Management of Acute Stroke Patients Amid the Coronavirus Disease 2019 Pandemic: Scientific Statement of the Korean Stroke Society

김범준,Eu Suk Kim,Myoung Jin Shin,Hongbin Kim,Hee Young Lee,Keun-Sik Hong,Hong-Kyun Park,Jun Lee,Sung-Il Sohn,Yang-Ha Hwang,Sang-Bae Ko,Jong-Moo Park,Joung-Ho Rha,Sun U. Kwon,Jong S. Kim,Ji Hoe Heo,이병철,B 대한뇌졸중학회 2020 Journal of stroke Vol.22 No.2

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딥러닝을 이용한 데이터 소실로 인한 훼손된 문서의 복구

이희준(Heejun Lee),김영민(Youngmin Kim),배준우(Junwoo Bae),김선범(Seonbeom Kim),박희진(Heejin Park) 한국정보과학회 2018 한국정보과학회 학술발표논문집 Vol.2018 No.12

스텐실마스크를 이용한 다기능 마이크로/나노 패터닝 기술의 개발

김범준,Kim, Beom-Jun 재료연구소 2004 機械와 材料 Vol.16 No.1

3$\times$1패턴에 의한 3차원 브레이드의 기하학적 모델

김범준,이재곤,강태진,Kim, Beom-Jun,Lee, Jae-Gon,Gang, Tae-Jin 한국섬유공학회 1989 한국섬유공학회지 Vol.26 No.2

The micromechanics of 3-D braided preform by 3 $\times$1 pattern has been analyzed Based on the actual yarn paths and interlacing patterns, geometric relations between the structural parameters are analytically established. Analysis of the yarn paths during one repeat of the preform gives the number of different groups of the yarn with the same pattern in the structure which will in turn decide the yarn types used in the formation of hybrid composites where several different types of yarns are used. Observation of the preform surface cut at an angle of 18$^{\circ}$gives the interlacing pattern of the yarns and the critical condition of jamming in all directions has been determined with the critical orientation angle of 54$^{\circ}$which is smaller than that 1 $\times$1 pattern preform which is calculated as 60$^{\circ}$. This difference in critical orientation angle will result in difference in physical properties of the composites. The maximum yarn volume fraction was determind to be 63.4% which is smaller than 78.5% of 1 $\times$1 pattern preform. The validity of the analytical model was examined by testing the preforms braided with several different high performance fibers.

Effect of Molecular Aggregation on the Photo-Induced Anisotropy in Amorphous Polymethacrylate Bearing an Aminonitroazobenzene Moiety

김범준,박수영,최동훈,Kim, Beom Jun,Park, Su Yeong,Choe, Dong Hun Korean Chemical Society 2001 Bulletin of the Korean Chemical Society Vol.22 No.3

We investigated H-type molecular aggregation in a simply spin-coated amorphous homopolymer film of polymethacrylate containing push-pull azobenzene moieties. It was found that the aggregate formation was strongly influenced by thermal treatment an d that the aggregate created in the polymer film could be easily disrupted by irradiation of a linearly polarized light. In the first writing cycle of aggregated polymer film, photo-induced birefringence showed a steep increase to the highest value followed by a gradual decrease to the certain asymptotic value under longer irradiation of a linearly polarized light. This unique behavior could be attributed to the cooperative motion and the disruption of the aggregated molecules under continuous irradiation of light.

집광형 태양전지 모듈의 전기적 특성에 관한 연구

김범준,강이구,류세환,Kim, Beum-Jun,Kang, Ey-Goo,Lyu, Se-Hwan 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.6

We have analyzed electrical characteristics of spot light solar cell modules and have completed fabrication of spot light solar cell modules. Before we test modules, we have carried about UV test of hologram. As a result of test, we have obtained 165% efficiency of hologram film. the other hand, we obtained 75% efficiency of general films. After we have fabricated solar modules and carried about field test, spot light solar cell modules with hologram have been investigated 17.3 A of Isc and 155.4 W of power.

소프트웨어 기반 모바일 VoIP 서비스 품질 측정

김범준,Kim, Beom-Joon 한국전자통신학회 2011 한국전자통신학회 논문지 Vol.6 No.1

스마트폰을 이용한 모바일 인터넷 전화 서비스의 사용이 급속도로 확산되고 있다. 기존의 전화망이나 이동 전화망을 통한 전화 서비스와는 달리 인터넷 전화는 서비스 품질이 보장될 수 없다는 문제점이 있고 특히 무선 환경을 통한 모바일 인터넷 전화 서비스의 경우 이 문제점은 더 심각해 질 수 있다. 따라서 모바일 인터넷 전화의 성공적인 정착과 활성화를 위해서는 보다 체계화된 철저한 품질 관리가 요구된다. 기존의 계측기를 이용한 측정 기반의 사후 품질 관리를 개선하기 위해서 본 논문에서는 서비스 이용자 단말에 설치되어 각종 품질 지표를 측정할 수 있는 소프트웨어를 개발하였다. 개발된 소프트웨어를 이용하면 모바일 음성 서비스의 품질을 상시적인 그리고 서비스 이용자의 능동적인 품질 측정이 가능하다는 장점이 있다. The mobile internet telephony service rapidly grows according to the extending deployment of smartphones. Unlike telephony service over a conventional public switched telephone network (PSTN) or mobile network, internet telephony service cannot guarantee its service quality, which can be severer in a wireless environment. Therefore, a more strict and systematic quality management is required for successful settlement and popularization of mobile internet telephony service. Existing quality management scheme using a specific measurement equipment cannot measure all the time so that it performs late management. In order to overcome the problem, this paper develops a software that can be equipped on a user terminal and measures the service quality all the time. By using the developed software, all-time and user-activating service quality monitoring can be supported.

버퍼 크기 기반 자동재전송 프로토콜의 재전송 지속성 제어

김범준,Kim, Beom-Joon 한국전자통신학회 2011 한국전자통신학회 논문지 Vol.6 No.4

본 논문에서는 무선 링크의 신뢰성을 높이기 위한 자동재전송(Automatic Repeat reQuest; ARQ) 프로토콜의 재전송 시도 횟수 조정 방안을 제안한다. 기존의 자동재전송 프로토콜은 항상 고정된 재전송 지속성(retransmission persistence)을 사용하는데 이를 너무 작은 값을 설정하면 신뢰성을 보장하는데 한계가 있고 너무 큰 값으로 설정하면 지연과 지연 변이(jitter)가 크게 증가하는 문제점을 가지고 있다. 반면 제안된 방안은 버퍼 내의 프레임의 수를 근거로 재전송 지속성을 조정하여 프레임의 수가 많은 경우에는 재전송 지속성을 낮추어 자동재전송 프로토콜의 프레임 처리율을 높이고 적은 경우에는 재전송 지속성을 높여 무선 링크의 신뢰성을 높일 수 있다. 시뮬레이션 결과를 통해서 제안된 방안이 재전송으로 인한 지연과 지연 변이를 크게 감소시킬 수 있음을 보인다. This paper proposes a retransmission persistence control scheme for automatic retransmit request (ARQ) protocol to improve the reliability of a wireless link. Most existing ARQ protocols adopt a fixed retransmission persistence. If the ARQ protocol sets the retransmission persistence too low, there is a limitation in providing transmission reliability. On the other hand, if the ARQ protocol sets the retransmission persistence too high, it increases transmission delay and jitter. In order to figure out the problem, the proposed scheme considers the number of frames in the buffer in controlling the retransmission persistence; it improves the throughput of ARQ protocol by increasing the retransmission persistence when the number of frames is small and decreasing otherwise. Simulation results show that the proposed scheme decreases the transmission delay and jitter significantly comparing to the existing schemes.

Association of Paraoxonase 1 (PON1) polymorphisms with osteoporotic fracture risk in postmenopausal Korean women

김범준,이종영,Jung-Min Koh,김신윤,조윤신,Bon-Jo Kim,한복기,박의균,Seung Hun Lee,김하영,Ghi Su Kim 생화학분자생물학회 2011 Experimental and molecular medicine Vol.43 No.2

There is increasing evidence of a biochemical link between lipid oxidation and bone metabolism. Paraoxonase 1 (PON1) prevents the oxidation of low-density lipoprotein (LDL) and metabolizes biologically active phospholipids in oxidized LDLs. Here, we performed association analyses of genetic variation in PON1 to ascertain its contribution to osteoporotic fractures (OFs) and bone mineral density (BMD). We directly sequenced the PON1 gene in 24 Korean individuals and identified 26 sequence variants. A large population of Korean postmenopausal women (n =1,329) was then genotyped for eight selected PON1polymorphisms. BMD at the lumbar spine and femoral neck was measured using dual-energy X-ray absorptiometry. Lateral thoracolumbar (T4-L4) radiographs were obtained for vertebral fracture assessment,and the occurrence of non-vertebral fractures (i.e., wrist, hip, forearm, humerus, rib, and pelvis) was examined using self-reported data. Multivariate analyses showed that none of the polymorphisms was associated with BMD at either site. However, +5989A>G and +26080T>C polymorphisms were significantly associated with non-vertebral and vertebral fractures,respectively, after adjustment for covariates. Specifically,the minor allele of +5989A>G exerted a highly protective effect against non-vertebral fractures (OR =0.59, P = 0.036), whereas the minor allele of +26080T>C was associated with increased susceptibility to vertebral fractures (OR = 1.73, P = 0.020). When the risk for any OFs (i.e., vertebral or non-vertebral) was considered,the statistical significance of both polymorphisms persisted (P = 0.002-0.010). These results suggest that PON1 polymorphisms could be one of useful genetic markers for OF risk in postmenopausal women.

임의 패킷 손실에 대한 TCP의 손실 복구 과정 모델링 및 분석

김범준,김동연,이재용,Kim, Beom-Joon,Kim, Dong-Yeon,Lee, Jai-Yong 한국통신학회 2003 韓國通信學會論文誌 Vol.28 No.4

TCP Reno 는 하나의 윈도우 내에서 다수 개의 패킷 손실이 발생하는 경우 손실된 패킷들을 효율적으로 복구하는 것이 불가능한 문제점을 가지과 있다. 이 문제점을 개선하기 위해서 설계된 TCP New-Reno 는 부분 스인 패킷(partial acknowledgement)를 통해 fast recovery를 연장함으로써 다수 개의 패킷 손실이 발생하더라도 이들을 재전송에 의해 복구하는 것이 가능하다. 그러나 TCP New-Reno 역시 재전송 패킷들이 다시 손질되는 경우 불가피한 RTO(Retransmission Timeout)가 발생한다는 문제점을 가지고 있다. 이런 문제점을 개선하기 위해서 중복 승인 패킷 수를 근거로 재전송 패킷 손실을 감지할 수 있는 DAC(Duplicate Acknowledgement Counting) 알고리듬을 제안한다. TCP Reno. TCP New-Reno 그리고 DAC를 사용하는 경우에 대해 손실 복구 과정을 정확하게 모델링하고 손실된 패킷이 복구되기 위한 조건들을 유도한다. 임의 패킷 손실 확률에 대한 손실 복구 확률을 수학적으로 계산하고 이를 통해 DAC가 TCP New-Reno 의 손실 복구 기능을 향상시킬 수 있다는 것을 보인다. The fast retransmit and fast recovery algorithm of TCP Reno, when multiple packets in the same window are lost, cannot recover them without RTO (Retransmission Timeout). TCP New-Reno can recover multiple lost packets by extending fast recovery using partial acknowledgement. If the retransmitted packet is lost again during fast recovery, however, RTO cannot be avoided. In this paper, we propose an algorithm called "Duplicate Acknowledgement Counting(DAC)" to alleviate this problem. DAC can detect the retransmitted packet loss by counting duplicate ACKs. Conditions that a lost packet can be recovered by loss recovery of TCP Reno, TCP New-Reno and TCP New-Reno using DAC are derived by modeling loss recovery behavior of each TCP. We calculate the loss recovery probability for random packet loss probability numerically, and show that DAC can improve loss recovery behavior of TCP New-Reno.