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TSDC 방법을 이용한 AC 폴링된 PMN-PT 단결정의 디폴링 메커니즘 분석
이건주 ( Geon-ju Lee ),김황필 ( Hwang-pill Kim ),이상구 ( Sang-goo Lee ),이호용 ( Ho-yong Lee ),조욱 ( Wook Jo ) 한국센서학회 2020 센서학회지 Vol.29 No.1
Currently, increasing attention is being paid to relaxor-based ferroelectric single crystals in photoacoustic images, especially for highend applications. Among the crystals are (1-x)Pb(Mg<sub>1/3</sub>Nb<sub>2/3</sub>)O<sub>3</sub>-xPbTiO<sub>3</sub> (PMN-100xPT) single crystals located near their morphotropic phase boundary (x = 0.30-0.35) because of their ultrahigh piezoelectric and electromechanical coupling properties. The alternating current poling (ACP) treatment, rather than the conventional direct current poling treatment, has recently been spotlighted due to its effectiveness in enhancing the piezoelectric properties. So far, it has been suggested that the enhanced piezoelectricity originates from either a domain miniaturization to nanodomains or from an electric-field-induced monoclinic symmetry. In this study, we demonstrate by thermally stimulated depolarization current measurements that the effect of ACP is too complex to be explained using a single mechanism and that the proposed electric-field-induced monoclinic symmetry is unlikely to exist.
손광현,이남수,이건주,Sohn, Kwang-Hyun,Lee, Nam-Soo,Lee, Geon-ju 대한흉부심장혈관외과학회 1980 Journal of Chest Surgery (J Chest Surg) Vol.13 No.2
A twenty three year old, Primigravida and 32 week pregnant woman who has been complained dyspnea, chest pain, nausea and vomiting was admitted to this chest surgical department on Feb. 19, 1979. Physical findings were those of acutely ill appearance, decreased thoracic excursion and absence of breath sounds in the left hemithorax. Roentgen examination of the chest revealed reticular cystic densities in the left, particularly in lower lung field with collapse of the left lung. Correction of the diaphragmatic hernia was carried out with reduction and repair of the hernia through transperitoneal approach. On exploration, the defect of the diaphragm was 12 x 12 cm in size and was located posterolateral area of left diaphragm. Hernia contents were stomach, spleen, omentum and splenic flexure of large bowel. The baby was normal full term spontaneous delivered at 36th POD. Diaphragmatic hernia complicated by pregnancy is a rarity and mortality is extremely high. Therefore, the literatures have reviewed and the case is reported.
저선량과 고선량 측정구간 변환이 가능한 모바일 방사선 측정시스템 개발 및 평가
이홍연(Hong-Yeon Lee),한상준(Sang-Jun Han),김보길(Bo-Gil Kim),이건주(Geon-Ju Lee),김석현(Seok-Hyeon Kim),김정훈(Jeong-Hun Kim) 대한방사선과학회(구 대한방사선기술학회) 2022 방사선기술과학 Vol.45 No.1
This study is to develop a mobile type environmental radiation measurement system for emergency response or environmental radiation monitoring of local governments near nuclear facilities. A mobile radiation measurement system can monitor radiation by field beyond the spatial constraints of a fixed environmental radiation monitor. If installed in local government infrastructure such as public transportation, environmental radiation can be monitored without additional manpower and measurement work. In addition, it is designed to enable monitoring and measurement of radiation from low to high doses as well as the environment in preparation for radioactive disasters such as nuclear power plant accidents. It is expected that this system will be utilized not only in normal times but also in the event of a radiation accident to improve the disaster prevention capabilities of local governments.
회전익 무인항공기를 이용한 노천석회석광산 채굴장 3차원 모델링 및 채굴량 분석
강성승 ( Seong-seung Kang ),이건주 ( Geon-ju Lee ),노정두 ( Jeongdu Noh ),장형두 ( Hyeongdoo Jang ),김선명 ( Sun-myung Kim ),고진석 ( Chin-surk Ko ) 대한지질공학회 2018 지질공학 Vol.28 No.4
이 연구는 회전익 무인항공기인 드론을 활용하여 노천석회석광산 채굴장에 대한 3차원 모델링과 화약 발파에 의한 석회석 채굴 전후의 채굴량 산정 가능성을 살펴보기 위한 것이다. 촬영된 채굴장의 영상에 대한 중복도를 분석한 결과 높은 화질의 구현이 가능한 것으로 나타났다. 카메라 캘리브레이션을 통해 왜곡도를 보정한 후 촬영 위치에서 각 축 방향 오차를 분석한 결과 허용 가능 범위를 보였다. 화약발파 전후 채굴량을 산정한 결과 넓은 범위의 채굴량을 비교적 짧은 시간에 빠르고 정확하게 산정 가능한 것으로 나타났다. 결론적으로 노천석회석광산의 채굴장 모니터링과 채굴량 산정에 있어 회전익 무인항공기 드론이 유용하게 활용될 수 있을 것으로 판단된다. 또한 이 방법은 향후 노천 광산뿐만 아니라 건설 현장이나 도로사면 등의 주기적인 모니터링에 적극 활용될 수 있을 것으로 기대된다. The purpose of this study is to show the possibility of 3-dimensional modeling of open-pit limestone mine by using a rotary-wing unmanned aerial vehicle, a drone, and to estimate the amount of mining before and after mining of limestone by explosive blasting. Analysis of the image duplication of the mine has shown that it is possible to achieve high image quality. Analysis of each axis error at the shooting position after analyzing the distortions through camera calibration was shown the allowable range. As a result of estimating the amount of mining before and after explosive blasting, it was possible to estimate the amount of mining of a wide range quickly and accurately in a relatively short time. In conclusion, it is considered that the drone of a rotary-wing unmanned aerial vehicle can be usefully used for the monitoring of open-pit limestone mines and the estimation of the amount of mining. Furthermore, it is expected that this method will be utilized for periodic monitoring of construction sites and road slopes as well as open-pit mines in the future.
성견 하악골 절단 후 기계적 골 견인에 의해 형성된 골 신장부에 대한 시기별 조직학적 변화
백선호,안병근,박영주,박희건,박준우,이건주,이용찬,조병욱,Baek, Sun-Ho,Ahn, Byoung-Keun,Park, Young-Ju,Park, Hee-Geon,Park, Jun-Woo,Rhee, Gun-Joo,Lee, Yong-Chan,Cho, Byoung-Ouck 대한구강악안면외과학회 2001 대한구강악안면외과학회지 Vol.27 No.5
Purpose : Traditionally, the treatement of choice has been a bone grafting procedure to increase the length of bone in case of actual length discrepancy. But, bone grafting procedure has many disadvantages, for example, graft resorption, donor site morbidity, and so on. So, many trials have been performed to avert the use of autogenous bone graft via introducing new materials or methods. And, one of those trials has been realized by the development of a technique inducing bone lengthening by osteotomy (or corticotomy) and slow gradual distraction of the osteotomized segments. This new technique of bone lengthening dates back to the early 20th century. But, the majority of information concerning the biology of new bone formation during bone lengthening and technical details of the procedure were produced by extensive clinical and experimental studies performed by Ilizarov, a Russian surgeon. According to Ilizarov, with adequate blood supply, preservation of periosteum, rigid fixation of the osteotomized segments, and proper rate and rhythm of distraction, intramembranous bone rapidly develops within the distraction gap in the limb lengthening procedure. In the limb lengthening, many orthopedic surgeons try to observe the biologic and clinical principles recommended by Ilizarov. In the oral and maxillofacial region, however, not a few studies must be performed to apply this surgical technique in the clinical cases. Besides, the mechanism of bone formation in the distraction gap is not clear, yet. The purpose of this experiment was to scrutinize serially the histological changes in the elongated bone affected by osteodistraction of the mandibular body in an adult canine model. In addition, it was performed to confirm the presence of specific region(s) which was important in the bone formation in the gap through the observation of the expression pattern of osteocalcin and osteonectin with the immunohistochemical examination. Materials and Methods : The experimental and control specimens were obtained from seven adult male mongrel dogs weighing over 20kg. The distractors were custom-made linear extraoral devices and bicortical fixation screws were 2.3mm in diameter, 50mm in total length, 15mm in screw length. The distractors were devised to produce a linear gap of 0.75mm between two bony segments every $360^{\circ}$ turn of the rotation rod of the device. The mandibular body of the right side of each animal was corticotomized perpendicular to the occlusal plane and then two bony segments were separated completely by careful manipulation of the segments with bone forceps. The left side of each animal was left intact. This side was served as control. At sixth day after osteotomy and fixation of the segments were performed, distraction of the segments was commenced with a rate of 1.1mm/day and a rhythm of two/day for ensuing 7 days. The animals were euthanized at the 16th. 29th, and 44th day after the osteotomy. The bony specimens were decalcified, embedded in paraffin, sectioned $5{\mu}m$ thick and stained with H&E. The prepared specimens were examined under the light microscope. And, immunohistochemical examinations using anti-osteocalcin antibody (OC1, Biodesign, USA) and anti-osteonectin antibody (Haematologic Technologies Inc., Essex, VT) to locate the expressions of osteocalcin and osteonectin, respectively, were performed. Results : 1. New bone was observed already at the 16th. day after osteotomy. This suggests that new bone formation in osteodistraction was commenced at an early stage of the regenerative process. But, radiologically and microscopically, bony union was not completed in the distraction gap at the 44th. day after osteotomy. Therefore, rigid fixation must be maintained between the bony fragments till the complete bony union is confirmed clinically rather than one month or so after the completion of distraction.
강성승 ( Seong-seung Kang ),노정두 ( Jeongdu Noh ),이건주 ( Geon-ju Lee ),김대현 ( Daehyeon Kim ),정희철 ( Heechul Jung ),고진석 ( Chin-surk Ko ) 조선대학교 공학기술연구원 2017 공학기술논문지 Vol.10 No.1
This study is to evaluate the ground behavior of the retaining wall using the Eco-SB displacement meter in the ground. For the purpose, bending and compression test in laboratory were firstly performed to examine the characteristics of the Eco-SB displacement meter. Secondly, the numerical analysis was carried out to determine the location of the Eco-SB displacement meter in the ground. Thirdly, after installing the Eco-SB displacement meter periodic monitoring of the retaining wall was performed. By the result, the ground by retaining wall was relatively stable except for the rainfall or rainy season. However the ground was unstable when the water penetrated the ground. Considering the measurement results, bending, tensile and compressive phenomena in the ground as well as the ground condition can be presented by the Eco-SB displacement meter. The ground behavior might be affected by seasonal changes, climate change, temperature and precipitation, and so on. Therefore, it suggests that short and long term monitoring for more accurate analysis is necessary.