The Relation Between Local Hysteresis Losses and Remanent Magnetic Fields in HTSC Films

Muyong Kim,Heeyeon Park,Chan Kim,Sang-Kook Park,Ri, H.-C Institute of Electrical and Electronics Engineers 2017 IEEE transactions on applied superconductivity Vol.27 No.4

<P>Various critical state models have been developed to understand the hysteresis loss mechanism of high-temperature superconducting (HTSC) films. The analytic relation between the hysteresis loss and the remanent field was obtained based on Bean's critical state model for thin films in the full-penetration case. Furthermore, numerical calculation of local hysteresis loops was carried out by Kim's critical state model. In this paper, we investigated local hysteresis losses for a GdBCO coated conductor by using low-temperature scanning Hall probe microscopy and reproduced the experimental results by applying the critical state model. Because of the demagnetizing effect in thin films, analysis of local hysteresis losses can be useful approach to understand of total hysteresis losses.</P>

SrCI_2:Eu^2+ 형광체의 광발광 및 광자극발광 특성

도시홍,서효진,김영국,김도성,김성환,김찬중,이병화,김완,강희동 한국센서학회 2002 센서학회지 Vol.11 No.6

고상반응법으로 SrCl_2:Eu^2+ 형광체를 제작하고, 제작한 형광체의 광자극발광과 광발광 특성을 조사하였다. SrCl_2:Eu^2+ 형광체와 광발광 및 광자극발광은 Eu^2+ 의 5d->4f 천이에 기인되었으며, 355 nm의 광으로 여기시켰을 때 광자극발광과 광발광 스펙트럼의 파장범위는 모두 380~440nm이었고, 피이크 파장은 407nm이었다. SrCl_2:Eu^2+형광체의 선량의존성은 2.5 mGy~200mGy영역에서 우수한 선형성을 나타내었으며, 상온에서 광자극발광의 fading은 20분에 60%이었다. SrCl_2:Eu^2+ phosphors were prepared by the solid phase reaction method, and their photostimulated luminescence(PSL) and photoluminescence(PL) characteristics were investigated. The PSL and PL peak of the SrCl_2:Eu^2+ phosphors are due to the 5d->4f transition of Eu^2+ ions in phosphors. The PSL and PL spectrum obtained by the 355 nm exitation was observed in 380~440 nm region with the peak at 407 nm. The dose response of the PSL phosphors were linear within 2.5 mGy ~ 200 mGy of 100kV X-ray. The fading of the phosphors at room temperature was approximately 60% after 20 min.

BaFBr:Eu^2+ 형광체의 열발광 및 광자극발광 특성

도시홍,서효진,강갑중,김영국,김도성,김성환,김찬중,이병화,김완,강희동 한국센서학회 2002 센서학회지 Vol.11 No.5

BaFBr:Eu^2+ 형광체를 제조하고, 이 형광체의 열발광 특성과 광자극발광 특성을 조사하였다. 이 형광체의 열발광 g1ow 피이크 온도는 352K와 448K였으며, 주 피이크(352K)에 관여하는 트랩의 활성화에너지는 약 0.96eV이었다. 또한 이 형광체의 광자극발광 스펙트럼의 파장범위는 350~450nm 사이였으며, 광자극발광에 기여하는 트랩의 활성화에너지는 약 0.98eV이었다. 열발광트랩과 광자극발광 트랩의 활성화에너지는 실험오차 내에서 일치하였다. BaFBr:Eu^2+ phosphors were prepared, and the thermoluminescence(TL) and photostimulatedluminescence(PSL) of the prepared phosphors were measured. Two glow peaks around 352 and 448 K are observed for x-ray irradiated BaFBr:Eu^2+ phosphors, and the activation energy of the main glow peak(352 K) was about 0.96 eV. The spectral range of the PSL was 350 ~450 nm, and the activation energy of the trap giving rise to PSL was about 0.98 eV. The activation energy of the traps giving rise to TL is agreed to those giving rise to PSL within experimental error.

화성암 중의 Selenium 정량

김찬국,山谷和久,吉田稔 동아대학교 공과대학 부설 한국자원개발연구소 1994 硏究報告 Vol.18 No.1

A study was performed for determination of trace of selenium in igneous rocks, by means of hydride generation methods with preconcentration. The procedure follows : At first, transfer 10㎖ of sample solution and 10㎖ of hydrochloric acid to a reaction vessel and inject 3% sodium tetrahydroborate solution with a flow rate of 4㎖/min for 45 seconds. Hydrogen selenide is generated from the sample solution by passing nitrogen gas at a flow rate of 125-150㎖/min for 3 minutes. Then the nitrogen gas bearing the hydrogen selenide is introduced in an absorbing solution(3M HC10₄ 5㎖十0.02M KMnO₄ 0.20㎖+0.05M Na₂C₂O₄0.15㎖) through a sintered glass filter At the second step, concentrated hydrochloric acid of 5㎖ with 1M potassium bromide solution of 0.20㎖ are added to the sample solution and then the solution was heated up to 95℃ for 45minutes for reduction of Se(Ⅵ) to Se(Ⅳ). The selenium contents of the concentrated sample solution were determined by A. A. S. The proposed method was applied to the determination of Se in igneous rock samples and satisfactory results were obtained.

극미량 Se의 정량에 관한 연구

김찬국 동아대학교 공과대학 부설 한국자원개발연구소 1995 硏究報告 Vol.19 No.2

A study was performed for determination of the trace amount of Selenium by A.A.S. with hydride generation method. The procedure is as follows ; transfer 40㎖ of sample solution and 20㎖ of HCl to a reaction vessel and inject 3% NaBH₄solution with a flow rate of 3㎖/min for 45 seconds. H₂Se gas is generated from the sample solution by passing nitrogen gas is introduced into an absorbing solution through a sintered glass filter. Then transfer it into 100㎖ beaker and add 3㎖ of HNO₃solution. Heat on a hot plate at 150℃ to evaporate slowly to about 2∼3㎖. Then add 10㎖ of 6M-HCl to the solution and heat to about 125℃ for reduction of Se(Ⅵ) to Se(Ⅳ). The selenium contents of the concentrated samples were determined by A.A.S. with hydride generation. This method is excellent for the determination of Selenium in view of conveniency, rapidity, high sensitivity and good reproducibility.

Myelodysplastic Syndrome의 혈액학적 소견

박찬정,조한익,김상인,이재훈,김병국,김노경 大韓血液學會 1984 大韓血液學會誌 Vol.19 No.2

고요산혈증의 위험인자 : 아산시 지역 주민을 대상으로

김용배,장원기,황보영,김화성,안규동,이병국,이용진,이종은,이준숙,이찬구,이한정,이성수 순천향대학교 2006 Journal of Soonchunhyang Medical Science Vol.12 No.1

Objective : Serum uric acid has now been identified as a marker for a number of metabolic and hemodynamic abnormalities. The aim of this study is to evaluate risk factors which influence hyperuricemia in the citizens of Asan. Method : The study design was cross-sectional and research subjects were 1086 citizens of Asan. General characteristics, cigarette smoking, alcohol consumption, and past history were obtained by interview using a structural questionnaire. Also, we measured height, weight and blood pressure, and serum uric acid of the subjects. Results : The mean serum uric acid level was 5.27 ㎎/㎗ in men and 4.01 ㎎/㎗, in women, In the multiple logistic regression analysis, statically significant risk factors of hyperuhcemia were gender, body mass index, blood lead concentration, and serum creatinine. Conclusion : Our results suggest that gender, body mass index, blood lead concentration, and serum creatinine might be the most important risk factors of hyperurcemia. Education program as well as routine check-up for serum uric acid was highly recommended for the effective prevention of hyperuricemia.

Mg-Zn-Ca합금의 부식저항 개선에 관한 연구

김유영,허남수,안국찬,김인환 진주산업대학교 1999 산업과학기술연구소보 Vol.- No.6

In order to corrosion resistance of Mg-Zn alloy the 3rd element, Ca(0 to 1.5wt.%)element was added. Alloy ingot was made under vacuum atmosphere of 4×10^-4 Torr in the quartz tube coated by BN. The addition of Ca elements to Mg-Zn alloys were obtained grain size refining and age hardening. Corrosion characteristics were investigated by potentiostatic corrosion test in 5wt.%NaCl solution.(ΔE=100mV) The corrosion current density of Mg and Mg-6wt.% Zn alloy was reduced by addition of 0.5wt.% Ca.

설록차에 의한 Cadmium, Lead 및 Copper 이온의 흡착 특성

김찬국,강헌찬 동아대학교 환경문제연구소 1998 硏究報告 Vol.21 No.1

The adsorption characteristics of heavy metal ion(Cu^(2+), Cd^(2+), Pb^(2+)) on the Korean sullok tea has been studied. The tea powder was treated with formalin in a dilute sulfuric acid. A l00ml solution containing heavy metal ions was mixed with 0.5g of the tea under shaking by jar tester for 60 minutes. The solution was the filtered through and the concentration of metal ions in the filtered were determined with atomic adsorption spectrometer. These results suggest that the metal ions have unexpectedly strong affinity for the powderly sullok tea. Heavy metals on sullok tea were easily eluted by using 0.1-M hydrochloric acid solution. The tea can be reused over several times on the adsorbent, after the metal are washed away with hydrochloric acid.

횡방향 충격을 받는 적층복합판의 층간전단응력 해석

안국찬,박승범,김봉환 한국산업안전학회 2002 한국안전학회지 Vol.17 No.4

This paper demonstrates the analyses of the interlaminar shear stress of laminated composite plates subjected to transversely impact. For this purpose, a plate finite element model based on the higher order shear deformation plate theory in conjunction with static contact laws is developed. Test materials were CFRP with cross-ply laminate [0_4/Θ_4]_s, [90_4/Θ_4]_s stacking sequences and angle-ply laminate [Θ_4/-Θ_4]_s, [Θ_4/-Θ_4]_s stacking sequences with 2^t×40^w×100^l(㎜) dimension. As a result, stacking sequence and fiber orientation were found to have a significant effect on the interlaminar stress in composite laminates.