• Title, Summary, Keyword: Standard Deviation

Search Result 4,662, Processing Time 0.082 seconds

Variable Sampling Interval $\bar{X}$ Control Chart Using Weighted Standard Deviation Method (가중표준편차를 이용한 가변표본채취간격 $\bar{X}$ 관리도)

  • Chang, Youngsoon
    • Journal of the Korean Operations Research and Management Science Society
    • /
    • v.39 no.1
    • /
    • pp.1-12
    • /
    • 2014
  • This article proposes a variable sampling interval (VSI) $\bar{X}$ control chart using weighted standard deviation (WSD) method for skewed populations. The WSD method decomposes the standard deviation of a quality characteristic into upper and lower deviations and adjusts control limits and warning limits of a control chart in accordance with the direction and degree of skewness. A control chart constant is derived for estimating the standard deviation of skewed distributions with the mean of sample standard deviations. The proposed chart is compared with the conventional VSI $\bar{X}$ control chart under some skewed distributions. Simulation study shows that the proposed WSD VSI chart can control the in-control average time to signal (ATS) as an adequate level better than the conventional VSI chart, and the proposed chart can detect a decrease in the process mean of a quality characteristic following a positively skewed distribution more quickly than the standard VSI chart.

Character Segmentation in a Grayscale Image using the Standard Deviation (그레이스케일 영상에서 표준 편차를 이용한 문자 분할)

  • Jung, Min Chul
    • Journal of the Semiconductor & Display Technology
    • /
    • v.11 no.2
    • /
    • pp.27-31
    • /
    • 2012
  • This paper proposes a new method of character segmentation in a grayscale image using the standard deviation. Firstly, the proposed method scans vertically the region of interest in an image in order to calculate a standard deviation for each scan line. Characters' standard deviations are much bigger than the background's. Therefore, it is possible to segment characters vertically using the differentiation of those two types of standard deviations. Secondly, the method scans each vertically segmented image horizontally at this time, and then segments each image similarly. The proposed method is implemented using C language in an embedded Linux system for a high-speed real-time image processing. Experiments were conducted by using credit card images. The results show that the proposed algorithm is quite successful for most credit cards. However, the method fails in some credit cards with strong background patterns.

Estimation of Unknown Parameters in Optimum Allocation

  • Park, Hyeonah;Park, Seunghwan;Na, Seongryong
    • Communications for Statistical Applications and Methods
    • /
    • v.20 no.2
    • /
    • pp.137-145
    • /
    • 2013
  • The use of pooled standard deviation can reduce the efficiency loss in optimum allocation when strata standard deviations are estimated and several of them are equal. Also shown is that the pooled standard deviation is useful in optimum allocation under a multivariate setting. In addition to theoretical development, we provide the result of simulation study to support the theory.

A Distcussion on the Size Deviation Test of Raw Silk (生絲纖度檢査規定에 關한 考察)

  • Choi, Jin-Sub
    • Journal of Sericultural and Entomological Science
    • /
    • v.25 no.1
    • /
    • pp.44-50
    • /
    • 1983
  • The study was carried out to suggest on opinion of the standardization of size deviation in the existing raw silk testing method. 1. The present grade A of size deviation stipulates 4.61 to 5.80 of standard deviation for 50 to 69 denier of mean value, however, the 5.80 standard deviation with the mean values of 50 and 69 denier belong to different distribution. 2. It is reasonable that the variation coefficients of grade 2A should be lower than that of grade A. However, the present testing method shows larger variation in grade 2A than in grade A. This is illustrated 9.00 for 69 denier in grade 2A and 8.41 for 70 denier in grade A. 3. The size deviation value compares the quality of raw silk with different mean value. Therefore, the standard deviation is recommended to be replaced by the C.V. value in determining the grade of silk. 4. The C.V. have a tendency to increase with lower grades below 6A for the size deviation below 33 denier with some inconsistencies. The figures should be adjusted so that the C.V. inconsistencies size deviation below 33 denier will be corrected. 5. The standard deviation increases with size under the same grade for the size deviations above 33 denier, however, the C.V. does not vary greatly with size deviation. 6. To rectify the above-mentioned inconsistencies the C.V. conversion and curvilinear regresion correction is recommended to improve the present silk testing method 7. The table of size deviation standard are as follows: Suggested standard of size deviation, unit: C.V. Value

  • PDF

Comparison of Accuracy and Output Waveform of Devices According to Rectification Method (정류방식에 따른 장치의 정확도와 출력 파형의 비교)

  • Lee, In Ja
    • Journal of radiological science and technology
    • /
    • v.41 no.6
    • /
    • pp.603-610
    • /
    • 2018
  • This study examined the following: accuracy of the exposure conditions in the inverter device and three-phase device; output waveform over the exposure conditions; and average and standard deviation of the output waveform. After assessing whether the dose corresponding to the theoretical dose was presented, the following conclusions were obtained: 1. The accuracy of the tube voltage(kVp) and tube current(mA) exposure time(sec) was within the tolerable level prescribed in Korea's Safety Management Standards. In the error, Inverter device was large the tube voltage and exposure time, the three-phase device was large the tube current. 2. In terms of the output waveform of the exposure conditions and the average and standard deviation of the output waveform, the higher tube voltage and larger tube current resulted in greater standard deviation in pulsation. Moreover, the standard deviation of pulsation was shown to be greater in the inverter device than the three-phase device; there was also greater standard deviation in the inverter device considering the exposure time. 3. Regarding the exposure conditions over the output dose, all linearity showed the coefficient of variation which had an allowable limit of error within 0.05. Although the output dose ratio for the inverter device was 1.00~1.10 times no difference that of the three-phase device, there was almost no difference in dose ratio between the tube currents.

The Consideration of Consistent Use of Sample Standard Deviation in the Confidence Interval Estimation of Population Mean and Population Ratio (모평균과 모비율의 구간추정에서 표본표준편차의 일관된 사용에 대한 고찰)

  • Park, Sun Yong;Yoon, Hyoung Seok
    • Journal of Educational Research in Mathematics
    • /
    • v.24 no.3
    • /
    • pp.375-385
    • /
    • 2014
  • This study compares the confidence interval estimation of population mean with that of population ratio, and considers whether these two estimations ensures consistency. As a result, this study suggests the following acquisition method of consistency : dealing with population mean and population ratio in the same mode, substituting the observed or experimental value of sample standard deviation for standard deviation in population in setting a confidence interval of both population mean and population ratio, and distinguishing population ratio $\hat{P}$ from its observed vale $\hat{p}$.

  • PDF

A Study on the Application of a Dementia Prevention Program and Its Effect Test (치매예방 프로그램 운영 및 효과검증 연구)

  • Hwang, Ok-Nam;Yoon, Sook-Rye;Hwang, Hye-Yeon;Nam, Ki-Seok
    • The Korean Journal of Rehabilitation Nursing
    • /
    • v.5 no.2
    • /
    • pp.156-165
    • /
    • 2002
  • The objective of this study was to apply a dementia prevention program to the subjects who were suspected of dementia and test its effect. This study was one group pretest-posttest design. The dementia prevention program was applied for 20 weeks to the 19 subjects who were suspected of dementia after a screen test among 638 subjects enrolled in 10 senior citizen's centers in G city. The scores of self-efficacy, cognition, quality of life were measured before and after the program. The data collected were analyzed using a SPSS (statistical analysis system) program, and frequencies, averages and standard deviations were obtained. The differences of the scores of the pretest and posttest were analyzed with Mann-Whitney test and sign test. The results were as follows: 1. After the program, the average score of self-efficacy was increased from 75.31 (standard deviation 11.99) to 84.26 (standard deviation 13.92). 2. There are no differences between the average scores of physical and psychological quality of life, however, the average score of social quality of life was slightly increased from 2.25 (standard deviation 0.40) to 2.53 (standard deviation 0.43), and the overall score of social quality of life was low. 3. The average score of cognition was significantly increased from 21.00 (standard deviation 2.60) to 24.58 (standard deviation 3.37), thus, it was found that the program was effective to improve the cognition level. 4. The score differences of self-efficacy, quality of life, cognition between the pretest and posttest were statistically significant. 5. The score differences of quality of life between the pretest and posttest were found to be dependent on marital status, exercise and regular checkup yes or no. In conclusion, the program was effective to prevent the subjects suspected of dementia from dementia.

  • PDF

Development of a Femur Neck Bone Mineral Density Measuring Device for Accurate Examination

  • Han, Man-Seok;Seo, Sun-youl;Kim, Yong-Kyun;Jeon, Min-Cheol;Lee, Hyun-kuk;Yoo, Se-Jong
    • Journal of Magnetics
    • /
    • v.21 no.2
    • /
    • pp.298-302
    • /
    • 2016
  • In bone density examinations, a change in the measured BMD occurs owing to the differences between the measured areas. To address this problem, we aimed to develop a new auxiliary device that could be rotated by $15^{\circ}$ by fixing the ankle to the distal femur neck. Dual energy X-ray absorptiometry (DXA) of BMD examinations were performed once a year, but 10 patients were examined over three sessions to analyze the area for measuring the femur neck BMD. The goal of this test was to determine the device's reliability, and the results were expressed in terms of the standard deviation of measurements. After performing bone density measurements using the new auxiliary device on 10 normal patients, with three measurements for each patient, the obtained standard deviation was 0.03. The standard deviation of the measured BMD was 0.19 when using the currently existing auxiliary device, while the standard deviation of the measured BMD was 0.03 when using the new auxiliary device. By using the new auxiliary device, the standard deviation could be reduced by ~80%. Accurate rotation of the femur neck was possible in all examinations, and the standard deviation of BMD measurements could be reduced by up to 80% compared with the measurements performed using the currently existing auxiliary device. We hope that this advantageous new design can be used as a standard auxiliary device for measuring the femur neck BMD.

A Study on the Track Irregularity Index for the Estimation of Track Quality (궤도품질평가를 위한 궤도틀림 지표에 대한 연구)

  • 오지택;한승용
    • Proceedings of the KSR Conference
    • /
    • /
    • pp.450-457
    • /
    • 2000
  • This paper establishes a scheme to estimate track quality using standard deviation and deterioration rate of track irregularities. To provide index of quality, standard deviation and deterioration rate of track irregularities are analyed. As an index, standard deviation and deterioration rate were applied to decision of corrective maintenance and replacement maintenance, respectively. Further, this paper proposes a basic scheme for a modernization of mechanize track maintenance that using MTT(Multiple Tie Tamper) and Ballast Cleaner.

  • PDF

Effect of Mixing Ratios of Active Ingredient on Content Uniformity of Tablets (주약의 혼합비율이 정제의 함량균일성에 미치는 영향)

  • 김길수
    • YAKHAK HOEJI
    • /
    • v.31 no.5
    • /
    • pp.343-346
    • /
    • 1987
  • The effect of mixing ratios of active ingredient on the content uniformity of tablets was studied using caffeine as active ingredient and hydroxypropyl starch as diluent. In the case that caffeine content was not more than 1%, the standard deviation of individual tablet assays was inversely proportional to caffeine content. In the case of more than 1%, the standard deviation was constant independently of caffeine content. In the case that the designed tablet weight was not more than 200mg, the standard deviation of individual tablet assays was inversley proportional to tablet weight designed. In the case of more than 200mg, it was constant and the results for weight variation against the designed weight showed same tendency.

  • PDF