• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.6
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• pp.1355-1362
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• 2011

This paper describes a multi-mode LDPC decoder which supports three block lengths(648, 1296, 1944) and four code rates(1/2, 2/3, 3/4, 5/6) of IEEE 802.11n WLAN standard. Our LDPC decoder adopts a block-serial architecture based on min-sum algorithm and layered decoding scheme. A novel way to store check-node values and parity check matrix reduces the sizes of check-node memory and H-ROM. An efficient scheme for check-node memory addressing is used to achieve stall-free read/write operations. The designed LDPC decoder is verified by FPGA implementation, and synthesized with a $0.18-{\mu}m$ CMOS cell library. It has 219,100 gates and 45,036 bits RAM, and the estimated throughput is about 164~212 Mbps at 50 MHz@2.5v.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.38 no.6
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• pp.65-75
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• 2001

We proposed the detection method of pH variations by integrating a photocurrent characteristic curve, instead of finding an inflection point by differentiating it in LAPS system. By a simulation of the performance of the proposed method, we verified that it had 80 and 1000 times higher sensitivity and resolution than a conventional method. Then, with the implemented system based on the simulation results, we measured a pH variation which was given rise to a potential change on the LAPS surface exposed to 2-0.03125[mg/ml] enzyme solutions. As results, we observed that the proposed method has a higher sensitivity and resolution of 3.76-0.08[pH/min] pH variations than 3.79-0.27[pH/min] for conventional method with same samples.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.12
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• pp.1087-1092
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• 2010

A micro 3D-PTV system has been constructed using a single camera system. Two viewing holes were created behind the object lens of the microscopic system to construct a stereoscopic viewing image. A hybrid recursive PTV algorithm was used. A concept of epipolar line was adopted to eliminate many spurious candidates. Three-dimensional velocity vector fields were obtained by calculating the three-dimensional displacements of particles that were identified as being identical. The system consists of a laser light source (Ar-ion, 500 mW), one high-definition camera ($1028{\times}1024$ pixels, 500 fps), a circular plate with two viewing holes, and a host computer. The performance of the developed algorithm was tested using artificial images. The characteristic of the vector recovery ratio was investigated for the particle numbers. A micro backward-facing step channel ($H{\times}h{\times}W:\;36{\mu}m{\times}70{\mu}m{\times}3000{\mu}m$) was measured using the developed measurement system. The results were in good qualitative agreement with other results.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.503-504
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• 2008

최근 정보통신 기술들이 빠르게 발전하고 있다. 다양한 통신 기술들 중에서도 업무의 효율을 높이고자 회사 및 가정, 학교 등에서 자주 사용되고 있는 영상채팅시스템을 구현해보고자 한다. 쿼타임 코덱 중 가장 보편적인 코덱으로 인코딩이 쉽고 저사양의 CPU만으로도 실시간 스트리밍이 가능한 H.263 코덱을 사용하여 영상채팅시스템을 Visual C++로 구현을 하였다. 전송로의 지연을 줄이기 위하여 영상, 음성, 텍스트 등을 압축하고 복원하는 데 걸리는 시간을 최소화기 위하여 데이터의 전송대역폭을 적절히 조절하는 알고리듬을 제안하여 전송지연을 최소화하였다. 또한 P2P 방식을 사용하여 다양한 영상 환경에 대하여 영상 및 텍스트 데이터의 안정성과 화질이 우수함을 보였으며, 실시간 가스안전관리 상담에 이용하여 업무의 효율을 높이고자 한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.2 s.173
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• pp.290-302
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• 2000

In this paper, we study on the identification of discrete-time state-space model for robust control of tandem cold mill, using a MOESP(MIMO output-error state-space model identification) algorithm based on subspace method. It is shown that the identified model is well adapted to input-output data sets, which are obtained from nonlinear mathematical equations of tandem cold mill. Furthermore, deterministic H$\infty$ norm bounds on uncertainties including modeling errors and disturbances are quantitatively identified in the frequency domain. Finally, the results give a basic idea to determine weighting functions included in formulating some robust control problems of tandem cold mill.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.4 s.304
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• pp.133-142
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• 2005

In this paper, two digital video scrambling methods are proposed as simple means of the digital content protection techniques. One is inter block scrambling using motion vector, the other is intra block scrambling using intra prediction mode. The proposed inter block scrambling method distorts the original sequences by swapping horizontal and vertical components of motion vector. This method can be applied on most common video coding techniques such as MPEG-1, 2, 4, H.264, etc. The proposed intra block scrambling method distorts the original sequences by modifying intra prediction mode that is property of H.254 video coding technique. Both methods do not cause my bit rate increase after scrambling. Moreover, they have low complexity because they need only simple operation like XOR. Especially, the proposed intra block scrambling does not distort inter blocks directly. But inter blocks are distorted by error propagation effect as much as intra blocks. This paper introduces two new digital video scrambling method and verifies its effectiveness through simulation.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.565-567
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• 2004

In active noise control (ANC) systems, the convergence behavior of the conventional Filtered-X Least Mean Square (FXLMS) algorithm may be affected by nonlinear distortions in the secondary path (e.g., in the power amplifiers, loudspeakers, transducers, etc.), which may lead to degradation of the error-reduction performance of the ANC systems. In this paper, a stable FXLMS algorithm with fast convergence is proposed to compensate for undesirable nonlinear distortions in the secondary-path of ANC systems by employing the Volterra filtering approach. In particular, the proposed approach is based on the utilization of the conventional P-th order inverse approach to nonlinearity compensation in the secondary path of ANC systems. Finally, the simulation results showed that the proposed approach yields a better convergence behavior In the nonlinear ANC systems than the conventional FXLMS.

• Journal of the Korean Operations Research and Management Science Society
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• v.33 no.2
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• pp.1-16
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• 2008

The purpose of this paper is to propose a new binary classification method for predicting corporate failure based on genetic algorithm, and to validate its prediction power through empirical analysis. Establishing virtual companies representing bankrupt companies and non-bankrupt ones respectively, the proposed method measures the similarity between the virtual companies and the subject for prediction, and classifies the subject into either bankrupt or non-bankrupt one. The values of the classification variables of the virtual companies and the weights of the variables are determined by the proper model to maximize the hit ratio of training data set using genetic algorithm. In order to test the validity of the proposed method, we compare its prediction accuracy with ones of other existing methods such as multi-discriminant analysis, logistic regression, decision tree, and artificial neural network, and it is shown that the binary classification method we propose in this paper can serve as a premising alternative to the existing methods for bankruptcy prediction.

• Journal of computational fluids engineering
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• v.14 no.4
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• pp.31-40
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• 2009

Although optimization by sequentially refining metamodels is known to be computationally very efficient, the metamodel that can be used for this purpose is limited to Kriging method due to the difficulties related with sample points selections. The present study suggests a novel method for sequentially refining metamodels using Pareto Frontiers, which can be used independent of the type of metamodels. It is shown from the examples that the present method yields more accurate metamodels compared with full-factorial optimization and also guarantees global optimum irrespective of the initial conditions. Finally, in order to prove the generality of the present method, it is applied to a 2D transonic airfoil optimization problem, and the successful design results are obtained.

• Journal of Sensor Science and Technology
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• v.7 no.5
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• pp.327-333
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• 1998

A new human sensibility (kansei) meter that can measure human sensibility at the indoor environment is developed in this paper. Four sensors that can measure temperature, humidity, $CO_2$ and $C_4H_{10}$ concentrations are used. Among these sensors, the first three are used to determine the human sensibility. And the last to protect human from the harmful gas. First of all, human sensibilities are defined for each sensor datum, and then those are linearly combined to make a final human sensibility (kansei). The efficiency and usefulness of the meter are verified using a simulator on Windows 95 and a stand-alone system constructed using a microprocessor.