• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.2
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• pp.55-64
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• 2000

In this paper, we propose an efficient datapath placement algorithm to minimize track density. Here, we consider each datapath element as a cluster, and merge the most strongly connected two clusters to a new cluster until only one cluster remains. As nodes in the two clusters to be merged are already linearly ordered respectively, we can merge two clusters with connecting them. The proposed algorithm produces circular linear ordering by connecting starting point and end point of the final cluster, and n different linear ordering by cutting between two contiguous elements of the circular linear ordering. Among the n different linear ordering, the linear ordering to minimize track density is final solution. In this paper, we show and utilize that if two clusters are strongly connected in a graph, the inner product of the corresponding vectors mapped in d-dimensional space using spectral method is maximum. Compared with previous datapath placement algorithm GA/S $A^{［2］}$, the proposed algorithm gives similar results with much less computation time.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.2
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• pp.120-127
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• 2015

In this paper, a linear-array transducer capable of overcoming the faults of a single element and phased array transducers with convex shape for non-destructive ultrasonic testing was designed and fabricated. A 5.5 MHz linear-array transducer was designed using the PiezoCAD program based on the KLM analysis and the PZFlex program based on the FEM analysis. A 2-2 composite structure was employed to achieve broad-band characteristics. A 128 element linear-array transducer was fabricated and its performance was compared with the simulation results. The center frequency of the fabricated transducer was 5.5 MHz and the -6 dB frequency bandwidth was 70 %. Thus, we expect that the designed transducer can provide an effective inner image of the test material during non-destructive ultrasonic testing.

• The Journal of the Acoustical Society of Korea
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• v.18 no.3
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• pp.27-34
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• 1999

This paper proposes an algorithm to design the non-linear array so as to form efficiently the one-shot beam with relatively less sensors for acoustic measurement. In this algorithm, according to the spatial sampling theory the part for high frequency(HF) band has equispaced sensor array and the sensor distances below the HF band are decided as a function of number of HF sensors. As the results of the simulations, the mean and variances of directivity index(DI) of non-linear array which has less sensors are similar to those of linear array. and the DI variation for beam steering angle is very small. And the beam width at -2dB point is 6.8°. Thus it is confirmed that the design algorithm for non-linear array which is proposed to have less sensors can be efficiently used in acoustic measurement.

• Journal of Sensor Science and Technology
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• v.12 no.2
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• pp.79-87
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• 2003

In this paper, we propose a method to obtain a linear characteristic using soft computing for systems which have array sensors of nonlinear characteristics. Also a procedure utilizing the pattern information of array sensors without additional sensors is proposed to reduce disturbance effects. For a typical example, even a single CdS cell for CdS array has nonlinear characteristics. Overall linear characteristic for CdS array is obtained using fuzzy logic for each cell and overlapped portion. In addition, further improvement for linearization is obtained applying genetic algorithms for the parameters of membership functions. Also the effect of disturbing external light changes to the CdS array can be reduced without using any additional sensors for calibration. The proposed method based on fuzzy logic shows improvements for position measurements and disturbance reduction to external light changes due to the fuzziness of the shadow boundary as well as the inherent nonlinearity of the CdS array. This improvement is shown by applying the proposed method to the ball position measurements of a magnetic levitation system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.44-51
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• 2009

The radiation characteristics of a pin array patch antenna phased array are compared to those of a conventional patch antenna phased array. The performance of a pin array patch antenna phased array is much improved than that of a conventional patch antenna phased array because the mutual coupling between the adjacent pin array patch antennas is very small compared to that between the adjacent conventional patch antennas. The radiation characteristics of a pin array patch antenna phased array show the superior performance such as low variation of the gain of the main beam and the side lobe level for the variation of the direction of the main beam.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04a
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• pp.809-811
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• 2003

써픽스 배열은 써픽스 트리와 더불어 바이오인포매틱스(bioinformatics) 등에 널리 사용되는 전체 텍스트(full-text)의 인덱스 자료구조이다. 여러 응용분야에서 처리해야하는 데이터양의 기하급수적인 증가에 따라, 써픽스 배열을 압축하여 저장해야 하는 필요성이 커지고 있다. Grossi와 Vitter는 주어진 스트링의 써픽스 배열이 있을 경우, 작은 저장 공간을 사용하는 압축된 써픽스 배열(compressed suffix arrays)을 정의하였다. 본 논문에서는 주어진 스트링에서 써픽스 배열을 구축할 필요 없이, 직접적으로 압축된 써픽스 배열을 구축하는 선형시간 알고리즘을 제시한다.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.9
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• pp.21-28
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• 1998

In this paper, we propose an efficient linear ordering algorithm, called LIME, for netlist partitioning. LIME incrementally merges two segments which are selected based on the proposed cost function until only one segment remains. The final resultant segment then corresponds to the linear ordering. LIME also runs extremely fast, because it exploits sparsity of netlist. Compared to the earlier work, the proposed algorithm is eight times faster in producing linear ordering and yields an average of 17% improvement for the multi-way scaled cost partitioning.

• The Journal of the Acoustical Society of Korea
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• v.17 no.2
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• pp.32-42
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• 1998

본 논문은 비균일 분포 수동형 견인 배열 센서를 사용하여 입사각 추정은 물론, 도 플러 주파수를 동시에 추정해내기 위한 기법을 제안한다. 균일 선형 센서 배열을 사용하는 전통적인 수동형 견인 센서 배열 처리기법은 센서간의 등 간격 구조 및 단순한 표본 과정에 기인하여 활용 분야의 한계성을 가지며, 주된 응용 분야가 방사된 음향신호의 입사각을 추 정하는데만 국한되어 사용될 수 있다는 문제점을 내포하고 있다. 이러한 사실 때문에, 수중 천해 환경 하에서 견인함의 등속 이동에 의해 발생하는 도플러 주파수들에 대한 정보는 목 표물에 대한 식별이나 음향신호 전달 경로의 모델링에 중요한 매개변수로 작용하며, 일반적 인 수동형 견인 센서 배열의 사용에 의한 처리 방식으로는 이러한 매개변수의 추출이 불가 능하게 된다. 본 논문은 이러한 제한성을 극복하고 방사 신호들의 개별적인 입사각 및 도플 러 주파수의 동시 추정을 가능케하도록 비균일 분포의 선형 센서 배열과 Sample Skipping 기법(Sample Skipping Technique;SST)을 적용한 새로운 형태의 수동형 견인 배열 센서 처 리 기법을 제안한다.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06e
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• pp.151-154
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• 1998

이 논문에서 비선형 배열 MUSIC 빔형성 기법을 이용하여 예인형 선배열 센서 시스템의 표적 좌우 방위 분리 방법을 기술하였다. 이 기법은 배열 운동모델 Water-Pully 모델과 방향센서의 정보를 이용하는 칼만필터를 설계하여 예인함 기동에 따른 배열형상을 추정하고 표적의 좌우방위를 분리하기 위하여 추정된 배열형상에서 MUSIC 빔형성 기법으로 신호처리를 수행하였다. 또한 예인주기와 예인진폭과 같은 예인함 기동형태의 전형적인 빔형성 기법과 MUSIC 빔형성 기법으로 표적의 좌우 방위 분리 성능을 비교 분석하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.304-311
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• 2003

In this paper, we present the 2.4 ㎓ and 5 ㎓ dual band antenna fur access point of WLAN(Wireless Local Area Network). The proposed antenna must have equal gains in both frequency bands to accept two services. We proposed using collinear array to compensate gain difference for two different frequency bands. Simulation results using 3D simulation program, CST MWS(Microwave Studio), for dual band antenna with collinear away show that the maximum gain is about 4.7 dBi at 2.4 ㎓, 5.2 dBi at 5.7 ㎓. We got additional gain of about 2.1 ㏈ with collinear array for 2.4 ㎓ in measurement. Measured results for the dual band antenna with collinear array show applicable performances for access point of wireless LAN.