• Atmosphere
• /
• v.30 no.2
• /
• pp.103-113
• /
• 2020

In this study, we analyzed and developed the monitoring system in order to confirm the effect of observations on forecast sensitivity on ensemble-based data assimilation. For this purpose, we developed the Ensemble Forecast Sensitivity to observation (EFSO) monitoring system based on Local Ensemble Transform Kalman Filter (LETKF) system coupled with Korean Integrated Model (KIM). We calculated 24 h error variance of each of observations and then classified as beneficial or detrimental effects. In details, the relative rankings were according to their magnitude and analyzed the forecast sensitivity by region for north, south hemisphere and tropics. We performed cycle experiment in order to confirm the EFSO result whether reliable or not. According to the evaluation of the EFSO monitoring, GPSRO was classified as detrimental observation during the specified period and reanalyzed by data-denial experiment. Data-denial experiment means that we detect detrimental observation using the EFSO and then repeat the analysis and forecast without using the detrimental observations. The accuracy of forecast in the denial of detrimental GPSRO observation is better than that in the default experiment using all of the GPSRO observation. It means that forecast skill score can be improved by not assimilating observation classified as detrimental one by the EFSO monitoring system.

• Transactions of the Society of Information Storage Systems
• /
• v.3 no.4
• /
• pp.178-182
• /
• 2007

Topology optimization methods are classified into two methods such as the density method and the homogenization method. Those methods need to consider relationships between the material property and the density of each element in a design domain, the relaxation of the design space, etc. However, it is hard to apply on some cases due to the complexity to compose the design objective and its sensitivity analysis. In this paper, a modified topology optimization is proposed to assist designers who do not have mathematical or theoretical background of the topology optimization. In this study, optimal topology of structures can be achieved by the sequential design of experiment (DOE) and the sensitivity analysis. We conducted the DOE with an orthogonal array and the sensitivity analysis of design variables to determine sensitive variables used for connectivity between elements. The modified topology optimization method has advantages such as freedom from penalizing intermediate values and easy application with basic DOE concept.

• Atmosphere
• /
• v.25 no.1
• /
• pp.51-66
• /
• 2015

This study was conducted to perform various sensitivity experiments using WRF (Weather Research and Forecasting) model in order to determine the effects of terrains of the Korean Peninsula and the land-sea thermal contrast on the formation and development of the convergent cloud band for the cases of 1 February 2012. The sensitivity experiments consist of the following five ones: CNTL experiment (control experiment), and TMBT experiment, BDMT experiment and ALL experiment that set the terrain altitude of Taeback Mountains and Northern mountain complex as zero, respectively, and the altitude of the above-mentioned two mountains as zero, and LANDSEA experiment that set to change the Korean Peninsula into sea in order to find out the land-sea thermal contrast effect. These experiment results showed that a cold air current stemming from the Siberian high pressure met the group of northern mountains with high topography altitude and was separated into two air currents. These two separated air currents met each other again on the Middle and Northern East Sea, downstream of the group of northern mountains and converged finally, creating the convergent cloud band. And these experiments suggested that the convergent cloud band located on the Middle and Northern East Sea, and the cloud band lying on the southern East sea to the coastal waters of the Japanese Island facing the East Sea, were generated and developed by different dynamical mechanisms. Also it was found that the topography of Taeback Mountains created a warm air advection region due to temperature rise by adiabatic compression near the coastal waters of Yeongdong Region, downstream of the mountains. In conclusion, these experiment results clearly showed that the most essential factor having an effect on the generation and development of the convergent cloud band was the topography effect of the northern mountain complex, and that the land-sea thermal contrast effect was insignificant.

• Nuclear Engineering and Technology
• /
• v.55 no.1
• /
• pp.131-143
• /
• 2023

Constitutive equations in a nuclear reactor safety analysis code are mostly empirical correlations developed from experiments, which always accompany uncertainties. The accuracy of the code can be improved by modifying the constitutive equations fitting wider range of data with less uncertainty. Thus, the sensitivity of the code with respect to the constitutive equations is evaluated quantitatively in the paper to understand the room for improvement of the code. A new methodology is proposed which first starts by dividing the thermal hydraulic conditions into multiple sub-regimes using self-organizing map (SOM) clustering method. The sensitivity analysis is then conducted by multiplying an arbitrary set of coefficients to the constitutive equations for each sub-divided thermal-hydraulic regime with SOM to observe how the code accuracy varies. The randomly chosen multiplier coefficient represents the uncertainty of the constitutive equations. Furthermore, the set with the smallest error with the selected experimental data can be obtained and can provide insight which direction should the constitutive equations be modified to improve the code accuracy. The newly proposed method is applied to a steady-state experiment and a transient experiment to illustrate how the method can provide insight to the code developer.

• Preventive Nutrition and Food Science
• /
• v.3 no.4
• /
• pp.356-361
• /
• 1998

An experiment was performed to determine if buckwheat intake would improve insulin sensitivity in in normal healthy ras and steptozoticin-induced diabetic Sprague-Dauley rats. For four weeks, rats were fed either corn starch as a cotnrol diet or buckwheat as an experimental diet. As a result, the insulin sensitivity and plasma glucose levels in normal rats were not significantly affected by buckwheat fedding. The insulin sensitivity was lower in diabetic rats than in normal rats(p<0.05). Buckwheat tends to decrease the final plasma glucose level and increase insulin sensitivity in diabetic rats, but there was no sifnificant difference. Another five-week experiment was conducted to determine protein digestibility and protein utility in normal healty rats ad streptozotocin-induced diabetic rats on a control diet or buckwheat diet. The diet composition in this experiment was the same as the preceeding experiment. In the cotnrol diet groups, the protein digestibility in diabetic rats was significantly lower than that in normal rats(p<0.05). Buckwheat reduced protein digestibility in both normal and disbetic rats(p<0.05). Interestingly, in buckwheat diet groups, protei digestibility in diabetic rats was similar to that in normal rats. Protein utility was significantly lower indiabetic rats than in normal rats. This phenomenon was observed as early as the first week of the feeding period. However, protein utility was not sifnificanlty altered in both normal and diabetic rats by buckwheat feeding. It follows that decreased protein digestibility and utility in diabetic rts are not further aggravated by buckwheat feeding, suggesting that buckwheat can be a feasible supplement food for the diabetic therapeutic diet.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.11a
• /
• pp.363-366
• /
• 2005

Social survey and auditory experiment on residential noises such as floor impact, air-bome, bathroom, drainage and traffic noises were conducted to investigate the effects of sensitivity and background noise levels on subjective response to residential noises. Results of survey showed that multiple questions for sensitivity to noise have a more power for discrimination against subjective response to noise than single question. It was also found that the correlation between sensitivity and annoyance was relatively low, but the differences in annoyance between sensitivity groups were significant. Result of auditory experiment showed that effects of sensitivity on annoyance were different according to noise type and noise level. It was also shown that the difference in annoyance between the lowest sensitive stoup and the highest sensitive group was significant in low noise level. The effects of background noise on subjective responses to noise was also different according to noise source and noise level, and were significant in low noise level of airborne and drainage noise.

• Transactions of Materials Processing
• /
• v.10 no.1
• /
• pp.15-22
• /
• 2001

The sensitivity method has been utilized to find initial blank shapes which transform into desired shapes after forming. From the information of die shapes, target shape and material properties, the corresponding initial blank which gives final shape after deformation has been found. Drawings of a trapezoidal cup, a cross-shaped cup and an oil pan have been chosen as the examples. At every case the optimal blank shape has been obtained only a few times of modification without any predetermined deformation path. With the predicted optimal blank, both computer simulation and experiment are performed. Excellent agreements are recognized between simulation and experiment at every cases Through the investigation, the sensitivity method is found to be effective in obtaining optimal blank shapes in drawing of complex shapes.

• Science of Emotion and Sensibility
• /
• v.5 no.1
• /
• pp.79-90
• /
• 2002

The role of memory is viewed as central to developing and maintaining flight situation awareness (SA). The present research examines constituent memory processes that underlie flight SA sensitivity as a function of pilot expertise. In Experiment 1, pilot memory for different forms (spatial or verbal) of cockpit situational information was tested immediately after presentation of the information (immediate recall) or after 30-s delay filled with an intervening task (delayed recall). In Experiment 2, pilot SA sensitivity was examined and correlated with memory measures obtained in Experiment 1. Results suggest that an expertise effect occurs in delayed recall but not in immediate recall and that memory representation of situational information required to develop high levels of SA sensitivity varies as a function of expertise. Theoretical accounts of results are discussed in the context of psychological theories of expertise.

• Journal of Embryo Transfer
• /
• v.28 no.3
• /
• pp.223-227
• /
• 2013

The objective of the study is to assess temperament of a horse based on general temperament test by a questionnaire survey. Five test criteria were identified: gentleness, patience, aggressiveness, sensitivity, and friendliness, each on a 5-point scale. 114 horses bred at the National Institute of Animal Science (NIAS) in 2010, 2011 and 2012. The horses recorded scores of 3.6~3.9 for gentleness, 3.1~3.6 for patience, 3.4~4.0 for aggressiveness, 2.8~3.2 for sensitivity, and 3.4~3.8 for friendliness, the overall score for sensitivity the lowest. Horses born in 2012 scored lower than the rest in all five areas at a statistically significant level (P<0.05). By gender, the colts scored higher than the fillies in all five areas, but the discrepancy was not statistically significant. Factor analysis yielded only one factor, and the Cronbach's ${\alpha}$ value was 0.980 for standardization of Factor 1, indicating a high reliability of internal consistency. The correlation coefficients among the test criteria ranged between 0.85 and 0.91 (P<0.01). The assessment criteria used in this study are expected to provide a useful basis designing a temperament test horses.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.18 no.1
• /
• pp.51-57
• /
• 2010

This study was to analyze the difference in pilot error by using the Signal Detection Theory. The task was to detect the targeted aircraft(signal) which is different shape from many other aircraft(noise). From the two experiments, we differentiated the task difficulty followed by change in noise stimuli. Experiment 1 was to search the signal stimuli(fighter plane) while the noise stimuli(cargo plane) were increasing. The results from the Experiment 1 showed the tendency to decrease the hit rate by increasing the number of noise stimuli. However, the false alarm rate was not increased. The sensitivity(d') showed quite high. In Experiment 2, a disturbance stimulus(helicopter) was added to noise stimuli. The result was generally similar to those of Experiment 1. However, the hit rate was lower than that of Experiment 1.