백색 LED용 청록색 BaSi₂O₂N₂:Eu²⁺ 형광체의 합성 및 응용

지순덕,최강식,최경재,김창해,Jee, Soon-Duk,Choi, Kang-Sik,Choi, Kyoung-Jae,Kim, Chang-Hae 한국재료학회 2011 한국재료학회지 Vol.21 No.5

We have synthesized bluish-green, highly-efficient $BaSi_2O_2N_2:Eu^{2+}$ and $(Ba,Sr)Si_2O_2N_2:Eu^{2+}$ phosphors through a conventional solid state reaction method using metal carbonate, $Si_3N_4$, and $Eu_2O_3$ as raw materials. The X-ray diffraction (XRD) pattern of these phosphors revealed that a $BaSi_2O_2N_2$ single phase was obtained. The excitation and emission spectra showed typical broadband excitation and emission resulting from the 5d to 4f transition of $Eu^{2+}$. These phosphors absorb blue light at around 450 nm and emit bluish-green luminescence, with a peak wavelength at around 495 nm. From the results of an experiment involving Eu concentration quenching, the relative PL intensity was reduced dramatically for Eu = 0.033. A small substitution of Sr in place of Ba increased the relative emission intensity of the phosphor. We prepared several white LEDs through a combination of $BaSi_2O_2N_2:Eu^{2+}$, YAG:$Ce^{3+}$, and silicone resin with a blue InGaN-based LED. In the case of only the YAG:$Ce^{3+}$-converted LED, the color rendering index was 73.4 and the efficiency was 127 lm/W. In contrast, in the YAG:$Ce^{3+}$ and $BaSi_2O_2N_2:Eu^{2+}$-converted LED, two distinct emission bands from InGaN (450 nm) and the two phosphors (475-750 nm) are observed, and combine to give a spectrum that appears white to the naked eye. The range of the color rendering index and the efficiency were 79.7-81.2 and 117-128 lm/W, respectively. The increased values of the color rendering index indicate that the two phosphor-converted LEDs have improved bluish-green emission compared to the YAG:Ce-converted LED. As such, the $BaSi_2O_2N_2:Eu^{2+}$ phosphor is applicable to white high-rendered LEDs for solid state lighting.

LED 조명의 색 온도에 따른 학습 성과의 객관적 평가

지순덕,김채복,Jee, Soon-Duk,Kim, Chae-Bogk 한국교육시설학회 2011 敎育施設 Vol.18 No.2

This study performs the objective evaluation on simple comparison and calculation works by students under LED illumination conditions according to three types of color temperatures (7000K, 5000K, 3000K) in the classroom, Since the objective of this study is to develop an electric lighting conditions suitable for students in the classroom, the learning performance under three types of LED illumination conditions were analyzed. The 4 kinds of simple tests concerning with learning performance were developed and test results under natural light and LED illumination by 3 types of color temperatures were analyzed. There were differences by t-test in most cases among simple experiment results of different illumination conditions ($p{\leq}.05$). It was confirmed that illumination condition plays an important role when students simply compare words or perform arithmetic calculations. The experimental results of this study might be applied to designing better luminous environment.

이완집중 및 긴장집중 시 LED 조명의 색온도에 따른 학습요인의 뇌파분석

지순덕,김채복,Jee, Soon-Duk,Kim, Chae-Bogk 한국교육시설학회 2014 敎育施設 Vol.21 No.6

The objective of this study is to investigate learning factors (stability, attention and activation) in school by electroencephalogram (theta, alpha and beta waves) analysis during relaxed or concentrated. In order to measure electroencephalograms, MP 150 by Biopac and ECI Electro-Cap are employed. Three types of color temperatures (3000K, 5000K, 7000K) are used and 13 undergraduate and 12 graduate students are selected as experimental subjects. When subjects are relaxed during contemplation or concentrated during mental arithmetic, we compare with stability, attention and activation indices. The test results show that subjects were stable when color temperature is 5000K. Subjects gave best attention when color temperature is 7000K. Subjects activated well when color temperature is 3000K during relaxed attention. However, subjects activated rigorous when color temperature is 7000K during constrained attention.

SERVPERF 모형을 응용한 학교 조명 품질 만족도 평가

지순덕,김성애,김채복,Jee, Soon-Duk,Kim, Sung-Ae,Kim, Chae-Bogk 한국교육시설학회 2013 敎育施設 Vol.20 No.3

This study addresses the evaluation on the satisfaction of school illumination quality by applying SERVPERF model after extracting factors affecting school illumination quality. Three types of illumination systems (fluorescence light, general LED light and high color rendition LED light) were tested by students who have used each illumination system. Three factors such as effectiveness, esthetic sense and function were developed for evaluation. Satisfaction evaluation was performed based on applied SERVPERF model by comparing perceived levels. The differences of perceived levels of satisfaction on the illumination systems were analyzed by ANOVA. The results said respondents satisfy only the high color rendition LED light regardless of three factors. Especially, students who experienced high color rendition LED light have strong intention to recommend that illumination system to other schools. They also express their desire to use that system at home. Interestingly, there is not much satisfaction difference between fluorescence light and general LED light.

백색 LED 조명의 색온도에 관한 감성평가

지순덕(Soon-Duk Jee),이상혁(Sang-Hyuk Lee),최경재(Kyoung-Jae Choi),박정규(Joung-Kyu Park),김창해(Chang-Hae Kim) 한국조명·전기설비학회 2008 조명·전기설비학회논문지 Vol.22 No.4

이 연구의 목적은 백색 LED 조명의 광학적 특성 중에서 색온도 특성에 따른 사람들의 감성 반응을 평가하는데 있다. 이를 위해 백색 LED 모듈을 시제품으로 만들고, 감성 평가용 모형을 제작하여 색온도에 따른 감성 반응을 평가 분석하였다. 감성 평가에는 15개의 문항에 대하여 5단계 SD법으로 하였으며, 신뢰도 검증과 타당성 검증을 통하여 조명과 관련이 있는 3개의 요인을 선정하였다. 1요인을 활동성 요인으로 명명하였고, 2요인을 안정성 요인으로 명명하였으며, 3요인을 역량성 요인으로 명명하였다. 감성 평가를 분석하기 위해 종속 변수는 감성 평가 점수로 하였으며, 독립 변수는 색온도로 분석하였다. 이 연구에서 얻어진 결과를 정리하면 다음과 같다. 형광등과 비교한 백색 LED 조명에 있어서 색온도에 따른 사람들에 대한 감성 평가는 활동성 요인과 역량성 요인에서는 색온도가 8,300[K]인 MA₃ 조명을 높게 평가하였으며, 안정감 요인에서는 색온도가 3,800[K]인 MA₁ 조명을 높게 평가하였다. The aim of this study is to investigate the sensitivity evaluation of human beings in reacting to the correlated color temperature of the optical properties of white LED lighting. For the sake of this study, white light-emitting diode modules have been fabricated, their correlated color temperature have been measured, test cabinets for the sensitivity evaluation have been constructed with the white LED modules, and their sensitivity reactions on the test cabinets have been evaluated and analyzed. The sensitivity reaction has been evaluated by the semantic differential method with 15 selected questions, and the reliability and the content validity of their lighting have been analyzed to 3 factors which are the activity as the first factor, the stability as the second one, the potency as the third one, respectively, For the data analysis on the sensitivity reaction, the dependent variable is the score of the sensitivity evaluation and the independent one is the correlated color temperature of the test module. The results of this study is as follows: In the case of the sensitive evaluation on the activity and the potency in the white LED lighting compared with the fluorescent lamp, the subjects have made higher mark on MA₃ with 8,300[K], and in the factor of the stability, they have made higher mark on MA₁ with 3,800[K].

이완집중 및 긴장집중 시 LED 조명의 색온도에 따른 학습요인의 뇌파분석

지순덕(Jee, Soon-Duk),김채복(Kim, Chae-Bogk) 한국교육시설학회 2014 敎育施設 Vol.21 No.6

The objective of this study is to investigate learning factors (stability, attention and activation) in school by electroencephalogram (theta, alpha and beta waves) analysis during relaxed or concentrated. In order to measure electroencephalograms, MP 150 by Biopac and ECI Electro-Cap are employed. Three types of color temperatures (3000K, 5000K, 7000K) are used and 13 undergraduate and 12 graduate students are selected as experimental subjects. When subjects are relaxed during contemplation or concentrated during mental arithmetic, we compare with stability, attention and activation indices. The test results show that subjects were stable when color temperature is 5000K. Subjects gave best attention when color temperature is 7000K. Subjects activated well when color temperature is 3000K during relaxed attention. However, subjects activated rigorous when color temperature is 7000K during constrained attention.

SERVPERF 모형을 응용한 학교 조명 품질 만족도 평가

지순덕(Jee, Soon-Duk),김성애(Kim, Sung-Ae),김채복(Kim, Chae-Bogk) 한국교육시설학회 2013 敎育施設 Vol.20 No.3

This study addresses the evaluation on the satisfaction of school illumination quality by applying SERVPERF model after extracting factors affecting school illumination quality. Three types of illumination systems (fluorescence light, general LED light and high color rendition LED light) were tested by students who have used each illumination system. Three factors such as effectiveness, esthetic sense and function were developed for evaluation. Satisfaction evaluation was performed based on applied SERVPERF model by comparing perceived levels. The differences of perceived levels of satisfaction on the illumination systems were analyzed by ANOVA. The results said respondents satisfy only the high color rendition LED light regardless of three factors. Especially, students who experienced high color rendition LED light have strong intention to recommend that illumination system to other schools. They also express their desire to use that system at home. Interestingly, there is not much satisfaction difference between fluorescence light and general LED light.

LED 기반 백색 조명의 색온도 및 연색지수에 따른 감성 평가

지순덕 ( Soon Duk Jee ),최경재 ( Kyoung Jae Choi ),김호건 ( Ho Kun Kim ),이상혁 ( Sang Hyuk Lee ) 한국감성과학회 2006 감성과학 Vol.9 No.4

학교 교실 LED 조명의 색온도에 대한 주관적 평가

지순덕(Soon-Duk Jee),김채복(Chae-Bogk Kim) 한국조명·전기설비학회 2011 조명·전기설비학회논문지 Vol.25 No.1

This study performs the subjective evaluations of LED illumination conditions according to three types of color temperatures (7,000[K], 5,000[K], 3,000[K]) after employing LED illumination system in the classroom, Since the objective of this study is to develop an artificial lighting conditions like day light comfortable to students in the classroom, the learning effect based on three types of LED illumination conditions are analyzed. Three factors (learning intention, learning environment, learning motivation) are extracted by ANOVA and there are preference differences of LED illumination conditions between learning intention and learning environment factors. Especially, preference differences of LED illumination conditions are existed about calculation, reading and fatigue reduction. The test results of this study can be applied to obtaining high achievement of learning based on the lighting conditions.

LED용Mg²⁺·Ba²⁺Co-Doped Sr₂SiO₄:Eu 노란색 형광체의 발광특성

최경재,지순덕,김창해,이상혁,김호건,Choi, Kyoung-Jae,Jee, Soon-Duk,Kim, Chang-Hae,Lee, Sang-Hyuk,Kim, Ho-Kun 한국세라믹학회 2007 한국세라믹학회지 Vol.44 No.3

An improvement for the efficiency of the $Sr_{2}SiO_{4}:Eu$ yellow phosphor under the $450{\sim}470\;nm$ excitation range have been achieved by adding the co-doping element ($Mg^{2+}\;and\;Ba^{2+}$) in the host. White LEDs were fabricated through an integration of an blue (InGaN) chip (${\lambda}_{cm}=450\;nm$) and a blend of two phosphors ($Mg^{2+},\;Ba^{2+}\;co-doped\;Sr_{2}SiO_{4}:Eu$ yellow phosphor+CaS:Eu red phosphor) in a single package. The InGaN-based two phosphor blends ($Mg^{2+},\;Ba^{2+}\;co-doped\;Sr_{2}SiO_{4}:Eu$ yellow phosphor+CaS:Eu red phosphor) LEDs showed three bands at 450 nm, 550 nm and 640 nm, respectively. The 450 nm emission band was due to a radiative recombination from an InGaN active layer. This 450 nm emission was used as an optical transition of the $Mg^{2+},\;Ba^{2+}\;co-doped\;Sr_{2}SiO_{4}:Eu$ yellow phosphor+CaS:Eu red phosphor. As a consequence of a preparation of white LEDs using the $Mg^{2+},\;Ba^{2+}\;co-doped\;Sr_{2}SiO_{4}:Eu$ yellow phosphor+CaS:Eu red phosphor yellow phosphor and CaS:Eu red phosphor, the highest luminescence efficiency was obtained at the 0.03 mol $Ba^{2+}$ concentration. At this time, the white LEDs showed the CCT (5300 K), CRI (89.9) and luminous efficacy (17.34 lm/W).