• 천문학회보
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• 제42권2호
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• pp.82.3-83
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• 2017

We investigate the relationships between the peak fluxes of 18 solar energetic particle (SEP) events and associated coronal mass ejection (CME) 3D parameters (speed, angular width, and separation angle) obtained from SOHO, STEREO-A and/or B for the period from 2010 August to 2013 June. We apply the STEREO CME Analysis Tool (StereoCAT) to the SEP-associated CMEs to obtain 3D speeds and 3D angular widths. The separation angles are determined as the longitudinal angle between flaring regions and magnetic footpoints of the spacecraft, which are calculated by the assumption of Parker spiral field. The main results are as follows. 1) We find that the dependence of the SEP peak fluxes on CME 3D speed from multi-spacecraft is similar to that on 2D CME speed. 2) There is a positive correlation between SEP peak flux and 3D angular width from multi-spacecraft, which is much more evident than the relationship between SEP peak flux and 2D angular width. 3) There is a noticeable anti-correlation (r=-0.62) between SEP peak flux and separation angle. 4) The multiple regression method between SEP peak fluxes and CME parameters shows that the longitudinal separation angle is the most important parameter, and the CME 3D speed is secondary on SEP peak flux.

• 한국의학물리학회지:의학물리
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• 제15권1호
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• pp.39-44
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• 2004

본 연구에서는 깊이선량률의 측정값과 단일에너지 계산값들로부터 치료용 전자선에 대한 에너지분포를 계산하였다. 최소제곱법에 기초한 수치연산을 이용하여 측정과 환산 깊이선량률의 차이가 최소가 되는 에너지분포를 결정하였다. 본 방법은 임상에 이용되는 명목에너지 6, 9, 12, 그리고 15 MeV 전자선에 대하여 적용되었다. 본 연구에서는 측정값과의 비교를 위하여 결정된 에너지분포를 입력자료로 이용한 깊이선량률의 몬테칼로 계산을 수행하였다. 계산된 깊이선량률을 측정값과 비교할 때, 모든 전자선에 대하여 표면에서 R$_{80}$ 깊이까지 측정값과 $\pm$3% 미만, 비정 근처까지 $\pm$4% 미만의 상대오차를 보였다. 본 연구는 입사 전자선의 에너지분포를 결정하기 위한 실용적 방법으로 응용될 수 있다.

• 한국표면공학회지
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• 제39권2호
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• pp.76-81
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• 2006

Molecular dynamics simulations were carried out to investigate physical sputtering of Fe(100) substrate due to energetic ion bombardments. Repulsive interatomic potentials at short internuclear distances were determined with ab initio calculations using the density functional theory. Bohr potentials were fitted to the ab initio results on diatomic pairs (Ar-Fe, Fe-Fe) and used as repulsive screened Coulombic potentials in sputtering simulations. The fitted-Bohr potentials improve the accuracy of the sputtering yields predicted by molecular dynamics for sputtering of Fe(100), whereas Moliere and ZBL potentials were found to be too repulsive and gave relatively high sputtering yields. In spite of assumptions and limitations in this simulation work, the sputtering yields predicted by the molecular dynamics method were in fairly good accordance with the obtainable experimental data in absolute values as well as in manner of the variation according to the Incident energy. Threshold energy for sputtering of Fe(100) substrate was found to be about 40 eV. Additionally, distributions of kinetic energies of sputtered atoms and their original depths could be obtained.

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2267-2273
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• 2011

A novel energetic material, 1-amino-1-(2,4-dinitrophenylhydrazinyl)-2,2-dinitroethylene (APHDNE), was synthesized by the reaction of 1,1-diamino-2,2-dinitroethylene (FOX-7) and 2,4-dinitrophenylhydrazine in N-methyl pyrrolidone (NMP) at 110 $^{\circ}C$. The theoretical investigation on APHDNE was curried out by B3LYP/6-311+$G^*$ method. The IR frequencies analysis and NMR chemical shifts were performed and compared with the experimental results. The thermal behavior of APHDNE was studied by DSC and TG/DTG methods, and can be divided into two crystal phase transition processes and three exothermic decomposition processes. The enthalpy, apparent activation energy and pre-exponential factor of the first exothermic decomposition reaction were obtained as -525.3 kJ $mol^{-1}$, 276.85 kJ $mol^{-1}$ and $10^{26.22}s^{-1}$, respectively. The critical temperature of thermal explosion of APHDNE is 237.7 $^{\circ}C$. The specific heat capacity of APHDNE was determined with micro-DSC method and theoretical calculation method, and the molar heat capacity is 363.67 J $mol^{-1}K^{-1}$ at 298.15 K. The adiabatic time-to-explosion of APHDNE was also calculated to be a certain value between 253.2-309.4 s. APHDNE has higher thermal stability than FOX-7.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2352-2358
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• 2012

A high-nitrogen energetic salt, 1-amino-1-hydrazino-2,2-dinitroethylene guanidine salt [G(AHDNE)], was synthesized by reacting of 1-amino-1-hydrazino-2,2-dinitroethylene (AHDNE) and guanidine hydrochloride in sodium hydroxide aqueous solution. The theoretical investigation on G(AHDNE) was carried out by B3LYP/$6-311+G^*$ method. The thermal behaviors of G(AHDNE) were studied with DSC and TG-DTG methods, and the result presents an intense exothermic decomposition process. The enthalpy, apparent activation energy and pre-exponential constant of the process are $-1060J\;g^{-1}$, $148.7kJ\;mol^{-1}$ and $10^{15.90}s^{-1}$, respectively. The critical temperature of thermal explosion of G(AHDNE) is $152.63^{\circ}C$. The specific heat capacity of G(AHDNE) was studied with micro-DSC method and theoretical calculation method, and the molar heat capacity is $314.69J\;mol^{-1}K^{-1}$ at 298.15 K. Adiabatic time-to-explosion of G(AHDNE) was calculated to be a certain value between 60-72 s. The detonation velocity and detonation pressure were also estimated. G(AHDNE) presents good performances.

• 한국추진공학회지
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• 제20권2호
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• pp.46-55
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• 2016

Differential Scanning Calorimetry(DSC) 실험 데이터를 이용하여 고에너지 물질의 반응속도식을 추출해내는 이론적 방법을 제안하고 알루미늄 고함유 화약(RDX/HTPB/Al)에 대한 반응속도식 추출을 수행하였다. DSC 실험 결과는 Friedman 등전환법으로 분석되었다. 질량분율에 따른 활성화에너지와 빈도인자를 추출해 내어 반응속도식을 완성하였다. 추출된 반응속도식은 고에너지 물질의 화학반응과정을 몇 단계의 주요단계로 가정하는 형태가 아닌 전체 화학반응 과정을 나타내는 형태를 갖는다. 이는 기존의 ODTX 실험을 통해 추출되는 화학반응속도식 형태에 비해 이론적 측면과 정확성 측면에서 상당한 장점을 갖는다. 추출된 반응속도식의 검증을 위해 화학반응률 그리고 생성물 질량분율에 대해 DSC 실험과 동일한 조건하에서 전산모사를 수행하였으며 실험값과 잘 일치함을 확인하였다. 또한 완속가열 전산모사를 수행하였으며 실험결과와 비교하여 DSC 반응속도식의 전산모사에의 적용가능성을 확인하였다.

• Journal of Mechanical Science and Technology
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• 제17권10호
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• pp.1572-1582
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• 2003

Hybrid rocket combustion has a manifestation of stable response to the perturbations compared to solid propellant combustion. Recently, it has revealed that the low frequency combustion instability about 10 Hz was occurred mainly due to thermal inertia of solid fuel. In this paper, the combustion response function was theoretically derived by use of ZN (Zeldovich-Novozhilov) method. The result with HTPB/LOX combination showed a quite good agreement in response function with previous works and could predict the low frequency oscillations with a peak around 10 Hz which was observed experimentally. Also, it was found that the amplification region in the frequency domain is independent of the regression rate exponent n but showed the dependence of activation energy. Moreover, the response function has shown that the hybrid combustion system was stable due to negative heat release of solid fuel for vaporization, even though the addition of energetic ingredients such as AP and Al could lead to increase heat release at the fuel surface.

• 공업화학
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• 제30권1호
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• pp.81-87
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• 2019

에너지화 열가소성 탄성체 제조에 사용될 수 있는 새로운 계열의 glycidyl azide polymer (GAP)을 모색하기 위해 전구체인 poly(epichlorohydrin) (PECH)에 친핵체인 아지드기와 알콕시 및 알킬 아민을 도입하여 4가지 GAP copolymer polyol을 합성하고 물성에 대하여 고찰하였다. 이 GAP copolymer 합성반응은 이종의 친핵체를 1단계 반응으로 동시에 치환하여 미반응 sodium azide가 남지 않는 친환경적이며 효율적인 합성법으로 평가할 수 있다. 역개폐 짝풀림(inverse gated decoupling) $^{13}C$ NMR 분석법과 Fourier transform infrared (FT-IR) 분석법으로 상대적 치환율을 정량적으로 분석하였으며 반응 진행도를 모니터링 하였다. 합성된 GAP copolymer의 유리전이온도와 분자량은 differential scanning calorimetry (DSC)와 gel permeation chromatography (GPC)로 분석하였다. 합성된 poly($GA_{0.8}-butoxide_{0.2}$), poly($GA_{0.7}-n-butylamine_{0.3}$), poly($GA_{0.7}-dipropylamine_{0.3}$), poly($GA_{0.7}-morpholine_{0.3}$)의 유리전이온도는 $-39^{\circ}C$에서 $-26^{\circ}C$ 범위의 값을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.165-169
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• 2001

Carbon nitride films were grown on Si (100) substrate by a laser-electric discharge method with and without a magnetic field assistance. The magnetic field leads to vapor plume plasma expending upon the ambient arc discharge plasma area. Influence of the magnetic field has resulted in increase of a crystallite size in the films due to bombardment (heating) of Si substrates by energetic carbon and nitrogen species generated during cyclotron motion of electrons in the discharge zone. Many crystalline grains were observed in the morphology of the deposited films by scanning electron microscopy. In order to determine the structural crystalline parameters, X-ray diffraction (XRD) was used to analysis the grown films.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.222-227
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• 2000

At representative thermoeconomic theory to determine the unit cost of multiple products, there are the $\ulcorner$SPECO$\lrcorner$ method of Tsatsaronis's study group and the $\ulcorner$MOPSA$\lrcorner$ method of chung-ang university phase laboratory. Against this theory, we propose new theory called $\ulcorner$Thermoeconomics to divide the exergetic cost into each working fluid$\lrcorner$ in this study. Also, we apply new thermoeconomic theory to CGAM problem (30MW-grade imaginary gas turbine cogeneration power plant) that it is representative power system in thermoeconomics theory, and we fixed to interpreted the unit cost of electricity on the part of gas turbine and the unit cost of steam exergy(enthalpy) on the part of HRSG.