• 한국소음진동공학회논문집
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• 제15권4호
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• pp.452-456
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• 2005

Cyclone is widely adopted in the vacuum cleaner, because of the simple structure, the high dust collection efficiency and its transparency feature, which can be shown to the customer. At past times, cyclone performance was represented by collection efficiency, flow rate, pressure drop etc. At recent times the noise problem is getting important as cyclone comes into home-appliances. In this paper, pressure drop of cyclone and it's noise were measured at the variation of the cyclone structure and the main sources of cyclone peak noise was found by experimental and numerical analysis. In addition, the structure for peak noise reduction was suggested and it is beneficial both pressure drop and noise reduction.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.89-92
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• 2004

Cyclone is widely apoted in the vacuum cleaner, because of it's simple structure, the dust collection efficiency is high and its transparency feaure which can be shown to the customer. At past times, cyclone performance is represented by collection efficiency, flow rate, pressure drop etc. At recent times the noise problem is getting important as cyclone comes into home-appliances. In this paper, cyclone's pressure drop and noise is measured at the variation of the cyclone structure and the main sources of cyclone peak noise is found by experiments and numerical analysis. In addition, the structure for peak noise reduction is suggested and it is beneficial both pressure drop and noise reduction.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2016년도 학술발표회
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• pp.375-379
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• 2016

Recently derived energy dissipation equation by Chamani(2008) and the profile function of the free overfall by Marchi(1993) were verified with present experiment data. The experiment was conducted in hydraulic laboratory, Hanyang University where the flume is 7m long and 0.44m wide, and the height of the drop structure is 0.205m. Water depth and free overfall profile data were collected using an ultra sonic distance sensor and photographic images. The time-averaged water depth data and the free overfall profile were analyzed to examine the energy dissipation pattern over the drop structure

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
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• pp.209-212
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• 2001

We Propose a novel structure add/drop multiplexer based on an all-fiber Mach-Zehnder interferometer and fiber Bragg grating. In this structure, wavelength separation is achieved by adjusting the amount of the phase shift in the Mach-Zehnder interferometer. The proposed add/drop multiplexer drops a part of signal at a specific wavelength and transmit the remnant of the signal to the different node separated wavelength in WDM network.

• 화약ㆍ발파
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• 제10권1호
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• pp.3-7
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• 1992

In the pilling works in the city, it is tend to transfered to the non-vibration pilling works. This drop-hammer pilling executed with in 2 meters distance to neighbour building structure. in the rainy season. According to imperical formula which tested in similar site, Vibration damaged area is within 14 meters radius from drop-hammer pilling site. The loratories Data of Dae Woo of Korea hausing Authority are refered to above poject.

• 한국전기전자재료학회논문지
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• 제21권11호
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• pp.981-986
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• 2008

The conventional IGBT has two problems to make the device taking high performance. The one is high on state voltage drop associated with JFET region, the other is low breakdown voltage associated with concentrating the electric field on the junction of between p base and n drift. This paper is about the structure to effectively improve both the lower on state voltage drop and the higher breakdown voltage than the conventional IGBT. For the fabrication of the circular trench IGBT with the circular trench layer, it is necessary to perform the only one wet oxidation step for the circular trench layer. Analysis on both the on state voltage drop and the breakdown voltage show the improved values compared to the conventional IGBT structure. Because the circular trench layer disperses electric field from the junction of between p base and n drift to circular trench, the breakdown voltage increase. The on state voltage drop decrease due to reduction of JFET region and direction changed of current path which pass through reversed layer channel. The electrical characteristics were studied by MEDICI simulation results.

• Korean Chemical Engineering Research
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• 제53권1호
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• pp.16-21
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• 2015

다이어프램 방식 준비작동식 유수검지장치의 압력손실을 줄이기 위하여 본체 구조를 개선하였다. 개정된 유수제어밸브의 압력손실시험 기술기준을 통과하기 위해서는 압력손실이 20.7 kPa을 초과하여서는 안된다. 압력손실시험은 한국소방산업기술원 유수제어밸브 기술기준에 따라서 실시하였다. 준비작동식 유수검지장치는 습식 유수검지장치에 비해 압력손실이 크게 발생하였는데, 그 원인을 유체의 유동현상과 관련하여 분석하였다. 준비작동식 유수검지장치의 본체 내부 구조는 유로의 단면 크기와 방향 변화로 인해 압력손실 요인이 많았다. 이러한 압력손실 요소를 제거하기 위해 습식 유수검지장치와 비슷한 클래퍼 타입으로 구조를 변경하였다. 구조 변경 후 압력손실 값은 호칭 80A인 경우 80.9 kPa에서 14.4 kPa로 감소하였으며, 호칭 100A인 경우 171.0 kPa에서 14.2 kPa로 감소하여 기술기준에 적합한 압력손실 값을 얻을 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1367-1372
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• 2008

A plate type supporting structure of a tube bundle in axial flow generates a certain band of a high frequency periodic excitation of a vortex shedding and/or a flow separation due to sharp edge of the plate thickness and a severe pressure drop due to a cross-sectional area of the supports. With a design consideration of the low vibration and a small flow resistance, the analysis method is uniquely confined to an experimental approach because a complex geometry of a cylindrical tube bundle and/or physical phenomena related to the fluid-structure interaction of tube bundle in a flow impede a theoretical or a numerical approach. A 5x5 cylindrical tube bundle with 5 supports which were discretely located along the bundle's axis was tested in the FIVPET hydraulic test loop for a design evaluation and an analysis perspectives. A high frequency flow-induced vibration of the supporting structures of the cylindrical tube bundle was measured at a outer surface of a supporting structure through a transparent flow housing by the laser dopper vibrometer. Pressure drop in-between three measurement distances was measured by the differential pressure transmitter. High frequency vibration and pressure drop fairly depends on the geometric design of supporting structure. So, these two parameters would be used as a qualitative design variables for design evaluation and analysis.

• 대한전자공학회논문지SD
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• 제37권5호
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• pp.49-54
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• 2000

양방향 환형망의 구성에 필수적인 새로운 구조의 양방향 파장가감가를 제안하였다. 제안된 구조는 광섬유 브래그 격자를 이용하였으며 실험을 통하여 이것의 성능을 광스펙트럼의 영역에서 검증하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.14-15
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• 2009

Insulated Gate Bipolar Transistor(IGBTs) are widely used in power device industry. However, to improve the breakdown voltage, IGBTs are suffered from increasing on-state voltage drop due to structural design. In this paper, the new structure is proposed to solve this problem. The proposed structure has double p-floating layer inserted in n-drift layer. The p-floating layers improve the breakdown voltage compared to conventional IGBT without change of other electrical characteristics such as on-state voltage drop and threshold voltage. this is because the p-floating layers expand electric field distribution at blocking state. A electrical characteristic of proposed structure is analyzed by using simulators such as TSUPREM and MEDICI. As a result, on-state voltage drop and threshold voltage are same to a conventional TIGBT, but breakdown voltage is improved to 16%.