On validation of fully coupled behavior of porous media using centrifuge test results

Tasiopoulou, Panagiota,Taiebat, Mahdi,Tafazzoli, Nima,Jeremic, Boris Techno-Press 2015 Coupled systems mechanics Vol.4 No.1

Modeling and simulation of mechanical response of infrastructure object, solids and structures, relies on the use of computational models to foretell the state of a physical system under conditions for which such computational model has not been validated. Verification and Validation (V&V) procedures are the primary means of assessing accuracy, building confidence and credibility in modeling and computational simulations of behavior of those infrastructure objects. Validation is the process of determining a degree to which a model is an accurate representation of the real world from the perspective of the intended uses of the model. It is mainly a physics issue and provides evidence that the correct model is solved (Oberkampf et al. 2002). Our primary interest is in modeling and simulating behavior of porous particulate media that is fully saturated with pore fluid, including cyclic mobility and liquefaction. Fully saturated soils undergoing dynamic shaking fall in this category. Verification modeling and simulation of fully saturated porous soils is addressed in more detail by (Tasiopoulou et al. 2014), and in this paper we address validation. A set of centrifuge experiments is used for this purpose. Discussion is provided assessing the effects of scaling laws on centrifuge experiments and their influence on the validation. Available validation test are reviewed in view of first and second order phenomena and their importance to validation. For example, dynamics behavior of the system, following the dynamic time, and dissipation of the pore fluid pressures, following diffusion time, are not happening in the same time scale and those discrepancies are discussed. Laboratory tests, performed on soil that is used in centrifuge experiments, were used to calibrate material models that are then used in a validation process. Number of physical and numerical examples are used for validation and to illustrate presented discussion. In particular, it is shown that for the most part, numerical prediction of behavior, using laboratory test data to calibrate soil material model, prior to centrifuge experiments, can be validated using scaled tests. There are, of course, discrepancies, sources of which are analyzed and discussed.

타당화 개념모형을 이용한 대학수학능력시험 체제 진단

김성훈 한국교육평가학회 2010 교육평가연구 Vol.23 No.1

This study was to diagnose the College Scholastic Ability Test(CSAT) with an application of a logical model. The logical model was made to evidence the assumptions underlying the (planning, operation, outcome, and context) phases of the CSAT. The diagnosis of the CSAT was done by checking the validity of each phase; content validation for planning phase, context validation for operation phase, prediction and consequence validation for outcome phase. The finding was that the CSAT was not sufficiently justifiable with respect to the validations. Content validity was decreased as the expansion of the test area; prediction validity was hardly supported by CSAT-GPA coefficients; lack of consequence validity was evidenced by the lack of content validity, existence of abnormal classes and private educating, and universities' practices of using CSAT sub-scores. It was discussed that the CSAT system could be simplified assuming the contextual change such as new and varying tryout of highschool programs and of college entrance screening practices. 대학수학능력시험체제를 진단하기 위해서 타당화 논리모형을 만들고, 그 모형에 근거하여 시험체제가 정당화될 수 있을 것인지 논의하였다. 논리모형은 그 시험 체제의 개념화, 시행, 성과 등의 국면을 상정하였다. 개념화 국면의 가정 충족하기 위한 타당성으로서, 계획국면은 내용타당성을; 시행국면은 상황타당성을; 성과 국면은 예언타당성과 결과타당성을 충족하는지를 분석하였다. 내용타당성은 시험범위의 확장과 함께 떨어졌으며, 예언타당성은 부분적으로만 확인될 뿐 내신점수에 비해서 떨어지며, 결과 타당성으로서는 고등학교 교육정상화나 사회적 신뢰 구축 어느 것에서도 만족스럽지 못했다. 이상의 타당성 미흡에도 불구하고 그 체제는 상황타당성에 근거하여 유지되는 것으로 해석되었다. 고등학교 프로그램 및 대학의 입학전형의 다양화와 같은 상황 변화를 전제한 대학수학능력시험 영역의 축소, 복수 시행 및 문항은행제 등이 제언되었다.

드론과 선박을 동시 활용한 내만에서의 GOCI-II 산출물 검증

백승일 ( Seungil Baek ),고수윤 ( Sooyoon Koh ),임태홍 ( Taehong Lim ),전기성 ( Gi-seong Jeon ),도영주 ( Youngju Do ),정유진 ( Yujin Jeong ),박소현 ( Sohyeon Park ),이용탁 ( Yongtak Lee ),김원국 ( Wonkook Kim ) 대한원격탐사학회 2022 大韓遠隔探査學會誌 Vol.38 No.5

위성산출물의 검증은 위성자료를 이용하게 되는 후속 분석작업에 결정적인 영향을 미친다. 특히, 탁하고 얕은 수심의 육상 인근 해역에서의 해색산출물은 해수구성입자 분포의 복잡성으로 인하여 오랫동안 그 성능 개선이 이루어지지 않고 있어왔다. 또한, 선박이나 고정관측소를 이용한 검증은 위성산출물과 현저히 차이나는 공간범위로 인하여 명확한 한계점을 노출해왔었다. 본 연구는 우선 선박을 이용한 현장조사를 통해서 천리안해양위성2호(GOCI-II)의 주요 산출물인 원격탐사반사도, 엽록소농도, 총부유물농도, 용존유기물 등에 대한 검증을 수행하였다. 둘째로, 본 연구에서는 드론영상을 이용한 산출물 검증을 위한 초기분석결과를 제시하였다. 선박과 위성사이의 공간범위 차이를 메우기 위하여 각 선박 정점에서 드론에 탑재된 MicaSense RedEdge 카메라를 이용해 해수에 대한 다분광 영상을 획득하였다. 향후 드론을 이용한 위성산출물 검증에 활용되도록 드론 고도에 따른 해수복사휘도의 변화를 분석하였다. 제한된 숫자의 현장조사 자료 개수이지만, 검증결과, 555 nm 에서의 GOCI-II 원격탐사반사도는 약 30% 가량 과대추정 되는 것으로 나타났고, 엽록소농도 및 용존 유기물은 현장 측정값과의 상관도가 낮았다. 총부유물농도는 결정계수 약 0.6의 상관도를 나타내었고 약 20%의 불확도를 가지는 것으로 나타났다. Validation of satellite data products is critical for subsequent analysis that is based on the data. Particularly, performance of ocean color products in turbid and shallow near-land ocean areas has been questioned for long time for its difficulty that stems from the complex optical environment with varying distribution of water constituents. Furthermore, validation with ship-based or station-based measurements has also exhibited clear limitation in its spatial scale that is not compatible with that of satellite data. This study firstly performed validation of major GOCI-II products such as remote sensing reflectance, chlorophyll-a concentration, suspended particulate matter, and colored dissolved organic matter, using the in-situ measurements collected from ship-based field campaign. Secondly, this study also presents preliminary analysis on the use of drone images for product validation. Multispectral images were acquired from a MicaSense RedEdge camera onboard a UAV to compensate for the significant scale difference between the ship-based measurements and the satellite data. Variation of water radiance in terms of camera altitude was analyzed for future application of drone images for validation. Validation conducted with a limited number of samples showed that GOCI-II remote sensing reflectance at 555 nm is overestimated more than 30%, and chlorophyll-a and colored dissolved organic matter products exhibited little correlation with in-situ measurements. Suspended particulate matter showed moderate correlation with in-situ measurements (R²~0.6), with approximately 20% uncertainty.

유아교사의 다문화적 효능감 척도 타당화

성영화 ( Young Hwa Sung ),이지영 ( Ji Young Lee ) 한국아동교육학회 2010 아동교육 Vol.19 No.4

본 연구는 유아교사의 다문화적 효능감 척도를 타당화하는 데 목적이 있다. 연구대상은 서울 및 경기도에 위치한 유아교육기관에 다니는 유아교사 201명이었다. 또한 다문화 효능감 척도의 타당화 절차는 예비문항 구성과 내용 타당도 검증, 예비조사, 본 조사로 이루어졌다. 본 조사를 통해 수집된 자료는 카이검증, 확인적 요인분석, 상관분석, 그리고 Cronbach a 계수를 살펴봄으로써, 타당도와 신뢰도를 검증하였다. 그 결과는 다음과 같다. 첫째, 다문화 효능감 척도의 타당도 검증 결과이다. 다문화적 효능감 척도의 문항 변별도는 카이 검증을 통해 살펴보았으며, 그 결과 14문항은 문항 변별도가 있는 것으로 나타났다. 또한 구성타당도 검증 결과 다문화적 효능감은 일반 효능감, 수업 효능감, 분위기 효능감으로 구성되었다. 그리고 공인타당도 검증 결과 다문화적 효능감과 다문화 신념 간에는 상관이 있는 것으로 나타났다. 둘째, 다문화 효능감 척도의 신뢰도 검증 결과이다. 일반 효능감은 .83, 수업 효능감은 .91, 분위기 효능감은 .89로 나타났고, 14문항의 신뢰도 검증 결과 .92로 나타났다. 따라서 유아교사의 다문화적 효능감 척도는 유아교사의 다문화적 효능감을 측정하기에 타당하고 신뢰도운 것으로 밝혀졌다. The purpose of this study was to validation of multicultrual efficacy scale for young children`s teachers. The subjects of this study were 201 young children`s teacher who worked kindergarten or day care centers located in seoul and Gyeonggi. The procedure of the multicultural efficacy scale validation was consisted of preliminary items, content validation questions, preliminary investigation, and this investigation. The collected date were analyzed by Chi-square test, confirmatory factor analysis, Pearson`s r and Cronbach`s a. The results were as follows. First, multicultural efficacy scale is result the validation. The validation about the item of multicultural efficacy scale was investigated by Chi-square test and multicultural efficacy of 14 items showed that there is a question of discrimination. and result of the construct validity, multicultural efficacy of young children`s teacher was consist of the following three factor: multicultural general efficacy, multirulcural teaching efficacy, and multicultural climate efficacy. And multicultural efficacy and multicultural belief of young children`s teacher were correlated. Second, multicultural efficacy scale is result the reliability. The result of the reliability, Cronbach a of multicultural general efficacy was 83, multirulcural teaching efficacy was .91, multicultural climate efficacy was .89, 14 items were .92. Therefore multicultural efficacy of young children`s teacher were validity and reliability.

맞벌이 가족의 아동복지감 척도에 대한 타당화 연구

도미향 한국영유아보육학회 2003 한국영유아보육학 Vol.0 No.33

The purpose of this study was to examine the validating the child well-being sense of the Dual Income Family scale to children. As the result, the child well-being sense scale contained 4variables (sense of child emotional well-being, satisfaction sense of child on the mother's role, satisfaction sense of child on the father's role, satisfaction sense of child on the mother's working) and 4 rating scale of 32items. Almost every items had high discriminating power. The reliability was satisfactory on the total readiness score. After the scale development, various validation procedures was using sample of 632. Three examples are concurrent validity, related validity, and. contrasted group validity. There appeared to be, sufficient evidence for validity of child psychological well-being instrument form the validity procedures. The present investigations contributed to understanding of child psychological well-being of the Dual Income Family. And the practical significance of the present study lied in the validation on the development of specific instrument for the measurement of the particular aspects of child well-being of the Dual Income Family. The validation of an instrument for the measurement of such variables provides the opportunity for assessing child well-being of the Dual Income Family scale.

시계열 교차검증을 적용한 2,3-BDO 분리공정 온도예측 모델의 초매개변수 최적화

안나현 ( Nahyeon An ),최영렬 ( Yeongryeol Choi ),조형태 ( Hyungtae Cho ),김정환 ( Junghwan Kim ) 한국화학공학회 2021 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.59 No.4

최근 인공지능에 대한 관심이 높아짐에 따라 화학공정분야에서도 인공지능을 활용한 연구가 많아지고 있다. 그러나 인공지능 기반 모델이 충분히 일반화되지 않아 학습에 이용되지 않은 새로운 데이터에 대한 예측률이 떨어지는 과적합 현상이 빈번하게 일어나고 있으며, 교차검증은 과적합을 해결하는 방법 중 하나이다. 본 연구에서는 2,3-BDO 분리 공정 온도 예측 모델의 초매개변수 중에서 배치 개수와 반복횟수를 조정하기 위해 시계열 교차검증을 적용하고 일반적으로 사용되는 K 겹 교차검증과 비교하였다. 결과적으로 K 겹 교차검증을 사용했을 때 보다 시계열 교차검증 방식을 사용했을 때 MAPE는 0.61% 증가한 반면 RMSE는 9.06% 감소하였고 학습 시간은 198.29초 적게 소요되었다. Recently, research on the application of artificial intelligence in the chemical process has been increasing rapidly. However, overfitting is a significant problem that prevents the model from being generalized well to predict unseen data on test data, as well as observed training data. Cross validation is one of the ways to solve the overfitting problem. In this study, the time-series cross validation method was applied to optimize the number of batch and epoch in the hyperparameters of the prediction model for the 2,3-BDO distillation process, and it compared with K-fold cross validation generally used. As a result, the RMSE of the model with time-series cross validation was lower by 9.06%, and the MAPE was higher by 0.61% than the model with K-fold cross validation. Also, the calculation time was 198.29 sec less than the K-fold cross validation method.

대학생 주체성 척도 개발 및 타당화

기희경,김정섭 부산대학교 교육발전연구소 2023 교육혁신연구 Vol.33 No.4

Purpose: This study aimed to develop and validate a scale of university student agency. The development plan, item development, validation, and pilot survey were conducted to develop and validate the scale. Method: Professionals’ reviews for the content validity were performed for the scale development. The pilot survey was conducted on 501 college students in Seoul, Busan, Gyeonggi, and Gyeongsang areas with 24 items to validate for the validation. The confirmatory factor analysis was performed with a total of 440 university students’ data. For the criterion-based validation, SPSS (25.0) Amos (22.0) were used for the correlation, concurrent validity and reliability. Results: The agency scale was identified as a second-order model including sub-construct factors respectively: autonomy, responsibility, and capabilities. The result of the reliability for the final 24 items is overall .929, autonomy .884, responsibility .881, and capabilities .835. Conclusion: The study contributes that the university student agency scale developed and has uniqueness a reliable and valid scale measuring the university student agency.

중·고등학생을 위한 진로메타인지 척도 개발 및 타당화

김태승,이동혁,고윤경,서희주,김혜윤,천재운 한국진로교육학회 2023 진로교육연구 Vol.36 No.4

본 연구의 목적은 중·고등학생을 위한 진로메타인지 척도를 개발하고 타당화하는 것이다. 이를 위해 진로메타인지의 구성개념에 근거하여 예비문항 60개를 구성 후 전문가 내용타당도를 총 3명(박사 3명)에게 검증하였다. 이후 중·고등학생 3명에게 안면타당도를 검증하고 반영하여 수정된 문항으로 중·고등학생 400명씩 2회에 걸쳐 총 800명에게 문항 선정을 위한 설문조사를 실시하였다. 1차 조사는 400명의 자료를 분석하여 60문항에서 20문항을 추출하였다. 이후 2차 조사는 중·고등학생 400명에게 실시하여 최종 18문항을 선정하였다. 최종 선정된 문항의 타당화를 위하여 중·고등학생 200명에게 설문조사를 실시하였다. 타당화 도구로는 메타인지 척도(State Metacognition Inventory; SMI), 진로개발역량검사 중 진로설계역량 척도를 활용하였다. 타당화를 위해 기술통계 및 상관분석, 신뢰도 검증, 확인적 요인분석, 수렴타당도, 판별타당도를 확인한 결과, 중·고등학생 진로메타인지 척도가 안정적인 요인구조와 신뢰도를 지니고 있음을 확인하였다. 중·고등학생을 위한 진로메타인지 척도의 전체적인 모형 적합도는 Bartlett 구형성 검증 χ2 = 1422.025(df=153, p<.000) CFI는 .941, TLI는 .930으로 상대적 적합도 지수에서 현실적으로 적합함이 검증되었다. 절대적 적합도 지수 RMSEA는 .058로 양호한 적합도를 보였다. 또한 Cronbach’s α는 계획 .82, 평가 .85, 조절 .79, 모니터링 .90으로 모든 요인에서 양호한 것으로 나타났으며, 전체 문항의 Cronbach’s α는 .89로 확인되었다. 이를 통해 선행연구에서 검증된 대학생 진로메타인지 척도의 구성개념이 중·고등학생에게도 유사하게 적용된다는 것을 확인하였다. 또한 중·고등학생용 진로메타인지 척도를 개발하고 신뢰도와 타당도를 확인하였으며, 이를 통해 추후 진로메타인지 척도를 활용한 다양한 진로 분야의 연구 영역을 확장하였다는 의의가 있다. 이런 연구결과를 바탕으로 중·고등학생용 진로메타인지 척도 개발 및 타당화의 의의와 시사점에 대하여 논의하였다. This study develops and validates a career metacognition scale for middle·highschool stundents. For this purpose, 60 preliminary questions were constructed based on the concept of career metacognition, and the content validity was verified by a total of 3 experts (3 doctors). Afterwards, face validity was verified and reflected on three middle and high school students, and a preliminary survey to select questions was conducted on a total of 800 students twice, with 400 middle and high school students each, using the revised questions. Data from 400 people in the first preliminary survey were analyzed and 20 questions were extracted from 60 questions. Afterwards, a second preliminary survey was conducted on 400 middle and high school students, and the final 18 questions were selected. To validate the final selected questions, a survey was conducted on 200 middle and high school students. As validation tools, the State Metacognition Inventory (SMI) and the career design competency scale from the career development competency test were used. Validation included descriptive statistics and correlation analysis, reliability verification, confirmatory factor analysis, convergent validity, and discriminant validity. As a result, it was confirmed that the youth career metacognition scale had a stable factor structure and reliability. The overall model fit of the career metacognitive scale for middle·highschool stundents was Bartlett test of sphericity χ2 = 1422.025 (df=153, p<.000), CFI was .941, and TLI was .930, which was verified as realistic fit based on the relative fit index. The absolute fit index RMSEA was .058, showing good fit. In addition, Cronbach’s α was found to be good for all factors, with planning at .82, evaluation at .85, control at .79, and monitoring at .90, and Cronbach’s α for all questions was found to be .89. Through this, it was confirmed that the concept of the college student career metacognition scale verified in previous studies was similarly applied to middle·highschool stundents, especially middle and high school students. In addition, a career metacognition scale for middle·highschool stundents was developed and reliability and validity were confirmed, which is significant in expanding the scope of future research in various career fields using the career metacognition scale. Based on these research results, the significance and implications of developing and validating a career metacognition scale for middle·highschool stundents were discussed.

The Precision Validation of the Precise Baseline Determination for Satellite Formation

최종연,이상정 한국우주과학회 2011 Journal of Astronomy and Space Sciences Vol.28 No.1

The needs for satellite formation flying are gradually increasing to perform the advanced space missions in remote sensing and observation of the space or Earth. Formation flying in low Earth orbit can perform the scientific missions that cannot be realized with a single spacecraft. One of the various techniques of satellite formation flying is the determination of the precise baselines between the satellites within the formation, which has to be in company with the precision validation. In this paper, the baseline of Gravity Recovery and Climate Experiment (GRACE) A and B was determined with the real global positioning system (GPS) measurements of GRACE satellites. And baseline precision was validated with the batch and sequential processing methods using K/Ka-band ranging system (KBR) biased range measurements. Because the proposed sequential method validate the baseline precision, removing the KBR bias with the epoch difference instead of its estimation, the validating data (KBR biased range) are independent of the data validated (GPS-baseline)and this method can be applied to the real-time precision validation. The result of sequential precision validation was 1.5~3.0 mm which is similar to the batch precision validation.

Development and Internal/External Validation of a Prediction Model for Weight Loss Following Gastric Cancer Surgery: A Multicenter Retrospective Study

( Ji-hyeon Park ),( Seong-ho Kong ),( Do Joong Park ),( Han-kwang Yang ),( Jong Won Kim ),( Ki Bum Park ),( In Cho ),( Sun-hwi Hwang ),( Dong-wook Kim ),( Su Mi Kim ),( Seung-wan Ryu ),( Seong Chan Go 한국정맥경장영양학회 2022 한국정맥경장영양학회지 Vol.14 No.2

Purpose: To develop an individualized model for predicting the extent of unintentional weight loss following gastrectomy in patients with gastric cancer based on related risk factors and to externally validate this model using multicenter clinical data in Korea. Materials and Methods: Among gastric cancer patients who underwent curative gastrectomy at 14 different gastric cancer centers, clinical data from patients with more than one weight measurement during the three-year followup period were retrospectively collected. Risk factors associated with weight loss in gastric cancer patients after gastrectomy were analyzed, and a predictive model was developed. Internal and external validation were performed. Results: The data from 2,649 patients were divided into a derivation set (n=1,420 from Seoul National University Hospital) and validation set (n=1,229 from 13 different gastric cancers). Postoperative duration (six vs. 12, 24, or 36 months), sex (female vs. male), age, preoperative body mass index, type of surgery (pylorus-preserving vs. total, distal or proximal gastrectomy), and cancer stage (I vs. II or III) were included in the final prediction model. The model showed approximately 20% accuracy in predicting weight loss at each period: R2 at six, 12, 24 and 36 months after gastrectomy in internal validation=0.20, 0.21, 0.17, and 0.18, respectively, and in external validation=0.20, 0.22, 0.18, and 0.18, respectively. Calibration slopes of internal and external validation were 0.95 and 1.0, respectively. Conclusion: Although predictive accuracy of the model did not reach an acceptable level, repeated external validation measurements showed high reliability. The model may serve as a basic reference in clinical practice.