• Journal of Biomedical Engineering Research
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• v.28 no.1
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• pp.153-161
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• 2007

Stroke is the second most significant disease leading to death in Korea. The conventional therapeutic approach is mainly based on physical training, however, it usually provides the limited degree of recovery of the normal brain function. The electric stimulation therapy is a novel and candidate approach with high potential for stroke recovery. The feasibility was validated by preliminary rat experiments in which the motor function was recovered up to 80% of the normal performance level. It is thought to improve the neural plasticity of the nerve tissues around the diseased area in the stroked brain. However, there are not so much research achievements in the electric stimulation for stroke recovery as for the Parkinson's disease or Epilepsy. This study aims at the developments of a wireless variable pulse generator using ZigBee communication for future implantation into human brain. ZigBee is widely used in wireless personal area network (WPAN) and home network applications due to its low power consumption and simplicity. The developed wireless pulse generator controlled by ZigBee can generate various electric stimulations without any distortion. The electric stimulation includes monophasic and biphasic pulse with the variation of shape parameters, which can affect the level of recovery. The developed system can be used for the telerehabilitation of stroke patient by remote control of brain stimulation via ZigBee and internet. Furthermore, the ZigBee connection used in this study provides the potential neural signal transmission method for the Brain-Machine Interface (BMI).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.3
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• pp.49-58
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• 2000

This paper deals with a systematic approach to neural network controller design for static VAR compensator (SVC) using a learning algorithm of error back propagation that accepts error and change of error as inputs, the momentum learning technique is used for reduction of learning time, to improve system stability. A SVC, one of the Flexible AC Transmission System(FACTS), constructed by a fixed capacitor(FC) and a thyristor controlled reactor(TCR), is designed and implemented to improve the damping of a synchronous generator, as well as controlling the system voltage.TO verify the robustness of the proposed method, we considered the dynamic response of generator rotor angle deviation, angular velocity deviation and generator terminal voltage by applying a power fluctuation and rotor angle fluctuation in initial point when heavy load and normal load. Thus, we prove the usefulness of proposed method to improve the stability of single machine-infinite bus with SVC system.

• Journal of Microbiology and Biotechnology
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• v.28 no.2
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• pp.338-346
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• 2018

Two molecular epidemiologic methods, IS6110 restriction fragment length polymorphism (IS6110-RFLP) and 24-locus mycobacterial interspersed repetitive unit-variable-number tandem repeat (MIRU-VNTR), are used worldwide in studies of Mycobacterium tuberculosis (MTB). Conversely, because of its poor resolution, pulsed-field gel electrophoresis (PFGE) is not widely used for MTB. In this study, we improved the 24-locus MIRU-VNTR and PFGE protocols and compared the effectiveness of these approaches for the molecular typing of MTB using 75 clinical isolates obtained from a cohort investigation of high-risk populations infected with MTB. The 24-locus MIRU-VNTR method demonstrated superior discriminatory ability, followed by PFGE and IS6110-RFLP. Next, we analyzed six isolates with clear epidemiologic connections; that is, isolates from patients who attended the same school. IS6110-RFLP and PFGE identified these samples as the same type. By contrast, according to MIRU-VNTR, two isolates differed from four other isolates at one locus each; one isolate was identified as Mtub29 and the other as QUB-26. In summary, the 24-locus MIRU-VNTR assay was the most useful molecular typing method among the three methods investigated due to its discriminatory power, short time required, and availability as an epidemiologic investigation tool. PFGE was the second-best method. Compared with the other loci assessed in the 24-locus MIRU-VNTR assay, the Mtub29 and QUB-26 loci appeared to exhibit greater variability during transmission.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.5
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• pp.260-270
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• 2007

Owing to the improved wireless communication technologies, it is possible to provide streaming service of multimedia with PDAs and mobile phones in addition to desktop PCs. Since mobile client devices have low computing power and low network bandwidth due to wireless network, the transcoding technology to adapt media for mobile client devices considering their characteristics is necessary. However, since mobile clients use wireless network and the wireless network have less stable bandwidth according to distance from AP and environments, it is hard to support stable QoS to mobile clients. In this paper, we propose a dynamic bit rate control method for transcoding in order to supprot stable QoS of streaming media service to mobile clients via wireless network. The proposed method is shown to serve seamless streaming media service with adaptive bit rate control according to state of wireless network in real time and to reduce transmission failure from experiment.

• The Journal of the Acoustical Society of Korea
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• v.19 no.6
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• pp.17-22
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• 2000

Statistical Energy Analysis(SEA) is an efficient tool to predict the broadband noise and vibration for the huge and complex structures such as aircraft and ships. To estimate the noise and vibration by using SEA accurately, the characteristics of SEA parameters associated with fluid loading have to be investigated. In this report, the fluid loaded coupling loss factors were calculated for an 'L' and 'T' type line connections and compared to the ones without fluid loading. Then, the vibration levels for steel box model with 'L' and 'T' type line connection were computed using the fluid loaded and no fluid loaded coupling loss factors, respectively. As a result, the calculated vibration levels of the model using the fluid loaded coupling loss factors were lower than those without fluid loading. As a conclusion, it is necessary to use the fluid loaded coupling loss factors for increasing the prediction accuracy on the noise and vibration of immersed structures.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.5 no.2
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• pp.1-6
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• 2009

Nuclear power plants (NPP) using Alloy 600 (Ni 75wt%, Cr 15wt%, Fe 10wt%) as a heat exchanger tube of the steam generator (SG) have experienced various corrosion problems by ageing such as pitting, intergranular attack (IGA) and stress corrosion cracking (SCC). In spite of much effort to reduce the material degradations, SCC is still one of important problems to overcome. Especially lead is known to be one of the most deleterious species in the secondary system that cause SCC of the alloy. Even Alloy 690 (Ni 60wt%, Cr 30wt%, Fe 10wt%) as an alternative of Alloy 600 because of outstanding superiority to SCC is also susceptible to leaded environment. An oxide on SG tubing materials such as Alloy 600 and Alloy 690 is formed and modified expanding to complex sludge throughout hideout return (HOR) of various impurities including Pb. Oxide formation and breakdown is requisite for SCC initiation and propagation. Therefore it is expected that an oxide property such as a passivity of an oxide formed on steam generator tubing materials is deeply related to PbSCC and an inhibitor to hinder oxide modification by lead efficiently can be found. In the present work, the SCC susceptibility obtained by using a slow strain rate test (SSRT) in aqueous solutions with and without lead was discussed in view of the oxide property. The oxides formed on Alloy 600 and Alloy 690 in aqueous solutions with and without lead were examined by using a transmission electron microscopy (TEM), an energy dispersive x-ray spectroscopy (EDXS), an x-ray photoelectron spectroscopy (XPS) and an electrochemical impedance spectroscopy (EIS).

• The Journal of the Korea Contents Association
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• v.16 no.11
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• pp.83-90
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• 2016

In this paper, we performed the analysis of transmission performance for Collision Free Period(CFP) supported by the low-power communication technology, IEEE 802.15.4 MAC (Media Access Control). For the analysis, periodic traffic, original service target of CFP, is considered and, according to the Quality of Service required, packet arrival pattern to MAC layer is categorized as batch and non-batch, and analysis on throughput, delay, and energy is performed for those patterns. On the basis of the obtained analysis, performance comparison with Collision Avoidance Period(CAP) is carried out for the health care applications that generate periodic traffic such as Pedometer, ECG, EMG. The evaluation confirms that CFP is more energy efficient for healthcare applications that generate periodic and time-critical traffic and moreover for the application with high bandwidth requirement CFP achieves up to 46% energy savings compared to CAP.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.586-588
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• 2007

The Moore's law states that the number of transistors on a chip doubles about every 18 months. And it was reported that the network speed has been doubled about every 9 months. This indicates that computing power and network is no longer the obstacles for the high performance applications requiring terabits networks. We believe that the application motivates the network and vice versa. This presentation will introduce the GLORIAD which is the first ring network connecting six countries around the world and provides scientists with advanced networking tools that improve a communications and data exchange. The GLORIAD trans-Pacific link started its service on August 1, 2005. Since then, there has been remarkable demonstrations were performed through major conferences like Supercomputing Conference. This paper will introduce the global collaborative works on demonstrations of VMT, high energy physics, SDSS and HD video transmission during SC'06 in Tampa, FL.

• Journal of Satellite, Information and Communications
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• v.7 no.3
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• pp.63-68
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• 2012

The VLC (visible light communication) system is communication technology using visible rays (RGB) that come out in LED device. It is energy curtailment effect and possible in ubiquitous network service applications. Also, VLC system has the above advantage about that the communication throughout the whole room is enabled by high power lighting and lighting equipment with white colored LED which are easy to install and have good outward appearance. However, the signal detection performance for the receiver near the network of transmitter boundary is severely degraded and the transmission efficiency decreased due to the influence of the interference signal from the adjacent networks. In this paper, we propose an interference mitigation method with optical relay and optical beamforming scheme in VLC systems, and evaluate the reception performance. For the system BER, the proposed system demonstrates the performance enhancement compared to the not using the optical relay and optical beamforming scheme, and SNR performance gain and higher channel capacity is achieved.

• Journal of the Korean Professional Engineers Association
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• v.15 no.4
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• pp.12-24
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• 1982

East Parts of Bangladesh have been benifited by low cost energy generated by domestic natural gas but West parts where energy generated by imported fuel. Bangladesh Government authority has very much concerned to transmit the low cost electricity to the West from the East for past several years. To solve such concerns, cross-country 230kv double circuits Power transmission line was proposed, however there was a big obstacle for the realization of this line to cross the Jamuna river which has 12 km long width with a deep muddy river bed. A consultant engineering firm named Merz-Mclellan anyway finalized this plan and a world-wide bid was announced on June 31, 1979. Due to the expected difficulty to construct the towers on sea like area, only three construction groups have participated. including a Korean joint venture organization of Samsung-Korean Developement corporation-Kolon Electric Machinery company. After 3 months bid evaluation, contract was awarded to Korean Consosium and KEM Co was in charge of designing steel towers with anchor bolts and base plates beside to electrical engineering field. Then KEM Co have faced and over-comed many unenpected technical difficulties such as forced eccentricity joint on base plate, distorsion issue of 60mm thick plates welding, threading anchor bolts, tad heat treatment of some anchor bolts, disagreement from Consultant Engineer on multiplying factor of leg stresses for 45$^{\circ}$ wind and on reducing O.L.F for wind loads on cables for such 1220km long spans. After spending two years long period for designing and engineering towers, base plates, and anchor bolts, first shipment of tower was finally realized on Nov. 8, 1981 and on the other hand KDD has proceeded concrete caisson work on schedule at Jamuna river site and expected to complete tower erection and stringing of cables within this year of 1982 which was original completion target.