• Title/Summary/Keyword: normal function

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OUTLIER DETECTION BASED ON A CHANGE OF LIKELIHOOD

  • Kim, Myung-Geun
    • Journal of applied mathematics & informatics
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    • v.26 no.5_6
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    • pp.1133-1138
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    • 2008
  • A general method of detecting outliers based on a change of likelihood by using the influence function is suggested. It can be applied to all kinds of distributions that are specified by parameters. For the multivariate normal case, specific computations are made to get the corresponding conditional influence function. A numerical example is provided for illustration.

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Influence of an Observation on the t-statistic

  • Kim, Hong-Gie;Kim, Kyung-Hee
    • Communications for Statistical Applications and Methods
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    • v.12 no.2
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    • pp.453-462
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    • 2005
  • We derive the influence function on t statistic and find its feature; the influence function on t statistic has two forms depending on the value of ${\mu}_0$. Sample influence functions are used to verify the validity of the derived influence function. We use random samples from normal distribution to show the validity of the function. The simulation study proves that the obtained influence function is very accurate to in estimating changes in t statistic when an observation is added or deleted.

Monte Carlo Estimation of Multivariate Normal Probabilities

  • Oh, Man-Suk;Kim, Seung-Whan
    • Journal of the Korean Statistical Society
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    • v.28 no.4
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    • pp.443-455
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    • 1999
  • A simulation-based approach to estimating the probability of an arbitrary region under a multivariate normal distribution is developed. In specific, the probability is expressed as the ratio of the unrestricted and the restricted multivariate normal density functions, where the restriction is given by the region whose probability is of interest. The density function of the restricted distribution is then estimated by using a sample generated from the Gibbs sampling algorithm.

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A study on renal function indices in lead exposed male workers (연폭로 남자 근로자들의 신기능 지표에 관한 연구)

  • Lee, Sung-Soo;HwangBo, Young;Ahn, Kyu-Dong;Lee, Byung-Kook;Kim, Joung-Soon
    • Journal of Preventive Medicine and Public Health
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    • v.28 no.2 s.50
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    • pp.421-432
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    • 1995
  • The influence of lead exposure on renal function was studied. Eighty nine lead exposed workers who worked in 2 storage battery factories, and seventy one control workers were chosen for this study. Blood lead(PbB) and zinc protoporphyrin in whole blood(ZPP) were selected as indicators of lead exposure. As indicators of renal function, urinary N-acetyl-$\beta$-D-glucosaminidase(NAG), blood urea nitrogen(BUN), serum creatinine(S-Cr), total protein in urine(U-TP),and serum uric acid(S-Ua) were selected. The results obtained were as follows: 1. While the mean values of lead exposure indicators of lead workers were significantly different from non-exposed ones, the mean values of NAG, U-TP, BUN and S-Cr of renal function indicators of exposed were also significantly different from non-exposed but their mean values were all within normal limits. 2. BUN, logarithmic U-TP, logarithmic NAG and S-Cr showed statistically significant correlation with PbB. 3. The proportion of workers whose values of renal function indicators were over the normal limits(NAG7.5 U/g Cr ; U-TP10.9 mg/dl ; BUN20 mg/dl ; S-Crl.2 mg/dl ; S-Ua7.0 mg/dl) by the level of lead absorption in terms of PbB and ZPP were calculated. The proportion of workers with over the normal limits of U-TP among total workers showed the dose-response relationship. When age is adjusted, U-TP showed significantly strong dose-response relationship with the level of PbB and ZPP.

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Capabilities of stochastic response surface method and response surface method in reliability analysis

  • Jiang, Shui-Hua;Li, Dian-Qing;Zhou, Chuang-Bing;Zhang, Li-Min
    • Structural Engineering and Mechanics
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    • v.49 no.1
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    • pp.111-128
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    • 2014
  • The stochastic response surface method (SRSM) and the response surface method (RSM) are often used for structural reliability analysis, especially for reliability problems with implicit performance functions. This paper aims to compare these two methods in terms of fitting the performance function, accuracy and efficiency in estimating probability of failure as well as statistical moments of system output response. The computational procedures of two response surface methods are briefly introduced first. Then their capabilities are demonstrated and compared in detail through two examples. The results indicate that the probability of failure mainly reflects the accuracy of the response surface function (RSF) fitting the performance function in the vicinity of the design point, while the statistical moments of system output response reflect the accuracy of the RSF fitting the performance function in the entire space. In addition, the performance function can be well fitted by the SRSM with an optimal order polynomial chaos expansion both in the entire physical and in the independent standard normal spaces. However, it can be only well fitted by the RSM in the vicinity of the design point. For reliability problems involving random variables with approximate normal distributions, such as normal, lognormal, and Gumbel Max distributions, both the probability of failure and statistical moments of system output response can be accurately estimated by the SRSM, whereas the RSM can only produce the probability of failure with a reasonable accuracy.

Hemorheology and clinical application : association of impairment of red blood cell deformability with diabetic nephropathy

  • Shin, Se-Hyun;Ku, Yun-Hee
    • Korea-Australia Rheology Journal
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    • v.17 no.3
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    • pp.117-123
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    • 2005
  • Background: Reduced deformability of red blood cells (RBCs) may play an important role on the pathogenesis of chronic vascular complications of diabetes mellitus. However, available techniques for measuring RBC deformability often require washing process after each measurement, which is not optimal for day­to-day clinical use at point of care. The objectives of the present study are to develop a device and to delineate the correlation of impaired RBC deformability with diabetic nephropathy. Methods: We developed a disposable ektacytometry to measure RBC deformability, which adopted a laser diffraction technique and slit rheometry. The essential features of this design are its simplicity (ease of operation and no moving parts) and a disposable element which is in contact with the blood sample. We studied adult diabetic patients divided into three groups according to diabetic complications. Group I comprised 57 diabetic patients with normal renal function. Group II comprised 26 diabetic patients with chronic renal failure (CRF). Group III consisted of 30 diabetic subjects with end-stage renal disease (ESRD) on hemo-dialysis. According to the renal function for the diabetic groups, matched non-diabetic groups were served as control. Results: We found substantially impaired red blood cell deformability in those with normal renal function (group I) compared to non-diabetic control (P = 0.0005). As renal function decreases, an increased impairment in RBC deformability was found. Diabetic patients with chronic renal failure (group II) when compared to non-diabetic controls (CRF) had an apparently greater impairment in RBC deformability (P = 0.07). The non-diabetic cohort (CRF), on the other hand, manifested significant impairment in red blood cell deformability compared to healthy: control (P = 0.0001). Conclusions: The newly developed slit ektacytometer can measure the RBC deformability with ease and accuracy. In addition, progressive impairment in cell deformability is associated with renal function loss in all patients regardless of the presence or absence of diabetes. In diabetic patients, early impairment in RBC deformability appears in patients with normal renal function.

Insulation Characteristic of Waste Sawdust-mixing Concrete (폐톱밥 혼입 콘크리트의 단열특성에 관한 실험적 연구)

  • Hong, Seung-Ryul;Cho, Byung-Hun;Son, Ki-Sang
    • Journal of the Korean Society of Safety
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    • v.20 no.2 s.70
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    • pp.98-104
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    • 2005
  • Saw dust concrete f3r finding out insulation characteristic was tested using test plate $30cm{\times}30cm{\times}5cm$. basically, molds f3r the test of compressive, tensile, normal without sawdust, $0.05\%,\;0.1\%,\;0.2\%,\; 0.4\%,\;0.6\%,\;0.8\%,\;1.0\%,\;1.2\%,\;1.4\%,\;1.6\%,\;1.5\%,\;2.0\%$, mixing proportion. heat conductivity of the saw dust concrete mixed with the above proportion was taken in this study. Thermal conduction of normal concrete depends on mixing proportion strength aggregate character, water content. all these items are specified here in fables. $1.8\%\~2.0\%$ saw-dust mising concrete shows as the faction as normal insulation material has its function. and the higher saw-dust mixing rate becomes, the thermal conduction becomes the less Then, the conclusions are that saw-dust using concrete has better insulation function than normal concrete.

Self-care Behaviors And Physiological Index According to Cognitive Function of Hemodialysis Patients (혈액투석환자의 인지기능에 따른 자가간호 행위와 생리적 지표)

  • Jang, Yeon-Hwa;Oh, Hyo-Sook;Jang, Geum-Song
    • The Korean Journal of Health Service Management
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    • v.6 no.2
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    • pp.57-69
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    • 2012
  • The purpose of this study was to investigate correlation with self-care behaviors and physiological index according to cognitive function of hemodialysis patients. The data were collected from 108 patients on hemodialysis in university hospital. The period of data collection was from January 4 to January 31, 2010. The instruments of research were MMSE, Self-care behavior scale for hemodialysis patients. The 17.6% of patients showed the cognitive disorder. Self-care behaviors of patients showed that normal cognitive function group was significantly higher than dysfunction group. Creatinine and parathyroid hormone of patients showed that normal cognitive function group was significantly lower than dysfunction group. The cognitive function of patients showed positive correlations with self-care behavior(r=.283, p=.003) and Kt/V(r=.214. p=.026), showed significant negative correlations with phosphorus(r=-.223, p=.020) and creatinine(r=-.318, p=.001). The results of this study can be used to develop nursing education program to improve self-care behaviors according to cognitive function of hemodialysis patients.