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유사구간 클러스터링을 이용한 에너지 효율적인 데이터 전송방법
홍창기(Changgi Hong),김창화(Changhwa Kim),이승재(Seungjae Lee),김상경(Sangkyeung Kim) 한국정보과학회 2006 한국정보과학회 학술발표논문집 Vol.33 No.2C
센서 네트워크는 제한된 에너지를 가지는 작은 노드들로 구성이 된다. 이 센서 네트워크에서 가장 큰 에너지 손실을 가져오는 부분은 RF통신 부분이라 할 수 있다. 해양 센서 네트워크는 통신 매체로 음파를 사용하기 때문에 RF를 사용하는 센서 네트워크보다 통신하는데 더 많은 에너지를 소모한다. 센서 네트워크에서 통신 횟수를 줄여 에너지 효율을 높이는 방법으로 네트워크 내 집계 연산이나 필터링 등이다. 해양환경에서 데이터 값들이 유사한 층을 가지고 있다. 이 유사층에서 네트워크 내 집계 연산과 필터링의 의미를 살펴보겠다. 해양 센서 네트워크는 기존의 토플로지와 다른 구조를 가지고 있다. 새로 제안하는 구조에 어떠한 개념과 기능이 있는지를 살펴본 후 센서 노드들 임계값을 사용하여 센싱된 데이터 값이 유사한 구간을 클러스터로 묶고 묶여진 클러스터 내에서 어떻게 데이터를 전송할 방법을 제안한다.
홍창기(Changgi Hong),권기현(Gihwon Kwon) 한국정보기술학회 2022 Proceedings of KIIT Conference Vol.2022 No.12
강화학습 알고리즘은 특정 환경에 대해 에이전트를 훈련시켜 하나의 에피소드에서 누적되는 보상의 합을 최대화하는 최적의 정책을 찾는다. 본 논문에서는 일반적인 강화학습의 목적에 반하는, 누적되는 보상의 합을 최소화하는 이른바 반항적 정책을 Q-Learning, SARSA 두 알고리즘을 통해 실패 도달 성능 차이를 보인다. 실험은 Open AI Gym의 FrozenLake 환경에서 기존의 학습방식은 유지한 채, 목표 상태가 아닌 실패 상태를 추적하도록 평가 과정을 변형하였다. 학습 과정과 평가 과정에서 보상, 총 보상 변화 추이와 실패 상태 도달경로 길이를 비교하였고, 그 결과 SARSA 알고리즘이 성능상 우세함을 실험을 통해 확인한다. 또한 두 알고리즘이 산출한 Q-테이블 내 데이터를 분석하여 해당 결과를 해석한다. Reinforcement learning algorithms find optimal policies that train agents at specific environment to maximize the sum of the accumulated rewards in one episode. In this paper, the so-called rebellious policy that minimizes the sum of accumulated rewards, contrary to the general purpose of reinforcement learning, shows the difference in failure reachabillity’s performance through two algorithms: Q-Learning and SARSA. The experiment transformed the evaluation process to track the failure state, not the goal state, while maintaining the existing learning method in the FrozenLake environment of Open AI Gym. In the learning and evaluation process, reward and total reward per episode changes, and the length of the path to fail state were compared, and as a result, it is confirmed through experiments that the SARSA algorithm is superior in performance. In addition, the results are interpreted by analyzing the data in the Q-table calculated by the two algorithms.
성인 요로 감염 환자에서 99mTc - DMSA 삼중검출기 SPECT 영상의 유용성
박정식(Jung Sik Park),문대혁(Dae Hyuk Moon),김순배(Soon Bae Kim),이명혜(Myung Hae Lee),류진숙(Jin Sook Ryu),배원규(Won Gyu Bae),박수길(Su Kil Park),홍창기(Changgi D . Hong),조경식(Kyung Sik Cho) 대한핵의학회 1992 핵의학 분자영상 Vol.26 No.2
N/A Although early diagnosis of urinary tract infection is important, the radiologic evaluation is still controversial because of the low sensitivity and the lack of cost-effectiveness. This study was carried out to evaluate the clinical utility of high resolution triple head Tc-99m-DMSA SPECT imaging in urinary tract infection. We prospectively performed Tc-99m-DMSA planar and SPECT imaging, ultrasound of kidney (US), intravenous pyelography (IVP) and voiding cystourethrography (VCU) in all 60 adult patients with UTI [26 with first episode of acute pyelonephritis (APN), 22 with recurrent APN, and 12 persistent asymptomatic pyuria] and 25 normal persons. To assess reversibility of the renal cortical defect (RCD), Tc-99m-DMSA SPECT was repeated 1 to 8 months later in those patients with abnormal initial findings. Overall detection rate of Tc-99m-DMSA SPECT imaging was 83% (50/60), but planar, US, IVP and VCU showed abnormal findings in 68%, 28%, 32% and 13%, respectively. 25 out of 27 patients with nonnal or single RCD were all normal in other radioligic studies. Only two patients showed vesicoureteral reflux (VUR) on VCU (grade I) and mild hydronephrosis on IVP. But, high proportion of those with multiple RCD showed abnormal findings on US (17/33), IVP (18/33), and VCU (7/33): 67% in any of these 3 studies. Especially, 3 out 7 patients with VUR showed multiple RCD on Tc-99m- DMSA SPECT without any abnormality on IVP or US. 25 normal persons showed normal findings in all studies except one false positive finding on Tc-99m-DMSA SPECT imaging. Follow-up Tc-99m-DMSA SPECT was done in 28 patients (13 with single RCD, 15 with multiple RCD). All 13 patients with single RCD showed improvement. Those with multiple RCD presented improvement in 4, no change in 10, and aggravation in 1 on follow-up studies. With these results, we conclude: 1) Tc-99m-DMSA SPECT imaging is superior to planar imaging, US, IVP or VCU in detection of renal lesion in urinary tract infection. Tc-99m-DMSA SPECT is useful as a initial diagnostic tool in adult patients with urinary tract infection. 2) The multiple RCD on Tc-99m- DMSA SPECT represent the high probability of irreversible tissue change and need of extensive urological work-up.
중합효소 연쇄반응을 이용한 신장 조직에서의 거대세포 바이러스 핵산 구조의 검출
김유겸,유빈,송재훈,양원석,홍창기,박정식,김순배 대한감염학회 1993 감염 Vol.25 No.2
Cytomegalovrus (CMV) has been suspected to-be involved in pathogenesis of I&A nephropathy (IgA N). However, the presence of CMV in renal tissue of IgA N remains to the subject of controversy. To elucidate the presence of CMV in I&A N and other glomerulonephritis (GN),polymerase chain reaction (PCR) which specifically amplified a 159 bp fragment of immediate early gene of CMV and indirect immunofluorescence (IF) with monoclonal antibody and late gene of CMV were performed in paraffin-embedded tissues from 10 I&A N and 14 non-I&A GNs. CMV DNA was detected in 6 of 10 I&A N tissues and 10 of 14 other GNs by PCR-Southern blot hybridization, whereas IF failed to show the presence of CMV antigen in all renal tissues. The nonspecific presence of CMV DNA in various kinds of GNs including I&A N would suggest that CMV is not specifically associated with the pathogenesis of I&A N inendemic areas of CMV infection.