http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Meshfree Local Radial Basis Function Collocation Method with Image Nodes
백승기,백승기 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.71 No.1
We numerically solve two-dimensional heat diffusion problems by using a simple variant of the meshfree local radial-basis function (RBF) collocation method. The main idea is to include an additional set of sample nodes outside the problem domain, similarly to the method of images in electrostatics, to perform collocation on the domain boundaries. We can thereby take into account the temperature profile as well as its gradients specified by boundary conditions at the same time, which holds true even for a node where two or more boundaries meet with different boundary conditions. We argue that the image method is computationally efficient when combined with the local RBF collocation method, whereas the addition of image nodes becomes very costly in case of the global collocation. We apply our modified method to a benchmark test of a boundary value problem, and find that this simple modification reduces the maximum error from the analytic solution significantly. The reduction is small for an initial value problem with simpler boundary conditions. We observe increased numerical instability, which has to be compensated for by a sufficient number of sample nodes and/or more careful parameter choices for time integration.
A noise filtering scheme for a chaotic signal
백승기,문희태 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.3
We present a noise-ltering scheme which works on a chaotic signal containing a certain level of noise. Our method exploits the simplicity of Rosa's ltering scheme, as well as the high applicability of the maximum likelihood method. We tested our scheme on signals from various dynamical systems and found that the noise amplitudes could be reduced up to a few percent. In the study, we are learned that our scheme could also be used for inferring the underlying dynamics of a received chaotic signal when no a-priori knowledge of the dynamics was given.
비산재를 활용한 해수 알칼리도 증대 및 흡수액의 알칼리도가 탈황 효율에 미치는 영향
백승기,조현호,서용칠,김성헌,정현태,홍정희 한국폐기물자원순환학회 2014 한국폐기물자원순환학회지 Vol.31 No.8
Among many types of flue gas desulfurization (FGD) facilities, wet type FGD using lime or limestone is most popular in the world because of its simplicity of operation and availability of lime and limestone. Seawater desulfurization utilizes the alkalinity of seawater, thus requires no addition of lime and limestone. The efficiency of seawater desulfurization depends on the variation of alkalinity of seawater at different locations. This study presents the effect of gas-water ratio and total alkalinity of absorbing solution on the removal efficiency of sulfur dioxide from the flue gas by means of seawater. Also this study provides an alternative way to increase total alkalinity of seawater by utilizing fly ash from coal-fired power plants. The increase of removal efficiency with increase of alkalinity was measured as 0.26 ± 0.01% per ppm of bicarbonate alkalinity from the set of experiments using seawater, underwater, and distilled water, the alkalinity of which were 111 ppm, 38 ppm, and 1 ppm, respectively. Capability to increase total alkalinity of seawater using fly ash was confirmed.
경쟁시장에서 컨조인트분석에 기초한 제품포지셔닝에 대한 연구:온라인 게임을 중심으로
백승기,임호순,박명섭 한국경영과학회 2006 한국경영과학회지 Vol.31 No.3
We introduce a two-stage game theoretic model to support decision making processes for product positioning and pricing in competitive environment. In the first stage, firms decide on entry and product position; in the second stage, firms compete with price. ‘Alpha rule' is used as a choice model. Demand parameters of the choice model are estimated by conjoint analysis. We investigate conditions for the existence of Nash price equilibria in the pricing game. Nash equilibria in the entry and positioning game are produced using a concept of stable sets. An example of the online game industry in Korea is examined.
백승기,김범준 한국물리학회 2010 새물리 Vol.60 No.9
A game-theoretic approach has been providing a powerful tool in the qualitative understanding of macroscopic social phenomena in social sciences, e.g., in economics and in political science. Recently, researchers in physics, especially in statistical physics, have also used these game-theoretic approaches, but in a more quantitative way, and have been producing a variety of interesting results in the new research area called ‘sociophysics’ by studying human society as a complex system. This work introduces recent works that have tackled the combinatorial complexities arising in gametheoretic studies with the aid of simplified assumptions and numerical computations. We first show how cooperation emerges in the prisoner’s dilemma game when each player’s memory capacity is enhanced and suggest that the intelligent tit-for-tat strategy plays a crucial role in the history of cooperation. Then, we numerically show that there is a certain case of simultaneous coordination among many players where the system has a high risk of failure when everyone is willing to follow the coordination, which is actually higher than when some are not concerned about it. Lastly, we discuss a mathematical treatment of an equilibrium solution for a reverse auction game, which is a variant of the minority game, and its computational approach. 경제학이나 정치학과 같은 사회과학에서 게임이론은 거시적인 사회현상을 이해하는 강력한 도구로 자리잡았다. 최근 물리학, 특히 통계물리학 분야의 연구자들은 이러한 게임이론의 모형들을 이용하여 복잡관계로서의 사회를 수치적으로 연구하는, 이른바 사회물리학 (sociophysics)이라는 신조어를 탄생시키면서 다양한 연구결과들을 생산해 내고 있다. 본 논문에서는 게임 이론의 연구에서 나타나는 조합론적 복잡성을 몇 가지 단순화된 가정과 수치 계산의 도움을 통해 분석한 최근 연구들을 소개한다. 먼저 죄수의 딜레마에서 각 참여자들의 기억력이 향상되었을 때 협력이 어떻게 발생하는가를 분석하여 ‘영리한 맞대응 (Intelligent Tit-for-tat)’전략이 중요한 역할을 수행한다는 사실을 보인다. 다음으로 여러 사람이 동시에 자신의 행동을 조정해나가는 조정 게임의 경우, 모든 사람이 자신의 행동을 주어진 규범에 따라 조직하려고 할 경우 오히려 조정이 방해받는 상황이 있을 수 있음을 수치 계산을 통해 보인다. 마지막으로 소수자 게임의 한 변형인 역경매 게임에서의 군형점을 어떻게 수학적으로 공식화할지와 그 계산 방법을 논한다.