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최세환,김기용 서울産業大學校 2001 논문집 Vol.52 No.1
A new multi-step voltage source inverter is proposed in this paper. The proposed scheme is composed of the double-connected 12-step inverter with an auxiliary circuit. The auxiliary circuit includes two voltage dividing capacitors, four switching devices and a low kVA autotransformer. The resultant system is shown to be a 36-step inverter suitable for large scale SVC applications in which the PWM method can not be employed. The design parameters are derived from the analysis of voltages and currents by means of switching functions. The simulation results verify the proposed concept.
최세환,백민우,조경석,최창락,지영희 대한신경외과학회 1990 Journal of Korean neurosurgical society Vol.19 No.7
We reported a case of huge cystic trigeminal neurinoma. The patient was 35 year old female with trigeminal nerve dysfunction and hemiparesis. The computed tomography disclosed a huge cystic low density mass at the temporal base and suprasellar cistern that extended to cerebellopontine cistern through the tentorium, and enlargement of Meckel's cave on coronal scan. Through the infratemporal and retromastoid suboccipital approach, the cystic content was aspirated and cyst wall was removed. The cystic change of neurinoma may be due to mucoid degeneration and liquifaction.
최세환,김보현,정도관,신홍식,주종남 한국공작기계학회 2006 한국공작기계학회 추계학술대회논문집 Vol.2006 No.-
Micro machining of tungsten carbide by electrochemical machining(ECM) was studied. In ECM, machining conditions and electrolyte should be chosen carefully according to the property of workpiece materials. In this paper, sulfuricacid and nitric acid were used for tungsten carbide machining and machining characteristics were investigated according to machining conditions such as electrolyte, workpiece potential and applied pulse voltage. By using mixture of sulfuric acid and nitric acid, micro structures with sharp edge and good surface quality were obtained. Micro electrochemical turning was also introduced to fabricate micro shafts.
최세환,홍용길,박영섭,이상원,강준기,최창락,윤상민 대한신경외과학회 1991 Journal of Korean neurosurgical society Vol.20 No.1-3
A case of sphenoid sinus mucoceles that also partially involved posterior ethmoid and frontal sinuses is described. Diplopia following severe headache of sudden onset developed to 43 year old man. MRI revealed high signal intensity either on T₁WI and on T₂WI. The mucoceles of sphenoid sinus and ethmoid sinus were removed by transnasal simple drainage and the postoperative result was satisfactory.
최세환,나형균,이길송,안명수,최창락,송진언 대한신경외과학회 1988 Journal of Korean neurosurgical society Vol.17 No.6
We have operated on 40 patients with radiculopathy and myelopathy with cervical ossification of posterior longitudinal ligament(OPLL) within recent 4 years. The age of patient at operation was from 4th decade to 8th decade, with the largest number in the 6th decade. Three times more men than women were affected. The surgical technique was selected in most cases on the basis of radiological findings. 26 patients underwent anterior approach by transuncal discal approach(TUD) and vertebrotomy. 14 patients underwent posterior approach by laminectomy and widening laminoplasty. Outcome of operation was generally good. Of 40 patients, 32 cases were in the excellent or good results. A short duration of symptoms before operation was associated with better results, but there not influenced by the age of the patients. In selection of operative method, we suggest that 1) Anterior approach is a better method in case of the patient whose lesion is limited at one of two levels without any narrow spinal canal, 2) In case having a lesion more than two levels and especially accompaning multiple canal stenosis, posterior approach may be effective, and widening laminoplasty is a better method than extensive laminectomy which could be complicated with postoperative spinal instability, scar formation at operation area, and abnormal curvature of the cervical spine.
최세환,김광일 한국화재소방학회 1993 한국화재소방학회논문지 Vol.7 No.2
The flash point for flammable liquids (alcohol, aromatic compounds) were measured by Penskt-Martens's measuring apparatus with closed cup. As a result, it was observed that the flash points had the regular tendency according to the carbon number and the molecular structure. Consequently, the flash point for the alcohols were increased in proportion to the increase of the carbon number and branch number. The differences between the literature and experimental data are 14.6% for the relative error and 3.46<TEX>$^{\circ}C$</TEX> in average for the measuring temperature.
다층 액정폴리머 기판을 이용한 Ka대역 탐색기용 송수신 모듈
최세환,유종인,이재영,이지연,남병창,Choi, Sehwan,Ryu, Jongin,Lee, Jaeyoung,Lee, Jiyeon,Nam, ByungChang 한국인터넷방송통신학회 2020 한국인터넷방송통신학회 논문지 Vol.20 No.5
본 논문에서는 35 GHz 대역의 군 탐색기용 송수신 모듈을 설계 및 제작하였다. 밀리미터파 대역의 기판 성능과 집적도를 높이기 위해, 4층 액정 폴리머 기판을 개발하였다. 4층 액정 폴리머 기판은 3장의 FCCL 기판과 2장의 접착층으로 구현되었으며, 적층을 위해 기판간의 녹는 점 차이를 이용한 공정을 이용하였다. 스트립선로와 마이크로스트립 선로를 이용하여 기판의 길이에 따른 전송손실을 확인하였고, 35 GHz 대역의 전력분배기를 통해 액정폴리머 기판의 성능을 검증하였다. 이러한 기판을 이용하여 전력증폭기와 저잡음증폭기와 같은 송수신모듈을 구성하는 개별 블록에 대한 성능을 확인한 후, 단일 채널 Ka대역 송수신모듈을 4층 액정 폴리머 기판을 이용하여 개발하였다. 제작한 송수신모듈의 송신출력은 펄스 Duty 10%에서 1.1W 이상, 수신 잡음지수는 8.5 dB 이하, 수신 이득은 17.6 dB 이상의 수신 특성을 갖는다. In this paper, the transmit-receive module for military seekers has been designed and fabricated in 35 GHz. To increase the performance of substrates and high integration of circuits in millimeter-wave band, a 4-layer LCP(Liquid Crystal Polymer) substrate was developed. This substrate was implemented with three FCCL substrates and two adhesive layers, and a process using the difference in melting point between the substrates was used for lamination. Using a strip line and a microstrip line was confirmed by the transmission loss along the length of the substrate, and the performance of LCP substrates was validated with a power divider in 35 GHz. After confirming the performance of individual blocks such as power amplifier and low noise amplifier, a single channel Ka-band transmission/reception module was developed using a 4-layer liquid crystal polymer substrate. The transmit power of this module has above 1.1W in pulse duty 10% and has an output power of 1.1W and it has receive noise figure less than 8.5 dB and receive gain more than 17.6 dB.