• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3A
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• pp.321-327
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• 2006

In this paper, when a H-polarized plane wave is incident on the grating consisting of uniform resistive strips, electromagnetic scattering is analyzed using the moment of methods (MoM). The current density of each resistive strip on a grounded dielectric plane is fixed by zero at both edges. To satisfy the condition at both ends of each resistive strip, the induced surface current density is expanded in a series of cosine and sine functions. The scattered electromagnetic fields are expanded in a series of floquet mode functions. The boundary conditions are applied to obtain the unknown current coefficients. According to the variation of the involving parameters such as strip width and spacing and angle of the incident field, numerical simulations are performed by applying the Fourier-Galerkin moment method. The numerical results of the normalized reflected power for resistive strips case for zero and several resistivities are obtained.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.6 s.121
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• pp.656-663
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• 2007

In this paper, when a E-polarized plane wave is incident on the grating consisting of tapered resistive strips, electromagnetic scattering is analyzed using the method of moments(MoM). The induced current density of each resistive strip in a grounded double dielectric layer is expected to blow up at both edges. To satisfy this, the induced surface current density is expanded in a series of Chebyshev polynomials of the second kind. The scattered electromagnetic fields are expanded in a series of Floquet mode functions. The boundary conditions are applied to obtain the unknown current coefficients. According to the variation of the involving parameters such as strip width and spacing and angle of the incident field, numerical simulations are performed by applying the Fourier-Galerkin moment method. The numerical results of the normalized reflected power for resistive strips case for several resistivities are obtained.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.165-170
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• 2006

In the Civil Aviation field, the international trend (through ICAO, EUROCONTROL) is to adopt one positioning system that allows to follow more flight phases. This will allow to release themselves by ground installations and optimize the traffic flows following the aRea Navigation (RNAV) concept. In order to realize this goal the European Scientific Community are focusing on Augmentation Systems based on Satellite infrastructure (SBAS - Satellite Based Augmentation System) and on Ground based ones (GBAS - Ground Based Augmentation System). The goal of this work is to present some results on SBAS and GBAS performances. Regarding SBAS, the Department of Applied Sciences of Parthenope University, after the acquisition of a Novatel OEM4 SBAS receiver has created a monitoring station that reflect as much as possible a standardized measure environment for EGNOS Data Collection Network (EDCN), established by Eurocontrol. The Department of Applied Science has decided to carry out a own monitoring survey to verify the performance of EGNOS that can be achieved in South Europe region, a zone not very covered by official (EDCN) monitoring network. Regarding GBAS, we started from a data set of measurements carried out at the GBAS of Milan-Linate airport where we work on a ground installation (GMS - Ground Monitoring Station) that supervises the GBAS signal and that represent, for our purposes, the Aircraft subsystem. So the set of data collected is to be considered in RTK mode and after the measures session we processed them with the software PEGASUS v 4.11. Both experiences give us the possibility to evaluate the GNSS1 performance that can be achieved.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.4
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• pp.358-365
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• 2011

Recently, the LED(Light Emitting Diode) replacing incandescent light bulbs and fluorescent light has great attentions as a most promising candidate for the next generation lighting source due to its environment-friendly characteristics, long life and excellent efficiency. Moreover, since it is a semiconductor device which can convert the electric energy to visible light at a very high speed, it can also used as a communication device. Therefore, the VLC(Visible Light Communication) using the LED can perform the near field communication and lighting function at the same time without additional expenses. However, since the switching device of the conventional LED driver for VLC is operated in the linear region, there exist several drawbacks such as a poor power conversion efficiency and serious heat generation. On the other hand, since the proposed driver is operated in the on/off switching region, it features a higher efficiency and more improved heat generation. To verify the validity of the proposed LED driver, experimental results from a prototype of 20W rated LED driver applied to 3MHz bps broadcasting audio system are given.

• The Transactions of the Korea Information Processing Society
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• v.4 no.7
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• pp.1900-1906
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• 1997

In this paper, the efficient BILBO(named EBILBO) is designed for BIST that is able to batch the testing when circuit is designed on FPGA. The proposed algorithm of batch testing is able to test the normal operation speed with one-pin-count that can control all part of large and complex circuit. PRTPG is used for the test pattern and MISR is used for PSA. The proposed algorithm of batch testing is VHDL coding on behavioral description, so it is easily modified the model of test pattern generation, signature analysis and compression. The EBILBO's area and the performance of designed BIST are evaluated with ISCAS89 benchmark circuit on FPGA. In circuit with above 600 cells, it is shown that area is reduced below 30%, test pattern is flexibly generated about 500K and the fault coverage is from 88.3% to 100%. EBILBO for the proposed batch testing BIST is able to execute concurrently normal and test mode operation in real time to the number of $s+n+(2^s/2^p-1)$ clock(where, in CUT, # of PI;n, # of register, p is order # of polynomial). The proposed algorithm coded with VHDL is made of library, then it well be widely applied to DFT that satisfy the design and test field on sme time.

• Journal of Sensor Science and Technology
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• v.6 no.5
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• pp.392-399
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• 1997

In this study, the effect of the sintering temperature on the dielectric and piezoelectric properties of 0.5 wt% $MnO_{2}$-doped $0.125Pb(Mg_{1/2}Nb_{2/3})O_{3}-0.435PbTiO_{3}-0.44PbZrO_{3}$ ceramics were investigated aiming at ultrasonic motor applications. From experimental result, it was found that the optimal sintering temperature condition was at $1270^{\circ}C$. The sample sintered at $1270^{\circ}C$ had density of $7.72\;g/cm^{3}$, dielectric constant of 570, dielectric loss of 0.82%, remanent polarization of $19.18{\mu}C/cm^{2}$, coercive field of 9.63 kV/cm, electromechanical coupling factor of radial mode of 55.1%, mechanical quality factor of 886. Temperature and frequency dependence of dielectric constant and dielectric loss of the sintered sample at $1270^{\circ}C$ was also investigated.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.6
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• pp.611-620
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• 2008

The process of sediment transport has a very complex mechanism due to waves, currents and bottom topography changes. Usually, beach erosion occurs from various causes such as non-equilibrium sediment transport condition, construction of seawall and rip currents. Therefore, when we try to reduce and develop countermeasures for beach erosion, we have to know the main mode and direction of sediment transport that causes beach erosion. In this study, the process of sediment transport on Jeonchon-Najung beach and main causes of beach erosion have been studied. Field investigation data, aerial photos and the results of numerical model test were used in the analysis. As a result, it was realized that the main causes of beach erosion at Jeonchon-Najung beach was due to the construction of fishery harbors and a seawall.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.99-103
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• 2006

In this paper, we focus on the problem of designing an energy efficient MAC protocol for wireless sensor networks and analyze S(Sensor)-MAC and T(Time-out)-MAC. S-MAC is based on the concept of the 'listen/sleep mode cycle'. This applies message passing to reduce contention latency for sensor-network applications that require store-and-forward processing as data moves through the network. However unlike the S-MAC, where the duration of the cycle is fixed, T-MAC introduces an adaptive duty cycle in a novel way: by dynamical ending the active part of it. This reduces the amount of energy wasted on idle listening, in which nodes wait for potentially incoming messages while still maintaining a reasonable throughput. In this paper we discuss the design of these two Protocols. We analyze them from the aspect of latency, throughput, and power savings when using the OMNeT++ simulator in various environments.

• Journal of Korean Society of Rural Planning
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• v.22 no.2
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• pp.141-152
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• 2016

The role of rural towns as a leisure space has recently been increasing with changes in the consumption trends in domestic tourism. Based on the tourists visiting the town of Sunheul-ri, Jocheon-eup, a rural Village in Jeju Island, this study categorized the market according to the images formed by the tourists of rural towns, and analyzed the preferred mode of participation in rural field activities for each category. We analyzed the characteristic factors of the images of rural tourism formed by the tourists, extracted three factors for cluster analysis, and then formed three groups: "Group of Rural Experience Activity" "Group of Rural Environment and Service" and "Group of Rest in the Rural" After analyzing the preferred activity in each image-category group, we found no significant differences among the groups in ordinary activities such as viewing the scenery, experiencing and learning about the natural environment, and culinary experiences. However, there were significant differences among the groups regarding participation in experiential tour programs with the purpose of active tourism. The "Group of Rural Experience Activity" sought to actively participate in various activity programs, whereas the "Group of Rest in the Rural" comparatively had a weaker preference for such active programs. We thus learnt that tourists' preferred activities are different according to the types of images formed by the tourists visiting rural towns. Therefore, to strengthen the competitive advantage of the rural tourist destinations of Jeju Island, it is necessary to provide various activity programs that are appropriate for the rural regions of Jeju and to accord with the expectations associated with each market segment category by positioning the programs according to the characteristics of the images held by the tourists.

• Journal of Chest Surgery
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• v.40 no.2 s.271
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• pp.128-131
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• 2007

da $Vinci^{TM}$ Surgical System is an advanced mode of minimal invasive surgery, using 3-dimensional imaging system and robotic arms which can mimic the dexterity of the human hand. Thus, various operations can be performed with minimal incision and limited surgical field and the merits of minimal invasive surgery can be maximized by using it. We report our first experience of robotic open heart surgery using the da $Vinci^{TM}$ Surgical System for repairing atrial septal defect.