고성능 폴리머 재질의 포스트-코어 시스템의 생역학적 거동에 대한 예비실험

이기선,김종은,김지환,이정열,신상완,Lee, Ki-Sun,Kim, Jong-Eun,Kim, Jee-Hwan,Lee, Jeong-Yol,Shin, Sang-Wan 대한심미치과학회 2018 Journal of the Korean Academy of Esthetic Dentistr Vol.27 No.2

본 연구의 목적은 기존의 다른 포스트-코어 재료와의 유한요소분석(FEA)의 비교를 통한 치과용 포스트-코어 재료로서의 고성능 폴리머 PEKK의 생체역학 및 장기 안전성을 평가하는 데 있다. 상악 중절치를 모델링 하였으며, 구개 표면에서 치아의 장축에 $45^{\circ}$의 각도로 50N의 반복 하중을 가했다. 전통적으로 사용 된 포스트 코어 재료와 비교하기 위해 3가지 재료 (금, 유리 섬유 및 PEKK)를 시뮬레이션하여 결과를 상호 비교 해 보았다. 상아질보다 낮은 탄성 계수를 갖는 PEKK는 종래의 포스트 코어 재료보다 비교적 치근에 유리한 응력 분포를 보여 주었다. 그러나, PEKK 포스트-코어 시스템은 금속 또는 유리 섬유 포스트-코어 시스템보다 장기간의 반복하중에 대해 타락 및 크라운 파손의 가능성이 더 높을 가능성이 있다. The aim of this study was to evaluate the biomechanical behavior and long-term safety of high performance polymer PEKK as an intraradicular dental post-core material through comparative finite element analysis (FEA) with other conventional post-core materials. A 3D FEA model of a maxillary central incisor was constructed. A cyclic loading force of 50 N was applied at an angle of $45^{\circ}$ to the longitudinal axis of the tooth at the palatal surface of the crown. For comparison with traditionally used post-core materials, three materials (gold, fiberglass, and PEKK) were simulated to determine their post-core properties. PEKK, with a lower elastic modulus than root dentin, showed comparably high failure resistance and a more favorable stress distribution than conventional post-core material. However, the PEKK post-core system showed a higher probability of debonding and crown failure under long-term cyclic loading than the metal or fiberglass post-core systems.

酪農製品의 需要展望과 그 問題點

李箕善,卞裕亮,梁堅 한국식품과학회 1980 식품과학과 산업 Vol.13 No.3

具體的 學習目標의 提示가 學業成就에 미치는 影響에 關한 一硏究

李基善 한국외국어대학교 교육대학원 1987 교육논총 Vol.2 No.1

다섯째마당-함께 나누는 이야기

이기선 우리신학연구소 1992 갈라진 시대의 기쁜소식 Vol.- No.19

진공증착법에 의한 $In_2O_3$ 투명전도막의 제작

이기선 대한전자공학회 1980 전자공학회지 Vol.17 No.5

전자선가열 도착법에 의해 ∼ 10-4 Torr의 산소 분권기중에서 In2O3 투명전도막을 제작하였으며, 막의 최적 훈착조건과 그의 전기적, 광학적 성질을 측정, 분석하였다. 최적 증착조건은 증착구도 3∼7 A/sec, 기판온도 300℃이상, SnO2 첨가률 2∼5 wt. % 이었으며, 이러한 조건하에서 막피 비저항은 2 × 10-4 Ω·cm 이었고, 가시광 투과률은 85∼90% 이었다. Transparent conducting films of In2O3 were fabricated by elect yon beam evaporation method in an oxygen atmosphere of -10-4 Torr., and the optimum conditions of film deposition, as well as their electrical and optical properties were measured and analysed. Evaporation rate of 3~7A/sec, substrate temperature of over 30$0^{\circ}C$, and SnO2 doping of 2~5wt. % were the optimum deposition conditions. Under these conditions , the resistivities of the films were 2$\times$10-4 $\Omega$.cm and the visible transmittances were 85~90%.

인공위성 병렬 연결 배터리 모듈 시스템을 위한 새로운 배터리 충.방전기

이기선,조윤제,장기영,조보형 전력전자학회 2000 전력전자학회 논문지 Vol.5 No.6

표준 배터리 모듈 시스템을 위한 새로운 배터라 충.방전기를 제안한다. 전체 시스템의 크기를 줄이기 위해 충전기와 방전기의 회로가 하나의 컨버터로 구현되었으며, 최대 전력 추적을 포함한 태양전지 출략전압 제어와 태양 전지 출력과 부하 전력에 따른 배터리 충.방전 전류 제어를 동시에 수행한다. 또한, 제안된 컨버터는 부하의 전략 공급을 간단히 할 수 있는 일성 전압 버스(regulated bus)를 제공한다. 제안된 컨버터는 특성상 DCM으로 동작하므로 전듀의 첨두지가 크므로 고전력 시스템에서는 여러 개의 모듈로 사용되어야 한다. A novel integrated battery charger/discharger converter for a standardized battery module is proposed. Instead of using separate charger and discharger converters, it integrates these two converters into a single converter in order to minimize the size. The integrated charger/discharger converter not only regulates the solar array output power including the peak power tracking capability but also controls the battery charging/discharging current depending on the solar array output power and the load power. In addition, it offers a regulated bus voltage which simplifies the power distribution/conversion for the pay load.

다이아몬드 공구용 코발트계 합금 결합제의 제조 및 기계적 성질

이기선,정승부,Lee, Gi-Seon,Jeong, Seung-Bu 한국재료학회 2000 한국재료학회지 Vol.10 No.8

Diamond 공구용 Co-0.5C-(15∼20)Cr-20Ni-8W-(2∼7)Fe 합금 결합제를 볼밍링(ball-milling)법과 기계적 합금화(mechanical alloying) 법으로 합성하였다. stearic acid의 첨가 유무에 상관없이 Co-0.5C-(15∼20)Cr-20Ni-8W-(2∼7)Fe 합금의 경우 6시간 동안 합금화된 금속 분말에서 미세 접합(micro welding) 형상이 균일하게 관찰되었다. stearic acid를 첨가하지 않을 때는 부분적으로 조대화된 분말이 형성되었으나 2% 첨가한 경우 미세하고 판상의 분말이 얻어졌다. stearic acid가 첨가된 복합분말을 열간 압축하여 기계적 성질을 평가한 결과 굽힘강도 1100MPa, 경도 46H(sub)Rc의 특성을 나타냈다. Co-0.5C-(15~20)Cr-20Ni-8W-(2~7)Fe alloy bond in diamond-impregnated abrasive tool was synthesized by ball-milling and mechanical alloying process. When the powders were mechanical alloyed for 6h, micro-welding in most metal powders was observed irrespective of addition of stearic acid. Without stearic acid in metal powders, partial-ly coarse powders were obtained, which could be unfaverable to the densification of composite of composite powders. The hot-pressed compacts showed rupture strength of 1100MPa and hardness of about $46H_{RC}$, respectively.

코로나 시대 이란의 음악교육 체계 변화: 테헤란 여자 음악학교 사례를 근거로

이기선 세계음악학회 2022 음악과 문화 Vol.- No.46

This study is about the history, the major, the curriculum, the current status of education since Covid-19 focusing on Tehran music school(girls branch) located in Teheran, Iran. Since the Islamic Revolution in 1979, Iran has strictly been under control of government regardless of the field of classical, traditional, and popular music. Therefore, music subject was not educated separately in the curriculum of the general elementary, middle, and high schools except for a few private schools, and because of this reason, it is very hard to explore the current status of music education in the public education of Iran. However, students who want to study or to major in music still can enter related music schools to have professional education, so it is still possible to study the current status of music education by it. Tehran music school located in Teheran, the capital of Iran, is a prestigious music school with a history of more than about a century. Since the established in 1914, the name of the school and the curriculum has reorganized. So, now the school is divided and operated into boys and girls separately. Since the spread of Covid-19, Tehran music school(girls branch) has been conducting both face-to-face and non-face-to-face classes, and non-face-to-face classes have been conducted from March 2020 to August 2021, and since September 2021, both face-to-face and non-face-to-face classes have been conducted. The teaching methods of face-to-face and non-face-to-face classes are similar with other music middle and high schools since Covid-19, so it was confirmed that the school follows the global educational trends. Moreover, there were some problems, for example, the use of government-provided “Shad” platforms being not familiar in the early non-face-to-face classes as well as other factors such as slow internet speed and unstable connection, pointed out. Moreover, other major issues, for instance, the lack of infrastructure, the spread of Internet networks, the government’s regulation of Internet speed, the lack of educational restrictions like laptops and mobile phones for students in poor areas, have emerged as well. The changes in the education field because of Covid-19 are still in progress, and this remote education system will continue in the future. Therefore, the efforts of Iranian government for improvement of many problems sincerely need to establish stable Internet infrastructure system, provide an appropriate environment for art education classes, and develop user-friendly educational platforms. This study is meaningful as a basic study because there is no any other research related to music education in Iran and nothing has not been introduced in Korea yet, so based on this study, it hopes to continue discussions on the music environment of Islamic culture countries as well as understanding the current status of music education in Iran. .

이달의 수필 : 카드

이기선 대한지방행정공제회 1968 地方行政 Vol.17 No.182

수도산 봉은사 사천왕상의 복장물

이기선 회당학회 2003 회당학보 Vol.8 No.-