• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.4
• /
• pp.362-370
• /
• 2008

In this paper, we propose a 2D-FE model in single impact with combined physical factors to obtain a unique residual stress by shot peening. Applied physical parameters consist of elastic-plastic deformation of shot ball, material damping coefficients, strain rate, dynamic friction coefficients. As a kinematical parameter, there is impact velocity. Single impact FE model consists of 2D axisymmetric elements. The FE model with combined factors showed converged and unique distributions of surface stress, maximum compressive residual stress and deformation depth. Further, in contrast to the FE models with rigid shot and elastic deformable shot, FE model with plastic deformable shot produces residual stresses very close to experimental solutions by X-ray diffraction. We therefore validated the 2D FE model with combined peening factors and plastic deformable shot. This FE model will be a base of the 3D FE model for residual stresses by multi-impact shot peening.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.7
• /
• pp.1920-1926
• /
• 2010

Yoon et $al.^1$ presented an approximate mathmatical model to describe ammonia removal from an experimental batch reactor system with gaseous headspace. The development of the model was initially based on assuming instantaneous equilibrium between ammonia in the aqueous and gas phases. In the model, a "saturation factor, $\beta$" was defined as a constant and used to check whether the equilibrium assumption was appropriate. The authors used the trends established by the estimated $\beta$ values to conclude that the equilibrium assumption was not valid. The authors presented valuable experimental results obtained using a carefully designed system and the model used to analyze the results accounted for the following effects: speciation of ammonia between $NH_3$ and $NH^+_4$ as a function of pH; temperature dependence of the reactions constants; and air flow rate. In this article, an alternative model based on the exact solution of the governing mass-balance differential equations was developed and used to describe ammonia removal without relying on the use of the saturation factor. The modified model was also extended to mathematically describe the pH dependence of the ammonia removal rate, in addition to accounting for the speciation of ammonia, temperature dependence of reactions constants, and air flow rate. The modified model was used to extend the analysis of the original experimental data presented by Yoon et $al.^1$ and the results matched the theory in an excellent manner.

• Current Optics and Photonics
• /
• v.7 no.4
• /
• pp.449-456
• /
• 2023

The localized surface-plasmon resonance has drawn great attention, due to its unique optical properties. In this work a general theoretical description of the dipole mode is proposed, using the forced damped harmonic oscillator model of free charges in an ellipsoid. The restoring force and driving force are derived in the quasistatic approximation under general conditions. In this model, metal is regarded as composed of free charges and bound charges. The bound charges form the dielectric background which has a dielectric function. Those free charges undergo a collective motion in the dielectric background under the driving force. The response of free charges will not be included in the dielectric function like the Drude model. The extinction and scattering cross sections as well as the damping coefficient from our model are verified to be consistent with those based on the Drude model. We introduce size effects and modify the restoring and driving forces by adding the dynamic depolarization factor and the radiation damping term to the depolarization factor. This model provides an intuitive physical picture as well as a simple theoretical description of the dipole mode of the localized surface-plasmon resonance based on free-charge collective motion.

• Journal of the Korea Safety Management & Science
• /
• v.15 no.4
• /
• pp.209-216
• /
• 2013

By means of the model competition, this research analyzed the factor of patient management, the factor of policy support, and the factor of medical treatment system. Concretely, the factor of policy support forms a positive effects on the factor of medical treatment system. Practically, well-established healthcare policy provide and facilitate the effective medical treatment system. of the hospital. And, in the effective medical treatment system, hospitals try to develop the patient management of the chronic disease. From the empirical research, this paper concluded that the factor of medical treatment system. mediated by the factor of policy support. Also, the factor of medical treatment system promotes the development of patient management in the chronic disease.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.23 no.3
• /
• pp.217-223
• /
• 2017

In order to assess risk as a basic step for securing safety, it requires to select risk factors and determine the frequency and the severity of the consequence of each risk factor. This research adopted common risk factors among well-known maritime risk assessment models, and proposed objective criteria to gauge the risk level of each risk factor. The starting points of risk evolution were chosen for criteria according to related studies and seafarers' experience. The rate of risk appearance over the criteria is named as the incidence of risk factor. Therefore, the total risk level is expressed as the combination of incidence of each risk factor and severity. This quantitative method would be applied to measuring and comparing the risk level of target maritime zones, and it would also be useful to survey which risk factor be focused for reducing the total risk of a certain maritime zone.

• 유체기계공업학회:학술대회논문집
• /
• 2002.12a
• /
• pp.465-470
• /
• 2002

For measuring friction-factor of artificially-roughened surfaces which are usually applied on damper seals, flat plate test apparatus is designed and fabricated. the measurement of leakage and pressure distribution through round-hole pattern specimen with different hole area is described and a method is discussed for determining the friction-factor experimentally. Results show that the friction-factor of the round-hole pattern surfaces is bigger than that of smooth surface and increases as increasing the hole area. A empirical friction factor model for round-hole pattern surface is defined as the Moody's friction factor formula.

• Journal of the Korean Data and Information Science Society
• /
• v.19 no.3
• /
• pp.751-759
• /
• 2008

Mixtures of factor analyzers(MFA) is useful to model the distribution of high-dimensional data on much lower dimensional space where the number of observations is very large relative to their dimension. Mixtures of common factor analyzers(MCFA) can reduce further the number of parameters in the specification of the component covariance matrices as the number of classes is not small. Moreover, the factor scores of MCFA can be displayed in low-dimensional space to distinguish the groups. We propose the factor scores of MCFA as new low-dimensional features for classification of high-dimensional data. Compared with the conventional dimension reduction methods such as principal component analysis(PCA) and canonical covariates(CV), the proposed factor score was shown to have higher correct classification rates for three real data sets when it was used in parametric and nonparametric classifiers.

• The KSFM Journal of Fluid Machinery
• /
• v.6 no.3 s.20
• /
• pp.15-20
• /
• 2003

For measuring friction factor of artificially-roughened surfaces which are usually applied to damper seals, flat plate test apparatus is designed and fabricated. The measurements of leakage flow and pressure distribution through round-hole patterned specimen with different hole areas are described, and a method is discussed for determining the friction factor experimentally. Results show that the friction factor of the round-hole patterned surface is bigger than that of smooth surface, and increases as increasing the hole area. A empirical friction factor model for the round-hole patterned surface can be descrived by the Moody's friction factor formula.

• Journal of Korean Academy of Nursing
• /
• v.43 no.4
• /
• pp.568-578
• /
• 2013

Purpose: The purpose of this study was to evaluate the reliability and validity of the Korean version of the Successful Aging Inventory (SAI-K) to determine its suitability for use with older Korean adults. Methods: Exploratory and confirmatory factor analyses were utilized to assess the factor structure and the construct validity of the SAI-K. First- and second-order Confirmatory Factor Analysis (CFA) were conducted to identify the most adequate model. Cronbach's alpha was used to test the reliability. Results: Using a second-order CFA, a four-factor structure was validated (${\chi}^2$=122.82, p<.001, GFI=.92, AGFI=.88, SRMR=.06 RMSEA=.07, 90% CI=.05-.09, CFI=.93). The four-factor SAI-K showed reliable internal consistency with a Cronbach's alpha for the total scale of .86. Conclusion: The four-factor, 13-item SAI-K showed satisfactory reliability and validity and, thus, has the potential to be an appropriate instrument for measuring successful aging in older Korean adults.

• Journal of Industrial Convergence
• /
• v.1 no.2
• /
• pp.107-124
• /
• 2003

With rapid growth and competition of electronic commerce through internet, various buying types and business models are being appeared. In this paper, we studied group buying which is new business model to consumer and factors affecting on trust and participation of group buying. The followings are the regression result of this study. First, familiarity factor, customer service factor, seal of security and product value factor made a significant effect on trust. Second, familiarity factor, perceived reputation factor, customer service factor, seal of security and product value factor made a significant effect on participation of group buying. Third, trust of group buying made a significant effect on participation of group buying. In this study, modeling and empirical test were implemented about structure of trust and participation of group buying. We can know where our group buying strategies should focus and which factor we should improve.