• 한국초전도ㆍ저온공학회논문지
• /
• 제13권4호
• /
• pp.14-17
• /
• 2011

The evaluation of the electromechanical properties of HTS CC tapes is one of the foremost procedures to be done to ensure the applicability of superconducting wires to electric devices. A precise measurement of the stress and strain is important in deriving the mechanical properties under operating environment. Up to now, there is no standard test method yet for the electromechanical property evaluation of HTS tapes under self field and external magnetic field although there are already reports on the different devices used to evaluate these properties. Strain can be measured by adopting a strain gauge or a high resolution double extensometer. In this study, strain effect on $I_c$ in HTS CC tapes under magnetic fields was evaluated. Comparison of advantages and setback of strain measuring devices were discussed. In addition, a dual strain measurement system using both the SG and extensometer may be practical to lessen the burden in case one of the measuring devices does not work well.

• 한국전자파학회논문지
• /
• 제20권6호
• /
• pp.526-534
• /
• 2009

본 논문은 전력공급설비 중 변전설비에서 발생하는 극저주파에 의한 자계의 실태를 조사하고 자계의 특성에 관한 이해증진 방안을 제시하는데 그 목적이 있다. 본고에서는 수도권 25개 변전설비를 중심으로 변전소 주변과 감사실 내부의 자계 수준을 IEC에서 제시하는 CISPR의 측정 방법(IEC/TC106 PT 62110)에 의거하여 변전설비에서 발생하는 자계를 측정하였다. 아울러 전력설비와 관련된 자계의 속성에 대한 정확한 이해를 위해 전자계 인증표시제와 같은 객관적이고 신뢰성 높은 정책적 접근방안을 제시한다.

• Journal of Magnetics
• /
• 제22권1호
• /
• pp.43-48
• /
• 2017

In order to detect the current flowing through concealed conductor, this paper proposes a new method based on derivative method. Firstly, this paper analyzes the main peak characteristic of the derivative function of magnetic field generated by a current-carrying conductor, and a relationship between the current flowing through the conductor and the main peak of the derivative function is obtained and applied to calculate the current. Then, the method is applied to detect the conductor current flowing through grounding grids of substations. Finally, the numerical experimental and field experiment verified the feasibility and accuracy of the method, and the computing results show that the method can effectively measure the conductor current of grounding grids with low error, and the error is within 5 %.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
• /
• pp.515-518
• /
• 2003

The electrical current generated by heart creates not only electric potential but also a magnetic field. In this paper, we have designed the multiplexing data acquisition system for multichannel bio-magnetic signal measurement. The system consists of VXI rack which is organized MUX and AD board, Industrial rack which is mounted single board computer and DSP board. This system enable to realtime monitoring of multichannel data simultaneously. The number of channel could be increased simply added each module and firmware could be upgraded easily using host port interface of DSP.

• Progress in Superconductivity
• /
• 제13권1호
• /
• pp.1-6
• /
• 2011

Measurement of magnetic signals generated from electric activity of myocardium provides useful information for the functional diagnosis of heart diseases. Key technical component of the magnetocardiography (MCG) technology is SQUID. To measure MCG signals with high signal-to-noise ratio, sensitive SQUID magnetic field sensors are needed. Present magnetic field sensors based on Nb SQUIDs have field sensitivity good enough to measure most of MCG signals. However, for accurate measurement of fine signal pattern or detection of local atrial fibrillation signals, we may need higher field sensitivity. In addition to field sensitivity, economic aspect of the SQUID system is also important. To simplify the SQUID readout electronics, the output voltage or flux-to-voltage transfer of SQUID should be large enough so that direct measurement of SQUID output can be done using room-temperature preamplifiers. Double relaxation oscillation SQUID (DROS), having about 10 times larger flux-to-voltage transfers than those of DC-SQUIDs, was shown to be a good choice to make the electronics compact. For effective cancellation of external noise inside a thin economic shielded room, first-order axial gradiometer with high balance, simple structure and long-baseline is needed. We developed a technology to make the axial gradiometer compact using direct bonding of superconductive wires between pickup coil and input coil. Conventional insert has mechanical support to hold the gradiometer array, and the dewar neck has equal diameter with the dewar bottom. Boiling of the liquid He can generate mechanical vibrations in the gradiometer array due to mechanical connection structure. Elimination of the mechanical support, and direct mounting of the gradiometer array into the dewar bottom can reduce the dewar neck diameter, resulting in the reduction of liquid He consumption.

• 천문학논총
• /
• 제15권spc2호
• /
• pp.57-64
• /
• 2000

It is realized that the extraterrestrial matter is in ionized state, plasma, so the matter of this kind behaves as not expected because of its sensitiveness to electric and magnetic fields and its ability to carry electric currents. This kind of subtle change can be observed by an instrument for the magnetic field measurement, the magnetometer usually mounted on the rocket and the satellite, and based on the ground observatory. The magnetometer is a useful instrument for the spacecraft attitude control and the Earth's magnetic field measurements for the scientific purpose. In this paper, we present the preliminary design and the test results of the two onboard magnetometers of KARl's (Korea Aerospace Research Institute) sounding rocket, KSR­III, which will be launched during the period of 2001-02. The KSR-III magnetometers consist of the fluxgate magnetometer, MAG/AIM (Attitude Information Magnetometer) for acquiring the rocket flight attitude information, and of the search-coil magnetometer, MAG/SIM (Scientific Investigation Magnetometer) for the observation of the Earth's magnetic field fluctuations. With the MAG/AIM, the 3-axis attitude information can be acquired by the comparison of the resulting dc magnetic vector fields with the IGRF (International Geomagnetic Reference Field). The Earth's magnetic field fluctuations ranging from 10 to 1,000 Hz can also be observed with the MAG/SIM measurement.

• 한국초전도학회:학술대회논문집
• /
• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
• /
• pp.7-7
• /
• 2000

A high $T_c$ SQUID system is developed for the application to biological immunoassay. In this application, magnetic nanoparticles are used as magnetic markers to perform immunoassay, i.e., to detect binding reaction between an antigen and its antibody. The antibody is labeled with ${\gamma}-Fe_2O_3\;(or\;Fe_3O_4)$ nanoparticles, and the binding reaction can be magnetically detected by measuring the magnetic field from the nanoparticles. Design and set up of the system is described. The system consists of (1) SQUID magnetometer or gradiometer made of 30-deg. bicrystal junctions, (2) field and compensation coils to apply the magnetic field of about 1 mT, (3) special Dewar to realize a 2 mm-distance between the SQUID and the sample, (4) two layers of cylindrical shielding to reduce the extemal magnetic noise to about 1/100, and (5) an electric slider to move the sample with a speed of 10 mm/sec. The sensitivity of the system is studied in terms of detectable magnetic flux. For the measurement bandwidth from 0.2 Hz to 10 Hz, minimum-detectable amplitude of the magnetic flux is $0.8\;m\;{\Phi}_o$ and $0.25\;m{\Phi}_o$ for the magnetometer and the gradiometer, respectively, when the magnetic field of 1 mT is applied. The difference between them is due to the residual environmental noise, and the applied magnetic field does not increase the system noise. The corresponding weight of the magnetic markers is 1 ng and 310 pg, respectively. An experiment is also conducted to measure antigen-antibody reaction with the present system. It is shown that the sensitivity of the present system is 10 times better than that of the conventional method using an optical marker. A one order of magnitude improvement of sensitivity will be realized by the sophistication of the present system.

• 한국전자파학회논문지
• /
• 제11권7호
• /
• pp.1194-1203
• /
• 2000

1 mG부터 5 G까지 발생시킬 수 있는 소동물 실험율 60Hz 자계 발생장치를 설계하고 제작하였다. 동시에 많은 동물을 시험하기 위해서는 발생장치 내의 균일한 자계 분포 영역이 넓어야 하는데, 본 고에서는 SD-계쥐 약 50마리를 수용할수 있도록 하기 위해 소동물의 거주 공간을 장치 내부 1$\times$1$\times$1m3 크기로 하고 전체 발생장치의 크기는 1.8$\times$1.8$\times$1.8m3 입방형으로 설정하였다. 장치 내부의 자계 균일도를 검증하기 위해서 3차원 자계 계산 프로그램을 개발하였고, 이를 이용하여 거주 공간의 자계 분포가 가장 균일하게 되는 내.외곽코일의 최적 전류비 및 위치를 결정하였다. 또한 수치계산을 통한 임피던스에 근거하여 전원장치를 제작하였다. 제작된 자계 발생장치는 측정을 통하여 동물 거주 공간의 자계 최대치와 최소치의 차이가 3% 이내임을 확인할수 있었고 정밀한 소동물 자계 노출 시험용으로 사용 가능한 것으로 판단되었다.

• 한국자동차공학회논문집
• /
• 제17권5호
• /
• pp.74-83
• /
• 2009

Recently, usage of electric and electronic system for car increases rapidly. Consequently power monitoring supplied to the system is essential for management and controlling. Generally, battery status is monitored through measuring and diagnosing the current measurement method utilizing Hall Effect. Therefore, in this paper, we analysed magnetic field to develop the solution of DC current sensor using Hall Effect which is the core of design and development. By analysing the magnetic field by FEM using Maxwell 3D software, the location of the highest output current and stable part in the Hall IC sensor was shown. Also, the optimal core design of DC current sensor using parametric and Simplex method was presented. A car battery charge and discharge process dependant on time effect on the changing of magnetic field was simulated and compared to the result from the experiment result of actual vehicle.

• 조명전기설비학회논문지
• /
• 제21권10호
• /
• pp.40-45
• /
• 2007

뇌경보시스템은 낙뢰에 의한 인적 물적 피해를 예방하는 중요한 장치이다. 본 논문에서는 뇌경보시스템의 주요기능으로 뇌운의 이동과 활동을 감시할 수 있는 뇌방전 위치표정 알고리즘 및 회로에 대해 연구하였다. 뇌방전시 발생하는 전계성분은 whip 안테나와 공진주파수 300[kHz]의 협대역 공진증폭기로 검출한다. 자계파형 측정회로는 직교루프코일과 적분증폭기로 구성되며 주파수 대역은 5[kHz]$\sim$1.2[MHz]이다. 전계파형으로 뇌방전의 극성을 판별하고, 자계파형의 크기와 영점교차점에 의해 방향과 거리를 산출하여 뇌방전의 위치를 표정한다.