• Bulletin of the Korean Chemical Society
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• 제21권7호
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• pp.701-704
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• 2000

Fluorene and carbazole-containing distyrylarylene model and polymeric fluorophores were prepared by reacting 2,7-dibromo-9-butylfluorene and 3,6-dibromo-9-butylcarbazole with styrene and divinylbenzene using the Heck reaction for the chemiluminesc ence. The UV-vis absorbance, photoluminescence (PL) as well as the chemiluminescence (CL) characteristics of the model and polymeric fluorophores were measured. Sodium salicylate-catalyzed reaction of bis(2,4,6-trichlorophenyl)oxalate (TCPO) with hydrogen peroxide produced a strong chemiluminescent blue light emission with 439-489 nm in the presence of the fluorophore. The wave-length of CL light was similar to that of photoluminescence. The chemiluminescent intensity was decayed according to the exponential equation.The glow of CL maintained more than 12 hr and was visible with naked eye.

• Bulletin of the Korean Chemical Society
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• 제22권7호
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• pp.727-731
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• 2001

Conjugated-non-conjugated alternating block copolymers containing distyrylarylene units were synthesized via Wittig reaction for chemiluminescent fluorophores. The polymers were differentiated from others by the presence of aromatic unit in the chromophoric block. When UV-VIS, photoluminescence and chemiluminescence spectra of these materials were compared with copolymers, a strong bathochromic effect was observed. A more pronounced red shift and higher chemiluminscence efficiency were observed in the polymer with anthracene ring. Sodium salicylate-catalyzed reaction of bis(2-carbopentyloxy-3,5,6-trichlorophenyl) oxalate with hydrogen peroxide produced a strong chemiluminescence from blue to yellow-green light emission with wavelength of 450-537 nm in the presence of the fluorophore. The chemiluminescent intensity decayed exponentially. The glow of chemiluminescence maintained more than l2 hr and was visible with the naked eye.

• Bulletin of the Korean Chemical Society
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• 제17권7호
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• pp.607-612
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• 1996

A series of new NLO-active poly(4-nitrophenylallylamine) derivatives was synthesized by the nucleophilic substitution reaction of several substituted 4-nitrohalobenzenes and poly(allylamine hydrochloride). All polymers obtained were amorphous and their glass transition temperatures (Tg) were observed around 148-160 ℃. For each of these polymers, their specific Tg values were dependent on characteristic electronic structures. UV-visible absorption spectra showed maximum absorption intensity at 355-393 nm for π-π* transition of alkylaminonitrophenyl groups. The χ(2)value of poly(4-nitrophenylallylamine), as determined by the second harmonic generation at 1064 nm, for a thin polymer film poled at an elevated temperature, was 1.4x10-8esu. The third-order NLO properties of poly(4-nitrophenylallylamine) derivatives were evaluated through measurement of degenerate four-wave mixing technique and χ(3) coefficient in the range of 2.7~3.2x10-12 esu at 602 nm was found with 400 fs laser pulses.

• 한국컴퓨터정보학회논문지
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• 제24권6호
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• pp.73-80
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• 2019

In this paper, we propose an effective dynamic range compression (DRC) method of infrared images. A histogram of infrared images has narrow dynamic range compared to visible images. Hence, it is important to apply the effective DRC algorithm for high performance of an infrared image analysis. The proposed algorithm for high dynamic range divides an infrared image into the overlapped blocks and calculates Shannon's entropy of overlapped blocks. After that, we classify each block according to the value of entropy and apply adaptive histogram modification method each overlapped block. We make an intensity mapping function through result of the adaptive histogram modification method which is using standard-deviation and maximum value of histogram of classified blocks. Lastly, in order to reduce block artifact, we apply hanning window to the overlapped blocks. In experimental result, the proposed method showed better performance of dynamic range compression compared to previous algorithms.

• Current Photovoltaic Research
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• 제7권2호
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• pp.29-32
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• 2019

Large band gap attenuation of CdS nanoclusters in hybrid sol gel matrix comprised of 3-(trimethoxysilyl)propyl methacrylate (TMSPM), 15 wt. % zirconium, and various amounts of cadmium acetate was observed after $H_2S$ exposure. Hybrid sol gel matrixes were prepared by hydrolysis and condensation reactions. The sol gels contained with various amount of cadmium acetate were spin coated to glass substrates and exposed to $H_2S$ gas. The UV-visible absorption peaks were shifted toward blue with increasing the amount of CdS nanoclusters and were shifted to the red after thermal process. Significant amount of -OH absorption peaks were reduced after thermal process. Strong room temperature photoluminescence (PL) of CdS nanoclusters was observed after exposing to $H_2S$ gas. The PL intensity increased for several minutes and slowly decreased thereafter. The luminescence peaks were continuously shifted toward blue as the time passed. Extraordinary Stokes shift (approximately 160 nm) was observed.

• 센서학회지
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• 제15권3호
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• pp.186-191
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• 2006

In general, Cerenkov light is produced by a charged particle that passes through a medium with a velocity greater than that of visible light. Although the wavelength of Cerenkov light is very broad, the peak is in the almost visible range from 400 to 480 nm. Therefore, it always causes a problem to detect a real light signal that is generated in the scintillator on the fiber-optic sensor tip for dose measurements of high-energy electron beam. The objectives of this study are to measure, characterize and remove Cerenkov light generated in a fiber-optic radiation sensor tip to detect a real light signal from the scintillator. In this study, the intensity of Cerenkov light is measured and characterized as a function of incident angle of electron beam from a LINAC, and as a function of the energy of electron beam. As a measuring device, a photodiode-amplifier system is used, and a subtraction method using a background optical fiber is investigated to remove Cerenkov light.

• 멤브레인
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• 제21권2호
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• pp.171-176
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• 2011

분리막을 이용한 수처리 공정에서 유입 수에 함유된 부유물질이나 기타 오염물질이 막 표면 또는 내부에 축적 흡착 등의 막 오염현상으로 인해 막 성능 감소와 함께 막 분리 공정에 큰 영향을 미치게 된다. 본 연구에서는 막 표면에서의 막 오염현상을 실시간으로 모니터링 할 수 있는 기술을 연구하였다. 투명한 오염물질에 의한 분리막 표면 오염을 측정하기 위해 막 표면에 360 nm 파장의 가시광선을 조사하여 이미지를 R. G. B 값으로 추출하여 막의 오염현상을 실시간으로 모니터링 하였다. 추출된 이미지 중 400~499 nm 파장영역인 B 값이 가장 강도가 강하게 나타났다. 막 오염정도의 변화를 이미지의 강도 차이로 관찰함으로써 실시간 분석이 가능함을 확인하였다.

• 한국결정성장학회지
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• 제19권5호
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• pp.251-255
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• 2009

나노사이즈의 귀금속을 $TiO_2$ 매트릭스에 균질하게 분산 시킨 구조는 염료감응형 태양전지의 유망한 광전극 특성을 나타내는 것으로 보고되고 있다. 이와 같은 금 및 백금 나노미립자를 균질하게 분산된 구조의 광전극을 제작하기 위하여 석영 및 ITO 기판위에 동시스퍼터법에 의하여 박막을 합성 하였다. XRD분석을 통하여 상분석을 수행 한 결과 합성된 나노컴포지트는 Rutile상이 지배적인 결정 구조를 나타냈으며 열처리를 $600^{\circ}C$까지 진행함에 따라 $TiO_2$ 결정성의 향상 및 귀금속인 금 및 백금의 나노미립자가 증가 하는 결과를 나타내었다. 귀금속인 금 및 백금이 분산된 $TiO_2$ 광전극에서는 자외선(UV) 영역을 포함하여 가시광(VIS) 영역의 빛의 조사에 광전류 응답 특성을 발현 하였다. 가시광선 영역에서 발현된 광전류 응답 특성은 나노사이즈로 분산된 금 및 백금 금속과 $TiO_2$와의 계면 준위에 기인 한 것으로 판명 되었다.

• Journal of Korean Neurosurgical Society
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• 제45권5호
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• pp.284-288
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• 2009

Objective : Our retrospective study aimed to determine whether 16-slice computerized tomography (CT) angiography optimized sharp kernel is suitable for the evaluation of visibility, luminal patency and re-stenosis of intracranial stents in comparison with conventional angiography. Methods : Fifteen patients with symptomatic intracranial stenotic lesions underwent balloon expandable stent deployment of these lesions (10 middle cerebral arteries, 2 intracranial vertebral arteries, and 3 intracranial internal carotid arteries). CT angiography follow-up ranged from 6 to 15 months (mean follow-up, 8 months) after implantation of intracranial stents and conventional angiography was confirmed within 2 days. Curved multiplanar reformations with maximal intensity projection (MIP) with optimal window settings for assessment of lumen of intracranial stents were evaluated for visible lumen diameter, stent patency (contrast distal to the stent as an indirect sign), and re-stenosis by two experienced radiologists who blinded to the reports from the conventional angiography. Results : All of stents deployed into symptomatic stenotic lesions. All stents were classified as patent and no re-stenosis, which was correlated with results of conventional angiography. Parts of the stent lumen could be visualized in all cases. On average, 57% of the stent lumen diameter was visible using optimized sharp kernel. Significant improvement of lumen visualization (22%, p<0.01) was observed using the optimized sharp kernel compared with the standard sharp kernel. Inter-observer agreements on the measurement of lumen diameter and density were judged as good, respectively (p<0.05). Conclusion : Sixteen-slice CT using the optimized sharp kernel may provide a useful information for evaluation of lumen diameter patency, and re-stenosis of intracranial stents.

• Archives of Plastic Surgery
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• 제36권1호
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• pp.66-74
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• 2009

Purpose: The importance of the deformities in alar - columellar complex has been underestimated in Asian ethnic groups for the last decades. Fortunately, with increasing familiarity of the open rhinoplasty techniques, the anatomic details of the nasal tip have been pointed up. Definitely, having an interest and demand for improving the sub - normal relationship between the alar rim and columella are indebted for such growing of knowledge about nasal tip anatomy. However, it is true that any single procedure is not settled as versatile and fully confident modality to correct the retracted notching of the alar rim. With this article, I should like to propose another useful option for treating retracted ala. Methods: The author has tried to correct alar rim retraction by means of: (1) Triangular onlay septal cartilage graft on the lower lateral cartilage with the medial end fixed to the anterior surface of the lateral crus(Alar extension graft), (2) Inserting lateral end of the alar extension graft to the vestibular skin pocket in the form of a finger - in - groove, (3) using the vestibular skin in the form of an advancement flap, and (4) using the soft shield graft to prevent possible visible step - off of the alar margin. Results: The author applied an alar extension graft to 16 patients in order to correct a retracted ala for the last 27 months (August, 2003 - October, 2005). The distances from alar rim to long axis of nostril were improved to be within 2 mm in all of the cases, and also the shape of the alar rim changed to a round form. Nostril asymmetry (6%) in one case, temporary palpable step - off (18%) in three cases, temporary visible step - off (6%) in one case, and temporary paresthesia of the tip (25%) in four cases were observed. Conclusion: The alar extension graft is simple and efficacious. It does not need donor sites other than the operative field, and its results are predictable. In particular, since it may give structural intensity to a weak lower lateral cartilage, it may be preferentially used for the correction of a retracted ala that arises from hypoplastic lower lateral cartilage. Moreover intensified lower lateral cartilage also improves the esthetic shape of lobule.