• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.29 no.6
• /
• pp.529-538
• /
• 2016

The simplified plate theory is presented for static and free vibration analysis of power-law(P) and sigmoid(S) Functionally Graded Materials(FGM) plates. This theory considers the parabolic distribution of the transverse shear stress, and satisfies the condition that requires the transverse shear stress to be zero on the upper and lower surfaces of the plate, without the shear correction factor. The simplified plate theory uses only four unknown variables and shares strong similarities with classical plate theory(CPT) in many aspects such as stress-resultant expressions, equation of motion and boundary conditions. The material properties of the plate are assumed to vary according to the power-law and sigmoid distributions of the volume fractions of the constituents. The Hamilton's principle is used to derive the equations of motion and Winkler-Pasternak elastic foundation model is employed. The results of static and dynamic responses for a simply supported FGM plate are calculated and a comparative analysis is carried out. The results of the comparative analysis with the solutions of references show relevant and accurate results for static and free vibration problems of FGM plates. Analytical solutions for the static and free vibration problems are presented so as to reveal the effects of the power law index, elastic foundation parameter, and side-to-thickness ratio.

• Nuclear Medicine and Molecular Imaging
• /
• v.40 no.6
• /
• pp.327-331
• /
• 2006

Purpose: Aspiration scintigraphy is a procedure of nuclear imaging to evaluate aspiration and of quantifying the amount of aspirate. The ultimate goal of our study is to define the correlation between aspiration and aspiration pneumonia by aspiration scintigraphy and this is a preliminary report of its trial. Materials and methods: Ten patients with positive findings by videofluoroscopy were selected. The patients ingested semi-solid food containing Tc-99m tin colloid 92.5 MBq (2.5 mCi) and images were acquired immediately after the ingestion and 3 hrs later. A fraction of aspiration to the ingested was calculated using an equation with a decay correction. Results: Five patients were interpreted positive by aspiration scintigraphy. Four patients were positive at initial images and the fractions of aspiration were 0.11%, 0.11%, 0.81%, and 0.11%. The one patient who was shown aspirated at both images had initial 5.82% and delayed 2.26%. Conclusion: Aspiration scintigraphy enables us to localize the aspiration at any desired time of the test and to quantify its amount. Follow-up studies are warranted.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.34 no.6
• /
• pp.177-187
• /
• 2022

This study estimates the design wave in the event of a typhoon attack at Busan new port using the wind field, the revised shallow water design wave estimation method proposed by the Ministry of Oceans and Fisheries in 2020, and proposed a reliable method of calculating the shallow water design through verification with the wave observation data. As a result of estimating typhoon wave using the wind field and SWAN numerical model, which are commonly used in the field work, for typhoon that affected Busan new port, it was found that reproducibility was not good except typhoons KONG-REY(1825) and MAYSAK(2009). In particular, in the case of typhoon MAEMI(0314), which had the greatest impact on Busan new port, the maximum significant wave height was estimated to be about 35.0% smaller than that of the observed wave data. Therefore, a plan to improve the reproducibility of typhoon wave was reviewed by applying the method of correcting the wind field and the method of using the Boussinesq equation numerical model, respectively. As a result of the review, it was found that the reproducibility of the wind field was not good as before when the wind field correction. However as a method of linking wind field data, SWAN model results, and Boussinesq numerical model, typhoon wave was estimated during typhoon MAEMI(0314), and the maximum significant wave was similar to the wave observations, so it was reviewed to have good reproducibility.

• Korean Journal of Culture and Social Issue
• /
• v.24 no.1
• /
• pp.49-62
• /
• 2018

The purpose of this study is to examine the effect of distress tolerance on subjective well-being and the mediating effect of experiential avoidance in the relationship between distress tolerance and subjective well-being. We conducted an online survey a total of 285 normal adults in the nation from October 21 to 24, 2015. The questionnaire was composed of a distress intolerance index, a concise measure of subjective well-being, and acceptance action questionnaire. And questionnaires were distributed and retrived by an online survey company. Collected data has been analyzed by the structural equation modeling. The correlation analysis showed that distress tolerance was positively correlated with subjective well-being, while negatively with experiential avoidance. Also, the verification of mediating effects of experiential avoidance in the relation between distress tolerance and subjective well-being indicated that experiential avoidance partly mediated the relationship at a meaningful level. Additionally, deflection correction bootstrap analysis was used to verify indirect effects and its results revealed that the mediating effect going from distress tolerance to subjective well-being passing through experiential avoidance was statistically significant. That is, distress tolerance not only influences subjective well-being directly but also influences indirectly through experiential avoidance. Finally, significance and limitations of this study were discussed along with the suggestions for further research.

• Journal of Wetlands Research
• /
• v.21 no.spc
• /
• pp.39-50
• /
• 2019

This study aims to assess the influence of climate change on the hydrological cycle at a basin level in North Korea. The selected model for this study is MRI-CGCM 3, the one used for the Coupled Model Intercomparison Project Phase 5 (CMIP5). Moreover, this study adopted the Spatial Disaggregation-Quantile Delta Mapping (SDQDM), which is one of the stochastic downscaling techniques, to conduct the bias correction for climate change scenarios. The comparison between the preapplication and postapplication of the SDQDM supported the study's review on the technique's validity. In addition, as this study determined the influence of climate change on the hydrological cycle, it also observed the runoff in North Korea. In predicting such influence, parameters of a runoff model used for the analysis should be optimized. However, North Korea is classified as an ungauged region for its political characteristics, and it was difficult to collect the country's runoff observation data. Hence, the study selected 16 basins with secured high-quality runoff data, and the M-RAT model's optimized parameters were calculated. The study also analyzed the correlation among variables for basin characteristics to consider multicollinearity. Then, based on a phased regression analysis, the study developed an equation to calculate parameters for ungauged basin areas. To verify the equation, the study assumed the Osipcheon River, Namdaecheon Stream, Yongdang Reservoir, and Yonggang Stream as ungauged basin areas and conducted cross-validation. As a result, for all the four basin areas, high efficiency was confirmed with the efficiency coefficients of 0.8 or higher. The study used climate change scenarios and parameters of the estimated runoff model to assess the changes in hydrological cycle processes at a basin level from climate change in the Amnokgang River of North Korea. The results showed that climate change would lead to an increase in precipitation, and the corresponding rise in temperature is predicted to cause elevating evapotranspiration. However, it was found that the storage capacity in the basin decreased. The result of the analysis on flow duration indicated a decrease in flow on the 95th day; an increase in the drought flow during the periods of Future 1 and Future 2; and an increase in both flows for the period of Future 3.

• The Korean Journal of Nuclear Medicine
• /
• v.35 no.6
• /
• pp.378-388
• /
• 2001

Purpose: In this study, we developed a new method for the determination of renal depth with anterior and posterior renal scintigrams in a dual-head gamma camera, considering the attenuation factor $e^{-{\mu}x}$ of the conjugate-view method. Material and Method: We developed abdomen and kidney phantoms to perform experiments using Technetium-99m dimercaptosuccinic acid ($^{99m}Tc$-DMSA). The phantom images were obtained by dual-head gamma camera equipped with low-energy, high-resolution, parallel-hole collimators (ICONf, Siemens). The equation was derived from the linear integration of omission ${\gamma}$-ray considering attenuation from the posterior abdomen to the anterior abdomen phantom surface. The program for measurement was developed by Microsoft Visual C++ 6.0. Results : Renal depths of the phantoms were derived from the derived equations and compared with the exact geometrical values. Differences between the measured and the calculated values were the range of 0.1 to 0.7 cm ($0.029{\pm}0.15cm,\;mean{\pm}S.D.$). Conclusion: The present study showed that the use of the derived equations for renal depth measurements, combined with quantitative planar imaging using dual-head gamma camera, could provide more accurate results for individual variation than the conventional method.

• Economic and Environmental Geology
• /
• v.50 no.6
• /
• pp.537-544
• /
• 2017

Stable carbon isotope ratio of carbon dioxide (${\delta}^{13}C_{CO2}$) is used as an important indicator in the researches for global climate change and carbon capture and sequestration technology. The ${\delta}^{13}C$ value has been usually analyzed with Isotope Ratio Mass Spectrometer (IRMS). Recently, the use of Laser Absorption Spectrometry (LAS) is increasing because of the cost efficiency and field applicability. The purpose of this study was to suggest practical procedures to prepare laboratory reference gases for ${\delta}^{13}C_{CO2}$ analysis using LAS. $CO_2$ gas was adjusted to have the concentrations within the analytical range. Then, the concentration of $CO_2$ was assessed in a lab approved by the Korea Laboratory Accreditation Scheme and the ${\delta}^{13}C_{CO2}$ value was measured by IRMS. When the instrument ran over 12 hours, the ${\delta}^{13}C$ values were drifted up to ${\pm}10$‰ if the concentration of $CO_2$ was shifted up to 1.0% of relative standard deviation. Therefore, periodical investigation of analytical suitability and correction should be conducted. Because ${\delta}^{13}C_{CO2}$ showed the dependency on $CO_2$ concentration, we suggested the equation for calibrating the concentration effect. After calibration, ${\delta}^{13}C_{CO2}$ was well matched with the result of IRMS within ${\pm}0.52$‰.

• Tuberculosis and Respiratory Diseases
• /
• v.44 no.2
• /
• pp.298-308
• /
• 1997

Background : Portable devices for measuring peak expiratory flow(PEF) are now of proved value in the diagnosis and management of asthma and many lightweight PEF meters have become available. However, it is necessary to determine whether peak expiratory flow rate(PEFR) measurements measured with peak flowmeters is accurate and reproducible for clinical application. The aim of the present study is to define accuracy, agreement, and precision of mini-Wright peak flow meter(MPFM) against standard pneumotachygraph. Methods : The lung function tests by standard pneumotachygraph and PEFR measurement by MPFM were performed in a random order for 2 hours in 22 normal and 17 asthmatic subjects and also were performed for 3 successive days in 22 normals. Results : The PEFR measured with MPFM was significantly related to the PEFR and $FEV_1$ measured with standard pneumotachygraph in normal and asthmatics(for PEFR, r = 0.92 ; p < 0.001 ; for $FEV_1$, r = 0.78 ; p < 0.001). The accuracy of MPFM was within 100(limits of accuracy recommeded by NAEP) in all the subjects or 22 normal, mean difference from standard pneumotachygraph being 16.5L/min(percentage of difference being 2.90%) or 10.6L/min(percentage of difference being 1.75%), respectively. According to the method proposed by Bland and Altman, the 95% limits of the distribution of differences between MPFM and standard pneumotachygraph after correction of PEFR using our regression equation were +38.2 and -71.5L/min in all the subjects or 20.49~+9.49L/min in 22 normal and was similar to the intraindividual agreements for 3 successive days in normal. There was no statistically significant difference of PEFR measured with MPFM and standard pneumotachygraph among three days(p > 0.05) and the coefficient of variation($2.4{\pm}1.2%$) of PEFR measured with MPFM was significantly lower than that($5.2{\pm}3.5%$) with standard pneumotachygraph in normal (p < 0.05). Conclusion : This results suggest that the MPFM was as accurate and reproducible as standard pneumotachygraph for monitoring of PEFR in the asthmatic subjects.