• Advances in aircraft and spacecraft science
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• v.10 no.3
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• pp.281-302
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• 2023

In this paper, bending analysis of exponentially varying functionally graded (FG) plate is presented using trigonometric shear deformation theory (TSDT) considering both transverse shear and normal deformation effects. The in-plane displacement field consists of sinusoidal functions in thickness direction to include transverse shear strains and transverse displacement include the effect of transverse normal strain using the cosine function in thickness coordinate. The governing equations and boundary conditions of the theory are derived using the virtual work principle. System of governing equations, for simply supported conditions, Navier's solution technique is used to obtain results. Plate material properties vary across thickness direction according to exponential distribution law. In the current theory, transverse shear stresses are distributed accurately through the plate thickness, hence obviates the need for a shear correction factor. TSDT results are compared with those from other theories to ensure the accuracy and effectiveness of the present theory. The current theory is in excellent agreement with the semi-analytical theory.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.10
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• pp.2396-2402
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• 2015

Air compressor, as an essential equipment used in the factory and plant operations, accounts for around 30% of the total electricity consumption in U.S.A, thereby being proposed advanced technologies to reduce electricity consumption. When the fluctuation of the compressed airflow rate is small, the system stability is increased followed by the reduction of the electricity consumption which results in the efficient design of the energy system. In the statistical analysis, the normal distribution, log normal distribution, gamma distribution or the like are generally used to identify system characteristics. However a single distribution may not fit well the data with long tail, representing sudden air flow rate especially in extremes. In this paper, authors decouple the compressed airflow rate into two parts to present a mixture of distribution function and suggest a method to reduce the electricity consumption. This reduction stems from the fact that a general pareto distribution estimates more accurate quantile value than a gaussian distribution when an airflow rate exceeds over a large number.

• Communications for Statistical Applications and Methods
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• v.21 no.3
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• pp.213-224
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• 2014

In this paper, we study the problem of transforming to normality. We propose to estimate the transformation parameter by minimizing a weighted squared distance between the empirical characteristic function of transformed data and the characteristic function of the normal distribution. Our approach also allows for other symmetric target characteristic functions. Asymptotics are established for a random sample selected from an unknown distribution. The proofs show that the weight function $t^{-2}$ needs to be modified to have thinner tails. We also propose the method to compute the influence function for M-equation taking the form of U-statistics. The influence function calculations and a small Monte Carlo simulation show that our estimates are less sensitive to a few outliers than the maximum likelihood estimates.

• The Korean Journal of Nuclear Medicine
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• v.20 no.1
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• pp.67-73
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• 1986

Subclinical hypothyroidism can be defined as an asymptomatic state in which a reduction in thyroid activity has been compensated by an increased TSH output to maintain a euthyroid state. We analysed clinical features, laboratory data, and pathologic findings in 3g cases of subclinical hypothyroidism who were diagnosed at the Dept. of Internal Medicine, Chungnam National University Hospital from Aug. 1984 to June, 1985. 1) The age distribution was from sixteen to sixty-nine and mean a9e was 34.8. Peak incidence was in the 4th decade and 3rd, 5th, 6th decade in order. 2) The sex distribution showed female preponderance with a ratio of 18.5 to 1. 3) The major presenting manifestations were nonspecific ones such as fatigue, indigestion, and anorexia. 4) Physical examination revealed diffuse goiter in 47.6%. Major abnormalities were no gross abnormality (30.9%), nodular goiter and facial edema. 5) There was no significant difference of the basal serum $T_3\;and\;T_4$ concentrations between subclinical hypothyroidism and normal controls (p>0.05). 6) The basal serum TSH concentration of subclinical hypothyroidism $(32.61{\pm}14.95{\mu}U/ml)$ was significantly higher than that of normal controls $(3.92{\pm}1.05{\mu}U/ml)$ (p<0.005). 7) Microsomal antibody was detected in 80.6% and thyroglobulin antibody was detected in 30%. 8) The pathologic findings in 26 cases revealed Hashimoto's thyroiditis in 76.9% (lymphocytic type, 34.6%; oxyphilic type, 26.9%; fibrotic type, 15.4%). The others were adenomatous goiter(15.4%), adenomatous carcinoma (3.8%) and subacute thyroiditis(3.8%).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.123-124
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• 2006

Usually, hydraulic cylinder is widely used as the actuator in the equipment of construction machines, airplane and military machines. In case of these devices, due to use under severe environment such as water, $SiO^2$ and dust, etc. seal which has high packing ability and long service life has been required. These characteristics are largely influenced by material and geometries of seal such as approach angle, withdrawal angle and interference. Recently, many a study about seal material has been performed so that many materials have been developed. But the concrete studies including the relationships between geometry of seal and sealing performance have hardly been performed yet. Therefore, in this study, we predicted the deformation behavior and contact normal distribution of dust seal with the variation of geometries of seal lip using finite element analysis. And based on the results of analyses, we discussed the effects of the design variables fur sealing performance of the dust seal.

• Journal of the Korean Society of Visualization
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• v.20 no.2
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• pp.78-85
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• 2022

In these days, the rapid development in prediction technology using artificial intelligent is being applied in a variety of engineering fields. Especially, dimensionality reduction technologies such as autoencoder and convolutional neural network have enabled the classification and regression of high-dimensional data. In particular, pixel level prediction technology enables semantic segmentation (fine-grained classification), or physical value prediction for each pixel such as depth or surface normal estimation. In this study, the pressure distribution of the ship's surface was estimated at the pixel level based on the artificial neural network. First, a potential flow analysis was performed on the hull form data generated by transforming the baseline hull form data to construct 429 datasets for learning. Thereafter, a neural network with a U-shape structure was configured to learn the pressure value at the node position of the pretreated hull form. As a result, for the hull form included in training set, it was confirmed that the neural network can make a good prediction for pressure distribution. But in case of container ship, which is not included and have different characteristics, the network couldn't give a reasonable result.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.2
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• pp.143-150
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• 1976

A trial has been made to find out a new method of calculating the survival rate of a fish Population utilizing the length composition data and the characteristics of the frequency curve of the length which usually is normal distribution curve. In this paper, a stochastic method is introduced and applied to calculate the survival rate of yellow croaker caught by Korean trawlers in the Yellow Sea and the East China Sea in 1971. The results are as follows : Mean of survival rate 0.46089 Variance 0.03073 Standard deviation 0.17529 95 percent confidence interval 0.36040-0.56138.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.201-202
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• 1998

In this paper we suggested an automated method for detecting and counting rapid eye movement(REM) using EOG during sleep. This method is formulated by two step fuzzy logic. At first step, the velocity and the distance of single channel eye movement are used for the fuzzy input to get the possibility of being REM at each EOG. At second step, the two possibility values of both EOG from the first step and the correlation coefficient of both eye movements are used for the fuzzy logic input, and the output is the final possibility of being Rapid Eye Movement. We applied this algorithm to the normal and narcoleptic sleep data and compared the difference. We found the possibility that the count of REM can be a parameter that has significant physiological meanings.

• Nuclear Engineering and Technology
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• v.15 no.1
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• pp.41-49
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• 1983

A computer code, BERD (Bayesian Estimation of Reliability Data), has been developed and tested in order to update the data for the reliability analysis of safety related systems in a specific nuclear power plant. The code has been used to derive the plant-specific data for reliability analysis of the auxiliary feedwater system of a pressurized water reactor. The prior information for components selected was taken from the U.S. Reactor Safety Study, WASH-1400, and the operating experiences from published licensee event reports. The results show that the updated data are well fitted to log-normal distribution curves and the error factors are reduced significantly.

• Journal of Distribution Science
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• v.15 no.12
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• pp.31-39
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• 2017

Purpose - The purpose of the paper is to examine shipping markets exposed on severe competition after Lehman Brothers crisis in 2008, and look for some alternatives to get it over. Research design, data, and methodology - The research method to be applied is first to look into world economic situations, and then to investigate supply and demand of shipping markets, and strategic alliances as alternatives, which lead to some implication and lessons. Results - After the fierce world economic situations after Lehman Brothers crisis in U.S, it has shown that world economic output and growth is not like that of previous years. It is periods of new normal. Then, shipping has been influenced by less trade volumes and, however, shipping capacity has reached to overcapacity in supply terms. Therefore rates down is clear, and it should be needed new way of getting it over market situations. In this sense, strategic alliance is answer for overcoming difficult markets. Conclusions - From the careful look at all situations, such as world economic situation, supply and demand of shipping market, deep understanding for strategic alliances of shipping, it has reached to conclusion that strategic alliance is only answer for difficult shipping markets.