• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2001년도 추계 기술심포지움
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• pp.146-150
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• 2001

Microwave model and high-frequency measurement of the ACF flip-chip interconnection was investigated using a microwave network analysis. S-parameters of on-chip and substrate were separately measured in the frequency range of 200 MHz to 20 GHz using a microwave network analyzer HP8510 and cascade probe. And the cascade transmission matrix conversion was performed. The same measurements and conversion techniques were conducted on the assembled test chip and substrate at the same frequency range. Then impedance values in ACF flip-chip interconnection were extracted from cascade transmission matrix. ACF flip chip interconnection has only below 0.1nH, and very stable up to 13 GHz. Over the 13 GHz, there was significant loss because of epoxy capacitance of ACF. However, the addition of SiO$_2$filler to the ACF lowered the dielectric constant of the ACF materials resulting in an increase of resonance frequency up to 15 GHz. High frequency behavior of metal Au stud bumps was investigated. The resonance frequency of the metal stud bump interconnects is higher than that of ACF flip-chip interconnects and is not observed at the microwave frequency band. The extracted model parameters of adhesive flip chip interconnects were analyzed with the considerations of the characteristics of material and the design guideline of ACA flip chip for high frequency applications was provided.

• 한국도로학회논문집
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• 제9권2호
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• pp.89-99
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• 2007

복소수계수 $E^*$로 표현되는 아스팔트 콘크리트의 탄성계수는 아스팔트 포장설계에서 매우 중요한 입력변수다. 일반적으로 아스팔트 콘크리트의 탄성계수는 동탄성 계수시험 (Dynamic Modulus Test)을 사용하여 평가한다. 그러나 동탄성계수시험은 일상적인 시험법으로 적용하기에는 고가의 시험장비, 복잡한 시험장비, 많은 시험시간 등의 문제가 있다. 이에 반하여 충격공진시험(IR: Impact Resonance test)은 비파괴시험으로서 간편한 시험장치, 단순한 시험방법이며 반복성이 뛰어나다. 본 연구의 주요 목적은 충격하중의 타격위치 시편거치 방법 충격하중원의 특성, 신호획득 속도, 신호처리방법 등을 포함한 IR시험의 시험조건의 영향을 평가하는 것이다. 본 연구에서 적용한 모든 시험조건 범위에서 충격공진시험에서 측정된 결과의 변동은 ${\pm}2.7%$ 이내에 들었다.

• 비파괴검사학회지
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• 제32권2호
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• pp.142-148
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• 2012

본 연구에서는 초음파원자현미경 캔틸레버의 접촉 공진주파수를 이용하여 실리콘 웨이퍼와 나노 스케일의 폴리머 박막 패턴의 접합면 사이에서 나타나는 접합 특성을 UAFM 이미지를 통해 평가하였다. 이를 위해 실리콘 웨이퍼의 표면 처리 공정을 다르게 하였고 리소그래피 공정을 통해 300 nm의 폴리머 박막 패턴을 제작하였다. 제작된 시험편의 접합 상태를 광학현미경 이미지를 통해 서로 비교하였고 나노 스크래치 시험의 임계하중 값을 통하여 나노 패턴의 접합 상태를 검증하였다. 각각의 시험편에 대해 UAFM을 이용하여 $1{\mu}m{\times}1{\mu}m$ 크기의 표면 이미지와 표층부의 접합 상태이미지를 각각 얻었고 접촉 공진주파수의 진폭과 위상의 변화로 인한 접합부의 이미지 콘트라스트 차이로 접합 상태를 평가하였다.

• 한국기계가공학회지
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• 제13권1호
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• pp.16-22
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• 2014

Resonance refers to the magnification of a structural response which occurs when a linear lightly damped system is driven with a sinusoidal input at its natural frequency. An exploratory vibration test (a natural frequency measurement test) is very important for the vibration testing of machine parts, as the value measured in an actual laboratory affects test results. For this reason, it is necessary to estimate the measurement uncertainty to verify the reliability of this type of test. In this study, measurement uncertainty is estimated based on three uncertainty factors. The uncertain factors are the measured points in the machine parts, the resolution of the vibration equipment, and uncertainty of the calibration certificate.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2003년도 제20회 춘계학술대회 논문집
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• pp.59-63
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• 2003

액체 램제트의 연소 현상을 연구하기 위한 소형 직접 연결식 시험 장치에 대한 개념 설계 방법을 기술하였다. 본 시험 장치를 이용하여 수 차례의 시험 결과 시험장치가 정상적으로 작동됨을 확인하였다. 측정된 연소실 압력 데이터에서 약190Hz대의 특정 주파수가 계측되었으며, 이는 연소실의 1L 음향 주파수(1200Hz)와는 차이가 큰 것이다. 불안정 모드를 야기하는 원인으로 dump combustor에서 발생되는 흡입 공기의 vortex street, 쵸크 되지 않은 긴 흡입관에서 발생되는 흡입구의 resonance, 관측창으로 인해 변형된 연소실 형상 등이 그 원인으로 판단된다.

• Journal of Biosystems Engineering
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• 제35권3호
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• pp.182-188
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• 2010

Post-Harvest processing engineering is a field that studies prevention of the quality change of agricultural products during sorting, packaging, storage, and distribution after harvested. In distribution steps, agricultural products could be damaged by physical force, it is the main reason of low quality and they lost value of commodities. This study was performed to find the vibration characteristics of the peach, and to find the extent of the damage on the peach by fatigue stress. The vibration data was obtained on expressway and the vibration characteristics of peach was used to find the damage on the peach. To analyze the vibration characteristics of peach, the resonance frequency and vibration transmissibility were measured. The resonance frequency of the peach was 167.98 Hz and the transmissibility was 4.06 at resonance point. It was 150 ~ 250 Hz that the transmissibility was more than 1. And the transmissibility in simulated test was measured. When the trasmissibility was more than 1, the range was 15 ~ 65 Hz, and when it was less than 1, the range was 65 ~ 175 Hz. When the transmissibility was about 1, the range was 5 ~ 15 Hz. The damage and the vibration cycle numbers of peaches were compared with input frequency and acceleration. More damage and less cycle number happened in 30 Hz than in 62.5 Hz. The reason was that the transmissibility of 30 Hz was higher and the vibration displacement in lower frequency was more. The more acceleration and cycle number increased, the more the bruising volume of peaches increased. The bruising volume ratio for vibration fatigue was measured according to input acceleration and cycle number. Using measured data, regression models for bruising volume ratio(BVR) was developed as a function of the acceleration(A) and cycle number(CN) as follows. BVR = a * $A^b*$ $(CN)^c$

• 한국소음진동공학회논문집
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• 제22권1호
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• pp.3-8
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• 2012

In an attempt to improve adhesion strength between glass and metal due to use of Pb-free solder as a sealant between glass and metal in the manufacturing process of vacuum insulation window glass to maintain the vacuum volume, ultrasonic energy is often applied during the process of Pb-free sealing. In this study, we propose an ultrasonic vibrator with a 4 mm end tip radius which performs resonance frequency of 60 kHz and 14 um or higher vibration displacement. A frequency variation due to applied pressure on piezo disks, which was excluded in the computer simulation, was verified experimentally, and we have demonstrated a 17 um vibration displacement at 50 V input through the performance test of a vibrator constructed with our specification.

• 센서학회지
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• 제28권6호
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• pp.371-376
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• 2019

We have developed an acoustic resonance inspection system to inspect the welding defects in the mechanical parts fabricated using friction stir welding method. The inspection system was consisted of a DAQ board, a microphone sensor, an impact hammer, and controlled by a PC software. The system was developed to collect and analyze the sound signal generated by hitting the sample with an impact hammer to determine whether it is defective. In this study, 100% welded good samples were compared with 95%, 90%, and 85% welded samples, respectively. The variation of the completeness in welding did not affect the visual appearance in the samples. As a result of analyzing the natural frequencies of the good samples, the five natural frequency peaks were identified. In the case of the defective samples, the frequency change was observed. The welding failure detection time was fast enough to be only 0.7 seconds. Employing our welding defect inspection system to the actual industrial field will maximize the efficiency of quality inspection and thus improve the productivity.

• 대한토목학회논문집
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• 제33권2호
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• pp.585-594
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• 2013

공진형 파동에너지 추출시스템은 권혁민 등(2010)에 의해 최초로 제안되었다. 본 시스템은 계류장치와 직렬발전기 그리고 발전기를 가진하는 부이로 구성되어 있으며 직렬발전기의 운동자는 부이의 수직운동에 의해 내부 진동하는 시스템이다. 하지만, 우리나라와 같이 파랑에너지가 비교적 적은 지역에서는 가진체인 부이의 수직운동 크기를 증폭시킬 필요가 있다. 본 연구는 발전기를 탑재한 부이가 공진할 수 있도록 제원을 조절하고 이의 증폭효과를 실험적으로 확인하였다. 모형부이는 공진주기 1.96 sec에 해당하는 흘수를 확보하도록 제원을 조절하였다. 부이공진 실험은 최대수심 6.0 m, 폭 8 m, 길이 110 m인 대형수조에서 규칙파 및 불규칙파에 대하여 수행되었다. 실험파는 평상파의 파형경사에 해당하는 약 0.01에 상응하도록 파를 선택하였다. 부이의 수직변위 관측시계열 자료는 규칙파의 진폭증폭율과 불규칙파의 스펙트럼 면적비에 대하여 분석하였다. 분석결과, 규칙파실험은 모형 전력생산부이의 공진주기 1.96 sec에서 최대 진폭증폭율 5.66을 얻었으며 불규칙파의 경우는 첨두주기가 1.96 sec보다 약간 짧은 1.85 sec에서 최대 스펙트럼면적비 20.73을 얻었다. 본 실험성과로부터 부이의 공진설계가 전력생산의 증대에 유효하며 우리나라와 같이 비교적 파랑에너지가 적은 지역에서 상업적 전력생산을 위하여 필수불가결함을 알았다.

• 전기학회논문지
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• 제58권3호
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• pp.566-572
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• 2009

This paper has studied breakage possibility of glass insulators by resonance and accelerated deterioration through the comparison of the natural vibration and on site vibration. The natural frequencies of the strut tube glass insulator was measured within a range of less than 1kHz. In the on site vibration, the largest frequency that was imposed on strut tube glass insulators was 80Hz with 1.13g of vertical vibration in the viaduct section, the largest vertical vibration (0.38g) was detected at 103Hz in the open route section. When site vibration and natural vibration of strut tube glass insulators were compared in terms of characteristics, the resonance frequency was not the same. In both the viaduct and open route sections, it seems that the impact by vertical vibration in strut tube glass insulators is large. It's very unlikely that glass insulators were damaged by fatigue accumulation of vibration since the possibility of damage by resonance was very low in consideration of the characteristics of natural vibration and site vibration of glass insulators. In addition, no damage was detected in the accelerated deterioration test.