• Bulletin of the Korean Chemical Society
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• 제18권10호
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• pp.1076-1082
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• 1997

The infrared, Raman, and jet-cooled laser-induced fluorescence excitation spectra of 1,2,3,4-tetrahydronaphthalene have been recorded and analyzed. The observed vibrations have been assigned to understand the conformational behaviors in its electronic ground (S0) and excited (S1) states. Ab initio at the HF/6-31G** level and molecular mechanics (MM3) force field calculations have been carried out to generate the complete normal mode frequencies of the molecule in its S0 state. The vibrational frequencies calculated from the ab initio method show a better agreement with the observed infrared and Raman frequencies than those calculated from the MM3 method. In several cases, the normal mode calculations were very helpful to clarify some ambiguities of previous assignments. In addition, the ring inversion process between two twisted conformers of 1,2,3,4-tetrahydronaphthalene has been reexamined utilizing ab initio calculation. The results show that the ring inversion energy is in the range of 3.7-4.3 kcal/mol which is higher than the previously reported AM1 value of 2.1 kcal/mol.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3247-3251
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• 2010

Molecular structures of the various conformers for the four stereoisomers of tetra-t-butyl-tetra-O-methylsulfinylcalix[4]arene (1) were optimized using DFT BLYP and mPW1PW91/6-31G(d,p) (hybrid HF-DF) calculation methods. We have analyzed the total electronic and Gibbs free energies and normal vibrational frequencies of 16 different structures from four major conformations (cone (CONE), partial cone (PC), 1,2-alternate (1,2-A), 1,3-alternate (1,3-A)) of the four stereoisomers [1(rccc), 1(rcct), 1(rctt), 1(rtct)]. The mPW1PW91/6-31G(d,p) calculations suggested that the $1(rccc)_{CONE}$, $1(rcct)_{PC}$, $1(rctt)_{PC}$, and $1(rtct)_{1,3-A}$ were the most stable conformations of the respective stereoisomers. These outcomes are in accordance with the experimental structures obtained from X-ray crystallography. The electrostatic repulsion between the sulfinyl and methoxy groups is a primary factor for the relative stabilities of the four different conformations. The IR spectra of the most stable conformers [$1(rccc)_{CONE}$, $1(rcct)_{PC}$, $1(rctt)_{PC}$, $1(rtct)_{1,3-A}$] of each stereoisomer were compared to each other.

• 한국의학물리학회지:의학물리
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• 제22권4호
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• pp.206-215
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• 2011

다엽콜리메이터, 겐트리회전, 선량율 등에서 형성되는 플루언스 맵을 이용하여 환자 맞춤형 치료 선량검증이 가능한지 알아보았다. 플루언스 맵은 2D 배열 검출기로 측정하였고, 동일 치료계획을 팬톰 내에서 이온전리함, 필름, 유리선량계 등을 이용하여 측정 비교하였다. 목표점에서 체적감마인자(volume gamma index, 3%, 3 mm)기준에 통과율은 $85.22%{\pm}1.7$(RT_target), $89.96%{\pm}2.15$였고, G4는 $95.14%{\pm}1.18$이었다. 선량 전달 오차는 선량이 급격히 변화는 영역(G1, G2, G3)과 주요장기(G4)에서 각각 $11.72%{\pm}0.531$, $-11.47%{\pm}0.991$, $7.81%{\pm}0.857$, $-4.14%{\pm}0.761$이었다. 이온전리함 측정값의 상대오차는 각각 평균 $-1.02%{\pm}0.222$ (Rt_target), $0.96%{\pm}0.294$ (Lt_target)이었다. 필름의 감마인자(3%, 3 mm) 기준 평균 통과율은 $92.59%{\pm}3.312$이었다. 유리선량계 상대 오차는 8.3% (G1), -5.4% (G2), 7.2% (G3), 6.1% (G4)이었다. 체적변조회전방사선 치료(VMAT)시 실시간 플루언스 맵 측정을 통한 실시간 환자 맞춤형 선량 검증이 가능할 것으로 사료되었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권7호
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• pp.43-52
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• 2015

The uranium removal capacity of radish sprouts (Raphanus sativus L.) in groundwater was calculated on the basis of the amount of uranium accumulated in the radish sprouts rather than the concentration in solution, of which process was very limited in previous studies. Continuous rhizofiltration clean-up system was designed to investigate the feasibility of radish sprouts, applying for uranium contaminated groundwater (U concentration: 110 μg/L) taken at Bugogdong, Busan. Six acrylic boxes (10 cm × 30 cm × 10 cm) were connected in a direct series for the continuous rhizofiltration system and 200 g of radish sprouts cultivars was placed in each box. The groundwater was flushed through the system for 48 hours at the constant rate of 5 mL/min. The rhizofiltration system was operated in the phytotron, of which conditions were at 25℃ temperature, 70% of relative humidity, 4,000 Lux illumination (16 hours/day) and 600 mg/L of CO₂ concentration. While 14.4 L of contaminated groundwater was treated, the uranium removal efficiency of the radish sprouts (1,200 g in wet weight) was 77.2% and their removal capacities ranged at 152.1 μg/g-239.7 μg/g (the average: 210.8 μg/g), suggesting that the radish sprouts belong to the group of hyper-accumulation species. After the experiment, the sum of U amounts accumulated in radish sprouts and remained in groundwater was 1,472.2 μg and the uranium recovery ratio of this rhizofiltration experiment was 92.9%. From the results, it was investigated that the radish sprouts can remove large amounts of uranium from contaminated groundwater in a short time (few days) because the fast growth rate and the high U accumulation adsorption capacity.

• 대한조선학회논문집
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• 제31권4호
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• pp.99-108
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• 1994

본 연구는 "유조선 구조해석을 위한 유한요소 입력자동화 프로그램의 개발"[1]의 연속된 연구결과로서, 유조선, 살물화물선, 콘테이너선등의 일반 상용 선박을 대상으로 유한요소법을 이용하여 선체중앙부(3-D cargo hold)구조해석을 수행할 때, 구조모델링과 해석을 위한 입력자료처리를 효율적으로 자동화하는 과정을 연구하였다. 본 논문에서는 전년도에 발표된 기본 알고리즘을 바탕으로 다양한 형태의 선종별 적용성, MSC/NASTRAN 인터페이스와 관련한 평면 유한요소 자동분할 기법, 파랑하중 직접계산 인터페이스 개발 및 입력자료 처리과정에 도입된 Graphic User Interface기법 등 새로이 개발된 내용에 대하여 자세히 기술하고, 다양한 실적선에 적용함으로써 프로그램의 유용성을 확인하였다.

• 한국전자파학회논문지
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• 제9권4호
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• pp.491-498
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• 1998

본 논문은 유한차분 시간영역 해석법(Finite-Difference Time-Domain method)을 사용하여 1.8 GHz용 휴대폰으로부터 방출된 전파의 인체 두부에 흡수된 전력량을 산출하였다. 이를 위하여 인체 두부를 7층 매질로 모델령하였고, 휴대폰은 금속상자에 부착된 모노폴 안테나로 모텔링하였다. 모델링에 사용된 인체 두부와 휴대폰의 크기는 상용의 크기를 갖도록 하였다. 이를 위하여 모노폴 안테나의 길이는 4.5 em으로 하였다. 설정된 모텔링하에서 인체의 위해 정도를 알려주는 지수인 비흡수율(SAR-Specific Absorption Rat te)의 분포를 계산하였고 그 결과 비홉수율이 최대가 되는 지점은 인체 두뇌의 깊숙한 점이 아닌 두부의 표피근 방임을 알게 되었다. 그리고 설정된 조건하에서 그 최대치는 1.4 mW/g이었는데, 이는 국제 권고치인 1.6 mW/g보다 약간 작은 값이었다.

• Bulletin of the Korean Chemical Society
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• 제31권7호
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• pp.1875-1880
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• 2010

A dicycle pyrazoline derivative, 1-phenyl-5-(p-fluorophenyl)-3,4-($\alpha$-p-fluoro-tolylenecyclohexano) pyrazoline, was synthesized and characterized by elemental analysis, IR, UV-vis, fluorescence spectra and X-ray single crystal diffraction. Density function theory (DFT) calculations were performed by using B3LYP method with 6-$311G^{**}$ basis set. The optimized geometry can well simulate the molecular structure. Vibrational frequencies were predicted, assigned and compared with the experimental values, which suggest that B3LYP/6-$311G^{**}$ method can well predict the IR spectra. Both the experimental electronic absorption spectra and the predicted ones by B3LYP/6-$311G^{**}$ method reveal three electron-transition bands, with the theoretical ones having some red shifts compared with the experimental data. Natural bond orbital analyses indicate that the absorption bands are mainly derived from the contribution of n $\rightarrow\pi^*$ and $\pi\rightarrow\pi^*$ transitions. Fluorescence spectra determination shows that the title compound can emit blue-light at about 478 nm. On the basis of vibrational analysis, the thermodynamic properties of title compound at different temperature have been calculated, revealing the correlations between $C^0_{p,m}$, $S^0_m$, $H^0_m$ and temperature.

• Bulletin of the Korean Chemical Society
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• 제19권8호
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• pp.847-851
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• 1998

13C, 15N, and 29Si NMR chemical shifts have been computed for selected X-substituted silatranes (X=Cl, F, H, CH3) using Gauge-Including Atomic Orbitals (GIAO) and Continuous Set of Gauge Transformations (CSGT) at the Hartree-Fock level of theory. The isotropic 13C chemical shifts are largely insensitive to substituent-induced structural changes. In this study, the isotropic 13C chemical shifts GIAO and CSGT calculations at the HF/6-31G and HF/6-31G* levels are sufficiently accurate to aid in experimental peak assignments. The isotropic 13C chemical shifts X-substituted silatranes at HF/6-31G* level are approximately 4 ppm different from the experimental values. In contrast, the isotropic 15N and 29Si chemical shifts and the chemical shielding tensors are quite sensitive to substituent-induced structural changes. These trends are consistent with those of the experiment. The 15N chemical shift parameters demonstrate a very clear correlation with Si-N distance, especially when we use the polarization function. Changes in anisotropy, 3a as well as in the 15N isotropic chemical shifts are due primarily to changes in the value of a.. But in case of "Si the correlations are not as clean as for the 15N chemical shift.

• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1079-1087
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• 2021

NTP-ERSN is a package developed for solving the multigroup form of the discrete ordinates, characteristics and collision probability of the Boltzmann transport equation in one-dimensional cartesian geometry, by combining pin cells. In this work, C5G7 MOX benchmark is used to verify the accuracy and efficiency of NTP-ERSN package, by treating reactor core problems without spatial homogenization. This benchmark requires solutions in the form of normalized pin powers as well as the vectors and the eigenvalue. All NTP-ERSN simulations are carried out with appropriate spatial and angular approximations. A good agreement between NTP-ERSN results with those obtained with OpenMC calculation code for seven energy groups. In addition, our studies about angular and mesh refinements are carried out to produce better quality solution. Moreover, NTP-ERSN GUI has also been updated and adapted to python 3 programming language.

• 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.