• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.150-152
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• 2004

Conventional CDDA (Compact Disc Digital Audio) system has limitations come from sampling frequency and quantization bit, 44.1kHz and 16 bit respectively. So, new medium is developed for high-resolution audio recording, like as DVD-audio etc. But CDDA is a widely used medium for high fidelity audio yet, because new medium has complexity and difficulty in manufacturing system. In this paper, we design a new encoding system for high-resolution audio signal. The system is backward compatible with conventional CDDA. By evaluation for encoding and decoding process, we describe practicability of our proposal system.

• 한국콘텐츠학회논문지
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• 제2권3호
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• pp.113-118
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• 2002

HFC(Hybrid Fiber Coax)기반으로 한 CATV망에서 양방향을 제공하기 위해서는 매체접근제어(Medium Access Control)프로토콜이 필요하다. 특히, 가입자에서 헤드앤드로 데이터를 전송하는 상향채널은 500가입자 이상이 공유하기 때문에 충돌이 발생하게 된다. 본 논문은 HFC-CATV망에 적합한 충돌해결알고리즘인 이진 스택 알고리즘의 안정성(stability)을 연구하기 위해 분석 모델을 제안하고 기존 모델과의 시스템 처리율(throughput)을 비교ㆍ분석하였다

• 대한전기학회논문지:시스템및제어부문D
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• 제54권5호
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• pp.327-329
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• 2005

Conventional CDDA(Compact Disc Digital Audio) system has limitation which means that bandwidth and resolution of the sign릴 are determined by the sampling frequency and quantization bit, 44.1kHz and 16 bit respectively. Though, new medium such as DVD-audio is developed for high-resolution audio recording, it has high complexity and difficulty in manufacturing process. So, CDDA is a widely used medium for high fidelity audio yet. In this paper, we design a new encoding system for high-resolution audio signal which has backward compatible with conventional CDDA. By evaluating for the encoding and decoding process. we verify the availability of our proposed system.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.23-26
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• 2006

Modernized GPS will have three frequencies modulated with three signals, which will be accessible to all users in the near future. This new frequency provides an opportunity to resolve the double differenced (DD) integer ambiguity very fast and with almost no baseline constraints. In order to study the performance of triple frequency system for Ambiguity Resolution (AR) over the medium baseline under different ionospheric levels, the Klobuchar Model was implemented and used in our triple simulation to generate the ionospheric delay. Furthermore, the White-Gaussian noise applying to distance-dependent parameters was added to the DD ionospheric delay. For medium baseline (defined as here 20 to 40kms), success rates of AR has been pretty improved. In this paper, the medium baseline AR strategies that take advantage of carrier phase measurement on the third frequency will be discussed.

• 천문학회보
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• 제46권2호
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• pp.64.2-64.2
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• 2021

Radio relics track cosmological shocks propagating through the intracluster medium. They are among the largest and most polarised sources in the radio sky reaching polarisation fractions up to ~60%. High-resolution observations in total intensity and in polarisation show complex structures on kiloparsec scales. Nevertheless, the relation between the observed features and the underlying morphology of the magnetic field is not clear. In this work we three dimensional MHD-Lagrangian simulations to study the polarised emission produced by a shock wave that propagates through a turbulent medium that resembles the intracluster medium. We find that the synchrotron emission produced in a shocked turbulent medium can reproduce some of the observed features in radio relics. Our work confirms that radio relics can also be formed in an environment with a tangled magnetic field. We also study the effect of intrinsic Faraday Rotation and the depolarisation of the source. Finally, we show how our results depend on the angular resolution of observations.

• 대한전자공학회논문지TC
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• 제39권5호
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• pp.225-231
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• 2002

본 논문에서는 무선 MAC 프로토콜상에서 실시간 응용의 QoS를 보장할 수 있는 지연 민감도를 고려한 차별적인 충돌해결 기법을 제안한다. 제안된 기법은 충돌해결을 위해 접근 요구 메시지들을 지연에 따라 서로 다르게 다루며, 이를 위해 본 논문에서는 지연 민감도가 높은 트래픽의 충돌해결을 보다 빠르게 해결하기 위해 CRP (Collision Resolution Period) 구간을 사용한다. 성능분석과 시뮬레이션 결과 제안된 프로토콜이 접근지연과 충돌의 정도를 줄임으로서 실시간 응용의 지연요구조건을 성공적으로 보장함을 보여준다

• Journal of Communications and Networks
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• 제13권1호
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• pp.43-49
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• 2011

In this paper, a new medium access control (MAC) protocol entitled three-phase multiple access with continual contention resolution (TPMA-CCR) is proposed for wireless multi-hop ad hoc networks. This work is motivated by the previously known three-phase multiple access (TPMA) scheme of Hou and Tsai [2] which is the suitable MAC protocol for clustering multi-hop ad hoc networks owing to its beneficial attributes such as easy collision detectible, anonymous acknowledgment (ACK), and simple signaling format for the broadcast-natured networks. The new TPMA-CCR is designed to let all contending nodes participate in contentions for a medium access more aggressively than the original TPMA and with continual resolving procedures as well. Through the systematical performance analysis of the suggested protocol, it is also shown that the maximum throughput of the new protocol is not only superior to the original TPMA, but also improves on the conventional slotted carrier sense multiple access (CSMA) under certain circumstances. Thus, in terms of performance, TPMA-CCR can provide an attractive alternative to other contention-based MAC protocols for multi-hop ad hoc networks.

• Current Optics and Photonics
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• 제1권1호
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• pp.34-44
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• 2017

Stereoscopic (S3D) displays present different images to the two eyes. Temporal multiplexing and spatial multiplexing are two common techniques for accomplishing this. We compared the effective resolution provided by these two techniques. In a psychophysical experiment, we measured resolution at various viewing distances on a display employing temporal multiplexing, and on another display employing spatial multiplexing. In another experiment, we simulated the two multiplexing techniques on one display and again measured resolution. The results show that temporal multiplexing provides greater effective resolution than spatial multiplexing at short and medium viewing distances, and that the two techniques provide similar resolution at long viewing distance. Importantly, we observed a significant difference in resolution at the viewing distance that is generally recommended for high-definition television.

• 한국재료학회지
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• 제32권8호
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• pp.345-353
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• 2022

In this study, using deep learning, super-resolution images of transmission electron microscope (TEM) images were generated for nanomaterial analysis. 1169 paired images with 256 × 256 pixels (high resolution: HR) from TEM measurements and 32 × 32 pixels (low resolution: LR) produced using the python module openCV were trained with deep learning models. The TEM images were related to DyVO₄ nanomaterials synthesized by hydrothermal methods. Mean-absolute-error (MAE), peak-signal-to-noise-ratio (PSNR), and structural similarity (SSIM) were used as metrics to evaluate the performance of the models. First, a super-resolution image (SR) was obtained using the traditional interpolation method used in computer vision. In the SR image at low magnification, the shape of the nanomaterial improved. However, the SR images at medium and high magnification failed to show the characteristics of the lattice of the nanomaterials. Second, to obtain a SR image, the deep learning model includes a residual network which reduces the loss of spatial information in the convolutional process of obtaining a feature map. In the process of optimizing the deep learning model, it was confirmed that the performance of the model improved as the number of data increased. In addition, by optimizing the deep learning model using the loss function, including MAE and SSIM at the same time, improved results of the nanomaterial lattice in SR images were achieved at medium and high magnifications. The final proposed deep learning model used four residual blocks to obtain the characteristic map of the low-resolution image, and the super-resolution image was completed using Upsampling2D and the residual block three times.

• 한국게임학회 논문지
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• 제11권2호
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• pp.105-114
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• 2011

MMORPG와 같은 게임에서 근접전투가 벌어지는 샷에서 프라이머리 액터들간의 오클루젼이 종종 발생한다. 본 논문은 미디엄 샷(medium shot) 기법으로 오클루젼을 해결하고 오버-숄더 샷(over-shoulder shot) 기법으로 대결구도를 강화하는 미디엄 오버-숄더(Medium and Oversholder, MOS) 기법을 제안한다. 미디엄 샷 기법은 4개의 기준점을 설정하고. 오버-숄더 샷 기법은 측면의 기준점을 가변적으로 위치시키며 오클루더는 두 개의 스피어로 대체한다. 레이와 스피어가 교차하는지 여부로 잠재적 오클루젼 상태가 판별되면 오클루더의 우측 또는 좌측으로 카메라를 이동시키고, 오클루젼이 해결되면 이동을 멈춘다. 실험결과 MOS 기법은 샷당 평균 $13.7{\mu}s$ 의 연산시간의 성능을 보였으며, 오클루젼은 평균 9.26% 비율로 뷰어의 시선 장애에 영향을 주진 않았다.