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치아 기준의 악교정 수술용 석고모형 수술, 과연 가능하고 정확한가
이승훈,오성섭,이충국,박경란,이상휘,Lee, Seung-Hoon,Oh, Seong-Seob,Yi, Choong-Kook,Park, Kyung-Ran,Lee, Sang-Hwy 대한악안면성형재건외과학회 2011 Maxillofacial Plastic Reconstructive Surgery Vol.33 No.2
Purpose: Errors in orthognathic model surgery occur during the planning, measuring and/or moving of the models. However, there has been little effort to find ways to reduce these errors. In this study, we introduce a new orthognathic model surgery technique (Yonsei method) which adopts the tooth point as the reference and the occlusal index as a moving vehicle for the model. Methods: The technique consists mainly of: 1) measuring the three-dimensional lengths of model points, 2) fabricating and moving the occlusal index and 3) verifying the movement. Then we compared the accuracy of the Yonsei method to conventional methods, with special reference made to influencing factors. Results: Errors for the Yonsei method with the occlusal index were reduced to the range of 0.61~1.04 mm in three-dimension, providing a more accurate model surgery technique than conventional methods which have errors ranging from 0.77~3.11 mm. Conclusion: It provided us a more accurate model surgery technique based on the reference points onto the teeth and the use of occlusal index.
HVPE 법을 활용한 GaN 성장 시 질화처리에 관한 연구
이승훈,이주형,이희애,오누리,이성철,강효상,이성국,양재득,박재화,Lee, Seung Hoon,Lee, Joo Hyung,Lee, Hee Ae,Oh, Nuri,Yi, Sung Chul,Kang, Hyo Sang,Lee, Seong Kuk,Yang, Jae Duk,Park, Jae Hwa 한국결정성장학회 2019 한국결정성장학회지 Vol.29 No.4
HVPE is one of the GaN single crystal manufacturing methods which has been commercially widely used due to its high growth rate. HVPE method consists of a number of processes, in particular the nitridation of the substrate prior to GaN growth has a significant effect on the crystalline quality of the manufactured GaN single crystal. In this study, we investigated the effect of nitridation for crystalline quality of GaN when it was grown on the sapphire substrate. The whole growth conditions except for the nitridation process were the same, and the gas flow rate supplied to the sapphire substrate was variously changed during the nitridation. Here, we examined the effect of nitridation via the surface characterization of GaN single crystal grown by HVPE. HVPE는 GaN 단결정의 제조 방법 중 하나로 빠른 성장 속도가 장점인 상업적으로 널리 사용되는 성장 방법이다. HVPE 법에 의한 GaN 단결정 성장은 여러 공정으로 이루어지며, 특히 GaN 성장 전 기판의 질화 처리는 성장되는 GaN 단결정 품질에 상당한 영향을 미친다. 본 연구에서는 사파이어 기판 위에 GaN 단결정 성장 시 기판의 질화처리가 성장되는 GaN 단결정 품질에 미치는 영향을 알아보고자 하였다. 질화 처리를 제외한 다른 성장 조건은 동일하게 하였고 질화처리 시 기판에 공급되는 가스 유량을 다양하게 변화시킨 후 GaN 박막을 성장시키고, 성장된 GaN의 표면 특성평가를 통하여, HVPE 법에서의 질화처리 효과를 고찰하여 보고자 하였다.
저온 GaN의 성장 온도에 따른 에피택셜 GaN의 stress relaxation 효과
이승훈,이주형,오누리,이성철,박형빈,신란희,박재화,Lee, Seung Hoon,Lee, Joo Hyung,Oh, Nuri,Yi, Sung Chul,Park, Hyung Bin,Shin, Ran Hee,Park, Jae Hwa 한국결정성장학회 2022 한국결정성장학회지 Vol.32 No.3
이종 기판과 GaN의 물성 차이로 인해 발생하는 결함을 제어하기 위한 다양한 방법 중 동종 물질을 완충층으로 사용하는 LT-GaN 방법을 사용하여 완충층과 성장 온도의 상관성을 자체 제작한 성장 장비를 통해 확인하고자 하였다. 성장 온도에 따라 표면에 형성된 LT-GaN 결정성에 변화가 있었으며, annealing 후 LT-GaN가 나타내는 결정성에 따라 epiGaN의 응력 완화 효과에 차이점이 있었다. 반면 LT-GaN의 높은 결정성은 다결정을 형성하는 원인으로 작용하여 그 위에 성장하는 epi-GaN의 결정질을 저해하는 결과를 유발하였다.
6 MeV 전자선의 차폐물질 원자번호와 조사야 크기에 따른 선량변화 연구
이승훈,곽근탁,박주경,김양수,차석용,Lee, Seung Hoon,Kwak, Keun Tak,Park, Ju Kyeong,Gim, Yang Soo,Cha, Seok Yong 대한방사선치료학회 2013 대한방사선치료학회지 Vol.25 No.2
목 적: 본 연구에서 우리는 6 MeV 전자선의 조사야 확대에 따른 선량변화가 차폐물질 원자번호와 관계가 있음을 알아보고 그 영향인자를 분석 하고자 한다. 대상 및 방법: 먼저 평행평판형 전리함(Exradin P11)을 $25{\times}25cm^2$ 폴리스티렌 팬텀표면에 평탄하게 끼운다. 허용투과율 5% 두께의 알루미늄, 구리, 납 물질들을 팬텀 상단에 차폐시킨 후 조사야 $6{\times}6$, $10{\times}10$ 그리고 $20{\times}20cm^2$별로 측정하였다. 조사조건은 선원-표면간거리 100 cm에서 기준조사야인 $10{\times}10cm^2$에 6 MeV 전자선을 이용하여 100 cGy 조사하였다. 다음으로 MCNP (Monte Carlo N Particle Transport Code)를 이용하여 각 물질 통과 후 발생되는 광자수, 전자수, 그리고 축적에너지를 계산하였다. 결 과: 허용투과율 5% 두께에 대한 차폐물 종류에 따른 측정결과 조사야 $10{\times}10cm^2$을 기준으로 한 $6{\times}6cm^2$과 $20{\times}20cm^2$의 두께변화율은 알루미늄에서 각각 +0.06%와 -0.06%, 구리에서 각각 +0.13%와 -0.1%, 납에서 각각 -1.53%와 +1.92%였다. 계산결과 조사야 $10{\times}10cm^2$ 대비 $6{\times}6cm^2$, $20{\times}20cm^2$의 축적에너지는 차폐를 하지 않았을 경우 각각 -4.3%와 +4.85%, 알루미늄 사용 시 각각 -0.87%와 +6.93%, 구리 사용 시 각각 -2.46%와 +4.48%, 납 사용 시 각각 -4.16%와 +5.57%였다. 광자수의 경우 차폐를 하지 않았을 경우 각각 -8.95%와 +15.92%, 알루미늄 사용 시 각각 -15.56%와 +16.06%, 구리 사용시 각각 -12.27%와 +15.53%, 납 사용 시 각각 -12.36%와 +19.81%였다. 전자수의 경우 차폐를 하지 않았을 경우 각각 -3.92%와 +4.55%, 알루미늄 사용 시 각각 +0.59%와 +6.87%, 구리 사용 시 각각 -1.59%와 +3.86%, 납 사용 시 각각 -5.15%와 +4.00%였다. 결 론: 본 연구로 조사야 증가함에 따른 차폐물 두께가 저 원자번호에서 감소하며, 고 원자번호에서는 증가함을 볼 수 있었으며, 계산을 통해 저 원자번호물질에서는 저지방사선, 고 원자번호물질에서는 산란전자가 영향을 주는 것을 알 수 있었다. Purpose: In this study, we analyzed how the dose change by field size effects on atomic number of shielding materials while using 6 MeV election beam. Materials and Methods: The parallel plate chamber is mounted in $25{\times}25cm^2$ the phantom such that the entrance window of the detector is flush with the phantom surface. phantom was covered laterally with aluminum, copper and lead which thickness have 5% of allowable transmission and then the doses were measured in field size $6{\times}6$, $10{\times}10$ and $20{\times}20cm^2$ respectively. 100 cGy was irradiated using 6 MeV electron beam and SSD (Source Surface Distance) was 100 cm with $10{\times}10cm^2$ field size. To calculate the photon flux, electron flux and Energy deposition produced after pass materals respectively, MCNPX code was used. Results: The results according to the various shielding materials which have 5% of allowable transmission are as in the following. Thickness change rate with field size of $6{\times}6cm^2$ and $20{\times}20cm^2$ that compared to the field size of $10{\times}10cm^2$ found to be +0.06% and -0.06% with aluminum, +0.13% and -0.1% with copper, -1.53% and +1.92% with lead respectively. Compare to the field size $10{\times}10cm^2$, energy deposition for $6{\times}6cm^2$ and $20{\times}20cm^2$ had -4.3% and +4.85% respectively without shielding material. With aluminum it had -0.87% and +6.93% respectively and with lead it had -4.16% and +5.57% respectively. When it comes to photon flux with $6{\times}6cm^2$ and $20{\times}20cm^2$ of field sizes the chance -8.95% and +15.92% without shielding material respectively, with aluminum the number -15.56% and +16.06% respectively and with copper the chance -12.27% and +15.53% respectively, with lead the number +12.36% and -19.81% respectively. In case of electron flux in the same condition, the number -3.92% and +4.55% respectively without shielding material respectively, with aluminum the number +0.59% and +6.87% respectively, with copper the number -1.59% and +3.86% respectively, with lead the chance -5.15% and +4.00% respectively. Conclusion: In this study, we found that the required thickness of the shielding materials got thinner with low atomic number substance as the irradiation field is increasing. On the other hand, with high atomic number substance the required thickness had increased. In addition, bremsstrahlung radiation have an influence on low atomic number materials and high atomic number materials are effected by scattered electrons.
탄소 기반의 고주파 나노 역학 공진기의 제작 및 동역학적 특성에 대한 연구
이승훈(Seung Hoon Lee),민범기(Bumki Min),이광철(Kwang-Cheol Lee),박세일(Se Il Park),이승섭(Seung S. Lee) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
Nanomechanical resonators have attracted much attention in the last decade due to superior performance with high sensitivity and high oscillation frequency. In this paper, we propose carbon-based high frequency nanomechanical resonators by utilizing pyrolyzed carbon layers with embedded single walled carbonnanotube (swCNT) layers. SwCNTs are used as a reinforcement material and also lower the density of the resonator. Dynamic behaviors of the fabricated resonators, including fundamental frequency, Q-factor, and frequency tuning characteristics were investigated using magnetomotive dynamic flexural measurements. We believe that the carbon-based nanomechanical resonators have promising applications in sensitive nanodevices with low power consumption. These materials are also ideal because of the low-cost batch processing capability and could be an alternative for silicon-based nanodevices.
위선암 환자의 말초혈액에서 역전사 중합효소 연쇄반응을 이용한 Cytokeratin 20 양성 미세 전이 암세포의 진단
이승훈(Seung Hoon Lee),진종률(Jong Youl Jin),송치원(Chi Won Song),이희진(Hee Jin Lee),박재후(Jae Hoo Park),박영세(Young Se Park),백창렬(Chang Nyol Paik),우영식(Yeong Sik Woo),김희정,김춘추(Chun Choo Kim),이준욱(Joon Wook Lee) 대한내과학회 2001 대한내과학회지 Vol.60 No.6
N/A Background : The development of metastasis in cancer is one of the main problems after primary tumor resection. The identification of metastases is only possible in the follow-up investigation when there is already a solid tumor mass. Subclinical tumor cell dissemination can be detected by immunocytological staining of cells or by other molecular biological methods, like PCR. We investigated 22 peripheral blood isolates from gastric cancer patients with a cytokeratin (CK) 20 specific nested reverse transcriptase PCR (RT-PCR) for the detection of disseminated tumor cells at the time of diagnosis. Methods : Fresh heparinized peripheral bloods (about 10 mL) were obtained from 22 gastric cancer patients and 10 healthy doctors as controls. Nucleated cells were isolated by a density gradient method. RNA was isolated and then subjected to RT-PCR with CK 20 specific primers. Results : In gastric cancer, 3 of 22 (13.6%) peripheral blood isolates yielded a CK 20 mRNA positive result in a stage undependent manner. Conclusion : We detected disseminated tumor cells in the peripheral blood isolated using CK 20 specific nested RT-PCR method. Studies on a larger scale are needed for further investigation on the relationship between positive rates of CK 20 mRNA and survival rates of stomach cancer, according to cancer stages.(Korean J Med 60:514-520, 2001)