• The Korean Journal of Nuclear Medicine Technology
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• v.23 no.1
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• pp.15-28
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• 2019

Purpose Nuclear medicine was initially introduced in Korea in 1969 and widely applied to treat hyperthyroidism with $^{131}I$. Also, gamma camera was adopted in 1969 in the first place and its application has been growing continually in many ways. We analyzed long-term trend in nuclear medicine examinations for the last 2 decades. The purpose of this paper is to make predictions and to set both plans and directions on the development of nuclear medicine. Materials and Methods We analyzed the performance of nuclear medicine examinations and therapies performed in Asan Medical Center from 1998 to 2017. Results Results from the last 20 years regarding Bone scan, Renal scan, MUGA scan and $^{18}F$-FPCIT, Bone Mineral Density were on a increase. And Myocardium perfusion SPECT, Thyroid scan, Lung scan were on a decrease while $^{18}F-FDG$ PET maintained on a steady course. Until 2010 there was a positive performance with the therapy but after the excessive medical care in thyroid examination performance is at status quo. Key events such as a medical strike(2000), Middle-East Respiratory Syndrome (2015) influenced the overall performance of the therapy. Conclusion In order to promote a long-term growth in nuclear medicine examination and therapy, it is inevitable to respond to the changes in current medical environment. Furthermore, it is strongly suggested to put efforts to maintain and develop new examinations and clinical indicators.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.3
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• pp.175-186
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• 2019

Efforts have been made to introduce the climate smart agriculture (CSA) for adaptation to future climate conditions, which would require collection and management of site specific meteorological data. The objectives of this study were to identify requirements for construction of agricultural meteorology information service system (AMISS) using technologies that lead to the fourth industrial revolution, e.g., internet of things (IoT), artificial intelligence, and cloud computing. The IoT sensors that require low cost and low operating current would be useful to organize wireless sensor network (WSN) for collection and analysis of weather measurement data, which would help assessment of productivity for an agricultural ecosystem. It would be recommended to extend the spatial extent of the WSN to a rural community, which would benefit a greater number of farms. It is preferred to create the big data for agricultural meteorology in order to produce and evaluate the site specific data in rural areas. The digital climate map can be improved using artificial intelligence such as deep neural networks. Furthermore, cloud computing and fog computing would help reduce costs and enhance the user experience of the AMISS. In addition, it would be advantageous to combine environmental data and farm management data, e.g., price data for the produce of interest. It would also be needed to develop a mobile application whose user interface could meet the needs of stakeholders. These fourth industrial revolution technologies would facilitate the development of the AMISS and wide application of the CSA.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.1
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• pp.29-41
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• 2019

Terrestrial Gross Primary Production (GPP) is the largest global carbon flux, and forest ecosystems are important because of the ability to store much more significant amounts of carbon than other terrestrial ecosystems. There have been several attempts to estimate GPP using mechanism-based models. However, mechanism-based models including biological, chemical, and physical processes are limited due to a lack of flexibility in predicting non-stationary ecological processes, which are caused by a local and global change. Instead mechanism-free methods are strongly recommended to estimate nonlinear dynamics that occur in nature like GPP. Therefore, we used the mechanism-free machine learning techniques to estimate the daily GPP. In this study, support vector machine (SVM), random forest (RF) and artificial neural network (ANN) were used and compared with the traditional multiple linear regression model (LM). MODIS products and meteorological parameters from eddy covariance data were employed to train the machine learning and LM models from 2006 to 2013. GPP prediction models were compared with daily GPP from eddy covariance measurement in a deciduous forest in South Korea in 2014 and 2015. Statistical analysis including correlation coefficient (R), root mean square error (RMSE) and mean squared error (MSE) were used to evaluate the performance of models. In general, the models from machine-learning algorithms (R = 0.85 - 0.93, MSE = 1.00 - 2.05, p < 0.001) showed better performance than linear regression model (R = 0.82 - 0.92, MSE = 1.24 - 2.45, p < 0.001). These results provide insight into high predictability and the possibility of expansion through the use of the mechanism-free machine-learning models and remote sensing for predicting non-stationary ecological processes such as seasonal GPP.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.501-513
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• 2019

In this study, which is based on the findings of the preceding studies, the researchers determined social support and Career Decision Self-efficacy as the key influencing variables for the successful Career Preparation Activities, to analyze the relationship between Career Preparation Activities and these variables, while identifying the mediating effect of Career Decision Self-efficacy in the relationship between social support and Career Preparation Activities. In addition, there is an objective to provide effective career counseling materials. For this study, a total of 174 North Korean adolescent defectors, who were in their middle and high schools, were interviewed and the resultant data were analyzed the data based on the questionnaire data of 204 copies from March 12 to 19, 2019. For the analysis of the data, SPSS and AMOS statistical suites were used to verify the hypothesis. The result of the analysis showed that, first, in the relationship between the social support, Career Decision Self-efficacy, and Career Preparation Activities of the North Korean adolescent defectors social support, Career Decision Self-efficacy, and Career Preparation Activities were all positively related. Especially, Career Decision Self-efficacy has been identified as the variable that is highly related to Career Preparation Activities. Second, rather than social support(${\beta}=.107$), Career Decision Self-efficacy(${\beta}=.388$) turned out to have more profound direct influence on Career Preparation Activities. Third, social support did not influence Career Preparation Activities directly(${\beta}=.107$, p>.05) but completely intermediated Career Decision Self-efficacy to influence Career Preparation Activities(Indirect effect=.307, p<.05, Z-value=2.924, p<.01). The findings of this study show that, in order to enhance the Career Preparation Activities of the North Korean adolescent defectors, it is necessary to examine how they perceive the emotional, informational, material, and evaluative supports from the surrounding environment are perceived and identify the abilities, values, and career desires of themselves through a behavioral planning that can establish a professional and value system in accordance with them.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.26 no.1
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• pp.11-36
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• 2021

The solar annual (Sa) and semiannual (Ssa) tides account for much of the non-uniform annual and seasonal variability observed in sea levels. These non-equilibrium tides depend on atmospheric variations, forced by changes in the Sun's distance and declination, as well as on hydrographic conditions. Here we employ tidal harmonic analyses to calculate Sa and Ssa harmonic constants for 21 Korean coastal tidal stations (TS), operated by the Korea Hydrographic and Oceanographic Agency. We used 19 year-long (1999 to 2017) 1 hr-interval sea level records from each site, and used two conventional harmonic analysis (HA) programs (Task2K and UTide). The stability of Sa harmonic constants was estimated with respect to starting date and record length of the data, and we examined the spatial distribution of the calculated Sa and Ssa harmonic constants. HA was performed on Incheon TS (ITS) records using 369-day subsets; the first start date was January 1, 1999, the subsequent data subset starting 24 hours later, and so on up until the final start date was December 27, 2017. Variations in the Sa constants produced by the two HA packages had similar magnitudes and start date sensitivity. Results from the two HA packages had a large difference in phase lag (about 78°) but relatively small amplitude (<1 cm) difference. The phase lag difference occurred in large part since Task2K excludes the perihelion astronomical variable. Sensitivity of the ITS Sa constants to data record length (i.e., 1, 2, 3, 5, 9, and 19 years) was also tested to determine the data length needed to yield stable Sa results. HA results revealed that 5 to 9 year sea level records could estimate Sa harmonic constants with relatively small error, while the best results are produced using 19 year-long records. As noted earlier, Sa amplitudes vary with regional hydrographic and atmospheric conditions. Sa amplitudes at the twenty one TS ranged from 15.0 to 18.6 cm, 10.7 to 17.5 cm, and 10.5 to 13.0 cm, along the west coast, south coast including Jejudo, and east coast including Ulleungdo, respectively. Except at Ulleungdo, it was found that the Ssa constituent contributes to produce asymmetric seasonal sea level variation and it delays (hastens) the highest (lowest) sea levels. Comparisons between monthly mean, air-pressure adjusted, and steric sea level variations revealed that year-to-year and asymmetric seasonal variations in sea levels were largely produced by steric sea level variation and inverted barometer effect.

• 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 Korean Society of Forest Science
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• v.111 no.4
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• pp.461-472
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• 2022

Natural and anthropogenic factors cause forest types to continuously change. Since the ratio of forest area by forest type is important information for identifying the characteristics of national forest resources, an accurate understanding of the prospect of forest type change is required. The study aim was to use National Forest Inventory (NFI) time-series data to understand the characteristics of forest type change and to estimate future prospects of nationwide forest type change. We used forest type change information from the fifth and seventh NFI datasets, climate, topography, forest stand, and disturbance variables related to forest type change to analyze trends and characteristics of forest type change. The results showed that the forests in Korea are changing in the direction of decreasing coniferous forests and increasing mixed and broadleaf forests. The forest sites that were changing from coniferous to mixed forests or from mixed to broadleaf forests were mainly located in wet topographic environments and climatic conditions. The forest type changes occurred more frequently in sites with high disturbance potential (high temperature, young or sparse forest stands, and non-forest areas). We used a climate change scenario (RCP 8.5) to establish a forest type change model (SVM) to predict future changes. During the 40-year period from 2015 to 2055, the SVM predicted that coniferous forests will decrease from 38.1% to 28.5%, broadleaf forests will increase from 34.2% to 38.8%, and mixed forests will increase from 27.7% to 32.7%. These results can be used as basic data for establishing future forest management strategies.

• Journal of Korean Society of Forest Science
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• v.111 no.3
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• pp.365-373
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• 2022

We compared carbon stocks in tree biomass and soils of Quercus acutissima, Q. mongolica, Q. serrata, and Q. variabilis stands. A total of 531 plots (Q. acutissima: 110 plots, Q. mongolica: 177 plots, Q. serrata: 96 plots, Q. variabilis: 148 plots) were examined between 2016 and 2021 to determine the tree biomass and soil carbon stocks throughout the country. The carbon stocks of tree biomass were significantly higher in Q. mongolica (mean stand age, 57 years, 144.9 Mg C ha^-1) than in Q. variabilis (mean stand age, 43 years, 123.7 Mg C ha^-1), Q. serrata (mean stand age, 43 years, 120.1 Mg C ha^-1), and Q. acutissima (mean stand age, 36 years, 113.2 Mg C ha^-1) stands. The soil carbon concentration was significantly higher in Q. mongolica (A: 43.1 mg C g-1) than in Q. serrata (31.0 mg C g-1), Q. variabilis (25.31 mg C g-1), and Q. acutissima (24.4 mg C g-1) stands. The soil carbon stocks were significantly higher in Q. mongolica (116.8 Mg C ha^-1) than in Q. acutissima (49.3 Mg C ha^-1) stands. Total carbon stocks of tree biomass and soil were highest in Q. mongolica (262 Mg C ha^-1), followed by Q. serrata (218 Mg C ha^-1), Q. variabilis (211 Mg C ha^-1), and Q. acutissima (163 Mg C ha^-1) stands. Multiple linear regressions were performed to estimate the total carbon stocks of the four Quercus spp., and results showed that total carbon stocks increased with increasing elevation, mean diameter at breast height, and basal areas. Basal area and elevation of Quercus spp. stands were important explanatory variables based on multiple linear regressions for estimating carbon stocks.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.6
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• pp.21-35
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• 2022

With the support of local and central governments, various incentive policies for "green" cars have been established, and the number of electric vehicle users has been rapidly increasing in recent years. As a result, much attention is being given to establishing a user-centered charging infrastructure. A standard for the number of electric vehicle chargers to be supplied is being prepared based on building characteristics, but there is quite limited research on the appropriate ratio of slow and fast chargers based on the characteristics of each place. Therefore, this study derived an appropriate penetration ratio based on data about the distribution ratio of common slow chargers. These data were collected using a survey of actual electric vehicle users. Next, an analysis was done on how to categorize the needs of charging environments and to determine what criteria or characteristics to use for categorization. Based on the results of the survey analysis, three types of places were derived. Type-1 places require 10% of chargers to be slow chargers, Type-2 places require 40-60% of chargers to be slow chargers (i.e., around equal distribution of slow and fast chargers), and Type-3 places require more than 80% of chargers to be slow chargers. The required levels of slow chargers were classified by place type and by individual using latent class cluster analysis, which made it possible to categorize them into five clusters related to socioeconomic variables, vehicle characteristics, traffic, and charging behaviors. It was found that there was a high correlation between charging behavior, weekend travel behavior, gender, and income. The results and insights from this study could be used to establish charging infrastructure policies in the future and to prepare standards for supplying charging infrastructure according to changes in the electric vehicle market.

• Journal of Korea Port Economic Association
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• v.39 no.1
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• pp.65-100
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• 2023

This study examines the effects of organizational trust of the container terminal operators' employee on organizational citizenship behavior and the moderating effect of organizational support in the relationship between the two variables. In order to efficiently achieve the purpose of this study, an empirical analysis was conducted by distributing a literature review and a questionnaire, and the results of the study are as follows... First, the organizational trust of the container terminal operators' employee was found to have a significant positive (+) effect on organizational citizenship behavior, and trust in the company appeared to be more important than trust in the superior, indicating trust in the institutional aspect. This means that formation has more influence on organizational citizenship behavior... Second, it was confirmed that the organizational support of the container terminal operators' employee can lead to active participation in organizational citizenship behavior through the expansion of educational compensatory support. Third, among the organizational support of container terminal operators, emotional support and educational compensatory support were found to have a partial moderating effect on the relationship between organizational trust and organizational citizenship behavior." Emotional support has a moderating effect on caring and active participation behaviors in the relationship between trust in the company and organizational citizenship behaviors, and a moderating effect on caring, active participation, and non-complaining behaviors in the relationship between trust in superiors and organizational citizenship behaviors. It was analyzed that there is Compensatory educational support has a moderating effect on altruistic, caring, active participation, and non-complaining behavior in the relationship between trust in the company and organizational citizenship behavior. It was analyzed that there was a moderating effect on active participation and non-complaining behavior. These analysis results mean that members' trust in the company further increases through the container terminal operator's emotional support and educational reward support. As uncertainty grows, it is very important to increase the trust of organizational members in the organization. sense of belonging to the organization, Emotional support that can increase immersion, improvement of work environment, provision of educational opportunities, and education-compensatory support such as a fair compensation system will increase organizational trust and induce effective organizational citizenship behavior to realize sustainable growth of the organization.