• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1C
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• pp.102-108
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• 2006

In this paper, we propose an interference cancellation(IC) scheme using a partial Rake(PRAKE) combining in ultra-wideband(UWB) multipath fading channels. In this IC scheme, differently from the conventional transmitter model, which employs a guard interval between each frame, the guard interval is employed between each slot for estimating the multiple access interference(MAI). The UWB systems using the proposed IC scheme have little performance degradation without regard to the number of user, while the conventional UWB systems have a significant performance degradation according to the number of user. In order to reduce the receiver complexity, the PRAKE combining of post-canceled signal and the partial user IC scheme are also proposed.

• 한국HCI학회:학술대회논문집
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• 2007.02a
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• pp.500-506
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• 2007

얼굴에 대한 시각적 인지는 오랫동안 인간에게 중요한 문제로 인식되어 왔다. 수 세기 동안 이루어져 왔던 미용 화장과 성형, 치아 교정 등의 다양한 연구는 사람의 얼굴을 감성적 측면에서 어떻게 하면 아름답게 만들 수 있는 가에 초점을 두었다. 본 논문에서는 휴먼 입출력 인터페이스로서 햅틱 장치와 스테레오 디스플레이를 혼합한 다중 감각 인터랙션 기반의 감성적인 3차원 얼굴 메이크업 시뮬레이션 프레임워크를 개발한다. 본 연구는 3차원 스캐너 장비로부터 사용자의 얼굴 모델을 추출하고, 그 데이터를 이용하여 자연스럽고 직관적인 얼굴 메이크업 시뮬레이션을 수행하는 것을 목표로 하고 있다. 이를 위하여 본 연구에서는 surface elements 표현 기반의 3차원 얼굴 필터링 방법과 얼굴 메이크업을 지원하는 페인팅 방법을 개발한다. 우선 사용자의 얼굴 모델을 3차원 스캐너로 획득한 후, 전처리 얼굴 필터링을 수행하여 조명, 그리고 사용자 얼굴 피부 상태에 기인하는 에러 및 속성들을 보정하고 피부 톤을 사용자가 선호하는 색으로 변경한다. 최종적으로 사용자는 햅틱 및 스테레오 디스플레이 장치를 이용하여 두 개의 레이어로 구성된 페인팅 표면 모델에 메이크업을 수행한다. 본 연구에서 적용한 surface elements 표현 기반의 그래픽 렌더링은 일반적인 메쉬 기반 페인팅의 문제점인 텍스쳐 왜곡 현상을 완화하고, 3차원 스캐너 장치에 기인하는 표면 에러를 보정한다. 그리고 전처리 얼굴 필터링과 메이크업 페인팅 방법은 사용자 중심의 감성적인 3차원 얼굴을 재구성하도록 한다. 결과적으로 본 연구에서 개발한 이러한 기술들이 다중 감각 인터페이스 기반의 메이크업 시뮬레이터의 기본 프레임워크가 되어, 차후 메이크업이나 코디네이션 분야 등의 디지털 콘텐츠 산업에서 활용될 수 있음을 확인하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.4
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• pp.424-432
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• 2016

World's leading countries are developing next generation digital broadcasting system specifications to support UHDTV (ultra-high definition television) contents and other various services. In order to maximize the transmission capacity by using the bandwidth efficiently, most broadcasting systems adopt MIMO-OFDM. In distributed-MIMO systems, multiple transmit antennas are spatially separated and therefore result in multiple timing offsets. To overcome this problem, this paper proposes a technique using a null symbol to detect each individual signal from distributed transmit antennas. By inserting null symbols before preambles, the receiver can distinguish the signals between each transmit antennas and perform frame synchronization. When the reception time difference is shorter than 500 samples, the proposed method outperforms the conventional method.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.6 s.360
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• pp.48-56
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• 2007

OFDMA (Orthogonal Frequency Division Multiple Access) is widely used as multiple access techniques for next generation mobile communication systems. However, OFDMA has a disadvantage of high peak-to-average power ratio and SC-FDMA (Single-Carrier Frequency Division Multiple Access) was proposed for uplink systems to overcome the drawback. SC-FDMA also has several demerits including degraded performance with high-order modulations or with multiple antenna techniques, and less flexibility in resource allocation and pilot patterns. In order to achieve the best performance over a wide range of environments, each mobile station should select either of OFDMA and SC-FDMA according to the given condition and a pilot structure for SC-FDMA systems should be similar to that of OFDMA to maintain the same frame structure. While conventional SC-FDMA schemes require an entire SC-FDMA symbol or a separate short symbol for pilots, this paper proposes a method which supports the pilots included in SC-FDMA data parts and enables a SC-FDMA frame to hold the same structure as an OFDMA frame.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.1
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• pp.50-56
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• 2016

This paper is about the implementation of the OFDM-based border guard/reconnaissance communication terminal systems. We have implemented Real-time Dynamic DL/UL symbol rate control function using the DL-MAP message, and proposed error detection method caused by malfunctioning and timing optimization method. The proposed scheme detects the variable rate symbol decoding timing without increasing additional physical layer logic, and also provides a wide variety of DL/UL data transfer rate. Furthermore, the proposed scheme applies to the current border guard/reconnaissance equipment and confirms a operation performance through field tests and demonstration at home and abroad.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.4
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• pp.69-76
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• 2011

In this paper, we present the analytic model to quantify the system capacity with delay Quality of Service (QoS) constraints, and analyze the effect of user-multiplexing on the delay QoS performance in multiuser low-power wireless communication systems. For this purpose, we define the degree of multiplexing as the number of scheduled users to be served in a frame, and investigate the effect of degree of multiplexing (DoM) on the trade-off of throughput and delay QoS constraints. Through this analysis, we characterize the optimal DoM maximizing the energy efficiency in low-power communication environments. Finally, through the simulation results, we verify that our approach with its optimal DoM yields substantial capacity gain.

• Journal of KIISE
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• v.43 no.7
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• pp.736-743
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• 2016

Several studies have reported the impact of core affinity on the network I/O performance of multi-core systems. As the network bandwidth increases significantly, it becomes more important to determine the effective core affinity. Although a framework for dynamic core affinity that considers both network and disk I/O has been suggested, the multiple queues provided by high-speed I/O devices are not properly supported. In this paper, we extend the existing framework of dynamic core affinity to efficiently support the multiple queues of high-speed I/O devices, such as 40 Gigabit Ethernet and NVM Express. Our experimental results show that the extended framework can improve the HDFS file upload throughput by up to 32%, and can provide improved scalability in terms of the number of cores. In addition, we analyze the impact of the assignment policy of multiple I/O queues across a number of cores.

• The Journal of the Acoustical Society of Korea
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• v.39 no.1
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• pp.8-15
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• 2020

In this paper, we propose a frame synchronization algorithm for robust to the combined effects of large Doppler fluctuations and extended, time-varying multipath in the underwater acoustic communication. From the algorithm, we can recover a high timing error which is occurred from an acoustic propagation delay and uncertainty of oscillator between transmitter and receiver. In order to verify the performance of the synchronization algorithm, the lake trial results are used. The lake experiments are performed in a Gyeongcheonho located in Mungyeong-si, Gyeongsangbuk-do. We can see that the start position of frame is adjusted after the frame synchronization while the receiver moving.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.12
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• pp.2725-2730
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• 2012

In this paper, for improving the H.264/AVC hardware performance, we propose an inter predictor hardware design using a multi reference frame selector and an implicit weighted predictor. previous reference frame are reused for Low Memory Bandwidth. The size of the reference memory in the predictor was reduced by about 46% and the external memory access rate was reduced by about 24% compared with the one in the reference software JM16.0. We designed the proposed system with Verilog-HDL and synthesized inter predictor circuit using the Magnachip 0.18um CMOS standard cell library. The synthesis result shows that the gate count is about 2,061k and the design can run at 91MHz.

• Journal of Broadcast Engineering
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• v.21 no.3
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• pp.357-368
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• 2016

In DAB+, HE-AAC v2 codec is applied for the fixed rate transmission of audio stream. In case that xHE-AAC codec including USAC, a more efficiency is expected when the variable frame is used in a given same bandwidth compared to the fixed frame transmission. For this to be realized, audio streams need to be multiplexed in a sub-channel before transmission, then a method is required to identify the border of each audio frames. In this paper, the toggled sync byte and additional identification field being sequentially placed between AU borders are proposed in order to deal with the AU border identification. In addition, the Reed-Solomon based error correction code which is compliant to DAB+ is proposed.