• Journal of Digital Convergence
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• v.11 no.11
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• pp.191-196
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• 2013

The proportion of small and medium sized enterprises based on the number of corporations in China is 99%, the number of employees is 80%, and the proportion of GDP is 60%. These facts show that small and medium sized enterprises have an very significant effect on the economic growth of China. However, most of the researches conducted so far have studied large corporations, thus, there are relatively insufficient researches on the determinant of the capital structure of small and medium sized enterprises. Therefore, the purpose of this paper is to confirm the factors that determine the capital structure of small and medium sized enterprises in China. To achieve this purpose, we performed multiple regression method to 45 small and medium sized manufacturing enterprises listed on the Shenzhen Stock Exchange of China. Results of this study are as follows. First, the growth appeared to have a significant positive effect to the debt ratio in 1% significance level. Second, the profitability appeared to have a significant negative effect to debt ratio in 1% significance level. Third, the firm size appeared to have no effect on the debt ratio. Fourth, the secured value and tax shield effect by non-debt appeared to have a weak positive effect on the debt ratio, however these variables showed statistical insignificant.

• Journal of Digital Convergence
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• v.18 no.10
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• pp.233-238
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• 2020

In the cloud environment, IoT devices using sensors and wearable devices are being applied in various environments, and technologies that accurately determine the information generated by IoT devices are being actively studied. However, due to limitations in the IoT environment such as power and security, information generated by IoT devices is very weak, so financial damage and human casualties are increasing. To accurately collect and analyze IoT information, this paper proposes a topographic information-based key management technique that considers IoT information errors. The proposed technique allows IoT layout errors and groups topographic information into groups of dogs in order to secure connectivity of IoT devices in the event of arbitrary deployment of IoT devices in the cloud environment. In particular, each grouped terrain information is assigned random selected keys from the entire key pool, and the key of the terrain information contained in the IoT information and the probability-high key values are secured with the connectivity of the IoT device. In particular, the proposed technique can reduce information errors about IoT devices because the key of IoT terrain information is extracted by seed using probabilistic deep learning.

• Journal of Digital Convergence
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• v.18 no.4
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• pp.23-35
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• 2020

This study is based on prior research cases on workplace learning, which had a significant impact on corporate research. To improve problem solving and supplementing ability by keeping the opportunity to participate in workplace learning for the weak small business owners and to strengthen opportunities for practical growth, and to propose education, policy and institutional windowing. Therefore, to establish the relationship between small business owners' workplace learning, job satisfaction, and service quality, a research hypothesis was set in the background of prior research and empirical analysis was conducted. The results from 203 questionnaires were analyzed with SPSS 18.0 program. As an analytical result, first, workplace learning had a partial positive (+) impact on job satisfaction. Second, workplace learning had a partial positive (+) impact on service quality. Third, in the relationship between workplace learning and service quality, job satisfaction played a full mediating role. From this, it was found that formal learning, the subfactor of workplace learning did not have an impact on job satisfaction and service quality, as subtitle of educational environment including offsite training and self education, systematization, and structuralization depending on the poor environment of small enterprises. Therefore, it was found that small enterprises' poor environment was revealed from the managerial, economic and social perspectives and to compensate such defect, educational, policy, and institutional strategies to strengthen the opportunity for growth and development of small enterprises can be suggested to the governmental agencies or local governments. Despite the significant results of this study, there may be limitations. Therefore, further studies should be conducted in various fields with various samples in the future, and further studies should be conducted in academic and practical relationships that can improve the service quality and management performance.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.4
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• pp.263-270
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• 2017

The shipbuilding industry uses large stationary tanks to store low-pressure air, which is used to open and close large shut-off valves. However, when supplying air from the tank to a distant valve, there are problems related to the need for supplementary pipes and the pressure drop during transportation. In this study, a portable welded vessel for storing high-pressure nitrogen (11 kg, 10 L, and 50 bar) was designed to prevent air leakage and improve the convenience of workers. This pressure vessel was elliptical to reduce the number of welded parts, which are structurally weak. The thickness and ratio of the major and minor axes of the pressure vessel were calculated to verify its structure stability at the working pressure (50 bar), and that the proposed weight and capacity were satisfactory. The residual stress caused by the welding process was calculated by performing a transient thermal-structural coupled field analysis using the ANSYS parametric design language (APDL), and the fatigue life of the vessel was verified based on the Goodman criterion.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.319-330
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• 2016

Recently, 3D printing technology has been applied to make a concept model and working mockup of an industrial application. On the other hand, this technology has limited applications in industrial products due to the materials and reliability of the 3D printed product. In this study, the components of a full cord switch module are proposed as a case of a 3D printed component that can be used as a substitute for a short period. These are hub-driven and lever lockup components that have the structural characteristics of breaking down frequently in the emergency operating status. To ensure the structural strength for a substitute period, research of structure optimization was performed because 3D printing technology has a limitation in the materials used. After optimizing the structure variables of the hub-driven component, reasonable results can be drawn in that the safety factors of the left and right switching mode are 1.243 (${\Delta}153.67%$) and 3.156 (${\Delta}404.96%$). The lever lockup component has a structural weak point that can break down easily on the lockup-part because of a cantilever shape and bending moment. The rib structure was applied to decrease the deflection. In addition, optimization of the structural variables was performed, showing a safety factor of 7.52(${\Delta}26%$).

• Geophysics and Geophysical Exploration
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• v.1 no.1
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• pp.49-56
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• 1998

Seismic tomography has been widely used as high resolution subsurface imaging techniques in engineering applications. Although most of the techniques have been using travel time inversion, waveform method is being driven forward owing to the progress of computational environments. Although full-waveform inversion method has been known as the best method in terms of model resolving power without high-frequency restriction and weak scattering approximation, it has practical disadvantage that it is apt to get stuck in local minimum if the initial guess is far from the actual model and it consumes so much time to calculate. In this study, 2-D full-waveform inversion algorithm in acoustic medium is developed, which uses result of traveltime tomography as initial model. From the application on synthetic data, it is proved that this approach can efficiently reduce the problem of conventional approaches: our algorithm shows much faster convergence rate and improvement of model resolution. Result of application on physical modeling data also shows much improvement. It is expected that this algorithm can be applicable to real data.

• International journal of advanced smart convergence
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• v.10 no.4
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• pp.241-255
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• 2021

The human auricle is the first part to receive sound from the outside. In this part, the frequency range of human recognizable form is divided and organized. In this study, we propose modeling by applying a single sound source to the surface of the human auricle. This means that when the sound pressure of a low frequency (low frequency) sound enters the pinna, the impedance felt at the tip of a part of the non-linear surface of the pinna is mainly due to the tensile force at the end of the part of the non-linear surface of the pinna. By expressing the situation of moving at a very small speed, the characteristic impedance of the pinna was confirmed to be negative infinity, and it was also confirmed that the speed at the tip of a part of the non-linear surface of the pinna was 0 in the anti-resonance state. It was found that the wave propagation phenomenon that determines the characteristics of the filter is determined by how large the wavelength, kL, is compared to the length of the tip of a part of the non-straight surface of the pinna. Humans first receive sounds from outside through their ears. The auricle is non-linear and has a curved shape, and it is known that it analyzes frequencies while receiving external sounds. The human ear has an audible frequency range of 20Hz - 20,000Hz. Through the study, we applied the characteristics of the notch filter to hypothesize that the human audible frequency range is separated from the auricle, and applied filter theory to analyze it, and as a result, meaningful results were obtained. The curved part and the inner part of the auricle function as a trumpet, collecting sounds, and at the same time amplifying the weak sound of a specific band. The point was found and the shape of the envelope detected in the auricle was found. Selectivity for selecting sounds coming from the outside is the formula of the pinna that implements the function of Q. The function of distinguishing human-recognizable sound from the pinna from low to high through frequency analysis is performed in the pinna, and the 2-3kHz area, where human hearing threshold is the most sensitive, is also the acoustic impedance of the most recessed area of the pinna. It can be seen that starting from.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.2
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• pp.73-77
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• 2021

Ga-doped ZnO thin films by RF magnetron sputtering process were synthesized according to the deposition conditions of O2 and Ar atmosphere gases, and rapid heat treatment (RTA) was performed at 600℃ in an N2 atmosphere. The thickness of the deposited ZnO : Ga thin film was measured, the crystal phase was investigated by XRD pattern analysis, and the microstructure of the thin film was observed by FE-SEM and AFM images. The intensity of the (002) plane of the X-ray diffraction pattern showed a significant difference depending on the deposition conditions of the thin films formed by O2 and Ar atmosphere gas types. In the case of a single thin f ilm doped with Ga under O2 conditions, a strong diffraction peak was observed. Under O2 and Ar conditions, in the case of a multilayer thin film with Ga doping, only a peak on the (002) plane with a somewhat weak intensity was shown. In the FE-SEM image, it was observed that the grain size of the surface of the thin film slightly increased as the thickness increased. In the case of a multilayer thin film with Ga doping under O2 and Ar atmosphere conditions, the specific resistance was 6.4 × 10-4 Ω·cm. In the case of a single thin film with Ga doping under O2 atmosphere conditions, the resistance of the thin film decreased. The resistance decreased as the thickness of the Ga-doped ZnO thin film increased to 2 ㎛, showing relatively a low specific resistance of 1.0 × 10-3 Ω·cm.

• New Physics: Sae Mulli
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• v.68 no.12
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• pp.1308-1314
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• 2018

$Er^{3+}$ and $Yb^{3+}$ co-doped $Y_3Ga_5O_{12}$ polycrystalline powders were prepared by using a solid-state reaction method, and their crystallinities were measured using X-ray diffraction. According to the results of X-ray diffraction, the powders showed a polycrystalline tetragonal structure. The photoluminescence and the upconversion luminescence properties of the $(Y_{0.85-x}Yb_{0.15})_3Ga_5O_{12}:Er^{3+}_x$ (x = 0.03, 0.06, 0.09, 0.12 and 0.15) phosphors were investigated in detail. Green and red upconversion emissions were observed for the phosphors excited by 980 nm radiation from a semiconductor laser. The powders exhibited strong green and weak red upconversion emission peaks at 553 and 660 nm, respectively. Also, their upconversion processes were explained using an energy-diagram analysis and the strongest upconversion intensity was emitted by the powder with a 0.12 mol $Er^{3+}$ ion concentration.

• FLOWER RESEARCH JOURNAL
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• v.26 no.4
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• pp.195-201
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• 2018

The plant morphological and chromosome characteristics of 'Bonanza', 'Coral Candy' and 'Purple Crystal', a formolongi-Asiatic (FA) interspecific hybrid species bred at the National Institute of Horticultural Science, Rural Development Administration (RDA), were investigated in this study. The flowering time of these species were found to have some variation. 'Bonanza' flowers in the middle to late June (medium-late maturing cultivar), 'Coral Candy' in the mid of June (medium maturing cultivar), and 'Purple Crystal' was observed to be in early June (early maturing cultivar). The flowering direction of all three cultivars are upward facing flowers and having a weak fragrance. The height of the plants was recorded in the range between 101.0 cm ('Purple Crystal') to 142.3 cm ('Bonanza'), thus they are able to develop cut flowers with excellent stem elongation. Flower diameters of 'Bonanza' (17.1 cm) and 'Coral Candy' (16.9 cm) were classified to be large sized flowers. On the other hand, 'Purple Crystal' had a narrow flower diameter (12.3 cm) with an outer petal width of more than 4.0 cm. Leaf length was observed for 'Bonanza' (15.7 cm), 'Coral Candy' (19.7 cm), and 'Purple Crystal' (11.1 cm). Chromosome analysis was done using FISH technique. Results revealed that all three cultivars were observed as triploids (2n=3x=36). FISH analysis also showed 5S/45S rDNA of 'Bonanza', 'Coral Candy' and 'Purple Crystal' as 4/11 loci, 4/12 loci, and 4/11 loci, respectively. The results of the FISH analysis are useful as markers to distinguish cultivars, since the patterns of rDNA observed on the remaining chromosomes are significantly different except FISH patterns of chromosome #3.