• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.897-903
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• 2004

Waste lime used in this study is producted as a by-product in the manufacturing process of making $Na_2CO_3$ from local chemical factory in Incheon. Currently about 320 millon tons of waste lime are accumulated and annually 100,000 tons are producted. Reuse of waste lime mixed with soil for banking and backfill materia in civil works was analysed in this study. This study was Carried out to investigate the geotechnical and environmental characteristics on field application. Field investigations were conducted on the road construction site in Incheon. This study presents the results of the engineering characteristics in field test and the leaching characteristic of waste lime in laboratory column tests. Countermeasure for reduction of environmental effects was suggested from the test results.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 1998년도 유체기계 연구개발 발표회 논문집
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• pp.97-104
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• 1998

The objective of this study is to understand the generation mechanism of sound and to develop a prediction method for the unsteady flow field and the acoustic pressure field of a centrifugal fan. Lowson's method is used to predict the acoustic pressure in a free field. A DVM(discrete vortex method) is used to model the centrifugal fan and to calculate the flow field. In order to compare the experimental data, a centrifugal fan and wedge introduced by Weidemann are used in the numerical calculation and the results are compared with the experimental data.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.576-580
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• 2000

This paper describes about the field test of IGBT VVVF inverter for the propulsion system. The 1650kV class IGBT VVVF inverter has been developed. Therefore the field test is performed in SMG 6 Line to confirm its the reliability and performance. The train consists of 4M4T and the electrical equipment for field test are as follows : VVVF inverter 4 sets 16 traction motors and 3 SIVs The propulsion system which have the excellent acceleration/deceleration and the jerk chracteristics as well as starting ability on slope are taken through the field test.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.306-313
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• 2005

For seismic response analysis of rockfill dam, dynamic material properties, by field test, are needed. Density and elastic wave profiles have to be known to get an information of the material properties of structure. In this study, various field tests are applied to the example of rockfill dam to get an information of dynamic material properties and seismic safety is evaluated by seismic response analysis with the result of field tests.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 추계학술대회 논문집
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• pp.183-186
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• 1998

Axial magnetic field generated by special electrode construction in vacuum interrupters is used to extinguish electric plasma arcs. This investigation by FDM should prove to what extent the magnetic field might influence on the arc expansion. The calculated results show that the stronger magnetic field induced the lesser radius of arc plasma. This study will help to offer good data in design of vacuum interrupters.

• 충청수학회지
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• 제26권3호
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• pp.517-523
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• 2013

In this paper we study the infiniteness of Hilbert 3-class field tower of real cubic function fields over $\mathbb{F}_q(T)$, where $q{\equiv}1$ mod 3. We also give various examples of real cubic function fields whose Hilbert 3-class field tower is infinite.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.436-452
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• 2008

In this study, the settlement prediction method based on field monitoring data under preloading improvement with ramp loading is developed. Settlement behavior can be predicted with field monitored settlement throughout the entire preloading process including ramp loading followed by constant loading. The developed method is verified by comparing its predicted results with results from physical model tests and field monitoring data.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.281-281
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• 2014

The field emission properties of GaN are reported in the present study. To be a good field emitter, it requires a low work function, high aspect ratio, and strong mechanical stability. In the case of GaN, it has a quite low work function (4.1eV) and strong chemical/mechanical/thermal stabilities. However, so far, it was difficult to fabricate vertical GaN nanostructures with a high aspect ratio. In this study, we successfully achieved vertically well aligned GaN nanostructures with chemical vapor-phase etching methods [1] (Fig. 1). In this method, we chemically etched the GaN film using hydrogen chloride and ammonia gases at high temperature around $900^{\circ}C$. This process effectively forms vertical nanostructures without patterning procedure. This favorable shape of GaN nanostructures for electron emitting results in excellent field emission properties such as a low turn-on field and long term stability. In addition, we observed a uniform fluorescence image from a phosphor film attached at the anode part. The turn-on field for the GaN nanostructures is found to be about $0.8V/{\mu}m$ at current density of $20{\mu}A$/cm^2. This value is even lower than that of typical carbon nanotubes ($1V/{\mu}m$). Moreover, threshold field is $1.8V/{\mu}m$ at current density of $1mA$/cm^2. The GaN nanostructures achieved a high current density within a small applied field range. We believe that our chemically etched vertical nanostructures are the promising structures for various field emitting devices.

• 전기의세계
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• 제23권2호
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• pp.55-61
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• 1974

Nature of magnetic creep phenomena in low coercive force films(Ni 80%-Fe 20%) in form of narrow channels imbedded in high coercive force films is studied in this work. Aluminium is evaporated on the hot glass substrate and eched free in the shape of narrow channels by photoetoetching method. then, Permalloy(Ni 80%, Fe 20%) is deposited on these Aluminium substrate under the uniform field of 30(Oe) to introduce anisotropy. Permalloy film on Al has a high coercive force and one on the substrate devoid of Al has how coercive force. Magnetic revers domain which is introduced at the end of channel grows under the a.c field in hard axis direction, in spite of very weak d.c field in easy axis direction. This creeping is investigated as a function of external fields and channel widths. Permalloy film thickness is 500.angs.-900.angs. and channel widths are 40, 51, 65, 81, 115.mu. respectively. Creeping increases as external field increases while it decreases with channel width decrease. Creep velocity in channels depends on the a.c field along hard axis, d.c field along easy axis and channel widths and its range is 1-10cm/sec in this experiment. From study of dependence of creep velocity on channel width, it can be concluded that creep velocity is expressed in form of v=v$_{0}$ exp .alpha.(H-H$_{0}$) where .alpha. is a function of a.c field along hard axis and H is driving d.c field along easy axis, H$_{0}$ is not a coercive force of film as usuall expected but the d.c threshold field along easy axis which is a function of channel width. This characteristic is also confirmed by the study of dependence of creep velocity upon easy axis field strength. Value of .alpha. obtained is 1.3-2.3cm/sec We depending upon film charactor, hard axis field strength and frequency.uency.

• KIEAE Journal
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• 제7권6호
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• pp.37-43
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• 2007

Discomfort glare is an important factor influencing appraisal for lighting environment. Unified Glare Rating (UGR) which has been proposed by CIE is one of the formula for evaluating discomfort glare. Position index is an important factor in the UGR formula. Position index was proposed by Guth in 1949. It has been used until present limiting upper visual field. Lower visual field has different sensation of brightness in comparing with upper visual field. Therefore, it is necessary to propose position index about lower visual field. The objective of this study is to investigate the brightness sensation in upper and lower visual field. First, the visual field was measured on the self-made Glare Tester. Second, luminance of the Borderline between Comfort and Discomfort (BCD) was measured on the glare Tester. Circular sources of brightness were located at various angular distances from the line of vision along five meridians, $0^{\circ}$, $45{\circ}$, $90{\circ}$, $-45{\circ}$, $-90{\circ}$. The size of the glare source is 0.0011sr. The luminance of the surrounding field, which extended over the entire visual field, was maintained $34ccd/m^2$. Ten subjects aged from 25 to 29 were participated in the experiment. The results show that the luminance of BCD on the line of vision is $4337cd/m^2$ and the glare sensation of the lower visual field is more sensitive than the upper visual field.