• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.4
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• pp.102-109
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• 2006

In this paper, the system level EMC radiated emission test results of KoDSat(Korea Demonstration Satellite), its affects upon the Launch vehicle and H/W improving methods regarding its over exceed value of EMC specification are discussed. Regarding its over exceed value, we estimated that DAU of KoDSat generated the exceeded EMC noise source, and these test results were analyzed using the EMC2000 tool to find out how did it affect the FTS(Flight Termination Subsystem) of KSLV-1(Korea Small Launch Vehicle). To diminish the EMC noise source of UHF(430.1Mhz) band level, we redesigned the DAU power board to be applied the various schemes for EMI noise reduction such as grounding, shielding and EMI filtering, and also verified these reworks to analyze its diminishing affects in UHF band level by means of performing the DAU box level EMC test and performing the second KoDSat's system level EMC test.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.12
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• pp.1097-1104
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• 2016

The infrared camera is difficult to satisfy the RE-102 specification of Mil-Std-461. Especially, in the case of UAV electronics, shielded cable is not used, so it is difficult to meet the electromagnetic compatibility standard. In the RE-102 test of the IR camera for UAV, radiated noise exceeding 30 dBuV/m was observed in the range of 50 MHz to 200 MHz. As a result of pcb em scan, peak noise which caused by the harmonic frequency of the digital control signal clock was observed. Radiated noise was reduced by up to 22.9 dBuV/m by applying the spread spectrum clock generator(SSCG) with 3 % down spreading method to the camera control clock.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.2A
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• pp.1-11
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• 2005

S-CDMA is the advanced physical layer modulation techniques of DOCSIS 2.0 specification. S-DMT is another challenging modulation technique for cable modem upstream channel due to the intrinsic robustness for fading and impulse noise. The BER performance of S-DMT and S-CDMA over the mixed channel model of AWGN and impulse noise were evaluated in comparison with TDMA. The mathematical BER derivation and the comparison of those three types of technique were performed based on the ${\varepsilon}-mixture$ non-Gaussian impulse noise model. The results of simulation show good compliance with those of analytic BER derivation. By the results of comparisons, it was verified that the performance of S-CDMA and S-DMT is almost the same, but the performance of S-DMT is far superior to that of TDMA at typical BER range of the practical data communications.

• Journal of Power Electronics
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• v.14 no.1
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• pp.22-29
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• 2014

Current sharing between modules in a converter parallel operation is very important for the reliability of the system. This paper proposes an improved droop method that can effectively improve current sharing accuracy. The proposed method adaptively adjusts the output voltage set-point of each module according to the current set-points. Unlike conventional droop control, modules share a signal line to communicate with each other. Nevertheless, since signals are simple and in digital form, the complexity of the circuitry is much less and noise immunity is much better than those of conventional methods utilizing communication. The operation principle and design procedure of the proposed method are described in detail. Results of the experiment on two boost converters operating in parallel under the specification of a TFT LCD TV panel power supply verify the validity of the proposed scheme.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.5
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• pp.76-82
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• 1999

During operating given working a robot manipulator makes some problems such as the accumulation of the error or the deviation from the command trajectory. These problems are mainly due to the disturbance noise or unmodeled system parameters. To solve these problems most of robot manipulators equip the controller. But if exact controller gains are not seleced we can't decrease the working efficiency(such as compensation about error or deviation) of the robot manipulator. So in this paper we present the controller gain tuning law by which we can find the controller gain which satisfies the per-formance specification of the robot manipulator during working of the robot. The proposed algorithm is derived from the Laypunov direct method. And by the simulation on the 4-axis SCARA type robot(SAMSUNG SM5 Robot) we guarantee the performance of this algorithm.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.11
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• pp.2825-2836
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• 1994

The engineering optimization has been developed for the automatic design of engineering systems. Since the conventional optimum is determined without considering noise factors, applications to practical problems can be limited. Current design practice tends to account for these noises by the specification of closer tolerances or the use of safety factors. However, these approaches may be very expensive. Thus the consideration on the noises of design variables is needed for optimal design. A method is presented to find robust solutions for unconstrained optimization problems. The method is applied to discrete and continuous variables. The orthogonal array is utilized based on the Taguchi concept. Through mathematical proofs and numerical examples, it is verified that solutions from the suggested method are more insensitive than the conventional optimum within the range of variations for design variables.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.1
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• pp.82-95
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• 1992

There is the high interest for sensing of tool wear with the aim of controlling machine tools productivity from the point of view of qualitity. Difficulties in this measurement are also known. This study is on the development of measurement setup for crater wear by CCD image inturning. In this study, the crater wear measurement system consists of the He-Ne gas laser, diffraction grating. CCD camera, noise filter, slit, microcomputer, diverging lens, converging lens and so on. He-Ne laser beam passes through a diverging lens and a diffraction grating is positioned properly. A converging lens focuses so that the interference fringes can be obtained on the crater wear. Performance test revealed that the developed image technique provides precise, absolute tool-wear quantification and reduces human measurement errors. The results obtained are as follows 1. The digitizing of one image requires less than 2ses. 2. It can give detailed information on crater wear with limited times and errors 3. All parameters required by specification are easily obtained for several points of the cutting edge.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.699-702
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• 2005

This study evaluates the properties of porous concrete for pavement according to content of silica fume and steel fiber. The results of the test indicate that in every condition, the void ratio and the coefficient of water permeability of porous concrete for pavement satisfy both the domestic standards and proposition values. Among the properties of strength, the compressive strength satisfies the standards in the specification of KNHC as for every factor of mixture but in the case of the flexural strength, more than $0.6vol.\%$ of steel fiber satisfied the JCI proposition values. The case when silica fume and steel fiber are used simultaneously presents the strongest durability and Noise Reduction Coefficient is 0.48 to prove that it possesses almost $50\%$ sound absorption.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.7
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• pp.18-27
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• 1997

A CMOS 950 MHz frequency synthesizer is designed and fabricated in a 0.8.mu.m standard CMOS process for IS-95-A CDMA mobile communication transceivers To utilize a CMOS ring VCO in a CDMA wireless communication receisver, we employed a QDC (quasi-direct conversion) receiver architecture for CDMA applications. Realized RF frequency synthesizer used as the RF local oscillator for a QDC receiver exhibits a phase noise of -92 dBc/Hz at 885kHz offset from the 950.4 MHz carrier, which complies with IS-95-A CDMA specification. It has a rms jitter of 23.7 ps, and draws 30mA from a 5V supply. Measured I/Q phase error of the 950.4 output signals is 0.7 degree.

• 한국지구물리탐사학회:학술대회논문집
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• 2009.05a
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• pp.67-71
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• 2009

The high resolution seismic data processing essentially requires the latest data processing technology with a system which enables to calculate the large volume of input/output and computing of data. Nowadays, there is a high foreign dependency on the data processing and QC. In this research, The test processing had been carried out to deduce the best suited software by evaluating functionality, usability and user environment. And several attempts are made to select the most appropriated specification of hardware in order to maximize the software efficiency. The results showed that more numbers of multiple and noise were eliminated in existing prestack time migration sections, which effectively enhanced the resolution.