• 한국항공운항학회지
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• 제14권1호
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• pp.43-48
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• 2006

The present study was carried out in order to develope a seven-hole pressure probe which is able to measure high flow angles. The seven-hole pressure probe is a non-nulling, directional velocity probe used for measuring three dimensional flow that having high flow angles. A 4 mm diameter seven-hole conical pressure probe was manufactured with a cone angle of 70$^{\circ}$. The probe was comprised of seven 1 mm diameter stainless steel tubes packed close together and fitted into an outer stainless steel sleeve. The calibration procedure is based on the use of the Callington's polynomial curve-fit method. The validity of the seven-hole conical pressure probe is demonstrated by comparisons with hot-wire data.

• 한국유체기계학회 논문집
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• 제13권6호
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• pp.5-12
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• 2010

Comparative study on the flow measurement by 5-hole and 7-hole probes was conducted in a linear cascade with tip clearances of 2.3%, 3.1%, and 4.4% of the blade span. Calibration range of the 5-hole and the 7-hole probes were ${\pm}25$ and ${\pm}50$ degrees, respectively. Results show that the secondary flow and total pressure loss measured by the 5e-hole and 7-hole probes were similar at small tip clearance cases. However, at the tip clearance of 3.1% and 4.4% of the blade span cases, flow angles exceeding the calibration range of the 5-hole probe were observed. Because of the wider calibration range, larger flow angle by strong leakage vortex could be measured by the 7-hole probe.

• 대한기계학회논문집B
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• 제21권5호
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• pp.637-649
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• 1997

Effects of cone angle, pressure-hole orientation and Reynolds number on the five-hole probe calibration have been investigated for eight large-scale conical five-hole probes, which have either perpendicular pressure holes or forward-facing pressure holes for the cone angles of 45 deg, 60 deg, 75 deg and 90.deg. Pitch and yaw angles are changed from -40 deg to +40 deg with an interval of 5 deg, respectively, when the probe Reynolds numbers are 1.77*10$^{4}$, 3.53*10$^{4}$ and 7.06*10$^{4}$. The result shows that larger cone angle results in more sensitive changes in the calibration coefficients. In the case that the cone angle is 45 deg, the pitch-angle and yaw-angle coefficients of the five-hole probe with the perpendicular pressure holes show a very different trend compared with those of the five-hole probe with the forward-facing pressure holes. On the other hand, when the cone angle is more than 60 deg, each calibration coefficient is nearly independent of the pressure-hole orientation. Additionally, the effects of the Reynolds number on the calibration coefficients are also reported in detail.

• 한국유체기계학회 논문집
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• 제14권5호
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• pp.5-11
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• 2011

In this study, the effect of cone angle of seven-hole probe on the accuracy of measured flow angle and velocity has been investigated. The seven-hole probe consisted of seven 1mm OD stainless inner tubes and one 3mm ID stainless tube. Six cone angles of $45^{\circ}$, $60^{\circ}$, $75^{\circ}$, $90^{\circ}$, $105^{\circ}$ and $120^{\circ}$ were tested. Calibrations of the seven-hole probes were conducted within ${\pm}60^{\circ}$ range with the interval of $5^{\circ}$. Analysis results show that the effect on the cone angle was not significant on the accuracy of the measured flow angle, pressure, and velocity. However, the data reduction method had more effect on the measurement accuracy.

• 한국전기전자재료학회논문지
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• 제11권8호
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• pp.613-619
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• 1998

Ultrasonic probes of 400kHz, 1MHz were fabricated using PZT-5Z plates. Epoxy was used for backing layer materials onthe plates. Nondestructive Test was carried using these probes. Pulse lobe width of impulse response was reduced 15.4% compare 1MHz with 400kHz and 96.6% compare 3MHz with 400kHz. The attenuation in aluminum was 2.05[dB/m] at 400kHz, 4/91[dB/m] at 1MHz, 7.35[dB/m] at 3HMz. Hole detection error of the first hole was 22.4% at 1HMz, 9.% at 3HMz, The second hole 11.6% at 1HMz, 4.7% at 3HMz. In the result of experiment of the hole detection error and resolution, 3HMz probe was the best among them.

• 동력기계공학회지
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• 제10권4호
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• pp.56-64
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• 2006

This paper shows the development process of a straight-type five-hole pressure probe for measuring three-dimensional flow velocity components. The data reduction method using a bi-cubic curve-fitting program in a new calibration map was introduced in this study. This new calibration map can be applied up to the application angle, ${\pm}55^{\circ}$ of a probe. As a result, for the application angle of ${\pm}45^{\circ}$, an error for yaw and pitch angles appeared from $-1.76^{\circ}\;to\;1.83^{\circ}$ and from $-1.91^{\circ}\;to\;1.75^{\circ}$, respectively. Moreover, an error for a vector magnitude and a static pressure compared with a dynamic one showed from -7.83% to 4.87% and from -0.73 to 0.77, respectively. Even though this data reduction method showed unsatisfactory errors in a vector magnitude, it resulted in an easy and simple application method. Especially, when it was applied to an actual flow field including a swirling flow, a good result came out on the whole. However, in order to obtain a better result, it is thought that a more sophisticated interpolation method needs to be introduced.

• 한국항공운항학회:학술대회논문집
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• 한국항공운항학회 2005년도 추계학술발표대회 논문집
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• pp.182-185
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• 2005

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.437-437
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• 2010

DC Hollow cathode 방전은 약 100여 년 전, Paschen에 의해 실험된 이후로 광원, 스퍼터링 공정, 이온빔 소스 등 다양한 분야에 이용되어 왔다. 최근 태양전지용 마이크로 결정질 실리콘 증착 시, RF CCP의 전극에 복수의 홀 혹은 트렌치 구조를 두어 Hollow cathode 방전 효과를 이용하여 향상된 공정 속도로 공정을 진행한다. 그러나 RF-MHCD (Multi hole cathode discharge) 공정을 위한 최적 규격의 홀 기에 관한 연구는 그 중요성과 응용성에도 불구하고 깊게 이루어지지 못한 바 있다. 그러므로 저자는 Capacitively Coupled Plasma (전극 간격 : 4cm, 전극 직경 : 14cm) 장비에서 평면 전극과 10mm 깊이와 각각 3.5mm, 5mm, 7mm, 10mm 직경의 홀이 있는 4개의 전극을 이용하여 Argon RF-MHCD 방전을 관찰하여 조건 별 최적의 홀 전극 디자인을 도출하였다. 실험 조건은 64.5mTorr ~ 645mTorr압력 범위/ 1A~9A이며, 플라즈마는 전극 사이 중앙에 설치한 RF-compensated Langmuir Probe와, 전극과 전기적으로 접촉하는 1000:1 Probe 와 Voltage-Current Probe를 이용하여 측정되었다. 실험 결과 압력 조건 별로, 최적의 전자 밀도를 유도하는 전극 상 홀의 직경이 달라짐을 확인하였다.

• 대한의용생체공학회:의공학회지
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• 제20권1호
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• pp.107-113
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• 1999

본 연구의 목적은 작은 부위의 종양 또는 수술후 잔여종양을 검출할 수 있는 소형 고성능 영상용 감마프로브를 개발하는 것이다. 감마프로브의 검출기 시스템을 위해 위치민감형 광전자증배관(PSPMT)을 사용하였고, -1000V의 고전압을 공급하였다. 섬광체는 직영 7.62cm, 두께 9.5mm인 NaI(Tl)를 사용하였으며, 광학그리스를 이용하여 NaI(Tl)와 PSPMT를 접합시켰다. 조준기는 평형육각구멍조준기로써 직경 1.3mm, 격벽 두께 0.22mm, 그리고 길이 40mm이었다. 신호처리시스템은 위치신호처리와 트리거신호처리로 구분되며, 위치신호처리는 전단증폭기, 주증폭기를 거쳐 가산, 감산, 제산신호회로를 이용하여 얻었고, 트리거신호는 가산증폭기, 일정분획식별기 그리고 게이트 모듈을 이용하여 얻었다. 데이터 획득은 Gamma-PF 인터페이스 보드를 경우유하여 PIP 소프트웨어와 펜티엄 PC에 제어되었다. 영상연구를 위해 점선원을 이용하여 장균이도 영상과 슬릿마스크 영상을 얻었다. 그리고 조준기를 사용하여 두 개의 구멍팬텀 영상을 얻었다. 고유공간분해능은 3.97mm이었으며, 시스템 공간분해능은 5.97mm이었다. PSPMT를 이용하여 개발한 소형 감마프로브에 의해 획득된 팬텀영상은 좋은 영상질을 보여주었으며, 임상적용을 위해서는 영상특성의 최적화 연구가 계속되어야할 것으로 생각된다.

• 한국공작기계학회논문집
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• 제15권1호
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• pp.1-7
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• 2006

A method of the volumetric error measurement and calibration of NC machine tools is studied using an artifact method. In this study, a hole-pate is designed and machined using stainless steel. We tested and applied the hole-plate artifact in a commercial CMM(Coordinate Measuring Machine), after calibration of the hole-plate using a precise CMM. It has been shown that not only the measurement of geometric error components but also the 2D length error calculation in a working volume is available using the hole-pate artifact method. The results of study can also be used in NC machine with touch probe as the same method in CMM.