피어 투 피어 네트워크에서 스워밍 기법을 위한 보안 프로토콜

이관섭,이광식,이장호,한승철,Lee, Kwan-Seob,Lee, Kwan-Sik,Lee, Jang-Ho,Han, Seung-Chul 한국정보통신학회 2011 한국정보통신학회논문지 Vol.15 No.9

초고속 통신망의 일반화와 다양한 온라인 서비스의 출현으로 인터넷을 통한 대용량 콘텐츠 배포에 대한 수요가 증가하고 있다. 이에 따라 서버와 네트워크의 부담이 커지자 P2P 네트워크 기반으로의 전환 움직임이 활발해지고 있다. P2P 스워밍 기법은 서버의 역할을 최소화하고, 트래픽을 고르게 분산시켜 네트워크 과부하로 인한 각종 문제들을 해결할 수 있으며, 자원의 유지보수 비용 또한 절감시킬 수 있다. 하지만 P2P 스워밍 기법의 특성상 보안 서비스제공을 위해선 많은 메시지 교환이 필요하다. 본 논문에서는 P2P 스워밍기법에서 기밀성, 인증, 무결성, 접근 제어 등의 보안 서비스를 제공하는 효율적인 보안 프로토콜을 제안한다. 제안된 프로토콜은 안드로이드 스마트폰 플랫폼에서 구현하여 실험을 하였다. 제안된 프로토콜은 스워밍기법을 이용하는 상용시스템에 사용될 수 있을 것으로 기대된다. With fast deployment of high-speed networks and various online services, the demand for massive content distribution is also growing fast. An approach that is increasingly visible in communication research community and in industry domain is peer-to-peer (P2P) networks. The P2P swarming technique enables a content distribution system to achieve higher throughput, avoid server or network overload, and be more resilient to failure and traffic fluctuation. Moreover, as a P2P-based architecture pushed the computing and bandwidth cost toward the network edge, it allows scalability to support a large number of subscribers on a global scale, while imposing little demand for equipment on the content providers. However, the P2P swarming burdens message exchange overheads on the system. In this paper, we propose a new protocol which provides confidentiality, authentication, integrity, and access control to P2P swarming. We implemented a prototype of our protocol on Android smart phone platform. We believe our approach can be straightforwardly adapted to existing commercial P2P content distribution systems with modest modifications to current implementations.

폐회로 다중 안테나 기법을 적용한 적응형 협동 중계 전송 기술

이관섭(Lee Kwan-Seob),김영주(Kim Young-Ju) 한국방송·미디어공학회 2009 한국방송공학회 학술발표대회 논문집 Vol.2009 No.11

본 논문에서는 폐회로 다중 안테나 송수신 (closed-loop multiple-input multiple-output) 기법을 사용하는 적응형 협동 다중 홉 중계 시스템을 제안한다. 중계기와 기지국 사이의 이동성이 낮기 때문에, 폐회로 다중 안테나 송수신 기법은 개회로 다중 안테나 송수신 기법보다 높은 다이버시티 이득을 얻을 수 있다. 이 때, 한 개 이상의 중계 터미널들은 기지국으로 전송을 공유하고 프리코딩 가중치벡터를 피드백하기 위해 하나의 협동 그룹에 포함되어야 한다. 피드백 비트의 증가로 인한 전송량 감소를 최소화 하기 위해 코드북 기반의 최대비 전송 기법을 사용하여 비트백 비트수를 제한한다. 기지국은 협동 중계 그룹 중에서 채널 상태가 가장 좋은 중계기를 선택하고, 프리코딩을 위한 인덱스 값을 중계기에 피드백한다. 이러한 중계 시스템을 위해 피드백 형태와 선택 프로토콜 시나리오를 제안하고, 모의실험을 통해 중계기 선택에 따른 성능을 확인한다.

양방향 통신 시스템에서 폐회로 다중 안테나 기법을 적용한 적응형 협동중계 전송 기술

이관섭(Kwan-Seob Lee),김영주(Young-Ju Kim) 한국방송·미디어공학회 2010 방송공학회논문지 Vol.15 No.2

시뮬레이션을 이용한 대규모 스마트 TV 서비스 제공을 위한 사용자 그룹핑 알고리즘 성능 분석

전철,이관섭,주우석,정태경,한승철,Jeon, Cheol,Lee, Kwan-Seob,Jou, Wou-Seok,Jeong, Tai-Kyeong Ted.,Han, Seung-Chul 한국시뮬레이션학회 2011 한국시뮬레이션학회 논문지 Vol.20 No.1

스마트 TV 시스템은 차세대 핵심 네트워크 서비스 중의 하나로서 통신과 미디어 산업에 급격한 변화를 가져올 것이다. 하지만, 스마트 TV 시스템은 동시접속자가 증가하면 서비스 품질이 급격하게 저하되는 문제가 발생하고 있다. 콘텐츠를 수많은 사용자에게 동시에 전송하는 것은 서버와 네트워크에 큰 부담으로 작용하기 때문이다. 서버의 수용능력의 한계는 서버 클러스터를 구성함으로써 어느 정도 해결할 수 있지만 네트워크의 수용능력의 한계는 부하와 혼잡의 발생 위치를 파악하고 추가적인 자원을 설치하여 해결하는데 어려움이 있다. 이를 해결하기 위해 현재까지 많은 기법들이 제안되었지만 기존의 연구들의 성능분석은 대부분 왕복시간(round-trip time), 다운로드 시간, 패킷 손실 비율과 같은 사용자 중심의 성능척도에만 초점이 맞춰져 있고 스마트 TV 서비스 품질에 중요한 영향을 미치는 동시접속과 전체 네트워크의 부하와 혼잡을 무시하는 경향이 있다. 본 논문에서는 실제 인터넷 테스트베드인 PlanetLab을 이용하여 스마트 TV 서비스 폼질에 중요한 영향을 미치는 사용자 그룹핑 알고리즘을 네트워크의 혼잡도와 부하중심으로 성능분석을 한다. Smart TV System will lead to drastic change of communication and media industries as one of the emerging next generation network services. However, when the number of concurrent users increases rapidly, the issue of service quality degradation occurs because providing services to many users simultaneously stresses both the server and the network. The server limitation can be circumvented by deploying server clusters. but the network limitation is far less easy to cope with, due to the difficulty in determining the cause and location of congestion and in provisioning extra resources. In order to alleviate these problems, a number of schemes have been developed. Prior works mostly focus on reducing user-centric performance metrics of individual connection, such as the round-trip time(RTT), downloading time or packet loss rate, but tend to ignore the network loads caused by the concurrent connections or global network load balance. In this work, we make an in-depth investigation on the issue of user grouping for massive Smart TV services through simulations on actual Internet test-bed, PlanetLab.

다낭 형성 이상을 보이는 융합된 교차성 신전위 1례

서은민,심은정,이관섭,Seo, Eun-Min,Shim, Eun-Jung,Lee, Kwan-Seob 대한소아신장학회 2008 Childhood kidney diseases Vol.12 No.2

교차성 신전위는 두 개의 신장이 정중선의 같은 편에 나란히 위치하는 선천성 신장병이다. 대개 기형은 오른쪽에 있고 융합되어 있는 경우가 융합되지 않는 경우의 8배에 달한다. 교차성 신전위는 흔한 질환은 아니지만, 영아에서 복부에 낭성 종물이 만져지고 반대편에 신장이 없는 경우에는 고려해 보아야 한다. 다낭 형성 이상을 동반한 융합된 교차성 신전위는 대부분 초음파로 진단되므로 진단을 위해 더 이상의 검사가 필요하지 않은 경우가 많다. 그러나 방사선 동위원소를 이용한 신주사로 교차성 신전위의 기능여부를 파악해야 하고, 배설성 방광요로조영술로 방광요관 역류나 신우요관이행부의 협착이 있는지 확인해야 한다. 다낭 형성 이상을 동반한 융합된 교차성 신전위에 대한 연구는 거의 없는 실정으로 저자들은 발열, 복통을 주소로 내원한 3세 남아에서 초음파를 시행하여 다낭 형성 이상을 동반한 융합된 교차성 신전위 1례를 경험하였기에 보고하는 바이다. Crossed renal ectopia is a congenital malformation in which both kidneys lie on the same side of the spine, usually side by side longitudinally. More often on the right side. Fusion of the two renal units is eight times more common than nonfusion. Although crossed renal ectopia is uncommon, this unusual entity must be considered in an infant when cystic mass in the abdomen or pelvis paticularly if no kidney can be found on the opposite side. In many cases of crossed fused ectopia with multicystic dysplastic kidney(MCDK), the diagnosis can be strongly suspected from the sonogram, and no other studies may be necessary. However, both intravenous urography and isotope renography is useful to assess the function of the crossed kidney. Crossed renal ectopia and MCDKs are associated with a greater incidence of ureteropelvic junction obstruction and reflux. So, screening voiding cystourethrography should be performed. Very few studies of MCDK in the setting of crossed fused ectopia have been reported. We have experienced a 3-year-old boy with crossed fused renal ectopia with multicystic dysplasia.

C-arm을 이용한 EVAR(Endovascular Aneurysm Repair) 시술시 Lead Curtain 설치에 따른 Staff의 피폭선량 감소에 대한 연구

유인웅,정재연,이관섭,Yoo, In Woung,Chung, Jea Yeon,Lee, Kwan Seob 대한디지털의료영상학회 2012 대한디지털의료영상학회논문지 Vol.14 No.2

In EVAR procedure using long time C-arm, we studied exposure dose reduction and effeciency through measuring surgical staff's ESD by installing lead curtain operating table next to. The height 3 the spot (50cm, 100cm, 150cm) dose was measured on 2 locations for 600sec in the X-ray radiation considering the surgical staff's movement. To install the curtains, we compared before and after the dose. As a result, it can confirm that dose of the installation former of 50cm height and after is reduced about 75% and 91% in 2 locations. In 100cm height, the reduction of the dose was a bit confirmed. There as to dose value, measured on 150cm height the installation former and after was nearly no change. This research examined the exposure dose about the radiation of the surgical staff during EVAR procedure in which the operation time is the long time. It was implemented in the object that it reduces the radiation exposure. It could confirm the certain effect of the experimental result exposure dose reduction In EVAR procedure using long time C-arm, we studied exposure dose reduction and effeciency through measuring surgical staff's ESD by installing lead curtain operating table next to. The height 3 the spot (50cm, 100cm, 150cm) dose was measured on 2 locations for 600sec in the X-ray radiation considering the surgical staff's movement. To install the curtains, we compared before and after the dose. As a result, it can confirm that dose of the installation former of 50cm height and after is reduced about 75% and 91% in 2 locations. In 100cm height, the reduction of the dose was a bit confirmed. There as to dose value, measured on 150cm height the installation former and after was nearly no change. This research examined the exposure dose about the radiation of the surgical staff during EVAR procedure in which the operation time is the long time. It was implemented in the object that it reduces the radiation exposure. It could confirm the certain effect of the experimental result exposure dose reduction.

엎드린 자세에서 디지털 전척추 촬영술의 유용성 분석

오창섭(Chang-Seob Oh),김광수(Kwang-Soo Kim),손순룡(Soon-Lyong Son),이관섭(Kwan-Sup Lee) 대한영상의학기술학회 2013 대한영상의학기술학회 논문지 Vol.2013 No.-

목적: 기립 전척추 전후면 검사와 엎드린 자세에서 디지털 전척추 검사의 Cobb‘s angle 차이를 실질적으로 비교하여 엎드린 자세에서 디지털 전척추 검사의 유용성을 입증하고자 한다. 대상 및 방법: 2012년 8월부터 2013년 2월까지 척추 측만증으로 기립 자세와 엎드린 자세 에서의 디지털 전척추 검사를 시행한 환자 91명을 환자를 대상으로 하여 King 분류법으로 분류한 후, Cobb s method를 이용하여 각각의 만곡 각도를 측정하였다. 측정을 통해 얻어진 자료는 대응t검정으로 유의한 차이를 분석하였다. 결과: 척추 측만증의 Cobb s angle의 측정 후, 통계적 분석결과 엎드린 자세일 때는 기립 자세일 때에보다 흉부만곡은 평균 25.5%, 요부만곡은 평균 25.2%, 이중만곡에서는 흉부는 평균 22.8%, 요부는 21.7%로 모두 감소하였으며 통계적으로 매우 유의한 차이를 보였다 (p<.01). 흉추와 요추에서 기립 자세의 척추 측만각이 커질수록 오차의 각도가 커지는 상관 관계가 있었다. 결론: 척추 측만증의 수술자세와 동일한 엎드린 자세에서의 전척추 검사는 척추 측만증 환자의 수술 전 검사에 매우 유용하므로 임상적용 시 매우 유용하리라 판단된다. rials and Methods: After King classification, measurements of scoliosis angles with Cobb s method were carried out in a sample of ninety-one patients who examined whole spine digital radiography in standing position and prone position for scoliosis from August 2012 to February 2013. The significant differences were analyzed by t-test with the results. Results: In prone position, thoracic scoliosis was 25.5%, and lumbar scoliosis was 25.2% on the average compared to the standing position. For double scoliosis, thoracic scoliosis was 22.8%, and lumbar scoliosis was 21.7% on the average showing decreases. All the results indicated significant differences(p<.01). There was a correlation that the error angles increased as the scoliosis angles of thoracic and lumbar spine in standing position increased. Conclusion: Because an operative correction is performed in prone position, whole spine digital radiography in the same prone position would be useful as a pre-examination of the operation and applicable to the clinical practice.

전 척추 전.후 방향 검사 시 AEC Mode와 Fix Mode에서 PC-Based Monte Carlo Program을 이용한 장기선량 및 유효선량 평가

김정진,장성원,박장흠,이관섭,하동윤,Kim, Jeong Jin,Jang, Seong Won,Park, Jang Heum,Lee, Kwan Seob,Ha, Dong Yoon 대한디지털의료영상학회 2012 대한디지털의료영상학회논문지 Vol.14 No.2

There are AEC mode and fix mode to exposure when the whole spine antero-posterior radiography is done by using DR equipment. This study compared the utility of fix mode to AEC mode, by evaluating organ dose and effective dose and by examining the quality of radiographic image. GE DEFINIUM 8000 and ART-200X Rando Phantom manufactured by Flukebiometical were used for this study. The Rando phantom was set in front of wall detector of X-rays equipment. AEC mode was set at 80kVp and Fix mode was set at 80kVp, 25mAs, 32mAs, 40mAs, and 50mAs. Whole spine AP image were aquired by combining C, T-L and L-S spine images obtained through 3 exposures. When obtaining C, T-L and L-S spine images, were checked for Air kerma (mGy) value calculated by UNFORS Xi meter attached at the phantom surface of center of radiation field. The effective and organ doses were compared by PCXMC program (PC-Based Monte Carlo Program). The quality of obtained radiographic image was evaluated visually by 3 radiologists using resolution chart. When the effective doses was calculated based on tissue weighting factor of ICRP-103, 1.278mSv was measured by AEC mode, and Fix mode measured 0.405mSv at 25mAs, 0.518mSv at 32mAs, 0.649mSv at 40mAs, and 0.810mSv at 50mAS. In addition, the organ dose measured with esposure at 25mAs by Fix mode was almost equivalent to the organ dose by AEC mode, at the esophagus, thyroid, oral mucosa, salivaly glands located at the cervical spine part, while the organ dose by Fix mode was in general lower than the organ dose by AEC mode at the other organs. When Fix mode at 32mAs, 40mAs, and 50mAs was compared to AEC mode for organ dose in 26 organs, AEC mode had higher measurement in 21 organs but not for than brain, trachea, thyroid, oral mucosa, and salivaly glands which are located at the cervical spine part. The image quality evaluated by resolution test chart was much higher with AEC mode than the quality with Fix mode at all exposure conditions. However, while the image quality of cervical spine exposured at 50mAs by Fix mode was lower than the quality of AEC mode, thoraco-lumbar spine and lumbo-sacral spine were calculated and the quality was similar to AEC mode. Scoliosis occurs mainly at thoraco-lumbar and lumbo-sacral spine, not at cervical spine. Compared to AEC mode, Using the appropriate protocol (80kVp, 50mAs) of fix mode for whole spine AP radiography was thought to be useful because the image quality of the thoraco-lumar and lumbo-sacral spine was similar on AEC mode, Also organ and effective doses can be decreased with Fix mode. Therefore, It is considered that fix mode can be used properly with AEC mode for whole spine AP radiography when considering patient's body posture.

가임기 여성의 유방촬영에서 Dose mode 적용의 유용성 분석

이소라,손순룡,정재연,이관섭,Lee, So-Ra,Son, Soon-Lyong,Chung, Jae-Yoen,Lee, Kwan-Seob 대한디지털의료영상학회 2013 대한디지털의료영상학회논문지 Vol.15 No.2

Purpose : Automatic exposure system(AOP mode) in DR Mammography of the STD and DOSE apply to women of childbearing age, the average glandular dose(AGD) and image quality by comparing was to demonstrate the usefulness of DOSE. Materials and Methods : Of the under 40 age 108 patients who visit to our hospital and examined STD and DOSE mammography from January 2008 to July 2013. AGD was obtained by DICOM header information provided by GE Senographe DS. STD and DOSE images were evaluated with obtained patients, Image J program was compared by calculating the SNR. Results : The average AGD of DOSE mode was 0.99mGy, and which decreased by 19% comparing to that of STD mode which was 1.18mGy. The two the average AGDs indicated statistically significant difference(p< .01). The average SNR of STD was 40.26, DOSE displayed, and to 39.68 in, there was no statistical significance. Results : The average AGD using DOSE mode which is one of DR mammography AOP modes decreased by comparing to that of STD mode showing no difference in image quality. The use of DOSE is considered to be useful.

Glass dosimeter와 PCXMC Program을 이용한 소아피폭선량 측정 및 분석

김영은,이정화,홍선숙,이관섭,Kim, Young-Eun,Lee, Jeong-Hwa,Hong, Sun-Suk,Lee, Kwan-Seob 대한디지털의료영상학회 2012 대한디지털의료영상학회논문지 Vol.14 No.2

Exposed dose of young child should be managed necessarily. Young child is more sensitive than adult of a Radioactivity, especially, and lives longer than adult. Must reduce exposed dose which follows The ALARA(As Low As Reasonably Achievable)rule is recommended by ICRP(International Commission on Radiological Protection)within diagnostic useful range. Therefore, We have to prepare Pediatric DRL(Diagnostic Reference Level) in Korea as soon as possible. Consequently, in this study, wish to estimate organ dose and effective dose using PCXMC Program(a PC-Based Monte Carlo Program), and measure ESD(Entrance surface dose)and organ dose using Glass dosimeter, and then compare with DRL which follows EC(European Commission)and NRPB(National Radiological Protection Board). Using glass dosimeter and PCXMC programs conforming to the International Committee for Radioactivity Prevention(ICRP)-103 tissue weighting factor based on the item before the organs contained in the Chest, Skull, Pelvis, Abdomen in the organ doses and effective dose and dose measurements were evaluated convenience. In a straightforward way to RANDO phantom inserted glass dosimeter(GD352M)by using the hospital pediatric protocol, and in a indirect way was PCXMC the program through a virtual simulation of organ doses and effective dose were calculated. The ESD in Chest PA is 0.076mGy which is slightly higher than the DRL of NRPB(UK) is 0.07mGy, and is lower than the DRL of EC(Europe) which is 0.1mGy. The ESD in Chest Lateral is 0.130mGy which is lower than the DRL of EC(Europe) is 0.2mGy. The ESD in Skull PA is 0.423mGy which is 40 percent lower than the DRL of NRPB(UK) is 1.1mGy and is 28 percent lower than the DRL of EC(Europe) is 1.5mGy. The ESD in Skull Lateral is 0.478mGy which is half than the DRL of NRPB(UK) is 0.8mGy, is 40 percent lower than the DRL of EC(Europe) is 1mGy. The ESD in Pelvis AP is 0.293mGy which is half than the DRL of NRPB(UK) is 0.60mGy, is 30 percent lower than the DRL of EC(Europe)is 0.9mGy. Finally, the ESD in Abdomen AP is 0.223mGy which is half than the DRL of NRPB(UK) is 0.5mGy, and is 20 percent lower than the DRL of EC is 1.0mGy. The six kind of diagnostic radiological examination is generally lower than the DRL of NRPB(UK)and EC(Europe) except for Chest PA. Shouldn't overlook the age, body, other factors. Radiological technician must realize organ dose, effective dose, ESD when examining young child in hospital. That's why young child is more sensitive than adult of a Radioactivity.