• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.7
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• pp.14-21
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• 2015

Distribution systems are operated in radial structure, but temporal loop structure could be founded the live load transfer. Main purposes of reconfiguration of distribution network are load balancing, loss minimization and voltage drop maintaining. In the loop structure, huge loop current can be flowed between two substations in case of large voltage angle difference. Protection devices of distribution line can be triped by this huge loop current. So, precise calculation of loop current is very important for secure switching. This paper proposes a novel calculation method of loop current using the voltage angle differences measured at the tie switches. Feasibility of the propose method has been verified by various case studies based on Matlab simulation.

• Journal of the Korea Society of Computer and Information
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• v.4 no.2
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• pp.105-112
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• 1999

Spread Spectrum Communication is a core technique in CDMA system, but the problem for SS Communication schemes is synchronous method. There are DLL(Delay Lock Loop), Tau-dither Loop, SO(Synchronous Osillator) etc., in the sychronous method. But since there are analog operations, the setting is difficult and circuit size is large. In this paper we proposed Digital Delay Lock Loop (DDLL) and estimated it's performance through the experiment.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.35-50
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• 2007

A contact patch between the wheel and the rail supports the train body and a traction power comes from it when rolling stocks run on the railroad. Friction force between the wheel and rail makes the train move on the rail. Whenever the train runs on the rail, the wheels and rails wear down by frictions inevitably. So it must be shaped by the lathe or changed for the safety train operation and the comfortable ride. Until now, many measures were carried out in order to prevent a wear and tear of the wheels. For example loop line railway in Kun Ja depot and Ji Chuk depot. This document reports the wheel changing data taken by maintenances department for the period before and after 1996 in the 1.2.3.4 lines in Seoul metro.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.1
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• pp.94-99
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• 2004

The global stiffnesses and vibration characteristics of vehicle structures are mainly influenced by local stiffnesses of the joint structures consisted of complicated thin-walled panels. In this paper, the parametric study for the stiffnesses of the center pillar-roof rail joint of vehicle structure is performed through the linear static analysis. The analysis result shows that the reinforcement panel much affects the joint stiffness of out-plane direction (i.e., z-direction). And also, the flange radius and width of the joint structure much affect the Joint stiffness of out-plane direction. The study shows that vehicle joint stiffnesses can be effectively determined in designing vehicle structure through the parametric study.

• Journal of Welding and Joining
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• v.14 no.4
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• pp.7-15
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• 1996

아크 용접 공정을 자동화하고 무인화하는 것은 용접 품질향상 및 생산성 향상 에 기여할 뿐만 아니라 용접숙련공의 감소문제에도 대처할 수 있기 때문에 중요한 것이라 생각된다. 그것을 위해 아크용접 분야에도 로봇의 도입이 급격히 증가하고 있는 추세이다. 그러나 현재 현장에 도입된 로봇은 주로 off-line으로 그 기능을 수행 하고 있기 때문에 생산성 향상 및 용접 품질향상 면에서 그 기능을 충분히 발휘하고 있지 못하고 있는 실정이다. 이런 단점을 극복하기 위해서는 센서의 도입과 그것을 이용하여 용접시스템을 퍼드백 루프로 구성할 필요가 있고 용접선 추적(seam tracking), 용융지 형상제어, 아크 길이 제어 등은 그 예라고 할 수 있다. 본논문에서 는 그동안 국내에서는 심도있게 취급되지 않았던 용융지 형상 제어시스템과 그것을 구성하기 위해 많이 사용되고 있는 비전센서에 관하여 서술한다.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.2
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• pp.53-57
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• 2017

This papers propose a Hall-effect sensors position error compensation method in a sunroof system using a BLDC motor with a low-cost MCU. If the BLDC motor is controlled with this wrong position, the torque ripple and operating current can be increased and the average torque also decreases. Generally, sunroof system has characteristics that operate at constant load for several seconds. It is possible to find the minimum operating current value while changing the position of the Hall-effect sensor during the sunroof operation by using these characteristics. Therefore, propose a method to change the Hall-effect sensor position and find the minimum current value. The validity of the proposed algorithm is verified through experiments.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.6
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• pp.545-550
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• 2009

Generally, the smoothing pre-filter of sensor's raw measurement(accelerometer and gyroscope) is used for INS's fast alignment. When the pre-filter is abruptly removed at Navigation-mode entry in vibration environment, INS's initial attitude error can be largely generated. So that we propose initial attitude error reducing methods(monotone increasing of cutoff-frequency, real-time attitude estimation), these are proved by simulation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.3 s.357
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• pp.98-104
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• 2007

In this paper, the dual-band open loop antenna using a strip conductor for the RFID reader and Wireless LAN Application, which has a resonant frequency at 910MHz and 2.45 GHz, is proposed. Input impedance of antenna is matched with the feed line of 50 ohm by varying the length and width of sip conductor making up the antenna. The gain and directivity of antenna is enhanced as tuning the length of strip, and as also grooving the teeth shapes on the strip conductor. The size of fabricated antenna is $75mm\times100mm$. The return loss and the gain of fabricated antenna are -11.92 dB, 3.02 dBi at 910 MHz and -21.31 dB, 4.08 dBi at 2.45 GHz, respectively.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.5
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• pp.1-6
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• 2007

This paper presents a new experimental Servo-Parameter tuning technique for a 6-axes articulated robot manipulator, especially considering robot's dynamics. First of all, investigation for proportional gain of velocity control loop by using a Dynamic Signal Analyzer(DSA) is performed. Using the FUNCTION characteristic of DSA based on the Bode plot, the Bode plot of open loop transfer function can be obtained. In turn, the integral gain of a servo controller can be found out by using the integration time constant extracted from the Bode plot of open loop transfer function. In the meanwhile, the positional gain of the servo controller can be obtained by using the Bode plot of the closed loop transfer function. Using the experimental gain tuning technique proposed in this paper, the testing linear motion of DR6-II robot has been shown to be more accurate rather than the motion with a conventional(empirical) gain tuning technique in Doosan Mecatec Co., Ltd., by improving the dynamic response of the robot as well as synchronizing each joint velocity according to the positional command of an end-effector.

• Journal of Internet Computing and Services
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• v.11 no.4
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• pp.59-72
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• 2010

WIM(Weigh-In-Motion) is the system measuring the weight of the vehicle with a high-speed. In the existing WIM system, vehicle weight is measured based on the constant speed and the error ratio has 10%. However, because of measuring the driving pattern, that is abnormal driving pattern which is like the acceleration and down-shift of the drivers, it has the error ratio which is bigger than the real. In order to it reduces the error ratio of WIM system, the improved WIM system needs to find the abnormal driving pattern. In order to reducing the error ratio of these WIM systems, the improved WIM system can find abnormal driving patterns. In this paper, the improved WIM system which analyzes the abnormality driving pattern influencing on the error ratio of WIM system of an existing and minimizes the error span is designed. The improved WIM system has the multi step loop structure of adding the loop sensor to an existing system. In addition, the measure function defined as an intrinsic is improved and the weight measured by the abnormal driving pattern is amended. The analysis of experiment result improved WIM system can know the fact that the error span reduces by 8% less than in the existing the maximum average sampling error 22.98%.