• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.254-259
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• 2003

The 4-probe method with a voltage tap on terminals has been used for the measurement of the critical current of multi-strand high-Tc superconducting (HTS) cables. And the critical current of cables is obtained as the measured total current divided by the number of conductor when the terminal voltage exceeds the predetermined criterion of critical current. However, because of the non-uniform current distribution due to the different critical current, shapes, and other characteristics of each conductor this is not applicable method to the multi-strand HTS cable. To determine the critical current of multi-strand HTS cable the critical current of each conductor must be measured with different method. In this paper, the current distribution and the critical current of each conductor in multi-strand cable were measured with specially made pick-up coils and voltage taps. It is presented that the real critical current of multi-strand is smaller than sum of each conductors. The main cause of non-uniform current distribution is the different resistances appeared in each HTS wires.

• 비파괴검사학회지
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• 제23권4호
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• pp.356-363
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• 2003

플랜트, 산업용 설비로서 사용되어지고 있는 강관의 결함 검출을 위한 와전류검사장비를 개발하였다. 강관은 내부 불균일 한 전자기적 특성을 포함하고 있는 자성체로서 와전류검사의 응답신호를 왜곡시키므로 이러한 전자기적 특성의 균일화를 위해 자기포화가 요구된다. 자기포화가 없을 경우 결함신호는 잡음신호와 구별되지 않았으나 약 0.62A의 전류가 코일에 가해졌을 때 자기포화되어 결함을 검출 할 수 있었다 자기포화형 탐촉자는 헬름홀츠 코일을 적용하여 제작하였고 내부 대역 통과필터를 이용하여 직류자기장으로 야기되는 잡음신호를 최소화하였다. 개발된 장비를 이용한 현장실험 결과 1m/sec의 이송속도에서 관통홀$({\phi}=2.0mm)$ 결함을 정확히 검출 할 수 있었다.

• 한국정밀공학회지
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• 제32권6호
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• pp.529-536
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• 2015

A defect could be generated in bolts for a use of oil filters for the manufacturing process and then may affect to the safety and quality in bolts. Also, fine defects may be imbedded in oil filter system. So it is very important that such defects be investigated and screened during the multiple manufacturing processes. Therefore, in order effectively to evaluate the fine defects, the FEM simulations were performed to make characterization in the crack detection of the bolts and the parameters such as number of turns of the coil, the coil size, applied frequency were calculated based on the simulation results. Simulations were carried out for the defect signal of eddy current probe. Exciter and receiver were utilized. In this paper, the FEM simulations were performed in both bobbin-type and pancake-type probe, both probes were optimized under Eddy current FEM simulations and the results of calculation were discussed.

• 한국초전도ㆍ저온공학회논문지
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• 제19권2호
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• pp.48-52
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• 2017

Discrepancy between a power supply current and an actual "spiral" coil current makes the conventional 4-probe measurement of a critical current ($I_c$) of a no-insulation (NI) high temperature superconductor (HTS) coil inaccurate and time-consuming. This paper presents a fast and accurate approach for $I_c$ measurement of NI HTS coils. With an NI HTS coil energized at a constant ramping rate, a complete analytic expression for the spiral coil current was obtained from a first-order partial differential equation that derived from an equivalent circuit model of the NI coil. From the analytic solution, both spiral coil current and radial leak current can be obtained simultaneously, which enables fast and accurate measurement of the NI coil $I_c$. To verify the proposed approach, an NI double-pancake (DP) coil, wound with GdBCO tapes of $6mm{\times}0.1mm$, was constructed and its $I_c$ was repeatedly measured with various ramping rates in a bath of liquid nitrogen at 77 K. The measured results agreed well with the calculated ones, which validates the proposed approach to measure $I_c$ of an NI HTS coil.

• 한국전기전자재료학회논문지
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• 제19권10호
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• pp.960-965
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• 2006

This research aims to develop the multiple channel electrochemical DNA chip using microfabrication technology. At first, we fabricated a high integration type DNA chip array by lithography technology. Several probe DNAs consisting of thiol group at their 5-end were immobilized on the gold electrodes. Then target DNAs were hybridized and reacted. Cyclic voltammetry showed a difference between target DNA and control DNA in the anodic peak current values. Therefore, it is able to detect a plural genes electrochemically after immobilization of a plural probe DNA and hybridization of non-labeling target DNA on the electrodes simultaneously. It suggested that this DNA chip could recognize the sequence specific genes.

• 천문학논총
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• 제15권spc2호
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• pp.37-44
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• 2000

Two different types of plasma probes have been developed and are currently in operation on board the KOMPSAT-l. One is the cylindrical Langmuir Probe (LP) that measures the electron density and temperature from its current-voltage characteristics in thermal plasmas, and the other is the Electron Temperature Sensor (ETS) which directly gives the information of the ambient electron temperatures. These plasma probes provide the electron properties of the local nighttime ionosphere at the KOMPSAT-l altitudes. In this paper we briefly describe the probes and the initial results obtained from these probes since the beginning of their normal operation in April, 2000.

• 한국환경과학회지
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• 제14권1호
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• pp.15-22
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• 2005

Natural gas possesses several characteristics that make it desirable as an engine fuel; 1)lower production cost, 2)abundant commodity and 3)cleaner energy source than gasoline. Due to the physics characteristics of natural gas, the volumetric efficiency and flame speed of a natural gas engine are lower than those of a gasoline engine, which results in a power loss of $10-20{\%}$ when compared to a normal gasoline engine. This paper describes the results of a research to improve the performance of a natural gas engine through the modification and controls of compression ratio, air/fuel ratio, spark advance and supercharging and method of measuring flame propagation velocity. It emphasizes how to improve the power characteristics of a natural gas engine. Combustion characteristics are also studied using an ion probe. The ion probe is applied to measure flame speed of gasoline and methane fuels to confirm the performance improvement of natural gas engine combustion characteristics.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.105.4-105
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• 2001

This paper describes a newly designed multipoint process monitoring system based on a NIR acousto-optic tunable filter. The NIR multipoint process monitoring system consists of a NIR AOTF device for wavelength selection, an InGaAs array sensor, and a specially designed iin-line type of optical fiber probe. Unlike a FTS(Fourier Transform Spectrometry) or grating based monitoring system, an AOTF has no moving parts, and it can be rapidly tuned to any wavelength in its operating range within microseconds. Thus, the AOTF is advantageous in terms of faster spectral imaging capability and rigidity required for industrial monitoring environment. In the current feasibility evaluation, an enhanced optical fiber probe with 3 monitoring points was used. However, ...

• 대한의용생체공학회:의공학회지
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• 제26권4호
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• pp.207-214
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• 2005

Breast cancer detection using electrical impedance techniques is based on numerous experimental findings that cancerous tissues have higher electrical conductivity values than normal tissues. Lately, by taking advantage of the structure of current flows underneath a planar probe of array electrodes, a mathematical formula to find lesions from a measured trans­admittance map has been derived. In order to experimentally validate its mathematical analysis and the suggested lesion estimation algorithm, we developed a 256-channel trans-admittance scanner (TAS) for probing anomalies underneath a planar array of electrodes. In this paper, we describe the design and implementation of the TAS. Its performance together with the lesion estimation algorithm was evaluated using saline phantoms. Further studies are proposed to validate the system on human subjects.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.216-216
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• 2011

There have been various direct or indirect methods to measure the characteristics of plasma. Comparing to direct method like Langmuir probe method, indirect measurements which give information as some external parameters like current, voltage, or phase are easier to obtain. In this research, an indirect method to measure averaged plasma density in a transformer coupled plasma(TCP) has been proposed and evaluated. With a simple analytic model connecting electrical characteristics to plasma impedance, direct measurement via double Langmuir probe has been performed. This result may play a meaningful role to diagnose TCP or similar plasma sources