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$Eu_{1-x}Sr_xCoO_{3-y}$계의 비화학량론과 자기적 특성
류광현,민지영,여철현,Ryu, Kwang Hyun,Min, Ji Young,Yo, Chul Hyun 대한화학회 1995 대한화학회지 Vol.39 No.7
$Eu_{1-x}Sr_xCoO_{3-y}$계에 대한 각 조성의 시료를 1150$^{\circ}C$ 대기압하에서 일정량의 반응혼합물을 가열하여 합성하였고 X-선 회절분석을 통하여 고용체가 합성되었음을 확인하였다. X-선 회절분석 결과 x=0.00과 0.25 조성의 화합물은 뒤틀린 orthoferrite형의 사방정계이고 x=0.50과 0.75는 단순 입방정계이고 x=1.00은 brownmillerite형의 사방정계이다. $Co^{4+}$ 이온의 양(${\tau}$값)은 x=0.50에서 최대가 되고 산소공위는 x값이 증가함에 따라 증가한다. 합성된 화합물에 대한$Co^{4+}$ 이온의 몰비와 산소 비화학량을 결정함으로서 합성된 각 조성의 화합물에 대한 비화학량론적 화학식을 결정하였다. 페롭스카이트 구조의 팔면체자리에 존재하는 $Co^{3+}$ 이온은 온도가 증가함에 따라 낮은 스핀상태에서 높은 스핀상태로의 전이가 일어난다. 이에 따라 자기측정 결과 각 시료는 온도가 상승함에 따라 유효자기모멘트가 증가한다. $EuCoO_{3.00}$의 경우 팔면체자리에 존재하는 $Co^{3+}$ 이온은 산소이온을 매개로 하여 이웃한 $Co^{3+}$ 이온과 반강자성 간접상호작용을 한다. ${\tau}$값이 증가하면 $Co^{3+}-O^2-Co^{4+}$의 강자성 상호작용에 의해 {\theta}_p$의 절대값이 감소하고, 결국 x=0.50에서는 양의 {\theta}_p$값을 갖는다. A series of samples in the $Eu_{1-x}Sr_xCoO_{3-y}$ system has been prepared by heating the proper amount of reactant mixture to 1150$^{\circ}C$ under an ambient atmosphere, and the solid solutions are identified by X-ray powder diffraction analysis. The crystal system of samples for the compositions of x=0.00 and 0.25 are found to be orthorhombic whose local symmetry is similiar to the distorted octahedra with orthoferrite type one, whereas those of x=0.50 and 0.75 to be the cubic system, and that of x=1.00 to the orthorhombic similiar to be the brownmillerite type. The amount of $Co^{4+}$ ion (${\tau}$ value) is maximized at the composition of x=0.50, and the oxygen vacancies increase with the x value. The nonstoichiometric chemical formula of each compound could be determined from the mole ratio of $Co^{4+}$ ion and oxygen vacancies. The $Co^{3+}$ ion located in octahedral site has spin transition from low spin to high spin states with increasing temperature. Therefore, the effective magnetic moment of each samples obtained from the magnetic measurement is increased with the increasing temperature. The $EuCoO_{3.00}$ has strong antiferromagnetic interaction between the neighboring $Co^{3+}$ ions through the intermediate oxygen ions. With the increasing ${\tau}$ value, the absolute {\theta}_p$ value is decreased by the ferromagnetic interaction of $Co^{3+}-O^2-Co^{4+}$ and thus the {\theta}_p$ has positive value at x=0.50.
류광현,오응주,김규홍,여철현,Ryu, Kwang Hyun,Oh, Eung Ju,Kim, Keu Hong,Yo, Chul Hyun 대한화학회 1995 대한화학회지 Vol.39 No.3
비화학량론적 산화물$WO_{3-x}$의 비화학량 x값과 전기전도도를 350~700$^{\circ}C$의 온도 범위와 $2{\times}10_{-1}\;to\;1{\times}10_{-5}$ atm의 산소분압 범위에서 측정하였다. 비화학량론적 조성식에서 x의 생성엔탈피 ${\Delta}H^{\circ}_f$가 양의 값을 가지는 것으로 보아 결함생성은 흡열 과정이고, 결함생성의 산소분압 의존성인 1/n값은 -1/5.7~-1/6.1로 변하였다. 전기전도도의 활성화에너지는 각 산소분압에 따라 0.24~0.29 eV이었고, 전기전도도의 산소분압 의존성인 1/n은 -1/4.3~-1/7.6의 값을 나타내었다. 이로부터 n형 반도체로써 산화텅스텐의 결함모델은 낮은 온도에서는 1가로 하전된 산소공위가 우세하지만 온도가 상승함에 따라 2가로 하전된 산소공위가 우세해진다. The x values and electrical conductivities of the nonstoichiometric compounds $WO_{3-x}$ have been measured in the temperature range from 350 to 700$^{\circ}C$ under oxygen partial pressure of $2{\times}10_{-1}\;to\;1{\times}10_{-5}$ atm. The enthalpy of the defect formation shows an endothermic process, and the oxygen pressure dependence of the defect formation or 1/n varies from -1/5.2 to -1/5.9. The activation energy and 1/n value for the electrical conductivity are 0.24~0.29 eV and -1/4.3~-1/7.6, respectively. The Tungsten Oxide as a n-type semiconductor has predominently defect model of singly charged oxygen vacancy at low temperature, and of doubly charged oxygen vacancy at high temperature.
Helicobacter pylori 감염 진단에 항 IgG 항체를 이용한 혈청검사 및 전혈검사 방법들의 정확성에 대한 비교 연구
류광현 ( Kwang Hyun Ryu ),김재준 ( Jae Jun Kim ),심상군 ( Sang Goon Shim ),최문석 ( Moon Seok Choi ),김창섭 ( Chang Seop Kim ),김영호 ( Young Ho Kim ),손희정 ( Hee Jung Son ),이규택 ( Kyu Taek Lee ),이종균 ( Jong Kyun Lee ),이준혁 대한소화기학회 1999 대한소화기학회지 Vol.34 No.4
Background/Aims: In Western countries, serological tests for the diagnosis of Helicobacter pylori (H. pylori) infection showed high sensitivity and specificity (more than 90% accuracy). This study was carried out to compare the accuracy of two rapid whole blood (WB) tests and three serological tests for detection of H. pylori in Korea. Methods: Fifty-two patients with functional dyspepsia underwent endoscopic evaluation for detection of H. pylori. The sensitivity, specificity, positive and negative predictive value, and accuracy of the five diagnostic tests were assessed on the basis of gold standard: The gold standard positives were defined as the case with at least one positive result of the two tests (histology and culture). Results: The prevalence of H. pylori infection was 51.9% (27/52). In most of diagnostic tests performed, the differences in sensitivity, specificity and accuracy were not statistically significant. However, the sensitivity of radim IgG test was significantly higher than that of Abacus WB test (88.5% vs 53.8%, p<0.05). The specificity of Abacus WB test was superior to that of GAP test (92.0% vs 66.7%, p<0.05). Conclusions: Five serum and rapid WB diagnostic tests showed the lower diagnostic accuracy in detecting H. pylori infection in Korea (less than 81.9%) than the results reported in Western countries. (Kor J Gastroenterol 1999;34:455 - 462)
류광현 ( Kwang-hyun Ryu ),김현중 ( Hyun-joong Kim ) 한국공업화학회 2019 공업화학전망 Vol.22 No.6
미세플라스틱은 폐플라스틱의 처리 과정과 일상생활 속에서 불가피하게 발생하며, 생태계에 악영향을 주고, 최종적으로 인체 내로 유입되어 들어온다. 자연환경 속 미세플라스틱의 양은 지속적으로 증가할 것으로 예측되며, 이에 대한 해결방안으로 생분해성 고분자를 이용한 난분해성 플라스틱의 대체제에 관심이 증대되고 있다. 그러나 생분해성 고분자(starch, PLA, PBAT, PBS, PHAs, PCL)는 기존 범용 플라스틱 대비 낮은 물성, 높은 생산비용이라는 단점이 있으며, 그 문제를 개선하기 위한 연구들이 이루어져 왔다. 또한 미세플라스틱의 발생을 효율적으로 저감할 수 있는 대책으로서 3R (reduce, recycle, reuse) 운동이 정부의 정책과 기업들의 제품개발로 활성화되고 있다. 이에 따라 본 총설에서는 미세플라스틱의 현황과 문제해결을 위한 대체제의 연구 동향 및 저감대책들에 대해 살펴보고자 한다.
류광현 ( Kwang Hyun Ryu ),이금희 ( Kum Hi Lee ),송운흥 ( Woon Heung Song ) 대한임상병리사협회 1999 임상수혈검사학회 발표자료집 Vol.5 No.1
Umbilical cord blood(UCB) is a rich source of hematopoietic stem cells that can be used to reconstitute hematopoiesis after intensive myeloablative therapy. The first successful transplantation for a patient with Fanconi`s anemia using HLA-identical sibling cells performed in 1988. The clinical advantages of UCB include that easy obtainable source from discarded umbilical cord and placenta, higher concentration of hematopoietic stem cells and lower reinjection rate due to immature T cells in transplantation. In 1997,umbilical cord blood bank for cryopreservation of UCB was established in samsung medical center, so we introduce the protocols for UCB collection, red cell depletion, cryopreservation and the results would be very helperful for future UCB storage and transplantation.
원저(原著) : Aliquot bag을 이용한 소아용 적혈구 제제의 사용 경험
류광현 ( Kwang Hyun Ryu ),송운흥 ( Woon Heung Song ) 대한임상병리사협회 1997 임상수혈검사학회 발표자료집 Vol.4 No.1
It is important to supply the small volume of blood for pediatric and neonatal transfusion. Anemia in newborns may result from red blood cell loss due to the multiple blood sampling for laboratory test or from pathological bleeding. Because small volume requirements of transfusion to newborns may give rise to a large amount of wastage and multiple donor blood exposure that blood bank providing blood for neonates have developed preparing 50~140 ml pediatric units of red blood cells. The authors experienced the use of aliquot bags for pediatric units of red blood cells in the Blood Bank, Samsung Medical Center since October 1994.
원저(原著) : 공혈자 선별을 위한 HCV-SPOT 검사의 평가
류광현 ( Kwang Hyun Ryu ),송운흥 ( Woon Heung Song ) 대한임상병리사협회 1996 임상수혈검사학회 발표자료집 Vol.3 No.1
Hepatitis C is a major problem of post-transfusion hepatitis. The best measure for preventing hepatitis C infection after transfusion is blood donor screening. There are many methods for detecting hepatitis C virus antibodies. EIA is one of the widely used, sensitive method. However it needs time consuming, but HCV-SPOT is a simple, rapid test for the detection of anti-HCV. We evaluated comparative results in detection of HCV antibodies by using a rapid HCV test and EIA. The study shows following results. The false positive was 8.3 %(3.36), false negative was 0 %(0.58), sensitivity was 100 %(54.54), specificity was 92.5 %(37.40), accuracy was 96.8 %(91.94). This study relatively shows high efficiency of SPOT test. But this rapid test must use emergency state.