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QoS NSIS Signaling Layer Protocol for Mobility Support with a Cross-Layer Approach
LEE, Sooyong,KIM, Myungchul,KANG, Sungwon,LEE, Ben,LEE, Kyunghee,SEOL, Soonuk The Institute of Electronics, Information and Comm 2011 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.eb94 No.10
<P>Providing seamless QoS guarantees for multimedia services is one of the most critical requirements in the mobile Internet. However, the effects of host mobility make it difficult to provide such services. The next steps in signaling (NSIS) was proposed by the IETF as a new signaling protocol, but it fails to address some mobility issues. This paper proposes a new QoS NSIS signaling layer protocol (QoS NSLP) using a cross-layer design that supports mobility. Our approach is based on the advance discovery of a crossover node (CRN) located at the crossing point between a current and a new signaling path. The CRN then proactively reserves network resources along the new path that will be used after handoff. This proactive reservation significantly reduces the session reestablishment delay and resolves the related mobility issues in NSIS. Only a few amendments to the current NSIS protocol are needed to realize our approach. The experimental results and simulation study demonstrate that our approach considerably enhances the current NSIS in terms of QoS performance factors and network resource usage.</P>
OEFMON: An open evaluation framework for multimedia over networks
Chunho Lee,Myungchul Kim,Hyun, S. J.,Sooyong Lee,Ben Lee,Kyounghee Lee IEEE 2011 IEEE communications magazine Vol.49 No.9
<P>As various types of networks are proliferating with greater capacity, the demand for multimedia services, such as videoconferencing, VoIP, and IPTV, over underlying networks has been increasing. This demand has increased the need for an evaluation framework to analyze the quality of such multimedia services and network performances for the related research areas. This article proposes OEFMON, an open framework for evaluating the quality of multimedia transmissions over networks. OEFMON integrates a multimedia module and a network simulator. The major advantages of OEFMON compared to other existing work are support for any number of multimedia codecs, adaptive coding based on network feedback, on-the-fly observation of multimedia transmission, and easy extension for other tools. A couple of case studies are performed to demonstrate the applicability and usefulness of our framework.</P>
이춘호(Chunho Lee),김명철(Myungchul Kim),윤요한(Yohaan Yoon),이일범(Ben Lee),현순주(Soon Joo Hyun),이경희(Kyunghee Lee),이수용(Sooyong Lee) 한국정보과학회 2011 한국정보과학회 학술발표논문집 Vol.38 No.1A
다양한 멀티미디어 서비스의 등장으로, 네트워크를 통한 멀티미디어의 원활한 전송에 대한 요구가 높아지고 있다. 이에 따라 이러한 기술 들을 검증하고 실험하기 위한 멀티미디어와 네트워크의 통합 프레임워크의 필요성은 높아졌다. 따라서, 이 논문에서는 멀티미디어의 네트워크 전송에 관한 연구를 위한 새로운 프레임워크를 제안한다. 본 프레임워크는 멀티미디어 프레임워크를 네트워크 시뮬레이터에 통합하여 멀티미디어 프레임워크에서 지원되는 다양한 멀티미디어 코덱을 시뮬레이터와 연동하여 사용하게 하고 네트워크 상태를 피드백으로 멀티미디어 프레임워크에 주어 수용하게 한다. 이 프레임워크는 기존 연구에 비해 다양한 코덱 지원, 네트워크 피드백기반 멀티미디어 코딩, 실시간 비디오 전송 관찰 등의 장점이 있다. 또한 제안된 프레임워크의개별 연구를 수행하여 그 효용성을 입증하였다.
Sooyong Lee,Hwajeong Kim,Youngkyoo Kim 한국태양광발전학회 2020 Current Photovoltaic Research Vol.8 No.4
Here we report the long-term stability of polymer:nonfullerene solar cells which were stored under dark and indoor light condition. The polymer:nonfullerene solar cells were fabricated using bulk heterojunction (BHJ) layers of poly[(2,6-(4,8-bis(5-(2-ethylhexyl) thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl –5′,7-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione))] (PBDB-T) and 3,9-bis(6-methyl-2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene (IT-M). To investigate their long-term stability, the PBDB-T:IT-M solar cells were stored in an argon-filled glove box. One set of the fabricated solar cells was completely covered with an aluminum foil to prevent any effect of light, whereas another set was exposed to indoor light. The solar cells were subjected to a regular performance measurement for 40 weeks. Results revealed that the PBDB-T:IT-M solar cells underwent a gradual decay in performance irrespective of the storage condition. However, the PBDB-T:IT-M solar cells stored under indoor light condition exhibited relatively lower power conversion efficiency (PCE) than those stored under the dark. The inferior stability of the solar cells under indoor light was explained by the noticeably changed optical absorption spectra and dark spot generation, indicative of degradations in the BHJ layers.
Influence of Physical Load on the Stability of Organic Solar Cells with Polymer
Sooyong Lee,Hwajeong Kim,Youngkyoo Kim 한국태양광발전학회 2016 Current Photovoltaic Research Vol.4 No.2
We report the effect of physical load on the stability of organic solar cells under physical loads. The active layers in organic solar cells were fabricated with bulk heterojunction films (BHJ) films of poly (3-hexylthiophene) and phenyl-C61-butyric methyl ester. The loading time was varied up to 60 s by keeping the physical load constant. Results showed that the open circuit voltage was not nfluenced by the physical load but other solar cell parameters were sensitive to the loading time. The fill factor was very slightly increased at 15 s, while short circuit current density was well kept for 30 s. The power conversion efficiency was reasonably maintained for 45 s but became significantly decreased by the continuous loading for 60 s.
Mobile collaborative computing on the fly
Lee, Hochul,Lee, Jaehun,Lee, Young Choon,Han, Hyuck,Kang, Sooyong Elsevier 2019 Pervasive and mobile computing Vol.58 No.-
<P><B>Abstract</B></P> <P>Today’s mobile devices are increasingly capable with a rich set of resources, such as octa-core processors, large amount of memory, GPS modules and even GPUs. Harnessing these devices for collaborative use is of great practical importance. At present, they are either collectively used or statically collaborated. In this paper, we present <I>Single Application Multiple Device</I> (SAMD) as a novel framework that provides collaboration functionalities at mobile platform level. A mobile app developed using SAMD is capable of mobile collaboration by sending portions of the app on-the-fly and running them without the prior installation. SAMD consists of three core functionalities: (1) Controller packaging, (2) lookahead transfer and (3) Controller replacement. We have implemented SAMD on Android as a proof-of-concept prototype. We evaluated SAMD using five applications on a number of real heterogeneous mobile devices. Our experimental results demonstrate SAMD can provide fine-grained sharing of latency-insensitive applications.</P>
Sooyong Lee,최유식 물리치료재활과학회 2023 Physical therapy rehabilitation science Vol.12 No.3
Objective: The purpose of this study was to investigate the effects of Pilates breathing exercises on functional disability and lumbar flexibility in patients with non-specific chronic low back pain. Design: A randomized controlled trial. Methods: 30 patients with non-specific low back pain were selected and classified into an experimental group (n=15) and a control group (n=15). Both groups were assessed for functional disability using the Oswestry Disability Index and flexibility of the lumbar spine using the modified-modified Schober test before and after the intervention. The intervention was applied twice a week for four weeks. The experimental group performed Pilates breathing exercises followed by spinal stabilization exercises, while the control group only performed spinal stabilization exercises. Results: Both groups showed significant improvements in functional disability and lumbar flexibility after the intervention. However, when comparing between the two groups, the experimental group showed a more significant effect than the control group. Conclusions: The combination of Pilates breathing exercises and spinal stabilization exercises can be considered an effective approach to improve low back pain and prevent chronic pain in patients with non-specific chronic low back pain.
Sooyong Lee,Jooyeok Seo,Jaehoon Jeong,Chulyeon Lee,Myeonghun Song,Hwajeong Kim,Youngkyoo Kim 한국태양광발전학회 2017 Current Photovoltaic Research Vol.5 No.3
Here we report the influence of thermal treatment on the performance of high efficiency polymer solar cells with the bulk heterojunction films of poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b"] dithiophene-alt-3-fluorothieno[3,4-b]thiophene-2-carboxylate] (PTB7-Th) and [6,6]-phenyl C71 butyric acid methyl ester (PC71BM). The crystalline nanostructure of PTB7-Th:PC71BM layers, which were annealed at three different temperatures, was investigated by employing synchrotron radiation grazing incidence X-ray diffraction (GIXD) technique. Results showed that the device performance was slightly reduced by thermal annealing at 50°C but became significantly poor by thermal annealing at 100°C. The poor device performance by thermal annealing was attributed to the collapse in the crystalline nanostructure of PTB7-Th in the PTB7-Th:PC71BM layers as evidenced by the GIXD measurements that exhibited huge reduction in the intensity of PTB7-Th (100) peak even at 50°C.