• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권4호
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• pp.238-243
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• 2006

This paper presents novel ignition method for automotive 35W metal halide discharge lamp electronic ballast. At this study, the novel method of ignition is developed to reduce costs and size of the ballast. By use of the novel method, the voltage needed in ignition is decreased, which result in use of the lower voltage rating power devices compared with conventional method and product compactness was achieved by deleting a circuit generating negative voltage needed in ignition at an conventional circuit. In terms of luminosity, color rendering, light efficiency(lm/W) and lifespan, the metal halide lamp is superior to, but unlike halogen lamp, it have more complicated transient characteristics to reach its steady state than the conventional halogen lamp. Therefore, in this paper, the electronic ballast was designed such that the metal halide lamp could be optimized for the automotive, by applying a method of microcontroller-based digital control. The results of the proposed system is verified through various experiment results.

• 대한화학회지
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• 제17권6호
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• pp.406-410
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• 1973

Dimethylsulfamoyl chloride의 할라이드 교환반응을 무수 아세톤 용매속에서 방사성 할라이드 이온을 사용하여 두 온도에서 속도론적으로 연구하였다. 그 결과를 benzensulfonyl chloride의 경우와 비교해 보면 친핵성에 있어서는 거의 비슷한 경향성을 나타내나, 반응속도는 dimethylsulfamoyl chloride 쪽이 $10^{-2}$배 이상이나 느린 경향을 나타낸다. 또한 활성화 파라미터, ${\Delta}H^{\neq}$나 ${\Delta}S^{\neq}$는 benzensulfonyl chloride의 경우와는 반대로 dimethylsulfamoyl chloride의 경우는 $Cl^-\;>\;Br^-\;>\;I^-$의 순서로 감소함을 나타낸다. 이 결과를 bond-breaking, bond formation, electronic requirment 및 HSAB 원리로 설명하였다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 추계학술대회 논문집
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• pp.81-84
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• 2008

1960년대 중반부터 이미 고압 나트륨램프에 사용되어 오던 반투명의 세라믹 재료(Polycrystalline Ceramic Alumina ; PCA)를 기존 메탈핼라이드램프의 석영(Quartz) 발광관에 적용시킨 세라믹 메탈핼라이드(Ceramic Metal Halide ; CMH) 램프는 1995년 처음 소개된 이래 색 제어, 연색성, 광속유지율 등에서 전통적인 석영 메탈핼라이드(Quartz Metal Halide ; QMH)램프보다 우수한 특성을 가지고 있어 저와트급(150W이하)에서 고와트급에 이르기까지 폭넓게 사용되어지고 있으며 현재 국내에서도 이러한 CMH램프의 개발이 진행 중이다. 본 논문에서는 CMH램프의 우수한 특성을 살펴보기 위하여 국외 선진제품에 대한 전기적, 광학적 특성을 살펴보았으며 실험 결과 CMH 램프의 광속유지 율이 기존 QMH 램프보다 우수한 특성을 갖는 것을 확인할 수 있었다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2002년도 춘계종합학술대회
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• pp.301-304
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• 2002

본 논문은 70［W］급 세라믹 방전관 메탈할라이드 램프용 전자식 안정기의 설계와 제자에 대하여 기술하였다. 제안한 안정기는 정류기, 능동성 역률개선회로, 하프브리지 인버터, LC 공진회로 및 제어회로로 구성되며, 램프의 재점등에 필요한 타이머 기능을 추가하였다. 점등시 램프에는 음향공명현상과 플리커 현상을 피하기 위하여 45［KHz］의 고주파 전압이 인가되도록 설계하였다. 실험결과로부터 역률과 효율은 각각 91［%], 97.7［%］로 평가되었다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2002년도 추계종합학술대회
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• pp.435-439
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• 2002

본 논문은 70[W]급 세라믹 방전관 메탈할라이드 램프용 전자식 안정기의 설계 및 제작에 대하여 기술하였다. 개발한 안정기는 정류회로, 능동성 역률개선회로, 하프브리지 인버터, LC 공진회로 및 제어회로로 구성되며, 램프의 재점등에 필요한 타이머 기능을 부가하였다. 점등시 램프에는 음향공명현상과 플리커 현상을 피하기 위하여 40[kHz]의 고주파 전압이 인가되도록 하였다. 실험결과로부터 역률과 효율은 각각 99.8[%], 93.1[%]로 평가되었다.

• 전기학회논문지
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• 제58권10호
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• pp.1989-1994
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• 2009

This study purposes are improvement of system (lamp & ballast) efficacy with and optical characteristics through the developed ceramic arc tube. The designed electronic ballast is substituted for conventional magnetic ballast. These electric signal and optical, thermal characteristics through the improving efficacy of lighting system compared with conventional magnetic ballast. properties of lamp by driving method is researching in ballast. Particularly, electronic ballasts, which improved against weakness of Magnetic Ballast, are researching and applying to control of ceramic metal-halide lamp. but One major limitation is the acoustic resonance problem in CMH lamps at high-frequency operation. In order to avoid acoustic resonance, driving frequency decided 21[kHz]. Before discharge in this paper. The PSpice simulation result obtained sufficient voltage gain and the ignition voltage obtained over 3[kV] at 75[kHz]. After discharge, driving voltage obtained approximately 90[Vrms] at 21[kHz].

• 한국표면공학회지
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• 제52권6호
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• pp.334-341
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• 2019

Organometal halide perovskite materials have attracted much attention in the photovoltaic and light emitting devices due to the compositional flexibility with AMX₃ formula (A is an organic amine cation; M is a metal ion; X is a halogen atom). The addition of homovalent or heterovalent metal cations to the bulk organohalide perovskites has been performed to modify their energy band structure and the relevant optoelectronic properties by ligand-assisted ball milling. Here, we report CH₃NH₃Pb_1-xM_xBr₃ nanocrystals substituted by metallic cations (M is Sn²⁺, In³⁺, Bi³⁺; x = 0, 0.01, 0.02, 0.05, 0.1, 0.2). Photoluminescence and quantum yield was significantly reduced with increasing metallic cations content. These quenching effect could be resulted from the metal cations that behave as a non-radiative recombination center.

• 한국재료학회지
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• 제31권9호
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• pp.496-501
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• 2021

Metal halide perovskite nanocrystals, due to their high absorption coefficient, high diffusion length, and photoluminescence quantum yield, have received significant attention in the fields of optoelectronic applications such as highly efficient photovoltaic cells and narrow-line-width light emitting diodes. Their energy band structure can be controlled via chemical exchange of the halide anion or monovalent cations in the perovskite nanocrystals. Recently, it has been demonstrated that chemical exfoliation of the halide perovskite crystal structure can be achieved by addition of organic ligands such as n-octylamine during the synthetic process. In this study, we systematically investigated the quantum confinement effect of methylammonium lead bromide (CH₃NH₃PbBr₃, MAPbBr₃) nanocrystals by precise control of the crystal thickness via chemical exfoliation using n-octylammonium bromide (OABr). We found that the crystalline thickness consistently decreases with increasing amounts of OABr, which has a larger ionic radius than that of CH₃NH₃⁺ ions. In particular, a significant quantum confinement effect is observed when the amounts of OABr are higher than 60 %, which exhibited a blue-shifted PL emission (~ 100 nm) as well as an increase of energy bandgap (~ 1.53 eV).

• Corrosion Science and Technology
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• 제18권3호
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• pp.110-116
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• 2019

Resistances to pitting corrosion of additive manufactured (AM) Ti-6Al-4V alloys in 0.6 M NaBr and 0.6 M NaCl aqueous solutions were compared using micro-droplet cell techniques. With respect to the pitting corrosion resistance, this study focused on two different types of halide anions in aqueous solutions, i.e. $Br^-$ and $Cl^-$. The differences between $Br^-$ and $Cl^-$ halide anions for breakdown on passive films of AM Ti-6Al-4V alloy were explained using Langmuir adsorption model with their equilibrium adsorption coefficients. The results of the analysis showed that the lower resistance to pitting potential of AM Ti-6Al-4V alloy in $Br^-$ aqueous solution was attributed to the higher equilibrium adsorption coefficient of Br-. In addition, micro-electrochemical test results showed that the pitting corrosion resistance of dark grains in additive manufactured Ti-6Al-4V alloy was lower as compared to that of bright grains due to the larger volume of ${\alpha}^{\prime}$ phase that caused the susceptibility to pit initiation.

• 센서학회지
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• 제31권6호
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• pp.383-388
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• 2022

Currently, photodetectors are being extensively studied and developed for next-generation applications, such as in autonomous vehicles and image sensors. In this regard, all-inorganic metal halide perovskite (CsPbX₃; X = Cl, Br, and I) nanocrystals (NCs) have emerged as promising building blocks for various applications owing to their high absorption coefficients, tunable bandgaps, high defect tolerances, and solution processability. These features, which are typically required for the development of advanced optoelectronics, can be engineered by modifying the chemical compositions and surface chemistry of the NCs. Herein, we briefly review various strategies adopted for the application of CsPbX₃ perovskite NCs in photodetectors and for improving device performance. First, modifications of the chemical compositions of CsPbX₃ NCs to tune their optical bandgaps and improve the charge-transport mechanism are discussed. Second, the application of surface chemistry to improve oxidation resistance and carrier mobility is described. In the future, perovskite NCs with prospective features, such as non-toxicity and high resistance to external stimuli, are expected to be developed for practical applications.