• Bulletin of the Korean Chemical Society
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• v.28 no.6
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• pp.1031-1034
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• 2007

The R- and Z-substituent effects for the gas-phase thermal decompositions of carbamates, R2NC(=O)- OCH2CH2Z, have been investigated theoretically at B3LYP level with 6-31G(d) and 6-31++G(d,p) basis sets. Both the Z- and R-substituent effects on reactivity (ΔH≠) were well consistent with experimental results, although the R-substituent effect was underestimated theoretically. No correlations were found between activation enthalpies and reaction enthalpies. The substituent effects on reactivity seemed to be complicated at a glance, but were understandable by concurrent electronic and steric factors. Variations of bond lengths at TS structures were well correlated with the Taft's σ* values and the TS structures became tighter as the Zsubstituent became a stronger electron-acceptor (δσ* > 0). However the effects of R-substituents on the TS structures were much smaller when compared to those of Z-substituents.

• Journal of Magnetics
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• v.10 no.1
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• pp.23-27
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• 2005

The crystallographic and magnetic properties of a series of substitutions in nickel ferrite where the Fe³⁺ is replaced with In³⁺ have been investigated using X-ray diffraction (XRD) and Mössbauer spectroscopy. Information on the exact crystalline structure, lattice parameters, bond lengths and bond angles were obtained by refining their XRD profiles by a Rietveld method. All the crystal structures were found to be cubic with the space group Fd/3m. The lattice constants increased with In³⁺ concentration. The expansion of the tetrahedron was outstanding, indicative of the tetrahedral (A) site preference of larger indium ion. The Mossbauer spectra showed two sets of sextuplet originating from ferric ions occupying the tetrahedral sites and the octahedral (B) sites under the Neel temperature T_N. Regardless of the composition x, the electric quadrupole splitting was zero within the experimental error. At x = 0.2, the magnetic hyperfine fields increased slightly, which meant that the nonmagnetic indium ions occupied preferentially the A-site. At the same time, the intensity of the B-site sub-spectra decreased markedly at the elevated temperature, indicating that the occupation of the A site by indium induced a considerable perturbation on the B site.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10a
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• pp.857-862
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• 1987

Given a network with k specified vertices bi called centers, a cardinality constrained cover is a family {Bi} of k subsets covering the vertex set of a network, such that each subset Bi corresponds to and contains center bi, and satisfies a given cardinality constraint. A set of cardinality constrained overlapping territories is a cardinality constrained cover such that the total sum of T(B$_{i}$) for all subsets is minimum among all cardinality constrained covers, where T(B$_{i}$) is the summation of the shortest path lengths from center bi to every vertex in B$_{I}$. This paper considers a problem of finding a set of cardinality constrained overlapping territories. and proposes an algorithm for the Problem which has the time and space complexities are O(k$^{3}$$\mid$V$\mid$$^{2}$) and O(k$\mid$V$\mid$+$\mid$E$\mid$), respectively, where V and E are the sets of vertices and edges of a given network, respectively. The concept of overlapping territories has a possibility to be applied to a job assignment problem.oblem.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.8
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• pp.695-703
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• 2005

The objective of this study is to determine the effective thermal conductivity and thermal resistance values in test boreholes with three different fill materials. To evaluate these heat transfer properties, in-situ tests on four vertical boreholes were conducted by adding a monitored amount of heat to water over various test lengths. Two parameter estimation models, line-source and numerical one-dimensional models, for evaluation of thermal response test data were compared when applied on the same four data sets. Results show that the average thermal conductivity deviation between measured data and these two models is in the range of $3.03\%$ to $4.45\%$. The effect of increasing grout thermal conductivity from 1.34 to 1.82 $W/m^{\circ}C$ resulted in overall increases in effective formation thermal conductivity by $11.1\%$ to $51.9\%$ and reductions in borehole thermal resistance by $11.6\%$ to $26.1\%$.

• Journal of the Korean Chemical Society
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• v.62 no.5
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• pp.358-363
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• 2018

The purpose of this study is to show the possibility of using Cu catalyst in removal of $NO_x$ from automobile exhaust which is regarded as the primary source of fine dust PM2.5. The energy and the bond lengths of the three possible structures of Cu-NO complex, which is formed by binding NO molecule to Cu, and the changes in IR and Raman spectra are calculated using MPW1PW91 method on the level of 6-311(+)G(d,p) of basis sets with Gaussian 09 program. As a result, the enthalpy of formation of the Cu-NO complexes are obtained as ${\Delta}H=104.89$, 91.98, -127.48 kJ/mol for the linear, bent, and bridging forms of them, respectively. And the bond lengths between N and O in NO complexes, which becomes longer than NO molecule, indicates that O is easily reduced from Cu-NO. In addition, the Cu-NO complexes using Cu catalyst can be easily measured by infrared or Raman spectroscopy because in the IR and Raman spectra of the NO and Cu-NO complexes the positon and the intensity of bands are definitely different in each vibration mode.

• Journal of Korea Spatial Information System Society
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• v.11 no.1
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• pp.127-136
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• 2009

This paper proposes an on-line mining algorithm of moving trajectory patterns in RFID data streams considering changing characteristics over time and constraints of single-pass data scan. Since RFID, sensor, and mobile network technology have been rapidly developed, many researchers have been recently focused on the study of real-time data gathering from real-world and mining the useful patterns from them. Previous researches for sequential patterns or moving trajectory patterns based on stream data have an extremely time-consum ing problem because of multi-pass database scan and tree traversal, and they also did not consider the time-changing characteristics of stream data. The proposed method preserves the sequential strength of 2-lengths frequent patterns in binary relationship table using the time-evolving graph to exactly reflect changes of RFID data stream from time to time. In addition, in order to solve the problem of the repetitive data scans, the proposed algorithm infers candidate k-lengths moving trajectory patterns beforehand at a time point t, and then extracts the patterns after screening the candidate patterns by only one-pass at a time point t+1. Through the experiment, the proposed method shows the superior performance in respect of time and space complexity than the Apriori-like method according as the reduction ratio of candidate sets is about 7 percent.

• Tunnel and Underground Space
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• v.30 no.3
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• pp.226-241
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• 2020

The stability of underground mine cavity is closely related with pillar strength. The vulnerability of pillars can be judged and reinforced if the pillar strength is known. The pillar strength is affected by characteristics of discontinuities and shape of a pillar. The change of pillar strength due to a discontinuity passing through the center of a pillar, width-to-height ratio of a pillar and small joints existing within a pillar was analyzed using PFC 3D. The result showed that the pillar strength is influenced by dip angle of a discontinuity and it increases as width-to-height ratio of a pillar increases. The pillar strength decreases as the number of contained joints increases. The relationship between total trace length observable from the pillar surface and the pillar strength was regressed with exponential function. The correlation coefficient of the regression was high enough so that pillar strength can be predicted using total trace length if a joint set exists in a pillar. Lastly, the method to estimate the strength of a pillar that includes two joint sets was proposed if the joint dip angles are 60°, 30°. The method also need total trace lengths of two joint sets.

• Human Ecology Research
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• v.52 no.1
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• pp.55-62
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• 2014

The purpose of this study is to identify changes in the sleeve patterns of women's jackets from the end of the 19th century to the early 20th century. To meet this purpose, we analyzed nine sets of historic sleeve patterns. The experimental sleeve patterns were selected from the English costume source books that provided women's costume patterns from the 1890s and 1900s. These experimental sleeve patterns were drafted on the basis of the directions given in the source books. The sleeve lengths, widths, and angles of each sleeve pattern were measured. The results of this study showed that the silhouette of the two-piece sleeves of women's jackets in the 1890s had a tight fit; further, they had a sharper elbow curve than that of 1900s' sleeves. The sleeves of the 1890s' women's jackets were 6-11 cm shorter or narrower than the sleeves of the 1900s' jackets. The under-sleeve inseam angle of the 1890s' sleeve was greater than that of the 1900s' sleeve. The outseam angle of the upper sleeve was greater than the under-sleeve angle of the 1900s' sleeve pattern. The elbow curve of the women's jacket sleeve pattern appeared to be a sluggish silhouette. This change happened as the outseam angle of the under sleeve was reduced. This shows that the elbow curve silhouette of the women's jacket sleeves of the 1890s and 1900s has controlled the change in the under-sleeve outseam angle.

• Imaging Science in Dentistry
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• v.44 no.2
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• pp.121-128
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• 2014

Purpose: The present study was performed to compare the planning of implant placement based on panoramic radiography (PAN) and cone-beam computed tomography (CBCT) images, and to study the impact of the image dataset on the treatment planning. Materials and Methods: One hundred five partially edentulous patients (77 males, 28 females, mean age: 46 years, range: 26-67 years) seeking oral implant rehabilitation were referred for presurgical imaging. Imaging consisted of PAN and CBCT imaging. Four observers planned implant treatment based on the two-dimensional (2D) image data-sets and at least one month later on the three-dimensional (3D) image dataset. Apart from presurgical diagnostic and dimensional measurement tasks, the observers needed to indicate the surgical confidence levels and assess the image quality in relation to the presurgical needs. Results: All observers confirmed that both imaging modalities (PAN and CBCT) gave similar values when planning implant diameter. Also, the results showed no differences between both imaging modalities for the length of implants with an anterior location. However, significant differences were found in the length of implants with a posterior location. For implant dimensions, longer lengths of the implants were planned with PAN, as confirmed by two observers. CBCT provided images with improved scores for subjective image quality and surgical confidence levels. Conclusion: Within the limitations of this study, there was a trend toward PAN-based preoperative planning of implant placement leading towards the use of longer implants within the posterior jaw bone.

• Geomechanics and Engineering
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• v.20 no.3
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• pp.191-205
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• 2020

Soil shear strength parameters play a remarkable role in designing geotechnical structures such as retaining wall and dam. This study puts an effort to propose two accurate and practical predictive models of soil shear strength parameters via hybrid artificial neural network (ANN)-based models namely genetic algorithm (GA)-ANN and particle swarm optimization (PSO)-ANN. To reach the aim of this study, a series of consolidated undrained Triaxial tests were conducted to survey inherent strength increase due to addition of polypropylene fibers to sandy soil. Fiber material with different lengths and percentages were considered to be mixed with sandy soil to evaluate cohesion (as one of shear strength parameter) values. The obtained results from laboratory tests showed that fiber percentage, fiber length, deviator stress and pore water pressure have a significant impact on cohesion values and due to that, these parameters were selected as model inputs. Many GA-ANN and PSO-ANN models were constructed based on the most effective parameters of these models. Based on the simulation results and the computed indices' values, it is observed that the developed GA-ANN model with training and testing coefficient of determination values of 0.957 and 0.950, respectively, performs better than the proposed PSO-ANN model giving coefficient of determination values of 0.938 and 0.943 for training and testing sets, respectively. Therefore, GA-ANN can provide a new applicable model to effectively predict cohesion of fiber-reinforced sandy soil.