• Journal of Climate Change Research
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• v.4 no.1
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• pp.41-49
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• 2013

Recent findings have revealed that black carbon is one of the substantial materials affecting climate change along with greenhouse gases. Usually, black carbon is generated by incomplete combustion of biomass and deposited on snow and ice surface, resulting in increasing adsorption of radiant energy and accelerating ice melting. However, it is still questionable what the emission characteristics of black carbons from biomass combustion is. We investigated the emission characteristics of black carbon generated from a wood stove in this study. We found that the emission of black carbon was highly dependent upon combustion temperature and the amount of combustion air supplied. The emission factors were 1.01 g-BC/kg-Oak for fireplace wood burning under incomplete combustion, 0.37 g-BC/kg-Oak for fireplace wood burning under complete combustion and 0.29 g-BC/kg-Oak for small wood-stove burning.

• Journal of Korea Water Resources Association
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• v.46 no.12
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• pp.1181-1191
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• 2013

This study have implemented finding the optimal water temperature parameter set for Hapcheon dam reservoir using CE-QUAL-W2 model. In particular the sensitivity analysis was carried out for four water temperature parameters of wind sheltering coefficient (WSC), radiation heat coefficient (BETA), light extinction coefficient (EXH2O), heat exchange coefficient at the channel bed (CBHE). Firstly, WSC, BETA, EXH2O shows relatively high sensitivity in common during April to September, and CBHE does during August to November. Secondly, as a result of identifying depth range of parameter influence, BETA and EXH2O show 0~9 m and 8~14 m which is thermocline layer close to water surface, CBHE is deep layer 12 m away from bottom. Finally, applying annual or monthly optimal parameter sets indicates that the bias between two sets does not show much differences for WSC and CBHE parameters, but BETA and EXH2O parameters show $0.20^{\circ}C$ and $0.51^{\circ}C$ of monthly average biases for two parameter sets. In particular the bias reveals to be $0.4^{\circ}C$ and $1.09^{\circ}C$ during May and August that confirms the necessity of use of monthly parameters during that season. It is claimed that the current operational custom use of annual parameters in calibration of reservoir water quality model requires the improvement of using monthly parameters.

• Korean Journal of Remote Sensing
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• v.33 no.6_1
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• pp.947-960
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• 2017

Soil moisture plays an important role to affect the Earth's radiative energy balance and water cycle. In general, satellite observations are useful for estimating the soil moisture content. Passive microwave satellites have an advantage of direct sensitivity on surface soil moisture. However, their coarse spatial resolutions (10-36 km) are not suitable for regional-scale hydrological applications. Meanwhile, in-situ ground observations of point-based soil moisture content have the disadvantage of spatially discontinuous information. This paper presents an experimental soil moisture retrieval using Sentinel-1 SAR (Synthetic Aperture Radar) with 10m spatial resolution for cropland in South Korea. We developed a soil moisture retrieval algorithm based on the technique of linear regression and SVR (support vector regression) using the ground observations at five in-situ sites and Sentinel-1 SAR data from April to October in 2015-2017 period. Our results showed the polarization dependency on the different soil sensitivities at backscattered signals, but no polarization dependence on the accuracies. No particular seasonal characteristics of the soil moisture retrieval imply that soil moisture is generally more affected by hydro-meteorology and land surface characteristics than by phenological factors. At the narrower range of incidence angles, the relationship between the backscattered signal and soil moisture content was more distinct because the decreasing surface interference increased the retrieval accuracies under the condition of evenly distributed soil moisture (during the raining period or on the paddy field). We had an overall error estimate of RMSE (root mean square error) of approximately 6.5%. Our soil moisture retrieval algorithm will be improved if the effects of surface roughness, geomorphology, and soil properties would be considered in the future works.

• Korean Journal of Materials Research
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• v.3 no.2
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• pp.121-130
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• 1993

The GaP crystals were grown by synthesis solute diffusion method and its properties were investigated. High quality single crystals were obtained by pull-down the crystal growing ampoule with velocity of 1.75mm/day. Etch pits density along vertical direction of ingot was increased from 3.8 ${\times}{10^4}$c$m^{-2}$ of the first freeze to 2.3 ${\times}{10^5}$c$m^2$ of the last freeze part. The carrier concentration and mobilities at room temperature were measured to 197.49cc$m^2$/V.sec and 6.75 ${\times}{10^{15}}$c$m^{-3]$, respectively. The temperature dependence of optical energy gap was empirically fitted to $E_g$(T)=[2.3383-(6.082${\times}{10^{-4}}$)$T^2$/(373. 096+TJeV. Photoluminescence spectra measured at low temperature were consist with sharp line-spectra near band-gap energy due to bound-exciton and phonon participation in band edge recombination process. Zn-diffusion depth in GaP was increased with square root of diffusion time and temperature dependence of diffusion coefficient was D(Tl = 3.2 ${\times}{10^3}$exp( - 3.486/$k_{\theta}$T)c$m^2$/sec. Electroluminescence spectra of p-n GaP homojunction diode are consisted with emission at 630nm due to recombination of donor in Zn-O complex center with shallow acceptors and near band edge emission at 550nm. Photon emission at current injection level of lower than 100m A was due to the band-filling mechanism.

• Journal of the Korean earth science society
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• v.41 no.6
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• pp.617-629
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• 2020

Sea surface temperature (SST), which plays an important role in climate change and global environmental change, can be divided into skin sea surface temperature (SSST) observed by satellite infrared sensors and the bulk temperature of sea water (BSST) measured by instruments. As sea surface temperature products distributed by many overseas institutions represent temperatures at different depths, it is essential to understand the relationship between the SSST and the BSST. In this study, we constructed an observation system of infrared radiometer onboard a marine research vessel for the first time in Korea to measure the SSST. The calibration coefficients were prepared by performing the calibration procedure of the radiometer device in the laboratory prior to the shipborne observation. A series of processes were applied to calculate the temperature of the layer of radiance emitted from the sea surface as well as that from the sky. The differences in skin-bulk temperatures were investigated quantitatively and the characteristics of the vertical structure of temperatures in the upper ocean were understood through comparison with Himawari-8 geostationary satellite SSTs. Comparison of the skin-bulk temperature differences illustrated overall differences of about 0.76℃ at Jangmok port in the southern coast and the offshore region of the eastern coast of the Korean Peninsula from 21 April to May 6, 2020. In addition, the root-mean-square error of the skin-bulk temperature differences showed daily variation from 0.6℃ to 0.9℃, with the largest difference of 0.83-0.89℃ at 1-3 KST during the daytime and the smallest difference of 0.59℃ at 15 KST. The bias also revealed clear diurnal variation at a range of 0.47-0.75℃. The difference between the observed skin sea surface temperature and the satellite sea surface temperature showed a mean square error of approximately 0.74℃ and a bias of 0.37℃. The analysis of this study confirmed the difference in the skin-bulk temperatures according to the observation depth. This suggests that further ocean shipborne infrared radiometer observations should be carried out continuously in the offshore regions to understand diurnal variation as well as seasonal variations of the skin-bulk SSTs and their relations to potential causes.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.3
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• pp.217-226
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• 2015

To investigate the distributions of BVOCs (Biogenic Volatile Organic Compounds) from mountain near mega city and their role in forest atmospheric, BVOCs and their oxidized species were measured at a 41 m tower in Mt. Taehwa during May, June and August 2013. A proton transfer reaction-mass spectrometer (PTR-MS) was used to quantify isoprene and monoterpenes. In conjunction with BVOCs, $O_3$, meteorological parameters, PAR (Photosynthetically Active Radiation) and LAI (Leaf Area Index) were measured. The average concentrations of isoprene and monoterpenes were 0.71 ppbv and 0.17 ppbv, respectively. BVOCs showed higher concentrations in the early summer (June) compared to the late summer (August). Isoprene started increasing at 2 PM and reached the maximum concentration around 5 PM. In contrast, monoterpenes concentrations began to increase 4 PM and stayed high at night. The $O_3$ maximum was generally found at 3 PM and remained high until 5 PM or later, which was concurrent with the enhancement of $O_3$. The concentrations of BVOCs were higher below canopy (18 m) than above canopy, which indicated these species were produced by trees. At night, monoterpenes concentrations were negatively correlated with these of $O_3$ below canopy. Using MEGAN (Model of Emissions of Gases and Aerosols from Nature), the emissions of isoprene and monoterpenes were estimated at 1.1 ton/year and 0.9 ton/year, respectively at Mt. Taehwa.

• The KIPS Transactions:PartD
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• v.13D no.7 s.110
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• pp.985-996
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• 2006

As the internet technologies develop, the geographic information system environment is changing to the web-based service. Since geospatial information of the existing Web-GIS services were developed independently, there is no interoperability to support diverse map formats. In spite of the same geospatial information object it can be used for various proposes that is duplicated in GIS separately. It needs intelligent strategies for optimal replica selection, which is identification of replication geospatial information objects. And for management of replication objects, OMG, GLOBE and GRID computing suggested related frameworks. But these researches are not thorough going enough in case of geospatial information object. This paper presents a model of location service, which is supported for optimal selection among replication and management of replication objects. It is consist of tree main services. The first is binding service which can save names and properties of object defined by users according to service offers and enable clients to search them on the service of offers. The second is location service which can manage location information with contact records. And obtains performance information by the Load Sharing Facility on system independently with contact address. The third is intelligent selection service which can obtain basic/performance information from the binding service/location service and provide both faster access and better performance characteristics by rules as intelligent model based on rough sets. For the validity of location service model, this research presents the processes of location service execution with Graphic User Interface.