• KIEE International Transactions on Power Engineering
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• v.3A no.4
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• pp.191-197
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• 2003

Accurate detection and classification of faults on transmission lines is vitally important. In this respect, many different types of faults occur, such as inter alia low impedance faults (LIF) and high impedance faults (HIF). The latter in particular pose difficulties for the commonly employed conventional overcurrent and distance relays, and if undetected, can cause damage to expensive equipment, threaten life and cause fire hazards. Although HIFs are far less common than LIFs, it is imperative that any protection device should be able to satisfactorily deal with both HIFs and LIFs. Because of the randomness and asymmetric characteristics of HIFs, their modeling is difficult and numerous papers relating to various HIF models have been published. In this paper, the model of HIFs in transmission lines is accomplished using the characteristics of a ZnO arrester, which is then implemented within the overall transmission system model based on the electromagnetic transients program (EMTP). This paper proposes an algorithm for fault detection and classification for both LIFs and HIFs using Adaptive Network-based Fuzzy Inference System (ANFIS). The inputs into ANFIS are current signals only based on Root-Mean-Square (RMS) values of 3-phase currents and zero sequence current. The performance of the proposed algorithm is tested on a typical 154 kV Korean transmission line system under various fault conditions. Test results demonstrate that the ANFIS can detect and classify faults including LIFs and HIFs accurately within half a cycle.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.9
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• pp.22-32
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• 1997

This paper proposes an imprecise compuitation model for DCT considering QOS of images and a two dimensional DCT architecture for imprecise computations. In case that many processes are scheduling in a hard real time system, the system resources are shared among them. Thus all processes can not be allocated enough system resources (such as processing power and communication bandwidth). The imprecise computtion model can be used to provide scheduling flexibility and various QOS(quality of service)levels, to enhance fault tolerance, and to ensure service continuity in rela time systems. The DCT(discrete cosine transform) is known as one of popular image data compression techniques and adopted in JPEG and MPEG algorithms since the DCT can remove the spatial redundancy of 2-D image data efficiently. Even though many commercial data compression VLSI chips include the DCST hardware, the DCT computation is still a very time-consuming process and a lot of hardware resources are required for the DCT implementation. In this paper the DCT procedure is re-analyzed to fit to imprecise computation model. The test image is simulated on teh base of this model, and the computation time and the quality of restored image are studied. The row-column algorithm is used ot fit the proposed imprecise computation DCT which supports pipeline operatiions by pixel unit, various QOS levels and low speed stroage devices. The architecture has reduced I/O bandwidth which could make its implementation feasible in VLSI. The architecture is proved using a VHDL simulator in architecture level.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.1
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• pp.36-42
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• 1996

In general, EMI(electromagnetic interference) from EHV(extra high voltage) power lines above 50kV cause interference to AM radio and low VHF television reception. This paper describes the results of long-term measurement of RI and TV1 in 765kV, double circule of $6\times29.59mm$(1.65k inches) diammer $480mm^{2}$(Rail) ACSR conductors in suitable for 766kV transmission lines to provide acceptable EMI at 15m fro the beneath of outmost phase.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.4
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• pp.409-416
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• 2009

Standard procedures for a fracture toughness testing require very severe restrictions for the specimen geometry to eliminate a size effect on the measured properties. Therefore, the used standard fracture toughness data results in the integrity assessment being irrationally conservative. However, a realistic fracture in general structures, such as in nuclear power plants, may develop under the low constraint condition of a large scale yielding with a shallow surface crack. In this paper, cleavage fracture toughness tests have been made on side-grooved PCVN (precracked charpy V-notch) type specimens (10 by 10 by 55 mm) with various crack depths. The constraint effects on the crack depth ratios were evaluated quantitatively by the developed scaling method using the 3-D finite element method. After the fracture toughness correction from scaling model, the statistical size effects were also corrected according to the standard ASTM E 1921 procedure. The results were evaluated through a comparison with the $T_0$ of the standard CT specimen. The corrected $T_0$ for all of the PCVN specimens showed a good agreement to within $5.4^{\circ}C$ regardless of the crack depth, while the averaged PCVN $T_0$ was $13.4^{\circ}C$ higher than the real CT test results.

• The Journal of the Acoustical Society of Korea
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• v.20 no.8
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• pp.19-23
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• 2001

DSP-based implementation is pervasive in wireless communication parts for systems and handsets according to developing high-speed and low-power programmable Digital Signal Processor (DSP). In this paper, we present a real-time implementation of multi-channel Adaptive Multi-rate (AMR) speech coder. The real-time implementation of an AMR algorithm is achieved using 32-bit fixed-point TMS320C6202 DSP chip that operates at 250 MHz. We performed cross compile, linear assembly optimization and TMS320C62xx assembly optimization for real-time implementation. Furthermore, speech data input/output function and communication function with external CPU is included in an AMR speech coder. The AMR Speech coder developed using DSP EVM board was evaluated in ETRI IMT-2000 Test-bed system.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.1
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• pp.93-98
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• 2010

In this paper, PLC which can be installed easily and is stable to transfer datum, is tested for approving its application in a real ship. Internet access service, CCTV monitoring, light control and huge sensor communications are needed for enhancing the convenience and safety of passengers and crew in ships. In order to apply PLC in ships, we surveyed some noises interrupting PLC in ships and investigated the PLC characteristics. The Hannara, a training ship of Korea Maritime University, was used for the test. We measured and analyzed blocking noises using by NI's SCXI-1001. When noises of specific frequency band occurred near the PLC frequency band, PLC transfer capacity was low for mass datum. We developed and verified some methods to apply PLC in a ship under lots of noises.

• Journal of Korean society of Dental Hygiene
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• v.13 no.6
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• pp.1023-1030
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• 2013

Objectives : The purpose of the study is to investigate the relationship between variables associated with oral health status in psychiatric patients and to provide basic information on oral health education program development for the psychiatric patients. Methods : Subjects were 151 psychiatric patients who filled out the structured questionnaire. The data were analyzed for independent t-test, one-way ANOVA and hierarchical multiple regression by using SPSS Win Program 18.0 version. Results : Higher DMFT index was shown in the older age(p<0.001) and low perceived oral health group(p<0.001). Higher DMFT index included no tooth brushing after breakfast(p=0.045), wrong tooth brushing method(p<0.001). Chewing discomfort(p=0.027) and denture(p=0.027) were closely related to higher DMFT index. Bread(p=0.033) and snack(p<0.001) increased DMFT index. Factors affecting oral health status were age, denture, snack and bread. The explanation power of the final model was 29.4%. Conclusions : Dietary control for the psychiatric patients is very important to prevent dental caries. Tooth brushing and use of oral hygiene devices can improve good oral health care. Furthermore, this result can improve the oral health care for the disabled people.

• Journal of the Korean Society of Industry Convergence
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• v.10 no.2
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• pp.115-122
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• 2007

The MPC(Moisture Protected Computer) system is completely unique. It was recently invented in Korea and it is a technological break-through in the field of computer systems. It will be instrumental in the development of a complete moisture air-tight capability and will work well in field environments. The MPC includes the following: 1) An enclosed design. 2) Moisture proof computer enclosure joints. 3) System dust protection & an impact buffing system. 4) A normal temperature maintenance system when the temperature inside the computer is low. 5) The ability to generate heat and a radiate system inside the computer 6) An automatic power input sensing controller device. 7) A safety device in case of mis-operation. 8) A proper admission procedure for various tests. Because of the above, and as a result of temperature property experiments, there aren't any operational problems. The result of this treatise could provide very important data for verification of cases involving: using strong materials to protect against explosions, searching for ways to make the size and weight small, and for making repairs easier. As a result, it could achieve price and function competitiveness in advanced countries such as the USA and in Europe.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1864-1866
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• 1996

Grounding is the art of making an electrical connection to the earth. In order to protect man, electrical and/or electric equipments from the lightning strokes, all the energy of lightning strokes must be diverted via a safe path to earth. It is essential to the transient grounding resistance against lightning strokes. In this paper, measurements and analyses of grounding surge impedance have been investigated. For measurements of grounding surge impedance the pulse generator was designed and fabricated. The pulse generator has rise time of 22.4 ns and pulse duration of $8\;{\mu}s$. The transient grounding resistance has been measuring by injecting low power and step current between the earthing system under test and a remote reference earth and measuring the potential rise caused by this current. As a result, the transient grounding resistance against lightning surge in the short time domain is much higher than steady state grounding resistance.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.193-201
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• 2013

Propeller is an important component of Human Powered Aircraft (HPA) propulsion system. HPA uses large diameter low rotational speed propeller to get high propeller efficiency. The propeller was designed by HPA propeller designing program. The propeller pitch is adjustable by rotating the blade axis angle at ground. Performance of the propeller for various parameters are analysed by the same program used for design. Off-design condition performance was also checked including pilot power change and flight speed change. The propeller was manufactured in ultra-light structure using carbon composite material down to 950g. The propeller was ground tested on ironbird and installed on KARI HPA. Finally the HPA flew 291m with this propeller.