• Clean Technology
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• v.16 no.2
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• pp.140-144
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• 2010

Titania-silica composite materials were obtained by sol-gel method from TiCl4 and TEOS precusors, and they were applied to anode materials of lithium ion battery. Uniformly distributed composite materials can be manufactured by sol-gel method. The composite materials were heat treated by microwave to obtain materials with new properties. The experimental variables were composition of the material, heat treatment temperature, and microwave exposure. The structure and surface properties of the materials were analyzed by XRD, SEM, and the electrochemical capacity was measured with charge/discharge cycler.

• Corrosion Science and Technology
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• v.22 no.2
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• pp.131-136
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• 2023

The aim of this study was to investigate effects of microstructure control on hydrogen diffusivity, trap activation energy, and cracking behaviors of high-strength steel using a range of experimental techniques. Results of this study showed that susceptibility to hydrogen induced cracking (HIC) was significantly associated with hydrogen diffusivity and trap activation energy, which were primarily influenced by the microstructure. On the other hand, microstructural modifications had no significant impact on electrochemical polarization behavior on the surface at an early corrosion stage. To ensure high resistance to HIC of the steel, it is recommended to increase the cooling rate during normalizing to avoid formation of banded pearlite in the microstructure. However, it is also essential to establish optimal heat treatment conditions to ensure that proportions of bainite, retained austenite (RA), and martensite-austenite (MA) constituents are not too high. Additionally, post-heat treatment at below A₁ temperature is desired to decompose locally distributed RA and MA constituents.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.156-156
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• 2022

Explicitly spatially distributed and reliable data on industrial water demand is very much important for both policy makers and researchers in order to carry a region-specific analysis of water resources management. However, such type of data remains scarce particularly in underdeveloped and developing countries. Current research is limited in using different spatially available socio-economic, climate data and geographical data from different sources in accordance to predict industrial water demand at finer resolution. This study proposes a random forest regression (RFR) model to predict the industrial water demand at 0.50× 0.50 spatial resolution by combining various features extracted from multiple data sources. The dataset used here include National Polar-orbiting Partnership (NPP)/Visible Infrared Imaging Radiometer Suite (VIIRS) night-time light (NTL), Global Power Plant database, AQUASTAT country-wise industrial water use data, Elevation data, Gross Domestic Product (GDP), Road density, Crop land, Population, Precipitation, Temperature, and Aridity. Compared with traditional regression algorithms, RF shows the advantages of high prediction accuracy, not requiring assumptions of a prior probability distribution, and the capacity to analyses variable importance. The final RF model was fitted using the parameter settings of ntree = 300 and mtry = 2. As a result, determinate coefficients value of 0.547 is achieved. The variable importance of the independent variables e.g. night light data, elevation data, GDP and population data used in the training purpose of RF model plays the major role in predicting the industrial water demand.

• Nuclear Engineering and Technology
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• v.55 no.10
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• pp.3692-3699
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• 2023

The Rare isotope Accelerator complex for ON-line experiments in Korea houses several accelerator complexes. Among them, the µSR facility will be initially equipped with a 600 MeV and 100 kW proton beam to generate surface muons, and will be upgraded to 400 kW with the same energy. Accelerated proton beams lose approximately 20% of the power at the target, and the remaining power is concentrated in the beam direction. Therefore, to ensure safe operation of the facility, concentrated protons must be distributed and absorbed at the beam dump. Additionally, effective dose levels must be lower than the legal standard, and the beam dumps used at 100 kW should be reused at 400 kW to minimize the generation of radioactive waste. In this study, we introduce a tailored method for designing beam dumps based on the characteristics of the µSR facility. To optimize the geometry, the absorbed power and effective dose were calculated using the MCNP6 code. The temperature and stress were determined using the ANSYS Mechanical code. Thus, the beam dump design consists of six structures when operated at 100 kW, and a 400 kW beam dump consisting of 24 structures was developed by reusing the 100 kW beam dump.

• Journal of Environmental Science International
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• v.33 no.1
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• pp.67-74
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• 2024

This study attempted to derive regional characteristics from forest areas in Fukuoka Prefecture, which are traditional forestry areas in Japan, but have reached a time when new conversions are needed due to a decrease in wood prices and loss of motivation due to natural disasters such as typhoons. As a result, most of them are distributed to areas that include urbanization, rural areas, and mountain villages, and production areas of remote materials, which have the potential for forestry, but need to change policies to revitalize them due to low mountain utilization. Therefore, forest management and forestry production activities by multiple municipalities were judged to be efficient in these regions due to the promotion of forestry infrastructure, such as the expansion of forestry networks and the creation of mechanized forestry.

• Korean Journal of Agricultural Science
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• v.4 no.2
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• pp.126-140
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• 1977

Present studies were carried out for breeding cold resistant clones of Citrus, improving overwintering techniques of Citrus in Jeju island as well as other southern region, Result obtained were as follows 1. In the vinyl house covered with two sheets of straw mat, 12 indivuals were found as non-injury and 15 were slightly injured by leaf freeging test at $-9^{\circ}C$ for 2 hours treatment. 2. In the condition of vinyl house covered with straw mat and viny film mulching and heat-in by sun-light, the inside temperature of vinyl house were not lowered below $-3^{\circ}C$ and the ground temperatura in vinyl house keeps above $0^{\circ}C$ during winter though outdoor temperature were lower by $-15^{\circ}C$(Daejeon area). 3. The vinyl tunnel inside the vinyl house and vinyl film mulching on ground position showed greater effectiveness for preventing heat loss from house but there were no significant difference between the color of vinyl film covered the tunnel. 4. In the vertical distribution of maximum temperature in vinyl house, the upper space was slightly higher than the lower position at high temperature condition, while minimum temperature was distributed as higher as the middle position, ground surface and upper position in order at low temperature condition 5. In the horizontal distribution of temperature in vinyl house, ground and surface-temperature of north side was lower than the other sides, and citrus planted within 30cm from north side wall died by cold injury and in the other side near wall appeared slight symptom of cold injury. 6. The insulating trench ($30{\times}30{\times}30cm$) packed with straw bundle installed under north wall might be effective to prevent heat loss of ground temperature. 7. In cloudy and snowy day, the temperature difference between indoor and outdoor were less, and the indoor temperature were maintained highly during night due to the effect of prevention of heat loss. 8. The highest temperature in a day was observed at about P.M. 3 both inside and outside of vinyl house and the lowest temperature was observed at about A.M. 6. The difference between the highest and lowest temperature of indoor in a sunny day was $19^{\circ}C$, compared with $9^{\circ}C$ on a cloudy or snowy day in late November. Especially, lowering of temperature in a snowy day was so less that the curve of temperature change was comparatively constant, 9. If the effective methods of citrus cultivation in vinyl house with improved clone such as hardiness. semi-dwarf and spur type are applied, it might be possible to cultivate the citrus tree safely in Jeju island as well as other southern rejion and to magnity the cultivation of citrus tree.

• Korean Journal of Remote Sensing
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• v.33 no.2
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• pp.243-248
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• 2017

Sea ice which is an important component of the global climate system is being actively detected by satellite because it have been distributed to polar and high-latitude region. and the sea ice detection method using satellite uses reflectance and temperature data. the sea ice detection method of Moderate-Resolution Imaging Spectroradiometer (MODIS), which is a technique utilizing Ice Surface Temperature (IST) have been utilized by many studies. In this study, we propose a simple and effective method of sea ice detection using the dynamic threshold technique with no IST calculation process. In order to specify the dynamic threshold, pixels with freezing point of MODIS IST of 273.0 K or less were extracted. For the extracted pixels, we analyzed the relationship between MODIS IST, MODIS $11{\mu}m$ channel brightness temperature($T_{11{\mu}m}$) and Brightness Temperature Difference ($BTD:T_{11{\mu}m}-T_{12{\mu}m}$). As a result of the analysis, the relationship between the three values showed a linear characteristic and the threshold value was designated by using this. In the case ofsea ice detection, if $T_{11{\mu}m}$ is below the specified threshold value, it is detected as sea ice on clear sky. And in order to estimate the performance of the proposed sea ice detection method, the accuracy was analyzed using MODIS Sea ice extent and then validation accuracy was higher than 99% in Producer Accuracy (PA).

• Journal of the Korean earth science society
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• v.37 no.7
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• pp.434-447
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• 2016

This study analyzed mass concentrations of PM10 and PM2.5, as measured at Tae-ahn and Gang-nae, Cheongju in central Korea over the period from 2011 to 2015. Higher mass concentrations of PM10, with the exception of dustfall cases during the period of winter and spring, reflected the influence of a prevailing westerly airflow, while the level of PM10 stayed at a low level in summer, reflecting the influence of North Pacific air mass and frequent rainfall. Accordingly, cases where a daily PM10 average of $81{\mu}gm^{-3}$ or over (exceeding the status of fine dust particles being 'a little bit bad') were often observed during the period of winter and spring, with more cases occurring in parts of Tae-ahn that are located close to the sources of pollutant emission in eastern China. Dustfall usually originated from dust storms made up of particles $2.5{\mu}m$ or over in diameter. However, anthropogenic haze displayed a high composition ratio of particulate less than $2.5{\mu}m$ in diameter. Accordingly, brightness temperature difference (BTD) values from the Communication, Ocean and Meteorological Satellite (COMS) were $-0.5^{\circ}K$ or over in haze with fine particulate. PM10 mass concentrations and NOAA 19 satellite BTD for haze cases were analyzed. Though PM10 mass concentrations were found to be lower than $200{\mu}g\;m^{-3}$, the mass concentration ratio of PM2.5/PM10 was measured as higher than 0.4 and BTD was found to be distributed in the range from -0.3 to $0.5^{\circ}K$. However, the BTD of dustfall cases exceeding $190{\mu}g\;m^{-3}$, were found to be less than 0.4 and BTD was found to be distributed in the range less than $-0.7^{\circ}K$. The result of applying BTD threshold values of the large-scale transport of haze proved to fall into line with the range over which aerosols of MODIS AOD and OMI AI were distributed.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.2
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• pp.80-98
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• 2023

This study explores the effectiveness of various data preprocessing algorithms for improving subseasonal to seasonal (S2S) climate predictions from six climate forecast models and their Multi-Model Ensemble (MME) using a deep learning-based postprocessing model. A pipeline of data transformation algorithms was constructed to convert raw S2S prediction data into the training data processed with several statistical distribution. A dimensionality reduction algorithm for selecting features through rankings of correlation coefficients between the observed and the input data. The training model in the study was designed with TimeDistributed wrapper applied to all convolutional layers of U-Net: The TimeDistributed wrapper allows a U-Net convolutional layer to be directly applied to 5-dimensional time series data while maintaining the time axis of data, but every input should be at least 3D in U-Net. We found that Robust and Standard transformation algorithms are most suitable for improving S2S predictions. The dimensionality reduction based on feature selections did not significantly improve predictions of daily precipitation for six climate models and even worsened predictions of daily maximum and minimum temperatures. While deep learning-based postprocessing was also improved MME S2S precipitation predictions, it did not have a significant effect on temperature predictions, particularly for the lead time of weeks 1 and 2. Further research is needed to develop an optimal deep learning model for improving S2S temperature predictions by testing various models and parameters.

• Journal of Bio-Environment Control
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• v.24 no.2
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• pp.128-133
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• 2015

Mushrooms can grow in nature when adequate temperature and humidity are maintained, but such condition can be satisfied for only a short period of time on an annual continuum. Therefore, it can be deemed that a majority of the distributed mushrooms in the current market are produced in an artificially manipulated environment. This study was conducted to resolve the problem of the Oyster mushroom cultivation house's internal temperature and humidity imbalance, where the Oyster mushrooms are cultivated in a multi-layered shelves. The air circulation fans were installed to improve the air uniformity of the Oyster mushroom cultivation house by using multi-layered shelves. During the experiment, the ambient temperature and the ambient relative humidity ranged from $5.2^{\circ}C$ to $20.4^{\circ}C$ and 40% to 100% respectively. Due to the change of the outdoor temperature, the internal temperature of the Oyster mushroom cultivation house also changed, ranging from $13.3^{\circ}C$ to $18.4^{\circ}C$, but the temperature gap between the different internal location of the facility during the conforming recorded time only ranged from $0.2^{\circ}C$ to $1.3^{\circ}C$, being significantly stable. The internal relative humidity, ranging from 82% to 96%, also changed due to the change of the outdoor temperature. Nevertheless, the relative humidity gap between the different internal location during the conforming recorded time only ranged from 2% to 7%. Furthermore, the research staff were able to maintain the concentration of $CO_2$ from 575ppm to 731ppm(below 1,000ppm was the goal) indicating the possibility of an even management of the internal environment by installing the air circulation fan.