• 천문학논총
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• 제25권2호
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• pp.31-49
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• 2010

Next to Paper I (Jeon 2009a), time-series BV CCD images of the open cluster M38 were taken for 4 nights on December, 2009. The observations have been carried out for total 27 nights. In addition to the 20 variable stars in the Paper I, the discovery of 44 new variable stars has been presented in this paper: $6{\delta}$ Scuti stars, $2{\gamma}$ Doradus stars, 18 eclipsing binaries and 18 semi-long periodic and/or slow irregular type variable stars. For the V photometry of the ${\delta}$ Scuti and ${\gamma}$ Doradus stars, multi-frequency analysis was performed using the Discrete Fourier Transform and linear least-square fitting. The period search for the eclipsing binaries and the semi-long periodic and/or slow irregular type variable stars was performed by phase fitting method. As a result, the periods for 23 variable stars among the 44 ones were defined.

• 천문학논총
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• 제25권4호
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• pp.167-176
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• 2010

In the region of the intermediate open cluster M35 (NGC 2168), the time-series of V CCD images was taken for 12 nights from December 18, 2007 to September 25, 2010. From this observation, we detected 22 variable stars including 15 new ones. They are 6 $\delta$ Scuti, a Cepheid, an RR Lyrae, 9 eclipsing binaries and 5 semi-long periodic and/or slow irregular type variable stars. For the V photometry of the $\delta$2 Scuti stars, the multi-frequency analysis was performed using the Discrete Fourier Transform and the linear least-square fitting.

• 대한수학회논문집
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• 제10권1호
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• pp.133-135
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• 1995

In this note, we will investigate the radial symmetry of some kind of solutions of nonlinear ellipitic equations $$ \Delta U = f(U) $$ $$ (1.1) U = 0 in B $$ $$ U \in C^2 (\bar{B}) on \partial B$$ Here f is $C^1$ and B denotes a n-dimensional unit ball in $R^n$.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2005년도 춘계학술대회 학술발표 논문집 제15권 제1호
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• pp.147-148
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• 2005

In this paper we study Laplace transform of the fuzzy Dirac delta function and the examples of fuzzy impulsive differential equations.

• 충청수학회지
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• 제23권2호
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• pp.349-362
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• 2010

We establish the various relationships among the integral transform ${\mathcal{F}}_{{\alpha},{\beta}}F$, the convolution product $(F*G)_{\alpha}$ and the first variation ${\delta}F$ for a class of functionals defined on K(Q), the space of complex-valued continuous functions on $Q=[0,S]{\times}[0,T]$ which satisfy x(s, 0) = x(0, t) = 0 for all $(s,t){\in}Q$. And also we obtain Parseval's and Plancherel's relations for the integral transform of some functionals defined on K(Q).

• 정보처리학회논문지B
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• 제12B권1호
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• pp.9-16
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• 2005

본 논문은 얼굴인증 시스템 구현과 조명변화에 견인한 얼굴인증 방법들에 관한 연구에 초점을 둔다. 얼굴인증 시스템 구현을 위한 방법으로 PCA(Principal Component Analysis), GMM(Gaussian Mixture Models), 1차원 HMM(1 Dimensional Hidden Markov Models), 준 2차원 HMM(Pseudo 2 Dimensional Hidden Markov Models) 방법을 이용한다. 네 가지 다른 얼굴인증 방법들의 조명변화에 대한 성능비교 실험을 수행한다. 조명변화실험을 위해 얼굴이미지의 왼쪽에서 오른쪽으로 인공적인 조명효과(${\delta}=0,40,60,80$)를 준다. 얼굴특징벡터는 얼굴이미지에서 분할한 각 블록에 대한 2D DCT(2 Dimensional Discrete Cosine Transform) 계수를 이용하고 실험은 ORL(Olivetti Research Laboratory) 얼굴데이터베이스를 사용한다. 실험결과 모든 경우 조명변화 값이 커질수록 성능저하가 발생한다. 또한 조명변화가 없는 경우(${\delta}=0$) 준 2차원 HMM이 $2.54{\%}$, 1차원 HMM이 $3.18{\%}$, PCA가 $11.7{\%}$, GMM이 $13.38{\%}$의 EER(Equal Error Rate) 성능을 나타낸다. 조명변화가 없는 경우(${\delta}=0$) 1차원 HMM 방법이 PCA 방법보다 좋은 성능을 나타내지만 조명변화 ${\delta}{\geq}40$인 때에는 반대로 PCA 방법이 더 좋은 성능을 나타낸다. 마지막으로 준 2차원 HMM의 경우 조명변화에 관계없이 가장 좋은 EER성능을 나타낸다.

• 천문학논총
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• 제31권3호
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• pp.43-56
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• 2016

Through time-series BV CCD photometry of the open cluster NGC 225 region, we have detected 30 variable stars including 22 new ones. They are five ${\delta}$ Scuti-type variable stars, a slowly pulsating B star, six eclipsing binary stars and 18 semi-long periodic or slow irregular variables, respectively. We have performed multiple-frequency analysis to determine pulsation frequencies of the ${\delta}$ Scuti-type stars and a slowly pulsating B star, using the discrete Fourier transform and linear least-square fitting methods. We also have derived the periods and amplitudes of 6 eclipsing binaries and a long-period variable star from the phase fitting method, and presented the light curves of all variable stars. A slowly pulsating B star is a member of NGC 225, but ${\delta}$ Scuti-type stars are not members from the positions in the color-magnitude diagram and the radial distancies from the center of the cluster. From Dias et al. (2014, A&A, 564, 79), only three variable stars including the slowly pulsating B star are members of clusters: two are in NGC 225 and one is in Stock 24. But a variable star in Stock 24 is not a member of the cluster because of its position of color-magnitude diagarm.

• 대한수학회논문집
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• 제27권4호
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• pp.721-732
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• 2012

The principal aim of the paper is to investigate new integral expression $${\int}_0^{\infty}x^{s+1}e^{-{\sigma}x^2}L_m^{(\gamma,\delta)}\;({\zeta};{\sigma}x^2)\;L_n^{(\alpha,\beta)}\;({\xi};{\sigma}x^2)\;J_s\;(xy)\;dx$$, where $y$ is a positive real number; $\sigma$, $\zeta$ and $\xi$ are complex numbers with positive real parts; $s$, $\alpha$, $\beta$, $\gamma$ and $\delta$ are complex numbers whose real parts are greater than -1; $J_n(x)$ is Bessel function and $L_n^{(\alpha,\beta)}$ (${\gamma};x$) is generalized Laguerre polynomials. Some integral formulas have been obtained. The Maple implementation has also been examined.

• Journal of the Optical Society of Korea
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• 제14권2호
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• pp.104-108
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• 2010

We proposed an axis transformation technique which reveals a distance parameter directly from optical scanning holography (OSH). After synthesis of a real-only spectrum hologram and power fringe adjusted filtering, we transform an original frequency axis to a new frequency axis using interpolation. In the new frequency axis, the filtered hologram has a single frequency which is linearly proportional to the distance parameter. Thus, the inverse Fourier transformation of the filtered hologram gives a delta function pair in the new spatial axis. Finally, we extract the distance parameter by detecting the location of the delta function pair.

• 한국기계가공학회지
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• 제2권4호
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• pp.46-52
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• 2003

For position control of electro-hydraulic servo system, single rod cylinders and double rod cylinders are used. Single rod cylinders have simple structure for manufacturing but different volume ratio of two sides induce to non-linearity in process of then mathematical modeling. So only with conventional PID control method it is difficult to control single rod cylinders precisely. For mole precise position control of single rod cylinders, a controller which is inserted a velocity feedback PID controller and MRAC controller are proposed. With experiment control performances of three control methods are compared. In case of experiment, for external varying load to the system, a hydraulic cylinder and a pressure control valve are used. In conclusion a MRAC is considered a suitable control method for external varying load.