• Journal of Energy Engineering
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• v.14 no.3 s.43
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• pp.194-202
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• 2005

The present study was analytically and experimentally carried out to predict the absorption characteristics on combined heat and mass transfer process in a vertical falling film of variable absorbers. Heat and mass transfer enhancements were analytically investigated. Effects of geometric parameters by insert device (spring) and corrugate, flow pattern on absorption performances has been also investigated. Especially, the optimal values of absorber geometry (ID=22.8mm, L=1150m) and kinetic variables (solution flow rate, flow pattern) for maximum absorption performance has been predicted by the numerical analysis. The maximum absorption performance in a numerical analysis and experiment was shown at the wavy-flow by insert device (spring).

• Journal of electromagnetic engineering and science
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• v.18 no.1
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• pp.7-12
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• 2018

This article proposes an ultrahigh frequency band radio frequency identification (RFID) tag antenna for drug runout management that can be used in hospitals. The RFID tag antenna is designed to function as a sensor that alerts drug runout when a drug inside a drip chamber is completely consumed but does not work when a drug remains inside a drop chamber. A previously proposed 915 MHz dipole antenna, is too large to be attached to the drip chamber of a feeding bag. Moreover, the length of the dipole (L) should be increased for conjugate matching with an RFID chip. Therefore, the dipole antenna is downsized so that it can be attached to the drip chamber through a fine meander line structure coupling with a corrugate meander line. A transparent cover is added to enhance the grip force between the designed antenna and the drip chamber and to enable detachment. The dimensions of the completed antenna structure attachable to a drip chamber are 32.59 mm (height) and 13.5 mm (width). The gain reduction due to the decreased antenna length is enhanced. The fabricated antenna shows an average omni-directional read range of 10.65 m on a horizontal plane and has the function of sensing the presence of a drug.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.679-682
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• 2002

Energy dissipations in a general PHE flow are the compounded effects of the piled corrugate geometries and its wall pressure and temperature distributions. In addition, although the exchangers are substantial pieces of engineering equipment, they are composed of a very large number of nominally identical and small geometrical elements. In the present numerical study, the three-dimensionally complicated energy dissipation fields and those wall-shape-induced flow destabilization are investigated in the cross-corrugated passages, which result in high energy transports with comparatively low pressure drop. We revealed the critical conditions as $Re=157.3 for the wall-shape-induced flow destabilization in a general PHE element by initial value method, or shooting method, and compare its value to that of analytical solution of plane Poiseille flow, two-dimensional grooved flow and so on. We also observed the detailed variation of flow field and energy transportation with changes in time and flow variables such as Reynolds number. Lastly, we considered the flow natural frequency, or Strouhal number, with variation of hydrodynamic conditions for the best use of active control, such as forced mass flow rate pulsative flow, to enhance energy transportation.

• Journal of the KSME
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• v.18 no.3
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• pp.18-24
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• 1978

열고환기에는 boiler와 같이 다량의 열 energy를 취급하는 것을 비롯하여 가정용 냉장고, 냉방기 기와 같이 비교적 적은 양의 열 energy를 취급하는것, 가종 고온 gas-gas 열교환기, 초전도송전 등의 초저온기기에 부속되는 저온열교환기 혹은 배열회수, 태양열이용을 위한 장치에 포함되는 열교환기등이 있으며, 그 종류와 내용에 있어서 다양하다. 따라서 새 형식의 열교환기 혹은 우수 한 전열특성을 갖는 표면, 형상을 갖는 전열관의 연구, 개발은 한층더 절실하게 요망된다. 최근주 목을 받고 있는 열교환기용전열관중에는 관축방향을 따라 표면을 파상으로 가공한 것(corrugate 식)과 축과 평형이 되게 만든 좁은 흠을 갖는 관(fluted tube)등이 있는데 이들에 있어서는 다같 이 표면의 요철에 의한 면부근의 난동을 촉진시켜서 우수한 대류열전달의 특성을 갖도록 하고 있다. 한편 응축과 비등등의 상변화를 동반하는 열전달에 대해서는 세구, 기공질금속층, 세공등을 갖는 면에 관해서 새로운 관심이 집중되고 있다. 이 후자의 전열면은 유축열전달에서는 평활면보 다 약10배의 높은 열전달율을 가지며 불등열전달에서는 벽면과 액의 온도차는 평활면의 경우보다 약1/5의 값을 갖는다. 동시에 한계열유속은 5활이상으로 증가시킬 수 있음이 알려져 있다. 따라서 본론에서는 후자의 전열면중에서 최근에 알려진 비약적으로 높은 전열성능을 갖는 전열면에 관해 서 소개하기로 한다.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.10a
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• pp.41-41
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• 2011

국제해사기구(IMO)에서2016년에 건조되는 선박부터 Tier III 규제를 예고하고 있다. 이 규 제를 만족하기 위하여 엔진 전처리 기술 및 후처리 기술 개발과 실증 연구가 활발히 진행되고 있다. 이중 SCR(Selective Catalytic Reduction) 반응을 이용한 질소산화물 저감기술이 80% 이상의 Tier III NOx 규제치를 만족할 수 있는 유일한 기술이다. 육상 플랜트에서 실증과 검증이 확보된 SCR 기술의 선박 엔진에 대한 적용을 위해서는 선박의 급격한 운전조건 변화와 엔진에 의한 저주파 진동에 대한 촉매 내구성 확보가 중요하다. 본 연구에서 기공 분포면에서 마이크로 기공보다는 메죠 및 매크로 기공쪽으로 구조를 개선함으로써 촉매 사용시 우려되는 배기가스중의 Soot 또는 2차 합성물질에 의한 촉매기공 막힘을 최대한 방지한 상용 SCR 촉매를 개발하였다. 또한 촉매에 대한 내구성 실증을 위하여 현재 운항 선박(한진피츠버그호)에 장착하여 실증 실험을 수행하였다. 기존 corrugate 타입의 촉매보다 40% 정도의 부피 감소와 차압 감소를 달성하였고 이로 인하여 선박내 제한된 공간에 효율적으로 SCR 시스템 설치가 가능할 것으로 생각된다. 그리고 본 연구에서는 가이드 베인 설치 없이 유동 균일화를 달성하여 반응기 전체의 크기 축소가 가능하다. 이는 추가적인 비용 및 압력 손실 저감, 유지 보수 공간 확보 등의 장점이 있다.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.2
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• pp.31-38
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• 2008

A column test was performed far a new-type column with a quasi static test. An internally confined hollow reinforced concrete column with a corrugated steel tube (ICH RC-CT column) was tested to evaluate its seismic performance. And also, a general solid RC column was tested fur the comparison. The test was performed as planned drift levels. The lateral displacements and the lateral loads of column specimens were measured during tests. From the test results, the ICH RC-CT column showed smaller energy absorbing capacity than a solid RC column but showed the almost equal energy ductility and equivalent viscous damping ratio to those of the solid RC column.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.6
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• pp.811-818
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• 2013

In this paper, we have designed the elliptical dual offset gregorian antenna which can use Ka band earth station antennas in the fixed-satellite service. The structure of antenna is increasing the antenna gain by decreasing blockage areas and decreasing wind effects by shortening height of the antenna. The corrugate horn antenna for this antenna has symmetric radiation patterns and low side lobe levels that can meet ITU-R envelope. The distribution of electric field on a aperture of main reflector is calculated by an ray-tracing method that use the radiation pattern of the feed horn. The final geometric of antena is decided by choosing the distribution that comply with antenna requirement. The FEKO analysed electrical performance of this antenna. The fabricated antenna has 45.0dBi(@30.0GHz)/41.7dBi(@20.2GHz), high efficiency and low side lobe level that meet ITU-R S. 580-6 envelope.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.3 s.55
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• pp.145-154
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• 2009

Steel-Concrete Composite Deck with I-beam welded is lighter and easier to construct than conventional in situ reinforced concrete slabs due to the I-beam embedded in the corrugated slab. For the calculation of effective flexural rigidity of conventional reinforced concrete structures, methods suggested in Design Standard for Roads and Bridges and ACI have been used. In this paper, the calculation methods were applied to steel-concrete composite deck with I-beam welded and then results of the steel-concrete composite deck were compared with those of reinforced concrete slabs. In addition, applicability of the methods to steel-concrete composite deck with I-beam welded was estimated. In order to compare the effective flexural rigidity, flexural experiments were conducted. Fifteen slabs were built and the variables considered in the experiments were studs, length of the slab, shape of the section and connecting methods.

• Journal of Korean Society of Steel Construction
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• v.18 no.1
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• pp.81-91
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• 2006

The corrugated web is a plate that was manufactured with a corrugated shape. It is widely used in bridges, buildings, and culverts. A girder with a corrugated web can be crippled by local, in-plane compressive loads. Due to its high out-of-plane strength, however, a stiffener is usually not needed in trapezoidally corrugated plates, and the corrugated profile of the web can change the boundary condition of the edge load. Some researchers have studied the strength of the partial-edge loading of the trapezoidally corrugated web, but they have not considered the profile of corrugation in their studies. This paper investigates the influence of the corrugate profile. A parametric study was conducted on the shape parameter using the finite-element method. In this parametric study, the relationship between the corrugated shape and the partial-edge strength was also investigated by dividing the partial-edge strength into the web capacity and the flange capacity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.6
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• pp.640-646
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• 2008

Design procedure of corrugated horn antenna for the mm-wave frequency range is presented, and hybrid condition in horn is calculated. In this paper, corrugate profiles of horn which satisfy both transition to balanced hybrid condition and fabrication possibility under the mm-wave short wavelength are obtained. Electromagnetic fields inside horn and corrugation are derived by the cylindrical mode theory. Propagation characteristics in the horn are calculated by the mode impedance matching method with boundary conditions, and radiation fields are obtained by the Kirchhoff-Hyugen principle to the horn aperture fields. A mm-wave corrugated horn antenna which operates on $85{\sim}115GHz$ is fabricated by electric forming method. Measurements show that VSWR is under 1.3:1 over whole band and the half power beamwidth on radiation pattern 9.2, 9.16 and 9.02 degree on 85, 100 and 110 GHz are agree well with theoretical calculation.