• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.10
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• pp.826-830
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• 2010

This study examined the effect of the scattering dose on the thyroid during a mammography examination. One hundred subjects for a mammography examination were enrolled in this study. The average glandular dose (AGD) and thyroid scattering dose (TSD) were measured. Statistical analysis was carried out using the percentage, t-test and co-variance. The mean radiation exposure to the breast and thyroid was $1.08{\pm}0.16$ and $0.14{\pm}0.04$ mGy, respectively. The percentage TSD to the AGD was 31.19%. There was no difference between the Rt. and Lt., and CC to MLO, and radiation dose to the TSD was 13.78% of the breast. Therefore, the volume of radiation exposure to the thyroid was 54.12% in a single routine mammography examination. These results suggest that the TSD was increased by increasing radiation dose to the breast. A thyroid protector is considered necessary to decrease the level of radiation exposure.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.6
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• pp.1245-1254
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• 2011

This paper proposes a target tracking algorithm for wheeled mobile robots using in various fields. For the stable tracking, we apply a vision system to a mobile robot which can extract targets through image processing algorithms. Furthermore, this paper presents an algorithm to position the mobile robot at the desired location from the target by estimating its relative position and attitude. We show the problem in the tracking method using the Position-Based Visual Servo(PBVS) control, and propose a tracking method, which can achieve the stable tracking performance by combining the PBVS control with Image-Based Visual Servo(IBVS) control. When the target is located around the outskirt of the camera image, the target can disappear from the field of view. Thus the proposed algorithm combines the control inputs with of the hyperbolic form the switching function to solve this problem. Through both simulations and experiments for the mobile robot we have confirmed that the proposed visual servo control method is able to enhance the stability compared to of the method using only either PBVS or IBVS control method.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.402-403
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• 2008

한전의 신배전정보시스템(NDIS)은 지리정보시스템(GIS)을 활용하여 전국에 시설되어 있는 방대한 배전설비를 데이터베이스로 구축한 후 배전계획, 배전설계, 공사관리, 준공정산, 자산취득, 유지보수 등 배전분야 전반의 업무를 수행하고 고객정보시스템과 연계하여 영업업무를 지원하는 시스템으로 저압공급방안검토, 고압계통분석, 보호협조검토, Simulation 등 배전분야에서 필요한 다양한 기술지원 기능과 경제적인 투자계획, 효율적인 유지보수 등을 위한 배전통계 및 자원정보 등 장기적 관점의 경영정보 인프라를 구축하여 배전설계에서 준공까지 업무흐름 표준화, 업무처리 절차, 방법 등을 시스템에서 자동 지원토록하여 반복적인 배전정보 관리업무의 정확도 향상을 목적으로 만들어진 시스템이다. 신배전 정보시스템의 배전설비는 모두 위치값을 가지고 있는데 지중배전설비는 위치에 대한 측량 및 탐사를 시행하여 신배전정보시스템에 DB입력하여 사용하고 있으며 이 입력 좌표체계는 한정된 일부지역에서만 사용할 수 있는 동경측지계를 사용하고 있다. 2010년 부터는 이동 경측지계를 전 세계적으로 GPS측량값을 그대로 적용할 수 있는 세계 측지계로 사용토록 측량법에 명시되어 있어 신배전정보시스템의 배전설비를 전환 프로그램을 개발하여 전환하고자 한다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.9
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• pp.1628-1635
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• 2008

In this paper, the motion coordination algorithm of mobile agents in active sensor network is proposed to track the dynamic boundary for environmental monitoring. While most of dynamic boundary tracking algorithms in the literature were studied under the assumption that the boundary and/or its evolving rate is known a priori, the proposed algorithm is assumed that the individual active agent can measure the state of environment locally without any information of the boundary. When the boundary is evolving dynamically, the formation of active agents is designed to achieve two objectives. One is to track boundary layer based on the measured information and a small deviation. The other is to maintain a uniform distance between adjacent agents. The algorithm structure based on a state diagram is proposed to achieve these two objectives. Finally, it will be shown in the simulations that all given agents converge to a desired boundary layer and maintain a formation along the boundary. (e.g., a circle, an ellipse, a triangle and a rectangle)

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.6
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• pp.852-862
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• 2013

This paper proposes a target tracking control method for wheeled mobile robots with nonholonomic constraints by using a backstepping-like feedback linearization. For the target tracking, we apply a vision system to mobile robots to obtain the relative posture information between the mobile robot and the target. The robots do not use the sensors to obtain the velocity information in this paper and therefore assumed the unknown velocities of both mobile robot and target. Instead, the proposed method uses only the maximum velocity information of the mobile robot and target. First, the pseudo command for the forward linear velocity and the heading direction angle are designed based on the kinematics by using the obtained image information. Then, the actual control inputs are designed to make the actual forward linear velocity and the heading direction angle follow the pseudo commands. Through simulations and experiments for the mobile robot we have confirmed that the proposed control method is able to track target even when the velocity sensors are not used at all.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2046-2052
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• 2016

Ramp metering is one of the most efficient and widely used control methods for an intelligent transportation management system on a freeway. Its objective is to control and upgrade freeway traffic by regulating the number of vehicles entering the freeway entrance ramp, in such a way that not only the alleviation of the congestion but also the smoothing of the traffic flow around the desired density level can be achieved for the maintenance of the maximum mainline throughput. When the cycle of the signal detection is larger than that of the system process, the density tracking problem needs to be considered in the form of the discrete-time system. Therefore, a discrete-time sliding mode control method is proposed for the ramp metering problem in the presence of both input constraint in the on-ramp and exogenous disturbance in the off-ramp considering the random behavior of the driver. Simulations were performed using a validated second-order macroscopic traffic flow model in Matlab environment and the simulation results indicate that proposed control method can achieve better performance than previously well-known ALINEA strategy in the sense that mainstream flow throughput is maximized and congestion is alleviated even in the presence of input constraint and exogenous disturbance.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.11
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• pp.2058-2065
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• 2010

This paper presents the sensor location and step estimation algorithm for personal navigation system (PNS). PNS has the disadvantage in that the position of the sensor must be fixed on a human body. Three-axis acceleration sensor is used to solve the disadvantage and to consider the real situation. We simplify the measurement data by using the band pass filter, witch It has the advantage in the detection of characteristic point. Through the detected characteristic points, it is possible to setup the parameter for the pattern detection. Depending on the sensor location, the parameters have the different type of noise covariance. Particularly, when the position of the sensor is changed, the impulse noise shows up. Considering the noise, we apply the recursive least square algorithm using the variable forgetting factors, which can classify the sensor location based on the estimated parameters. We performed the experiment for the verification of the proposed algorithm in the various environments. Through the experimental results, the effectiveness of the proposed method is verified.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.7
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• pp.1270-1276
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• 2016

This paper proposes the controller design for regulation control of two-link robot arm using sum of squares (SOS) control method that takes into account the input constraint. The existing studies of two link robotic arm system used a linear model of all the non-linearity of the system is linearized. For a linear controller, since the model of the system is simplified, it is possible to design a controller in consideration of constraints on the disturbance. However, there is a limit to the performance using a linearized model for a system with a complex nonlinear properties. To compensate for this in the case of using a fuzzy LMI method, it is necessary to have a large number of linear models and thus there is a disadvantage that the system becomes complicated. To solve these problems, we represents a two-link robot arm system with a polynomial model using a Taylor series expansion and design the controller considering the case where the magnitude of the control input is limited using SOS method. We demonstrate by simulations the feasibility of the proposed algorithm.

• Journal of the Korean Institute of Telematics and Electronics
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• v.10 no.3
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• pp.10-22
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• 1973

Recently, nematic and nematic-cholesteric mixtures of substances have been discovered which have stimulated progress in electronics research and industry. In the liquid crystalline state, compounds with nematic mesopheses possess the ability to scatter light, depending on the strength of an applied electric field. The rewaking of interest in this fascinating but long-neglected area has occasioned the introduction of the subjects at the situation of the chemists. Since 1888 year, approximately 2000 compounds have been found to possess the unusual properties of what are commonly referred to as liquid crystals. In this paper, a comprehensive review will not be attempthed here. Nevertheless, some general information necessary to familarize the reader with rather exotic field will facilitate an understanding of the new effect and its application.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.567-570
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• 2001

In the Asia Pacific Summit on Information Society in Tokyo, Ministers for information and communications of member countries of the APT(Asia Pacific Telecommunity) shared the view that it is necessary to take initiatives to unite efforts of all concerned and to tackle In(Information and Communication Technology)-related issues, so that a sound information-based society is established which respects the diversity of the Asia Pacific Region. At that meeting, Ministers adopted the Declaration and Action Plan for the Asia Pacific Renaissance through ICT. Thus, this paper focuses on analysis of the major issues regarding Declaration and Action Plan for the Asia Pacific Renaissance. In addition, this paper introduces the APT's following actions to implement the Declaration and Action Plan for Asia Pacific region.