• Progress in Superconductivity
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• v.12 no.1
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• pp.57-61
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• 2010

We have developed a whole-head MEG system for basic brain research and clinical application. The sensor system consists of a 152 SQUID gradiometer array oriented and located in a suitable way to cover a whole head of the human. The system measures magnetic fields generated by neuronal currents in the brain to get information on the brain activities. For this purpose, the field sensitivity determined by the position, orientation and geometry of the pickup coil as well as amplification factor of the electronic circuits should be known precisely. However, the position and orientation of the pickup coil might be changed from the designed specifications during cool down of the dewar and it is necessary to characterize the field sensitivity. In this study, we made calibration systems to determine the actual position and orientation of the 152 pickup coils and compared the localization results of the N100m source in the auditory cortex.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.6
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• pp.1037-1044
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• 2014

A (t,n) threshold secret sharing scheme is the scheme which allows a trusted party to distribute the shares among n participants in such a way that any t of them can recover the original secret, but any group knowing only t-1 or fewer shares can not. Recently, Eslami et al. and Tadayon et al. proposed threshold multi-secret sharing schemes, respectively. They proposed that their schemes don't require secure channels. But, without secure channels in their schemes, everyone can get the shares and find the secrets. The proposed scheme does not use secure channels and only t participants can solve the equations of the system from the delivered share shadows and find the secrets.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06b
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• pp.336-337
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• 2011

The popularity of general purpose GPU（GPGPU）makes the CPU-GPGPU heterogeneous architecture normal. Therefore, tradeoff the usage of CPU and GPGPU becomes a way to improve performance of programs. In this work, we exploit the properties of the CPU-GPGPU heterogeneous architecture and use them to accelerate the content based chunking operation of deduplication. We built a prototype system which is able to coordinate CPU and GPGPU to chunk file and has been proven to have a better performance compared to using either CPU or GPGPU alone.

• The Journal of Korean Physical Therapy
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• v.22 no.2
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• pp.47-53
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• 2010

Purpose: This study investigated the effect of electroacupuncture stimulation on changes in blood biochemistry in spinal cord injury (SCI) rats whose cords were damaged by 6-hydroxydopamine (6-OHDA). Methods: Twenty-one Sprague-Dawley adult male rats were assigned to one of three groups: normal (n=7), control (n=7) and experimental group (n=7). The experimental group received electroacupuncture (Es-160, ITO, Japan) for 15 minutes in the form of low frequency (2 Hz) stimulation to the zusanli point. After treatment, we observed motor behavior recovery using the inclined plane test. We also measured serum and CNS concentrations and activities of enzymes including creatine kinase (CK), alkaline phosphatase (ALP), and Immunoglobulin G (IgG). Statistical analysis was done using one-way analysis of variance (ANOVA). Results: Concentrations of CK, ALP and IgG were lower in the experimental group than in the control group. Functional recovery was evaluated by the maximal angle of the inclined board on which rats could maintain their initial position. This allowed us to monitor progressive locomotor recovery. The maximal angles of the inclined plane test were higher in the experimental group than in the control group (p<0.05). Conclusion: The results of this study showed that electroacupuncture to the zusanli point has a therapeutic effect on functional recovery after SCI.

• Smart Structures and Systems
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• v.17 no.3
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• pp.471-489
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• 2016

Modal identification based on ambient vibration data has attracted extensive attention in the past few decades. Since the excitation for ambient vibration tests is mainly from the environmental effects such as wind and traffic loading and no artificial excitation is applied, the signal to noise (s/n) ratio of the data acquired plays an important role in mode identifiability. Under ambient vibration conditions, certain modes may not be identifiable due to a low s/n ratio. This paper presents a study on the mode identifiability of an instrumented cable-stayed bridge with the use of acceleration response data measured by a long-term structural health monitoring system. A recently developed fast Bayesian FFT method is utilized to perform output-only modal identification. In addition to identifying the most probable values (MPVs) of modal parameters, the associated posterior uncertainties can be obtained by this method. Likewise, the power spectral density of modal force can be identified, and thus it is possible to obtain the modal s/n ratio. This provides an efficient way to investigate the mode identifiability. Three groups of data are utilized in this study: the first one is 10 data sets including six collected under normal wind conditions and four collected during typhoons; the second one is three data sets with wind speeds of about 7.5 m/s; and the third one is some blind data. The first two groups of data are used to perform ambient modal identification and help to estimate a critical value of the s/n ratio above which the deficient mode is identifiable, while the third group of data is used to perform verification. A couple of fundamental modes are identified, including the ones in the vertical and transverse directions respectively and coupled in both directions. The uncertainty and s/n ratio of the deficient mode are investigated and discussed. A critical value of the modal s/n ratio is suggested to evaluate the mode identifiability of the deficient mode. The work presented in this paper could provide a base for the vibration-based condition assessment in future.

• Korean Journal of Agricultural Science
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• v.41 no.4
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• pp.385-390
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• 2014

To evaluate the impact of nitrogen fertigation on crop growth and $NO_3$-N concentration in the soil solution, field experiment for cucumber cultivation during spring and fall season were carried out in on-farm located in Byeongcheon-myeon, Chunan-si, Chungcheonnam-do. Supplying nitrogen of 120-150 mg/L by fertigation device into soil per week reached to maximum yields of cucumber fruits. However, cucumber growth did not show any significant difference between nitrogen levels. Nitrogen supply of 400 mg/L, highest N levels, did not affect cucumber growth. Difference between green values of cucumber leaves using RGB scores were closely related with cucumber yields, and therefore, this results suggests that green values of cucumber leaves could be used as a way of determining the application rates of nitrogen for cucumber cultivation period under fertigation system.

• The Journal of Korean Physical Therapy
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• v.18 no.5
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• pp.35-41
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• 2006

Purpose: This study was to determine the effects of exercise program for knee osteoarthritis on the physical fitness in elderly. The progressive exercise program included flexibility, strength, endurance, active range of motion and function activities. Methods: Nineteen subjects with osteoarthritis of the knees randomized to exercise group(n=10) or control group(n=9), but fourteen subjects completed the trial with an adherence of 70% to the intervention and 77% to the control. The physical fitness(back muscle strength, grip strength, flexibility, muscle power, agility, equilibrium) were evaluated with Helmas(Health Management System) made by Sewoo system at pre- and post- intervention. Results: The data were analysed with the two-way repeated ANOVA and paired t-test. The physical fitness had no difference among the groups and times except muscle power. Within experimental group, muscle power and agility were significantly increased between pre and post intervention, while the control group showed no change. Conclusion: Exercise program for knee osteoarthirits appear to be effective in muscle power and agility.

• Journal of KIISE:Computing Practices and Letters
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• v.5 no.6
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• pp.686-699
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• 1999

본 논문은 열린대학(및 열린병원) 구현을 위한 캠퍼스내(종합병원내)에서의 무선 LAN을 이용한 멀티미디어 원격교육(및 원격진료) 시스템 구현에 관한 연구이다. 본 시스템은 정보통신 기술과 멀티미디어 기술이 접목되어 개발된 시스템이다. 또한 본 시스템은 성균관대학교의 원격교육시스템을 확장한 개념이기도 하다. 또한 본 원격교육 시스템은 멀티미디어 미들웨어에 의해 실시간 상호참여형 환경과 IP multicasting을 제공하고 있다.본 시스템은 캠퍼스 내에서 AP(Access Point)을 사용한 무선 LAN과 캠퍼스와 캠퍼스 사이의 T1/E1 네트워크로 구성되어 있다. 이것은 로밍지역을 해결하기 위한 handoff와 중재를 위한 다중 브릿지을 사용함으로써 구현이 가능하다. Abstract In this paper, we propose a multimedia distance education system(or telemedicine) using a wireless LAN for an inner campus university/hospital, which is intended to implement an open university. This system is implemented by a high technology of multimedia and information communication software. Also, this system is an enhanced and expanded system of the conventional distance education of SKKU(Sung Kyun Kwan University). The structure of this system consists of a T1/E1 network(information super high way) between campuses and wireless LAN using the AP(Access Pointer) inner campus. It will be able to use a use multiple bridge for mediation and hand off to solve roaming areas. This distance education system supports a real-time collaboration environment and IP multicasting by multimedia middleware for collaboration.

• Analytical Science and Technology
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• v.23 no.6
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• pp.560-565
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• 2010

Perchlorate ion ($ClO_4^-$) has been widely used as oxidizing agent in military weapon system such as rocket and missile fuel propellant. So it has been challenging to remove the pollutant of perchlorate ion. nanoscale zero valence iron (nZVI) particles are widely employing reduction catalyst for decomposition of perchlorate ion. nZVI particles has increasingly been utilized in groundwater purification and waste water treatment. But it have strong tendency of aggregation, rapid sedimentation and limited mobility. In this study, we focused on reduction of perchlorate ion using nZVI particles immobilized in alginate polymer bead for stabilization. The stabilized nZVI particles displayed much greater surface area, and much faster reaction rates of reduction of perchlorate ion. In this study, an efficient way to immobilize nZVI particles in a support material, alginate bead, was developed by using $Ca^{2+}$ as the cross-linking cations. The efficiency and reusability of the immobilized Fe-alginate beads on the reduction of perchlorate was tested at various temperature conditions.

• Journal of Communications and Networks
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• v.15 no.4
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• pp.430-438
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• 2013

This paper addresses the issue of throughput-delay of one-to-many wireless multi-hop flows based on random linear network coding (RLNC). Existing research results have been focusing on the single-hop model which is not suitable for wireless multi-hop networks. In addition, the conditions of related system model are too idealistic. To address these limitations, we herein investigate the performance of a wireless multi-hop network, focusing on the one-to-many flows. Firstly, a system model with multi-hop delay was constructed; secondly, the transmission schemes of system model were gradually improved in terms of practical conditions such as limited queue length and asynchronous forwarding way; thirdly, the mean delay and the mean throughput were quantified in terms of coding window size K and number of destination nodes N for the wireless multi-hop transmission. Our findings show a clear relationship between the multi-hop transmission performance and the network coding parameters. This study results will contribute significantly to the evaluation and the optimization of network coding method.