• Fire Science and Engineering
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• v.31 no.5
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• pp.53-62
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• 2017

Electric power which is the energy source of economy and industries requires long distance transportation due to regional difference between its production and consumption, and it is supplied through the multi-loop transmission and distribution system. Prior to its actual use, electric power flows through several transformations by voltage transformers in substations depending on the characteristics of each usage, and a transformer has the structure consisting of the main body, winding wire, insulating oil and bushings. A transformer fire that breaks out in substations entails the primary damage that interrupts the power supply to houses and commercial facilities and causes various safety accidents as well as the secondary economic losses. It is considered that causes of such fire include the leak of insulating oil resulting from the destruction of bottom part of bushings, and the chain reaction of fire due to insulating oil that reaches its ignition point within 1 second. The smoke detector and automatic fire extinguishing system are established in order to minimize fire damage, but a difficulty in securing golden time for extinguishing fire due to delay in the operation of detector and release of gas from the extinguishing system has become a problem. Accordingly, this study was carried out according to needs of active mechanism to prevent the spread of fire and block the leak of insulating oil, in accordance with the importance of securing golden time in extinguishing a fire in its early stage. A bushings fireproof structure was developed by applying the high temperature shape retention materials, which are expanded by flame, and mechanical flame cutoff devices. The bushings fireproof structure was installed on the transformer model produced by applying the actual standards of bushings and flange, and the full scale fire test was carried out. It was confirmed that the bushings fireproof structure operated at accurate position and height within 3 seconds from the flame initiation. It is considered that it could block the spread of flame effectively in the event of actual transformer fire.

• Journal of electromagnetic engineering and science
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• v.18 no.3
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• pp.188-198
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• 2018

In this study, we propose an approach for the design and satisfy the requirements of the fabrication of a small, lightweight, reliable, and stable ultra-wideband receiver for millimeter-wave bands and the contents of the approach. In this paper, we designed and fabricated a stable receiver with having low noise figure, flat gain characteristics, and low noise characteristics, suitable for millimeter-wave bands. The method uses the chip-and-wire process for the assembly and operation of a bare MMIC device. In order to compensate for the mismatch between the components used in the receiver, an amplifier, mixer, multiplier, and filter suitable for wideband frequency characteristics were designed and applied to the receiver. To improve the low frequency and narrow bandwidth of existing products, mathematical modeling of the wideband receiver was performed and based on this spurious signals generated from complex local oscillation signals were designed so as not to affect the RF path. In the ultra-wideband receiver, the gain was between 22.2 dB and 28.5 dB at Band A (input frequency, 18-26 GHz) with a flatness of approximately 6.3 dB, while the gain was between 21.9 dB and 26.0 dB at Band B (input frequency, 26-40 GHz) with a flatness of approximately 4.1 dB. The measured value of the noise figure at Band A was 7.92 dB and the maximum value of noise figure, measured at Band B was 8.58 dB. The leakage signal of the local oscillator (LO) was -97.3 dBm and -90 dBm at the 33 GHz and 44 GHz path, respectively. Measurement was made at the 15 GHz IF output of band A (LO, 33 GHz) and the suppression characteristic obtained through the measurement was approximately 30 dBc.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.10
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• pp.2343-2350
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• 2010

In this paper, new smart switch that can monitor and control the power consumption and standby power in real-time by implementing an embedded web-server is proposed. The proposed switch can perform the following functions: measuring the electric power like commercial smart meter product, monitoring the power consumption in real-time in distant places through wire and wireless devices, and finally controlling ON/OFF of each switch. In addition, it also contains auto power-shutoff functions for standy power, overvoltage and overcurrent just like existing power-saving outlet and mulitap. Finally, the proposed smart switch has lower hardware and power consumption than the existing products and can be commercialized as a small-sized product by using exclusive embedded web-server of its own, rather than using PC for monitoring and remote control.

• The KIPS Transactions:PartC
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• v.11C no.2
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• pp.219-228
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• 2004

Wireless LAN(wireless Local Area Network) is constructed network environment by radio in indoors or outdoors environment and that to use electric wave or light instead of wire to client such as PC(Personal Computer), notebook, PDA in hub(Hub) in technological side. Now, among IEEE 802.11 WG(Working Group), there is TGf(Task Group F) that develop standard protocol between AP's(Access Point). In this group, proposed IAPP(Inter Access Point Protocol) to secure interoperability between AP producing in different manufacturer, this offers seamless connectivity between STA by sharing Security Context information or Layer 2 forwarding information between AP without passing through re-authentication process when STAs(Station) move by protocol to secure mobility between AP that differ in equal serve network. In this paper, I wish to suggest method that change avenue of communication of message to block information leakage that can occur at security message or WEP Key transmission between above AP, and uses public key to offer wireless area security little more.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.8
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• pp.1184-1191
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• 2013

Probability of ignition due to arc-fault and energy of the arc-fault for the case of applying serial arc-fault interruption time of 120 V defined in UL 1699 to the voltage of 220 V of domestic condition and also for the case of applying it to the HIV wire type are analyzed. It has been confirmed that when the arc-fault occurs under 5 A, 10 A, and 20 A. Probability of ignition for the three different current conditions is 0.74(74%), 0.48(48%), and 0.32(32%) respectively for respective interruption time within 1 sec, 0.4 sec, and 0.2 sec. We discover that when we apply the same arc interruption time for 120 V defined in UL 1699 to the domestic environment of 220 V. The probability of ignition increases from 1.5% for 120 V condition to as much as 74% for 220 V condition. Conclusively, if we apply the standard for the serial arc-fault interruption time defined in UL 1699 for 120 V to the domestic condition of 220 V, the fire prevention effect of electric fire due to arc-fault equal to that of UL standard of 120 V can not be achieved.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.3
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• pp.32-43
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• 2014

This paper presents the intra capacitance modeling according to the winding method, section bobbin and coil structure for hybrid choke coil capable of the EMI attenuation of broad bands from lower frequency bands to higher frequency bands and high frequency type common-mode choke coil capable of the EMI attenuation of high frequency band used in the EMI Block of LED-TV SMPS. In case of high frequency type CM choke coil, it can be explained the parasitic capacitance of A type and section bobbin type winding methods among them is much smaller than the other. The first resonant frequency of the proposed CM choke coil tends to increase as the parasitic capacitance becomes small and its impedance characteristics also show improved performance as the first resonant frequency increases. In case of hybrid choke coil using rectangular copper wire, it has investigated its parasitic capacitance compared to CM choke coil of conventional toroidal type becomes small. Also it has confirmed through the experiment results that CE margin and RE margin in frequency bands 0.5MHz to 5MHz and 30MHz to 200MHz are respectively 10dB and 15dB greater than that of conventional type in case of one stage EMI filter structure adopting hybrid choke coil compared to two stage EMI Filter structure using two of each CM choke coil used in the lower and higher frequency bands or two of CM choke coil used in only the lower frequency bands. In the future, the hybrid choke coil and CM choke coil of high frequency type show it can be practically used in not only LED/LCD-TV SMPS but also several applications such as LED Lighting, Laptop Adapter, Server Power Supply and so on.

• Journal of the Korea Fashion and Costume Design Association
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• v.22 no.2
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• pp.117-136
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• 2020

The purpose of this study is to analyze changes in high-tech fashion along with the types and characteristics of high-tech fashion that have appeared recently providing diverse material for the fashion field. High-tech fashion requires such research to learn how much distance one has in one's life. It is also meaningful to predict what direction high-tech fashion research may be needed. For research methods, previous research and literary studies were considered and photographs in which high-tech techniques were used were collected using the keyword 'high-tech fashion'. High-tech fashion types can be organized into the four types of luminescent types, mutual interaction types, 3D printing fashion, and virtual fashion. The research results were as follows. First, luminescent fashion was an important expression method of high-tech fashion. Materials for luminescent fashion first started with LED electric wire connections and many methods have been attempted with the appearance of electrically conductive clothing material, such as luminescent lasers and beam projectors. Second, interactive high-tech fashion often appears as variable fashion. The work of Hussein Chalayan, which was combined with advanced technology, set up a base for variable type interactive high-tech fashion in the 2000s. As bioengineering technology has developed, fashion that interacts with the environment without an energy source has appeared and the interaction among fashion, people, and the environment can be seen. Third, diverse forms of expressiveness in virtual reality such as 3D CLO shows a great difference with past high-tech fashion. Simple and diverse attempts made through virtual fittings reduce the limitations of time and space, permit interaction, and add a sense of reality through speed and dynamic physical beauty. Fourth, 3D printed fashion expresses complex and detailed clothing material that is different from those before with the development of computer 3D modeling technology. Modeling that can imitate geometric and bio-engineered structures is possible and mysterious feelings are passed on to people through creative expressions.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.5
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• pp.536-541
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• 2015

Copper has been used extensively as an electric wire or as a base material in various types of machineries owing to its good electrical and thermal conductivity and good fabricating property, as well as its good corrosion resistance compared to iron. Furthermore, the copper-nickel alloy has significant corrosion resistance in severely corrosive environments. Although, cupro-nickel alloy shows better corrosion resistance than the brass and bronze series, this alloy also corroded in severely corrosive environments, including aggressive chloride ions, dissolved oxygen, and condition of fast flowing seawater. In this study, and annealing treatment at various annealing temperatures was carried out on the cupro-nickel (Cu-10%Ni) alloy, and the effects of annealing were investigated using electrochemical methods, such as measuring the polarization and impedance behaviors under flowing seawater conditions. The corrosion resistance increased by annealing compared to non heat treatment in the absence of flowing seawater. In particular, the sample annealed at $200^{\circ}C$ exhibited the best corrosion resistance. The impedance in the presence of flowing seawater showed higher values than in the absence of flowing seawater. Furthermore, the highest impedances was observed in the sample annealed at $800^{\circ}C$, irrespective of the present of flowing seawater. Consequently, the corrosion resistance of cupro-nickel (Cu-10%Ni) alloy in a severely corrosive environment can be improved somewhat by annealing.

• Journal of Preventive Medicine and Public Health
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• v.21 no.2 s.24
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• pp.238-244
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• 1988

This study was conducted to investigate the causes of burn and emergency cares taken on the spot for the burn patient. Study population included 161 burn patients admitted to 2 university hospitals and 1 general hospital in Taegu from November 1, 1987 to April 30, 1988. Patients or guardians were interviewed with a structured questionnare. Out of 161 burn patients 111(68.9%)were males and 50(31.1%) females. Preschool children of 1-4 years old accounted for 29.8% of the total patients. Burns of children under 15 years of age took place at home in 91.0%, while 48.3% of burns of adult (15 years and over)males occurred at the working place, and 68.0% of adult females occurred at the home. Out of total burns occurred at home 39.8% took place at kitchen/dining room and 24.1% in the room. The most common cause of burns in children was the boiling water or hot food (74.3%). In adults the common causes were electrical burn(22.4%), hot water or food(19.0%) and explosion(12.1%) for males, and hot water or food(32.0%) and explosion (20.0%) for females. Common emergency cares for the burn taken on the spot were undressing(64.6%), pouring Soju(liquor)(13.7%), and pouring cold water(5.0%). There were a few cases who applied ash, soy or salt. To prevent burn, it is recommended to remodel the traditional kitchen and coal-briquet hole, to strengthen the safety control of LP Gas and LN Gas supply, to educate the public for the handling method for such gases, to strengthen the occupational safety control, to improve the safety device for the electric wire and socket, and to limit the temperature of hot water at home and public baths.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.8
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• pp.790-796
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• 2011

The system which is exposed in the impact range of High-altitude Electromagnetic Pulse(HEMP) may get serious damage because HEMP has a very large electric field value, a very fast rise-time, and so on. Electromagnetic analysis should be performed for signals coupled to the opening or cables of the system prior to derive the system design specifications in order to protect the system against HEMP adequately. In this paper, we analyzed the HEMP coupled signals for the coaxial cable which is generally used to transmit and receive video or RF signals and compared the coupled signal of the one wire with that of the inner conductor of a coaxial cable to confirm the decreased effect of HEMP by the shield. The coaxial cable is analyzed by the external and internal region of the shield separately. For the external region of the coaxial cable, general scattered equation was applied to calculate currents on the surface of the shield and for internal region of the coaxial cable, chain matrix algorithm is used. To verify this paper the analyzed results were compared the results of the existing paper and the two results have good agreements.