Proposing New Equilibrium Concepts in Dynamic Games with Noisy Signals

김정유 ( Jeong-yoo Kim ) 한국경제학회 2023 The Korean Economic Review Vol.39 No.2

본 연구에서는 관찰의 오류로 인하여 균형에서 어떠한 신호도 가능한 동태적 게임을 고려한다. 이러한 불완전한 신호를 갖는 게임에서는 완전 베이지안 균형이나 순차적 균형이 요구하는 믿음의 일관성조건이 지나치게 강하여 타당성있는 결과를 배제하게 되므로 ε -완전 베이지안 균형이나 극한 완전균형과 같은 대체적 균형개념이 필요함을 주장한다. 위 두 개념은 균형전략이 선택되었다고 할때 신호의 우도가 ε 을 초과하는 경우에만 믿음에 베이지안 룰을 적용한다는 다소 완화된 일관성조건에 의해 정의된다. 이러한 개념들은 희소한 사건에 대해서는 베이지안 룰로부터의 이탈경향이 보다 높다는 경험적 관찰과도 일치한다. 본 연구는 위 두 개념이 선도자의 행위를 관찰함에 아주 근소한 오류가 있더라도 소멸되는 선도자 이득을 특정 조건하에 다시 회복시켜 줄 수 있음을 보인다. In this study, we consider dynamic games with noisy signals in which any signal is possible in equilibrium due to noises in observations. We argue that in games with noisy signals, the consistency condition of beliefs required by the perfect Bayesian equilibrium or sequential equilibrium is too strong to comprehend reasonable outcomes. Accordingly, we propose alternative solution concepts called ε -perfect Bayesian equilibrium and limit perfect Bayesian equilibrium. The two equilibrium concepts rely on a weaker consistency condition that requires beliefs to be updated by Bayes’ law only if the likelihood that a signal occurs given that the equilibrium action was played exceeds ε > 0 . Our concepts are consistent with empirical observations that show higher deviations from Bayes’ law for rare events. We show that under some conditions, both ε -PBE and limit PBE can fully recover the first-mover advantage that disappears with even a slight noise in observing the first mover’s strategy.

Equilibrium Analysis of a Two-Sided Market with Multiple Platforms of Monopoly Provider

( Do Hoon Kim ) 정보통신정책학회 2012 정보통신정책연구 Vol.19 No.3

In this paper, we consider a single monopoly platform provider which operates both platforms: an old and a new platform. These two platforms connect the user group with the suppliers, thereby leveraging the indirect network externalities in a two-sided market. We also incorporate a cross-platform externality which represents a potential backward compatibility of the new platform: i.e., users joining the new platform can also enjoy the products and services provided by suppliers using the old platform. Users and suppliers are uniformly populated over [0, 1] interval as in the Hotelling model, and play a subscription game to choose (exactly) one platform. The platform determines the pricing profile for the supplier market, and users and suppliers respond to the pricing profile. Our basic analysis for static equilibrium indicates that it is very unlikely that an interior equilibrium is stable. Furthermore, some specific types of boundary equilibriums, where at least one market side tips to a single platform, are stable under certain conditions. We also present a dynamic decision model of the platform provider, which tries to maneuver the markets toward a target state by controlling price profiles. Our analytical results from the optimal control theory assert that a bang-bang control with subsidization for a specific platform eventually leads the market to the corresponding boundary equilibrium. The cross-platform externality plays an important role for a co-existence of competing platforms under a certain condition.

Equilibrium Analysis of a Two-Sided Market with Multiple Platforms of Monopoly Provider

김도훈 정보통신정책학회 2012 정보통신정책연구 Vol.19 No.3

In this paper, we consider a single monopoly platform provider which operates both platforms: an old and a new platform. These two platforms connect the user group with the suppliers, thereby leveraging the indirect network externalities in a two-sided market. We also incorporate a cross-platform externality which represents a potential backward compatibility of the new platform: i.e., users joining the new platform can also enjoy the products and services provided by suppliers using the old platform. Users and suppliers are uniformly populated over [0, 1] interval as in the Hotelling model, and play a subscription game to choose (exactly) one platform. The platform determines the pricing profile for the supplier market, and users and suppliers respond to the pricing profile. Our basic analysis for static equilibrium indicates that it is very unlikely that an interior equilibrium is stable. Furthermore, some specific types of boundary equilibriums, where at least one market side tips to a single platform, are stable under certain conditions. We also present a dynamic decision model of the platform provider, which tries to maneuver the markets toward a target state by controlling price profiles. Our analytical results from the optimal control theory assert that a bang-bang control with subsidization for a specific platform eventually leads the market to the corresponding boundary equilibrium. The cross-platform externality plays an important role for a co-existence of competing platforms under a certain condition.

구조변화 전후의 수도권 주택 공간 및 자산시장의 단기동적균형 메커니즘 연구

이무송(Moo Song Lee),유정석(Jung Suk Yu) 한국주택학회 2015 주택연구 Vol.23 No.1

본 연구는 공적분 관계의 구조변화를 고려하여 주택매매가격 및 전세가격 외에 주택자산가격 결정모형에서 두 변수 간의 관계를 결정하는 핵심 거시경제변수인 금리를 VEC 모형의 내생변수에 포함하였고, 금융시장인 주식시장까지 확장하여 수도권 주택시장의 장기균형관계 및 단기 동태적 균형메커니즘을 분석하였다. 첫째, VEC 모형 추정결과 금융시장을 대표하는 코스피 지수와 금리는 내생변수로서 주택매매가격과 전세가격과의 공통적인 추세가 있다기보다 매매가격과 전세가격에 외생성이 있는 것으로 판단되었다. 둘째, 외생적 충격으로 인한 장기균형관계 이탈시 회복되는 단기조정속도는 구조변화 전후 모두 코스피 지수가 가장 빠르게 조정되고 다음으로 주택매매가격과 전세가격 순으로 나타났다. 셋째, 구조변화 이후에는 주택매매가격이 주가지수 변동성에 영향을 받는 정도가 구조변화 이전보다 훨씬 덜 민감해 주택자산이 상대적으로 더욱더 안정적인 성격의 자산으로 바뀌고 있음을 알 수 있었다. 넷째, 충격반응분석 결과 역시 주택매매가격과 전세가격은 구조변화 이전에는 상호 동조화 현상을 보이고 있으나, 구조변화 이후에는 탈동조화 현상을 보이고 있었다. 다섯째, 예측오차의 분산분해 결과도 마찬가지로 구조변화 이전에는 매매가격 및 전세가격의 잔차에 의해 상호 설명력이 유지되고 있지만, 구조변화 이후에는 전세가격이 주택매매가격에 대한 설명력이 없는 것으로 나타나 탈동조화 현상을 보이고 있었다. 분석결과를 종합해볼 때, 우리나라의 주택은 주식에 비해서는 안전한 자산이지만 금융시장에 밀접한 투자자산의 성격을 보이고 있으며, 구조변화 전후 모두 주택매매가격이 장기균형관계 일탈시 시장을 주도하며 회복을 이끌고 있음을 알 수 있다. 하지만 구조변화 이후 주택매매가격은 안정된 현상을 보이는데 반해 전세가격은 계속해서 상승추세를 나타내고 있어, 이는 구조변화로 인한 새로운 균형관계가 형성되고 있는 것으로 보인다. 또한 구조변화 이후에는 금리가 주택매매가격이나 전세가격에 영향을 미치지 못하고 있어, 정부정책 또한 과거 부양정책 의존에서 벗어나 공간시장 안정에 역점을 두어야 할 것으로 보인다. This paper includes the interest which is the key macroeconomic variable in the housing capital asset pricing model as well as the housing price and jeonse price into endogenous variables in VEC Model considering the structural break of cointegration relation. And this investigates the long-run equilibrium and the short-run dynamics equilibrium mechanism in the metropolitan housing market expanding the endogenous variables range to the stock market. Empirical results find that the housing in Korea is more safe asset than the stock is, but it is much similar to the investment asset closely related to the financial market in character. Also, the housing price leads the market and tries to return to balance in the deviations from the long-run equilibrium before and after the structural break. However, while the housing price stays stable after the structural break, the jeonse price is still in the upward trend. This shows that the structural break is building a new equilibrium. Meanwhile, since the interest after the structural break has no influence on the housing price and jeonse price, the government's policy needs to break away from the old pump-priming policies and lay emphasis on the stabilization in the space market.

Benford’s law in non-equilibrium processes: Droplet collisions case

Elsevier 2012 PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIO Vol.391 No.20

<P><B>Abstract</B></P><P>Benford’s law is investigated for the simulation results generated from non-equilibrium molecular dynamics. A statistic to measure how closely a set of the numbers follows Benford’s law is defined. The simulation data are from the collisions of two nano droplets with different impact velocities. When a non-equilibrium system returns to its equilibrium state, some physical quantities relevant to the non-equilibrium settings follow Benford’s law more closely. The initial settings for the non-equilibrium state can be interpreted as a data fabrication of its corresponding equilibrium state. A connection with the Shannon entropy for the first digit distribution is also discussed.</P> <P><B>Highlights</B></P><P>► Characterization of non-equilibrium processes. ► Detecting program correctness. ► Different perspective of relaxation from initial condition.</P>

Articles : Effects of Non-Ideal Adsorption Equilibria of Gas Mixtures on Column Dynamics

( Jeong Ho Yun ),( Dae Ki Choi ),( Sung Hyun Kim ),( Hee Moon ) 한국화학공학회 1997 Korean Journal of Chemical Engineering Vol.14 No.5

A theoretical study has been made for simulating the dynamic behavior of non-ideal gas mixtures in an isothermal fixed-bed adsorber. A mathematical model was developed which takes into account the non-ideality of adsorbable species on the adsorbed phase under equilibrium. The model is based on both the real adsorbed solution theory (RAST), which incorporates the activity coefficients in the multicomponent isotherm equations to account for the deviations from ideality, and the linear driving force (LDF) model for representing diffusion resistance inside the adsorbent particles. To describe the effect of non-ideal adsorption equilibrium of gas mixtures on the breakthrough curves, we considered several model mixtures of binary and ternary components which exhibit non-ideal behavior with azeotropic crossovers in the composition domains at equilibrium. Sample calculations of a fixed-bed adsorption were done with various inlet gas compositions of binary and ternary mixtures, respectively, at a fixed total concentration. From the calculation results, it was shown that the order of breakthrough curves could be changed at a certain value of inlet gas composition ratio. This result implies that the dynamic behaviors of fixed-bed adsorption are greatly influenced by multicomponent equilibrium models. Furthermore, the reversal phenomenon of breakthrough curves could not be simulated by the ideal adsorbed solution theory (IAST).

한국의 대 중국 FDI의 대 중국수출에 대한 효과 분석

최원익 ( Won Ick Choi ) 국제지역학회 2007 국제지역연구 Vol.11 No.1

어떤 국가에 대한 직접투자가 그 국가에 대한 수출에 영향을 미치는 정도에 대한 연구가 그간 있어왔지만 주로 통상적인 최소자승법을 이용한 회귀분석이었다. 이런 통상적인 연구방법은 많은 경제시계열자료가 불안정적(non stationary)이라는 사실을 간과한 것으로서 자료가 불안정적일 때 허구적 회귀현상이 발생해 추정계수들이 비표준적 분포를 이루고 또한 불편추정량이 되지 못하는 문제점을 내포하게 된다. 따라서 본고는 한국에서 중국으로 수출을 할 경우 중국에 대한 직접투자를 비롯한 관련 변수들이 어떻게 영향을 미치는지를 검토함에 있어서, 관련 변수들이 불 안정적인지를 알아보기 위해 단위근검정을 실시하고, 공적분검정을 실시한 결과를 토대로 Johansen의 벡터오차수정모형(VECM; Vector Error Correction Model)을 활용하여 장기균형관계와 균형 상태로부터 이탈되는 단기적 동태분석까지 시도하였다. 분석의 결과 두 개의 장기균형관계가 성립하였는데, 특히 한국에서 중국으로의 수출, 한국의 상대가격, 그리고 한국에서 중국으로의 직접투자 사이에 장기균형관계가 있으며, 단기적으로는 한국에서 중국으로의 수출이 증가해서 장기균형 상태로부터 벗어나면 한국의 수출은 균형회복을 위해 감소하고 중국의 GDP, 한국의 상대가격, 그리고 한국의 중국에 대한 직접투자도 균형회복을 위해 감소한다. Many researches have been done about the effect of a country`s FDI on the export of the country but the researches have mainly utilized a regression analysis using the ordinary least square method. This ordinary research method ignores that many economic time series data are non-stationary. Non-stationary data causes a spurious regression phenomenon so that estimated coefficients are non-standard distributions and are not unbiased estimators. Therefore, this research does a unit root test and a cointegration test in studying the analysis of the effects of many variables including FDI to China on the export to China. On the basis of these tests, this research tries the long-term equilibrium and the short-term dynamic analyses by using Johansen`s VECM(Vector Error Correction Model). Two long-term equilibrium relationships come from the analysis. Especially the long-term equilibrium relationship is constituted among the Korea`s export to China, Korea`s comparative price, and Korea`s FDI to China. In the short run, if the long-term equilibrium relationship break by increased Korea`s export to China; Korea`s export decrease in order to recover the equilibrium, and China`s GDP, Korea`s comparative price, and Korea`s FDI to China also decrease to recover the equilibrium.

생태계(生態系)의 발전(發展)과 역동적(力動的) 균형(均衡)을 위한 환경윤리(環境倫理)에 관한 연구

권혁길 ( Hyuk Kihl Kwon ) 한국윤리학회 2011 倫理硏究 Vol.81 No.1

Ecosystem Development means the ecological succession. Also, ecological succession is the process by which an ecosystem matures. This means the ecosystem response to change from the inside and outside. As an ecosystem develops, the species composition of the community changes until the association of organism best adapted to the physical conditions of the area is reached. Ecosystems are dynamic, that is, they constantly go through changes of various kinds. Organisms die and new generations arise. Temperature rise and fall with the season. One community is replaced by another during succession. Ecosystems also possess equilibrium, a condition of balance or stability. In this paper, I tried to research the more rational Environmental Ethics for the Ecosystems development and Dynamic equilibrium. Also, I introduced moderate pluralism of Callicott`s land ethic. Peter S. Wenz explain moderate, and extreme Moral Pluralism. Moderate Pluralism wants to coexist with other moralism. I think the Moderate Moral Pluralism will be a good partner for Ecosystems Development and Dynamic equilibrium for Sustainable development of the our future.

Dynamic Spectrum Access with Spatial Reuse

Ying Liu,Guangqiang Shi,Xiaomin Mu 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.1

We investigate the problem of achieving utility function optimization for distributed channel selection using game theoretic solutions in opportunistic spectrum access system, where secondary users are spatially located and mutual interference only emerges between neighboring users. In addition, interference graph of spatial position is introduced to measure interference and evaluate the possible opportunities of spectrum access. Based on this we propose an optimization problem of minimizing loss throughput, which is solved by a game theory and an optimal channel selection set is derived. The main work of this paper is to prove that this game is an exact potential game, which has at least one pure strategy Nash equilibrium. Finally simulation results is given to verify the correctness of the theoretical analysis. Especially meanwhile after considering spatial reuse by users’ position, the system throughput is significantly increased, thus the spectrum utilization rate is effectively improved.

Nonequilibrium thermodynamics for a harmonic potential moving in time

Lee Hyun Keun,Kwon Youngchae,권철안 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.83 No.5

We investigate non-equilibrium thermodynamics externally driven by moving the center of harmonic potential in time. We present the theoretical formalism for an arbitrary motion in underdamped dynamics. We provide the formulas to find thermodynamic quantities such as work, heat and entropy production produced for time period, which are main quantities in non-equilibrium studies. For sinusoidal driving with external frequency Ω, we observe a resonance for work production where the average rate for infinite period is maximized at Ω = ω0 that is the internal frequency of the harmonic oscillator. It may be used for an alternative way to measure the stiffness of an optical trap potential. We confirm the thermodynamic uncertainty relation newly found for underdamped dynamics subject to general time-dependent protocols for a specific example of driving.