• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.872-878
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• 2003

In this paper, we developed a simulator which can generate the polarization waves for the indoor wireless communications based on three dimensional ray tracing technique and verified the simulation results comparing with the measured data in indoor wireless propagation environments. Using the developed simulator, we analyzed the channel characteristic and polarization diversity reception characteristic for the vertical, horizontal and circularly polarized waves. From the analysis results, in the case of using circularly polarized wave it can be clearly seen that the multipath fading is markedly reduced compared to the vertical and horizontal polarized waves due to the reception characteristic of removing the odd time reflected waves.

• The KIPS Transactions:PartC
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• v.9C no.3
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• pp.367-374
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• 2002

IPsec offers not odd Internet security service such as Internet secure communication and authentication but also the safe key exchange and anti-replay attack mechanism. Recently IPsec is implemented on the various operating systems. But there is no existing tool that checks the servers, which provide IPsec services, work properly and provide their network security services well. In this paper, we design and implement the rule based security evaluation system for IPsec engine. This system operated on Windows and UNX platform. We developed the system using Java and C language.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.213-215
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• 2005

본 논문의 목표는 일체형 디지털 방송 과 데이터 방송 그리고 아날로그 방송을 수신할 수 있는 일체형 디지털 방송 수신기 구현과 일체형 디지털 방송 수신기에서 아날로그 방송과 영상을 입력 받았을때 화질저하의 원인이되는 De-interlace 알고리즘과3-D Noise를 적절하게 제거할 수 있는 알고리즘에 관한 연구가 목표이다. 또한, 디지털 방송의 수신된 컨텐츠를 다른 저장매체로 불법적으로 복사, 재생을 막기 위한 디지털 컨텐츠 복사를 방지할 수 있는 알고리즘에 관한 연구이다. 현재, 우리나라에서는 기존의 아날로그 방송과 고품질 디지털 방송 서비스을 위한 디지털 방송이 시험적으로 실시되고 있는 상황이다. 이러한 환경하에서 디지털 방송 수신만을 위한 수신기는 아직 시기상조이며, 아날로그 방송과 디지털 방송을 동시에 수신할 수 있근 일체형 수신기가 필요하다. 일체형 수신기에서 가장 문제가 되는 부분이 아날로그 방송을 수신하여 디지털 영상으로 인코딩한 후 화면에 뿌려줄때 Even Field와 Odd Field를 분리하여 뿌려주기 때문에 많은 영상의 열화가 발생하게 된다. 이러한 문제를 해결하기 위하여 많은 방법들이 연구되고 있는 실정이다. 본 연구에서 사용된 시스템을 간략하게 소개하면 디지털 방송 수신을 위한 SoC로는 Zoran의 G9 Ellete 채택하였고 아날로그 영상의 Decoder로는 AMI의 ADV7401을 선택하였다. 이에 대한 운영체제는 실시간 운영체제인 Thread-X를 선택하였다.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2179-2181
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• 2004

Model-free Method들 중에 반복 피트백 조절 알고리즘(Iterative Feedback Tuning, IFT)는 특정한 성능지수를 정의하고, 이를 최소화하도록 제어기의 게인들을 조절하는 방법을 제시하였다. PID와 같은 고전적인 제어이론에 근거한 제어기 설계 과정과는 달리, IFT 알고리즘은 반복 실험을 통해 성능지수의 Gradient를 구하여 이로부터 필터 게인들 조정하는 방법을 채택하고 있다. 수학적 증명과 실험적 실증을 통하여 IFT의 수렴성과 유용성이 보여짐에도 불구하고 IFT 알고리즘의 한계점은 단일 성능지수의 사용이라는데 있다. 이를 개선하기 위해서는 단일 제어 목적을 위한 단일 성능지수의 사용이 아닌 복수의 제어 목적을 위한 복수의 성능지수의 사용이 필요하다. 본 논문에서는 두 개의 성능지수를 가지는 IFT를 이용해서 위상 여유가 크고, 대역폭이 넓은 제어기를 설계하기 위해서 제어기 게인을 자동 조절하는 알고리즘을 제안하고 ODD에서 사용되는 플랜트에 적용한 모의실험을 통하여 그 유용성을 보였다.

• 한국전산유체공학회:학술대회논문집
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• 1998.11a
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• pp.13-18
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• 1998

The practical use of the particle image velocimetry(PIV), a whole-field velocity measurement method, requires the use of fast, reliable, computer-based methods for tracking velocity vectors. The full search block matching, the most widely studied and applied technique both in area of PIV and Image Coding and Compression, is computationally costly. Many less expensive alternatives have been proposed mostly in the area of Image Coding and Compression. Among others, TSS, NTSS, HPM are introduced for the past PIV analysis, and found to be successful. But, these algorithms are based on small dynamic range, 7 pixels/frame in maximum displacement. To analyze the images with large displacement, Even and Odd field image separation and a simple version of multi-resolution hierarchical procedures are introduced in this paper. Comparison with other algorithms are summarized. A Results of application to the turbulent backward step flow shows the improvement of new algorithm.

• Communications of Mathematical Education
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• v.32 no.3
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• pp.257-273
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• 2018

In this paper, we deal with the isoprimetric problem of polygons from the point of view of learning materials for elementary gifted students. The isoperimetric problem of the polygon of odd degree can be solved by E-transformation(see Figure III-1) and M-transformation(see Figure III-3). But in the case of even degree's polygon, it is quite difficult to solve the problem because of the connected components of diagonals (here we consider the diagonals forming triangle with two adjacent sides of polygon). The primary purpose of this paper is to give an idea to solve the isoperimetric problem of polygons of even degree using the properties of ellipse. This idea is derived from the programs of the Institute of Science Education for Gifted Students in the Jeju National University.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.1
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• pp.147-152
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• 2008

This paper has been fabricated the two different type of variable attenuators using a characteristics of a 3 dB directional coupler and pin diodes. One was not analyzed using the conventional even-odd modes but used simple two-port techniques. The resulting scattering parameters described operation characteristics for the general case where the terminating impedances are equal and unequal. After analyzing resistor role of the ${\pi}$ type fixed attenuator. this paper used a pin diode instead of a resistor. The variable attenuators were fabricated using pin diodes for current-controlled attenuation on the coupled ports of a 3 dB branch-line coupler and ${\pi}$ type fixed attenuator. The realized variable attenuators have more than 33 dB attenuation ranges at 2.1 GHz. and the input and output reflection coefficients are less than -13 dB. These results could be applied to mobile communication systems. It can be varied gain of the power amplifier according to change a outdoor environmental temperature and improved linearity.

• Journal of applied mathematics & informatics
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• v.13 no.1_2
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• pp.413-424
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• 2003

L. H Encinas, A. J. Menezes and J. M. Masque in [3] proposed a classification of isomorphism classes of hyperelliptic curve of genus 2 over finite fields with characteristic different from 2 and 5. Y. Choie and D. Yun in [2] obtained the number of isomorphic classes of hyperelliptic curves of genus 2 over $F_{2-}$ using direct counting method. We have obtained isomorphism classes of hyperelliptic curves of genus 2 over $F_{2n}$ for odd n, represented by an equation of the form $y^2$ + $a_{5}$ y = $x^{5}$ + $a_{8}$ x + $a_{10}$ ( $a_{5}$ $\neq$0) [1]. In this paper we characterize hyperelliptic curves of genus 2 over $F_{2n}$ for even n, represented by an equation of the form $y^2$ + $a_{5}$ y = $x^{5}$ + $a_{5}$ x + $a_{10}$ ( $a_{5}$ $\neq$0).>0).

• Journal of applied mathematics & informatics
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• v.30 no.1_2
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• pp.289-304
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• 2012

In this paper, we study asymptotic behaviour of solutions of the following higher order nonlinear dynamic equations $$S_n^{\Delta}(t,x)+{\delta}p(t)f(x(g(t)))=0$$ and $$S_n^{\Delta}(t,x)+{\delta}p(t)f(x(h(t)))=0$$ on an arbitrary time scale $\mathbb{T}$ with sup $\mathbb{T}={\infty}$, where n is a positive integer, ${\delta}=1$ or -1 and $$S_k(t,x)=\{\array x(t),\;if\;k=0,\\a_k(t)S_{{\kappa}-1}^{\Delta}(t),\;if\;1{\leq}k{\leq}n-1,\\a_n(t)[S_{{\kappa}-1}^{\Delta}(t)]^{\alpha},\;if\;k=n,$$ with ${\alpha}$ being a quotient of two odd positive integers and every $a_k$ ($1{\leq}k{\leq}n$) being positive rd-continuous function. We obtain some sufficient conditions for the equivalence of the oscillation of the above equations.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.5
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• pp.473-481
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• 2013

A fractional folding analog-to-digital converter (ADC) with a novel arithmetic digital encoding technique is discussed. In order to reduce the asymmetry errors of the boundary conditions for the conventional folding ADC, a structure using an odd number of folding blocks and fractional folding rate is proposed. To implement the fractional technique, a new arithmetic digital encoding technique composed of a memory and an adder is described. Further, the coding errors generated by device mismatching and other external factors are minimized, since an iterating offset self-calibration technique is adopted with a digital error correction logic. A prototype 8-bit 1GS/s ADC has been fabricated using an 1.2V 0.13 um 1-poly 6-metal CMOS process. The effective chip area is $2.1mm^2$(ADC core : $1.4mm^2$, calibration engine : $0.7mm^2$), and the power consumption is 88 mW. The measured SNDR is 46.22 dB at the conversion rate of 1 GS/s. Both values of INL and DNL are within 1 LSB.