• Korean Chemical Engineering Research
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• v.60 no.2
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• pp.249-254
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• 2022

With the rapid advance of the semiconductor and Information and communication technologies, remote environment monitoring technology, which can detect and analyze surrounding environmental conditions with various types of sensors and wireless communication technologies, is also drawing attention. However, since the conventional remote environmental monitoring systems require external power supplies, it causes time and space limitations on comfortable usage. In this study, we proposed the concept of the self-powered remote environmental monitoring system by supplying the power with the levitation-electromagnetic generator (L-EMG), which is rationally designed to effectively harvest biomechanical energy in consideration of the mechanical characteristics of biomechanical energy. In this regard, the proposed L-EMG is designed to effectively respond to the external vibration with the movable center magnet considering the mechanical characteristics of the biomechanical energy, such as relatively low-frequency and high amplitude of vibration. Hence the L-EMG based on the fragile force equilibrium can generate high-quality electrical energy to supply power. Additionally, the environmental detective sensor and wireless transmission module are composed of the micro control unit (MCU) to minimize the required power for electronic device operation by applying the sleep mode, resulting in the extension of operation time. Finally, in order to maximize user convenience, a mobile phone application was built to enable easy monitoring of the surrounding environment. Thus, the proposed concept not only verifies the possibility of establishing the self-powered remote environmental monitoring system using biomechanical energy but further suggests a design guideline.

• Journal of the Korean earth science society
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• v.42 no.6
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• pp.632-645
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• 2021

Satellite sea surface temperature (SST) composites provide important data for numerical forecasting models and for research on global warming and climate change. In this study, six types of representative SST composite database were collected from 2007 to 2018 and the characteristics of spatial structures of SSTs were analyzed in seas around the Korean Peninsula. The SST composite data were compared with time series of in-situ measurements from ocean meteorological buoys of the Korea Meteorological Administration by analyzing the maximum value of the errors and its occurrence time at each buoy station. High differences between the SST data and in-situ measurements were detected in the western coastal stations, in particular Deokjeokdo and Chilbaldo, with a dominant annual or semi-annual cycle. In Pohang buoy, a high SST difference was observed in the summer of 2013, when cold water appeared in the surface layer due to strong upwelling. As a result of spectrum analysis of the time series SST data, daily satellite SSTs showed similar spectral energy from in-situ measurements at periods longer than one month approximately. On the other hand, the difference of spectral energy between the satellite SSTs and in-situ temperature tended to magnify as the temporal frequency increased. This suggests a possibility that satellite SST composite data may not adequately express the temporal variability of SST in the near-coastal area. The fronts from satellite SST images revealed the differences among the SST databases in terms of spatial structure and magnitude of the oceanic fronts. The spatial scale expressed by the SST composite field was investigated through spatial spectral analysis. As a result, the high-resolution SST composite images expressed the spatial structures of mesoscale ocean phenomena better than other low-resolution SST images. Therefore, in order to express the actual mesoscale ocean phenomenon in more detail, it is necessary to develop more advanced techniques for producing the SST composites.

• Journal of Navigation and Port Research
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• v.46 no.3
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• pp.179-190
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• 2022

In this study, we investigated the characteristic impedance and bandwidth of CPW3DCS (coplanar waveguide employing periodic 3D coupling structures), and examined its potential for the development of a marine radio communication FISoC (fully-integrated system on chip) semiconductor device. To extract bandwidth and characteristic impedance of the CPW3DC, we induced a measurement-based equation reflecting measured insertion loss, and compared the measured results of the propagation constant β and characteristic impedance with the measured ones. According to the results of the comparison, the calculated results show a good agreement with the measured ones. Concretely, the propagation constant β and characteristic impedance exhibited an maximum error of 3.9% and 6.4%, respectively. According to the results of this study, in a range of LT = 30 ~ 150 ㎛ for the length of periodic structures, the CPW3DC exhibited a passband characteristic of 121 GHz, and a very small dependency of characteristic impedance on frequency. We could realize a low impedance transmission line with a characteristic impedance lower than 20 Ω by using CPW3DCS with a line width of 20 ㎛, which was highly reduced, compared with a 3mm line width of conventional transmission line with the same impedance. The characteristic impedance was easily adjusted by changing LT. The above results indicate that the CPW3DC can be usefully used for the development of a wireless communication FISoC (fully-integrated system on chip) semiconductor device. This is the first report of a study on the bandwidth of the CPW3DC.

• Journal of Korean Home Economics Education Association
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• v.34 no.3
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• pp.133-148
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• 2022

This study aims to explore the status and motives for using avatars and digital fashion items in the metaverse and to examine consumers' purchase satisfaction and future purchase intentions. We intend to provide implications for the development of avatars and fashion items, and the direction of the fashion industry and clothing education. For this purpose, the purchasing status, consumer motives for using avatars and digital fashion items, purchase satisfaction, and future purchase intentions were investigated, through a survey with 149 consumers aged 19 years or older, with the experience of using avatars. The results are as follows. First, the percentage of avatar ownership was high among women aged between 19 and 29, and those with low or high incomes. The younger group was more likely to make mobile phone purchases than the older group, and the older group was more likely to use credit cards. Even those respondents who owned avatars did not purchase frequently or spent a lot on items. On the other hand, in the case of fashion item purchases, the group spending more than 8,000 won was aged between 19 and 29, and the frequency and amount of purchases increased as income increase. Second, among the motives for using avatars and fashion items, the pursuit of pleasure had the greatest influence, and men paid more attention to self-expression through avatars than women. Third, the motive for vicarious satisfaction influenced purchase satisfaction, and the factors that influenced future purchase intention were vicarious satisfaction and stress relief. The results of this study suggests that avatars and fashion items should be developed considering factors that can relieve stress for all age groups, create a sense of unity among metaverse users, and provide satisfaction in a virtual world that is different from reality. In addition, education on how to use fashion items and consumption attitudes in education related to clothing life will be required.

• Journal of Korea Water Resources Association
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• v.54 no.spc1
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• pp.1107-1118
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• 2021

Climate change brought on by global warming increased the frequency of flood and drought on the Korean Peninsula, along with the casualties and physical damage resulting therefrom. Preparation and response to these water disasters requires national-level planning for water resource management. In addition, watershed-level management of water resources requires flow duration curves (FDC) derived from continuous data based on long-term observations. Traditionally, in water resource studies, physical rainfall-runoff models are widely used to generate duration curves. However, a number of recent studies explored the use of data-based deep learning techniques for runoff prediction. Physical models produce hydraulically and hydrologically reliable results. However, these models require a high level of understanding and may also take longer to operate. On the other hand, data-based deep-learning techniques offer the benefit if less input data requirement and shorter operation time. However, the relationship between input and output data is processed in a black box, making it impossible to consider hydraulic and hydrological characteristics. This study chose one from each category. For the physical model, this study calculated long-term data without missing data using parameter calibration of the Soil Water Assessment Tool (SWAT), a physical model tested for its applicability in Korea and other countries. The data was used as training data for the Long Short-Term Memory (LSTM) data-based deep learning technique. An anlysis of the time-series data fond that, during the calibration period (2017-18), the Nash-Sutcliffe Efficiency (NSE) and the determinanation coefficient for fit comparison were high at 0.04 and 0.03, respectively, indicating that the SWAT results are superior to the LSTM results. In addition, the annual time-series data from the models were sorted in the descending order, and the resulting flow duration curves were compared with the duration curves based on the observed flow, and the NSE for the SWAT and the LSTM models were 0.95 and 0.91, respectively, and the determination coefficients were 0.96 and 0.92, respectively. The findings indicate that both models yield good performance. Even though the LSTM requires improved simulation accuracy in the low flow sections, the LSTM appears to be widely applicable to calculating flow duration curves for large basins that require longer time for model development and operation due to vast data input, and non-measured basins with insufficient input data.

• Journal of the Korean earth science society
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• v.43 no.5
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• pp.591-603
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• 2022

The color and optical properties of seawater are determined by the interaction between dissolved organic and inorganic substances and plankton contained in it. The Ieodo - Ocean Research Institute (I-ORS), located in the East China Sea, is affected by the low salinity of the Yangtze River in the west and the Tsushima Warm Current in the south. Thus, it is a suitable site for analyzing the fluctuations in circulation and optical properties around the Korean Peninsula. In this study, seawater surrounding the I-ORS was classified according to its optical characteristics using the satellite remote reflectance observed with Moderate Resolution Imaging Spectroradiometer (MODIS)/Aqua and National Aeronautics and Space Administration (NASA) bio-Optical Marine Algorithm Dataset (NOMAD) from January 2016 to December 2020. Additionally, the variation characteristics of optical water types (OWTs) from different seasons were presented. A total of 59,532 satellite match-up data (d ≤ 10 km) collected from seawater surrounding the I-ORS were classified into 23 types using the spectral angle mapper. The OWTs appearing in relatively clear waters surrounding the I-ORS were observed to be greater than 50% of the total. The maximum OWTs frequency in summer and winter was opposite according to season. In particular, the OWTs corresponding to optically clear seawater were primarily present in the summer. However, the same OWTs were lower than overall 1% rate in winter. Considering the OWTs fluctuations in the East China Sea, the I-ORS is inferred to be located in the transition zone of seawater. This study contributes in understanding the optical characteristics of seawater and improving the accuracy of satellite ocean color variables.

• Journal of Korea Entertainment Industry Association
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• v.14 no.3
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• pp.27-40
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• 2020

The marathon has long been established as a representative lifestyle for all ages. With the recent expansion of the Work and Life Balance trend across the society, marathon with a relatively low barrier to entry is gaining popularity among young people in their 20s and 30s. By analyzing the issues and related words of the marathon event, we will analyze the spottainment elements of the marathon event that is popular among young people through keywords, and suggest a development plan for the differentiated event. In order to analyze keywords and related words, blogs, cafes and news provided by Naver and Daum were selected as analysis channels, and 'JTBC Marathon' and 'Culture' were extracted as key words for data search. The data analysis period was limited to a three-month period from August 13, 2019 to November 13, 2019, when the application for participation in the 2019 JTBC Marathon was started. For data collection and analysis, frequency and matrix data were extracted through social matrix program Textom. In addition, the degree of the relationship was quantified by analyzing the connection structure and the centrality of the degree of connection between the words. Although the marathon is a personal movement, young people share a common denominator of "running" and form a new cultural group called "running crew" with other young people. Through this, it was found that a marathon competition culture was formed as a festival venue where people could train together, participate together, and escape from the image of a marathon run alone and fight with themselves.

• Journal of Christian Education in Korea
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• v.68
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• pp.245-277
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• 2021

The purpose of this study was to investigate the trend of Christian picture book-related research. The purpose of this study is to present basic data for various and balanced research and development in the Christian picture book field by analyzing the research period, research content, and research method related to Christian picture books. For this study, 45 domestic master's and doctoral dissertations were extracted through the National Assembly Library and the Academic Research Information Service (RISS) with the keywords of 'Christian picture book', 'Bible picture book', 'Christian story', and 'Bible story'. The frequency and percentage were calculated by analyzing Christian picture book-related studies according to four criteria: research period, research content, research method, and research subject. As a result of the study, first, the trend of Christian picture book research papers by research period from 1999 to 2021 was 43 master's articles (95.6%) and 2 doctoral articles (4.4%), focusing on Christian picture book-related studies. Second, the trend by research content was found to be 12 basic studies (26.6%) and 33 practical studies (73.4%). Research related to Christian picture books is being actively conducted focusing on practical research rather than basic research. Third, the trend by research method was in the order of 33 quantitative studies (73.4%), 11 literature studies (24.4%), and 1 qualitative study (2.2%). Research related to Christian picture books is centered on quantitative research, and literature research and qualitative research account for a relatively low proportion. Fourth, as for the trends by study subject, there were 35 human subjects (77.8%) and 10 physical subjects (22.2%). Among human subjects, 33 single subjects (73.4%) and 2 mixed subjects (4.4%) were found, and among single subjects, 30 studies (66.7%) targeting children were high. In other words, research on Christian picture books had a higher proportion of studies with children as a single subject than mixed subjects between children and children, children and teachers, and between children and parents.

• Korean Journal of Psychosomatic Medicine
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• v.30 no.2
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• pp.127-136
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• 2022

Objectives : The study aimed to identify factors associated with suicidal attempt in Korean adults experiencing thoughts of suicide. Methods : This study analyzed outcomes of suicidal behavior in the Korea National Health and Nutrition Examination Survey (KNHANES) 2015, 2017, and 2019. This survey was administered by the Korea Centers for Disease Control and Prevention (KCDC). The suicidal idea group was divided into individuals who had attempted suicide (n=92) and those who had not (n=831). Complex samples crosstabs analysis was conducted to compare the two groups' sociodemographic, psychiatric, and clinical characteristics. In addition, factors related to attempted suicide were investigated using complex samples logistic regression analysis. Results : The attempted suicide group had significantly higher rates of depression, recent psychiatric counseling, and suicidal plan (p<0.001) than the non-attempting group. In addition, the groups differed significantly in the frequency of binge drinking and smoking (p<0.05). Adjusted multivariate analysis revealed that the presence of a suicidal plan (Odds ratio [OR]=8.46, 95% Confidential Intervals [CI]=4.72-15.00), daily binge drinking (OR=3.14, 95% CI=1.26-7.84), psychiatric counseling within the past year (OR=3.03, 95% CI=1.75-5.23), low income level (OR=2.89, 95% CI=1.17-7.10), and history of depression (OR=2.39, 95% CI=1.29-4.42) were significantly associated with suicidal attempt. Conclusions : Factors associated with suicidal attempt among suicidal ideators in the general Korean population were identified across all sociodemographic, psychiatric, and clinical variables. Assessment of and intervention in suicidal plan, binge drinking, income level, and depression might prevent progression to suicidal attempt among those contemplating suicide.

• Journal of Food Hygiene and Safety
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• v.37 no.6
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• pp.385-393
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• 2022

The contamination level of inorganic arsenic, a human carcinogen, was investigated in 87 grains and 66 processed grain foods. Two inorganic arsenic species arsenite (As(III)) and arsenate (As(V)) and four organic arsenic monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, arsenocholine were analyzed using HPLC-ICP/MS with high separation and sensitivity and ICP/MS was used to quantify total arsenic. Inorganic arsenic was detected in all grains. And the total arsenic in grains consists of about 70-85% inorganic arsenic and about 10-20% DMA. The concentration of inorganic arsenic was high in rice and black rice cultivated in paddy soil with irrigated water, while the miscellaneous grain in field was low. Mean concentration of inorganic arsenic in rice germ, brown rice and polished rice was 0.160 mg/kg, 0.135 mg/kg, 0.083 mg/kg, respectively, indicating that rice bran contains more arsenic. In processed grain foods, inorganic arsenic concentration varied according to the kind of ingredients and content, and the detection amount was high in processed food with brown rice and germ. The arsenic content of all samples did not exceed each standard, but the intake frequency is high and it is considered that continuous monitoring is necessary for food safety.