• Journal of IKEEE
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• v.19 no.2
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• pp.124-132
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• 2015

In this paper, we proposed a multiband internal antenna for LTE mobile handset that could be used for mobile devices. The proposed antenna has a volume of $50mm(W){\times}21mm(L){\times}5mm(H)$, ground plane size is $60mm(W){\times}100mm(L)$, and covers 9 service frequency bands including LTE(Long Term Evolution) band with VSWR(Vlotage Standing Wave Ratio) less than 3. With rapid change of technologies, people wants to include more function into one device. In addition, each country uses different frequency band for traffic service, it is necessary to design multiband antenna for mobile phone since traveling foreign country needs roaming. And if we can cover several services with one antenna, cost and volume needed for antennas are minimized. A HFSS (High Frequency Structure Simulator) of the Ansoft Corporation based on a finite element method is employed to analyze the proposed antenna in the design process and to compare the simulation and experimental results.

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.39-40
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• 2006

Digital image-projection and several modifications are the classical applications of Digital Micromirror Devices (DMD), however further applications in the field of optical metrology are also available. Operated with certain patterns, a DMD can function, for instance, as an array of pinholes that may substitute the Galvanic mirror or the stage scanning system presently used for 2 dimensional scanning in confocal microscopes. The various process parameters that influence the result of measurement (e.g. pinhole size, lateral scanning pitch and the number of pinholes used simultaneously, etc.) should be configured precisely for individual measurements by appropriately operating the DMD. This paper presents suitable conditions for the diffraction limited analysis between DMD-optics-CCD to achieve the best performance. Also sampling theorem that is necessary for the image acquisition by scanning system is simulated with OPTISCAN which is the simulator based on the diffraction theory.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.3
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• pp.347-358
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• 1998

The possibility of modeling the complex and diversified radio environment using Rician channel has been considered. The signals received in Rician channel have been simulated using the computer simulator. The PDF(Probability Density Function of the Envelope amplitude), PSD(Power Spectral Density), LCR(Level Crossing Rate), ADF(Average Duration of Fades) and BER(Bit Error Rate) of the simulated signal have been compared with those of theory. They were shown to be in good agreement.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.292-294
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• 2016

이황화몰리브덴을 활용한 전계효과트랜지스터(Field Effect Transistor)는 채널 물질의 우수한 특성으로 차세대 저전력 고성능 스위치와 광전소자로 주목받고있다. Underlap 게이트 구조에서 게이트 길이(L_G), 절연체 두께(T), 절연체 상대유전율(${\varepsilon}_r$)에 따라 변화하는 소자특성을 분석하여 저전력 고성능 $MoS_2$ 전계효과트랜지스터를 위한 게이트 구조 최적화방법을 모색하였다. EDISON simulator 중 Tight-binding NEGF 기반 TMD FET 소자 성능 및 특성 해석용 S/W를 활용하여 게이트 구조에 따른 게이트 전압 - 드레인 전류 상관관계(transfer characteristic)를 얻고, Y-function method를 이용하여 채널 유효전하이동도(Effective Mobility), Sub-threshold Swing, on/off 전류비(on/off current ratio)를 추출하여 비교 분석하였다. 시뮬레이션으로 추출한 소자의 최대 채널 유효전하이동도는 $37cm^2V^{-1}s^{-1}$, on/off 전류비는 $10^4{\sim}10^5$, Sub-threshold Swing은 ~38mV/dec 수준을 보였다.

• Journal of Electrical Engineering and Technology
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• v.7 no.2
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• pp.236-239
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• 2012

In this paper, we study the transient characteristics of 4H-SiC DMOSFETs with different interface charges to improve the turn-on rising time. A physics-based two-dimensional mixed device and circuit simulator was used to understand the relationship between the switching characteristics and the physical device structures. As the $SiO_2$/SiC interface charge increases, the current density is reduced and the switching time is increased, which is due primarily to the lowered channel mobility. The result of the switching performance is shown as a function of the gate-to-source capacitance and the channel resistance. The results show that the switching performance of the 4H-SiC DMOSFET is sensitive to the channel resistance that is affected by the interface charge variations, which suggests that it is essential to reduce the interface charge densities in order to improve the switching speed in 4H-SiC DMOSFETs.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.11
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• pp.96-101
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• 2015

In recent years, researches regarding optimal placement of CCTV(Closed-circuit Television) cameras via architecture modeling has been conducted. However, for analyzing surveillance coverage through actual human movement, the application of VA(Video Analytics) function of IP(Internet Protocol) cameras has not been studied. This paper compares two methods using data captured from real-world cameras and data acquired from a virtual environment. In using real cameras, we develop GUI(Graphical User Interface) to be used as a logfile which is stored hourly and daily through VA functions and to be used commercially for placement of products inside a shop. The virtual environment was constructed to emulate an real world such as the building structure and the camera with its specifications. Moreover, suitable placement of the camera is done by recognizing obstacles and the number of people counted within the camera's range of view. This research aims to solve time and economic constraints of actual installation of surveillance cameras in real-world environment and to do feasibility study of virtual environment.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.504-505
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• 2014

In this paper, by using hardware in the loop(HIL) of the EES, which is an inverter of high-rated technique and analyze the function. By exchanging information between the simulation and system controller to be used in a live system, HIL approach, approach experimental is used to interpret the system mass analysis is not possible in a real system some. This paper presents the implementation of the EES and the RTDS DSP28335 is a real-time connection to the electrical signal, and to verify the actual system is difficult, it was possible to analyze the performance of the system. Thus, it is expected to contribute I raise the stability and reliability of the operation during the actual EES is built.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.6 s.111
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• pp.658-664
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• 2006

Shock vibrations are usually experienced in vehicles excited by impulsive input, such as bumps. The frequency weighting functions of the current standards in ISO 2631 and BS 6841 are to help objectively predict the amount of discomfort of stationary vibration. This experimental study was designed to develop frequency weighting shape for shock vibration having various fundamental frequencies from 0.5 to 16Hz. The specks were produced from the response of single. degree-of-freedom model to a half-sine force input. Fifteen subjects used the magnitude estimation method to judge the discomfort of vertical shock vibration generated on the rigid seat mounted on the simulator. The magnitudes of the shocks, expressed in terms of both peak-to-peak value and un-weighted vibration dose values (VDVs) , were correlated with magnitude estimates of the discomfort. The frequency weighting shapes from the correlation were developed and investigated having nonlinearity due to the magnitude of the shock.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.67-75
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• 2021

As pass the three revised bills, the Personal Information Protection Act was revised to have a larger application for personal information. For an industrial development through an efficient and secure usage of personal information, there is a need to revise the existing anonymity processing method. This paper modifies the Zero Knowledge Proofs algorithm among the anonymity processing methods to modify the anonymity process calculations by taking into account the reliability of the used service company. More detail, the formula of ZKP (Zero Knowledge Proof) used by ZK-SNAKE is used to modify the personal information for pseudonymization processing. The core function of the proposed algorithm is the addition of user variables and adjustment of the difficulty level according to the reliability of the data user organization and the scope of use. Through Setup_p, the additional variable γ can be selectively applied according to the reliability of the user institution, and the degree of agreement of Witness is adjusted according to the reliability of the institution entered through Prove_p. The difficulty of the verification process is adjusted by considering the reliability of the institution entered through Verify_p. SimProve, a simulator, also refers to the scope of use and the reliability of the input authority. With this suggestion, it is possible to increase reliability and security of anonymity processing and distribution of personal information.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.2
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• pp.75-81
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• 2021

This study analyzes the resonance characteristics caused by the mutual interference between LCL filters and the grid impedance under the parallel operation of the grid-connected inverter using the LCL filter. These characteristics are verified through simulation and experiment. Two inverters are used to connect to the grid in parallel, and the system parameters, including the LCL filter, are set to the same conditions. In the case of inverters running in parallel at the point of common coupling, the presence of grid impedance causes mutual interference between the LCL filters of each inverter, and the deviation of the filter resonance frequency is analyzed to understand the parallel inverter. The correlation between the number of devices and the size of grid impedance is simulated by PSIM and verified by MATLAB. By connecting the real-time digital simulator Typhoon HILS to the DSP 28377 control board, the mutual interference characteristics are tested under the condition of two inverters running in parallel. The experimental and analysis results are the same, indicating the validity of the analysis.