• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.449-451
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• 2002

Sheath circulating current rises from the change of sheath mutual impedance which is caused by imbalanced cable system, and different section length between joint boxes. However, mixed burying typo and imbalance section length take many parts of main reasons of sheath circulating current increment in domestic underground transmission power cables. Therefore, the increment reason and variation characteristics of sheath circulating current is analysed with simulation using EMTP/ATPDraw and measuring data of practical cable system which has a problem of exceeding sheath circulating current in this paper.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1855-1857
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• 2001

An Inverted-F antenna for the 2.4GHz application is designed and implemented. The antenna is implemented on the PCB board and installed in a vertical position. The 10dB characteristics are 2.4 to 2.48GHz in bandwidth which satisfies the bluetooth requirement and the whole impedance is matched. The feed-line on the PCB board is also calculated and implemented. And the measuring system is installed at the KITI in Kangwon Nat'l Univ. and applied to measured the antenna characteristics. The measured values show that this antenna is suitable for the commercial applications.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.241-245
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• 2002

Dual-band microstrip antenna is designed for industrial-scientific-medical(ISM) band of 2.4㎓ and 5.8㎓ using finite-difference time-domain method(FDTD). Cross Patch fed 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 by aperture and stub length change is examined. And it is investigated that center frequency and -10 ㏈ bandwidth by Length of radiation element and width change. Experimental result about reflection Loss confirmed that agree well with analysis results of FDTD and IE3D, And -3 ㏈ beam width, front to back ratio and gain in frequency 2.43㎓ and 5.79㎓ is presented by measuring radiation Pattern of antenna.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.2
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• pp.66-75
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• 1993

This paper proposes a monitoring method for nondestructive and in-process measurement of the case depth in LASER surface heat treatment process. The method is essentially an eddy-current method, and measures sensing coil's electrical impedance which varies with the changes of the material microstructure due to hardening. To investigate te validity of the proposed method a series of experiments were performed for various hardning depths. The results show that the relationship between the eddy- current sensor output and the changes in case depth is almost linear. This indicates that the eddy-current measuring method can be used as one of the possible monitoring method for mesauring the hardened depth in LASER heat treatment processes.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.2
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• pp.190-195
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• 2003

We developed a loading sleeve for Automobile, which has the PCS and IMT-2000 frequency bands. The electric characteristics of the designed sleeve monopole has SWR<1.311 and 3.0dBi in average gain for that frequency bands. In this study, the designed sleeve monopole was installed at a roof and trunk lid of vehicle. The characteristics of designed sleeve monopole was investigated by measuring SWR, input impedance and radiation pattern. The experimental results show that the efficiency of the sleeve monopole is superior th that of domestic and foreign commercial PCS antenna.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2699-2701
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• 2002

In this study, a system for measurement of impedance (transmission parameter) on the human muscle was constructed. The system composed of the stimulating part for input with milli-voltage and the measuring part for measurement of transmission voltage in human muscle. As a result of this experiment, the frequency characteristic of each subject represent that the transmission voltage goes up in spite of a constant input voltage according to frequency (1Hz -50kHz) increment. Namely, the amplitude of input signal was not reflected but frequency was reflected on the measured results. This result be estimated that the proposed system is able to measure passive electrical characteristic of human body.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1773-1775
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• 1998

This paper deals with the pulse generator using PFN(Pulse Forming Network), and its operation characteristics and application. Two kinds of pulse generator were composed of the best appropriate condition circuit. The output current of the one pulse generator has the rise time of 28 ns and the pulse duration of $7{\mu}s$. The other pulse generator has high current of about 2kA. By use of the former generator with rapid rise time, the impulse impedance characteristic of ground electrodes was investigated with measuring the ground potential rise when the pulse current was injected into the ground electrode.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1801-1803
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• 1997

The Gas Insulated Switchgear(GIS) has made it an indispensible part of power transmission network. In order that the GIS may have its high reliability, it is necessary to pay careful attention to its whole process e.g., designing, manufacturing, installation, and operation. The main hazard in GIS comes from free conducting particles, which can move and cause breakdown under the influence of the electric field. Although the concentration on protecting the GIS inner part against the free conducting particles is made, it is, actually, almost impossible to avoid the hazard from the particles throughly. In this paper, the corona discharge in GIS initiated by the free conducting particles was discribed through laboratorial experiment The magnitude of the corona discharge voltage was measured using current measuring method by the impedance. The purpose of this experiment is to get fundamental data which is essential to develop GIS diagnosis technology.

• Journal of the Korean Ceramic Society
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• v.28 no.12
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• pp.953-960
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• 1991

Effect of MgO doping was studied by measuring complex impedance of PZT[Pb(Zr0.52Ti0.48)O3] samples doped with 0.25~6 mol% MgO. Electrical conductivity of PZT samples increased within 1.5 mol% of MgO doping. However above 1.5 mol%, no noticeable changes were found. Activation energy and pre-exponential factor of electrical conductivity were found to decrease within 1.5 mol% of MgO doping, but increase above 1.5 mol%. Therefore it was concluded that the decrease of electrical conductivity with MgO doping was due to the decrease of activation energy.

• 전기의세계
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• v.28 no.4
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• pp.47-52
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• 1979

Total number of resonant modes in a microwave oven cavity may be maximized for a given frequency bandwidth to obtain more uniform power distribution by choosing proper size of the cavity. The total number of modes is calculated for a dielectrically loaded rectangular cavity and its size is suggested here for which the change in the number of modes is less sensitive to the change of dielectric layer thickness and its total number of modes is maximized in a given range of cavity sizes. A prove coupled rectangular cavity is constructed and the total existing modes are measured to see the change of modes depending on the dielectric layer thickness and the cavity size. Surface wave mode existing in the dielectric layer is confirmed by measuring Q and the input impedance of the cavity for this mode, which closely compares with the calculation.