• 대한기계학회논문집B
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• 제31권6호
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• pp.547-557
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• 2007

This study was conducted to investigate the flow and combustion characteristic of the experimental burner which was manufactured for the reflection of the oven and broil burner features. As slot shape, spacing between slots, and slot arrangement of the exit area which emits the mixing gas are different in case of oven burners and broil turners, the purpose of this study is to know the affection of the flame interaction and combustion characteristic according to the change of shape factors such as slot shape, slot arrangement, and slot-to-slot spacing. With no relation of the slot shape, as the spacing between slots became narrow, the occurrence of a lift-flame was delayed. So the combustion was possible in the leaner region, but the appearance of yellow-tip became a little fast. Slit slot port had the broadest operating range among the other slot shapes. Specially, from the side of lift-flame, as the jet that spreads downstream in the longitudinal slot was nearly circular just a few slot lengths away from the orifice, slot-to-slot spacing of the Slit port was closer than the other ports. These results could be expected through the computer numerical method and had a good agreement. As the spacing between slots increased, in case of Slit and Mix port, NOx emission rate was constant or decreased, but the NOx emission of Hole port was increased. CO emission rate of Slit and Hole port was increased as the slot-to-slot spacing was broadened.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2006년도 추계학술대회 논문집
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• pp.55-58
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• 2006

The flow characteristics in a confined slot jet impinging on a flat plate were investigated by using cinematic Particle Image Velocimetry technique. The three different kinds of confined slot were applied to the jet with a view to evaluating the shape effect and the jet Reynolds number was varied from 250 to 1000 for a fixed jet-to-plate spacing of H/W=5. It was found that the vortex structures in the shear layer are developed with increase of Reynolds number and that the jet becomes unsteady by the interaction of vortex pairs between 500 and 750 of Reynolds number. Finally, the slot shape was proved to be related with the generation timing of vortex pair and the temporal vortex structure.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2798-2803
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• 2008

The confined slot air jet impinging normally on a moving flat surface has been investigated numerically by using commercial CFD code Ansys CFX-V11. Turbulent flows are modeled using k-w turbulence model. Two-dimensional turbulent flow is considered. Calculations were conducted for a nozzle-to-plate spacing of eight slot nozzle width, at three Reynolds number(Re=4500, 6700 and 10,000) and four surface-to-velocity ratios i.e. 0, 0.25, 0.5 and 1. Results are compared against corresponding cases for heat transfer from a stationary plate. Local Nusselt number is calculated under constant wall temperature condition. The analysis reveals that the average Nusselt number increases considerably with the jet exit Reynolds number, but decrease with the plate velocity.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(1)
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• pp.455-458
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• 2002

Design methods are presented for an X-band traveling-wave slot array realized on a rectangular waveguide. An array of 21 longitudinal slots is realized on the broad wall of a rectangular waveguide. The squint of the antenna main beam is adjusted using the element spacing and the waveguide broad wall dimension. The excitation of the array is controlled by the slot offset from the waveguide center line Multiple I-plane steps are placed around last slot elements so that the second-order beam due to tile reflected wave Is minimized A waveguide-to-coaxial adapter Is designed for feeding the array antenna from a coaxial system. Results of the design show an outstanding performance of the antenna 17.1 dB gain. 36"beam 1111, and -21 dB maximum sidelobe level.evel.

• 한국가시화정보학회지
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• 제3권2호
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• pp.57-62
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• 2005

The flow characteristics in a confined slot jet impinging on a flat plate were investigated by using cinematic Particle Image Velocimetry technique. The jet Reynolds number was varied from 250 to 1000 for a fixed jet-to-plate spacing of H/W=5. We found that the vortical structures in the shear layer are developed with increase of Reynolds number and that the jet becomes unsteady by the interaction of vortex pairs between 500 and 750 of Reynolds number. Vortical structures and their temporal evolution are verified by using proper orthogonal decomposition.

• 한국군사과학기술학회지
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• 제25권2호
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• pp.135-143
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• 2022

In this paper, the compact waveguide slot array antenna for interferometric radar altimeter is proposed. The proposed antenna structure consist of corrugation structure which is applied between each channel to improve isolation, three-channel waveguide slot array antenna and feeder. In addition, to reduce the occurrence of phase ambiguity, the baseline spacing of the three-channel antenna is analyzed and the results are applied to the design. For compact design, reduced height and SMP connector structure are used and the dip brazing method which is the conjugation method after dipping to flux is used for the fabrication of the lightweight antenna. The measurement result of the proposed antenna shows less than 1.41 : 1 (VSWR) and 48.3 dBc (isolation). The antenna gain is higher than 20.2 dBi and the side lobe levels are lower than 18.8 dB (vertical plane) and 10.0 dB (horizontal plane).

• 센서학회지
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• 제31권2호
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• pp.107-114
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• 2022

The effects of ring radius and coupling spacing on the free spectral range (FSR), full width at half maximum (FWHM), quality factor, and sensitivity of single-channel and add-drop channel slot ring resonators were systematically investigated using FIMMPROP and PICWAVE numerical software. The single-channel ring resonator exhibited better characteristics, namely, a wider FSR and narrower FWHM compared with the add-drop structure; thus, it was evaluated to be more suitable for biochemical sensors. The FSR, FWHM, quality factor, and sensitivity for a single channel ring resonator with a radius of 59.4 ㎛ and coupling gap of 0.5 ㎛ were 2.4 nm, 0.087 nm, 17677, and 550 [nm/RIU], respectively.

• 한국인터넷방송통신학회논문지
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• 제24권1호
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• pp.103-107
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• 2024

본 논문은 직사각형 슬롯과 스트립 도체를 이용한 삼각 패치 안테나에 대한 연구이다. 직사각형 슬롯을 갖는 삼각 패치 안테나 특성을 확인하기 위해 슬롯 길이와 간격을 조정하였고, 복사 패치의 형태를 삼각형, 직사각형, 육각형으로 변화시켜 임피던스 매칭을 하였다. 안테나 파라미터 특성으로 확인하기 위해 HFSS 시뮬레이터를 이용하였다. 제안한 안테나 크기는 26 mm × 26 mm이다. 제안한 안테나에서 시뮬레이션을 통해 얻게 된 VSWR 2이하인 주파수 대역은 5.27 ~ 6.24 GHz이며, 주파수 대역폭은 970 MHz이다. 실제로 제작한 안테나의 주파수 대역은 5.24 ~ 6.38 GHz이고, 주파수 대역폭은 1140 MHz이다. 복사패턴을 확인한 주파수는 5.855 GHz, 5.890 GHz, 5.925 GHz이다. 최대 이득은 5.01 dBi이다. 모든 복사패턴에서 지향성 특징을 갖는 것을 확인할 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.274-279
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• 2001

An experimental investigation of heat transfer characteristics at the surface of two-dimensional protruding heated blocks using confined impinging multiple slot jets has been performed. The effects of jet-to-jet distances(S=16B, 24B), dimensionless nozzle-to-block distances(H/B=2, 6) and jet Reynolds numbers(Re=2000, 3900, 5800, 7800) on the local and average heat transfer coefficients have been examined with five isothermally heated blocks at streamwise block spacing(p/w=1). To clarify local heat transfer characteristics, naphthalene sublimation technique was used. From the results, it was found that the local and average heat transfer of heated blocks increases with decreasing jet-to-jet distance and increasing jet Reynolds number. Measurements of local heat transfer coefficients have given an indication of the nature of the interaction between jets and of the uniformity of heat transfer obtainable with various arrangements. In the case of S/B=16, H/B=6 and Re=7800, maximum average Nusselt number of overall blocks was obtained.

• 한국전자파학회논문지
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• 제15권4호
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• pp.353-359
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• 2004

본 논문에서는 슬롯 판과 도파관의 두 파트로 구성되어 있는 단층 구조의 슬롯 도파관 배열 안테나를 설계하였다. 슬롯 판과 도파관 사이의 전기적인 접촉을 구현하는 것이 대량 생산에 있어 가장 어려운 점이며 이를 위하여 Dumbbell 패치와 초크를 가지는 슬롯 도파관 배열 안테나를 제안하였다. 초크는 슬롯 판과 도파관 사이의 갭에 의해 발생하는 누설 전류를 막아 주지만 도파관 사이에 공간상의 손실이 발생하게 된다 본 논문에서는 Dumbbell 패치를 사용하여 공간상의 손실을 줄일 수 있었고, 16${\times}$16배열 안테나를 제작한 결과 27.2 ㏈의 이득과 45 %의 효율을 얻었다.