• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.400-403
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• 2009

Current wind turbine units that are used primarily 3Blade type devices or large-scale wind-term capacity of 2MW of 60m~90m Blade diameter is applied. This is not the best suitable design with the designing condition for the special quality of wind condition in the South-West Coastal Areas of Korea where the wind speed frequency of average wind speed and over 10m/s high wind velocity is fairly low. For this matter, in this dissertation, the expecting generation amount of electric power is measured excluding a mechanical moment, considering wind power energy traveling to the Blade when 60m~120m blade is applied, based on 2MW wind generator. Also, we would like to propose the Blade diameter which is fitted by wind condition of South-West Coastal Areas of Korea.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.529-535
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• 2018

The range extender vehicle runs on a mechanism that allows the small power generation engine to start in the most efficient specific operating range to charge the battery and extend the mileage. In this study, we developed a step motor type intake air supply system that replaces existing throttle body system to develop a simple low cost control logic system. The system was applied to the existing base engine, and in order to improve the performance by increasing the amount of intake air, the effect of changing the length of the intake and exhaust manifold was experimentally examined. As a result, the Type B intake air control actuator operated by one step motor showed higher performance than the Type A in all the operation region, but the performance was lower than that of the base engine due to the increase of flow resistance. To improve this, it was confirmed that the engine performance was improved at both speeds of 2200rpm and 4300rpm when the 140mm adapter was installed in the intake manifold and when the newly designed 70mm exhaust manifold was applied. Through this process, high - precision operation control was realized by connecting the generator load to the optimized engine for the range extender electric vehicle. Experimental results showed that the speed change rate was within ${\pm}2.5%$ at 2200rpm in 1st stage and 4300rpm in 2nd stage and the speed follow-up result of 610 rpm/s was obtained when the speed was increased from 2200rpm to 4300rpm.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.319-324
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• 2003

In general industrial rotating machinery is operated under 3,600 rpm as rotating speed and designed to have critical speed that is above operating speed. So, there was no problem to operate rotating machine under critical speed. But nowadays, they should be operated more than the frist critical speed as usual with the trend of high speed, large scale and hish precision in industries. In case of the large rotor assembly as the trend of large scale, using fitting method of disk or cylinder on shaft is rising for the convenience of assembly and cutting down of manufacturing cost. The shrink fitting is used to assemble lamination part on shaft for manufacturing of rotor of motor or generator in many cases and also is widely used for other machinery. In rotating system, which is compose of rotor and bearing, the critical speed is determined from inertia and stiffness for the rotor and bearings. In case of fitting assembly, analysis and design of the rotor is not easy because the rotor stiffness is determined depend on a lot of factors such as shaft material/dimension, disk material/dimension and assembled interference etc. Therefore designer who makes a plan for hish-speed rotating machine should design that the critical speed is located out of operating range, as dangerous factors exist in it. In order to appropriate design, an accurate estimation of stiffness and damping is very important. The stiffness variation depend on fitting interference is a factor that changes critical speed and if it's possible to estimate it, that Is very useful to design rotor-bearing system. In this paper, the natural frequency variation of the rotor depends on fitting interference between basic shaft and cylinder is examined by experimentation. From the result, their correlation is evaluated quantitatively using numerical analysis that is introduced equivalent diameter end the calculation criteria is presented for designer who design fitting assembly to apply with ease for determination of appropriate interference.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.62-65
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• 1998

This paper presents a method and implementation of the parallel distributed sample scrambler(DSS) in the cell-based ATM transmission environment. In the serial processing, it requires very high speed clock because the processing clock of the serial DSS is equal with the data transmission speed. In this paper, we develop a conversion method of the serial SRG(shift register generator) to 8bit parallel realization. In this case, it has a sample data processing problem which is a character of DSS. So, a theory of correction time movement is presented to solve this problem. We has developed a ASIC using this algorithm and verified the recommendation of ITU-T, I.432.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.4
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• pp.582-588
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• 2008

Microgrids are new distribution level power networks that consist of various electronically-interlaced generators and sensitive loads. The important control object of Microgrids is to supply reliable and high-quality power even during the faults or loss of mains(islanding) cases. This paper presents power control methods to coordinate multiple distributed generators(DGs) against abnormal cases such as islanding and load power variations. Using speed-droop and voltage-droop characteristics, multiple distributed generators can share the load power based on locally measured signals without any communications between them. This paper adopts the droop controllers for multiple DG control and improved them by considering the generation speed of distribution level generators. Dynamic response of the proposed control scheme has been investigated under severe operation cases such as islanding and abrupt load changes through PSCAD/EMTDC simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.10
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• pp.1433-1443
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• 1993

DCT(Discrete Cosine Transform) / IDCT(Inverse DCT) is widely used in various image compression and decompression systems as well as in DSP(Digital Signal Processing) applications. Since DCT/ IDCT is one of the most complicated part of the compression system, the performance of the system can be greatly enchanced by improving the speed of DCT/IDCT operation. In this thesis, we designed a DCT/IDCT core processor using module generator technique. By utilizing the partial sum and DA(Distributed Arithmetic) techniques, the DCT/ IDCT core processor is designed within small area. It is also designed to perform the IDCT(Inverse DCT) operation with little additional circuitry. The pipeline structure of the core processor enables the high performance, and the high accuracy of the DCT/IDCT operation is obtained by having fewer rounding stages. The proposed design is independent of design rules, and the number of the input bits and the accuracy of the internal calculation coa be easily adjusted due to the module generator technique. The accuracy of the processor satisfies the specifications in CCITT recommendation H, 261.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.12
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• pp.83-88
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• 2008

The QPP interleaver has been gaining attention since it provides contention-free interleaving functionality for high speed parallel turbo decoders. In this paper we first show that the quadratic term $f_2x^2%K$ of $f(x)=(f_1x+f_2x^2)%K$, the address generating function, is periodic. We then introduce a low-power address generator which utilizes this periodic characteristic. This generator follows the conventional method to generate the interleaving addresses and also to save the quadratic term values during the first half of the first period. The saved values are then reused for generating further interleaved addresses, resulting in reduced number of logical operations. Power consumption is reduced by 27.38% in the design with fixed-K and 5.54% in the design with unfixed-K on average for various values of K, when compared with the traditional designs.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.5
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• pp.56-67
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• 1994

The installation methods of diesel engines in ships would be largely classified into two groups : one is the direct mounting system fixing engine directly into double bottom of the hull, and the other is the resilient mounting system having vibration absorbers between engine and ship body such as rubber plate to prevent shocks or vibration transmission. The direct mounting system is generally used for large-sized low speed diesel engines, because the resilient mounting system has difficulties in reducing the natural frequency of engine itself under normal speed. On the contrary, the resilient mounting system is often used for medium or high speed engines for marine propulsion and generator that have light weight and high revolution speed. Recently, it is even applied to engines having relatively low speed(300-400rpm) for fishing boats. Although many researches for the resilient mounting system have been carried out, many problems in applying these results directly to marine vessels because most of these have been used for automobiles. Up to now we have had to depend on the professional foreign company in design and the supply of parts for the resilient mounting system of marinediesel engines utterly. In preseut study, the exciting forces of engines effecting to resilient mounting were examined, and patterns of vibration and evaluation procedure for force transmission from resilient mounting to the body of hull were established. Also, these results were applied to the analysis of free and forced vibration for the rubber-type resilient mounting systems of marine diesel engines. Besides, after changing the various design parameters, such as locations, angles, dynamic characteristics and the number of resilient mountings, the influences on resilient mounting system were also examined.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.286-289
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• 2008

Wind turbine industry is booming and spending a lot on research for improving the performance of its present machines and increasing their capacity. Wind turbine requires service life of about 20 years and each components of wind turbine requires high durability, because installation and maintenance costs are more expensive than generated electricity by wind-turbine. So the design of wind turbine must be verified in various condition before production step. For this work, high reliability model for analysis is required. Drivetrain model is modeled by multibody dynamic modeling method. The model constituted with rotor blades, hub, main shaft, gear box, high speed shaft and generator. Natural frequency and torsional stiffness of drivetrain are calculated and analyzed.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.977-979
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• 2001

The application of SRM(Switched Reluctance Motor) is dramatically increasing due to a simple mechanical structure, high efficiency and a good high speed characteristics. Generally, turn-off angle of power switch must be limited the demagnetization period. To control high conduction ratio in motor operation and regenerative voltage in the generator operation in the SRM, multi-level voltage control is effective. This paper proposes multi-level inverter to have a maximum conduction ratio of SRM. The proposed method is verified by experiment.