• Earthquakes and Structures
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• v.23 no.1
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• pp.13-21
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• 2022

Masonry constructions exhibit uncertain behaviors under dynamic effects such as seismic action. Complex issues arise in the idealization of structural systems of buildings having different material types and mechanical properties. In this study, the structural behavior of a vaulted masonry building constructed using full clay brick and lime-based mortar and sitting on consecutive arches was investigated by experimental and numerical approaches. The dimensions of the structure built in the laboratory were 391 × 196 cm, and its height was 234 cm. An incremental repetitive loading was applied to the prototype construction model. Along the gradually increasing loading pattern, the load-displacement curves of the masonry structure were obtained with the assistance of eight linear displacement transducers. In addition, crack formation areas, and relevant causes of its formation were determined. The experimental model was idealized using the finite element method, and numerical analyses were performed for the area considered as linear being under similar loading effect. From the linear analyses, the displacement values and stress distribution of the numerical model were obtained. In addition, the effects of tie members, frequently being used in the supports of curved load-bearing elements, on the structural behavior were examined. Consequently, the experimental and numerical analysis results were comparatively evaluated.

• Steel and Composite Structures
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• v.43 no.4
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• pp.511-522
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• 2022

An experimental investigation to study the behaviour of connections between cold-formed steel (CFS) joist and plywood structural panel is presented in this paper. Material testing on CFS and plywood was carried out to assess their mechanical properties and behaviour. Push-out tests were conducted to determine the slip modulus and failure modes of three different shear connection types. The employed shear connectors in the study were; size 14 (6mm diameter) self-drilling screw, M12 coach screw, and M12 nut and bolt. The effective bending stiffness of composite cold-formed steel and plywood T-beam assembly is calculated based on the slip modulus values computed from push-out tests. The effective bending stiffness was increased by 25.5%, 18% and 30.2% for self-drilling screw, coach screw, nut and bolt, respectively, over the stiffness of cold-formed steel joist alone. This finding suggests the potential to enhance the structural performance of composite cold-formed steel and timber flooring system by mobilisation of composite action present between timber sheathing and CFS joist.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.5
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• pp.53-59
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• 1996

Warm deep drawing of single-action dies using local heating has appeared to be an alternative attractive production method of multi-operation die sets generally used at room temperature in deep drawing of rectangular cup. Uniaxial tensile tests and deep drawing tests of various materials are carried out and the effect of temperature on tensile properties and drawability are examined at temperatures up to 200 .deg. C under three kinds of lubricants of teflon film, vinyl film and drawing oil. Good formability is achieved when punch and die temperature were differentiated intentionally in order to get large tensile strength(TS) at punch shoulder protion and small TS at die side. Throughout the experiments, it has been shown that the limiting drawing height of STS316L was increased with heating die and blank holder at 100 .deg. C, but that of STS430 wasn't. When vinyl or teflon film was attached on the plates, the drawability was increased considerably.

• Earthquakes and Structures
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• v.22 no.3
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• pp.319-330
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• 2022

Retrofit of soft-story buildings due to seismic loads using Gap-Inclined-Brace (GIB) system is considered a new retrofit technique that aims to maintain both strength and stiffness of structure. In addition, it provides more ductility and less P-delta effect, and subsequently better performance is observed. In this paper, the effect of the eccentricity between GIB and the retrofitted column due to installation on the efficiency of the retrofitting system is studied. In addition, a modification in the determination method of GIB properties is introduced to reduce the eccentricity effect. Also, the effect of GIB system on the seismic response of mid-rise buildings with different heights considering soft-story at various heights has been studied. A numerical model is developed to study the impact of such system on the response of retrofitted soft-story buildings under the action of seismic loads. To achieve that goal, this model is used to perform a numerical investigation, by considering five case study scenarios represent several locations of soft-story of two mid-rise reinforced concrete buildings. At first, Non-linear static pushover analysis was carried out to develop the capacity curves for case studies. Then, Non-linear time history analyses using ten earthquake records with five peak ground accelerations is performed for each case study scenario before and after retrofitting with GIB. The results show that large GIB eccentricity reduce the ultimate lateral resistance and deformation capacity of the retrofitting system. Moreover, the higher the retrofitted building, the more deformation capacity is observed but without significant increase in ultimate lateral resistance.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.27-28
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• 2021

The search for new corrosion inhibitors for different corrosive mediums is a never-ending task. In the present work, the corrosion inhibition behavior and adsorption mechanism of two novel synthetic thiazolidinedione derivatives noted MTZD and ATZD in 3.5 wt.% NaCl solution on copper were investigated. Electrochemical, scanning electron microscope (SEM), atomic force microscopy (AFM) techniques were used along with first-principles DFT calculations. At maximum inhibitor concentration i.e., 300 ppm corrosion inhibition efficiency reached maximum up to 90% and 96% for MTZD and ATZD, respectively, and thereby followed the order of ATZD > MTZD. The inhibition efficiency increased up to 24 h of immersion, and then decreased after 48h immersion. The potentiodynamic curves suggested that the inhibition action of tested compounds is a mixed type of inhibitor. The first-principles DFT calculations suggested that compounds under investigation formed covalent bonds with Cu(111) surface via reactive sites. SEM and AFM results confirmed the formation of protective barrier that prevent corrosion attack.

• The Journal of Korean Medical History
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• v.35 no.2
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• pp.19-34
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• 2022

Objectives : The purpose of this study was to compare the prescriptions used for insomnia in Uihagimmun and Donguibogam. Methods : In Uihagimmun, 17 prescriptions were selected. If there was a change in the medicinal material, the altered herbal medicine was indicated along with the prescription name. In Donguibogam, 14 prescriptions were selected. Each prescription was analyzed by dividing it into prescription composition, and herbal medicine. Medications constituting a prescription were classified according to the classification of Korean herbal medicines and arranged based on their frequency of appearance. Result : The causes of insomnia were classified mainly as exhaustion in Uihagimmun and as exhaustion, stress, low energy, aging and discomfort in Donguibogam. In Uihagimmun, numerous medicines were used to relieve fever, and in Donguibogam, the use of stabilizers increased. More warm medicines were used in Donguibogam than in Uihagimmun, and the taste trend was similar in each. Conclusions : The types of causes of insomnia increased more in Donguibogam than Uihagimmun. Accordingly, the two books showed differences in drug classification and properties of a medicine. However, in terms of taste and action of medicinal herbs, they showed similar patterns, and there was only a difference in the order of frequency.

• Biomedical Science Letters
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• v.29 no.3
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• pp.121-129
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• 2023

Parkinson's disease (PD) is a progressive neurodegenerative disorder that affects millions of people worldwide. The conventional treatment model for PD have harmful side effects, such as dyskinesia, hallucinations, nausea, and fatigue, and are expensive. As a result, natural products derived from medicinal herbs, fruits, and vegetables have emerged as potential therapeutic strategies for PD. These natural products have been traditionally used to treat various diseases and have been shown to possess anti-oxidative and anti-inflammatory properties, as well as inhibitory roles in protein misfolding, mitochondrial homeostasis, neuroinflammation and other neuroprotective processes. In addition, they have fewer side effects and are generally less expensive than conventional drugs. It also discusses the limitations of current treatments and the potential of natural remedies derived from plants to treat PD in new ways or as supplements to existing treatments. The multifunctional mechanisms of medicinal plants that may be utilized to treat PD are also discussed, including the modulation of neurotransmitter systems, the enhancement of neurotrophic factors, and the inhibition of apoptosis. While more research is needed to fully understand their mechanisms of action and efficacy, natural products have the potential to provide safer and more effective treatment options for patients with PD.

• Journal of Mushroom
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• v.21 no.4
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• pp.195-199
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• 2023

The fungus Alternaria alternata, responsible for causing brown to black spotting on numerous fruits and vegetables globally, was identified in 2022 as the causative pathogen of brown spot disease in potatoes in Korea. In pursuing potential inhibitors against A. alternata growth, we evaluated 15 mushroom culture filtrates: eight from Trametes spp. and seven from Polyporus spp., known for their antibacterial and anticancer properties. Antifungal activity was assessed by exposing each filtrate to A. alternata on a paper disc. Four filtrates displayed inhibitory action against the fungus, albeit with mild effects. Our findings highlight the potential of Trametes and Polyporus fungi as emerging antifungal candidates, offering promise in preventing potato brown spots.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.3
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• pp.337-344
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• 2024

This work focuses on improving the light-harvesting efficiency of thin-film silicon solar cells through innovative multi-architecture surface modifications. To create a regular optical structure, a lithographic process was performed to form it on a glass substrate through various etching processes, from Etch-1 to Etch-3. AZO was deposited on top of the structures and re-etched to create a multi-architectural surface. These surface-modified structures improved the light absorption and overall performance of the solar cell through changes in optical and physical properties, which we will analyze. In addition, we investigated the effect of post-cleaning on the etched glass structures through EDX analysis to understand the mechanism of the etching action. The results of this study are expected to provide important guidelines for the design and fabrication of solar cells and other photovoltaic devices.

• Biomedical Science Letters
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• v.30 no.3
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• pp.137-142
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• 2024

The aim of this study was to investigate the inhibitory effects of Alismatis rhizoma extract on breast cancer cell growth and elucidate the underlying mechanisms. The growth inhibitory effects of Alismatis rhizoma extract on breast cancer cells were measured using the WST-1 assay, while its impact on relevant proteins and genes was analyzed using real-time polymerase chain reaction. The results demonstrated significant inhibition of breast cancer cell growth by Alismatis rhizoma, with the inhibitory effect showing a positive correlation with the dosage, treatment duration, and quantity. Furthermore, Alismatis rhizoma extract markedly decreased the expression levels of cell cycle protein D1 and suppressed cell migration and invasion. In conclusion, Alismatis rhizoma exhibits the potential to inhibit breast cancer cell growth, possibly by regulating cell cycle progression and inhibiting cell migration and invasion. These findings suggest that Alismatis rhizoma extract possesses anticancer properties against human breast cancer cells. Further investigation of its reuglation of action will provide foundational data, potentially paving the way for its development as an anticancer therapeutic agent.