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

코발트 산화물 박막의 상 변화 제어 및 Co3O4 박막의 산소 빈자리 조절

학위논문(석사) -- 서울대학교대학원 : 자연과학대학 물리·천문학부(물리학전공), 2022.2. 노태원.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 CoAl2O¬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 2θ-θ 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.코발트 산화물은 촉매, 초전도성 스피넬 산화물 이종구조, 강자성까지 폭넓게 응용되어 많은 관심을 받고 있습니다. 최근 Lado et al. 은 2차원 위상 초전도 위상을 구축하기 위한 대안으로 3차원 반강자성체를 사용하여 2차원 위상 초전도 상태 구현에 대한 이론적 예측을 했다. 이론적 예측에 따르면 2차원 초전도 상태는 BCS 초전도체와 위상학적으로 사소한 반강자성체 사이의 경계면에서 나타난다. 앞서 언급한 논문에서는 CoAl2O4가 위상적으로 사소한 반강자성체의 후보로 제안되었으나, 이 재료는 저온에서 스핀 좌절을 나타내는 문제가 있어 반강자성 배열을 방해할 수 있다. 이에 따라 나는 대안적인 반강자성 물질로 스핀 좌절이 덜 나타나는 Co3O4를 제시하고자 한다. Co3O4 박막의 섬세한 에피택셜 성장 제어 방법을 도입하는 것은 이종 구조의 계면에서 위상 초전도성에 대한 추가 연구를 위한 필수 단계이다. 2차원 영역에서 Co3O4의 위상 초전도성은 아직 확인되지 않았지만 이 물질은 산화물 초전도성의 새로운 장을 열 수 있다. 이 시스템의 산소 결핍 제어는 본질적으로 애플리케이션과 관련이 있다. Matsuda et al.의 최근 보고서에 따르면 Co3O4 필름이 상온에서도 높은 에피택셜 품질로 성장될 수 있다는 주장이 제시되었다. 그러나 그들이 상온에서 성장한 Co3O4 박막은 산소 결손이 많다는 사실을 알게 되었고 박막의 산소 결손 형성과 상전이에 대한 추가적인 연구가 필요하다고 판단된다. 이 학위논문에서 나는 CoO, Co3O4, 산소가 결핍된 Co3O4 및 미정의 산화코발트 화합물을 포함하는 산화코발트 박막의 상전이를 확인하기 위해 XRD 2θ-θ 스캔 및 필름의 분광 타원법으로 광전도도를 측정했다. 코어 레벨 XPS 측정은 산소 결손량에 대한 정량적 정보를 제공하기 위해 측정되었다. 산소 분압 및 성장 온도의 분별 성장 조건에서 산화 코발트 박막의 성장도 수행되었다. XRD, XPS 및 Ellipsometry의 종합된 분석을 기반으로 산소 화학량론 제어가 가능한 산화 코발트 박막의 상세한 성장 다이어그램을 제시하고자 한다. 나는 내 연구가 이 시스템에 대한 에피택셜 성장 박막 연구를 위한 기본적인 지침을 제공할 것이라고 믿는 바이다.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 국문 초록 (Korean Abstract) 33석

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