• Journal of the Semiconductor & Display Technology
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• v.9 no.2
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• pp.11-14
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• 2010

In this paper, an improved binary-CDMA (Code Division Multiple Access) system for high speed multimedia data transmission will be presented. The improved binary CDMA technology will be used in municipal wireless network. The new name of the system is the Guardian system using a binary CDMA technology. The Guardian system can provide high data rate, and improve its throughput by minimizing latency from the limitation of resources of system bus during multimedia data transmission. Finally, we analyze the performance of Guardian modem according to the report of wireless data transmission test.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.503-506
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• 1999

Recently, as increasing population of internet, the larger one of required facts is solution for access speed, that transmission performance. ADSL system can provide the best application to resident in low cost, flexible approach. In this paper, for DMT line code that is one of ADSL modulation/demodulation signal processing methods, transmission performance and characteristic are discussed as studies and analysis through computer simulation using MATLAB. We made results with practising simulation using parameters based on ANSI standard Tl .413 Iusse2.

• Wind and Structures
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• v.34 no.2
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• pp.185-197
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• 2022

This study aimed to analyze the wind-induced mechanical energy (WME) of a proposed super high-rise and long-span transmission tower-line system (SHLTTS), which, in 2021, is the tallest tower-line system with the longest span. Anew index - the WME, accounting for the wind-induced vibration behavior of the whole system rather than the local part, was first proposed. The occurrence of the maximum WME for a transmission tower, with or without conductors, under synoptic winds, was analyzed, and the corresponding formulae were derived based on stochastic vibration theory. Some calculation data, such as the drag coefficient, dynamic parameters, windshielding areas, mass, calculation point coordinates, mode shape and influence function, derived from wind tunnel testing on reducedscale models and finite element software were used in calculating the maximum WME of the transmission tower under three cases. Then, the influence of conductors, wind speed, gradient wind height and wind yaw angle on WME components and the energy transfer relationship between substructures (transmission tower and conductor) were analyzed. The study showed that the presence of conductors increases the WME of transmission towers and changes the proportion of the mean component (MC), background component (BC) and resonant component (RC) for WME; The RC of WME is more susceptible to the wind speed change. Affected by the gradient wind height, the WME components decrease. With the RC decreasing the fastest and the MC decreasing the slowest; The WME reaches the its maximum value at the wind yaw angle of 30°. Due to the influence of three factors, namely: the long span of the conductors, the gradient wind height and the complex geometrical profile, it is important that the tower-line coupling effect, the potential for fatigue damage and the most unfavorable wind yaw angle should be given particular attention in the wind-resistant design of SHLTTSs

• Journal of Digital Convergence
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• v.15 no.2
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• pp.11-25
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• 2017

The primary purpose of this study is to present the fact that high-speed internet service should be designated as universal service because it becomes an indispensible and crucial service in the modern information society but free market system fails to implement universal service of high-speed internet service. To do so, it theoretically analyses previous works related to the issue of high-speed internet service and universal service in a critical point of view and investigates the current situation that high-speed internet service is not designated as universal service. In conclusion, this paper suggests that high-speed internet service should be included in the scope of universal service, in terms of infrastructure and minimum transmission speed, for the development of democracy and the information society.

• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.1
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• pp.43-50
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• 2007

In a high-speed flash style or a pipelining style analog-to-digital converter (A/D converter), the DC reference fluctuation caused by external noises becomes serious, as the sampling frequency is increased. To reduce the fluctuations in conventional A/D converters, capacitors have been simply used, but the layout area was large. Instead of capacitors, a low-noise and small-size DC reference circuit based on transmission gate (TG) is proposed in this paper. In order to verify the proposed technique, we designed and manufactured a 6-bit 2GSPS CMOS A/D converter. The A/D converter is designed with a 0.18um 1-poly 6-metal n-well CMOS technology, and it consumes 145mW at 1.8V power supply. It occupies the chip area of 977um by 1040um. The measured result shows that SNDR is 36.25 dB and INL/DNL is within 0.5LSB, even though the DC reference fluctuation is serious.

• Journal of the Semiconductor & Display Technology
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• v.15 no.2
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• pp.81-86
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• 2016

Moisture vapor transmission rate (MVTR) is an important item for many applications of polymer breathable thin film. To determine the optimum values of the process parameters, it is essential to find their influence on The significance of six important process parameters namely, extruder cylinder temperature, extruder speed, extruder dies temperature, cooling roll temperature, stretching ratio, stretching roll temperature on breathable film strength of polymer extrusion was determined. Moreover, this paper presents the application of Taguchi method and analysis of variance (ANOVA) for maximization of the breathable film MVTR influenced by extrusion parameters. The optimum parameter combination of extrusion process was obtained by using the analysis of signal-to-noise ratio. The conclusion revealed that extruder speed and stretching ratio were the most influential factor on the film strength, respectively. The best results of film MVTR were obtained at higher extruder speed and stretching ratio.

• Journal of Drive and Control
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• v.11 no.1
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• pp.1-7
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• 2014

This paper presents a novel concept of wave energy converter for electric generation from the ocean wave energy. In this paper, a Multi-Point Absorbing Wave Energy Converter, shortened as MPAWEC by using Secondary Control Hydrostatic Transmission (SCHST) was proposed. The power take-off (PTO) system in the proposed MPAWEC includes multi heaving buoys to drive hydraulic pumps placed at different points. The application of SCHST in MPAWEC gives some advantages, such as longevity of hydraulic components; more energy is harvested; the variation of the pressure in the accumulator limited; therefore the accumulator volume is reduced and the output speed is more stable, etc. A PID controller was designed for speed control of the hydraulic motor. The simulation results indicated that the speed of the generator was ensured with the relative error as 0.67%; the efficiency of the proposed system was 71.4%.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.132-138
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• 2000

Complex gear shifting and high speed-reduction ratio reduce the transmission efficiency in power driveline of agricultural tractors. According to a field test, the power transmission efficiency of a tractor in transporting operations was estimated about 70%. However, the actual efficiency was found by the experiment to fluctuate in a range of 56 to 87%. Therefore, the constant efficiency model commonly used for a simulation of power drivelines is not likely to simulate its performance more accurately. In order to predict power transmission efficiency more accurately, a new model was proposed and the new concepts of the maximum efficiency and sticking torque were introduced. The error mean between the measured and the predicted efficiencies was about 2.3% in mean. The new model reflecting the transmission characteristics in the power driveline of tractors could be used to analyze and predict the power transmission performance of tractors more accurately.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.258-264
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• 2004

WLAN technologies enable high-speed data transmission in a small space with relatively low cost and power. There are two main standardizations regarding WLAN; namely, IEEE802.11a and ETSI BRAN. Two standards use a radio frequency of 5 ㎓ band and employs OFDM as a transmission mode. OFDM is known to provide high-frequency efficiency as well as high-speed data transmission. In this paper, We use SPW simulation tool and implement the HIPERLAN/2 system. Based on the HIPERLAN/2 system in the SPW platform, the system performance is analyzed and compared with turbo codes in place of a convolutional coder of the HIPERLAN/2 WLAN system. The simulation results show that the performance with the turbo codes (rate 1/3 and 1/4) at a data rate of 12 Mbps shows 3 ㏈ gain over the system with the convolutional codes. At a data rate of 36 Mbps, the performance with the turbo codes is further improved by approximately 4 ㏈.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.6
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• pp.1060-1068
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• 2002

Compound continuously variable transmission(CVT) mechanisms are proposed, which can offer a backward mode, a geared neutral, an underdrive mode and an overdrive mode. They are composed of a 2K-H I type differential gear unit, a V-belt type continuously variable unit(CVU), a few friction clutches and gears, and not required of a starting device as a torque converter. Compound CVT mechanisms developed here present two distinct operating modes which are a power circulation mode and a power split mode. The transition of two modes takes place at the particular CVU speed ratio. For these CVT mechanisms, performance analysis related to speed ratio, power ratio and efficiency are executed and proven by experimental studies.