Role of the oxidizing agent in the etching of 4H-SiC substrates with molten KOH

Na, M.,Kang, I. H.,Moon, J. H.,Bahng, W. 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol. No.

<P>A novel etching solution using molten potassium hydroxide (KOH) for the identification of dislocation types in a silicon-carbide (SiC) epilayer is identified. Threading screw dislocations (TSDs) and threading edge dislocations (TEDs) are rarely useful for size-based differentiation of etch pits in highly nitrogen (N)-doped SiC through conventional KOH etching. In this study, we report the role of sodium peroxide (Na2O2) and potassium dioxide (KO2) as oxidizing agent additives to the etchant for identifying the dislocation types in highly N-doped 4H-SiC. A Na2O2-KOH phase diagram was calculated to predict the chemical composition of the etchant. Solid-phase Na2O2 remained in the system when added to the etchant at concentrations greater than 13-wt% Na2O2, and it provided excess oxygen to the etchant. We experimentally confirmed that etch pit shapes became more hexagonal and that the etch pit sizes of TSDs and TEDs differed more greatly when more than 20-wt% Na2O2 was added to the etchant. We also found that the size distribution of TEDs was much smaller than that of TSDs after etching using Na2O2-KOH. Dissolved oxygen played an essential role in enhancing the anisotropic etching of highly N-doped SiC and allowed the dislocation types to be identified.</P>

Isolation and genetic characterization of naturally NS-truncated H3N8 equine influenza virus in South Korea

NA, W.,KANG, B.,KIM, H.-I.,HONG, M.,PARK, S.-J.,JEOUNG, H.-Y.,AN, D.-J.,MOON, H.,KIM, J.-K.,SONG, D. Cambridge University Press 2014 Epidemiology and infection Vol.142 No.4

<B>SUMMARY</B><P>Equine influenza virus (EIV) causes a highly contagious respiratory disease in equids, with confirmed outbreaks in Europe, America, North Africa, and Asia. Although China, Mongolia, and Japan have reported equine influenza outbreaks, Korea has not. Since 2011, we have conducted a routine surveillance programme to detect EIV at domestic stud farms, and isolated H3N8 EIV from horses showing respiratory disease symptoms. Here, we characterized the genetic and biological properties of this novel Korean H3N8 EIV isolate. This H3N8 EIV isolate belongs to the Florida sublineage clade 1 of the American H3N8 EIV lineage, and surprisingly, possessed a non-structural protein (NS) gene segment, where 23 bases of the NS1-encoding region were naturally truncated. Our preliminary biological data indicated that this truncation did not affect virus replication; its effect on biological and immunological properties of the virus will require further study.</P>

H-Bridge 멀티-레벨 인버터 시스템

윤홍민(H.M.Yun),전재현(J.H.Jeon),이정표(J.P.Lee),장동제(D.J.Jang),나승호(S.H.Na),권봉현(B.H.Kwon) 전력전자학회 2005 전력전자학술대회 논문집 Vol.- No.-

본 논문은 대용량 전력변환장치인 멀티-레벨 인버터 시스템에서 출력 전압가변이 손쉬운 HBML (H-Bridge Multi-Level) 인버터의 Master와 Cell 제어기 구성에 관한 것이다. HBML 인버터는 각각의 단위 Cell을 저압에서 사용하는 인버터로 구성하며, 구조적으로 풀-브릿지(Full-Bridge) 인버터를 캐스케이드 방식으로 연결하여 고압출력을 얻을 수 있는 토폴로지이다. 시스템에서 Master와 Cell의 제어 처리를 한곳에 집중하지 않는 분산 제어 방식을 적용하여 통신 Data를 최적화하도록 구성하고, 이를 바탕으로 두 제어기를 고성능 원-칩(One-Chip) DSP로만 설계하였다. 모든 외부 모듈을 내장한 CPU로 제어기가 구성될 경우, 외부 노이즈에 강하며, 추가되는 하드웨어 결선을 최소화할 수 있다. 본 논문에서는 HBML 인버터 출력 생성 시 반드시 요구되는 출력 PWM 동기 및 위상전이(Phase Shift)를 각 제어기 자체에 내장된 모듈만을 이용해서 구현하였다.

H-bridge 멀티-레벨 인버터의 파워Cell AVR에 관한 알고리즘

전재현(J.H.Jeon),윤홍민(H.M.Yun),김민극(M.K.KIM),이정표(J.P.Lee),장동제(D.J.Jang),나승호(S.H.Na),권봉현(B.H.Kwon) 전력전자학회 2005 전력전자학술대회 논문집 Vol.- No.-

본 논문은 멀티-레벨 H-bridge 인버터에서 입력전압 변동에 따른 AVR(Auto Voltage Regulation) 기능을 적용 그 타당성을 제안하였다. 기존의 범용 인버터에서 (V/F)로 구동되는 전동기 시스템에 있어서 인버터에 공급되는 입력 전압은 출력 주파수에 따라 출력 전압 비율을 일정하게 하고 기동에 필요한 전압을 더하여 출력하는 방식이다. 집중 제어 방식의 멀티-레벨 H-bridge 인버터에서는 Cell의 DC-Link 전압을 Master에서 받아들여서 각각의 Cell에 기준 전압값을 지령하게 된다. 그러므로 입력 전압 변동에 따른 DC-Link 전압의 변동이 발생하게 되면 상전압 Unbalance 가 발생하게 되어 부하가 원하는 출력 전압을 낼 수가 없게 된다. 또한 각각의 Cell을 제어하는 Master 제어기가 가지고 있는 문제점을 보완하여 각각의 Cell 제어기 스스로가 AVR을 수행하는 좀더 나은 방법을 제안하였다.

난관배양액이 처녀발생유기된 돼지난포란의 체외발달에 미치는 영향

문승주,이경호,김호,김창렬,은대숙,김광현,나진수,김재홍 全南大學校 農業科學技術硏究所 1997 農業科學技術硏究 Vol.32 No.-

본 연구는 난관배양액이 돼지수정란의 체외발달에 미치는 효과를 규명키 위하여 수행하였다. 돼지 미성숙 난포란은 TCM-199, Ham's F-10 그리고 Whitten's 배양액에 10% 난포액과 호르몬(PMSG : 10IU/㎖, HCG : 10IU/㎖)을 첨가 20시간 배양하고 호르몬을 첨가하지 않는 배양액에서 20시간 추가 배양하여 총 40시간동안 배양하여 체외성숙을 유도하였다. 체외성숙후 0.1% hyaluronidase로 난구세포를 제거하고 15% FCS가 함유된 TCM-199으로 3회 세척하고 TCM-199에 15% FCS와 10% ethanol 혼합액에 세척한 난자를 옮겨 10분간 배양 처녀발생을 유기하였다. 처녀발생 6시간후 전핵형성율은 체외성숙배양액으로 TCM-199을 사용했을 때 56.4%, Ham's F-10의 경우 58.3%, Whitten's 배양액의 경우 74.0%를 보였다. 처녀발생 유기 48시간째 난할율은 TCM-199을 사용했을 때 45.7%, Ham's F-10에서 45.4%, Whitten's배양액에서 39.2%를 보였으며 세종류의 배양액에 POCM을 첨가 배양했을 때 TCM-199에 44.8%, Ham's F-10에서 45.4%, Whitten's배양액에서 43.7%로 나타났다. 처녀발생육 난자를 96시간 체외배양시킨 결과 상실배 발달율이 POCM을 첨가 했을 때 첨가하지 않은 시험구에 비하여 유의적으로 높았다(P<0.05) The effect of porcine oviductal conditioned medium(POCM) on in vitro development of chemically activated porcine oocytes was studied. Porcine oocytes were cultured in TCM-199, Ham's F-10 and Whitten's medium with hormonal supplements for 20h and 40h additional culture without hormonal supplements. After in vitro maturation, the denuded oocytes were washed 3 times with TCM-199 contaning 15%(v/v) ethanol to induce pathenogenetic activation. At 6h after activation, pronuclea formation rates were 56.4% in TCM-199, 59.3% in Ham's F-10 and 74.0% in Whitten's maturation medium. At 48h after activation, 45.7%, 45.4% and 39.2% of oocytes claved in TCM-199, Ham's F-10 and Whitten's culture medium, respectively. And 44.8%, 45.5% and 43.7% of oocytes were claved in TCM-199, Ham;s F-10 and Whitten's culture medium supplemented with POCM, respectively. The rates of moular were higher in culture medium with POCM than without POCM at 96h after activation.(P<0.05)

인플루엔자 유행시 국가방역 관리 능력 향상을 위한 기초연구

김지희,김우주,이주연,나병국,박종원,신구철,김선숙,김진아,고연아,박순희,김도근,임윤구 국립보건연구원 1999 국립보건원보 Vol.36 No.-

동적 상황 기반 응용 개발 플랫폼의 설계 및 구현

송호근(H.K song),서주홍(J.H Seo),최정희(J.H. Choi),신승중(S.J. Shin),류대현(D.H. Ryu),나종화(J.H. Na) 한국정보과학회 2004 한국정보과학회 학술발표논문집 Vol.31 No.2Ⅲ

유비쿼터스 컴퓨팅의 응용분야에서 거시적이고 동적인 개념을 쉽게 구현할 수 있는 플랫폼을 설계하고 구현 하였다. 주위 정보를 수집하는 센서들과 이 정보들을 서버에게 보내는 PDA 그리고 여러 지역을 감지하기 위해 이동이 가능하게 하는 이동체 등으로 구성되어 있다. 응용하는 곳에 따라 이동체, 센서, 룰셋 등을 변경할 수 있도록 플랫폼을 설계하였다. 이 논문에서는 이 플랫폼의 H/W의 구성과 S/W의 구성을 살펴보고 이를 응용한 곳에 대해 설명한다. 그리고 향후 개발 방향에 대해 언급한 후 끝을 맺는다.

15-Deoxy-Δ^12,14-prostaglandin J₂ induces p53 expression through Nrf2-mediated upregulation of heme oxygenase-1 in human breast cancer cells

Kim, D. H.,Song, N. Y.,Kim, E. H.,Na, H. K.,Joe, Y.,Chung, H. T.,Surh, Y. J. Informa Healthcare 2014 Free radical research Vol.48 No.9

<P>Heme oxygenase-1 (HO-1) is a stress-responsive enzyme that has antioxidant and cytoprotective functions. However, HO-1 has oncogenic functions in cancerous or transformed cells. In the present work, we investigated the effects of HO-1 on the expression of p53 induced by 15-deoxy-Δ<SUP>12,14</SUP>-prostaglandin J<SUB>2</SUB> (15d-PGJ<SUB>2</SUB>) in human breast cancer (MCF-7) cells. Treatment of MCF-7 cells with 15d-PGJ<SUB>2</SUB> led to time-dependent increases in the expression of p53 as well as HO-1. Upregulation of p53 expression by 15d-PGJ<SUB>2</SUB> was abrogated by si-RNA knock-down of HO-1. In MCF-7 cells transfected with HO-1 si-RNA, 15d-PGJ<SUB>2</SUB> failed to induce expression of p53 as well as HO-1. In addition, HO-1 inducers enhanced the p53 expression. We speculated that iron, a by-product of HO-1-catalyzed reactions, could mediate 15d-PGJ<SUB>2</SUB>-induced p53 expression. Upregulation of p53 expression by 15d-PGJ<SUB>2</SUB> was abrogated by the iron chelator desferrioxamine in MCF-7 cells. Iron released from heme by HO-1 activity is mostly in the Fe<SUP>2+</SUP> form. When MCF-7 cells were treated with the Fe<SUP>2+</SUP>-specific chelator phenanthroline, 15d-PGJ<SUB>2</SUB>-induced p53 expression was attenuated. In addition, levels of the Fe-sequestering protein H-ferritin were elevated in 15d-PGJ<SUB>2</SUB>-treated MCF-7 cells. In conclusion, upregulation of p53 and p21 via HO-1 induction and subsequent release of iron with accumulation of H-ferritin may confer resistance to oxidative damage in cancer cells frequently challenged by redox-cycling anticancer drugs.</P>

In vivo imaging of tumor apoptosis using histone H1-targeting peptide

Wang, K.,Purushotham, S.,Lee, J.Y.,Na, M.H.,Park, H.,Oh, S.J.,Park, R.W.,Park, J.Y.,Lee, E.,Cho, B.C.,Song, M.N.,Baek, M.C.,Kwak, W.,Yoo, J.,Hoffman, A.S.,Oh, Y.K.,Kim, I.S.,Lee, B.H. Elsevier Science Publishers 2010 Journal of controlled release Vol.148 No.3

In vivo imaging of apoptosis could allow monitoring of tumor response to cancer treatments such as chemotherapy. Using phage display, we identified the CQRPPR peptide, named ApoPep-1(Apoptosis-targeting Peptide-1), that was able to home to apoptotic and necrotic cells in tumor tissue. ApoPep-1 also bound to apoptotic and necrotic cells in culture, while only little binding to live cells was observed. Its binding to apoptotic cells was not dependent on calcium ion and not competed by annexin V. The receptor for ApoPep-1 was identified to be histone H1 that was exposed on the surface of apoptotic cells. In necrotic cells, ApoPep-1 entered the cells and bound to histone H1 in the nucleus. The imaging signals produced during monitoring of tumor apoptosis in response to chemotherapy was enhanced by the homing of a fluorescent dye- or radioisotope-labeled ApoPep-1 to tumor treated with anti-cancer drugs, whereas its uptake of the liver and lung was minimal. These results suggest that ApoPep-1 holds great promise as a probe for in vivo imaging of apoptosis, while histone H1 is a unique molecular signature for this purpose.

Fluorescent chemosensor based-on the combination of julolidine and furan for selective detection of zinc ion

Na, Y.J.,Hwang, I.H.,Jo, H.Y.,Lee, S.A.,Park, G.J.,Kim, C. Elsevier 2013 Inorganic Chemistry Communications Vol.35 No.-

A new sensor 1-[[(2-furanylmethyl)imino]methyl]-2-hydroxyjulolidine (1) based on the combination of julolidine and furan groups was designed and synthesized as a Zn<SUP>2+</SUP> selective fluorescent chemosensor. Upon treatment with zinc ions, the complexation of 1 with Zn<SUP>2+</SUP> exhibited a pronounced enhancement in the fluorescence emission in methanol, while many other ions such as Mn<SUP>2+</SUP>, Co<SUP>2+</SUP>, Ni<SUP>2+</SUP>, Cd<SUP>2+</SUP>, Hg<SUP>2+</SUP>, Na<SUP>+</SUP>, K<SUP>+</SUP>, Mg<SUP>2+</SUP>, Ca<SUP>2+</SUP>, Al<SUP>3+</SUP> and Ag<SUP>+</SUP>, had no influence. Notably, this chemosensor could distinguish clearly Zn<SUP>2+</SUP> from Cd<SUP>2+</SUP>. The 1:1 binding mode of the 1-Zn<SUP>2+</SUP> complex was drawn, based on UV-vis titration, fluorescence titration, Job plot and ESI-mass spectrometry analysis.