• Journal of Korean Society of Industrial and Systems Engineering
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• v.16 no.28
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• pp.137-143
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• 1993

Generally there are three methods to derive an approximation formula: 1) approching standard normal distribution by appropriate changing variable 2) using standardization variable for expansion 3) deriving approximation formula by direct method. This paper present correction terms having the form of $C_{1/v^{n/2}}/{\;}+{\;}C_2{\;}(n=1,2)$ with respect to $x^2_{\alpha}(v)$ distribution (${\nu}{\;}{\leq}{\;}30$), which minimize the error by EDA method and least square method.

• The Korean Journal of Applied Statistics
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• v.32 no.1
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• pp.99-109
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• 2019

We compared the confidence intervals of estimators using various bootstrap methods for a Random Coefficient Autoregressive(RCA) model. We consider a Quasi score estimator and M-Quasi score estimator using Huber, Tukey, Andrew and Hempel functions as bounded functions, that do not have required assumption of distribution. A standard bootstrap method, percentile bootstrap method, studentized bootstrap method and hybrid bootstrap method were proposed for the estimations, respectively. In a simulation study, we compared the asymptotic confidence intervals of the Quasi score and M-Quasi score estimator with the bootstrap confidence intervals using the four bootstrap methods when the underlying distribution of the error term of the RCA model follows the normal distribution, the contaminated normal distribution and the double exponential distribution, respectively.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.1
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• pp.34-39
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• 2013

In this study, the quantitative analysis and pattern analysis of the error bounds with respect to recording period were carried out using the wave climate data from coastal areas. Arbitrary recording periods were randomly sampled from one month to six years using the bootstrap method. Based on the analysis, for recording periods less than one year, it was found that the error bounds decreased rapidly as the recording period increased. Meanwhile, the error bounds were found to decrease more slowly for recording periods longer than one year. Assuming the absolute estimate error to be around 10% (${\pm}0.1m$) for an one meter significant wave height condition, the minimum recording period for reaching the estimate error for Sokcho and Geoje-Hongdo stations satisfied this condition with over two years of data, while Anmado station was found to satisfy this condition when using observational data of over three years. The confidence intervals of the significant wave height clearly show an increasing pattern when the percentile value of the wave height increases. Whereas, the confidence intervals of the mean wave period are nearly constant, at around 0.5 seconds except for the tail regions, i.e., 2.5- and 97.5-percentile values. The error bounds for 97.5-percentile values of the wave height necessary for harbor tranquility analysis were found to be 0.75 m, 0.5 m, and 1.2 m in Sokcho, Geoje-Hongdo, and Anmado, respectively.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.4
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• pp.18-30
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• 2010

As the automobile industry is developing, the number of deaths and injuries has increased. To reduce the damages from automobile accidents, the government of each country proposes experimental conditions for reproducing the accident and establishes the vehicle safety regulations. Automotive manufacturers are trying to make safer vehicles by satisfying the requirements. The Hybrid III crash test dummy is a standard Anthropomorphic Test Device (ATD) used for measuring the occupant's injuries in a frontal impact test. Since a real crash test using a vehicle is fairly expensive, a computer simulation using the Finite Element Method (F.E.M.) is widely used. Therefore, a detailed and robust F.E. dummy model is needed to acquire more accurate occupant injury data and behavior during the crash test. To achieve this goal, a detailed F.E. model of the Hybrid III 5th percentile female dummy is constructed by using the reverse engineering technique in this research. A modeling process is proposed to construct the F.E. model. The proposed modeling process starts from disassembling the physical dummy. Computer Aided Design (CAD) geometry data is constructed by three-dimensional (3-D) scanning of the disassembled physical dummy model. Based on the geometry data, finite elements of each part are generated. After mesh generation, each part is assembled with other parts using the joints and rigid connection elements. The developed F.E. model of dummy is simulated based on the FMVSS 572 validation regulations. The results of simulation are compared with the results of physical tests.

• Clinical and Experimental Pediatrics
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• v.51 no.9
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• pp.998-1006
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• 2008

Purpose : Hypertension is defined as average systolic blood pressure and/or diastolic blood pressure that is ${\geq}95^{th}$ percentile for gender, age, and height on ${\geq}three$ occasions. Knowing that blood pressure values increase in children as they grow older, the purposes of this study were to measure blood pressure by an oscillometric device and to determine normal values and percentile curves for children. Methods : Systolic and diastolic blood pressures were measured twice with an oscillometric device in 3,545 boys and 3,145 girls under six years of age, in Seoul. Using this data, we determined average blood pressure values and percentile curves based on gender and age; we subdivided these values into blood pressures of $50^{th}$, $90^{th}$, $95^{th}$, and $99^{th}$ percentiles, by percentile of height. The regression coefficients and standard deviations of the systolic and diastolic blood pressure values were obtained from linear regression models. Results : Older boys and girls had higher systolic and diastolic blood pressure values. Older boys and girls in the same percentile of height for age had higher systolic and diastolic blood pressure values. Taller boys and girls within the same age group had higher systolic and diastolic blood pressure values. Conclusion : Blood pressure standards based on gender, age, and height were obtained via an oscillometric method. Llimitation of this study is that the study population was not from the whole country, but exclusively from Seoul. Nonetheless, the data from this study will be helpful in diagnosing and managing hypertension in Korean children.

• Clinical and Experimental Pediatrics
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• v.50 no.8
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• pp.732-739
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• 2007

Purpose : A universal standard of the birth weight for gestational age cannot be made since birth weight distribution varies with races, nations and eras. This report aims to establish the birth weight for gestational age patterns by sex, plurality, and parity, specific for Korean live births. Methods : The national birth certificate data of all live births in Korea from January 2000 to December 2004 were used: for live births with gestational age 24 weeks to 42 weeks (n=2,585,5160), mean birth weight, standard deviation and 10th, 25th, 75th and 90th percentile values were obtained for each gestational age group by one week increment. To establish final standard values of Korean birth weight distribution by gestational age, the finite mixture model to eliminated erroneous birth weights was used for respective gestational age. Same as above method the birth weight for gestational age standard by sex, plurality, and parity were completed. Results : The male newborns are more heavier than female during the entire gestational age. The singletons are more heavier than twin during the entire gestational age. The para 2 are more heavier than the para 1 during the entire gestational age. Korean standard was more heavier in 10th and 50th percentile than Lubchenco's standard. Alexander's standard was more heavier in 50th and 90th percentile than Korean standard. Conclusion : These birth weight for gestational age patterns by sex, plurality, and parity are similar to the other standards. I hope that for Korean infants, this curve will help clinicians in defining and managing the large for gestational age infants and also for infants with intrauterine growth retardation.

• Journal of the Ergonomics Society of Korea
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• v.21 no.2
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• pp.47-58
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• 2002

This research suggested the mathematical model (forward kinematics method) to provide the reference points of driver space more easily and accurately in designing the package layout of vehicle interiors. For this purpose, the lengths of body segments of drivers and various joint angles occurred while were used. The length data between joints for the mathematical model were extracted from $SAFEWORK^{\circed{R}}$ as well as 95th percentile male and 5th percentile female body dimensions were utilized. In addition, the angles of body segments were applied on its diverse values within proper ranges in order to compare them each other. the mathematical model in this study was based on the concept of converting polar coordinate system to Cartesian coordinate system so that reference points of driver space were acquired in Cartesian coordinate system after using the segment lengths of drivers and the joint angles of driving postures as an input of polar coordinate system. It is expected that reference points of driver space obtained from this research are helpful to the study on package layout that is appropriate for physical characteristics of drivers.

• Journal of Korean Academy of Nursing
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• v.36 no.2
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• pp.265-277
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• 2006

Purpose: The study attempted to find family perception differences between abused children and normal children by Kinetic Family Drawing. Method: The subjects of the study consisted of two groups, 143 abused who were in the upper 25th percentile, and 150 normal who were in the lower 25th percentile. Collected Kinetic Family Drawings were divided into five dimensions such as actions, human figure characteristics, dynamics, styles and symbols, and they was analyzed with SPSS/WIN 10.0. Results: In the perception about their family in action dimension, their family in figure characteristics dimension, their family in dynamics dimensions, and their family in symbols dimension, there is a sharp contrast between the two groups. Conclusion: Putting these results together, abused children feel lower self-esteem and feel more sense of alienation in their family than normal children do. In addition, abused children perceive their parents as negative and aggressive people.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.735-741
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• 2011

In the early phase of vehicle development, CAE is conducted as tool for vehicle performance assessment. To maintain acceptable road noise performance, solution for reduced vehicle sensitivity is required. Chassis interface dynamic stiffness characteristics are key component to isolating vibration and noise of road from the vehicle interior. This research provide how to set up the optimized dynamic characteristics under noise effect through DFSS study. CAE-based DOE is performed to build prediction math model, CMS process involves DOE to achieve very fast run times while giving results very comparable. Minimized $95^{th}$ percentile of performance distribution is applied to minimize vehicle sensitivity and road noise levels variation during the optimization process. Finally, the results of optimization were reviewed for performance and robustness.

• Journal of Korean Institute of Industrial Engineers
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• v.26 no.3
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• pp.257-264
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• 2000

This research suggested a method by which the driver space can be designed to best accommodate the driver's anthropometric characteristics. Three-dimensional manikins and a variable seating buck were developed and used for this study. Manikins were designed with 18 links comprising the 95th percentile male and 5th percentile female data. The seating buck was built to create various driving environments using the distance and the height between the H-point(hip pivot) of the seat and the AHP(accelerator heel point), the angle of the back rest, the angle of the steering wheel, the vertical distance of the steering wheel, and the location of the T.G.S.(transmission gear shift) knob. Measurements of each variable were collected with a coordinate measuring machine by positioning the 3-D manikin under various combinations of the design factors of the seating buck, which was constructed based on mid-size domestic passenger cars. The data were then converted to the joint angles of the driver. The combination of the measurements for an optimal driving environment is suggested by applying sets of the joint angles at which the driver feels comfortable.