• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.2
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• pp.109-116
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• 1988

The strength and load of structure are varied with the Passage of time, and become a process of probability. It is possible to estimate the reliability from the relation between strength and load. Considering the safety, It is reasonable to estimate allowable stress from the safety factor based on the reliability. In this study, the method to estimate probability of fracture, which is index of reliability for rail subjeict to long term fatigue load were examined. In estimation of reliablity it is meaningless to evaluate numerical value especially this difficult case estimating parameter of random variable. To overcome this problem, conventional design method estimating relative reliability were proposed. In this study the Cornell method were examined. The uncertainity of random variale, ie coefficient of variation which is the index of variation of strength and load were considered. The effect of uncertainity related to probability of fracture, and safety factor based on reliability were examined. The results of this study are followed. The reliability of weld metal were influenced by variation of strength more then load, and base metal were influenced by load. It is confirmed that the allowable stress range calculating with factor of safety based an reliability is conservative.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.12
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• pp.1159-1166
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• 2010

Today, detecting the location of moving object has been traced as various methods in our world. In this paper, we preset the system to improve the estimation accuracy utilizing detail localization using radar sensor based on WSN and situational awareness for a calibration (context aware) database, Rail concept. A variety of existing location tracking method has a problem with receiving of data and accuracy as tracking methodology, and since these located data are the only data to be collected for location tracing, the context aware or monitering as the surrounding environment is limited. So, in this paper, we enhanced the distance aware accuracy using radar sensor utilizing the Doppler effect among the distance measuring method, estimated the location using the Triangulation algorithm. Also, since we composed the environment data(temperature, illuminancem, humidity, noise) to entry of the database, it can be utilized in location-based service according to the later action information inference and positive context decision. In order to verify the validity of the suggested method, we give a few random situation and built test bed of designed node, and over the various test we proved the utilizing the context information through route tracking of moving and data processing.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.2
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• pp.63-75
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• 2018

This paper proposes extension of Latin Hypercube Sampling (LHS) to avoid the necessity of using intervals with the same probability area where intervals with different probability areas are used. This method is called Weighted Latin Hypercube Sampling (WLHS). This paper describes equations and detail procedure necessary to apply weight function to WLHS. WLHS is verified through numerical examples by comparing the estimated distribution parameters with those from other methods such as Random Sampling and Latin Hypercube Sampling. WLHS provides more flexible way on selecting samples than LHS. Accuracy of WLHS estimation on distribution parameters is depending on the selection of weight function. The proposed WLHS is applied to seismically isolated structures in nuclear power plants. In this application, clearance-to-stops (CSs) calculated using LHS proposed by Huang et al. [1] and WLHS proposed in this paper, respectively, are compared to investigate the effect of choosing different sampling techniques.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.5
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• pp.2003-2007
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• 2012

Purpose: E-cadherin is a transmemberane protein which is responsible for adhesion of endothelial cells. The aim of our study was to assess existing evidence of associations between reduced expression of E-cadherin and prognosis of ovarian cancer with a discussion of potential approaches to exploiting any prognostic value for improved clinical management. Methods: We conducted a meta-analysis of 9 studies (n=915 patients) focusing on the correlation of reduced expression of E-cadherin with overall survival. Data were synthesized with random or fixed effect hazard ratios. Results: The studies were categorized by author/year, number of patients, FIGO stage, histology, cutoff value for E-cadherin positivity, and methods of hazard rations (HR) estimation, HR and its 95% confidence interval (CI). Combined hazard ratios suggested that reduced expression of E-cadherin positivity was associated with poor overall survival (OS), HR= 2.10, 95% CI:1.13-3.06. Conclusion: The overall survival of the E-cadherin negative group with ovarian cancer was significant poorer than the E-cadherin positive group. Upregulation of E-cadherin is an attractive therapeutic approach that could exert significant effects on clinical outcome of ovarian cancer.

• Coupled systems mechanics
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• v.3 no.2
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• pp.147-170
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• 2014

In the recent times, dimensions of heavy load carrying vehicle have changed significantly incorporating structural flexibility in vehicle body. The present paper outlines a procedure for the estimation of bridge response statistics considering structural bending modes of the vehicle. Bridge deck roughness has been considered to be non homogeneous random process in space. Influence of pre cambering of bridge surface and settlement of approach slab on the dynamic behavior of the bridge has been studied. A parametric study considering vehicle axle spacing, mass, speed, vehicle flexibility, deck unevenness and eccentricity of vehicle path have been conducted. Dynamic amplification factor (DAF) of the bridge response has been obtained for several of combination of bridge-vehicle parameters. The present study reveals that flexible modes of vehicle can reduce dynamic response of the bridge to the extent of 30-37% of that caused by rigid vehicle model. However, sudden change in the bridge surface profile leads to significant amount of increment in the bridge dynamic response even if flexible bending modes remain active. The eccentricity of vehicle path and flexural/torsional rigidity ratios plays a significant role in dynamic amplification of bridge response.

• Korea Trade Review
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• v.44 no.2
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• pp.269-282
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• 2019

This study analyzes the effects of participation in the global production network on the income inequality using panel data from 2005 to 2016 for 63 countries. In this study were used fixed effects model with autocorrelation, random effect model with autocorrelation and the GLS method. Results are as follows: First, the economic development level supports the Kuznets hypothesis. And then, the forward participation in global value chains increased income inequality, and the backward participation decreased income inequality. In order to derive more detailed estimation results, we analyzed OECD countries and non-OECD countries. First, OECD countries featured decreased, but increased beyond a certain level as a U-shaped curve, that did not support the Kuznets hypothesis. In contrast, non-OECD countries followed the Kuznets U-curve. Second, participation in the global production network showed that both OECD and non-OECD countries featured increased income inequality. In contrast, backward participation appears to mitigate income inequality both in OECD and non-OECD countries. Finally, the ratio of labor and capital is significant in mitigating income inequality in non-OECD countries in which they feature backward participation in production networks. This can be interpreted as developing economies participate in the global production network due to increased capital accumulation and increased the labor productivity.

• Journal of Korean Association for Spatial Structures
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• v.21 no.2
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• pp.99-110
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• 2021

This study presents the estimation of crack depth by analyzing temperatures extracted from thermal images and environmental parameters such as air temperature, air humidity, illumination. The statistics of all acquired features and the correlation coefficient among thermal images and environmental parameters are presented. The concrete crack depths were predicted by four different machine learning models: Multi-Layer Perceptron (MLP), Random Forest (RF), Gradient Boosting (GB), and AdaBoost (AB). The machine learning algorithms are validated by the coefficient of determination, accuracy, and Mean Absolute Percentage Error (MAPE). The AB model had a great performance among the four models due to the non-linearity of features and weak learner aggregation with weights on misclassified data. The maximum depth 11 of the base estimator in the AB model is efficient with high performance with 97.6% of accuracy and 0.07% of MAPE. Feature importances, permutation importance, and partial dependence are analyzed in the AB model. The results show that the marginal effect of air humidity, crack depth, and crack temperature in order is higher than that of the others.

• Journal of Veterinary Clinics
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• v.28 no.4
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• pp.422-426
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• 2011

For a national survey in which wide geographic region or an entire country is targeted, multi-stage sampling approach is widely used to overcome the problem of simple random sampling, to consider both herd- and animallevel factors associated with disease occurrence, and to adjust clustering effect of disease in the population in the calculation of sample size. The aim of this study was to establish sample size for estimating bovine tuberculosis (TB) in Korea using stratified two-stage sampling design. The sample size was determined by taking into account the possible clustering of TB-infected animals on individual herds to increase the reliability of survey results. In this study, the country was stratified into nine provinces (administrative unit) and herd, the primary sampling unit, was considered as a cluster. For all analyses, design effect of 2, between-cluster prevalence of 50% to yield maximum sample size, and mean herd size of 65 were assumed due to lack of information available. Using a two-stage sampling scheme, the number of cattle sampled per herd was 65 cattle, regardless of confidence level, prevalence, and mean herd size examined. Number of clusters to be sampled at a 95% level of confidence was estimated to be 296, 74, 33, 19, 12, and 9 for desired precision of 0.01, 0.02, 0.03, 0.04, 0.05, and 0.06, respectively. Therefore, the total sample size with a 95% confidence level was 172,872, 43,218, 19,224, 10,818, 6,930, and 4,806 for desired precision ranging from 0.01 to 0.06. The sample size was increased with desired precision and design effect. In a situation where the number of cattle sampled per herd is fixed ranging from 5 to 40 with a 5-head interval, total sample size with a 95% confidence level was estimated to be 6,480, 10,080, 13,770, 17,280, 20.925, 24,570, 28,350, and 31,680, respectively. The percent increase in total sample size resulting from the use of intra-cluster correlation coefficient of 0.3 was 22.2, 32.1, 36.3, 39.6, 41.9, 42.9, 42,2, and 44.3%, respectively in comparison to the use of coefficient of 0.2.

• Journal of Animal Science and Technology
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• v.52 no.5
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• pp.349-356
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• 2010

This study was conducted to estimate heritabilities, repeatabilities and rank correlation coefficients among breeding values for litter size and sex ratio of Yorkshire and Landrace pigs using various single trait animal models. The analyses were carried out the data comprising 26,390 litters of Yorkshire and 26,173 litters of Landrace collected from the year 1998 to 2008 at a private swine breeding farm located in central part of Korea. Five different analytical models were used for genetic parameter estimation. Model 1 was most simple basic model fitted with year-month contemporary group fixed effect, random additive genetic effect and random residual effect. Model 2 was similar to the model 1 but permanent maternal environmental effect added as random effect, and model 3 was similar with the model 2 but linear and quadratic effects of sow age were added as fixed covariate effect. Model 4 was similar as model 2 except that the parity was added as fixed effect and model 5 was similar to model 3 or model 4 but covariate of sow age was nested within parity effect. The results obtained in this study are summarized as follows: The means and standard error of total number of pigs born per litter (TNB) and number of pigs born alive per litter (NBA) were $11.35{\pm}0.02$ and $10.04{\pm}0.02$ for Yorkshire, $10.97{\pm}0.02$ and $9.98{\pm}0.02$ for Landrace, respectively. The sex ratio (percentage of female per litter) was $45.75{\pm}0.11%$ and $45.75{\pm}0.11%$ for Yorkshire and Landrace, respectively. The heritability estimates of TNB (0.243) and NBA (0.192) from model 1 tended to be higher than those from any other models in both breeds. Differences in heritability and repeatability for TNB were not large among models 3, 4 and 5 and same tendency of negligible differences among estimates by models 3, 4 and 5 were observed for NBA, where heritability and repeatability ranged from 0.096 to 0.099 and from 0.188 to 0.193, respectively, in Yorkshire; and ranged from 0.092 to 0.098 and from 0.193 and 0.196, respectively, in Landrace. The heritability estimates for sex ratio were close to zero which was ranged from 0.002 to 0.003 for TNB and from 0.001 to 0.003 for NBA over the models applied. The rank correlation coefficients of breeding values by model 1 with those from other models (model 2, 3, 4 and 5), and breeding values by model 2 with those from other models (model 1, 3, 4 and 5) were highly positive but lower than the coefficients among breeding values by model 3, model 4 and model 5 which were high of 0.99, approximately, for TNB and NBA of both breeds.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.3
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• pp.275-282
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• 2009

Generally, the sinusoidal cavity dither is adopted to ring laser gyroscope for eliminating the lock-in which is non-linear effect at the small rotation input. Despite this method, there are some remained errors which are generated at the dither turnaround, and those errors produce random walk which is a general character of a ring laser gyroscope. As one of the numerous research results for compensating these errors, there is a special lock-in compensation method which is the method of error estimation and compensation by comparing the beat signal periods of before and after the dither turnarounds. In this paper, by ring laser gyroscope modeling and numerical analysis, we verified the theoretical validity and confirmed the effectiveness of this method in expectation of the possible beat signal measurement time resolution. As a result, we confirmed the random walk decreases from a-half to a-third by this lock-in compensation method. So, it is expected to be a remarkable method for reducing the INS alignment time.