• Nuclear Medicine and Molecular Imaging
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• v.42 no.2
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• pp.153-163
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• 2008

Medical imaging modalities to image either anatomical structure or functional processes have developed along somewhat independent paths. Functional images with single photon emission computed tomography (SPECT) and positron emission tomography (PET) are playing an increasingly important role in the diagnosis and staging of malignant disease, image-guided therapy planning, and treatment monitoring. SPECT and PET complement the more conventional anatomic imaging modalities of computed tomography (CT) and magnetic resonance (MR) imaging. When the functional imaging modality was combined with the anatomic imaging modality, the multimodality can help both identify and localize functional abnormalities. Combining PET with a high-resolution anatomical imaging modality such as CT can resolve the localization issue as long as the images from the two modalities are accurately coregistered. Software-based registration techniques have difficulty accounting for differences in patient positioning and involuntary movement of internal organs, often necessitating labor-intensive nonlinear mapping that may not converge to a satisfactory result. These challenges have recently been addressed by the introduction of the combined PET/CT scanner and SPECT/CT scanner, a hardware-oriented approach to image fusion. Combined PET/CT and SPECT/CT devices are playing an increasingly important role in the diagnosis and staging of human disease. The paper will review the development of multi modality instrumentations for clinical use from conception to present-day technology and the application software.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.348-350
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• 2012

광파장다중화(WDM) 기반 광인터넷 환경에서 논리적인 다중 링 구조에 의한 통신망 복구 기법을 연구한다. 이 방법은 링 토폴로지의 특성을 이용해 빠르고 간단한 복구 동작을 제공하며, 지역적인 복구를 수행한다. 동시에 다중 링 구성을 통하여 대체 경로의 분산과 공유 정도를 높이고 단위 링크당 예약되어야 하는 예비 광파장의 수를 줄임으로써 전체 통신망 자원 이용의 효율성을 높일 수 있다. 본 논문에서는 위험공유 링크그룹(SRLG) 개념을 이용하여 링크 손실을 복구하는데 필요한 예비대역폭 비율을 토폴로지상의 Cut-Set을 이용해 계산하고 이를 실험을 통해 확인하였다.

• Proceedings of the Korea Contents Association Conference
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• 2014.11a
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• pp.461-462
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• 2014

기존 전문가 델파이 평가를 대체하는 특허기반 기술수준 평가모형들의 독립변수로 활용되는 특허활동도, 특허집중도, 특허시장력, 특허경쟁력 및 특허영향력의 다중공선성이 존재하여 이를 제거함으로써 보다 신뢰성이 높은 기술수준 평가모형을 실증하여 제안하고자 한다.

• KSCI Review
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• v.15 no.1
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• pp.77-81
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• 2007

센서 네트워크 라우팅에 대한 공격은 무선이라는 네트워크 환경 때문에 애드혹과 유사하게 이루어 지고 있다. 하지만 이를 대처하는 보안 매커니즘은 노드가 보다 제한된 자원을 가지므로 그대로 적용할 수 없어 새로운 연구가 필요하게 되었다. 본 논문에서는 웜홀 이라는 라우팅 공격에 대하여 다중 경로를 이용하여 공격을 회피하고 검출하는 방법에 대하여 제안한다. 다중 경로 환경에서 주경로와 대체 경로간 홉당 지연시간을 비교하여 웜홀 경로를 회피, 검출하고 검출 오차를 줄이기 위하여 블랙리스트를 방법을 사용한다. Ns-2 시뮬레이션 환경에서 제안한 방법을 이용한 웜홀 검출 메커니즘을 시뮬레이션하고 웜홀과 정상 노드의 검출율을 비교하여 성능을 측정하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.936-938
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• 2014

폐쇄회로 TV는 우리의 생활에 밀접하게 접근할 수 있는 수준에 다다르게 되었다. 따라서 중요한 작업은 영상에서 우리가 원하는 개체를 검출해내는 것이라 할 수 있다. 그 중에서 사람의 모습을 촬영해서 사람의 특징을 추출하는 연구가 많이 진행되었고 이를 이용해서 실제 CCTV 영상을 토대로 개체를 검출해내는 시스템에 대해 고찰하였다. 여러 가지 개체 검출 알고리즘 중에서 오픈소스로 제공이 되며, 다중 개체를 검출하기 위해서 Haar-like feature를 이용한 개체 추출 알고리즘을 이용하여 CCTV 다중대체 검출에 대해 실험을 진행하였다. 정지영상에서는 정면을 응시하는 얼굴영역 검출에서는 높은 성능을 보이며 다른 각도에서는 차이가 있지만 무난한 성능을 보이지만 실시간에서는 보정 작업이 필요하게 되었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.28-29
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• 2011

SSD(Solid State Drive)는 다중-채널/ 다중-웨이 방식의 NAND 플래시 메모리를 이용하는 저장장치로서 기존 HDD(Hard Disk Drive)를 대체할 차세대 보조기억장치로 주목받고 있다. 하지만 SSD 와 같은 동작을 하는 커널레벨의 시뮬레이터가 존재하지 않아, 사용자 영역에서부터 실제 NAND 플래시 칩까지의 동작 원리를 파악하기 어렵다. 이러한 문제를 해결하기 위해 본 논문에서는 SSD 시뮬레이터의 설계 및 구현내용을 기술한다. 구현한 SSD 시뮬레이터는 다중-채널/ 다중-웨이 방식의 SSD 전체적인 동작 원리를 리눅스 커널 수준에서 파악할 수 있다. 또한 FTL 개발을 위한 환경을 제공할 뿐만 아니라, 사용자가 다양한 SSD 구조를 설계하여 성능을 예측할 수 있도록 한다.

• The Korean Journal of Applied Statistics
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• v.23 no.2
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• pp.305-315
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• 2010

In this paper, a frequentistic approach to impute the values of R, G, B-components in random missing pixels of color image is provided. Under assumption that the given image is a realization of Gaussian Markov random field, its model is designed such that each neighbor pixel values for a given pixel follows (independently) the normal distribution with covariance matrix scaled by an evaluates of the similarity between two pixel values, so that the imputation is not to be affected by the neighbors with different color. An approximate EM-based algorithm maximizing the underlying likelihood is implemented to estimate the parameters and to impute the missing pixel values. Some experiments are presented to show its effectiveness through performance comparison with a popular interpolation method.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.39 no.6
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• pp.587-598
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• 2021

This study aims to develop a multi-camera based MMS (Mobile Mapping System) technology for building a HD (High Definition) map for autonomous driving and for quick update. To replace expensive lidar sensors and reduce long processing times, we intend to develop a low-cost and efficient MMS by applying multiple cameras and real-time data pre-processing. To this end, multi-camera storage technology development, multi-camera time synchronization technology development, and MMS prototype development were performed. We developed a storage module for real-time JPG compression of high-speed images acquired from multiple cameras, and developed an event signal and GNSS (Global Navigation Satellite System) time server-based synchronization method to record the exposure time multiple images taken in real time. And based on the requirements of each sector, MMS was designed and prototypes were produced. Finally, to verify the performance of the manufactured multi-camera-based MMS, data were acquired from an actual 1,000 km road and quantitative evaluation was performed. As a result of the evaluation, the time synchronization performance was less than 1/1000 second, and the position accuracy of the point cloud obtained through SFM (Structure from Motion) image processing was around 5 cm. Through the evaluation results, it was found that the multi-camera based MMS technology developed in this study showed the performance that satisfies the criteria for building a HD map.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5B
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• pp.539-548
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• 2011

We propose an efficient cooperative ARQ (Automatic Repeat reQuest) scheme for single-hop and multi-hop underwater acoustic communications, in which cooperative nodes are used to provide more reliable alternative paths for a specific source-to-destination connection. This alternative path has higher channel quality than that of the direct source-destination path. In addition, during a packet-relay through multiple hops, the typical acknowledgement (ACK) signal is replaced with overhearing data packet returned back from the next hop. The usage of overhearing as an ACK improves the system performance. In this paper, we evaluate the proposed scheme by comparing it with a conventional S&W ARQ in terms of throughput efficiency. Computer simulation results show that the proposed cooperative retransmission scheme can significantly improve the throughput by increasing the probability of successful retransmission.

• 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.24-30
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• 2007

In this paper, an energy detection-based low power, low complexity IR-UWB receiver in multipath impulse radio channel is presented. The proposed receiver has a simple 1-bit sampler for energy detection. Also, multipath signal received from multipath impulse radio channel is amplified and envelope of the signal is detected. Then, energy detection technique using integrator by summing multipath signals in certain period is adopted to minimize the BER loss by simple energy detection. In particular, in acquisition of a sample signal, SNR is additionally improved using a digital sampler. Symbol decision using several sampled signals is performed and thus the process of symbol synchronization is significantly simplified. Also, it is effectively designed to be compatible with influences of multipath and timing error. In addition, the proposed receiver complexity is reduced using pulse decision window. The performance of the proposed receiver is simulated based on IEEE 802.15.4a channel model and the algorithms are implemented on FPGA.