• Korean Journal of Remote Sensing
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• v.36 no.3
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• pp.487-501
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• 2020

As a viable option for retrieval of LST (Land Surface Temperature), this paper presents a DNN (Deep Neural Network) based approach using 148 Landsat 8 images for South Korea. Because the brightness temperature and emissivity for the band 10 (approx. 11-㎛ wavelength) of Landsat 8 are derived by combining physics-based equations and empirical coefficients, they include uncertainties according to regional conditions such as meteorology, climate, topography, and vegetation. To overcome this, we used several land surface variables such as NDVI (Normalized Difference Vegetation Index), land cover types, topographic factors (elevation, slope, aspect, and ruggedness) as well as the T₀ calculated from the brightness temperature and emissivity. We optimized four seasonal DNN models using the input variables and in-situ observations from ASOS (Automated Synoptic Observing System) to retrieve the LST, which is an advanced approach when compared with the existing method of the bias correction using a linear equation. The validation statistics from the 1,728 matchups during 2013-2019 showed a good performance of the CC=0.910~0.917 and RMSE=3.245~3.365℃, especially for spring and fall. Also, our DNN models produced a stable LST for all types of land cover. A future work using big data from Landsat 5/7/8 with additional land surface variables will be necessary for a more reliable retrieval of LST for high-resolution satellite images.

• Weed & Turfgrass Science
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• v.6 no.2
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• pp.130-135
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• 2017

In the current study, we surveyed the status of graveyard lawn maintenance in Korea. The lawn maintenance information was obtained from the vicarious companies registered on the internet portal site and the Forestry Federation of Korea, and the questionnaire investigation from Primary Agricultural Cooperatives (Nonghyup). In all provinces surveyed, individual graves were maintained on a $66m^2$ (20 Pyeong) basis. The vicarious maintenance of graveyard lawn was carried out 1~5 times a year, and the maintenance cost increased as the number of times increased. Mowing the grass around a grave (Beolcho) was mainly done before the Korean Thanksgiving Day (Chuseok). The number of Beolcho was steadily increased from 2013 to 2015, and the price was getting higher and higher. Gyeonggi province had the highest cost, and Jeolla had the lowest cost. Regardless of the year, the number of orders received were higher in Gyeongnam > Gyeongbuk > Jeonnam province in order. Most of the reason for requested Beolcho was because the client lives in the area far from the graveyard. The direction of the cemetery was very varied. According to the survey, the all grass were zoysiagrass (Zoysia japonica), and grass coverage rate of the graves was 35.4~71.9%. Through questionnaire investigation, the reason why the density of grass was lowered was because the periodic management of weeds and fallen leaves was insufficient. Further research on the maintenance of graveyard in the future will be necessary.

• Economic and Environmental Geology
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• v.50 no.6
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• pp.497-508
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• 2017

This study was carried out to document and diagnose the conditions of the seated stone statue of Buddhist Master Seungga in Seunggasa temple immediately after its conservation treatment, which was found to be long covered in surface of white materials. The stone Halo was researched along with the Statue, and basic data was secured through precisely examination and nondestructive diagnosis. The result from the surface deterioration evaluation shows that both the Statue and Halo had a little bit of physical deterioration, although their level of chemical deterioration was proportionally higher due to discoloration. The physical property diagnosis using ultrasonic measurements on the Statue and Halo showed that the average ultrasonic velocity was found to be 3,570 m/s and 3,373 m/s, respectively, which corresponds to grade III, an indication of a favorable physical property. The surface covered materials were detected to be Ca, Ti, Pb, Fe, Al and Si, emanating from Hobun (Oster shell powder; $CaCO_3$) or lime ($CaO{\cdot}Ca(OH)_2$) and silicate minerals. Furthermore, Ti and Pb seems to be the component of the white coloring pigments, titanium white ($TiO_2$) and white lead ($2PbCO_2{\cdot}Pb(OH)_2$). Therefore, the seated stone statue of Buddhist Master Seungga is presumed to be painted with Hobun or lime and thereafter painted over with titanium white and white lead.

• Nuclear Engineering and Technology
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• v.21 no.2
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• pp.111-122
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• 1989

With the Zircaloy-4 tube oxidized in high temperature (1323 K) steam for 5, 10, 30 and 60 minutes, the expanding copper mandrel test was carried out over a temperature range of 673-l173k at $\varepsilon\;=\;3.0\times10^5S\;^1$. The oxidation parameters $(K_i)$ in the present study were linearly proportional to square root of time $(Ki= \delta_{kit})$ and their rate constants ($\delta_{ki}$) are 0.281, 2.82, and 2.313 for weight gain and thickness of Zr02 and $\alpha$(0) layer, respectively. Activation energy for high temperature (873-1073k) plastic deformation of Zircaloy-4 increases from 251 KJ/mol to 323 KJ/mol with increase in oxidation time from 5 minutes to 60 minutes due to the high strengthened Zr02. With the oxide layer thickness [K ; expressed in "Equivalent Cladding Reacted" (ECR,%)] and the yield stress obtained from the mandrel test, an empirical relation was derived as ($\sigma/C)^n=K^mexp$ (Q/RT) with n=6.9, m=5.7, C=0.155, 0.138, 0.051, and 0.046 MPa for Q=251, 258, 316, 323 KJ/mol, respectively.

• Korean Journal of Remote Sensing
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• v.37 no.2
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• pp.211-220
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• 2021

Land Surface Temperature (LST) is one of the useful parameters to diagnose the growth and development of crop and to detect crop stress. Unmanned Aerial Vehicle (UAV)-based LST (LSTUAV) can be estimated in the regional spatial scale due to miniaturization of thermal infrared camera and development of UAV. Given that meteorological variable, type of instrument, and surface condition can affect the LSTUAV, the evaluation for accuracy of LSTUAV is required. The purpose of this study is to evaluate the accuracy of LSTUAV using LST measured at ground (LSTGround) under various meteorological conditions and growth phases of garlic crop. To evaluate the accuracy of LSTUAV, Relative humidity (RH), absolute humidity (AH), gust, and vegetation index were considered. Root mean square error (RMSE) after minimizing the bias between LSTUAV and LSTGround was 2.565℃ under above 60% of RH, and it was higher than that of 1.82℃ under the below 60% of RH. Therefore, LSTUAV measurement should be conducted under the below 60% of RH. The error depending on the gust and surface conditions was not statistically significant (p-value < 0.05). LSTUAV had reliable accuracy under the wind speed conditions that allow flight and reflected the crop condition. These results help to comprehend the accuracy of LSTUAV and to utilize it in the agriculture field.

• Journal of the Korea Concrete Institute
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• v.25 no.5
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• pp.529-537
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• 2013

The aim of the current study is to develop a nonlinear isoparametric layered frame finite element (FE) analysis of FRP strengthened reinforced concrete (RC) beam or column members by a force-based FE formulation. In sections, concrete is modeled in the triaxial stress-strain relationship state and the FRP sheet is modeled as layered composite materials in two-dimension. The element stiffness matrix derived by the force-based FE has the force-interpolation functions without assuming the displacement shape functions. A lateral load test of RC column strengthened by GFRP sheets was analyzed by the developed force-based FE model. From comparative studies of the experimental and analysis results, it was shown to compare with the stiffness FE method that the force-based FE analysis could give more accurate predictions in the overall lateral load-deflection response as well as in nonlinear deformations and damages in the column plastic hinge region.

• Journal of Environmental Science International
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• v.19 no.9
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• pp.1103-1108
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• 2010

This study was conducted to be used as basic data of environmental friendly construction planning by comparing and analyzing thermal environment, find particles and biotope area rate according to land cover types of outside space of schools located in Chung-ju. When meteorological factors were analyzed according to land cover types, for temperature planting area and paved area showed low-and high-temperature ranges, respectively, and relative humidity was negatively related with temperature as low-and high-temperature ranges corresponded to high-and low-humidity ranges, respectively. For Wet Bulb Globe Temperature Index (WBGT) by land cover types, it was observed to be artificial grass> bare land> natural grass. Find particles were different according to land cover types of playground with being bare land> artificial grass> natural grass in the order. Bare land playground, where there were artificial factors and no absorption of fine particles through stomata of leaves as a function of natural circulation, recorded the highest level of $39.8\;{\mu}g/m^3$ and the level was relatively higher compared to the levels by season in Chung-ju. Biotope area rate showed the order of M elementary school> K elementary school> C commercial high school. That was considered to be caused by the difference of land cover type of school playground accounting for a large part of a school.

• Journal of Korean Society of Forest Science
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• v.101 no.3
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• pp.538-545
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• 2012

This study addressed soil disturbances following harvesting as well as soil physical and hydrological properties within three first-order headwater catchments characterized by ephemeral-intermittent streams. Four treatments representing a range of potential Best Management Practices(BMPs) for ephemeral-intermittent streams were used; BMP1, BMP2, clearcut and reference. This study includes 1 year of pre- and post-harvest observations. Results showed that post-harvest disturbances were closely related with harvesting intensity and generally tended to reflect changes in soil physical and hydrological properties following harvest with the except of bulk density and porosity. Forest clearcutting decreased macroporosity and saturated hydraulic conductivity, and increased soil resistence as a result of severe soil disturbances thereby increasing soil erosion. These impacts were reduced by implementing two BMP treatments during harvesting activities. The finding support the use of either BMP treatments for ephemeral-intermittent streams, however, the additional measure of leaving logging debris in BMP2 did not cover enough soil surface to reduce erosion.

• Journal of the Korean Institute of Landscape Architecture
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• v.35 no.4
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• pp.40-47
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• 2007

The objective of this study is to analyze the propriety of the Biotope Area Factor's(BAF) application and propose an improvement plan. The BAP system, initially started by Seoul metropolitan city, is being settled in Korea. The BAF originated from the Biotop $Fl{\ddot{a}}chen$ Faktor(BFF) system of Berlin Germany. It was established as part of the Landscape Plan for the ecological function recovery in the high density built-up area with a sense of environmentally friendly urban management. The study compared the BAF's present condition of Ganddong-Gu, Seoul with Seoul's BAF system. Some problems appeared from the system application. Firstly, it may cause ecological damage if the site ranges are more than current BAF system limits. Secondly, the application of the current BAF system has the possibility of general redevelopment, but the partial improvement considering current standards of the high density built-up area's paving section is impossible. Lastly, division of the application object and application type are not divided well. In addition, the Seoul BAF which is currently applied across the board is based on the destruction of the natural area and low density built-up area. Accordingly, to improve these problems requires a complementary system protecting the ecological function prior to the application of the BAF and with restricted application to high density of BAF system built-up area.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.5
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• pp.563-570
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• 2015

The existing research on the damage detection method for building structures has considered the damages from the excessive loadings such as the earthquake. However, the structural performance of building structures could be reduced due to the deterioration based on the chloride, carbonation during the long-term time. Thus, to effectively manage the healthiness of structures, the deterioration influences on the structures should be checked. In this study, the corrosion of rebars by the chloride is considered as the deterioration factor. To consider the structural performance reduction of the corroded rebars, the yield strength, cross-sectional area, rupture strain of rebars and the compressive strength of cover concrete based on the corrosion level are estimated. These properties of rebars and cover concrete are used for the procedure to evaluate the structural performance reduction of structural member level and the building level. The moment-curvature analysis is performed to evaluate the structural performance reduction of structural member level. Also, the eigenvalue analysis and the pushover analysis are performed to investigate the natural period and mode shape and the strength and deformation performance of buildings, respectively.