• Journal of Environmental Science International
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• v.9 no.5
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• pp.429-436
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• 2000

In order to study on the variational characteristics of water quality and chlorolphyll a concentration the water samples were collected daily or three times a week during the period from April 1990 to November 1991 at Kukdong port located in the northern Kamak bay of Southern Korea I made an analysis on biological factor as chlorophyll a concentration as well as physico-chemical factors such as water temperature salinity sigma-t dissolved oxygen, nutrients (ammonia, nitrite, nitrate, phosphate, and silicate) N/P ratio and chemical oxygen demand. In Northern Kamak bay seasonal variations in physical factors such as water temperature salinity and sigma-t were very marked. On the other hand chemical factors such as nutrients concentration and COD were not so. Chemical factors, in particular silicate were influenced by input of freshwater. And the roles of silicate on the seasonal succession of phytoplankton species composition was very low. Phytoplankton biomass as measured by chlorophyll a concentration was very high all the year round and it was controlled by the combination of several factors especially of N/P ratio determined by dissolved inorganic nitrogen.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.2
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• pp.339-346
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• 1999

A RF receiver section for INMARSAT-C external mounting unit was designed, fabricated and evaluated. Using a INA-03184, the high gain amplifier consists of matched amplifier type. Active bias circuitry can be used to provide temperature stability without requiring the large voltage drop or relatively high-dissipated power needed with a bias stabilization resistor. The bandpass filter was used to reduce a spurious level. As a result, the characteristics of the receiver section implemented here show 60 dB in gain, 44.83 dBc in a spurious level. The voltage standing wave ratios(VSWR)of input output port are less than 1.8:1, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.8
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• pp.1721-1728
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• 2009

Future computer interface was interchanged with person's hands or eyes from traditional mouse. In this research, I developed glove type radio mouse using gyro sensor that is replaced mouse cursor movement with persons's hand movement. Introducing a mobile sensor network technology based on bluetooth, radio mouse connected to computer system wirelessly for overcoming wire mouse's activity restrictions. Also, using USB port interface made be easy to install and to use. Developed glove type radio mouse was confirmed in the possibility of using as well as an input pointing device for presentations or games that needed many kinds of user interaction.

• International Journal of Safety
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• v.11 no.2
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• pp.10-14
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• 2012

Recently, the combined power plants are refocused rapidly as a replaceable energy system of the nuclear power plant. The large turbine is revolved highly at 1800~3600 rpm. Thus, the turbine speed should be monitored with mechanical and electrical method for a safety. The electrical cutoff valve which blocks the flow channel with the electrical signal is with a built in. The aim of this study is to develop a manufacturing technology through by the localization of a solenoid actuated directional control valve. Especially the results show performances of the solenoid valve by the experiments and modeling and the reliability estimation. Applied load port pressure was changed rapidly on the form of a quadratic curve over time. And in the cases of square waveform when 0~100 V and 20~120 V input voltage, it was driven on a stable state until 13.4 Hz and 16.6 Hz, respectively. We think that this study will give useful data for the electricity safety system of the combined power plant gas turbine.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.10
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• pp.59-68
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• 2013

This paper proposes the boost type bidirectional DC/DC converter with high efficiency for electric vehicle using an interleave method. This interleave method can reduce the system size because it reduces the ripple of output voltage and input current with no add to extra filter. Proposed system is consist of two converters and applies to interleaved method through phase shift to each converter. And it implements the high boost through voltage double and series construction of output port. Also, it reduces the price and increases the efficiency as operating the ZCS by leakage inductance of transformer and capacitor of voltage double with not add special reactor. Proposed DC/DC converter using interleave method is proved the validity through the result of PSIM simulation and experiment of 5kW DC/DC converter.

• Journal of the Korea Society of Computer and Information
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• v.3 no.2
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• pp.29-35
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• 1998

In this paper, the proposed audio/video control device for multiple user in the multimedia platform is changed for the better a disadvantage that must get one computer per participant to process a floor mode needed for interactive collaboration in the multimedia based distance education. It also proposed simulator of co-work environment that included multimedia data. This developed to proceed a multimedia distance education efficiently and sharing a computer among multiple users. Therefore, this is resulting in a reduction the cost needed to build a multimedia distance education system as well as totally simplified the organization of system. It also offers compatibility and generality, interfacing with the printer port of standard PC supporting the bi-direction mode.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.4
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• pp.39-45
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• 2009

In this paper, designed and fabricated the microstrip antenna using parasitic plane. This active antenna for the use of AM/FM, DMB(Digital Multimedia Broadcasting), GPS(Global Positioning System) band in vehicle. Fabricated active antenna was compared to existing planar antenna represents more than 15% size reduction and equivalence performance compared to commercial helical antenna. And satisfy performance in DMB, GPS band. This active antenna composed of single input port and two output ports and entire size of antenna is $133{\times}31{\times}1.2mm$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.5
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• pp.426-429
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• 2017

For the W-band remote sensing radiometer, direct detection type radiometer receiver is designed. The receiver should be low noise and high gain of 60 dB unlike communication and radar receiver. The W-band radiometer consist of 4-stage low noise, high gain amplifier, band pass filter and square law detector. The developed direct detection receiver show 4 GHz bandwidth, 56 dB gain, and 4,500 mV/mW voltage sensitivity at integrator output port for -20 dBm input power at 94 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.3
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• pp.254-262
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• 1996

In this paper, we present a polarizer that consists of three step rotary detents which can selectively convert linear polarzation into circular polarization and vice versa. For the design of the polarizer, the transmission line theory is applied to design the wa- veguide mode transducer for the modes to be smothly converted in waveguides, and a dielectric plate is inserted in circular waveguide for the conversion of a polarized wave with the angle of an inserted dielectric plate. Also, we simulated to obtain the optimum values of the transmission and the reflection coefficient characteristics at input and output port, and proved the propriety of the theory from the knowledge of measuring the constructed polarizer with the designed data.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.4
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• pp.821-827
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• 2009

Currently, with the development of web 2.0 knowledge sharing system became more and more important. In this paper, we proposed and implemented seminar assistant system using database system and knowledge sharing system on public seminar. We recorded speaker's voice and presentation files on our system and user can review past talks on our seminar review systems. Our database system is implemented using MS SQL, and Input/Output Completion Port(IOCP) socket model as our server side network module. Also we used presentation software using Direct Show with MFC and Windows Presentation Foundation(WPF). and our review system is based on WFP programmed with C# language.