• 한국IT서비스학회지
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• 제20권4호
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• pp.129-140
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• 2021

Recently, interest in AI tutors is rising as a way to bridge the educational gap in school settings. However, research confirming the effectiveness of AI tutors is lacking. The purpose of this study is to explore how effective learner characteristics and recommended item learning activities are in predicting learner's academic performance in an adaptive online learning environment. This study proposed the hypothesis that learner characteristics (prior knowledge, midterm evaluation) and recommended item learning activities (learning time, correct answer check, incorrect answer correction, satisfaction, correct answer rate) predict academic achievement. In order to verify the hypothesis, the data of 362 learners were analyzed by collecting data from the learning management system (LMS) from the perspective of learning analytics. For data analysis, regression analysis was performed using the regsubset function provided by the leaps package of the R program. The results of analyses showed that prior knowledge, midterm evaluation, correct answer confirmation, incorrect answer correction, and satisfaction had a positive effect on academic performance, but learning time had a negative effect on academic performance. On the other hand, the percentage of correct answers did not have a significant effect on academic performance. The results of this study suggest that recommended item learning activities, which mean behavioral indicators of interaction with AI tutors, are important in the learning process stage to increase academic performance in an adaptive online learning environment.

• Journal of Yeungnam Medical Science
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• 제40권2호
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• pp.187-192
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• 2023

Background: This study aimed to present the short- and midterm outcomes after complete atrioventricular canal defect (CAVC) repair using a single-patch technique. Methods: This study included 30 children who underwent surgical correction of the CAVC using a single-patch technique. Results: The median age of the patients was 5.7 months (interquartile range [IQR], 5.0-7.5 months), and 23 patients (76.7%) had type A CAVC. Fourteen patients (46.7%) were female and 17 (56.7%) had been diagnosed with Down syndrome. The in-hospital mortality rate was 0%. No deaths were observed during a median follow-up of 4 years (IQR, 3.5-5.0 years). Patients without Down syndrome were associated with late moderate mitral regurgitation (MR) (p=0.02). Late MR less than moderate degree was observed in 96.6%, 78.5%, and 50% of patients after 2, 4, and 5 years of follow-up, respectively, while late tricuspid valve regurgitation less than moderate degree was observed in 96.7%, 85.9%, and 59.0% of patients after 2, 4, and 6 years of follow-up, respectively. After a median follow-up of 4 years, only one patient had required surgical repair of a left ventricular outflow tract obstruction, which occurred 26 months after the first operation. Multivariable logistic regression analysis adjusted for the type of CAVC, sex, Down syndrome, age, and weight revealed that the absence of Down syndrome was a risk factor for late moderate MR (MR-2) (odds ratio, 0.05; 95% confidence interval, 0.006-0.50; p=0.01). Conclusion: A single-patch technique for CAVC surgical repair is a safe method with acceptable short- and midterm results.

• 실천공학교육논문지
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• 제16권1_spc호
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• pp.33-39
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• 2024

본 연구는 최근 생성형 AI로 인한 새로운 교육 트렌드 변화에 학습자들의 수업 경험에 대한 긍정/부정 인식의 변화와 실제 활용 형태를 살펴본다. 공학 계열 대학생 6학급을 대상으로 2학기 동안 AI 챗봇을 웹 프로그래밍 수업에 활용하였고, 학기 초부터 설문 조사를 시작으로 중간/기말 고사 보고서 제출 기간까지 학습자의 경험과 활용에 대한 변화를 분석했다. 연구 분석 결과, Q/A 피드백과 실습 문제 해결 등 학습 개선에 도움이 되었고, 수업 적용 이후 중간부터 기말범위까지 챗봇에 대한 인식이 긍정적으로 변화하였다. 이외 수업 내에 커뮤니티 단절(개인화) 문제와 교육 S/W로써 활용 방안에 대한 유의미한 결론을 도출했다. 본 연구는 앞으로 생성형 AI 기반 소프트웨어 개발을 위한 기초 연구로써 의의가 있다.

• Clinics in Shoulder and Elbow
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• 제27권1호
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• pp.39-44
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• 2024

Background: Displaced olecranon fractures constitute a challenging problem for elbow surgeons. The purpose of this study is to evaluate the role of suture anchor fixation for treating patients with displaced olecranon fractures. Methods: A retrospective review was performed for all consecutive patients with displaced olecranon fractures treated with suture anchor fixation with at least 2 years of clinical follow-up. Surgical repair was performed acutely in all cases with nonmetallic suture anchors in a double-row configuration utilizing suture augmentation via the triceps tendon. Osseous union and perioperative complications were uniformly assessed. Results: Suture anchor fixation was performed on 17 patients with displaced olecranon fractures. Functional outcome scores were collected from 12 patients (70.6%). The mean age at the time of surgery was 65.6 years, and the mean follow-up was 5.6 years. Sixteen of 17 patients (94%) achieved osseous union in an acceptable position. No hardware-related complications or fixation failure occurred. Mean postoperative shortened disabilities of the arm, shoulder, and hand (QuickDASH) score was 3.8±6.9, and mean Oxford Elbow Score was 47.5±1.0, with nine patients (75%) achieving a perfect score. Conclusions: Suture anchor fixation of displaced olecranon fractures resulted in excellent midterm functional outcomes. Additionally, this technique resulted in high rates of osseous union without any hardware-related complications or fixation failures.

• Journal of Chest Surgery
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• 제19권2호
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• pp.288-294
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• 1986

During the period from Mar. 1983 to Feb. 1986, 22 patients with vascular trauma were treated at Capital Armed General Hospital. 1] 11 patients had arterial injury alone, 6 patients had venous injury alone, and 5 patients had both arterial and venous injuries. 2] The mechanism of injury in these 22 patients was 7 penetrating non-gun shot wounds, 5 blast fragments injuries, 4 iatrogenic injuries, 4 blunt injuries, 2 gun shot wounds. 3] The method of 16 arterial repair was 5 autogenous saphenous vein graft, 8 synthetic vascular graft, 1 end to end anastomosis, 2 lateral suture. Midterm patency of 16 repairs was 100% within 1 months. 4] The method of 11 venous repair was 1 autogenous saphenous vein graft, 2 onlay vein patch, 2 ligation, 1 lateral suture. The thrombotic obstructions occurred in 4 repairs [36.4%], but they were resolved somewhat with heparinization. 5] Uncommon cases of false aneurysm of internal carotid artery and laceration of retrohepatic inferior vena cava were summarized.

• Journal of Chest Surgery
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• 제34권5호
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• pp.407-409
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• 2001

기존의 중앙 단락술을 기술적으로 변형하여 두 명의 신생아를 수술하였다. 해부학적 진단은 심실 중격 결손을 동반한 폐동맥 동맥관 개존증이었다. 일차 수술에서 대동맥-단락간 문합을 측-측 문합 방식으로 하였다. 관찰기간 동안 양쪽 폐동맥과 주폐동맥은 잘 성장하였고 각각 10, 18개월에 Lecompte 술식을 시행하였다. 이 방법은 짧고 뒤틀림이 적은 직선주행의 단락을 만드는 장점을 가지고 있다.

• 한국건축시공학회지
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• 제11권5호
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• pp.515-522
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• 2011

As Construction and Demolition (C&D) debris increases every year, systems have been adopted to compel the use of recycled aggregate made from C&D debris, and the use of recycled aggregate in the construction field has increased. But environmental problems linked to the alkalinity of recycled aggregate have occurred, and a study on approaches to lower the alkalinity of recycled aggregate is needed. It was certified by this study that a large amount of recycled aggregate could be carbonated in the C&D debris midterm-treatment field. As a result, the density and the water absorption of recycled aggregate after carbonation reaction was improved, and pH of recycled aggregate was lowered from over 11 to 9.4. X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), and Thermogravimetry/Differential Thermal Analysis (TG/DTA) methods also indicated the carbonation of recycled aggregate.

• Journal of Information Processing Systems
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• 제18권2호
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• pp.282-291
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• 2022

This research applies a pre-trained bidirectional encoder representations from transformers (BERT) handwriting recognition model to predict foreign Korean-language learners' writing scores. A corpus of 586 answers to midterm and final exams written by foreign learners at the Intermediate 1 level was acquired and used for pre-training, resulting in consistent performance, even with small datasets. The test data were pre-processed and fine-tuned, and the results were calculated in the form of a score prediction. The difference between the prediction and actual score was then calculated. An accuracy of 95.8% was demonstrated, indicating that the prediction results were strong overall; hence, the tool is suitable for the automatic scoring of Korean written test answers, including grammatical errors, written by foreigners. These results are particularly meaningful in that the data included written language text produced by foreign learners, not native speakers.

• Journal of Chest Surgery
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• 제36권9호
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• pp.659-665
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• 2003

심폐바이패스를 사용하지 않는 관상동맥우회술에서 골격화된(skeletonized) 양측 내흉동맥 이외에 골격화된 우위대망동맥을 함께 사용한 환자들에서 수술 직후와 1년째의 성적을 비교하였다. 대상 및 방법: 1999년 8월부터 2001년 12월까지 서울대학교병원 흉부외과에서 골격화된 양측 내흉동맥과 우위대망동맥을 이용하여 시행한 103예의 관상동맥우회수술을 대상으로 하였다 이중 우위대망동맥을 유근이식편(in situ graft)으로 사용한 것이 88예, 근위부를 다른 혈관 도관에 연결(composite graft)하여 사용한 것이 10예, 대동맥에 연결(free graft)하여 사용한 것이 5예로 각각의 경우 수술 직후와 1년후 혈관조영검사를 통해 도관의 기능을 평가하였다. 결과: 평균 문합수는 3.8$\pm$0.7개였고 수술 직전 측정한 도관의 자유혈류량(free flow (ml/rnin))은 우위대망동맥이 130$\pm$95 ml/min로 좌내흉동맥(107$\pm$55 ml/min)과 우내흉동맥(113$\pm$57 ml/min)에 비해 유의하게 많았다(p<0.05). 수술 후 100명(97.1%)의 환자에게 평균 1.3$\pm$0.8일째에 혈관 조영 검사를 시행하였는데 내흉동맥은 98.6% (272/276),우위대망동맥은 97.0% (97/100)의 개통률을 보였다(p=ns). 퇴원 후에 평균 12.4$\pm$3.7개월째에 다시 88명(85.4%)의 환자에서 혈관 조영 검사를 시행하였다 개통률은 내흉동맥과 우위대망동맥이 각각 95.9%(234/244), 88.6%(78/88)로 내흉동맥이 조금 우세하였지만 통계적 유의성은 없었다(p=0.07). 우위대망동맥과 자신의 관상동맥 사이 혈류경쟁(flow competition)의 소견은 수술 직후에 5예, 1년 뒤에 7예에서 관찰되었는데 TTFM (transit time flow measurement)을 수술 중에 시행하여 혈류경쟁이 의심되는 경우에서 교정을 시행한 이후에는 각각 1예와 2예로 유의하게 줄어듦을 관찰할 수 있었다. 결론: 우위대망동맥은 내흉동맥에 이어 비교적 안전하게 사용할 수 있는 제3의 동맥 도관이며, 수술 중 혈류 측정, 대상 혈관의 정확한 수술 전 평가 등을 통해 중장기 개통률을 향상시킬 수 있다.

• Journal of Chest Surgery
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• 제41권6호
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• pp.695-702
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• 2008

배경: 심장 판막 수술에서 조직판막 혹은 기계판막의 선택은 중요한 문제이고, 조직판막의 내구성이 그 결정에 주요한 역할을 한다. 본 연구는 승모판에서 조직판막 이식 후 중기 결과를 알아보고자 하였다. 대상 및 방법: 1989년 7월부터 2007년 8월까지 조직판막을 이용하여 승모판 치환술을 받은 모든 환자를 대상으로 하였다. 216명의 환자에서 236예의 수술을 시행하였으며 평균 연령은 $63{\pm}15$세, 남녀 비는 1 : 3이었다. 술 후 총 추적 관찰 기간은 760.2 patient-years, 평균 추적 관찰 기간은 $41.9{\pm}40.7$개월 ($0{\sim}212$개월)이었고, 외래 경과 기록과 의무 기록을 통해 후향적으로 분석하였다. 결과: 조기 사망은 18명(8.3%)이었고, 13명은 승모판 치환술과 다른 동반 수술을 같이 시행한 경우였다. 5년, 8년에서 생존율은 각각 $79.9{\pm}3.5%$, $65.5{\pm}5.5%$이었으며, 구조적 판막 손상으로부터의 5년, 8년 회피율(freedom from structural valve deterioration, SVD)은 각각 $96.2{\pm}2.2%$, $85.9{\pm}5.3%$이었다. 재수술의 5년, 8년 회피율(freedom from Reoperation)은 $96.0{\pm}1.7%$$, $90.4{\pm}4.2%$, 구조적 판막 손상으로 인한 재수술의 회피율(freedom from Reoperation for, SVD)은 $98.1{\pm}1.2%$$, $92.3{\pm}4.1%$이었다. 수술 전 위험인자의 다변량 분석에서 작은 판막(Valve size 25 and 27 mm)을 사용한 경우가 재수술의 유의한 위험 인자였으며, 중등도 이상의 좌심실 기능부전(Left ventricle ejection fraction, LVEF < 40%)은 구조적 판막 손상과 사망률의 유의한 위험인자였다. 결론: 승모판의 조직판막 치환술에서 생존율과 재수술의 회피율은 만족할 만한 중기 성적을 보여주나, 구조적 판막 손상의 회피율은 비교적 낮은 성적을 보였다. 수술 후 8년을 전후해서 급격한 손상의 진행을 보이므로, 8년을 기준으로 해서 잦은 경과 관찰과 심초음파 검사는 판막 손상의 조기 발견에 도움이 될 것이며, 더 많은 환자 수에서 보다 장기적인 연구가 필요할 것이다.