• Journal of the Korean Chemical Society
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• v.60 no.1
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• pp.28-33
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• 2016

The spiropyran is a typical material having photodegradation properties in the process of photochromism. The spiropyran has been utilized in various applications such as optical switch, optical memories, and biosensor because of its remarkable stability, fast responsive time, stronger color change, and photo-induced controllability. However, the spriropyran is photodegraded by the repetitive optical irradiation. The photodegradation of spiropyran have been investigated by using UV-Visible spectroscopy, nuclear magnetic resonance (NMR), and Raman spectroscopy. Herein, the properties of spiropyran were characterized by using terahertz time-domain spectroscopy (THz-TDS) in the terahertz frequency region. In terahertz region, the measured absorbance of spiropyran was increased due to the photodegradation induced by the repetitive UV irradiation. The absorbance tendency of spiropyran in the terahertz frequency region was compared with that in the visible region, and they were completely opposite to each other.

• Korean Journal of Crystallography
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• v.10 no.2
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• pp.110-113
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• 1999

x의 범위가 0.5

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.76-77
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• 2000

포화흡수분광(saturated apsorption spectroscopy)$^{[1]}$ 은 원자나 분자의 도플러 선폭확대를 제거할 수 있는 고분해 분광법 중의 하나이다. 이 방법은 조사하려는 매질에 서로 반대방향으로 진행하는 펌프광과 조사광을 비추어, 펌프광의 주파수가 원자의 에너지 준위에 공진 될 때, 매질 내에서 조사광의 흡수가 달라지는 현상을 이용하는 것이다. 특히 알카리 원자의 경우, 바닥상태에 두 개의 초미세준위를 가지고 있고 들뜬상태의 수명이 짧으므로 약한 펌프광에 의해서도 쉽게 이 현상을 관찰할 수가 있다(그림 1 (a), 그림 2 (a)). (중략)

• The Journal of Natural Sciences
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• v.12 no.1
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• pp.49-59
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• 2002

Exponential decrease of saturation absorption signal was reported in pump beam spacially keeping off from probe beam. Optimum angle between pump beam and probe beam in the differential-velocity-selective saturation absorption spectroscopy was computed theoretically, $1.33^{\circ}$ in cesium atoms and $1.08^{\circ}$ in Rb 87 atoms, and was good agreement with the experimental results.

• Journal of dental hygiene science
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• v.9 no.2
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• pp.189-195
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• 2009

Two diketones, 1,2-phenylpropanedione (PD) and diacetyl (DA) were investigated as new visible light photosensitizers for dental composite resin of bis-GMA in order to improve the photopolymerization effect. The photopolymerization efficiency of bis-GMA composite resin containing PD and DA was studied by IR absorption spectroscopy. And the results were compared with that of camphorquinone (CQ). Relative photopolymerization efficiency of the photosensitizers increased in the order of DA < CQ < PD. Thus. PO is a new visible light photosensitizer for dental composite resin with higher photopolymerization efficiency than that of CQ.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.194.2-194.2
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• 2016

저주파 (수십 kHz)와 고주파 (13.56 MHz)로 구동되는 대기압 플라즈마 젯을 발생시키고, 인가전압 (혹은 인가전력)과 기체 유량에 따른 대기압 플라즈마의 특성을 비교하였다. 고주파에서 발생된 플라즈마는 저주파의 경우보다 안정적이었으며, 인가전압 (혹은 인가전력)이 증가함에 따라 플라즈마 기체온도는 상승하였고, 고주파 젯의 기체온도는 저주파 젯 보다 높았으나 330 K이하인 것을 확인하였다. Optical Emission Spectroscopy (OES)를 이용하여 저주파와 고주파의 광 방출 특성을 측정하였다. 저주파에서는 $N_2{^+}$ (391.4 nm)의 intensity 증가가 두드러지게 나타났지만 고주파 젯에서는 $N_2$, $N_2{^+}$의 intensity는 감소하였으며, OH, NO, $H_{\alpha}$, O와 같은 활성 산소 종 (Reactive Oxygen Species)이 저주파 젯 보다 높게 측정되었다. Boltzmann plot method를 이용한 분석을 통해 저주파와 고주파 영역에서의 플라즈마 전자 여기 온도를 측정하였다. 또한 자외선 흡수분광법을 이용하여 플라즈마-액체 계면에서의 OH이 입자밀도를 측정하여 OES방법으로 측정한 OH 밀도와 비교하였다. 그리고 화학적 측정법 (terephtalic acid solution)을 이용하여 액체 내의 OH의 농도를 측정하였다.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.216-217
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• 2000

상자성을 갖는 분자에 대한 분광학 연구에서는 제만(Zeeman) 효과로 생기는 이색성을 이용한 magnetic rotation spectroscopy (MRS)가 널리 사용되고 있다.$^{(1)}$ MRS가 일반적인 흡수 분광법에 비해 더 민감한 측정을 할 수 있기는 하지만 사용하는 편광기의 extinction ratio에 의해 감도가 한정된다. MRS의 감도를 높이는 방법으로는 광경로를 길게 만드는 것을 고려할 수 있다. 일반적으로 공진기 광자감쇠 분광학(Cavity Ring-Down Spectroscopy, CRDS)은$^{(2)}$ 높은 반사율을 갖는 거울을 사용해서 수 km 이상의 광 경로를 만들기 때문에 감도가 높다. (중략)

• Korean Journal of Optics and Photonics
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• v.10 no.5
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• pp.357-363
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• 1999

A frequency domain spectroscopic system was constructed to investigate the optical properties of multiple scattering media. The alternating current (AC) and phase lag components of backscattered light were measured by using the heterodyne detection method. Absorption and transport scattering coefficients were computed from the values based on diffusion theory. Predictions showed excellent matches in comparison with actual values of absorption and scattering. Predictable ranges of the optical coefficients were analyzed in terms of the distance between light source and detector, and modulation frequencies. A proposed compact experimental set-up using laser diodes can be utilized to estimate non-invasively the optical properties of multiple scattering media such as biological tissues.

• Journal of the Korean Chemical Society
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• v.51 no.4
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• pp.331-338
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• 2007

A rapid, simple and sensitive spectrophotometric method was developed for the determination of cobalt(II) using 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC) as a analytical reagent. The metal ion in aqueous medium forms a brown coloured complex with HMBATSC at pH 6.0. The complex has two absorption maxima at 375 nm and 390 nm. At 375 nm, the reagent shows considerable absorbance, while at 390 nm the reagent does not shows appreciable absorbance. Hence, analytical studies were carried out at 390 nm. Beer's law is obeyed in the range of 0.059-2.357 μg ml-1 of Co(II). The molar absorptivity and Sandall's sensitivity of the method are 2.74×104 l mol-1 cm-1 and 0.0024 μg cm-2 respectively. The interference of various diverse ions has been studied. The complex has 1:2 [Co(II)- HMBATSC] stoichiometry. A method for the determination of cobalt(II) by second order derivative spectrophotometry has also been proposed. The proposed methods were applied for the determination of cobalt(II) in alloy steels, vitamin B12 and in some biological samples.

• Analytical Science and Technology
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• v.15 no.4
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• pp.341-345
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• 2002

The extent of UV-curing photo-polymerization reaction was monitored by near-IR spectroscopic method. Acrylates containing quaternary ammonium salts and Darocur 1173 were used as reactive monomer and a photo initiator, respectively. The extent of photo-polymerization reaction was obtained from the conversion ratio of acrylate double bond calculated from the intensities of measured bands at 1615 nm and at 2105 nm. Near-IR spectroscopic methods can be an useful tool for the monitoring of the progress of photo-polymerization.