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기계적 합금화하여 제조한 Fe-5Y<sub>2</sub>O<sub>3</sub> 합금분말의 나노산화물 석출거동
김가언,노상훈,최지은,김영도,김태규,Kim, Ga Eon,Noh, Sanghoon,Choi, Ji Eun,Kim, Young Do,Kim, Tae Kyu 한국분말야금학회 2015 한국분말재료학회지 (KPMI) Vol.22 No.1
A precipitation behavior of nano-oxide particle in Fe-$5Y_2O_3$ alloy powders is studied. The mechanically alloyed Fe-$5Y_2O_3$ powders are pressed at $750^{\circ}C$ for 1h, $850^{\circ}C$ for 1h and $1150^{\circ}C$ for 1h, respectively. The results of Xray diffraction pattern analysis indicate that the $Y_2O_3$ diffraction peak disappear after mechanically alloying process, but $Y_2O_3$ and $YFe_2O_4$ complex oxide precipitates peak are observed in the powders pressed at $1150^{\circ}C$. The differential scanning calorimetry study results reveal that the formation of precipitates occur at around $1054^{\circ}C$. Based on the transmission electron microscopy analysis result, the oxide particles with a composition of Y-Fe-O are found in the Fe-$5Y_2O_3$ alloy powders pressed at 1150oC. It is thus conclude that the mechanically alloyed Fe-$5Y_2O_3$ powders have no precipitates and the oxide particles in the powders are formed by a high temperature heat-treatment.
제선공정 온실가스 저감을 위한 바이오매스 활용 대체 환원제 개발
김가언,오한상,이종협,박영주,이유빈,권재홍,김병철 대한금속·재료학회 2023 JOURNAL- KOREAN INSTITUTE OF METALS AND MATERIALS Vol.61 No.3
Technologies to reduce CO2 emissions in the steel industry have been actively developed since theearly 1990s in order to deal with global climate change. In particular, the utilization of various types ofbiomass including wood, bamboo, grass, food and agricultural by-product are being attempted as carbonneutral fuels in the blast furnace process. In this study, an alternative reducing agent for coke and pulverizedcoal using biomass was developed and the effect on blast furnace performance and CO2 reduction wasevaluated. The first investigation was whether a burden material made of torrefied biomass mixed with ironore and coal (Iron-bearing Biomass Coke, IBC) could be used as a substitute for coke in the form of acarbonized briquette. In addition, a method of mixing torrefied biomass with pulverized coal (Bio-PC) to injectthrough tuyere in a blast furnace was examined. As a result, when coke was replaced with 10% of IBC, thereducibility of the sintered ore was improved in association with an increased CO gas utilization ratio, henceCO2 emissions decreased by 2.3%. Furthermore, the combustion efficiency of Bio-PC mixed with 10% oftorrefied biomass was improved by 13.2%, thus, the amount of CO2 emissions was calculated to decrease by4%. These results suggest that the possibility of using IBC and Bio-PC in blast furnaces, as they couldeffectively reduce CO2 emissions in the ironmaking process.
제선공정 온실가스 저감을 위한 바이오매스 활용 대체 환원제 개발
김가언,오한상,이종협,박영주,이유빈,권재홍,김병철 대한금속·재료학회 2023 대한금속·재료학회지 Vol.61 No.3
Technologies to reduce CO2 emissions in the steel industry have been actively developed since theearly 1990s in order to deal with global climate change. In particular, the utilization of various types ofbiomass including wood, bamboo, grass, food and agricultural by-product are being attempted as carbonneutral fuels in the blast furnace process. In this study, an alternative reducing agent for coke and pulverizedcoal using biomass was developed and the effect on blast furnace performance and CO2 reduction wasevaluated. The first investigation was whether a burden material made of torrefied biomass mixed with ironore and coal (Iron-bearing Biomass Coke, IBC) could be used as a substitute for coke in the form of acarbonized briquette. In addition, a method of mixing torrefied biomass with pulverized coal (Bio-PC) to injectthrough tuyere in a blast furnace was examined. As a result, when coke was replaced with 10% of IBC, thereducibility of the sintered ore was improved in association with an increased CO gas utilization ratio, henceCO2 emissions decreased by 2.3%. Furthermore, the combustion efficiency of Bio-PC mixed with 10% oftorrefied biomass was improved by 13.2%, thus, the amount of CO2 emissions was calculated to decrease by4%. These results suggest that the possibility of using IBC and Bio-PC in blast furnaces, as they couldeffectively reduce CO2 emissions in the ironmaking process.
Metaplastic Carcinoma with Chondroid Differentiation Arising in Microglandular Adenosis
김가언,이지신,김나임,박민호 대한병리학회 2017 Journal of Pathology and Translational Medicine Vol.51 No.4
Microglandular adenosis (MGA) of the breast is a rare, benign proliferative lesion but with a significant rate of associated carcinoma. Herein, we report an unusual case of metaplastic carcinoma with chondroid differentiation associated with typical MGA. Histologically, MGA showed a direct transition to metaplastic carcinoma without an intervening atypical MGA or ductal carcinoma in situ component. The immunohistochemical profile of the metaplastic carcinoma was mostly similar to that of MGA. In both areas, all the epithelial cells were positive for S-100 protein, but negative for estrogen receptor, progesterone receptor, HER2/neu, and epidermal growth factor receptor. An increase in the Ki-67 and p53 labelling index was observed from MGA to invasive carcinoma. To the best of our knowledge, this is the first case of metaplastic carcinoma with chondroid differentiation arising in MGA in Korea. This case supports the hypothesis that a subset of MGA may be a non-obligate morphologic precursor of breast carcinoma, especially the triple-negative subtype.
Fe-5Y2O3 조성의 기계적 합금화 분말에 형성된 산화물의 상변태 거동
김가언,최정선,노상훈,강석훈,최병권,김영도,김태규 대한금속·재료학회 2017 대한금속·재료학회지 Vol.55 No.5
The phase transformation behavior of the oxides formed in mechanically alloyed Fe-5Y2O3 powder is investigated. Non-stoichiometric Y-rich and Fe-rich oxides with sizes of less than 300 nm are observed in the mechanically alloyed powder. The diffusion and redistribution reactions of the elements in these oxides during heating of the powder above 800 ℃ were observed, and these reactions result in the formation of a Y3Fe5O12 phase after heating at 1050 ℃. Thus, it is considered that the Y2O3 powder and some Fe powder are formed from the non-stoichiometric Y-rich and Fe-rich oxides after the mechanical alloying process, and a considerable energy accumulated during the mechanical alloying process leads to a phase transformation of the Y-rich and Fe-rich oxides to YαFeβOγ-type phase during heating.
열간일축가압한 Fe-5Y2O3 합금에 생성된 나노산화물의 미세조직
김가언 ( Ga Eon Kim ),김영도 ( Young Do Kim ),노상훈 ( Sanghoon Noh ),김태규 ( Tae Kyu Kim ) 대한금속재료학회(구 대한금속학회) 2016 대한금속·재료학회지 Vol.54 No.7
The microstructure of nano-sized oxide particles formed in Fe-5Y2O3 alloys uniaxial-hot-pressed at 1150 ℃ for 1 hour after a mechanical alloying of 95 wt%Fe and 5 wt%Y2O3 powders was examined. Several kinds of nano-sized oxide particles were found in the uniaxial hot pressed Fe-5Y2O3 alloy, and their crystal structures seemed to be Y2O3, Y3Fe5O12 and YFeO3. The oxide particles with diameters of about 20 nm showed a semi-coherent relationship with the matrix while those more than 200 nm in diameter exhibited a non-coherent relationship with the matrix, and this tendency appeared to be independent of the kind of oxide particles. †(Received September 11, 2015; Accepted January 9, 2016)
[Pd/Co]<SUB>5</SUB>/FeMn 초격자 다층 박막구조에서 수직 자기이방성과 교환바이어스에 관한 연구
김가언(Ka-Eon Kim),최혁철(Hyeok-Cheol Choi),유천열(Chun-Yeol You) 한국자기학회 2012 韓國磁氣學會誌 Vol.22 No.1
We investigate the exchange bias effect in [Pd/Co]<SUB>5</SUB> superlattice structures which are representative system of the perpendicular magnetic anisotropy. We fabricate Si/[Pd/Co]<SUB>5</SUB>/FeMn structures, and study the exchange bias variations by measuring hysteresis loop variations with thickness of FeMn layer. In order to optimize the perpendicular magnetic anisotropy, we fix the thickness of Pd with 1.1 nm and investigate the dependence of the perpendicular magnetic anisotropy on the ferromagnetic Co layer thickness. As results, we find that the biggest coercivity in 0.3 nm of Co layer without FeMn layer. The biggest exchange bias field is found for 0.3 nm of Co layer when we change the Co thickness with fixed FeMn thickness. When we vary thickness of FeMn layer, the biggest coercivity is found for 5 nm of FeMn layer. No exchange bias is observed when the FeMn layer is thinner than 3 nm, and the exchange bias field increases with FeMn layer thickness continuously up to 15 nm.