• Environmental Engineering Research
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• v.24 no.3
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• pp.456-462
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• 2019

Hydrocarbon contamination is among the most challenging problems in soil remediation. Electrokinetic method can be a promising method to remediate hydrocarbon-contaminated soils. Electrokinetic method consists of different transport phenomena including electro-migration, electrophoresis, and electroosmotic flow. Electroosmotic flow is the main transport phenomenon for hydrocarbon removal in soil porous media. However, the main component of hydrocarbons is the hydrophobic organic which indicates low water solubility; therefore, it makes the electroosmotic flow less effective. The objective of the present study is to enhance electrokinetic remediation of diesel-contaminated silty sand by increasing the solubility of the hydrocarbons in the soil and then increase the efficiency. For this purpose, sodium dodecyl sulfate (SDS) was used as a catholyte. In this content, SDS 0.05 M was used as catholyte and $Na_2SO_4$ 0.1 M was used as an anolyte. Low (1 V/cm) and high (2 V/cm) voltage gradients were used in periodic and continuous forms. The best removal efficiency was observed for high voltage gradient (2 V/cm) in a periodic form, which was 63.86. This result showed that a combination of periodic voltage application in addition to the employment of SDS is an effective method for hydrocarbon removal from low permeable sand.

• Advances in nano research
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• v.16 no.1
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• pp.27-40
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• 2024

This work is the first of its kind to integrate Mindlin's theory with analytical methods in order to produce an exact solution to a specific vibration issue as well as a bending problem involving a nanoplate that is supported by a viscoelastic foundation. The plate is exposed to the simultaneous effects of a compressive load in the plate plane and a force operating perpendicular to the plane of the nanoplate. In addition, the flexoelecity effect is included into the plate. The strain gradient component is taken into consideration while calculating the plate equilibrium equation using the nonlocal theory and Hamilton's principle. The free vibration and static responses of the nanoplate seem to be both real and imaginary components because of the appearance of the viscoelastic drag coefficient of the viscoelastic foundation. This study also shows that when analyzing the mechanical response for nanostructure, taking into account the flexoelectricity effect and the influence of the nonlocal parameter, the results will be completely different from the case in which this parameter is ignored. This indicates that it is vital to take into consideration the effects of nonlocal parameters on the nanosheet structure while also taking into consideration the effect of flexoelectricity.

• Communications for Statistical Applications and Methods
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• v.31 no.2
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• pp.213-234
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• 2024

In recent decades, increasing research attention has been directed toward predicting the price of stocks in financial markets using deep learning methods. For instance, recurrent neural network (RNN) is known to be competitive for datasets with time-series data. Long short term memory (LSTM) further improves RNN by providing an alternative approach to the gradient loss problem. LSTM has its own advantage in predictive accuracy by retaining memory for a longer time. In this paper, we combine both supervised and unsupervised dimension reduction methods with LSTM to enhance the forecasting performance and refer to this as a dimension reduction based LSTM (DR-LSTM) approach. For a supervised dimension reduction method, we use methods such as sliced inverse regression (SIR), sparse SIR, and kernel SIR. Furthermore, principal component analysis (PCA), sparse PCA, and kernel PCA are used as unsupervised dimension reduction methods. Using datasets of real stock market index (S&P 500, STOXX Europe 600, and KOSPI), we present a comparative study on predictive accuracy between six DR-LSTM methods and time series modeling.

• Geophysics and Geophysical Exploration
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• v.5 no.3
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• pp.199-205
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• 2002

In the resistivity method, the potential difference between two grounded electrodes is measured and this can be positive or negative. The apparent resistivity and the potential difference have the same polarity. Since the electric field is the gradient of the potential, the polarity of the potential difference depends on the direction of the electric field. If the direction of the vector connecting two grounded electrodes is the same to that of the electric field, the measured potential difference and the apparent resistivity become positive. If the opposite is the case, they become negative. In general, the primary electric field and the vector connecting two potential electrodes have the same direction in a surface resistivity method. In this case, the measured potential difference is always positive because the primary electric field is greater than the secondary field. Therefore, the apparent resistivity is always positive if noise is free and topography is flat. The secondary field component, however, can be greater than the primary field component along the vector connecting two potential electrodes in the cross-hole resistivity method. Furthermore, if the secondary electric field and the vector connecting two potential electrodes have an opposite direction, the apparent resistivity become negative. Consequently, the apparent resistivity may be negative in the region where the primary electric field component along the vector connecting two potential electrodes is very small.

• Journal of the Korean association of regional geographers
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• v.6 no.2
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• pp.71-82
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• 2000

The purpose of this paper is to clarify geomorphic features and development on the boulder stream of granitoid in Korea. Considering the purpose and the method of this paper, three boulder streams are selected : Biseulsan(Mt. Biseul) boulder stream (Daegu city), Maneosan (Mt. Maneo) boulder stream(Gyeongnam province), Geumjeongsan(Mt. Geumjeong) boulder stream (Busan city). The boulder streams mentioned above are bigger in scale and more typical in shape than any other ones in the Korean Peninsula. The main results are summarized as follows. 1. The following are the main features of the boulder streams morphology : the mean gradient is $3{\sim}25^{\circ}$, the longer axes of the component boulders within the deposits averaged about 2m in length, the shapes of the component boulders may be both subangular and subrounded features. 2. The formation of the component boulders is associated with deep weathering of granitoid under warm humid conditions, and the downward movement of boulders occurred by solifluction and frost creep under periglacial conditions. 3. The geomorphic development stage of the boulder streams may be classified into four stages. These boulder streams come under fossil landform stage, the 4th stage ; evidence provided by lichens and weathering features indicate inactive or fossil landform. 4. In generally, boulder streams are well developed on shallow valley floors.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.2
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• pp.47-58
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• 2023

The quality and yield of crops produced using field cultivation are expected to decrease due to the recent global climate change caused by extreme weather. The plant reproductive stage associated with crop yields is a highly vulnerable period to global warming caused by high temperatures. This study analyzed the adzuki bean's yield properties, antioxidant contents, and pollen viability of adzuki bean (Vigna angularis L.) under high-temperature stress and growth periods in a temperature gradient greenhouse that forms 0 to 4℃ above the outside temperatures. As the main variety of red beans cultivated in Korean farms, the "Arari" red bean was grown in the rain shield greenhouse and the temperature gradient greenhouse from 2021 to 2022 in Milyang, Korea. Compared to 2022, it showed a 0 - 1.0℃ lower temperature during the whole growth period in 2021. However, its average temperatures were 0 - 3.7℃ higher in the vegetative stage and 0.4 - 2.4℃ higher in the anthesis stage in 2021. The lowest yield (6.8 ± 0.7 g) was at the highest temperature (T4: low, 23.6℃; average, 28.5℃; high, 35.8℃) during the anthesis stage in 2021. The temperatures of the mature stage were 1.7 - 3.9℃, which were higher in 2022 than in 2021, although the low temperatures of 2022 were lower than in 2021. The yields of the mature stage in 2022 increased more than in 2021 because of the high temperature of the mature stage. The growth and yield were good at 40.5℃ in the vegetative stage. However, growth was poor when the average temperature was 27.0℃ or higher, and yields decreased during the flowering period. Total polyphenol and flavonoid contents were increased, and the pollen viability was 40.75% in the whole growth period at high temperature (T4: low, 22.9℃; average, 28.8℃; high, 36.9℃). These results showed that the antioxidant levels increased when the antioxidant component was affected at higher temperatures than at normal. In contrast, the pollen viability-related yield decreased as the temperature increased. Our results are the basic data for field growers and the breeding of thermos-tolerance in adzuki beans to prepare for the changeable future climate.

• The Korean Journal of Applied Statistics
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• v.30 no.1
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• pp.41-55
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• 2017

This study predicts the average scores of top 150 PGA golf players on 132 PGA Tour tournaments (2013-2015) using data mining techniques and statistical analysis. This study also aims to predict the Top 10 and Top 25 best players in 4 different playoffs. Linear and nonlinear regression methods were used to predict average scores. Stepwise regression, all best subset, LASSO, ridge regression and principal component regression were used for the linear regression method. Tree, bagging, gradient boosting, neural network, random forests and KNN were used for nonlinear regression method. We found that the average score increases as fairway firmness or green height or average maximum wind speed increases. We also found that the average score decreases as the number of one-putts or scrambling variable or longest driving distance increases. All 11 different models have low prediction error when predicting the average scores of PGA Tournaments in 2015 which is not included in the training set. However, the performances of Bagging and Random Forest models are the best among all models and these two models have the highest prediction accuracy when predicting the Top 10 and Top 25 best players in 4 different playoffs.

• The Korean Journal of Pharmacology
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• v.30 no.2
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• pp.243-254
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• 1994

Inflammatory diseases, allergic and asthmatic disorders are caused by the mediator release from the activation of the phospholipase C (PLC), phospholipase D (PLD), methyltransferase or adenylate cyclase etc. during IgG or IgE cross-linking of high affinity receptors on mast cells or basophil surface. One important enzyme activated after IgG or IgE receptor cross-linking is PLD, the enzyme which converts phosphatidylcholine (PC) to phosphatidic acid (PA). Under the hypothesis that these may be some differences in mediator release according to the difference in PLD activity, we attempted to confirm the ginseng saponin effects on the PLD activity. We examined the PLD activity during the passively sensitized mast cell activation in the presence of single component of ginsenosides $(Rc,\;Rg_1,\;Rg_2,\;Rg_3)$. We also measured the amount of mediators (histamine and leukotrienes) released by stimulating with ovalbumin (OA) or calcium ionophore (CaI), Guinea Pig lung mast cells were purified using enzyme digestion, count current elutriation, and discontinuous Percoll density gradient. In purified mast cells prelabeled with $[^3H]$ arachidonic acid or $[^3H]$ palmitic acid, PLD activity was assessed more directly by the production of labeled PEt by PLD-mediated transphosphatidylation in the presence of ethanol. Histanine release was determined by Spectrophotofluorometry, and leukotrienes by radioimmunoassay. The PLD activity during the passively sensitized mast cell activation is increased up to $3{\sim}5times$. The PLD activity during the passively sensitized mast cell activation in the presence of all ginsenosides is decreased up to $4{\sim}11$ times. $Rg_l\;and\;Rg_2$ ginsenoside pretreatment decreased histamine and leukotrienes by 50% in the OA-induced or by 40% in the Cal-induced mast cell after passively sensitization. Rc pretreatment poorly decreased histamine but leukotrienes decreased by 70% in the OA-induced or by 35% in the Cal-induced mast cell. $Rg_3$ ginsenoside pretreatment increased histamine release without challenging OA or Cal but leukotrienes decreased. These observations indicate that single unit of ginsenosldes may be an important contributor to inhibit the release of histamine and leukotrienes in the guinea pig lung mast cells, that inhibits the PLD-mediated formation of DAG evoked by mast cell activation.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.3
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• pp.177-184
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• 2000

The effect of the buyancy and thermocapillarity for differnent aspect ratio of flow field on melt motion and mass transfer has been numerically investigated in magnetic Czochralski crystal growth of silicon. During the process of crystal growth, the melt depth of crucible reduces so the aspect ratio of flow field also reduces. Therefore the shape of magnetic field of the flow field changes and the flow pattern also changes significantly. Together with the melt flow which forms the Marangoni convection (or thermocapillary flow) that comes from the inside the flow field, a flow circulation is observed near the corner close both to the crucible wall and the free surface. Due to this circulation, buoyancy effect has been turned out to be local rather than global. As the aspect ratio decreases, the radial component of the magnetic field prevails compared with the axial component in the flow field. Under the influence of this magnetic field, the melt flow and the temperature distribution in a meridional plane tend to depend on the radial position. As the aspect ratio decreases, the temperature gradient near the edge of the crystal decreases yielding smaller thermocapillarity, and the oxygen concentration near the crystal and the oxygen incorporation rate also decrease.

• Korean Journal of Environmental Agriculture
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• v.35 no.1
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• pp.32-38
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• 2016

BACKGROUND: Our study aims to investigate the impact of temperature on the abundance and structure of soil microbial community in a temperature gradient tunnel.METHODS AND RESULTS: To investigate the interaction between temperature and input of C and N, rice straw and urea were applied to the study plots, respectively. We also studied the impact of plants by comparing plots cultivated with rice and unplanted plots. Soil microbial response was measured using the phospholipid fatty acid (PLFA) analysis. Soil chemical properties, including pH and ammonia and phosphate concentrations were influenced by warming and material addition. Microbial PLFA was partially influenced by material inputs, and actinomycetes PLFA was decreased by warming. In cultivated rice plots, an increase in the carbon to nitrogen ratio illustrated the effect of plant on microbiota caused by carbon addition through the root residues. Results from the principal component analysis of PLFA data showed that warmed and control plots applied with rice straw could be separated by principal component analysis.CONCLUSION: Our results suggest that plant influence both the microbial community structure and abundance, and temperature change has a minimal impact on soil microorganisms in flooded soil.