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다결정을 이용한 실온에서의 분광 홀버닝 광메모리 구현에 관한 연구
조재헌,백운식,장기완 경희대학교 레이저공학연구소 2001 레이저공학 Vol.12 No.-
The extremely high data densities can be obtained by spectral holeburning, so persistent holeburning has been studied on crystal that doped sm2+ ions at room temperature. To improve performance of persistent spectral holeburning system, we replace a dye laser system by our Littman type external cavity tunable laser diode system.
양규호,박창헌,손정수,김낙현,최남기,김선미,김기백,신혜성 大韓小兒齒科學會 2009 大韓小兒齒科學會誌 Vol.36 No.3
혼합치열기 정상교합 아동 24명(남:14명 여:10명 초진 시 평균 나이 9±1.3세, 평균 관찰 기간: 13±1.3개월)에 대한 성장량을 측정하여 기능적 교정장치의 순수 치료효과를 평가하는데 도움이 되기 위해 3회(5~8개월 간격) 촬영한 측모 두부 방사선 규격 사진에 대한 분석 결과 다음과 같은 결론을 얻었다. 1. 남아는 상악골은 전하방, 하악골은 전방성장하였고, 여아는 상하악골이 전하방 성장하였다(p<0.05). 2. 상하악골의 남녀간 차이에서 수평적 성장상태는 여아가 컸고(A point 여아: 2.39mm, 남아: 1.26mm, p<0.05), 수직적 성장상태는 유의한 차이가 없었다. 3. 상악 전치의 치축은 두개저에 대해서 순측 경사하였고(p<0.01) 하악 전치의 치축은 큰 변화가 없었다. The purpose of this study was to provide the reference data evaluating the treatment effect of orthopedic appliances. The skeletal and dental growth increments were measured in 24 normal mixed dentition children(boys: 14, girls: 10) by three serial lateral cephalograms: initial mean age: 9±1.3 years, mean observation period: 13±1.3 months, Cephalometric changes were analysed. The results were as follows: 1. In boys, the maxilla showed forward and downward growth pattern and the mandible showed forward growth pattern(p<0.05). In girls, the maxilla and mandible showed forward and downward growth pattern(p<0.05). 2. Horizontal growth of both maxilla and mandible in girls was superior to those in boys(A point: girls: 2.39mm, boys: 1.26mm, with p<0.05), whereas vertical growth of both maxilla and mandible in boys was similar to those in girls. 3. The change in tooth axis showed labioversion of upper incisor(p<0.01) and comparatively stable lower incisor position.
Complex dynamics of a Ivlev-type predator-prey system with impulsive control strategy
Hun Ki BAEK 한국산업응용수학회 2007 한국산업응용수학회 학술대회 논문집 Vol.3 No.2
In this paper, we study a predator-prey model with Ivlev-type functional response and impulsive perturbations and we prove that there exists a stable prey-free solution when the impulsive period is less than some critical value. Also, we find a sufficient condition that the model is permanent. We have numerical results on impulsive perturbations that show that the model we consider can give birth to various kinds of dynamical behaviors. It will be useful for studying the dynamical complexity of ecosystems.
Dynamics of An Impulsive Food Chain System With A Lotka-Volterra Functional Response
( Hun Ki Baek ) 한국산업응용수학회(구 한국산업정보응용수학회) 2008 한국산업정보응용수학회 Vol.12 No.3
We investigate a three species food chain system with Lotka-Volterra type functional response and impulsive perturbations. We find a condition for the local stability of prey or predator free periodic solutions by applying the Floquet theory and the comparison theorems and show the boundedness of this system. Furthermore, we illustrate some examples.
Regularities of Fractal Measures on R^{2}
Hun Ki Baek,Hung Hwan Lee 경북대학교 자연과학대학 수학과 2004 Kyungpook mathematical journal Vol.44 No.4
We get a characterization of strong regularity with d-measure on.
Extinction and Permanence of a Holling I Type Impulsive Predator-prey Model
Baek, Hun-Ki,Jung, Chang-Do Department of Mathematics 2009 Kyungpook mathematical journal Vol.49 No.4
We investigate the dynamical properties of a Holling type I predator-prey model, which harvests both prey and predator and stock predator impulsively. By using the Floquet theory and small amplitude perturbation method we prove that there exists a stable prey-extermination solution when the impulsive period is less than some critical value, which implies that the model could be extinct under some conditions. Moreover, we give a sufficient condition for the permanence of the model.
Scaling Law of the Hausdorff Measure
Baek, Hun-Ki,Lee, Hung-Hwan Department of Mathematics 2009 Kyungpook mathematical journal Vol.49 No.4
We exhibit an example that the scaling property of Hausdorff measure on $\mathbb{R}^{\infty}$ does not hold.
Mutifractal Analysis of Perturbed Cantor Sets
Baek, Hun Ki,Lee, Hung Hwan Department of Mathematics 2005 Kyungpook mathematical journal Vol.45 No.4
Let $\left{K_{\alpha}\right}_{{\alpha}{\in}{\mathbb{R}}}$ be the multifractal spectrums of a perturbed Cantor set K. We find the set of values ${\alpha}$ of nonempty set $K_{\alpha}$ by using the Birkhoff ergodic theorem. And we also show that such $K_{\alpha}$ is a fractal set in the sense of Taylor [12].
The convergence of the finite element multigrid solution of an optimal control optimality system
Hun Ki BAEK,Sangdong KIM,Philsu KIM 한국산업응용수학회 2006 한국산업응용수학회 학술대회 논문집 Vol.1 No.1
Optimal control problems involving partial differential equation are nowadays receiving much attention because of their importance in the industrial design process. Especially, the need for accurate and efficient solution methods for these problems has become an important issue. We consider a finite element framework and multigrid methods for the case of a partial differential equation control problem with a finite number of design parameters. This present work is characterized by the fact that we extend known analytic tools for scalar elliptic problems to the case of a non symmetric system of elliptic partial differential equation, called an optimality system. First, we prove stability of the finite element optimality system and prove the error estimates in the discrete L² norm and in the discrete H¹ norm. And then, the convergence of the multigrid method to weak solutions of the optimality system is proved. Moreover, this multigrid convergence does not require special assumptions on the boundary, it applies to polygonal domains.