• Korean Journal of Medicinal Crop Science
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• v.26 no.4
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• pp.308-316
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• 2018

Background: The Rosa multiflora, a well-known plant belonging to Rosacea, is widely used in orthodox medicine in worldwide. However, its biological activity and cosmetic preservative efficacy have not yet been studied. Thus, this species is yet to be defined as a functional cosmetic material. Accordingly, an investigation of the above mentioned atrributes was performed on a 50% ethanol extract of Rosa multiflora. Methods and Results: The antioxidant activity was assessed through free radical scavenging assays with 2,2-diphenyl-1-picrylhydrazyl (DPPH). Additionally, the contents of total phenols and flavonoids were analyzed. The phenolic compounds were detected using HPLC. The antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans was assessed using the disc diffusion assay. The preservative effect (challenge test) on a formulation of soothing gel was performed for 28days. The DPPH radical scavenging ability, denoted by the $SC_{50}$ (half maximal inhibitory concentration for DPPH radical scavenging) value was found to be $131.63{\mu}g/m{\ell}$. The content of total polyphenol and flavonoid content were 202 mg/g and 86.77 mg/g, respectively. In additon, astragalin and gallic acid were identified in the extract. The antimicrobial activity of the extract against S. aureus and E. coli was observed to be 5 - 0.5%, and no significant activity was noted against C. albicans. The ethanol extracts (5% and 10%) met the preservation standards of the Cosmetics, Toiletry, and Fragrance Association (CTFA). Conclusions: Thus the ethanol extract of R. multiflora can be used in cosmetics as a natural preservative and antioxidant.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.6 s.171
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• pp.213-221
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• 2005

An insole type local shear force measurement system was developed and local shear stresses in the foot were measured during level walking. The shear force transducer based on the magneto-resistive principle, was a rigid 3-layer circular disc. Sensor calibrations with a specially designed calibration device showed that it provided relatively linear sensor outputs. Shear transducers were mounted on the locations of four metatarsal heads and heel in the insole. Sensor outputs were amplified, decorded in the bluetooth transmission part and then transferred to PC. In order to evaluate the developed system, both shear and plantar pressure measurements, synchronized with the three-dimensional motion analysis system, were performed on twelve young healthy male subjects, walking at their comfortable speeds. The maximum peak pressure during gait was 5.00kPa/B.W at the heel. The time when large local shear stresses were acted correlated well with the time of fast COP movements. The anteroposterior shear was dominant near the COP trajectory, but the mediolateral shear was noted away from the COP trajectory. The vector sum of shear stresses revealed a strong correlation with COP movement velocity. The present study will be helpful to select the material and to design of foot orthoses and orthopedic shoes for diabetic neuropathy or Hansen disease.

• Journal of Korean Neurosurgical Society
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• v.60 no.1
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• pp.114-117
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• 2017

A 42-year-old man was admitted to our hospital with complaints of low back pain and intermittent right thigh pain. Twelve weeks before admission, the patient received intradiscal electrothermal therapy (IDET) at a local hospital. The patient still reported low back pain after the procedure that was managed with narcotic analgesics. Follow-up magnetic resonance imaging (MRI) was performed, and his referring physician thought the likely diagnosis was spondylodiscitis at the L4-5 spinal segment with a small epidural abscess. At admission to our department, the patient reported aggravated low back pain. Blood test results, including the erythrocyte sedimentation rate and C-reactive protein levels, were slightly elevated. Biopsy samples of the L4, L5 vertebral bodies and disk were obtained. The material underwent aerobic, anaerobic, fungal, mycobacterial cultures and histologic examination. Results of all cultures were negative. Histologically, necrosis of the bone was evident from the number of empty osteocyte lacunae. In addition, there was no evidence of infection based on biopsy results. No antibiotic treatment was administered on discharge. Repeat computed tomography and MRI performed 12 months after IDET showed a bony defect in the L4 and L5 vertebral bodies, and a decrease in the size of the L4-5 intervertebral disc lesion. We report a case of lumbar vertebral osteonecrosis induced by IDET and discuss etiology and radiologic features.

• Journal of Radiation Industry
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• v.7 no.1
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• pp.87-91
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• 2013

Taraxacum platycarpum (TP) has been used for years without restriction on usual dose for its non-toxic nature and nonexistence of the side effects. To develop antimicrobial hydrogel, poly (vinylalcohol) (PVA) hydrogels containing the aqueous extracted TP as an antimicrobial agent were prepared by using gamma-rays irradiation. The antimicrobial activities of the TP hydrogels were tested against Staphylococcus aureus and Staphylococcus epidermidis by disc diffusion method. The inhibition zones (IZ) of the TP extracts and TP hydrogels against S. aureus were 16 mm and 20 mm and against S. epidermidis was 10 mm and 13 mm, respectively. In conclusion, the TP hydrogel that has an excellent antimicrobial activity was proved to be a valuable material for functional skin care.

• Korean Journal of Materials Research
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• v.29 no.7
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• pp.443-450
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• 2019

Thermal management is a critical issue for the development of high-performance electronic devices. In this paper, thermal conductivity values of mild steel and stainless steel(STS) are measured by light flash analysis(LFA) and dynamic thermal interface material(DynTIM) Tester. The shapes of samples for thermal property measurement are disc type with a diameter of 12.6 mm. For samples with different thickness, the thermal diffusivity and thermal conductivity are measured by LFA. For identical samples, the thermal resistance($R_{th}$) and thermal conductivity are measured using a DynTIM Tester. The thermal conductivity of samples with different thicknesses, measured by LFA, show similar values in a range of 5 %. However, the thermal conductivity of samples measured by DynTIM Tester show widely scattered values according to the application of thermal grease. When we use the thermal grease to remove air gaps, the thermal conductivity of samples measured by DynTIM Tester is larger than that measured by LFA. But, when we did not use thermal grease, the thermal conductivity of samples measured by DynTIM Tester is smaller than that measured by LFA. For the DynTIM Tester results, we also find that the slope of the graph of thermal resistance vs. thickness is affected by the usage of thermal grease. From this, we are able to conclude that the wide scattering of thermal conductivity for samples measured with the DynTIM Tester is caused by the change of slope in the graph of thermal resistance-thickness.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.2
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• pp.45-49
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• 2019

Herein we developed the hot extrusion technology to prepare n-type Bi-Te-Se-based thermoelectric materials with high reliability. Starting ingot was fabricated via melt-solidification process, then pulverized it into powders (${\sim}30{\mu}m$) by using high energy ball milling. By optimization of mold design and temperature-pressure conditions for hot extrusion, dense extrudate of 1.8 mm in diameter with high 00l orientation could be obtained from disc-shape compacted powders (20 mm in diameter). High power factor ${\sim}4.1mW/mK^2$ and enhanced mechanical strength ~50 MPa were simultaneously observed at 300 K.

• The Journal of Advanced Prosthodontics
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• v.14 no.6
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• pp.360-368
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• 2022

PURPOSE. This study assessed the physical and mechanical properties of interim crown materials fabricated using various digital techniques after accelerated aging. MATERIALS AND METHODS. Three groups of interim dental restorative materials (N = 20) were tested. The first group (CO) was fabricated using a conventional manual method. The second group (ML) was prepared from prefabricated resin blocks for the milling method and cut into specimen sizes using a cutting disc. The third group (3D) was additively manufactured using a digital light-processing (DLP) 3D printer. Aging acceleration treatments using toothbrushing and thermocycling simulators were applied to half of the specimens corresponding to three years of usage in the oral environment (N = 10). Surface roughness (Ra), Vickers microhardness, 3-point bending, sorption, and solubility tests were performed. A 2-way analysis of variance (ANOVA) and Fisher's multiple comparison test were used to compare the results among the groups. RESULTS. The mean surface roughness (Ra) of the resin after accelerated aging was significantly higher in the CO and ML groups than that before aging, but not in the 3D group. All groups showed reduced hardness after accelerated aging. The flexural strength values were highest in the 3D group, followed by the ML and CO groups after accelerated aging. Accelerated aging significantly reduced water sorption in the ML group. CONCLUSION. According to the tested material and 3D printer type, both 3D-printed and milled interim restoration resins showed higher flexural strength and modulus, and lower surface roughness than those prepared by the conventional method after accelerated aging.

• Structural Engineering and Mechanics
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• v.85 no.3
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• pp.337-351
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• 2023

In this paper, the shear behavior of soft filling in rectangular-hollow concrete specimens was simulated using the 2D particle flow code (PFC2D). The laboratory-measured properties were used to calibrate some PFC2D micro-properties for modeling the behavior of geo-materials. The dimensions of prepared and modeled samples were 100 mm×100 mm. Some disc type narrow bands were removed from the central part of the model and different lengths of bridge areas (i.e., the distance between internal tips of two joints) with lengths of 30 mm, 50 mm, and 70 mm were produced. Then, the middle of the rectangular hollow was filled with cement material. Three filling sizes with dimensions of 5 mm×5 mm, 10 mm×5 mm, and 15 mm×5 mm were provided for different modeled samples. The parallel bond model was used to calibrate and re-produce these modeled specimens. Therefore, totally, 9 different types of samples were designed for the shear tests in PFC2D. The shear load was gradually applied to the model under a constant loading condition of 3 MPa (σc/3). The loading was continued till shear failure occur in the modeled concrete specimens. It has been shown that both tensile and shear cracks may occur in the fillings. The shear cracks mainly initiated from the crack (joint) tips and coalesced with another one. The shear displacements and shear strengths were both increased as the filling dimensions increased (for the case of a bridge area with a particular fixed length).

• Geomechanics and Engineering
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• v.35 no.5
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• pp.487-497
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• 2023

Penetration rate (PR) and penetration depth (Pe) are crucial parameters for estimating the cost and time required in tunnel construction using tunnel boring machines (TBMs). This study focuses on investigating the impact of rock strength on PR and Pe through full-scale experiments. By conducting controlled tests on rock-like specimens, the study aims to understand the contributions of various ground parameters and machine-operating conditions to TBM excavation performance. An earth pressure balanced (EPB) TBM with a sectional diameter of 3.54 m was utilized in the experiments. The TBM excavated rocklike specimens with varying uniaxial compressive strength (UCS), while the thrust and cutterhead rotational speed were controlled. The results highlight the significance of the interplay between thrust, cutterhead speed, and rock strength (UCS) in determining Pe. In high UCS conditions exceeding 70 MPa, thrust plays a vital role in enhancing Pe as hard rock requires a greater thrust force for excavation. Conversely, in medium-to-low UCS conditions less than 50 MPa, thrust has a weak relationship with Pe, and Pe becomes directly proportional to the cutterhead rotational speed. Furthermore, a strong correlation was observed between Pe and cutterhead torque with a determination coefficient of 0.84. Based on these findings, a predictive model for Pe is proposed, incorporating thrust, TBM diameter, number of disc cutters, and UCS. This model offers a practical tool for estimating Pe in different excavation scenarios. The study presents unprecedented full-scale TBM excavation results, with well-controlled experiments, shedding light on the interplay between rock strength, TBM operational variables, and excavation performance. These insights are valuable for optimizing TBM excavation in grounds with varying strengths and operational conditions.

• Journal of the Korean Applied Science and Technology
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• v.33 no.3
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• pp.606-613
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• 2016

The purpose of this study is to analyze the possibility of a residual product of coffee (RC). RC oil extracted with n-hexane at $60({\pm}10)^{\circ}C$ for 24 hours. In this study, the cytotoxicity of RC oil was observed against B16F10 melanoma cells and RAW 264.7 macrophage cells by water solubletetrazolium salt-1 assay, and The RC oil measured by methods of DPPH radical scavenging and antimicrobial activities in Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Candida albicans. As a result, the RC oil treatment-related cytotoxic effects appeared on B16F10 melanoma cells from 0.125 to $2{\mu}{\ell}/m{\ell}$ and RAW 264.7 macrophage cells from 0.125 to $0.5{\mu}{\ell}/m{\ell}$ concentrations in this study. RC oil is radical scavenging activity concentrations on dependent. The antimicrobial activity of RC oil ($150{\mu}l/{\ell}$) was determined by clear zone method. Straphylococcus epidermidis, Straphylococcus aureus, Escherichia coli, Candida albicans showed clear zone by each $11.3{\pm}0.4$, $12.{\pm}0.7$, $12.0{\pm}0.0$, $0.0{\pm}0.0mm$. It is suggested that RC oil have effects on the cytotoxicity, antioxidant and antimicrobial that could be applicable to cosmetics as a new material.