• Journal of Welding and Joining
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• v.15 no.6
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• pp.85-95
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• 1997

This study is to investigate the optimum conditions of Nd:YAG laser beam welding for Zircaloy-4 end cap closure by optical fiber transmission. Laser welding parameters which affect the penetration depth and bead width were experimentally examined using the various beam radius by the beam quality analyzer, joint geometries of end cap and the laser parameters which mean pulse width, repetition rate and pulse energy. Also, an optimum welding speed and the effect of assistant gas with varying the flow rate of He were investigated. We found that the laser average power for the end cap welding will be 230W and rotation speed must not exceed 8 RPM, the best position of focus using optical fiber with 600.mu.m will be 2 to 3mm below the surface of the material.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.5
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• pp.110-120
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• 1994

Due to the increasing demands in comfortable drivability, most motor companies are developing their own unique shift controller to suppress the shift shock induced by gear change. For a typical automatic transmission system, the dynamic constraints of friction clutch was clarified for efficient program development and major factors effecting the shift transient was confirmed by simulation study. The MIMO LQG/LTR controller was designed to control the turbine and corresponding gear speed. By establishing the control strategy recalling transient response during shift the speed controller mentioned above was used as an indirect torque controller. Consequently a new concept for a systematic design method of shift controller applicable to wide-varying systems was suggested which is time efficient and cost efficient saving a lot of experimental study.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.8 no.4
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• pp.156-163
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• 1983

A composite DPCM system is designed and implemented for the transmission of a NTSC color TV signal over a 44, 736Mbps channel. It is based on an intra-field fourth-order linear predictor and a nonlinear quantizer of five bits. The predictor preserves both the luminance and the chrominance components through one predictor. To accomodate the speed requirement for real time processing, mainly high speed ECL gates and memory devices are used in the hardware implementation. Experimental results show that this composite DPCM system can be applicable for a practical transmission of color TV signal with CATV quality.

• Journal of KSNVE
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• v.5 no.2
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• pp.183-195
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• 1995

The mathematical model of the gear reductioner which consists which consists of the geared rotor-bearing system containing case is developed, assuming as the lumped parameter system. Constraints for vibration suppresion as well as strength of gear teeth, and shaft and kinematic conditions in gear pairs are considered. To find the design parameters satisfing the proposed constraints, a direct search method modified by the technique of Taguchi's experimental scheduling is used. One and two stepped gear reductioners are designed so that the criticl speeds due to the gear transmission error are moved out of the operating speed range.

• Electronics and Telecommunications Trends
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• v.33 no.2
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• pp.30-38
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• 2018

Wi-Fi is a technology that has become an essential part of our lives, and not simply a convenience. Wi-Fi is mainly used indoors and is evolving in terms of an increase in the transmission speed and expanded coverage. 802.11ac Wi-Fi, operating at 5 GHz, and 802.11ad Wi-Fi, operating at 60 GHz, were standardized in the same year, 2012, as a gigabit-transmission speed Wi-Fi technology. In this article, we examine the current status of the Wi-Fi market trends and present the possibility of the development of 60 GHz Wi-Fi and future market prospects.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.11
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• pp.141-150
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• 2000

Continuously variable transmission(CVT) combined differential gear unit has many advantages, which are the decrease of CVT size, the increase of overall efficiency, the extension of speed ratio range, and the generation of geared neutral. It is known that such CVT can be classified into the input coupled type and the output coupled type according to the coupling location of continuously variable unit(CVU). In this paper, six different configurations of input coupled type CVT combined V-belt CVU and 2K-H I type differential gear unit are proposed. Some useful theoretical formula related to speed ratio, power flow and efficiency are derived and analyzed. The propriety of derived formula and theoretical analysis are proven by various experiments.

• Current Research on Agriculture and Life Sciences
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• v.8
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• pp.107-113
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• 1990

This study was attempted to develop a remote controllable speed sprayer in order to protect an operator from agricultural chemicals. For the purpose of remote controllable transmission was developed by using one chip microcomputer. The following results could be summarized in this study. 1. Remote controllable transmission developed had not made even a single mistake during the test performed 100 times repeat. Thus, it could that this machine was very accurate. 2. One chip microcomputer was made by machine language and its was with in 3 sec's which was the same as human did. 3. One chip microcomputer which was used in the experiment could be widely used to automation of agricultural machinery, since it is smaller and chiper than any other similar ones such as personal computer, lap tap, one board computer. 4. Since, farm tractor has the same type of transmission as this system, it also could be adapted to farm tractors. 5. In this experiment, transmission lever was remote controll were designed to operate simultaneously. Thus, this system developed was more complicate than conventional system. However, by removing this transmission lever and by mounting the remote controll system at the speed sprayer, it would be higher and easier to handle than the conventional one.

• Journal of Digital Convergence
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• v.14 no.10
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• pp.261-269
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• 2016

This paper aims to propose a novel technology of network convergence to provide ultra high speed internet services over CATV networks, by which a CMC(cable modem concentrator) and CM(cable modem) of 1Gbps level are designed. This technology not only lowers the production cost in comparison to the existing bonding technology with DOCSIS specification but also enables the adjustment of data speed based on the channel bandwidth. According to the experiments, when convolutional code rate with 128QAM is changed to 1/2, 2/3, 3/4 and 7/8, the data recorded the maximum transmission speed of up to 299 Mbps at the zero error rate. As the convolutional code rates with 256QAM is increased, it showed 334Mbps at the error rate of $10^{-5}$. Based on the findings of this paper, if we secure the channel bandwidth of 200MHz and adjust the modulation order of QAM and the convolution code rate depending on the channel status, we can get the transmission speed of more than 1Gbps, which is much more competitive in its function and price than the existing technology based on DOCSIS.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.522-525
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• 2007

Frame Synchronization is applied to not only digital data transmission for data synchronization between transmitter and receiver but also data communication with satellite. When satellite image data with high resolution and mass storage is transmitted, hardware frame synchronizer for real-time processing or software frame synchronizer for post-processing is used. In case of hardware, processing with high speed is available but data loss may happen for Search of Frame Synchronization. In case of software, data loss does not happen but speed is relatively slow. In this paper, Pending Buffer concept was proposed to cope with data loss according to processing status of Frame Synchronization. Algorithm to process Frame synchronization with high speed using bit threshold search algorithm with pattern search technique and SIMD is also proposed.

• Journal of Power System Engineering
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• v.6 no.2
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• pp.73-81
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• 2002

In this study, electronically controlled automatic transmission adopted on a subcompact model in the market was modelled, and the driving performances of the transmission were simulated with the models. Kinetic and dynamic models of working components are established. The driving simulation program is developed with those models, and the various driving conditions are analyzed. With the results, the dynamic behaviour of the engine and the automatic transmission is easily understood. Especially, the transient performances of torque converter and clutches are deeply analyzed. Skipping the vehicle road test by using this analyzing tool, we can expect the cost down and the reduction of the development period of automatic transmission.