• 센서학회지
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• 제23권6호
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• pp.368-376
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• 2014

In order to measure the segmental impedance of the body, a bioelectrical impedance measurement system (BIMS) using multi-frequency applying method and two-electrode method was implemented in this study. The BIMS was composed of constant current source, automatic gain control, and multi-frequency generation units. Three experiments were performed using the BIMS and a commercial impedance analyzer (CIA). First, in order to evaluate the performance of the BIMS, four RC circuits connected with a resistor and capacitor in serial and/or parallel were composed. Bioelectrical impedance (BI) was measured by applying multi-frequencies -5, 10, 50, 100, 150, 200, 300, 400, and 500 KHz - to each circuit. BI values measured by the BIMS were in good agreement with those obtained by the CIA for four RC circuits. Second, after measuring BI at each frequency by applying multi-frequency to the left and right forearm and the popliteal region of the body, BI values measured by the BIMS were compared to those acquired by the CIA. Third, when the distance between electrodes was changed to 1, 3, 5, 7, 9, 11, 13, and 15 cm, BI by the BIMS was also compared to BI from the CIA. In addition, BI of extracellular fluid (ECF) was measured at each frequency ranging from 10 to 500 KHz. BI of intracellular fluid (ICF) was calculated by subtracting BI of ECF measured at 500 kHZ from BI measured at seven frequencies ranging from 50 to 500 KHz. BI of ICF and ECF decreased as the frequency increased. BI of ICF sharply decreased at frequencies above 300 KHz.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
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• pp.188-195
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• 2000

This study was conducted to measure the moisture content of powdered food using RF impedance spectroscopic method. In frequency range of 1.0 to 30㎒, the impedance such as reactance and resistance of parallel plate type sample holder filled with wheat flour and red-pepper powder of which moisture content range were 5.93∼-17.07%w.b. and 10.87 ∼ 27.36%w.b., respectively, was characterized using by Q-meter (HP4342). The reactance was a better parameter than the resistance in estimating the moisture density defined as product of moisture content and bulk density which was used to eliminate the effect of bulk density on RF spectral data in this study. Multivariate data analyses such as principal component regression, partial least square regression and multiple linear regression were performed to develop one calibration model having moisture density and reactance spectral data as parameters for determination of moisture content of both wheat flour and red-pepper powder. The best regression model was one by the multiple linear regression model. Its performance for unknown data of powdered food was showed that the bias, standard error of prediction and determination coefficient are 0.179% moisture content, 1.679% moisture content and 0.8849, respectively.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.777-782
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• 2005

In this paper, we designed and fabricated a partial discharge (PD) detector to diagnose the soundness of CNCV cables by analyzing PD pulses and to predict discharge locations. The PD detector is consisted of a coupling network with a discharge free capacitor and a detection impedance, a voltage follower and a low noise amplifier. Lower cut-off frequency of the detector is adjusted at 175kHz to block AC voltage and to pass discharge pulse only. The discharge location could be obtained by the time of arrival method using travelling wave propagation theory. In a laboratory test on an eighty meter CV cable, we could position the discharge location within a two meter error.

• 한국항행학회논문지
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• 제25권5호
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• pp.370-376
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• 2021

항공 우주 산업의 발전으로 발사체의 연구가 많아지고 있다. 더불어 많은 시험이 진행하고 있고 그에 따라 많은 실패도 발생한다. 발사체는 다른 전자장비보다 위험성이 높기 때문에 실패를 최소화할 수 있어야 한다. 따라서 발사체에 전원을 공급하기 전에 배선을 검증할 필요가 있다. 이에 따라 저항 측정을 통해 배선 상태를 검증하였다. 하지만 이전의 저항측정 방식의 배선 점검은 발사체 회로의 커패시터, 인덕터등의 소자들 때문에 정확한 측정을 할 수 없다. 본 논문에서는 TDR 미터를 이용하여 케이블 및 발사체의 연결 상태에서 임피던스를 측정한다. 측정한 정상상태의 임피던스의 기준 값을 설정하기 위해 Z-Segmentation 알고리즘을 사용한다. Z-Segmentation 알고리즘은 우선 임피던스 파형의 피크 값들을 칼만 필터를 이용하여 찾고 찾은 피크값을 Segmentation을 통해 최종 impedance peak segment를 얻는다. 이런 방법으로 배선의 정상 상태에 대한 기준 값으로 설정하고 이를 기준으로 배선 상태를 판정한다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2007년도 제34회 KOSCO SYMPOSIUM 논문집
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• pp.27-30
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• 2007

We have been setting up experiments on propagation of shock waves generated by the pulsed laser ablation. One side of a thin metal foil is subjected to laser ablation as a shock wave is generated from a localized spot of high intensity energy source. The resulting reactive shock wave, which penetrates through the foil is reflected by an acoustic impedance which causes the metal foil to high-strain rate deform. This short time physics is captured on an ICCD camera. The focus of our research is generating reactive shock wave and high strain rate deforming of thin metal foil for accelerating micro-particles to a very high speed on the orders of several thousand meter per second. Somce innovative applications of this device will be discussed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.527-528
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• 2006

A dissipation factor standard of decade type having the range of 1 to 0.0001 at the frequency of 1 kHz and 10 kHz was fabricated using "T" networks combined R and C components. The values of the fabricated dissipation factor standard were adjusted within 1% of the nominal values at 0.0001 dial range and 0.05% at the others. This dissipation factor standard is used as a working standard for calibration of a impedance measurement meter at KRISS and as a primary standard of dissipation factor field at NML-SIRIM in Malaysia.

• 대한기계학회논문집B
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• 제28권11호
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• pp.1398-1406
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• 2004

The nonlinear signals from an impedance meter for the area average void fraction in two-phase flow have been analyzed to construct a phase space trajectory. The pseudo phase space was constructed with the time delay and proper dimensions. The time delay and the embedding dimension were chosen by the average mutual information and by the false nearest neighborhood, respectively. The attractor-density-map of projected states was used to produce the two dimensional probability distribution functions (2D-PDF). Since the developed 2D-PDF showed clear distinction of the flow patterns, the flow regime identification was made with three rules and with the 2D-PDF. Also, the transition criteria of Mishima-Ishii agree well with the present results.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.191-192
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• 2020

The purpose of this study is to measure the electrical conductivity of cementitious composites as an early step to obtain shielding performance by mixing various type of steel fiber into cementitious composites, the main building material of protection facility, to shield electromagnetic pulse (EMP) damage. Fiber such as conductors as amorphous metallic fiber, hooked steel fiber, and smooth steel fiber are mixed into cementitious composites to give electrical conductivity and measure the impedance of concrete using LCR meter. By doing this, the electrical conductivity of each type of steel fiber reinforced cementitious composites (FRCC) is compared.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.62_63
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• 2009

This paper is distribution utility to generation of analysis fault several cases on the ground of substation in a energy meter three phase current, voltage data measurement to fault type and characteristics. Mother wavelet transformation of suitable to method algorism from the distribution utility to generation of fault in image impedance etc several parameter for utility characteristics effective to probatory.

• 전기학회논문지
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• 제58권10호
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• pp.1855-1860
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• 2009

This paper caused a distribution utility to generation of analysis fault several cases on the ground of substation in a energy meter three phase current, voltage data measurement to fault type and characteristics. Mother wavelet transformation of suitable to method algorithm from the distribution utility to generation of fault in image impedance etc several parameter for utility characteristics effective to probatory fault point extraction.