• Proceedings of the Korea Water Resources Association Conference
• /
• 2018.05a
• /
• pp.39-39
• /
• 2018

우리나라는 전체 국토의 약 70%가 산악지형으로 이루어져 있고 연중 강우가 6월에서 9월에 집중되는 기후적 특성을 가지고 있다. 최근 기후변화의 영향까지 더해지면서 시간당 300mm 이상의 집중호우를 보이는 이상강우가 빈번하게 발생하고 있다. 대부분의 도시지역은 하천을 중심으로 발달되어 있어 인구 및 사회기반시설의 집약정도가 매우 높고 하천변 저지대 지역에 주거 및 상업시설이 밀집되어 있다. 기후적 지역적 특성으로 인한 홍수피해를 미연에 방지하고 피해를 최소화하기 위하여 치수 중심의 수자원 관리를 위해 노력하고 있다. 하지만 우리나라의 하천관리는 시기별 하천 수량의 급격한 변동으로 어려움을 겪고 있다. 이러한 어려움을 극복하고 효율적인 수자원 관리 및 홍수피해 저감을 위해 수계를 중심으로 20개의 다목적댐을 건설하여 운영 관리 중에 있다. 특히, 홍수기 시 댐 운영은 예상 강우에 따라 적절한 예비방류와 강우 시 효율적인 댐 운영계획이 필수적이다. 본 연구에서는 강우가 집중되는 홍수기 댐 운영 시에 예상 강우량에 따라 댐 유역 내 유량 증가에 기여하는 정도를 예측할 수 있는 유출율 예측 회귀식을 개발하였다. 유출율은 강우와 유출량의 비로 지역특성, 강우특성, 관개여부, 선행강우량, 강우이동 방향 등 다양한 요인에 의해 복잡한 메케니즘을 갖는다. 단순히 예상되는 총강우량에 따른 유출율 만으로 상호관계를 정의하기가 쉽지 않기 때문에 한국수자원공사에서 개발한 댐군 홍수조절 연계운영시스템(COSFIM)인 수문학적 연계운영모형을 활용하였다. 최근 10년간 홍수기에 발생한 강우사상별 시간단위의 수문자료(총강우량, 기저유량, 유출율, 무강우일수, 강우지속시간 등) 분석을 실시하였다. COSFIM 모형을 통한 결과를 토대로 고려항목 간 교차검증을 통해 사분위수범위의 이상치 경계를 설정하고 상관분석 결과에 따라 0.5 이상의 상관성이 높은 항목을 활용하여 예측 강우량에 따른 유출율 예측 회귀식을 도출하였다. 본 연구에서 개발한 예측 강우에 따른 유출율 예측 산정식은 댐 유역에 예상되는 강우량에 대하여 하천의 유량 증가 예측 정도를 정량적으로 제시할 수 있으며, 실제 홍수기 댐 운영 시 예상 강우량에 따라 신속하고 적절한 수문 방류 계획 수립에서 용이하게 활용할 수 있을 것으로 기대한다.

• Journal of Korea Water Resources Association
• /
• v.51 no.12
• /
• pp.1247-1260
• /
• 2018

This study investigated the effect of arctic oscillation by analyzing the cross-correlation characteristics between the arctic oscillation index (AOI) and the number of typhoons occurred in the North Pacific, the number of typhoons affecting South Korea, total rainfall amount and number of rainy days during the monsoon season in South Korea. For this analysis, the monthly AOI data were transformed into the average data about January and seasonal AOI data representing winter, spring, fall and winter. The typhoon data and monsoon data were all those collected annually. The data period for this analysis was determined to be from 1961 to 2016 by considering the data available. Based on this analysis, it was found that the arctic oscillation has a weak but statistically significant effect on the monsoon characteristics of South Korea. However, the level of effect was not consistent over the data period but varied significantly periodically. For example, the cross-correlation coefficient derived for the recent 10 years was estimated to be higher than 0.8, but was simply insignificant during the 30 years before the last decade. The overall effect of arctic oscillation on the occurrence of typhoon was found to be statistically insignificant, but was also fluctuating periodically to show somewhat significant effect. Finally, it should be mentioned that the effect of arctic oscillation on the typhoon and monsoon had been changing by turns from 1960s to 2000s. However, in the 2010s, it happened that the effect of arctic oscillation has become significant on both typhoon and monsoon in South Korea.

• Journal of Cadastre & Land InformatiX
• /
• v.48 no.2
• /
• pp.137-151
• /
• 2018

Recently, National interest has been rising due to earthquakes in Gyeongju and Pohang, disasters caused by landslides, landslides, and sinkholes around construction sites, and damage caused by disasters. SAR is able to detect ground displacement in mm for wide area, collect data through satellite, predict timeliness of crustal change by time series analysis, and reduce disaster and disaster damage. The purpose of this study is to investigate the latest SAR interference analysis technique (SqueeSAR analysis technique) of Sentinel-1A satellite (SAR sensor) of European ESA for about 3 years by selecting the 1st landfill site in the metropolitan area in Incheon, The settlement amount was calculated in a time series. Especially, in order to examine the accuracy of the subsidence and subsidence tendency by the SqueeSAR analysis method, the ground level survey was compared and analyzed for the first time in Korea. Also, the tendency of the subsidence trend was predicted by analyzing the time series and correlation trend of the subsidence for three years. Through this study, it is expected that disaster prevention and disaster prevention such as sinkhole and landslide can be utilized from time series monitoring of crustal variation of the land.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.46 no.6
• /
• pp.1-16
• /
• 2018

The decline in the construction industry has led to a decrease the profitability of small and medium-sized landscape contractors. To relieve this situation, small and medium-sized landscape contractors have continued to proactively find ways to enter global construction markets. However, many small and medium-sized landscape contractors face risks due to their lack of capacity and insufficient preparations to extend the business abroad. Thus, this study aims to analyze the current condition of the Vietnamese construction market and the related risk factors. It then suggests strategies to improve the small and medium-sized landscape contractors' competitiveness in that market. We investigated the business climate and analyzed risk factors. Finally, we developed expansion strategies and conducted in-depth interviews with six overseas construction professionals. The study results first showed that efforts to improve infrastructure and the increased demand for housing in Vietnam will lead to more opportunities for small and medium-sized landscape contractors entering the Vietnamese construction market. However, changes in the Vietnamese business climate may act as a variable. Second, we found that small and medium-sized landscape contractors' risk factors are mainly related to laws and regulations, government finance, market fluctuations, public administration system, minimum wage increases, financing and bonds, contracting, trees and materials, and design errors. Finally, small and medium-sized landscape contractors are required to consider the following when seeking to enter the Vietnamese construction market: short-term strategy and mid-to-long-term strategy. This study will be used as the basis for small and medium-sized landscape contractors to plan to enter the Vietnamese construction market and to contribute to the expansion of the global construction market in the landscape industry.

• Journal of Korea Water Resources Association
• /
• v.54 no.3
• /
• pp.181-190
• /
• 2021

In this study, a large-scale levee breach experiment from lateral overflow was conducted to verify the effect of the new reinforcement method applied to the levee's surface. The new method could prevent levee failure and minimize damage caused by overflow in rivers. The levee was designed at the height of 2.5 m, a length of 12 m, and a slope of 1:2. A new material mixed with biopolymer powder, water, weathered granite, and loess in an appropriate ratio was sprayed on the levee body's surface at a thickness of about 5 cm, and vegetation recruitment was also monitored. At the Andong River Experiment Center, a flow (4 ㎥/s) was introduced from the upstream of the A3 channel to induce the lateral overflow. The change of lateral overflow was measured using an acoustic doppler current profiler in the upstream and downstream. Additionally, cameras and drones were used to analyze the process of the levee breach. Also, a new method using 3D point cloud for calculating the surface loss rate of the levee over time was suggested to evaluate the performance of the levee reinforcement method. It was compared to existing method based on image analysis and the result was reasonable. The proposed 3D point cloud methodology could be a solution for evaluating the performance of levee reinforcement methods.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.23 no.4
• /
• pp.391-404
• /
• 2021

This study developed a long-term prediction model for the potential yield of garlic based on a genetic algorithm (GA) by utilizing global climate reanalysis data. The GA is used for digging the inherent signals from global climate reanalysis data which are both directly and indirectly connected with the garlic yield potential. Our results indicate that both deterministic and probabilistic forecasts reasonably capture the inter-annual variability of crop yields with temporal correlation coefficients significant at 99% confidence level and superior categorical forecast skill with a hit rate of 93.3% for 2 × 2 and 73.3% for 3 × 3 contingency tables. Furthermore, the GA method, which considers linear and non-linear relationships between predictors and predictands, shows superiority of forecast skill in terms of both stability and skill scores compared with linear method. Since our result can predict the potential yield before the start of farming, it is expected to help establish a long-term plan to stabilize the demand and price of agricultural products and prepare countermeasures for possible problems in advance.

• The Journal of the Korea Contents Association
• /
• v.22 no.2
• /
• pp.529-544
• /
• 2022

With the global pandemic in the era of the 4th industrial revolution, the business environment of companies was engulfed by rapid volatility and uncertainty. In particular, in order for an organization to have high competitiveness due to the spread of the flexible work system, relationship management with members of the organization and self-directed job crafting are recognized as important key resources. This study aims to investigate how relational energy and resilience within a corporate organization affect job crafting and to verify the effect of job crafting on individual job performance. For empirical research, 400 valid responses to employees of general companies were analyzed by SPSS 26.0 and Smart PLS 3.0. As a result of the analysis, first, it was confirmed that relational energy did not have a positive (+) effect on task crafting. Second, it was found that relational energy had a positive (+) effect on relational crafting and cognitive crafting, respectively. Third, it was found that resilience had a positive (+) effect on both task crafting, relationship crafting, and cognitive crafting that constitute job crafting. Fourth, it was found that job crafting had a positive (+) effect on individual job performance. Based on these research results, we intend to derive academic and practical implications and provide practical help to follow-up researchers and stakeholders.

• Journal of Korea Port Economic Association
• /
• v.39 no.1
• /
• pp.115-129
• /
• 2023

This study analyzed the risk spillover of BDI on shipping company stock prices through the Copula-CoVaR method based on daily data from January 4, 2010, to October 31, 2022. The main empirical analysis results and policy implications are as follows. First, copula results showed that there was a weak dependence between BDI and shipping company stock prices, and PAN, KOR, and YEN were selected as the most fitting model for dynamic Student-t copula, HMM was selected as the rotated Gumbel copula, and KSS was selected as the best model. Second, in the results of CoVaR, it was confirmed that the upside (downside) CoVaR was significantly different from the upside (downside) VaR in all shipping companies. This means that BDI has a significant risk spillover on shipping companies. In addition, as for the risk spillover, the downside risk is generally lower than the upside risk, so the downside and upside risk spillover were found to be asymmetrical. Therefore, policymakers should strengthen external risk supervision and establish differentiated policies suitable for domestic conditions to prevent systematic risks from BDI shocks. And investors should reflect external risks from BDI fluctuations in their investment decisions and construct optimal investment portfolios to avoid risks. On the other hand, investors propose that the investment portfolio should be adjusted in consideration of the asymmetric characteristics of up and down risks when making investment decisions.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.21 no.1
• /
• pp.209-220
• /
• 2022

With the worldwide spread of African swine fever, interest in livestock epidemics has increased. Livestock transport vehicles are the main cause of the spread of livestock epidemics, but there are no empirical quarantine procedures and standards related to the mobility of livestock transport vehicles in South Korea. This study extracted the trajectory of livestock-related vehicles using the facility-visit history data from the Korea Animal Health Integrated System and the DTG (Digital Tachograph) data from the Korea Transportation Safety Authority. The results are presented as exposure indices aggregating the link-time occupancy of each vehicle. As a result, 274,519 livestock-related vehicle trajectories were extracted, and the exposure values by link and zone were derived quantitatively. This study highlights the need for prior monitoring of livestock transport vehicles and the establishment of post-disaster prevention policies.

• Korea Trade Review
• /
• v.43 no.5
• /
• pp.47-66
• /
• 2018

This study analyzes the potential economic effects of a trade war between the U.S. and China. The CGE model is used to estimate the macroeconomic variables of each country and the change in imports/exports by industry by considering three different scenarios: (i) the US imposes a 25% of tariff on China; (ii) the US and China impose a 25% tariff bilaterally; (iii) the United States expands protection in vehicles and metals to Korea, Japan, and the EU. According to the results of the study, when the US and China initiate a trade war, GDP and welfare of both countries decline. China's decline in GDP and welfare are larger than those of the United States, which implies a trade war is more favorable to the U.S. than to China. In the long run, China's GDP and welfare decline widens further. While the trade volumes of the US and China are greatly reduced, the trade volumes of other countries does not significantly fluctuate. Finally, if the US extends protection policy to Korea, Japan and the EU, it creates undesirable effects on the US. In particular, damage to the US jeopardizes its advantageous position in a trade war with China. In order to emphasize the unfairness of protectionist policy and the damage to Korean industry, Korea needs to establish a strategy to counter US protectionist policy.