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.

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.

상부위장관출혈에서 Hypertonic Saline-Epinephrine 용액 국소주사의 지혈효과

정현용,이헌영,김영건 충남대학교 의과대학 지역사회의학연구소 1990 충남의대잡지 Vol.17 No.2

We have assessed the hemostatic efficacy of endoscopic HS-E solution injection sclerosis in the upper gasrointestinal bleeding. A total 27 cases admitted to CNUH internal medicine department from november 1989 to october 1990 were included in this treatment model and the following results were obtained : 1. The causes of bleeding were gastric ulcer(44%), duodenal ulcer(25.9%), Dieulafoy's ulcer (18.5%), advanced gastric cancer(3.7%), Mallory-Weiss syndrome(3.7%) and angiodysplasia(3. 7%). 2. The locations of bleeding were high body(25.9%), angle(18.5%), bulb(18.5%), antrum(14.8%), midbody(3.7%), cardia(3.7%), pyloric canal(3.7%) and stoma(3.7%). 3. Endoscopic findings of UGI bleeding showed active bleeding in 51.9% (14/27 cases) as spurting (11.1%). pulsating(22.2%) and oozing(18.9%). Stigmatas of recent bleeding were 48.1% (13/27cases) as denuded vessels(29.6%) and fresh blood clots(18.9%). 4. The hemostatic effect of HS-E solution injection sclerosis was 92.6%(25/27 cases). The sussess rate of first injection was 70.3%(19/27), second injection 14.8% and third injection 7.4%. Two cases(7.4%) were operated for hemostasis. 5. According to bleeding types viewed endoscopically, hemostatic effects were following sussess rate ; spurting cases 67% (2/3), pulsating cases 83% (5/6), oozing 100% (5/5). Others showed 100% of sussess rates.

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).

胃食道 異物의 內視鏡的 除去

정현용,이헌영,김영건 충남대학교 의과대학 지역사회의학연구소 1993 충남의대잡지 Vol.20 No.2

Gastrointestinal foreign bodies present a significant problem, causing a surprising amount of morbidity and mortality. The clinician is presented with the problem of expectant management, endoscopy, and surgery, to obtain an optimal outcome. We have assessed the efficacy of endoscopic removal in the gastroesophageal foreign body. A total 19 cases admitted at CNUH hospital from january 1991 to december 1993 were included in this treatment model and the following results were obtained : 1) The age distribution varies 10 months to 74 years old, prevalence rate under 5 years of age was 4 cases(21%). 2) Foereign bodies were :lodged in the esophagus 12 cases(normal anatomy 7 cases, benign stricture 5 cases) and in the stomach 7 cases. 3) Nature of foreign bodies was meat ball, marble, check, coin, fish bone, animal bone, video key and bean. 4) Patients with esophageal foreign body were always complained dysphagia or odynopgagia, patients with stomach foreign body were chiefly asymptomatic. 5) Accessory using in endoscopic removal were grasping forceps, alligator forceps, stone extraction baskets, polypectomy snare and laser equipment. 6) All cases were successfully removed by endoscopy, there were no complication during procedure.

DNA 감지를 위한 MOSFET형 전하검출센서의 제작 및 특성

정용택,김동선,류홍근,박혜정,신장규,최평,이종현,임근배 경북대학교 센서기술연구소 2002 센서技術學術大會論文集 Vol.13 No.1

일부 종합병원 병리조직실 공기 중 포름알데히드 농도

정규현,하안례,이용환 고신대학교 보건과학연구소 2002 보건과학연구소보 Vol.12 No.-

Formaldehyde irritiates mucous membranes in the eyes, nose, and upper respiratory tract, and it is a potential carcinogen. The purpose of this study was to assess the time-weighted average (TWA) and short-term exposure limit (STEL) concentration to formaldehyde exposure and to suggest proper improvement strategy to minimize exposure. This study was conducted at 3 histopathology laboratories in the hospitals located in Busan from January 20 to March 10, 2002. Formaldehyde and organic solvents (ethanol and xylene) were sampled by personal air sampler and analyzed by gas chromatography. The obtained results were as follows. 1. TWA concentrations of formaldehyde ranged from 0.28 to 10.64 ppm and those of two laboratories out of 3 were exceeded the threshold limit value (TLV). 2. In one laboratory, STEL concentrations was exceeded threshold limit value (TLV), as 2.39 ppm. 3. TWA concentrations of ethanol and xylene were under the TLVs. It is necessary to improve the local ventilation systems and other facilities to prevent the personnels in the laboratories from the diseases due to formaldehyde exposure.

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.

상부소환관협착에 대한 Savary-Gilliard Dilatation의 치료효과와 안전성에 관한 관찰

정현용,육은주,임의혁,김병호,성자원,이기천,허승식,이헌영,김영건 충남대학교 의과대학 지역사회의학연구소 1992 충남의대잡지 Vol.19 No.2

For the patient with stenosis of upper digestive tract caused by either benign or malignant process, esophageal dilatation is an important therapeutic modality. We reviewed retrospectively 39 cases treated by Savary-Gilliard dilatation for upper digestive tract stenosis, and results were follows : (1) Dysphagia was improved in 95% of the patients. (2) Eight patients(20%) sufferd perforation, five of them were managed with conservative medical measures, others were managed operatively. (3) In the cases with benign stenosis dysphagia was not noticed for 8.8 months, but with malignant stenosis dysphagia was reappeared after 2.8 months despite concomitant chemoradiotherapy. In conclusion, Savary-Gilliard dilatation was an effective measure for symptome due to upper digestive tract stenosis, but more careful attention for perforation should be necessitated. Also another therapeutic modality for treatment of malignant stenosis was inevitable.