• The korean journal of orthodontics
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• v.48 no.6
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• pp.377-383
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• 2018

Objective: This study was performed to investigate the effects of external tooth bleaching with flouridation on the appearance of white spot lesions (WSLs) in vitro. Methods: In total, 125 bracket-bonded bovine incisor enamel blocks with artificial WSLs were randomly divided into a control group and four treatment groups (home bleaching, home bleaching + fluoridation, in-office bleaching, and in-office bleaching + fluoridation). A spectroradiometer (SR) and digital images (DIs) were used to evaluate colorimetric parameters (Commission Internationale l'Eclairage $L^*a^*b^*$) for all specimens. Color measurements were obtained before WSL formation (T1), after WSL formation (T2), and after completion of the external tooth bleaching treatment (T3). Results: The SRbased color change after bleaching was significantly greater in the treatment groups than in the control group (p < 0.05). SR-based lightness ($L^*$) and redgreen ($a^*$) values were significantly higher at T2 than at T1 (p < 0.001), with no significant changes in yellow-blue ($b^*$) values. At T3, SR-based $L^*$ values had increased while $a^*$ and $b^*$ values had decreased in the treatment groups (p < 0.001). The DI-based color difference between the sound enamel and WSL areas (DE*DI) increased significantly from T1 to T2 in all groups (p < 0.001) and significantly decreased from T2 to T3 in the treatment groups (p < 0.001). No significant differences in ${\Delta}E^*DI$ at T3 were shown between the four treatment groups (p > 0.05). Conclusions: The findings of this study suggested that external tooth bleaching with fluoridation can alleviate the conspicuity of WSLs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.10
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• pp.1263-1269
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• 2016

Stress has become one of the largest health risk to shorten the life time of health. Accordingly, in order to increase the life time of health, stress relief can be very important. Many social expenses and economic commitment have been inputted for this purpose, but their effectiveness compared to the current situation is not very high. In this paper, we carried out an identification work of rain sound which is similar to the white noise that can stabilize the body and mind of the person by analyzing the variations of 3rd formant frequency bandwidth. Also, for relieving stress, the sounds of rain that is easily accessible at a relatively among the sounds of nature instead of consuming a lot of money and time were selected for solving these problems. In addition, we identified the effectiveness of the stress relief about the sound of rain and research on whether there is a difference between men and women in their 20's or not was performed. Finally, we discussed the personal - adjusted rain making to maximize the effectiveness of stress relief.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.969-974
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• 2007

In this paper, a beamforming technique is introduced to measure the acoustic impedance at both normal and oblique incidence in a free field. The acoustic impedance is obtained by separating incident and reflected signals using the adaptive nulling method which is one of the various beamforming algorithms. To obtain better results, pressure vector commonly used in array signal processing is replaced with the transfer function vector between each microphone and the white Gaussian noise is suppressed by a wavelet shrinkage technique. The experiments conducted in a semi-anechoic room show that the proposed method is efficient and accurate in measuring the acoustic impedance of sound absorbing materials under a free field condition.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1450-1454
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• 2007

주상복합형 주거공간에 각 실간 Cross Talking에 의한 소음을 저감시키고 실내기의 공기조화로 발생하는 팬의 소음을 저감 시키기 위하여 소음 환기 장치를 개발 하였다. 공명형과 팽창형의 특성을 적용한 복합적 소음기로 저감주파수 대역에 따른 설계가 가능하며 이 소음기 성능시험 결과 특정 주파수 대역에서 20dB이상의 삽입손실치가 발생하고, 삽입에 의한 압력손실 2mmAq 이하가 됨을 확인하였다. 본 개발품의 특성은 구조가 간단하고 분해조립이 가능하여 설치 및 유지보수가 용이한 제품이다.

• Journal of Welding and Joining
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• v.34 no.5
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• pp.6-12
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• 2016

This study was performed bead welding of pure titanium by using fiber laser. Since titanium is very sensitive to oxidation and nitriding during welding, it is important to compose the shielding equipment compared with different material. Thus side and coaxial shield nozzle, rail and chamber type shielding equipment are widely used to protect effectively the weld during welding. Experiments were performed by changing nozzle angle and distance using side and coaxial shield nozzle. The bead colors of gold, brown, blue, purple and yellowish white were obtained by changing variables of shield nozzle, and then its weldability was investigated. As experiment result, sound and not brominated beads were formed when side nozzle angle and distance were respectively $45^{\circ}$ and 10 mm.

• Journal of Biosystems Engineering
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• v.35 no.2
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• pp.138-145
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• 2010

An on-line algorithm that discriminates brown rice kernels on their echelon feeder using color image processing is presented for quality inspection. A rapid color image segmentation algorithm based on Bayesian clustering method was developed by means of the look-up table which was made from the significant clusters selected by experts. A robust estimation method was presented to improve the stability of color clusters. Discriminant analysis of color distributions was employed to distinguish nine types of brown rice kernels. Discrimination accuracies of the on-line discrimination algorithm were ranged from 72% to 85% for the sound, cracked, green-transparent and green-opaque, greater than 93% for colored, red, and unhulled, about 92% for white-opaque and 67% for chalky, respectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1247-1251
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• 2006

공동주택의 보급 증가에 따라 화장실과 같이 환기용 덕트를 통한 층간 소음전달 문제가 예상되어 환기용 덕트에 간단히 설치하여 층간 소음 전달을 차단할 수 있는 환기장치용 소음기를 개발하였다. 본 개발품은 소음 차단 기능이 확실하고, 구조가 간단하며 분해조립이 가능하여 설치 및 유지보수가 용이한 제품이다. 또한 습기에 의한 부식이 없고, 먼지와 습기를 쉽게 제거할 수 있는 특징이 있다. 성능시험 결과 환기용 덕트를 통한 소음의 전달을 10dB 이상 저감시킬 수 있고, 삽입에 의한 압력손실 2mmAq 이하가 됨을 확인하였다.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.951-956
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• 2008

Development of a silencer to Reduce Noise of Cross Talking in Apartment & Stores and air conditioning to fan Composite silencer application a specific of resonant type and expansion type, design possibility at reduction frequency. This silencer test result develop reduce 20dB of specification frequency. Pressure loss 2mmAq. This silencer is special of brief structure and possibility disjoint and joint, simple installation and maintenance.

• English & American cultural studies
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• v.9 no.1
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• pp.71-90
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• 2009

David Harris argues that mass media suppress counter-hegemonic factors in order to reach audience. According to Harris's theory, the success of the film "Tess" depends on its effective adaptation from Thomas Hardy's novel Tess of the D'Urbervilles (1891). Tess (1979), directed by Roman Polansky, casting Nastassia Kinski for Tess, was acclaimed as a professional and commercial success, awarded with various prizes. Hardy's aim at criticizing Victorian English social and moral standard through Tess appears obscure in Polansky's film which focuses on the aesthetics of human body and capital. Polanski's Tess with urban white beauty does not emerge victimized by poverty, which the late twentieth century audience under the capitalist umbrella may abhor. To examine his use of music, sound effect, visual images by means of camera operation—angles, distances, close-ups and frequent movements—light and color, and mythic elements in the film, show Polansky's sharp perception of his contemporary audience's desire and conscientious work upon it.

• International Journal of Advanced Culture Technology
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• v.9 no.4
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• pp.320-328
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• 2021

As the number of visually impaired people steadily increases, interest in independent walking is also increasing. However, there are various inconveniences in the independent walking of the visually impaired at present, reducing the quality of life of the visually impaired. The white cane, which is an existing walking aid for the visually impaired, has difficulty in recognizing upper obstacles and obstacles outside the effective distance. In addition, it is inconvenient to cross the street because the sound signal to help the visually impaired cross the crosswalk is lacking or damaged. These factors make it difficult for the visually impaired to walk independently. Therefore, we propose the design of an embedded system that provides traffic light recognition through object recognition technology, voice guidance using TTS, and upper obstacle recognition through ultrasonic sensors so that blind people can realize safe and high-quality independent walking.