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고온 진동 센서용 BiFeO3-BaTiO3 압전세라믹의 나노 BaTiO3 모분말 도입에 따른 화학적 불균일성 및 압전 특성 연구
박규현,이경자,이민구 한국소음진동공학회 2022 한국소음진동공학회 논문집 Vol.32 No.6
1mol% MnO2-doped 0.7BiFeO3-0.3BaTiO3 (BFO-BTO) piezoceramics were synthesized through a conventional solid-state method, using nano-sized BaTiO3 raw powders. In the application of the nano-BaTiO3 raw powders, the phase structure, chemical heterogeneity, microstructure, ferroelectric, and piezoelectric properties significantly changed, compared to the application of conventional micron-sized BaCO3 and TiO2 raw powders. The sintered BFO-BTO piezoceramics showed a reduced chemical heterogeneity and strong ferroelectric nature, whereas the counterparts using the conventional micron-sized raw powders typically exhibited a core-shell structure with a high degree of chemical heterogeneity, causing a relaxor characteristic. In addition, the piezoceramics sintered using the nano-sized BaTiO3 exhibited greater piezoelectric, ferroelectric and insulating properties, compared to those of ceramics sintered using the conventional micron-sized raw powders. The property enhancements of the BFO-BTO piezoceramics were attributed to the effects of reduced chemical heterogeneity, large grain size, low leakage current and the formation of appropriate morphotropic phase boundary. Finally, the achieved high TC of 519.1°C and excellent thermal aging resistance of d33 up to 480°C indicate great potential for use in high-temperature environments.
TMS320F240을 이용한 PWM 인버터 유도전동기 구동 시스템의 전도노이즈 저감을 위한 스위칭 기법
朴奎炫,金利勳,元忠淵,金奎植,崔世琓,咸年根 성균관대학교 2003 학술회의지원논문목록집 Vol.2003 No.-
PWM 인버터에 의해 구동되는 유도전동기에 발생되는 고주파 커먼 모드 전압은 전도성 EMI, 전동기 접지전류, 베어링 전류 및 다른 원치 않는 결과의 주원인이 된다. 인버터 제어의 무효벡터 스위칭 상태는 나머지 유효벡터 스위칭 상태에 비교하여 큰 커먼 모드 전압을 일으킨다. 그러므로 이 논문은 커먼 모드 전압을 완화하는 스위칭기법을 다룬다. 즉 정현파 PWM기법을 기본으로 한 커먼 모드 전압 제거방법을 제안하였다. PWM 신호는 각각의 정현파 기준신호와 120˚위상차가 나는 3개의 캐리어 파형과 비교하여 발생된다. 시뮬레이션과 실험적결과는 제안된 PWM 기법에서 커먼 모드 전압이 종래의 PWM 기법보다 약 66% 더 저감됨을 보였다. High frequency common mode voltage produced by PWM inverter fed induction motor is a major cause of conducted EMI. creation motor ground currents, bearing currents and other hamful products. The zero switching states of inverter control invoke large in comparison with the non-zero switching state of inverter control. We proposed a common mode voltage reduction method based on sinusoidal PWM technique. PWM signal are generated by comparing respective sinusoidal reference signal with three triangular carrier wave displaced of 120˚. Simulation and experimental result show that common mode voltages in the propsed PWM technique are reduced by approximate 66% more than conventional PWM technique.
뇌동맥류 파열의 임상적 특징 및 유발인자로서 고혈압과 흡연의 역할
박규현,이응재,신용삼,안영환,조기홍,조경기 대한신경외과학회 2004 Journal of Korean neurosurgical society Vol.36 No.1
Objective : The purpose of this study is to identify risk factors for subarachnoid hemorrhage (SAH) in Korea. Methods : The clinical record and environmental data of 250 patients who had admitted our hospital between September 2001 and May 2003 were reviewed retrospectively by the neurosurgical nursing practitioners. Results : In this study, the peak age for presentation with ruptured intracranial aneurysm was around 5th decade which is most active period of his or her life. The peak time of aneurysm rupture was from 6 to 12 A.M. (34.8%) and the onset of SAH occurred the most frequently at work (30.4%). The prevalence of hypertension in SAH patients was 42.8%, That of cigarette smoking in men and in women were 81.7% and 15.8% respectively. Hypertension was significantly corrected with the amount of hemorrhage based on Fisher Grading system (P<0.05). The consumption of smoking and the amount of hemorrhage was closely correlated also (P<0.05). Conclusion : Hypertension and cigarette smoking may be closely related to aneurysmal SAH. Undoubtedly, they are significantly related to massive, fatal SAH with poor neurologic condition. To prevent reduce aneurysmal SAH, cessation of smoking, anti-hypertensive medication and stress control are most important basic step in promotion of public health.
박규현,황순철,곽임수,김홍범,문한규 ( Kyu Hyun Park,Soon Chun Hwang,Ihm Soo Kwak,Hong Bum Kim,Han Kyu Moon ) 대한소화기학회 1981 대한소화기학회지 Vol.13 No.1
The activities of LDH isozymes, transaminases and alkaline phosphatase were studied on 71 cases of liver diseases, among them hepatoma were 27 cases, liver cirrhosis 18 cases and hepatitis 26 cases. The results were as follow: ]. The total activity of LDH in normal control was 171.48+66.37 unit and the fractions of LDH isozymes from LDH-1 to LDH-5 were 30. 655. 81%, 35. 67+3. 73%, 25. 13+3. 83o, 4. 61W3. 08% and 4, 03 2. 73% respectively. 2. The total activity of serum LDH was significantly increased in the cases of liver diseases to compare with those of normal control group. 3, The fractions of LDH-4, LDH-5 and the ratios of LDH-5/LDH-I, LDH-5/LDH-4 and LDH-4+5/LDH-1+2 were significantly increased and LDH-2 and LDH-3 were decreased in the cases of liver diseases to compare with those of normal control. 4. LDH-4+5/LDH-I+2, GOT and alkaline phosphatase were significantly increased in hepatoma than in liver cirrhosis, the fractions of LDEI-5/LDH-1, LDH-5/LDH-4, LDH-4+5/ LDH-I+2 and GOT, GPT were increased in hepatitis than in liver cirrhosis. Nevertheless, there was no significant difference between hepatoma and hepatitis.
유대인의 마그레브 정착과 베르베르인의 유대교도화에 대한 연구
박규현 한국프랑스학회 2021 한국프랑스학논집 Vol.115 No.-
Selon de nombreux historiens, diverses légendes évoquent le passé lointain des peuples judéo-berbères de la région du Maghreb, le mystère de leurs origines. Cependant, en raison du manque de documents, il n'avait pas une place claire dans l'histoire. Si, d'une certaine manière, les Berbères en tant que peuples autochtones du Maghreb étaient en dehors de l'histoire de l'Afrique du Nord, on pourrait en dire autant des Juifs, seconds colons du Maghreb. Notre étude s'est intéressée à savoir depuis combien de temps les Juifs se sont installés dans la région du Maghreb, et comment ils ont maintenu leur monothéisme tout en gardant une relation étroite avec les Berbères. Julien Coang-Cassanho défend la thèse selon laquelle la propagation du monothéisme juif en Afrique du Nord a été principalement motivée par le prosélytisme. La judaïsation des Berbères conduit même à croire que la moitié des Juifs d'Afrique du Nord sont des Berbères. Par conséquent, les recherches sur les Berbères du Maghreb nous dirigent inévitablement vers des études sur les Juifs. Dans le contexte de l'histoire des origines judéo-berbères, cette étude examine l'implantation des Juifs au Maghreb, leur contact avec les Berbères, la judaïsation des Berbères, et enfin, l'évolution de la situation après la colonisation française du Maghreb. 여러 역사가에 따르면, 다양한 전설적 이야기들이 마그레브 지역 유대-베르베르 종족의 먼 과거, 즉 두 종족의 기원적 수수께끼를 떠올리게 만든다고 한다. 하지만 문헌의 부재로 인해 역사 속에 분명한 자리를 잡지 못했다. 만일 어떤 면에서 마그레브 토착민으로서의 베르베르인이 북아프리카 역사의 바깥에 자리했다면, 마그레브에 두 번째로 정착한 유대인들 역시 마찬가지라고 할 수 있다. 본 연구는 유대인이 얼마나 오래전부터 마그레브 지역에 정착했는가, 어떻게 베르베르인과 밀접한 관계를 맺으며 그들의 유일신교를 유지했는가에 관심을 가졌다. 줄리앙 코앙-라카사뉴는 북아프리카에서의 유대 유일신교 전파가 적극적 포교에 의해 이루어졌다고 주장한다. 베르베르인의 유대교도화는 북아프리카 출신 유대인의 절반이 베르베르인이라는 얘기까지 나오게 만든다. 따라서 마그레브의 베르베르인에 대한 연구는 유대인에 대한 연구로 이어질 수밖에 없다. 본 연구는 유대-베르베르 기원의 역사라는 맥락에 따라 유대인의 마그레브 정착 및 베르베르인과의 접촉, 베르베르인의 유대교도화, 마지막으로 프랑스의 마그레브 식민통치 이후의 상황 변화에 대해 고찰하였다.