• Proceedings of the KIEE Conference
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• summer
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• pp.270-272
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• 2004

At the water supply field, high voltage induction motor is main facility of a load equipment. The motor is often out of order and its noise, generated heat, loss etc occurred occasionally. especially, transmission motor for flux control generates an amount of the harmonics then have a bad influence upon the electric power system. In this study, to analyze the total harmonics distortion of the water supply field receiving high voltage, the harmonics measured and analyzed using the PQA(Power quality Analyzer) according to the electric power system and electrical load and the reduction method presented.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.4
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• pp.582-593
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• 1999

This paper presents the design and fabrication of the diplexer for a KOREASAT-III Ka-band satellite transponder. The transmission characteristics of the diplexer is analyzed by calculating the generalized scattering matrix using mode matching method. It is composed of 2 bandpass filters, coupled with H-plane T-junction having symmetrical inductive iris and E-plane metal insert structures. Compared with the size and weight of the Rx and Tx filter loaded with a transponders respectively, those of the diplexer can be effectively reduced. In a high power transmission, the variation of the filter characteristics is minimized by the scheme that irises are extended to the exterior of H-plane of the waveguide. This scheme needs no extra heat sinks for dissipating high power. The diplexer is designed to improve the simplification, durability and reliability by eliminating tuning screws, which have been used to compensate for the characteristics of fabricated filters. The bandpass filters of the diplexer show the insertion loss of less than 1.2 dB and the return loss in excess of 15 dB. The isolations of more than 65 dB have been achieved between Rx and Tx filter.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.8
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• pp.36-44
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• 1999

This paper presents the design and fabrication of the duplexer for a Ka-band satellite transponder which is analyzed transmission characteristics by calculating the generalized scattering matrix using mode matching method. It is composed of 2 bandpass filters, coupled with H-plane T-junction having symmetrical inductive iris and E-plane metal insert structures. Compared with the size and weight of the Rx and Tx filter loaded with a transponders respectively, those of the duplexer can be effectively reduced. In a high power transmission, the variation of the filter characteristics is minimized by the scheme that irises are extended to the exterior of H-plane of the waveguide. This scheme needs no extra heat sinks for dissipating high power. The duplexer is designed to improve the simplification, durability and reliability by eliminating tuning screws, which have been used to compensate for the characteristics of fabricated filters. The bandpass filters of the duplexer show the insertion loss of less than 1.2 dB and the return loss in excess of 15 dB. The isolations of more than 65 dB have been achieved between Rx and Tx filter.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.9 s.240
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• pp.1235-1242
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• 2005

A district heating(DH) system supplies environmentally-friend heat and is appropriate for reduction of energy consumption and/or air pollutions. The DH transmission pipe, composed of supply and return pipes, has been used to transmit the heat and prevent heat loss during transportation. The two types of pipes are operated at a temperature of $75\~115^{\circ}C\;and\;40\~65^{\circ}C$, respectively, with an operating pressure of less than 1.568MPa. The objectives of this paper are to systematize data processing of transition temperature and investigate its effects on fatigue life of DH pipes. For the sake of this, about 5 millions temperature data were measured during one year at ten locations, and then available fatigue lift estimation schemes were examined and applied to quantify the specific thermal fatigue life of each pipe. As a result, a relational database management system as well as reliable fatigue lift evaluation procedures is established for Korean DH pipes. Also, since the prototypal evaluation results satisfied both cycle-based and stress-based fatigue criteria, those can be used as useful information in the future fer optimal design, operation and energy saving via setting of efficient condition and stabilization of water temperature.

• Journal of the Korean Ceramic Society
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• v.41 no.3
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• pp.221-228
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• 2004

Basic properties of artificial lightweight aggregate by using waste dusts and strength properties of LWA concrete were studied. Bulk specific gravity and water absorption of artificial lightweight aggregates varied from 1.4 to 1.7 and 13 to 16%, respectively. Crushing ratio of artificial lightweight aggregate was above 10% higher than that of crushed stone or gravel. As a result of TCLP leaching test, the leaching amount of tested heavy metal element was below the leaching standard of hazardous material. Slump, compressive strength and stress-strain properties of LWA concrete made of artificial lightweight aggregate were tested. Concrete samples derived from LWA substitution ratio of 30 vol% and W/C ratio of 45 wt% showed the best properties overall. Thermal insulation and sound insulation characteristics of light weight concrete panel with the optimum concrete proportion were tested. Average overall heat transmission of 3.293W/㎡$^{\circ}C$ was observed. It was higher by about 15% than those of normal concrete made by crushed stone. Sound transmission loss of 50.9 ㏈ in frequency of 500 ㎐ was observed. It was higher by about 13% than standard transmission loss.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.5
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• pp.169-173
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• 2004

This paper presents the basic application idea of superconductor cable for voltage stability limited power system. In bulk power system, the transfer capability of transmission line is often limited by the voltage stability, and superconductor cable could be one of the countermeasure to enhance heat transfer limit as well as voltage stability limit. Steady state voltage stability approach by P-V curve is used to calculate the maximum transfer capability of initial system and superconductor applied system. IEEE-14 bus system is used to demonstrate its applicability.

• ETRI Journal
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• v.36 no.1
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• pp.116-123
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• 2014

In this paper, a novel unequal broadband out-of-phase power divider (PD) is presented. Double-sided parallel-strip lines (DSPSLs) are employed to achieve an out-of-phase response. Also, an asymmetric dual-band matching structure with two external isolation resistors is utilized to obtain arbitrary unequal power division, in which the resistors are directly grounded for heat sinking. A through ground via (TGV), connecting the top and bottom sides of the DSPSLs, is used to short the isolation components. Additionally, this property can efficiently improve the broadband matching and isolation bandwidths. To investigate the proposed divider in detail, a set of design equations are derived based on the circuit theory and transmission line theory. The theoretical analysis shows that broadband responses can be obtained as proper frequency ratios are adopted. To verify the proposed concept, a sample divider with a power division of 2:1 is demonstrated. The measured results exhibit a broad bandwidth from 1.19 GHz to 2.19 GHz (59.2%) with a return loss better than 10 dB and port isolation of 18 dB.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.321-324
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• 2009

The unpredicted worldwide oil price makes the energy efficiency technology be more importance than any other period. The small cogeneration system is one of the most representative technology among the energy efficiency technologies, and recently, the household cogeneration system has been the center object of attention because of the loss of power transmission and the reasonable energy consumption relative to the household (condensing) boiler producing heat only. A tiny, 1kW of electrical output, gas fueled internal combustion engine cogeneration system was investigated. The electrical efficiency and thermal efficiency of the system were measured. With the emission characteristics, the cogeneration system was analyzed. It was showed the gas engine cogeneration system produced the lowest NOx level compared any other cogeneration system due to the three-way catalyst.

• KIEAE Journal
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• v.9 no.6
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• pp.13-18
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• 2009

Korean traditional houses have been developed in harmony with natural environment and comfortable indoor condition by using the natural resources including building layout, space composition and materials. Originally Korea traditional architectures have used wood lintel constructions and loess walls through the many years. Theses loess have many strength such as highly heat capacity, controling of humidity, a deodorant than any other materials. Nowaday it is recommended to use exterior and interior walls in loess wall to meet the eco-friendly materials to improve our residental environmental. Thus this study aims to research the sound insulation performance of traditional loess brick wall varied with thickness, thermal insulation materials and cavity wall. The sound insulation performance of these loess walls are compared with other masonry wall's and sound insulation performance of th walls were tested in anechoic laboratory to measure the sound transmission loss of these walls. The loess brick wall with 75mm thickness of cavity is shown the sound insulation performance with Rw 57 which is nearly same performances of 1B brick wall and cement 8' block wall, The improving effect of insulation materials is shown in the high frequency bandwidth. Especially, there is improving as much as 11 dB using the extruded poly stylene form(75mm) and poly ethylene film(0.7mm).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.6
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• pp.448-453
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• 2019

This work reports the electrical characteristics of and temperature distribution in chalcogenide phase change memory (PCM) devices that have a self-aligned structure. GST (Ge-Sb-Te) chalcogenide alloy films were formed in a self-aligned manner by interdiffusion between sputter-deposited Ge and $Sb_2Te_3$ films during thermal annealing. A transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDS) analysis demonstrated that the local composition of the GST alloy differed significantly and that a $Ge_2Sb_2Te_5$ intermediate layer was formed near the $Ge/Sb_2Te_3$ interface. The programming current and threshold switching voltage of the PCM device were much smaller than those of a control device; this implies that a phase transition occurred only in the $Ge_2Sb_2Te_5$ intermediate layer and not in the entire thickness of the GST alloy. It was confirmed by computer simulation, that the localized phase transition and heat loss suppression of the GST alloy promoted a temperature rise in the PCM device.