• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.443-446
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• 2003

The vibration mode shape changed by the phase angle that can be controlled by phase-shifting ESPI system is discussed. For the phase-shifting ESPI experiment the stroboscopic illumination by using AOM(Acousto-Optic Modulator) is needed, and the initial phase angle can be adjusted by the program. The vibration mode shape is changed when the initial phase angle is changed. We examined the vibration mode shape change due to the initial phase angle change at each resonance frequency. Through this study, we found that in the vibration testing using phase-shilling ESPI the vibration mode shape is improved in the quality by adjusting exact phase angle and the error of the quantitative vibration analysis can be reduced.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.174-174
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• 2004

본 논문에서는 4변이 고정된 정사각형 알루미늄 평판의 진동 진폭을 측정하기 위하여, 기존의 위상 이동 ESP떼 스트로보스코프식 조사를 적용한 스트로보스코픽 ESPI 기법을 이용하였다. 일반적으로 시간평균 ESPI를 이용하면 진동하고 있는 대상체의 정성적인 진동 패턴을 측정할 수 있다. 그러나 시간평균 ESPI로는 진동하고 있는 대상체의 두께방향으로의 진폭량을 측정하기는 어렵다. 또한 일반적인 위상이동법을 적용시킬 경우, 대상체가 진동을 하게 됨으로써 정확한 진동 진폭을 측정하기 어렵다.(중략)

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.2
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• pp.207-220
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• 2006

The newly developed equipments for the early detection of carious lesion are LFD (laser fluorescence device), Ultrasonic diagnostic system, CLSM(confocal laser scanning microscopy), QLF(quantitative light-induced fluorescence) and DIFOTI (digital imaging fiber-optic trans-illumination) system. In this study, DIFOTI system and LFD were used for the detection of early enamel caries. Twenty five primary teeth extracted from twenty one children at around the dentitional exchanging period were selected as samples. The results obtained from DIFOTI imaging and LFD measurement were compared with those of CLSM and comprehensive evaluations were made for the diagnostic capacity of each device. In vitro test, 40 sample teeth with their buccal & lingual surface formed by a window of $2{\times}3mm$ in diameter were immersed in artificial demineralizing solution for the period of 4, 8, 12 and 16 days. The results obtained from the experimental groups (DIFOTI, LFD) were compared to control group (CLSM) and we have reached to the following conclusions. 1. The sensitivity and specificity of DIFOTI system operated in oral environment was 88.2% and 76.9% respectively. 2. The sensitivity and specificity of LFD measured in oral environment was 76.5% and 69.2% respectively. 3, Regression analysis on the light transparent rate of DIFOTI showed its decrease according to the length of primary enamel decalcification performed in vitro(r=-0.96, p<0.05). 4. No statistically significant difference between LFT measurement and the length of in vitro decalcification was found in regression analysis (p>0.05). 5. The correlation coefficient of DIFOTI image transparent rate and the lesion depth of CLMS was -0.6988 (p<0.05), whereas no statistically significant difference was found for LFD measurement.

• Korean Journal of Materials Research
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• v.22 no.7
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• pp.379-383
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• 2012

$TiO_2$ thin films consisting of positively charged poly(diallyldimethylammonium chloride)(PDDA) and negatively charged titanium(IV) bis(ammonium lactato) dihydroxide(TALH) were successfully fabricated on glass beads by a layer-by-layer(LBL) self-assembly method. The glass beads used here showed a positive charge in an acid range and negative charge in an alkaline range. The glass beads coated with the coating sequence of(PDDA/TALH)n showed a change in the surface morphology as a function of the number of bilayers. When the number of bilayers(n) of the(PDDA/TALH) thin film was 20, Ti element was observed on the surface of the coated glass beads. The thin films coated onto the glass beads had a main peak of the (101) crystal face and were highly crystallized with XRD diffraction peaks of anatase-type $TiO_2$ according to an XRD analysis. In addition, the $TiO_2$ thin films showed photocatalytic properties such that they could decompose a methyl orange solution under illumination with UV light. As the number of bilayers of the(PDDA/TALH) thin film increased, the photocatalytic property of the $TiO_2$-coated glass beads increased with the increase in the thin film thickness. The surface morphologies and optical properties of glass beads coated with $TiO_2$ thin films with different coating numbers were measured by field emission scanning electron microscopy(FE-SEM), X-ray diffraction(XRD) and by UV-Vis spectrophotometry(UV-vis).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.453-454
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• 2008

본 논문은 가로등 LED조명 설계를 위해 LED(Light Emiting Diode)소자 특성 분석 및 시뮬레이션을 통한 광 특성을 개선하고자 하였다. 시뮬레이션은 Geometry 와 Optic 특성을 고려하였으며, 광속, 스펙트럼, 지향각, 조도값 분석을 통해 제품과 시뮬레이션 특성을 비교하였다. 광 특성 개선 설계변수로는 $30^{\circ}C{\sim}50^{\circ}$ 사이의 2차 렌즈를 각도별로 설계하여 35 도 렌즈 각도일 때 최대 조도특성을 확인했으며, LED 모듈간 간격 배치는 3Cm 일 때 가장 높은 조도특성이 나타났다. 9개의 LED모둘 각도를 정면 Angle($\theta1$)과 측면 Angle($\theta2$)으로 구분하여 각도에 따라 배치 시켜본 결과, 정면 Angle($\theta1$)은 0도일 때, 측면 Angle($\theta2$)은 10도 일 때 가장 높은 조도 특성이 나타났다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.5
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• pp.227-231
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• 2010

Super hydrophilic $TiO_2$ thin films with photocatalytic property were successfully fabricated on a glass substrate by liquid phase deposition (LPD). The $TiO_2$ thin film formed nano particles on a surface at $70^{\circ}C$. As an immersion time in $TiF_4$ solution increased, the thickness of thin films gradually increased. $TiO_2$ thin film showed a water contact angel of below ca. $5^{\circ}$ and the transmittance of ca. 75~90 % in visible range. In addition, $TiO_2$ thin film showed the photocatalytic property to decompose methyl orange solution by the illumination of UV light. The surface morphologies, optical properties and contact angel of prepared thin films with a different immersion time were measured by field emission scanning electron microscope (FE-SEM), atomic force microscope (AFM), UV-Vis spectrophotometer and contact angle meter.

• The Journal of the Acoustical Society of Korea
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• v.31 no.2
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• pp.73-78
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• 2012

The photophone, Alexander Graham Bell's device for transmitting sound through light was patented in 1880. It included the transmitter modulating and reflecting strong light like sunlight to a distant receiver which produced sound. In this working of the photophone, the discovery of the sound-emitting effect under illumination was very essential. Longing for being famous in the scientific community, Bell focused on presenting various methods for producing sounds and for maximizing the loudness by performing intensive research on the photoacoustic effect. Bell's scientific research on photoacoustics was successful in establishing himself as a scientist and laid a foundation of photoacoustic analysis. And his invention became a basis for other researchers' subsequent technologies like fiber-optic communication.

• Journal of Korean Neurosurgical Society
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• v.46 no.5
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• pp.479-483
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• 2009

Objective : A mouse model of spinal cord injury (SCI) could further increase our basic understanding of the mechanisms involved in injury and repair of the nervous system. The purpose of this study was to investigate whether methods used to produce and evaluate photochemical graded ischemic SCI in rats, could be successfully adapted to mice, in a reliable and reproducible manner. Methods : Thirty female imprinting control region mice (weighting 25-30 g, 8 weeks of age) were used in this study. Following intraperitoneal injection of Rose bengal, the translucent dorsal surface of the T8-T9 vertebral laminae of the mice were illuminated with a fiber optic bundle of a cold light source. The mice were divided into three groups; Group 1 (20 mg/kg Rose bengal, 5 minutes illumination), Group 2 (20 mg/kg Rose bengal, 10 minutes illumination), and Group 3 (40 mg/kg Rose bengal, 10 minutes illumination). The locomotor function, according to the Basso-Beattie-Bresnahan scale, was assessed at three days after the injury and then once per week for four weeks. The animals were sacrificed at 28 days after the injury, and the histopathology of the lesions was assessed. Results : The mice in group 1 had no hindlimb movement until seven days after the injury. Most mice had later recovery with movement in more than two joints at 28 days after injury. There was limited recovery of one joint, with only slight movement, for the mice in groups 2 and 3. The histopathology showed that the mice in group 1 had a cystic cavity involving the dorsal and partial involvement of the dorsolateral funiculi. A larger cavity, involving the dorsal, dorsolateral funiculi and the gray matter of the dorsal and ventral horns was found in group 2. In group 3, most of the spinal cord was destroyed and only a thin rim of tissue remained. Conclusion : The results of this study show that the photochemical graded ischemic SCI model. described in rats, can be successfully adapted to mice, in a reliable and reproducible manner. The functional deficits are correlated an increase in the irradiation time and, therefore, to the severity of the injury. The photothrombotic model of SCI, in mice with 20 mg/kg Rose bengal for 5 minutes illumination, provides an effective model that could be used in future research. This photochemical model can be used for investigating secondary responses associated with traumatic SCI.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.2
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• pp.666-671
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• 2016

This paper introduces a device providing close local lighting to the affected part, where the operation-purpose astral lamp alone cannot shed light directly, in an operation room of hospitals or clinics, which helps clinical doctors perform safe treatment of the affected part deep inside a human body. This medical assisting lighting is a device necessary to prevent fatal operation failures, which can occur with minute operation processes, such as tumor removal or angiorrhaphy. The components, such as the light source and power supply were designed to be low power consuming and small in size, have a narrow angle lens was used to increase the light spreading effect and focused illumination. The end-caps of the light transmission device using an optical cable and the lighting device were designed in the waterproof type to enable disinfection of these devices after use for the next patients. According to the measurement of the light source properties made after development of the retractor lighting device, the illumination intensity was 490 lux, the brightness was $11,550cd/m^2$, general color rendering index was 78, color temperature was 11,000K, and the intensity distribution was even, which were confirmed to be adequate for medical assisting local lighting.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.1
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• pp.13-23
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• 2010

This study was performed to compare the quality of image processing between the newly developed prototype using light emitting diode(LED) and the conventional $DIFOTI^{TM}$ system(EOS Inc., USA). To estimate the optimal light emitting power for the improved images, primary enamel surfaces treated under Carbopol 907 de-mineralizing solution were taken daily during 20 days of experimental periods by both DIFOTI systems. The results of comparative analyses on the images obtained from both systems with polarized image as gold standard can be summarized as follows: 1. Trans-illumination indices of images taken from primary enamel surfaces were decreased with time in both systems. 2. The differences of intensity of luminance between sound and de-mineralized enamel surface in prototype DIFOTI system was shown to be relatively smaller than conventional $DIFOTI^{TM}$ system. 3. From the comparative analysis of images from both DIFOTI system with polarized images as gold standard, the difference between sound and de-mineralized enamel surface of intensity of luminance of $DIFOTI^{TM}$ system was more correlated to polarized images than prototype of DIFOTI system. With the optimal LED emitting power, the control of aperture of digital camera is considered as the another key factor to improve the DIFOTI images. For the best image quality and analysis, the development of the improved image processing software is required.