• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.194-199
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• 2011

This study has been carried out to evaluate the performance of $PbO_2$ electrode for the purpose of degradation of N,N-Dimethyl-4-nitrosoaniline (RNO, indicator of OH radical), generation of ozone and decolorization of Rhodamine B (RhB) in water. The effect of the applied current (0.2~1.2 A), electrolyte type (NaCl, KCl and $Na_2SO_4$), electrolyte concentration (0.0~2.5 g/L) and solution pH (3~11) were evaluated. Experimental results showed that RhB and RNO removal were increased with the increase of current, NaCl dosage and decrease of pH. Ozone generation tendencies appeared with the almost similar to the RhB and RNO degradation, except of solution pH (Ozone generation was increased with increase of pH). Optimum current for RhB degradation and consumption of electric power was 1.0 A. The RhB degradation with Cl type electrolyte were higher than that with the sulfate type. Optimum NaCl dosage for RhB degradation was 1.0 g/L.

• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.181-186
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• 2008

2,5-Di-(2'-hydroxyethoxy)-4'-nitrostilbene (3) was prepared and polycondensed with terephthaloyl chloride, adipoyl chloride, and sebacoyl chloride to yield novel T-type polyesters (4-6) containing the NLO-chromophores dioxynitrostilbenyl groups, which constituted parts of the polymer backbones. Polymers 4-6 are soluble in common organic solvents such as acetone and N,N-dimethylformamide. They showed thermal stability up to 260 oC in thermogravimetric analysis with glass-transition temperatures obtained from differential scanning calorimetry in the range 90-95 oC. The second harmonic generation (SHG) coefficients (d33) of poled polymer films at the 1064 nm fundamental wavelength were around 1.42 ´ 10-9 esu. The dipole alignment exhibited high thermal stability up to 5 oC higher than glass-transition temperature (Tg), and there was no SHG decay below 100 oC due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications.

• Proceedings of the Korea Crystallographic Association Conference
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• 2002.11a
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• pp.18-18
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• 2002

Although it was suggested in 1962 that an efficient wavelength conversion could be achieved using ferroelectric crystals of periodic 180° domains, it was not until 1990's that quasi-phase-matching (QPM) became realized, as technology for periodic poling of LiNbO₃ crystals was readily available. Since ferroelectric domain inversion brings about change of the sign of second-order nonlinear susceptibility, periodically poled ferroelectric structures provide an ideal way of achieving QPM for second-harmonic generation and optical parametric oscillation. Periodically poled ferroelectric domains can also be utilized for optical devices, such as Brags electrooptic modulators. fabrication of stable periodic domain structures depends on a number of poling parameters of a ferroelectric crystal, such as coercive field, internal field and electrical conductivity. We present poling kinetics of KNbO₃ crystals, which involve domain nucleation and growth, backswitching, relaxation of internal field. Optimum poling conditions were established by designing a proper wave shape of external field. We demonstrate an efficient second-harmonic generation using QPM in a periodically poled KNbO₃ crystal.

• Korean Journal of Optics and Photonics
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• v.12 no.1
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• pp.48-54
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• 2001

We investigate the generation of the dark spatial soliton and its role of wave guiding in Fe doped$LiNbO_3$ A cw Ar+ laser of 488 nm is used for the generation of the dark spatial soliton. The generation of the dark spatial soliton is observed even at the laser intensity as low as 10 mW/cm2. The self-defocusing effect is observed when the direction of the intensity variation is parallel to the optic axis, while it can't be seen when perpendicular to the axis. So, it is verified that the refractive index change is generated parallel to the optic axis. When 633 nm He-Ne laser beam is injected into the dark spatial soliton, the beam propagates just as in the diffraction free medium. So, it is verified that the dark spatial soliton can act as a waveguide.eguide.

• KSCI Review
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• v.2 no.1
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• pp.121-129
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• 1995

Fault simulation of logic circuits is an important part of the test-generation process. It is used for the propose of generation fault dictionaries or for the verification of the adequacy of tests. In this paper, a backtrace fault simulation is proposed to test generation. This is consists of 3 part ; initialization phase for given circuit, backtrace fault simulation phase to find fault list and reevaluation phase to list event. The main idea of this algorithm is to retain a minimum fault list by cutting uncontrollable lines of path when a logic event occurs in backward tracing phases. And the simulator is revaluates a fault list associated with the output of an element only if logic event occurs at any of its inputs when a list event occurs at one of its primary inputs. It reguires a O(n) memory space complexity. where n is a number of signal lines for the given circuits. Several examples are given to illustrate the power of this algorithm.

• Environmental Engineering Research
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• v.25 no.3
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• pp.324-334
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• 2020

Tannery wastewater is known to contain high concentrations of organic compounds, pathogens, and other toxic inorganic elements such as heavy metals, nitrogen, sulfur, etc. Biological methods such as aerobic and anaerobic processes are unsuitable for tannery wastewater treatment due to its high salinity, and electrochemical oxidation offers a promising method to solve this problem. In this study, raw tannery wastewater treatment using DSA® Ti/RuO₂, Ti/IrO₂ and Ti/BDD electrodes with continuous flow systems was examined. Effects of current densities and electrolysis times were investigated, to evaluate the process performance and energy consumption. The results showed that a Ti/BDD electrode is able to reach higher treatment efficiency than Ti/IrO₂, and Ti/RuO₂ electrodes across all parameters, excluding Total Nitrogen. The main mechanism of tannery wastewater oxidation at a Ti/BDD electrode is based on direct oxidation on the electrode surface combined with the generation of oxidants such as °OH and Cl₂, while at DSA® Ti/RuO₂ and Ti/IrO₂ electrodes, the oxidation mechanisms are based on the generation of chlorine. After treatment, the effluents can be discharged to the environment after 6-12 h of electrolysis. Electrooxidation thus offers a promising method for removing the nutrients and non-biodegradable organic compounds in tannery wastewater.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.394-394
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• 2010

Ammonium ion (${NH_4}^+$) was suggested as the origin of interstellar $6.85\;{\mu}m$ band. Early study, in which organic molecule and water ice film mixtures were photolyzed so that organic acids could be produced, explained the generation of ${NH_4}^+$ from the reaction of photogenerated organic acid and ammonia ($NH_3$). However, the observed abundance of organic acids or their counter-anions are not so high in interstellar ice and not enough to protonate $NH_3$ into ${NH_4}^+$ in the observed level. Because of the shortage in photogenerated organic acids, the candidate of acid which protonates $NH_3$ should be modified. Here, we prepare $NH_3/H_2O$ binary mixtures and photolyze them with vacuum ultraviolet (VUV, peak at 10.6 and 10.0 eV). We find the ammonium ion (${NH_4}^+$) from photolyzed mixture by using low energy sputtering (LES) and reflection absorption IR spectroscopy (RAIRS). As a hydronium ($H_3O^+$) can be produced by UV irradiation and protonate bases, ${NH_4}^+$ may be formed from the reaction of photogenerated $H_3O^+$ and $NH_3$. We show the generation of ${NH_4}^+$ without any kind of organic molecules or acids, and it may explain the relatively high abundance of ${NH_4}^+$ compared to the counter-anions or organic acids in interstellar ice.

• Journal of the Korean Wood Science and Technology
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• v.28 no.4
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• pp.17-24
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• 2000

The peroxidase activity was localized cytochemically to get an insight into its precise function in lignin biosynthesis. In this work, cerium chloride ($CeCl_3$) was used as a trapping agent for hydrogen peroxide ($H_2O_2$) generated from peroxidase. Seasonal variation of peroxidase activities in cambial region of Populus, Pinus, and Ginkgo was investigated at subcellular levels. Under transmission electron microscopy, electron dense deposits of cerium perhydroxide formed by reaction with $H_2O_2$ were observed in cambium and its immediate derivatives. The staining with $CeCl_3$ in cambium varied with growth seasons. The strongest $H_2O_2$ accumulation, regardless of tree species, appeared in May. Staining pattern of $CeCl_3$ in the cambium of poplar indicated that the production of peroxidase started in March before the opening of buds and reached the highest in May and then declined in August. Ginkgo and Pinus showed relatively late generation of $H_2O_2$ production when compared with Populus. Although Ginkgo and Pinus are classified into gymnosperms, however, the generation of peroxidase production and its duration was different from each other. Little staining appeared in all the tree samples collected in September before falling the leaves.

• Korean Journal of Materials Research
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• v.24 no.7
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• pp.357-362
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• 2014

Thermal barrier coatings(TBCs) are being applied in many industrial fields such as thermal power generation, aviation and seasonal fields. $ZrO_2-Y_2O_3$(8%) thermal spray coating powders are commercially used as thermal-barrier coating materials to protect against oxidation and corrosion of heat-resistant alloys at elevated temperatures. Currently, $ZrO_2-Y_2O_3$(8%) thermal-spray powder is made using the industrial co-precipitation process, which is very complex and requires a lot of time. In this study, orthorhombic $ZrO_2$ and $Y_2O_3$ powders were fabricated by mechanical mixing, which is more economical than the co-precipitation process. A tetragonal, yttria-stabilized zirconia(YSZ) coating-layer was produced by plasma spraying, using orthorhombic $ZrO_2-Y_2O_3$(8%) powder. Our experimental results indicate that $ZrO_2-Y_2O_3$(8%) mixed powder can be used economically in industry because it is no longer necessary to make this powder by liquid and gas-phase methods.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1407-1409
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• 1995

This paper describes ozone concenteration($O_{3con}$), ozone generation($O_{3g}$) and ozone yield($O_{3Y}$) of lamp type ozonizer which be performed a role of lighting source and ozonizer. OLamp is consist of two of low pressure mercury lamps. The important conclusions obtained from this paper are as follows, The more quality of supplied gas(Q) decrease, the higher $O_{3con}$ rise. The more quality of supplied gas(Q) increase, the higher $O_{3g}$ some rise. When supplied oxygen 10[l/min] obtained 4,010[mg/kwh] $O_{3Y}$. The Echerichia coli which is reacted on ozone can be sterilized about 95[%].