• Journal of the Korean Society of Industry Convergence
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• v.21 no.6
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• pp.361-368
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• 2018

This paper proposes a grid - connected CTTS system that can be soft switched to meet the government's effective resource allocation policy for emergency generator. In order to eliminate the system instability caused by the large inrush current generation in the system switching, a new virtual rotation coordinate method for the dissimilar power source is proposed. The proposed virtual rotation coordinate method improves the voltage detection accuracy of the voltage difference of the dissimilar power supply, and it is proved that the synchronous switching characteristic is excellent. In addition, zero current and system stabilization can be achieved by realizing zero current when blocking CTTS with instantaneous reactive power control. Simulation was carried out to verify the validity of the proposed method, and the 500[kVA] system was fabricated and verified to demonstrate the superiority of the proposed method.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.1
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• pp.53-62
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• 2023

Due to the recent increase in new and renewable energy, gas turbine generators start and stop every day to supply high-quality power, and accordingly, the life span of high-temperature parts is shortened and the failure of combustion chamber temperature sensors increases. Therefore, in this study, we proposed a fuzzy logic-based failure diagnosis algorithm that can accurately diagnose and systematically detect the failure of the sensor when the dual temperature sensor used for gas turbine control fails, and to confirm the usefulness of the proposed algorithm We tried to confirm the usefulness of the proposed algorithm by performing various simulations under the matlab/simulink environment.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2017.11a
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• pp.206-208
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• 2017

In recent years, we have been working on the improvement project of mercury 3-lecture type at the Geummundo lighthouse for more than 100 years. We have installed toxic mercury removal, LED light source, and dualization system for nonstop. It can be seen as an example. Circular restoration of the entire frame is performed, and the real-time status can be grasped through the installation of the double-ball bearing and the remote control system. After installation, optical measurement through Hanvit secured the optical performance of 2,000,000 cd of floating brightness of 300cd, proving the efficient possibility of introducing the domestic rotary type light source using LED light source.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.4
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• pp.80-91
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• 2002

An on-line ultrasonic detector was developed to continuously monitor the ultrasonic signal due to partial discharge in transformer in service. The on-line ultrasonic detector has a band-pass filter designed to measure only the frequencies from 50 to 300[㎑] of ultrasonic signal, to remove electrical and mechanical noises from outside of the transformer, and tlle ultrasonic sensor contains a pre-amplifier with 60[dB] gain. The ultrasonic signal discrimination algorithm which discriminates the ultrasonic signal duration was developed to remove the ultrasonic signal due to OLTC operation having similar characteristics to those due to partial discharge. The reliability of the on-line ultrasonic detector developed in this study was convinced of measurement the ultrasonic signals from the model. transformer in laboratory and transformer in service.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.6
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• pp.584-591
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• 2000

Power Quality Compensator(PQC) has been installed to protect the sensitive loads against the voltage disturbances, such as voltage sag and interruption. In general, static switch is used for the purpose of link between utility and PQC. So transfer operation of the static switch play a important part in the PQC. Many studies on the structure and control of PQC have been progressed in active, but these researches have been rarely mentioned about any voltage-disturbances-detection method to start the PQC operation. In this paper, a new voltage-disturbances-detection algorithm for computer application loads using the CBEMA/ITIC curve is proposed for transfer operation of the static switch. The proposed detection algorithm is implemented to get fast detecting time through the comparison of instantaneous 3-phase voltage values transferred to DC values in the synchronous reference frame with the operating reference values. To get the robust characteristics against the noise, a first order digital filter is designed. The magnitude falling and phase delay caused by the filter are compensated through the error normalizing and numerical analysis using transfer function, respectively. Finally, the validity of the proposed algorithm is proved by ACSL simulation and experimental results.

• 한국금형공학회:학술대회논문집
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• 2008.06a
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• pp.197-202
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• 2008

With the growth of electrical power needs, demand of the knife-type switches in the distribution boards is increasing. We have developed a knife-type switch which is not currently produced in Korea. The switch was desinged and a comprehensive tooling for it was also accomplished. A total of two sets of injection molds and three sets of press dies were designed and manufactured. The parts for knife switches were produced using the tools. Finally, the parts were assembled together and the switch is now under the test phase.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.1
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• pp.1-7
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• 2016

In this paper, the tunable filter based on high power cavity using mechanical switch for 1.5 GHz band is presented. The LPF is inserted to eliminate the spurious wave, coupler is embeded to extract the output power, and then the tunable filter system is configured using mechanical switch. The LPF obtains attenuation over 40 dB between 4 GHz and 12.75 GHz, Coupler is satisfied with coupling value 40 dB and coupling isolation over 55 dB. The tunable filter system using mechanical switch obtains insertion loss 0.88 dB at bypass mode between 1,495.9 MHz and 1,510. 9 MHz, 3.29 dB at fil mode between 1,495.9 MHz and 1,500.9 MHz. It is also satisfied with output power of 132 W at the center frequency 1,498.4 MHz, and switching time below 10 ms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.9
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• pp.1040-1049
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• 1992

When the model of control object is not described correctly, ambiguity is often expressed by unknown parameter, In a case that this ambiguity satisfies a certain condition of limit, if robust control method is used, even if model is not correctly discribed, control system can be composed. The characteristic of control based on the variable structure theory is that the influence by ambiguity of system eradicates high-gain feedback. Therefore in this paper, VSS indentifier is proposed. Transformation of control input producing control system in sliding mode actually reflects influence of ambiguity unknown parameter of control object. If useful information is out from transformation input by a few times of operation, proper identify mechanism is selected and this information is used, to decide the unknown parameter is possible. So more effective controller was composed by addition of the proposed identifier to the unknown parameter identifier of robot manipulator.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.4
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• pp.278-286
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• 2008

This paper investigates the fault generation type and the cause of output interruptionsin bulky with $30^{\sim}500[KVA]$ double conversion UPS, and proposes the fault detection method to improve the reliability of power supply used in the critical load in industry. Identifies its existing way of detecting a quality of inverter output it to bypass when exceeds its expectation. Under a UPS managing system, when an inner (Power device, Controller, CPU) fault occurs it disrupts the power supply and these occurrences has been verified by the results of experiments and application results. To overcome these problems, the proposed method constructs independently a fault-detection, a bypass-control device and a triple power supply apart from the conventional UPS operation. Also the detection point is changed to the preceding of a circuit breaker, a reference of fault detection is modified to avoid any clash and the breaking equipment is attached to intercept a spread of accident. As a result of applications of these developed systems to 242 UPS which was installed purposefully to the communication power supply, the service errors has not occurred in the UPS for two years since 2006.

• Journal of Satellite, Information and Communications
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• v.5 no.1
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• pp.32-37
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• 2010

The algorithm of multiple channel signal processing requires the flexibility of variable frequency band, efficient allocation of transmission power, and flexible frequency band reallocation to satisfy various service types which requires different transmission rates and frequency band. There are three methods including per-channel approach, multiple tree approach, and block approach performing frequency band reallocation method by channelization and dechannelization in the multiple-channel signal. This paper proposes an improved per-channel approach for converting the frequency band of multiple carrier signals efficiently. The proposed algorithm performs decimation and interpolation using CIC(cascaded integrator comb filter), half-band filter, and FIR filter. In addition, it performs filtering of each sub-channel, and reallocates channel band through FIR low-pass filter in the multiple-channel signal. The computer simulation result shows that the perfect reconstruction of output signal and the flexible frequency band reallocation is performed efficiently by the proposed algorithm.