• Journal of Periodontal and Implant Science
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• 제47권1호
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• pp.13-19
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• 2017

Purpose: The purpose of this study was to examine whether periodontal pocket could be satisfactorily visualized by optical coherence tomography (OCT) and to suggest quantitative methods for measuring periodontal pocket depth. Methods: We acquired OCT images of periodontal pockets in a porcine model and determined the actual axial resolution for measuring the exact periodontal pocket depth using a calibration method. Quantitative measurements of periodontal pockets were performed by real axial resolution and compared with the results from manual periodontal probing. Results: The average periodontal pocket depth measured by OCT was $3.10{\pm}0.15mm$, $4.11{\pm}0.17mm$, $5.09{\pm}0.17mm$, and $6.05{\pm}0.21mm$ for each periodontal pocket model, respectively. These values were similar to those obtained by manual periodontal probing. Conclusions: OCT was able to visualize periodontal pockets and show attachment loss. By calculating the calibration factor to determine the accurate axial resolution, quantitative standards for measuring periodontal pocket depth can be established regardless of the position of periodontal pocket in the OCT image.

• 한국수산과학회지
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• 제52권2호
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• pp.114-120
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• 2019

In the case of being contaminated with pathogenic Vibrio, shellfish pose a serious threat for public health. This study was conducted to investigate the presence of Vibrio parahaemolyticus and V. vulnificus in the seawater, bottom deposit and shellfish samples collected from the Gomso Bay, west coast of Korea. V. parahaemolyticus (30-80 CFU/g) was detected from seawater Jul. to Oct. and highest at Sep. V. parahaemolyticus was detected less than 10 CFU/g from seawater at Nov. with $14.6^{\circ}C$ of seawater temperature. V. parahaemolyticus (180-1,850 CFU/g) was detected more than 100 CFU/g from 3 kinds of shellfish, Short-necked clam Ruditapes philippinarum, Corb shell Cyclina sinensis, and Surf clam Mactra veneriformis, Jul. to Oct. and was highest in Surf clam at Oct. V. parahaemolyticus was detected less than 20 CFU/g from all tested shellfish at Nov. V. vulnificus (1.8-2.7 MPN/100 mL) was detected from seawater Jul. to Oct. and was not detected at Nov. V. vulnificus (18-236.7 MPN/100 g) was also detected from 3 kinds of shellfish Jul. to Oct. and was highest in Corb shell at Jul. V. vulnificus was not detected from all tested shellfish at Nov.

• Restorative Dentistry and Endodontics
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• 제44권1호
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• pp.8.1-8.7
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• 2019

Objectives: Irrigants are imperative in endodontic therapy for the elimination of pathogens from the infected root canal. The present study compared the antimicrobial efficacy of octenidine dihydrochloride (OCT) with chlorhexidine (CHX) and sodium hypochlorite (NaOCl) against Staphylococcus epidermidis (S. epidermidis) for root canal disinfection. Materials and Methods: The minimum inhibitory concentration (MIC) was obtained using serial dilution method. The agar diffusion method was then used to determine the zones of inhibition for each irrigant. Lastly, forty 6-mm dentin blocks were prepared from human mandibular premolars and inoculated with S. epidermidis. Samples were randomly divided into 4 groups of 10 blocks and irrigated for 3 minutes with saline (control), 2% CHX, 3% NaOCl, or 0.1% OCT. Dentin samples were then collected immediately for microbial analysis, including an analysis of colony-forming units (CFUs). Results: The MICs of each tested irrigant were 0.05% for CHX, 0.25% for NaOCl, and 0.0125% for OCT. All tested irrigants showed concentration-dependent increase in zones of inhibition, and 3% NaOCl showed the largest zone of inhibition amongst all tested irrigants (p < 0.05). There were no significant differences among the CFU measurements of 2% CHX, 3% NaOCl, and 0.1% OCT showing complete elimination of S. epidermidis in all samples. Conclusions: This study showed that OCT was comparable to or even more effective than CHX and NaOCl, demonstrating antimicrobial activity at low concentrations against S. epidermidis.

• 센서학회지
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• 제26권1호
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• pp.44-49
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• 2017

In this paper, the automatic sweep flattening for wavelength swept laser of SS-OCT has implemented. Through its performance test applied to the laser, 50 nm flat sweeping range, ${\pm}0.5dB$ fluctuation range, 22 sec the time required, and 10 mW average optical power were obtained. This shows that the realized automatic process can replace the inconvenient manual operation used for polarization control of current sweeping laser. Additionally it cuts costs for optical spectrum analyzer necessary to sweep monitoring.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2459-2463
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• 2005

Optical coherence tomography (OCT) is high resolution medical imaging system which is obtaining image inside biological objects with non-destructive method. OCT system is based on Michelson interferometer with a reciprocating mirror in the reference arm and a biological object in the sample arm. The obtained OCT image suffers from a granular or mottled image, called speckle. Speckle is caused by random interferences between reflected coherence waves. In this paper, we propose effective speckle reduction method that uses wavelet transform. With wavelet domain image, sub-windowing and thresholding are performed. Finally, speckle reduction experiments for Misgurnus mizolepis skin and rat eye images are shown.

• 천문학회보
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• 제35권2호
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• pp.34.2-34.2
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• 2010

The 3C84 (NGC 1275), one of Seyfert 2 galaxy, is an interesting object with its peculiar sub-mas structure. We found that the inner jet (r < 2.5mas) of 3C84 seemed to even changed its position angle and flux over one and a half years based on the result of global 86GHz VLBI survey (Lee et al. 2008). In order to confirm the 'precession' of jet, we observed the object in 4 epochs May07, Oct.07, May08 and Oct.08 with the GMVA (Global mm-VLBI Array) at 3mm (86.25GHz) and the each observation time is about 14 hours. Here we present observation and preliminary result of Oct.07 and May08 epochs.

• 센서학회지
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• 제26권5호
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• pp.324-330
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• 2017

In this paper, the automation of sweeping center setting for wavelength swept laser used in SS-OCT has implemented. For 3 regions where the initial FFP-TF pass wavelength can be located, each different DC voltage pattern is applied to FFP-TF. Through its performance test to the laser, fast and exact setting to sweeping central wavelength, flat sweeping with ${\pm}0.5dB$ fluctuation range, and 10 mW average optical power were obtained. This shows that the realized automatic setting process can replace an inconvenient manual setting operation used for current wavelength swept laser. Additionally it cuts costs for optical spectrum analyzer necessary to laser spectrum monitoring.

• 한국임상수의학회지
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• 제30권4호
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• pp.324-328
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• 2013

A 5-year-old intact male Yorkshire terrier dog was referred with a 1-week history of blindness. In both eyes, menace responses and pupillary light reflexes were absent. The indirect ophthalmoloscopy revealed multiple small gray-white and discoloration lesion in mid-nontapetum area in both eyes. Electroretinograms showed diminished amplitude of a- and b-waves. Multifocal serous retinal detachments were detected with optical coherence tomography (OCT) over the small gray-white and discoloration lesion in the fundus. After one week of treatments, the indirect ophthalmoloscopy showed that irregular patches and hyperpigmentation in the center of hyperreflectivity area. Reattachment and retinal thinning were observed by the OCT. The results indicate that OCT scanning is considered to be a useful method for retinal evaluation in dogs with chorioretinitis.

• EDISON SW 활용 경진대회 논문집
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• 제6회(2017년)
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• pp.628-630
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• 2017

관상동맥의 협착 병변의 위험성을 치료 및 예방하기 위하여 FFR(Fractional flow reserve)이라는 지표를 사용한다. 기존의 임상에서 FFR을 측정하기 위하여 침습적인 방법을 이용하여 진행하였다. 이러한 침습적 방법은 부작용의 위험성을 가지고 있기 때문에 컴퓨터 시뮬레이션을 통해 계산하면 위험성을 해소할 수 있다. 하지만 현재 컴퓨터 시뮬레이션은 CT image를 이용하기 때문에 칼슘을 정확히 구별하거나 지질의 위치 등을 확인하는 것이 어렵기 때문에 FFR 결과에 오류를 발생시킬 수도 있고, 또한 전체 관상동맥을 해석하기 때문에 많은 계산량이 필요하다. 본 연구에서는 최근 높은 해상도를 가진 OCT(Optical Coherence Tomography)를 이용하여 이러한 한계점을 극복하고자 하고, 임상에서 측정한 FFR과 OCT에서 측정된 FFR은 비교하는 것이 목적이다.

• Journal of the Optical Society of Korea
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• 제13권3호
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• pp.316-320
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• 2009

A novel broadband wavelength-swept Raman laser was used to implement Fourier-domain mode locked (FDML) swept-source optical coherence tomography (SS-OCT). Instead of a conventional semiconductor optical amplifier, this study used broadband optical fiber Raman amplification, over 50 nm centered around 1545 nm, using a multi-wavelength optical pumping scheme, which was implemented with the four laser diodes at the center wavelengths of 1425, 1435, 1455 and 1465 nm, respectively, and the maximum operating power of 150 mW each. The operating swept frequency of the laser was determined to 16.7 kHz from the FDML condition of 12 km optical fiber in the ring cavity. The OCT images were obtained using the novel broadband wavelengthswept Raman laser source.