• Tunnel and Underground Space
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• v.34 no.3
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• pp.208-217
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• 2024

There is so much research effort for developing and implementing deep learning-based surveillance systems to manage health and safety issues in construction sites. Especially, the development of deep learning-based object detection in various environmental changes has been progressing because those affect decreasing searching performance of the model. Among the various environmental variables, the accuracy of the object detection model is significantly dropped under low illuminance, and consistent object detection accuracy cannot be secured even the model is trained using low-light images. Accordingly, there is a need of low-light enhancement to keep the performance under low illuminance. Therefore, this paper conducts a comparative study of various deep learning-based low-light image enhancement models (GLADNet, KinD, LLFlow, Zero-DCE) using the acquired construction site image data. The low-light enhanced image was visually verified, and it was quantitatively analyzed by adopting image quality evaluation metrics such as PSNR, SSIM, Delta-E. As a result of the experiment, the low-light image enhancement performance of GLADNet showed excellent results in quantitative and qualitative evaluation, and it was analyzed to be suitable as a low-light image enhancement model. If the low-light image enhancement technique is applied as an image preprocessing to the deep learning-based object detection model in the future, it is expected to secure consistent object detection performance in a low-light environment.

• Journal of the Korea Society of Computer and Information
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• v.25 no.9
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• pp.183-191
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• 2020

Many learners are encountering e-Learning contents with smart devices and contents provides are carefully observing learners' reuse intention and behavior. Therefore, this study investigated the effect of e-Learning content platform characteristics on reuse intention for 200 users with smartphone-based e-Learning experience. The results show that the characteristics affecting reuse intention are content quality, interactivity, and ubiquity. Moreover, for men, only interactivity affects reuse intention, and for women, ubiquity and content quality affect reuse intention. When using smartphone-based e-Learning for less than an hour a day, only content quality affects reuse intention. On the contrary, ubiquity, convenience, and interactivity influence reuse intention when learning for more than one hour. Our results suggest meaningful implications that how e-Learning companies change their smartphone-based platform business strategy and how they utilize its key factors.

• Journal of Korea Port Economic Association
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• v.31 no.4
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• pp.169-187
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• 2015

Ports as central factors of the logistics industry and principal bases in industrial activities play a significant role in the development of the social economy. This paper takes the throughput data from 2000 to 2014 of 10 container ports located in China as the research object with the Gini coefficient and employs the shift-share analysis. It aims to analyze the changes in port concentration and movement of container throughputs and propose a stage of development port system in China. The results are as follows. First, the system of container ports clearly moves northward. According to the above shift-share analysis, the throughput moves from the Pearl River Delta to the other two regions. This indicates that the center of Chinese container port system moves northward. Second, container port diversification development takes a representative position in the change of container throughput space structure. According to the calculation results of Gini coefficient, diversified development gradually predominates the change of container throughput space structure.

• Korean Journal of Ecology and Environment
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• v.46 no.2
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• pp.205-214
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• 2013

In Yeongsan River estuary, located in the southern West Coast, a dike was constructed in December 1981. After the construction of a dike, discharge mechanism of fresh water has been changed, the water quality and chlorophyll-a are expected to be influenced by fresh water discharge. We investigated temporal and spatial variations and long-term trend of phytoplankton biomass (chlorophyll-a) and environmental factors. The concentrations of nutrient and chlorophyll-a were generally high in summer and the concentrations were increased toward downstream. Surface/bottom salinity difference was negatively correlated with salinity in surface water but positively with nutrient and chlorophyll-a. TN, TP and DIN concentrations were generally increased over 10 years. This study can provide information for better management of water quality for Youngsan River estuary.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.7189-7195
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• 2015

The method of moments (MoM) is implemented to simulate scattering from a PEC (perfectly electric conductor) cylinder in the TE(transversw electric) EFIE (Electric Field Integral Equation) approach. The procedure expresses the singularity integral and the hypersingularity integral in terms of an analytic function and employs a singularity isolation process coupled with numerical technique along the discretized segment to evaluate the self terms. It is known that, in the MoM technique, the choice of base functions and test functions is very important for the accuracy and convergence of the numerical analysis. Thus, in this paper, three conditions, obtained from the combination of basis functions and test functions, are adopted to get the induced currents on the PEC surface. These currents are compared to the analytical one in the relative rms current error to get the condition that shows fast convergence rate. The fast order of convergence of the current error, 2.528, is obtained under the combination of pulse basis function/delta test function.

• Journal of the Korea Convergence Society
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• v.8 no.7
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• pp.39-46
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• 2017

Dongguan City of Guangdong province, one of the core areas of the Pearl River Delta, has also pursued economic development through the geographical advantage close to Hong Kong. In the early 1980s, small and medium-sized multinational corporations related to home appliances industry from Hong Kong invested to the Dongguan area and set up a production factory. In the mid-1990s, as Taiwanese PC manufacturers invested, local industrial clusters have developed in Dongguan with core of the IT, PC components and electronic industries. The case of the IT industrial cluster in Dongguan is a typical example of the development of Chinese manufacturing industry after the reform of China. This paper focused on the coupling strategy case of Dongguan City industrial cluster in Guangdong province, and theoretically compared the endogenous growth factor analysis(NMID) of regional industrial development with the regional differentiation of industry based on external linkage with global production network(GPN).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.2
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• pp.15-20
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• 1998

The furfural, generated by decomposition of insulating paper, the amount of metal in insulating oil, and tano(electrical properties of insulating oil)have been studied for the insulating oil in pole transformer with accelarated thermal aging test. It has been found that tan $\delta$ is affected by adding components of the transformer. The examination of amount of metal, which exhibits catalytic behavior to oxidation of insulating oil, suggested that the amounts of copper increase with degradation time. A comparison between tano and copper amount suggested that the amounts of copper for attention are above 0.2[pp]). Finally, the examination of amount of furfural revealed that the amounts of furfural increase with degradation time. As a consequence, these results could be used for diagnosis of pole transformer.former.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.4
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• pp.335-341
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• 2009

In this paper, review of developed MLS-based finite elements and a proposal for their applications are described. The shape functions and their derivatives of MLS-based finite elements are constructed using Moving-Least Square approximation. In MLS-based finite element, using the adequate influence domain of weight function used in MLS approximation, kronecker delta condition could be satisfied at the element boundary. Moreover, because of the characteristics of MLS approximation, we could easily add extra nodes at an arbitrary position in MLS-based finite elements. For these reasons, until now, several variable-node elements(2D variable element for linear case and quadratic case and 3D variable-node elements) and finite crack elements are developed using MLS-based finite elements concept. MLS-based finite elements could be extended to 2D variable-node triangle element, 2D finite crack triangle element, variable-node shell element, finite crack shell element, and 3D polyhedron element. In this paper, we showed the feasibility of 3D polyhedron element at the case of femur meshing.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.273-280
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• 2023

The purpose of this study is to investigate the effect of functional bedding of ceravida recovery materials on muscle fatigue, brain waves, and heat in the cervical spine before and after sleep. The subjects of the study were 12 women in their 50s or older in D Metropolitan City who complained of insomnia due to sleep disorders and cervical pain. The results of this study first showed that functional bedding lowered muscle tension. Second, the skin temperature of cervical spine increased statistically significantly for both functional and general bedding. Third, there was a statistically significant difference in EEG(alpha, beta, theta, delta) of functional bedding. Through these results, it is considered that functional bedding of ceravida recovery material has sufficient effect on sleep recovery technology.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.1
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• pp.66-72
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• 2017

Potato greening determines the shelf life and affects the marketability of this tuber. Various stresses during handling and storage interact to affect the tuber's physiological status and can affect the rate of greening. This study investigated the effects of storage temperature on tuber greening and shelf life in unwashed and washed potatoes of the cultivar Superior. Physiological and biochemical changes were examined during 15 days at room temperature ($23{\pm}2^{\circ}C$) under cool-white fluorescent light after storage for 1 month at different temperatures ($4^{\circ}C$, $20^{\circ}C$). Hunter a values were negative (-) for washed potatoes after 3 days (-0.8) and 15 days (-2.5) at room temperature following 1 month of storage at $4^{\circ}C$ while positive (+) values were observed for unwashed potatoes after 15 days at room temperature. The Hunter ${\Delta}E$ values of washed potatoes previously stored at $4^{\circ}C$ for 1 month increased after 3 days at room temperature compared with those of unwashed potatoes. The total chlorophyll content of washed potatoes was higher than that of unwashed potatoes. The highest correlation was observed between the Hunter ${\Delta}E$ value and Hunter a value (-0.93506), while a positive correlation coefficient (0.89806) was observed between greening criteria and Hunter ${\Delta}E$ value by using colorimetry. We conclude, therefore, that there is a biosynthetic link between temperature-induced chlorophyll accumulation and tuber greening in storage.