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다중 양자 우물 구조의 전계 흡수 변조기의 혼변조 왜곡 특성
윤영설,최영완 대한전기학회 2005 전기학회논문지C Vol.54 No.6(C)
Linearity is an important property of optical devices for analog communications. In this paper, we study the 3rd-order intermodulation distortion (IMD3) of an InP/InGaAsP multiple-quantum-well (MQW) traveling-wave type electroabsorption modulator (TW-EAM). We observe abnormal notches in the IMD3 results those were different from notches by general transfer curve of electroabsorption modulators (EAMs). We analyze the phenomena through absorption coefficients according to wavelengths and bias voltages to verify appearance of the abnormal notchs, where it can be known to result from Stark-shift and broadening. We propose the method to enhance linearity of MQW-EAMs by using these effects.
윤영설,장진우,정상섭,박용구,이병인,박수철 대한신경외과학회 1993 Journal of Korean neurosurgical society Vol.22 No.11
Authors report a case of intractable temporal lobe epilepsy recorded by the foramen ovale electrode and underwent standard temporal lobectomy including amygdalohippocampectomy. The foramen ovale electrode for analysis of seizures provides good neurophysiological information in candidates for resective surgery. Also the foramen ovale electrode is a relatively simple free hand procedure and relatively nontraumatic to the brain. In conclusion, the foramen ovale electrode recording in the presurgical evaluation of intractable temporal lobe epilepsy might provide suffcient information to select a candidates for temporal lobectomy or selective amygdalohippocampectomy.
FDTD를 이용한 TEM Cell의 차단주파수에 관한 분석
윤영설,공순철,윤재훈,김정기 한국전자파학회 1999 한국전자파학회논문지 Vol.10 No.1
본 논문에서는 FDTD법을 이용하여 TEM Cell의 차단주파수를 분석하고, 모드를 확인하기 위하여 FDTD 에 맞는 경계조건 등 분석방법을 제시한다. 그리고 이전에 발표된 논문들과의 결과비교를 통해 FDTD의 효율성을 확인한다. 그와 더불어 이전에 발표된 논문들 중에서 TEM Cell 특히 symmetric TEM Cell의 차단주 파수에서 논쟁이 되었던 부분에 대해 FDTD 결과를 이용해 의견을 제시한다. In this paper, we analyze the cutoff frequencies of the TEM Cells by the FDTD, and introduce new boundary condition for the FDTD to identify the modes. Then, we confirm efficiency of the FDTD comparing results in previous papers. We also give our opinion from the results by FDTD to the arguments, which is resulted from different results about cutoff frequencies in the TEM Cells, especially the symmetric TEM Cells.
마이크로파 특성에 따른 진행파형 전계흡수 변조기의 비선형 모델
윤영설,이정훈,최영완 대한전자공학회 2003 電子工學會論文誌-SD (Semiconductor and devices) Vol.40 No.8
본 논문에서는 진행파형 전계흡수 변조기 (TW-EAM: traveling-wave electroabsorption modulator)의 선형성을 분석하기 위한 새로운 모델을 제시한다. TW-EAM은 소자의 길이, 마이크로파 손실 (microwave loss, ML), 그리고 임피던스 부정합에 의한 내부반사(internal reflection, IR) 등이 소자의 선형성에 영향을 미친다. 소자의 길이의 증가는 혼변조 왜곡 (intermodulation distortion, IMD)이 최소가 되는 전원전압의 크기를 감소시킨다. ML의 증가는 3차 혼변조 왜곡 (third-order IMD, IMD3)의 감소와 동시에 출력신호의 전력도 감소시킨다. IR은 입력주파수의 파장과 소자의 길이에 따라 각기 다른 IMD 특성을 나타낸다. ML 또는 IR에 의한 SFDR (spurious-free dynamic-range)의 변화는 거의 없었으며, TW-EAM의 IR을 이용하면 ML에 의한 신호 전력의 감쇄를 보상해 줄 수 있음도 알 수 있었다. 결과적으로 50 GHz 대역의 RF-광통신용 TW-EAM은 길이가 0.8 mm이고 출력단의 임피던스 부정합을 이용하면서 최소의 손실을 가지는 구조가 적당함을 알 수 있었다. In this paper, we introduce a novel model to analyze the linearity of a TW-EAM (traveling-wave electroabsorption modulator). The device length, microwave loss (ML), and internal reflection (IR) due to impedance mismatch have effect on the linearity of a TW-EAM. The longer devices have characteristics of lower biases with minimum IMDS (intermodulation distortions). ML decreases the output power as well as the IMD value. Internal reflection has different nonlinear characteristics according to the wavelength of the input frequency and the device length. There is little change in SFDR (spurious-free dynamic range) due to ML or IR. As a result, for a 50 GHz band RF-optical communication system, a 0.8 mm-long TW-EAM with the lowest ML would have better properties by using n, which is caused by impedance, mismatch at the output port.
윤영설,진동규,김긍년,장진우,김영수 대한스포츠의학회 1999 대한스포츠의학회지 Vol.17 No.1
Head injury is the most frequent direct cause of death in sports. Furthermore, injury to the head takes an singular importance when we realise the brain is neither capable of regeneration nor, unlike many other body parts and organs, of transplantaion. Every effort must be made to protect the athlete's head as injury can lead to dementia, epilepsy, paralysis and death. There are three distinct types of stress that can be generated by an acceleration force to the head : compressive, tensile and shearing forces. The differential diagnosis with a head injury includes cerebral concussion, intracranial hemorrhage, postconcussion syndrome, second impact syndrome, malignant brain edema. 90 to 95% of all head injuries are cerebral concussions and more than 90% all cerebral concussions fall into mild categories. With a head injury the ABCs of first aid must be followed and then a neurological examination will be followed. In the case of the intracranial hematoma. definite surgical evacuation is indicated and in cases of the closed head injuries and most severe degree of concussion. observation is appropriate, with careful neurological monitoring. Over the last 20 years there has been a dramatic decrease in the most serious head injuries due to multiple factors. There are five areas that can affect a reduction in head injuries. The first two involve rules and coaching technique changes. The other three areas involve improvements in conditioning (especially of the neck), equipment, and finally medical supervision. The reduction in incidence and severity of athletic head injury gas been the results of changes and improvements instituted following constant study and research. And also, for the reduction in incidence of athletic head injury every effort or team physician, athletic trainer, physical trainer and team coaches should be necessary.