsteady-state tunnel air velocity and concentration of pollutants according to the assumed average day traffic profile and summarize the energy consumption for the operation of ventilation system. And the operation energy consumption for the electric precipitation system and vertical vent shaft system are evaluated and compared in various operation mode. As the results of this study, the optimal operation stage for these ventilation system are provided.

• Journal of Biosystems Engineering
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• v.26 no.6
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• pp.553-562
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• 2001

The greenhouse heating system with heat pump and latent heat storage was built for development of simulation model and validation. The computer simulation model for the system to predict temperature of air, soil surface and cover film in the greenhouse were developed and its validity was justified by actual data. From the analysis of experimentally measured and the simulation output, following results were obtained. 1. The expected values of inside air temperature for the greenhouse with a heat pump and a latent heat storage system were very much close to the experimental values at the error range of 1.0$\^{C}$. 2. The expected values of soil surface temperature fur the geenhouse with a heat pump and a latent heat storage system were very much close to the experimental values at the error range of 1.0$\^{C}$. 3. The expected values of thermal energy flow fur the greenhouse with a heat pump and a latent heat storage system were very much close to the experimental values at the error range of 167.2kJ/m$^2$h. 4. Heat lass value of day time was found to be larger than that of night time as much as 1.11 time. 5. At day time. the inside air temperature was shown to be higher than the set point of 7.0$\^{C}$. At night time, the inside air temperature was controlled in order to maintain higher temperatures than the set point.

• Journal of Korea Multimedia Society
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• v.22 no.11
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• pp.1280-1287
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• 2019

For developing a wireless implantable device to monitoring the artery variation in real-time. The concept of a special vessel variation measurement capacitive sensor is presented in this paper. The sensor consists of two part; main sensor to measuring the arterial variation, and reference sensor is used to improve the accuracy of the capacitance value variation. Before sensor manufacture, a model of the sensor attached on the artery was designed in 3D to conduct in the FEA simulation to validate the validity and feasibility of the idea. The artery model was designed as layered structures and made of collagenous soft tissues with intima inside, followed by the media and the adventitia. Also, a grease layer was designed in the inner of the arterial wall to imitate the clogged arteries. The simulation was divided into two parts; sensor performance test by changing the diameter of the grease layer, and arterial wall tension test by changing the blood pressure. As the simulation results, the capacitance value measured by the proposed sensor is decreased follow the diameter of the grease increased. Also, large elastic deformation of the arterial wall since changing the blood pressure has been observed.