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김준철(Jun Cheol Kim),권숙희(Sookhee Kwon),하일도(Il Do Ha),나명환(Myung Hwan Na) 한국데이터정보과학회 2021 한국데이터정보과학회지 Vol.32 No.2
4차 산업혁명 기술 융합과 혁신으로 최근 농업 분야에서 정보통신기술을 접목하여 적정한 생육환경을 유지하고 관리할 수 있도록 스마트팜의 보급과 확산이 활발히 이뤄지고 있다. 본 연구에서는 스마트팜 빅데이터로부터 실제로 수집된 주별 토마토 자료를 활용하여 생존분석 결과를 제시하고자 한다. 여기서 관심사건에 대한 생존시간을 수확시간 (착과부터 수확까지의 시간)으로 정의하고 계산된 수확시간을 통해 통상적으로 고려되는 환경변수인 내부온도, 내부습도, CO2농도 그리고 누정일사량 등 관심 있는 환경 요인의 그룹 변수의 누적수확 확률에 대한 비모수적 추정 결과를 제시한다. 나아가, 가속화 실패시간 모형과 벌점화 가능도를 이용하여 생존시간에 중요한 영향을 주는 요인을 찾고자 한다. 본 논문에서는 벌점함수로서 LASSO, ALASSO, SCAD, HL (hierarchical likelihood)을 사용한다. 추가적으로 네 가지 벌점화 변수 선택 방법에 따른 예측 모형의 성능을 평가하였다. With technological convergence and innovation following the 4th industrial revolution, smart farms are recently spreading to maintain an appropriate cultivation environment by grafting information and communication technology into the agricultural field. In this paper, we present the results of survival analysis using weekly tomato data actually collected from smart farm big data. Here, the survival time for the event of interest is defined as the harvest time (time from fruiting to harvesting). In addition, nonparametric estimation results of the cumulative harvest probability of the group variables of interest such as internal temperature, internal humidity, CO2 concentration, and cumulative insolation, which are important environmental factors, are presented through the calculated harvest time. Furthermore, using the acceleration failure time (AFT) model and the penalized likelihood, we present the factors that have an important influence on the survival time. Here, we use LASSO, ALASSO, SCAD, and HL (hierarchical likelihood) as the penalty function. In particular, we evaluate the performance of the prediction model according to the four penalized variable selection methods via MSE (mean squared error) and C-index (concordance index).
Dentascan?瑛? 이용한 하악구치부의 하악관 위치에 관한 임상적 연구
김준철(Jun-Cheol Kim),이승훈(Seung-Hoon Rhee),이정근(Jeong-Keun Lee) 대한구강악안면외과학회 2002 대한구강악안면외과학회지 Vol.28 No.5
This study was designed to determine the location of the mandibular canal on lower molar areas. Thirty-three patients were examined with multi-planar reformatted CT scan(Dentascan). Three kinds of measurements were performed. The first was the distances between the upper border of the mandibular canal and the root apices of the first and second molars, the second was the distance between the cortical plate of the mandible and mandibular canal, and the last was the location of the mandibular canal in the buccolingual plane. The obtained results are as follows 1. The distance between the root apices of lower molars and the superior border of mandibular canal was largest at the mesial root of the first molar, and shortest at the distal root of the second molar(p<0.05). 2. The longest distance between the outer surface of the buccal cortical plate of the mandible and mandibular canal was measured from the distal root of the second molar, and this distance decrease gradually mesially( p<0.05). 3. The distance between the mandibular base and inferior border of mandibular canal was longest at the distal root of the second molar, and shortest at the mesial root of the first molar(p<0.05). 4. The location of mandibular canal was lingually positioned in relation to the axis of teeth and alveolar ridge in molar areas.