http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
오늘 본 자료
폴리이미드 중공사막을 이용한 H2S/CH4 투과거동에 관한 연구
이형근,안영모,김대훈,조항대,서용석,박영성 한국막학회 2009 멤브레인 Vol.19 No.4
폴리이미드는 유리상 고분자로서 높은 화학적 저항성과 열적 안정성을 지니고 있으며, 기계적 물성이 거의 변하지 않는다. 본 연구에서는 황화수소와 메탄의 투과특성을 알아보기 위하여 폴리이미드 중공사막을 건/습식 상전이 공정에 의하여 제조하였고, 제조된 중공사막의 구조 및 실리콘 코팅 전/후의 황화수소와 메탄의 투과특성에 대하여 알아보았다. 압력이 증가함에 따라 황화수소의 투과도는 가소화 현상으로 인해 증가하였고, 황화수소와 메탄의 선택도 역시 증가하는 것으로 나타났다. 실험에 사용된 세 종류의 막 가운데 KSM03b의 투과도와 KSM03d의 선택도가 가장 높은 것으로 나타났다. air gap이 증가 할수록 투과도는 감소하지만 선택도는 증가하였다. 또한 실리콘 코팅 후 투과도는 감소하였지만, 선택도는 증가하였고 7기압에서 KSM03d의 선택도는 275이었다. Polyimide which is the glassy polymer has high chemical resistance, thermal stability and high mechanical property. In this study, the polyimide hollow fiber membranes were prepared by the dry-jet wet phase inversion in order to investigate the permeation porperties of the H2S and CH4. The morphology of prepared hollow fiber membranes and their permeation behaviors of H2S and CH4 before and after silicon coating were evaluated. The permeance of H2S and H2S/CH4 selectivity increased due to plasticization with increasing the feed pressure. The permeance of KSM03b and selectivity of KSM03d were highest among the three type membranes used this experiments. The permeance decreased but the H2S/CH4 selectivity increased with increasing the air gap. The permeance reduced after silicon coating. However, the selectivity increased and the selectivity of KSM03d was 275 at 7 atm.
이형근 대한의사협회 2019 대한의사협회지 Vol.62 No.12
Despite the successful development of modern medical educational systems within the last century, such systems need improvement in terms of developing better ways to educate medical students as future clinicians while also nurturing them to be good physician scientists. The period from 1964 to 1972 was called the Golden Era of Nobel Laureates in Medicine. Nine laureates, all graduates from American medical schools, came to the United States National Institute of Health (NIH). During the Vietnam War, many medical doctors substituted military service for service in the NIH, became members of the United States National Academy of Sciences, and attained brilliant medical and scientific achievements. There is a crucial lesson to learn from this golden time of the NIH: ambitious young physicians given opportunities to become cutting-edge scientists can make fundamental discoveries. In hopes of encouraging a similar “golden era” for medical research in Korea, I suggest three steps. First, medical schools and the educational system should provide medical students with more opportunities to conduct in-depth medical research in various fields. Second, the Physician Scientist Program should be further expanded to include more medical students and clinical board holders. Better treatments and approaches are essential for gathering both bright candidates and brilliant mentors, who will support each other in making outstanding scientific discoveries. Finally, the flexibility of the medical educational system in terms of medical students and clinical residency needs updating. In conclusion, a national medical educational system that is well balanced can maintain and support both excellent physician scientists and skillful clinicians.
이형근,김영준,조원일,Lee, H.G.,Kim, Y.J.,Cho, W.I. 한국전기화학회 2007 한국전기화학회지 Vol.10 No.1
이 리뷰를 통하여, 휴대폰용 리튬이차전지의 최근 기술동향을 설명하였다. 휴대폰용 이차전지로는 니카드, 니켈-금속수소, 리튬이온 혹은 리튬이온폴리머의 세 가지 형태의 전지가 있으며, 리튬 이차전지가 에너지밀도 측면에서 가장 성능이 우수하다. 즉, 동일한 용량을 갖는 이차전지 가운데 가장 작고 가벼운 것은 리튬이차전지이다. 이러한 리튬이차전지의 시장은 매년 약 15%의 높은 성장을 기록하고 있다. 연구개발은 $LiFePO_4$를 포함하는 새로운 양극, $Li_4Ti_5O_{10}$, Si, 주석 등의 새로운 음극소재, 새로운 전해질과 안정성 확보에 관한 것을 중심으로 진행되고 있다. In this review article, we are going to explain the recent development of lithium secondary batteries for a cellular phone. There are three kinds of rechargeable batteries for cellular phones such as nickel-cadmium, nickel-metal hydride, and lithium ion or lithium ion polymer. The lithium secondary battery is one of the most excellent battery in the point of view of energy density. It means very small and light one among same capacity batteries is the lithium secondary battery. The market volume of lithium secondary batteries increases steeply about 15% annually. The trend of R&D is focused on novel cathode materials including $LiFePO_4$, novel anode materials such as lithium titanate, silicon, and tin, elecrolytes, and safety insurance.