• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.70-75
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• 2002

The penetration potential of TIG welding in one single run is limited, though the process itself generates high quality welds with good weld cosmetics. This is one of the main reasons, which has contributed to its development in high duty applications such as those encountered in aeronautical, aerospace, nuclear & power plant applications. For these applications, stainless steels, titanium k nickel based alloys are most often used. As these materials remain very sensible to weld heat input k atmospheric pollution, stringent processing conditions are imposed. For example welding of titanium alloys requires argon shielding of weld zone and for 5 mm thick plates multi-pass runs & filler additions are required. This multi-run operation not only raises the welding cost, but also increases defect risks. In recent years, extensive interest has been raised by the possibility to increase weld penetrations through flux applications & the process is designated ATIG-activated TIG, or FBTIG-flux bounded TIG. The improved welding performance of such flux assisted TIG is related to arc constriction and surface tension effects on weld pool. The research work by authors has lead to the formulation of welding fluxes for stainless steels k titanium alloys with TIG Process. These fluxes are now commercialized & some applications in industry have already been carried out. FBTIG for aluminum has been proposed with silica application for AC mode TIG welding. The paper highlights the fundamentals of flux role in TIG welding and illustrates some industrial applications.

• 에너지공학
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• 제13권2호
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• pp.133-143
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• 2004

Simultaneous removal technology of particulate/NOx/SOx/HCl using CuO/3Al$_2$O$_3$ㆍ2SiO$_2$catalyst impregnated ceramic candle filters is an advanced air pollution process and provides significantly to reduce hazardous gases emitted from coal-fired power plant. This process uses a high-temperature catalytic filter for integrating SOx and HCl reduction through injection an alkali sorbent (such as hydrated lime or sodium bicarbonate), NOx removal through ammonia injection and selective catalytic reduction (SCR), and particulate collection on the catalytic filter surface. The advantages of the process include : compact integration of the emission control technologies into a single component; easy handling of dry sorbent and by-product; and improved SCR catalytic life due to lowered SOx, HCl and particulate levels. CuO/3Al$_2$O$_3$ㆍ2SiO$_2$ catalyst impregnated ceramic candle filters showed a possibility of simultaneous treatment from results which have ascertained high removal efficiency at various combined gases conditions, and in pilot plant test for 3 months, NO conversion was showed 90% over.

• 한국의류산업학회지
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• 제23권6호
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• pp.844-851
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• 2021

Due to the increase in consumers' interest about well-being, interest in eco-friendly products has been increasing due to the harmful effects of various harmful substances contained in textile products and environmental issues. As a result, natural dyes of less potential risk than synthetic dyes and digital textile printing(DTP) textile products with less environmental pollution are drawing attention. However, due to the lack of evaluation criteria for DTP textile products with natural ink and the nature of many colors are stacked layer by layer for dying, the need for simultaneous analysis is emerging. To evaluate whether the natural dye is derived from natural ingredients, the biocarbon content is analyzed. However, in the case of ink made using natural dyes and DTP textile products using natural ink, it is difficult to analyze the biocarbon content due to the limitation of the presence of a small amount of dye contained therein. In this study, we were shown the possibility of natural derived verification by cross-checking the analytes of natural dyes (Persicaria tinctoria, an indigo dye; Dactylopius coccus, a light red; and Curcum longa L., i.e., turmeric) and natural ink with HPLC-MS/MS. The coefficient of determination was 0.999 or higher, the limit of quantification was 0.647-3.664 ㎍/L and a %RSD of each indicator material was less than 10. Then, the extraction amount of natural dyes for five patterned fabrics was analyzed.

• 한국수산과학회지
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• 제56권4호
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• pp.438-448
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• 2023

The concentrations of trace metals and organic matters in marine sediments collected from southeast Korean coastal areas were investigated. The primary purpose of this study was to evaluate the contamination status, spatial distribution and potential ecological risks associated with the physiochemical composition in the studied areas. We found that the concentrations of trace metals in marine sediments were as follows: Fe > Mn > Zn > Cr > Pb > Cu > As > Cd > Hg. According to the sediment quality guidelines (SQGs) of Korea, concentrations of Zn, Cr, Cu and Cd at all sampling sites were below threshold effect levels (TEL). However, concentrations of As, Hg, and Pb (i.e., at the 94-98% of sampling sites), were below the TEL. In addition, concentration factors (CF) in the surveyed area were found to be associated with low ecological risks, whereas As, Hg, and Cu showed moderate to high risk levels in some inner parts of the studied bays. Finally, the pollution load index (PLI) and ecological risk index (ERI) of the elucidated metals were linked to moderate ecological risk, pointing to the possibility of being deleterious to some benthic organisms.

• 한국토양비료학회지
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• 제50권5호
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• pp.472-481
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• 2017

Agricultural field near at the abandoned metal mine and industrial area has a high possibility to be polluted by heavy metals. However, concern about chemical properties including heavy metal concentration has been increased and biological properties such as soil respiration has been minimal in heavy metal polluted field. Therefore, main objective of this research was to evaluate soil respiration as an indicator of heavy metal pollution in agricultural field. Total of 60 sampling sites including each 30 sites of abandoned metal mine and industrial area were selected and heavy metal concentration, soil respiration, and chemical properties were measured. Results showed that heavy metal concentration in metal mine area was ranged Cu: $6.21~85.23mg\;kg^{-1}$, Pb: $23.84{\sim}1,044.72mg\;kg^{-1}$, As: $1.88{\sim}691.44mg\;kg^{-1}$, Zn: $18.72{\sim}527.55mg\;kg^{-1}$, Cd: $0.58{\sim}4.27mg\;kg^{-1}$, and Cu: $0.29{\sim}30.62mg\;kg^{-1}$, Pb: $4.41{\sim}19.77mg\;kg^{-1}$, As: $2.23{\sim}11.76mg\;kg^{-1}$, Zn $39.98{\sim}109.59mg\;kg^{-1}$, Cd $0.29{\sim}0.57mg\;kg^{-1}$ for industrial area respectively. While no sampling site was exceed the threshold value of each heavy metals in industrial field, metal mine area was highly polluted with Pb, As, Zn, and Cd. Soil respiration in the metal mine and industrial area was ranged $12.05{\sim}299.80mg\;O_2\;kg^{-1}$ and $27.68{\sim}330.94mg\;O_2\;kg^{-1}$, respectively. Correlation analysis between heavy metal concentration in soil and soil respiration showed that negative correlation was observed in metal mine area while no correlation was observed in industrial area. This result might indicate that as heavy metal concentration was increased, microbial activity in soil was decreased resulting decrease of soil respiration rate. Overall, soil respiration can be used as indicator of heavy metal pollution in soil and more biological properties need to be evaluated to better understand heavy metal pollution in soil.

• 한국조경학회지
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• 제32권3호
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• pp.43-50
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• 2004

This study looked into the water quality improvement effect of reed (Phragmites communis), bur reed (Sparaganium stoloniferum), Alisma canaliculatum, and Hydrocharis dubia in order to develop native hydrophytes suitable to natural-type wetlands for ecological restoration. The result confirms that the concentration of wastewater was lowered in most plants indicating a possibility in wastewater treatment. Among four species, reed (Phragmites communis) and bur reed (Sparaganium stoloniferum) were most effective in removing a majority of contaminants. Considering that reed (Phragmites communis) is a species that has been used most often among hydrophytes, bur reed (Sparaganium stoloniferum), which is a native species in Korea, showed equivalent level of outstanding effect. In the physiological and growing activity and its relations to water quality improvement effect, each species appeared differently. Reed (Phragmites communis) and bur reed (Sparaganium stoloniferum) were best also in physiological and growing activity. In the case of Hydrocharis dubia, growth was strong in polluted water environment but its physiological activity was poor, indicating that it was under stress. The growth and physiological activity of Alisma canaliculatum were also poor, indicating that it too is being stressed. However, measuring organic contents in the plants of each species shows that the organic contents of Alisma canaliculatum was high. Alisma canaliculatum is a species effective in removing pollutants in water, although it is under stress. A unique phenomenon in removing water pollution with plants is that each species removed different pollutants. In the case of Alisma canaliculatum, which was relatively poor in removing pollution, it was remarkable in reducing nitrogen and phosphorus. Hydrocharis dubia was also effective in eliminating floating matter.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.150-150
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• 2016

Mankind is enjoying a great convenience of their life by the rapid growth of secondary industry since the Industrial Revolution and it is possible due to the invention of huge power such as engine. The automobile which plays the important role of industrial development and human movement is powered by the Engine Module, and especially Diesel engine is widely used because of mechanical durability and energy efficiency. The main work mechanism of the Diesel engine is composed of inhalation of the organic material (coal, oil, etc.), combustion, explosion and exhaust Cycle process then the carbon compound emissions during the last exhaust process are essential which is known as the major causes of air pollution issues in recent years. In particular, COx, called carbon oxide compound which is composed of a very small size of the particles from several ten to hundred nano meter and they exist as a suspension in the atmosphere. These Diesel particles can be accumulated at the respiratory organs and cause many serious diseases. In order to compensate for the weak point of such a Diesel Engine, the DPF(Diesel Particulate Filter) post-cleaning equipment has been used and it mainly consists of ceramic materials(SiC, Cordierite etc) because of the necessity for the engine system durability on the exposure of high temperature, high pressure and chemical harsh environmental. Ceramic Material filter, but it remains a lot of problems yet, such as limitations of collecting very small particles below micro size, high cost due to difficulties of manufacturing process and low fuel consumption efficiency due to back pressure increase by the small pore structure. This study is to test the possibility of new structure by direct infiltration of SiC Whisker on Carbon felt as the next generation filter and this new filter is expected to improve the above various problems of the Ceramic DPF currently in use and reduction of the cost simultaneously. In this experiment, non-catalytic VS CVD (Vapor-Solid Chemical Vaporized Deposition) system was adopted to keep high mechanical properties of SiC and MTS (Methyl-Trichloro-Silane) gas used as source and H2 gas used as dilute gas. From this, the suitable whisker growth for high performance filter was observed depending on each deposition conditions change (input gas ratio, temperature, mass flow rate etc.).

• 한국가구학회지
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• 제26권1호
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• pp.71-76
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• 2015

It is important thing that air quality affects human health. And It is more important thing that Indoor Air Quality more affects human health than Outdoor Air Quality. The cause of that is indoor air pollutants are more absorbed than outdoor air pollutants. By the way, in case of Multi-use facility for example office, department store, school etc., it has a feature that there are more people than any other buildings. therethrough, effects of Indoor Air Quality of Multi-use facility affect more people's health than Indoor Air Quality of any other buildings. However, in multi-use facility, specifically retail store, chemical treated materials are used for interior finishing, showcase finishing and product finishing because esthetic element is more added for detention of customer. Consequently, in place where demands brisk sales, possibility that indoor air is polluted by VOCs is high. This study considered retail store's Indoor Air Quality. as result of experiment, figure of department store's air pollution exceed about 5~20 times in guideline of multi-use facility's Indoor Air Quality in any kind of shop of department store (guideline : $500{\mu}g/m^3$).

• 한국재료학회지
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• 제19권3호
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• pp.169-173
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• 2009

In chemistry, the study of sonochemistry is concerned with understanding the effect of sonic waves and wave properties on chemical systems. In the area of chemical kinetics, it has been observed that ultrasound can greatly enhance chemical reactivity in a number of systems by as much as a million-fold. Nano-technology is a super microscopic technology in which structures of 100 nanometers or smaller can be investigated. This technology has been used to develop $TiO_2$ materials and $TiO_2$ devices of that size. Thus far, electrochemistry methods and photochemistry methods have generally been used to create $TiO_2$ nano-size particles. However, these methods are complicated and create pollutants as a by-product. In the present study, nano-scale silver particles (5 nm) were prepared in a sonochemistry method. Sonochemistry deals with mechanical energy that is provided by the collapse of cavitation bubbles that form in solutions during exposure to ultrasound. $TiO_2$ powders 25 nm in size doped with Ag were formed using an ultrasonic sound technique. The experimental results showed the high possibility of removing pollution through the action of a photocatalyst. This powder synthesis technique can be considered as an environmentally friendly powder-forming processing owing to its energy saving characteristics.

• 수산해양교육연구
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• 제19권1호
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• pp.1-7
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• 2007

The purpose of this study was to investigate geochemical characteristics of surface sediments in the Keum river estuary adjacent to coastal area. For this study we collected the 21 surface sediments samples. Mean size of surface samples was $3.24{\sim}6.65{\phi}$ on inner estuary and was $2.15{\sim}3.42{\phi}$ on outside estuary. Surface samples were composed of silt on inner estuary and were composed of sand which was more larger than $4{\phi}$ on outside estuary. Most major elements except CaO, $Na_2O$ showed good relationships between variation of contents and grain size. Contents of $Al_2O_3$, $Fe_2O_3$, MgO, $K_2O$, $TiO_2$, $P_2O_5$ and $M_nO$ were increased predominately owing to the variation of mean size of surface samples. Contents of Co, Cr, Cu, Li, Sr, Zn, La, Ce, Pb, Rb, Nd have a good relationships with grain size but Ba, Th, Sm have not. All of major and minor elements contents except $K_2O$ and Ba were less than world mean contents of shallow surface sediments but apprehend a high pollution possibility on silt sediments in the estuaries.