• Computers and Concrete
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• v.24 no.2
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• pp.103-115
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• 2019

In this study, the strength and stiffness (EI) of wood-concrete composite beams for bridges with T-shaped cross section were evaluated. Two types of connectors were used: connectors bonded with epoxy adhesive and connectors attached to the wood just by pre-drilling (without adhesive). The connectors consisted of common steel bars with a diameter of 12.5 mm. Initially, the strength and stiffness (EI) of the beams were analyzed by bending tests with the load applied at the third point of the beam. Subsequently, the composite beams were evaluated by numerical simulation using ANSYS software with focus on the connection system. To make the composite beams, Eucalyptus citriodora wood and medium strength concrete were used. The slip modulus K and the ultimate strength values of each type of connector were obtained by direct shear tests performed on composite specimens. The results showed that the connector glued with epoxy adhesive resulted in better strength and stiffness (EI) for the composite beams when compared to the connector fixed by pre-drilling. The differences observed were up to 10%. The strength and stiffness (EI) values obtained analytically by $M{\ddot{o}}hler^{\prime}$ model were lower than the values obtained experimentally from the bending tests, and the differences were up to 25%. The numerical simulations allowed, with reasonable approximation, the evaluation of stress distributions in the composite beams tested experimentally.

• Journal of Korean society of Dental Hygiene
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• v.19 no.1
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• pp.65-78
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• 2019

Objectives: This study was conducted to characterize the impact of cognitive function and oral health status on mastication in senior citizens, ${\geq}65$ years of age, using senior centers in the city of Wonju, South Korea. Methods: A cross-sectional study consisting of a simple oral examination and survey questionnaires was performed in 154 individuals. General characteristics, subjective masticatory function, objective masticatory function, cognitive function, and oral health status were collected as variables. Correlation and multiple linear regression analyses were conducted. A p-value of <0.05 was considered to be statistically significant. Results: The subjective masticatory function was scored using the 5-point Likert scale. When subjective masticatory function was analyzed in groups according to cognitive function, the mean subjective masticatory function scores were 4.31, 4.09, and 3.29 in the normal group (cognitive score of ${\geq}16$), suspected dementia group (cognitive score of 1215), and mild dementia group (cognitive score of ${\leq}11$), respectively. Thus, subjective masticatory function decreased along with decreasing cognitive function. When cognitive function, subjective masticatory function, and objective masticatory function were compared with indicators of oral health status (number of functional teeth, oral dryness), subjective masticatory function exhibited a significant positive correlation with objective masticatory function (r=0.635, p<0.01), cognitive function (r=0.292, p<0.01), and total number of functional teeth, including prosthetic appliances (dentures) (r=0.305, p<0.01). According to the regression analysis, age, sex, number of functional teeth, and cognitive function affected subjective masticatory function. Conclusions: The results of this study revealed that age, sex, number of functional teeth, and cognitive function affected subjective masticatory function, whereas oral dryness did not. Therefore, dental professionals must consider subjective masticatory function when providing oral care in senior patients with low cognitive function.

• Advances in nano research
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• v.7 no.2
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• pp.125-134
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• 2019

The Origanum vulgare L.-mediated synthesis of Ag nanoparticles was successfully realized within the present study. Various concentrations of the $AgNO_3$ used as a silver precursor (1, 2.5, 5, 10 and 100 mM) were used. Very rapid formation of Ag nanoparticles was observed, as only minutes were necessary for the completion of the reaction. With the increasing concentration, red shift of the surface plasmon resonance peak was observed in the Vis spectra. According to photon cross-correlation spectroscopy results, the finest grain size distribution was obtained for the 2.5 mM sample. The transmission electron microscopy analysis of this sample has shown bimodal size distribution with larger crystallites with 100 nm size and smaller around 10 nm. The antibacterial activity was also the best for this sample so the positive correlation between good grain size distribution and antibacterial activity was found. The in-depth discussion of antibacterial activity with related works from the materials science point of view is provided, namely emphasizing the role of effective nanoparticles distribution within the plant extract or matrix. The antibacterial activity seems to be governed by both content of Ag nanoparticles and their effective distribution. This work contributes to still expanding environmentally acceptable field of green synthesis of silver nanoparticles.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.138-149
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• 2018

The objective of this cross-cultural study is to assess the effects of relational support on the entrepreneurial capacity and entrepreneurial attitude of university students in Korea and China. Another focal point is to identify any meaningful difference in the role of relational support between these two countries. Three universities participated in this study from both countries. 224 Korean sample and 216 sample from China were used in hierarchical multiple regression analysis. The findings report that relational support has significant positive relationships with entrepreneurial attitude and entrepreneurial capacity in both Korea and China. In addition, entrepreneurial capacity had a positive effect on entrepreneurial attitude. There were no significant differences in the effect of relational support on entrepreneurial activity between Korean and Chinese university students. Finally, theoretical and practical implication were discussed.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.491-500
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• 2020

The present study proposes a time domain model for the Vortex-induced Vibration (VIV) simulation of a catenary riser under the combination of the current and oscillatory flow induced by vessel motion. In this model, the hydrodynamic force of VIV comprises excitation force, hydrodynamic damping and added mass, which are taken as functions of the non-dimensional frequency and amplitude ratio. The non-dimensional frequency is related with the response frequency, natural frequency, lock-in range and the fluid velocity. The relatively oscillatory flow induced by vessel motion is taken into account in the fluid velocity. Considering that the added mass coefficient and the non-dimensional frequency can affect each other, an iterative analysis is conducted at each time step to update the added mass coefficient and the natural frequency. This model is in detail validated against the published test models. The results show that the model can reasonably reflect the effect of the added mass coefficient on the VIV, and can well predict the riser's VIV under stationary and oscillatory flow induced by vessel motion. Based on the model, this study carries out the VIV simulation of a catenary riser with harmonic vessel motion. By analyzing the bending moment near the touchdown point, it is found that under the combination of the ocean current and oscillatory flow the vessel motion may decrease the VIV response, while increase the excited frequencies. In addition, the decreasing rate of the VIV under vessel surge is larger than that under vessel heave at small vessel motion velocity, while the situation becomes opposite at large vessel motion velocity.

• Korean Journal of Metals and Materials
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• v.46 no.2
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• pp.88-96
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• 2008

Thermal evaporated 10 nm-$Ni_{50}Co_{50}$/(70 nm-poly)Si films were deposited to examine the energy saving properties of silicides formed by rapid thermal annealing at temperature ranging from 500 to $1,100^{\circ}C$ for 40 seconds. Thermal evaporated 10 nm-Ni/(70 nm-poly)Si films were also deposited as a reference using the same method for depositing the 10 nm-$Ni_{50}Co_{50}$/(70 nm-poly)Si films. A four-point probe was used to examine the sheet resistance. Transmission electron microscopy (TEM) and X-ray diffraction XRD were used to determine cross sectional microstructure and phase changes, respectively. UV-VIS-NIR and FT-IR (Fourier transform infrared spectroscopy) were used to examine the near-infrared (NIR) and middle-infrared (MIR) absorbance. TEM analysis confirmed that the uniform nickel-cobalt composite silicide layers approximately 21 to 55 nm in thickness had formed on the single and polycrystalline silicon substrates as well as on the 25 to 100 nm thick nickel silicide layers. In particular, nickel-cobalt composite silicides showed a low sheet resistance, even after rapid annealing at $1,100^{\circ}C$. Nickel-cobalt composite silicide and nickel silicide films on the single silicon substrates showed similar absorbance in the near-IR region, while those on the polycrystalline silicon substrates showed excellent absorbance until the 1,750 nm region. Silicides on polycrystalline substrates showed high absorbance in the middle IR region. Nickel-cobalt composite silicides on the poly-Si substrates annealed at $1,000^{\circ}C$ superior IR absorption on both NIR and MIR region. These results suggest that the newly proposed $Ni_{50}Co_{50}$ composite silicides may be suitable for applications of IR absorption coatings.

• Korean Journal of Metals and Materials
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• v.46 no.3
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• pp.159-168
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• 2008

Thermally-evaporated 10 nm-Ni/1 nm-Ru/(30 nm or 70 nm-poly)Si structures were fabricated in order to investigate the thermal stability of Ru-inserted nickel monosilicide. The silicide samples underwent rapid thermal anne aling at $300{\sim}1,100^{\circ}C$ for 40 seconds. Silicides suitable for the salicide process were formed on the top of the single crystal and polycrystalline silicon substrates mimicking actives and gates. The sheet resistance was measured using a four-point probe. High resolution X-ray diffraction and Auger depth profiling were used for phase and chemical composition analysis, respectively. Transmission electron microscope and scanning probe microscope(SPM) were used to determine the cross-sectional structure and surface roughness. The silicide, which formed on single crystal silicon and 30 nm polysilicon substrate, could defer the transformation of $Ni_2Si $i and $NiSi_2 $, and was stable at temperatures up to $1,100^{\circ}C$ and $1,100^{\circ}C$, respectively. Regarding microstructure, the nano-size NiSi preferred phase was observed on single crystalline Si substrate, and agglomerate phase was shown on 30 nm-thick polycrystalline Si substrate, respectively. The silicide, formed on 70 nm polysilicon substrate, showed high resistance at temperatures >$700^{\circ}C$ caused by mixed microstructure. Through SPM analysis, we confirmed that the surface roughness increased abruptly on single crystal Si substrate while not changed on polycrystalline substrate. The Ru-inserted nickel monosilicide could maintain a low resistance in wide temperature range and is considered suitable for the nano-thick silicide process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.424-430
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• 2021

Determining the cause of a traffic signal violation is difficult if the drivers' claims are contradictory. In this study, the process of identifying signal violations using a simulation was presented based on cases. First, statements from the driver or witness whose cause of the signal violation is unclear were excluded. Second, the final position, final location, damaged area, steering status, braking status, and road surface traces of the vehicle were collected. The impact point was investigated from the stop line. Third, simulation data were modified and entered until the collision situation of the accident vehicle and the final stop position were met. Fourth, if the simulation results were consistent with the crash situation, the facts were verified by cross-validation to conform to the driver's statement. The results of the simulation showed that the Lexus entered the left turn signal in the intersection at approximately 55 km/h. In comparison, the Sonata driver saw the vehicle straight ahead at the intersection, entered the 72 km/h intersection, and collided with the Lexus. Therefore, the Sonata was identified as a signal violation, and the claims of the Sonata driver, witnesses, and police were contradictory.

• Journal of Oriental Neuropsychiatry
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• v.32 no.1
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• pp.55-66
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• 2021

Objectives: The aim of this scoping review was to analyze research trends about mental health of nurses working in Korean medicine (KM) hospitals in Republic of Korea. Methods: Searches were conducted using four electronic databases including Oriental Medicine Advanced Searching Integrated System, Korean Studies Information Service System, Research Information Sharing Service, Korea Citation Index to collect relevant studies. The search date was March 4, 2021. All studies published up to the search date were considered. Observational studies reporting mental health outcomes of nurses working at KM Hospital were included. Results: A total of 11 cross-sectional observation studies were included. Four of them compared mental health of nurses working on KM and Western medicine (WM). Commonly reported outcomes related to mental health were job satisfaction, role conflict, and work stress. As a result of meta-analysis based on a 5-point Likert scale, the following factors were related to mental health of KM nurses: job satisfaction (2.844±0.067 points), role conflict (3.678±0.058 points), work stress (3.142±0.021 points), turnover intention (3.483±0.028 points), and burnout (3.180±0.033). Compared to WM nurses, KM nurses had significantly less work stress (p=0.000), role conflict (p=0.039), and job satisfaction (p=0.000). Conclusions: Mental health problems of nurses are known to be very common. Although improving them is an important social task, studies on mental health of KM nurses remain insufficient. Based on findings of this study, more cooperation between nurses and KM doctors should be made to improve the mental health of KM nurses, especially their job satisfaction in the future. The Korean Society of Oriental Neuropsychiatry needs to pay more attention to this topic.

• Korean Journal of Plant Resources
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• v.34 no.1
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• pp.73-78
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• 2021

We report a technique for obtaining seeds of 'Cheongnarae' (a variety of Hosta minor cultivated at the Korea National Arboretum in 2019) by artificial crossing of H. minor, collected from Jeju Island, as the female parent and H. minor 'Krossa Regal', cultivated outside Korea, as the male parent. Among the individuals obtained after sowing, those that showed different morphological characteristics, such as leaf shape and color, were selected. Among these individuals, those with thick leaves and light-colored flowers were further selected. Vegetative propagation and cultivation steps were repeated for evaluation of the characteristics. 'Cheongnarae' has relatively thicker leaves and a darker color (RHS 137A) than the control variety 'Black Hills' and has wings at the point where the petiole meets the leaf blade. The shape of the leaf blade edge is clearly sinuous, and the flower color is close to white (White N155B). 'Cheongnarae' cultivated in this way can be used for pot plant or gardening.