• Journal of the Korean Wood Science and Technology
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• v.50 no.2
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• pp.113-125
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• 2022

This study aimed to explore the biodiversity of chemical compounds found in the bark of Guibourtia tessmannii from Gabon, commonly called Kévazingo, and evaluate their anti-termite activity to determine their potential values as a source of development of anti-termite products that can be valued in the fields of fine chemicals and wood preservation. Extraction of G. tessmannii bark powders was carried out using the cold maceration method with trichloroethylene, acetone, ethanol, and water. Phytochemical screening made it possible to highlight groups of chemical families present in the extracts. Anti-termite activity was tested on the wild termites "Cubitermes sp" of the genus Isoptera. The yield of the extracts were 17.11% for the buttress and 13.42% for the height at 6 m. Phytochemical tests revealed that alkaloids, polyphenols, sterols, tannins, reducing compounds, flavonoids, saponins, and anthraquinones were present in the extracts. Results of anti-termite activity indicated that anti-termite activity varied with the different parts of the bark studied, extraction solvent, and concentration (50/50) and (25/75) of the extracts used. The extracts at 50/50 concentration showed a slightly better anti-termite activity compared to the 25/75 concentration. In addition, the buttress Kévazingo or buttress showed the strongest anti-termite activity for the aqueous extract with a survival rate of 0% after 2 days.

• Journal of Environmental Impact Assessment
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• v.22 no.2
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• pp.135-145
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• 2013

The recycling of coal bottom ash generated from coal power plants in Korea has been limited due to heterogenous characteristics of the materials. The most common management option for the ash is disposal in landfills (i.e. ash pond) near ocean. The presence of large coarse and fine materials in the ash has prompted the desire to beneficially use it in an application such as fill materials. Prior to reuse application as fill materials, the potential risks to the environment must be assessed with regard to the impacts. In this study, a total of nine test cells with bottom ash samples collected from pretreated bottom ash piles and coal ash pond in a coal-fired power plant were constructed and operated under the field conditions to evaluate the leachability over a period of 210 days. Leachate samples from the test cells were analyzed for a number of chemical parameters (e.g., pH, salinity, electrical conductance, anions, and metals). The concentrations of chemicals detected in the leachate were compared to appropriate standards (drinking water standard) with dilution attenuation factor, if possible, to assess potential leaching risks to the surrounding area. Based on the leachate analysis, most of the samples showed slightly high pH values for the coal ash contained test cells, and contained several ions such as sodium, potassium, calcium, magnesium, chloride, sulfate, and nitrate in relatively large quantities. Three elements (aluminum, boron, and barium) were commonly detected above their respective detection limits in a number of leachate samples, especially in the early leaching period of time. The results of the test cell study indicate that the pollutants in the leachate from the coal ash test cells were not of a major concern in terms of leaching risk to surface water and groundwater under field conditions as fill materials. However, care must be taken in extending these results to actual applications because the results presented in this study are based on the limited field test settings and time frame. Structural characteristics and analysis for coal bottom ash may be warranted to apply the materials to actual field conditions.

• Clean Technology
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• v.7 no.1
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• pp.13-25
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• 2001

With fast advancement of fine machineries and semiconductor industries in recent decades, the ultra-cleaning of organic chemicals, submicron particles from contaminated unit equipments and products such as silicon wafers becomes one of the most important steps for further advancement of such industries. To date, two kinds of ultra cleaning techniques are used; one is the wet-cleaning and the other is the dry cleaning. In case of wet cleaning, removal of organic contaminants and submicron particles is made by DIW with additives such as $H_2O_2$, $H_2SO_4$, HCl, $NH_4OH$ and HF, etc. While the wet cleaning method is most widely adopted for various occasions, it is inevitable to discharge significant amount of toxic waste waters in environment. Dry cleaning is an alternative method to mitigate environmental pollution of the wet cleaning with maintaining comparable degree of cleaning to the wet cleaning. Although there are various concept of dry cleaning have been devised, the dry cleaning with environmentally-benign solvent such as carbon dioxide proven to show high degree of cleaning from the contaminated porous surface as well as from the bare surface. Thus, special global attention has been placing on this technique since it has important advantages of simple process schemes and no environmentally concern, etc. Thus, this article critically reviews the state-of-the-art of the supercritical fluid drying with emphasis on the thermo-physical characteristics of the supercritical solvent, environmental gains compared to other dry cleaning methods, and the generic aspects of the basic design and processing engineering.

• Resources Recycling
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• v.19 no.3
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• pp.62-70
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• 2010

As the demand for paper continues to grow and the importance of recycled paper, white ledgar(WL) and old newspaper pulp(ONP), continuously increase. In addition, usage of recycled paper is essential in terms of forest conservation and environmental protection issues. However, optical and mechanical properties of recycled paper have some drawbacks than regular paper's properties that is indispensable. In order to complement these problems of recycled paper, precipitated calcium carbonate (PCC) was synthesized by the In-situ process with a recycled pulp. Depending on the size of PCC is divided into 2 types, $0.01{\mu}m{\sim}0.09{\mu}m$ colloid type ultra-fine particle and $0.1{\mu}m{\sim}0.9{\mu}m$ cubic type particles. In this study, we analyze how the different shape and size of precipitated calcium carbonate affects in the optical and mechanical properties of the recycled paper used as a filler. Furthermore, we mixed with chemical pulp for overcome reduce of mechanical properties, without using other chemicals, when we use PCC as a filler. The results has the possibility to meet in GR excellent recycling certification mark, standard was proposed.

• Journal of Environmental Impact Assessment
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• v.25 no.6
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• pp.369-383
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• 2016

A distributed watershed model CAMEL(Chemicals, Agricultural Management and Erosion Losses) was applied to a part of grazing grassland and vegetation buffer strip(VBS) located in Daegwanryeong, Korea. A set of scenario analyses was carried out for grassland and VBS with various combinations of VBS widths, soil textures and ground surface slopes. The simulation results indicate that annual direct runoff decreases with wider VBS and the removal efficiency of pollutants generally decrease with steeper slopes. The removal efficiency of sediment is not significantly different with VBS widths. For gentle and medium slopes($10^{\circ}$, $20^{\circ}$), the removal efficiency of TOC and TN is not significantly different with VBS widths. As for a steep slope($30^{\circ}$), however, the removal efficiency of TOC and TN increases with narrower VBS. The removal efficiency of TP is generally high except for medium and steep slope of sandy loam where the removal efficiency of TP increases with wider VBS. This result of TP is contrary to the results of TOC and TN due to the adsorption characteristics of phosphorus associated with fine sediment particles. It is expected that CAMEL can be used for evaluating the effectiveness of VBS to reduce non-point source pollution discharges.

• The Korean Journal of Pesticide Science
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• v.5 no.4
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• pp.20-26
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• 2001

A series of new 2-benzoyl-3-phenyl-2,5-dihydroisoxazol-5-one, (A) and 3-phenyl-5-phenylcarbonyl-oxyisoxazole, (B) derivatives as substrates were synthesized and their quantitative structure-activity relationships (QSAR) analyses between the antifungal activities ($pI_{50}$) and physicochemical parameters of substituents onl the benzoyl group against resistant (RPC:95CC7303) and sensitive (SPC:95CC7105) Phytophthora blight (Phytophthora capsici,) were studied. The synthetic yield (%) and antifungal activities of (A) were higher than (B) and selectivities between the fungi were not showed. From the basis on the Hansch-Fujita analyses, the optimum width values ($(B_2)_{opt.}=ca.\;4.00{\AA}$) of the substituents on the benzoyl group were important factor in determining fungicidal activity against the two fungi. Influence of the substituents as electron withdrawing group on the fungicidal activity against RPC, but not for SPC. And tile bromo- and acetyl-substituents were contributed to higher antifungal activity against RPC and SPC from the results of Free-Wilson analyses.

• The Korean Journal of Pesticide Science
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• v.6 no.2
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• pp.72-79
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• 2002

3D-QSAR between fungicidal activitives ($pI_{50}$) against metalaxyl-sensitive (SPC: 95CC7105) or metalaxyl-resisitant (RPC: 95CC7303) isolate of phytophthora blight fungus (Phytophthora capsici), and a set of 3-phenylisoxazole (A) and 3-phenyl-2,5-dihydroisoxazole (B) derivatives as substrates were conducted using comparative molecular field analyses (CoMFA). The antifungal activities of (A) were generally higher than those of (B). And it is assumed that the most stable conformation of the active substrate was approximately planar from conformational search. The CoMFA models proved a good predictive ability and suggested that the electronic field of substrates were higher than hydropohobic field and steric field requirements for recognition forces of the receptor site. And the factors were strongly correlated (cross-validated $q^2>0.570$ & conventional $r^2>0.968$) with the fungicidal activitives. According to the CoMFA analyses, the selectivity factors for RPC suggested that the sterically bulky groups (C14 & C15) and electron withdrawing groups (C15 & C16) have to be introduced to the ortho, meta and para-position on the benzoyl moiety of substrates.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.536-539
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• 2018

In this paper, we propose a system that analyzes environment information by using deep learning and then provides a suitable environment for users by predicting environmental information change. As the level of living improves, interest in improving the quality of life is increasing. In particular, as the air quality deteriorated due to the recent occurrence of dust, smog, fine dust, and ultrafine dust, the indoor air quality as well as the outdoor air became a serious problem. The increase of indoor pollution due to the lack of ventilation and the use of chemicals is a serious problem for modern people who have a lot of indoor living. In order to solve this indoor air pollution, a system has been proposed that measures the state of air quality through sensors and maintains proper temperature and humidity. However, existing system has a difficulty to apply most of the atmospheric environment information to various users depending on sensors only. The system proposed in this paper predicts the indoor environment by analyzing the indoor pollution information collected through the sensor using the deep learning. Then, the predicted indoor environment is modeled and learned in this system, and the environment suitable for the user is suggested. Afterwards, the system receives feedback from the user and repeats the process of re-learning the proposed environment so that it can create the optimal environment for the user.

• Journal of the Korean Ceramic Society
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• v.39 no.2
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• pp.178-183
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• 2002

Zinc fluosilicate ($ZnSiF_6$, 15% aqueous solution) was prepared using zinc oxide (ZnO) and fluosilicic acid ($H_2SiF_6$) by soluiton synthetic method. The fluidity and hydration properties of cement which was added $ZnSiF_6$ (aq.) as an additive for cement were studied. At water to cement ratio (W/C) equals to 0.45, the initial fluidity and slump loss of cement paste which the addition of $ZnSiF_6$ (aq.) was increased from 1.0% to 4.0% based on cement weight were investigated. Initial fluidity of cement paste was measured by mini-slump test and slump loss was examined by measuring the fluidity variation of cement paste with time elapsed from 0 min to 120 min at intervals 30 min. Also, the effect of $ZnSiF_6$ addition on the setting and hydration of cement paste when $ZnSiF_6$ increased in the addition range 1.0% to 3.0% were investigated. The fluidity of cement paste which was added 2.1% $ZnSiF_6$ (aq.) presented the highest value among all addition ranges. The setting time of cement paste was retarded gradually and the heat evolution of hydrated cement was reduced with the increasing of $ZnSiF_6$ addition.

• Journal of the Korean Geographical Society
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• v.49 no.1
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• pp.91-105
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• 2014

The objective of this study is to analyze the project performance and development process of the phase 1 project of GFEZ from 2004 to 2010. The phase 1 project from 2004 to 2010 is consist of eleven project zones. Among these zones, eight zones are currently underway and three zones have been completed. The performance of the phase 1 projects is no so much because it were stated later than planning with the difficulty of business developers selection. The major performances are development and supply of industrial & residential land, construction of road and railway, investment promotion of 102 companies, and creation of 20,971 new jobs. Most of the direct invested companies were located at Gwangyang and Yulchon Districts, and were mainly logistics and related service, iron and steel, machinery, shipbuilding, and fine chemicals. The main problems, however, are the limit of promotion of high-tech industries and large firms, low FDI reported rate, difficulty of superior business developers, delayed business progress of Hadong district. Therefore, efforts to solve these problems are required for the success of GFEZ.