• Korean Journal of Environment and Ecology
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• v.34 no.1
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• pp.42-54
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• 2020

This study aimed to analyze the rate of increase and spread patterns of dead trees of the conifer (Abies koreana and others) in subalpine zones by using the high-resolution aerial images in Jirisan National Park around 10 years ago. Furthermore, factors affecting the death of conifer were identified by analyzing the altitude, topographical information, solar radiation, and moisture environment of the site where the dead trees are located. The number of dead trees per unit area increased by two to five times in the Banyabong peak, Yeongsinbong peak, and Cheonwangbong peak in Jirisan National Park over the past decade. The increase was about 2 times in the Banyabong peak, about 3.9 times in the Yeongsinbong peak, and about 5.2 times in the Cheonwangbong peak, indicating the most notable increase in the Cheonwangbong peak. It is estimated that dead trees commonly occurred in the environments where the soil moisture content was low due to the high slope, amount of evaporation was high due to strong solar radiation as the location faced south, and the soil was dry due to strong solar radiation and short rain retention time. In other words, dead conifer trees in subalpine zones were concentrated in dry location environments, and the tendency was the same more than ten years ago.

• Korean Journal of Remote Sensing
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• v.30 no.6
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• pp.809-816
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• 2014

Ocean Color products have been used to understand marine ecosystem. In high latitude region, ice melting optically influences the ocean color products. In this study, we assessed optical properties in fjord around Svalbard Arctic sea, and estimated distribution of chlorophyll-a and suspended sediment by using high resolution satellite data, Landsat-8 Operational Land Imager (OLI). To estimate chlorophyll-a and suspended sediment concentrations, various regression models were tested with different band ratio. The regression models were not shown high correlation because of temporal difference between satellite data and in-situ data. However, model-derived distribution of ocean color products from OLI showed a possibility that fjord and coastal areas around Arctic Sea can be monitored with high resolution satellite data. To understand climate change pattern around Arctic Sea, we need to understand ice meting influences on marine ecosystem change. Results of this study will be used to high resolution monitoring of ice melting and its influences on the marine ecosystem change at high latitude. KOPRI (Korea Polar Research Institute) has been operated the Dasan station on Svalbard since 2002, and study was conducted using Arctic station.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.1
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• pp.181-190
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• 2016

Improvements in disaster management has become a global necessity because the magnitude of disasters is intensifying in parallel with the increased disaster damage. The disaster risk in Korea is also increasing due to the emergence of new types of disaster; such as the Middle East respiratory syndrome coronavirus, the increase of complex disasters, and the heightened probability of a catastrophic event due to climate change. This paper aimed to identify the disaster loss-frequency relationship from 1948 to 2014 in Korea by using four types of variables. In addition, this paper found major disasters that resulted in the reformation of disaster response organizations, and inputted the deaths and economic loss attributed to those disasters into the disaster loss-frequency graph. The research result substantiated that the disaster loss-frequency relationship in Korea follows the Power Law and found the coefficients of each Power Function. Additionally, this paper found that most of the reformations of disaster response organizations happened after major disasters that concentrated societies attention and anger due to the high human and economic impact; such events are labelled as "focusing events." These focusing events, with the characteristics of a low probability and high impact, are located in the long tail of the Power Law Distribution. This paper suggests that the effective public policy for disaster response needs to be developed by paying attention to 'low probability and high impact' focusing events that are located in the long tail of the Power Law Distribution.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.1
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• pp.89-102
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• 2010

Future uncertainty on water demand caused by future climate condition and water consumption leads a difficulty to determine the reservoir operation rule for supplying sufficient water to users. It is, thus, important to operate reservoirs not only for distributing enough water to users using the limited water resources but also for preventing floods and drought under the unknown future condition. In this study, the reservoir storage is determined in the first stage when future condition is unknown, and then, water distribution to users and river stream is optimized using the available water resources from the first stage decision using 2-stage stochastic linear programming (2-SLP). The objective function is to minimize the difference between target and actual water storage in reservoirs and the water shortage in users and river stream. Hedging rule defined by a precaution against severe drought by restricting outflow when reservoir storage decreases below a target, is also applied in the reservoir operation rule for improving the model applicability to the real system. The developed model is applied in a system with five reservoirs in the Han River basin, Korea to optimize the multi-reservoir system under various future water demand scenarios. Three multi-purposed dams - Chungju, Hoengseong, and Soyanggang - are considered in the model. Gwangdong and Hwacheon dams are also considered in the system due to the large capacity of the reservoirs, but they are primarily for water supply and power generation, respectively. As a result, the water demand of users and river stream are satisfied in most cases. The reservoirs are operated successfully to store enough water during the wet season for preparing the coming drought and also for reducing downstream flood risk. The developed model can provide an effective guideline of multi-reservoir operation rules in the basin.

• Journal of Korea Water Resources Association
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• v.51 no.3
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• pp.195-205
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• 2018

Drought is a complex phenomenon caused by various factors which can be classified into natural and anthropogenic causes. In Korea, the natural drought typically occurs when the high pressure of the Pacific Ocean develops rapidly or becomes stronger than usual in summer, resulting in a short-lived monsoon season. Drought also can be classified into meteorological, agricultural, hydrological, and socioeconomic drought depending on the development process and consequences. Each type of droughts can influence the other drought types directly or indirectly. Drought propagation refers a phenomenon that changes from meteorological drought to agricultural or hydrological drought. In this study, the occurrence and patterns of drought propagation are evaluated. The relationship between meteorological and agricultural droughts was assessed using hydrometeorological data. We classified the types of drought into five categories to evaluate the occurrence and characteristics of drought propagation. As results, we found drought propagation did not occur or delayed until three months, depending on the type of drought. The further generalized relationship of drought propagation is expected to be used for predicting agricultural drought from the preceding meteorological drought.

• Spatial Information Research
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• v.20 no.1
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• pp.71-80
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• 2012

Carbon Point system is Climate Change Action Program by providing incentives in proportion to voluntary reduction of energy consumption such as electricity, gas and water for houses, commercial facilities. So far, existing researches have been limited to construction of GHG(Green House Gas) Inventory and have little attention to empirical impact analysis on carbon reduction policy regarding the residential section. Therefore, this paper is intended to provide convincing findings of impact analysis on carbon reduction, revolving around the carbon point system. For this, we firstly calculated the carbon emission by using electricity and gas usage data in household targeting to Seongbuk-Gu. Carrying out IPA and spatio-temporal analysis. Then, we are capable of visualizing spatial patterns from 2007 to 2009 as a macro analysis. Following that, we explored the effect on carbon point system through Ex ante-Ex post Analysis by paired t-test. To conclude, we can spatially identify the distribution with a significant difference between carbon emissions according to energy use as a micro analysis by Hot Spot to Analysis on point entities. It is to be hoped that this method will be utilized to establish various policies and to evaluate the effect of reduction of GHG.

• Korean Journal of Ecology and Environment
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• v.36 no.3 s.104
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• pp.242-256
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• 2003

This study aimed to determine the relationship between rainfall-discharge patterns and maior aquatic environmental factors in a river-type reservoir. Specifically, daily monitoring was conducted in Paltang Reservoir from January 1999 to December 2001. Observation of the daily changes of the environment factors showed that natural meteorological factors and hydrological factors causing the change of water discharge had a major effect on the aquatic environment. Rainfall was the main source of hydrological changes, with its frequency a possible direct variable governing the range of discharge changes. Rainfall was weak in November${\sim}$May and heavy in June${\sim}$October (heavist in summer). The range of water discharge was greatest during summer (July to September) and lowest during winter (January to February). A principal component analysis (PCA) showed that aquatic environmental factors could be classified into three different types in the pattern of annual variation. First, type I included water temperature, turbidity, water color and organic matter (COD), which increased with increasing water discharge. Second, type ll consisted of DO and pH, which decreased with increasing water discharge. Third, type III included conductivity, alkalinity and chloride ion, which showed middle values with increasing water discharge. Monthly variation of aquatic environments explained by the first two dimensions of the PCA suggests that aquatic environments of Paltang Reservoir may have annual cycle typical of river-type reservoirs depending on hydrological factor such as water discharge.

• Weed & Turfgrass Science
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• v.5 no.1
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• pp.1-4
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• 2016

The Rural Development Administration of Korea conducted a series of surveys of paddy weeds from 1971 to 2013 in approximately 10-year cycles and the results have been used for the efficient weed management of paddy fields. In 1971, annual weeds such as Rotala indica, Eleocharis acicularis f. longiseta, and Monochoria vaginalis were dominant. In 1981, the population of Echinochloa species decreased whereas broadleaf weeds such as M. vaginalis, Sagittaria pygmaea, and S. trifolia were dominant. In 1991, perennial weeds such as Eleocharis kuroguwai, S. pygmaea, and S. trifolia were dominant over annual weeds. In 2000, M. vaginalis was the most abundant species, followed by E. kuroguwai, Echinochloa species, and S. trifolia. In 2013, herbicide-resistant Echinochloa species and M. vaginalis were most dominant, followed by E. kuroguwai, Scirpus juncoides, and S. trifolia. It has been predicted that the prevalence of Echinochloa species will continue to increase and that perennial weeds will be more abundant than annual ones in the near future. The occurrence of herbicide-resistant weeds and exotic weeds will also increase due to global warming and changes in agricultural patterns.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.11
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• pp.1271-1276
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• 2015

The recent trend is that diesel power generation on islands where its prime cost for power generation is high is replaced by new and renewable energy. Therefore, south Jeolla province is progressing the construction project of self-sufficient islands for the areas where power is supplied by depending on diesel generators, which is the project that power is supplied through eco-friendly energy source using sunlight, wind power and energy storage device etc. However, it is difficult to construct new and renewable energy source with the capacity to respond to the load perfectly due to its environmental and geographical conditions regarding capacity design of new and renewable energy. Besides, Microgrid design considering appropriate capacity design of the system components and efficient operation is required through the analysis of climate conditions and load patterns from the design stage for optimal composition of a hybrid system with economic feasibility. Therefore, this study is aimed to conduct a research on optimal combination, capacity calculation and economic feasibility by comprising a hybrid power generation system which will replace 40% of power generation by diesel as new and renewable energy source for Geomun Island where has more than 300 households and requires expansion of the facility among islands located in southwest coast.

• Journal of Korean Society for Geospatial Information Science
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• v.21 no.1
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• pp.27-37
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• 2013

A roof surface temperature monitoring, utilizing remotely sensed thermal infrared image has been specifically proposed to explore evidential data for heating load in winter by cool roof. The remotely sensed thermal infrared image made it possible to identify area-wide patterns of changing trends of surface temperature according to rooftop color (white, black, blue, green) which cannot be acquired by traditional field sampling. The temperature difference of cool roof having a higher solar reflectance were ranged from $3^{\circ}C$ up to $9^{\circ}C$, compared to the general roofs. It is confirmed that there is a significant potential to the energy saving by introducing the cool roof in a Korean climate since up to $18.46^{\circ}C$ difference in cool roof, compared to the general roofs in summer were already identified in Seoul, South Korea. It is anticipated that this research output could be used as a valuable reference in identifying heating load in winter by cool roof since an objective monitoring has been proposed based on the area-wide measured, fully quantitative performance of remotely sensed thermal infrared image.