• The Transactions of the Korea Information Processing Society
• /
• 제5권5호
• /
• pp.1204-1215
• /
• 1998

In this paper, we propose a scenario representing method, a specification language, and a verification technique for OARTS(Object based Approach for Real-Time Systems). As well as the general modeling method(event trace diagram), this study includes a specification language and a verification technique because there was no study about methodological level technique for scenario development as yet. Centering around the synchronization problem of transition of external modules which are the communication interfaces based on the objects, we lay stress on the representation of sequence of external events and internal action transitions. From the results of practical experiences, it has been ascertained that the proposed method reflect well the requirements in the analysis step, and its validity of the representation has been identified by a conceptual verifier. We support that it can serve as an analyzing tool for representing a general real-time scenarios also.

• Journal of Power Electronics
• /
• 제13권4호
• /
• pp.592-599
• /
• 2013

This paper investigates a new isolated single-phase AC-DC converter, which integrates a modified AC-DC buck-boost converter with a DC-DC forward converter. The front semi-stage is operated in discontinuous conduction mode (DCM) to achieve an almost unity power factor and a low total harmonic distortion of the input current. The rear semi-stage is used for step-down voltage conversion and electrical isolation. The front semi-stage uses a coupled inductor with the same winding-turn in the primary and secondary sides, which is charged in series during the switch-on period and is discharged in parallel during the switch-off period. The discharging time can be shortened. In other words, the duty ratio can be extended. This semi-stage can be operated in a larger duty-ratio range than the conventional AC-DC buck-boost converter for DCM operation. Therefore, the proposed converter is suitable for universal input voltage (90~264 $V_{rms}$) and a wide output-power range. Moreover, the voltage stress on the DC-link capacitor is low. Finally, a prototype circuit is implemented to verify the performance of the proposed converter.

• Environmental Engineering Research
• /
• 제14권2호
• /
• pp.120-125
• /
• 2009

Water stress has become a major concern in agriculture. Korea suffers from limited agricultural water supply, and wastewater reuse has been recommended as an alternative solution.A study was performed to examine the effects of microorganism concentration in the ponded-water of a paddy rice field with reclaimed-water irrigation for evaluating the microbial risk to farmers and neighborhoodchildren.Most epidemiological studies were performed based on an upland field, and they may not directly applicable to paddy fields. Beta-Poisson model was used to estimate the microbial risk of pathogen ingestion. Their risk value increased significantly high level after irrigation and precipitation.It implies that agricultural activities such as plowing, and fertilizing, and precipitation need be practiced a few days after irrigation considering health risks. The results about field application of the microbial risk assessment using E. coli showed difference according to monitoring time and treatment plot. Result of the microbial risk assessment showed that risk values of ground-water and reclaimed secondary waste water irrigation were lower than directly use of wastewater treatment plants' effluent. This paper should be viewed as a first step in the application of quantitative microbial risk assessment of E. coli to wastewater reuse in a paddy rice farming.

• Journal of the Korean Society of Clothing and Textiles
• /
• 제41권3호
• /
• pp.556-574
• /
• 2017

This study explored the appearance management experiences of breast cancer patients undergoing mastectomy. For data collection, one-on-one interviews were held with 18 Korean females diagnosed with breast cancer from the first stage to the third stage from 2008 to 2015. The data was analyzed through a three-step analysis of grounded theory. QSR NVivo 11.0 for Mac was applied in order to avoid biased results according to the subjective viewpoint of researchers. From open coding results, six paradigms and 15 categories were drawn. The results of axial coding showed that the psychological changes category was the central phenomenon. Additionally, three categories (skin changes, scalp/hair changes, and general reactions) were found to be causal conditions, and five paradigms (clothing behavior, skin care behavior, makeup behavior, scalp/hair-care behavior, and shopping behavior) were found to be action/interaction strategies. Last, selective coding integrated fragmented qualitative data through open coding and axial coding in order to derive explanatory narratives. A comprehensive examination of the appearance management behaviors of breast cancer patients suffering from extreme stress due to physical/psychological changes enables this study to provide a foundation for related studies to be activated in the clothing and textiles discipline.

• Transactions of Materials Processing
• /
• 제11권5호
• /
• pp.447-456
• /
• 2002

A study has been made to investigate the boundary sliding and its accommodation mode with respect to the variation of $\alpha$$_2$/$eta$ volume fraction during superplastic deformation of two-phase Ti$_3$Al-xNb intermetallics. Step strain rate and load relaxation tests have been performed at 950, 970 and 99$0^{\circ}C$ to obtain the flow stress curves and to analyze the deformation characteristics by the theory of inelastic deformation. The results show that the grain matrix deformation and boundary sliding of the three intermetallics containing 21, 50 and 77% in $eta$ volume fractions are well described by the plastic deformation and viscous flow equations. Due to the equal accommodation of both $a^2$ and $\beta$ phases, the accommodation modes for fine-grained materials are in good agreement with the iso-strain rate models. The sliding resistance analyzed for the different boundaries is the lowest in the $\alpha$$_2$/$\alpha$$_2$ boundary, and increases in the order of $\alpha$$_2$/$\alpha$$_2$<< $\alpha$$_2$/$\beta$ = $\beta$/$\beta$, which plays an important role in controlling the superplasticity of the alloys with the various $\alpha$$_2$/$\beta$ phase ratio.

• Journal of the Korean Society for Precision Engineering
• /
• 제26권10호
• /
• pp.89-96
• /
• 2009

In recent years, there has been a considerable interest in the application of super plastic forming in the aircraft and automotive industries. This requires a detailed design of the technological process in order to exploit its peculiar potentialities better. Nowadays, the finite element method is used to plan the sheet metal forming processes whose simulation requires determination of material constants for super plastic materials. The present work is aimed to show a simple method to characterize super plastic materials duplex stainless steel which was formed by a constant gaspressure to hemispheres with and without back pressure. The forming operation was performed using an in-house designed and built biaxial forming apparatus. The temporal change of dome heights of hemispheres were measured for applying the pressures. The flow stresses and strain rates developed at the top of the dome during the forming step were shown to follow closely the flow stress - strain rate relationship obtained from the strain rate change tests performed at the same temperature.

• Journal of Korean Society for Quality Management
• /
• 제35권3호
• /
• pp.107-117
• /
• 2007

The fatigue has been considered the most failure mode of metal, ceramic, and composite materials. In this paper, numerical experiments to asses the usefulness of two Dixon's methods(small and large samples) and 14 S-N methods on assumptions of lognormal fatigue limit distribution under RFL(Random Fatigue Limit) model are conducted for staircase(or up-and-down) test and compared by MSE(Mean Squared Error) and bias for estimates of mean log-fatigue limit. Also, guidelines for staircase test plans to choose initial stress level and step size are recommended from numerical experiments including sensitivity analyses. In addition, the parametric bootstrap method to construct a confidence interval for the mean of log-fatigue limit by the percentile method using a transition probability matrix of Markov chain is presented and illustrated with an example.

• Biomolecules & Therapeutics
• /
• 제22권3호
• /
• pp.232-238
• /
• 2014

Alzheimer's disease (AD) is the most common neurodegenerative disease without known ways to cure. A key neuropathologic manifestation of the disease is extracellular deposition of beta-amyloid peptide (Ab). Specific mechanisms underlying the development of the disease have not yet been fully understood. In this study, we investigated effects of 4-O-methylhonokiol on memory dysfunction in APP/PS1 double transgenic mice. 4-O-methylhonokiol (1 mg/kg for 3 month) significantly reduced deficit in learning and memory of the transgenic mice, as determined by the Morris water maze test and step-through passive avoidance test. Our biochemical analysis suggested that 4-O-methylhonokiol ameliorated $A{\beta}$ accumulation in the cortex and hippocampus via reduction in beta-site APP-cleaving enzyme 1 expression. In addition, 4-O-methylhonokiol attenuated lipid peroxidation and elevated glutathione peroxidase activity in the double transgenic mice brains. Thus, suppressive effects of 4-O-methylhonokiol on $A{\beta}$ generation and oxidative stress in the brains of transgenic mice may be responsible for the enhancement in cognitive function. These results suggest that the natural compound has potential to intervene memory deficit and progressive neurodegeneration in AD patients.

• Journal of Plant Biotechnology
• /
• 제38권2호
• /
• pp.130-136
• /
• 2011

Ions deficiency or excess remains one of the critical ground level environmental problems, affecting crop productivity. In this overview, we will discuss an increased application of proteomics technology in addressing this issue using rice (Oryza sativa L.) as a model crop plant. Proteomics analyses have revealed that rice proteome undergoes changes in the proteins composition and expression in response to several ionic stresses, including mineral nutrients (aluminum, nitrogen, and phosphorous) and heavy metals (arsenic, cadmium, and copper). Developed inventory of responsive proteins and their correlation with changes in physiological symptoms and parameters are a major step forward in: (i) better understanding the underlying mechanisms of ionic stresses-triggered responses in rice; (ii) comparative proteomics studies; and (iii) designing a novel strategy to improve crop plants.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• 제7권4호
• /
• pp.38-43
• /
• 2011

For the efficient and safe operation of nuclear power plant, evaluating quantitatively aging phenomenon of major components is necessary. Especially, typical aging parameters such as stresses and cumulative usage factors should be determined accurately to manage the lifetime of the plant facility. The 3-D finite element(FE) model is generated to calculate the aging parameters. Mechanical and thermal transfer functions called Green's functions are developed for the FE model with standard step input. The stress results estimated from transfer functions are verified by comparing with 3-D FE analyses results. Lastly, we suggest an effective fatigue evaluation methodology by using the transfer functions. The usefulness of the proposed fatigue evaluation methodology can be maximized by combining it with an on-line monitoring system.