8,050 research outputs found
Baseline CNN structure analysis for facial expression recognition
We present a baseline convolutional neural network (CNN) structure and image
preprocessing methodology to improve facial expression recognition algorithm
using CNN. To analyze the most efficient network structure, we investigated
four network structures that are known to show good performance in facial
expression recognition. Moreover, we also investigated the effect of input
image preprocessing methods. Five types of data input (raw, histogram
equalization, isotropic smoothing, diffusion-based normalization, difference of
Gaussian) were tested, and the accuracy was compared. We trained 20 different
CNN models (4 networks x 5 data input types) and verified the performance of
each network with test images from five different databases. The experiment
result showed that a three-layer structure consisting of a simple convolutional
and a max pooling layer with histogram equalization image input was the most
efficient. We describe the detailed training procedure and analyze the result
of the test accuracy based on considerable observation.Comment: 6 pages, RO-MAN2016 Conferenc
μ½λ°νΈ μ°νλ¬Ό λ°λ§μ μ λ³ν μ μ΄ λ° Co3O4 λ°λ§μ μ°μ λΉμ리 μ‘°μ
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Όλ¬Έ(μμ¬) -- μμΈλνκ΅λνμ : μμ°κ³Όνλν 물리·μ²λ¬ΈνλΆ(물리νμ 곡), 2022.2. λ
Ένμ.Cobalt oxides have attracted much attention because of its wide application for catalyst, superconducting spinel oxide heterostructure, and even ferromagnetism. Recently, Lado et al. [1] made a theoretical prediction on realization of 2D topological superconducting state utilizing a class of 3D antiferromagnets as an alternative way to build a 2D topological superconducting phase. According to its theoretical prediction, the 2D superconducting state appears at the interface between a BCS superconductor and a topologically trivial antiferromagnet. Tough CoAl2OΒ¬4 was suggested in the above-mentioned paper as a candidate for the topologically trivial antiferromagnet, this material has some issue about showing spin frustration at low temperature which means it may disturb its antiferromagnetic ordering. Here I suggest an alternative antiferromagnetic material; Co3O4 which shows less spin frustration and introduce a way of delicate epitaxial growth control of Co3O4 thin films which is essential step for further study on topological superconductivity at the interface of heterostructure. Though the topological superconductivity of Co3O4 in two-dimensional area has not been confirmed, this material may open a new playground for oxide superconductivity.
Control of oxygen vacancy in this system is essentially related for the application. According to a recent report by Matsuda et al., [2] assertion that Co3O4 films can be grown in high epitaxial quality at room temperature was given. However, I found that Co3O4 films grown at room temperature have lots of oxygen vacancies, further research on the oxygen vacancy formation in thin films and phase transition is required. Here, I measured XRD 2ΞΈ-ΞΈ scans and optical conductivity by spectroscopic ellipsometry of the films to verify phase transition of cobalt oxide films including CoO, Co3O4, oxygen vacant Co3O4, and undefined cobalt oxide compound. Core level XPS measurement is provided to give quantitative information on the amount of oxygen vacancies. Growth of cobalt oxide thin films under fractionized growth conditions of oxygen partial pressure and growth temperature have also been performed. Based on the combining analysis by XRD, XPS, and Ellipsometry, I provide a detailed growth diagram of cobalt oxide thin films with oxygen stoichiometry control. I believe my work will provide fundamental guidance for the epitaxially grown thin film study on this system.μ½λ°νΈ μ°νλ¬Όμ μ΄λ§€, μ΄μ λμ± μ€νΌλ¬ μ°νλ¬Ό μ΄μ’
ꡬ쑰, κ°μμ±κΉμ§ νλκ² μμ©λμ΄ λ§μ κ΄μ¬μ λ°κ³ μμ΅λλ€. μ΅κ·Ό Lado et al. μ 2μ°¨μ μμ μ΄μ λ μμμ ꡬμΆνκΈ° μν λμμΌλ‘ 3μ°¨μ λ°κ°μμ±μ²΄λ₯Ό μ¬μ©νμ¬ 2μ°¨μ μμ μ΄μ λ μν ꡬνμ λν μ΄λ‘ μ μμΈ‘μ νλ€. μ΄λ‘ μ μμΈ‘μ λ°λ₯΄λ©΄ 2μ°¨μ μ΄μ λ μνλ BCS μ΄μ λ체μ μμνμ μΌλ‘ μ¬μν λ°κ°μμ±μ²΄ μ¬μ΄μ κ²½κ³λ©΄μμ λνλλ€. μμ μΈκΈν λ
Όλ¬Έμμλ CoAl2O4κ° μμμ μΌλ‘ μ¬μν λ°κ°μμ±μ²΄μ νλ³΄λ‘ μ μλμμΌλ, μ΄ μ¬λ£λ μ μ¨μμ μ€ν μ’μ μ λνλ΄λ λ¬Έμ κ° μμ΄ λ°κ°μμ± λ°°μ΄μ λ°©ν΄ν μ μλ€. μ΄μ λ°λΌ λλ λμμ μΈ λ°κ°μμ± λ¬Όμ§λ‘ μ€ν μ’μ μ΄ λ λνλλ Co3O4λ₯Ό μ μνκ³ μ νλ€. Co3O4 λ°λ§μ μ¬μΈν μνΌνμ
μ±μ₯ μ μ΄ λ°©λ²μ λμ
νλ κ²μ μ΄μ’
ꡬ쑰μ κ³λ©΄μμ μμ μ΄μ λμ±μ λν μΆκ° μ°κ΅¬λ₯Ό μν νμ λ¨κ³μ΄λ€. 2μ°¨μ μμμμ Co3O4μ μμ μ΄μ λμ±μ μμ§ νμΈλμ§ μμμ§λ§ μ΄ λ¬Όμ§μ μ°νλ¬Ό μ΄μ λμ±μ μλ‘μ΄ μ₯μ μ΄ μ μλ€.
μ΄ μμ€ν
μ μ°μ κ²°ν μ μ΄λ λ³Έμ§μ μΌλ‘ μ ν리μΌμ΄μ
κ³Ό κ΄λ ¨μ΄ μλ€. Matsuda et al.μ μ΅κ·Ό λ³΄κ³ μμ λ°λ₯΄λ©΄ Co3O4 νλ¦μ΄ μμ¨μμλ λμ μνΌνμ
νμ§λ‘ μ±μ₯λ μ μλ€λ μ£Όμ₯μ΄ μ μλμλ€. κ·Έλ¬λ κ·Έλ€μ΄ μμ¨μμ μ±μ₯ν Co3O4 λ°λ§μ μ°μ κ²°μμ΄ λ§λ€λ μ¬μ€μ μκ² λμκ³ λ°λ§μ μ°μ κ²°μ νμ±κ³Ό μμ μ΄μ λν μΆκ°μ μΈ μ°κ΅¬κ° νμνλ€κ³ νλ¨λλ€. μ΄ νμλ
Όλ¬Έμμ λλ CoO, Co3O4, μ°μκ° κ²°νλ Co3O4 λ° λ―Έμ μ μ°νμ½λ°νΈ νν©λ¬Όμ ν¬ν¨νλ μ°νμ½λ°νΈ λ°λ§μ μμ μ΄λ₯Ό νμΈνκΈ° μν΄ XRD 2ΞΈ-ΞΈ μ€μΊ λ° νλ¦μ λΆκ΄ νμλ²μΌλ‘ κ΄μ λλλ₯Ό μΈ‘μ νλ€. μ½μ΄ λ 벨 XPS μΈ‘μ μ μ°μ κ²°μλμ λν μ λμ μ 보λ₯Ό μ 곡νκΈ° μν΄ μΈ‘μ λμλ€. μ°μ λΆμ λ° μ±μ₯ μ¨λμ λΆλ³ μ±μ₯ 쑰건μμ μ°ν μ½λ°νΈ λ°λ§μ μ±μ₯λ μνλμλ€. XRD, XPS λ° Ellipsometryμ μ’
ν©λ λΆμμ κΈ°λ°μΌλ‘ μ°μ ννλλ‘ μ μ΄κ° κ°λ₯ν μ°ν μ½λ°νΈ λ°λ§μ μμΈν μ±μ₯ λ€μ΄μ΄κ·Έλ¨μ μ μνκ³ μ νλ€. λλ λ΄ μ°κ΅¬κ° μ΄ μμ€ν
μ λν μνΌνμ
μ±μ₯ λ°λ§ μ°κ΅¬λ₯Ό μν κΈ°λ³Έμ μΈ μ§μΉ¨μ μ 곡ν κ²μ΄λΌκ³ λ―Ώλ λ°μ΄λ€.List of Figures 3
Abstract 4
Chapter 1. Introduction 5
1.1 spinel oxides
1.2 Oxygen vacancy control of thin films
1.3 Outline of Thesis
Chapter 2. Experimental Methods 8
2.1 Pulsed laser deposition
2.2 Structure and surface characterization
2.3 Spectroscopic measurement
Chapter 3. Results and Discussion 12
3.1 Structural phase transition of cobalt oxide thin films
3.2 Electronic structural transition in cobalt oxides
3.3 Oxygen vacancy dependence of electronic structure in films
3.4 Comprehensive growth phase diagram of cobalt oxide thin films
Chapter 4. Conclusion 28
References 29
κ΅λ¬Έ μ΄λ‘ (Korean Abstract) 33μ
Life-table analysis for correlated response times
Survival data consisting of independent groups of correlated response times arise from a variety of situations, such as event times collected from husband and wife pairs, siblings, litter mates, distinct components of a machine, or repeated measurements on each individual subject. In this dissertation, we restrict our attention to the situations where response times within groups are not distinguishable, and the marginal survival distributions are same for all individuals within any group. Furthermore, the data are interval censored, so exact event times are not observed. Only the number of failures and number of censored individuals are observed within a finite set of time intervals. We are interested in estimating marginal survival probabilities and their variances and covariances from the observed counts. In this situation, distribution-free methods are developed for the situations involving independent groups of correlated response times. This will be referred to as life-table analysis for correlated response times ;In Chapter 2, the product limit (PL) and actuarial life-table (AL) estimates of marginal survival probabilities are defined and a modification of the Greenwood formula is derived for their variances. Large sample properties of the PL and AL estimates are also examined. In Chapter 3, a non-parametric maximum likelihood estimate is developed under the same assumptions used to derive the PL estimate, and it is used to check the relative efficiency of the PL estimate. Results of a simulation study of small sample properties of the PL estimate, AL estimate, and the MLE for marginal survival probabilities are reported in Chapter 4. The effects of the strength of correlation between responses, the level of censoring, the number of time intervals, and sample size are examined. Estimates of variances from the Greenwood formula and the modified Greenwood formulas are compared. Differences between the modified and unmodified Greenwood formula are most greatly affected by the levels of correlation between responses. In Chapter 5, we review tests for the equality of two survival distributions given independent and univariate event times, and develop chi-square tests for testing equality of two survival distributions for the situation involving correlated response times where the entire groups of correlated responses are randomly assigned to treatments. Then, different treatments are applied to different independent sets of subjects. The use of these estimation and testing procedures is illustrated with an analysis of failure times for angioplasty procedures where more than one procedure is performed on some patients
Black Holes in Two Dimensional Dilaton Gravity and Nonlinear Klein-Gordon Soliton
Two-dimensional dilaton gravity coupled to a Klein-Gordon matter field with a
quartic interaction term is considered. The theory has a classical solution
which exhibits black hole formation by a soliton. The geometry of black hole
induced by a soliton is investigated.Comment: 9 pages, no figures, late
A Cost Effective Block Framing Scheme for Underwater Communication
In this paper, the Selective Multiple Acknowledgement (SMA) method, based on Multiple Acknowledgement (MA), is proposed to efficiently reduce the amount of data transmission by redesigning the transmission frame structure and taking into consideration underwater transmission characteristics. The method is suited to integrated underwater system models, as the proposed method can handle the same amount of data in a much more compact frame structure without any appreciable loss of reliability. Herein, the performance of the proposed SMA method was analyzed and compared to those of the conventional Automatic Repeat-reQuest (ARQ), Block Acknowledgement (BA), block response, and MA methods. The efficiency of the underwater sensor network, which forms a large cluster and mostly contains uplink data, is expected to be improved by the proposed method
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