• Journal of Environmental Science International
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• v.17 no.11
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• pp.1281-1293
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• 2008

This study aims at the estimation of dam failure time and dam failure scenario analysis of and applied to Yeoncheon Dam which was collapsed August 1st 1999, using HEC-HMS, DAMBRK-FLDWAV simulation model. As the result of the rainfall-runoff simulation, the lancet flood amount of the Yeoncheon Dam site was $10,324\;m^3/sec$ and the total outflow was $1,263.90\;million\;m^3$. For the dam failure time estimation, 13 scenarios were assumed including dam failure duration time and starting time, which reviewed to the runoff results. The simulation time was established with 30 minutes intervals between one o'clock to 4 o'clock in the morning on August 1, 1999 for the setup standard for each case of the dam failure time estimation, considering the arrival time of the flood, when the actually measured water level was sharply raising at Jeongok station area of the Yeoncheon Dam downstream, As results, dam failure arrival time could be estimated at 02:45 a.m., August 1st 1999 and duration time could be also 30 minutes. Those results and procedure could suggest how and when dam failure occurs and analyzes.

• Journal of Environmental Science International
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• v.17 no.11
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• pp.1295-1305
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• 2008

This study aims at the analyze of unsteady downstream flow due to dam failure along dam failure scenario and applied to Yeoncheon Dam which was collapsed August 1st 1999, using HEC-RAS simulation model. The boundary conditions of this unsteady flow simulation are that dam failure arrival time could be at 02:45 a.m. August 1st 1999 and failure duration time could be also 30 minutes. Downstream 19.5 km from dam site was simulated for unsteady flow analysis in terms of dam failure and non-failure cases. For the parameter calibration, observed data of Jeonkok station were used and roughness coefficient was applied to simulation model. The result of the peak discharge difference was 2,696 to $1,745\;m^3/sec$ along the downstream between dam failure and non-failure and also peak elevation of water level showed meanly 0.6m difference. Those results of these studies show that dam failure scenarios for the unknown failure time and duration were rational because most results were coincident with observed records. And also those results and procedure could suggest how and when dam failure occurs and downstream unsteady flow analyzes.

• Journal of Forest and Environmental Science
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• v.30 no.1
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• pp.76-84
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• 2014

This study was performed to monitor the effects of water level change on changes of landscape, vegetation community, and species diversity of riparian forest. Hantan river dam, study area, has been constructed in the area of Chansoo-myeon, Pocheon-si and Yeoncheon-eup, Yeoncheon-gun, Gyeonggi-do, which is a dam for flood control only in flooding season. Landscape changes were notable after the construction of coffer dam, and the changes were caused by water level increase in areas of riparian forests which consisted of mainly withered willow as a dominant species in the flooding season. It changed vegetation communities of riparian forest from Phragmites japonica and Salix koreensis to Phragmites japonica. Species diversity index was lowest in 2010 when the coffer dam was constructed and showed an increasing trend later. Thus, this study is well in agreement with a previous report that plants of the genus Salix wither by muddy water during flooding and also suggests, controlling water level of river and prediction of water level change's effects should be considered when any facilities are planned.

• Journal of Environmental Science International
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• v.20 no.12
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• pp.1635-1646
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• 2011

This April 5th dam and Hwanggang dam, which are located in Imjin river, North Korea, become the main causes of water shortages and damages in Imjin river downstream. April 5th dam is assumed a small or medium-sized dam, its total storage volume reaches about 88 million $m^3$. And Hwanggang dam, multi-purposed dam of total storage volume approximately 0.3 billion $m^3$ to 0.4 billion $m^3$ is used as source of residental or industrial water in Gaeseong Industrial Complex. North Korea, which has April 5th dam and Hwanggang dam in Imjin river, manages water of approximately 0.39 billion $m^3$ to 0.49 billion $m^3$ directly. As water is storaged or discharged through dam, it causes a severe damage to areas in Yeoncheon-gun and Paju city, South Korea. Therefore, this study intends to analyze and estimate runoff through dam construction by using hydrological observation data and artificial data such as service water supply and agricultural water in Imjin river, water shortage and damage correctly.

• Journal of the Earthquake Engineering Society of Korea
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• v.18 no.6
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• pp.271-278
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• 2014

Seismic intensity deduced from instrumental data has been evaluated using the empirical relationship between intensity and peak ground acceleration (PGA) during an earthquake. The Japan Meteorological Agency (JMA) developed a seismic intensity meter, which can estimate the real-time seismic intensity from seismic motions observed at a local site to evaluate the damage during the earthquake more correctly. This paper proposes a practical application of the JMA intensity to dams during the 2013 earthquake in Yeongcheon, Korea. In the present paper, seismic intensity was estimated from the relationships between accelerations observed at Yeongcheon Dam. Estimated seismic intensities were in the range of 0 to 3, which was verified from the displacements of dams and the variation of the ground water level observed at Yeongcheon dam during the earthquake. The JMA intensity, which is determined by considering the frequency, duration of cyclic loading, etc., was 0 (zero) and there was no damage to Yeoncheon dam during the earthquake.

• Korean Journal of Remote Sensing
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• v.34 no.6_1
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• pp.1033-1039
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• 2018

In Korea, every year during the summer season, typhoons and torrential rains cause floods and damage to property. In particular, the Imjin River basin is characterized by steep slopes, narrow upstream areas, and low flat downstream areas, which are vulnerable to floods. In addition, damages occurred due to unauthorized discharge in the Hwanggang Dam, a large dam upstream of the Imjin River in North Korea. In order to prevent such flood damage, Korea is constructing the Gunnam Flood Control Site in 2010 to prevent flood damage. However, even after the construction of the flood control zone, the flood control capacity is only 20% of the maximum water level of the Hwanggang dam. This study used LAHARZ_py program to calculate flood damage area in the northern part of Gyeonggi province. As a result, when the discharge of Hwanggang dam exceeding the flood control ability of Gunnam flood control zone occurs, damage to Yeoncheon-gun and Paju-si of Gyeonggi-do was expected. This study will be useful as a material to prepare for flood damage.

• Korean Journal of Plant Taxonomy
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• v.45 no.4
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• pp.362-368
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• 2015

Two new and one unrecorded hybrids of the genus Asplenium were newly found in Korea. They were proved to be hybrid based on intermediate morphology between putative parents. The first hybrid is $A.{\times}uiryeongse$ C.S. Lee & K. Lee (Aspleniaceae), nom. nov. (vernacular name: geo-mi-sa-cheol-go-sa-ri). This new hydrid is a cross between the Asian walking fern, A. ruprechtii and A. pekinens in Uiryeong-gil, Mt. Bukansan, Seoul, Korea. The other new one occurs in Mt. Seongsan in Yeoncheon-gun, Gyeonggi-do, Korea, $A.{\times}montanus$ C.S. Lee & K. Lee, nom. nov. (vernacular name: san-kko-ri-go-sa-ri) which might have experienced multiple hybridization events between A. ruprechtii ${\times}$ A. trichomanes and A. incisum following the hybrid between A. ruprechtii and A. trichomanes. In addition, one unrecorded hybrid, $A.{\times}kitazawae$ Kurata & Hutoh (vernacular name: geo-mi-dol-dam-go-sa-ri), reported first from Japan, is found in natural habitats in Do-dong, Daegu-si, and is a hybrid, between the Asian walking fern and A. sarelli. These hybrid taxa grow in sympatric regions with both putative parental species. The diagnostic characters for each taxon and evidence for their hybridization have been suggested. Descriptions, illustrations, and photographs of these hybrid taxa in their habitats are provided from Korea.