• Geophysics and Geophysical Exploration
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• v.9 no.2
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• pp.148-154
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• 2006

The effect of small-scale near surface inhomogeneity on Rayleigh wave propagation and dispersion has been investigated in this study using two-dimensional FEM elastic modeling. Various inhomogeneity models with a variety of geometrical shape and embedment depth which exist in homogeneous half-space and two-layered media are considered. Results show that any near surface inhomogeneity greater than one wavelength in terms of minimum wavelength of Rayleigh wave shows dispersion characteristics. Such dispersion effect become stronger as the dimensions of the inhomogeneity increase. The effect of horizontal dimension is more dominant factor governing the dispersion characteristics than vertical dimension. However, the dispersion effect can not be identifiable in seismogram if the horizontal dimension is not wide enough. Nonetheless, even in this case, the existence of inhomogeneity can be inferred by the reflection or transmission event of Rayleigh wave. The results can be expected to provide insights on the behavior of Rayleigh wave which may be helpful for designating field work or new processing scheme to detect near surface inhomogeneity by surface wave method.

• International Commerce and Information Review
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• v.12 no.1
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• pp.179-202
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• 2010

Broadcasting services sector has been facing strong public pressure to shift gears from regulation to deregulation since mid-1990s, where a triggering role was played particularly by rapid development of IT technology and content digitization. Major agenda was how to reduce regulatory divides between more liberal telecommunication sector and less liberal broadcasting. After all, common solution package worldwide was for the latter to switch over from network-dependent(vertical) to network-independent(horizontal) regulation, and to facilitate more open and competitive transmission with content market kept protected. This is no other than decoupling content provision from broadcasting and promoting market access towards the latter. Policy experiences of US and UK show that there exists a complementary relationship between quantitative and qualitative restrictions in implementing such deregulation. While mitigating quantitative ownership regulations in broadcasting, they also sought to systematize, so-called, PIT(public interest test) as a qualitative safety device to cope with the risk of losing fundamental public values accordingly in broadcasting. Recent domestic progress in broadcasting legislation in 2009, however, seems to overlook the growing importance of PIT in the process of deregulation. Bearing this motivation in mind and taking account of the relevant WTO disciplines, this paper is to address policy issues and suggestions for PIT in Korea's broadcasting services sector.

• Transactions on Electrical and Electronic Materials
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• v.12 no.6
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• pp.241-244
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• 2011

An isolator transmits light in the forward direction and blocks light from passing in the reverse direction. It is regarded an essential optical component in medical, industrial, and research lasers for blocking reflection beams that cause optical damage and noise. It is also used as a communicative light intensifier to expand the lifespan of devices and enhance transmission quality. This study analyzed the characteristics of the core components in the construction of a polarization-independent isolator, namely, the walk-off polarizer and the Faraday rotator. Measurement of the extinction ratio of the resultant walk-off polarizer revealed that the ratio between the vertical and horizontal rays was 1,050:1 with a laser output of 0.032 W and 1,010:1 with a laser output of 2.68 W, thus presenting ratios similar to 1,000:1. In addition, the walk-off polarizer and Faraday rotator constructed in this study were used to compare output changes according to changes in power of input light and to check the penetration ratio. Results from the study presented variations in output value according to changes in power of input light. However, the average penetration ratio remained relatively consistent (~81.4%).

• Journal of Korean Association for Spatial Structures
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• v.17 no.4
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• pp.93-102
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• 2017

Wireless MEMS sensors have common features such as wireless communication, data measurement, embedded processing, battery-based self-power, and low cost, and increased measurement effectiveness. Wireless MEMS sensors enable efficient SHM without interfering with location because there is no requirement for triboelectric noise and cumbersome cables. However, there is little research on the communication distance with sensors and data. For instance, existing researches have limited communication distance experiments in civil engineering bridges. It is also necessary to investigate the characteristics of dynamic behavior and the communication distance of architectural structures with different wireless transmission/reception environments. Therefore, in a building structure with walls and slabs instead of open spaces, MEMS sensors and data loggers were used as distance experiments where communication disturbance between the vertical slab and the horizontal wall could actually be communicated.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.2
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• pp.265-277
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• 1998

In this paper, to investigate the possibility of fading reduction effect and high transmission rate in indoor multipath propagation environment, we measured and analyzed broadband signal conducting by frequency sweeping method in LOS(Line-of-Sight) environment. In measuring, we used vertically polarized, horizonatally polarized and circularly polarized and circularly polarized antenna to compare the fading reduction effect and the characteristic of bandwidth amplitude fluctuation between each broadband signals. As a result, it can be seen that the circularly polarized antenna can reduce the amplitude deviation of the broadband signal because it can remove the odd-times reflected wave in LOS environment. And also, It was found that the best effective diversity reception method is to use polarization branches, which install a circularly polarized antenna at the transmitting end and compose the vertical and horizontal antenna at the receiving end.

• ETRI Journal
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• v.44 no.1
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• pp.135-146
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• 2022

The importance of big data analytics has become apparent with the increasing volume of data on the Internet. The amount of data will increase even more with the widespread use of Internet of Things (IoT). One of the most important application areas of the IoT is healthcare. This study introduces new real-time data analytics architecture for an IoT-based smart healthcare system, which consists of a wireless sensor network and a radio-frequency identification technology in a vertical domain. The proposed platform also includes high-performance data analytics tools, such as Kafka, Spark, MongoDB, and NodeJS, in a horizontal domain. To investigate the performance of the system developed, a diagnosis of Wolff-Parkinson-White syndrome by logistic regression is discussed. The results show that the proposed IoT data analytics system can successfully process health data in real-time with an accuracy rate of 95% and it can handle large volumes of data. The developed system also communicates with a riverbed modeler using Transmission Control Protocol (TCP) to model any IoT-enabling technology. Therefore, the proposed architecture can be used as a time-saving experimental environment for any IoT-based system.

• Korean Journal of Veterinary Research
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• v.38 no.4
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• pp.803-810
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• 1998

Pullorum disease caused by Salmonella pullorum, has been considered as one of the most important diseases in both clinically and economically in poultry industry since it had been firstly reported in 1925 in Korea. This disease is still problem in the industry in this country even though several attempts have been made to eradicate the disease. As one of the trials to solve the problem, we investigated the pattern of the outbreak of the disease, isolated the causative agent, S pullorum and tested biochemical properties, antimicrobial susceptibility and plasmid profiles of the isolates. Outbreak of the disease based on the species was the highest in layer followed by in Korean native chick, and broiler. Daily mean mortality in vertical transmission (0.90%) was higher than that in horizontal (0.14%). There was no seasonal difference in the outbreak. Also, biochemical properties and antimicrobial susceptibility pattern of the isolates were same. However four different plasmid profiles of the isolates were observed. These results suggested that S pullorum isolates were different in the genotype while they were same in phenotypes.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.484-486
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• 1998

In this paper, a new method for controlling the pointing device on digital display using EOG(electrooculogram) which is generated from eye movement, was suggested. The manufactured system is consisting of pre-amplifier, A/D converter, serial transmission device and PC program. The EOG is amplified by pre-amplifier. And the amplified EOG is digitized and transmitted to personal computer via rs-232c by PIC16C74A. Finally, the software for controlling the pointer on digital display is developed on computer. As the result, the error between the real subject's viewing point and the point indicated by the developed pointing device on digital display was investigated into the average value, 0.72 degree for horizontal axis, 0.96 degree for vertical axis. The pointing device developed in this study is controlled by subject's eye movement, that is, the user's intention. Furthermore, the algorithm of this study is applicable for many field such as a new method remote control, a new wheelchair control and so forth.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.1005-1008
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• 2006

In this paper, we provide data of wireless environment in indoor for Bluetooth and wireless LAN systems. To accurately measure transmission characteristic for influence of the indoor wall, we used radiation measurement system with antennas. And various structure and material of the indoor wall are measured. Results of the measurement show that the attenuation of power is about $1\sim3dB$ for cement wall(25cm). In the case of cement wall with steel frame, the attenuation of power was increased using horizontal polarization but was not affect using vertical polarization.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.3
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• pp.771-783
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• 1996

A desing technique of 8 ports variable wave impedance generator (8P-VWIG) is described. The design technique employs not only a numerical algorithm to find the structure with arbitrary characteristic impedance, but also a numerical solution to analyze the uniform elementrognentic fields established inside the generator. The 8P-VWIG so obtained is shown to have good performance with the VSWR of less than 1.4 at any frequency of interest below which higher order mode begin to propagate. The measured first resonant frequency is 152.1 MHz. The 8P-VWIG is designed based on the concept of an expanded multi-transmission line(8 channel). It is especially useful for the electronmagnetic interference(EMI) and electronmagnetic susceptibility(EMS) testing since it maximizes usable test crosssectional area, and its is easy change the polarization, vertical or horizontal, of field.