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경막외 스테로이드 주사(Epidural Steroid Injection : ESI) 시 C-arm의 두 가지 측방향에서 시술자의 피폭선량 평가
김현우(Hyeon-Woo Kim),심재민(Jae-Min Shim),정태섭(Tae-Seob Jeong),송창욱(Chang-Wook Song),방용식(Yong-Sik Bang) 대한인터벤션영상기술학회 2020 대한인터벤션영상기술학회지 Vol.23 No.1
목적 : 경막외 스테로이드 주사 시 C-arm 장비의 tube 위치에 따른 두 가지 측방향에서 시술자의 피폭선량을 평가해보고자 하였다. 대상 및 방법 : RS-113(Pelvis) 팬텀을 대상으로 Philips사의 Allura Xper FD 20 방사선 발생장치와 Unfors Xi 선량계를 이용하였다. 환자가 엎드린 자세를 기준으로 tube의 위치에 따라 Right tube, Left tube로 구분하였으며 측정 위치로는 대한민국 남성 평균 신장인 170 cm를 기준으로 눈(지면으로부터 160 cm높이), 흉부(지면으로부터 130 cm높이), 손(다섯 번째 허리뼈 위)의 위치로 지정하였다. 시술 시와 동일한 기하학적 구조를 유지한 상태로 tube의 위치와 측정 위치에 따라 선량계를 장축과 평행하게 위치시켜 0°(360°), 90°, 180°, 270° 모든 방향에서 각각 20회씩 측정하였다. Right tube에서 측정된 선량과 Left tube에서 측정된 선량을 통계학적 유의성 검정을 위해 독립표본 t검정으로 유의한 차이를 분석하였다. 결과 : Right tube의 경우 모든 방향에서 측정된 총 선량은 눈의 위치에서 평균 0.27 mR, 흉부 위치에서 평균 0.57 mR로 측정되었다. Left tube의 경우 눈의 위치에서 평균 0.09 mR, 흉부위치에서 평균 0.05 mR로 측정되었다. 그리고 LL5(Left Lumbar 5) 위의 손 위치에서 측정된 총 선량의 경우 Right tube에서 평균 96.76 mR, Left tube에서 평균 136.65 mR로 측정되었다. RL5(Right Lumbar 5) 위 손의 위치에서는 Right tube에서 평균 194.79 mR, Left tube에서 평균 76.1 mR로 측정되었다. 결론 : Right tube와 Left tube 시 각 위치에서의 선량 측정 결과 모든 측정 위치에서 유의한 차이가 있었다. 눈과 흉부의 위치에서는 차폐체에 의해 Left tube일 때 시술자가 받는 선량이 더 적은 것을 확인하였으며 손의 위치에서는 Right tube일 때 측정된 선량이 적은 것을 확인하였다. 이를 통해 시술하고자 하는 부위와 tube 사이의 거리가 멀수록 선량이 적은 것을 알 수 있었다. Purpose : To reduce the exposure dose received by the operator in Epidural Steroid Injection, we wanted to compare the dose in two directions depending on the tube position of the C-arm equipment. Materials and Methods : The RS-113(Pelvis) phantom was used with Allura Xper FD 20 radiation generator and the Unfors Xi dosimeter from Philips. Right tube and Left tube was divided according to the location of the tube based on the patient"s prone position, and the measurement area was eye(160 cm height from ground), chest(130 cm height from the ground), and hand(above the 5th Lumbar) location which were based on the average height of 170 cm for men in Korea. Dose was measured 20 times each in all directions at 0°(360°), 90°, 180° and 270°, parallel to the long axis, depending on the location of the tube and the specified area. The significant difference between the measured dose on the Right tube and on the Left tube was analyzed by the independent t-test analysis for statistical significance. Result : For the Right tube, the total dose measured in all directions was measured on average 0.27 mR in the eye and 0.57 mR in the chest. In the case of the Left tube, it was measured on average 0.09 mR in the eye and 0.05 mR in the chest. And for the total dose received by the operator"s hand at LL5(Left Lumbar 5) position, the average was 96.76 mR on the Right tube and 136.65 mR on the Left tube. At the RL5(Right Lumbar 5) position, the average was 194.79 mR on the Right tube and 76.1 mR on the Left tube. Conclusion : Dose measurements at each position during the Right tube and Left tube showed significant differences in all measurement positions. In the location of the eye and chest, it was measured that the operator received less doses by the shield when the tube located left. In the position of the hand, the longer the distance between the procedure area and the tube, the lesser dose was measured. It is considered that using a more specific dose measurement method by referring to these results will help in the study of reducing exposure dose for the operator.
김현우(Hyeon Woo Kim),이유식(You-sik Lee),남유진(Yujin Nam) 대한설비공학회 2021 설비공학 논문집 Vol.33 No.2
In case of a fire in a large volume space, the localization of smoke through a smoke control system is essential. However, in korea, the installation standard of the smoke reservoir screen in large volume space is insufficient. Therefore, this study was conducted in order to analyze smoke control effect in large volume space. The three numerical analyzation is conducted smoke diffusion time according to depth of screen, smoke diffusion time in the change of distance from fire source, smoke diffusion time in the change of height with a fire simulation, FDS. As the result, depth of the screen became deeper, the absolute value of the smoke control effect increased, but the increase in the delay effect of smoke delayed gradually compared to the increase in depth.
과학 : 가속되는 파원으로부터 발진하는 음파의 도플러 효과
김현우 ( Hyeon Woo Kim ),허예훈 ( Ye Hoon Heo ),한상욱 ( Sang Wook Han ) 전북대학교 과학교육연구소 2014 과학과 과학교육 논문지 Vol.39 No.2
움직이는 물체가 발진하는 파동은 관측자와의 상대적인 운동에 따라서 원래 파동의 떨기수보다 크거나 작게 느끼는 것을 도플러 효과라고 한다. 등속도 운동하는 파원으로부터 관측된 파의 떨기수 변화는 도플러효과 이론값과 정확히 일치한다. 가속되는 파원으로부터 발진되는 파동의 도플러효과도 등속도 운동하는 도플러효과 이론식을 이용하여 정확히 예측할 수 있다. 가속되는 파원으로부터 발진하는 음파의 떨기수는 다양한 속력의 파원이 발진한 음파의 떨기수의 합으로 나타났다. The Doppler effect describes an observed frequency change depending on a relative movement between a source and an observer. Observed frequencies of sounds generated from a source with a constant speed can be precisely estimated by using the Doppler effect theory. We measured frequency changes from an accelerated source and compared them with theoretical calculations using the Doppler effect theory. From the measurements, we found that observed frequencies were the summation of total frequencies emitted from a sound source at different speeds.
김현우(Hyeon-woo Kim),이수정(Su-jeong Lee),송영화(Yeong-wha Sawng) 한국창업학회 2016 한국창업학회 Conferences Vol.2016 No.3
This paper is based on the innovation ecosystem stake holder model by MIT Sloan. It is a model to analyze an ecosystem of startup and innovation cluster. Since 2000, global economy has been experienced digital economy and many ICT focused clusters has been emerged as Jerusalem of innovation and startup. Pangyo techno-valley is assessed as a desirable cluster of IT and related industries. Also, Techcity in London is emerging as an herb for startups and innovators in Europe, which was ranked the best city for entrepreneurs(European Digital City Index,2015). According to the innovation ecosystem stake holder model, five factors are vital to organize startup ecosystem- entrepreneur, company & firm, risk capital, government, university. We figured out Techcity is a well developed, balanced ecosystem for startup and innovation. In contrasts, Pangyo is assessed to have a weakness in university factor. This vulnerable point should be reinforced by partnership or collaborative research with p restigious universities around Seoul and Gyeonggi-do Province.
5알파 환원효소억제제 복용 후 혈중 전립선특이항원의 변화
김현우(Hyeon Woo Kim),하홍구(Hong Koo Ha) 대한비뇨기종양학회 2012 대한비뇨기종양학회지 Vol.10 No.2
The aim of this review is to provide a discussion of serum prostate specific antigen (PSA) after use of 5α-reductase inhibitors (5αRIs). The 5αRIs that are used to treat benign prostatic hyperplasia may reduce operation risks and acute urinary retention. However, it causes alteration of serum PSA level requiring clinician’s attention. After two large studies, Prostate Cancer Prevention Trial (PCPT) and Reduction by Dutasteride of Prostate Cancer Events (REDUCE) study, many literatures has showed that 5αRI reduces the prevalence of prostate cancer, especially in low grade cancer. However, the incidence of high grade prostate cancer increased in 5αRI group than placebo group. Recently, some authors revealed that serum PSA sensitivity to prostate cancer increased in the 5αRIs arm than placebo using serum PSA doubling rule, serum PSA density and increasing serum PSA after nadir level. The serum PSA is usually doubled in patients with 5αRIs more than 12 months because these decrease serum PSA level down to approximately 50% at 1 year compared to baseline. It seems to be such a simple method but may yield serum PSA overestimation during first 6 months and underestimation after 4 years of the use of 5αRIs. Some authors have reported serum PSA density is useful in increasing sensitivity to prostate cancer after 1 year use of 5αRI that reduce serum PSA noising effect of benign prostatic hyperplasia. Recently, increasing serum PSA after nadir level has been seemed to be an attractive method to detect prostate cancer in patients with use of 5αRIs.
기업생태계 관점에서의 클러스터 분석 : 판교와 런던을 중심으로
김현우(Kim, Hyeon-woo),이수정(Lee, Su-jeong),송영화(Sawng, Yeong-wha) 한국창업학회 2017 한국창업학회지 Vol.12 No.1
This study is a meaningful study that derived the implications of ecosystem cycle from macroscopic environmental analysis of Pangyo Techno Valley and London Tech City, which are specialized clusters of ICT industry, which have been actively involved in the fusion and merger. As a result of the macroeconomic analysis, both Pangyo and London showed more than industrial districts, which were matched to the ecosystem development cycle, and suggested implications for fostering, maintaining and developing the cluster. In addition, as implications for cluster development, it is necessary to develop cluster-wide growth through co-evolution, open networks and the need for collaborative research among industry, academia, and research, suggestions for benchmarking overseas excellent cases.