• Journal of Korean Society of Forest Science
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• v.107 no.4
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• pp.486-496
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• 2018

Pine wilt disease (PWD) in Gyeonggi province was first detected in Gwangju in 2007, and ever since has caused extensive damage. Insect vector and host tree in Gyeonggi province are Monochamus saltuarius and Pinus koraiensis, respectively, which are different from the southern region that consist of Monochamus alternatus and Pinus densiflora. Consequently, spread and mortality characteristics may be different, but our understanding is limited. In this research, we utilized the spatial data of newly infected trees in Gyeonggi province from 2008 to 2015 to analyze how it is related to various environmental and human factors, such as elevation, forest type, and road network. We also analyzed the minimum distance from newly infected tree to last year's closest infected tree to examine the dispersal characteristics based on new outbreak locations. Annual number of newly infected trees rapidly increased from 2008 to 2013, which then stabilized. Number of administrative districts with infected trees was 5 in 2012, 11 in 2013, and 15 in 2014. Most of the infected trees was Pinus koraiensis, with its proportion close to 90% throughout the survey period. Mean distance to newly infected trees dramatically decreased over time, from 4,111 m from 2012 to 2013, to approximately 600 m from 2013 to 2014 and 2014 to 2015. Most new infections occurred in higher elevation over time. Distance to road from newly infected trees continuously increased, suggesting that natural diffusion dispersal is increasingly occurring compared to human-influenced dispersal over time.

• Korean Journal of Remote Sensing
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• v.37 no.3
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• pp.531-542
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• 2021

Open-pit mines require constant monitoring as they can cause surface changes and environmental disturbances. In open-pit mines, there is little vegetation at the mining site and can be monitored using InSAR (Interferometric Synthetic Aperture Radar) coherence imageries. In this study, activities occurring in mine were analyzed by applying the recently developed InSAR coherence-based NDAI (Normalized Difference Activity Index). The March 5 Youth Mine is a North Korean mine whose development has been expanded since 2008. NDAI analysis was performed with InSAR coherence imageries obtained using Sentinel-1 SAR images taken at 12-day intervals in the March 5 Youth Mine. First, the area where the elevation decreased by about 75.24 m and increased by about 9.85 m over the 14 years from 2000 was defined as the mining site and the tailings piles. Then, the NDAI images were used for time series analysis at various time intervals. Over the entire period (2017-2019), average mining activity was relatively active at the center of the mining area. In order to find out more detailed changes in the surface activity of the mine, the time interval was reduced and the activity was observed over a 1-year period. In 2017, we analyzed changes in mining operations before and after artificial earthquakes based on seismic data and NDAI images. After the large-scale blasting that occurred on 30 April 2017, activity was detected west of the mining area. It is estimated that the size of the mining area was enlarged by two blasts on 30 September 2017. The time-averaged NDAI images used to perform detailed time-series analysis were generated over a period of 1 year and 4 months, and then composited into RGB images. Annual analysis of activity confirmed an active region in the northeast of the mining area in 2018 and found the characteristic activity of the expansion of tailings piles in 2019. Time series analysis using NDAI was able to detect random surface changes in open-pit mines that are difficult to identify with optical images. Especially in areas where in situ data is not available, remote sensing can effectively perform mining activity analysis.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.915-929
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• 2023

Improvements in people's quality of life, diversification of leisure activities, and changes in population structure have led to an increase in the demand for tourism and an expansion of the diversification of tourism activities. In particular, for coastal cities where land and marine tourism elements coexist, various factors influence their tourism demands. Tourism requires the construction of infrastructure and content development according to the demand at the tourist destination. This study aims to improve the prediction accuracy and explore influencing factors through time series analysis of tourism scale using agent-based data. Basic local governments in the Busan area were examined, and the data used were the number of tourists and the amount of tourism consumption on a monthly basis. The univariate time series analysis, which is a deterministic model, was used along with the SARIMAX analysis to identify the influencing factor. The tourism consumption propensity, focusing on the consumption amount according to business types and the amount of mentions on SNS, was set as the influencing factor. The difference in accuracy (RMSE standard) between the time series models that did and did not consider COVID-19 was found to be very wide, ranging from 1.8 times to 32.7 times by region. Additionally, considering the influencing factor, the tourism consumption business type and SNS trends were found to significantly impact the number of tourists and the amount of tourism consumption. Therefore, to predict future demand, external influences as well as the tourists' consumption tendencies and interests in terms of local tourism must be considered. This study aimed to predict future tourism demand in a coastal city such as Busan and identify factors affecting tourism scale, thereby contributing to policy decision-making to prepare tourism demand in consideration of government tourism policies and tourism trends.

• Korean Journal of Remote Sensing
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• v.39 no.5_1
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• pp.655-667
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• 2023

Algal bloom outbreaks are frequently reported around the world, and serious water pollution problems arise every year in Korea. It is necessary to protect the aquatic ecosystem through continuous management and rapid response. Many studies using satellite images are being conducted to estimate the concentration of chlorophyll-a (Chl-a), an indicator of algal bloom occurrence. However, machine learning models have recently been used because it is difficult to accurately calculate Chl-a due to the spectral characteristics and atmospheric correction errors that change depending on the water system. It is necessary to consider the factors affecting algal bloom as well as the satellite spectral index. Therefore, this study constructed a dataset by considering water quality, hydrological and meteorological factors, and sentinel-2 images in combination. Representative ensemble models random forest and extreme gradient boosting (XGBoost) were used to predict the concentration of Chl-a in eight weirs located on the Nakdong river over the past five years. R-squared score (R²), root mean square errors (RMSE), and mean absolute errors (MAE) were used as model evaluation indicators, and it was confirmed that R² of XGBoost was 0.80, RMSE was 6.612, and MAE was 4.457. Shapley additive expansion analysis showed that water quality factors, suspended solids, biochemical oxygen demand, dissolved oxygen, and the band ratio using red edge bands were of high importance in both models. Various input data were confirmed to help improve model performance, and it seems that it can be applied to domestic and international algal bloom detection.

• Korean Journal of Heritage: History & Science
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• v.56 no.4
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• pp.132-158
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• 2023

The five-story and seven-story stone pagodas at Cheongnyangsaji temple site in Gongju are located under the Sambulbong peak of Gyeryongsan mountain, and are known to have been built of the middle in Goryeo dynasty. As the two pagodas in which two types of Baekje stone pagoda coexist in one era, their historical and academic value are recognized. The seven-story pagoda was overturned by robbery in 1944, and as a result, the five-story pagoda was tilted. Although the two pagodas were restored in 1961, structural instability was continuously raised. In this study, measurement data accumulated from May 2021 to March 2022, and seasonal characteristics were reviewed, and the micro behavior of pagodas were analyzed according to temperature and precipitation during the same period. As a result, the micro thermoelastic behavior was repeated according to the daily temperature change in all sensors, and both the slope and the displacement showed microscale behavior. In the inclinometer, moisture containing the surface and inside of the stones repeated expansion and contraction due to temperature change, showing the micro movements. In particular, the upper part of the five-story pagoda moved up to 3.89° to the northwest, and the seven-story pagoda tilted up to 0.078° to the northeast. The maximum displacements were recorded as 0.127 and 0.149 mm in the five-story and the seven-story pagoda, respectively. These values tended to return to the original position at the end of the measurement, but did not recover completely, indicating a state requiring precise monitoring. The result obtained through the study can be used as basic data for the stable conservation of the two stone pagodas. Based on the behavioral characteristics considering various environmental factors should be analyzed, and the preventive conservation through the maintenance of measurement system built this time should be continued.

• Journal of the Korea Institute of Building Construction
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• v.24 no.2
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• pp.273-284
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• 2024

This study investigates the impact of international oil price fluctuations on overseas construction orders secured by domestic and foreign companies. The analysis employs statistical data spanning the past 20 years, encompassing international oil prices, overseas construction orders from domestic firms, and new overseas construction orders from the top 250 global construction companies. The correlation between these variables is assessed using correlation coefficients(R), determination coefficients(R²), and p-values. The results indicate a strong positive correlation between international oil prices and overseas construction orders. The correlation coefficient between domestic overseas construction orders and oil prices is found to be 0.8 or higher, signifying a significant influence. Similarly, a high correlation coefficient of 0.76 is observed between oil prices and new orders from leading global construction companies. Further analysis reveals a particularly strong correlation between oil prices and overseas construction orders in Asia and the Middle East, potentially due to the prevalence of oil-related projects in these regions. Additionally, a high correlation is observed between oil prices and orders for industrial facilities compared to architectural projects. This suggests an increase in plant construction volumes driven by fluctuations in oil prices. Based on these findings, the study proposes an entry strategy for navigating oil price volatility and maintaining competitiveness in the overseas construction market. Key recommendations include diversifying project locations and supplier bases; utilizing hedging techniques for exchange rate risk management, adapting to local infrastructure and market conditions, establishing local partnerships and securing skilled local labor, implementing technological innovations and digitization at construction sites to enhance productivity and cost reduction The insights gained from this study, coupled with the proposed overseas expansion strategies, offer valuable guidance for mitigating risks in the global construction market and fostering resilience in response to international oil price fluctuations. This approach is expected to strengthen the competitiveness of domestic and foreign construction firms seeking success in the international arena.

• Journal of radiological science and technology
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• v.31 no.1
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• pp.17-23
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• 2008

Purpose : Because there is a difference depending on the environment as for an inspection equipment the important part of bone density scan and the precision/accuracy of a tester, the management of quality must be made systematically. The equipment failure caused by overload effect due to the aged equipment and the increase of a patient was made frequently. Thus, the replacement of equipment and additional purchases of new bonedensity equipment caused a compatibility problem in tracking patients. This study wants to know whether the clinical changes of patient's bonedensity can be accurately and precisely reflected when used it compatiblly like the existing equipment after equipment replacement and expansion. Materials and methods : Two equipments of GE Lunar Prodigy Advance(P1 and P2) and the Phantom HOLOGIC Spine Road(HSP) were used to measure equipment precision. Each device scans 20 times so that precision data was acquired from the phantom(Group 1). The precision of a tester was measured by shooting twice the same patient, every 15 members from each of the target equipment in 120 women(average age 48.78, 20-60 years old)(Group 2). In addition, the measurement of the precision of a tester and the cross-calibration data were made by scanning 20 times in each of the equipment using HSP, based on the data obtained from the management of quality using phantom(ASP) every morning (Group 3). The same patient was shot only once in one equipment alternately to make the measurement of the precision of a tester and the cross-calibration data in 120 women(average age 48.78, 20-60 years old)(Group 4). Results : It is steady equipment according to daily Q.C Data with $0.996\;g/cm^2$, change value(%CV) 0.08. The mean${\pm}$SD and a %CV price are ALP in Group 1(P1 : $1.064{\pm}0.002\;g/cm^2$, $%CV=0.190\;g/cm^2$, P2 : $1.061{\pm}0.003\;g/cm^2$, %CV=0.192). The mean${\pm}$SD and a %CV price are P1 : $1.187{\pm}0.002\;g/cm^2$, $%CV=0.164\;g/cm^2$, P2 : $1.198{\pm}0.002\;g/cm^2$, %CV=0.163 in Group 2. The average error${\pm}$2SD and %CV are P1 - (spine: $0.001{\pm}0.03\;g/cm^2$, %CV=0.94, Femur: $0.001{\pm}0.019\;g/cm^2$, %CV=0.96), P2 - (spine: $0.002{\pm}0.018\;g/cm^2$, %CV=0.55, Femur: $0.001{\pm}0.013\;g/cm^2$, %CV=0.48) in Group 3. The average error${\pm}2SD$, %CV, and r value was spine : $0.006{\pm}0.024\;g/cm^2$, %CV=0.86, r=0.995, Femur: $0{\pm}0.014\;g/cm^2$, %CV=0.54, r=0.998 in Group 4. Conclusion: Both LUNAR ASP CV% and HOLOGIC Spine Phantom are included in the normal range of error of ${\pm}2%$ defined in ISCD. BMD measurement keeps a relatively constant value, so showing excellent repeatability. The Phantom has homogeneous characteristics, but it has limitations to reflect the clinical part including variations in patient's body weight or body fat. As a result, it is believed that quality control using Phantom will be useful to check mis-calibration of the equipment used. A value measured a patient two times with one equipment, and that of double-crossed two equipment are all included within 2SD Value in the Bland - Altman Graph compared results of Group 3 with Group 4. The r value of 0.99 or higher in Linear regression analysis(Regression Analysis) indicated high precision and correlation. Therefore, it revealed that two compatible equipment did not affect in tracking the patients. Regular testing equipment and capabilities of a tester, then appropriate calibration will have to be achieved in order to calculate confidential BMD.

• Journal of Christian Education in Korea
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• v.71
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• pp.305-340
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• 2022

This study was started to suggest the direction of Christian educational development to revitalize North Korea's 'education' research. Since the two Koreas have experienced heterogeneity in almost all elements of society, such as politics, economy, society, culture, and education, during the period of division in 1977, true unification depends on laying the foundation for social integration that can overcome the sense of heterogeneity between the two Koreas. This is why North Korea's "education" research is needed. Education is the foundation for transferring culture and history, and for bringing about the survival, transformation, and community of society and since it is the mission of Korean churches and Christian educators to establish the direction of North Korean "education" research, North Korean "education" research is very important. Despite this importance, 'North Korean research' in the field of Christian education has not been properly conducted. Research on the "Christian Unification Education Program" that can be used in churches is actively taking place, but research on the macro level of presenting post-unification education blueprints is rare. This study was started to suggest the direction of Christian educational development to revitalize North Korea's 'education' research. For the study, the characteristics of 'North Korea Research' were analyzed according to generational classification. As a result of the study, recent research on North Korea has been expanding in research topics and methodologies, and recent studies have been differentiated into microscopic studies that deviate from existing research trends at a macro level and view North Korea's daily life. The characteristics of 'North Korean education research' are summarized by period. The research on North Korean education, which began in earnest in the 1970s, was divided into the period of start(70s), transition(80s), leap(90s), expansion(2000s), and development(2010s~). and research characteristics for each period were analyzed. Through this, early North Korean education research was also conducted in the policy aspect of the country, and the characteristics of political and social studies were strong, but recent studies have confirmed that the subjects and contents are diversifying. Based on these studies, the pending issues and issues of North Korean education research in the field of Christian education were analyzed. The study of North Korea in the field of Christian education, which began in the 1980s, has been conducted in the engineering aspect of 'development of unification education programs for churches'. However, studies on Christian unification education and North Korean education itself, which can be used in public education sites including Christian schools, have yet to be sufficient. Nevertheless, the diversification of research in the field of Christian education can be evaluated as a positive change. Based on these studies, it was proposed to establish a de-ideological research foundation, secure primary research data(Raw Data), activate research topics and research methodologies, and strengthen research capabilities in the direction of development to revitalize North Korean research in the field of Christian education. I hope this study will trigger various follow-up studies and help Korean churches that must achieve unification.

• Journal of the Korean Geographical Society
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• v.30 no.1
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• pp.16-34
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• 1995

This study aims to analyze the impact of cement industry on region change. For this study Maepo-Eub was selected as study area, where three cement factories are located. The data for analysis were obtained from interviews, questionaire surveys and the employee list of each cement factory. The analytic procedures for this study are as follows: 1) The change of regional employment was analyzed by development was industry in terms of the permanent address, education level, occupational status of the employee. 2) The degree of population growth are analyzed by developmental staae of the industry. Some conclusions from this study follows: 1) As these cement factories were built at Maepo in the 1960's, there were plenty of employment opportunities. Thus many technicians and workers flooded in Maepo-Eub. in the 1970's with the expansion of production facilities therewere much more immigrants to the industrial region, while there were outflow in the neighboring rural areas. In the 1980's the opportunity for the employment of cement factories have been decreased due to the introduction of the automation processes and larger, sized machines. Among the employee of three cement factories the native of Chungcheongbukdo (65%; in them Danyang 52%, Jecheon 32%) is dominant, the second is from Kangwon-do (13%), and the third is from Kyungsangbuk-do (11%) adjacent to Chungcheongbuk-do. It means that there are more employment opportunity in the near places of cement factories. 2) In the period of 1960's study area had experineed rapid social increase in population by the development of cement industry. That is, cement industries created new job opportunities and attracted large population concentration into this area. In the period of 1970's the population of the industrial region have increased continuously, while the population of neighboring rural areas have decreased. In the period of 1980's the population of Maepo decreased steadily because of decrease of labour forces through automation and commuting. Thus in the early stage of idustrial development large population concentrated in the neighboring villages of cement factories, and formed residential areas, commercial areas and service areas. As agricultural and was encroached, rural people left their regions to live in the more convenient suburbs. 3) People engaged in cement industry think that cement industry has a favorable influence on regional development, such as creating job opportunity, raising income level, developing business and service sector, and leading high economic growth. While farmers and some people think that cement industries as a pollution causing factories have a harmful influence on regional development, sucha as injuring the crops, causing environmental pollution, and being harmful to health. If pollution problems are solved, I think Maepo will play an important role as a regional center which can offer employment opportunity, business and service function to pheripheral rural areas, and raise a income level.

• IMMUNE NETWORK
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• v.3 no.1
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• pp.1-7
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• 2003

Type II collagen (CII), major component of hyaline cartilage, has been considered as an auto-antigen in rheumatoid arthritis (RA). However, the clinical and biological significances with regard to the CII autoimmunity need to be clarified in human RA. The presence of antibodies to CII has been identified in sera, synovial fluid, and cartilage of patients with RA. In our study, the increased titer of IgG anti-CII in sera was well correlated with C-reactive protein, suggesting that this antibody may reflect the inflammatory status of RA. The titer of anti-CII antibodies (anti-CII Abs) tended to be higher in early stages of diseases. In our extending study, among 997 patients with RA, 269 (27.0%) were positive for circulatory IgG antibody to CII, those levels were fluctuated over time. It is hard to assess the significant amount of T cell responses to CII and CII (255~274) in RA. By using a sensitive method of antigen specific mixed lymphocyte culture, we can detect the presence of CII-reactive T cells in peripheral blood mononuclear cells of RA patients. Sixty seven (46.9%) of 143 patients showed positive CII reactive T cell responses to CII or CII (255~274). The frequencies of CII reactive T cells were more prominent in inflamed synovial fluid (SF) than in peripheral blood. These T cells could be clonally expanded after consecutive stimulation of CII with feeding of autologous irradiated antigen presenting cells (APC). Moreover, the production of Th1-related cytokine, such as IFN-${\gamma}$, was strongly up-regulated by CII reactive T cells. These data suggest that T cells responding to CII, which are probably presenting the IFN-${\gamma}$ producing cells, may play an important role in the perpetuation of inflammatory process in RA. To evaluate the effector function of CII reactive T cells, we investigated the effect of CII reactive T cells and fibroblasts-like synoviocytes (FLS) interaction on the production of pro-inflammatory cytokines. When the CII reactive T cells were co-cultured with FLS, the production of IL-15 and TNF-${\alpha}$ from FLS were significantly increased (2 to 3 fold increase) and this increase was clearly presented in accord to the expansion of CII reactive T cells. In addition, the production of IFN-${\gamma}$ and IL-17, T cell derived cytokines, were also increased by the co-incubation of CII reactive T cells with FLS. We also examined the impact of CII reactive T cells on chemokines production. When FLS were co-cultured with CII stimulated T cells, the production of IL-8, MCP-1, and MIP-1${\alpha}$ were significantly enhanced. The increased production of these chemokines was strongly correlated with increase the frequency of CII reactive T cells. Conclusively, immune response to CII was frequently found in RA. Activated T cells in response to CII contributed to increase the production of proinflammatory cytokines and chemokines, which were critical for inflammatory responses in RA. The interaction of CII-reactive T cells with FLS further augmented this phenomenon. Taken together, our recent studies have suggested that autoimmunity to CII could play a crucial role not only in the initiation but amplification/perpetuation of inflammatory process in human RA.