• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.16 no.3
• /
• pp.54-62
• /
• 2017

When gears mesh, shock and noise are produced as results of tooth error and tooth deformation under load. Transmission error (TE) is the most important cause of gear noise and vibration because TEs affect the changes of the force and the speed of gears. Gear tooth modification research plays a positive role in reducing TE and improving the design level and transmission performance of transmission systems. In high-precision manufacturing gear, gear tooth modification is also commonly used to reduce noise in practical applications. In order to study the accuracy of gear transmission, some empirical gear profile micro-modifications are introduced, and a helical gear pair is modeled and analyzed in RomaxDesigner software to investigate the utility of these modification methods. Some of these will be selected as experimental proposals for gear pairs, and these manufactured gears will be tested and compared in a semi-anechoic room later. The final purpose of this study is to find reasonable and convenient empirical formulae to facilitate improved gear production.

• Journal of Pharmaceutical Investigation
• /
• v.26 no.3
• /
• pp.215-219
• /
• 1996

Active component was sought among three herb medicines, which are used in combination as a traditional medicine prescribed for patients with hyperlipidemia related diseases. Antihyperlipidemic effect of this remedy has previously been shown model by the authors on the animal model. Hyperlipidemia was induced on male Wistar rats by keeping them on high lipid diet for one week, as previously described by the authors. Blood lipid profile was verified on these rats by measuring total cholesterol (TC), triglyceride (TG), high density lipoprotein (HDL) and low density lipoprotein (LDL). Then, the diet was changed to normal. At the same time, methanol extracts of Scutellaris baicalensis Georg.(radix), Coptidis japonica Makino(rhizoma) or Rhei koreanum Nakai(rhizoma) were given on daily basis, and changes in the blood lipid profile were monitored for 4 weeks. Methanol extract of Scutellaris baicalensis Georg. significantly reduced the TC value, implying the in vivo antihyperlipidemic effect.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.4
• /
• pp.23-29
• /
• 2015

In this paper, we introduce a underwater ranging algorithm with Look-up Table (LUT) by modifying the existing method which is using the changes of angles of accoustic rays with SSP (Sound Speed Profile). We compare the horizontal distance errors and the calculation times. Our new algorithm exploits Time of Arriva l(ToA) - horizontal distance table based on SSP. This algorithm offers faster calculation speed than the previous one with the slight increase of the distance estimation error.

• Journal of Dental Anesthesia and Pain Medicine
• /
• v.19 no.5
• /
• pp.271-276
• /
• 2019

Background: The Child Oral Health Impact Profile (COHIP) is a measure of oral health-related quality of life (OHRQoL) in children and adolescents. This study examined the impact of dental fear on the OHRQoL by comparing the COHIP scores of children with and without dental fear. Methods: The OHRQoL in children and adolescents was measured using the Korean version of the COHIP. In total, 102 students (49 boys and 53 girls) filled in a questionnaire designed to evaluate dental fear and the OHRQoL in 2012 and 2014. Results: In 2012, the group without dental fear showed higher COHIP scores than the group with dental fear; the difference between the two groups was statistically significant. In 2014, the same pattern was observed, but the difference was non-significant for all COHIP items other than those pertaining to social-emotional well-being. Comparison of COHIP scores according to changes in fear showed that the group with continuous dental fear showed significantly lower overall COHIP, negative COHIP, and low social-emotional wellbeing scores, than the group without continuous fear in 2012 and 2014. Conclusion: We expected children with dental fear to have poor oral health, affecting their OHRQoL; however, dental fear did not affect the OHRQoL.

• Food Science of Animal Resources
• /
• v.41 no.4
• /
• pp.739-747
• /
• 2021

This study examined the measurement conditions of the texture profile analysis (TPA) experiments that are typically used to measure the physical properties of sausage. As the measurement conditions (compression ratio and cross-head speed) were changed, the significant differences between the values of textural parameters (hardness, adhesiveness, springiness, cohesiveness, chewiness) of samples changed. Furthermore, among the measurement conditions, there was more variation in the significant difference between the value of samples due to a change in the compression ratio than due to a change in the cross-head speed. The highest variation in significant difference was observed between the values of cohesiveness of samples due to changes in measurement conditions, whereas the lowest variation in significant difference was observed between the values of springiness of samples due to change in measurement conditions. Therefore, it is desirable to provide a clear basis for setting specific measurement conditions for TPA test, since significant differences in the values of textural parameters of samples were caused by differences in cross-head speed or compression ratio, not by a difference in samples, when analyzing the cohesiveness of sausage, especially.

• Tribology and Lubricants
• /
• v.39 no.3
• /
• pp.118-122
• /
• 2023

In our study, we develop a finite element model based on Archard's wear law to predict the cumulative wear and the evolution of the tool profile in friction stir welding (FSW) applications. Our model considers the rotational and translational behaviors of the tool, providing a comprehensive description of the wear process. We validate the accuracy of our model by comparing it against experimental results, examining both the predicted cumulative wear and the resulting changes to the tool profile caused by wear. We perform a detailed comparison between the predictions of the model and experimental data by manipulating non-dimensional coefficients comprising model parameters, such as element sizes and time increments. This comparison facilitates the identification of a specific non-dimensional coefficient condition that best replicates the experimentally observed cumulative wear. We also directly compare the worn tool profiles predicted by the model using this specific non-dimensional coefficient condition with the profiles obtained from wear experiments. Through this process, we identify the model settings that yield a tool wear profile closely aligning with the experimental results. Our research demonstrates that carefully selecting non-dimensional coefficients can significantly enhance the predictive accuracy of finite element models for tool wear in FSW processes. The results from our study hold potential implications for enhancing tool longevity and welding quality in industrial applications.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.43 no.1
• /
• pp.83-88
• /
• 2010

Acoustic telemetry is a useful method to investigate fish behavior and is widely used to obtain biological information. In this study, the detection ability of a mooring-type acoustic telemetry system and the seasonal changes were studied for survey design and data analysis. The system detection range was examined with an underwater noise model, and seasonal changes were estimated with a ray-tracing program and underwater temperature profile data. The field experiment was conducted with two sets of pingers and six receivers to estimate the difference in detection rate by installation depth and to compare the model estimate. Results indicated that the long-range detection ability of the acoustic telemetry system was significantly affected by underwater temperature. The detection rate rapidly decreased near the sea surface or bottom despite that the near-range Signal to noise ratio was sufficient.

• The Korean Journal of Zoology
• /
• v.37 no.4
• /
• pp.597-604
• /
• 1994

Membranes obtained from the normal human RBC population were separated by continuous sucrose density gradient centrifugation and the density-fractionated membranes were then examined for changes in molecular markers. This study focuses on changes of (i) the membrane protein profile, (ii) differences in membrane-associsted enzyme activities, and (iii) the amount of autologous IgG bound. The following observations were made: (i) ratios for band 4. la over the sum of bands (4. la + 4.Ib) ranged from 0.58 to 0.79 for membranes of lowest density; (ii) significant changes in bound glyceraldehyde-3-phosphate dehydrogenase and acetvlcholinesterase activities were found; (iii) the amounts of autolosous IgG's attached to the red blood cells was highest in the membrane fraction of lowest density.

• Mycobiology
• /
• v.47 no.3
• /
• pp.346-349
• /
• 2019

AMP-activated protein kinase sucrose non-fermenting 1 (Snf1) is a representative regulator of energy status that maintains cellular energy homeostasis. In addition, Snf1 is involved in the mediation of environmental stress such as salt stress. Snf1 regulates metabolic enzymes such as acetyl-CoA carboxylase, indicating a possible role for Snf1 in metabolic regulation. In this article, we performed nuclear magnetic resonance (NMR) spectroscopy to profile the metabolic changes induced by Snf1 under environmental stress. According to our NMR data, we suggest that Snf1 plays a role in regulating cellular concentrations of a variety of metabolites during environmental stress responses.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2000.04a
• /
• pp.120-129
• /
• 2000

As structure-soil interaction analysis for the seismic analysis of structures requires a nonlinear analysis of a structure-soil system considering the inelastic characteristics of soil layers nonlinear analyses of the foundation-soil system with the horizontal excitation were performed considering the nonlinear soil conditions for the nonlinear seismic analysis of structures. Stiff soil profile of SD and soft soil profile of SE specified in UBC were considered for the soil layers of a foundation and Ramberg-Osgood model was assumed for the nonlinear characteristics of soil layers. Studies on the changes of dynamci stiffnesses and damping rations of surface and embedded foundations depending on foundation size soil layer depth and piles were performed to investigate the effects of the nonlinear soil layer on the horizontal and rotational dynamic stiffnesses and damping ratios of the foundation-soil system According to the study results nonlinear prperties of a soil laryer decreeased horizontal and rotational linear stiffnesses and increased damping ratios largely Effects of foundation size soil layer depth and piles were also significant suggesting the necessity of nonlinear seismic analyses of structures.