• Bulletin of the Korean Chemical Society
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• v.30 no.10
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• pp.2398-2402
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• 2009

Ten steroidal compounds as impurities in canrenone were isolated from the enriched mother liquor by using various chromatographic methods. Their structures were elucidated by spectrometric analysis, among which three new compounds were characterized as 3-(3-oxo-7$\alpha$-(ethoxycarbonyl)methyl-17$\beta$-hydroxy-4-androsten-17$\alpha$-yl) propionic acid $\gamma$-lactone (1), 3-(3-oxo-7$\alpha$-ethoxy-17$\beta$-hydroxy-4-androsten-17$\alpha$-yl) propionic acid $\gamma$-lactone (2) and 3-(3-oxo- 5$\beta$-propionic acid-$\gamma$-lactone-6$\beta$,17$\beta$-hydroxy-4-androstan-17$\alpha$-yl) propionic acid $\gamma$-lactone (3).

• Journal of Welding and Joining
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• v.16 no.2
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• pp.122-128
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• 1998

This investigation was performed to collect fundamental informations concerning the behavior of glass solders on ceramic joining process. The wettability of glasses on two types of alumina was evaluated by sessile drop method. SiO$_2$-CaO-Al$_2$O$_3$system glasses were selected as solder glasses, and alumina that have different purities were used for substrate materials. It is indicated that contact angles of glasses on 99% purity of alumina substrate do not change as increasing time at elevated temperature, however the contact angles on the 92% purity of alumina substrate exhibit the strong time dependency. The time-dependent property on 92% alumina was due to the interlayer reactions occurred between the glass solder and impurities on the substrate.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.10 s.253
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• pp.1328-1334
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• 2006

In the rolling mills for sheet metal rolling, paper rolling and etc., the impurities of roller surface have crucial effects on the surface quality of the products obtained by rolling. The Roll Cleaner is a device to remove impurities on roller surface during a rolling operation. Nip Pressure means the line pressure interacted between the roll cleaner blade and the roller surface. The nip pressure is the most important parameter which decides the performance of roll cleaner, and it depends upon several factors including the cleaner design and its blade stiffness. This study, first, analyzes the mechanism of the nip pressure generation for a roll cleaner designed commercially, which is an crucial process for effective design of roll cleaners. Second, the technique for the measurement of nip pressure is developed, which is useful to verify the performance of roll cleaners and to setup them properly at factory floor.

• Journal of the Korean institute of surface engineering
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• v.30 no.6
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• pp.412-418
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• 1997

The surface appearance of zinc coating chromated electrochemically was investigated with the concentration of impurities in chromating solution. The chromium content and yellowness of chromated film decreased with more than 0.1g/1 Zn in chromating solution, while white ness of it increased slightly. The chromium content and whiteness of chromated film also decreased with more than 0.1g/1 Fe in chromating solution, but the yellowness of it increased. Chromium content, whiteness and yellowness of chromated film decreased slightly with more than 0.5g/1 $Cr^{3+}$<\TEX>. But the chromium content and surface appearance of chromated film are not influenced with less than 1.0g/1 Pb in chromating sloution.

• Journal of the Korean Ceramic Society
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• v.15 no.4
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• pp.199-204
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• 1978

In the present investigation, refined alumina obtained from alunite locally available was used as a aluminous source to synthesize monocalcium aluminate $(CA)_3$ the major mineral constituent of alumina cement. The influence of $SiO_2$ and $Fe_2O_3$ contents on the formation of monocalcium aluminate was studied by X-ray diffraction analysis mainly. About 0.8-1.0 of $Al_2O_3/C_3O$ mol ratio and less than 4 percent of $SiO_2$ were desirable for the effective formation of CA. The small amount of alkali and sulphur contents contained in refined alumina from alunite as the impurities were affected to form $C_4A_3S$ and $C_3S_2$, disadvantageous compounds for the alumina cement, therefore the impurities should be restricted in minimum content as possible.

• Journal of the Korean Ceramic Society
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• v.27 no.8
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• pp.1011-1019
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• 1990

Pyrophyllite, which has low impurities, was used in the synthesis of mullite to decrease the glass phase, which can be formed from impurities such as alkali and alkali earth elemetns present in raw materials. But, as pyrophyllite has less alumina content than other aluminosilicate materials such as kaolin, more alumina sources were needed in the synthesis of mullite. In other to investigate the effect of particle size of alumina sources on the mullitization of pyrophyllite, aluminum hydrate gel and activated alumina were used. When activated alumina, which has large particle size, was added to pyrophyllite, mullitization was not fully accomplished regardless of temprature. In the case of aluminum hydrate gel, which has small particle size, the maximum yield of mullite was about 90.3% at 1700$^{\circ}C$, and grain size of mullite was larter than the case of activated alumina was added.

• Applied Science and Convergence Technology
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• v.23 no.3
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• pp.113-127
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• 2014

For more than five decades, silicon has dominated the semiconductor industry that supports memory devices, ICs, photovoltaic devices, etc. Photoluminescence (PL) is an attractive silicon characterization technique because it is contactless and provides information on bulk impurities, defects, surface states, optical properties, and doping concentration. It can provide high resolution spectra, generally with the sample at low temperature and room-temperature spectra. The photoluminescence properties of silicon at low temperature are reviewed and discussed in this study. In this paper, silicon bulk PL spectra are shown in multiple peak positions at low temperature. They correspond with various impurities such as In, Al, and Be, phonon interactions, for example, acoustical phonons and optical phonons, different exciton binding energies for boron and phosphorus, dislocation related PL emission peak lines, and oxygen related thermal donor PL emissions.

• Journal of the Korean Ceramic Society
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• v.20 no.1
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• pp.13-18
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• 1983

The investigations have been carried out to study the characteristics of limestone using in Korean cement industry with prime interests in the dissociation and thermal phase changes of limestone between 90$0^{\circ}C$ and 140$0^{\circ}C$ The range of decomposition temperature of limestone was 840-87$0^{\circ}C$ and it was considered that the temperature was lowered by impurities in the limestone. The more the impurities and the finer the grain size of quartz in limestone the lower temperature was applied in forming $C_2S$ mineral the temperature of about 100$0^{\circ}C$. The major clinker minerals such as $C_3S$, $C_2S$, $C_3A$ and $C_4AF$ were formed in most of limestone when the firing temperature was up to 130$0^{\circ}C$.

• Journal of the Korean institute of surface engineering
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• v.13 no.4
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• pp.211-220
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• 1980

Internal stress of electrodeposited metals affect physical and mechanical characteristics of deposits. Internal stress of nickel deposits was reviewed intensively. Important outcomes are as follows. Substrate have an important effect on internal stress of electrodeposit. Origin of its internal stress could be explained mismatch of crystal lattice and coalescence of crystallites. When surface cleaning is not satisfying, instantaneous stress is low but the electrodeposited layer being thickened increasingly stress become to high and peeling phenomenon occurs. Effect of current density and temperature on internal stress is variable. Internal stress increases rapidly at pH 5 and above because of codepositing colloidal materials caused hydrolysis. Concentrations of nickel ion and $H_3BO_3$ ion affect little on internal stress and solution which contains impurities tend to increase stress. Especially impurities of $H_2O_2$ and iron ion have a great effect on internal stress. Additives are divided in two kind. One is increasing tensile stress another is increasing compressive stress. Concentrations of additives have a great effect on internal stress.

• Resources Recycling
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• v.5 no.2
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• pp.57-62
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• 1996

The regeneration of wastc piddlng acid from ironmaking industry produces Iron oxides as by products which are used for pigments and raw matcrial of ferrite. Thc impurilies level of iron axides for ferrile arc strictly regalated. Filtrat~on, adsorption medw technique, Fe leaching and ncutralizaiion wcre tried in order to remove silica impurities in the wasb pickling acid solution.