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치과병원에서 사용되는 진단영상에 대한 JPEG 2000 압축률에 대한 평가
정기훈,한원정,유동수,최순철,김은경 대한구강악안면방사선학회 2005 Imaging Science in Dentistry Vol.35 No.3
Purpose : To find out the proper compression ratios without degrading image quality and affecting lesion detectability on diagnostic images used in dentistry compressed with JPEG 2000 algorithm. Materials and Methods : Sixty Digora periapical images, sixty panoramic computed radiographic (CR) images, sixty computed tomographic (CT) images, and sixty magnetic resonance (MR) images were compressed into JPEG 2000 with ratios of 10 levels from 5 : 1 to 50 : 1. To evaluate the lesion detectability, the images were graded with 5 levels (1: definitely absent; 2: probably absent; 3: equivocal; 4: probably present; 5: definitely present), and then receiver operating characteristic analysis was performed using the original image as a gold standard. Also to evaluate subjectively the image quality, the images were graded with 5 levels (1: definitely unacceptable; 2: probably unacceptable; 3: equivocal; 4: probably acceptable; 5: definitely acceptable), and then paired t-test was performed. Results : In Digora, CR panoramic and CT images, compressed images up to ratios of 15 : 1 showed nearly the same lesion detectability as original images, and in MR images, compressed images did up to ratios of 25 : 1. In Digora and CR panoramic images, compressed images up to ratios of 5 : 1 showed little difference between the original and reconstructed images in subjective assessment of image quality. In CT images, compressed images did up to ratios of 10 : 1 and in MR images up to ratios of 15 : 1. Conclusion : We considered compression ratios up to 5 : 1 in Digora and CR panoramic images, up to 10 : 1 in CT images, up to 15 : 1 in MR images as clinically applicable compression ratios.
정신분열증 입원환자에서 니코틴과 항정신병 약물의 상관관계 규명을 위한 니코틴 패취 적용 연구
반건호,유희정,윤도준,김종우,이기철 대한생물치료정신의학회 2000 생물치료정신의학 Vol.6 No.1
연구목적 : 정신분열증 환자는 흡연율이 높고, 그에 따라 항정신병 약물 투여량이 늘어나고, 약물에 의한부작용은 오히려 감소한다고 알려져 있다. 이러한 연구에서 방법론적 문제로는 실제 니코틴 용량을 측정하지 않았다는 점이다. 본 연구는 담배보다 니코틴의 주요 대사물인 코티닌을 측정하여 방법론적 오류를 최소화하고자 하였다. 방법 : 정신분열증으로 진단받은 입원환자 중 니코틴 패취군 8명, 대조군 8명을 설정하였다. 5일간 패취를 붙인 후 혈액에서 코티닌을 측정하였고, 정신증상의 정도를 알기 위하여 PANSS, 약물의 추체외로 부작용 측정을 위하여 ESRS를 실시하였다 일일 약물용량을 chlorpromazine 동량으로 환산하여 기록하였다. 결과 : 코티닌 수치와 정신증상, 추체외로부작용, 약물용량 사이에는 유의한 차이가 없었다. 결론 : 코티닌은 항정신병 약물의 작용에 영향을 미치지 못하였다. 단, 향후 연구에서는 니코틴 패취의 양을 증량하여 사용하므로써, 코티닌 용량에 따라 항정신병 약물효과에 영향을 미칠 수 있는지를 검증해야 할 것이다.
패킷 손실률에 기반한 효율적인 TCP Buffer Tuning 알고리즘
류기철 ( Gi Chul Yoo ),김동균 ( Dong Kyun Kim ) 한국정보처리학회 2005 정보처리학회논문지 C : 정보통신,정보보안 Vol.12 No.1
The existing TCP(transmission Control Protocol) is known to be unsuitable for a network with the characteristics of high BDP(Bandwidth-Delay Product) because of the fixed small or large buffer size at the TCP sender and receiver. Thus, some trial cases of adjusting the buffer sized automatically with respect to network condition have been proposed to improve the end-to-end TCP throughput. ATBT(Automatic TCP Buffer Tuning) attempts to assure the buffer size of TCP sender according to its current congestion window size but the ATBT assumes that the buffer size of TCP receiver is maximum value that operating system defines. In DRS(Dynamic Right Sizing), by estimating the TCP arrival data of two times the amount TCP data received previously, the TCP receiver simply reserves the buffer size for the nest arrival, accordingly. However, we do not need to reserve exactly two times of buffer size because of the possibility of TCP segment loss. We propose an efficient TCP buffer tuning technique(called TCP sender and the TCP receiver, respectively. For the purpose of testing the actual TCP performance, we implemented our TBT-PLR by modifying the linux kernel version 2.4.18 and evaluated the TCP performance by comparing TBT-PLR with the TCP schemes of the fixed buffer size. As a result, more balanced usage among TCP connections was obtained.
기초 : 기초회절증강 CT법을 이용한 악성신경교종 모델의 영상 연구
유재철 ( Je Chul Yoo ),이상평 ( Sang Pyung Lee ),김종기 ( Jong Gi Kim ),최기환 ( Gi Hwan Choi ),여형태 ( Hung Tae Yeo ) 대한뇌종양학회 2011 대한뇌종양학회지 Vol.10 No.2
Objective: Glioblastoma is the most common malignant brain tumor, accounting for 2-15% of intracranial tumors and one half of primary brain tumors, and it is one of the most malignant brain tumor due to its aggressive biological behavior. In order to detect the true glioblastoma tumor margin including infiltrated tumor components in the peritumoral edema zone, Diffraction Enhanced Imaging (DEI) technique was used. Methods and Materials: The orthotopic brain tumor models were made in Sprague Dawley rats using C6 tumor cell line. The whole brain was taken out as ex vivo model using cardiac perfusion with a fixing agent after confirming apparent evidence of tumor development with peritumoral edema in the brain of model by MR images. DEI-CT was acquired at 35 KeV monochromatic X-ray from Photon Factory Synchrotron facility. The reconstructed 2D/3D images were analyzed. Results: In glioma model, distinction among necrosis, typical ring-shaped viable tissue, edema and healthy tissue were clearly observed in the region of the frontal lobe in front of caudate nucleus. In addition, DEI-CT images of the normal cerebellum showed more apparent contrast between the white and gray matter than conventional absorption-based CT images. Conclusion: Higher-resolution imaging of the tumor cells could be obtained with DEI-CT than conventional method. It could be useful in the diagnosis, treatment planning, and determination of the effectiveness of treatment in malginant glioma.