• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.3
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• pp.317-321
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• 1986

In this paper the design of a new microstrip wide-band microwave discdriminator is presented which is composed of a binary power divider, an open stub and a shorted stub. The microstrip line frequency discriminator is designed at the center frequency of 3.2GHz. Measured discriminating bandwidth is about 20% and return loss is 15dB or more over that frequency range. Experimetal results are in good agreement with the theory.

• Journal of Veterinary Science
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• v.24 no.2
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• pp.25.1-25.6
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• 2023

An eight-year-old Maltese dog presented with diarrhea and anorexia. Ultrasonography revealed marked focal wall thickening with loss of layering in the distal ileum. Contrast-enhanced computed tomography (CT) revealed a preserved wall layer with hypoattenuating middle wall thickening. In some segments of the lesion, small nodules protruding toward the mesentery from the outer layer were observed. Histopathology revealed focal lipogranulomatous lymphangitis (FLL) with lymphangiectasia. This is the first report to describe the CT features of FLL in a dog. CT features of preserved wall layers with hypoattenuating middle wall thickening and small nodules can assist in diagnosing FLL in dogs.

• Journal of Ceramic Processing Research
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• v.13 no.spc2
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• pp.174-176
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• 2012

Piezoelectric 0.93(Na0.5K0.5)NbO3-0.07BiTiO3 (NKN-BTO) ceramics were fabricated by the mixed-oxide method and their structural and dielectric properties was investigated with the variation of sintering temperature. All specimens were crystallized in the perovskite single phase without any formation of a second phase such as pyrochlore. The average grain size of the NKN-BTO specimen sintered at 1130 ℃ is 0.32 ㎛. The specimen sintered at 1100 ℃ showed the highest relative density of 98%. Electromechanical coupling factor, relative dielectric constant and dielectric loss of the NKN-BTO specimens sintered at 1110 ℃ were 0.31, 1222 and 0.02, respectively. Curie temperature of the specimen sintered at 1110 ℃ was 445 ℃.

• Journal of the Korean Mathematical Society
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• v.59 no.2
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• pp.217-233
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• 2022

Although machine learning shows state-of-the-art performance in a variety of fields, it is short a theoretical understanding of how machine learning works. Recently, theoretical approaches are actively being studied, and there are results for one of them, margin and its distribution. In this paper, especially we focused on the role of margin in the perturbations of inputs and parameters. We show a generalization bound for two cases, a linear model for binary classification and neural networks for multi-classification, when the inputs have normal distributed random noises. The additional generalization term caused by random noises is related to margin and exponentially inversely proportional to the noise level for binary classification. And in neural networks, the additional generalization term depends on (input dimension) × (norms of input and weights). For these results, we used the PAC-Bayesian framework. This paper is considering random noises and margin together, and it will be helpful to a better understanding of model sensitivity and the construction of robust generalization.

• Earthquakes and Structures
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• v.24 no.2
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• pp.111-126
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• 2023

Highly reliable and versatile methods artificial intelligence (AI) have found multiple application in the different fields of science, engineering and health care system. In the present study, we aim to utilize AI method to investigated vibrations in the human leg bone. In this regard, the bone geometry is simplified as a thick cylindrical shell structure. The deep neural network (DNN) is selected for prediction of natural frequency and critical buckling load of the bone cylindrical model. Training of the network is conducted with results of the numerical solution of the governing equations of the bone structure. A suitable optimization algorithm is selected for minimizing the loss function of the DNN. Generalized differential quadrature method (GDQM), and Hamilton's principle are used for solving and obtaining the governing equations of the system. As well as this, in the results section, with the aid of AI some predictions for improving the behaviors of the various sport systems will be given in detail.

• Tribology and Lubricants
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• v.39 no.6
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• pp.228-234
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• 2023

In this study, reciprocating wear tests are performed on AISI 52100 bearing steel to investigate its tribological behavior in a hexagonal boron nitride (h-BN) water solution. The h-BN-based aqueous lubricant is prepared using an atoxic procedure called ultrasonic sonication in pure water. Ball-on-flat reciprocating sliding experiments are conducted, where the ball is slewed on a fixed flat at 50-㎛ displacement. The lubricating behavior of h-BN is compared with that of deionized (DI) water. Results show that the friction coefficient is higher in h-BN testing than that in DI tests, but the results are equalized as the friction coefficient reaches a stable level. Scanning electron microscopic images reveal significant material loss in the center and mild abrasion on the edge of the wear scar in h-BN tests. However, these effects are minor in DI water situations. The results of energy-dispersive X-ray spectroscopy show that considerable oxidation occurs in the central zone of the wear scar in h-BN cases with strong adhesion and material removal. These findings reveal the importance of determining ideal circumstances that can tolerate material friction and wear.

• Korean Journal of Artificial Intelligence
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• v.12 no.3
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• pp.25-31
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• 2024

The purpose of this study is to develop a sophisticated web-based artificial intelligence chatbot system designed to provide personalized dietary service for diabetic patients. According to a 2022 study, the prevalence of diabetes among individuals over 30 years old was 15.6% in 2020, identifying it as a significant societal issue with an increasing patient population. This study uses generative AI algorithms to tailor dietary recommendations for the elderly and various social classes, contributing to the maintenance of healthy eating habits and disease prevention. Through meticulous fine-tuning, the learning loss of the AI model was significantly reduced, nearing zero, demonstrating the chatbot's potential to offer precise dietary suggestions based on calorie intake and seasonal variations. As this technology adapts to diverse health conditions, ongoing research is crucial to enhance the accessibility of dietary information for the elderly, thereby promoting healthy eating practices and supporting disease prevention.

• Journal of Society of Preventive Korean Medicine
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• v.19 no.1
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• pp.109-116
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• 2015

Objective : Solar ultraviolet (UV) light can cause photoaging of human skin. Many researchers have focused on effective prevention to mitigate the aging process. This study was aimed to investigate anti-wrinkle effects of pomegranate concentration solution (PCS) using photoaged hairless mouse model. Method : To clarify the protective effect of PCS against UVB-induced photo-damage, water capacity was measured with transepidermal water loss (TEWL) in SKH-1 hairless mice. In addition, image of skin replicas was analyzed. Results : Our results showed that the PCS treatment protects skin against UVB-induced photoaging, based on the parameters including moisture capacity and TEWL. According to visual assessment of skin replica, application of 1 ml/kg PCS inhibited UV-induced wrinkle formation in mice skin as compared to the vehicle-applied control mice. Conclusion : Taken together, these results indicated that PCS could improve skin wrinkle formation induced by UVB irradiation in SHK-1 hairless mice. PCS could be applied as an anti-wrinkle agent.

• Journal of Hydrogen and New Energy
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• v.16 no.1
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• pp.40-48
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• 2005

Until recently, only perfluorinated ionomer membrane such as Nation and Aciflex practically could be successfully used in water splitting. However, these membrane are limited by high cost and loss of membrane performance such as proton conductivity at elevated temperature above 80$^{\circ}C$. The sulfonated aromatic polymers such as PEEK and PSf, polyimides, and polybenzimidazoles are expected to have lower production cost as well as satisfactory chemical and electrochemical properties. HPAs and sulfonated polymers could have a significant influence on water electrolysis performance at elevated temperatures above 80$^{\circ}C$, but these phenomena have received relatively little attention until now. Therefore, it would be desirable to investigate the interrelation between the HPA and sulfonated polymer, such as SPEEK. The SPEEK membrane were prepared by the sulfonation of PEEK, and HPA was blended with SPEEK to increase the mechanical strength and electrochemical characteristics. As a results, electrochemical characteristics such as proton conductivity and ion exchange capacity were improved with the addion of 0.5 g HPA. And the properties of polymer electrolyte, SPEEK/HPA were better than Nation membrane at elevated temperature above 80$^{\circ}C$.

• Journal of the Korean Dietetic Association
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• v.11 no.2
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• pp.242-250
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• 2005

The objective of this study is to determine the effectiveness of 4-month milk consumption in the prevention of osteoporosis in elderly women living in Asan. Subjects included 277 women age over 65 years were divided into control (n=111) and milk (n=166) groups. For those in the milk group, one cup (200ml) of partially lactose-digested low-fat milk was provided everyday for 4 months. Each subject was interviewed to assess food intake by 24-h recall method before and after milk supplementation. Prevalence of osteoporosis was determined by WHO criteria with calcaneus bone mineral density (BMD) measured by quantitative ultrasound (QUS) on left heel. After 4 months, the nutrient intake levels of control did not change while intakes of energy, protein, calcium, phosphorous, riboflavin, pyridoxin, niacin and folic acid were significantly increased in milk group. No significant changes were observed in anthropometric, and BMD in both control and milk groups. T-score of milk group, however, was significantly increased after 4 month milk consumption. Prevalence of osteoporosis was increased (27% to 32%) in control group while that of milk group was decreased (32% to 30%). When BMD and t-score changes after 4 months of milk consumption were compared between those with low baseline calcium intake and high calcium intake subjects in the milk group, BMD and t-score were significantly improved in the low baseline calcium intake group. We conclude that one cup a day milk consumption for a relatively short period of 4 months can prevent further bone loss and significantly improve intakes of both macro and micro-nutrients of elderly women.