• ETRI Journal
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• 제35권5호
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• pp.827-837
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• 2013

In this paper, we present wideband common-mode (CM) noise suppression using a vertical stepped impedance electromagnetic bandgap (VSI-EBG) structure for high-speed differential signals in multilayer printed circuit boards. This technique is an original design that enables us to apply the VSI-EBG structure to differential signals without sacrificing the differential characteristics. In addition, the analytical dispersion equations for the bandgap prediction of the CM propagation in the VSIEBG structure are extracted, and the closed-form expressions for the bandgap cutoff frequencies are derived. Based on the dispersion equations, the effects of the impedance ratio, the EBG patch length, and via inductances on the bandgap of the VSI-EBG structure for differential signals are thoroughly examined. The proposed dispersion equations are verified through agreement with the full-wave simulation results. It is experimentally demonstrated that the proposed VSI-EBG structure for differential signaling suppresses the CM noise in the wideband frequency range without degrading the differential characteristics.

• Journal of electromagnetic engineering and science
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• 제8권4호
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• pp.153-157
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• 2008

Most of malfunctions in electronic equipment or systems controlled by processors is occurred by the differential- and common-mode noises, and the electrical fast transient (EFT). The International Electrotechnical Commission (IEC) has prepared the dummy signal to test the immunity level of the equipment. For the countermeasure against the differential- and common-mode noises, and the EFT, we designed, fabricated, and tested a new electromagnetic compatibility (EMC) filter, which is composed of feed-through capacitors and ferrite beads with high permeability. As a result, the filter showed excellent differential- and common-mode noises filtering, and immunity improving characteristics over the frequency band from 30 MHz to 1.5 GHz and 1.8 GHz, respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.479-482
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• 1993

A fully balanced differential amplifier can achieve high-gain wide-bandwidth characteristics. And also, Offset PSRR, CMRR and Noise performance of that are excellent, but these merits can be achieved only when the architecture holds fully balanced. Commonly, the fully balanced differential amplifier has a common mode feedback(CMFB) circuit in order to maintain the balance. This paper presents improved characteristics of the CMFB circuit and designs the wide-bandwidth CMOS Op-amp. The unity gain bandwidth of this Op-amp is 50MHz with the load capacitor 2pF, and the value of phase margin is $85^{\circ}$.

• 한국전자파학회논문지
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• 제19권9호
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• pp.985-991
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• 2008

본 논문은 차동과 공통 모드로 동작하는 메타 재질 구조를 바탕으로 평형 믹서 수신기를 제안한 것이다. 이 메타 재질 구조는 리키 웨이브 안테나로 동작하며, 순수 공통 모드는 억압한다. 이러한 특성은 낮은 LO 누설전력과 높은 RF-LO 고립도를 갖고 있어 LO과 RF 경로에 추가적인 여파기가 필요로 하지 않는다. 이 메타 재질은 차동 모드 동작에서는 Composite Right/Left-Handed(CRLH) 메타 재질처럼 동작하고, 공통 모드에서는 차단되는 성질을 갖는 단위 셀을 기초로 설계하였다. 제안된 메타 재질의 차동과 공통 모드 특성은 실험 결과를 통하여 증명하였다. 메타 재질을 이용한 수신기는 $1.96{\sim}2.40$ GHz의 주파수 범위에서 동작하는 안테나와 평형 믹서를 집적화시켜 제작하였고, 2.4 GHz에서 21.1 dB의 믹서의 변환 손실을 얻었다.

• 한국전자파학회논문지
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• 제19권3호
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• pp.343-351
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• 2008

본 논문에서는 FPC(Flexible Printed Circuit) 케이블에 적층된 나선형 인덕터를 내장하여 다기능 케이블을 위한 공통 모드 필터를 제안하였다. 공통 모드 필터가 내장된 FPC 케이블은 별도의 SMD(Surface Mounted Device) 필터 없이 연성 케이블과 공통 모드 차단 특성을 가짐으로서, 다기능 케이블이라는 새로운 개념을 제시한다. 내장된 공통 모드 필터는 광대역의 공통 모드 차단 대역을 가지고 손실이 큰 페라이트와 같은 자성 물질을 사용하지 않아 차동 모드 삽입 손실 및 반사 손실이 향상되었다. 3-turn 인덕터를 가진 공통 모드 필터는 공통 모드차단 대역이 $0.4{\sim}3.12GHz$이며, 페라이트를 적용한 상용 LTCC(Low Temperature Co-fire Ceramic) 공통 모드 필터에 비해 3 GHz에서 1.95 dB, 8 GHz에서 6.97 dB의 향상된 차동 모드 삽입 손실을 갖는다.

• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.301-306
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• 2014

We proposed a new PCB-type 'common-mode current($I_c$) and differential-mode current($I_d$) detector' working for fast detection of $I_c$ and $I_d$ from the differential-mode signaling, with miniaturization effect and possibility of cheaper fabrication. In order to realize this device, we suggest a branch-line-coupler balun having a composite right- and left-handed(CRLH) one-layer microstrip phase-shifting line as compact as roughly ${\lambda}_g/14$. The presented balun obviously is different from the conventional bent-&-folded delay lines or slits on the ground for coupling the lines on the top and bottom dielectrics. As we connect the suggested balun output ports of the differential-mode signal lines via the through-port named U and coupled-port named L, $I_c$ and $I_d$ will appear at port ${\Delta}$ and port ${\Sigma}$ of the present device, in order. The validity of the design scheme is verified by the circuit-and numerical electromagnetic analyses, and the dispersion curve proving the metamaterial characteristics of the geometry. Besides, the examples of the $I_c$ and $I_d$ indicator are observed as the even and odd modes in differential-mode signal feeding. Also, the proposed device is shown to be very compact, compared with the conventional structure.

• Korean Journal of Radiology
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• 제23권6호
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• pp.581-597
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• 2022

Left ventricular (LV) wall thickening, or LV hypertrophy (LVH), is common and occurs in diverse conditions including hypertrophic cardiomyopathy (HCM), hypertensive heart disease, aortic valve stenosis, lysosomal storage disorders, cardiac amyloidosis, mitochondrial cardiomyopathy, sarcoidosis and athlete's heart. Cardiac magnetic resonance (CMR) imaging provides various tissue contrasts and characteristics that reflect histological changes in the myocardium, such as cellular hypertrophy, cardiomyocyte disarray, interstitial fibrosis, extracellular accumulation of insoluble proteins, intracellular accumulation of fat, and intracellular vacuolar changes. Therefore, CMR imaging may be beneficial in establishing a differential diagnosis of LVH. Although various diseases share LV wall thickening as a common feature, the histologic changes that underscore each disease are distinct. This review focuses on CMR multiparametric myocardial analysis, which may provide clues for the differentiation of thickened myocardium based on the histologic features of HCM and its phenocopies.

• Advances in pediatric surgery
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• 제8권1호
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• pp.54-61
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• 2002

Hirschsprung's disease (HD) is usually diagnosed in the newborn period and early infancy. The common presentation of HD in newborns consists of a history of delayed passage of meconium within the first 48 hours of life. The differential diagnosis in newborns is one of the clinical challenges of this disorder. A number of medical conditions which cause functional obstruction of the intestines are easily excluded. Neonates with meconium ileus, meconium plug syndrome, distal ileal atresia and low imperforate anus often present in a manner similar to those with HD in the first few days of life. Abdominal radiographs may help to diagnose complete obstruction such as intestinal atresia. Microcolon on contrast enema can be shown in cases with total colonic aganglionosis, ileal atresia or meconium ileus. Suction rectal biopsy or frozen section biopsy at operation is essential for differential diagnosis in such cases. HD is also considered in any child who has a history of constipation regardless of age. Older children with functional constipation may have symptoms that resemble those of HD and contrast enema is usually diagnostic. However, children with other motility disorders generally referred to as chronic idiopathic intestinal pseudoobstruction present with very similar symptoms and radiographic findings. These disorders are classified according to their histologic characteristics.; visceral myopathy, visceral neuropathy, intestinal neuronal dysplasia (IND), hypoganglionosis, immature ganglia, internal sphincter achalasia. Therefore, the workup for motility disorders should include rectal biopsy not only to confirm the presence of ganglion cells but also evaluate the other pathologic conditions.

• 한국안전학회지
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• 제23권5호
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• pp.111-118
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• 2008

In usual safety signs are final means to transmit hazard information so that the importance of them cannot be emphasized too much. Nevertheless, in Korea, few people are interested in functions of safety signs so that evaluation of safety signs are seldom committed. This research was conducted to evaluate and compare perceptional characteristics of safety signs, especially "Fall" signs, by Semantic Differential Method and Multi-dimensional Scaling Method, with undergraduate students as well as industrial workers. According to research results on several signs evaluated high through suggested procedure, action inducibility was different for students majoring in different sciences, but it had common elements in the sense of 'openness' or 'arrangements'. Besides, perceptional images on safety signs were mainly recognized with bases of 'arrangement' for student group and 'simplicity' for industrial workers, respectively, and their maps corresponded well with each other by partial rotating so that students and workers seemed to recognize safety signs with similar factors though their name might be different. However, since perceptional characteristics including image map, comprehensibility, and action inducibility were similar for student group whereas those were not for worker group, it was concluded that the test for action inducibility would be absolutely necessary for safety signs for workers' group.

• 한국전자파학회논문지
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• 제25권1호
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• pp.39-46
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• 2014

본 논문에서는 On-Board Broadband 특성을 갖는 2.4 GHz Inverted-L 안테나를 제안하였다. 안테나는 시스템 보드에 Inverted-L 안테나를 설계하였으며, 공통 모드와 차동 모드를 형성하도록 스터브를 설계하여 안테나의 리액턴스를 조정하여 대역폭을 개선하였다. 시스템 크기는 $80mm{\times}60mm$이고, 안테나 영역은 $30mm{\times}60mm$로 제한하였으며, 기판은 두께가 0.8 mm이고, 유전율이 4.4인 FR4를 사용하였다. 실험 결과, 대역폭은 17.2~24.1 %이고, 이득은 3.01~4.71 dB이며, 방사 패턴은 전방향 특성의 결과를 얻었다. 본 논문의 결과를 적용함으로써 휴대 단말기의 가격경쟁력과 생산효율을 향상시킬 수 있다.