• Journal of Electrical Engineering and Technology
• /
• 제3권1호
• /
• pp.121-124
• /
• 2008

This paper presents the fabrication and field emission of carbon nanotube field emitters for a micro mass spectrometer. The carbon nanotube is an adequate material as a field emitter since it has good characteristics. We have successfully fabricated a diode field emitter and a triode field emitter. Each field emitter has been constructed using several micromachining processes and a thermal CVD process. In the case of the diode field emitter, to increase the electric field, the carbon nanotubes are selectively grown on the patterned nickel catalyst layer. The electron current of the diode field emitter is 73.2 ${\mu}A$ when the anode voltage is 1100V. That of the triode field emitter is 3.4 pA when the anode voltage is 1000V.

• Journal of Family Resource Management and Policy Review
• /
• 제13권3호
• /
• pp.247-280
• /
• 2009

The purpose of this study was to investigate the actual conditions of management of the healthy family field practicum and to present suggestions for its improvement. For this purpose, a preliminary investigation, survey, data analysis, interview as secondary source, and final data analysis were processed as research methods. The subjects of this study were the 42 supervisors in the centers which oversee the field practicum experience and the 12 supervisors in the centers which do not oversee the field practicum experience. 3 supervisors were interviewed to inquire about the reformation of field instruction in Healthy Family Support Centers. Analysis was made of the general characteristics of the above-mentioned 54 supervisors, including sex, age, academic background, certificate of qualification, class of position, and length of career related to the healthy family program. The environment of the field practice, such as the numbers of students supervised, time of field practice, practice hours, and so on, was examined in the centers which oversee the field practicum experience. The actual condition of operation investigated was divided into the preparatory stage, the early stage, the midterm stage, and the end stage. Research was conducted on the improvement of the field practicum, including the proper number of students supervised, adequate practice hours, interaction with universities or colleges, obstacles to the field practicum, and of practicum. The possibility and preparation of a further field practicum was conducted for 12 Healthy Family Support Centers, by inquiring about (a) the reasons for not overseeing the field practicum experience and (b) the needs of universities or colleges for a field practicum. The 54 supervisors surveyed suggested a particular need for improvement in human resources, the space of field instruction, system of field practicum, length of practice hours, orientation for students etc. This study investigated the actual conditions and suggested improvements of the field practicum in Healthy Family Support Centers. Therefore, its results should be meaningfully used to develop the Field Practicum for the Healthy Family and to conduct further studies.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• 제30권2호
• /
• pp.78-84
• /
• 2016

This paper is focused on the measurement and analysis of an atmospheric electric field which is caused by thunderclouds. The electric field due to thunderclouds changes very slowly. For this reason, the extremely low frequency E-field sensor needs to be used for measuring the atmospheric electric field strength. The balloon-carried E-field sensor system with the time constant of 1sec was designed and fabricated. The electric field sensor consists of $100mm{\times}100mm$ copper plate, active integrator, high pass and low pass filters and batteries. The measurements of atmospheric electric fields were made by the balloon-carried E-field sensor and radiosonde, which sends the data back to ground in real time. From the calibration experiments, the response sensitivity of the E-field sensor was 0.154mV/kV/m in the frequency range of less than 1kHz. As a result from the actual experiment of the atmospheric electric field, the electric field signals were observed from the altitude of about 2.5km. Also, as the altitude was increased, the detected electric field wave oscillated with the fluctuation of sensing plate. The proposed method seems suitable for measurements of atmospheric electric fields, because it is inexpensive, simple to use and launch.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 대한산업공학회/한국경영과학회 1994년도 춘계공동학술대회논문집; 창원대학교; 08월 09일 Apr. 1994
• /
• pp.375-384
• /
• 1994

Depending upon the eye and head movement, the visual field is often classified into three categories; stationary field, eye field and head field. To investigate the effect of background condition on the size of stationary field, an experiment was conducted, in which the subject was instructed to search a target with distinct orientations. In each trial, a single target was presented on the rear-view screen projected by the two-field tachistoscope, with the visual angle subtended 4.3.deg. vertically and horizontally. Density, meridian and subject showed a significant effect on stationary field at .alpha.=0.01, where density was inversely proportional to the size of stationary field. The size of the stationary field on horizontal axis was larger than that on vertical axis, and that on right and below meridian also larger than on left and lower meridian. The shape was found to be horizontally oriented oval and statistically asymmetric with respect to horizontal and vertical axes. The regression equation to predict stationary field on the given background condition was suggested. These results were expected to be used as a designing guideline when arranging displays and controls on panels such as automobile display panels, cockpits, etc. In addition, it can be inferred from the results that eye field and head field are also subjected to the influence of background condition.

• Journal of Korean Vacuum Science & Technology
• /
• 제3권1호
• /
• pp.10-15
• /
• 1999

Using micro-wells on the Mo substrate, we could obtain various tubular-volcano-types of free-standing diamond field emitters by depositing a diamond film detaching the film and turning the film upside down. The field emission characteristics of these structures were investigated as a function of size, shape and the number density of the tubular-volcano-type diamond field emitters. The field emission characteristics, especially the current density, were greatly enhanced with increasing the number density of the tubular-volcano-type diamond field emitters on the Mo substrate. Based on these results, we suggest that the reduction of the well size can give better field emission characteristics by the increase in the number density of the tubular-volcano-type diamond field emitters. Finally, we suggest the feasibility of fabricating a large-area field emission display using our patterned tubular-volcano-type free-standing diamond field emitters.

• The Bulletin of The Korean Astronomical Society
• /
• 제36권1호
• /
• pp.86.1-86.1
• /
• 2011

Most astrophysical systems are turbulent and magnetized. Magnetic field plays an important role in the dynamics of ISM and influence all of properties of astrophysical system. Information of magnetic field is very important to understand properties of astrophysical systems. For example, one way to obtain information of magnetic field is to use Rotation Measure. Mean strength of the magnetic field along the line of sight can be estimated from RM/DM. (where RM is rotation measure, DM is dispersion measure) For the estimation of magnetic field strength using RM/DM, the correlation between density and magnetic field is very important. When there is no correlation between density and magnetic field the relation gives exact mean magnetic field strength. But, if the correlation is positive, it overestimates the magnetic field strength, while if the correlation is negative, it underestimate the strength. We calculate correlation between density and magnetic field in compressible MHD turbulence.

• Bulletin of the Korean Mathematical Society
• /
• 제55권6호
• /
• pp.1823-1834
• /
• 2018

The position vector field x is the most elementary and natural geometric object on a Euclidean submanifold M. The position vector field plays very important roles in mathematics as well as in physics. Similarly, the tangential component $x^T$ of the position vector field is the most natural vector field tangent to the Euclidean submanifold M. We simply call the vector field $x^T$ the canonical vector field of the Euclidean submanifold M. In earlier articles [4,5,9,11,12], we investigated Euclidean submanifolds whose canonical vector fields are concurrent, concircular, torse-forming, conservative or incompressible. In this article we study Euclidean submanifolds with conformal canonical vector field. In particular, we characterize such submanifolds. Several applications are also given. In the last section we present three global results on complete Euclidean submanifolds with conformal canonical vector field.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• 제7권5호
• /
• pp.852-857
• /
• 2006

This paper presents a precision method to calculate the electric field density of mountain area using digital terrain elevation data(DTED). Generally we calculate the electric field density of a point adding a direct field density and horizontal reflection field density between two points. In this paper, we consider a vertical reflection field density from vertical surface near the wave propagation line between transmitter and receiver. The vertical reflection electric field have different propagation path and polarization from a horizontal reflection field. And the total electric field density adding horizontal field density and vertical reflection value is more accurate than a direct path electrical field density or direct field density adding a horizontal reflection field density.

• Proceedings of the IEEK Conference
• /
• 대한전자공학회 2003년도 신호처리소사이어티 추계학술대회 논문집
• /
• pp.359-362
• /
• 2003

In PDP(Plasma Display Panel), sub-field method is used to implement gray scale. Each sub-field has different periods. And Every gray level has information of which sub-field has to be displayed. This is called sub-field mapping. There are several sub-field mapping values in some gray levels. So, it is possible to select best choice in this paper, we propose new sub field mapping method using a fuzzy inference system to select best sub-field mapping values in accordance with input image and environment temperature. In order to implement fuzzy system, we used MATLAB fuzzy inference editor.

• Progress in Superconductivity and Cryogenics
• /
• 제17권3호
• /
• pp.23-27
• /
• 2015

Quadruple magnet is an essential component for the accelerator, and the field uniformity in the good field region reflects the quality of quadruple magnet. In this paper, the total magnetic field B was separated into the coil-induced magnetic field $B_s$ and the iron-induced magnetic field $B_c$ to explain why the total magnetic field B has some inhomogeneity. Using Fourier analysis, harmonic components of $B_s$, $B_c$ and B have been analyzed at good field region, respectively. The harmonics of multipole magnet and Fourier analysis are helpful to show the uniformity of magnetic field. Several geometries of yoke and coils were defined to analyze the effect on field uniformity of an HTS quadruple magnet. By the analysis, it was found that the sixth harmonics which is the main factor of field inhomogeneity can be reduced to zero. It means that the sixth harmonics of the magnetic field B can be removed by adjusting the geometry of the magnet pole and the position of coils. We expect that this result can effectively improve the uniformity of an HTS quadruple magnet.