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Bessel-like beam generation by superposing multiple Airy beams.
Hwang, Chi-Young,Kim, Kyoung-Youm,Lee, Byoungho Optical Society of America 2011 Optics express Vol.19 No.8
<P>We propose a way of generating Bessel-like non-diffracting beams based on the superposition of multiple Airy beams. We also demonstrate, through numerical simulations of the propagation dynamics of the Bessel-like beams, that these Bessel-like beams can be modified to show the feature of vortex power flow by controlling the initial positions of each single Airy beam.</P>
Hwang, Chi-Young,Choi, Dawoon,Kim, Kyoung-Youm,Lee, Byoungho Optical Society of America 2010 Optics express Vol.18 No.22
<P>We derive a general form of Airy wave function which satisfies paraxial equation of diffraction. Based on this, we propose a new form of Airy beam, which is composed of two symmetrical Airy beams which accelerate mutually in the opposite directions. This 'dual' Airy beam shows several distinguishing features: it has a symmetric transverse intensity pattern and improved self-regeneration property. In addition, we can easily control the propagation direction. We also propose 'quad' Airy beam, which forms a rectangular shaped optical array of narrow beams that travel along a straight line. We can control its propagation direction without changing transverse intensity patterns. These kinds of superposed optical beams are expected to be useful for various applications with their unique properties.</P>
황기하,양원석,김병호,김홍래 순천향대학교 부설 산업기술연구소 2021 순천향 산업기술연구소논문집 Vol.27 No.2
This paper introduces EMTP, a digital simulation software that can analyze electromagnetic transient of power systems such as failures. Simulation systems are constructed to ensure power supply and reliability in the present era of increasing power demand and pursuing power quality. If an accident actually occurs in a large-scale power system, it causes failures such as power outages and generator load carriers. Continuous research was conducted, such as constructing an analytical model of a circuit breaker using EMTP, reviewing the results obtained from the model, or configuring an EMTP communication simulation.
Neuromorphic Hardware System for Visual Pattern Recognition With Memristor Array and CMOS Neuron
Myonglae Chu,Byoungho Kim,Sangsu Park,Hyunsang Hwang,Moongu Jeon,Byoung Hun Lee,Byung-Geun Lee Institute of Electrical and Electronics Engineers 2015 IEEE transactions on industrial electronics Vol. No.
<P>This paper presents a neuromorphic system for visual pattern recognition realized in hardware. A new learning rule based on modified spike-timing-dependent plasticity is also presented and implemented with passive synaptic devices. The system includes an artificial photoreceptor, a Pr<SUB>0.7</SUB>Ca<SUB>0.3</SUB>MnO<SUB>3</SUB>-based memristor array, and CMOS neurons. The artificial photoreceptor consisting of a CMOS image sensor and a field-programmable gate array converts an image into spike signals, and the memristor array is used to adjust the synaptic weights between the input and output neurons according to the learning rule. A leaky integrate-and-fire model is used for the output neuron that is built together with the image sensor on a single chip. The system has 30 input neurons that are interconnected to 10 output neurons through 300 memristors. Each input neuron corresponding to a pixel in a 5 × 6 pixel image generates voltage pulses according to the pixel value. The voltage pulses are then weighted and integrated by the memristors and the output neurons, respectively, to be compared with a certain threshold voltage above which an output neuron fires. The system has been successfully demonstrated by training and recognizing number images from 0 to 9.</P>
Dynamic Control of Circular Airy Beams With Linear Optical Potentials
Chi-Young Hwang,Kyoung-Youm Kim,Byoungho Lee IEEE 2012 IEEE photonics journal Vol.4 No.1
<P>We investigate the propagation dynamics of radially symmetric, circular Airy beams through a medium having linear optical potentials. On the basis of analytic expressions and numerical calculations, we show that “off-axis” autofocusing can be implemented. We also show that we can shift the field distributions of Bessel-like circular Airy beams transversely via the introduction of appropriate linear potentials. Furthermore, by a suitable choice of initial launch condition, the focal length of the autofocusing beam can be modulated.</P>
Object Tracking using KLT aided Mean-shift Object Tracker (ICCAS 2014)
Sun-Ho Kim,Jungho Kim,Youngbae Hwang,Byoungho choi,Ju Hong Yoon 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10
In this paper, we present a new object tracking algorithm which integrates color-based mean-shift and feature-based optical flow methods. To utilize two approaches in the complimentary manner, we iteratively compute the mean-shift vector based on color histograms and tracked features by KLT. In the experiments, we show the improved performance for partial occlusion and severe appearance changes in the representative benchmark sequences.
Quantification of Stereopsis in Patients with Impaired Binocularity :
Han, Sang Beom,Yang, Hee Kyung,Kim, Jonghyun,Hong, Keehoon,Lee, Byoungho,Hwang, Jeong-Min Ovid Technologies (Wolters Kluwer) - Lippincott Wi 2016 Optometry and vision science Vol.93 No.6
<P>Purpose To quantify stereopsis at distance resulting from binocular fusion in patients with impaired binocular vision using a three-dimensional (3-D) display stereotest. Methods A total of 68 patients (age range, 6 to 85 years) with strabismus (40 esotropes and 28 exotropes) whose stereoacuity could not be measured with the near and distance Randot stereotests were included. Contour-based circles with a wide range of crossed horizontal disparities (2500 to 20 arcsec) displayed on a 3-D monitor were presented to subjects at 3 m. Between the patients who had stereoacuity of at least 2500 arcsec and those with no measurable stereoacuity, parameters including age, sex, best-corrected visual acuity, spherical equivalent refractive error, Worth 4 dot test results, and type and angle of deviation were compared. Results Stereoacuity at distance of 2500 arcsec or better was detected in 25 (63%) of 40 esotropes, and 16 (57%) of 28 exotropes, although stereoacuity of 800 arcsec or better was found only in two (5%) esotropes and one (4%) exotrope. Patients with stereopsis were significantly younger (19.3 16.9 years) than those with no measurable stereopsis (31.5 +/- 26.4 years) (p = 0.040). There were no significant differences in best-corrected visual acuity, presence of amblyopia >20/100, spherical equivalent refractive error, type of deviation, deviation angle, sex, and Worth 4 dot test results between these groups. Conclusions Stereopsis at distance resulting from binocular fusion that cannot be measured with conventional stereoacuity tests may be preserved in patients with impaired binocular vision. The 3-D display stereotest can be useful for quantifying stereopsis at distance resulting from binocular fusion.</P>