Effects of Pilger Rolling and Heat Treatment on Microstructure and Corrosion Resistance of Ag-electroplated 304 Stainless Steel Tubes

Hyun Park,Woo‑Jin Lee,Jae‑Han Son,Han‑Kyun Shin,Sung‑Kyu Hong,Hyo‑Jong Lee 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8

We introduce a cost-effective method that combines electroplating with metal cold working processes to manufacture compositetubes with robust corrosion resistance. First, a 3-step electroplating process was developed to form an adhesive anduniform Ag coating on the outer wall of a 304 stainless steel tube. The process consisted of a Ni-strike step for removing thepassivation layer of the initial 304 tube, Cu deposition for smoothing the surface by adding a buffer layer, and Ag deposition. To reinforce the interfacial adhesion between the electroplated layers and the 304 tube and increase the area of the Ag coating,a pilger rolling or pilger rolling + heat-treatment process was performed after the Ag electroplating process. Scanningelectron microscopy of the composite tubes after each process indicated that the as-deposited Ag coating changed fromhaving a rough to smooth surface after only pilger rolling and with additional heat treatment. Electron backscatter diffractionanalysis of the microstructures and textures of the tubes revealed that dynamic recrystallization occurred extensively duringpilger rolling, resulting in the formation of a relatively defect-free grain structure without heat treatment. Furthermore,electrochemical polarization curves determined that the Ag-coated composite tubes are superior to the uncoated 304 tubein terms of corrosion resistance under Cl−atmosphere, owing to the formation of a AgCl passivation layer during testing. Surface analysis of the composite tubes suggests that the properties of the AgCl passivation layer are related to the grainsize of the Ag coating and the density of plastic-deformation-induced defects.

DOC의 K-7 Mode에 의한 배기가스 저감에 관한 연구

한영출,백두성,오용석,박만재,박귀열,류규현 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.3

With the significant growth of the number of vehicles, environmental problems is raised. NOx, SOx, and PM emissions in diesel powered vehicles are larger than that in gasoline, because the development of pollutants reduction techniques has no: been yet achieved. So it is need to develop after-treatment or to convert into alternative fuel to satisfy emission regula-tion. Among the after-treatment systems to reduce the diesel emissions, studies with diesel oxidation catalyst(DOC) are done greatly. In this study using DOC, reduction efficiency with the change of temperature and catalyst loading was calculated through measurements of CO, HC, PM, and SOx.

터보 차져와 인터쿨러를 장착한 디젤기관의 시뮬레이션 연구

한영출,백두성,류규현,오용석,박만재 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.4

Studies on the turbocharger itself or various aspects generated from turbocharged engine have been made. However, only a few researches have been made on the performance for the natural aspirated engine equipped with the turbocharger and the intercooler. In this study, the performance prediction program based on turbocharger theory is developed for simu-lation which may reduce the cost and the trial-and-error time. The program is verified with the experimental results for 11,000cc diesel engine with the turbocharger and the intercooler. Also, various factors which are invisible in experiment are predicted using this program.

Experimental study on condensation heat transfer characteristics of special heat transfer tubes

한규일,박종운,권영철,조동현 대한설비공학회 2001 설비공학 논문집 Vol.13 No.9

In this study, condensation heat transfer characteristics were conducted with special heat transfer tubes of SH-C type. Experiments were carried out the saturated vapor temperature of 334K and the wall subcooling of 1.5-4.5K. The refrigerant was R-113 and the enhanced tubes used in the present study were SH-CDR, SH-CYR and SH-CHR. The experimental results showed that the condensation heat transfer coefficients of SH-C type tubes were about 23-66% higher than those of a low integral-fin tube. It was visualized that the condensed liquid on the outer surface of SH-C type tubes flowed continuously down unlike a low integral-fin tube and a plain tube, due to a 3-D extending fin on the outer surface of SH-C type tubes. As a result, the thermal resistance of the condensed liquid decreased and the heat transfer coefficient increased. Also, the enhancement ratio of SH-CDR tube was the highest, and it was about 9-11 times as compared to that of a plain tube.

사람 갑상선자극호르몬 수용체를 발현하는 Chinese Hamster Ovary(hTSHR-CHO)세포를 이용한 자극형 갑상선자극호르몬 수용체 항체 활성 측정의 임상적 유용성

한희정,원진호,채수홍,김현진,송민호,김영건,노흥규 충남대학교 의과대학 지역사회의학연구소 2000 충남의대잡지 Vol.27 No.1

Detection of thyroid stimulating hormone receptor(TSHR) autoantibodies has clinical value in establishing the diagnosis of Graves ' disease, and in predicting its clinical course with high sensitivity and high specificity. Especially, TBII using radioreceptor assay has been widely used. Recently, for detecting thyroid stimulating antibody(TSAb), a sensitive method using human TSH receptor-transfected Chinese Hamster Ovary(CHO) cells has been developed and clinically used. The aims of this study are to determine the change and discrepancy of 2 TSHR autoantibodics in clinical course and to evaluate the correlation between 2 autoantibodies. We measured TSAb and TBII in 30 newly diagnosed and untreated patients and in 73 previously diagnosed as Graves ' disease and treated with antithyroid drug. Also we compared the changes of the antibodies in clinical course and correlation between 2 antibodies. Thes results are summarized follows. 1. In newly diagnosed patients, all of the 30 patients had positive TBII and/or TSAb. None of them had negative TBII and negative TSAb. And in newly diagnosed patients, mean TBII and mean TSAb values are 46.8% and 361%, respectively. In 73 treated patients mean values are 18. 7% and 196% each other. Therefore, newly diagnosed group has significant greater TBII and TSAb than antithyroid drug-treated group. 2. TBII was significantly different between euthyroid group and thyrotoxic group in antithyroid drug-treated patients, but TSAb was not. 3. TBII was sequentially decreased as increased medication duration, but TSAb was not shown sequential decrease as increased medication duration. 4. There was significant negative correlation between cumulative doses of antithyroid drug and TBII, but no significant correlation between cumulative doses and TSAb. 6. There was significant positive correlation between TBII and TSAb in total patients group and in antithyroid drug medication group, but not in newly diagnosed group. In conclusion, in Graves ' disease patients, detection of TSHR antibodies are clinical values in establishing the diagnosis and prediction of clinical course. A method detecting TSAb using hTSHR-CHO cells should be further studied for standardization of measurement, and for detecting the changes of TSAb in clinical course, long-term follow-up of patients are important.

직업적 연폭로에서 혈중 연량 수준에 따른 선별검사로서의 혈중 ZPP 검사의 타당도

한구석,안현철,김용배,리갑수,김화성,황규윤,장봉기,이성수,안규동,이병국 순천향대학교 산업의학연구소 1999 순천향산업의학 Vol.5 No.1

In order to evaluate the validity of current screening criteria of lead exposure and to provide effective information for the better health management of lead workers, author investigated the interrelationship between blood lead and blood zinc protoporphyrin(ZPP) and evaluate the validity of blood zinc protoporphyrin as the screening test and blood lead as gold standard of diagnostic test. The total of 2245 lead workers (male workers: 1982, female workers : 263) from 12 lead using industries were studied. Blood lead, ZPP, hemoglobin and hematocrit were selected as lead exposure variables. Personal information on sex, age and work duration were also checked. Blood lead was measured with flameless atomic absorption spectrometry (model: Hitachi 8100) using standard addition method. Blood ZPP was measured with portable hematoflurometer (model: Aviv 206). The results obtained were as follows: 1. The mean blood lead of all lead workers were 0.7±14.3㎍/㎗(Male: 31.0±14.4㎍/㎗, Female: 28.2±12.9㎍/㎗), whereas the mean blood ZPP of those were 68.1±47.5㎍/㎗(Male: 63.9±43.7㎍/㎗, Female: 100.1±61.0㎍/㎗). The mean value of hemoglobin and hematocrit of all lead workers were 14.5±1.5g/㎗(Male: 14.7±1.3g/㎗, Female: 12.3±1.2g/㎗) and 45.4±3.6(Male: 46.2±2.8, Female: 39.5±3.1) respectively. 2. Validity of test using blood zinc protoporphyrin as screening test for blood lead levels of 30㎍/㎗ as gold standard of diagnostic test revealed that the highest validity value for male and female lead workers were 50 and 90 ㎍/㎗ of ZPP respectively, showing 50 and 60 ㎍/㎗ of ZPP for all lead workers. While those test for blood lead levels of 40㎍/㎗ as gold standard of diagnostic test revealed that the highest validity value for male and female lead workers were 60 and 90 ㎍/㎗ of ZPP respectively, showing 60 ㎍/㎗ of ZPP for all lead workers, those test for blood lead levels of 50 and 60㎍/㎗ as gold standard of diagnostic test revealed that the highest validity value for male and female lead workers were 60 or 70 and 100 ㎍/㎗ ZPP respectively, showing 60and 70 or 80 ㎍/㎗ of ZPP for all lead workers. 3. Predictive value of test using blood zinc protoporphyrin as the screening test for different blood lead levels of 30, 40, 50 and 60㎍/㎗ as gold standard of diagnostic test revealed that positive predictive value of screening test were decreased by the increase of blood lead level regardless of csreening criteria value ZPP and negative predictive value of screening test were increased accordingly regardless of screening criteria value of ZPP. On the other hand, within same blood lead level as a gold standard positive predictive values were inceased by the increase of screening criteria value of ZPP, whereas the negative predictive value were decreased accordingly by the the increase of screening criteria value of ZPP. 4. The correlation analysis of all lead workers among study variables revealed that CPbB and natural log transformation ZPP(LZPP) were better correlated with other variables and found to be better estimate than PbB and ZPP themselves. The age was correlated with all other variables, but the work duration was not. The correlation analysis of male and female workers among study variables revealed the same results with all lead workers. 5. The slope of simple linear regression of CPbB (independent variable) with ZPP in female workers(3.223)was steeper than in male workers(2.144). That of lead workers with work duration of less than 1 year was steeper than that of lead workers whose work duration was more than 1 year. But there was no slope difference between two groups divided by their work duration of 2 years less and more. The slope of simple linear regression of CPbB lead (independent variable)with ZPP in lead workers whose blood lead were higher than 30㎍/㎗and 40㎍/㎗ were steeper than those whose blood lead were less than 30㎍/㎗ and 40㎍/㎗. 6. The slope of simple linear regression of CPbB (independent variable) with ZPP in lead industries with low mean blood lead were less steeper than those with high mean blood lead. 7. The slope of simple linear regression of CPbB (independent variable) with LZPP in female workers(0.0308was steeper than in male workers(0.0253). That of lead workers with work duration of less than 1 year was steeper than that of lead workers whose work duration was more than 1 year. But where was no slope difference between two groups divided by their work duration of 2 years less and more. While the slope of simple linear regression of CPbB lead (independent variable) with LZPP in lead workers whose blood lead were hogher than 30㎍/㎗ was not steeper than those whose blood lead were less than 30㎍/㎗, there was no slope difference between two groups whose blood lead were less than 40㎍/㎗ and more than 40㎍/㎗. 8. The slope of simple linear regression of CPbB (independent variable) with LZPP in lead industries with low mean blood lead were less steeper than those with high mean blood lead, but the difference was not significant then that of CPbB and ZPP. With above results, it is recommended that the screening criteria value of ZPP should be down to 60-70㎍/㎗ from 100㎍/㎗ for male lead workers and screening criteria of ZPP for female lead workers was all right with current value of 100㎍/㎗. So it is recommended to make different screening criteria of ZPP for male and female workers like the hemoglobin and hematocrit screening criteria. It is also preferable to use CPbB and LZPP rather than uncorrected PbB and ZPP in the evaluation of lead exposure for lead workers.

Al 질화물 강화 복합재료에 관한 연구

한종선,이현규 조선대학교 생산기술연구소 2005 生産技術硏究 Vol.27 No.1

In the present work, dispersion morphology of particulate of Al-5%Ti-10%㎎+ N₂ composite materials prepared by casting has been studied by using optical microscope, SEM and EDAX. An attempt has been Carried out to understand the dispersion behavior and interfiacial reaction of nitride particles (TiN, AIN) in aluminum alloy melt after homogenization treatment. Al and Ti form intermetallic compounds preferably near nitride particles and tend to be distributed uniformly in matrix with the content of nitride dispersoids. Microstructural analysis of as-cast composites shows that most of nitride dispersoids are observed at grain boundary. but a parts of them are distributed inside the grain.

다시마 식이가 흰쥐에서 글리피지드의 체내동태에 미치는 영향

최한곤,장보현,이종달,유봉규,용철순 한국약제학회 2003 Journal of Pharmaceutical Investigation Vol.33 No.2

Drug interactions with food, on occasion, lead to serious nutritional and functional changes in the body as well as alternations of pharmacological effect. It, therefore, should be necessary to take drug interactions with food into consideration for effective and safe therapeutics. Diabetes mellitus is a heterogeneous group of disorders characterized by abnormal glucose homeostasis, resulting in hyperglycemia, and is associated with increase risk of micovascular, macrovascurlar, and neuropathic complications. However, the precise mechanixm of diabetes mellitus remains unclear. Three basic objectives in the care of diabetic patients are maintaining optimal nutrition, avoiding hypo- or hyperglycemia and preventing complications. The purpose of this study was to investigate the effect of Laminaria japonica diet on the absorption, distribution, metabolism and excretion of glipizide which are frequently used in the treatment of diabetes. Diabetic rats induced by streptozotocin were employed in this study. Blood concentrations of oral hypoglycemic agents were measured by HPLC and resultant pharmacokinetic parameters were calculated by RSTRIP. The mechanisms of drug interaction with food were evaluated on the basis of pharmacokinetic parameters such as k_a, t_1/2, C_max, t_max, and AUC. Administration of glipzide in normal rats treated with Laminaria japonica diet showed significant increase in AUC, k_a, t_1/2, t_max and decrease in C_max, compared to those without Laminaria japonica diet. This might result from adsorption of glipizide on components of Laminaria japonica, causing delayed absorption. Administration of glipizide in diabetic rats treated with Laminaria japonica diet showed significant increase in t_1/2 and t_max, and decrease in C_max, compared to those without Laminaria japonica diet. This might also result from adsorption of glipizide on components of Laminaria japonica, causing delayed absorption and flattened blood concentration of glipizide. The oral glucose test showed that Laminaria japonica diet could lower blood glucose level probably through either inhibiting the activity of disaccharidases, intestinal digestive enzymes, or delaying the absorption of glucose. More studies should be followed to fully understand pharmacokinetic changes of glipizide caused by long-term Laminaria japonica diet.

긴장형 두통환자에서의 근막이완술이 뇌혈류 속도에 미치는 영향

서현규,한종만,이동호 대한정형물리치료학회 2002 대한정형도수물리치료학회지 Vol.8 No.2

The aim of study carried out to determine the effects of myofascial release on the cranial arteries velocity from November 11, 2001 to March 29, 2002 the objects were 10 patients who having the tension-type headache at H-hospital This research compared with measure the mean flow velocity middle cerebral artery, posterior cerebral artery, vertebral cerebral artery. Result obtain were as follows; 1. Middle cerebral artery blood velocity between pre treatment and after treatment for 10days experiment was significantly increased 9.76㎝/s(p<0.05)in right, 4.88㎝/s(p<0.05)in left. 2. Posterior cerebral artery blood velocity between pre treatment and after treatment experiment was difference 6.35㎝/s(p<0.01)in right, 5.14㎝/s(p<0.01)in left, between pre treatment and after treatment for 5days experiment was 11.48㎝/s(p<0.01)in right, 10.74㎝/s(p<0.01)in left, between pre treatment and treatment for 10days experiment was 12.92㎝/s(p<0.001)in right, 12.68㎝/s(p<0.001) in left. 3. Vertebral artery blood velocity between pre treatment and post treatment experiment was difference 4.48㎝/s(p<0.05)in right, 6.10㎝/s(p<0.05)in left, between pre treatment and after treatment for 5days experiment was 12.50㎝/s(p<0.001)in right, 14.40㎝/s(p<0.001)in left, between pre treatment and after treatment for 10days experiment was 14.70㎝/s(p<0.001)in right, 13.90㎝/s(p<0.001)in left.

Lactobacillus casei YIT9018로부터 분리ㆍ정제한 Whole Peptidoglycan의 In Vitro 항종양활성

金昌漢,李明燮,高時煥,朴相瑨,朴圭炫,白永振 건국대학교 생명과학연구원 1995 생명과학지 Vol.2 No.-

In vitro antitumor activity of whole peptidoglycan(WPG) purified from Lactobacillus casei YIT9018 was examined by clonogenic assay. WPG had antitumor activity against five human tumor cell lines and three mouse tumor cell lines. Antitumor activity of WPG against human tumor cell lines such as A-427, SKMES-1, SF-188, FARROW and RAJI was observed at 300, 1,000, 600, 800 and 900㎍/ml concentration, respectively. Antitumor activity of WPG against mouse tumor cell lines such as 3LL, S-180 and P388 was observed at 100, 500 and 1,000㎍/ml concentration, respectively.