• Journal of the Korean Ceramic Society
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• v.53 no.1
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• pp.7-12
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• 2016

In this paper, we have developed a simple, new and economical carbonation method to synthesize a pure form of aragonite needles using dolomite raw materials. The obtained aragonite Precipitated Calcium Carbonate (PCC) was characterized by XRD and SEM, for the measurement of morphology, particle size, and aspect ratio (ratio of length to diameter of the particles). The synthesis of aragonite PCC involves two steps. At first, after calcinated dolomite fine powder was dissolved in water for hydration, the hydrated solution was mixed with aqueous solution of magnesium chloride at $80^{\circ}C$, and then $CO_2$ was bubbled into the suspension for 3 h to produce aragonite PCC. Finally, aragonite type precipitated calcium carbonate can be synthesized from natural dolomite via a simple carbonation process, yielding product with average particle size of $30-40{\mu}m$.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.1
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• pp.13-18
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• 2006

The magnetic abrasive machining has been developed as a new finishing technology to obtain a fine surface of workpiece. In this paper, a static magnetic field method and a magnetic abrasive brush which has many technical advantages, are applied for the magnetic abrasive machining. In the experiment, some items such as finishing time, ratio of the magnetic abrasives to Fe-powder, motor revolutions per minute, and motor ratio revolutions per minute are tested. The results of this study have shown the fact that the burr height is mostly affected by the finishing time and the abrasive ratio. Also, it has been found that the magnetic abrasive machining is a possible new technology for the deburring.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.93.2-93.2
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• 2010

Recently, printing and coating technologies application fields have been expanded to the energy field such as solar cell. One of the main reasons, why many researchers have been interested in printing technology as a manufacturing method, is the reduction of manufacturing cost. In this paper, We fabricated CIGS solar cell thin film layer by doctor blade methods using synthesis of CIS precursor nanoparticles ink on molybdenum (Mo) coated soda-lime glass substrate. Synthesis CIS precursor nanoparticles ink fabrication was mixed Cu, In, Se powder and Ethylenediamine, using microwave and centrifuging. Using multi coating process as we could easily fabrication a fine flatness CIS thin-film layer ($0.7{\sim}1.35{\mu}m$), and reduce a manufacture cost and process steps. Also if we use printing and coating method and solution process in each layer of CIGS solar cell (electrode, buffer), it is possible to fabricate all printed thin-film solar cell.

• Journal of the East Asian Society of Dietary Life
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• v.10 no.4
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• pp.261-273
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• 2000

This paper was studied on the fruits in Dongeuebogam. Dongeuebogam is a representative ancient book of medicine, published in 1600. It mentioned to be thirty six kinds of fruits, with respect to taste, way of use, efficasy, facts of toboo were mentioned. Most of fruits have cold, warm character and sweet, sour taste and even nature which are based on Em yang oh hang theory. And they had been used for protection or cure of several kinds of diseases, and keeping health. The method of utilization of fruits presented in Dongeuebogam as medicine were food processing type, such as jook(porridge), tang(soup), jeup(juice), boonmal(powder), kunjo(drying), hoonyun(smoking).

• Computers and Concrete
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• v.21 no.2
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• pp.111-116
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• 2018

Establishment of test methods to assess the fresh properties of self-compacting concrete (SCC) are required to ensure the homogeneity in fresh and hardened states. This paper discusses the suitability of a simple test method for assessing the slump flow and stability of SCC by testing on self-compacting mortar (SCM) fraction. The proposed test method aims at investigating slump flow diameter test and sieve stability test of SCC by testing SCM fraction with a plunger penetration apparatus. A central composite modeling design was performed to evaluate the effects of water/cement ratio (W/C), superplasticizer dosage (SP) and powder marble content (MP) on slump flow diameter, stability and plunger penetration test of fresh SCC. The responses of the derived statistical models are slump flow (Sf), sieve stability (S) and plunger penetration (P). Relationships obtained in this study show acceptable correlations between plunger penetration test value and slump flow diameter test results and stability. It should note that the developed relationships are very useful to predict slump flow diameter and stability of studied SCC mixtures by carrying out a simple plunger penetration test on its mortar, which can save labour and time in laboratory experiments.

• Bulletin of the Korean Chemical Society
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• v.30 no.9
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• pp.2007-2010
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• 2009

Donepezil hydrochloride is a reversible acetylcholinesterase inhibitor that is used in the treatment of Alzheimer’s disease to improve the cognitive performance. It shows different crystalline forms including hydrates. Therefore, it is very important to confirm the polymorphic forms in the formulations of pharmaceutical materials because polymorphs of the same drug often exhibit significant differences in solubility, bioavailability, processability and physical/chemical stability. In this paper, four different forms of donepezil hydrochloride were prepared and characterized using X-ray powder diffraction, Fourier transform infrared, and solid-state nuclear magnetic resonance (NMR) spectroscopy. This study showed that solid-state NMR spectroscopy is a powerful technique for obtaining structural information and the polymorphology of pharmaceutical solids.

• Journal of Environmental Science International
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• v.15 no.12
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• pp.1199-1203
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• 2006

This paper analyzes the separation efficiency of vehicles mat residual product, and caloric value, element analysis and heavy metal of separated PE & PVC mat residual product. A results of separation efficiency, fiber fraction of PE & PVC mat residual product was analyzed 71.9% and 18.6%, respectively. Caloric value of PE & PVC mat residual product was analyzed 3,894kca1/kg and 10,203kca1/kg, respectively. A results of element analysis, main component of PVC mat were carbon(33.2%) and oxygen(21.0%), and main component of PE mat fiber were carbon(75.4), hydrogen(11.3%) and oxygen(9.1%). Lead and cadmium concentration of PVC powder was detected 98.9mg/kg and 19.8mg/kg, but Lead and cadmium concentration of fiber was detected 15.7mg/kg and 6.1mg/kg.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.6
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• pp.78-84
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• 2000

In this paper, the diagnosis technique was proposed by measuring and analyzing ultrasonic signals caused by partial discharge on the interface of cable joint. The measured ultrasonic signal was filtered by wavelet transform, and then the dominant signal of filtered signal was analyzed by fast fourier transform(FFT). As a result, it was confirmed that different characteristics were obtained with the moisture and the metal powder on the interface of cable joint and with voltage increment.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.434-438
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• 2003

This paper present an investigation of the influence on the PFC(power factor correction) circuit with characteristics variation of MPP (Molybdenum permalloy powder) core. The experiment results of the 1.5kW class Boost converter for PFC rectifier with the average current mode control are evaluated to verify the influence on the PFC converter with inductance variation of the MPP core. As a results, it is shown that the ripple of the inductor using a MPP core increase with output power of the converter.

• Proceedings of the Korea Concrete Institute Conference
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• 1992.10a
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• pp.1-4
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• 1992

This paper deals with the effect of siliceous slurry coating on concrete microstructure under damp environment. This material is mixed inorganic powder consisted of silica, cement and fine sand and water. Water pressure was given on the coated surface of concrete. for estimation on effect of siliceous slurry coating, microstructure of coated concrete was observed through SEM, and chemical components of crystals were analyzed with X-ray diffraction and EDX. A number of needle and fibrous crystals were produced in microstructure. And based on X-ray diffraction and EDX, needle crystal mainly consist of Al, Si, and Ca, and it is concluded to be ettringite. Fibrous crystals consist of Ca and Si, and it to be calcium silicate hydrate.