• Journal of Broadcast Engineering
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• v.10 no.3
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• pp.340-347
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• 2005

This paper presents a polyphase down sampling based multiple description coding applied to H.264 video coding standard. For a given macroblock, a residual macroblock is calculated by motion estimation, and before applying DCT, quantization and entrophy coding of the H.264 coding process, the polyphase down sampling is applied to the residual macroblock to code in four separate descriptions. Experiments were performed for all the 9 test sequences of JVT SVC standardization in various packet loss patterns. Experimental results show that the proposed one gives 0.5 to 5 dB enhancement over an error-concealment based on the slice group map technolgoy.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.3
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• pp.328-335
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• 2002

When we want to transfer video streaming data through computer networks, we will have to be allocated a larger bandwidth compared to a general application. In general, it causes a serious network overload inevitably due to the limited bandwidth. In this paper, in order to resolve the problem, we haute taken a method for transmitting video streaming data using RTP and RTCP. With RR(Receiver Report) packet in RTCP we will test it to check whether the traffic in a network has occurred or not. If it happened, we haute tried to reduce the overall network traffic by dynamically changing the quantization factor of the Motion JPEG that is one of the encoding styles in JMF. When the ratio of the average of transmission for each session to the average of overall transmission is greater than 7%, we should adjust the amount of data to be transmitted for each session to reach the session mean values. The experimental results show that the proposed method taken here reduces the overload effectively and therefore improves the efficiency for transmitting video streaming data.

• Journal of the Korea Society of Computer and Information
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• v.18 no.11
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• pp.229-240
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• 2013

This study critically review the textbooks and the syllabus of computer network courses currently used at universities, and the specifications of the certifications concerned to provide the students with the competitive and optimized course contents. Considering the vitality of the practicum in the computer network courses, we also suggest a new learning-instruction case study that focuses on the practice by analyzing the computer network practice test simulators which are certified nationally and the internationally. The proposed learning-instruction case study for computer network courses includes the weekly core lessons and contents, study goals and key points, the practice theme, handy tools based on two track of lecture and practice. Therefore it is expected to be a quite resourceful and practical teaching plan for the teacher, and a highly achievement of learning outcomes through motivation which can facilitate CCNA certification enrolling in the field of network aspect for the learner.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.291-292
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• 2014

High-speed video transmission modes of master bridge IC are implemented, which supports MIPI (Mobile Industry Processor Interface) DSI (Display Serial Interface) standard. MIPI DSI master bridge IC sends RGB data and various commands to display module (slave) in order to test it. The master bridge IC consists of buffers storing video data of two lines, packet generation block, and D-PHY layer that distributes packets to data lanes and transmits them to slave. In addition, it supports four bpp (bit per pixel) formats and three transmission modes including Burst and Non-Burst (Sync Events, Sync Pulses types). The designed bridge IC is verified by RTL simulations showing that it functions correctly for various operating parameters.

• Journal of Physiology & Pathology in Korean Medicine
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• v.33 no.4
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• pp.239-248
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• 2019

There are no published data on Gyeongokgo (GOK) safety or efficacy despite being commonly use. The Gyeongokgo (GOK) is commonly used in traditional Korean medicine to promote a health qi and blood, but their objective data was not sufficient in clinical field. To investigate the safety and efficacy of GOK with hematologic and serologic testing and the change of the quality of life in healthy individuals. Randomized, subject-assessor-blind, placebo-controlled, single-center pilot study Participants and Interventions 29 healthy volunteer subjects were randomly placed into the GOK group (n = 20) or placebo control group (n = 9) and instructed to take one treatment packet (GOK or placebo) twice daily for 4 weeks. Subjects were assessed using the Fatigue Severity Scale (FSS) and Short Form 36 Health Survey (SF-36) and underwent hematologic and serologic tests and body composition analysis. The FSS total score (p = 0.093) and SF-36 general health index (p = 0.002) were improved following treatment in the GOK group. Post-treatment thyroid-stimulating hormone levels were increased in the GOK group compared with pre-treatment levels (p = 0.0042). C-reactive protein levels decreased (p = 0.0256) in the GOK group compared with that the placebo group. In time-series tests, GOK did not affect post-prandial serum triglycerides, glucose, insulin, or C-peptide levels. Notably, elevations in serum fasting triglycerides at 2- (p = 0.0333) and 4-hours (p = 0.0414) post-prandial were lower than those in the placebo group. GOK reduced fatigue levels and did not significantly affect laboratory test results performed to measure safety, serum glucose, and lipid profiles. Post-meal triglyceride levels were effectively reduced with treatment.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.1
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• pp.39-52
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• 2011

An application-layer attack can effectively achieve its objective with a small amount of traffic, and detection is difficult because the traffic type is very similar to that of legitimate users. We have discovered a unique characteristic that is produced by a difference in client intention: Both a legitimate user and DDoS attacker establish a session through a 3-way handshake over the TCP/IP layer. After a connection is established, they request at least one HTTP service by a Get request packet. The legitimate HTTP user waits for the server's response. However, an attacker tries to terminate the existing session right after the Get request. These different actions can be interpreted as a difference in client intention. In this paper, we propose a detection algorithm for application layer DDoS attacks based on this difference. The proposed algorithm was simulated using traffic dump files that were taken from normal user networks and Botnet-based attack tools. The test results showed that the algorithm can detect an HTTP-Get flooding attack with almost zero false alarms.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.2
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• pp.119-129
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• 2011

TCP-related Flooding attacks still dominate Distributed Denial of Service Attack. It is a great challenge to accurately detect the TCP flood attack in hish speed network. In this paper, we propose the NIC_Cookie logic implementation, which is a kind of security offload engine against TCP-related DDoS attacks, on network interface card. NIC_Cookie has robustness against DDoS attack itself and it is independent on server OS and external network configuration. It supports not IP-based response method but packet-level response, therefore it can handle attacks of NAT-based user group. We evaluate that the latency time of NIC_Cookie logics is $7{\times}10^{-6}$ seconds and we show 2Gbps wire-speed performance through a benchmark test.

• Journal of Digital Contents Society
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• v.19 no.3
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• pp.505-512
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• 2018

Internet demand has increased rapidly, and Internet Protocol Version 4, the main Internet protocol, can not cope with various types of network demand in the future. Therefore, it is urgent to spread IPv6-based stable network to solve the shortage of Internet address resources. Due to the proliferation of IoT and the increase in mobile devices, efficient and optimal IPv6 routing design is indispensable. In this paper, we have studied about characteristics of IPv6, address system of IPv6, structure analysis and efficient routing technology among IPv6 terminals. Furthermore, experimental results on routing packet analysis and convergence time are presented in network - based IPv6 routing implementation environment. In addition, we show the results of the experiment analysis by dividing the implementation of IPv6 routing, operation test, and fail over performance into three kinds of routing protocol methods. As a result, this study can be applied to the introduction of IPv6 system, test bed environment construction, and network design.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.9
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• pp.35-46
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• 2011

Future Internet should support more efficient mobility management, flexible traffic engineering and various emerging new services. So, lots of traffic engineering techniques have been suggested and developed, but it's impossible to apply them on the current running commercial Internet. To overcome this problem, OpenFlow protocol was proposed as a technique to control network equipments using network controller with various networking applications. It is a software defined network, so researchers can verify their own traffic engineering techniques by applying them on the controller. In addition, for high-speed packet processing in the OpenFlow network, programmable NetFPGA card with four 1G-interfaces and commercial Procurve OpenFlow switches can be used. In this paper, we implement an OpenFlow test-bed using hardware-accelerated NetFPGA cards and Procurve switches on the KREONET, and implement CSPF (Constraint-based Shortest Path First) algorithm, which is one of popular QoS routing algorithms, and apply it on the large-scale testbed to verify performance and efficiency of multimedia traffic engineering scheme in Future Internet.

• Korean Journal of Biological Psychiatry
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• v.21 no.3
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• pp.107-113
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• 2014

Objectives Restless legs syndrome (RLS) is a sleep disorder characterized by uncomfortable and unpleasant sensations in the legs and an urge to move the legs, usually at night. The aim of this study is to investigate the incidence of RLS in patients with late life depression and its influence on various clinical outcomes such as severity of depression, sleep quality, cognitive function, and quality of life and accordingly, to elucidate the clinical significance of RLS in patients with late life depression (LLD). Methods This study enlisted 170 depressive patients aged 65 years or older from an outpatient clinic. Structured diagnostic interviews were performed using the Korean version of the Mini-International Neuropsychiatric Interview. All patients completed the questionnaires, including the International RLS Severity Scale, the Korean version of Short-Form 36-Item Health Survey (SF-36), and the Pittsburgh Sleep Quality Index (PSQI). The severity of depression was evaluated by the Korean form of the Geriatric Depression Scale (KGDS) and the level of global cognition was assessed by the Mini-Mental State Examination in the Korean version of The Consortium to Establish a Registry for Alzheimer's Disease Assessment Packet (MMSE-KC). Results The incidence of RLS was 17.6% in LLD patients. RLS was more prevalent among the subjects with major depressive disorder (MDD) than those with minor depressive disorder or subsyndromal depressive disorder. The RLS group showed higher score in the KGDS than the Non-RLS group but the difference did not reach the statistical significance (p = 0.095, Student t-test). The mean PSQI score was significantly higher in the RLS group than in the Non-RLS group (p = 0.001, Student t-test). The MMSE-KC score was also lower in the RLS group than in Non-RLS group (p = 0.009, analysis of covariance). But, there was no difference in the score of SF-36 between the RLS group and the Non-RLS group. Conclusions RLS is common in LLD patients, especially in the patients with MDD and is associated with poor sleep quality and cognitive dysfunction, indicating that RLS is clinically significant in patients with LLD. Therefore, RLS should be considered as an important clinical issue in the management of LLD.