• The Journal of the Acoustical Society of Korea
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• 제25권1E호
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• pp.32-35
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• 2006

The screech tone of underexpanded jet is numerically calculated without any specific modeling for the screech tone itself. Fourth-order optimized compact scheme and fourth-order Runge-Kutta method are used to solve the 2D axisymmetric Euler equation. Adaptive nonlinear artificial dissipation model and generalized characteristic boundary condition are also used. The screech tone, generated by a closed loop between instability waves and quasi-periodic shock cells at the near field, is reasonably analyzed with present numerical methods for the underexpanded jet having Mach number 1.13. First of all, the centerline mean pressure distribution is calculated and compared with experimental and other numerical results. The instantaneous density contour plot shows Mach waves due to mixing layer convecting supersonically, which propagate downstream. The pressure signal and its Fourier transform at upstream and downstream shows the directivity pattern of screech tone very clearly. Most of all, we can simulate the axisymmetric mode change of screech tone very precisely with present method. It can be concluded that the basic phenomenon of screech tone including the frequency can be calculated by using high-order and high-resolution schemes without any specific numerical modeling for screech tone feedback loop.

• 한국인쇄학회지
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• 제10권1호
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• pp.15-22
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• 1992

This paper proposed correction tone density eq. and dot area eq. for perdict tone reproduction when dot gain is constant, and these are based on Yule & Nielson`s tone density equation. The experimental results show that proposed coreaction tone density eq. and dot area eq. are useful and valid for perdict tone reproduction of a half-tone image.

• 한국전자파학회논문지
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• 제11권2호
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• pp.197-205
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• 2000

매우 높은 선형성을 요구하는 혼합기의 설계는 입력 전력의 back-off로 얻어지는 것이 일반적이다. 본 논문에 서는 혼합기의 비선형 특성을 보상하기 위해 혼합기의 입력 단에 역 비선형 특성을 갖는 전치왜곡 회로를 부착 하여 비선형 특성을 개선시키는 방볍을 제안하였다. 이 제안된 방법으로 주파수 성분이 1852.5 MHz와 1857.5 MHz인 2 2 -tone 엽력 RF 선호와 2015 MHz인 LO 선호를 혼합기에 입력하여 혼합기의 ell비를 IF 출력이 -20dBm/tone 일 때 22 dB. - 17 dBm/tone일 때 21.7 dB를 개선시켰다.

• ETRI Journal
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• 제38권6호
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• pp.1124-1134
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• 2016

The tone reservation method is one of the most effective pre-distortion methods for peak-to-average power ratio reduction in orthogonal frequency division multiplexing (OFDM) systems. Its direct application to OFDM systems with offset quadrature amplitude modulation (OQAM) is, however, not effective. In this paper, two novel TR-based methods are proposed, specifically designed for OFDM/OQAM systems by taking into consideration the overlapping nature of OQAM signals. These two methods have different approaches to the generation of the peak-cancelling signal. The first one (overlapped scaling tone reservation) generates the peak-cancelling signal using a least squares approximation algorithm with possible adjacent symbol overlap; the second one (multi-kernel tone reservation) generates the peak-cancelling signal by using multiple impulse-like time domain kernels. It is shown by simulation that, when used in OFDM/OQAM systems, the proposed methods can provide better performance than the direct application of the existing controlled clipping tone reservation method, and even outperform the multi-block tone reservation method.

• 한국인쇄학회지
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• 제15권1호
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• pp.41-55
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• 1997

We examine various digital halftoning technique and their application to printings. Three such technique are the error diffusion, cluster dither and disperse dither method. This paper describes a new tone correction halftone method to compensate dot gain. Input digital level are transformed by tone correction characteristics. The function of tone correction are solved from the printer response characteristic. The experimental results show that the proposed method is useful and valid.

• 한국멀티미디어학회논문지
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• 제15권1호
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• pp.9-17
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• 2012

최근 HDR (High Dynamic Range) 영상 렌더링을 위하여 다중 노출 영상 기반의 iCAM06 영상 재생 모델이 개발되었다. HDR 영상을 좁은 다이나믹 레인지를 갖는 디스플레이 장치에 출력하기 위해서는 톤 재현(tone reproduction) 또는 톤 맵핑(tone mapping) 과정을 거쳐야 하는데, HDR 렌더링 알고리즘을 대표하는 iCAM06은 출력 장치의 다이나믹 레인지에 영상을 재현하기 위해 S자 곡선 3 자극치 톤 압축(tone compression) 기법을 사용한다. 그러나 동일한 톤 맵핑 곡선의 사용으로 인한 톤 압축과정 중에서는 화이트 포인트 이동이 발생하는 단점이 있다. 그래서 본 논문에서는 3 자극치의 조명 영역의 입력에 대한 왜곡된 채널 이득을 보정하여 화이트 포인트 이동을 보상하는 방법을 제안하였다. 실험 결과는 제안한 방법이 iCAM06보다 정량 정성적으로 개선된 결과를 보임을 확인할 수 있다.

• 한국통신학회논문지
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• 제38A권11호
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• pp.919-927
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• 2013

본 논문에서는 HDR (high dynamic range) 영상 렌더링을 위한 히스토그램 변형 기법을 이용한 인지기반 톤 맵핑(tone mapping) 기법을 제안한다. HDR 톤 맵핑 알고리듬은 넓은 동적 영역을 갖는 영상을 LDR (low dynamic range) 영상 장치에 표현하기 위해 사용된다. 인간의 시각특성을 이용한 톤 맵핑 알고리듬은 상당히 효과적이지만 고정된 형태의 맵핑 함수를 사용하기 때문에 모든 영상에서 동일한 성능을 얻지 못한다. 제안하는 방법은 인지기반 톤 맵핑 함수와 히스토그램 변형기법을 적용하여 HDR 영상의 동적 영역을 압축한다. 인지기반 톤 맵핑 함수를 이용해서 원 영상의 히스토그램을 제한하고 보상과정을 통해서 적응적인 톤 맵핑 함수를 얻을 수 있다. 이는 화소값에 따라 서로 다른 제약조건들을 사용함으로써 contrast를 향상시킬 뿐만 아니라 원 영상의 디테일도 보존한다. 또한, 히스토그램 변형기법을 사용함으로써 과도한 히스토그램 평활화로 인한 왜곡을 개선할 수 있고, 더욱이 제어파라미터를 이용하여 영상의 contrast를 조정할 수 있다. 시뮬레이션 및 실험을 통해 주관적 및 객관적 성능을 비교하고 기존 방법에 비해 제안한 방법이 우수함을 입증한다.

• 대한물리의학회지
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• 제14권2호
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• pp.117-124
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• 2019

PURPOSE: This study was to investigate the effects of crocodile breathing exercise on pain, muscle tone, and muscle stiffness of non-specific low back pain patients. METHODS: The subjects were 37 patients with nonspecific low back pain. The patients were divided into two groups. The experimental group (EG) performed crocodile breathing exercise and the control group (CG) performed chest expansion breathing exercise. The intervention was conducted for 10 minutes every day for a total of eight weeks. Pain was measured using a VAS. Muscle tone and stiffness were measured using Myoton PRO. Two points were measured for muscle tone and muscle stiffness. They were measured at 30mm from the spinous process of the L1 and T10 vertebra. RESULTS: Pain, muscle tone and muscle stiffness at the T10 level showed a significant decrease in both EG and CG. Muscle tone and muscle stiffness in the L1 level area decreased significantly in the experimental group but the control group did not show any difference. The only statistically significant difference was observed in the L1 muscle tone between the pre and post intervention values. CONCLUSION: This study suggests that Crocodile breathing is a good method for managing pain, muscle tone, and muscle stiffness in non-specific low back pain patients.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.806-809
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• 1988

The frequency response characteristics of a bimorph type PZT piezoelectric transducer was investigated. In this study, function generator which generates short burst signal, plane reflection plate and oscilloscope were used to measure the characteristics of piezoceramic ultrasonic transducer. The resonant frequency of a bimorph type piezoceramic transducer which is acquired by using Tone-Burst Method had good agreement with the measured results from spectrum analyzer.

• 대한물리의학회지
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• 제16권1호
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• pp.83-92
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• 2021

PURPOSE: This study examined whether ankle joint stabilizing taping and muscle control taping influenced the ankle range of motion (ROM), muscle tone, and balance ability in chronic stroke patients. METHODS: Ten stroke patients were assigned randomly to experimental group 1 (joint stabilization taping n = 5) and experimental group 2 (Muscle control taping n = 5). After general physical therapy in both groups, ankle stabilization taping was applied to experimental group 1, and muscle control taping was applied to experimental group 2 three times a week for a total of six weeks (18 times). RESULTS: The muscle tone and stiffness of the gastrocnemius (GCM) showed significant differences between the experimental 1 and experimental 2 groups (p < .05). The Berg Balance Scale (BBS) and ROM also showed significant differences within the experimental 1 and experimental 2 groups (p < .05). The BBS and ROM also showed no significant differences between the experimental 1 and experimental 2 groups (p > .05). CONCLUSION: This study examined the muscle tone, balance, and ROM on the paraplegic side of stroke patients using kinesio taping, and the effect of the taping application method was confirmed from the preceding study. Therefore, it can decrease the paralysis side muscle tone and improve the ROM and balance ability.