Cation이 Europium, Praseodymium인 Nitroprusside [Fe(CN)?NO]²­ 분말내의 중심 원자인 철에 대한 M?ssbauer parameters

劉演奉 삼척대학교 1997 論文集 Vol.30 No.3

We observed the ?Fe Mossbauer spectra for the ground states at room temperature of sodium nitroprusside. Na₂[Fe(CN)?NO]·2H₂O single crystal. europium notroprusside. Eu₂[Fe(CN)?NO]₃·9H₂O powder. praeseodymuim nitropruside and Pr₂[Fe(CN)?NO]₃·6H₂O powder which is substituted cations as rare earth metal element. The M??ssbauer parameters. isomer shifts (I.S.). quadrupole splittings (Q.S.) and full width half maxima (F.W.H.M.T.) of the ground state in two powder samples are compared with ground state of sodium nitroprusside single crystal for analysis of the electronic properties of the materials. We have found that values of quadrupole splitting for ground state in two powder samples are positive larger than these parameter in sodium nitroprusside single crystal and values of ?????? shifts of these for ground state in there samples are equal within experimental errors.

중성자 조사된 원자로압력 용기에 대한 풀림 효과

劉演奉 三陟大學校 1999 論文集 Vol.32 No.3

To estimate the thermal annealing effect of the nuclear reactor pressure vessel (RPV) by the fast neutron (En>1MeV) irradiation, we have studied the change of the Mossbauer parameters of RPV steel with the fast neutrons dosage of 1, ??, ?? n/㎠. DSC experiment was done to find annealing temperature of all samples, so all samples were annealed at 600℃ for 1, 2, 3 and 4 hours respectively. The influence of neutron irradiation on RPV steel was studied by Mossbauer effect. The Mossbauer spectra for all samples showed the superposition of two sextets and one doublet at room temperature. The isomer shift(I. S.) and quadrupole splitting(Q. S.) values of sextets were changed within experimental errors for all samples, but these values of doublet were rapidly changed at the sample of the dose ?? n/㎠. The magnetic hyperfine field was varied within ±3%. For thermal annealing, we can not found any particular change in the values of I.S. and Q. S. But in Geff. we think that there were any annealing effect for the dose 1016 n/㎠ after 3 hours annealing time.

Mo¨ssbauer 분광법에 의한 Ni_(0.8)Zn_(0.2)Fe₂O₄Ferrite에 대한 연구

유연봉,백승수 三陟大學校 産業科學技術硏究所 2003 産業科學技術硏究論文集 Vol.8 No.2

페라이트계 전파흡수체로 사용되이지고 있는 Ni_(0.8)Zn_(0.2)Fe₂O₄를 택하여 800~1100℃각 2시간씩 소결하여 자료를 합성하여 조사하였다. 고온에서 소결할수록 모분발의 XRD peak는 감소하여 spinel ferrite peak이 우세하였으며, 입자의 크기는 증가하였다. 또한 보자력은 감소한 반면 magnetization saturation은 증가하였다. 따라서 본 실험에서는 fernte 제주의 합성온도 1100℃에서 양실의 시료를 합성화하였고 보문말의 ferrite합성이 1100℃에서 가장 활발하였다.

다공질 실리콘 PL특성에 대한 열적 안정성

劉演奉 三陟大學校 1995 論文集 Vol.28 No.2

The thermal stability of the photoluminescence and Raman spectra of various thermally treated porous silicon samples have been investigated. Samples were prepared by electrochemially etching silicon wafers with a current density of 50mA/㎠ in an HF, DI water solution for 10 min and then post-annealing them under various conditions. Porous silicon samples which underwent rapid thermal oxidization and further annealing in a N2 ambient were compared with those which were only rapid thermal annealed. Anealing of as-prepared porous silicon in an inert gas atmosphere shows a severe degradation in the photoluminescence intensity 500℃, whereas, the photoluminescence of the pre-oxidized samples shows thermal stability. Oxidation of the sample is believed to cause of this stability.

W/Si 및 WNx/Si Schottkey 다이오우드의 전기적 특성

劉演奉 三陟大學校 1995 論文集 Vol.28 No.2

The electrical properties of the W/Si and WNx/Si Schottkey contacts deposited by plasma enhanced chemical vapor deposition technique were investigated. We measured leakage current at 5V reverse bias for W/Si, WNx/Si diodes fabricated with various reactant gases. The leakage current for WNx/Si diode deposited with WF6-NH3-H2 gas system has the lowest value of all. As-deposited tungsten film was a polycrystal consisting of only (110), (200), and (211) oriented α-W phase, similarly in the case of the tungsten films deposited on silicon by plasma enhanced chemical vapor deposition. And, as-deposited WNx film NH3/WF6=0.5 ratio shows a amorphous structure slightly consisting of α-W and metastable β-W phases. Then the thermal stability and elctrical property of the WNx/Si samples were compared with the W/Si samples by Ⅰ-V, XRD, SEM measurements. It is evident that the thermal stability of the WNx/Si diodes is excellent than the W/Si diodes. We then measured leakage current after annealing at reverse applied voltage. The leakage current for W/Si diode increased with annealing at 900℃ for 20sec, but that for WNx/Si diode decreased slightly at 900℃. Therefore, it is thought that WNx is stble during high temperature annealing above about 800℃ because the tungsten-silicide is not performed at WNx/Si interface.

한국형기동헬기 임무컴퓨터 비행필수기능 설계

유연운,김태열,장원홍,김성우,임종봉,Yu, Yeon-Woon,Kim, Tae-Yeol,Jang, Won-Hong,Kim, Sung-Woo,Lim, Jong-Bong 한국군사과학기술학회 2011 한국군사과학기술학회지 Vol.14 No.2

Avionics system tends to be designed to have the integrated architecture, and it is getting difficult and complex to verify the flight-critical function because of sophisticated structure. In Korean Utility Helicopter, mission computer acts as the MUX Bus Controller to handle the data from both communication, identification, mission/display and survivability equipment inside Mission Equipment Package and aircraft subsystems such as fuel system and electrical system while it is interfacing with Automatic Flight Control System and Full-Authority Digital Engine Control via ARINC-429 bus. The Flight Displays which is classified as flight-critical function in aircraft is implemented on Primary Flight Display after mission computer processes data from AFCS in order to generate graphics. This paper defines the flight-critical function implemented in mission computer for KUH, and presents the static and dynamic test procedures which is performed on System Integration Laboratory along with Playback Recorder prior to flight test.

한국형 기동헬기 임무탑재장비체계 설계 및 입증

김성우,이병화,유연운,이종훈,임종봉,Kim, Sung-Woo,Lee, Byoung-Hwa,Yu, Yeon-Woon,Lee, Jong-Hoon,Yim, Jong-Bong 한국군사과학기술학회 2011 한국군사과학기술학회지 Vol.14 No.3

Mission Equipment Package(MEP) system is a collection of avionic components that are integrated to perform the mission of the Korean Utility Helicopter(KUH). MEP system development is classified mission-critical embedded system but KUH MEP system developed including flight-critical data implementation. It is important to establish the good development and verification process for the successful system development. This paper describe the development and verification process in each phase for the KUH MEP system. MEP system design is verified through the qualification test, system failure test and compatibility test in System Integration Laboratory(SIL).

Mo¨ssbauer Parameters of Fast Neutron-irradiated Nuclear Pressure Vessels at Room- and Liquid nitrogen-temperature

이용곤,김형상,홍치유,유연봉 동국대학교 자연과학연구원 2000 자연과학연구 논문집 Vol.5 No.-

The embrittlement of fast neutron-irradiated reactor pressure vessel (RPV) steels was investigated by X-ray diffraction patterns at room temperature and Mo¨ssbauer spectroscopy at room- and liquid nitrogen-temperature. Neutron fluence on the samples were 1012, 1013, 1014, 1015, 1016, 1017, 1018n/cm². The X-ray diffraction patterns at room temperature showed that the structure of neutron unirradiated sample was bcc type, where as but the neutron irradiated samples with the fluence higher than 1017 n/cm² were so severely damaged, that bcc type structure disappeared. The Mo¨ssbauer spectra of all samples showed superposition of two or more sextets. In this paper all Mo¨ssbauer spectra were fitted by three set of sextet. The isomer shift and quadrupole splitting values were found around zero. At liquid nitrogen temperature, magnetic hyperfine field increase rapidly to 480 ∼ 552 kOe at S1 sextet in the samples of 1017∼1018n/cm² neutron fluences. And room temperature, magnetic hyperfine field also increased rapidly to 480 ∼507 kOe at S1 sextet in the samples of 1017∼1018n/cm²neutron fluences. This rapid increase of magnetic hyperfine field was infered to be caused by the change of 56Fe, 55Mn into 57Fe by neutron irradiation.

Study on the oxidation states of the iron atoms in hematinics by Mossbauer spectroscopy

김순구,김형상,이용곤,장상철,홍치유,유연봉 동국대학교 자연과학 연구원 1999 자연과학연구 논문집 Vol.4 No.-

Iron in the body is an essential element of trace elements and is a very important element of hemoglobin and enzyme products. It was studied by Mossbauer spectroscopy that the oxidation states of Fe atoms contained in the hematinics. From Mossbauer parameter we are able to investigate the interaction of Fe atoms with surrounding elements related to the oxidation states of Fe atoms. Mossbauer spectra for all hematinics samples showed the superposition of two doublet at the room temperature. Consequently the Fe atoms for the six samples as usual exists in the S=2 high spin of Fe²+ and in the S=1/2 low spin state of Fe³+. Also we were able to observe that the absorption area of Fe²+ state was larger than Fe³+ state.

소결온도 변화에 의한 LiFePO₄ 전극의 분광학적 특성 연구

김선배,김지영,김형배,김형상,윤인섭,유연봉 한국진공학회 2007 한국진공학회 학술발표회초록집 Vol.16 No.1