• Structural Engineering and Mechanics
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• v.91 no.4
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• pp.393-401
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• 2024

This study explores the integration of the generative AI, specifically ChatGPT (GPT-4o), into the field of structural analysis and design using the finite element method (FEM). The research is conducted in two main parts: structural analysis and structural design. For structural analysis, two scenarios are examined: one where the FEM source code is provided to ChatGPT and one where it is not. The AI's ability to understand, process, and accurately perform finite element analysis in both scenarios is evaluated. Additionally, the application of ChatGPT in structural design is investigated, including design modifications and parameter sensitivity analysis. The results demonstrate the potential of the generative AI to assist in complex engineering tasks, suggesting a future where AI significantly enhances efficiency and innovation in structural engineering. However, the study also highlights the importance of ensuring the accuracy and reliability of AI-generated results, particularly in safety-critical applications.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.5
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• pp.519-526
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• 2024

This review examines the use of halide perovskite materials in electronic devices, highlighting their exceptional optoelectronic properties and the challenges associated with them. Despite their potential for high-performance devices, practical applications are limited by sensitivity to environmental factors such as moisture and oxygen, etc. We discuss advances in enhancing stability and operational reliability, featuring innovative synthesis methods and device engineering strategies that help mitigate degradation. Furthermore, we explore the integration of perovskites in applications such as field-effect transistors and LEDs, emphasizing their transformative potential. This review also outlines future research directions, stressing the need for ongoing improvements in material stability and device integration to fully realize the commercial potential of perovskites.

• Journal of the Korea Convergence Society
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• v.11 no.4
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• pp.233-245
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• 2020

This study aims to investigate the relationship between positive psychological capital and entrepreneurial intention among middle-aged and elderly individuals who are interested in starting their own business by focusing on the mediating effect of risk sensitivity and the moderating effect of asset status. To accomplish the study's objective, a questionnaire was administered to approximately 250 middle-aged and elderly people working in Seoul from December 1 to December 31, 2019. Collected data were analyzed using SPSS 26.0. Specifically, frequency analysis and descriptive statistics were conducted, and reliability of the constructs was assessed. Factor analysis was used to measure the goodness of fit of the model developed. Finally, a structural equation model was established, and analysis was conducted on the test of the hypotheses about the mediating, moderating, and adjusting effects using the AMOS statistical package. The results revealed that positive psychological capital had a positive impact on risk sensitivity, and the path analysis of self-efficacy and entrepreneurial intention as well as resilience and entrepreneurial intention showed results of 0.042 and 0.026, respectively, supporting mediating effects. In the causal relationship between positive psychological capital and entrepreneurial intention, asset status acted as a moderator given that the chi square difference between the models was 7.096. Thus, the findings provide implications for comprehensive training programs to boost positive psychological capital and asset status in middle-aged and elderly individuals who are preparing to establish their own business. Further studies are needed to cover broader geographic areas and compare/analyze other variables associated with business startups.

• Journal of Environmental Health Sciences
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• v.46 no.5
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• pp.576-587
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• 2020

Objectives: This study calculated local residents exposures to VOCs (Volatile Organic Compounds) released into the atmosphere using the CalTOX model and carried out uncertainty analysis and sensitivity analysis. The model validity was analyzed by comparing the predicted and the actual atmospheric concentrations. Methods: Uncertainty was parsed by conducting a Monte Carlo simulation. Sensitivity was dissected with the regression (coefficients) method. The model validity was analyzed by applying r² (coefficient of determination), RMSE (root mean square error), and the Nash-Sutcliffe EI (efficiency index) formula. Results: Among the concentrations in the atmosphere in this study, benzene was the highest and the lifetime average daily dose of benzene and the average daily dose of xylene were high. In terms of the sensitivity analysis outcome, the source term to air, exposure time, indoors resting (ETri), exposure time, outdoors at home (ETao), yearly average wind speed (v_w), contaminated area in ㎡ (Area), active breathing rate (BRa), resting breathing rate (BRr), exposure time, and active indoors (ETai) were elicited as input variables having great influence upon this model. In consequence of inspecting the validity of the model, r² appeared to be a value close to 1 and RMSE appeared to be a value close to 0, but EI indicated unacceptable model efficiency. To supplement this value, the regression formula was derived for benzene with y=0.002+15.48x, ethylbenzene with y ≡ 0.001+57.240x, styrene with y=0.000+42.249x, toluene with y=0.004+91.588x, and xylene with y=0.000+0.007x. Conclusions: In consequence of inspecting the validity of the model, r² appeared to be a value close to 1 and RMSE appeared to be a value close to 0, but EI indicated unacceptable model efficiency. This will be able to be used as base data for securing the accuracy and reliability of the model.

• Tunnel and Underground Space
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• v.19 no.3
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• pp.203-212
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• 2009

The prediction of near field behavior around an underground high-level radioactive waste repository is important for the repository design as well as the safety assessment. In this study, a sensitivity analysis for seven parameters consisted of design parameters and material properties was carried out using a three-dimensional finite difference code. From the sensitivity analysis, it was found that the effects of borehole spacing, tunnel spacing, cooling time and rock thermal conductivity were more significant than the other parameters. For getting a statistical distribution of buffer and rock temperatures around the repository, an artificial neural network, backpropagation, was applied. The reliability of the trained neural network was tested with the cases with randomly chosen input parameters. When the parameter variation is within ${\pm}10%$, the prediction from the network was found to be reliable with about a 1% error. It was possible to calculate the temperature distribution for many cases quickly with the trained neural network. The buffer and rock temperatures showed a normal distribution with means of $98^{\circ}C$ and $83.9^{\circ}C$ standard deviations of $3.82^{\circ}C$ and $3.67^{\circ}C$, respectively. Using the neural network, it was also possible to estimate the required change in design parameters for reducing the buffer and rock temperatures for $1^{\circ}C$.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.5
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• pp.514-522
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• 2020

To understand the ecotoxicological differences between representative Skeletonema sp. and Dunaliella tertiolecta, both producers as international standard test species for marine ecotoxicity testing, we compared each standard test method, and comparatively analyzed the suitability of the species for environmental assessment and their sensitivity to various test substances. Although most of the test conditions were the same in each method, there were differences in limitation of pH changing and the initial inoculation density in the validation criteria, which is supposed to originate from the low growth rate of D. tertiolecta. In terms of suitability, both species showed consistency in test performance by repeatedly meeting the validation criteria required by the standard test methods. The salinity ranges available for testing were 20 and 10 psu for Skeletonema sp. and D. tertioelecta, respectively. Finally, regarding sensitivity, the toxicity sensitivity of Skeletonema sp. was relatively higher than that of D. tertiolecta for the reference toxicant, actual polluted water discharged (ballast water), and other chemicals. This implies that using at least two species of microalgae from different classification groups could help increase the reliability and objectivity of test results in the performance of marine ecotoxicity tests using producers.

• Science of Emotion and Sensibility
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• v.9 no.4
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• pp.353-366
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• 2006

The aim of this study is to characterize the optical properties of white light-emitting diodes lighting modules and then to evaluate the sensitivity of students and teachers in reacting to the optical properties of these modules. For the sake of this study, each of 5 lighting modules was introduced to the 5 test cabinets. The 5 test cabinets were evaluated and analyzed the student and teacher's sensitivity reaction. We have selected If questions on sensitivity of the lighting and evaluated these questions with semantic differential method. To verify the reliability and objectivity of the questions, the feasibility survey was carried out by a preliminary test. As a result of the test, the sensitivities on the test cabinets were classified the 4 factors, namely, activity as the first factor, stability as the second one , potency as the third one and sensitive image as the fourth one respectively. By the evaluation of student and teacher's sensitivity on the correlated color temperature, they preferred the cabinet with the higher color temperature in view of the activity and potency. And they preferred the cabinet with the lower color temperature in view of the stability factor. In the sensitive image, they preferred the 5800K, bluish white lighting regardless of the color temperature. By the evaluation on the color rendering index, they preferred the cabinet with the higher color rendering index in view of the activity, stability and sensitive image. In the potency factor, they preferred the white lighting with the middle color rendering index.

• The korean journal of orthodontics
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• v.40 no.6
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• pp.364-372
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• 2010

Objective: This study was designed to assess the diagnostic validity of digital panoramic radiographs compared to cone beam computed tomography (CBCT) in patients with temporomandibular joint disorders. Methods: Panoramic radiograph and CBCT were taken from a total of 212 joints from 106 subjects. The joints were examined by two dentists and divided into the following six groups: normal, flattening, osteophyte formation, erosion, sclerosis, and unclassified. The sensitivity and specificity of each observer and inter-observer reliability were statistically analyzed. Results: The results showed relatively high intra-observer reliability in the diagnosis of both panoramic and CBCT images and the weighted Kappa indices of panoramic and CBCT images were 0.714 and 0.727, respectively. The sensitivities of panoramic images of observer A and B to CBCT images was 82.35% and 84.30%, respectively, while the specificity of observer A and B was 58.06% and 61.54%, respectively. However, guided diagnosis from panoramic and CBCT images were statistically different (p < 0.05). Conclusions: The present study suggests that the panoramic radiograph could be used as a primary diagnostic device to detect bony changes of temporomandibular joints in clinical orthodontics, because panoramic images showed relatively high sensitivity compared to CBCT images. However, CBCT images may be one of the best choices when a more accurate diagnosis is necessary.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.268-268
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• 2016

Chemical sensors have attracted much attention due to their various applications such as agriculture product, cosmetic and pharmaceutical components and clinical control. A conventional chemical and biological sensor is consists of fluorescent dye, optical light sources, and photodetector to quantify the extent of concentration. Such complicated system leads to rising cost and slow response time. Until now, the most contemporary thin film transistors (TFTs) are used in the field of flat panel display technology for switching device. Some papers have reported that an interesting alternative to flat panel display technology is chemical sensor technology. Recent advances in chemical detection study for using TFTs, benefits from overwhelming progress made in organic thin film transistors (OTFTs) electronic, have been studied alternative to current optical detection system. However numerous problems still remain especially the long-term stability and lack of reliability. On the other hand, the utilization of metal oxide transistor technology in chemical sensors is substantially promising owing to many advantages such as outstanding electrical performance, flexible device, and transparency. The top-gate structure transistor indicated long-term atmosphere stability and reliability because insulator layer is deposited on the top of semiconductor layer, as an effective mechanical and chemical protection. We report on the fabrication of InGaZnO TFTs with silver nanowire as the top gate electrode for the aim of chemical materials detection by monitoring change of electrical properties. We demonstrated that the improved sensitivity characteristics are related to the employment of a unique combination of nano materials. The silver nanowire top-gate InGaZnO TFTs used in this study features the following advantages: i) high sensitivity, ii) long-term stability in atmosphere and buffer solution iii) no necessary additional electrode and iv) simple fabrication process by spray.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.24 no.2
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• pp.279-290
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• 1994

The purpose of this study was to compare the diagnostic accuracy of periapical radiographs and their digitized images for the detection of simulated interproximal carious lesions. A total of 240 interproximal surfaces was used in this study. The case sample was composed of 80 anterior teeth, 80 bicuspids and 80 molars which were prepared in order to distribute the surfaces from carious free to those containing simulated carious lesions of varying depths (0.5㎜, 0.8㎜, and 1.2㎜). The periapical radiographs were taken by paralleling technique and film used was Kodak Ektaspeed(E group). All radiographs were evaluated by five dentist to recognize the true status of simulated carious lesion. They were asked to give a score of 0, 1, 2, or 3. Digitized images were obtained using a commercial video processor(FOTOVIX Ⅱ- XS). And the computer system was 486 DX PC with PC Vision and frame grabber. The 17' display monitor had a resolution of 1280×1024 pixels(0.26㎜ dot pitch). But the one frame of the intraoral radiograph has a resolution of 700×480 pixels and each pixel has a grey level value of 256. All the radiographs and digital images were viewed under uniform subdued lighting in the same reading room. After a week the second interpretation was performed in the same condition. The detection of lesions on the monitor was compared with the finding of simulated interproximal carious lesions on the film images. The results were as follows: 1. When the scoring criteria was dichotomous ; lesion present and not present 1) The overall sensitivity, specificity and diagnostic accuracy of periapical radiographs and their digital images showed no statistically significant difference. 2) The sensitivity and specificity according to the region of teeth and the grade of lesions showed no statistically significant difference between periapical radiographs and their digital images. 2. When estimate the grade of lesions ; score 0, 1, 2, 3 1) The overall diagnostic accuracy was 53.3% on the intraoral films and 52.9% on digital images. There was no significant difference. 2) The diagnostic accuracy according to the region of teeth showed no statistically significant difference between periapical radiographs and their digital images. 3. The degree of agreement and reliability 1) Using gamma value to show the degree of agreement, there was similarity between periapical films and digital images. 2) The reliability of each twice interpretation of periapical films and digital images showed no statistically significant difference. In all cases P value was greater than 0.05, showing that both techniques can be used to detect the incipient and moderate interproximal carious lesions with similar accuracy.