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재활용 APT를 이용한 WO<sub>3</sub> 제조와 WC-Co 의 용사코팅
정준기,김성진,온진호,문흥수,피재환,하태권,박상엽,Chung, J. K.,Kim, S. J.,On, J. H.,Moon, H. S.,Pee, J. H.,Ha, T. K.,Park, S. Y. 한국소성가공학회 2015 소성가공 : 한국소성가공학회지 Vol.24 No.4
The possibility of chemical precipitation for recycled ammonium paratungstate (APT) was studied. WO<sub>3</sub> particles were synthesized by chemical precipitation method using a 1:2 weight ratio of APT:DI-water. At the 500℃ sintering temperature, the X-ray diffraction results showed that APT completely decomposed to WO<sub>3</sub>. For the granulated powder WC-Co, vacuum heat treatment at proper temperatures increases tap density and flow-ability. Hardness of the WC-Co thermal spray coating layer was measured in the range HV 831~1266. Spray conditions for the best characteristic values were an oxygen flow rate=1500 scfh, a fuel flow rate = 5.25gph and a gun distance = 320mm.
다양한 산소분압에서 소결한 NdBCO 초전도체의 열적 안정성
정준기,김원정,박성창,강성구,임영진,김철진,Chung, J.K.,Kim, W.J.,Park, S.C.,Kang, S.G.,Lim, Y.J.,Kim, C.J. 한국초전도학회 2009 Progress in superconductivity Vol.10 No.2
The $Nd_{1+x}Ba_{2-x}Cu_3O_{7-{\delta}}$(Nd123) superconductor exhibits high performance in high magnetic field and high temperature. We have studied phase stability for Nd123 under reduced oxygen partial pressure and various heat-treatment conditions. The main phase is Nd123 and some samples contain small amounts of Nd422 depending on the temperature and oxygen partial pressure. The decomposition temperature decreases with decreasing oxygen partial pressure from $1052^{\circ}C(P(O_2)$=150 Torr) to about $845^{\circ}C(P(O_2)$=0.1 Torr). The liquidus line was steeper temperature with decreasing oxygen partial pressure. In same condition of oxygen partial pressure, the region of stable Nd123 phase was formed at slightly higher temperature than the region of stable YBCO phase.
$YBa_2CU_3O_{7-\delta}$ coated Conductor 완충층으로의 응용을 위한 $SrTiO_3 $ 박막의 성장 조건
정준기,고락길,송규정,박찬,김철진,Chung, J.K.,Ko, R.K.,Song, K.J.,Park, C.,Kim, C.J. 한국결정학회 2003 韓國結晶學會誌 Vol.14 No.2
YBa₂CU₃O/sub 7-8/(YBCO) coated conductor의 완충층 구조를 개선하기 위하여 2축배향된 Ni-3 wt%W 합금 기판위에 단일 완충층으로 SrTiO₃(STO) 박막을 증착하였다. YBCO와 STO 박막은 펄스레이저 증착법으로 성장시켰다. STO 박막의 표면은 증착온도에 따라 다른 미세조직을 보여 주었고, XRD 분석에서는 STO와 YBCO 박막이 금속기판의 배향성을 가지면서 성장되었음을 알 수 있었다. 액체질소 온도에서 1.2 MA/㎠의 임계전류밀도와 86 K의 임계온도를 가지는 짧은 길이의 coated conductor를 STO 단일완충층을 이용하여 제조하였다. SrTiO₃ (STO) thin fims were deposited on the biaxially textured Ni-3 wt%W alloy substrates to be used as a single buffer layer for YBa₂CU₃O/sub 7-8/(YBCO) coated conductor. Thin films of YBCO and STO were deposited using pulsed laser. The deposition condition for epitaxial growth of STO on the textured metal was identified, and YBCO coated conductor with a single STO buffer layer with critical current density of 1.2 MA㎠ at 77 K under zero magnetic field and critical temperature of 86 K, was fabricated.
휴식 / 부하 심근 Rubidium - 82 양전자단층촬영과 부하 / 휴식 심근 Tc - 99m - MIBI 단일광자단층촬영의 비교
이동수(D . S . Lee),정준기(J . K . Chung),이명철(M . C . Lee),고창순(C . S . Koh),이경한(K . H . Lee),강건욱(K . W . Kang),정재민(J . M . Jeong),곽철은(C . Kwark),서정돈(J . D . Seo) 대한핵의학회 1995 핵의학 분자영상 Vol.29 No.1
N/A We compared stress/rest myocardial Tc-99m-MIBI tomographic image findings with rest/stress rubidium-82 tomographic images. In 23 patients with coronary artery disease (12 of them received bypass grafts before) and 6 normal subjects, rest rubidium PET study was performed, rubidium-82 and Tc-99m-MrBI were injected simultaneously to each patient after dipyridamole stress for rubidium PET and MIBI SPECT; and rest MIBI SPECT was performed 4 hours thereafter. We scored segmental decrease of rubidium, or MIBI uptakes into 5 grades for 29 segments from 3 short-axis, vertical and horizontal slices. Scores were summed for each major arterial territory. When more score than two grade-2's or one grade-3 was considered as the cue for significant stenosis for major arterial territories, 67% of 46 stenosed arteries were found with MIBI studies and 78% of them by rubidium studies. Fourteen among 28 grafted arterial territories of 12 post-CABG patients were found normal with both rubidium and MIBI. Segmental scores were concordant between rubidium and MIBI in 72% of 709-stress segments and in 80% of 825 rest segments. Stress rubidium segmental scores were less than stress MIBI scores in 9%, so were rest rubidium scores. Stress rubidium scores were more than stress MIBI scores in 20% of segments, and rest rubidium segmental scores were more than rest MIBI scores in 11%. Rank correlations (Spearman's rho's more than 0.7(stress) and 0.5(rest), slopes (MIBI/rubidium) around 0.7(stress) and 0.9(rest) suggested deeper and wider defects in stress with rubidium. Slope over 1 (MIBI/rubidium) with LAD segemental scores at rest and 7 territories which had much larger score with MIBI revealed exaggeration of rest defects with rest MIBI in same-day stress/rest study. Difference scores (stress-rest for each territory) suggesting ischemia were larger with rubidium (slope of MIBI/rubidium around 0.45). As has been implied by animal or separate-day- human studies, these segmental analyses with simultaneous examination in patients told that rubi
일부 농촌지역 주민에서 혈청 CA19-9 및 CA125 농도에 영향을 미치는 인자에 관한 연구
이명철(M. C. Lee),이수근(S. K. Lee),유근영(K. Y. Yoo),박수경(S. K. Park),강대희(D. H. Kang),김진규(J. Q. Kim),정준기(J. K. Chung) 대한핵의학회 1998 핵의학 분자영상 Vol.32 No.1
N/A This study examines the levels of carbohydrate antigen 19-9(CA19-9) and cancer antigen 125(CA125) in serum and its related factors in healthy Korean population. Although CA19-9 and CA125 have been widely used tumor markers for gastroenteric cancers and ovarian cancer in Western countries, there are no information available on the serum levels of CA19-9 and CA125 in healthy population and the factors affecting the levels of these tumor markers in Korea. A cross-sectional study was performed to measure CA19-9 and CA125 among 76 healthy males and 95 healthy females in Korea. CA19-9 and CA125 were quantitated using solid-phase radioimmunoassay kits. Informations on the factors which might be related to the levels of these markers were collected by questionnaire(e.g., smoking, alcohol consumption, menstruation, oral pill use, breast-feeding history, etc.). There was no statistically significant difference in the mean of CA19-9 concentration between men(l0.4 u/ml) and women(l0.l u/ml), Whereas the mean of CA125 levels(11.2 u/ml) was higher in omen than that(2.5 u/ml) in men. Although there was a statistically significant association between CA19-9 and average number of cigarette consumed per day(r=0.59, p=0.026) and total number of cigarettes consumed in women(r=0.74, p=0.003), the significance disappeared by multiple regression analysis after adjusting age and body mass index. Later age of menopause(p=0.035) and longer duration f breast-feeding(p=0.050) were significant predictors for CA125 levels in women by multiple regression analysis after adjusting age and body mass index. In conclusion, CA19-9 can be used as a stable tumor marker in clinical practices, however, menstruation and breast-feeding should be considered when CA125 is used in women.
신동맥분지협착에 의한 신혈관성고혈압 예에서 캅토프릴투여후 99mTc - DMSA 신 스캔
양원석(W . S . Yang),김연수(Y . S . Kim),엄재호(J . H . Earm),김상은(S . E . Kim),이동수(D . S . Lee),한진석(J . S . Han),정준기(J . K . Chung),김성권(S . K . Kim),이명철(M . C . Lee),이정상(J . S . Lee),고창순(C . S . Koh) 대한핵의학회 1990 핵의학 분자영상 Vol.24 No.2
N/A Radionuclide renal scintigraphies were performed in a 24-year-old man with right renal artery branch stenosis. Captopril enhanced Tc-99m-DTPA renal scintigraphy revealed no abnormal finding in the right kidney But, Tc-99m-DMSA renal scintigraphy showed regional cortical photon deficient area corresponding to the area supplied by the stenotic branch artery. The defect size increased in captopril enhanced Tc-99m-DMSA renal scintigrphy and nearly disappeared after successful transluminal renal angioplasty. This case suggests that the captopril enhanced Tc-99m- DMSA renal scintigraphy may be a useful method in the evaluation of renovascular hypertension, especially due to branch renal srtery stenosis.