• The Korean Journal of Quaternary Research
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• v.15 no.1
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• pp.53-61
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• 2001

To examine the effects of El Nino-Southern Oscillation (ENSO) on the tree growths of central Korea, tree rings of Korean pine(Pinus koraiensis) , Japanese red pine (Pinus densiflora) and yew (Taxus cuspidata) were analyzed. Korean pine and red pine samples were collected from 4 and 7sites in Sorak Mountain ranges, respectively ; yew from one site in Sobaek Mountain. Correlations between ring-width and monthly temperature data showed generally positive relationships for the Korean pine and yew chronologies, but negative ones for the red pine chronologies. In the analysis of correlation between ring-width and monthly S0 index data, only one Korean pine chronology at the lower Hangaerung valley site, and one red pine chronology at Baekdamjang shelter site showed significant relationships ; negative with April SOI for the former and positive with previous August-September SOI for the latter. The other chronologies at higher elevation sites did not indicate any significant correlations with SOI.

• Wind and Structures
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• v.39 no.4
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• pp.271-285
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• 2024

The multiple-fan wind tunnel is an important facility for reproducing target wind field. Existing control methods for the multiple-fan wind tunnel can generate wind speeds that satisfy the target statistical characteristics of a wind field (e.g., power spectrum). However, the frequency-domain features cannot well represent the nonstationary winds of extreme storms (e.g., downburst). Therefore, this study proposes a multiple-fan wind tunnel control scheme based on Deep Reinforcement Learning (DRL), which will completely transform into a data-driven closed-loop control problem, to reproduce the target wind field in the time domain. Specifically, the control scheme adopts the Deep Deterministic Policy Gradient (DDPG) paradigm in which the strong fitting ability of Deep Neural Networks (DNN) is utilized. It can establish the complex relationship between the target wind speed time series and the current control strategy in the DRL-agent. To address the fluid memory effect of the wind field, this study innovatively designs the system state and control reward to improve the reproduction performance based on historical data. To validate the performance of the model, we established a simplified flow field based on Navier Stokes equations to simulate a two-dimensional numerical multiple-fan wind tunnel environment. Using the strategy of DRL decision maker, we generated a wind speed time series with minor error from the target under low Reynolds number conditions. This is the first time that the AI methods have been used to generate target wind speed time series in a multiple-fan wind tunnel environment. The hyperparameters in the DDPG paradigm are analyzed to identify a set of optimal parameters. With these efforts, the trained DRL-agent can simultaneously reproduce the wind speed time series in multiple positions.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.19 no.2
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• pp.1-18
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• 2016

Baekdudaegan Mountain System (BDMS) is a unique and traditional concept in Korea that puts importance on the connectivity of energy when Korean people recognize their mountain system. Two main national organizations that are in charge of managing natural environment in Korea, Korea Forest Service (KFS) and Ministry of Environment (MoE), have been independently investigating the natural resources in protected areas of BDMS. Each organization released its first survey report for the whole protected areas in 2011. In order to provide better understanding of BDMS's natural environment, the results contained in the first reports of KFS and MoE were compared. It was found that KFS contains a wider variety of survey items, though many of the items are overlapped between the reports of KFS and MoE. It was noticeable that the survey results of KFS and MoE were not always matched even for the same or similar items in the identical target areas. The main causes of the different survey results are suggested to be the differences of the details of the survey conditions between KFS and MoE, such as the season of the surveys and the subjectivity of surveyors, and the type of literatures included in the indoor survey. As a result, it is difficult to directly compare the survey results of KFS and MoE, which leads to low usability of the data and low efficiency of the survey processes. Therefore, it is strongly recommended that the sections and methodologies of survey should be clearly set with consideration for the research purposes. The survey data and geographical information should be digitalized and opened to the public for better accessibility to BDMS information. Also, the survey reports should include English summary, thereby the results can be utilized globally for scientific, cultural and political purposes, such as designation of a heritage site.

• Journal of Korean Society for Geospatial Information Science
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• v.24 no.1
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• pp.99-107
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• 2016

Korea has been known as volcanic disaster free area. However, recent surveying result shows that Baekdu mountain located in northernmost in the Korean peninsula is not a dormant volcano anymore. When Baekdu mountain is erupting, various damages due to the volcanic ash are expected in South Korea area. Especially, volcanic ash in the air may cause big aviation accident because it can hurt engine or gauges in the airplane. Therefore, it is a crucial issue to interrupt airplane navigation, whose route is overlapped with volcanic ash, after predicting three dimensional dispersion of volcanic ash. In this paper, we deals with 3D visualization techniques for volcanic ash dispersion prediction results. First, we introduce the data acquisition of the volcanic ash dispersion prediction. Dispersion prediction data is obtained from Fall3D model, which is volcanic ash dispersion simulation program. Next, three 3D visualization techniques for volcanic ash dispersion prediction are proposed. Firstly proposed technique is so called 'Cube in the Air', which locates the semitransparent cubes having different color depends on its particle concentration. Second technique is a 'Cube in the Cube' which divide the cube in proportion to particle concentration and locates the small cubes. Last technique is 'Semitransparent Volcanic Ash Plane', which laminates the layer, whose grids present the particle concentration, and apply the semitransparent effect. Based on the proposed techniques, the user could 3D visualize the volcanic ash dispersion prediction results upon his own purposes.

• Journal of Wetlands Research
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• v.20 no.3
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• pp.210-218
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• 2018

It is very important to analyze water balance in the mountain wetland for the sustainable management of the wetland. In this study, the SWAT model was used to analyze the water balance of Janggun wetland located in Geumjeong mountain of Gyungnam province, Korea. The data such as rainfall and water level measured in Janggun wetland were used for water balance analysis and from the analysis we have known that the rainfall of 10mm within 8 days is required for maintaining an appropriate water level in Janggun wetland. Also, water balance analysis in the wetland for the period of 2009 to 2017 was performed by using hydro-meteorological data obtained from Yangsan weather station which is located around Janggun wetland. From the analysis results, we have known that the amount of rainfall was relatively small in 2010, 2012 and 2015 and water shortage was occurred in the wetland. Especially, water shortage was occurred during the summer that we had intensive rainfall for very short time and faster removal of the runoff from the wetland. Therefore, we may need extend water courses from a wetland watershed to the wetland for preventing land-forming of the wetland and also store water by banking up the wetland for preventing the decrease of water level in the wetland.

• Journal of Environmental Science International
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• v.15 no.12
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• pp.1141-1154
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• 2006

Orographic effect is one of the important factors to induce Local circulations and to make atmospheric turbulence, so it is necessary to use the exact topographic data for prediction of local circulations. In order to clarify the sensitivity of the spatial resolution of topography data, numerical simulations using several topography data with different spatial resolution are carried out under stable and unstable synoptic conditions. The results are as follows: 1) Influence of topographic data resolution on local circulation tends to be stronger at simulation with fine grid than that with coarse grid. 2) The hight of mountains in numerical model become mote reasonable with high resolution topographic data, so the orographic effect is also emphasized and clarified when the topographic data resolution is higher. 2) The higher the topographic resolution is, the stronger the mountain effect is. When used topographic data resolution become fine, topography in numerical model becomes closer to real topography. 3) The topographic effect tends to be stronger when atmospheric stability is strong stable. 4) Although spatial resolution of topographic data is not fundamental factor for dramatic improvement of weather prediction accuracy, some influence on small scale circulation can be recognized, especially in fluid dynamic simulation.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.981-983
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• 2003

The Remote Sensing Group of the Mines and Geosciences Bureau (MGB) has acquired SAR data of the Central Cebu Island for its research study area. The MGB is one of the proponent of DOST-NASA PACRIM II Project, which is composed of eleven (11) agencies and institutions in the Philippines, that focuses on the scientific application of radar data with the theme on hazard and natural resources management. The PACRIM II Project, being done on three-year term, is slated for completion in the year 2004. The main thrust of the project study of the MGB is the baseline environmental monitoring studies, on which the data are to be fused with some other available data from LandSAT and photogrammetry. The generated data is part of the information for the update of thematic mapping being done. The 12 ${\times}$ 60 km swath AirSAR data covers the Central Cebu Island. The highlights of conducting this research project are: Extent of Watershed Basin boundaries - identification of the tributaries that drain water supply to the metropolitan area; Monitoring of the mountain highways - identification of landslide risk prone sites as part of natural hazard monitoring on a national highway that cuts along the mountainous areas; and Coastline change assessment - monitoring the coastline activities relative to the rapid urbanization and exposure as part of coastal management. The Phase 1 of this report discusses the fusion with the ArcView generated data as baseline studies on the monitoring activities.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.10a
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• pp.391-396
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• 2003

The digital map expresses natural topography and artificial things with 3D position coordinates in the computer such as the road, railway, building, river, mountain, paddy and dryland. Therefore, those should contribute to the information-oriented society by maintaining information and providing it to users quickly. However it is difficult to maintain the most recent topographic information all the time because of restricted budget and time. The purpose of this study is to investigate and analyze the updating area of the digital map using remotely sensed data, and to furnish the useful information reducing cost and time. To predict updating area of the digital map, we applied the urban changes analysis method to Landsat TM images from produced date of the digital map to up-to-date. Classification method for urban change analysis applied single band process algorithm. This study presents that updating area of the digital map is predicted by only the rate of 40% on total research area.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.83.3-83.3
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• 2015

During a six-month period (autumn 2014 within the framework of a research & education project) we have constructed a professional double-station video-meteor detection network at the SOAO and BOAO mountain summits. Meteor detection is achieved by pixel-to-pixel motion-detection trigger. Each station is nearly autonomous and has three cameras with fixed viewing angles monitoring part of the night-sky over Korea. Various field of views are in use for testing purpose and captured video-meteor data is automatically transferred to a central FTP server on a nightly basis. Data is publicly available. The network has been operational since September 2014 and could serve as a prototype system for a more extended national network for meteor/fireball monitoring and detection in Korean airspace. We will report on the network construction, technical setup and present first results of detected meteors and fireballs. Further information: Meteors@KASI: http://meteor.kasi.re.kr.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.62.2-63
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• 2015

During a six-month period (autumn 2014 within the framework of a research & education project) we have constructed a professional double-station video-meteor detection network at the SOAO and BOAO mountain summits. Meteor detection is achieved by pixel-to-pixel motion-detection trigger. Each station is nearly autonomous and has three cameras with fixed viewing angles monitoring part of the night-sky over Korea. Various field of views are in use for testing purpose and captured video-meteor data is automatically transferred to a central FTP server on a nightly basis. Data is publicly available. The network has been operational since September 2014 and could serve as a prototype system for a more extended national network for meteor/fireball monitoring and detection in Korean airspace. We will report on the network construction, technical setup and present first results of detected meteors and fireballs. Further information: Meteors@KASI: http://meteor.kasi.re.kr.