김정호 교수

Abstract We study a global dynamics of the thermomechanical Cucker–Smale (TCS) particles immersed in incompressible viscous fluid. For this, we use a coupled system consisting of kinetic TCS equation for particles and incompressible Navier–Stokes for fluid via a drag force in three dimensions. We first show the global existence of weak solutions for large data, and then establish the global existence and uniqueness of strong solutions under a smallness assumption on the initial data. We also pro

We present the optical models and calculation results of thin-film organic solar cells (OSCs) at oblique incidence of light, using the transfer matrix method. The simple expression for the optical power dissipation is derived at oblique incidence for s- and p-polarized light. The spatial distribution of the electric field intensity, the optical power density, and the optical power dissipation are calculated in both s- and p-polarized light with respect to the incidence angle. We identify how the

In this paper, we propose Q-learning algorithms for continuous-time deterministic optimal control problems with Lipschitz continuous controls. Our method is based on a new class of Hamilton-Jacobi-Bellman (HJB) equations derived from applying the dynamic programming principle to continuous-time Q-functions. A novel semi-discrete version of the HJB equation is proposed to design a Q-learning algorithm that uses data collected in discrete time without discretizing or approximating the system dynam

Maximum entropy reinforcement learning methods have been successfully applied to a range of challenging sequential decision-making and control tasks. However, most of the existing techniques are designed for discrete-time systems although there has been a growing interest to handle physical processes evolving in continuous time. As a first step toward their extension to continuous-time systems, this article aims to study the theory of maximum entropy optimal control in continuous time. Applying

This Study investigates the Star power of Korean Movies. The sample consists of 421 films released during 2003-2007. During the period, 204 directors made only one film each. 63 directors made 147 movies. 43 actors and actress played main roles for 263 movies. Median numbers of audience are 424,514, average numbers of audience are 986,757.44, and the mode is 424,514. The regression results indicate the Power of Stars in the Korean film Industry between 2003 and 2007. Seventeen individual actors,

Purpose: This study evaluated the psychometric properties of the Korean version of Yale Food Addiction Scale for Children (YFAS-C). Methods: Participants were 419 young adolescent students (11~15 years old). The content validity of the expert group was calculated as the content validity index (CVI) after the translation and reverse translation process of the 25 items of the YFAS-C. The multitrait-multimethod matrix (MTMM) method was used to verify the construct validity; the generalized linear m

In this paper, we propose a consensus-based algorithm for nonconvex optimization on the Stiefel manifold. For a given objective function on the Stiefel manifold, we construct a stochastic interacting particle system for sample points so that all the sample points are expected to asymptotically converge to a single point, which is close enough to a global minimizer. We show the global existence and uniqueness of solutions to our stochastic differential equation (SDE) model for consensus. A predic

한국 영화의 시장 점유율은 최저 2008년 42.1%에서 최고 2013년 59.7%로 높은 점유율을 유지하고 있다. 그러나 멀티플렉스와 와이드 릴리스 전략, 4대 메이저 배급 회사와 3대 멀티플렉스 체인의 독과점의 영향으로 한국 영화 흥행의 양극화 현상은 심화되고 있다. 한국 영화 흥행 집중도는 2004년 0.53에서 2014년 0.85로 심화되었다. 흥행 순위 상위 10%의 한국 영화가 차지하는 관객 수 비중은 2004년 30.28%에서 2014년 71.2%로 급격히 높아진 반면에, 흥행 순위 하위 50%는 2004년 11.03%에서 2014년 0.08%로 아주 낮아졌다. 상영 스크린 집중도도 2004년 0.36에서 2014년 0.67로 심화되었고, 상영 횟수 집중도도 2004년 0.46에서 2014년 0.78로 높아졌다. 좌석 수의 집중도도 2004년 0.50에서 2014년 0.79이다. 많은 관객이 선택하는 영화라서 상영 스크린 수를 늘리고, 상영 횟수를 늘리고, 많은 좌석 수

Composite buffer layers of N,N′-bis(naphthalene-1-yl)-N,N′-bis(phenyl)benzidine (NPB) and NaCl at the anode/organic interface were found to be very effective on the hole injection enhancement from an indium tin oxide anode to the hole-transport layer (HTL) of NPB. Two maxima of significant current injection with respect to compositional variation were observed, implying multiple injection mechanisms of the tunneling effect and other interfacial effects. From a longer operation lifetime, the enha

This Study is on the determinants of financial performances of Hollywood movies in the U.S. domestic market and foreign market such as Korea. For study, we collect the variables for 179 Hollywood films that were released in Korea during 2007～2008. The two markets are highly related with each other. However, Variables that are related with the box office performance in the two markets are significantly different. Opening weekend revenue, IMDB User rating, Oscar, numbers of Opening weekend screens

In this paper, we introduce Hamilton-Jacobi-Bellman (HJB) equations for Q-functions in continuous time optimal control problems with Lipschitz continuous controls. The standard Q-function used in reinforcement learning is shown to be the unique viscosity solution of the HJB equation. A necessary and sufficient condition for optimality is provided using the viscosity solution framework. By using the HJB equation, we develop a Q-learning method for continuous-time dynamical systems. A DQN-like alg

한국 영화의 배급은 CJ E & M, 롯데, 쇼박스, NEW의 4대 메이저 배급사를 통해서 이뤄지고, CJ CGV, 롯데 시네마, 메가 박스의 3대 멀티플렉스를 통해서 관객에게 선보인다. 2009년부터 2014년까지 배급된 한국영화 538편수 중에서, 이들 4대 배급사는 290편을 배급하여 배급점유율은 53.9% 이나 관객점유율은 85.74%를 차지한다. 나머지 248편을 배급하여 배급편수의 46.09%를 차지하는 4대 배급사 이외의 기타배급의 형태는 14.26%의 관객점유율을 가지고 있는 현실이다. 4대 배급사 중에 CJ와 롯데는 배급과 극장 사업을 함께 가지고 있다. 멀티플렉스와 와이드 릴리스 전략, 4대 메이저 배급 회사와 3대 멀티플렉스 체인의 독과점의 영향으로 한국 영화 흥행의 양극화 현상은 심화되고 있다. 작품수, 동원 관객 수, 상영 스크린 수, 상영 횟수, 좌석 확보수 등의 척도에서 기타 배급사의 영화들은 각 흥행순위 구간에서, 모든 척도의 평균값보다 낮은 수치를 보였

In this paper, we present the hydrodynamic limit of a multiscale system describing the dynamics of two populations of agents with alignment interactions and the effect of an internal variable. It consists of a kinetic equation coupled with an Euler-type equation inspired by the thermomechanical Cucker--Smale (TCS) model. We propose a novel drag force for the fluid-particle interaction reminiscent of Stokes' law. Whilst the macroscopic species is regarded as a self-organized background fluid that