• Journal of the Korean Chemical Society
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• v.54 no.5
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• pp.603-610
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• 2010

The potential feasibility of Maghnia clay as adsorbent to remove three cationic dyes (methylene blue (MB), neutral red (NR) and malachite green oxalates (MG)) from aqueous solution was investigated at various operating parameters such as contact time, pH, initial dye concentration and adsorbent dose. Optimum pH values for dyes adsorption were 6 for NR and 7 for MB and MG, respectively. Maximum adsorption of dyes, i.e. $\geq$ 90% has been achieved in aqueous solutions in 60 minutes. The adsorption of dyes followed the pseudo-second-order rate equation.

• Proceedings of the Membrane Society of Korea Conference
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• 1994.10a
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• pp.12-13
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• 1994

막분리 공정을 이용하여 수용액상에 존재하는 유기 오염물질을 제거하기 위해서는 역삼투나 투과중발법의 도입이 필요하다. 그러나 두가지 공정 모두 대단위의 처리를 위해서는 막대한 시설$\cdot$가동비를 필요로 한다. 특히 물속에 녹아 있는 방향족 유기물들은 심각한 환경오염의 주범이 되고 있음에도 불구하고 효율적이고 경제적인 처리가 거의 이루어지지 않고 있다. Micllar enhanced ultrafiltration (MEUF) 공정은 오염물이 녹아있는 수용액에 계면활성제를 투입하여 오염물이 포함된 micelle을 형성시킨 후 이를 한외여과함으로써 계면활성제와 유기물을 동시에 제거하는 공정이다[1]. 이 공정을 이용함으로써 한외여과막의 종류, 유기 오염물의 특성에 다른 제거 효율의 변화나 최적 조업 조건 등에 대한 체계적인 연구[3,4]가 미흡한 실정이다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.706-708
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• 2004

본 논문에서는 코어를 이용한 주조에 대한 계산 기하학 문제를 다룬다. 주조는 녹인 물질을 주형 안에 주입해서 응고시킨 후 주형을 제거하는 방법으로, 주물은 주형의 내부 공동의 모양을 갖게 된다 코어는 두 개의 주형으로는 만들 수 없는 물체를 주조하기 위한 부속물로서, 두 개의 주요 주형이 제거되는 방향과는 다른 방향으로 제거된다. 따라서 코어를 사용하면 두 개의 주형으로는 제작할 수 없는 물체를 주조로 만들 수 있게 된다. 본 논문에서는 어떤 물체가 주어졌을 때, 코어를 사용하는 주조로 만들 수 있는지를 증명 할 수 있는 필요충분 조건을 제시한다 또한, 다면체의 물체를 테스트하는 O(n$^3$ logn)의 알고리즘과, 동일한 시간 안에 주형의 형태를 만들어낼 수 있는 알고리즘을 제시한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.127-127
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• 2004

입자분사 가공(abrasive jet machining)은 과거에는 녹(rust) 도색(painting)의 제거 흑은 디버링(deburring), 표면 처리 등의 용도에 국한되어 사용되어졌다. 한편 최근 들어 반도체 제작공정이나 MEMS 공정 등에 적용되는 실리콘(silicon) 등의 세라믹 재료의 미세가공분야가 주목받고 있으며, 따라서 이와 관련된 많은 연구가 진행되고 있다. 한편, 세라믹 재료는 파괴인성이 매우 낮고 취성이 강하기 때문에 크랙발생 후 큰 응력이 연속적으로 주어지면 크랙은 음속으로 진행되어 파단 되는 특성이 있어서 일반적인 기계가공이 매우 어렵다.(중략)

• Journal of the Korean Society of Safety
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• v.19 no.2
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• pp.41-46
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• 2004

The formation of rust on metallic substrate is known to cause the damages and destructions of raw materials, which is one of the leading reasons of sturctural collapses and many kind of hazards in modern industry. Polymer gels with rust removing effects were compounded in this study by employing various kinds of acids like hydrochloric acid, phosphoric acid, gluconic acid, oxalic acid as the rust removing ingredients. TEA(Triethanolamine) as dispersant and hydrophilic chemical were used for effective gelation of acids. Also corrosion inhibitor was added to enable the coating effect and to improve rust removing effect on metallic surface. In order to investigate the rust properites on metallic substrate, artificial rusts were prepared in salt solution, using iron, copper, aluminium and brass as the base metals. The properties of gel compounds were checked by gelation, pH, viscosity, morphology property and rust removing test. Developed gel compounds in this study have a good rust removing property, showing a strong adhesion on horizontal and vertical metallic surface, and can be easily rinsed off by water.

• Journal of Ocean Engineering and Technology
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• v.19 no.6 s.67
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• pp.72-77
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• 2005

The materials used in a ship screw propeller are commonly made with brass. The seawater corrosion and seawater cavitation of the screw propeller reduces the propulsive performance of the ship. In screw manufacturing, the corrosion rust of the screw propeller is removed through a hand grinding method. The grinding process produces dust of the heavy metals from the brass. The dust creates a poor working environment that is harmful to the health of the workers. An automatic corrosionrust removing apparatus, using a blasting method, was developed for the improvement of screw polishing conditions and its working environment. The performance of this apparatus was investigated by surface roughness, weight loss rate, hardness, electrochemical corrosion resistance, and cavitation erosion, after removing of the corrosion rust under various blasting conditions. Two medias of alumina and emery were used in this experiment. The surface roughness and hardness of the screw were improved by this apparatus. The electrochemical corrosion potential (Ecorr) and current density (Icorr) were measured by the dynamic polarization method, using a potentiostat,under the conditions of surface polishing with grinding, blasting, wire brushing, and fine sand papering. The test results prove that the new corrosion rust-removing apparatus improves the surface performance of a screw propeller.

• Journal of the Korean Chemical Society
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• v.30 no.5
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• pp.465-474
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• 1986

The solvent extraction and cleanup processes for the simultaneous gas-liquid chromatographic determination of 11 kinds of organophosphorous pesticide residues in crops were investigated. The extracts dissolved with acetone were partitioned with petroleum ether after adding saturated NaCl solution. Evaporated the partitioning solvent, the residue was dissolved in methylene chloride and eluted through mixed adsorbent (1 : 2 : 4 of activated carbon, magnesia and diatomaceous earth) with methylene chloride as an eluent. The pesticides recovered were 82∼105% and the impurities were effectively removed.

• Korean Chemical Engineering Research
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• v.44 no.2
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• pp.136-148
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• 2006

A foundry makes various machinery parts made by iron. For manufacturing machinery parts, they usually uses wooden mold with molding sand and pour the molten iron into wooden mold through inlet. A foundry have many processes including Furan process, In Furan process workers prepares a wooden mold in the molding sand. So they fixes wooden mold in sand housing and then they fill the molding sand in the sand housing. Molding sand should be sticky enough to sustain the shape of wooden mold, so several materials are needed to prepare the suitable molding sand. The first step of Furan process is making the molding sand with molding sand and Voltaic Organic Compounds (VOC) and the second step of Furan process is pour the molding sand into the wooden molding housing. This two step of process generated noxious VOC and various size of dust. So the process is very dirty and dangerous one. Because of these, Workers frequently shrink out of the plant. The company related with foundry usually faced on the difficult situation for engagement and always have shortage of hiring problem. Through this study, we developed a system which removes toxic VOC and dust simultaneously. We design and construct real system and install it at real plant. Before setting up this system, the working surroundings VOC (for formaldehyde) 15 ppm and Dust(for $PM_{10}$) $8,000{\mu}g/m^3$. After setting up this system, working surroundings is improved by VOC (for formaldehyde) 0 ppm, Dust(for $PM_{10}$) $4{\mu}g/m^3$, and the work evasion factor is removed. So we contribute to solve hiring problem of this company and increasing the productivity also.

• Journal of the Korean Chemical Society
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• v.29 no.5
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• pp.496-502
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• 1985

The solvent extraction and cleanup processes for the simultaneous gas-liquid cliromatographic determination of 16 kinds of organochlorine pesticide residues were investigated. The pesticides were extracted out from-various crops with the aqueous acetone solution acidified (pH < 1.5) by adding conc. $H_3PO_4$. Most of the pesticides were partitioned from the solution with petroleum ether. Evaporated the extracting solvent, the residues were dissolved in ethylether-petroleum ether (6 : 94) eluent and eluted through the Florisil column activated at 650$^{\circ}$C for 2.5hrs. The extraction efficiency was over 94% and impurities were effectively removed by the column chromatography.

• 보존과학연구
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• s.33
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• pp.125-148
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• 2012

The Octagonal nine storied pagoda of Woljeongsa Temple consists mainly of granite with the rockforming minerals quartz, plagioclase, microcline, and biotite. The surface of the stone stupa is light brown that has been discolored by the rust from the metal ornament and aids. The surface of the stylobate and roof stone is colonized by biological contaminants. Therefore, a comprehensive deterioration diagnosis was carried out in this study, and conservation treatment was conducted. It was proven that the $Fe^{2+}$ yield increases depending on the count of poultice used with oxalic acid, but the $Mg^{2+}$, $Al^{3+}$, and $Ca^{2+}$ yields were marginal following the preliminary test. Therefore, the use of poultice is an effective way of removing the rust, and only marginally influences the rock. The biological contaminants were removed through dry cleaning, and the soil located under the contaminants was removed through wet cleaning. Based on this, the dry and wet cleaning of all the biological contaminants, and the use of poultice with oxalic acid, were done to remove the rust. For the conservation treatment of the metal ornament, the rust was removed through physical cleaning, and anticorrosion treatment was performed on the iron ornament using Renaissance wax and copper ornament by BTA.