• 대한기계학회논문집A
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• 제32권8호
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• pp.654-659
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• 2008

This paper is to suggest a concept design of the permanent magnet type magnetic resonance imaging (MRI) device based on the parameter optimization method. Pulse currents in the gradient coils will introduce the effect of eddy currents in the ferromagnetic material, which will worsen the quality of imaging. In order to equalize the magnetic flux in the MRI device for good imaging, the eddy current effect in the ferromagnetic material must be taken into account. This study attempts to use the design of experiment (DOE) and the response surface method (RSM) for equalizing the magnetic flux of the permanent magnet type MRI device using that the magnetic flux can be calculated directly using a commercial finite element analysis package. As a result, optimal shapes of the pole and the yoke of the PM type MRI device can be obtained. The commercial package, ANSYS, is used for analyzing the magnetic field problem and obtaining the resultant magnetic flux.

• 한국포장학회지
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• 제11권1호
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• pp.11-16
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• 2005

Fruits are subjected to complex dynamic stresses in the transportation environment. During a long journey form the production area to markets, there is always some degree of vibration present. Vibration inputs are transmitted from the vehicle through the packaging to the fruit. Inside, these cause sustained bouncing of fruits against each other and container wall. These steady state vibration input may cause serious fruit injury, and this damage is particularly severe whenever the fruit inside the package is free to bounce, and is vibrated at its resonance frequency. The determination of the resonant frequencies of the fruit may help the packaging designer to determine the proper packaging system providing adequate protection for the fruit, and to understand the complex interaction between the components of fruit when they relate to expected transportation vibration inputs. The first frequency of the pear in packaged freight be stacked in resonance frequency band of the pear packaged freight was increased from the bottom to the top of the stack but the second frequency of that in resonance frequency band of the pear was decreased. This indicated that the high damage score of the pear in bottom tier in vibration test was due to higher acceleration level in resonance frequency band of the pear.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1366-1367
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• 2006

Embedded capacitor technology is one of the effective packaging technologies for further miniaturization and higher performance of electric package systems. So we used the 3D EM simulator for embedded capacitor design in 8-layed PCB(Printed Circuit Board). The designed capacitors value are 2 pF, 5pF, 10 pF, respectly. we investigated characteristics of capacitance - frequency and SRF(Self Resonance Frequency) as changing the rate of hight and width of upper pad of embedded capacitors.

• 한국포장학회지
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• 제25권3호
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• pp.125-130
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• 2019

Shock and vibration inputs are transmitted from the vehicle through the packaging to the fruit. Inside, these cause sustained bouncing of fruits against each other and container wall. These steady state vibration input may cause serous fruit injury, and this damage is particularly severe whenever the fruit inside the package is free to bounce, and is vibrated at its resonance frequency. The determination of the resonance frequencies of the fruit and vegetables may help the packaging designer to determine the proper packaging system providing adequate protection for the fruit, and to understand the complex interaction between the components of fruit when they relate to expected transportation vibration inputs. Instrumentation and technologies are described for determining the vibration response characteristics of the pears for exporting with frequency range from 10 to 200 Hz, sweep rate of 1 octave/min, sweep method of logarithmic up and down and acceleration levels of 0.2, 0.4, 0.6, 0.8 and 1.0 G considering the domestic transportation environment. The resonance frequency of the pears ranged from 49.04 to 87.16 Hz and the amplitude at resonance was between 0.96 and 4.02 G in test frequency band and acceleration level. The resonance frequency and amplitude at resonance frequency band of the pears decreased with the increase of the sample mass. The multiple nonlinear regression equations for predicting the resonance frequency of the pears were developed using the independent variables such as mass, input acceleration.

• 한국음향학회지
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• 제38권2호
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• pp.200-206
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• 2019

본 연구에서는 예인 음탐기용 음향패키지에 대한 수신전압감도 특성을 분석하기 위해 수치해석과 실험계획법을 적용하였다. 수치해석 결과는 초기 설계된 음향패키지의 구조 공진 모드 특성으로 인한 수신전압감도 변화를 보여준다. 수신전압감도 편차를 줄이기 위해 도출된 음향패키지 설계 변수의 영향은 실험계획법을 통해 분석하였다. 수신전압감도 편차는 수중청음기 쉴드캔 두께(t)의 변화에 가장 민감한 것을 확인하였다. 수조시험 결과 실험계획법에 의해 도출된 음향패키지는 수신전압감도 편차가 감소됨을 확인하였다.

• 한국포장학회지
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• 제21권3호
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• pp.91-96
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• 2015

Fruit and vegetables are subjected to complex dynamic stresses in the transportation environment. During a long journey from the production area to customers using parcel delivery service, there is always some degree of vibration present. Vibration inputs are transmitted from the vehicle through the packaging to the fruit. Inside, these cause sustained bouncing of fruits against each other and container wall. These steady state vibration input may cause serous fruit injury, and this damage is particularly severe whenever the fruit inside the package is free to bounce, and is vibrated at its resonance frequency. The determination of the resonance frequencies of the fruit and vegetables may help the packaging designer to determine the proper packaging system providing adequate protection for the fruit, and to understand the complex interaction between the components of fruit when they relate to expected transportation vibration inputs. Instrumentation and technologies are described for determining the vibration response characteristics of the fruits with frequency range 3 to 150 Hz. The resonance frequency of the pear ranged from 53 to 102 Hz and the amplitude at resonance was between 1.08 and 2.48 G. The resonance frequency and amplitude at resonance decreased with the increase of the sample mass, and they were slightly affected by mechanical properties such as bioyield deformation and rupture deformation. Regression analysis was performed among the relatively high correlated parameters from the results of correlation coefficient analysis.

• 조명전기설비학회논문지
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• 제17권4호
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• pp.8-12
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• 2003

TO-can 레이저 다이오드를 사용한 광송수신기 모듈의 주파수 대역의 특성을 관찰하였다. 레이저 다이오드의 등가회로를 추출하기 위한 R-L-C변수는 임피던스 분석기를 이용하였다. 칩콘덴서를 사용하여 패키지내의 도선에 의한 인덕턴스 성분과의 임피던스 정합을 시도하였으나 저주파수 대역에서 공진으로 인한 경사가 발견되었다. 표면실장 형으로 소자를 구성하여 사용함으로써 공진주파수를 이동시켜 원하는 주파수 대역에서 공진 경사를 제거할 수 있었다.

• 한국전자파학회논문지
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• 제15권3호
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• pp.271-277
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• 2004

초고주파 및 밀리미터파 통신 시스템의 집적회로 및 실장 기술로서 CPW기반의 전송선로를 갖는 MMIC 개발이 크게 증가하고 있으나, 실장시 패키지에서 발생되는 기생공진 현상으로 인해 그 성능이 크게 저하될 수 있다. 이런 기생 공진 현상을 억제시키기 위하여 도핑된 lossy 실리콘 웨이퍼를 칩 캐리어로 사용하고, HRS wafer를 사용하여 표면 및 벌크 MEMS 공정이 가능한 실리콘 MEMS 패키지가 해석적으로 제안되었다. 제안된 구조를 제작하여 세 가지의 칩 캐리어(conductor-back metal, 15 Ω$.$cm lossy Si, 15 ㏀$.$cm HRS)위에서 측정하여 실리콘 MEMS 패키지의 특성을 확인하였다. 제안된 실리콘 MEMS 패키지는 15 Ω$.$cm lossy 실리콘 칩 캐리어를 사용하여, 기생 공진 현상을 효과적으로 억제시킬 수 있었다. 전체 패키지에서 중앙의 GaAs CPW 패턴을 de-embedding하여 순수한 CPW MMIC 용의 실리콘 MEMS 패키지는 40 ㎓에서 삽입 손실은 - 2.0 ㏈이며, 전력 손실은 - 7.5 ㏈의 결과를 얻었다.

• 한국전자파학회논문지
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• 제18권5호
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• pp.563-568
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• 2007

본 논문에서 제안된 패키지 안테나는 900 MHz RFID 대역에 적용하기 위하여 미엔더 라인과 단락 핀을 부설하고 LTCC(Low Temperature Cofired Ceramic) 층의 공동 내부에 RFID BGA(Ball Grid Array) 칩을 장착하였다. BGA 칩과 안테나 사이에 발생되는 커플링과 혼신을 감소시키기 위한 격리 특성을 확보하기 위하여 접지면과 비아 펜스를 부설하여 Faraday Cage를 구현하였다. 제안된 안테나는 낮은 주파수 대역에서 패키지 단계의 안테나 구현에 관점을 두었다. 제안된 안테나의 크기는 $13mm{\times}9mm{\times}3.51mm$이며, 측정된 안테나의 공진 주파수는 0.893 GHz, 임피던스 대역폭은 9 MHz, 최대 방사 이득은 -2.36 dBi를 나타내었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(2)
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• pp.96-99
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• 2000

We presents a BGA(Ball Grid Array) package for RF circuit modules and extracted its electrical parameters. We constructed a BGA package of ITS(Intelligent Transportation System) RF module and examined electrical parameters with a HP5475A TDR(Time Domain Reflectometry) equipment and compared its electrical parasitic parameters with PCB RF circuits. With a BGA substrate of 3 $\times$ 3 input and output terminals, we have found that self capacitance of BGA solder ball is 68.6fF, self inductance 146pH, mutual capacitance 10.9fF and mutual inductance 16.9pH. S parameter measurement with a HP4396B Network Analyzer showed the resonance frequency of 1.55㎓ and the loss of 0.26dB. Thus, we may improve electrical performance when we use BGA package structures in the design of RF circuit modules.