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Cu-Ag 합금의 전기전도도와 기계적 특성에 미치는 P , Mg 의 영향
정봉용,김기태,정운재,김명호 ( Bong Yong Jeong,Ki Tae Kim,Woon Jae Jung,Myung Ho Kim ) 한국주조공학회 1998 한국주조공학회지 Vol.18 No.2
N/A Effects of P and Mg on the electrical conductivity and mechanical properties of Cu-Ag alloys were investigated experimentally. Small addition of these alloying elements decreased the electrical conductivity of Cu alloy greatly, especially for P addition. The maximum amounts of P addition to obtain the electrical conductivity being over 90%IACS was found to be about 0.019wt.%, and in this case recrystallization temperature of the addition was about 450˚C. The tensile strength was not changed significantly by the addition of P. However, for Cu-Ag-P-Mg alloys, P-Mg compound was precipitated by heat treatment at 450˚C for 1 hour. Such a precipitation of P-Mg compound increased the electrical conductivity of the alloy from 47~57%IACS to 72.3~86.6%IACS. (Received January 15, 1998)
NaF 전해질 양극산화에 의한 마이크로콘 구조 니오븀 산화물 제조
정봉용,정은혜,Jeong, Bong-Yong,Jung, Eun-Hye 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.6
In this study, we show that by anodization of Nb in NaF electrolytes microcone niobium oxide layers can be formed under a range of experimental conditions. It is found that a single NaF electrolyte leads to the formation of microcones. At 1 M NaF, 40 V, 1 h, well-ordered microcones were generated on Nb discs. XRD results show that the initially formed anodic oxide is amorphous, but an amorphous to crystalline transition occurs during anodization. For the formation of favorable microcones, it is considered that proper parameters such as electrolyte concentration, voltage, anodizing time are necessary according to the kind of electrolytes.
AAO 템플릿과 잉크젯 인쇄 기술에 의한 은 나노로드 제조에 관한 연구
정봉용 ( Bong Yong Jeong ),정은혜 ( Eun Hye Jung ),최진섭 ( Jin Sub Choi ),김지훈 ( Ji Hoon Kim ),이진형 ( Jin Hyung Lee ),장정호 ( Jeong Ho Chang ),이종무 ( Chong Mu Lee ) 대한금속재료학회(구 대한금속학회) 2013 대한금속·재료학회지 Vol.51 No.9
Silver nanorods were fabricated using a porous anodic aluminum oxide (AAO) template by an ink-jet printing process. The highly arrayed AAO template was prepared to infiltrate silver nano particles by an anodization method. The ink-jet printing unit is equipped with a piezoelectric nozzle with a 50 um orifice from Microfab technology. The morphology and crystal structure of the silver nanorods were confirmed by field emission scanning electron microscopy and x-ray diffraction pattern, respectively. The diameter of the silver nanorods was about 60 nm, which was consistent with that the diameter distribution of the AAO template.
정은혜,장정호,정봉용,Jung, Eun-Hye,Chang, Jeong-Ho,Jeong, Bong-Yong 한국전기화학회 2011 한국전기화학회지 Vol.14 No.4
본 연구에서는 니오븀 산화물을 비교적 저온에서 단시간 동안의 양극산화법을 통해 제조하였다. 이때, 전해질로는 NaF와 HF를 혼합하여 사용하였으며, 20~120 V의 다양한 전압 조건에 따라 생성되는 니오븀 산화물의 미세구조를 관찰하였다. 일반적으로 니오븀 금속의 양극산화 시 초기에 생성된 니오븀 산화물은 무정형 구조이나 반응이 경과함에 따라 점차 결정형 산화물로 성장하게 된다. 이러한 산화물은 XRD 분석을 통하여 결정형의 $Nb_2O_5$ 임을 확인하였고, FE-SEM 분석결과, 그 표면은 매우 밀집된 형태의 나노로드로 이루어진 마이크로콘 산화물임을 알 수 있었다. 적절한 공정변수로 제조된 니오븀 산화물은 마이크로콘 구조 전체 표면에 걸쳐 동일한 크기를 갖는 나노로드 다발을 형성하고 있으며, 이러한 나노 구조는 또한 넓은 표면적을 기대할 수 있어 염료감응 태양전지나 바이오 소재 등에 대한 다양한 분야에 응용될 수 있을 것으로 기대된다. The formation of niobium oxide microcones on niobium substrates was investigated in NaF to the HF electrolytes. This condition builds on the uniqueness of the microstructures niobium oxide. The dimensions and integrity of the bulk microstructures were found to be strongly dependent on potential, temperature, electrolyte composition, and anodization time. The anodic oxide was initially amorphous at all temperatures, but crystalline oxide nucleated during anodization. From XRD patterns of the anodized specimens, the microcones consisted of crystalline $Nb_2O_5$. We demonstrated niobium oxide microcone structures with nanorods. The anodized niobium oxide microcone texture revealed nanorod bundles. The surface of $Nb_2O_5$ microcones is very regular and has a nano-scale. The surface morphologies of the nanorods were examined using FE-SEM. EDS analyses show that the anodically prepared niobium oxide consists of $Nb_2O_5$. The aim of this study is to find the condition of forming the favorable nanorods by anodization method.
정은혜 ( Eun Hye Jung ),정봉용 ( Bong Yong Jeong ) 대한금속재료학회(구 대한금속학회) 2013 대한금속·재료학회지 Vol.51 No.11
Titanium and titanium alloys have been used extensively as bone-implant materials due to their high strength-to-weight ratio, good biocompatibility and excellent corrosion resistance. In this work, we investigated the surface characteristics of nanotubes formed on Ti25Nb alloys in a 0.1M NaF aqueous electrolyte containing HF using electrochemical methods. The constant voltages were widely applied to a range from 20 to 80 V. As a result, the oxide layers formed with nanotube structures in which the nanotubes increased in a linear diameter and length. The TiNb nanotube morphology was strongly influenced by the fluoride concentration, applied potential and reaction time.
장생도라지 (Platycodon grandiflorum)의 항산화 활성 평가
김충현(Chung Hyeon Kim),정봉용(Bong Yong Jung),정선기(Sun Ki Jung),이철호(Chul Ho Lee),이현선(Hyun Sun Lee),김봉희(Bong-Hee Kim),김상겸(Sang Kyum Kim) 환경독성보건학회 2010 환경독성보건학회지 Vol.25 No.1
Platycodon grandiflorum, Doraji as Korean name, is one of the most widely used traditional oriental medicine for bronchial diseases and also used as a folk remedy for geriatric diseases and inflammatory diseases. In recent studies, it has been reported that some effect of P. grandijlorum is derived from its antioxidant activity, although there is still a lack of evidence to establish its oxy-radical scavenging activity. In this study, total oxy-radical scavenging capacity (TOSC) assay was used to evaluate antioxidant activity of total extracts (T-PG), polysaccharide fraction (Po-PG), and saponin fraction (Sa-PG) isolated from P. grandiflorum against peroxyl radicals and peroxynitrites. And MTT assay was taken to assess cyto-protective effects of T-PG, Po-PG and Sa-PG in H4IIE cells treated with hydrogen peroxide and tert-butylhydroperoxide. In the TOSC assay, Sa-PG showed strong oxy-radical scavenging capacity compared with T-PG and Po-PG. In cell-based assay, T-PG and Po-PG protected cells from oxidative stress, but Sa-PG did not protect cells because of cytotoxicity of Sa-PG. These results suggest that the saponin components of P. grandiflorum have relatively strong antioxidant capacity and cytotoxicity in rat hepatoma cells.