고상반응법으로 합성한 Sm3+ 을 첨가한 calcium pyrophosphate 분말 특성 연구

홍경수,양임정 한국물리학회 2022 새물리 Vol.72 No.2

Samarium-doped calcium pyrophosphate (Ca2P2O7:Sm3+) powder is synthesized using the solid-state reaction method. X-ray diffraction patterns and Fourier transform infrared spectra reveal that Ca2P2O7:Sm3+ forms in different phases depending on sintering temperature. This study examines the radiative energy relaxation of Sm3+ ions in Ca2P2O7 by taking absorption and emission spectra at room temperature. An emission wavelength of almost 600 nm with near ultraviolet excitation is observed as a result of the transition of 4G5/2 ! 6H7/2. Phase transition is induced, as the sintering temperature varies from 900 oC to 1200 oC. Emission intensity is measured as the doping concentration of Sm3+ increases up to 0.100 mol at each sintering temperature. The emission intensity of -Ca2P2O7 prepared at 1200 oC increases as Sm3+ concentration increases but is quenched above a certain concentration. Therefore, an optimized concentration of Sm3+ requires highly efficient -Ca2P2O7. This work reports that Ca2P2O7:Sm3+ powder is a good candidate for a red-orange emitting phosphor.

합성 조건에 따른 SrTiO3:Sm3+ 분말의 광 특성 연구

홍경수,양호순 한국물리학회 2013 새물리 Vol.63 No.1

Samarium-doped strontium titanate (SrTiO3:Sm3+) is synthesized by using the solid-state reaction method. The structure and the surface morphology of the synthesized powder are characterized, and the optical properties are studied by taking absorption, excitation, and emission spectra at room temperature. A red-orange luminescence corresponding to the 4G5/2 ! 6H7/2 transition of Sm3+ is observed. For operation with near ultraviolet excitation, SrTiO3:Sm3+ is found to be a red-orange emitting powder. The luminescence intensity is shown to vary with the doping rate of Sm3+ ions and the sintering time. 넓은 에너지 띠 간격을 갖는 perovskite 산화물인 SrTiO$_3$에Sm$^{3+}$이 첨가된 분말의 광특성을 연구하였다. 적색 형광을 내며분광학적 특성이 있어 중요한 활성체인 Sm$^{3+}$을 첨가한 SrTiO$_3$분말을 고상반응법으로 합성하였다. 합성된 시료의 물성과 표면 상태를조사하였으며, 분말 합성에 사용한 소결 시간 및 첨가된 Sm$^{3+}$이온의 농도에 따라 흡수, 여기 및 발광 스펙트럼을 측정하여 합성된분말이 갖는 광학적 성질을 알아보았다. 근자외선 여기에 의한 Sm$^{3+}$이온의 $^4$G$_{5/2}$ $\rightarrow$ $^6$H$_{7/2}$ 전이에 대응하는적-황색 형광이 관측되었다. SrTiO$_3$ 분말 합성에서 소결 시간과 발광세기와의 관계 및 Sm$^{3+}$ 이온의 농도가 발광의 세기에 미치는 영향을확인하여 광소재로 응용할 수 있음을 보였다.

Temperature-Dependent Structures and Chemical Bonding States of the Calcium Chlorapatite Powders Doped with Rare-Earth-Ions

홍경수,양호순 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.70 No.4

Calcium chlorapatite powders doped with rare-earth-ions are synthesized by using the solid-state reaction method and sintering at 1,100 C and 1,300 C, respectively. This study focuses on the crystal structures and the chemical bonding states of calcium chlorapatite powders for different sintering temperatures, doping elements, and doping concentrations. The characterized physical properties show that the apatite powders exhibit two phases based on the sintering temperatures: the powders sintered at temperatures below 1,100 C have a hexagonal structure while those sintered at 1,300 C have a monoclinic structure. That is, the apatite compounds sintered at higher temperatures show a structure with a lower space symmetry. The chemical bonding states of the synthesized powders remain unchanged regardless of the amount of doped rare-earths and the sintering temperature.

대마젤란은하 식쌍성의 측광 및 분광 관측

홍경수,강영운 한국천문학회 2010 天文學會報 Vol.35 No.1

Optical Properties and Chemical Bonding States with Annealing Conditions of ZnO Nanofibers Prepared by Using the Electrospinning Method

홍경수,Eun Sick Pak,배종성,정의덕,진종성,하명규,김종필 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.9

We have prepared ZnO nanofibers by using the electrospinning method and have analyzed the variations in their structure, optical properties, and chemical bonding states with the annealing temperature and the annealing conditions. After annealing at 500 ℃, the average diameter and the average grain size are determined to be approximately 170 nm and 50 nm, respectively. The ZnO nanofibers have a clearly visible dislocation-free crystal structure. The 2<i>p</i> level of Zn caused Zn-O bonds and the O 1<i>s</i> core level caused physisorbed O₂. When the nanofibers are annealed at 700 ℃, both ions exhibit shifts of the binding energies compared with those annealed at 500 ℃. The observed band in the visible region shows a strong temperature dependence and a red-shift with the oxygen flow in annealing process, which is related to oxygen vacancies.

힐링캠프, 사운드적 서사의 등장과 함의

홍경수 한국방송학회 2012 한국방송학회 학술대회 논문집 Vol.2012 No.11

외과적 치료를 요하는 신생아질환

홍경수,김순경 한국의학사 1982 診斷과治療 Vol.2 No.5

Electron-Phonon Interactions in Insulating Nanoparticles Eu2O3

홍경수,양호순 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.47 No.1

The temperature and particle size dependencies of the holewidths burned in the 7F0 ! 5D0 transition of Eu3+ ions in Eu2O3 are calculated and compared with experiment. The temperature behavior T7 for the bulk is observed to be strongly weakened to T3 for the nanoparticles. A calculation is performed with a two-phonon Raman-scattering mechanism involving the discrete phonon modes of a homogeneous nanoparticle with stress-free boundary conditions. The experimental results are successfully described assuming that the phonon modes broaden with frequency as !2.

기억력과 정신질환

홍경수,연병길,Hong, Kyung Sue,Yeon, Byeong Kil 대한생물정신의학회 1997 생물정신의학 Vol.4 No.1

Disturbances in memory are the most common problem in patients with an organic mental syndrome. Other patients with significant psychiatric disorders also often have difficulty with memory. So it is very important in the clinical practice of psychiatry to understand the biological and neurocognitive mechanisms of memory proessing, and to develop the assessment tools with which memory function can be evaluated reliably and validly. Moreover, memory researches provide an important viewpoint from which we can understand the pathophysiological mechanisms of major neuropsychiatric illnesses. This article focuses on our understanding of memory functions in clinical and neurobiological aspects. The relevant material will be presented in four parts : 1) terminologies needed in defining major stages of various types of memory processing : 2) neurochemical and neuroanatomical basis of memory processing : 3) brief bed-side screening tests and more comprehensive neuropsychological tests for the evaluation of memory function : 4) the characteristics of memory dysfunction in several major psychiatric illnesses.

알코올의존과 도파민 D2 수용체 TaqI A1 대립유전자의 관련

홍경수,김종원,김길숙,오동열,김승태 대한신경정신의학회 1997 신경정신의학 Vol.36 No.6

알코올의존의 유전적 원인론을 추구하는 일련의 연구결과 중 전세계적으로 논란이 되고 있는 도파민 D2 수용체 유전자 TaqI A1 대립유전자와 알코올의존의 유전적 관련(genetic association) 여부를 단일인종인 우리나라 인구를 대상으로 검증해 보고자 본 연구를 시행하였다. 환자군은 DSM-IV에 근거하여 알코올의존으로 진단내려진 남자 입원환자 59명이며, 대조군은 알코올의 존이 배제되고 2차친척 내에 알코올의존 환자가 없는 74명의 정상인이었다. 알코올의존의 심한정도는 미국 National Council on Alcoholism(NCA)의 주요진단기준 제1단계 10항목 중 환자가 만족시키는 항목의 수 로 평가하였다. 유전자 분석은, 각 개인별로 분리된 genomic DNA를 중합효소연쇄반응시켜 그 산물을 TaqI 제한효소로 소화시킨 후 전기영동하여 나타나는 band를 확인하여 대립유전자 종류를 파악하였다. A1 대립유전자의 빈도는 환자군에서 0.45, 대조군에서 0.34로 환자군에서 더 높았으나 통계적으로 유의 한 차이는 보이지 않았다(χ2=2.98, df=1, p=0.08). 환자군을 NCA 주요 진단기준 제1단계 10항목 중 5 항목 이상을 만족시키는 중증군과 그 이하를 만족시키는 경증군으로 나누어 분석하였을 때, 중증군 47명에 서는 A1 대립유전자 빈도가 0.48로 대조군에 비해유의하게 높았으며(χ2=4.21, df=1, p=0.04), 경증 환 자군에서는 0.33으로 대조군과 비슷한 수준이었다(χ2=0.04, df=1, p=0.85). 유전자형별로 중증군에 속하 는 환자의 비율은 A1A1군에서 92%, A1A2군에서 77%, A2A2군에서 73%로 A1 대립유전자를 많이 가지 고 있을수록 중증군에 속하는 환자 비율이 증가하였다(χ2=11.78, df=2, p=0.003).이러한 결과는 원인론적으로 비동질적인 알코올의존 환자군 중 중증을 보이는 특정 소집단에서, 도파민 D2 수용체 유전자의 TaqI A1 대립유전자 혹은 TaqI A 분절길이다형성과 연관된 인접 유전자가 병의 민감 성(susceptibility)을 증가시키는 복합유전자(polygenic) 모델의 원인 유전자 중 하나가 될 수 있음을 의미 한다. Objectives:The existence of an allelic association between alcohol dependence and the TaqI A1 allele at the D2 dopamine receptor(DRD2) locus has been proposed but still remains controversial. The purpose of the present study was to examine the allelic association of alcohol dependence and the TaqI A polymorphism of DRD2 gene in ethnically homogenous Korean population. Methods:The subjects were 59 male patients diagnosed as alcohol dependence(DSM-IV) and the controls were 74 nonalcoholic male volunteers screened for alcohol problems in their 2nd degree relatives. The severity of alcohol dependence was estimated by the number of items of diagnostic level 1 of the Major Criteria for the Diagnosis of Alcoholism by National Council on Alcoholism (NCA). Genotyping was done by polymerase chain reaction(PCR) and the electrophoresis of the PCR products digested by TaqI. Results:The frequency of the A1 allele in alcoholic group(0.45) was higher than that in control group(0.34) but there was no significant difference between them(χ2=2.98, p=0.08). The frequency of A1 allele in 47 more severe alcoholic patients who met five or more items of Major Criteria for the Diagnosis of Alcoholism by NCA was 0.48 and it was significantly higher compared with that in control group(χ2=4.21, p=0.04). In less severe alcoholic patients, the frequency of A1 allele(0.33) was similar to that in control group(χ2=0.04, p=0.85). The proportions of subjects with more severe alcoholism in the patients with A1A1, A1A2, and A2A2 were 92%, 77%, and 73%, respectively. Conclusion:An allelic association of more severe alcoholic subgroup and the TaqI A1 allele of D2 dopamine receptor gene was supported in Korean population. It is suggested that the TaqI A1 allele is related to or has a linkage disequilibrium with a genetic factor which may be one of the risk factors for susceptibility to more severe alcoholic subgroup in multifactorial-threshold etiologic model.