• Tunnel and Underground Space
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• v.33 no.2
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• pp.95-107
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• 2023

In this study, the effect of repeated traffic vibration on the long-term stability of mine openings is analyzed for re-utilization of abandoned mine galleries. The research mine in this study is an underground limestone mine which is developed by room-and-pillar mining method, and a dynamic numerical analysis is performed assuming that the research mine will be utilized as a logistics warehouse. The actual traffic vibration generated by the mining vehicles is measured directly, and its waveform is used as input data for dynamic numerical analysis, As a results of dynamic numerical analysis, after 20,000 repetitions of traffic vibration, the mine openings is analyzed to be stable, but an increase in the maximum principal stress and an additional area of plastic zone are observed in the analysis section. As shown in the changes of displacement, volumetric strain, and maximum principal stress which are measured at the mine opening walls. It is confirmed that if the repeated traffic vibration is continuously applied, the instability of the mine openings can be increased. Authors expect that the results of this study can be used as a reference for basic study on utilization of abandoned mine.

• Journal of Wetlands Research
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• v.25 no.2
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• pp.111-120
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• 2023

In Korea, wetland policies are currently being pursued through long-term plans such as nationwide wetland surveys and wetland conservation basic plans. However, most policies focus on understanding the status of wetlands, such as their area, distribution, and biodiversity, and there is a lack of awareness regarding the need to conserve and manage wetland ecosystems as a single organism. Therefore, this study aims to identify potential riverine wetland sites that can be ecologically connected by considering functional aspects such as floodplain, biodiversity, habitat provision, and tourism resources. This study attempted to select a candidate site that could potentially provide ecological connectivity with three wetlands in the Nakdonggang River water system : Upo Wetland, Hwapocheon Wetland, and Junam Reservoir. 63 wetlands and 7 candidate sites located in 15 subwatersheds of the Nakdonggang River were analyzed, and the most suitable candidate site for ecological connectivity was selected based on the calculated scores. A suitability analysis was conducted using 9 evaluation factors to evaluate candidate sites, and the scoring method, using quantile, was applied to these factors. As a result, Upo2(Hopo) was selected as the most suitable site for ecological connectivity, receiving the highest score 36. Therefore, it is believed that Upo2(Hopo) can serve as a floodplain, habitat, biodiversity enhancer, and tourism resource while being the most suitable for ecological connectivity.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.3
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• pp.321-335
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• 2023

Monitoring sediment loads in natural rivers is the key process in river engineering, but it is costly and dangerous. In practice, suspended loads are directly measured, and total loads, which is a summation of suspended loads and bed loads, are estimated. This study proposes a real-time sediment discharge monitoring system using the horizontal acoustic Doppler current profiler (H-ADCP) and support vector regression (SVR). The proposed system is comprised of the SVR model for suspended sediment concentration (SVR-SSC) and for total loads (SVR-Q_TL), respectively. SVR-SSC estimates SSC and SVR-Q_TL mimics the modified Einstein procedure. The grid search with K-fold cross validation (Grid-CV) and the recursive feature elimination (RFE) were employed to determine SVR's hyperparameters and input variables. The two SVR models showed reasonable cross-validation scores (R²) with 0.885 (SVR-SSC) and 0.860 (SVR-Q_TL). During the time-series sediment load monitoring period, we successfully detected various sediment transport phenomena in natural streams, such as hysteresis loops and sensitive sediment fluctuations. The newly proposed sediment monitoring system depends only on the gauged features by H-ADCP without additional assumptions in hydraulic variables (e.g., friction slope and suspended sediment size distribution). This method can be applied to any ADCP-installed discharge monitoring station economically and is expected to enhance temporal resolution in sediment monitoring.

• Journal of Appropriate Technology
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• v.5 no.2
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• pp.106-113
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• 2019

In order to respond to the global environmental issues, developed countries have been helped the developing countries as the Official Development Assistance (ODA). It is important to understand technology needs of the developing countries to provide the optimum solutions. In this study, the information of the environmental R&D dealing with appropriate technology were comprehensively collected based on the conducted R&D projects from the ministry of environment in Korea. The technology needs by UNFCCC (United Nations Framework Convention on Climate Change) and Korean government were analyzed named as TNA and CPS according to the target developing countries. In South-East Asia and Africa region, there were technology needs on water, biota, air, solid wastes, infrastructures and resources. And they were related to the issues such as environmental pollution, construction, climate change, biodiversity, energy and water management. The technology needs by UNFCCC and Korean government were also compared. Furthermore, the environmental R&D on appropriate technology should be focused on localization and maintenance to provide sustainable solutions to the developing countries.

• Ecology and Resilient Infrastructure
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• v.10 no.2
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• pp.31-39
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• 2023

NNbF is a newly emerging approach to reduce flood risk in coastal and fluvial areas using natural features or engineered nature-based features with the expectation of co-benefits of provisional, regulating, and socio-cultural services provided by the ecosystem. NNbF is not quite different from existing, related terms based on nature, such as NbS, Eco-DRR, NI, GI, EwN, and BwN, for all these terms include expectation of benefits for human societies by directly utilizing or mimicking nature's ecological functions. If we focus on the comprehensiveness of each term's subject and object, we can say that NbS > NNbF > (Eco-DRR, NI/GI). Among the 18 measures introduced in the NNbF International Guideline in the river and floodplain management category, it was found that measures of wash lands and floodplain restoration, including levee setback/removal and side-channel restoration, seemed to be the most applicable to rivers in Korea. These selected measures could be more effective when river managers purchase riparian lands along river courses by relevant laws for river water-quality protection.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.3
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• pp.131-146
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• 2023

Smart card data is widely used in the public transportation field. Despite the inevitability of various errors occur during the data collection and storage; however, smart card data errors have not been extensively studied. This paper investigates inherent errors in boarding and alighting station information in smart card data. A comparison smart card data and bus boarding and alighting survey data for the same time frame shows that boarding station names differ by 6.2% between the two data sets. This indicates that the error rate of smart card data is 6.2% in terms of boarding station information, given that bus boarding and alighting survey data can be considered as ground truth. This paper propose 6-step algorithm for correcting errors in smart card boarding station information, linking them to corresponding information in Bus Information System(BIS) Data. Comparing BIS data and bus boarding and alighting survey data for the same time frame reveals that boarding station names correspond by 98.3% between the two data sets, indicating that BIS data can be used as reliable reference for ground truth. To evaluate its performance, applying the 6-step algorithm proposed in this paper to smart card data set shows that the error rate of boarding station information is reduced from 6.2% to 1.0%, resulting in a 5.2%p improvement in the accuracy of smart card data. It is expected that the proposed algorithm will enhance the process of adjusting bus routes and making decisions related to public transportation infrastructure investments.

• Journal of the Korea Society of Computer and Information
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• v.28 no.4
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• pp.121-131
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• 2023

The Chinese three northeastern three provinces - Heilongjiang, Liaoning, and Jilin - hold significant geographical, geopolitical, and commercial importance due to their location allowing for cross-border trade and transportation with North Korea. These provinces are crucial for establishing a complex Eurasian logistics network in line with South Korea's new northern policy. The Chinese three northeastern three provinces, as this region is known, boasts excellent maritime transportation links between South Korea, China, and North Korea, making it an logistics hub for transporting goods to Eurasia and Europe through multimodal transport. This study highlights the importance of securing a logistics hub area by fostering cooperation and friendly relations with China's three northeastern three provinces, which are crucial to the success of the New Northern Policy. In particular, the study aims to analyze current status of trade with these region and freight volume transported by ships and recommend political advice for securing logistics hub and revitalizing maritime transport. As the policy suggestion, this study is to establish a logistics hub by implementing joint port operations, constructing port infrastructure jointly, and operating shipping companies together. Additionally, we propose ways to revitalize the maritime passenger transport business between Korea and China, which involves expanding cultural exchanges and developing content.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.1
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• pp.240-257
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• 2022

Autonomous vehicles use various local sensors such as camera, radar, and lidar to perceive the surrounding environment. However, it is difficult to predict the movement of vulnerable road users using only local sensors that are subject to limits in cognitive range. This is true especially when these users are blocked from view by obstacles. Hence, this paper developed an algorithm for collision avoidance with VRU using V2X information. The main purpose of this collision avoidance system is to overcome the limitations of the local sensors. The algorithm first evaluates the risk of collision, based on the current driving condition and the V2X information of the VRU. Subsequently, the algorithm takes one of four evasive actions; steering, braking, steering after braking, and braking after steering. A simulation was performed under various conditions. The results of the simulation confirmed that the algorithm could significantly improve the performance of the collision avoidance system while securing vehicle stability during evasive maneuvers.

• 한국노년학
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• v.31 no.4
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• pp.1047-1065
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• 2011

The main purpose of this study is to provide the sustainability and continuous development of Long-term care Insurance in projecting changes of the Long-term care Insurance beneficiary population and Cost. We conducted a transformed cohort-component projection method that are employed for the beneficiary population projection and applied the previous experiences in Japan and German. A transformed cohort-component method means that we also projected the increasing beneficiary of long-term care insurance for using the data of geriatric disease in NHIC and estimated the cost of insurance's financial resources. First of all, beneficiary increase and strategy of extending to level 4 are categorized 2 and the expense account projection are categorized 2. If it is thought experience of Japan and German, The Level 4 extend of insuree is projected 2012 or 2013. With the results of this study, we proposed that extended level 4 insuree include the 40%~90% of geriatric disease in elderly people. The number of beneficiaries in 2011 is expected to reach to about 342,896 and in 2015 is 415,905 on scenario 1. Scenario 2(40%of geriatric disease in elderly people), the number of beneficiaries in 2011 is 342,896 and in 2015 is 483,453. Scenario 3(90%of geriatric disease in elderly people), the number of beneficiaries in 2012 is 545,068 and in 2015 is 565,565. The cost of beneficiaries insurance benefit of scenario 1 are projected from 3,000billion in 2012 to 3,500billion won in 2015. Scenario 2 are projected from 3,100billion in 2012 to 4,000billion won 2015. Finally, The cost of Level 4 extending are need minimum 300billion to maximum 1,400billion won.

• Journal of the Korean Society of International Agriculture
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• v.23 no.5
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• pp.513-519
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• 2011

In recent, the cultivation of maize in the world is being increased as a feed for the animal due to the increase of the large amount of meat consumption. However, reduction of supply for the feeding maize by the natural disaster such as drought, flooding, and demanding materials for bioenergy are attributed to increase the cereal price of the world that caused for the fluctuation of prices. The research has been done to provide useful information to the Korean agricultural investor regarding the current status of maize production and distribution in Cambodia. The maize cultivation of Cambodia in 2009 presented as a second major crop at the area of 6.8% in the total crop production area, and it continuously increased maize production yearly basis for the internal uses as well as for the exportation. The total amount of production showed by amount of 0.92 million tons due to the increased production of unit area. The yield production of unit area in current shows about 4 tones per hectare. About 90% of total production produced during August to September at wet season, and area of Batambang province produced about 70% of the total production. The production of feeding maize cultivated about 70% of the total cultivation area, and the exportation have done around 60% and remains were consumed as a domestic uses. The prospects of maize production in Cambodia will be increased due to the acceleration of livestock industry as 8.7% of annual growth rate.