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상압소결에 의한 Al<sub>2</sub>O<sub>3</sub>/Fe-Ni 나노복합재료의 제조 및 자기적 특징
이홍재,정영근,남궁석,오승탁,이재성,Lee, Hong-Jae,Jeong, Young-Keun,NamKung, Seok,Oh, Sung-Tag,Lee, Jai-Sung 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.8
금속 산화물 상태으 혼합분말을 수소 환원하여 $Al_2O_3$ 분말 표면에 20 nm 크기의 Fe-Ni 합금이 균일하게 분산된 복합분말을 합성하였다. 상압소결을 이용하여 제조한 $Al_2O_3$/Fe-Ni 나노복합재료는 전 소결 온도 범위에서 단지 $Al_2O_3$와 ${gamma}$-Fe-Ni 상만으로 구성되어 있었고, $1350^{\circ}C$ 이상의 소결 온도에서 98% 이상의 치밀화를 이루었다. 최대 파괴강도와 파괴인성은 각각 574 MPa과 3.9 MP$a{\cdot}m1/2$로서 동일한 소결 조건의 순수 $Al_2O_3$ 보다 약 20% 증가하였다. 나노복합재료는 강자성 거동을 보였으며 분산상의 평균 입자 크기가 감소함에 따라 증가된 보자력 값을 나타내었다. The powder mixture in which Fe-Ni alloy particles of 20 nm were homogeneously dispersed on $Al_2O_3$ particle surfaces was prepared by hydrogen reduction of $Al_2O_3$ and metal oxide powders. $Al_2O_3$/Fe-Ni nanocomposites fabricated by pressureless sintering were only composed of $Al_2O_3$ and ${gamma}$-Fe-Ni phases and achieved over 98% of the theoretical density at the sintering temperature above $1350^{\circ}C$. The highest strength and toughness of the composites were 574 MPa and 3.9 MP$a{\cdot}m1/2$, respectively. These values were about 20% higher than these of monolithic $Al_2O_3$ sintered at the same conditions. Nanocomposites showed ferromagnetic properties and coercive force was increased with decrease of the average particle size of dispersions.
소결분위기 제어에 의한 Al<sub>2</sub>O<sub>3</sub>/Fe-Ni 나노복합재료의 제조 및 특성
이홍재,정영근,오승탁,이재성,Lee, Hong-Jae,Jeong, Young-Keun,Oh, Sung-Tag,Lee, Jai-Sung,Sekino, Tohru 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.2
소결 분위기가 금속입자분산 세라믹스기 복합체의 미세 조직 및 물성에 미치는 영향에 대하여 조사하고자 화학적 방법으로 합성한 $Al_2O_3$/Fe-Ni 나노복합분말을 수소 및 아르곤 가스 분위기, 또한 소결온도 등으로 제어하여 열간가압 소결하였다. 수소분위기에서 소결한 복합체는 아르곤분위기의 경우보다 반응상 $FeAl_2O_4$의 형성이 억제되었으며, 증가된 파괴강도 및 인성 값을 나타내었다. 또한, 소결 온도를 낮추었을 경우 기지상 및 금속 분산상의 미세화와 향상된 기계적 성질을 얻을 수 있었다. 소결 조건에 따른 기계적 특성의 변화는 주로 반응상의 형성과 관련된 미세조직 특성에 의존하는 것으로 해석하였다. To investigate an effect of sintering atmosphere on microstructure and properties of metallic particle dispersed ceramic based composites, the powder mixtures of $Al_2O_3$/Fe-Ni, synthesized by chemical solution process, were hot-pressed under different atmospheres such as hydrogen or argon gas and different sintering temperature. Hot-pressed composite in a hydrogen atmosphere exhibited less reaction phase of $FeAl_2O_4$ and enhanced mechanical properties than that in an argon atmosphere. Furthermore, decreasing hot-pressing temperature produced a refinement of ceramic matrix and metallic dispersion particles as well as improvement of mechanical properties. The change of mechanical properties in the composites with different sintering conditions was explained by microstructural characteristics relating to reaction phase formation.
이홍재(Hong Jai Lee),심영학(Young Hak Shim),김남동(Nam Dong Kim),임채선(Chae Seon Lim),이광훈(Kwang Hoon Lee),박금수(Kum Soo Park) 대한내과학회 1988 대한내과학회지 Vol.34 No.3
N/A In a study of about 1,000 bone marrow examinations performed in our haspital from 1981 to 1985, we selected 23 instances having 10 or more phagocytic histocytes in one bone marrow slide. The diagnosis, clinical features, laboratory findings and outcome of the patients with the phagocytic histiocytes were examined, and the results are as follows; 1) The disease were mainly infectious in orign, including typhoid fever, septicemia, leptospirosis, tuberculous pericarditis and EH fever, and the others were liver cirrhosis, Wilson's disease with hemolytic anemia, malignant lymphoma, myelodysplastic syndrome and agranulocytosis. 2) The clinica1 features were fever (86.8%), hepatomegaly (43.4%), splenomegaly (43.4%), lymphadenopathy (4.3%) and hemorrhagic tendency (4.3%). 3) The peripheral blood showed anemia in 82.6%, leukopenia in 39.1% and thrombocytopenia in 90.4% and reticulocytosis in some eases. 4) In blood chemistry studies, hypoalbuminemia was found in 86.8% and an increase of SGOT and alkaline phosphatase was noted in 95.7% and 78.9% respectively. LDH was increased in 100% (7/7). 5) The clinical courses of the patients with infectious diseases were good except 3 cases with fatal septicemia, and the other cases were not followed affer discharge.
각족 늑막저류에서 Adenosine Deaminase 활성도에 관한 연구
성낙억(Nak Uk Sung),신계철(Kye Chul Shin),이홍재(Hong Jai Lee),이경원(Kyung Won Lee) 대한내과학회 1987 대한내과학회지 Vol.33 No.2
N/A Adenosine deaminase (ADA) ia an enzyme of purine metabolism, which catalizes the irreversible hydrolytic deamination of adenosine to produce inosine and ammonia. ADA is essential for the differentiation of lymphoid cells, particularly T cells, and also plays a role in the maturation of monocytes to macrophage. Therefore ADA levels are related to stimulation of cellular immunity. Recent investigations have demonstrated that the determination of ADA in pleural fluid is useful in the differential diagnosis of pleural effusion. In this study, pleural fluid ADA activities were measured in 127 patients with pleural effusion of various causes, According to the final diagnosis, the patients was devided into 6 groups: tuberculosis was 47 cases, suspected tuberculosis was 23 cases, empyema was 22 cases, pneumonia was 12 cases, malignancy was 12 cases and transudate was 11 cases. The result obtained were as follows: 1) The mean ADA activity in tuberculous effusion was 124.1±6.4 U/L, suspicious tuberculous effusion was 116.2±8.1 U/L, empyema was 112.2±18.3 U/L, parapneumonic effusion was 38.9±4.5 U/L, malignant effusion was 26.8±3.1 U/L, and transudative effusion was 7.4±1.5 U/L. 2) The ADA activities in exudative effusions showed significatnly higher values than those in transudative effusion (P<0.001). 3) The ADA activities in tuberculous effusions and empyema showed no significantly higher values than those in malignant or parapneumonic effusion (P<0. 001). 4) The ADA activities in tuberculous effsuions showed no significant difference compared with empyema (P>0.05). 5) The ADA activites above 50 U/L had a sensitivity of 100% and a specificity of 92% when used as a screening test for tuberculous effusions. 6) In tuberculous effusions, ADA activities showed no significant difference according to age, sex, onset, amount of effusion and association with pulmonary tuberculosis. It is suggested that the measurement of pleural fluid ADA activity, if excluding empyema, is a simple reliable test for the differential diagnosis of tuberculous and malignant pleural effusion.
李洪宰 順天大學校 1982 論文集 Vol.1 No.1
階段式 新墾地의 桑田에 稻藁單用, polyethylene 單用, 稻藁, poly 竝用의 被覆處理 效果 試驗을 한 結果는 다음과 같다. 1. 土壤의 保水力 增大와 土壤濕度의 適正 維持를 한다. 2. 雜草發生을 土壤 表面積의 10% 以內로 抑制한다. 3. 春期에 先枯長을 3cm 以內로 抑制한다. 4. 土壤의 3相(液相·氣相·固相) 調節效果를 增大하고 化學肥料의 施用效率을 높여주며 保肥性을 向上시킨다. 5. 土壤의 酸性化와 寒害 및 土葉을 防止한다. 6. 雨水의 流失 억제로 地下浸透를 增大한다. 7. 桑葉質이 優秀하고 桑收量이 增大되며 安定된다. 8. 夏期 桑葉의 黃化 및 粗硬化를 防止한다. 9. 蟲害豫防에 效果가 있고 土壤의 物理 化學性을 改善한다. 10. 透水性이 나쁜 桑田일수록 生育機物을 바로 매입하지 말고 被覆하여 썩혀가지고 土壤에 混入한다. The author has tried a straw-mulch, a poly-mulch, and a straw and poly-mulch on a newly cultivated terraced mulberry field, and the observed effects are like followings. 1. It increased water-retaining capacity of soil and maintained the proper dampness of soil. 2. It restricted weeding to only 10% of soil surface. 3. It preserved the branches from drying up so that drying doesn't expand to more than 3cm from the end. 4. It regulates the three phases of soil and increases the effects of chemical fetilizers and inhance the fertilizer-preservation power of soil. 5. It prevents soil from changing into acid and from having cold injury and soil leaf. 6. It prevents rain water from going out the mulberry field and makes the water saturate into underground. 7. It increases mulberry leaves out put of good quality. 8. It prevents mulberry leaves from etiolation, hardening, and becoming rough skin. 9. It prevents insect injury and it improves physical and chemical conditions of soil. 10. In the care of ill-pervious mulberry field, organic matter should be scattered after we made it into farmyard manure through mulching instead burying raw stuffs in soil directly.
김우성,이선화,김상엽,정동윤,김재이,이영자,이홍재,정성욱,박흥재 한국환경과학회 2003 한국환경과학회지 Vol.12 No.10
Pesticides were extracted from samples with 70% acetone and methylene chloride in order, and then cleaned up via open-column chromatography apparatus packed with fiorisil, and finally analyzed simultaneously the organophosphorus pesticides using GC/NPD, Ultra-2 and Ultra-1 fused silica capillary columns were used to separate and identify the products. Recovery of most analytes from soybean sample, taken from pesticide residues well, was greater than(80%) for all except(6) analytes. This method can simultaneously determine multiple pesticides with a high degree of accuracy and precision.