• Current Optics and Photonics
• /
• v.5 no.1
• /
• pp.52-58
• /
• 2021

We show that a simple double-slit experimental setup can be used to measure the thickness of a transparent thin film. The phase difference between the light passing through one slit covered with photoresist film and that passing through the other slit without film was estimated using the simple Fraunhofer diffraction formula for a double slit. Our method gave error of a few percent or less for film thicknesses ranging from 0.7 to 1.7 ㎛, demonstrating that a laboratory double-slit experimental setup can be utilized in practical film-thickness measurements.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.10
• /
• pp.1094-1102
• /
• 2010

In this paper, the problem of electromagnetic transmission via slits in a cavity inside conducting screen of finite thickness is considered for the case that the TE(to the slit axis) polarized plane wave is incident on the slit in conducting screen. Using the method of moments the variations of the transmitted power through the slits are obtained and compared with those computed from an equivalent circuit constructed using an equivalent slit admittance. It is found that the effective slit width of a narrow slit, at resonance, becomes $1/{\pi}$ wavelengths independently of the actual slit width. The transmission resonance phenomena in the proposed geometry are explained in connection with the variations of an equivalent admittance of the slit in the cavity.

• Textile Coloration and Finishing
• /
• v.29 no.3
• /
• pp.139-147
• /
• 2017

In this study, interesting area of development is retro-reflective thin film and then slitting to form retro-reflective material to be conbined with other fibers to form having retro-reflective characteristics, which slitting yarn can then be to provide fabrics. Glass beads are microscopic spherical size with diameters ranging from several microns to several millimeters. Applying the effects of optical property, glass beads are consumed for road safety used to make traffic signs, safety clothing and others. Glass beads retro-reflective films can be turned into slit yarns through slitting yarn process. The slit yarns can be combined into textiles using diverse methods such as weaving to provide a fabric having retro-reflective characteristics. Lightness and Luminance was increased with decreasing of interval of slit yarn in the fabric. Also, the hue is shifted greenish and bluish with interval of slit yarn.

• Journal of the Optical Society of Korea
• /
• v.15 no.2
• /
• pp.196-201
• /
• 2011

Near-field properties of light emanated from a subwavelength double slit of finite length in a thin metal film, which is essential for understanding fundamental physical mechanisms for near-field optical beam manipulations and various potential nanophotonic device applications, is investigated by using a three-dimensional finite-difference time-domain method. Near-field intensity distribution along the propagation direction of light after passing through the slit has been obtained from the phase relation of transverse electric and magnetic fields and the wave impedance. It is found that the near field of emerged light from the both slits is evanescent, that is consistent with conventional surface plasmon localization near the metal surface. Due to the finite of the slit, the amplitude of this evanescent field does not monotonically approach to than of the infinite slit as the slit length increases, i.e. the near-field of the longer slit along the center line can be weaker than that of the shorter one.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.8 no.1
• /
• pp.166-175
• /
• 1996

In recent years, air-conditioning units designed with higher efficiency and more compactness are required due to emphasis on energy efficiency in home electrical appliances. This trend in the air-conditioning industries has accelerated the development of improved heat exchanger with a better performance in heat transfer aspects. In this study, experiments were performed to investigate the shape and configuration of fins affecting on the performance of the conventional fin-and-tube type heat exchanger equipped in a commercial air conditioners. The geometry similtude method was employed to measure the heat transfer coefficient and pressure drop. Experimental results show that this method is very useful to analyze the heat transfer characteristics of the fin-and-tube type heat exchanger. It is also found that the slit fin has better performance than the conventional fin type in the air conditioners. The present results indicate that heat transfer from the fin si influenced by the parameters such as the forming area of the slit fin, the type of interrupted surfaces like a louver or slit, slit patterns and slit raised direction, and it also affects the overall heat exchanger performance.

• Steel and Composite Structures
• /
• v.45 no.2
• /
• pp.249-261
• /
• 2022

This paper presents a numerical study to develop a guideline for estimating the plastic strength of elliptical steel slit damper with reasonable accuracy. The strut width increases from middle to end in elliptical steel slit damper and it is observed from the past studies that variation of the width is not considered for calculating the plastic strength of the damper. It is also noticed that the existing formulas for predicting plastic strength of this kind of damper may not be accurate and further refinement is warranted. Study is then carried on elliptical steel slit damper made of mild steel and having different geometry to find out equivalency of it with oblong steel slit damper having similar plastic strength. A few three-dimensional finite element models of seismic moment connection system with steel slit damper are developed and validated against past experiments for carrying the present study considering both the material nonlinearity as well as geometric nonlinearity. The results of the parametric studies have been compared with energy quantities and presented graphically to better understand the effects of different parameters on the system. Based on the pattern of parametric study results, closed-form semi-empirical algebraic expression of damper plastic strength is developed for elliptical steel slit damper which shows very good agreement with finite element analysis as well as experiments. This developed expression can now be used for elliptical steel slit damper in replacement with any type of damper in the design of moment connection.

• Steel and Composite Structures
• /
• v.50 no.6
• /
• pp.721-734
• /
• 2024

In this research, the efficiency of a metallic energy dissipation device for seismic retrofit of an existing structure is evaluated by cyclic loading test. The proposed device, which is called multi-slit damper, is made of weak and strong slit dampers connected in series. Its energy dissipation mechanism consists of two stages: (i) yielding of the weak-slit damper under minor earthquakes; (ii) restraint of further deformations of the weak slit damper and activation of the strong slit damper under major earthquakes using a gap mechanism. A reinforced concrete (RC) frame with characteristics similar to soft-first-story structures is tested under cyclic loading before and after retrofit using the proposed device. The details of the experimental study are described and the test is simulated in an available commercial software to validate the analytical model of the damper. To further verify the applicability of the damper, it is applied to an analysis model of a 4-story structure with soft first story and its seismic performance is evaluated before and after retrofit. The experimental and analysis results show that the multi-slit damper is effective in controlling seismic response of structures.

• Fashion & Textile Research Journal
• /
• v.15 no.2
• /
• pp.173-181
• /
• 2013

This research analyzed the expression trend about the slit which composes the open space by the visual concept and then introduced the imbedded aesthetic value in it. Based on it, this work aims at showing the evidence on the slit as a utilizing tool for various design applications and providing the basic materials in order to develop the creative design production in the fashion area in the future. Specifically, for the theoretical background in this research, the concept of slit and its chronological changes were reviewed through literature. For the empirical analysis on the slit, a total of 226 designs with its application were analyzed from collection pieces in the four major collections including Paris, Milan, New York, and London from 2006S/S to 2012S/S. As a result of analysis, types of slit appeared as a slash, opening, slit, or a mix of them. These were applied to many different items of clothing, and among which, one-piece or dress was adopted most for application. In regard to space form, perpendicularity was used most frequently. But other various forms like cross and geometrical pattern were also used as well as curve, oblique line and horizontality. As to the arrangement of slit, single type was most frequently used. However, in addition to it, other types were also applied, producing both the functionality and the decorative detail such as bilateral symmetry, free irregularity, and a combination of regular and repeated layout which makes an effect of single pattern. Aesthetic values imbedded in slit were revealed as functionality, sensuality, spatiality, and decorativeness.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.16 no.5
• /
• pp.69-77
• /
• 2017

This paper introduces an optical encoder using the reflection in the slit. The digital optical encoder is a sensor to generate a pulse according to the displacement. An optical encoder is composed of 3 parts: light source, slit plate and light-receiving element. In a conventional encoder, one slit produces one signal. The resolution of the digital optical encoder is determined by the number of slits in the encoder plate. The small slit size is most important among the factors that determine the resolution in a generic-type optical encoder. However, a small slit has low productivity and technical difficulties, so analog optical encoders have emerged as an alternative. Nonetheless, this alternative requires additional circuitry and equipment because of the noise and drafts in the analog signals. A new sensor is presented in this paper with a high resolution and a slit of the same size using the reflection in the slit. Then, the path of the light that passes through the slit ccording to the shape was analyzed, and some paths were expressed in the mathematical expressions. In addition, the optical paths were analyzed in the rectangular, octagonal, and circular encoders, and shown the obtained number of signals per slit by using them. Thus, we confirm that this method has the best performance in circle-shaped slits.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.14 no.1
• /
• pp.50-55
• /
• 2004

In this study, slit-tones by plane impinging jet are investigated experimentally over the whole subsonic flow range, especially at low speeds, in order to obtain the instability behaviour of impinging plane jet. Slit-tones are generated at low speeds associated with laminar shear layer instability as well as at high speeds associated with turbulent instability. Most of low-speed slit-tones are induced by symmetric mode instability unless the slit is not so wide, in which case antisymmetric modes are induced like edge-tones. It is found that the frequencies at low speeds ate controled by the unstable condition of the vortex at the nozzle exit and its pairings by which the frequencies are decreased by half. In the case of symmetric modes related with low-speed slit-tones, frequencies lower than those associated with one-step pairings are not found.