• Korean Journal of Remote Sensing
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• v.34 no.6_1
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• pp.905-923
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• 2018

In order to generate high-resolution products using UAV images, it is necessary to analyze the sharpness of the themselves measured through image analysis. When images that have unclear sharpness of UAV are used in the production, they can have a great influence on operations such as acquisition and mapping of accurate three-dimensional information using UAV. GRD (Ground Resolved Distance) has been used as an indicator of image clarity. GRD is defined as the minimum distance between two identifiable objects in an image and is used as a concept against the GSD (Ground Sampling Distance), which is a spatial sample interval. In this study, GRD is extracted by analyzing the edge target without visual analysis. In particular, GRD to GSD ratio (GRD/GSD), or GRD expressed in pixels, is used as an index for evaluation the relative image sharpness. In this paper, GRD is calculated by analyzing edge targets at various altitudes in various shooting environments using a rotary wing. Using GRD/GSD, it was possible to identify images whose sharpness was significantly lowered, and the appropriateness of the image as an image clarity index was confirmed.

• Microbiology and Biotechnology Letters
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• v.47 no.1
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• pp.164-171
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• 2019

Radiation therapy has many side effects, such as digestive mucosal ulcers, without regard to its efficacy. The purpose of this study is to address an alternative method to replace the limitation of radiation therapy using radiomimetic microbial ribotoxins. In the evaluation of cancer therapy, we analyzed the formation of colorectal cancer (CRC) cell spheroids, which can take into account the heterogeneous cellular constitution, tumor stem cells, and the surrounding microenvironment. Ribotoxic stress interfered with the spheroid structure composed of relatively small clusters. Spheroids under ribotoxic stress were structurally sparse and their shrinkage was very slow. In the control group, the clusters of strongly aggregated cells were resistant to physical stress, but the ribotoxic stress-exposed spheroids were easily broken up by the physical stress. Moreover, the ribosome-insulted CRC cells slowly migrated to form clusters and the cell-cell junctional points in the ribosome-insulted spheroids were rarer than those in the control CRC spheroid. Moreover, levels of the cell-to-cell junctional protein E-cadherin were suppressed by ribotoxic stress in both allograft and xenograft spheroids. In conclusion, the radiomimetic microbial ribotoxins induced structural defects in CRC cell spheroids via retardation of migration and cell-cell junction in the formation of three-dimensional structures, and provides a basis for the mechanism of pharmacological radiomimetic anticancer actions as an alternate to radiotherapy against cancer.

• Science of Emotion and Sensibility
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• v.24 no.2
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• pp.65-74
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• 2021

With recent innovations in the ICT industry, the demand for wearable sensing devices to recognize and respond to biological signals has increased. In this study, a three-dimensional (3D) spacer fabric was embedded in a single-wall carbon nanotube (SWCNT) dispersive solution through a simple penetration process to develop a monolayer piezoresistive pressure sensor. To induce electrical conductivity in the 3D spacer fabric, samples were immersed in the SWCNT dispersive solution and dried. To determine the electrical properties of the impregnated specimen, a universal testing machine and multimeter were used to measure the resistance of the pressure change. Moreover, to examine the changes in the electrical properties of the sensor, its performance was evaluated by varying the concentration, number of penetrations, and thickness of the specimen. Samples that penetrated twice in the SWCNT distributed solution of 0.1 wt% showed the best performance as sensors. The 7-mm thick sensors showed the highest GF, and the 13-mm thick sensors showed the widest operating range. This study confirms the effectiveness of the simple process of fabricating smart textile sensors comprising 3D spacer fabrics and the excellent performance of the sensors.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.6
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• pp.725-731
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• 2020

In mineral resource development, resource exploration is a task to find economical minerals on the surface and underground, and the success rate is low compared to the development and production stages, and it is necessary to collect a lot of data through exploration and accurately analyze the collected information. In this study, mine spatial information was constructed using a 3D (Three-dimensional) laser scanner, and accuracy evaluation was performed to obtain a maximum deviation of 0.140 m and an average of 0.095 m in the X, Y and Z directions, and the possibility of utilizing the construction of mine geospatial information through a 3D laser scanner could be presented. In addition, the ore body modeling was performed by applying the interpolation method of the ore body section using the resource exploration results. The ore body modeling result was superimposed with the modeling result of the mine geospatial information built through the 3D laser scanner to construct the ore body modeling result based on the precise mine geospatial information. The results of ore body modeling based on mine geospatial information built through research can increase the ease of data interpretation and the accuracy of the calculated data, which will greatly increase the efficiency of work related to mineral resource development and mine damage prevention in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.116-122
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• 2021

This study quantitatively evaluated the performance improvement of a circular reinforced concrete pier under dynamic load with strengthening using a steel plate. Various three-dimensional elements were applied using the finite element program ABAQUS. The analytical parameters included the ratios of the steel cover length to the pier's total height and the ratios of the steel cover thickness to the pier diameter for inelastic-nonlinear analysis. The lower part of the pier had fixed boundary conditions, and lateral repetitive loads were applied at the top of the pier. The pier was investigated to evaluate the dynamic performance based on the load-displacement curve, stress-strain curve, ductility, energy absorption capability, and energy ratio. The yield and ultimate loads of piers with steel covers increased by 3.76 times, and the energy absorption capability increased by 4 times due to the confinement effects caused by the steel plate. A plastic hinge part of the column with a steel plate improved the ductility, and the thicker the steel plate was, the greater the energy absorption capacity. This study shows that the reinforced pier should be improved in terms of the seismic performance.

• Journal of the Korean Geotechnical Society
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• v.37 no.5
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• pp.47-63
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• 2021

Recently, the demand for three-dimensional (3D) underground maps from the perspective of digital twins and the demand for linkage utilization are increasing. However, the vastness of national geotechnical survey data and the uncertainty in applying geostatistical techniques pose challenges in modeling underground regional geotechnical characteristics. In this study, an optimal learning model based on multi-layer perceptron (MLP) was constructed for 3D subsurface lithological and geotechnical classification in Seoul, South Korea. First, the geotechnical layer and 3D spatial coordinates of each borehole dataset in the Seoul area were constructed as a geotechnical database according to a standardized format, and data pre-processing such as correction and normalization of missing values for machine learning was performed. An optimal fitting model was designed through hyperparameter optimization of the MLP model and model performance evaluation, such as precision and accuracy tests. Then, a 3D grid network locally assigning geotechnical layer classification was constructed by applying an MLP-based bet-fitting model for each unit lattice. The constructed 3D geotechnical layer map was evaluated by comparing the results of a geostatistical interpolation technique and the topsoil properties of the geological map.

• Journal of the Korean Society of Radiology
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• v.17 no.4
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• pp.557-564
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• 2023

In this study, 3D printing technology was used to compensate for the shortcomings of the use of lead, which has proven to have excellent shielding performance, and to control unnecessary human exposure. 3D printers can implement three-dimensional shapes and can immediately apply individual ideas, which has great advantages in maintaining technology supplementation while reducing the cost and duration of prototyping. Among the various special 3D printers, the FDM method was adopted, and the filament used for output was manufactured using a research extruder by mixing two materials, PLA (Poly-Lactic-Acid) and tungsten. The purpose was to verify the validity through dose evaluation and to provide basic information on the production of chapezones of various materials. The mixed filament was implemented as a morphological shield. Filaments made of a research extruder by mixing PLA and tungsten were divided into 10 %, 20 %, 30 %, 40 %, and 50 % according to the tungsten content ratio. Through the process of 3D Modeling, STL File storage, G-code generation, and output, 10 cm × 10 cm × 0.5 cm was manufactured, respectively, and dose and shielding ability were evaluated under the conditions of tube voltages of 60 kVp, 80 kVp, 100 kVp, 120 kVp, and tube currents of 20 mAs and 40 mAs.

• Journal of the Korea Society of Computer and Information
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• v.28 no.4
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• pp.41-51
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• 2023

In this paper, we propose a technique of multi-time window feature extraction for anger detection in gait data. In the previous gait-based emotion recognition methods, the pedestrian's stride, time taken for one stride, walking speed, and forward tilt angles of the neck and thorax are calculated. Then, minimum, mean, and maximum values are calculated for the entire interval to use them as features. However, each feature does not always change uniformly over the entire interval but sometimes changes locally. Therefore, we propose a multi-time window feature extraction technique that can extract both global and local features, from long-term to short-term. In addition, we also propose an ensemble model that consists of multiple classifiers. Each classifier is trained with features extracted from different multi-time windows. To verify the effectiveness of the proposed feature extraction technique and ensemble model, a public three-dimensional gait dataset was used. The simulation results demonstrate that the proposed ensemble model achieves the best performance compared to machine learning models trained with existing feature extraction techniques for four performance evaluation metrics.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3D
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• pp.499-509
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• 2006

Precast concrete deck has many advantages comparing with the in-situ concrete deck, and has been successfully applied to replacement of the deteriorated decks and to the newly constructed highway bridges in domestic region. In order to apply the precast decks into the railway bridges, however, differences of the load characteristics between the highway and the railway should be properly taken into account including the train load, longitudinal force of the continuous welded rail, acceleration or braking force, temperature change and shrinkage. Proper level of the longitudinal prestress of the tendons that can ensure integrity of the transverse joints in the deck system is of a primary importance. To this aim, the longitudinal tensile stresses induced by the design loads are derived using three-dimensional finite element analyses for the frequently adopted PSC composite girder railway bridge. The effect of the temperature change is also investigated considering the design codes and theoretical equations in an in-depth manner. The estimated proper prestress level to counteract those tensile stresses is above 2.4 MPa, which is similar to the case of the highway bridges.

• Journal of Intelligence and Information Systems
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• v.29 no.4
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• pp.69-90
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• 2023

The purpose of this study is to evaluate the service attributes and consumer reactions of telemedicine apps in South Korea and visualize their differentiation by constructing positioning maps. We crawled 23,219 user reviews of 6 major telemedicine apps in Korea from the Google Play store. Topics were derived by BERTopic modeling, and sentiment scores for each topic were calculated through KoBERT sentiment analysis. As a result, five service characteristics in the application attribute category and three in the medical service category were derived. Based on this, a two-dimensional positioning map was constructed through principal component analysis. This study proposes an objective service evaluation method based on text mining, which has implications. In sum, this study combines empirical statistical methods and text mining techniques based on user review texts of telemedicine apps. It presents a system of service attribute elicitation, sentiment analysis, and product positioning. This can serve as an effective way to objectively diagnose the service quality and consumer responses of telemedicine applications.