• Journal of Microbiology and Biotechnology
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• 제4권3호
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• pp.176-182
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• 1994

The light-organ symbiont of pine cone fish, Vibrio fischeri, senses its presence in the host and responds to environmental changes by differentially expressing its symbiosis-related luminescence genes. The V. fischeri luminescence genes are activated by LuxR protein in the presence of an autoinducer. In an effort to elucidate the mechanism of regulation of luxR, a plasmid containing luxR was mutagenized in vitro with hydroxylamine and a luxR mutant plasmid was isolated by its ability to activate luminescence genes cloned in E. coli in the absence of the autoinducer. The specific base change identified by DNA sequencing was only single base transition at ＋78 from the transcriptional start of luxR. Based on a Western immunoblot analysis, the nucleotide change directed the synthesis of much higher level of LuxR protein without any amino acid substitutions. The results suggest that the region including the ＋78th base is presumably internal operator required for autorepression of luxR, and the increased cellular level of LuxR results in activation of luminescence genes by autoinducer independent fashion.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.1002-1006
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• 2004

The studies on OLED(Organic Light-Emitting Diode) materials and structures have been researched in other to improve luminescence efficiency of OLED. Electrons and holes are injected into the devices, transported across the layer and recombine to form excitons, their profiles are sensitive to mobility velocity of electrons and holes. A suggested means of improving the efficiency of LEDs would be to balance the injection of electrons and holes into light emission layer of the device. In this paper, we demonstrate the difference of velocity between hole and electron by experiments, and compare with a data of simulation and experiment changing hole carrier transport layer thickness, so we get the optimal we improve luminescence efficiency. We improve understanding of the various luminescence efficiency through experiments and numerical analysis of luminescence efficiency in the hole carrier transport layer's thicknes.

• Journal of the Optical Society of Korea
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• 제8권3호
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• pp.132-136
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• 2004

Delayed luminescence of plant leaves was imaged by a 2-D cooled charge-coupled device. We report the delayed luminescence imaging of normal/injured leaves picked ami the leaves intact. The luminescent intensity was lower in leaf veins, scars and edge cut. The intensity of delayed luminescence from intact leaves was higher than that of picked leaves. These results indirectly support the argument that the delayed luminescence of a photosynthetic system is closely related to the electron transfer process of PSII in the thylakoid membrane.

• 한국세라믹학회지
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• 제48권3호
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• pp.251-256
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• 2011

The luminescence properties of polycrystalline ZnO annealed in reducing ambience ($H_2/N_2$) have been studied. An effective quenching of green luminescence with enhanced UV emission from polycrystalline ZnO is observed for the reduced ZnO. The variations of the UV and green luminescence band upon reduction treatment are investigated as a function of temperature in the range between 20 and 300 K. Upon annealing treatment in reducing ambience, the optical quality of polycrystalline ZnO is improved. The UV to green intensity ratio of sintered ZnO approaches close to zero (~0.05). However, this ratio reaches more than 13 at room temperature for polycrystalline ZnO annealed at $800^{\circ}C$ in reducing ambience. Furthermore, the full width at half maximum (FWHM) of the UV band of polycrystalline ZnO is reduced compared to unannealed polycrystalline ZnO. Electron paramagnetic resonance (EPR) measurements clearly show that there is no direct correlation between the green luminescence and oxygen vacancy concentration for reduced polycrystalline ZnO.

• 한국결정성장학회지
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• 제6권4호
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• pp.564-570
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• 1996

급속 열산화 없이 다공성 실리콘으로부터 적색 및 청색 발광을 관찰할 수 있었다. 묽은 HF 농도에서, 특히 짧은 양극 산화 북식으로제조한 aged 된 다공성 실리콘은 청색band 의 증가를 나타내었다. 상온에서 측정된 발광 decay 시간은 약 100 ps를 나타내었고 20K에서 측정된 값에 비하여 상당히 빠른 값을 지니고 있었다. 청색 광발광 peak 최대값은 액체질소온도에서 청색전이를 나타내지 않았다. 그러나 적색 광발광 band는 77K 에서 적색으로 전이를 하였고 황색을 나타내었다. 적색 발광의 origin은 Si 결정과 연관이 있는 것으로 사료되어지는 한편 청색 발광은 Si결정과 무관한 것으로 생각되어 진다.

• Journal of Radiation Protection and Research
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• 제41권3호
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• pp.222-228
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• 2016

Background: We are developing a small size dosimeter for dose estimation in particle therapies. The developed dosimeter is an optical fiber based dosimeter mounting an radiation induced luminescence material, such as an OSL or a scintillator, at a tip. These materials generally suffer from the quenching effect under high LET particle irradiation. Materials and Methods: We fabricated two types of the small size dosimeters. They used an OSL material Eu:BaFBr and a BGO scintillator. Carbon ions were irradiated into the fabricated dosimeters at Heavy Ion Medical Accelerator in Chiba (HIMAC). The small size dosimeters were set behind the water equivalent acrylic phantom. Bragg peak was observed by changing the phantom thickness. An ion chamber was also placed near the small size dosimeters as a reference. Results and Discussion: Eu:BaFBr and BGO dosimeters showed a Bragg peak at the same thickness as the ion chamber. Under high LET particle irradiation, the response of the luminescence-based small size dosimeters deteriorated compared with that of the ion chamber due to the quenching effect. We confirmed the luminescence efficiency of Eu:BaFBr and BGO decrease with the LET. The reduction coefficient of luminescence efficiency was different between the BGO and the Eu:BaFBr. The LET can be determined from the luminescence ratio between Eu:BaFBr and BGO, and the dosimeter response can be corrected. Conclusion: We evaluated the LET dependence of the luminescence efficiency of the BGO and Eu:BaFBr as the quenching effect. We propose and discuss the correction of the quenching effect using the signal intensity ratio of the both materials. Although the correction precision is not sufficient, feasibility of the proposed correction method is proved through basic experiments.

• Bulletin of the Korean Chemical Society
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• 제23권8호
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• pp.1154-1156
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• 2002

• 암석학회지
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• 제10권3호
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• pp.202-211
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• 2001

루미네센스(luminescence)는 석영이나 장석 등과 같은 무기결정이 외부에서 에너지를 받아 흡수된 에너지를 빛으로 바꿔 외부에 방출하는 물리적인 현상이다. 가전자대(valence band)에 존재하는 하전입자들은 전리성 방사선에 의해 전자와 정공(hole)으로 이온화 되고, 이온화된 전자와 정공들은 결정 내에서 자유로이 움직이다가 결정 내에 존재하는 격자결함에 포획된다. 이러한 결정을 빛으로 여기하면 격자결함에 포획된 전자들이 결함에서 빠져 나와 발광중심(recombination center)에서 정공과 재결합하면서 빛을 동반하게 되는데, 이를 광 여기 루미네센스(optically stimulated luminescence; OSL)라 한다. 열 루미네센스(thermoluminescence; TL) 연대 측정법의 원리와 같이, 광 여기 루미네센스를 적당한 조건에서 관측하면 퇴적층의 연대 계산에 응용할 수 있다. 광 여기 루미네센스를 연대측정에 이용하면 빛에 민감한 전자들만 여기시킬 수 있는 장점이 있다. 이 연구에서는 신기 퇴적층으로부터 분리된 석영을 청색 파장의 빛으로 여기하여 그로부터 검출된 광 여기 루미네센스를 신기 퇴적층의 연대 산출에 응용하였다. 논문에서는 광 여기 루미네센스 연대측정법과 관련된 일련의 실험방법 및 최근에 소개된 연구성과, 그리고 앞으로 보다 신뢰도 높은 연대측정 결과를 얻기 위해 연구되어야 할 내용을 이 연구에서 수행한 신기 퇴적층의 연대측정 결과와 함께 기술하였다.

• 대한화학회지
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• 제46권6호
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• pp.502-508
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• 2002

본 실험은 N-Carbamoylglycine의 농도 결정에 PET sensor를 응용한 것이다.N-Carbamoylglycine이 금속 이온에 리간드로 작용하면서 착물을 만들고 있는 fluorophore의 luminescence intensity를 변화시킬수 있고 이를 통해 농도결정에 이용할 수 있다. 사용한 금속이 온은 $Ni^{2+}$, $Cu^{2+}$ 그리고 $Zn^{2+}$이며 비교대상으로 아세트산을 사용하여 선택성을 확인하였다. $Ni^{2+}$ 이온은 음이온 리간드에 의해서 eT mechanism 변화를 보여주었으며 , $Cu^{2+}$이온은 아세트산과 N-Carbamoylglycine을 구별하는 선택성을 가지고 있으며, $Zn^{2+}$이온은 매우 예민한 luminscence intensity 변화를 일으키는 것으로 나타났다.

• 한국재료학회지
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• 제28권10호
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• pp.578-582
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• 2018

ZnO crystals with different morphologies are synthesized through thermal evaporation of the mixture of Zn and Cu powder in air at atmospheric pressure. ZnO crystals with wire shape are synthesized when the process is performed at $1,000^{\circ}C$, while tetrapod-shaped ZnO crystals begin to form at $1,100^{\circ}C$. The wire-shaped ZnO crystals form even at $1,000^{\circ}C$, indicating that Cu acts as a reducing agent. As the temperature increases to $1,200^{\circ}C$, a large quantity of tetrapod-shaped ZnO crystals form and their size also increases. In addition to the tetrapods, rod-shaped ZnO crystals are observed. The atomic ratio of Zn and O in the ZnO crystals is approximately 1:1 with an increasing process temperature from $1,000^{\circ}C$ to $1,200^{\circ}C$. For the ZnO crystals synthesized at $1,000^{\circ}C$, no luminescence spectrum is observed. A weak visible luminescence is detected for the ZnO crystals prepared at $1,100^{\circ}C$. Ultraviolet and visible luminescence peaks with strong intensities are observed in the luminescence spectrum of the ZnO crystals formed at $1,200^{\circ}C$.