1,723,405 research outputs found
준고전적 블랙홀의 동역학과 정보손실문제
No full text학위논문(박사) - 한국과학기술원 : 물리학과, 2011.2, [ xii, 173 p. ]In this thesis, the author studies the information loss problem using semi-classical black holes. If a black hole loses information after evaporation, it will imply the violation of unitarity and predictability. Therefore, to understand the nature of the Theory of Everything and to reconcile the quantum theory and gravitation, we need to understand the problem of the information loss.
If we assume that there exists a unitary theory of quantum gravity as a working hypothesis, the area of a black hole is proportional to the statistical entropy of the black hole, and there is an observer who can see information from Hawking radiation, then it is inevitable to accept black hole complementarity. However, if there is an observer who can see both information of inside and outside, i.e., if the duplication experiment is possible, then black hole complementarity will be violated.
A duplication experiment and other thought experiments can be investigated by semi-classical backgrounds. In this thesis, we focus on three subjects: gravitational objects of Einstein gravity with renormalized energy-momentum tensors, gravitational objects of modified theories of gravity, and initial conditions which can be prepared by quantum tunneling. To study such subjects, we use the following techniques: traditional analytic approaches, numerical approaches using the double-null formalism, and Euclidean analytic continuations.
We study a possibility of a duplication experiment in a charged black hole and a regular black hole. Causal structures allow the possibility; but to regularize curvatures around the inner horizon, we require a sufficiently large number of massless fields which contribute to Hawking radiation. In fact, if we assume the large number, we can violate black hole complementarity even for neutral black holes. The required number of fields can be reduced to a reasonable amount; although we need a large number, if it is finite, the number may be allowed by a model of quantum...한국과학기술원 : 물리학과
Distribution of asset price movement and market potential
No full textIn this article we discuss the distribution of asset price movements
by introducing a market potential function. From the principle of free energy
minimization we analyze two different kinds of market potentials. We obtain a
U-shaped potential when market reversion (i.e. contrarian investors) is dominant.
On the other hand, if there are more trend followers, flat and logarithmic
potentials appear. By using the cyclically adjusted price-to-earning ratio, which
is a common valuation tool, we empirically investigate the market data. By
studying long term data we observe the historical change of the market potential
of the US stock market. Recent US data show that the market potential looks
more like a trend-following potential. Next, we compare the market potentials
for 12 different countries. Though some countries have similar market potentials,
there are specific examples like Japan which exhibits a very flat potential.In this article we discuss the distribution of asset price movements by introducing a market potential function. From the principle of free energy minimization we analyze two different kinds of market potentials. We obtain a U-shaped potential when market reversion (i.e. contrarian investors) is dominant. On the other hand, if there are more trend followers, flat and logarithmic potentials appear. By using the cyclically adjusted price-to-earning ratio, which is a common valuation tool, we empirically investigate the market data. By studying long term data we observe the historical change of the market potential of the US stock market. Recent US data show that the market potential looks more like a trend-following potential. Next, we compare the market potentials for 12 different countries. Though some countries have similar market potentials, there are specific examples like Japan which exhibits a very flat potential
Studies on the KDP ferroelectric domains by laser interferometry
No full text학위논문(석사) - 한국과학기술원 : 물리학과, 1985.2, [ [ii], 55 p. ]한국과학기술원 : 물리학과
A computer modelling of fission gas release in fuel during normal operation
No full text학위논문(석사) - 한국과학기술원 : 핵공학과, 1985.2, [ vi, 65 p. ]한국과학기술원 : 핵공학과
Time spent on social media and its impact on travel behaviours and activity participation: Preliminary results from a comparative study based on association analysis and discrete choice models
No full textAn empirical analysis is proposed to study the effects that the use of computers for leisure and relaxing, that includes the time spent on social media, has on travel patterns, with special emphasis on some discretionary trips (especially leisure trips). Data from 2013 American Time Use Survey is used in the study. Results obtained using a data mining technique, namely association analysis (AA), and those derived from a discrete-continuous model of leisure engagement (DCM) are proposed. Association analysis is implemented first to explore the intertwined relationships between socio-economic characteristics, social media use and travel behaviours, and then inform the specification of the econometric model. Then the estimated models are applied to predict changes in the decisions of activity participation and time usage according to changed socio-demographic profile and time usage on other related activities. The analysis reveals the socio-demographic profile of those engaged in various types of leisure activities and the effect of travel on the time spent on leisure. High educated individuals are more likely to be involved in leisure associated to computer use, while the presence of children in the household and a full time job have the opposite effect. Travel time to different activities have little effect on the total leisure tim
The recurrence time for ergodic systems with infinite invariant measures
No full textWe investigate quantitative recurrence in systems having an infinite invariant measure. We extend the Ornstein–Weiss theorem for a general class of infinite systems estimating return time in decreasing sequences of cylinders. Then we restrict to a class of one-dimensional maps with indifferent fixed points and calculate quantitative recurrence in sequences of balls, obtaining that this is related to the behaviour of the map near the fixed points
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Determination of optimum condition for PIN-type amorphous silicon solar cells deposited by RF glow discharge decomposition
No full text학위논문(석사) - 한국과학기술원 : 물리학과, 1984.2, [ vi, 36 p. ]한국과학기술원 : 물리학과
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