• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.7 s.349
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• pp.13-19
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• 2006

A 5Gb/s cross coupled transimpedance amplifier (TIA) & limiting amp(LA), regulated cascode(RGC) is realized in a 0.18$\mu$m CMOS technology for optical printed circuit board applications. The optical receiver demonstrates $92.8db{\Omega}$ transimpedance and limiting amplifier gain, 5Gb/s bandwidth for 0.5pF photodiode capacitance, and 9.74mW power dissipation from 1.8V, 2.4V supply. Input stage impedance is $50{\Omega}$. The circuit was implemented on an optical PCB, and the 5Gb/s data output signal was measured with a good data eye opening.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.104-106
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• 2003

In recent years for propulsion of cooling fan in cars are more used electrical motors than the engine direct coupled type. But the electrical motor which is now used has the brush and the commutator. Because of the brush and the commutator the electrical motor has short life time, low efficiency and mechanical- electrical noise. Therefore it is tried to develope brushless dc motor. The motor is located in the hot air from the radiator. The motor temperature increases high and the increasing of the motor temperature rolls big in its character. The cooling fan motor has relative small in size and input voltage is low. For 300 w output power must be the current of the motor high which causes high copper loss. In this paper will be tested and analysed characteristics of a dc motor which is now used for cooling fan and a BLDC motor will be designed with same character of the brushed motor and with considering of improvement of the efficiency. After design the motor should be analysed and tested.

• The KSFM Journal of Fluid Machinery
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• v.1 no.1 s.1
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• pp.7-16
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• 1998

An interactive mode of grid generation system has been developed for a Navier-Stokes design procedure of axial flow compressors. The present grid generator adopts the multiblock H-grid structure, which simplifies the creation of computational grids about complex turbomachinery geometries and facilitate the manipulation of multiple grid blocks for multirow flow fields. The numerical algorithm adopts the combination of the algebraic and elliptic method to create the internal grids efficiently and quickly. The system consists of four separated modules, which are linked together with a common graphical user interface. The system input is made of the results of the preliminary design. The final grids generated from each module of the system are used as the preprocessor for the performance prediction of the two-or three-dimensional flow simulation inside the blade passage. Application to the blade design of the LP compressor was demonstrated to be very reliable and practical in support of design activities. This customized system are coupled strongly with the design procedure of the turbomachinery cascades using the Navier-Stokes technique.

• Journal of electromagnetic engineering and science
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• v.4 no.4
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• pp.168-174
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• 2004

A bandwidth-enhanced and phase noise-improved differential LC-tank VCO is proposed in this paper. By connecting the varactors to the bases of the cross-coupled transistors of the proposed LC-tank VCO, its input negative resistance has been widened. Also, the feedback capacitor Cc in the cross-coupling path of the proposed LC-tank VCO attenuates the output common-mode level modulated by the low-frequency noise because the modulated common-mode level jitters the varactor bias point and degrades phase noise. Compared with the fabricated conventional LC-tank VCO, the proposed LC-tank VCO demonstrates $200\;\%$ enhancement in tuning range, and 6 - dB improvement in phase noise at 6 MHz offset frequency from 5.4-GHz carrier. We achieved the phase noise of - 106 dBc/Hz at 6 MHz offset, and $10\;\%$ tuning range from the proposed LC-tank VCO. The proposed LC-tank VCO consumes 12 mA at 2.5 V supply voltage.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.5
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• pp.479-488
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• 2003

Dual-band microstrip antenna is designed for industrial-scientific-medical(ISM) band of 2.4 GHz and 5.8 GHz using finite-difference time-domain method(FDTD). Cross patch 130 by aperture in the ground plane of microstrip line is proposed as radiation element of antenna which is 2 rectangular patch is overlapped. To design antenna, change of input impedance is examined by length change of aperture and stub. And center frequency and - 10 dB bandwidth are investigated by change of length and width in radiation element. Measured result about reflection loss confirm that agree well with simulation results of FDTD and IE3D. And 3 dB beam width, front to back ratio and maximum gain is presented by measuring radiation pattern of antenna in frequency 2.43 GHz and 5.79 GHz.

• Journal of Korea Spatial Information System Society
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• v.11 no.2
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• pp.27-33
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• 2009

The emergences of GeoSensor and researches about GIS have promoted many researches of u-GIS. The disaster application coupled in the u-GIS can apply to monitor accident area and to prevent spread of accident. The application needs the u-GIS DSMS technique to acquire, to process GeoSensor data and to integrate them with GIS data. The u-GIS DSMS must process big and large-volume data stream such as spatial data and multimedia data. Due to the feature of the data stream, in u-GIS DSMS, query processing can be delayed. Moreover, as increasing the input rate of data in the area generating events, the network traffic is increased. To solve this problem, in this paper we describe TRIGGER ACTION clause in CQ on the u-GIS DSMS environment and proposes data source management. Data source weight table controls GES information and incoming data rate. It controls incoming data rate as increasing weight at GES of disaster area. Consequently, it can contribute query processing rate and accuracy

• Journal of Technology Innovation
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• v.12 no.2
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• pp.209-225
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• 2004

This study aims to explore and understand the role of knowledge intensive service activities in the industrial innovation of Korea. It analyzes public and private service inputs to the innovation of manufacturers. The contribution of KISs to the innovation of both service suppliers and manufacturers was analyzed by using survey questionnaire. The results of the analysis revealed that the contribution of KISs to the innovation capability of manufacturers is significant. Large manufacturers that hold internal capability to supply KISs are also active in using external KISs. The manufacturing firms that utilized KISs intensively proved to be more innovative than those did not. Heavy KISs users also entertained benefits of capability enhancement as they improved monitoring and achieved efficient application of knowledge asset into product and process innovation. The role of public KISs in the innovation of manufacturers appeared to be indirect and done mainly through education and public R&D activities. Direct input, such as public software service, was not utilized as much in service suppliers themselves. The major reason is that public KISs may not be relevant to their actual needs. Manufacturers have implemented both tighter integration of familiar KISs and loosely coupled unfamiliar KISs.

• Transactions on Electrical and Electronic Materials
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• v.15 no.6
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• pp.309-314
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• 2014

This work proposes an integrated high frequency divider with an inductive peaking technique implemented in a current mode logic (CML) frequency divider. The proposed divider is composed with a master-slave flip-flop, and the master-slave flip-flop acts as a latch and read circuits which have the differential pair and cross-coupled n-MOSFETs. The cascode bias is applied in an inductive peaking circuit as a current source and the cascode bias is used for its high current driving capability and stable frequency response. The proposed divider is designed with $0.18-{\mu}m$ CMOS process, and the simulation used to evaluate the divider is performed with phase-locked loop (PLL) circuit as a feedback circuit. A divide-by-two operation is properly performed at a high frequency of 20 GHz. In the output frequency spectrum of the PLL, a peak frequency of 2 GHz is obtained witha divide-by-eight circuit at an input frequency of 250 MHz. The reference spur is obtained at -64 dBc and the power consumption is 13 mW.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.5
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• pp.1-9
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• 2010

Evapotranspiration (ET) is one of the basic components of the hydrologic cycle and is essential for estimating irrigation water requirements. In this study, artificial neural network (ANN) models for reference crop evapotranspiration ($ET_0$) estimation were developed on a monthly basis (May~October). The models were trained and tested for Suwon, Korea. Four climate factors, daily maximum temperature ($T_{max}$), daily minimum temperature ($T_{min}$), rainfall (R), and solar radiation (S) were used as the input parameters of the models. The target values of the models were calculated using Food and Agriculture Organization (FAO) Penman-Monteith equation. Future climate data were generated using LARS-WG (Long Ashton Research Station-Weather Generator), stochastic weather generator, based on HadCM3 (Hadley Centre Coupled Model, ver.3) A1B scenario. The evapotranspirations were 549.7 mm/yr in baseline period (1973-2008), 558.1 mm/yr in 2011-2030, 593.0 mm/yr in 2046-2065, and 641.1 mm/yr in 2080-2099. The results showed that the ANN models achieved good performances in estimating future reference crop evapotranspiration.

• Journal of Astronomy and Space Sciences
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• v.24 no.1
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• pp.31-38
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• 2007

We have investigated the evolutionary status of 85 Peg within the framework of standard evolutionary theory. 85 Peg has been known to be a visual and spectroscopic binary system in the solar neighborhood. In spite of the accurate information of the total mass (${\sim}1.5M_{\odot}$) and the distance (${\sim}12pc$) from the HIPPARCOS parallax, it has been undetermined an individual mass, therefore the evolved status of the system. Moreover, the coupled uncertainties of chemical composition and age, make matters worse in predicting an evolutionary status of the system. Nevertheless, we computed the various possible models for 85 Peg, and then calibrated stellar parameters by adjusting to the recent observational data. Our modelling computation has included recently updated input physics and stellar theory such as opacity, equation of state, and chemical diffusion. Through a statistical assessment, we have derived a confident parameter set as the best solution which minimized $X^{2}$ within the observational error domain. Most of all, we found that 85 Peg is not a binary system but a triple system with an unseen companion 85 Peg $B_{b}\;{\sim}0.16M_{\odot}$. The aim of the present paper is (1) to provide a complete modelling of the stellar system based on the evolutionary theory, and (2) to constrain the physical dimensions such as mass, metallicity and age.