• Journal of Advanced Navigation Technology
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• v.14 no.3
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• pp.328-335
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• 2010

In this paper, an efficient algorithm and area-efficient hardware architecture have been proposed for $2{\times}2$ MIMO-OFDM based WLAN baseband modem with two transmit and two receive antennas. To enhance the performance of the receiver, the efficient timing synchronization algorithm and symbol detector based on MML algorithm are presented. Also, by sharing the hardware block with multi-stage pipeline structure and using the complex multiplier based on polar-coordinate, the complexity of the proposed architecture is dramatically decreased. The proposed area-efficient hardware design was designed in hardware description language (HDL) and synthesized to gate-level circuits using 0.13um CMOS standard cell library. As a result, the complexity of the proposed modem receiver is reduced by 56% over the conventional architecture.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.68-68
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• 2017

농작업 시에 가장 빈번하게 일어나는 위험한 농기계 관련 사고는 전도사고로 트랙터의 전복이 꼽히고 있다. 따라서 트랙터의 전복을 유발하는 주원인인 무게중심의 측정이 중요시 되고 있다. 지금까지 사용해 왔던 북미와 유럽, 일본 등의 선진 농기계 업체들이 사용하고 있는 트랙터 무게중심 측정방법(ISO 789-6 : OECD code2, 작도법)은 정밀성과 신뢰성이 다소 결여되어 이를 정확히 측정하기 위한 새로운 방법 및 알고리즘의 개발이 시급한 상황이다. 따라서 본 연구에서는 트랙터 무게 중심을 보다 정확히 측정할 수 있는 방법을 개발하고 이를 ISO에 NP(New Proposal)제안 과정을 거쳐 ISO 개정을 위한 기초연구로 수행되었다. 트랙터 무게중심 측정을 위한 ISO 789-6의 경우 작도법으로 시험하도록 되어 있으나, 본 연구에서는 무게중심을 계산할 수 있는 프로그램을 개발하고, 극좌표계산방식으로 측정된 값을 프로그램에 직접 입력하는 방법을 개발하여 신뢰성과 정밀성을 높일 수 있도록 하였다. 프로그램의 개발은 ISO(OECD) 방법에 대해 계산식을 개발하고 4개의 좌표가 교차하는 좌표와, 트랙터 후방을 들어 올렸을 때의 끝점 좌표, 전방을 들어 올렸을 때의 끝점 좌표 등을 구하는 자동 알고리즘을 개발하고, 중심 위치는 시험방법 및 트랙터의 제원에 따른 치수와 중량 데이터를 측정하여 입력하면 자동으로 계산이 되도록 하였다. 본 연구에서 개발한 방법과 기존 ISO 789-6(작도법)을 비교한 결과 보다 신뢰성 있는 결과를 얻을 수 있었으며, 이를 ISO에 NP제안을 위한 합리적인 시험방법임을 알 수 있었다. 개정작업이 완료될 시에 이 방법을 농기계 업체에 보급함으로써 보다 안전한 농기계 설계 및 제작에 기여하고 농민의 안전사고 예방에 기여할 수 있을 것이다.

• The KIPS Transactions:PartB
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• v.19B no.3
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• pp.201-208
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• 2012

Accurately segmenting lumen border in intravascular ultrasound images (IVUS) is very important to study vascular wall architecture for diagnosis of the cardiovascular diseases. After each of IVUS image is transformed to a polar coordinated image, initial points are detected using wavelet transform. Then, lumen border is initialized as the set of important points using non parametric probability density function and smoothing function by removing outlier initial points occurred by noises and artifacts. Finally, polynomial curve fitting is applied to obtain real lumen border using filtered important points. The evaluation of proposed method was performed with related method and the proposed method produced accurate lumen contour detection when compared to another method in most types of IVUS images.

• Journal of Broadcast Engineering
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• v.23 no.5
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• pp.636-641
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• 2018

Recently, the digital signages display not only the rectangular shapes but also the various shapes and sizes. The high-resolution large-screen display monitors have evolved to multi-vision modes in which several screens are connected to one another. In this paper, we present the structure of an atypically shaped signage system in which the ROI changes with the rotation of the multiple displays. The inclination angle of the monitor is calculated by taking the output value of the gyro sensor inter-locked with the Arduino, and an image in which the position of the four corners is varied according to the rotation angle by using the polar coordinate system. In order to display images in the multi-screen environment, multiple displays with a gyro sensor were controlled using serial communication. As the result, we have obtained the flexibly moving monitor systems with associated images fitting in them.

• Journal of the Korean Chemical Society
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• v.23 no.3
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• pp.125-131
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• 1979

A method for calculation of two center overlap integrals for a pair of Slater type orbitals was developed by Mulliken et al. In this method the spherical polar coordinates for a pair of Slater type orbitals located at two different points are required to be transformed into a spheroidal coordinate set for calculation of two center overlap integrals. A new method, the expansion method for spherical harmonics, in which Slater type orbitals, located at two different points, are expressed in a common coordinate system has been applied for computation of two center overlap integrals. The new method for computation of two center overlap integrals is required to translate Slater type orbitals centered at two different points into the reference point for computation of two center overlap integrals. This work has been expanded the expansion method for spherical harmonics for computation of two center overlap integrals to $|3s{\g}$, $|5s{\g}$ and $|5s{\g}$. Master formulas for two center overlap integrals are derived for these orbitals, using the general expansion formulas. The numerical values of the two center overlap integrals evaluated for a hypothetical NO molecule are in agreement with those of the previous works.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.1
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• pp.44-52
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• 2010

In this paper, we propose a novel method for face recognition which uses polar coordinate instead of conventional cartesian coordinate. Among the central area of a face, we select a point as a pole and make a polar image of a face by evenly sampling pixels in each direction of 360 degrees around the pole. By applying conventional feature extraction methods to the polar image, the recognition rates are improved. The polar coordinate delineates near-pole area more vividly than the area far from the pole. In a face, important regions such as eyes, nose and mouth are concentrated on the central part of a face. Therefore, the polar coordinate of a face image can achieve more vivid representation of important facial regions compared to the conventional cartesian coordinate. The proposed polar coordinate transform was applied to Yale and FRGC databases and LDA and NLDA were used to extract features afterwards. The experimental results show that the proposed method performs better than the conventional cartesian images.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.3
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• pp.41-50
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• 2010

In this paper, an area-efficient symbol detector is proposed for MIMO communication systems with two transmit and two receive antennas. The proposed symbol detector can support both the spatial multiplexing mode and spatial diversity mode for MIMO transmission technique, and shows the optimal maximum likelihood (ML) performance. Also, by sharing the hardware block with multi-stage pipeline structure and using the complex multiplier based on polar-coordinate，the complexity of the proposed architecture is dramatically decreased. The proposed symbol detector was designed in hardware description language (HDL) and implemented with Xilinx Virtex-5 FPGA. With the proposed architecture, the number of logic slices for the proposed symbol detection is 52490 and the number of DSP48s (dedicated multiplier) is 52, which are reduced by 35.3% and 85.3%, respectively, compared with the conventional architecture.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.9C
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• pp.729-734
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• 2010

In the initial stage of the communications between a base station and a satellite transponder, the base station transmits the frequency-sweeping un-modulated up-link carrier within a certain frequency range to acquire the doppler frequency shift and signal power between the base station and the satellite in orbital flight. The satellite transponder acquires and tracks the carrier in order to initialize the communication. To control such initialization process, the satellite receiver should analyze the input carrier signal in various ways. This paper presents an SNR estimation algorithm to control the initialization process. The proposed algorithm converts the input signal into the baseband polar coordinate representation and estimates the SNR via the statistics of the angular signal components as well as the status parameters to control the receiver. The Monte-Carlo simulations shows the validity of the estimation proposed.

• Journal of Korean Society of Steel Construction
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• v.22 no.3
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• pp.241-251
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• 2010

This paper presents the development of a new analytical solution to the governing differential equation for isotropic annular sector plates subjected to uniform loading in a three-dimensional polar coordinate system. The 4th order governing partial differential equation (PDE) was converted to an ordinary differential equation (ODE) by assuming the Levy-type series solution form and the subsequent mathematical operations. Finally, a series-type solution was assembled with homogeneous and nonhomogeneous solution parts after operating real values and complex conjugates derived from the characteristic equation. To demonstrate the convergence rate and the accuracy of the featured method, several examples with various sector angles were selected and solved. The deflections and internal moments in the example annular sector plates that were obtained from the proposed solution were compared with those obtained from other analytical studies and numerical analyses using the finite element analysis package program, ABAQUS. Very good agreement with the results of other analytical and numerical methodologies was shown.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.2
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• pp.45-53
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• 2002

This paper presents an algorithm for the appropriate parameter selection of a power system stabilizer and power converters in two-area power systems with a series HVDC links. The method for PSS is one of the classical techniques by allocating properly poly-zero positions to fit as closely as desired the ideal phase lead and by changing the gain to produce a necessary damping torque. Proper parameter of power converters are obtained in order to have sufficient speed and stability margin to cope with changing reference values and disturbances based on the Root-locus technique. The small signal and transient stability studies using the PSS and power converters parameters obtained from these methods show that a natural oscillation frequency of the study case system is adequately damped. The simulation used in the paper was performed by the Power System Toolbox software program based on MATLAB.