딥러닝을 활용한 시공간 데이터 예측

학위논문(석사) -- 서울대학교대학원 : 자연과학대학 통계학과, 2023. 8. 임채영.크리깅은 관측한 시공간 데이터를 이용해 관측되지 않은 위치를 예측하는 통계적 기법이다. 데이터를 예측하여 보간하는데 시공간 데이터의 시공간 의존성을 이용한다. 그러나 복잡한 데이터의 경우 크리깅은 최적의 예측값이 되지 않을 수 있다. 최근 심층 신경망을 이용한 딥러닝은 많은 분야에서 활용되고 있다. 다층 퍼셉트론을 회귀에 활용할 수 있다는 점을 이용해 본 논문에서는 이 신경망 구조를 이용한 새로운 크리깅 방법을 제안한다. 이 방법은 더 복잡한 시공간 확률 과정을 학습할 수 있다. 그다음, 통계 학습 이론의 관점에서 기존의 크리깅 방법과 제안된 방법을 비교한다. 마지막으로, 실제 한국의 미세먼지 농도 데이터에 제안된 방법을 활용하여 이것의 성능을 평가한다. 여기서 교차 검증 방법을 사용한다.Kriging provides the Best Linear Unbiased Predictor (BLUP) for a spatial data or spatio-temporal data. This is a method of interpolation used to predict spatial process or spatio-temporal process at unobserved locations. However, for complex data, Kriging, the linear predictor, may not be optimal. Nowadays, Deep learning using Deep neural networks (DNNs) is being used in many fields. Deep feedforward networks can be used for regression, so I propose a novel prediction method using DNN structure in this study. This method may learn more complex spatio-temporal dependencies. Next, I study the traditional Kriging and my method in terms of statistical learning theory. Finally, I apply my method to Korea fine dust data to evaluate the performance. Here, the K-fold Cross Validation method for spatio-temporal data is used.Chapter 1 Introduction 1 Chapter 2 Preliminaries 3 2.1 Spatio-Temporal Model 3 2.2 Spatio-Temporal Universal Kriging 4 2.3 Deep Feedforward Networks 6 Chapter 3 The Methodology 9 3.1 Decomposition of the Spatio-Temporal Process 9 3.2 Deep Neural Networks Structure 10 Chapter 4 Theoretical Study 14 4.1 Statistical Learning Theory 14 4.2 Ensemble Method 20 Chapter 5 Application 22 5.1 Detailed Structural Settings 22 5.2 Data Description 23 5.3 Results 26 Chapter 6 Conclusion and Future Work 31 6.1 Conclusion 31 6.2 Future Work 32석

Performance Analysis on Coexistence of LAA and WiFi

학위논문 (석사)-- 서울대학교 대학원 : 공과대학 전기·정보공학부, 2018. 8. 최성현.본 논문에서는 LAA와 WiFi 공존 시뮬레이터를 작성한 방법과 시뮬레이터를 활용하여 LAA와 WiFi 공존 성능을 확인한 것을 다룬다. 시스템 레벨 통신 시뮬레이터인 ns-3의 LTE 모듈 코드를 기반으로 3GPP release 13의 표준 동작을 지키는 LAA 모듈을 작성하였으며, 기존 ns-3에서 LTE와 WiFi 채널이 독립적으로 구현되어 있었으나 이를 수정하여 비면허대역에서 LAA와 WiFi간 통신 간섭이 있을 수 있도록 구현하였다. LAA와 WiFi 공존 성능 확인을 위해 LAA의 에너지 감지 임계값을 표준과 다르게 설정하며 어떤 영향이 있는지 실험하였으며, 그 결과 현재 LAA 에너지 감지 임계값이 WiFi의 에너지 감지 임계값과는 상이하여 비대칭적인 히든 문제가 발생하는 것을 확인하였다. LAA와 WiFi간 채널 접속 방식은 비슷하지만, 근본적인 통신 방식이 서로 달라 전통적인 비대칭적인 히든 상황에서 발생하는 문제 외에도 다른 현상이 있는 점을 발견하였으며 이 점을 본 논문에서 자세히 다루었다.제 1 장 서 론 1 제 2 장 LAA의 동작 방식 2 제 1 절 채널 접속 방식 2 제 2 절 경쟁 윈도우 조절 3 제 3 절 무선 랜 채널 감지 기능 3 제 4 절 다수 반송파 전송 시 채널 접속 방식 4 제 3 장 LAA와 WiFi 공존 시뮬레이터의 구현 6 제 1 절 기존 ns-3의 문제점 6 제 2 절 채널 모델 6 제 3 절 LAA의 매체 접근 제어 모델 7 제 4 절 LAA의 물리 계층 모델 8 제 5 절 LAA 모듈의 구현 8 제 6 절 WiFi 모듈의 구현 12 제 4 장 LAA의 다수 채널 접속 방식에 따른 성능 분석 13 제 1 절 LAA 단일 링크 분석 13 제 2 절 LAA와 WiFi 공존 성능 분석 15 제 3 절 LAA간 채널 접속 방식에 따른 공존 성능 분석 19 제 5 장 LAA의 에너지 감지 임계값 변화에 따른 WiFi와의 공존 성능 분석 23 제 1 절 실험 환경 23 제 2 절 WiFi 네트워크는 항상 전송을 성공하는 환경 24 제 3 절 LAA 네트워크는 항상 전송을 성공하는 환경 34 제 6 장 결론 43 참고 문헌 44 Abstract 45 감사의 글 46Maste

power factor

Maste

Professional Degree System in Institutions of Higher Education

본 연구에서는 우리나라 고등교육 학위 취득자들이 입직교육 후 직업세계로 원활하게 이행하도록 고등직업교육 학위제도를 체계적으로 정비하기 위한 기초 작업을 하고자 하였다. 이를 위한 세부적인 작업은 다음과 같다. 첫째, 우리나라 고등학위제도를 직업교육의 관점에서 조망하고, 둘째, 우리나라 직업학위제도의 문제점을 규명하며, 셋째, 선진 외국의 직업학위제도를 우리나라와 비교하여 시사점을 제시하고, 넷째, 우리나라의 새로운 직업학위제도 구축을 위한 방향을 제시한다.In the Korean higher education, degrees themselves are not considered an effective and meaningful means to employment, although some great emphasis has been placed on academic-industrial cooperation and vocational education. The vocational education for employment is largely limited to the programs offered in specialized high schools and junior colleges. At the level of bachelor degrees and above, higher education does not have any explicit or systematic recognition of vocational education, thus failing to develop vocational or professional degrees in distinction from traditional academic degrees. In these circumstances in which laws and regulations concerning vocational education are accordingly not properly provided, individual universities are helplessly left with the highly challenging task of a successful transition from higher education to the labor market. It is the business of this research to lay foundation for the establishment of ‘higher education professional degree system’ in Korea that enables a smooth transition from higher education to the labor market. For this purpose, this research conducts the international comparative study of five nations (Korea, the UK, the US, France, and Japan), which consists of a simple comparison and an in-depth comparison of the five nations. Seven categories are prepared for the simple comparison; (1) higher education system, (2) laws concerning higher education degrees, (3) national qualifications system, (4) academic degrees and professional degrees, (5) conditions for professional degrees, (6) quality control system of professional degrees, (7) recent policies concerning professional degrees. And under the seven categories fifteen items are developed for a detail comparison. For the in-depth comparison which intends to give a systematic explanation of the main differences among the professional degrees systems of the five nations, three levels of analysis (surface, middle, foundation levels) are suggested. The surface level analysis is concerned with the extent to which a higher education system is oriented towards traditional academic degrees programs or professional degrees programs. The middle level analysis is about the overarching aim of higher education, the proposition of private higher education institutions to public ones, the market-orientedness of higher education, the youth unemployment, the professionalization policy, the market values of professional degrees, the social trust in professional degrees, the internalization, and so forth. And at the foundation level, the analysis focuses on two factors that subtlely yet significantly result in a distinctive higher education system of a nation. It is shown that each nation’s higher education system has been developed in its own way, depending both on different modes of family system open to the young people who have begun studies at higher education institutions, and on different modes of social security system. The comparison helps identify two contrasting models of higher education professional degrees system, which can be found typically in France and the US. The French model is one that fully acknowledges the social and market values of professional degrees and thus systematically arranges professional degrees programs for the all levels of higher education whereas the American model is one in which professional degrees themselves are not greatly valued and required in the market. These two models are taken as two possible scenarios for the development of the Korean higher education system, and three steps to go through are provided for the completion of what is suggested in each scenario.요 약 제1장 서 론 1 제1절 연구의 필요성과 목적 3 제2절 연구 방법 7 제2장 한국의 고등직업학위제도와 문제 15 제1절 제도 17 제2절 문제점 63 제3장 외국의 사례 분석 65 제1절 영국 67 제2절 미국 115 제3절 프랑스 145 제4절 일본 183 제4장 비 교 243 제1절 고등직업학위제도 비교 245 제2절 국가 간 제도 차이 설명 251 제5장 결 론 259 SUMMARY 271 참고문헌 27

단일예측제어에서 설계 파라미터의 단순화된 선정기준에 관한 연구

학위논문(석사)--서울대학교 대학원 :화학공학과,1996.Maste

Oral health status and dental treatment need of liver transplant candidates

학위논문(석사) --서울대학교 대학원 :치의학과, 2009.2.Maste

Fluorescence features of Tm3+-doped multicomponent borosilicate and borotellurite glasses for blue laser and S-band optical amplifier applications

Novel B2O3-SiO2-Al2O3-ZnO-Li2O/MgO and B2O3-TeO2-PbO-ZnO-Li2O-Na2O glasses with different concentrations of Tm2O3 were synthesized by using the melt-quench method. All the fabricated samples have been characterized by visible emission spectra and decay times, including near-infrared (NIR) luminescence measurements. For 0.5 mol% Tm3+-doped borotellurite glass, several radiative parameters are evaluated using the Judd-Ofelt parameters. The intensity of all the visible emission bands increased with the increase of Tm2O3 concentration up to 0.5 mol%, and beyond this doping content, luminescence concentration quenching takes place. The luminescence intensity quenching is attributed to energy transfer (ET) processes through cross-relaxation (CR) channels. The visible luminescence decay curves were well fit with a single exponential (for Tm3+: D-1(2) level) and double exponential (for Tm3+: (1)G(4) level) functions for the multicomponent borosilicate samples, while Inokuti-Hirayama model was used for the multicomponent borotellurite glass D-1(2) level decay time fit. The derived decay lifetimes of the D-1(2) level are found to be much shorter than that of the (1)G(4) level. In Li2O (alkali) or MgO (alkaline) containing borosilicate samples, pumped under 808 nm laser diode, the H-3(4) -˃ F-3(4) (1.458 mu m) emission intensity increased from 0.1 to 2.0 mol% Tm3+ ion concentration, indicating negligible CR processes. The computed Full-Width at Half-Maximum (FWHM) values for the 1458 nm emission in 2.0 mol% Tm3+-doped Li and Mg series borosilicate samples are 117 and 125 nm, respectively, while the FWHM value for 0.5 mol% Tm2O3 content doped borotellurite glass is 118 nm. Following the analyzed visible and NIR optical results, the fabricated Tm3+ glasses could be useful for blue laser and S-band optical amplifier applications.This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. NRF2018R1A5A1025137). The author G.L.N would like to acknowledge the use of the facilities of Universiti Putra Malaysia (UPM), Malaysia. The author (A. Dahshan) gratefully thank the Deanship of Scientific Research at King Khalid University for financial support through research groups program under grant number (R.G.P.2/34/40)

사르코프스키 정리 와 더하기 기계

Thesis (master`s)--서울대학교 대학원 :수학과,1995.Maste

Luminescence properties of reddish orange emitting BaLa2ZnO5:Sm3+ phosphor prepared by citric based sol-gel synthesis

A series of BaLa2ZnO5:Sm3+ phosphors were synthesized with the sol-gel technique. The crystalline structure of each sample was characterized by X-ray diffraction (XRD). Phase formation was investigated using scanning electron microscope (SEM). Photoluminescence studies revealed an efficient excitation of phosphors at near blue light (similar to 410 nm), providing emission in the bright reddish-orange region (603 nm). Concentration quenching through multipolar interaction was observed in BaLa2ZnO5 phosphor system doped with 0.015 mol of Sm3+ concentration. The optimum phosphor showed prominent characteristics for application in white LEDs.This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (2018M2B2A9065656)

A Wearable Sleep Position Tracking System Based on Dynamic State Transition Framework

Sleep monitoring is vital as sleep plays an important role in recovering physical and mental health. To have a sound sleep, one has to avoid bad sleep positions associated with personal health conditions. However, most of the existing sleep trackers merely show quantitative information about sleep patterns and duration at each sleep stage, overlooking the importance of sleep positions upon sleep quality. To accurately keep track of sleep positions, we propose a wearable sleep position tracking system consisting of two wristbands and one chest-band. We suggest a two-level classifier specialized for sleep motion based on Dynamic State Transition (DST)-framework. The DST-framework is designed to process the spatio-temporal sleep motion data collected via accelerometer/gyro sensing and classify twelve sleep position (SP) motions from four sleep positions. Our experimental results demonstrate that the proposed system effectively and accurately classify twelve SP motions for tracking sleep positions, and hence, serves as a key building block for comprehensive sleep care applications related to sleep positions