• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.4
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• pp.303-310
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• 2008

Recently, IEC 61850 supports the standardized communication technique in both station bus and process bus, and presents substation automation model. In order to implement the IEC 61850 based communication in a substation using the MU (merging unit) which is one of the important data acquisition equipments in substation automation, the time synchronization is demanded for cooperative operation between the devices. This paper proposes the precision time synchronization technique using IRIG-B protocol to develop the MU under IEC 61850 communication protocol. The proposed technique is implemented and its performance is verified experimentally.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.5-6
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• 2008

차단기, 개폐기, 배전반과 같은 전력기기에 대한 성능시험시, 전압과 전류, 제어신호를 측정하고, 필요한 경우 고속카메라를 이용해 시험장면을 촬영한 다음, 이들을 종합적으로 분석하여 시험결과를 판정한다. 이때, 대부분 개별 시스템으로 전압-전류 시험파형과 시험영상을 측정하고 분석하기 때문에, 시간 동기화가 불가능하여 시험현상이나 시료동작특성 분석에 많은 어려움이 있다. 따라서 개별 시스템으로 측정한 신호를 동기 시켜 동시에 분석할 수 있는 프로그램이 있다면, 시험결과 판정뿐만 아니라 시험 중에 발생하는 전기적 과도현상이나 시료의 동작특성분석에 많은 도움이 될 것이다. 이러한 목적을 위해, PT&T에서는 측정시스템과 고속카메라를 이용하여 측정한 전압-전류 시험파형과 시험영상을 동기 시켜 동시에 분석할 수 있는 프로그램인 Dual Viewer를 개발하였다. 본 논문에서는 Dual Viewer에 대한 기능과 특징에 대해 소개하고자 한다.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.8
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• pp.883-890
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• 2015

As the semiconductor processing technology has been developing, multiple cores or NoC(network on chip) can be contained in recent chips. GALS(globally asychronous locally synchronous) clocking scheme that has multi-clock domains with different frequencies or phase differences is widely used to solve power consumption and clock skew in a large chip with a single clock. A synchronizer is needed to avoid a synchronization problem between sender and receiver in GALS. In this paper, the setup and hold time of DFF required to design the synchronizer are measured using 180nm CMOS processing parameters depending on temperature, supply voltage, and the size of inverter in DFF. The simulation results based on the bisection method in HSPICE show that the setup and hold time are proportional to temperature, however they are inversely proportional to supply voltage, and negative values are measured for the hold time.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.5 no.1
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• pp.111-115
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• 2011

In this paper, we present a novel time-synchronization method for distributed systems to measure the body motion. The distributed system scheme is considered because human data acquisition systems tend to have a centralized controller with sensors connected with a long range of electric wires running through the subject's body, which results in inconvenience. Utilizing simple key switches and digital input ports for reading the key, the proposed method requires a very simple hardware structure, which means less power consumption compared with the well-known ubiquitous sensor network. After measuring the motion data as well as the synchronization pulses, the proposed method compensates, in offline, the difference of the sampling instance between the two systems by scaling the time difference. The paper presents experimental results to show the validity of the proposed method.

• Journal of the Korean Society for Railway
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• v.20 no.5
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• pp.595-601
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• 2017

Due to the electrification of railways, fault at the traction line is increasing year by year. So importance of the fault locator is growing higher. Nevertheless at the field traction line, it is difficult to locate accurate fault point due to various conditions. In this paper railway feeding system current loop equation was simplified and generalized though measured data. And substation, train power data were measured under synchronized condition. Finally catenary impedance was predicted through generalized equation. Also simulation model was designed to figure out the effect of load current for train at same location. Train current was changed from min to max range and catenary impedance was compared at same location. Finally, power measurement was performed in the field at train and substation simultaneously and catenary system impedance was predicted and calculated. Through this method catenary impedance can be measured more easily and continuously compared to the past method.

• Journal of KIISE:Information Networking
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• v.35 no.2
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• pp.166-172
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• 2008

This paper proposes an autonomous decentralized frame synchronization system for Ad-hoc Inter-Vehicle Communication Network (IVCN). We have to consider the feature of Ad-hoc IVCN: "time variant" about the number and the location of vehicles and receive power in IVCN, frame timing, and fading. Proposed scheme is different from other decentralized synchronization systems that have association with a fixed base station, and from centralized Personal Communication Systems. This system includes an autonomous decentralized frame synchronization scheme for Ad-hoc IVCN, a high-speed algorithm, a protocol for a newly joining subscriber in IVCN, and a utilization of spread spectrum ranging for frame timing error of the system under highway conditions. Performance evaluation of proposed scheme is validated through simulation. It is shown that Ad-hoc IVCN can be carried out among one and surrounding vehicles in such environment.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.589-592
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• 2011

Induced longitudinal voltage and induced noise voltage are used in the analysis on the power induction phenomenon and it is well known that these are in the subordinate relationship. But sometimes. there is a confusing situation that these voltages have not exact subordinate relationship in the actual measurement fields. So. we have analyze the correlation between induced longitudinal voltage and induced noise voltage by using tile actual measured data in the fields of 30 urban areas and 30 rural areas.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.7
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• pp.703-707
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• 2008

This paper designs and implements a software prober to support a more effective power analysis for Linux-based embedded systems by using power consumption data measured in hardware. The proposed software prober, which is included in a target system as a module, collects power data and provides a service to discover major power consumers in user functions of applications or kernel functions through time synchronization between the power data measured in hardware and software. In addition, we verified usefulness of the implemented software prober by running user applications on target systems.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.171-172
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• 2015

PMU (Phasor Measurement Unit)는 전력시스템의 노드에서 실시간으로 시간 동기화된 페이저 정보를 측정하여 전력계통 모니터링을 가능하게 하는 장치이다. 이 때, PMU가 모니터링 장치로서 활용되기 위해서는 고신뢰도의 페이저 정보 측정이 요구된다. 기본적인 페이저 추정기법은 푸리에 변환을 이용하여 정현파 신호의 기본주파수 성분을 분석하는 것으로 본 논문에서는 푸리에 변환 기반 페이저 추정기법과 웨이브렛 기반 페이저 추정기법의 성능을 분석하여 웨이브렛 기반 페이저 추정기법의 타당성을 검토하고자 하였다. 페이저 추정기법의 평가에는 IEEE 표준에 따른 TVE (Total Vector Error) 개념을 사용하며 정현파 신호의 진폭변화와 위상변화 및 잡음발생 환경의 진폭변화에 대하여 페이저 추정 기법들의 성능평가로 신뢰성을 확인하였다.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.1
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• pp.73-80
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• 2015

The valve device is installed in hazardous areas, such as a chemical plant explosion has been sealed with fire protection device to prevent the risk of explosion. In this paper, due to the explosion-proof devices using external power the device can not be used in infrared sensors and Zigbee sensor valve device by measuring the open degree of valve opening and closing of the danger zone to check whether. Valve opening and closing operation log screen time, we propose a low-power operation monitoring system administrators to manage and control the plant. Develop power control relay board apply an improved algorithm to apply the asynchronous LPL power management. The plant monitoring system and explosion-proof valve opening and closing the valve system with the intelligent device designed and implemented and tested it.