• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.6
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• pp.28-34
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• 1993

An algorithm for MMADF(modified multiplication-free adaptive filter) which need not to multiplication arithmatic operation is proposed to improve the performance of FSE (fractionally spaced equalizer) which reduce the ISI(intersymbol interference) in signal transfer channel. The input signals are quantized using DPCM and the reference signals is processed using a first-order linear prediction filter. The convergence properties of Sign. MADF and M-MADF algorithm for updating of the coefficients of a FIR digital filter of the fractionally spaced equalizer (FSE) are investigated and compared with one another. The convergence properties are characterized by the steady state error and the convergence speed. It is shown that the convergence speed of M-MADF is almost same as Sign algorithm and is faster than MADF in the condition of same steady state error. Especially it is very useful for high correlated signals.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.6
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• pp.1017-1022
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• 2020

LTE-R(Long Term Evolution-Railway) for high speed railway system operation as an essential technology is based on LTE. Recently, moving speed of high speed train is on going to 600[km/h] level over commercial speed 400[㎞/h]. LTE-R as communication technology for a high speed railway system can be able to provide seamless communication to support moving speed for high speed railway system. In this study, a handover method based on prediction is suggested and performance of the suggested method is evaluated. Computer simulation based on NS(Network Simulator)-3 is used for this study.

• Journal of information and communication convergence engineering
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• v.8 no.5
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• pp.534-538
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• 2010

Efficient control of a marine engine requires an engine control unit (ECU) system that handles fast and precise signal processes for in-coming and out-going signals from fast running engines. In order to handle these roles, the sequential control has been adapted in the ECU system in small and medium size ship engines, which has caused high production cost and complexity of the system. Hence, this paper is focused on developing an distributed ECU system for high speed and high precision control of a marine engine by efficiently combining a CPLD chip and a microprocessor. By sharing load at the MCU with the designed CPLD chip, we could achieve in driving a marine engine with high speed and precise control so that the ECU board has been simplified and its production cost has been reduced.

• The Journal of Korea Robotics Society
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• v.11 no.3
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• pp.183-192
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• 2016

Generating motion of center of mass for biped robots is a challenging issue since biped robots can easily lose balance due to limited contact area between foot and ground. In this paper, we propose force control method to generate high-speed motion of the center of mass for horizontal direction without losing balancing condition. Contact consistent multi-body dynamics of the robot is used to calculate force for horizontal direction of the center of mass considering balance. The calculated force is applied for acceleration or deceleration of the center of mass to generate high speed motion. The linear inverted pendulum model is used to estimate motion of the center of mass and the estimated motion is used to select either maximum or minimum force to stop at goal position. The proposed method is verified by experiments using 12-DOF torque controlled human sized legged robot.

• International journal of advanced smart convergence
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• v.12 no.4
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• pp.26-34
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• 2023

A high-speed data transmission system is designed for the ground inspection equipment of satellite measurement and control. Based on USB2.0, the system consists of interface chip CY7C68013A, programmable logic processing unit EP4CE30F23C8, analog/digital and digital/analog conversion units. The working principle of data transmission is analyzed, and the system software logic and hardware composition scheme are detailed. The system was utilized to output/capture and store specific data packets. The results show that the high-speed data transmission speed can reach 38MB/s, and the system is effective for satellite test requirements.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.269-276
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• 2009

The local preconditioning method has both robust convergence and accurate solutions by using local flow properties for parameters in the preconditioning matrix. Preconditioning methods have been very effective to low speed inviscid flows. In the viscous and turbulent flows, deterioration of convergence should be overcame on the high aspect ratio grids to get better convergence and accuracy. In the present study, the local time stepping and min-CFL/max-VNN definitions are applied to compare the results and we propose the method that switches between two methods. The min-CFL definition is applied for inviscid flow problems and the min-CFL/max-VNN definition is implemented to viscous and turbulent flow problems.

• International Journal of Railway
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• v.6 no.1
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• pp.26-31
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• 2013

Following the success of the KTX (Korea's first high-speed rail system) with a maximum operating speed of 300 km/h opened in 2004, experts in Korea started a research on the development of key technologies for high-speed rail (HSR) with a top speed of 500 km/h. This paper is a preliminary analysis of the research. It first reviews HSR experiences around the world, in terms of traffic and economic impacts of HSR, and presents a preliminary analysis of 500 km/h HSR in Korea. It is estimated that introduction of 500 km/h HSR with a 54% of travel time reduction will increase HSR passengers to about 9.8 million (about 78% of market share) between Seoul and Busan. It is a 23% of growth compared to the base scenario. Along with conventional rail passengers, air passengers are expected to be significantly impacted by the 500 km/h HSR. As a function of HSR travel time, the estimated market shares of both KTX and 500 km/h HSR compared to air are very comparable with previous international experiences. Based on the forecasted traffic, estimated total benefits are $758 million per year.

• Journal of information and communication convergence engineering
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• v.3 no.4
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• pp.201-204
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• 2005

Twofish is a 128-bit block cipher that accepts a variable-length key up to 256 bits. The cipher is a 16­round Feistel network with a bijective F function made up of four key-dependent 8-by-8-bit S-boxes, a fixed 4­by-4 maximum distance separable matrix over Galois Field$(GF (2^8)$, a pseudo-Hadamard transform, bitwise rotations, and a carefully designed key schedule. In this paper, the Twofish is modeled in VHDL and simulated. Hardware implementation gives much better performance than software-based approaches.

• Journal of the Chungcheong Mathematical Society
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• v.28 no.4
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• pp.575-582
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• 2015

The Newton-Raphson method is used to compute the q-th roots of a p-adic number for a prime number q. The sufficient conditions for the convergence of this method are obtained. The speed of its convergence and the number of iterations to obtain a number of corrected digits in the approximation are calculated.

• 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.