• Journal of the Korean Data and Information Science Society
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• 제26권2호
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• pp.495-504
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• 2015

The Gaussian geostatistical model has been widely used for modeling spatial data. However, this model suffers from a severe difficulty in computation because inference requires to invert a large covariance matrix in evaluating log-likelihood. In addressing this computational challenge, three strategies have been employed: likelihood approximation, lower dimensional space approximation, and Markov random field approximation. In this paper, we reviewed statistical approaches attacking the computational challenge. As an illustration, we also applied integrated nested Laplace approximation (INLA) technology, one of Markov approximation approach, to real data to provide an example of its use in practice dealing with large spatial data.

• 한국신뢰성학회지:신뢰성응용연구
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• 제17권2호
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• pp.83-91
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• 2017

Purpose: The purpose of this study is to develop a quality assurance model and to determine appropriate warranty period for a guided missile using its field data. Methods: 10 years of actual firing data is collected from the defense industry company and military. Parametric maximum likelihood estimation for a reliability function is determined with the data. Results: The reliability function estimates average lifetime of the missile. That function shows a user requirement, 80% reliability (lifetime) is come up when 8 years have passed, which is longer than the estimates in the missile's development phase. Conclusion: Quality assurance warranty for a guided missile must be established with actual test data. It is necessary to update and modify the reliability prediction and the warranty period with actual field test data.

• 농업과학연구
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• 제42권1호
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• pp.53-61
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• 2015

Development of highly efficient and energy-saving tractors has been one of the issues in agricultural machinery. For design of such tractors, measurement and analysis of load on major power transmission parts of the tractors are the most important pre-requisite tasks. Objective of this study was to perform pre-processing procedures before effective analysis of load data of agricultural tractors (30, 75, and 82 kW) during major field operations such as plow tillage, rotary tillage, baling, bale wrapping, and to select the suitable pre-processing method for the analysis. A load measurement systems, equipped in the tractors, were consisted of strain-gauge, encoder, hydraulic pressure, and radar speed sensors to measure torque and rotational speed levels of transmission input shaft, PTO shaft, and driving axle shafts, pressure of the hydraulic inlet line, and travel speed, respectively. The entire sensor data were collected at a 200-Hz rate. Plow tillage, rotary tillage, baling, wrapping, and loader operations were selected as major field operations of agricultural tractors. Same or different farm works and driving levels were set differently for each of the load measuring experiment. Before load data analysis, pre-processing procedures such as outlier removal, low-pass filtering, and data division were performed. Data beyond the scope of the measuring range of the sensors and the operating range of the power transmission parts were removed. Considering engine and PTO rotational speeds, frequency components greater than 90, 60, and 60 Hz cut off frequencies were low-pass filtered for plow tillage, rotary tillage, and baler operations, respectively. Measured load data were divided into five parts: driving, working, implement up, implement down, and turning. Results of the study would provide useful information for load characteristics of tractors on major field operations.

• Geomechanics and Engineering
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• 제16권4호
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• pp.399-413
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• 2018

This paper addresses the issue of field measurement of excavation damage zone (EDZ) and its numerical simulation method considering both excavation unloading and blasting load effects. Firstly, a 2000 m-deep rock cavern in China is focused. A detailed analysis is conducted on the field measurement data regarding the mechanical response of rock masses subjected to excavation and blasting operation. The extent of EDZ is revealed 3.6 m-4.0 m, accounting for 28.6% of the cavern span, so it is significantly larger than rock caverns at conventional overburden depth. The rock mass mechanical response subjected to excavation and blasting is time-independent. Afterwards, based on findings of the field measurement data, a numerical evaluation method for EDZ determination considering both excavation unloading and blasting load effects is presented. The basic idea and general procedures are illustrated. It features a calibration operation of damage constant, which is defined in an elasto-plastic damage constitutive model, and a regression process of blasting load using field blasting vibration monitoring data. The numerical simulation results are basically consistent with the field measurement results. Further, some issues regarding the blasting loads, applicability of proposed numerical method, and some other factors are discussed. In conclusion, the field measurement data collected from the 2000 m-deep rock cavern and the corresponding findings will broaden the understanding of tunnel behavior subjected to excavation and blasting at great depth. Meanwhile, the presented numerical simulation method for EDZ determination considering both excavation unloading and blasting load effects can be used to evaluate rock caverns with similar characteristics.

• 대한원격탐사학회지
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• 제40권1호
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• pp.93-101
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• 2024

Accurate field crop classification is essential for various agricultural applications, yet existing methods face challenges due to diverse crop types and complex field conditions. This study aimed to address these issues by combining support vector machine (SVM) models with multi-seasonal unmanned aerial vehicle (UAV) images, texture information extracted from Gray Level Co-occurrence Matrix (GLCM), and RGB spectral data. Twelve high-resolution UAV image captures spanned March-October 2021, while field surveys on three dates provided ground truth data. We focused on data from August (-A), September (-S), and October (-O) images and trained four support vector classifier (SVC) models (SVC-A, SVC-S, SVC-O, SVC-AS) using visual bands and eight GLCM features. Farm maps provided by the Ministry of Agriculture, Food and Rural Affairs proved efficient for open-field crop identification and served as a reference for accuracy comparison. Our analysis showcased the significant impact of hyperparameter tuning (C and gamma) on SVM model performance, requiring careful optimization for each scenario. Importantly, we identified models exhibiting distinct high-accuracy zones, with SVC-O trained on October data achieving the highest overall and individual crop classification accuracy. This success likely stems from its ability to capture distinct texture information from mature crops.Incorporating GLCM features proved highly effective for all models,significantly boosting classification accuracy.Among these features, homogeneity, entropy, and correlation consistently demonstrated the most impactful contribution. However, balancing accuracy with computational efficiency and feature selection remains crucial for practical application. Performance analysis revealed that SVC-O achieved exceptional results in overall and individual crop classification, while soybeans and rice were consistently classified well by all models. Challenges were encountered with cabbage due to its early growth stage and low field cover density. The study demonstrates the potential of utilizing farm maps and GLCM features in conjunction with SVM models for accurate field crop classification. Careful parameter tuning and model selection based on specific scenarios are key for optimizing performance in real-world applications.

• 한국응급구조학회지
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• 제28권1호
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• pp.47-62
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• 2024

Purpose: This study aimed to provide basic data for infection control education plans based on infection control awareness and performance of paramedic students during clinical field training. Methods: Data were collected from paramedic students with experience in clinical field training. The data collection period was from May 4, 2023, to June 4, 2023, and 132 copies of the collected survey were analyzed using the SPSS27.0 program. Results: Infection control awareness and performance were 4.80±0.24 points and 4.49±0.55 points out of 5, respectively. The infection control awareness of the participants according to clinical field training-related characteristics differed significantly in university education before clinical field training (t=2.100, p=.038). In addition, there were significant differences in performance in the number of clinical field training sessions (F=9.149, p=.000), hospital education before clinical field training (t=5.365, p=.000), and hospital education during clinical field training (t=3.094, p=.002). Conclusion: Before clinical field training, schools should provide infection control education that combines theory and practice suitable for hospital practice so that students can complete the infection control education organized by the hospital. Furthermore, if a university develops infection control in the clinical field training guidelines, it will have a positive impact on students' infection control performance through prior education.

• 정보관리학회지
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• 제34권4호
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• pp.59-79
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• 2017

본 연구는 Figshare를 통해 공유되고 있는 문헌정보학분야 연구데이터의 유형, 주제, 공개 수준 등을 분석하고 재사용성이 상대적으로 높은 데이터의 특성을 통계적으로 해석해 보았다. 분석 결과 데이터의 유형은 dataset과 paper 유형이, 주제 분야는 open access와 research data가 가장 많은 비중을 차지하였으며, 70%에 가까운 연구데이터가 pdf와 같이 편집과 재사용이 원활하지 않은 형태로 공개되어 있는 것으로 조사되었다. 또한 연구데이터의 특성과 활용 정도간의 관계 분석 결과, 주제에 있어서는 APC(Article Processing Charge)를 비롯한 open access 영역이 가장 많이 활용되고 있는 것으로 나타났으며, 데이터 유형에 있어서는 paper의 활용도가 가장 높은 것으로 나타났다.

• 대한토목학회논문집
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• 제42권5호
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• pp.599-606
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• 2022

공용 중 강교량의 피로 평가에 활용할 수 있는 현장계측 데이터에는 대표적으로 변형률 계측과 Brigde Weight-In-motion (BWIM)이 있다. AASHTO The Manual For Bridge Evaluation에 따라, 대상 교량에서 계측된 데이터로부터 피로 상세에 가해지는 유효응력범위 및 반복응력 횟수를 추정할 수 있다. 추정된 유효응력범위와 반복응력 횟수를 통해 피로 손상 누적에 의한 신뢰도분석을 수행할 수 있다. 하지만 현장계측 데이터로부터 유효응력범위 및 응력범위 반복횟수를 추정하는 절차가 평가규정에 구체적으로 제시되어 있지 않고, 계측 데이터의 종류 또는 처리방법에 따른 피로 평가결과의 차이를 정량적으로 비교한 연구는 아직 미비한 실정이다. 본 연구에서는 공용 중 교량에서 동시에 계측한 변형률계 및 BWIM 데이터를 활용하여 피로 신뢰도평가를 수행하여, 활용되는 현장계측 데이터의 종류에 따른 평가결과의 차이에 대해 정량적으로 검토하였다. 이때, BWIM 데이터를 활용한 피로 신뢰도평가 시 구조해석모델의 정밀성이 평가결과에 미치는 영향을 검토하기 위해 평가 대상 교량의 뼈대요소 해석모델과 Shell-Solid 해석모델을 구축하였다. 또한, BWIM 데이터로부터 유효응력범위와 반복응력 횟수를 추정하기 위한 두 종류의 데이터 처리 방법을 정의하였으며, 이로 인한 피로 신뢰도 차이 역시 검토하였다.

• 한국농공학회지
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• 제39권2호
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• pp.53-61
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• 1997

The interface system, GIS-AGNPS was to be validated with field data from six tested small watersheds ranging from 0.7 to 4.7$km^2$ in size which have steep topography and complex landuses. The model validation involved the calibration of input parameters and component modifications, in efforts to develop a model applicable to general uses for identifying and controlling nonpoint source pollution loads from agricultural watersheds. The simulated direct runoff from AGNPS was in good agreement with the field data for the averaged antecedent moisture conditions or AMC- II. The results differed, however, from the observed for AMC- I or III. A simple empirical relationship was proposed to estimate the curve number for AMC- I or m from AMC- II, which was found to result in simulated runoff close to the observed. The peak runoff relationship at AGNPS was also modified to reflect the watershed conditions and tested satisfactorily with the field data. The simulated sediment yields from the watersheds were fair as compared to the observed. Nutrient loads simulated from the model were different from the observed data. It appeared that the model was incapable of adequate depicting nutrient transport processes at paddy field and other landuses of the tested watersheds. Some modifications may be needed for the accurate representing the processes at paddy field.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제11권2호
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• pp.93-100
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• 2022

기존의 데이터 검색 방법으로는 키워드 중심의 검색 방법이 주로 사용되나, 이는 전문적인 용어가 많이 쓰이는 법률 분야의 검색 방법으로는 적합하지 않다. 이에 대해 본 논문에서는 법률 분야의 효과적인 데이터 검색 방안을 제안한다. 법률 도메인의 자연어처리 분야에서 문장 간의 유사성을 판단하는 데 최적화된 임베딩 방법에 관하여 서술한다. 법률문장을 TF-IDF를 이용하여 키워드 기반으로 임베딩하거나 Universal Sentence Encoder를 이용하여 의미 기반으로 임베딩을 한 후, BERT모델을 결합하여 법률 분야에서 문장 간 유사성을 검사하여 데이터를 검색하는 최적의 방안을 제안한다.