고령에서 발현한 척수외 혈관모세포종 - 증 례 보 고 -

김영우,김재건,유도성,허필우,조경석,김달수,강준기,Kim, Young Woo,Kim, Jae Keon,Yoo, Do Sung,Huh, Phil Woo,Cho, Kyuong Suck,Kim, Dal Soo,Kang, Joon Ki 대한신경외과학회 2001 Journal of Korean neurosurgical society Vol.30 No.2

Intradural extramedullary hemangioblastoma of the spinal cord is uncommon tumor. Symptom onset is typically in the forth decade. Complete excision offers the best chance for cure. We report a case of extramedullary hemangioblastoma of the spinal cord in old age. A 76 -year old man presented with 1 month history of paraparesis. Multiple enhancing lower thoracic and lumbar spinal masses were seen on magnetic resonance imaging(MRI). Surgical exploration for symptomatic lesion revealed intradural-extramedullary mass, which had hypervascularity. The excised spinal masses were diagnosed as hemangioblastoma. Postoperative course was uneventful and symptoms improved gradually.

AlN-Al₂O₃ 계에서의 상압소결 질화물복합체

김영우,김규헌,김동현,윤석영,박홍채,Kim, Young Woo,Kim, Kyu Heon,Kim, Dong Hyun,Yoon, Seog Young,Park, Hong Chae 한국세라믹학회 2014 한국세라믹학회지 Vol.51 No.5

Particulate nitride composites have been fabricated by sintering the compacted powder of AlN and 5 - 64.3 mol% $Al_2O_3$, with a small addition of $Y_2O_3$ ($Y_2O_3$/AlN, 1 wt%), in 1-atm nitrogen gas at $1650-1900^{\circ}C$. The composites were characterized in terms of sintering behavior, phase relations, microstructure and thermal shock resistance. AlN, 27R AlN pseudopolytype, and alminium oxynitride (AlON, $5AlN{\cdot}9Al_2O_3$) were found to existin the sintered material. Regardless of batch composition, the AlN-$Al_2O_3$ powder compacts exhibited similar sintering behavior; however, the degree of shrinkage commonly increased with increasing $Al_2O_3$ content, consequently giving high sintered bulk density. By increasing the $Al_2O_3$ addition up to ${\geq}50 mol%$, the matrix phase in the sintered material was converted from AlN or 27R to AlON. Above $1850^{\circ}C$, a liquid phase was formed by the reaction of $Al_2O_3$ with AlN, aided by $Y_2O_3$ and mainly existed at the grain boundaries of AlON. Thermal shock resistance was superior in the sintered composite consisting of AlON with dispersed AlN or AlN matrix phase.

두개골 성형술의 사용 재료와 수술 시기에 따른 감염율

김영우,유도성,김달수,허필우,조경석,김재건,강준기,Kim, Young-Woo,Yoo, Do-Sung,Kim, Dal-Soo,Huh, Pil-Woo,Cho, Kyung-Suck,Kim, Jae-Gun,Kang, Joon-Ki 대한신경외과학회 2001 Journal of Korean neurosurgical society Vol.30 No.2

Objective : Cranioplasty is required to protect underlying brain, to correct major aesthetic deformities, or both. The ideal material for this purpose is autogenous bone. When this is not available, alloplastic or artificial materials may be used. In this study authors compared the infection rate according to the cranioplasty materials(the frozen autologous bone vs. bone cement), and duration of the skull defect. Materials : Between May 1994 and December 1999, 111 patients with skull defect treated with cranioplasty(82 cases of frozen autologous bone and 29 cases of artificial bone material) were included in this study. There were 77 males and 34 females with a mean age of 41.4 years(range 1-85 years). 57 patients had head trauma and 54 had non-traumatic insults. According to the duration of skull defect, there were 28 cases under 1 month, 33 cases of 1-2 months, 15 cases of 2-3 months, 20 cases of 3-6 months and 15 cases over 6 months of duration. Results : Overall infection rate was 9.9%. In cases with frozen autologous bone and artificial bone material, the infection rate was 8.5% and 13.7%, respectively. The infection rate according to the duration of skull defect was 3.6%(among 28 cases) under 1 month of age, while those were 12%(4 among 33 cases) at 1-2 months, 20%(3 among 15 cases) at 2-3 months, 5%(1 among 20 cases) at 3-6 months and 13%(2 among 15 cases) over 6 months. Accoring to the underlying disease, the infection rate in traumatic cases was 12%(7 among 57 cases) and that in non-traumatic one was 3.7%(2 among 54 cases). Conclusion : From this study, it appears that skull defect should be repaired as soon as possible, because early cranioplasty can lower the infection rate. And surgeons could save the patients' cranial bone as possible as they can because autologous bone is not only cost effective in cosmatic purpose but lower the infection rate.

'87우리나라 과학기술발전에의 기대-산업기술개발

김영우,Kim, Yeong-U 한국과학기술단체총연합회 1987 과학과 기술 Vol.20 No.2

세계 슈퍼컴퓨터 연구정책 현황

김영우,김성운,최완,Kim, Y.W.,Kim, S.W.,Choi, W. 한국전자통신연구원 2011 전자통신동향분석 Vol.26 No.6

최근 수년간 슈퍼컴퓨터 분야에서 중국과 일본은 막강한 자본력과 인적 자원에 힘입어 급격한 발전을 거듭하여, 2010년 중국이 세계 슈퍼컴퓨터 1위를 차지하고 이어서 2011년 일본이 이를 다시 추월함으로써 슈퍼컴퓨터 분야에서 세계적인 경쟁우위를 확보하게 되었다. 이와 같은 국내외적인 추세에 따라, 최근 한국 내에서도 슈퍼컴퓨터에 대한 관심이 늘고 있는 추세이다. 슈퍼컴퓨터 기술은 컴퓨터 시스템 및 관련 소프트웨어의 최첨단 기술이 종합된 기술로 한 국가의 기술력을 판단할 수 있는 기술 분야의 하나로써, 전 세계적으로 슈퍼컴퓨터 기술은 이미 Petaflops 시대를 시작하였으며, Exaflops 시대로 진행 중에 있다. 국내의 경우는 생활에 밀착된 IT 정보기술 분야에 집중하여 연구개발을 진흥함에 따라, 슈퍼컴퓨터 관련 기술의 수준이 경제 수준에 비하여 상대적으로 낮은 것으로 평가되고 있다. 본 고에서는 슈퍼컴퓨팅 기술개발 정책 및 연구방향에 도움이 되고자, 슈퍼컴퓨팅 기술과 관련한 세계 각국 및 한국의 연구정책 동향과 기술개발 현황을 알아보도록 한다.

Monitoring circulating tumor DNA by analyzing personalized cancer-specific rearrangements to detect recurrence in gastric cancer

김영우,Young-Ho Kim,송유라,Han-Seong Kim,심혜원,Shiv Poojan,엄방울,Myeong-Cherl Kook,주정남,홍경만 생화학분자생물학회 2019 Experimental and molecular medicine Vol.51 No.-

Circulating tumor DNA (ctDNA) has emerged as a candidate biomarker for cancer screening. However, studies on the usefulness of ctDNA for postoperative recurrence monitoring are limited. The present study monitored ctDNA in postoperative blood by employing cancer-specific rearrangements. Personalized cancer-specific rearrangements in 25 gastric cancers were analyzed by whole-genome sequencing (WGS) and were employed for ctDNA monitoring with blood up to 12 months after surgery. Personalized cancer-specific rearrangements were identified in 19 samples. The median lead time, which is the median duration between a positive ctDNA detection and recurrence, was 4.05 months. The presence of postoperative ctDNA prior to clinical recurrence was significantly correlated with cancer recurrence within 12 months of surgery (P = 0.029); in contrast, no correlation was found between cancer recurrence and the presence of preoperative ctDNA, suggesting the clinical usefulness of postoperative ctDNA monitoring for cancer recurrence in gastric cancer patients. However, the clinical application of ctDNA can be limited by the presence of ctDNA non-shedders (42.1%, 8/19) and by inconsistent postoperative ctDNA positivity.

Mg-Li-Al(- Zr) 합금의 연화현상

김영우,황영하,임용진,김도향,홍준표 ( Y . W . Kim,Y . H . Kwang,Y . J . Lim,D . H . Kim,C . P . Hong ) 한국열처리공학회 1998 熱處理工學會誌 Vol.11 No.1

The softening behavior of squeeze cast Mg-Li-Al and Mg-Li-Al-Zr alloys have been investigated. The highest hardness values of Mg-Li-Al and Mg-Li-Al-Zr alloys were obtained after solution treatment at 400℃ for 1 hour. The hardness value, however, decreased as the aging temperature and time increased. Microstructural and calorometric analyses showed that quenched-microstructure changed from primary (α and β)+secondary α to primary(α and β)+secondary α+θ after aging. The softening during aging was due to the coarsening of θ precipitates.

열분석법에 의한 Mg-8.5Li-4.5Al합금의 시효거동 연구

김영우,황영하,박태원,김도향,홍준표 ( Y . W . Kim,Y . H . Hwang,T . W . Park,D . H . Kim,C . P . Hong ) 한국열처리공학회 1997 熱處理工學會誌 Vol.10 No.4

Precipitation and strengthening mechanisms in squeeze cast Mg-8.5wt%Li-4.5wt%Al have been investigated by differential scanning calorimetry(DSC), scanning electron microscopy(SEM), in-situ and ex-situ X-ray diffraction analysis and hardness measurement. Special emphasis was placed on the investigation of the precipitation behavior by the DSC technique. Microstructural and calorimetric analysis showed that θ and δ precipitates in the b.c.c. β phase matrix, forming two exothermic peaks at the temperature ranges of 130℃∼180℃ and 236℃∼280℃. θ and δ dissolve into the matrix forming an endothermic peak at the temperature range of 280℃∼352℃. The as-cast microstructure consists of α, β and δ. Peak strength was obtained after aging for 1 hour at 50℃. The aging time required for the peak strength decreased as the aging temperature increases. The hardness decrease during overaging was due to the coarsening of θ precipitates. Microhardness measurement showed that variation of the hardness of β matrix was more pronounced than that of the α phase, indicating that the β phase is more responsible for the strengthening of the Mg-8.5wt%Li-4.5wt%Al alloy.

가변 CSD 계수를 이용한 저전력 디지털 필터의 설계

김영우,유재택,김수원,Kim, Yeong-U,Yu, Jae-Taek,Kim, Su-Won 대한전자공학회 2001 電子工學會論文誌-SD (Semiconductor and devices) Vol.38 No.7

In this Paper, an approximate processing method is proposed and tested. The proposed method uses variable CSD (VCSD) coefficients which approximate filter stopband attenuation by controlling the precision of the CSD coefficient sets. A decimation filter for Audio Codec '97 specifications has been designed having processor architecture that consists of program/data memory, arithmetic unit, energy/level decision, and sinc filter blocks, and fabricated with 0.6${\mu}{\textrm}{m}$ CMOS sea-of-gate technology. For the combined two halfband FIR filters in decimation filter, the number of addition operations were reduced to 63.5%, 35.7%, and 13.9%, compared to worst-case which is not an adaptive one. Experimental results show that the total power reduction rate of the filter is varying from 3.8 % to 9.0 % with respect to worst-case. The proposed approximate processing method using variable CSD coefficients is readily applicable to various kinds of filters and suitable, especially, for the speech and audio applications, like oversampling ADCs and DACs, filter banks, voice/audio codecs, etc. 본 논문에서는 많은 연산을 필요로 하는 디지털 필터의 저전력화를 위한 새로운 저전력 기법을 제안한다. 제안된 저전력 기법에서는 CSD (canonic signed digit)숫자의 유효 표현 범위를 결정하는 nonzero digit 와 ternary digit의 값에 따른 필터의 차단대역 특성 변화를 이용하여, 다단계의 필터 차단 대역 특성을 가지는 가변 CSD 계수를 얻고 이를 approximate processing 기법에 적용하였다. 제안된 저전력 필터 설계기법의 성능을 확인하기 위하여 4개의 필터 차단대역 특성을 사용하는 AC '97 과표본화 ADC용 decimation 필터의 설계에 적용하였다. Decimation필터 중 제안된 저전력 기법을 적용한 두 half-band 필터의 연산량은 제안된 기법을 적용하지 않은 경우에 비해 각각의 근사화 수준에서 단위 출력 샘플 당 63.5, 35.7, 13.9 %의 덧셈 연산만을 수행하여 필터의 출력을 얻을 수 있었다. Decimation 필터는 0.6㎛ CMOS SOG 라이브러리를 사용하여 제작·실험하였으며, 실험결과 입력 신호의 attenuation에 따라 전체 소모전력의 약 3.8 %에서 9 %의 소모전력이 감소되었음을 확인하였다. 제안된 가변 CSD 계수를 이용한 approximate processing 방식은 특히 음성 대역 및 오디오 대역의 신호처리와 과표본화 ADC/DAC의 decimation/interpolation과 같은 multirate 시스템에 적합하다.

$\textrm{Al}_2\textrm{O}_3$를 함유하는 AIN세라믹스의 반응소결 및 열전도도

김영우,이윤복,박상희,오기동,박홍채,Kim, Yeong-U,Lee, Yun-Bok,Park, Sang-Hui,O, Gi-Dong,Park, Hong-Chae 한국재료학회 1998 한국재료학회지 Vol.8 No.1

5-64.3mol% AI$_{2}$O$_{3}$를 함유하는 AIN(1wt% $Y_{2}$O$_{3}$)의 1650-190$0^{\circ}C$ 상압소결에 따른 치밀화 거동, 미세구조, 열전도도가 검토 되었다. XRD 분석결과, AION(5NIN \ulcorner9 AI$_{2}$O$_{3}$ ), 27R AIN다형, AIN이 소결체의 주상으로서 동정되었다. AI$_{2}$O$_{3}$ 의 함량이 증가할수록 소결체의 부피밀도는 증가 하였다. AION을 기지상으로 하는 물질($\geq$ 30mol% AI$_{2}$O$_{3}$ )인 경우는 175$0^{\circ}C$ 소결에서 최대의 부피밀도를 나타내었으며, AIN을 기지상으로 하는 경우(5mol% AI$_{2}$O$_{3}$ ) 는 소결온도가 증가할수록 밀도가 감소하였다. $Y_{2}$O$_{3}$의 존재하에서 주로 185$0^{\circ}C$이상에서 AI$_{2}$O$_{3}$ 와 AIN의 반응에 으해서 액상이 생성되었다. AION을 기지로 하는 물질의 치밀화는 주로 액상의생성 및 AION의 입성장에 의해서 지배되었으나, AIN을 기지로 하는 물질에 있어서는 1$650^{\circ}C$에서 액상이 생성되었고, 소결온도가 190$0^{\circ}C$까지 상승할 동안 AIN의 입성장은 크게 일어나지 않았다. AI$_{2}$O$_{3}$ 함량이 증가할수록 낮은 열도도를 갖는 다량의 AION 및 액상의 생성으로 인하여 소결체의열전도도는 감소 하였다. 5mol% AI$_{2}$O$_{3}$ 를 함유한 190$0^{\circ}C$ 소결체가 최대의 열전도도(77.9W/(m\ulcornerk))를 나타내었다.