LED용 Sr2Ga2S5:Eu2+ 황색 형광체의 합성 및 발광특성

김재명,박정규,김경남,이승재,김창해,장호겸,Kim, Jae-Myeong,Park, Jeong-Gyu,Kim, Gyeong-Nam,Lee, Seung-Jae,Kim, Chang-Hae,Jang, Ho-Gyeom 대한화학회 2006 대한화학회지 Vol.50 No.3

LED는 고휘도 청색 칩의 개발로 인해 단순표시소자로만 이용되던 것이 다양한 분야의 발광소자로 적용되기 시작하였다. 특히, 최근에 InGaN 칩과 황색 형광체(YAG:Ce3+)를 이용한 방법이 많이 연구되어지고 있다. 하지만 이 방법은 2 파장을 이용한 것으로 색연지수가 낮은 단점을 지니며, 황색의 YAG:Ce3+ 형광체 이외에 450~470 nm의 여기 영역에서 효율적으로 발광하는 형광체가 거의 없다. 따라서 본 연구에서는 장파장 영역의 여기 특징을 지닌 thiogallate 형광체의 합성을 시도하였다. 그 중에 가장 잘 알려진 SrGa2S4:Eu2+ 형광체의 모체를 변화시켜 Sr2Ga2S5:Eu2+ 형광체를 합성하였으며, 발광특성을 조사하였다. 그리고 무해성과 제조 공정의 단순화를 위하여, 황화물질과 5 % H2/95 % N2 혼합 기체를 CS2와 H2S 가스 대신에 사용하였다. 이렇게 합성되어진 형광체는 550 nm의 발광 중심을 가지는 황색 형광체로서 300~500 nm에 이르는 넓은 여기원을 통한 발광이 가능하다. 그리고 YAG:Ce3+ 형광체와 비교해 볼 때 강도 면에서 110 % 이상을 보이며, UV 영역의 여기적 특성을 이용해 UV LED에도 응용이 가능하다. Nowadays, LEDs has been applied to the luminescent devices of various fields because of the invention of high efficient blue chip. Recently, especially, the white LEDs composed of InGaN blue chips and a yellow phosphor (YAG:Ce3+) have been investigated extensively. With the exception of YAG:Ce3+ phosphor, however, there are no reports on yellow phosphor that has significant emission in the 450~470 nm excitation range and this LED system is the rather low color rendering index due to their using two wavelength. Hence, we have attempted to synthesize thiogallate phosphors that efficiently under the long wavelength excitation range in the present case. Among those phosphors, we have synthesized Sr2Ga2S5:Eu2+ phosphor by change the host material of SrGa2S4:Eu2+ which is well known phosphor and we investigated the luminescent properties. In order to obtain the harmlessness and simplification of the synthesis process, sulfide materials and mixture gas of 5 % H2/95 % N2 were used instead of the CS2 or H2S gas. The prepared phosphor shows the yellow color peaking at the 550 nm wavelength and it possible to emit efficiently under the broad excitation band in the range of 300~500 nm. And this phosphor shows high luminescent intensity more than 110 % in comparison with commercial YAG:Ce3+ phosphor and it can be applied for UV LED due to excitation property in UV region.

고상법을 이용한 LED용 SrGa₂S₄:Eu 녹색 형광체의 합성 및 발광특성

김재명,김경남,박정규,김창해,장호겸,Kim, Jae-Myung,Kim, Kyung-Nam,Park, Joung-Kyu,Kim, Chang-Hae,Jang, Ho-Gyeom 대한화학회 2004 대한화학회지 Vol.48 No.4

The $SrGa_2S_4:Eu^{2+}$ green emitting phosphor has been studied as a luminous device for CRT (Cathode Ray Tube) or FED (Field Emission Display) and EL (Electroluminescence). This phosphor, also, is under noticed for LED (Lighting Emitting Diode) phosphor, which makes use of excitation characteristics of long wavelength region. The $SrGa_2S_4:Eu^{2+}$ phosphor was prepared generally conventional synthesis method using flux. However, this method needs high heat-treated temperature, long reaction time, complex process and harmful $H_2S$or $CS_2$ gas. In this works, therefore, we have synthesized $SrGa_2S_4:Eu^{2+}$ using SrS, $Ga_2S_3$, and EuS as starting materials, and the mixture gas of 5% H2/95% N2 was used to avoid the $H_2S$or $CS_2$. We investigated the luminescence characteristic of $SrGa_2S_4:Eu^{2+}$ phosphor prepared in various synthesis conditions, performed post-treatment and sieving process for application to LED. 기존의 $SrGa_2S_4:Eu^{2+}$ 녹색 발광 형광체는 주로 CRT (Cathode Ray Tube)용이나 FED (Field Emission Display), 그리고 EL (Electroluminescence)용 발광소자로 많이 연구되어졌다. 현재는 장파장 영역의 여기 특성을 이용한 LED (Light Emitting Diode)용 형광체로 주목 되어지고 있다. $SrGa_2S_4:Eu^{2+}$ 형광체의 일반적 합성 방법은 Flux를 이용하여 인체에 유해한 $H_2S$나 $CS_2$ 기체를 사용할 뿐만 아니라 높은 합성온도, 긴 반응시간 및 공정이 복잡한 단점을 지니고 있다. 따라서 본 실험은 황화물계 원료인 SrS, $Ga_2S_3$ 그리고 EuS를 출발 물질로 하여 $H_2S$ 기체를 사용하지 않고 혼합 기체$(5% H_2/95% N_2)$를 사용해 환원 분위기 하에서 $SrGa_2S_4:Eu^{2+}$을 합성하였다. 그리고 다양한 합성 조건과 LED용으로 사용되기 위해 수세처리와 Sieving 과정을 거친 형광체의 발광특성을 검토하였다.

산 에칭에 의한 BaO-B₂O₃-ZnO계 유리조성물의 용출 현상

김재명,홍경준,김남석,김형순,Kim, Jae-Myung,Hong, Kyung-Jun,Kim, Nam-Suk,Kim, Hyung-Sun 한국세라믹학회 2006 한국세라믹학회지 Vol.43 No.1

For producing the fine ribs structure of plasma display panel, the metal ions of barrier materials during the etching process should be understood on the etching mechanism with etching conditions. Etching was done on bulk glasses of the $BaO_B_2O_3-ZnO$ system with $HNO_3$ solution at $40^{\circ}C$. The surface structure of glasses and ion dissolution were analyzed by ICP (Inductive Coupled Plasma measurement). The structure and surface of the etched bulk glass were investigated by using scanning electron microscopy and nanoindenter. As a result, Ba (3-35 ppm/min) and Zn (2-27 ppm/min) ions as major components were leached in the solution and the leached layers were found to be phosphor-rich surface layers. A decrease of the bridge oxygen and relative increase of non bridge oxygen in the etched glass were found by X-ray photoelectron spectroscopy.

LED용 BaGa₂S₄:Eu²⁺ 녹색 형광체의 합성 및 발광특성

김재명,박정규,김경남,이승재,김창해,Kim, Jae-Myung,Park, Joung-Kyu,Kim, Kyung-Nam,Lee, Seung-Jae,Kim, Chang-Hae 한국재료학회 2006 한국재료학회지 Vol.16 No.12

[ $II-III_2-(S,Se)_4$ ] structured of phosphor has been used at various field because those have high luminescent efficiency and broad emission band. Among these phosphors, the europium doped $BaGa_2S_4$ was prepared by solid-state method and had high potential application due to an emissive property of UV region. Also, the common sulfide phosphors were synthesized by using injurious $H_2S\;or\;CS_2$ gas. However, in this study $BaGa_2S_4:Eu^{2+}$ phosphor in addition to excess sulfur was prepared under at 5% $H_2/95%\;N_2$ reduction atmosphere. Thus, this process could be considered as large scale synthesis because of non-harmfulness and simplification. The photoluminescence efficiency of the prepared $BaGa_2S_4:Eu^{2+}$ phosphor increased 20% than that of commercial $SrGa_2S_4:Eu^{2+}$ phosphor. The prepared $BaGa_2S_4:Eu^{2+}$ could be applied to green phosphor for white LED of three wavelengths.

권두언

김재명,Kim, Jae-Myeong 한국위성정보통신학회 2007 위성통신과 우주산업 Vol.14 No.1

PAPR Reduction Using Hybrid Schemes for Satellite Communication System

김재명,조자빈,이호위,손성환,Kim, Jae-Moung,Zhao, Zibin,Li, Hao-Wei,Sohn, Sung-Hwan Korea Society of Satellite Technology 2008 한국위성정보통신학회논문지 Vol.3 No.2

In the future, satellite communication systems, such as ISDB in Japan and DVB in Europe, are required to support higher transmission date rate for providing multimedia services including HDTV, high rate data communication etc. Considering the effectiveness of OFDM technique in efficient usage of frequency bandwidth and its robustness to the multi-path fading, several OFDM based standards have been proposed for satellite communication. However, the problem of high Peak to Average Power Ratio is one of the main obstacles for the implementation of OFDM based system. Many PAPR reduction schemes have been proposed for OFDM systems. Among these, the partial transmit sequences (PTS) is attractive as they obtain better PAPR property by modifying OFDM signals without distortion. In this paper, considering the complexity issue, we present a simplified minimum maximum (minimax) criterion and Sub-Optimal PTS algorithm to optimize the phase factor. This algorithm can be dynamically made tradeoff`f between performance and complexity on demand. In addition, we integrate guided scrambling (GS) with this method. Simulation in multiple antenna based OFDM system proves that the proposed Hybrid schemes can get much more PAPR reduction and do not require transmission of side information (SI). Thus it is helpful when implementing OFDM technique in satellite communication system.

효율적인 인사관리

김재명,Kim, Jae-Myeong 대한병원협회 1991 대한병원협회지 Vol.20 No.11

권두언

김재명,Kim, Jae-Myeong 한국위성정보통신학회 2006 위성통신과 우주산업 Vol.13 No.1

독일어 수동형 형태의 생성과정과 그 통시적 변화과정

김재명,Kim Jai-Myoung 한국독어학회 2002 독어학 Vol.6 No.-

Im Mittelpunkt der vorliegenden Arbeit steht die Untersuchung der Dynamik im System des deutschen Passivs mit dem $R\"{u}ckblick$ auf das Genuanische. Dabei steht es vorrangig im Zusammenhang mit der Grammatikalisierung der $Verbalf\"{u}gungen$ 'werden + PP' und 'sein + PP'. Und im heutigen deutschen Passivsystem ist zwar die $F\"{u}gung$ 'werden + PP' unmarkiert, aber im Genuanischen $\"{u}berwiegt\;die\;F\"{u}gung$ 'sein + PP'. Das Partizip der Kombination 'werden/sein + PP' wird im Gotischen $ausschlie{\ss}lich$ und im Althochdeutschen noch stellenweise flektiert. Hieraus darf geschlossen werden, dass im $Fr\"{u}hdeutschen$ das Verb finita und das Partizip als relativ $unabh\"{a}ngige$ Glieder einander $gegen\"{u}ber$ stehen und in einer Konstruktion verkettet werden, die einfach den Status der neuhochdeutschen periphrastischen Konstruktion aufweist. Die aspektuelle Bedeutung der $Passivf\"{u}gungen\;l\"{a}sst$ sich da als $bin\"{a}re$ Opposition von kategoriellen Merkmalen 'mutativ' (= Zustandswechel) und 'statal' (= Zustand), verteilt auf die F\"{u}gungen$ 'werden + PP' und 'sein + pp', beschreiben. Diese Merkmale kommt jeweils aus dem inchoativen bzw. durativen Verbalaspekt der Verba 'werden' bzw. 'sein' heraus. Diese Opposition unterscheidet sich von der neuhochdeutschen $Gegen\"{u}berstellung$ vom Vorgangspassiv und Zustandspassiv. Die Eigenbedeutung der Verben 'werden' und 'sein' $l\"{o}st$ sich nun, insbesondere im $Sp\"{a}talthochdeutschen$ in der Semantik der ganzen $F\"{u}gungen$ weitgehend auf, was seinerseits den Verlust der aspektualen Markiertheit der Passiv-Periphrasen mit den Verben finiten verursacht und ihre Entwicklung in Richtung auf die Paradigmatisierung der beiden $F\"{u}gungen\;erm\"{o}glicht$. Die weiter Entwicklung von $Passivf\"{u}gungen$ zeichnet sich durch eine zunehmende Expansion der $F\"{u}gung$ 'werden+PP' in die ursprungliche aspektuale $Sph\"{a}re$ der sein-Konstruktion aus. Dieser Prozess, der zur Auxilialisierung des Verbums finitum $f\"{u}hrt$, setzt schon im $Sp\"{a}talthochdeutschen$ ein und gelangt im Mittelhochdeutschen zur vollen $Auspr\"{a}gung$. Die Konkurrenz der beiden Passivkonstruktionen $f\"{u}hrt$ nun zur $allm\"{a}hlichen$ Verengung des aspektualen Bereichs der $F\"{u}gung$ '.sein+PP', $f\"{u}r$ die nun nur das Resultivum $\"{u}brig$ bleibt.

우리목장 월동준비 - 소결핵병 등 호흡기 질병예방

김재명,Kim, Jae-Myeong 한국낙농육우협회 2013 낙농·육우 Vol.33 No.12