• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.12a
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• pp.25-28
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• 2000

시변 특성을 갖는 무선 채널 환경에서 UEP(Unequal Error Protection) 채널 부호화 방법은 효율적인 정보 전송을 가능케 한다. 본 논문에서는 IP-SCCC (Interleaved Puncturing Serially Concatenated Convolutional Codes)로 CSI(Channel State Information)와 SSI(Source Significance Information)를 이용한 두가지 UEP 채널 부호화 방법을 제안한다. 또한 AWGN(Additive White Gaussian Noise)과 Rayleigh 페이딩이 존재하는 채널을 가정하고 모의 실험을 통해 알고리즘의 우수성을 검증한다.

• Journal of KSNVE
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• v.10 no.1
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• pp.74-81
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• 2000

The vibrational model of a helical gear pair is developed with considering the elastic deformation of the active teeth and the body to be a rigid. The main source of vibration in geared system which has been known to be the gear transmission error is mathematically formulated and used for the analysis of vibrational characteristics of geared system. 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.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.195-198
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• 1997

This paper proposes the effective compensation method of the rotor time constant of induction motor. An indirect vector control method is highly dependent on the motor parameters. To solve the problem of performance degradation due to parameter variation in an indirect vector control of induction motor, we compensate the rotor time constant by current error feedback. The proposed method is a simple on-line rotor time constant compensation method using the information from terminal voltages and currents. As the current error, difference between current command and estimated current, approaches to zero, the value of rotor time constant in an indirect vector controller follows the real value of induction motor. This scheme is valid transient region as well as steady state region regardless of low or high speed. This method is verified by computer simulation. For this, we constructed the simulation model of induction motor, indirect vector controller and current regulated PWM (CRPWM) voltage source inverter (VSI) using SIMULINK in MATLAB.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.1
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• pp.119-126
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• 2000

In constructing the positioning system based on a conventional dead-reckoning for a wheeled vehicle with pneumatic tires, the position estimation error is inevitable as changes of the radius of the wheels depend on live load and variable enviroment. Therefore, this paper proposes the positioning system which can estimate the error source i.e. the vehicle parameter errors, such as the right and left wheel radius error, using gyroscope and ultrasonic sensor and correct the parameter to reduce the dead-reckoned position estimation error. The extended Kalman filter was used as a method for the multisensor data fusion. The simulation to verify the effectiveness of the proposed positioning system is performed.

• Journal of Information Technology Services
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• v.7 no.3
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• pp.271-286
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• 2008

The core of the semantic web is ontology, which supports interoperability among semantic web applications and enables developer to reuse and share domain knowledge. It used a variety of fields such as Information Retrieval, E-commerce, Software Engineering, Artificial Intelligence and Bio-informatics. However, the reality is that various errors might be included in conceptual hierarchy when developing ontologies. Therefore, methodologies and supporting tools are essential to help the developer construct suitable ontologies for the given purposes and to detect and analyze errors in order to verify the inconsistency in the ontologies. In this paper we propose a new approach for ontology error detection based on the Concept Lattices of Formal Concept Analysis. By using the tool that we developed in this research, we can extract core elements from the source code of Ontology and then detect some structural errors based on the concept lattices. The results of this research can be helpful for ontology engineers to support error detection and construction of "well-defined" and "good" ontologies.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.672-672
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• 2011

This study describes the comparison of noise suppression performances at different locations of two error microphones in active noise control (ANC) for outdoor applications. For this study, 12 different locations were predefined to decide best locations for error sensors in terms of suppressing noise. As shown in Fig. 1, the ANC system with one primary loudspeaker, two secondary loudspeakers and two error microphones is operated by a filtered-x LMS (FXLMS) algorithm which is implemented in a TI 6713 DSP board and Realsys 4713 AD/DA Extension board. The noise for the primary source is a typical road noise measured at a highway roadside. The lengths of adaptive filters of W1 and W2 are varied from 32 to 128 respectively. An intensive computer simulation was accomplished before outdoor ANC experiments. It is expected from the simulation results that the ANC performances are very much dependent upon the locations of the two error microphones.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.4
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• pp.261-268
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• 1989

A novel current controlled PWM voltage source type converter and control strategy is proposed that is able to draw nearly sinusoidal current at unity power factor from three phase power lines. Current error vector control scheme is used which has two operating states : low harmonic current content state and quick current response state. The state is changed according to the current error to optimize the steady state and transient state performances. To regulate the dc oupput voltage, the magnitude of the reference current is determined by a controller dc voltage error. The ac input power factor can be controlled with unity, and even leading or lagging by adjusting the relative position of the reference current with respect to the supply voltage.

• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.41-44
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• 2002

In the communications systems with diversity, we are commonly faced on needing of new source coding technique, error resilient coding. The error resilient coding addresses the coding algorithm that has the robustness to unreliability of communications channel. In recent years, many error resilient coding techniques were proposed such as data partitioning, resynchronization, error detection, concealment, reference picture selection and multiple description coding (MDC). In this paper, we proposed an MDC using whitening transform. The conventional MDC using correlating transform is need additional information to decode the image. But, if an image is transformed using the whitening transform, the additional information is not necessary to transform because the coefficients of whitening transform have uni-variance statistics.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.216-219
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• 2003

In this paper, we present performance analysis of an IEEE P802.15.3a high rate wireless personal area network transceiver. This physical layer standard uses QOSK as its sub-channel modulation scheme and orthogonal frequency domain modulation (OFDM) for sub-bands. OFDM is used for each sub-band so that multi-path effects are absorbed by equalizer and guard, and fading can be approximately modeled as additive white Gaussian noise. In multi-band ultra-wideband system, DAC quantization error is important noise source since high resolution conversion cannot be used due to high power consumption. Simulation result shows that, to get 640-Mbps throughput, at least 5-bits precision is necessary to maintain bit-error rate under 10$\^$-2/, which can be lowered, with channel coding, to 10$\^$-6/ that is the bit-error rate required by IEEE 802.15 upper protocol layer, in 4-meter LOS fading channel.

• Proceedings of the Acoustical Society of Korea Conference
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• 1997.06a
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• pp.68-74
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• 1997

Ship radiated noise is an infortant parameter which dtermines Anti Submarine Warfare(ASW) countermeansure or passive Sonar detection and classification performance. Its measurement should be performed under controlled ocean acoustic environment. In data reduction of the measured data from hydrophone array, theeffect fo ambient noise, surface reflection and bottom reflection etc. should be compensated to obtain the source level of the ship radiated noise. This study describes the measurement hydrophone array design criteria based on the analysis of transimission anomaly due to the surface reflection.