• The Journal of Korean Association of Computer Education
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• v.15 no.6
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• pp.75-82
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• 2012

The sensor registry system has been proposed to interpret and process semantics of sensor data independently of heterogeneous sensor networks. However, the existing sensor registry system provides the static processing method. In other words, the existing system reduces the overall performance because it executes unnecessary operations and does not consider data scope to be used. To resolve the problem of the existing sensor registry system, this paper proposes a performance enhancement model based on sensor metadata reusability and scoping. The proposed model in this paper provides a function that can decide a proper scope of sensor metadata from the sensor registry system. The proposed model improves the overall performance by providing reusability of sensor metadata. This paper also shows the advantages of the proposed model through the comparative performance evaluation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12C
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• pp.1144-1152
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• 2005

Intra prediction coding is one of the many coding-efficiency oriented tools of H.264/AVC, but it requires high computational complexity. Many fast intra coding algorithms have been proposed to reduce the computational complexity of intra prediction. While most of them have been focused on the mode decision methods themselves, we propose a fast algorithm in which new intra modes are substituted for the conventional intra modes so that the number of intra modes can be reduced. The simulation results show that the proposed method could reduce the encoding time of the overall sequence by $49\%$ without any noticeable degradation of the coding efficiency.

• Journal of ILASS-Korea
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• v.10 no.2
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• pp.41-47
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• 2005

Exhaust gas emissions from internal combustion engines are one of the major sources of air pollution. And. it is extremely difficult to increase gasoline engine efficiency and to reduce NOx and PM(particulate matter) simultaneously in diesel combustion. This paper offers some basic concepts to overcome the above problems. To solve the problems, a recommended technique is CAI(controlled auto-ignition) combustion. In this paper. internal EGR(exhaust gas recirculation) effect is suggested to realize CAI combustion. An experimental study was carried out to achieve CAI combustion using homogeneous premixed gas mixture in the constant volume combustion chamber(CVCC). A flame trap was used to simulate internal EGR effect and to increase flame propagation speed in the CVCC. Flame propagation photos and pressure signals were acquired to verify internal EGR effect. Flame trap creates high speed burned gas jet. It achieves higher flame propagation speed due to the effect of geometry and burned gas jet.

• Journal of Hydrogen and New Energy
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• v.21 no.2
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• pp.129-135
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• 2010

Homogeneous charge compression ignition (HCCI) engines have the potential to provide both diesel-like efficiency and very low emissions of nitrogen oxide (NOx) and particulate matter(PM). However, several technical issues still must be resolved before HCCI can see application. Among these, steep pressure-rise rate which leads to narrow operating range of HCCI engine continues to be a major issue. This work investigates the combination of two methods to mitigate the excessive pressure-rise rates at high power output, namely fuel stratification and Cooled exhaust-gas recirculation (Cooled EGR), after identifying the each effects to pressure-rise rate. When applying the fuel stratification to simulation, total fuelling width of 0.15 at BDC is set as a equivalent ratio difference based on the previous research. In order to simulate the effects of cooled EGR, $CO_2$ mole fraction in pre-mixture is changed ranging from 0 to 30%. DME which has a characteristic of two-stage ignition is used as a fuel.

• Economic and Environmental Geology
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• v.34 no.6
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• pp.523-537
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• 2001

The physical properties of pH, turbidity, TDS and salt contents in the stream water near the entrance of Woonjcongdong sanitary landfill area with a drainage pipe are higher than those in neighbored drainage system, but DO it lower than that in neighbored drainage system blue to the eutrophication. In the ground water, pH, turbidity, TDS and salt contents at A ,F and C where may be under effect of the Woonjeongdong sanitary landfill area, are also shown higher values in contrast to other groundwater site, like B , D , and E , Particularly, the groundwater in A , F and C are plotted in Na-Cl type (If the piper diagram, which is an another important prolf of the contaminapion by the leachate and washing water from the Woonjeongdong sanitary landfill area. Some elements and physical properties of the waters in rainy season are desplayed a clear characteristics of contaminaton, compared to the theose of winter in thes study. Elements such as Ca, Mg, Na, K, Cl­,$SO_4^{2-} , \;and \;F­^-$) are accompanied well with each other by the result of water in the vicinity of landfillarea.

• Proceedings of the KIEE Conference
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• 2008.04a
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• pp.221-222
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• 2008

This paper is proposed a high performance speed control of the synchronous reluctance motor through the artificial intelligent SV-PWM. SV-PWM is controlled using fuzzy control that is artificial intelligent control. SV-PWM can be maximum used maximum dc link voltage and is excellent control method due to characteristic to reducing harmonic more than others. Fuzzy control has a advantage which can be robustly controlled. Simulation results are presented to show the validity of the proposed algorithm.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1143-1145
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• 2002

IPMSM (Interior Permanent Magnet Synchronous Motor) is widely used in many applications such as an electric vehicle, compressor drives of air conditioner and machine tool spindle drives. In order to maximize the efficiency in such applications, this paper is proposed the optimal control method of the armature current. The controllable electrical loss which consists of the copper loss and the iron loss can be minimized by the optimal control of the armature current. The minimization of loss is possible to realize efficiency optimization control for the proposed IPMSM. The proposed control algorithm is applied to IPMSM drive system, the operating characteristics controlled by efficiency optimization control are examined in detail by simulation.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1140-1142
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• 2002

This paper is proposed to position and speed control of interior permanent magnet synchronous motor(IPMSM) drive without mechanical sensor. The rotor position, which is an essential component of any vector control schemes, is calculated through the instantaneous stator flux position and an estimated flux value of rotating reference frame. A closed-loop state observer is implemented to compute the speed feedback signal. The validity of the proposed sensorless scheme is confirmed by simulation and its dynamic performance is examined in detail.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.153-159
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• 2010

This article presents a method that improve the drive-license test system, especially the course-driving by using the image processing. Decision(pass or not) is recorded and informed to test-driver after the image processing such as image capture, grayscaling, normalization, Hough transform and decision. That result system enables us to manage much more economically and effectively.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2010.09a
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• pp.18-24
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• 2010

이 연구의 목적은 대한지적공사에서 추진하고 있는 지적정보서비스 유통 방안을 마련하기 위해 공공과 민간부분의 지적정보서비스 현황과 수요를 파악하고 분석하는데 있다. 이 연구에서는 심층면접과 개별면접을 병행하여 지적정보의 인지도와 활용도를 포함한 지적공간정보에 대한 활용실태, 지적공간정보의 품질만족도, 향후 지적공간정보 수요 예측, 지적공간정보의 유통서비스체계에 대한 선호도, 공사의 사업 다각화, 공간정보 시장의 수요 등을 정확히 파악한 후 지적정보의 이 활용과 유통을 증진시킬 방안을 도출하였다.