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        검색결과 15

        2.
        2021.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A progressive muscle atrophy is strongly associated with aging, resulting in lower quality of life in elderly individuals. This study was conducted to determine relative hemoglobin (Hb) concentrations in the rabbit model of the sciatic nerve transection injury using non-invasive diffuse optical spectroscopy (DOS). From the 2nd week to the end of the experiment after sciatic nerve injury, a total muscle mass in nerve injured-group (NI group) significantly reduced compared with that in the normal group (p<0.001). During the capillary occlusion after nerve injury, the deoxy-hemoglobin (Hb-R) concentration in NI group significantly increased compared to that in the normal group at the 2nd and 3rd week after sciatic nerve injury (p<0.05). During the capillary release after nerve injury, the oxy-hemoglobin (Hb-O2) concentration in NI group significantly decreased at the 1st and 3rd week, and Hb-R significantly increased at 2nd week, compared to those in the normal group (p<0.05). Histological changes in the gastrocnemius muscle of NI group observed that clear fat filled spaces at the periphery of muscle fibers and angular fibers. From the results of this study, non-invasive DOS could be used to measure changes of Hb concentrations in muscles.
        4,000원
        8.
        2011.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this study, optical emission spectroscopy was used to monitor the plasma produced during the RF magnetron sputtering of a BaTiO3 target. The intensities of chemical species were measured by real time monitoring with various discharge parameters such as RF power, pressure, and discharge gas. The emission lines of elemental and ionized species from BaTiO3 and Ti targets were analyzed to evaluate the film composition and the optimized growth conditions for BaTiO3 films. The emissions from Ar(I, II), Ba(I, II) and Ti(I) were found during sputtering of the BaTiO3 target in Ar atmosphere. With increasing RF power, all the line intensities increased because the electron density increased with increasing RF power. When the Ar pressure increased, the Ba(II) and Ti(I) line intensity increased, but the Ar+ line intensity decreased with increasing pressure. This result shows that high pressure is of greater benefit for the ionization of Ba than for that of Ar. Oxygen depressed the intensity of the plasma more than Ar did. When the Ar/O2 ratio decreased, the intensity of Ba decreased more sharply than that of Ti. This result indicates that the plasma composition strongly depends on the discharge gas atmosphere. When the oxygen increased, the Ba/Ti ratio and the thickness of the films decreased. The emission spectra showed consistent variation with applied power to the Ti target during co-sputtering of the BaTiO3 and Ti targets. The co-sputtered films showed a Ba/Ti ratio of 1.05 to 0.73 with applied power to the Ti target. The films with different Ba/Ti ratios showed changes in grain size. Ti excess films annealed at 600˚C did not show the second phase such as BaTi2O5 and TiO2.
        4,000원
        9.
        2004.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Chemical compositions of planetary nebulae are of interest for a study of the late stage of stellar evolution and for elemental contributions to the interstellar medium of reprocessed elements since possibly a large fraction of stars in 0.8 - 8 M⊙ range go through this stage. One of the methods for getting chemical composition is a construction of theoretical photoionization models, which involves geometrical complexities and a variety of physical processes. With modelling effort, one can analyze the high dispersion and find the elemental abundances for a number of planetary nebulae. The model also gives the physical parameter of planetary nebula and its central star physical parameter along with the knowledge of its evolutionary status. Two planetary nebulae, NGC 7026 and Hu 1-2, which could have evolved from about one solar mass progenitor stars, showed radically different chemical abundances: the former has high chemical abundances in most elements, while the latter has extremely low abundances. We discuss their significance in the light of the evolution of our Galaxy.
        4,000원
        11.
        2000.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The emission line objects such as planetary nebulae, symbiotics, gaseous nebulae, HII regions, novae, supernovae, SNRs, nearby spiral galaxies, dIrr, dE, and nearby active galactic nuclei, would be goldmines for us to dig with the 1.8m bohyunsan optical (BOAO) telescope. We discussed the importance of strategically important diagnostic lines and atomic constant calculation for a study of Galactic and extragalactic emission objects. The scientific background on a spectrometer development history is briefly presented and spectroscopic research areas other than the emission objects are also summarized.
        4,200원
        12.
        1996.12 KCI 등재 SCOPUS 구독 인증기관·개인회원 무료
        The results of the Crab pulsar observations with the photometrical MANIA (Multichannel Analysis of Nanosecond Intensity Alterations) complex at the 6-m telescope are presented. More than 12 millions photons in UBVR-bands simultaneously with time resolution of 10-7s were detected. Using the original software for search for optical pulsar period, we obtained the light curves of the object with time resolution of about 3.3 μs. Their detailed analysis gives the spectral change during pulse and subpulse, the shape of the pulse peaks, which are plateaus (with the duration of about 50 μs for the main pulse), limits for an amplitude of fine temporal (stochastic and regular) structure of pulse and sub pulse and the interpulse space intensity. The results of CCD-spectroscopy of the Crab pulsar show that its summarized spectrum is flat. There are no lines, neither emission nor absorbtion ones. Upper limit for line intensity or depth is 3.5% with the confidence probability of 95%.
        13.
        2019.09 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        This paper is a part of the series on positron annihilation spectroscopy of two-phase diffuse gas-and-dust aggregates, such as interstellar medium and the young remnants of type II supernovae. The results obtained from prior studies were applied here to detect the relationship between the processes of the annihilation of the K-shell electrons and incident positrons, and the effects of these processes on the optical spectra of their respective atoms. Particular attention was paid to the Doppler broadening of their optical lines. The relationship between the atomic mass of the elements and the Doppler broadening, ΔλD (Å), of their emission lines as produced in these processes was established. This relationship is also illustrated for isotope sets of light elements, namely 3 6 7 7 9 10 11 2 3 3 4 4 5 5 He, Li, Li, Be, Be, B, and B. A direct correlation between the γ-line luminosity ( Eγ =1.022 MeV) and D Δλ (Å) was proved virtually. Qualitative estimates of the structure of such lines depending on the positron velocity distribution function, f(E), were made. The results are presented in tabular form and can be used to set up the objectives of further studies on active galactic nuclei and young remnants of type II supernovae.
        14.
        2018.08 KCI 등재 서비스 종료(열람 제한)
        Tb3+ 이온이 첨가 된 NaCa(PO3)3 형광체의 여기 및 방출 스펙트럼 및 레이저 분광 측정을 통하여 형광특성을 조사 하였다. 고상법으로 NaCa(PO3)3:Tb3+ 형광체를 합성하였다. X선 회절측정(XRD)을 사용하여 형광체의 결정 구조 및 결정성을 분석하여 Tb3+ 이온이 30 mol%까지 첨가되어도 형광체의 결정구조가 NaCa(PO3)3의 결정상을 유지하였다. NaCa(PO3)3:Tb3+(0.01 - 30mol %)형광체의 여기 및 방출 스펙트럼과 형광의 감쇠곡선을 상온에서 측정 하였다. NaCa(PO3)3:Tb3+의 여기 스펙트럼에서 205 ~ 245 nm 영역에서 넓은 Tb3+의 4f – 5d 전이에 의한 f - d 밴드가 나타났다. NaCa(PO3)3:Tb3+의 방출 스펙트럼에서 5D4 → 7FJ 전이에 의한 강한 피크와 5D3 → 7FJ 전이에 약한 피크가 관찰 되었다. 방출 스펙트럼의 형광 강도와 형광의 수명시간 분석을 통하여 Tb3+ 이온 사이의 에너지 전이 및 교차 이완이 확인되었다.
        15.
        2015.01 KCI 등재 서비스 종료(열람 제한)
        본 연구는 고상법으로 형광체를 합성하였다. 모체 물질은 La2W3O12에 활성제로 Eu3+이온을 첨가하여 활성제 조성 변화에 따른 XRD 분석과 여기 및 방출 스펙트럼 및 온도에 따른 형광 스펙트럼 분석과 수명시간을 측정하였다. La2W3O12:Eu3+의 1 mol%의 XRD 스펙트럼은 ICSD 카드 (78180)에 보고된 데이터 스펙트럼과 비교하였을 때 XRD 스펙트럼이 잘 일치함을 확인 하였다. La2W3O12형광체에 활성제로 Eu3+이온 1 mol%를 첨가한 여기 스펙트럼에서는 286 nm 근처에서 286 nm 넓은 전하전달밴드가 관찰된다. 이 전하전달밴드는 WO4그룹과 Eu3+이온의 전하 전달 밴드이며 O2--W6+,O2--Eu3+의 ligand-to-metal 전하 전달 흡수가 이루어진다. 350〜500 nm 영역에서는 Eu3+의 f-f 전이에 의한 피크가 나타났다. 여기 스펙트럼에서 Eu3+의 7F0 → 5D4,5D4,5L6,5G4,5D3,5D2전이에 해당한다. 방출 스펙트럼은 280, 395 nm로 각각 여기한 결과 Eu3+이온의 5D0 → 7F2(618nm)에서 강한 피크가 보였다. 희토류 이온이 도핑 되지 않은 La2W3O12형광체를 266 nm로 여기하여 온도에 변화 따른 방출 스펙트럼은 저온에서 상온으로 갈수록 형광의 세기가 약하게 나타났다. 온도에 따른 수명시간은 7 K(114 μs), 100 K(94 μs), 200 K(10 μs), 300 K(0.5 μs)로 나타났다.