Study on Microstructure and Mechanical Properties of the Al–25Cr–5Si (at%) Alloy Powder Using Gas-Atomization and SPS Process

Yong‑Ho Kim,Hyo‑Sang Yoo,Jeong‑Han Lee,Ik‑Hyun Oh,Hyun‑Kuk Park,Hyeon‑Taek Son 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

In order to investigate the microstructure and mechanical properties on Al–25Cr–5Si (at%) alloy, a mixed powder with pureelements and an alloy powder using a gas atomization process were used. Fine and high purity Al–25Cr–5Si (at%) alloypowder was successfully prepared by gas atomization and densified using a spark plasma sintering (SPS) process. The overallpowder size distribution of the mixed Al, Cr, and Si elemental powders was in the range of 10–15 μm. The atomized Al–Cr–Sialloy powder was fine and spherical in morphology and difficult to be formed by intermetallic formation. Densification wasclearly confirmed at 1000 °C, with almost isolated pores formed, by clear removal of pores between particles, deformationof particles, an increase in the number of contacts, and a change in size between particles. As a result of XRD analysis ofthe sintered compacts, single phase was observed using the mixed powder, but the compact using gas atomization remainedthe alloy phase even at the process temperature. The Vickers hardness of the compacts by mixed powder was observed at59.70 Hv and the compact using gas atomized powders on the temperature 1000 °C of the Vickers hardness increased to702.6 Hv. The compressive yield strength of the compact with mixed powder was 195.24 MPa and the compressive strengthof the compact with gas atomized powder increased to 802.07 MPa. It is considered not to be decomposed by the AlCrSi,Al13Cr4Si4and Al8Cr5phases sintering process, resulting from the improvement of mechanical properties.

니페디핀이 암피실린의 흡수에 미치는 영향

정현정,용철순,최윤수,오두만 영남대학교 약품개발연구소 1997 영남대학교 약품개발연구소 연구업적집 Vol.7 No.-

Amino-β-lactam antibiotics are absorbed by the dipeptide transporter in the small intestine. These uptakes are coupled to a proton influx. The inward proton gradient is partly induced by the Na^(+)/H^(+) exchanger and cakium ion is involved in control of this antiport. Interaction between ampicillin which is one of the amino-β-lactam antibiotics and nifedipine which is one of calcium channel blocking agents was studied in rats in vivo and with rabbit jejunum mounted on the Sweetana/Grass diffusion cells in vitro. Bioavailability of ampicillin was increased significantly when nifedipine was co-administered orally in rats. There were no differences in the distribution phase and the elimination phase when ampicillin was given either alone or with nifedipine intravenously. Conditions for in vitro experiments were determined. The lift rate of O₂/CO₂ gas was controlled to 3 bubbles/sec and ampicillin was stable in the Kreb's buffer at pH6.0 Absorption of ampicillin was the greatest when the completely-stripped serosal membrane was used. Transport of ampicillin from mucosal to serosal side in the rabbit jejunum was enhanced by 32% in the presence of nifedipine (p=0.059). Above results suggest that nifedipine might increase the plasma level of ampicillin via the improved absorption in the intestine rather than the reduction in the elimination or/and alteration in the distribution.

혈액투석 환자에게서 발생한 재생불량성 빈혈 1예

정지용,윤나라,강대웅,오종찬,장재현,선길홍,박경희,정종훈,김현리 朝鮮大學校 附設 醫學硏究所 2005 The Medical Journal of Chosun University Vol.30 No.1

Aplastic anemia is a disease characterized by pancytopenia in the peripheral blood and hypocellular bone marrow with the fatty infiltration. The causes of the acquired aplastic anemia were usually related to drugs and immune-related diseases. A 34-years old man was admitted due to general weakness. He has been going hemodialysis for 2 years because of end stage renal disease (ESRD) due to chronic glomerulonephritis. At admission, laboratory tests showed hemoglobin 6.2 g/dL, hematocrit 18.0 %, WBC 5,710mm (neutrophil 71.8%, lymphocyte 19.1%, monocyte 5.9%), reticulocyte 1.9%, platelet 93,000/mm, Fe 12.8 ug/dL, TIBC 204 ug/dL, ferritin 941.47 ng /ml, haptoglobin 0.72 g/L, vitamin B12 508.17 pmol/L, folate 24 ng/mL, total protein 6.54 g/dL, albumin 3.76 g/dL, Alk. pohsphatase 79 IU/L, AST 30.0 IU/L, ALT 39.7 IU/L, total bilirubin 0.57 mg/dl, BUN 79.4 mg/dl and creatinine 10.18 mg/dl. Peripheral blood smear showed the normocytic normochromic anemia with anisocytosis. Anemia was diagnosed but it was irresponsive to the recombinant human erythropoietin (EPO) and blood transfusion. In the bone marrow aspiration smear were there the hypoplastic myeloid and erythroid precursors. The bone marrow biopsy section showed the hypoplasia of all components (10-20%) and the fatty infiltration. We have experienced one case of the idiopathic aplastic anemia in a patient going through hemodialysis and we just report it with documentary records. 저자들은 혈액 투석 중인 환자에서 약물, 면역계 이상등의 원인을 발견할 수 없었음에도 재생 불량성 빈혈이 발생한 1예를 경험하여 문헌 고찰과 함께 보고하는 바이다.

농촌주민의 혈중 납과 카드뮴 농도에 관한 조사연구

정현숙,조영채,이동배 忠南大學校 環境問題硏究所 1991 環境硏究 Vol.9 No.-

The purpose of this study was to find out blood lead and cadmium concentration levels of rural residents. The blood samples were collected from 140 rural residents in 5 nonpolluted regions in Kunbuk-Myun, Kumsan-Gun, Chungnam province from August 31 to September 30, 1990 and analyzed by atomic absorption spectrophotometry. The results were summerized as follow : The mean concentration level(range) of blood lead was 0.240±0.060㎍/ml(0.130-0.390㎍/ml) for males and 0.237±0.056㎍ /ml(0.120-0.370㎍/m) for females. There was no statistically significant difference among age groups and sexes. The distributions were similar to normal distribution in both sexes. The mean concentration level(range) of blood cadmium was 0.066±0.099㎍/ml(0.012-0.582㎍/ ml) for males and 0.060±0.062㎍/ml(0.015-0.392㎍/ml) for females. There was no statistically significant difference among age groups and sexes. The distributions were skewed to the low level ranges in both sexes. The lead concentration level in whole blood did not show statistically sinificant difference among kinds of farming product. But the cadmium level of the rice-ginseng-tobacco farmers was statistically significantly high (p<0.005). The cadmium concentration level in whole blood was 0.040±0.027㎍/ml for the rice-ginseng farmers, 0.076±0.100㎍/ml ofr the rice-tobacco famers, and 0.158±0.171㎍/ ml for the rice-ginseng-to-bacco farmers. There were no statistically significant difference in blood lead and cadmuim concentration levels among groups classified by drinking habit, smoking habit and exposed years to pesticides. The correlation coefficent between the blood lead and cadmium concentration levels was statistically significant(R=0.2054, P<0.05).

소화성 궤양 환자에 대한 염산 베넥세이트(울굿^(�)) 임상 효과

정현용,육은주,이헌영,노홍구,김영건 최신의학사 1993 最新醫學 Vol.36 No.8

石菖蒲가 血壓 및 局所腦血流量에 미치는 影響

鄭鉉雨,康城溶,白承化 대한본초학회 1999 大韓本草學會誌 Vol.14 No.2

Rhizoma Acori Graminei(RAG) has been used in Korea for many centuries as a therapeutic agent for cerebral disease. The effect of RAG on the vascular system is not known. The purpose of this study was to determine the effect of RAG on Blood Pressure(BP) and regional Cerebral Blood Flow(rCBF) of male Sprague-Dawely rats. The changes in rCBF were determinated by Laser-Doppler Flowmetry(LDF). The results were as follows : 1. Blood pressure was not affected by RAG in rats. 2. rCBF was increased by RAG in a dose-dependent manner. 3. Pretreatment with propranolol significantly inhibited RAG induced increased rCBF. 4. Pretreatment with methylen blue and ODQ significantly inhibited RAG induced increased rCBF. 5. Pretreatment with L-NNA significantly inhibited RAG induced increased rCBF. These results suggest that RAG causes a diverse response of blood pressure and regional cerebral blood flow(rCBF). The increased in rCBF is also mediated by adrenergic β-receptor, nitric oxide synthease and guanylate cyclase.

VES-LMC 덧씌우기를 이용한 콘크리트 포장 보수

정원경,김용곤,김기헌,윤경구 강원대학교 산업기술연구소 2005 産業技術硏究 Vol.25 No.B

Since in 1970, the length of concrete pavements(JCP, JRCP and CRCP) are growing rapidly at both of main highways and local roads. Many of them are deteriorated and old enough to be repaired or replaced. The pavement is more important than the other infrastructures and it is very difficult to go around or block the traffic during the rehabilitation. The very-early strength latex-modified concrete(VES-LMC)may offer the advantages of high-early-strength, higher flexural strength, higher bond strength, and improved durability. The VES-LMC could be used at a kind of fast track ofr early opening to the traffic after 3 hours of concrete placement. The installation of VES-LMC overlay at Jung-Boo highway was successfully done from April 28 to 29, 2005. The traffic was closed at 07:00 PM and opened to traffic at 08:30 AM. The compressive and flexural strength of VES-MC were more than 28MPa, 6.2MPa after 4 hours, respectively.

위암조직에서 Carcinoembryonic Antigen 측정의 의의

정현용,윤세진,이헌영,김영건 충남대학교 의과대학 지역사회의학연구소 1991 충남의대잡지 Vol.18 No.2

To estimate tumor CEA expression of stomach cancers in relation to normal mucosa CEA, degree of cellular differentiation, pathologic stage and other clinicopathologic findings, we measured CEA concentrations in tissue extracts by radioimmunoassay for 24 cases of stomach cancer. The results were as follows: 1. Ranges of tissue CEA concentrations in normal stomach mucosa was from 6.Ong/gm to 15.4 ng/gm(mean 10.2ng/gm). 2. Mean conceatrations of cancer tissue CEA was 42.1ng/gm(from 2.9 ng/gm to 414.Ong/gm), 4 times higher than normal mucosa. In 46% of stomach cancers, tissue CEA concentrations was above normal cut off value(18.7ng/gm). 3. Tiuse CEA concentrations of stomach cancer was significantly high as high CEA levels of normal mucosa(r=0.6954), not related to serum CEA concentrations. 4. Tissue CEA concentrations of stomach cancer was high as high TNM stage, but was not related to wall invasion depth, lymph node metastasis, cellular differentiation and other clinicopathologic findings. In conclusion, the production of CEA in stomach cancers was significantly increased in half cases, CEA expression of tumor was related to pathologic stage rather than cellular differentiation. The factors determined CEA production was considered more higher levels such as DNA profile. To estimate prognostic values of tissue CEA concentrations, follow up of included patients and further study should be pursued.

재배 콩나물 저장 중 온도처리가 isoflavone 함량에 미치는 영향

정연신,이향미,Krishna Hari Dhakal,김용훈,이정동,신동현,황영현 경북대학교 농업과학기술연구소 2008 慶北大農學誌 Vol.26 No.-

콩나물로부터 고 isoflavone 함량의 콩 식품윈료를 얻고자 콩나물 재배 시 빛을 쪼여주고, 재배한 콩나물의 저장온도를 달리한 조건에서 isoflavone 함량변이 를 조사하였다. 공시 품종들의 7일 재배 후 저장하기 전 isoflavone함량은 아가 3호>아가 1호>아가 2호>아가 4호>장기콩>보석콩>은하콩>풍산나물콩 순이었는데 아가 3호의 isoflavone 함량은 4,619㎍/g이었다. 재배한 콩나물의 isoflavone 함량은 저장온도에 따라 품증별로 상이한 차이를 보였는데, 저장온도 6℃와 20℃에서 isoflavone함량이 높은 반면 저장온도 9℃와 30℃에서는 대부분 콩 품종들의 isoflavone 함량은 낮았다. 저장일수에 따른 isoflavone의 함량은 품종들 간에 일정한 경향이 없었으나 대부분의 품종들은 저장기간 3일 이내에 가장 높은 isoflavone 함량을 보였고, 아가 4호와 장기콩은 저장기간 5일에서도 높은 isoflavone의 함량을 보였다. 저장기간과 온도처리를 하여 재배한 콩나물의 isoflavone 함량을 높이고자 한 결과 아가 3호를 포함하여 공시한 8품종 중 4품종에서 20'C에서 하루 동안 저장했을 때 가장 높은 isoflavone의 함량을 나타내었다. 재배한 콩나물들 중 저장을 통해 가장 높은isoflavone의 함량을 보인 품종은 아가 3호로써 저장후의 isoflavone 함량은 11,705㎍/g이었다. 본 연구에서는 콩나물 저장기간 동안 수분공급이 지속적으로 이루어겼기 때문에 콩나물이 계속 성장한 것으로 생각된다. 따라서 저장기간 동안 온도처리를 달리하여 isoflavone의 함량을 증가시키는 보다 확실한 방법을 확립하기 위해서는 더 많은 연구가 이루어져야 할 것으로 생각되어진다. To obtain food materials of high isoflavone content from soy-sprouts, 8 soy-sprout varieties, Aga 1, Aga 2, Aga 3, Aga 4, Pungsannamulkong, Eunhakong, Jangkikong and Bosugkong, were grown into soy-sprouts for 7 days under light condition and stored for 5 days at 6 different temperatures; 3, 6, 9, 20, 30, and 40℃ in the dark. The isoflavone content of 7 days grown sprout varieties were highest in the order of Aga3>Aga 1>Aga 2>Aga 4>Jangkikong>Bosugkong>Eunhakong>Pungsannamulkong. The highest isoflavone content of Aga 3 was 4,619 ㎍/g. The isoflavone content of soy-sprouts showed much varietal differences depending on the storage temperatures. Comparative high isoflavone content was obtained at storage temperatures of 6℃ and 20℃ while most of varieties showed low isoflavone content at 9℃ and 30℃. No constant trend in isoflavone content for the tested varieties along with the days to storage but most of varieties showed the highest isoflavone content in 3 days of storage. On the contrary, Aga 4 and Jangkikong showed high isoflavone content even at 5 days of storage . The comparatively high isoflavone content for 4 varieties including of Aga 3 out of 8 varieties was obtained from the treatment of one day storage at 20℃. Out of all treatments, the highest isoflavone content was obtained from one day storage at 20℃ for Aga 3 and the content was as high as 11,705 f-㎍/g. In this experiment, soy-sprouts were believed to be made continuous growth during the storage because the sprouts were being dipped in water during the temperature treatment to protect soy-sprouts from drying. Thus, it is inferred that additional researches should be made to establish better method to increase isoflavone content in soy-sprouts during the storage.

신경회로망을 이용한 지능형 로봇 제어 시스템 설계

정동연,김용태,한성현 경남대학교 공업기술연구소 2000 硏究論文集 Vol.18 No.-

본 논문에서는 일반적으로 고정된 위치에서 검사하는 비젼 시스템이 아닌 카메라를 로봇의 말단효파부에 장착하여 렌덤하게 움직이는 물체를 추적하여 지능적으로 매니퓰레이터의 위치 및 속도를 제어하여 정확한 위치에 납땜 작업을 한 후 비젼 검사를 실시하는 로봇 비젼 시스템을 설계한다. 자동검사를 위한 비젼기술은 실시간 실현을 위해 디지털 신호 처리기를 사용한 새로운 고성능 비젼 알고리즘을 개발해서 S사의 전자부품 조립검사라인, 즉 카메라 조립검사라인에서 라인을 따라 흘러 들어오는 백커버(Back Cover)들을 정해진 위치를 따라 로봇을 이동하여 자동 인식한다. 인식된 백커버의 납땜상태를 다양한 위치 및 이동공정에서 대해서도 유연하게 검사를 자동으로 수행하고 품질기준 통과여부를 자동 판단할 수 있는, 이른바 다공정 제품의 형상인식 및 자동검사용 로봇 비젼 기술을 개발하기 위한 연구가 수행되었다. 그리고 제안된 로봇 비젼 시스템의 성능을 컴퓨터 시뮬레이션 및 실험을 통하여 S사의 조립라인중 5번 Cell의 유사공정을 모델링하여 그에 대한 유사한 실험을 통해 그 신뢰성을 입증하고자 한다. In this paper, we have proposed a new approach to the design of robot vision system to develop the technology for the automatic test and assembling of precision mechanical and electronic parts for the factory automation. In order to perform real time implementation of the automatic assembling tasks in the complex processes, we have developed an intelligent control algorithm based-on neural networks control theory to enhance the precise motion control. Implementing of the automatic test tasks has been performed by the real-time vision algorithm based-on TMS320C31 DSPs. It distinguishes correctly the difference between the acceptable and unacceptable defective item through pattern recognition of parts by the developed vision algorithm. Finally, the performance of proposed robot vision system has been illustrated by experiment for the similar model of fifth cell among the twelve cell for automatic test and assembling in S company.