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박병윤,이영호,이명철 大韓成形外科學會 1987 Archives of Plastic Surgery Vol.14 No.1
There are two approach methods in reduction of mandibular fracture, one is external approach and the other is intraoral approach. Most surgeon have been used external approach but intraoral approach gives many benefits. The authors performed interosseous fixation of various sites of 10 cases of mandibular fracture through intraoral approach and concluded that advantages of this method are; 1. no external scar 2. complete reduction (alignment) 3. decreased rate of malunion, maloclusion 4. fewer possibility of facial nerve injury 5. shorter operation time.
통신서비스의 늦은 수요 확산 현상에 관한 연구 : Fax 서비스를 중심으로 Focused on the Fax Markets
임병락,최문기,박명철 한국경영과학회 2002 한국경영과학회지 Vol.27 No.2
Telecommunication services are distinctive in that their adoptions are influenced by network effect resulting in 'the late take-off phenomenon' and the 'critical mass' problem. In this paper we examined, so called, 'the late take-off phenomenon' in the diffusion process of telecommunication services. We compared the parameters of the diffusion process of consumer durables with those of fax services in the US and Korea. By analyzing the parameters of a new diffusion model based on the threshold model proposed by Markus, we found that 'the late take-off phenomenon' resulted from the low heterogeneity of the threshold distribution for the potential adopters. A simulation approach was proposed for the theoretical implication of the 'critical mass' problem in the start-up telecommunications services.
Extremity CT검사 시 Cradle Angle이 피사체의 선량과 화질에 미치는 영향에 관한 연구
박병서(Byeong-seo Park),이민수(Min-su Lee),유희성(Hoe-seong Yoo),이성현(Sung-hyeon Lee),정우준(Woo-joon Jung),주명식(Myeong-sik Joo),조인완(In-wan Jo),박태현(Tae-hyeon Park) 대한CT영상기술학회 2018 대한CT영상기술학회지 Vol.20 No.1
Purpose : Correct positioning patients is the important factor for diagnosis and direction of treatment. Despite of technicians effort, it is difficult because of patients build and extremity, splint, and gips. In this study, we try to compare and analyze the effect of cradle angle on the dose and image quality in the case that the subject is correct with the center of cradle and the opposite case that subject get tilted by angle of cradle. Material and method : The phantoms used in the study were acryl phantom sized 32 cm, called body phantom and the anthropomorpic phantom (RS-114T, RS-116T Radiology Support Devices, Alderson, USA). We compared the dose and the image quality using the value measured in the three cases that the center of cradle was correct with phantom, 10 cm far to the left, and 10 cm far to the right. All evaluation of the dose was done using Kruskal-Wallis test to evaluate the significance. In case of Acryl phantom, the index of coincidence was evaluated by Intra calss correlation, ICC Result : As a result, each surface dose in the direction of 3 o clock and 9 o clock was 2.9±0.5 and 2.7±0.1 compared to the depth dose, 1.8±0.1 at the center. Using Kruskal-Wallis test, we found out there was significant result at the center and in 3 o clock and 9 o clock (0.001<p). According to the result of ICC test using Acryl phantom, there was statistically significant result by 0.915 (95 % CI=0.786~0.966) between the center and the direction of 9 c clock, and 0.991 (95 % CI=0.977~0.99) between the center and the direction of 9 o clock.In the evaluation of the dose using the anthropomorpic phantom, there was significant result from hand & wrist phantom and ankle & foot phantom by using Kruskal-Wallis test, because the measure about CTDI volume value at hand and wrist was 0.02<p, and at foot and ankle was 0.01<p. In case to evaluate image quality, SNR when the subject was correct with the center of cradle was 46.6 ±2.1, 44.6±3.4. SNR in the case that subject was 10 cm far to the left from the center of the cradle was 52.7±3.1, 50.2±1.4, and 10 cm far to the right was 42.2±2.8, 46.0±3.0. There was the significant result statistically (0.03<0.05). Also there was difference more than twice in the case that the subfect was far to the left or right compared to the alignment with center. Conclusion : In this study, it didn t matter in the dose and image quality even though the subject moved to the left or right in case of Extremity CT, but the distortion of image happened and the reproducibility of the shape got wores by the CT cradle tilted. That is the reason why the algorithm is applied using software to compensate for that. Also the appropriate instrument need to be used to raise the reproducibility of image. 목적 : Extremity CT 검사 시 올바른 환자의 위치 잡이는 진단 및 치료방향에 있어 중요한 요소이며, 좁은 cradle과 cradle angle, 환자의 체구와 양측 사지 그리고 각종 부목 (Splint), 고정붕대 (Gips) 등은 검사자의 노력에도 불구하고 적절한 환자의 자세를 잡는 데 한계가 준다. 이에 피사체가 cradle 중심에 일치한 경우와 cradle angle의 영향으로 피사체가 기울어졌을 경우의 cradle angle이 선량과 화질에 미치는 영향을 비교 분석하고자 한다. 대상 및 방법 : 실험에 사용된 팬텀은 Acryl phantom (지름 32 cm body phantom), 인체모형팬텀인 (RS-114T, RS-116T Radiology Support Devices, Alderson, USA)사용하였고, phantom의 중심부의 일치하였을 때 측정된 값과 좌측으로 10 cm, 우측으로 10 cm 이동하여 측정된 값을 이용하여 선량과 화질을 비교 하였다. 모든 선량 평가는 Kruskal-Wallis test 통해 유의성을 평가하였고, acryl phantom은 급내상관계수 (Intra calss correlation, ICC)를 이용하여 측정값의 일치도를 평가하였다. 결과 : acryl phantom을 이용한 선량평가에서는 중심부인 심부선량보다 표면선량 (3시 방향, 9시 방향)에서의 선량은 9시방향의 경우 2.7±0.1, 3시방향의 경우 2.9±0.5, 중심부인 심부선량에서는 1.8±0.1로 측정되었고 중심부와 9시 3시 방향에서 Kruskal-Wallis 검정을 통해 유의한 결과를 나타내었다 (0.001<p). acryl phantom을 이용한 선량의 ICC test결과 중심부와 9시 방향에서는 0.915 (95 % CI=0.786~0.966), 중심부와 3시에서는 0.991 (95 % CI=0.977~0.99)으로 중심부와 3시, 9시 방향에서의 측정값의 일치도는 통계적으로 유의한 결과를 나타내었다. 인체팬텀 선량 평가에서는 Hand & wrist phantom, foot & ankle 측정한 결과 중심에 일치하는 경우와 좌, 우측으로 이동한 경우 Kruskal-Wallis 검정을 통해 CTDIvol값에 대해 hand & wrist는 0.02<p, foot & ankle은 0.01<p로 유의성이 있었고, DLP 값에 대해 hand & wrist는 0.9>p로 유의성이 없는 반면 foot & ankle 0.01<p 으로 유의성을 보였다. 화질평가의 경우 cradle의 중심으로부터 일치한 경우의 SNR 46.6±2.1, 44.6±3.4이며, 좌측으로 10 cm 벗어난 경우 SNR은 52.7±3.1, 50.2±1.4, 우측으로 10 cm 벗어난 경우 SNR은 42.2±2.8, 46.0±3.0 으로 측정되었고, 통계적으로 유의한 결과를 나타내었다 (0.03<0.05). 화질의 정성적 평가에서는 4개의 항목 중에 B, D항목 (영상의 회전, 3D reformation)에서 좌, 우측으로 이동한 경우 중심정렬보다 2배 이상의 차이를 보였다. 결론 : 본 연구를 통해 Extremity CT 검사 시 피사체가 좌, 우측으로 이동하여 검사하면 선량과 화질에는 큰 영향이 없다는 결과를 나타내었지만, CT cradle의 기울기에 따라 영상의 왜곡과 형태의 재현성이 떨어지므로 이에 대한 보상으로 소프트웨어를 이용한 영상 기법을 적용 시키거나 cradle 기울기의 적절한 보상 및 보조기구의 활용을 통해 영상의 재현성을 높여야 할 것으로 생각된다.