• Investigative Magnetic Resonance Imaging
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• 제19권3호
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• pp.137-145
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• 2015

Purpose: To investigate correlations of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor type 2 (HER2) statuses with magnetic resonance imaging (MRI) features and clinicohistological characteristics in patients with invasive lobular carcinoma (ILC). Materials and Methods: Data from 64 histologically confirmed ILCs were analyzed retrospectively. Preoperative breast MRI was reviewed for morphology and dynamic contrast-enhanced kinetics of the tumor. Pathologic reports were reviewed for ER, PR, and HER2 positivity, tumor size, lymph node metastasis, and the number of metastatic lymph nodes. Furthermore, there was an investigation of the MRI features and clinicohistologic characteristics, according to the ER, PR, and HER2 statuses. Results: A significant difference in MRI features and clinicohistological tumor characteristics were observed only in relation to PR status. Of the 64 ILCs, 10 (15.6%) were PR negative. PR negative cancers, compared with PR positive cancers, were more likely to present as non-mass enhancement (P = 0.027); have a significantly larger mean tumor size ($5.00{\pm}1.05cm$ vs. $2.57{\pm}0.21cm$, P = 0.021); and have significantly more metastatic lymph nodes (P = 0.010). Conclusion: PR negative ILC presented more frequently as non-mass enhancement on MRI, with larger tumors and increased numbers of metastatic lymph nodes. Therefore, the PR status plays an important role in determining MRI features and clinicohistological characteristics of ILC.

• 대한전기학회논문지:전력기술부문A
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• 제55권5호
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• pp.191-194
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• 2006

Power system restoration following a wide area or complete blackout starts with energizing primary restorative transmission systems. During this primary restoration process, unexpected over-voltage may happen due to nonlinear interaction between the unloaded transformer and the transmission system. This is known as the harmonic resonance phenomenon that may cause burning out of transformer or other devices. Since the harmonic resonance originates from the nonlinear characteristics, it is very difficult to predict the occurrence of this phenomenon. This paper reports the analyses of the harmonic resonance occurred in domestic power system. Various analyses and results of the harmonic over-voltage is presented based on the PSCAD/EMTDC simulations.

• Journal of information and communication convergence engineering
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• 제3권3호
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• pp.137-141
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• 2005

The paper presents some methods to improve characteristics of film bulk acoustic resonator (FBAR) devices. The FBAR devices were fabricated on Bragg reflectors. Thermal treatments were done by sintering and/or annealing processes. The measurement showed a considerable improvement of return loss $(S_{11})$ and quality factor $(Q_{s/p}).$ These thermal treatment techniques seem very promising for enhancing FBAR resonance performance.

• International Journal of Internet, Broadcasting and Communication
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• 제4권2호
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• pp.22-27
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• 2012

The design characteristics of circular vertical-cavity surface-emitting lasers are studied by using a newly developed equivalent network. Optical parameters, such as the stop-band or the reflectivity of periodic mirrors and the resonance wavelength, are explored for the design of these structures. To evaluate the differential quantum efficiency and the threshold current density, a transverse resonance condition of modal transmission-line theory is also utilized. This approach dramatically reduces the computational time as well as gives an explicit insight to explore the optical characteristics of circular vertical-cavity surface-emitting lasers (VCSELs).

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2000년도 종합학술발표회 논문집 Vol.10 No.1
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• pp.319-323
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• 2000

A method for miniaturization of microstrip patch antenna without degrading its radiation characteristics is investigated. The ring geometry introduces additional parameters to the antenna that can be used to control its resonance frequency and bandwidth. For a single square ring increasing the size of patch decreases the resonance frequency and bandwidth. To match the antenna to a transmission line and also enhance its bandwidth. the square ring patch is stacked by a square ring patch. The computed results are compared with experiment and good agreement is obtained.

• Journal of information and communication convergence engineering
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• 제3권4호
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• pp.167-171
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• 2005

In this paper, the resonance characteristics of SMR-type FBAR devices annealed by three different annealing methods are investigated and compared. The resonance characteristics could be effectively improved by the proposed efficient annealing method which optimizes the annealing conditions. It seems very useful for improving the performance of the SMR-type FBAR devices as a cost-effective way.

• 대한전자공학회논문지TC
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• 제47권11호
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• pp.77-83
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• 2010

본 논문은 2.4 GHz 와 5 GHz 대역에서 802.11n 규격에 사용가능한 이중 공진 PIFA(Planar Inverted F-Antenna)를 제안하였다. 이중 공진을 위해 2.4 GHz 대역에서는 패치, 5 GHz 대역에서는 U-형 슬랏을 이용하여 PIFA를 설계하였다. 단락판과 급전핀의 위치, 단락판의 폭, U-형 슬랏의 두께, U-형 슬랏의 위치를 변경시키며 HFSS(High Frequency Structure Simulation)를 이용하여 안테나의 특성변화를 조사하였다. 실제 시제품을 제작하여 측정한 값과 시뮬레이션 값을 비교 분석한 결과, U-형 슬랏의 위치가 급전핀과 멀어질수록, 그 두께가 얇을수록 안테나의 특성이 좋아지는 것을 알 수 있었다.

• 항공우주기술
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• 제4권2호
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• pp.216-219
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• 2005

이 논문은 무중력환경에서 작은 질량을 측정하기 위한 시스템의 설계와 테스트 결과 분석을 보여준다. 무중력환경에서는 지상에서와 같이 중력에 이용하여 무게를 측정하는 것은 어렵다. 그래서 여기서 제안된 방법은 측정하고자 하는 샘플의 무게에 대한 함수인 공진주파수를 측정하는 것이다. 우리가 무게에 대한 공진주파수를 안다면 샘플의 공진주파수를 측정하여 그 질량을 알 수 있다. 그래서 피에조 세라믹이라는 물질을 이용하여 시스템을 만든 후 실제로 측정하였다. 이 시스템은 여러 문제가 있었지만, 우리는 미지의 물체의 질량을 측정할 수 있었다.

• Journal of Biosystems Engineering
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• 제28권3호
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• pp.253-260
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• 2003

In this study, the feasibility of magnetic resonance techniques for nondestructive internal quality evaluation of Korean red ginseng was examined. Relaxation time constants were measured using various grades of red ginsengs. Solid state magnetic resonance imaging technique was applied to image dried red ginsengs which have low moisture contents (about 13%). A 7 tesla magnetic resonance imaging system operating at a proton resonant frequency of 300 ㎒ was used for acquiring MR images of dried Korean red ginseng. The comparison test of cross cut digital images and magnetic resonance images of heaven grade, good grade with cavity inside, and good grade with white part inside red ginseng suggested the feasibility of the internal quality evaluation of Korean red ginsengs using MRI techniques. A good grade red ginseng included abnormal tissues such as cavities or white parts inside was observed by the signal intensity of MR image based on magnetic resonance properties of proton nucleus. Analysis on an one dimensional profile of acquired MR image of Korean red ginseng showed easy discrimination of normal and abnormal tissues. MR techniques suggested ways to detect internal defects of red ginsengs effectively.

• 동력기계공학회지
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• 제3권2호
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• pp.26-33
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• 1999

Pressure pulsation Inside the discharge and suction cavity of rotary and scroll compressor are often a major source of objectionable noise and vibration. The key factor of these noise and vibration is due to the cavity resonance. It is not only necessary to understanding the characteristics of pulsation in order to reduce the excitation force of gas to the cavity but also to verifying the phenomena of cavity resonance. For the purpose of these understandings, measurement and simulation of cavity resonance can lead to a better understandings how they occur and be very important to identify the ways to reduce the noise efficiently. In this paper, modeling of the cavity(internal acoustics inside the shell) is discussed and simulated using FEM. Results from the simulation are compared with those measurement in experiments. In describing of cavity mode by experiments, it is very important to specify the exact conditions under which they are measured. Finally, this paper shows the one example of reduced cavity resonance in the compressor.