• ETRI Journal
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• v.46 no.2
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• pp.205-217
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• 2024

We propose a bandwidth prediction approach based on deep learning. The approach is intended to accurately predict the bandwidth of various types of mobile networks. We first use a machine learning technique, namely, the gradient boosting algorithm, to recognize the connected mobile network. Second, we apply a handover detection algorithm based on network recognition to account for vertical handover that causes the bandwidth variance. Third, as the communication performance offered by 3G, 4G, and 5G networks varies, we suggest a bidirectional long short-term memory model with time distribution for bandwidth prediction per network. To increase the prediction accuracy, pretraining and fine-tuning are applied for each type of network. We use a dataset collected at University College Cork for network recognition, handover detection, and bandwidth prediction. The performance evaluation indicates that the handover detection algorithm achieves 88.5% accuracy, and the bandwidth prediction model achieves a high accuracy, with a root-mean-square error of only 2.12%.

• Communications for Statistical Applications and Methods
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• v.31 no.1
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• pp.37-53
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• 2024

In this study, flood records from 79 sites across Thailand were analyzed to estimate flood indices using the regional frequency analysis based on the L-moments method. Observation sites were grouped into homogeneous regions using k-means and Ward's clustering techniques. Among various distributions evaluated, the generalized extreme value distribution emerged as the most appropriate for certain regions. Regional growth curves were subsequently established for each delineated region. Furthermore, 20- and 100-year return values were derived to illustrate the recurrence intervals of maximum rainfall across Thailand. The predicted return values tend to increase at each site, which is associated with growth curves that could describe an increasing long-term predictive pattern. The findings of this study hold significant implications for water management strategies and the design of flood mitigation structures in the country.

• Korean Journal of Environmental Biology
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• v.42 no.3
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• pp.258-266
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• 2024

A crustose red alga, Lithophyllum neo-okamurae A.Kato, D.Basso, Caragnano, Rodondi, V.Peña & M.Baba, is reported a new record from Korea and its biogeographic distributions are extended in Korea. Lithophyllum neo-okamurae has been known as endemic species in Japan. Despite the resemblance between L. neookamurae and L. okamurae, our molecular and morphological analyses have revealed the simultaneous presence of both species in Korea. Although L. neo-okamurae and L. okamurae share morphological similarities, there are notable variations in gene sequences, with a range of 9.1-11.3% in psbA and 14.8-15.3% in rbcL. Specifically, while L. neo-okamurae is distributed throughout the entire coastline of Korea, L. okamurae is predominantly found in southern region. Furthermore, our analyses have revealed their detailed distributions in Korea.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.1
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• pp.103-106
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• 2012

To investigate distribution characteristics of heavy metals in soils in the vicinity of King Sejong Station of King George Island, Antarctica, Fe, Mn, Cu, Zn, Pb, Co, Cd, Cr, Ni and Mo contents were investigated under different distances and directions from King Sejong Station. 13 sample sites were distributed from King Sejong Station. In site 4, the Cd content was higher than that in other sites. The Cr content was the highest in site 9, and the Ni and Mn contents were high in site 12. Cu, Co and Zn were highly contained in distance 1~2 km from King Sejong Station. Cd, Cr, Ni and Mo contents were lower, whereas Fe, Mn, Cu, Zn, Pb and Co contents were higher than other heavy metal contents at all sites.

• Journal of Microbiology and Biotechnology
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• v.19 no.9
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• pp.1051-1054
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• 2009

This cross-sectional study examined the distribution of HPV 58 sequence variation in Korean women for the first time. Among 1,750 Korean women, 53 women were positive for HPV 58 single infection, of whom 26 were without disease, 20 were with cervical intraepithelial neoplasia (CIN) 1, and 7 with CIN 2 or 3. Altogether, 36 different nucleotide sequence variations were identified with the L1, 20 within E2, 5 within E6, and 10 within E7. Further studies on variants of oncogenic HPVs are necessary, particularly for the purpose of developing more predictive HPV detection methods.

• International Journal of Costume and Fashion
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• v.10 no.2
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• pp.73-88
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• 2010

Study aims to identify customer equity drivers and their relative importance, to represent customer lifetime value (CLV) distribution, and to investigate the effect of customer equity drivers and demographics on CLV when shopping apparels at the four big department stores in Seoul. Recently, Korean department stores marked significant decrease in sales volume and it calls for more focus on customer orientation. Customer equity is a managerial concept which considers customers as a valuable asset for business success. Sustainable competitive advantage is attainable when customer equity drivers and CLV are measured, managed and enhanced. results identified four dimensions of customer equity drivers such as 'retail brand equity: 'relationship equity', 'retail service equity', and 'price value equity'. Among them, 'relationship equity' was proved to be the most influencing factor on the customer's store patronage intention. The CLV distribution represented unique characteristics of each department store. The level of CLV depended on such demographics as age and income. Marital status influenced the relationship between perceived customer equity drivers and CLV. It also analyzed competitive structure of the four big department stores in Seoul and offered managerial suggestions. This study provided conceptual framework for the future study of customer equity related to apparel shopping at the department stores as well as managerial implications.

• Journal of Radiation Protection and Research
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• v.28 no.4
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• pp.353-360
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• 2003

The concentration of $^{137}Cs$, the particle size, and the contents of TOC, H, N and S were measured for sediments collected in the adjacent sea to Yangnam, Korea. The concentrations of $^{137}Cs$ in sediments are in the range of $^{137}Cs$ for sediments strongly depend on particle size and TOC content of sediments. The results of multiple regression analysis suggest that humic substances may have great influence on the deposition of $^{137}Cs$ in sediment.

• Journal of Korean Society for Quality Management
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• v.41 no.1
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• pp.149-162
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• 2013

Purpose: The purpose of this study was to design of a probabilistic model for optimum manpower planning in R&D department by Montecarlo simulation. Methods: We investigate the process and the requirement of manpower planning and scheduling in R&D department. The empirical distributions of necessary time and manpower for R&D projects are developed. From the empirical distributions, we can estimate a probability distribution of optimum manpower in R&D department. A simulation method of estimating the probability distribution of optimum manpower is considered. It is a useful tool for obtaining the sum, the variance and other statistics of the distributions. Results: The real industry cases are given and the properties of the model are investigated by Montecarlo Simulation. we apply the model to the research laboratory of the global company, and investigate and compensate the weak points of the model. Conclusion: The proposed model provides various and correct information such as average, variance, percentile, minimum, maximum and so on. A decision maker of a company can easily develop the future plan and the task of researchers may be allocated properly. we expect that the productivity can be improved by this study. The results of this study can be also applied to other areas including shipbuilding, construction, and consulting areas.

• Tuberculosis and Respiratory Diseases
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• v.64 no.3
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• pp.236-239
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• 2008

A unique case of atypical pulmonary sarcoidosis in a 62-year-old man complaining of dyspnea is presented. Chest CT scan showed an unusual pattern and distribution of pulmonary sarcoidosis manifesting mainly as reticular densities, interlobular septal thickening, and ground-glass opacities, in the subpleural and lower lung predominancy. However, a surgical lung biopsy revealed classical findings of sarcoidosis. Knowledge of this atypical pulmonary involvement may improve understanding sarcoidosis as the great masquerader.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.79-80
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• 2006

본 논문에서는 초고압전력용 케이블에서 절연재료로 사용되고 있는 가교폴리에틸렌 내부(XLPE)에 침투된 침전극의 기울기변화에 따른 XLPE의 전계분포를 경계요소법에 의한 3차원 시뮬레이션 프로그램을 통하여 해석하여, 약 $20^{\circ}$의 기울기에서 전계가 집중되는 현상을 확인하였다.