• Bulletin of the Korean Chemical Society
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• v.20 no.5
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• pp.559-566
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• 1999

Gas-phase alkylations of delocalized ambident anions, Y---CH---X- where X, Y=CH2, O, or S, have been investigated theoretically at the MP2/6-31+G*//MP2/6-31+G* and QCISD/6-31+G*//MP2/6-31+G* lev-els. O-and S-alkylations (X=O and S) are more favored kinetically by ΔE^≠ = 4.6 and 9.8 kcal mol-1 than the respective C-alkylations even though they are thermodynamically less favored by 22.4 and 6.0 kcal mol-1 respectively. It was found that the transition structures for the C-alkylations are imbalanced due to the endoergic rehybridi-zation of the carbon center from sp2 to sp3 which leads to premature bond contraction of the C-Y bond and delayed bond stretching of the C-X bond. In the O-, or S-alkylation, such endoergic process is not required since the σ-lone pair on O or S is involved in the initial stage of alkylation. The imbalanced TSs for the C-alkylation are accompanied by higher intrinsic barriers and deformation energies.

• Clinical and Experimental Reproductive Medicine
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• v.8 no.2
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• pp.35-43
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• 1981

In order to evaluate the clinical utilization and efficacy of X-ray pelvimeter, a study of selective information from 292 cases, who had clinical and X-ray pelvimetry, among 7346 single term deliveries in the years 1975 and 1978 was undertaken in Yonsei University Medical Center. The results revealed that there were no significant statistical difference between X-ray and clinical pelvimetry groups in terms of the outcome of labor and in regard to determining the pelvic size (p > 0.05). Most X-ray examination which caused significant fetal exposure were pelvimetries.

• Current Applied Physics
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• v.18 no.11
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• pp.1212-1217
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• 2018

The electric field-induced modifications of magnetic anisotropy in CoFeB/MgO systems are studied using X-ray resonant magnetic scattering and magneto-optical Kerr effect. Voltage dependent changes of the magnetic anisotropy of -12.7 fJ/Vm and -8.32 fJ/Vm are observed for Ta/CoFeB/MgO and Hf/CoFeB/MgO systems, respectively. This implies that the interfacial perpendicular magnetic anisotropy is reduced (enhanced) when electron density is increased (decreased). X-ray resonant magnetic scattering measurements reveal that the small in-plane magnetic component of the remanent state of CoFeB/MgO systems with weak magnetic anisotropy changes depending on the applied voltage leading to modification of the magnetic anisotropy at the CoFeB/MgO interface.

• International Journal of Computer Science & Network Security
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• v.23 no.6
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• pp.84-90
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• 2023

In this article the problem of computing floating-point reciprocal cube root functions is considered. Our new algorithms for this task decrease the number of arithmetic operations used for computing $1/{\sqrt[3]{x}}$. A new approach for selection of magic constants is presented in order to minimize the computation time for reciprocal cube roots of arguments with movable decimal point. The underlying theory enables partitioning of the base argument range x∈[1,8) into 3 segments, what in turn increases accuracy of initial function approximation and decreases the number of iterations to one. Three best algorithms were implemented and carefully tested on 32-bit microcontroller with ARM core. Their custom C implementations were favourable compared with the algorithm based on cbrtf(x) function taken from C ＜math.h＞ library on three different hardware platforms. As a result, the new fast approximation algorithm for the function $1/{\sqrt[3]{x}}$ was determined that outperforms all other algorithms in terms of computation time and cycle count.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1B
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• pp.107-111
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• 2006

The samples collected from two reactors are analyzed by X-ray diffraction and M$\ddot{o}$ssbauer spectroscopy in this study. It is concluded that the iron oxide crystal attached on anthracite media which possesses catalytic ability is identified to be Ferrihydrite, regardless of the value of pH from the analysis of the iron oxide. Iron oxide in Batch reactor is identified to be Microcrystalline goethite.

• Nuclear Engineering and Technology
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• v.56 no.1
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• pp.241-246
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• 2024

The study was carried out by numerical integration based on the diffraction properties and elemental composition. The elemental compositions of breast tissues in the literature were tested. The photon attenuation coefficients calculated using the recent elemental composition were found within 0.2-16% for adipose tissue and within 0.04-17% for glandular tissue with the experimental reference data. The attenuation coefficients of cancerous breast tissue calculated according to the elemental content previously measured in breast cancer patients were found within 0-17% with experimental data in the literature. The attenuation coefficients are of great interest to medical research. To calculate realistic attenuation coefficients, the characteristic coherent scatter, which is most intense at small angles, must be considered. For this reason, experimentally measured form factor data were reviewed, and the most compatible one with the theoretical form factor data produced in this study was used at low momentum transfer x (0 < x ≤ 8 nm^-1). The differential linear coherent scattering distributions were calculated for an energy value of 17.44 keV and compared with their experimental counterparts.

• Annual Conference of KIPS
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• 2024.05a
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• pp.258-261
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• 2024

크리덴셜 스터핑 공격에 대응하기 위해 일부 기업에서는 C3(Compromised Credential Checking) 서비스를 제공한다. 인증 정보 대상 공격이 고도화됨에 따라 유출 계정의 양은 매우 방대한 것으로 드러나고 있으며, C3 서비스 서버의 데이터의 양 또한 지속해서 증가할 것이다. 그러나 C3 서비스의 PSI(Private set intersection) 프로토콜은 정적인 환경에서의 데이터 연산을 전제로 적용되고 있어 이용자가 반복연산을 요청했을 때의 연산 복잡도를 상쇄할 수단이 없다. 본 연구에서는 반복연산에 적용할 수 있는 updatable PSI 를 제안하였으며, static PSI 대비 x2~x4.3 의 전처리 시간과 x1.8~ x3.3 의 데이터 전송량이 효율적으로 개선되었음을 보인다.

• Progress in Medical Physics
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• v.27 no.1
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• pp.8-13
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• 2016

Dual energy cone-beam CT can distinguish two materials with different atomic compositions. The principle of dual energy cone-beam CT based on modulation layer is that higher energy spectrum can be acquired at blocked x-ray window. To evaluate the possibility of modulation layer based dual energy cone-beam CT, we analyzed x-ray spectrum for various thicknesses of modulation layers by Monte Carlo simulation. To compare with the results of simulation, the experiment was performed on prototype cone-beam CT for 50~100 kVp with CdTe XR-100T detector. As the result of comparing, the mean energy of energy spectrum for 80 kVp are well matched with that of simulation. The mean energy of energy spectrum for 80 and 120 kVp were increased as 1.67 and 1.52 times by 2.0 mm modulation layer, respectively. We realized that the virtual dual energy x-ray source can be generated by modulation layer.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.58-66
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• 1999

The catalytic oxidation of vinyl chloride was investigated over $CrO_x$ impregnated on $Al_2O_3$ at temperature between 200 and $400^{\circ}C$. The major carbonaceous products were CO and $CO_2$, and the selectivity of $CO_2$ was gradually increased with increasing reaction temperature, while that of CO was dropped consequently. This suggests that CO is the first product which is further oxidized to $CO_2$ in the oxidation of vinyl chloride over $CrO_x/Al_2O_3$. The addition of HCl in the feed didn't affect the conversion of vinyl chloride, but the selectivity of $CO_2$ decreased by adding HCl. It implies that HCl inhibits, the complete oxidation of vinyl chloride to $CO_2$. When oxidizing vinyl chloride in dry air, significant amounts of $Cl_2$ were observed, while no $Cl_2$ was detected in the humid condition. The activities of several catalysts including various precious metals and other transition metal oxides were measured, it was found that the catalytic activity of 12% $CrO_x/Al_2O_3$ was higher than other catalysts except 1% $Pt/Al_2O_3$. The reaction rate of 12% $CrO_x/Al_2O_3$ was 1.2 times lower than that of 1% Pt/alumina, but it was 3 to 8 times more active than other catalysts for vinyl chloride oxidation at $275^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.3
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• pp.368-381
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• 2020

This study was conducted to optimize the processing conditions of seasoned laver Pyropia yezoensis with conger eel Conger myriaster seasoning sauce (CES) using response surface methodology (RSM). The RSM program results for bonesoftness showed that the optimum independent variables based on the dependent variables (Y₁, lipid removal rate; Y₂, texture; and Y₃, sensory fish odor score) were 431.0% for X₁ (water amount), 115.6℃ for X₂ (retort-operated temperature), and 50.1 min for X₃ (retort-operated time). The RSM program results for the CES blend showed that the optimum independent variables (X₁, amount of bone-softened conger eel by-products; X₂, mixed sauce amount; and X₃, starch amount) based on the dependent variables (Y₁, amino-N; Y₂, Hunter redness; and Y₃, drying time) were 44.8% for A (pre-treated conger eel by-product), 36.0% for B (mixed sauce), and 19.2% for C (starch). The RSM program results for seasoned laver with CES showed that the optimum independent variables based on the dependent variables (Y₁, water activity; Y₂, Hunter yellowness; and Y₃, overall acceptance) were 5.0% for X₁, (CES amount), 313.8℃ for X₂ (roasting temperature), and 6.0 s for X₃ (roasting time). The seasoned laver with CES prepared under the optimum conditions was superior to commercial seasoned laver in terms of overall acceptance.