CART 방법론을 사용한 클라우드 컴퓨팅 도입 의사 결정 모델링

백승현,장병윤,Baek, Seung Hyun,Chang, Byeong-Yun 한국시뮬레이션학회 2014 한국시뮬레이션학회 논문지 Vol.23 No.4

In this paper, we conducted a study on place-free and time-free cloud computing (CC) adoption decision-making model. Panel survey data which is collected from 65 people and CART (classification and regression tree) which is one of data mining approaches are used to construct decision-making model. In this modeling, there are 2 steps: In the first step, significant questions (variables) are selected. After that, the CART decision-making model is constructed using the selected variables. In the variable selection stage, the 25 questions are reduced to 5 ones. The benefits of question reduction are quick response from respondent and reducing model-construction time. 본 논문에서는 장소와 시간의 제약을 받지 않는 클라우드 컴퓨팅 도입 의사 결정 모델링에 대한 연구를 진행하였다. 연구에서는 65명의 응답자에게 수집 된 패널데이터와 데이터마이닝 방법 중 하나인 CART(회귀분류나무)를 사용하여 의사결정 모델을 구축하였다. 모델링에는 2단계로 진행되는데 첫 번째 단계에서는 패널데이터를 사용하여 도입 의사를 결정하는데 영향을 미치는 문항들을 선택하고 2 번째 단계에서는 선택된 문항을 사용하여 도입 의사 결정 모델을 구축하였다. 문항 선택을 통하여 설문지 수집 문항수를 25개에서 5개로 줄일 수 있어 응답자에게 빠른 답변을 얻을 수 있고 데이터의 사이즈가 작기 때문에 모델 구축 시간을 줄일 수 있는 장점을 보여주었다.

중합효소연쇄반응으로 확인된 엡스타인-바바이러스 재활성화가 소아 급성 A형 간염에 미치는 영향

백승현,김상용,고홍,Baek, Seung-Hyon,Kim, Sang-Yong,Koh, Hong 대한소아소화기영양학회 2011 Pediatric gastroenterology, hepatology & nutrition Vol.14 No.1

목 적: 본 저자들은 급성 A형 간염 환아에서 EBV의 재활성화가 증가하였고 EBV의 재활성화가 A형 간염의 경과에 영향을 미치는 지 보고한 바 있으나 과거 연구의 한계를 극복하고자 중합효소연쇄반응을 시행하여 EBV의 재활성화가 확인된 급성 A형 간염 환아들의 임상경과를 분석하기로 하였다. 방 법: 과거 연구와 동일한 대상으로 2008년부터 2010년까지 세브란스병원에서 급성 A형 간염으로 진단받은 19세 이하의 환자 중 EBV PCR을 추가로 시행한 34명으로 제한하여 입원 당시의 나이, 성별, 간염으로부터 완전히 회복될 때까지 걸린 기간, 혈청검사 결과, 초음파검사 결과를 조사하였다. 대상 환아를 EBV의 비활성화군과 재활성화군으로 나누어 결과를 비교 하였고 10세를 기준으로 환아를 나누어 비활성화군과 재활성화군을 비교하였으며 이번 연구 결과와 과거연구 결과에서 유의하게 나온 항목을 비교분석하였다. 결 과: 재활성화된 비율은 35.3%였고 비활성화군과 재활성화군을 비교하였을 때 AST (p=0.001), ALT (p<0.001), AST/ALT ratio (p=0.002), 이환 기간 중의 최소 단백량(p<0.001), 이환 기간 중의 최소 알부민(p<0.001), 비정형림프구의 백분율(p=0.001), PT-INR (p<0.001), 간염회복기간(p<0.001), 비장비대(p<0.001)가 통계적으로 유의한 차이를 보였고 10세 미만에 비해 10세 이상의 환아에서 EBV가 재활성화 되었을 때 임상양상이 더 좋지 않았다. 지난 연구결과와 비교하였을 때 최소 혈청 단백농도(p<0.001)가 추가로 유의하였으며 10세 미만의 환아군에서 PT-INR의 차이가 사라지고 10세 이상의 환아군에서 최소 혈청 단백농도가 추가로 유의한 결과를 보였다. 결 론: 중합효소연쇄반응을 이용한 본 연구에서도 급성 A형 간염 환아에서 EBV의 재활성화가 흔하며 간염의 경과에 좋지 않은 영향을 미치고 나이가 많은 환아에서 더 좋지 않은 영향을 미치는 것으로 확인할 수 있었다. Purpose: We previously reported that concurrent reactivation of latent Epstein-Barr virus (EBV) in children with hepatitis A virus (HAV) infection is common and EBV reactivation with HAV infection adversely affects the clinical features of hepatitis. However, the incidence of concurrent reactivation was not accurate because the detection of EBV reactivation was based on serologic methods. Therefore, we studied the effects of polymerase chain reaction (PCR)-proven EBV reactivation, thus a more precise concurrence, on acute HAV infection in children. Methods: PCR were conducted in 34 patients, who had enrolled previous study and diagnosed with acute HAV infection between January 2008 and June 2010. Their medical records were reviewed. Results: Among 34 patients with acute HAV infection, 12 patients (35.3%) had EBV reactivation which was proven using serologic and molecular biologic techniques. There were significant differences in the peak levels of AST and ALT between the reactivated and non-reactivated groups (p=0.001 and p<0.001, respectively). The duration of full recovery from hepatitis was more prolonged in the reactivated group (p<0.001). Clinical parameters, such as serum protein (p<0.001) and albumin concentrations (p<0.001), atypical lymphocyte count (p=0.001), prothrombin time-international normalized ratio (PT-INR, p<0.001), and splenomegaly (p<0.001), showed significant differences. The clinical features in the reactivated sub-group >10 years of age revealed more liver dysfunction compared to the non-reactivated sub-group. A comparison with a previous study was performed. Conclusion: PCR-proven reactivation of latent EBV in children with HAV infection is common and EBV reactivation with HAV infection adversely affects the clinical features of hepatitis, especially in older children.

강화학습을 이용한 냉장고 전력 최적화

백승현(Seunghyun Baek),강민경(Minkyeong Kang),김강현(Kanghyun Kim),김인중(Injung Kim) Korean Institute of Information Scientists and Eng 2024 한국정보과학회 학술발표논문집 Vol.2024 No.6

서양정치사상 연구의 토대적 질문들에 대한 고찰

백승현 ( Seung Hyun Baek ) 慶熙大學校 社會科學硏究院 2001 社會科學硏究 Vol.27 No.-

L2 읽기능력의 요인들과 L2 읽기능력과의 구조적 관계

백승현 ( Seung Hyun Baek ),지문건 ( Moon Gun Ji ) 21세기영어영문학회 2016 영어영문학21 Vol.29 No.2

The empirical research was examined for a sample of 129 4th graders in an EFL environment in order to explore the fundamental elements impacting on second language (L2) reading comprehension and their structural relationship to L2 reading comprehension. The materials used for the current study were (1) a questionnaire on L2 reading comprehension, (2) L2 productive/receptive vocabulary test and (3) L2 reading comprehension test, adopted from Woodcock-Johnson Ⅲ Diagnostic Reading Battery (Woodcock, Mather, and Schrank 2004). First, four factors on L2 reading comprehension were unveiled: L2 reading comprehension learning strategy, first language (L1) proficiency, parents’ interest on their children``s English learning, and extra-curricular activities. Those factors are strongly associated with L2 vocabulary and L2 reading comprehension. Second, L2 productive/receptive vocabulary were significant indicators of successful L2 reading comprehension. Finally, L2 vocabulary knowledge contributed a significant amount of unique variance to L2 reading comprehension based on the structural equation modeling (SEM). These findings are steadily aligned with the Lexical Quality Hypothesis in which L2 vocabulary knowledge is assumed to be a critical determinant of L2 reading comprehension (LQH: Perfetti & Hart, 2001).

CART를 이용한 주가결정요인분석과 주가예측

백승현(Seung Hyun Baek),황승준(Seung-June Hwang) 한국경영과학회 2018 經營 科學 Vol.35 No.1

Existing stock price analysis studies tended to focus only on stock price rather than stock price determinants, but in this study we develop a stock price forecasting system with a two-step method. In the first step, we find the factors that determine the stock price and predict the stock price based on the factors determined in the second step. The scope of the research is meaningful in reducing the cost of collecting data by developing predictive-based models that can be used in the stock market and selecting the variables needed for forecasting. The research methodology will use CART (Classification And Regression Tree). In this study, we applied to the stock price prediction in two directions of both prediction and classification. We use the KOSPI 200 data for empirical analysis and present a quantitative forecasting model that considers the direction of future share prices by using financial statement indices, past and present stock prices related to asset value and profitability value. Experiments were conducted in three experiments according to the input parameters of prediction and classification problem. Based on the experimental results, two determinants and two models are suggested for prediction and classification.

비장 손상의 임상적 치료 결과

백승현 ( Seung Hyun Baek ),박성진 ( Sung Jin Park ),김재훈 ( Jae Hoon Kim ),김현성 ( Hyun Seong Kim ),김대환 ( Dae Hwan Kim ),조홍재 ( Hong Jae Jo ),서형일 ( Hyung Il Seo ) 대한외상학회 2012 大韓外傷學會誌 Vol.25 No.2

Purpose: The management of splenic injuries has shifted from a splenectomy to splenic preservation owing to immunity. The purpose of this study was to assess the kinds of management and outcomes through a review of our experience with splenic injuries. Methods: We retrospectively reviewed 47 patients with traumatic splenic injuries using by electronic medical records from Jan. 2007 and Dec. 2011. Splenic injuries were classified according to the American Association for the Surgery of Trauma (AAST) grading system. Results: There were 11 falls, 11 traffic accidents, 10 motorcylcle accidents, 10 pedestrian accidents and 5 abdominal blunt traumas. Low-grade injured patients (≤Grade Ⅲ) were 29 of 43(61.7%), and High-grade injured patients (≥Grade IV) were 18 of 43(38.3%). In 34 patients, non-surgical treatment was performed, and 14 patients underwent a splenectomy. There were relatively more high-grade in older patients, and the highgrade-injury group showed need for a transfusion (p=0.002), more need for a splenectomy (p<0.001), a longer mean hospital stay (p=0.036), a longer ICU stay (p=0.045) and more combined organ injury (p=0.036). Conclusion: Conservative treatment should be considered in low-grade-injury patients (≤Grade Ⅲ). A Splenectomy was performed on 56% of the patients with Grade Ⅳ injuries, so a splenectomy should be considered carefully in such patients. In patients with a grade Ⅴ injury, we think surgical treatment may be needed. (J Korean Soc Traumatol 2012;25:44-48)

철도분야 정부출연연구기관의 조직문화가 직무몰입 및 성과지향성에 미치는 영향분석

백승현(Sunghyun Baek),김춘수(Choonsu Kim),진영권(Yeongkwon Jin) 한국철도학회 2022 한국철도학회 학술발표대회논문집 Vol.2022 No.4

수업언어가 제2언어 음운인식과 읽기능력에 미치는 효과

백승현 ( Seung Hyun Baek ) 글로벌영어교육학회(구 호남영어교육학회) 2010 Studies in English education Vol.15 No.2

The present study explored the effects of language of instruction on the L2 phonological awareness and word reading. Ninety Korean-speaking EFL children in third grade were randomly assigned to Korean-English instruction group or English-only instruction group. Twelve 40-minute teaching sessions in each language were implemented to each group. After treatments, the results unveiled that overall the phonological awareness gradually improved across the two experimental groups. More importantly, within each group, the achievement of sensitivity to phonemes and rimes children with English-only instruction showed was much larger than the performance of sensitivity to phonological units those with Korean-English instruction showed, Additionally, an Analysis of Covariance found that children taught to read out words in Korean and English performed better on L2 phoneme awareness, especially L2 nucleus (medial vowel) and L2 pseudo word reading than those in English only. The results suggest that an instructional language, Korean-English made a greater impact on the achievement of phonological recoding to read out unknown/unfamiliar words and phonological sensitivity to nucleus rather than another instructional language, English-only. Consequently, there will be an ongoing need for dynamically selecting the language(s) of L2 early literacy instruction, raising a precise caution in employing an English-only instruction.

라즈베리 파이를 활용한 OpenWRT 기반 LTE 비상망 로드밸런서

백승현(Seung-Hyun Baek),장민석(Min-Seok Jang) 한국전자통신학회 2019 한국전자통신학회 논문지 Vol.14 No.1

제 4차 산업혁명이 각광받고 있는 가운데 통신 장애를 대비한 다양한 기술이 개발되어 상용화되고 있다. 그러나 IDC의 백업망은 많은 개발이 진행되고 있으나 소규모 저전력의 개인 또는 센서에 대한 통신 장애 대비는 다소 부족한 것이 현실이다. 이에 시중에서 쉽게 구할 수 있는 라즈베리 파이 재단의 라즈베리 파이 제품군에 OpenWRT 펌웨어를 사용하여 저전력 개인 로드 밸런서를 구축하고, USB기반 LTE 안테나를 통해 유선통신에 장애 발생 시 LTE를 통하여 장애 알림과 중요 데이터를 송신할 수 있는 시스템을 개발하였다. 시중에서 쉽게 구할 수 있는 제품들인 점과 USB를 사용함으로 다른 초소형 개발보드에서도 응용할 수 있기 때문에 개인의 센서 네트워크 망 구축에 많은 도움이 될 것이라 기대된다. Recently, the 4th Industrial Revolution has been emerged and various products are developed and commercialized in preparation of the communication failure. Many solutions are underway in Back-Up Network for IDC Servers, but not in the personal or sensor for low-power system use. Therefore we used the OpenWRT Firmware in Raspberry Pi which can be easily obtained in online market, and it created a low-power load balancer. Therefore, we developed the device that uses LTE Antenna based on USB Interface for communication fault notification and important data. The equipment used in this paper is easy to buy in online shop for anyone. Also, it can be applied in other vendors’ boards by using USB. We hope that this paper will contribute to the stability of individual sensor networks.