• Proceedings of the KSR Conference
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• 1998.11a
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• pp.241-248
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• 1998

The purpose of this study is to evaluate the harmonics generated from Korea High Speed Rail's trainset and to analyze the effect on the KEPCO power system. This study focuses on the test track of the high speed rail and analyzes 154㎸ transmission line, scott transformer, autotransformer and 27,5㎸ line. The trainset is modeled as a harmonic source attached to the catenary line of the test track. Then, harmonic distortion is calculated. This distortion is compared with the KEPCO's regulations in relation to harmonic.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.386-389
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• 2013

In this paper, for signal integrity analysing high-speed signal between a processor and a DDR2 memory, transient analysis is done and eye diagrams are generated using IBIS models of IC chips and S-parameters of transmission line. From the eye diagrams of such high-speed signals as DQ, DQS/DQSb, Clock, Address and Control, signal quality is assured through measuring timing and voltage margins during setup and hold times and verifying that the over-/under-shoot and the cross points of differential signals satisfy their specifications.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.1
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• pp.7-11
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• 2008

A new continuously variable transmission (CVT) for electric bicycles was developed using a traction drive mechanism with inner and outer spherical rotors. This electric bicycle CVT permits three propulsion modes: human-power only, motor-power only, or a combination of motor power and human power. In addition, the electric bicycle CVT has high power efficiency, large torque capacity, improved drivability, and good packageability. A prototype was manufactured based on a conceptual design, a performance analysis, and a detailed design. This prototype has a rated power of 250 W and input motor speed of 20 rad/s for an overall speed ratio in the range 0.3-1.2. A bench test was conducted to measure the power transmission performance of the prototype.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.12
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• pp.54-62
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• 1996

To get the time response characteristics of the hydrostatic transmission, seaborne winch is modelde by using bond graphs. After modeling of its basic elements, it is represented as power flow, and the determination of variable causality. The state equations are derived by using CAMP. As dynamic stabilites and solutions are investigated by perturbation method and direct integration, winch system is stable. Simulations are performed under the conditions of low speed, high speed, and maximum tension. The pressure and flow rate of the hydrostatic transmission have a big overshoot. But when it is comparaed to the empirical data with simulation results, it is similar to each other. When a lead compensator is applied to improve response characteristics of the hydrostatic transmission, rise time and overshoot of the system are improved.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.7
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• pp.923-929
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• 2021

TCP communication and packet communication require transmission control technology to ensure high quality and high reliability. However, in the case of real-time data transmission, an inefficient transmission problem occurs. In order to overcome this problem and transmit the packet reliability, in general, early congestion control using the buffer level as an index was used. Control of the congestion control point and the cancellation point is delayed because the point at which congestion is controlled is based on the buffer level. Therefore, in this paper, not only the buffer level indicator, but also the ideal buffer level, which determines the packet discard probability, is classified so that the transmission rate and buffer level that measure network congestion are close to the level above the optimal setting. As a result, it was shown that the average buffer level can be directly controlled by maintaining the average buffer level by the ideal buffer level set in the experiment to prove the proposed method.

• Journal of electromagnetic engineering and science
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• v.8 no.2
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• pp.41-46
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• 2008

A bandwidth and power efficient high speed ubiquitous sensor network(USN) for realizing a ubiquitous society is a great challenge for researcher community. In this paper we incorporate a cooperative transmission protocol within a special type of multi-code modulation to meet these requirements. Multi-code(Mc) modulation has been developed for high-speed data transmission over wireless channels. We proposed a new class of orthogonal codes for multi-code modulation which is an orthogonal subset of orthogonal codes(OSOC). Our proposed OSOC structure allows us to use only one relay to cooperate M nodes that effectively reduces the bandwidth and power requirement. This protocol is similar to spread-spectrum(SS) technique that can reduce both broad and narrow band jamming.

• ETRI Journal
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• v.36 no.3
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• pp.374-384
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• 2014

To achieve high-speed (giga-bit) connectivity for short-range wireless multimedia applications, the millimeter-wave (mmWave) wireless personal area networks with directional antennas are gaining increased interest. Due to the use of directional antennas and mmWave communications, the probability of non-interfering transmissions increases in a localized region. Network throughput can be increased immensely by the concurrent time allocation of non-interfering transmissions. The problem of finding optimum time allocation for concurrent transmissions is an NP-hard problem. In this paper, we propose two enhanced versions of previously proposed multi-hop concurrent transmission (MHCT) schemes. To increase network capacity, the proposed schemes efficiently make use of the free holes in the time-allocation map of the MHCT scheme; thus, making it more compact.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.131-132
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• 2008

It is necessary to develop a high-speed wireless transmission system, which is able to send medical informations to the emergency medical center during emergency patient transportation. In this research, a system which transmits patient’s vital signs and a real-time audio/video contents of the event has been designed, developed, and the suitability of the system has been verified. Test results indicate that the system is capable of transmitting vital signal data, including 17 numeric data, 12 waveforms and 113 events, reading the affected part by forwarding a $320{\times}240$ pixel image at 2fps. Also, the full-duplex voice transmission of the system at 8bit/64kbps is enough to make stable communication between emergency medical technicians and hospital professionals possible. After numerous hours of driving, the packet loss of patient vital signs is 0.013%.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.731-732
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• 2011

This paper shows a whole noise quality checking system for the new developed 6th speed automatic transmission manufactured in USA. Due to demand for manufacturing of the high NVH quality transmissions in the mass product line, some special checking system called EOL is adapted. This EOL system is using vibration analysis technologies. Through adapting vibration analysis technologies and functions likewise RMS, Crest Factor, Harmonics, Peak, Band, and Order tracking, various noise problems caused by wear, nick, and deformations could be successfully detected and predicted. Therefore, automatic transmissions manufactured in the USA could get high NVH quality.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.8
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• pp.16-25
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• 1994

The prediction of crosstalk in one of important problems in estimating the EMC of a system for high speed digital signal transmission. Crosstalk curves are shown in terms of characteristic impedance of lines spacing between lines and rise time of pulse by using general multiple coupled transmission line equation and harmonic-balance method. The coupled symmetrical two-line on dielectric material epoxy-glass FR 4(${\varepsilon}_r$), is fabricated to measure crosstalk occuring at the near end and far end of the passive line. The inter-line is inserted to reduce crosstalk between two microstrip lines. The simulation results and the measurement results are shown and found to be very close.