• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.9-12
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• 2002

In this Paper, we propose an efficient de-interlacing algorithm using temporal and spatial domain information. In the proposed scheme, motion estimation is performed same parity fields, i.e., if current field is even field, reference fields are previous even field and forward even field. And then motion vector refinement is performed to improve the accuracy of motion vectors. In the interpolating step, we use median filter to reduce the interpolation error caused by incorrect motion vector. Simulations conducted for various video sequences have shown the efficiency of the proposed interpolator with significant improvement over previous methods in terms of both PSNR and perceived image quality.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.453-454
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• 2006

In this paper, we propose an invertible biometric image watermarking algorithm which can detect block-wise malicious manipulations. The proposed method embeds two types of watermark. The first type can completely remove distortion due to authentication if the data is deemed authentic. The second type can detect block-wise malicious manipulation by applying the parity bits concept to biometric image blocks.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04a
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• pp.373-376
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• 2002

RAID 저장장치는 병렬성과 고 가용성을 추구하는 대용량 저장장치를 구축하는 방법이다. 특히 패리티 디클러스터링을 사용한 RAID 저장장치는 고장이 발생하였을 경우 재구축 작업중에도 사용자의 요청을 처리함에 있어서 성능 저하가 적고 높은 fault tolerance 와 고 가용성을 지원한다. 본 논문에서는 기존의 패리티 디클러스터링 기법과 분산 스페어링 기법을 적용한 RAID 구조에서 올 수 있는 단점을 보완할 수 있는 새로운 분산 스페어 기법을 제안한다. 본 논문에서 제안된 기법은 시뮬레이션을 통해 그 유효성이 입증되었고, 전반적으로 기존의 방식보다 $1%\sim11%$정도 성능이 더 좋음을 알 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.10A
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• pp.1782-1793
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• 2001

터보부호 심벌비트들을 서로 다른 부호율로 반복부호화한 뒤 여러 부채널로 나란히 보내는 터보 부호화 여러반송파 직접수열 부호분할 다중접속 시스템을 제안한다. 레일리 감쇄채널에서 신호대잡음비가 높을 때에는 이 시스템의 성능 한계를 얻었고, 신호대잡음비가 낮아 한계를 적용할 수 없을 때에는 모의실험에서 성능을 살펴보았다. 신호대잡음비가 낮을 때 성능 손실이 조금 있지만 홀짝 검사(parity check) 심벌에 다양성 차수를 크게 주어 오류 마루를 (error floor) 낮출 수 있음을 보였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9C
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• pp.841-847
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• 2009

In this paper we propose a high-performance Hybrid ARQ scheme employing Chase combining based on LDPC (Low-Density Parity-Check) codes. The proposed scheme uses symbol mapping diversity and turbo demodulation to improve decoding performance. We analyze the performance of the proposed scheme by EXIT (EXtrinsic Information Transfer) chart and compare its performance with several symbol mappings.

• ETRI Journal
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• v.37 no.5
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• pp.940-944
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• 2015

We present a frame synchronization algorithm for lowdensity parity-check (LDPC) coded burst transmissions, which combines a conventional pilots-assisted frame synchronization algorithm and a code-aided algorithm based on the mean magnitude of the soft outputs from the LDPC decoder. With moderate computational complexity, the proposed algorithm is more efficient in bandwidth than conventional pilots-assisted algorithms. When compared with other code-aided algorithms, the proposed algorithm offers a better trade-off between complexity and performance. Simulation results in the case of an 8-PSK system with (1944, 972) LDPC code show that the proposed algorithm can achieve a performance equivalent to that of the perfect frame synchronization, with a bandwidth efficiency loss of 0.06 dB due to the use of pilot symbols.

• Journal of Korea Port Economic Association
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• v.19 no.2
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• pp.111-139
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• 2003

In this paper, the unbiasedness hypothesis cannot be rejected for JPY. It means that Japanese forward exchange market is efficient. This implies that there would not be an unusual profit from speculation. However, the unbiasedness hypothesis can be rejected for THB, HKD, IDR. It means that Asian forward exchange market is inefficient. This implies that there would be an unusual profit from all available information. This suggests that forward exchange rates cannot be an unbiased estimator of future spot exchange rate. This result explains that the actual pricing for forward rate is not based on the international financial market's pricing mechanism of interest rate parity theory, but rather depends upon that simple market expectations and aspirations.

• ETRI Journal
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• v.36 no.4
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• pp.591-598
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• 2014

This paper proposes a new min-sum algorithm for low-density parity-check decoding. In this paper, we first define the negative and positive effects of the received signal-to-noise ratio (SNR) in the min-sum decoding algorithm. To improve the performance of error correction by considering the negative and positive effects of the received SNR, the proposed algorithm applies adaptive scaling factors not only to extrinsic information but also to a received log-likelihood ratio. We also propose a combined variable and check node architecture to realize the proposed algorithm with low complexity. The simulation results show that the proposed algorithm achieves up to 0.4 dB coding gain with low complexity compared to existing min-sum-based algorithms.

• International Journal of Control, Automation, and Systems
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• v.5 no.3
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• pp.329-336
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• 2007

This paper considers a fault accommodation problem for inertial navigation systems (INS) that have redundant inertial sensors such as gyroscopes and accelerometers. It is wellknown that the more sensors are used, the smaller the navigation error of INS is, which means that the error covariance of the position estimate becomes less. Thus, when it is decided that double faults occur in the inertial sensors due to fault detection and isolation (FDI), it is necessary to decide whether the faulty sensors should be excluded or not. A new accommodation rule for double faults is proposed based on the error covariance of triad-solution of redundant inertial sensors, which is related to the navigation accuracy of INS. The proposed accommodation rule provides decision rules to determine which sensors should be excluded among faulty sensors. Monte Carlo simulation is performed for dodecahedron configuration, in which case the proposed accommodation rule can be drawn in the decision space of the two-dimensional Cartesian coordinate system.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.28B no.9
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• pp.739-746
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• 1991

This paper develops a modified multilayer perceptron architecture which speeds up learning as well as the net's mapping accuracy. In Phase I, a cluster partitioning algorithm like the Kohonen's self-organizing feature map or the leader clustering algorithm is used as the front end that determines the cluster to which the input data belongs. In Phase II, this cluster selects a subset of the hidden layer nodes that combines the input and outputs nodes into a subnet of the full scale backpropagation network. The proposed net has been applied to two mapping problems, one rather smooth and the other highly nonlinear. Namely, the inverse kinematic problem for a 3-link robot manipulator and the 5-bit parity mapping have been chosen as examples. The results demonstrate the proposed net's superior accuracy and convergence properties over the original backpropagation network or its existing improvement techniques.