• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.5
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• pp.118-125
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• 2008

In this paper, an efficient frequency offset synchronization structure for OFDM(Orthogonal Frequency Division Multiplexing) is proposed. Conventional CORDIC(Coordinate Rotation Digital Computer) algorithm for frequency offset synchronization utilizes two CORDIC hardware i.e., one is vector mode for phase estimation, the other is rotation mode for compensation. But proposed structure utilizes one CORDIC hardware and divider. Through simulation, it is shown that hardware implementation complexity is reduced compared with conventional structures. The Verilog-HDL coding and front-end chip implementation results for the proposed structure show 22.1% gate count reduction comparison with those of the conventional structure.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.1
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• pp.127-136
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• 2002

This papers presents a practical damage detection algorithm based on damage index method that accurately assesses both the location and severity of the localized detriment in a bridge structure using only limited mode shapes. In the algorithm, the ratio of the modal vector sensitivity of an undamaged structure to that of a damaged structure is used as an indicator of damage. However, a difficulty arises when the damaged element is located at a node of mode where the amplitude of medal vector is close to zero, leading the singularity of the ratio (i.e., division-by-zero). This singularity problem is overcome by introducing a parameter denoted a sensitivity filter, a function of mode shape of the structure, in modal vector sensitivity. Using this concept, an improvement can be considerably achieved in the estimation of both degree of severity and location of damage. To verify the proposed algorithm, its numerical implementations are conducted for a simply supported beam and a 2-span continuous beam.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.283-288
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• 2004

In case while modulation index (M) is more than 0.7, the spectrum of motor voltage and current of a conventional two-phase SRP scheme are not reduced considerably. To solve the problems of a conventional two-phase SRP, this paper proposes a two-phase SRP(DZSRP) with double zero vector mode which zero vector is selected as V(111) in case of $M\;\geqq\;0.7$, and zero vector is selected as V(000) if M < 0.7. For the validity of the proposed method, a 16 bit micro-controller C167 was used and the experiments were conducted with the 1.5kw induction motor under load condition. And the experimental results show that the switching noise spectrum for all the M are spread to a wide band area.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.2
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• pp.48-56
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• 2009

We propose a fast intra mode skip decision algorithm for H.264/AVC video encoding. Although newly added MB encoding algorithms based on various prediction methods increase compression ratio, they require a significant increase in the computational complexity because we calculate rate-distortion(RD) cost for all possible MB coding modes and then choose the best one. In this paper, we propose a fast mode decision algorithm based on an adaptive motion vector map(AMVM) method for H.264/AVC video encoding to reduce the processing time for the inter frame. We verify that the proposed algorithm generates generally good performances in PSNR, bit rates, and processing time.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.5
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• pp.507-515
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• 2004

With the advent of fast power devices, the high dv/dt voltage produced by PWM inverts have been found to cause EMI noise, shaft voltage and bearing current. This paper describes the application of newly developed Conducted EMI reduction SVPWM technique in induction motor drives. The newly developed common mode voltage reduction SVPWM technique don't use any zero-vector states for inverter control, hence it can restrict the common mode voltage more than conventional PWM technique. The validity of the proposed technique by software approach is verified through simulation and experimental results.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.106-108
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• 2020

This paper introduces a new pulse-width modulation (PWM) method to reduce common-mode voltages (CMVs) and compare its performance with other reduced CMV-PWM (RCMV-PWM) methods. To avoid the use of zero-vectors which cause high CMV peaks, the introduced method splits every reference vector into two vectors such that the peak-to-peak magnitude of CMV is reduced by one-third of conventional space-vector PWM (SVPWM). The performance of RCMV-PWMs altered by the modulation index are analyzed with simulation results.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.5
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• pp.102-108
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• 2011

Support vector machines are well known for their outstanding performance in pattern recognition fields. One example of their applications is music/speech classification for a standardized codec such as 3GPP2 selectable mode vocoder. In this paper, we propose a novel scheme that improves the speech/music classification of support vector machines based on the second-order conditional maximum a priori. While conventional support vector machine optimization techniques apply during training phase, the proposed technique can be adopted in classification phase. In this regard, the proposed approach can be developed and employed in parallel with conventional optimizations, resulting in synergistic boost in classification performance. According to experimental results, the proposed algorithm shows its compatibility and potential for improving the performance of support vector machines.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.29-30
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• 2015

본 논문에서는 3레벨 인버터의 common mode voltage 변동을 줄여주는 스위칭 방식인 MVPWM(Medium Vector PWM)을 비엔나 정류기에 적용하는 방식을 제안한다. MVPWM은 3개의 상의 reference중의 중간 값일 때의 스위칭 신호를 medium vector가 되도록 바꿔서 3개의 상의 합이 0이 될 수 있게 만들어주므로 인해 common mode voltage변동이 저감된다. 이를 PSIM을 사용하여 모의해석과 실험을 통해 효과를 입증하였다.

• Journal of Broadcast Engineering
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• v.14 no.1
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• pp.59-69
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• 2009

A bi-directional symmetric prediction technique has been developed to improve coding efficiency of B-slice and to reduce the computational complexity required to estimate two motion vectors. On the contrary to the conventional bi-directional mode which encodes both forward and backward motion vectors, it only encodes a single forward motion vector, and the missing backward motion vector is derived in a symmetric way from the forward motion vector using temporal distance between forward/backward reference frames to and from the current B picture. Since the backward motion vector is derived from the forward motion vector, it can halve the computational complexity for motion estimation, and also reduces motion vector data to encode. This technique always derives the backward motion vector from the forward motion vector, however, there are cases when the forward motion vector is better to be derived from the backward motion vector especially in scene changes. In this paper, we generalize the idea of the symmetric coding with forward motion vector coding, and propose a new symmetric coding with backward motion vector coding and adaptive selection between the conventional symmetric mode and the proposed symmetric mode based on rate-distortion optimization.

• Journal of the Korea Society of Computer and Information
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• v.20 no.6
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• pp.87-97
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• 2015

An Aerial video summarization is not only the key to effective browsing video within a limited time, but also an embedded cue to efficiently congregative situation awareness acquired by unmanned aerial vehicle. Different with previous works, we utilize sensor operation mode of unmanned aerial vehicle, which is global, local, and focused surveillance mode in order for accurately summarizing the aerial video considering flight and surveillance/reconnaissance environments. In focused mode, we propose the moving-react tracking method which utilizes the partitioning motion vector and spatiotemporal saliency map to detect and track the interest moving object continuously. In our simulation result, the key frames are correctly detected for aerial video summarization according to the sensor operation mode of aerial vehicle and finally, we verify the efficiency of video summarization using the proposed mothed.