CT-Based Radiomics Signature for Preoperative Prediction of Coagulative Necrosis in Clear Cell Renal Cell Carcinoma
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- Korean Journal of Radiology
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- 제21권6호
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- pp.670-683
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- 2020
Objective: The presence of coagulative necrosis (CN) in clear cell renal cell carcinoma (ccRCC) indicates a poor prognosis, while the absence of CN indicates a good prognosis. The purpose of this study was to build and validate a radiomics signature based on preoperative CT imaging data to estimate CN status in ccRCC. Materials and Methods: Altogether, 105 patients with pathologically confirmed ccRCC were retrospectively enrolled in this study and then divided into training (n = 72) and validation (n = 33) sets. Thereafter, 385 radiomics features were extracted from the three-dimensional volumes of interest of each tumor, and 10 traditional features were assessed by two experienced radiologists using triple-phase CT-enhanced images. A multivariate logistic regression algorithm was used to build the radiomics score and traditional predictors in the training set, and their performance was assessed and then tested in the validation set. The radiomics signature to distinguish CN status was then developed by incorporating the radiomics score and the selected traditional predictors. The receiver operating characteristic (ROC) curve was plotted to evaluate the predictive performance. Results: The area under the ROC curve (AUC) of the radiomics score, which consisted of 7 radiomics features, was 0.855 in the training set and 0.885 in the validation set. The AUC of the traditional predictor, which consisted of 2 traditional features, was 0.843 in the training set and 0.858 in the validation set. The radiomics signature showed the best performance with an AUC of 0.942 in the training set, which was then confirmed with an AUC of 0.969 in the validation set. Conclusion: The CT-based radiomics signature that incorporated radiomics and traditional features has the potential to be used as a non-invasive tool for preoperative prediction of CN in ccRCC.
The wall shear stress in the vicinity of end-to end anastomoses under steady flow conditions was measured using a flush-mounted hot-film anemometer(FMHFA) probe. The experimental measurements were in good agreement with numerical results except in flow with low Reynolds numbers. The wall shear stress increased proximal to the anastomosis in flow from the Penrose tubing (simulating an artery) to the PTFE: graft. In flow from the PTFE graft to the Penrose tubing, low wall shear stress was observed distal to the anastomosis. Abnormal distributions of wall shear stress in the vicinity of the anastomosis, resulting from the compliance mismatch between the graft and the host artery, might be an important factor of ANFH formation and the graft failure. The present study suggests a correlation between regions of the low wall shear stress and the development of anastomotic neointimal fibrous hyperplasia(ANPH) in end-to-end anastomoses. 30523 T00401030523 ^x Air pressure decay(APD) rate and ultrafiltration rate(UFR) tests were performed on new and saline rinsed dialyzers as well as those roused in patients several times. C-DAK 4000 (Cordis Dow) and CF IS-11 (Baxter Travenol) reused dialyzers obtained from the dialysis clinic were used in the present study. The new dialyzers exhibited a relatively flat APD, whereas saline rinsed and reused dialyzers showed considerable amount of decay. C-DAH dialyzers had a larger APD(11.70
The wall shear stress in the vicinity of end-to end anastomoses under steady flow conditions was measured using a flush-mounted hot-film anemometer(FMHFA) probe. The experimental measurements were in good agreement with numerical results except in flow with low Reynolds numbers. The wall shear stress increased proximal to the anastomosis in flow from the Penrose tubing (simulating an artery) to the PTFE: graft. In flow from the PTFE graft to the Penrose tubing, low wall shear stress was observed distal to the anastomosis. Abnormal distributions of wall shear stress in the vicinity of the anastomosis, resulting from the compliance mismatch between the graft and the host artery, might be an important factor of ANFH formation and the graft failure. The present study suggests a correlation between regions of the low wall shear stress and the development of anastomotic neointimal fibrous hyperplasia(ANPH) in end-to-end anastomoses. 30523 T00401030523 ^x Air pressure decay(APD) rate and ultrafiltration rate(UFR) tests were performed on new and saline rinsed dialyzers as well as those roused in patients several times. C-DAK 4000 (Cordis Dow) and CF IS-11 (Baxter Travenol) reused dialyzers obtained from the dialysis clinic were used in the present study. The new dialyzers exhibited a relatively flat APD, whereas saline rinsed and reused dialyzers showed considerable amount of decay. C-DAH dialyzers had a larger APD(11.70
This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.
본 연구에서는 서로 다른 학습접근방식의 학생이 유전 가계도 문제 해결 과정상에서 어떠한 차이를 보여주는지 심층적으로 들여다보고자 하였다. 연구 대상은 고등학교 2학년 학생으로 생명과학I을 이수한 학생으로 학업성취수준은 비슷하였으나 학습접근방식이 각각 심층적 접근방식과 피상적 접근방식을 나타내었다. 각 학생의 문제 해결 사례를 심층적으로 분석하기 위해 문제 해결 과정은 비디오 녹화되었고, 문제 해결이 종료된 후에 학생들의 문제 해결 과정에 대한 사고 구술 인터뷰를 실시하였다. 연구 결과, 학생들은 2가지 형질의 유전 원리가 불확실한 문제 상황을 해결하는 과정에서 유사한 오류를 보여주었다. 하지만 심층적 학습접근방식의 학생 A는 자발적으로 2번 반복하여 문제를 해결하면서 3가지 제한 요인에 대해 원리 기반추론을 하며 옳은 개념적 프레이밍을 나타내었다. 검토 단계에서 자료와 본인이 그린 가계도 사이의 일치도를 점검하고, 문제 해결 이후에도 끊임없이 본인의 문제 해결 과정을 점검하였다. 마지막의 문제 해결 과정에서는 성공적인 문제 해결 알고리즘에 근접한 문제 해결 과정을 나타내었다. 하지만 피상적 학습접근방식의 학생 B는 연구자의 권유로 비자발적으로 문제 해결 과정을 반복하였고, 답을 구하려는 목적 지향적인 문제 해결 태도로 인해 문제에서 제시한 일부 정보만을 검토하였다. 문제의 제한 요인에 대해 기억 장치 추론이나 임의적 추론을 통해서 옳지 않은 개념적 프레이밍을 하였고, 이를 수정하지 않고 유지하는 모습을 나타내었다. 본 연구 결과를 통해 심층적 접근방식과 피상적 접근방식의 학생이 문제 해결 과정에서 추론 방식과 개념적 프레이밍의 변화가 어떻게 일어나는지 구체적으로 살펴봄으로써 유전 문제의 접근을 어려워하는 학생들이나 이들을 지도하는 교사들에게 도움을 줄 수 있을 것이다.
본 논문에서는 선형 판별분석 (LDA: Linear Discriminant Analysis)과 공통벡터 추출방법을 이용한 음성인식방법을 제안하였다. 음성신호는 화자의 성별, 나이, 출생지, 주위 잡음, 정신적 상태, 발성기관의 구조 등과 같은 다양한 정보를 포함하고 있다. 이로 인해 같은 음성신호라 할지라도 서로 다른 화자가 발성하게 되면 서로 다른 특성을 보이게 된다. 음성신호의 이러한 성질은 같은 음성군 (class)에 포함된 공통된 특성벡터를 추출하는 일을 상당히 어렵게 한다. 음성신호에서 공통된 특징 벡터를 추출하는 방법은 KLT (Karhunen-Loeve Transformation)와 같이 선형 대수적인 접근방법이 많이 사용되어지고 있으나, 본 논문에서는 M. Bilginer et al.이 제안한 공통벡터 추출 방법을 사용하였다. M. Bilginer et al.이 제안한 방법은 주어진 훈련 음성신호들에 대하여 최적의 공통 벡터를 추출하여 주면서 공통벡터 추출에 사용된 훈련 데이터에 대해서는 100%의 인식결과를 보여준다. 그러나 공통벡터 추출을 위한 훈련 음성신호의 수를 무한히 늘릴 수 없다는 점과 공통벡터들간의 구별정보 (discriminant information)가 정의되지 않았다는 단점이 있다. 본 논문에서는 단어그룹간 (class) 구별정보를 추출된 공통벡터와 결합해 단어간의 오인식률 (error rate)을 감소시킬 수 있는 방법과 공통벡터 추출방법에 적합한 파라미터 가공 방법을 제안하였다. 공통벡터 추출방법은 음성신호의 시간 축 정규화 방법과 벡터의 차원 크기에 따라 인식시간과 인식률에 영향을 받는다. 따라서 부적절한 시간 축 정렬과 너무 큰 벡터의 차원 수는 인식률 저하 등과 같이 알고리즘의 효율성을 떨어뜨린다. 본 논문에서 제안한 방법을 사용하여 실험한 결과 알고리즘의 효율성이 증가되었으며, 기존방법보다 약 2%정도의 향상된 인식률을 얻을 수 있었다.낮추는 효과를 나타내었다.다. 이상의 결과를 통하여 추출 온도와 용매 농도에 따른 수율의 차이가 있었으며 free radical 소거 활성에서는 종자 에탄을 추출물이 과피 에탄올 추출물 보다 145배 이상의 현저히 높은 활성을 나타내었다.을 나타내었다.'Lian(연)' : repeatability, continuance, plenty and intercommunicate, 2. 'Lian(연)'-'Lian(염)': integrity, 3. 'He (하)'-'He(화)' : peace, harmony and combination, 4. 'He(하)'-'He(하)' : clear river, 5.'He(하)'-'He(하)' ; all work goes well. When the Chinese use lotus patterns in lucky omen patterns, same pronunciation and pitch of Chinese language more prominent than natural properties or the image of Buddhism. I guess that it cause praying individual's peace and happiness more serious than philosophical meaning or symbol that base in Buddhism for ordinary people.ML., -9.00~12.49 and -19.81~19.81%, respectively). Therefore, it is concluded that the two formulations are bioequivalent for both the extent and the rate of absorption after single dose administration.ation.ion.ion.ation.ion.n. fibrosis, collagen bundle) was
댐유입량 예측에 대하여 데이터 기반 머신러닝 및 딥러닝(Machine Learning & Deep Learning, ML&DL) 분석도구들이 공개되어 다양한 분야에서 ML&DL의 적용연구가 활발히 진행되고 있으며, 모델의 자체 성능향상 뿐만 아니라 모델의 특성을 고려한 데이터의 전처리도 댐유입량을 정확하게 예측하게 하는 중요한 모델성능 향상의 요소라고 할 수 있다. 특히 기존 강우자료는 적설량을 열선 설비를 통하여 녹여 강우량으로 환산되어 있으므로, 융적설에 따른 강우와 유입량의 상관관계를 왜곡하게 된다. 따라서 본연구에서는 소양강댐과 같이 융적설의 영향을 받는 댐유역에 대한 댐일유입량 예측시 겨울에 강설량이 적설이 되어 적게 유출되는 현상과, 봄에 융설로 인하여 무강우나 적은 비에도 많은 유출이 일어나는 물리적 현상을 ML&DL모델로 적용하기 위하여 필요한 강우 데이터의 전처리에 대한 연구를 수행 하였다. 강우계열, 유입량계열을 조합하여 3가지 머신러닝(SVM, RF, LGBM)과 2가지 딥러닝(LSTM, TCN) 모델을 구축하고, 최적 하이퍼파라메터 튜닝을 통하여 적합 모델을 적용하고 한 결과, NSE 0.842~0.894로 높은 수준의 예측성능을 나타내었다. 또한 융적설을 반영한 강우보정 데이터를 만들기 위하여 융적설 모의 알고리즘을 개발하고, 이를 통하여 산정된 보정강우를 머신러닝 및 딥러닝 모델에 적용한 결과 NSE 0.841~0.896 으로 융적설 적용전과 비슷한 높은 수준의 예측 성능을 나타내었으나, 융적설 기간에는 조정된 강우로 학습되어 예측되었을 때 실측유입량에 근접하는 모의결과를 나타내었다. 결론적으로, 융적설이 영향을 미치는 유역에서의 데이터 모델 적용시에는 입력자료 구축시 적설 및 융설이 물리적으로 타당한 강우-유출 반응에 적합하도록 전처리과정이 중요함을 밝혔다.