• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.10
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• pp.2411-2429
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• 2013

In this paper, we extend the case of information exchange error mitigation for the distributed orthogonal space-time block code (DOSTBC) for two transmit antennas to distributed quasi-orthogonal space-time block code (DQOSTBC) for four transmit antennas. A rate 1 full-diversity DQOSTBC for four transmit antennas is designed. The code matrix changes according to different information exchange error cases, so full diversity is maintained even if not all information exchange is correct. We also perform analysis of the pairwise error probability. The performance analysis indicates that the proposed rate 1 DQOSTBC outperforms rate 1/2 DOSTBC for four transmit antennas at the same transmission rate, which is confirmed by the simulation results.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.6
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• pp.102-108
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• 2001

This paper addresses an analytical approach to the mechanical error analysis of gear train and tolerance design and manufacture of gear train in restricted space considering motor driving torque, driving system inertia, motor acceleration, motor rotor inertia and friction torque. The gear train is designed to have optimum gear ratio in restricted space and each gear is manufactured to have the lowest weight and each gear tooth is heat-treated to have robustness. Based on the small difference between the mechanical error analysis and measurement, gear train design with optimum gear ratio and restricted space and robustness is proposed.

• Journal of the Korea Institute of Military Science and Technology
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• v.2 no.1
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• pp.132-138
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• 1999

This paper addresses an analytical approach to the mechanical error analysis of gear train and tolerance design and manufacture of gear train in restricted space considering motor driving torque, driving system inertia, motor acceleration, motor rotor inertia and friction torque. The gear train is designed to have optimum gear ratio in restricted space and each gear is manufactured to have the lowest weight and each gear tooth is heat-treated to have robustness. Based on the small difference between the mechanical error analysis and measurement, gear train design with optimum gear ratio and restricted space and robustness is proposed

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.6
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• pp.879-888
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• 1999

A Study on the ARQ scheme of data error control is important for more reliable information transmission. Since performance difference is large by the long transmission delay time in satellite communication, the performances of SR ARQ and conventional type-I hybrid ARQ with fixed code rate are investigated by using the parameters of packet length, channel capacity, BER, and transmission delay time especially. BCH code is used in type-I hybrid ARQ for FEC method. This paper presents the throughput analyses according to such various parameters as BCH code rate, window size, data rate and round-trip delay time. Especially we derive a performance equation of type-I hybrid ARQ with the factor of the transmission delay time using the equation of SAW ARQ. Also, the performance of type-I hybrid ARQ specially considering transmission delay time is analyzed through numerical analysis and computer simulation so we can get a important characteristics variation.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.1
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• pp.130-136
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• 2012

Dynamic as well as static and geometric design parameters such as inertia, tooth profile, backlash and clearance can be directly considered via multi-body dynamic analysis along with contact analysis. However, it is time consuming to use finite elements for the consideration of the tooth flexibility in the multi-body dynamic analysis of gears. A computationally efficient procedure, so called, Gear Stiffness Module, is suggested to resolve this calculation time issue. The characteristics of gear tooth compliance are discussed and rotational stiffness element concept for the Gear Stiffness Module is presented. Transmission error analyses for a spur gear system are carried out to validate the reliability and efficiency of the module. Compared with the finite element model, the Gear Stiffness Module yields considerably similar results and takes only 3% of calculation time.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.10-11
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• 2006

The fault location is obtained from the distance relay that detects the fault of the transmission line. In this time, transmission line crews track down the fault location and the reasons. However, because of having error at the fault location of the distance relay, there is a discordance between real and obtained fault location. As this reason, the inspection time for finding fault location can be longer. In this paper, we proposed the statistical (regression) analysis method based on each type of relay's the historical fault location data and the real fault distance data to improve the problems. With finding the regression equation based on the regression analysis, and putting the relay fault location into that equation, the real fault distance is calculated. As a result of the Prediction fault location, the inspection time of transmission line can be reduced.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4462-4466
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• 2013

In optical system, the signal and additive noise for statistical properties of a variety of ways to evaluate the performance of the system is essential for the optimization. In this paper, performance analysis of spectrum-sliced optical system in the optical pre-amplifier in the receiver the received signal by including the error limits for the bit that is, the bit error rate (BER: Bit Error Rate) required to maintain the average optical power represents the number of photons per bit is included in this paper to digital form, noticeable signal the receiver to calculate the sensitivity of the method for the calculation was performed. The general strength of the transmission of the modulated signal and digital signal transmission was required for the comparison of optical power. As shown in Figure 3, the general strength of the digital signal transmission system for transmitting a modulated signal compared with the case is improved by at least 10dB.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.4
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• pp.129-135
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• 1996

The area of gear vibration and noise, has recently been the focus of many studies. The proper kinematic and geometric design of gears, the mathematical modeling of gear system are essential for a good design. This work present a gear disign for reducing noise, and practical approaches used for machinery noise reduction slong with the summary of methods available for predicting gear noise in terms of the transmis- sion error, and show a comparative study with other methods. A new tooth profile modification is proposed for reducing vibration and noise of involute gears. The method is based on the use of cubic spline curves. The tooth profile is constrained to assume an involute shape during the loaded operation. Thus the new gear profile assures conjugate motion at all points along the line of action. The new profile is found to result in a more uniform static transmission error compared to not only standard involute profile but also modificated profile therby contributing to the improvement of vibration and noise characteristics of the gear.

• International Journal of Automotive Technology
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• v.7 no.4
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• pp.477-483
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• 2006

A vibration model of a helical gear pair for vehicle transmission is developed by considering the elastic deformation of the active teeth and the body to be a rigid. The main source of vibration in a helical gear system which caused by the mass unbalances of rotors and the transmission errors of gearings in mathematically formulated and applied to the analysis of vibration characteristics of geared systems. As an example, a simple geared system containing a helical gearing is considered. The critical speeds are found by the Campbell diagram and compared with the experimental results We expect this developed program to contribute to the reduction of the vibration and noise on vehicle a transmission in the field of both design and manufacturing. In addition, this program can be used as a basic program for CAD/CAM of low-noised gear teeth.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.621-629
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• 2001

In this thesis a wireless data transmission system has been proposed and analysed that uses the multi-carrier technique with the adaptive modulation scheme. In general, the OFDM(Orthogonal Frequency Division Multiplexing) system is assigning a same amount of information to all sub-carriers in a wireless data transmission. In the proposed system, the different amount of information is assigned to each sub-carrier depending on the state of channel and the target probability of error of system. With the proposed scheme, the transmission rate can be maximized with the fixed power and the required power to transmit the information can be minimized with the target probability of error of system.