• Korean Journal of Veterinary Research
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• v.52 no.2
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• pp.141-146
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• 2012

Calving records of Holstein dairy cows from 2005 to 2010 comprising Goyang and Paju cities herd with 2,362 calving events representing 240 twin births were used to evaluate the effect of abomasal displacement and retained placenta after single or twin births on fertility. In retained placenta cows, the period of twin pregnancy (mean 270.5 days) was shorter than that of single pregnancy (mean 274.8 days), however first artificial insemination period (twin: mean 107.4 days, single: mean 92.0 days), non-pregnant period (twin: 154.8 days, single: 132.2 days), and number of insemination (twin: mean 2.00 times, single: mean 1.87 times) of twin pregnancy were increased as compared with single pregnancy. In abomasal displacement cows, first artificial insemination period (twin: mean 122.9 days, single: mean 106.0 days), non-pregnant period (twin: 172.4 days, single: 152.0 days), and number of insemination (twin: mean 2.16 times, single: mean 1.89 times) of twin pregnancy were increased as compared with single pregnancy. The prevalence of complication such as retained placenta, abomasal displacement with single or twin births increased first artificial insemination period, non-pregnant period, and number of insemination period.

• International Journal of Air-Conditioning and Refrigeration
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• v.10 no.4
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• pp.177-183
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• 2002

A pulsed tracer gas technique is applied to measure the distributions of local mean age and local mean residual-life-time of air in a half-scale experimental chamber, The airflow patterns in the chamber are visualized by a Helium bubble generator for three different exhaust locations. A supply slot is located at the top of a right wall, and an exhaust slot is at either bottom-left (Case 1), bottom-right (Case 2), or top-left (Case 3) location. Results show that the distributions of local mean age and local mean residual-life-time are different from each other, but both of them are closely related to the airflow pattern in the space. Included are discussions on explaining the variations of overall room ventilation effectiveness depending upon airflow rates for three different supply-exhaust configurations.

• Journal of Korean Institute of Industrial Engineers
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• v.29 no.3
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• pp.239-246
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• 2003

Individual items are produced continuously from an industrial process. Each item is checked to determine whether it satisfies a lower screening limit for the quality characteristic which is the weight of an expensive ingredient. If it does, it is sold at a regular price; if it does not, it is reprocessed or sold at a reduced price. The process mean may be adjusted to a higher value in order to reduce the proportion of the nonconforming items. Using a higher process mean, however, may result in a higher production cost. In this paper, the optimal process mean and lower screening limit are determined in situations where the probability that an item functions well is given by a logistic function of the quality characteristic. Profit models are constructed which involve four price/cost components; selling prices, cost from an accepted nonconforming item, and reprocessing and inspection costs. Methods of finding the optimal process mean and lower screening limit are presented and numerical examples are given.

• Journal of Korean Institute of Industrial Engineers
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• v.24 no.4
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• pp.639-647
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• 1998

We consider a multiclass production system processed by a single machine with cyclic order. Each part belongs to one of several classes and arrives at each queue in a Poisson process. The processing discipline at each queue is either exhaustive or gated. We introduce a new approach to analysis of mean waiting times for each queue. We formulate mean waiting times as cost functions on state of the system. The mean waiting times are obtained by solving a set of O($J^2$) linear equations, where J is the number of queues in the system. We also obtain the mean number of parts of each queue in the system at an arbitrary time. Based on this result, we plot the numerical values of the mean waiting times for several parameter settings.

• Journal of Korean Neurosurgical Society
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• v.30 no.2
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• pp.201-206
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• 2001

Objective : The purpose of this study was to assess the complications, duration of admission, cost effectiveness, radiologic stabilization of the anterior cervical bone fusion in the treatment of cervical disc disease with and without plating. Materials and Methods : Fifty-two surgically treated patients for cervical disc disease were reviewed. Group I consisted of consecutive treated patients with iliac auto-bone graft without instrumentation after anterior cervical discectomy. Group II consisted of consecutive treated patients with iliac autologous-bone graft with CASPER cervical plate fixations. Radiologic fusion was decided when loss of end plate boundary between graft bone and vertebral body and immobile, maintenance of the disc space were evident on simple dynamic plain films. The patients were discharged after the stabilization of cervical motion by films was of tained. These groups were analysed multiple variably with Mann-Whitney U-test. Results : Group I consisted of 18 patients, group II consisted of 34 patients. Mean age was $49.0{\pm}8.1years$, mean duration of admission was $17.27{\pm}10.51days$, mean costs for treatment was $1,970,000{\pm}475,000won$. In group I, mean age was 47.7(34-60) years, 16 patients had undergo on one-level operation, 2-patients had undergo on two-level operation, mean duration of admission was $28.7{\pm}10.4days$, mean costs for treatment was $2,194,473{\pm}561,639won$. The periods of stabilization was $6.6{\pm}3.36weeks$ on radiologic study. Mean periods of out patient follow up was 16.8(6-64) weeks after discharge. Mean period of radiologic follow up was 17.3(4-6) weeks after surgical operation. In group II, mean age was 49.7(37-62) years and 18 patients one-level operation, 14- patients had undergo on two-level operation and 2-patients three-level operation. Mean duration of admission was $11.24{\pm}3.29days$, mean costs for treatment was $1,850,823{\pm}389,372won$. The periods of stabilization was $5.88{\pm}7.07weeks$ on radiologic study. Mean period of out patients follow up was 16.7(4-60) weeks after discharge. Mean period of radiologic follow up was 12.4(3-52) weeks after surgical operation. The duration of admission showed statistical significance in Group II but other items showed no significant difference between two groups. Conclusions : The more economic, early life return and effective method of cervical disc disease in our series were evident in patients who had undergone, iliac bone graft and plate fixations after anterior discectomy.

• Communications for Statistical Applications and Methods
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• v.22 no.3
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• pp.255-264
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• 2015

This paper addressed the problem of estimation of finite population mean in double sampling for stratification. This paper proposed a generalized ratio-cum-product type estimator of population mean. The bias and mean square error of the proposed estimator has been obtained upto the first degree of approximation. A particular member of the proposed generalized estimator was identified and studied from a comparison point of view. It is observed that the identified particular estimator is more efficient than usual unbiased estimator and Ige and Tripathi (1987) estimators. An empirical study was conducted in support of the theoretical findings.

• Kyungpook Mathematical Journal
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• v.49 no.1
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• pp.167-181
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• 2009

Based on Ricatti equation $XA^{-1}X=B$ for two (positive invertible) operators A and B which has the geometric mean $A{\sharp}B$ as its solution, we consider a cubic equation $X(A{\sharp}B)^{-1}X(A{\sharp}B)^{-1}X=C$ for A, B and C. The solution X = $(A{\sharp}B){\sharp}_{\frac{1}{3}}C$ is a candidate of the geometric mean of the three operators. However, this solution is not invariant under permutation unlike the geometric mean of two operators. To supply the lack of the property, we adopt a limiting process due to Ando-Li-Mathias. We define reasonable geometric means of k operators for all integers $k{\geq}2$ by induction. For three positive operators, in particular, we define the weighted geometric mean as an extension of that of two operators.

• Communications for Statistical Applications and Methods
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• v.21 no.1
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• pp.1-9
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• 2014

This paper discusses the problem of estimation of finite population mean in double sampling for stratification. In fact, ratio and product type exponential estimators of population mean are proposed in double sampling for stratification. The biases and mean squared errors of proposed estimators are obtained upto the first degree of approximation. The proposed estimators have been compared with usual unbiased estimator, ratio and product estimators in double sampling for stratification. To judge the performance of the proposed estimators an empirical study has been carried out.

• Communications for Statistical Applications and Methods
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• v.18 no.4
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• pp.537-548
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• 2011

In this paper following Singh et al. (2008), we propose a modified ratio-product type exponential estimator to estimate the finite population mean $\={Y}$ of the study variable y in presence of non-response in different situations viz. (i) population mean $\={X}$ is known, and (ii) population mean $\={X}$ is unknown. The expressions of biases and mean squared error of the proposed estimators have been obtained under large sample approximation using single as well as double sampling. Some realistic conditions have been obtained under which the proposed estimator is more efficient than usual unbiased estimators, ratio estimators, product estimators and exponential ratio and product estimators reported by Rao (1986) and Singh et al. (2010) are found to be more efficient in many situations.

• 한국기계연구소 소보
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• s.18
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• pp.169-175
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• 1988

The influence of mean strain on the behavior of early stage stress amplitude was investigated quantitatively in low cycle fatigue. It was obtained that the exponent of cyclic strain(n') and the coefficient of cyclic strain(C') decreased with increasing cycle numbers in compressive mean strain level. But it was the opposite in 0% mean strain and tensile mean strain level. And the cyclic yield strength ($\delta_(yc)$) was constant irrespective of mean strain or cyclic strain