• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.1
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• pp.25-33
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• 2010

The matching condition at a perforated wall with vertical slits involves the permeability parameter, which can be calculated by two different methods. One expresses the permeability parameter in terms of energy dissipation coefficient and jet length at the perforated wall, being advantageous in that all the related variables are known, but it gives wrong result in the limit of long waves. The other expresses the permeability parameter in terms of friction coefficient and inertia coefficient, giving correct result from short to long waves, but the friction coefficient should be determined on the basis of a best fit between measured and predicted values of such hydrodynamic coefficients as reflection and transmission coefficients. In the present study, an empirical formula for the friction coefficient is proposed in terms of known variables, i.e., the porosity and thickness of the perforated wall and the water depth. This enables direct estimation of the friction coefficient without invoking a best fit procedure. To obtain the empirical formula, hydraulic experiments are carried out, the results of which are used along with other researchers' results. The proposed formula is used to predict the reflection and transmission coefficients of a curtain-wall-pile breakwater, the upper part of which is a curtain wall and the lower part consisting of a perforated wall with vertical slits. The concurrence between the experimental data and calculated results is good, verifying the appropriateness of the proposed formula.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.93-100
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• 2000

In this study, we used photoelastic coating method which is a kind of model test for examining the stress condition of rock masses around underground structures. Using this method, we could know adaptability and usefulness of photoelastic coating method for various shape of tunnel models. And, in spite of higher cross section efficiency, square shape model showed unstable status because of high stress concentration. So, we cut the slits at the each corner of tunnel, and we could make more stable stress condition by means of moving high stress concentration to rock mass.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.113-116
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• 2000

평행평판의 원면에 위치한 슬릿을 통하여, 슬릿의 바로 윗 부분에 도체 스트립이 있을 때 일어나는 전자기적 결합 현상에 대하여 살펴보았다. 슬릿의 폭이 파장에 비하여 매우 작을 때와 매우 클 때의 두 경우로 나누어서 기술하였다. 슬릿의 폭이 좁은 경우는 기존의 개구결합(aperture-coupled) 마이크로스트립 안테나에 해당되며 슬릿의 폭이 넓은 경우는 기존의 proximity-coupled 마이르로스트립 안테나에 해당된다. 본 연구의 결과는 기존의 마이크로스트립 안테나의 급전구조와 기존의 마이크로스트립 누설파 안테나의 급전구조 설계에 도움을 줄 것으로 생각된다.

• Proceedings of the Korean Society of Laser Processing Conference
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• 2005.06a
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• pp.102-103
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• 2005

Using THz time-domain spectroscopy, we study plasmonic band gaps in periodic metal arrays of slits. Femtosecnd machining system guarantees good quality sub millimeter structures for THz spectroscopy. Fabry-Perot effect enhances the transmission when the two resonances cross but does not alter the surface plasmon peak positions.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.11
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• pp.1988-1991
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• 2007

This study investigates the performances of the signaling techniques including differential signals for the power-distribution network(PDN)s with and without the slit, using a rigorous evaluation method 'Modal Analysis', validated by being compared to the FDTD simulation up to 5 GHz.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.9
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• pp.859-869
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• 2015

In this study, we analyze the problem of wedge cracks, which are geometrically unsymmetrical in transversely piezoelectric materials. A single concentrated antiplane mechanical load and inplane electrical load are applied at the point of the wedge surface, while one concentrated antiplane load is applied at the crack surface. The crack surfaces are considered as permeable thin slits, where both the normal component of electric displacement and the electric potential are assumed to be continuous across these slits. Using Mellin transform method, the problem is formulated and the Wiener-Hopf equation is derived. By solving the equation, the solution is obtained in a closed form. The intensity factors of the stress and the electric displacement are obtained for any crack length as well as inclined and wedge angles. Based on the results, the intensity factors are independent of the applied electric loads. The electric displacement intensity factor is always dependent on that of stress intensity factor, while the electric field intensity factor is zero. In addition, the energy release rate is computed. These solutions can be used as fundamental solutions which can be superposed to arbitrary electromechanical loadings.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.6 s.97
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• pp.632-643
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• 2005

This paper presents a folded stripline-fed small broadband disk-loaded monopole antenna with vertical ground plane. The bandwidth of the proposed antenna can be enhanced by electromagnetic coupling between the shorted rectangular disk and the probe with folded strip line. The measured impedance bandwidth of the proposed antenna is $37.6\%$ for $VSWR\leq2$ with the center frequency at 2.313 GHz and has the physical dimensions of only $11mm\times11mm\times11mm$ which corresponds to the electrical length of $0.085\lambda_0\times0.085\lambda_0\times0.085\lambda_0$. For improving the radiation pattern characteristics, rectangular slits are inserted in the vertical ground plane. Rectangular slits affect the currents distribution on the ground plane, so that the antenna radiation in the direction of the ground plane is reduced more than 3 dBi. Gain of the antenna is approximately 2.6 dBi within the bandwidth.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.4
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• pp.475-485
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• 2004

This paper was studied to investigate and compare the effects of inclined baffle plate on the turbulent flow characteristics of a gun-type gas burner through X-Y plane and Y-Z plane respectively by using X-probe from hot-wire anemometer system. For this purpose, two burner models with a cone-type baffle plate and a flat-type one respectively were used. The fast jet flow spurted from slits plays a role such as an air-curtain because it encircles rotational flow by swirl vanes and drives mixed main flow to axial direction regardless of the inclination of baffle plate. The inclined baffle plate causes axial mean velocity component and turbulent intensities etc. to be greatly concentrated towards the central part of a burner, and its effect especially appears in the range of about X/R=1.0-2.0. Also, it gives much larger size to axial mean velocity component and turbulent intensities etc formed near the slits in the range of X/R=1.4103. Especially the inclined baffle plate shifts more the Reynolds shear stress uw to the central region of a burner(Y/R=${\pm}$0.75) than the flat-type one, moreover it develops more strongly than uv.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.1 s.92
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• pp.84-91
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• 2005

In this papers, we study the characteristics of dual band PIFA(Planar Inverted F antenna) for handy phones using H-type silt in the antenna radiators. Slit types on the antenna radiator vary resonance mechanism of the antenna and affect reactance component of impedance for the antenna. Therefore the antennas resonate at the dual band(cellular -band, Korea-PCS band), the bandwidth, input impedance and radiation patterns of the proposed antenna is affected by the silt length on the radiators. In order to demonstrate the validity of the proposed theory, it is implementation the antenna of the 4 types. From results for the experiment of the implementation antenna, -5 dB bandwidth of return loss is content with the allocated bandwidth of Cellular and Korea-PCS system the gains of the antenna is about -8$\~$ - 1 dB, the radiation patterns for x-polarized or y-polarized are omnidirectional pattern. From above the results of this papers, it is conclude mobile phones antenna for handy phones using this papers results.

• Journal of the Korean Society of Costume
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• v.53 no.1
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• pp.1-15
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• 2003

This study as one of a series of systematic studies about dancing costumes will compare the costumes of the middle age with their normal style of dress. In brief, this study wants people to know about middle a9e dancing costumes and understand the culture in the middle ages. It was found that people's everyday clothes in the middle age such as Surcot. Surcot-ouvert, Pourpoint, Houppelande were used as dancing costumes. They were, however. changed from the public's clothes which were tight and long. Rather than wearing costume over others. dancers wore costumes which had slits on skirt or sleeves to increase motion. With the Wild Man of the Wood's which only nobles used for their dancing costumes. costumers highlighted the beauty of human body There were various costume materials used in the middle ages like silk. cotton fabrics, linen or brocade. These materials were used for Surcot and Pourpoint as dancing costumes. The naturalness of nature or geometric patterns also was expressed on the costumes. Further about those patterns, because the development of stained glass, vivid colors were used especially red, light green, blue etc. As for the hair styles used, dancers let their hair down and put a jeweled crown over their hair. In summation. dancers wore the same clothes that normal People did, but the costumes were different depending on social status and gender. The costumes of ordinary people's were based upon ordinary clothes that moved and emphasized the dynamic motion. On the other side, the court dancers' costumes were very fancy. symbolizing a measurement of nobles' from wealth and authority. as well as an expression of a sense of beauty, The main features of middle ages follows. : To emphasize vitality, there were long slits on the side of skirt. Hair decorations and jewels are more used than in the ancient age's. To hide a dancer's social status. they could use a mask. Wild Man of the Wood's was used for the body makeup. All these features of the dancing costumes must contribute to the progress of the dance in the middle age's.