• Journal of Astronomy and Space Sciences
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• v.29 no.2
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• pp.233-244
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• 2012

The Korea Astronomy and Space Science Institute and the Department of Astronomy at the University of Texas at Austin are developing a near infrared wide-band high resolution spectrograph, immersion grating infrared spectrometer (IGRINS). The compact white-pupil design of the instrument optics uses seven cryogenic mirrors, including three aspherical off-axis collimators and four flat fold mirrors. In this study, we introduce the optomechanical mount designs of three off-axis collimating mirrors and one flat slit-viewer fold mirror. Two of the off-axis collimators are serving as H and K-band pupil transfer mirrors, and are designed as system alignment compensators in combination with the H2RG focal plane array detectors in each channel. For this reason, the mount designs include tip-tilt and parallel translation adjustment mechanisms to properly perform the precision alignment function. This means that the off-axis mirrors' optomechanical mount designs are among the most sensitive tasks in all IGRINS system hardware. The other flat fold mirror is designed within its very limitedly allowed work space. This slit-viewer fold mirror is mounted with its own version of the six-point kinematic optics mount. The design work consists of a computer-aided 3D modeling and finite element analysis (FEA) technique to optimize the structural stability and the thermal behavior of the mount models. From the structural and thermal FEA studies, we conclude that the four IGRINS mirror mounts are well designed to meet all optical stability tolerances and system thermal requirements.

• Korean Journal of Optics and Photonics
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• v.5 no.3
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• pp.364-371
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• 1994

Real-time MTF measuring system for testing microlens arrays with a linear CCD array is developed. The spread function of slit image that is relayed and magnified by a microscopic object lens can be measured at several times in a second. The signal uniformity and MTF of CCD is also calibrated. The experimental result of micro lens arrays developed for contact image sensor is presented.sented.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.696-697
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• 2015

In this paper, the shape of the slit to provide a view of the sensor in such a manner as to encode the rotor position information using a single sensor for studies of economic rotor position and speed detection method for electric motor drive has a special electronic commutator bar-and proposes a robust encoder can produce a rotor position information for each of the woman, and reads out the location information by using the position detection method of the proposed new method compared to traditional DSP Capture function of incremental encoder that its validity was verified through experiments.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.433-434
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• 1988

Rectangular microstrip antenna with parasitic element is analyzed. Radiation admittance and equivalent circuit parameters between rectangular microstrip antenna and parasitic element are obtained by using equivalent ${\pi}$-network parameters of the slit in the wall of the parallel plate waveguide filled with homogeneous dielectric. The return loss is calculated and measured as a function of frequency with gap width 0.5mm between the patch and parasitic element. The experimental results are in fairly agreement with calculated values.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.2 no.2
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• pp.55-58
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• 1988

Electron mobility which is a basic parameter to represent gas state, is calculated for 38mm 20W fluorescent lamp. 2 Electron Group Model is u&ed for electron distribution function. To prove this result electron mobility in 38mm 20W fluorescent lamp is measured at various wall temperatures. In order to obtain electric field strength of positive column, the sum of anode and cathode fall voltages assumed to be 15(VJ) and dual slit is used to measure positive column length. The measured and calculated result is potted under $10-80^{\circ}C$ wall temperature.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.6
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• pp.922-928
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• 2006

An absolute absorption cross section of benzene was measured with a spectrometer system including a mono-chrometer and a grating in the wavelength region of $240{\sim}280nm$ under the atmospheric pressure and room temperature in the laboratory. A certificated reference benzene gas ($98{\mu}mol/mol$ in $N_2$) was used to measure its absorption cross section. A 710 mm cell with a quartz window and a 150 W Xe arc lamp were employed. The magnitude of absorption cross section of $1.41{\times}10^{-18}cm^2$ was lower than that of the reference spectra ($2.5{\times}10^{-18}cm^2$) of high resolution spectrometer, Total measurement uncertainty was estimated to be 4.0%.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1573-1576
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• 2003

The quality of bundles is closely related with the apparent thickness. Especially the variation of apparent thickness of bundle determines the qualify of the plane structure made or the bundle such as surface evenness, pore size, and the shape of air-gap, etc.,. This study is dealing with the development of a new measuring system of the thickness of bundle or cross-section by determining the size of the shadow of the object covered by a laser slit beam. Also the measured signal is characterized in terms of the correlogram, the irregularity in wavelength. The correlogram for the irregularity of several sample types could be represented by a sinusoidal function with exponentially decaying amplitude. Moreover, influence of the measuring speed on the signal and the characteristic differences according to the different types of bundle are investigated.

• Korean Institute of Interior Design Journal
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• v.18 no.3
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• pp.39-46
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• 2009

The purpose of this study is to analyze the meaning of 'dis-joint' in the works of Louis I. Kahn. Kahn tried to realize his main architectural thoughts of 'what it wants to be' and 'how it was done' through his whole life. The concept of 'dis-joint' had been developed to visualize his architectural thoughts. Kahn used' dis-joint' to show and emphasize the structural system for the raison d'etre of building. Kahn's 'dis-joint' can be categorized as 'spacing', 'butt', 'slit' and 'protrusion'. Kahn used this kind of unusual way of joint beyond simple exposure to stress the existence of element, part and building itself. Through variable combination usage of 'dis-joint', Kahn can realize his architectural thoughts into building in a concrete way. The efficiency and function of joint is not the main issue in his works. 'Dis-joint' was the concrete tool to show the tectonic of architecture and construction process to enhance its presence. Therefore 'dis-joint' of Kahn's architecture is not a joint only to combine building parts but a concrete mean to realize his thoughts in a corporeal way. These facts insinuate that Kahn's architectural philosophy is based on the thoughts of tectonic and its realization.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.2
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• pp.77-82
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• 2018

Electromagnetic wave transmission through periodic metal-insulator-metal(MIM) waveguides as a function of plate thickness has not been extensively studied at various terahertz frequencies. In this paper, we investigate the transmittances through gold MIM slits when a normally incident wave with parallel polarization is considered at several terahertz frequencies. In addition, the results are compared to the case of a perfect electric conductor, and the differences are discussed.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.4
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• pp.354-361
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• 2004

This Paper describes a crack scattering model for SH wave based on the boundary integral equation(BIE) method, where the fundamental unknown is crack opening displacement(COD). When a time harmonic plane wave was incident on a 2-D isolated crack (slit) of width 2a, the COD distributions were numerically calculated as a function of ka. The calculated COD agreed well with results obtained with other methods. The far-field scattering amplitude, which completely characterizes the flaw response, was calculated in two ways. The Kirchhoff approximation and the BIE-COD exact formulation were compared in terms of incidence angle and frequency ka in a pulse-echo mode. Maximum response was obtained for both methods at the specular reflection direction. Away from the specular direction, the Kirchhoff approximation becomes less accurate. The time domain crack response was also calculated using a band-limited spectrum of center frequency 10 MHz. At oblique incidence to the crack both methods show the existence of an antisymmetric flash points occurring from the crack edge. The Kirchhoff approximation provides an exact time interval between flash points, although it unrealistically gives the same amplitude.