CAPT를 위한 발음 변이 분석 및 CycleGAN 기반 피드백 생성

학위논문(박사)--서울대학교 대학원 :인문대학 협동과정 인지과학전공,2020. 2. 정민화.Despite the growing popularity in learning Korean as a foreign language and the rapid development in language learning applications, the existing computer-assisted pronunciation training (CAPT) systems in Korean do not utilize linguistic characteristics of non-native Korean speech. Pronunciation variations in non-native speech are far more diverse than those observed in native speech, which may pose a difficulty in combining such knowledge in an automatic system. Moreover, most of the existing methods rely on feature extraction results from signal processing, prosodic analysis, and natural language processing techniques. Such methods entail limitations since they necessarily depend on finding the right features for the task and the extraction accuracies. This thesis presents a new approach for corrective feedback generation in a CAPT system, in which pronunciation variation patterns and linguistic correlates with accentedness are analyzed and combined with a deep neural network approach, so that feature engineering efforts are minimized while maintaining the linguistically important factors for the corrective feedback generation task. Investigations on non-native Korean speech characteristics in contrast with those of native speakers, and their correlation with accentedness judgement show that both segmental and prosodic variations are important factors in a Korean CAPT system. The present thesis argues that the feedback generation task can be interpreted as a style transfer problem, and proposes to evaluate the idea using generative adversarial network. A corrective feedback generation model is trained on 65,100 read utterances by 217 non-native speakers of 27 mother tongue backgrounds. The features are automatically learnt in an unsupervised way in an auxiliary classifier CycleGAN setting, in which the generator learns to map a foreign accented speech to native speech distributions. In order to inject linguistic knowledge into the network, an auxiliary classifier is trained so that the feedback also identifies the linguistic error types that were defined in the first half of the thesis. The proposed approach generates a corrected version the speech using the learners own voice, outperforming the conventional Pitch-Synchronous Overlap-and-Add method.외국어로서의 한국어 교육에 대한 관심이 고조되어 한국어 학습자의 수가 크게 증가하고 있으며, 음성언어처리 기술을 적용한 컴퓨터 기반 발음 교육(Computer-Assisted Pronunciation Training; CAPT) 어플리케이션에 대한 연구 또한 적극적으로 이루어지고 있다. 그럼에도 불구하고 현존하는 한국어 말하기 교육 시스템은 외국인의 한국어에 대한 언어학적 특징을 충분히 활용하지 않고 있으며, 최신 언어처리 기술 또한 적용되지 않고 있는 실정이다. 가능한 원인으로써는 외국인 발화 한국어 현상에 대한 분석이 충분하게 이루어지지 않았다는 점, 그리고 관련 연구가 있어도 이를 자동화된 시스템에 반영하기에는 고도화된 연구가 필요하다는 점이 있다. 뿐만 아니라 CAPT 기술 전반적으로는 신호처리, 운율 분석, 자연어처리 기법과 같은 특징 추출에 의존하고 있어서 적합한 특징을 찾고 이를 정확하게 추출하는 데에 많은 시간과 노력이 필요한 실정이다. 이는 최신 딥러닝 기반 언어처리 기술을 활용함으로써 이 과정 또한 발전의 여지가 많다는 바를 시사한다. 따라서 본 연구는 먼저 CAPT 시스템 개발에 있어 발음 변이 양상과 언어학적 상관관계를 분석하였다. 외국인 화자들의 낭독체 변이 양상과 한국어 원어민 화자들의 낭독체 변이 양상을 대조하고 주요한 변이를 확인한 후, 상관관계 분석을 통하여 의사소통에 영향을 미치는 중요도를 파악하였다. 그 결과, 종성 삭제와 3중 대립의 혼동, 초분절 관련 오류가 발생할 경우 피드백 생성에 우선적으로 반영하는 것이 필요하다는 것이 확인되었다. 교정된 피드백을 자동으로 생성하는 것은 CAPT 시스템의 중요한 과제 중 하나이다. 본 연구는 이 과제가 발화의 스타일 변화의 문제로 해석이 가능하다고 보았으며, 생성적 적대 신경망 (Cycle-consistent Generative Adversarial Network; CycleGAN) 구조에서 모델링하는 것을 제안하였다. GAN 네트워크의 생성모델은 비원어민 발화의 분포와 원어민 발화 분포의 매핑을 학습하며, Cycle consistency 손실함수를 사용함으로써 발화간 전반적인 구조를 유지함과 동시에 과도한 교정을 방지하였다. 별도의 특징 추출 과정이 없이 필요한 특징들이 CycleGAN 프레임워크에서 무감독 방법으로 스스로 학습되는 방법으로, 언어 확장이 용이한 방법이다. 언어학적 분석에서 드러난 주요한 변이들 간의 우선순위는 Auxiliary Classifier CycleGAN 구조에서 모델링하는 것을 제안하였다. 이 방법은 기존의 CycleGAN에 지식을 접목시켜 피드백 음성을 생성함과 동시에 해당 피드백이 어떤 유형의 오류인지 분류하는 문제를 수행한다. 이는 도메인 지식이 교정 피드백 생성 단계까지 유지되고 통제가 가능하다는 장점이 있다는 데에 그 의의가 있다. 본 연구에서 제안한 방법을 평가하기 위해서 27개의 모국어를 갖는 217명의 유의미 어휘 발화 65,100개로 피드백 자동 생성 모델을 훈련하고, 개선 여부 및 정도에 대한 지각 평가를 수행하였다. 제안된 방법을 사용하였을 때 학습자 본인의 목소리를 유지한 채 교정된 발음으로 변환하는 것이 가능하며, 전통적인 방법인 음높이 동기식 중첩가산 (Pitch-Synchronous Overlap-and-Add) 알고리즘을 사용하는 방법에 비해 상대 개선률 16.67%이 확인되었다.Chapter 1. Introduction 1 1.1. Motivation 1 1.1.1. An Overview of CAPT Systems 3 1.1.2. Survey of existing Korean CAPT Systems 5 1.2. Problem Statement 7 1.3. Thesis Structure 7 Chapter 2. Pronunciation Analysis of Korean Produced by Chinese 9 2.1. Comparison between Korean and Chinese 11 2.1.1. Phonetic and Syllable Structure Comparisons 11 2.1.2. Phonological Comparisons 14 2.2. Related Works 16 2.3. Proposed Analysis Method 19 2.3.1. Corpus 19 2.3.2. Transcribers and Agreement Rates 22 2.4. Salient Pronunciation Variations 22 2.4.1. Segmental Variation Patterns 22 2.4.1.1. Discussions 25 2.4.2. Phonological Variation Patterns 26 2.4.1.2. Discussions 27 2.5. Summary 29 Chapter 3. Correlation Analysis of Pronunciation Variations and Human Evaluation 30 3.1. Related Works 31 3.1.1. Criteria used in L2 Speech 31 3.1.2. Criteria used in L2 Korean Speech 32 3.2. Proposed Human Evaluation Method 36 3.2.1. Reading Prompt Design 36 3.2.2. Evaluation Criteria Design 37 3.2.3. Raters and Agreement Rates 40 3.3. Linguistic Factors Affecting L2 Korean Accentedness 41 3.3.1. Pearsons Correlation Analysis 41 3.3.2. Discussions 42 3.3.3. Implications for Automatic Feedback Generation 44 3.4. Summary 45 Chapter 4. Corrective Feedback Generation for CAPT 46 4.1. Related Works 46 4.1.1. Prosody Transplantation 47 4.1.2. Recent Speech Conversion Methods 49 4.1.3. Evaluation of Corrective Feedback 50 4.2. Proposed Method: Corrective Feedback as a Style Transfer 51 4.2.1. Speech Analysis at Spectral Domain 53 4.2.2. Self-imitative Learning 55 4.2.3. An Analogy: CAPT System and GAN Architecture 57 4.3. Generative Adversarial Networks 59 4.3.1. Conditional GAN 61 4.3.2. CycleGAN 62 4.4. Experiment 63 4.4.1. Corpus 64 4.4.2. Baseline Implementation 65 4.4.3. Adversarial Training Implementation 65 4.4.4. Spectrogram-to-Spectrogram Training 66 4.5. Results and Evaluation 69 4.5.1. Spectrogram Generation Results 69 4.5.2. Perceptual Evaluation 70 4.5.3. Discussions 72 4.6. Summary 74 Chapter 5. Integration of Linguistic Knowledge in an Auxiliary Classifier CycleGAN for Feedback Generation 75 5.1. Linguistic Class Selection 75 5.2. Auxiliary Classifier CycleGAN Design 77 5.3. Experiment and Results 80 5.3.1. Corpus 80 5.3.2. Feature Annotations 81 5.3.3. Experiment Setup 81 5.3.4. Results 82 5.4. Summary 84 Chapter 6. Conclusion 86 6.1. Thesis Results 86 6.2. Thesis Contributions 88 6.3. Recommendations for Future Work 89 Bibliography 91 Appendix 107 Abstract in Korean 117 Acknowledgments 120Docto

DHPV의 노화성 근감소 억제 및 근육분화 촉진 효능

학위논문 (석사)-- 서울대학교 대학원 : 농업생명과학대학 농생명공학부, 2018. 2. 이기원.Procyanidins have many health benefits. After intake, procyanidins are degraded into small metabolites by gastrointestinal microorganisms. According to a previous study, 5-(3',4-Dihydroxyphenyl)-γ-valerolactone is the most abundant among these metabolites. The object of this study is to determine the effects of DHPV on muscle and whether DHPV could recover aged muscle to normal. TGF-β is connected to muscle aging and attenuates the muscle differentiation and inhibits myogenesis. In this study, I measured myoD, myogenin, and the myosin heavy chain expression level to determine whether DHPV improved the myogenesis of C2C12, which had been inhibited by a TGF-β treatment. The results show that the RNA and protein expression level of these 3 biomarkers increases in the DHPV treated group in comparison to TGF-β only treated. In addition, DHPV modulated the TGF-β signaling pathway and C2C12 myogenesis by regulating p-smad2/3, p-JNK, p-ERK and p-p38 expression. Taken together, it may be suggested that DHPV is an ideal therapeutic candidate for recovering myogenesis and muscle differentiation evoked by aging.I. INTRODUCTION 1 II. MATERLIALS AND METHODS 4 1. Chemicals and reagents 4 2. Cell culture and treatments 5 3. Sulforhodamine B assay 6 4. Hematoxylin and Eosin staining (H&E staining) 6 5. Western blot assay 7 6. Real-time quantitative PCR 8 7. Statistical analysis 10 III. RESULTS 11 1. DHPV promotes myotube formation and has no toxic effect on C2C12 murine myoblasts 11 2. DHPV improves the myoD expression compared to TGF-β treatment 15 3. DHPV up-regulates the expression of myogenin in spite of TGF-β treatment on C2C12 myoblasts 19 4. DHPV treatment counteracts the inhibition of myosin heavy chain expression induced by TGF-β 22 5. DHPV donw-regulates p-smad2/3 expressions even in TGF-β treated group 26 6. The summary of the myogenic role of DHPV on C2C 12 myogenesis against TGF-β 29 IV. DISCUSSION 30 V. REFERENCES 34 VI. 국문 초록 38Maste

Why has Financial Reporting Become More Conservative over Time?

학위논문 (석사)-- 서울대학교 대학원 : 경영학과, 2015. 2. 황이석.Accounting conservatism has significantly increased over the last several decades, but little is known about causes for these changes. I find that the overall increase in conservatism is largely driven by a subset of young firms rather than old firms in the firm population. I then examine whether the different conservatism trends between old and young firms are due to changes in accounting standards, changes in demand for conservatism, or changes in firms economic environments. My evidence suggests that the adoption of new accounting standards is responsible for changes in conservatism as most prior studies expect, but changes in demand for conservatism driven by the passage of regulations also play an important role in explaining conservatism trends. In contrast, changes in economic environments seem to have had little effect on conservatism.1. INTRODUCTION 2. CHANGES IN THE ACCOUNTING CONSERVATISM 3. WHO DRIVES THE OVERALL TREND IN CONSERVATISM? 4. EXPLANATIONS FOR THE DIFFERENT CONSERVATISM TREND BETWEEN OLD AND YOUNG FIRMS 4.1 Three possible sources of the changes in conservatism 4.2 Changes in accounting standards and changes in the demand for conservatism 4.3 Changes in firms economic environments 5. CONCLUSION REFERENCES APPENDIXMaste

Thrombolytic Effects of the Snake Venom Disintegrin Saxatilin Determined by Novel Assessment Methods: A FeCl3-Induced Thrombosis Model in Mice.

Saxatilin, a novel disintegrin purified and cloned from the venom of the Korean snake Gloydius saxatilis, strongly inhibits activation and aggregation of platelets. Glycoprotein (GP) IIb/IIIa receptor antagonists can resolve thrombus, so saxatilin might also have thrombolytic effects. We investigated the thrombolytic effects of saxatilin in mice using a ferric chloride-induced carotid arterial thrombosis model. Thrombotic occlusion and thrombus resolution were evaluated quantitatively by measuring blood flow in the carotid artery with an ultrasonic flow meter and calculating the degree of flow restoration on a minute-by-minute basis; results were confirmed by histological examination. Saxatilin dissolved thrombi in a dose-dependent manner. Saxatilin at 5 mg/kg restored blood flow to baseline levels. As saxatilin dose increased, time to recanalization decreased. A bolus injection of 10% of a complete dose with continuous infusion of the remaining dose for 60 minutes resulted in effective recanalization without reocclusion. The thrombolytic effect of saxatilin was also demonstrated in vitro using platelet aggregometry by administering saxatilin in preformed thrombi. Bleeding complications were observed in 2 of 71 mice that received saxatilin. Fibrin/fibrinogen zymography and platelet aggregometry studies indicated that saxatilin does not have fibrinolytic activity, but exerted its action on platelets. Integrin-binding assays showed that saxatilin inhibited multiple integrins, specifically α2bβ3 (GP IIb/IIIa), α5β1, αvβ3, αvβ1, and αvβ5, which act on platelet adhesion/aggregation. Saxatilin inhibited multiple integrins by acting on platelets, and was safe and effective in resolving thrombi in mice.ope

기업 자본조달 의사결정 및 회계보수주의에 관한 연구

학위논문(박사)--서울대학교 대학원 :경영대학 경영학과,2019. 8. 황이석.본 논문은 기업의 자본조달 의사결정과 회계보수주의에 대한 두 개의 독립적인 논문으로 구성되어 있다. 첫 번째 논문은 기업의 성장성에 대한 불확실성이 부채와 자기자본의 가치평가를 매개로 하여 기업의 자본조달 의사결정에 미치는 영향에 대하여 연구하였다. 효율적 시장에 대한 가정에 기반한 가치평가모형에 따르면, 높은 불확실성은 주식의 볼록성으로 인해 자기자본의 가치를 높이는 반면, 부채의 오목성으로 인해 부채의 가치는 떨어뜨린다. 이러한 관계는 정보 비대칭이나 가치평가오류가 존재하지 않는 경우에도 성립한다. 이로 인해 불확실성은 자기자본조달의 상대적 매력도를 높여 궁극적으로 기업의 자본조달 의사결정에 영향을 미칠 수 있다. 1980년부터 2017년까지 외부자본을 조달한 미국 기업을 대상으로 분석한 결과, 기대 불확실성이 높은 기업은 타인자본보다는 자기자본 조달을 선호하며, 자기자본 조달액은 더 높으나 타인자본 조달액은 더 낮은 것으로 나타났다. 이러한 효과는 주식과 부채의 비선형성이 두드러지는 기업에서 더욱 강하게 나타났다. 본 연구 결과는 자본조달비용, 가치평가오류, 재무적 곤경과 같은 대체적인 요인에 의해 설명되지 않았다. 이러한 결과들은 기업이 예상되는 불확실성에 따라 자본조달 구조를 조정하며, 그 주된 원인이 불확실성이 주식 및 부채의 가치평가에 미치는 영향임을 시사한다. 두 번째 논문은 회계 보수주의가 지난 몇십 년 동안 변화한 원인에 대하여 연구하였다. 논문의 첫 번째 부분에서는 먼저 회계 보수주의의 특성이 1981년부터 2017년까지 어떻게 변하였는지 연구하였다. 그 결과, 선행연구가 제시한 결과와 일관되게 보수주의가 유의하게 증가하였음을 발견하였으며, 동 증가가 영업현금흐름이 아닌 발생액 항목에, 영업손익이 아닌 비영업손익 항목에 기인하는 것으로 나타났다. 또한, 보수주의의 증가는 표본에 새롭게 편입된 새로운 기업들에 기인하는 것으로 나타났다. 논문의 두 번째 부분에서는 이러한 변화가 나타난 원인에 대하여 연구하였다. 구체적으로, 성숙기업과 새로운 기업이 서로 다른 보수주의 추세를 보이는 원인을 식별하고자 하였다. 분석 결과, 선행연구의 예측대로 회계기준의 변화가 보수주의의 변화, 특히 그 증가추세와 유의한 관련성을 보였다. 이와 더불어 제도 변화로 촉발된 보수주의에 대한 수요 변화 역시 보수주의의 추세를 설명하는데 중요한 요인으로 확인되었는데, 일부 기간에는 이러한 요인이 회계기준의 효과를 완전히 상쇄하기도 하였다. 반면, 기업의 경제적 환경 변화는 보수주의의 변화를 초래한 주된 원인은 아닌 것으로 나타났다.This dissertation is comprised of two essays on corporate financing choices and accounting conservatism. The first essay, entitled Growth Uncertainty and the Choice between Debt and Equity: A Valuation Perspective, examines the effect of uncertainty about firms growth on financing decisions through its effect on debt and equity valuations. According to the rational asset pricing model, higher uncertainty contributes to higher equity valuations (lower debt valuations) due to the convexity (concavity) in equity (debt) value, even in the absence of asymmetric information or mispricing. This increases the relative attractiveness of equity financing, potentially affecting firms financing choices. Analyzing firms raising external capital during the period 1980-2017, I find that firms with higher expected uncertainty are more likely to issue equity as opposed to debt and raise larger amount of equity financing and smaller amount of debt financing. Consistent with a valuation channel, the effect is more pronounced for firms predicted to have greater nonlinearities in equity and debt values. Investigating several alternative explanations, I show that my main findings are not likely to be explained by cost of capital, mispricing, or financial distress channel. Overall, I provide evidence that firms adjust their financing structures in response to the level of uncertainty expected to exist, since uncertainty has differential effects on equity and debt valuations. The second essay, entitled The Changing Properties of Accounting Conservatism: Why Has Financial Reporting Become More Conservative?, investigates causes for the over-time change in accounting conservatism. In the first part of the paper, I investigate how the properties of accounting conservatism have changed for the period 1981-2017. I find that conservatism has substantially increased over time as prior studies document, and that this increase is primarily driven by the increase in the asymmetric timeliness of accruals rather than cash flow from operations, and by the increased recognition of non-operating expenses. Moreover, the increasing trend in conservatism is largely led by young firms that are newly incorporated into the sample. In the second part of the paper, I examine what causes the change in conservatism by investigating the source of different conservatism trends observed for old and young firms. My findings suggest that changes in accounting standards account for the change, especially an increase, in conservatism as most prior studies expect, but changes in demand for conservatism caused by the introduction of related regulations also play an important role, even offsetting the effect of accounting standards in some years. In contrast, changes in economic environments do not seem to be the major source of time-series variation in conservatism.Essay 1. Growth Uncertainty and the Choice between Debt and Equity: A Valuation Perspective 1 1. Introduction . 2 2. Literature Review and Hypothesis Development . 6 2.1. Literature Review . 6 2.1.1. Value Implications of Economic Uncertainty . 7 2.1.2. The Determinants of Corporate Financing Decisions 9 2.2. Hypothesis Development 12 3. Research Design 14 3.1. Sample 14 3.2. Measuring Growth Uncertainty 15 3.3. External Financing Decisions . 16 4. Empirical Results 18 4.1. Descriptive Statistics 18 4.2. The Average Effect of Growth Uncertainty on Financing Choices 19 4.3. The Valuation Channel 21 4.3.1. Growth Uncertainty and Valuations of Equity and Debt 21 4.3.2. The Role of Convexity (Concavity) of Equity (Debt) Value in the Relation between Growth Uncertainty and Financing Choices 25 4.4. Alternative Explanations . 28 4.4.1. Cost of Capital 29 4.4.2. Mispricing . 31 4.4.3. Financial Distress . 33 5. Additional Analyses 34 5.1. Frequent Issuers vs. One-Time Issuers . 34 5.2. The Effect of Macro Uncertainty 35 5.3. The Use of Cash Proceeds from External Financing 37 5.4. Alternative Proxies for Growth Uncertainty . 38 6. Conclusions . 39 References . 41 Appendix . 86 Essay 2. The Changing Properties of Accounting Conservatism: Why Has Financial Reporting Become More Conservative 90 1. Introduction . 91 2. Changes in the Accounting Conservatism . 97 2.1. Overall Trends in Accounting Conservatism 97 2.2. Changing Properties of Accounting Conservatism . 99 2.2.1. Asymmetric Timeliness of Earnings in Reflecting Current and Past News 100 2.2.2. Asymmetric Timeliness of Various Components of Earnings. 102 2.2.3. Changes in the Sample Composition. 106 3. Why Has Financial Reporting Become More Conservative . 109 3.1. Three Possible Sources of the Changes in Conservatism . 109 3.2. Changes in Accounting Standards and Demand for Conservatism 110 3.3. Changes in Firms Economic Environments 118 4. Additional Analyses 120 4.1. Changes in Firm Characteristics . 120 4.2. Confounding Effect of Cost Stickiness . 122 4.3. Non-Linearity in the Asymmetric Timeliness of Earnings . 123 5. Conclusions . 125 References . 127 Appendix . 164Docto

운동지속 임계속도를 이용한 풀링훈련이 견관절의 등속성 회전력과 2,000m 수영능력에 미치는 영향

학위논문(석사)--서울대학교 대학원 :체육교육과,1998.Maste

The Effects of Learner Centered Instruction in Nursing: A Meta-Analysis

본 연구는 간호학 분야 학습자 중심 수업의 효과를 알아보기 위해 문제중심학습, 액션러닝, 플립러닝, 팀 기반 학습을 적용한 연구 84편을 대상으로 메타분석을 실시하였다. 연구결과, 간호학 분야 학습자 중심 수업의 전체 효과크기는 0.624로 나타났다. 이는 학습자 중심 수업이 중간 효과크기를 갖고 있음을 의미한다. 수업모형에 따라서는 팀 기반 학습, 액션러닝, 플립러닝, 문제중심학습의 순으로 효과크기가 높게 나타났다. 총 15가지의 종속변인 중 큰 효과크기를 보인 것은 임상수행능력이었다. 간호분야 지식, 창의성, 자기주도학습, 의사소통능력, 대인관계능력, 문제해결력, 비판적 사고 등의 종속변수에서는 중간 효과크기가 나타났다. 종속변수를 세 가지 영역으로 묶었을 때, 전공능력의 효과크기가 가장 컸으며, 개인역량과 학습태도의 순으로 효과가 있었다. 이 밖에도 학습자 중심 수업의 운영 방법과 관련된 조절변수에 따른 효과크기의 차이를 살펴보았다. 본 연구를 통해 전통적 교수자 중심 수업보다 학습자 중심 수업이 더 효과적임을 알 수 있다. 이에 본 연구의 결과를 바탕으로 학습자 중심의 새로운 교육방법을 적용하기를 제안하였다.The purpose of this study is to analyze the effect of learner centered instruction in the nursing field by using meta-analysis of 84 studies with problem based learning, action learning, flipped learning, and team based learning. As a result, the total effect size of learner centered class in nursing was 0.624. This means that learner centered instruction has a medium effect size. According to the instructional model, the effect size was higher in order of team based learning, action learning, flipped learning, and problem based learning. Among the total 15 dependent variables, the greatest effect size was in clinical performance. The medium effect size was in the dependent variables such as nursing knowledge, creativity, self directed learning, communication ability, interpersonal ability, problem solving ability, critical thinking. When the dependent variables were grouped into three domains, the effect size of the major competency was the largest, followed by the individual competency and the learning attitude. In addition, we examined the effect sizes of the moderate variables in learner centered instruction. This study shows that learner centered instruction is more effective than traditional teacher centered instruction. Based on the results of this study, we propose applying a new method of learner centered education

중국인 학습자의 한국어 분절음 변이양상과 발음모델링

학위논문 (석사)-- 서울대학교 대학원 : 협동과정 인지과학전공, 2016. 2. 정민화.Learners of second foreign language stand to benefit greatly from Computer-Assisted Pronunciation Training (CAPT) systems which can offer automatic mispronunciation detection and individualized corrective feedback. The increasing demand for learning Korean as a foreign language yields a strong need for a Korean CAPT system development. However, recognition accuracy for non-native speech is often too low to make practical use of Automatic Speech Recognition (ASR) technology in language learning interfaces, and there is limited research on Koran pronunciation produced by non-natives. As a preliminary research towards developing a CAPT system for Mandarin Chinese learners of Korean, the first part of the study surveys major agreements and disagreements among related works. By conducting a corpus-based experiment, these disagreements are resolved and segmental variations patterns are analyzed, in which flap sounds show the highest variation rate of 35%. The second part of this study discusses quantitative modeling of these variation patterns for adapting Korean ASR system to Chinese learners. Using context-dependent variation rules describing substitutions, insertions, deletions, and phonological knowledge, extended pronunciation dictionary is generated. With the proposed approach, 21.2% and 1.3% relative WER reduction is obtained from consonantal and vocalic models. The result verifies the corpus-based variation pattern analysis. This study lays the groundwork for Korean CAPT system for various linguistic backgrounds.컴퓨터기반 발음교육 (Computer-Assisted Pronunciation Training, CAPT) 시스템은 학습자의 발음오류를 자동으로 인식 및 검출하고 개인화된 교정 피드백을 제공함으로써, 효율적인 제 2외국어 학습을 제공한다. 최근 증가하는 한국어 교육에 대한 수요는 한국어 CAPT 시스템 개발의 필요성을 의미한다. 그러나, 비원어민 한국어 발화에 대한 연구는 부족한 실정이며, 학습자의 발음에 대한 비원어민 음성인식 성능이 향상됨으로써 학습 인터페이스에 구현이 가능할 것이다. 중국인 학습자를 위한 한국어 CAPT 시스템 개발의 초기 연구로써, 본고의 초반부는 선행연구 실험결과의 일치 및 불일치 양상을 정리한다. 그리고, 코퍼스 기반 실험을 진행하여 불일치 양상을 해소하여 주요 변이양상을 분석한다. 본 연구의 실험결과 탄설음의 설측음화 변이율이 35%로 가장 높게 나타났다. 본고의 후반부는 발음모델링과 음성인식 실험결과를 제시한다. 정량화된 변이양상의 문맥을 고려하여 대치, 삽입, 삭제, 음운변동 패턴규칙으로 구분하였다. 이 규칙을 사용하여 확장된 발음열을 구축하여 인식 실험을 진행하였다. 이 방법으로 자음 및 모음 모델에서 상대 인식률 21.2%과 1.3%의 개선이 각각 확인되었다. 인식실험 결과는 코퍼스 기반 변이양상 분석 결과와 발음모델링 기법을 검증한다.1. Introduction 6 1.1. Purpose of Research 7 1.2. Research Scope 9 1.3. Outline of Research 9 2. Survey of Related Work 10 2.1. Contrastive Analysis of Chinese and Korean 10 2.2. Survey of Previous Studies 13 3. Segmental Variations Produced by Chinese Learners 21 3.1. Experiment Design for Corpus-based Analysis 21 3.2. Experiment Results 24 3.3. Comparison with the Related Works 26 3.4. Analysis of Frequent Segmental Variations 28 4. Modeling Pronunciation Variation for Speech Recognition 31 4.1. Rule Derivation 32 4.2 Dictionary Generation 35 4.3 Speech Recognition Experiment 36 4.4 Speech Recognition Result and Discussion 37 5. Conclusion 43 References 45 Appendix 48 국문초록 57Maste

Role of tumour necrosis factor receptor-1 and nuclear factor-κB in production of TNF-α-induced pro-inflammatory microparticles in endothelial cells

Tumour necrosis factor-α (TNF-α) is upregulated in many inflammatory diseases and is also a potent agent for microparticle (MP) generation. Here, we describe an essential role of TNF-α in the production of endothelial cell-derived microparticles (EMPs) in vivo and the function of TNF-α-induced EMPs in endothelial cells. We found that TNF-α rapidly increased blood levels of EMPs in mice. Treatment of human umbilical vein endothelial cells (HUVECs) with TNF-α also induced EMP formation in a time-dependent manner. Silencing of TNF receptor (TNFR)-1 or inhibition of the nuclear factor-κB (NF-κB) in HUVECs impaired the production of TNF-α-induced EMP. Incubation of HUVECs with PKH-67-stained EMPs showed that endothelial cells readily engulfed EMPs, and the engulfed TNF-α-induced EMPs promoted the expression of pro-apoptotic molecules and upregulated intercellular adhesion molecule-1 level on the cell surface, which led to monocyte adhesion. Collectively, our findings indicate that the generation of TNF-α-induced EMPs was mediated by TNFR1 or NF-κB and that EMPs can contribute to apoptosis and inflammation of endothelial cells.ope

Plasma osteoprotegerin levels increase with the severity of cerebral artery atherosclerosis

OBJECTIVES: Osteoprotegerin (OPG) is a member of the tumor necrosis factor receptor superfamily and suggested as a marker of atherosclerosis. We investigated whether plasma OPG levels were associated with the presence and severity of cerebral atherosclerosis. DESIGN AND METHODS: We used an enzyme-linked immunosorbent assay to measure the plasma OPG levels of 107 patients with acute cerebral infarction. We compared the plasma OPG levels according to the presence and number of arteries with cerebral atherosclerosis (≥ 50% stenosis). RESULTS: Of 107 patients, 73 (68.2%) had cerebral atherosclerosis. OPG levels were increased in patients with cerebral atherosclerosis (374.69 ± 206.48 vs 261.17 ± 166.91 pg/mL, p=0.006). OPG levels showed positive correlation with the number of cerebral arteries with atherosclerosis (Spearman's rho=0.342, p229.9 pg/mL was independently associated with the presence [OR 4.61, 95% CI 1.57-13.55, p=0.005, binary logistic regression] of cerebral atherosclerosis and number [OR 3.20, 95% CI 1.26-8.12, p=0.014, ordinal logistic regression] of arteries with cerebral atherosclerosis. CONCLUSIONS: Plasma OPG levels were significantly associated with the presence and severity of cerebral atherosclerosis. This finding suggests that plasma OPG might have a role in cerebral atherosclerosis.ope