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무선 네트워크에서 I, P, B 프레임 패턴에 따론 멀티미디어의 효율적인 전송
문은지,손예진,강승석 서울여자대학교 2010 정보기술논문지 Vol.8 No.-
The advancement of neiwork technology helps expanding the use of multimedia transmissions, especially over the wireless networks. However, the signal attenuation and interference of the wireless networks results in the frequent packet losses, which produces a quality degradation of the media content. In order to tackle the quality degradation problem, many encoding schemes are introduced for transmitting multimedia data over the wireless networks. MPEG-4 is one of the multimedia encoding schemes to use I, p, and B frames in order to transmit video data. This paper analyzes the relationship between the quality of video and the patterns of the three frame types, and compares the quality (with PSNR) of the receiver-side video data transmitted over the wireless networks with applying diverse encoding patterns. In addition, this paper applies the two network transmission approaches, best effort and quality of service (QoS), to compare the video quality with diverse encoding patterns delivered over the wireless networks. According to the simulation results, the wireless network transmission approaches affect the quality of transmitted video, and especially the QoS approach outperforms the best effort by 11% in terms of the PSNR (Peak Signal to Noise Ratio).
신동천,김예신,문지영,박화성,김진용,박선구 한국환경독성학회 2002 환경독성보건학회지 Vol.17 No.4
At present, the health risks associated with the natural radionuclides of ground water have become a concern as potential social problems. However, there are no regulatory actions or control strategies for such risks. Therefore, we have investigated and discussed the risks and associated management strategies for radionuclides in other countries. US EPA has proposed MCL (300 pCi/L) and AMCL (4,000 pCi/L) for radon, and 30 ppb for uranium, 15 pCi/L for gross-alpha and 5 pCi/L for radium as final MCLs. Also, Canada, WHO and European countries have their inherent management levels. Finally, we suggested several criteria for setting guidelines in our countries including exposure related criteria such as geological distribution, occurrence, exposure probability distribution, exposure population and multimedia exposure assessment, acceptable risk, and cost-benefit analysis. The national-scale exposure and risk assessment, and economic analysis should be conducted for producing and aggregating the representative information on these criteria.
Moon-Jin Jeong,Jung-Hui Son,Soon-Jeong Jeong,Ye-Jin Kim,Hee-Jung Lim,Im-Hee Jung,Do-Seon Lim 한국치위생과학회 2023 치위생과학회지 Vol.23 No.4
Background: The purpose of this study is to investigate the tooth whitening effect of Listerine Healthy White and provide effective management of extrinsic discoloration by comparing the whitening effects of existing whitening products.Methods: The included study four groups: those using whitening gel, whitening toothpaste, and Listerine Healthy White and a control using artificial saliva. Each group received 40 bovine tooth specimens, which were stained with commonly consumed tooth-coloring-inducing foods; black tea, black coffee, and instant noodles for 72 hours. The specimens were treated with tooth whitening materials for 5 weeks, after which the lightness (L*) was measured weekly using a spectrophotometer. Results: There was a significant difference in lightness among the groups between the 1st and 5th week of treatment for all tooth-coloring-inducing foods (p<0.05). When comparing the changes in lightness values from before whitening to the 5th week of whitening for all tooth-coloring-inducing foods, the order of change was as follows: whitening gel, whitening toothpaste, Listerine Healthy White, and artificial saliva. Listerine Healthy White showed a significant whitening effect for all tooth- coloring-inducing foods (p<0.05). Particularly, changes in lightness values for specimens stained by black tea after 5 weeks of whitening were in the following order: whitening gel (21.72), whitening toothpaste (14.89), Listerine Healthy White (12.91), and artificial saliva (3.85). For specimens stained by black coffee, the changes in lightness values were in the following order: whitening gel (12.99), whitening toothpaste (9.66), Listerine Healthy White (7.91), and artificial saliva (3.12). Lastly, changes in lightness values for specimens stained by instant noodles were as follows: whitening gel (10.84), whitening toothpaste (9.85), Listerine Healthy White (7.71), and artificial saliva (2.61). Conclusion: Listerine Healthy White exhibits continuous whitening effects over time, and for consumers seeking convenient ways to achieve tooth whitening effects at home, consistent use of Listerine Healthy White is recommended.
Ye Jin Kim(Ye Jin Kim),Hye-seon Jeon(Hye-seon Jeon),Joo-hee Park(Joo-hee Park),Gyeong-Ah Moon(Gyeong-Ah Moon),Yixin Wang(Yixin Wang) 한국전문물리치료학회 2022 한국전문물리치료학회지 Vol.29 No.4
Background: Virtual reality (VR) programs based on motion capture camera are the most convenient and cost-effective approaches for remote rehabilitation. Assessment of physical function is critical for providing optimal VR rehabilitation training; however, direct muscle strength measurement using camera-based kinematic data is impracticable. Therefore, it is necessary to develop a method to indirectly estimate the muscle strength of users from the value obtained using a motion capture camera. Objects: The purpose of this study was to determine whether the pedaling speed converted using the VR engine from the captured foot position data in the VR environment can be used as an indirect way to evaluate knee muscle strength, and to investigate the validity and reliability of a camera-based VR program. Methods: Thirty healthy adults were included in this study. Each subject performed a 15-second maximum pedaling test in the VR and built-in speedometer modes. In the VR speedometer mode, a motion capture camera was used to detect the position of the ankle joints and automatically calculate the pedaling speed. An isokinetic dynamometer was used to assess the isometric and isokinetic peak torques of knee flexion and extension. Results: The pedaling speeds in VR and built-in speedometer modes revealed a significantly high positive correlation (r = 0.922). In addition, the intra-rater reliability of the pedaling speed in the VR speedometer mode was good (ICC [intraclass correlation coefficient] = 0.685). The results of the Pearson correlation analysis revealed a significant moderate positive correlation between the pedaling speed of the VR speedometer and the peak torque of knee isokinetic flexion (r = 0.639) and extension (r = 0.598). Conclusion: This study suggests the potential benefits of measuring the maximum pedaling speed using 3D depth camera in a VR environment as an indirect assessment of muscle strength. However, technological improvements must be followed to obtain more accurate estimation of muscle strength from the VR cycling test.
Yoon, Jin-Hwan,Kim, Kwang-Woo,Kim, Je-Han,Heo, Kyu-Young,Jin, Kyeong-Sik,Jin, Sang-Woo,Shin, Tae-Joo,Lee, Byeong-Du,Rho, Ye-Cheol,Ahn, Byung-Cheol,Ree, Moon-Hor The Polymer Society of Korea 2008 Macromolecular Research Vol.16 No.7
There are two beamlines (BLs), 4C1 and 4C2, at the Pohang Accelerator Laboratory that are dedicated to small angle X-ray scattering (SAXS). The 4C1 BL was constructed in early 2000 and is open to public users, including both domestic and foreign researchers. In 2003, construction of the second SAXS BL, 4C2, was complete and commissioning and user support were started. The 4C2 BL uses the same bending magnet as its light source as the 4C1 BL. The 4C1 BL uses a synthetic double multilayer monochromator, whereas the 4C2 BL uses a Si(111) double crystal monochromator for both small angle and wide angle X-ray scattering. In the 4C2 BL, the collimating mirror is positioned behind the monochromator in order to enhance the beam flux and energy resolution. A toroidal focusing mirror is positioned in front of the monochromator to increase the beam flux and eliminate higher harmonics. The 4C2 BL also contains a digital cooled charge coupled detector, which has a wide dynamic range and good sensitivity to weak scattering, thereby making it suitable for a range of SAXS and wide angle X-ray scattering experiments. The general performance of the 4C2 BL was initially tested using standard samples and further confirmed by the experience of users during three years of operation. In addition, several grazing incidence X-ray scattering measurements were carried out at the 4C2 BL.