• Steel and Composite Structures
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• v.26 no.3
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• pp.289-301
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• 2018

The rigid steel connections were suffered severe damage because of low rotational capacity during earthquakes. Hence, many investigations have been conducted on the connections of steel structures. As a solution, steel slit dampers were employed at the connections to prevent brittle failure of connections and damage of main structural members. Slit damper is a plate or a standard section with a number of slits in the web. The objective of this paper is to improve the seismic performance of steel slit dampers in the beam-to-column connection using finite element modeling. With reviewing the previous investigations, it is observed that slit dampers were commonly fractured in the end parts of the struts. This may be due to the low participation of struts middle parts in the energy dissipation. Thus, in the present study slit damper with elliptic slits is proposed in such a way that end parts of struts have more energy absorption area than struts middle parts. A parametric study is conducted to investigate the effects of geometric parameters of elliptic slit damper such as strut width, strut height and plate thickness on the seismic performance of the beam-to-column connection. The stress distribution is improved along the struts in the proposed slit damper with elliptic slits and the stress concentration is decreased in the end parts of struts. The average contributions of elliptic slit dampers, beam and other sections to the energy dissipation are about 97.19%, 2.12% and 0.69%, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.4
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• pp.399-402
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• 2016

We propose a thin electromagnetic wave absorber using varactor diodes combined with intentionally introduced multiple slits, which enables continuous sweep of an absorption frequency band throughout relatively wide frequencies. The absorption frequency range of conventional electrically tunable absorbers has been restricted by high capacitance of varactor diodes. In order to overcome the problem, we introduce parasitic capacitance and connect them with varactors in series, which reduces the total capacitance dramatically. As a result, we can raise the operating absorption frequency up to the X-band region. Moreover, we can also control the operating frequencies by modifying the number of slits with little change in an entire frequency sweep range. Good agreement between simulated and measured results show the validity of our proposal.

• Journal of the Korean Institute of Navigation
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• v.10 no.1
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• pp.81-100
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• 1986

Self-contained portable remote-indicating magnetic compass was designed and tested. Its sensing part consists of main scale disk of rotary encoder with photo-etched 180, oopaque slits and three pairs of light sources and detectors seperated by a transparent index scale, so that any angular deflection of main scale disk against the bowl may be detected optically. The outputs from the sensing part are transformed into digital ship's course indication by electronics unit which consists of operational amplifier, phase discriminator, up-down counter and counting starter circuit. The results from testign the above compass with turntable at variable rate of turn are as following : 1) The main scale disk deflection against the bowl can be detected without any disturbing influence to the freedom of its north-seeking function. 2) The digital indication resolution is found to be $\circ \pm$1 degree. 3) Misrepresenting indication can be avoided by ensuring dimension uniformity and arrangement accuracy of slits on main and index scale disks and by centering pivot in the encoder disk. 4) Indication resolution should be improved by modifying the signal processing and by doubling the number of slits on compass card. 5) Further study should be made on developing non-conductive compass liquid, analogue repeater driving system and more compact processing element.

• Journal of the Korean Vacuum Society
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• v.16 no.1
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• pp.46-51
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• 2007

The HFMX((High Flux Macromolecular X-ray crystallography) beamline at Pohang Accelerator Laboratory uses beams from a multi-pole wiggler. Two horizontal and vertical slits relevant to high heat-load are installed at its front-end. In order to treat high heat-load with reducing beam scattering, the horizontal slit has two Glidcop blocks with a grazing incidence angle of $10^{\circ}$ of a grazing-incidence knife-edge configuration. The blocks adjust the slit gap by being translated along guides by two actuating bars, respectively. Water flowing through holes, drilled along the actuating bars, cools the heat-load of both blocks. The vortical slit has the same structure as the horizontal slit except its installation direction with respect to the vacuum chamber and its grazing incidence angle. By virtue of a pair of blocks translating on guides, no alignment between both blocks is required and the installed slits show stable operating performance. The cooling performance of the two slits has been also shown to be acceptable. In this paper, the detailed explanation for the design of the two slits is presented and their operating performance is discussed.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3183-3186
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• 2007

Taylor-Couette flow may appear when the angular velocity is different between two concentric rotating cylinders. This kind of Taylor-vortex flow can be easily seen in lots of engineering problems. In general the geometries of rotating cylinders are generally complex in these cases. In this study, we investigated Taylor-Couette flow when the outer cylinder has the slit along the annulus. The radius ratio and aspect ratio of the experimental model used was 0.825 and 48, respectively. The depth of slits is 5mm and total 18 slits are azimuthally located along the inner wall of outer cylinder. We used PIV method to measure the flow and applied index matching method to resolve the complex geometry effect. The results show the model with slit has no stable wavy vortex region above Re=143.

• ETRI Journal
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• v.32 no.2
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• pp.312-318
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• 2010

A small reconfigurable patch antenna is proposed to achieve polarization diversity for digital multimedia broadcasting systems at 2.6 GHz. To obtain polarization diversity, a pair of on-slit PIN diodes is inserted in each diagonal of a cross-shaped patch. Thus, four PIN-diodes on these slits are utilized to change the connection of the slits and thus achieve polarization. Bias circuits for the diodes are allocated in the cutting corner of the cross-shaped patch to minimize the antenna size. The antenna produces left-hand circular polarization, right-hand circular polarization, or linear polarization, depending on the PIN-diode status. Analysis of circular polarization operation is explicated. Measurements show a gain of about 1.5 dB, a cross polarization of about -20 dB, and an axial ratio of about 2.5 dB.

• Journal of electromagnetic engineering and science
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• v.10 no.3
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• pp.127-131
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• 2010

In this paper, the problem of electromagnetic transmission via slits in a cavity inside a conducting screen of finite thickness has been considered in the case that the transverse electric(to the slit axis) polarized plane wave is incident on a slit. The problem is solved numerically by the method of moments and the results are compared with those obtained from an equivalent circuit suitable for a case in which the slit width is infinite and the structure is modified to the two partially overlapped conducting planes. It is observed that when the cavity is resonated, the effective slit width reaches its maximum value of $1/\pi$ wavelengths, irrespective of the actual slit width and the incidence angle. When the thickness of the conducting plane is much smaller than the wavelength, the numerical results for the effective slit width(or transmission width) agree well with those obtained from the equivalent circuit, even though the slit is as narrow as the thickness of the conducting plane.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.672-674
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• 2001

Axial magnetic field(AMF) type electrode can increase the interrupting capability of vacuum interrupters. But, this interrupting capability vary with design parameters such as shape of electrode, slits of contact, material of contact and so on. In this paper, shown arc characteristics of unipolar axial magnetic field type electrode for vacuum interrupter by design parameters such as shape of contact slits and diameter of contact. And, confirmed vacuum arc configuration by individual design parameter using high speed camera.

• Journal of the Optical Society of Korea
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• v.18 no.6
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• pp.783-787
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• 2014

This paper presents an improved vertical alignment nematic liquid crystal mode characterized by the protrusions or slits of the top substrate and additional stripe type common electrodes with polarity switching of the bottom substrate to improve multi-domain vertically aligned (MVA) and patterned vertically aligned (PVA) nematic modes. MVA and PVA modes have disadvantages such as an LC disclination in the vicinity of the middle region of electrodes between the top and bottom protrusions in MVA mode or the top and bottom slits in PVA mode. Therefore, the stripe type common electrode generating a horizontal electric field and the protrusion or slit producing some pretilt of liquid crystals (LCs) were used to improve the LC disclination, which influences the transmittance and response speed. The simulation results showed that the proposed VA mode has higher transmittance than the MVA and PVA modes. As a result, the proposed VA mode can improve the response speed and transmittance remarkably, which makes it useful for upgrading the LCD display quality.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.258-260
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• 2008

Developed halftone exposure technique was successfully applied to the fabrication of narrow transistor channels below $4\;{\mu}m$ with conventional photolithography method. Asymmetric slits concept of photo mask was applied to make channel lengths (L) shorter for thin film transistor's (TFT) high performance. These short channel TFTs verified better quality transistor characteristics.