• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.966-967
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• 2006

본 논문에서는 250W 메탈핼라이드 램프용 전자식 안정기의 구조 및 디밍 방법에 따른 특성을 비교하였다. 측정 및 분석된 안정기는 PFC, 벅 컨버터, Full-bridge 인버터의 3단 구조를 가진 안정기와 PFC, Half-bridge 인버터의 2단 구조를 가진 안정기이다. 3단 구조를 가진 안정기의 경우 벅 컨버터의 듀티 조절하여 출력 전력을 제어하며, 2단 구조 안정기의 경우는 구동 주파수를 조절하여 전력을 제어한다. 본 논문에서는 각각의 전력제어 방식을 통한 램프 디밍 시의 출력의 특성을 측정 및 분석하였으며, 조도 조절 범위는 $100%{\sim}35%$까지 구현하였다.

• YAKHAK HOEJI
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• v.55 no.1
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• pp.32-38
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• 2011

A series of new alkylselenoallylthiopyridazine 12~18 was synthesized as expected to retain anticancer activity. Synthetic route for the final compounds 12~18 was proceeded with diselenylation, hydrolysis/alkylation and allylthiolation from 3,6-dichloropyridazine 1. Dichloropyridazinyl diselenide 2 was prepared from the diselenide anion using synthetic route of Bhasin. Diselenide 2 can be reduced to 3-chloropyridazinyl selenolate anion using hydrazine hydrate at rt in the presence of NaOH in THF. The anion thus formed reacts readily with alkyl halide to give the 3-alkylseleno-6-chloropyridazine 3~11. 3-Alkylseleno-6-allylthiopyridazines 12~18 were prepared from 3~11 with allylmercaptan and sodium methoxide.

• Bulletin of the Korean Chemical Society
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• v.31 no.1
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• pp.69-74
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• 2010

The new idarubicin analogues (12 and 13) with a glucose or galactoseas as a glycone were synthesized from daunomycin (2). (+)-4-Demethoxydaunomycinone (6) obtained from reaction of 2 with $AlCl_3$ was converted to 4-trifluoromethanesulfonyl daunomycinone (7) through reaction with trifluoromethanesulfonic anhydride. The treatment of 7 with 1,1-bis-(diphenylphospino)ferrocene/$Pd(OAc)_2$ in triethylamine/formic acid/dioxane provided the idarubicinone (5b). Glycosylation of 7-hydroxy group of 5b with two kinds of tetraacetyl pyranosyl halide (8 and 9) by a modified Koenigs-Knorr procedure and then deacetylation using aqueous 0.1 N LiOH solution and amberlite cationic resin gave the objective materials. The in vitro MTT assay of the analogues (12b and 13a) in comparison with idarubicin (5a) on peripheral blood human promyelocytic-leukemia cell line and human breast cancer cell line were also described.

• Bulletin of the Korean Chemical Society
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• v.27 no.4
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• pp.545-548
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• 2006

We investigated the Surface-enhanced Raman Spectroscopy (SERS) spectrum of ethephone (2-chloroethylphosphonic acid). We observed significant signals in the ordinary Raman spectrum for solid-state ethephone as well as when it was adsorbed on a colloidal silver surface, strong vibrational signals were obtained at a very low concentration. The SERS spectra were obtained by silver colloids that were prepared by the $\gamma$-irradiation method. The influence of pH and the influence of anion $(Cl^-,\;Br^-,\;I^-)$ on the adsorption orientation were investigated. Two different adsorption mechanisms were deduced, depending on the experimental conditions. The chlorine atom or the chlorine and two oxygen atoms were adsorbed on the colloidal silver surface. Among halide ions, $Br^-$ and $I^-$ were more strongly adsorbed on the colloidal silver surfaces. As a result, the adsorption of ethephone was less effective due to their steric hinderance.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3686-3690
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• 2012

Photochemical degradation of dimethyl phthalate (DMP) in Fe(III)/tartrate/$H_2O_2$ system was investigated utilizing fluorescent lamps as the primary light source. Effects of initial pH, light source, and initial concentration of each reactant on DMP photodegradation was examined. The results show that the system was able to effectively photodegrade DMP utilizing visible light. Fluorescent lamp, halide lamp, UV lamp and sunlight could all be used as the light sources. The optimal pH ranged among 3.0-4.0 for the system. Increases of the initial concentrations of Fe(III) and $H_2O_2$ accelerated the photodegradation of DMP, whereas excessively high initial tartrate concentration resulted in the decrease of photodegradation efficiency and rate of DMP.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.12
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• pp.737-749
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• 2016

Recently perovskite materials with much cheaper cost and marvellous optoelectronic properties have been studied for next generation LED display devices overseas. Technology development trends of inorganic $CsPbX_3$(X=halogen) based LEDs (PeLEDs) with assumed high stability were investigated on literature worldwide. It was found that syntheses methods of these nanocrystals (NCs, mainly quantum dots, QDs) made great progress. A new room temperature synthesis method showed outstanding PL (photoluminescence) properties such as high quantum yield (QY), narrow emission width, storage stability comparable with, or often exceeding those of conventional hot injection method and CdSe@ZnS type inorganic colloidal QDs. PeLEDs with shell layers might be more promising, indicating urgent real research start of this solution processing technology for small businesses in Korea.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.1004-1013
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• 2010

Three-dimensional superstructures of unique self-assemblies generated by exploring the conformational flexibility of various dipyrromethenes through creation of hydrogen-bonds with metal-halide anions are reported and the conformational diversity is thoroughly described in the solid and solution states by X-ray diffraction analysis and variable temperature NMR spectroscopy. The tetrahedral or octahedral structures of their precursors, various metal-dipyrromethene complexes, are also reported, based on the crystallographic data. STM images of the self-assemblies observed on graphite surfaces present interesting arrangements and appear as tubular bunches.

• Proceedings of the IEEK Conference
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• 2001.06e
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• pp.99-102
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• 2001

In this paper, the electronic ballast was developed to control 250W metal halide lamp. To avoid acoustic resonance phenomenon, we calculated the acoustic resonance band and determined the driving frequence to from 70kHz to 100kHz. Due to the switching loss of MOSFET, many problems are caused in the inverter circuit during lighting the lamp, so we have reduced the loss by connecting the capacitor to reduce inrush current In this paper, main research area is to find the methods to operate the Iamp on regulated constant output. After detecting the current I and voltage V of the lamp, we changed the driving frequency by changing the DC voltage level.

• Corrosion Science and Technology
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• v.7 no.4
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• pp.233-236
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• 2008

Halide-activated pack cementation was utilized to deposit B-doped silicide coating. The pack powders were consisted of $3Wt.c/oNH_4Cl$, 7Wt.c/oSi, $90Wt.c/oAl_2O_3+TiB_2$. B-doped silicide coating was consisted of two layers, an outer layer of $NbSi_2$ and an inner layer of $Nb_5Si_3$. Isothermal oxidation resistance of B-doped silicide coating was tested at $1250^{\circ}C$ in static air. B-doped silicide coating had excellent oxidation resistance, because continuous $SiO_2$ scale which serves as obstacle of oxygen diffusion was formed after oxidation.

• Macromolecular Research
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• v.14 no.3
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• pp.338-342
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• 2006

The kinetic features of polymerization with an active site comprising cobalt dihalides ($CoX_2$, where X=Cl, Br, I) activated by methylaluminoxane (MAO) were investigated in 1,3-butadiene polymerization. The catalytic system exhibited the characteristic features of living polymerization. The initiation ($k_i$) and propagation ($k_p$) rate coefficients were estimated using the kinetic model for slow initiation previously reported by Shiono et al. The energy of activation fur the propagation reaction was calculated to be 27-30 $kJmol^{-1}$. The marked changes in reaction rate observed with different halides could be adequately described in terms of variations in the initiation process, with the same Arrhenius curve fitting propagation rate coeffcients estimated from all three halides, suggesting that the halide does not participate in the growing chain end.