• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.5
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• pp.33-41
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• 2006

In the modem power distribution systems, there are lots of zero-phase current harmonics in the neutral power line due to much usages of the controlled switching devices, various semiconductor power converting systems, OA(Office Automation) equipments, PC etc. In order to minimize the current harmonics a zero-phase neutral line current eliminating reactor (NHER) is designed and analyzed its performance using the finite element program. For the design of NHER a program is developed using C++ program. To verify the program a case model(380/220[V], 200[A]) is designed and analyzed by the developed program. As the results of the optimal design, the core loss is reduced by 26[%] with eliminating of the current harmonics. Especially the ninth harmonics is much reduced as compared with the others. When the design of NHER is adapted to the load of the power system, the eliminating effect and efficiency of the device will be much better

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.6
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• pp.316-323
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• 2004

This paper develops an ADWHM(Advanced Digital Watt-Hour Meter) which integrates and implements the voltage management data record function and the load management data record function in the electronic watt-hour meter. ADWHM is developed based on PIC16F874 which is 8bit micro-controller of RISK type for the easy of programing and maintenance, and electronic power signal processing module is located at front of it to reduce the computing load of processor. Also, a 16kbyte EEPROM is used to record the voltage management data and load management data for a week as well as watt-hour data and USART communication mode is used to transfer data from ADWHM to PC. The accuracy of the voltage and unt measuring for ADWHM is verified by identifying the LCD display values of the ADWHM after the voltage signals of id levels from digital function generator is applied to PT(Potential Transformer) and CT(Current Transformer) output under state which it is separated from real power line. On the its basic functions such as watt-hour data recording function, voltage management data recording function and load management data recording function was verified by showing data for three days among the collected data to PC by RS232C communication from ADWHM which was connected to real power lines for a week.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.1
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• pp.1-7
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• 2013

This paper analyzes the flashover rate by lightning in Korea distribution system. Because of random characteristics of lightning, the Monte Carlo method is applied to estimate the lightning performance. The magnitude of lightning stroke is based on the curve measured in field. The classification of direct and indirect lightning depends on the striking distance. The striking distance and flashover rate are calculated by using the method based on Central Research Institute of Electric Power Industry(CRIEPI). The distribution system and lightning is modeled by using EMTP and MATLAB, and the accuracy of modeling is discussed. The simulations for the various spacing between two adjacent surge arresters and the various grounding resistance of GW according to the existence of GW are performed and the simulation results are analyzed.

• Journal of the Korean Society of Safety
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• v.12 no.3
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• pp.10-16
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• 1997

The problem of sound radiation from curved beam under the action of harmonic line forces is studied. The reaction due to fluid loading on the vibratory response of the curved beam is taken into account. The curved beam is assumed to occupy the plane y=0. The curved beam material and the elastic foundation are assumed to be lossless including a tension force(T), damping coefficient(C) and stiffness of foundation($k_s$) will be employed. The non-dimensional sound power is derived through integration of the surface intensity distribution over the entire curved beam. The expression for sound power is integrated numerically and the results are examined as a function of wavenumber ratio($\gamma$) and stiffness factor($\psi$).

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.693-696
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• 1999

This paper describes a new voltage recorder for the voltage management of a power distribution line by using a new voltage measurement technique. The RMS(Root Mean Square) voltage measurement for the power line under the assumption of a sinusoidal input voltage is taken by the full-wave rectifier, half-adder utilizing operational amplifier(OP) circuit. A/D converter utilizing a dual slope converter converts an analog voltage signal into a serial pulse. The pulse is counted with a single chip micro-controller, converted with the RMS voltage, and saved into a flash memory. In the last, a new voltage recorder with compact size and multifunction is developed. Also, Voltage Management System that can analyze the stored data via RS-232C cable is developed based on Windows 95 and Visual C++.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1827-1829
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• 1997

In this paper, measurement and analysis of ELF electric and magnetic fields due to a transmission line have been carried out and the power frequency field strength measuring system is designed. In order to evaluate electric and magnetic fields associated with 60 Hz electric power transmission and distribution lines, the actual survey near a transmission tower has been made and analyzed. It may be inferred from these results that the maximum electric and magnetic fields strength in the vicinity of a line tower do not exceed 3.5[kV/m] and 20[${\mu}T$]. The results of the field measurements agree with limits and guidelines recommended by various authorized international institutes.

• IE interfaces
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• v.9 no.3
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• pp.22-33
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• 1996

The KOREASAT satellite, the first Korean commercial communication and broadcasting satellite, has been launched in August 1995, and has started to provide the communication and preliminary broadcasting services, respectively, in March and July 1996. In this paper the network configurations and characteristics of the services which the KOREASAT satellite provides are described. The services, which are provided by the KOREASAT satellite with its twelve communication and four broadcasting transponders, are the direct broadcasting service, the video relay service including the TVRO, SNG and TV/CATV program distribution, the company-wide communication service including VSAT and TSAT, and the other services with the digital line, trunk relay, telephone line, mobile data, music broadcasting services, etc. A communication transponder has the 36MHz bandwidth and 14W output power, and a broadcasting transponder has the 27MHz bandwidth and 12OW output power.

• Journal of the Korean Society of Safety
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• v.32 no.3
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• pp.15-20
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• 2017

This study presented the strength of the materials and parts for smart distribution board fabrication, and developed a work operation process chart for smart distribution board fabrication. This work operation process chart for smart distribution board fabrication complied with SPS-KEMC regulations, and the applicable range and object are less than 1,000 V and 1,000 Hz for the AC distribution board and less than 1,500 V for the DC distribution board. The power supply is 3 phase 4 wires ($3{\Phi}$ 4W), divided into a single phase circuit and a 3 phase circuit. In addition, the circuit was configured so that the leakage current flowing through the distribution line of the load could be monitored in real time by using the sensor module installed at the rear end of the circuit breaker. Therefore, the administrator can easily find the risk factor of the load since engineer can check the leakage current of each distribution line. In addition, if a leakage current greater than standard value flows, it is possible to generate an alarm against a short circuit and cut off the leakage current. The work operation process chart for the smart distribution board fabrication consists of the following steps: raw and subsidiary materials, sheet metal work, tube making, welding, painting, busbar fabrication, assembly and wiring, product inspection, shipment, etc. Moreover, symbols, ${\Delta}$, ${\nabla}$, ${\bigcirc}$, ${\Rightarrow}$, etc. were used according to the type of work and work progress so that workers can easily understand the progress of the work.

• The Journal of the Korea Contents Association
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• v.18 no.5
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• pp.357-366
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• 2018

This study analyzed the factors affecting box office performance of 200 movies released at the Chinese theater in 2015. The results showed that main actor power, online rating, production power, and Chinese film were sighificant factors which influenced box office, while the distribution power, genre, IP utilization and integration of production and distribution were insignificant. These results mean that online marketing factors such as the popularity index of the main actors evaluated on the internet and the online rating are affecting box office performances in Chinese theaters.

• Journal of Power Electronics
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• v.12 no.4
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• pp.567-577
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• 2012

This paper introduces a new scheme to balance the DC bus voltages of a cascaded H-bridge converter which is used as a Distribution Static Synchronous Series Compensator (D-SSSC) in electrical distribution network. The aim of D-SSSC is to control the power flow between two feeders from different substations. As a result of different cell losses and capacitors tolerance the cells DC bus voltage can deviate from their reference values. In the proposed scheme, by individually modifying the reference PWM signal for each cell, an effective balancing procedure is derived. The new balancing procedure needs only the line current sign and is independent of the main control strategy, which controls the total DC bus voltages of cascaded H-bridge. The effect of modulation index variation on the capacitor voltage is analytically derived for the proposed strategy. The proposed method takes advantages of phase shift carrier based modulation and can be applied for a cascaded H-bridge with any number of cells. Also the system is immune to loss of one cell and the presented procedure can keep balancing between the remaining cells. Simulation studies and experimental results validate the effectiveness of the proposed method in the balancing of DC bus voltages.