• Journal of the Semiconductor & Display Technology
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• v.10 no.4
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• pp.31-35
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• 2011

For high efficiency of Si-cells, Si wafers were textured by the KOH and NaOH etching solution to decreas the reflectance at surfaces of the cells. The textured surfaces were shown various types such as isotropic and anisotropic depending on the etching solution. The reflectance at sample of an anisotropic form with pyramid type was lower than that of isotropic form. The surface with isotropic form of general tiny circles on the surface increased the efficiency, however, the reflectance of it was increased. The efficiency was increased on surface with low roughness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.338-339
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• 2005

The wider surface of the aluminum foil, electrochemically very important and it is necessary to increase the surface area. A study has been made of the fabrication condition for etching cube texture of high purity aluminium foil and of electrochemical etching of the aluminium foil. In the present work, it is shown there exists a relation between the influence of the pre-treatment time in the NaOH & HCI solution and $H_2SO_4$ concentration in the conversion solution. Also effect of temperature during AC etching was also studied. Result of the etched aluminum film is shown in the typical SEM images. Its electrochemical characteristics were investigated by cyclic voltammetry. And effects of current density and frequency is also reported. Cyclic voltammogram showed that the protective oxide film was formedon the inner surfaces of etch pit. the frequency influence resistance of oxide film in AC etching.

• Journal of Radiation Protection and Research
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• v.13 no.2
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• pp.57-66
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• 1988

A series of experiments is performed to measure radon concentration in the near-surface soil gas at the four locations (Cheju-Si, Seoguipo-Si, Taejeong-eup, Seongsan-eup) in Cheju Island, using CR-39 detectors placed inside radon cups. Two types of radon cups are installed in shallow holes of about 15 cm in diameter and 50cm in depth. The optimum etching conditions, i.e., the concentration of NaOH solution, etchant temperature and etching time, are found to be 625N, $70^{\circ}C$ and 5.5 hours for CR-39 detectors. A typical conversion factor of radon cup is calculated as $$1track/mm^3{\cdot}30day=0.059Bq/{\ell}$$. Average radon concentrations over 30 days measured in Cheju Island from May 1, 1987 to April 23, 1988 are $3.1{\pm}0.3Bq/{\ell}$ for open radon cups and $1.7{\pm}0.2Bq/{\ell}$ for closed radon cups.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.6
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• pp.286-290
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• 2012

Boehmite (AlOOH) powder was synthesized using waste aluminium etching solution. In waste solution, precipitated phase was gibbsite ($Al(OH)_3$), and boehmite (AlOOH) phase was obtained at pH of 7 and 8 controlled by addition of acid. Boehmite powder was obtained by washing process to remove the Na ion in precipitated solution. Mean particle size of obtained powder was 40 nm. Boehmite phase transformed to ${\alpha}-Al_2O_3$ phase via ${\gamma}-Al_2O_3$, ${\delta}-Al_2O_3$, and ${\Theta}-Al_2O_3$.

• Progress in Medical Physics
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• v.1 no.1
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• pp.97-107
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• 1990

A method of detecting charged particles in an allyl diglycol carbonate material (PN-3) which is available, amorphous, optically clear and thermoset plastic in which nuclear particle tracks could be revealed by etching in hot NaOH solutions, has been investigated. It has been applied to the study of alpha particle tracks over an energy range of 3.17～5.49 MeV which has been obtained after having passed through several sheets of polycarbonate. The dose equivalent rate of the alpha source was calculated and the spark chamber was used in order to measure the range of alpha particles after having passed through different number of absorbers. The etching characteristics and the detection response of PN-3 have been studied as a funcion of lengths of etched tracks against the parameters of energies and of the track etching rate(V$_{T}$). The investigation of the etching process for alpha particles in the PN-3 provided the most interesting results.s.

• Biomedical Science Letters
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• v.14 no.2
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• pp.105-113
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• 2008

The objective of this study was to evaluate the influence of surface modifications on the bonding characteristics and cytotoxicity of specific titanium porcelain bonded to milling titanium and cast titanium. Milling titanium and cast titanium samples were divided into 8 test groups. These groups are as follow: i) sandblasted with particles of different size of $220{\mu}m\;and\;50{\mu}m$, ii) different sequences of sandblasting treatment and etching treatment, iii) etched with different etching solutions, and iv) preheated or not. The surface characteristics of specimens were characterized by the test of mean roughness of surface and SEM. The bond strength of titanium-ceramic systems was measured by using three-point bending test and SEM. The results show that the mean roughness of surface of sample sandblasted with $220{\mu}m$ aluminum oxide increased and bond strength were higher than sample sandblasted with $50{\mu}m$ aluminum oxide. The mean roughness of surface decreased, but the bond strength increased when the samples sandblasted with $220{\mu}m$ aluminum oxide were preheated. The sample sandblasted with $220{\mu}m$ aluminum oxide after oxidized with occupational corrosive agent I (50% NaOH, 10% $CuSO_4{\cdot}5H_2O$) and II (35% $HNO_3$, 5% HF) showed higher bond strength than sample oxidized with 30% $HNO_3$ after sandblasted with $220{\mu}m$ aluminum oxide. Group NaCuNF220SP (milling Ti: 35.3985 MPa, casting Ti: 37.2306 MPa) which was treated with occupational corrosive agent I (50% NaOH, 10% $CuSO_4{\cdot}5H_2O$) and II (35% $HNO_3$, 5% HF), followed by sandblasting with $220{\mu}m$ aluminum oxide and preheating at $750^{\circ}C$ for 1 hour showed the highest bond strength and significant differences (P<0.05). The method for modifying surface of titanium showed excellent stability of cells.

• Applied Chemistry for Engineering
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• v.32 no.1
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• pp.20-27
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• 2021

Effects of the etching treatment of SAPO-34 catalyst were investigated to improve the catalytic lifetime in DTO reaction. The aqueous NH3 solution was a more appropriate treatment agent which could control the degree of etching progress, compared to that of using a strong acid (HCl) or alkali (NaOH) solution. Therefore, the effect on characteristics and lifetime of SAPO-34 catalyst was observed using the treatment concentration and time of aqueous NH3 solution as variables. As the treatment concentration or time of aqueous NH3 solution increased, the growth of erosion was proceeded from the center of SAPO-34 crystal plane, and the acid site concentration and strength gradually decreased. Meanwhile, it was found that external surface area and mesopore volume of SAPO-34 catalyst increased at appropriate treatment conditions. When the treatment concentration and time were 0.05 M and 3 h, respectively, the lifetime of the treated SAPO-34 catalyst was the longest, and was significantly enhanced by ca. 36% (based on DME conversion of > 90%) compared to that of using the untreated catalyst. The model for the etching progress of SAPO-34 catalyst in a mild treatment process using aqueous NH3 solution was also proposed.

• Clean Technology
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• v.14 no.2
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• pp.123-128
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• 2008

The waste solution, which was discharged from the recovery process of LCD etching solution, consists of 15 wt% nitric acid and 20 wt% acetic acid. In this study, it was conducted to separate acid individually from the mixed acid by vacuum evaporation under -760 mmHg gauge and at $40^{\circ}C$. We have investigated evaporation behavior of acid as a function of temperature. There have been problems that tiny amount of nitric acid were evaporated simultaneously above $33^{\circ}C$. Thus, efforts were conducted to recover acetic acid by vacuum evaporation with adding $H_2O$, waste mixed acid and 20 g/L NaOH for a curb on evaporation of nitric acid. By adding $H_2O$, evaporation of nitric acid was reduced from 7% to 0.78%. However, it was reduced from 7% to 0.25% by adding mixed acid. In view of the results achieved so far, we may expect to separate the etching solution individually by controlling vacuum conditions.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.508-512
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• 2004

An ultra-sharp tungsten electrode for field emission was manufactured by using an electrochemical etching method, and its beam characteristics were investigated. KOH and NaOH were the electrolytes used in this research, and the taper length of the tip varied form 150 $\mu\textrm{m}$ to 250 $\mu\textrm{m}$ according to the applied voltage and the concentration of the electrolyte. The electron-beam stability was measured to be within 5% for a total emission current of 5 ${\mu}\textrm{A}$ during 4 hours of operation, and the Ignition voltages were found to be ∼300 V. The tip radius was experimentally found to be 250${\AA}$ from a linear fitting of Fowler-Nordheim plots, which was in remarkably good agreement with that of the image size from scanning ion-microscopy.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1430-1431
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• 2006

We investigated the formation of 2-dimension hologram grating by means of selective etching characteristic and photo-expansion effect according to photo irradiation on amorphous As-Ge-Se-S thin film. By method of phase holography, we made the 2-dimensional hologram grating by each (S:P) and ($+45^{\circ}:-45^{\circ}$) polarized beam with DPSS laser(532nm) and He-Ne laser(632nm). A recording property was observed at each polarized beam through 2-dimensional hologram surface relief grating. Chalcogenide thin film was etched selectively by NaOH solution after the formation of 1-dimensional diffraction grating. And then etched sample was rotated 90 degree to fabricate 2 dimensional hologram grating. We found that it was observed the formation of 2-dimensional hologram grating by AFM(Atomic Force Microscopy).