• Journal of radiological science and technology
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• v.33 no.1
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• pp.45-50
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• 2010

In this study, we compared the clinical usefulness of SPAIR (Spectral Adiabatic Inversion Recovery) and STIR (Short TI Inversion Recovery) to evaluate the fat tissues precisely. The images of brain axial (n = 20), lumber spine sagittal (n = 20), hip joint coronal (n = 17) and knee joint (n = 25) were obtained by turbo spin echo T2 weighted method on 3T magnetic resonance image. The signal intensity (SI) values were measured using region of interest in fat, muscle tissue, and background noise. The inhomogeneity values were measured using the standard deviation (SD) value divided by the mean values. SD signifies the amount of error which is similar to the imaging heterogeneity. In brain axial images, the SPAIR showed more superior SI and inhomogeneity results than the STIR. In spine, hip and knee images, STIR showed more excellent SI results, but poor inhomogeneity than the SPAIR.

• Journal of Korean Society of Steel Construction
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• v.22 no.3
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• pp.241-251
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• 2010

This paper presents the development of a new analytical solution to the governing differential equation for isotropic annular sector plates subjected to uniform loading in a three-dimensional polar coordinate system. The 4th order governing partial differential equation (PDE) was converted to an ordinary differential equation (ODE) by assuming the Levy-type series solution form and the subsequent mathematical operations. Finally, a series-type solution was assembled with homogeneous and nonhomogeneous solution parts after operating real values and complex conjugates derived from the characteristic equation. To demonstrate the convergence rate and the accuracy of the featured method, several examples with various sector angles were selected and solved. The deflections and internal moments in the example annular sector plates that were obtained from the proposed solution were compared with those obtained from other analytical studies and numerical analyses using the finite element analysis package program, ABAQUS. Very good agreement with the results of other analytical and numerical methodologies was shown.

• Journal of the Korean Society of Tobacco Science
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• v.20 no.2
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• pp.191-197
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• 1998

Discriminant analysis using near infrared spectra derived from Korean Flue-cured(KF) and American Flue-cured(AF), and also Korean Burley(KB) and American Burley(AB) tobacco was done to classify flue-cured and burley tobacco as either grown in Korea or grown in the USA. Samples were scanned in the wavelength of 400 ～ 2500 nm by near infrared analyzer(NIRSystem Co., model 6500). The discrimination equations for flue-cured and burley tobacco were developed using partial least square 2 method in Infrasoft International NIRS 3 software package. KF samples used for the development of the discrimination equations were higher contents of total sugar, crude ash and chlorine, and higher value of leaf density and brightness, but lower contents of nicotine, total nitrogen and ether extracts, and higher value of redness than those of AF samples. KB samples were higher contents of nicotine, crude ash and chlorine, but lower contents of ether extracts and value of brightness than those of AB samples. On 3 dimensional graph drawn with 3 principal component scores calculated with 3 principal component from KF and KB sample spectra, KF sample spectra were significantly different from AF, and also KB sample spectra were significantly different from AB. The discrimination equations of flue-cured and burley were developed with 3 principal component, respectively. The discrimination equations for flue-cured and burley had a standard error of 0.03 and 0.04, and a R2 of 0.88 and 0.84, respectively. The tobacco samples used for the development of discrimination equation were perfectly classified as KF and AF by flue-cured discrimination equation, and also perfectly classified KB and AB by burley discrimination equation, respectively. The correct classification rates of KF and AF samples not used for the development of discrimination equations were 9S % (828 out of 869 samples) and 98 % (98 out of 100 samples) by flue-cured discrimination equations, and KB and AB samples were 94%(345 out of 368 samples) and 100%(42 out of 42 samples) by burley discrimination equations, respectively.

• Computers and Concrete
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• v.25 no.1
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• pp.67-73
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• 2020

Traditionally used analytical approach to predict the fatigue failure of reinforced concrete (RC) structure is generally conservative and has certain limitations. The nonlinear finite element method (FEM) offers less expensive solution for fatigue analysis with sufficient accuracy. However, the conventional implicit dynamic analysis is very expensive for high level computation. Whereas, an explicit dynamic analysis approach offers a computationally operative modelling to predict true responses of a structural element under periodic loading and might be perfectly matched to accomplish long life fatigue computations. Hence, this study simulates the fatigue behaviour of RC beams with finite element (FE) assemblage presenting a simplified explicit dynamic numerical solution to show computer aided fatigue behaviour of RC beam. A commercial FEM package, ABAQUS has been chosen for this complex modelling. The concrete has been modelled as a 8-node solid element providing competent compression hardening and tension stiffening. The steel reinforcements are simulated as two-node truss elements comprising elasto-plastic stress-strain behaviour. All the possible nonlinearities are duly incorporated. Time domain analysis has been adopted through an automatic Newmark-β time incremental technique. The program consists of twelve RC beams to visualize the real behaviour during fatigue process and to obtain the reliability of the study. Both the numerical and experimental results indicate a redistribution of stresses along the time and damage accumulation of beam which severely affect the serviceability and ultimate capacity of RC beam. The output of the FEM analysis demonstrates good match with the experimental consequences which affirm the efficacy of the computer aided model. The controlled fatigue damage evolution at service fatigue load limits makes the FE model an efficient tool in predicting high cycle fatigue behaviour of RC structures.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.11
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• pp.1071-1077
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• 2012

Low frequency noises(up to about 200 Hz) such as booming are mainly caused by particular modes, and in general the solutions may be found based on mode controls where conventional methods such as FEM can be used. However, at higher frequencies between 0.3~1 kHz, as the number of modes rapidly increases, radiation characteristics from structures, performances of damping sheets and sound packages may be more crucial rather than particular modes, and consequently the conventional FEM may be less practical in dealing with this kinds of structure-borne problems. In this context, so-called 'mid-frequency simulation model' based on FE-SEA hybrid method is studied and validated to reduce noise in this frequency region. Energy transmission loss(i.e. air borne noise) is also studied. A dash panel component is chosen for this study, which is an important path that transmits both structure-borne and air borne energies into the cavity. Design modifications including structural modifications, attachment of damping sheets and application of different sound packages are taken into account and the corresponding noise characteristics are experimentally identified. It is found that the dash member behaves as a noise path. The damping sheet and sound packages have similar influences on both sound radiation and transmission loss. The comparison between experiments and simulations shows that this model could be used to predict the tendency of noise improvement.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.225-225
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• 2011

The dielectric and optical properties of GaInZnO (GIZO), HfInZnO (HIZO) and InZnO (IZO) thin films on glass by RF magnetron sputtering method were investiged using reflection electron energy loss spectroscopy (REELS). The band gap was estimated from the onset values of REELS spectra. The band gaps of GIZO, HIZO and IZO thin films are 3.1 eV, 3.5 eV and 3.0 eV, respectively, Hf and Ga incorporated into IZO results in an increase in the energy band gap of IZO by 0.5 eV and 0.1 eV. The dielectric functions were determined by comparing the effective cross section determined from experimental REELS with a rigorous model calculation based on the dielectric response theory, using available software package, good agreement between the experimental and fitting results gives confidence in the accuracy of the determined dielectric function. The main peak of Energy Loss Function (ELF) obtained from IZO shows at 18.42 eV, which shifted to 19.43 eV and 18.15 eV for GIZO and HIZO respectively, because indicates the corporation of cation Ga and Hf in the composition. The optical properties represented by the dielectric function e, the refractive index n, the extinction coefficient k, and the transmission coefficient, T of HIZO and IZO thin films were determined from a quantitative analysis of REELS. The transmission coefficient was increased to 93% and decreased to 87% in the visible region with the incorporation of Hf and Ga in the IZO compound.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.158-158
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• 2012

A new kind of organic-inorganic hybrid polymer, poly(tetraphenyl)silole siloxane (PSS), was invented and synthesized for realization of its unique charge trap properties. The organic portions consisting of (tetraphenyl)silole rings are responsible for electron trapping owing to their low-lying LUMO, while the Si-O-Si inorganic linkages of high HOMO-LUMO gap provide the intrachain energy barrier for controlling electron transport. Such an alternation of the organic and inorganic moieties in a polymer may give an interesting quantum well electronic structure in a molecule. The PSS thin film was fabricated by spin-coating of the PSS solution in THF organic solvent onto Si-wafer substrates and curing. The electron trapping of the PSS thin films was confirmed by the capacitance-voltage (C-V) measurements performed within the metal-insulator-semiconductor (MIS) device structure. And the quantum well electronic structure of the PSS thin film, which was thought to be the origin of the electron trapping, was investigated by a combination of theoretical and experimental methods: density functional theory (DFT) calculations in Gaussian03 package and spectroscopic techniques such as near edge X-ray absorption fine structure spectroscopy (NEXAFS) and photoemission spectroscopy (PES). The electron trapping properties of the PSS thin film of quantum well structure are closely related to intra- and inter-polymer chain electron transports. Among them, the intra-chain electron transport was theoretically studied using the Atomistix Toolkit (ATK) software based on the non-equilibrium Green's function (NEGF) method in conjunction with the DFT.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.534-538
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• 2003

Final disposal of radioactive waste generated from Nuclear Power Plant (NPP) requires the detailed knowledge of the natures and quantities of radionuclides in waste package. Many of these radionuclides are difficult to measure and expensive to assay. Thus it is suggested to the Indirect method by which the concentrations of DTM (Difficult-to-Measure) nuclide is decided using the relation of concentrations (Scaling Factor) between Key (Easy-to-Measure) nuclide and DTM nuclide with measured concentrations of Key nuclide. In general, scaling factor is determined by using of log mean average (LMA) and regression. These methods are adequate to apply most corrosion product nuclides. But in case of fission product nuclides and some corrosion product nuclides, the predicted values aren't well matched with the original values. In this study, the models using artificial neural network (ANN) for C-14 and Sr-90 are compared with those using LMA and regression. The assessment of models is executed in the two parts divided by a training part and a validation part. For all of two nuclides in the training part, the predicted values using ANN are well matched with the measured values compared with those using LMA and regression. In the validation part, the accuracy of the predicted values using ANN is better than that using LMA and is similar to or better than that using regression. It is concluded that the predicted values using ANN model are better than those using conventional model in some nuclides and ANN model can be used as the complement of LMA and regression model.

• Journal of Engineering Education Research
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• v.5 no.2
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• pp.22-35
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• 2002

The main purpose of this study is to prepare an outline for developing the Contents Systems that achieve self-study systems to make the students adopt themselves into new study atmosphere and maximize the result of study on technical college in Electric-Electronic field. Questionnaire posed to analyze the demand of teaching materials to the students, and professors and also to find characteristics of students in technical college. The SPSSWIN/PC+ statistics Package was used to assay the collected answers. And simple frequency with percentage, average, and standard deviation were calculated to check the entire trend and actual state of each question. The primary outcomes of this study are as follows i) The students in the technical college prefer self-directed learning to lecturer-oriented teaching. ii) It is difficult to offer the technical college students normal education systems since the students?interest and motivation towards study are very low. iii) The lack of capability of foreign language and basic mathematics are considered as obstacles for many students technical college to study. iv) The professors in technical college still depend on traditional method to teach the students without organized research of the intellectual levels and attitude the students. v) Teaching materials in currently use are not appropriated to induce the motivation and interest of study from the students. Also, the teaching materials in use now were discovered not to have enough originality, practical application, andwere text based. Therefore, the improvement of the existing teaching materials was demanded while the fundamental ability to study of general students is declining. Consequently, it is necessary to introduce new teaching materials which are simple, easy, and organized to offer the studen ts study desire and interest.

• Journal of Fashion Business
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• v.10 no.3
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• pp.31-43
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• 2006

The purpose of this study is to investigate the changes of modern Korean men's fashion from the 1960s to the 1990s by reviewing fashion magazine advertisements and pictorials. For theoretical study, the characteristics and the importance of apparel advertisements and the changes of modern Korean men's fashion trend were reviewed. On the basis of the theoretical investigation, this study analyzed 932 pictorials from Joongang Magazine, Shin Dong-A, Bokjangwolbo, Meot, Men's Life, WWD, and S.F.F.A's photograph album, published from 1962 to 1998. Content analysis method was used to analyze the content of magazines and pictorials. The 932 samples are classified into apparel types, silhouette, pattern, color, type of breasts, shape of collar, number of button, type of inner wear. Frequency and $x^2$-test were conducted using a SAS statistics package to analyse the data. The results were as follows. The two-piece style prevailed in men's wear during the 60s, 70s, and 90s, while separate style prevailed during the 80s. H silhouette was the most popular during the 60s, 70s and 90s, however, X silhouette dominated the 70s. For patterns, solids were most frequently used throughout the whole 4 decades. In colors, gray was most frequently used during the 60s, and multi color was most frequently used during the 70s, 80s, and 90s. Throughout the whole decades, single breast, tailored collar, two buttons, and dress shirts were the most prevalent styles.