• Title/Summary/Keyword: percentile.

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A Study on the Correlation between Optimal Safety of Structures and Minimization of Life Cycle Cost(LCC) (구조물의 최적안전지수와 생애주기비용의 상관관계에 관한 연구)

  • Bang, Myung-Seok
    • Journal of the Korean Society of Safety
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    • v.29 no.6
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    • pp.94-98
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    • 2014
  • This study was intend to develop the optimal design method of suspension bridge by the reliability analysis based on minimization of life cycle cost(LCC). The reliability analysis was performed considering aleatory uncertainties included in the result of numerical analysis. The optimal design was estimated based on life-cycle cost analysis depending on the result of reliability analysis. As the effect of epistemic uncertainty, the safety index (beta), failure probability (pf) and minimum life cycle cost were random variables. The high-level distributions were generated, from which the critical percentile values were obtained for a conservative bridge design through sensitivity assessment.

Correction of Mean and Extreme Temperature Simulation over South Korea Using a Trend-preserving Bias Correction Method (변동경향을 보존하는 편의보정기법을 이용한 우리나라의 평균 및 극한기온 모의결과 보정)

  • Jung, Hyun-Chae;Suh, Myoung-Seok
    • Atmosphere
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    • v.25 no.2
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    • pp.205-219
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    • 2015
  • In this study, the simulation results of temperature by regional climate model (Reg- CM4) over South Korea were corrected by Hempel et al. (2013)'s method (Hempel method), and evaluated with the observation data of 50 stations from Korea Meteorological Administration. Among the 30 years (1981~2010) of simulation data, 20 years (1981~2000) of simulation data were used as a training data, and the remnant 10 years (2001~2010) data were used for the evaluation of correction. In general, the Hempel method and parametric quantile mapping show a reasonable correction both in mean and extreme climate of temperature. As the results, the systematic underestimation of mean temperature was greatly reduced after bias correction by Hempel method. And the overestimation of extreme climate, such as the number of TN5% and freezing day, was significantly recovered. In addition to that, the Hempel method better preserved the temporal trend of simulated temperature than other bias correction methods, such as the quantile mapping. However, the overcorrection of the extreme climate related to the upper quantile, such as TX5% and hot days, resulted in the exaggeration of the simulation errors. In general, the Hempel method can reduce the systematic biases embedded in the simulation results preserving the temporal trend but it tends to overcorrect the non-linear biases, in particular, extreme climate related to the upper percentile.

Characteristics and Trends of Tropical Night Occurrence in South Korea for Recent 50 Years (1958-2007) (우리나라에서 최근 50년 (1958-2007)간 열대야 발생 특성 및 변화 경향)

  • Park, Woo-Sun;Suh, Myoung-Seok
    • Atmosphere
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    • v.21 no.4
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    • pp.361-371
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    • 2011
  • In this study, characteristics and trends of tropical night (TN) are investigated by using the KMA 14 observation data for the recent 50 years (1958-2007) over South Korea. The TN is defined as a day with a daily minimum temperature exceeds the absolute threshold temperature ($25^{\circ}C$), and the relative deviation from normal temperature, 95th percentile of all observed daily minimum temperature. Although the spatial distribution of TN occurrence depends on the choice of the definitions, the frequency of TN shows strong spatial and interannual variations with the minimum at high land area (Chupungnyeong and wet years) and maximum at southern coastal area and large city area (Jeju, Busan, Seoul, Daegu). Most of TN occurs in August (56%) and July (41%), and the duration date of TN is proportional to the frequency of TN without regard to the definition method. In general, increasing trends are found in the TN time series without regard to the analysis method, but the trends are clearly depending on the analysis period and geographic locations. Decreasing trends are prominent during the most of analysis period, especially until the mid of 1990, whereas strong increasing trends are found during recent 30 years (1988-2007), especially at Jeju, Ulsan, Daegu and Pohang. Also the severity of TN is significantly increased in recent years.

A Study on Test for New Better than Used of an unknown specified age ($NBU-t_0$ Class에 대한 검정법 연구)

  • 김환중
    • Journal of Korean Society for Quality Management
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    • v.29 no.2
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    • pp.37-45
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    • 2001
  • A survival variable is a non-negative random variable X with distribution function F(t) satisfying F(0) : 0 and a survival function F(t): 1-F(t). This variable is said to be New Better than Used of specified age t$_{0}$ if F(x+ t$_{0}$)$\leq$F(x).F(t$_{0}$) for all x$\geq$0 and a fixed t$_{0}$. We propose the test for H$_{0}$ : F(x+t$_{0}$)=F(x).F(t$_{0}$) for all x$\geq$0 against H$_1$: F(x+t$_{0}$) $\leq$ F(x).F(t$_{0}$) for all x$\geq$0 when the specified age to is unknown but can be estimated from the data when t$_{0}$$_{p}$, the pth percentile of F. This test statistic, which is based on the normalized spacings between the ordered observations, is readily applied in the case of small sample. Also, our test is more simple than Ahmad's test (1998). Finally, the performance of our test is presented.our test is presented.

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The Optimal Spacing of Speed Humps in Traffic Calming Areas (교통정온화 구역 과속방지턱 최적 설치간격)

  • Yeo, Insoo;Baek, Jung-Gil;Choi, Jang-Won;Kim, Yong Seok
    • International Journal of Highway Engineering
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    • v.15 no.3
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    • pp.151-157
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    • 2013
  • PURPOSES : This study aims to suggest the optimal spacing between speed humps which is placed at traffic calming areas including pedestrian priority zones, school zones, and residential areas. METHODS: The study measured the operating speed of vehicles passing through two successive humps by using laser gun in 0.2 seconds interval, and analysed the basic statistical characteristics of speeds data to have an insight on the relationship between spacing and speed. Assumption was made to derive the maximum spacing within which two successive humps influence each other. RESULTS: The statistically significant model explaining the relationship between spacing and 85th percentile speed of vehicles was derived as well as the maximum spacing maintained in order to take the benefits of successive installation of humps. CONCLUSIONS: Spacing of 20 meters was suggested to achieve the widely accepted target speed of 30 km/h in traffic calming zone, and spacing of 70 meters was suggested as a maximum spacing. The comparison across the studies were made and empirical reasoning the difference of results between studies was discussed as well as the future studies.

A Study on Analysis of Importance Weights of Riverfront Assessment Items Using Analytic Hierarchy Process - Focused on the Gyeong-An Stream in Gyeonggi Province - (AHP 기법을 이용한 하천 친수공간 평가항목 중요도 분석 연구 - 경기도 경안천을 중심으로 -)

  • Lee, Hyung-Sook
    • Journal of Korean Society of Rural Planning
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    • v.20 no.1
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    • pp.27-36
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    • 2014
  • The purposes of this study are to identify assessment items to evaluate riverfront for amenity and recreation and to analyze the relative importance of the items using Analytic Hierarchy Process(AHP). Total 15 items of 5 categories were identified through literature review and panel discussion. Based on the AHP analysis results, a weighted value was set for each of the layers in the hierachy. 'Ecological Characteristics' (0.333) was rated with the highest weighted value. followed by 'Landscape Characteristics'(0.190) and 'Physical Characteristics'(0.166). Among the assessment items, 'Water Quality' (0.152) and 'River Naturality'(0.118) had higher weighted values. With the set of assessment items field assessments were carried out for Gyung-An Stream of Gyeonggi-Do to exam its applicability. Total 6 segments and 31 reaches out of the 22.5 km long river were evaluated and the mean scores of the five categories were converted into a percentile score for comparison. Overall, the segments which had higher scores were located close to neighborhood areas and had better connections with other historical and cultural amenities. Also, existing facilities was an important factor and needs to be considered for waterfront development.

Open Heart Surgery of Infants Uunder 10kg of Body Weight (체중 10kg 이하 영아에서의 개심술)

  • 박성동
    • Journal of Chest Surgery
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    • v.28 no.5
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    • pp.447-452
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    • 1995
  • From January 1983 to December 1992, 116 patients under 10Kg of body weight were underwent open heart surgery in National Medical Center.There were 64 males and 52 females, and their mean age was 14 2.6 months, ranged from 3 days to 38 months. Their mean body weight was 7.4$\pm$1.2Kg, ranged from 2.4Kg to 10Kg which were less than 3 percentile of normal developmental pattern in 109 out of 116 cases.The composition of the patients was VSD[73 , TOF[18 , ASD[8 , ECD[5 , TGA[4 , PS[3 , TAPVC[2 , TA[1 , cardiac rhabdomyoma with ASD[1 , and Ebstein`s anomaly[1 . The overall surgical mortality was 17.2%.In acynotic group, 11 patients died among 91 patients and the mortality was 12.1%, in cyanotic group 9 patients died among 25 patients, the mortality was 36%.The surgical result of patients under 5Kg of body weight was worse than those over 5Kg of body weight. [56.2% versus 11% The surgical result in this period was improved year by year, but poor surgical results in the group of cyanotic, under 5Kg of body weight should be improved by means of more precise preoperative diagnoses, more advanced surgical techniques and more proper postoperative management.

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The Optimization of Passenger Seat Belt Design for Female Passenger (여성 승객을 고려한 동승자석 안전벨트의 설계 최적화)

  • Kim, Yun-Bae;Kim, Hyung-Jun;Han, Jae-Nyung;Kim, Hyung-Il;Chae, Soo-Won
    • Transactions of the Korean Society of Automotive Engineers
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    • v.20 no.4
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    • pp.10-15
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    • 2012
  • The design of automobile occupant seat belt system has been studied by using MADYMO. Based on the FMVSS 208 (Federal Motor Vehicle Safety Standards 208) and the USNCAP (United States New Car Assessment Program) regulations, seat belt design parameters were chosen for the design improvement to the 5th percentile female dummy: limit force of load limiter, time to fire of shoulder belt, inlet length of shoulder belt, inlet length of lap belt. The design of experiment method was employed to optimize the design parameters of passenger seat belt. Range of injury probability due to the change of H-point position was estimated by the simulation.

A Korean-American Comparative Study of 3D Scanned Female Anthropometric Data

  • Yi, Kyonghwa;Cynthia, L. Istook
    • Journal of Fashion Business
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    • v.17 no.3
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    • pp.74-84
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    • 2013
  • The purpose of this research is to provide useable data for application in American and Korean apparel company. This data was developed by analyzing information of Korean and American body sizes obtained from "Size USA Project" and "Size Korea Project". The Subjects were 6,306 American females and 1,988 Korean females over 18 years old. 30 measurements and 14 computed values were chosen that were considered critical in making garments. And descriptive analysis, percentile analysis and t-test were used as statistical methods for analyzing measurements and computed value between the two countries. The results were as follows. It was determined that American women were larger and bigger than Korean women in all measurements and computed values, except for Shoulder Slope. Based on BMI values, we determined that American women had a distinct tendency towards being overweight. Through the comparison of drop values (i.e. the difference between Hip and Bust Girths or Hip and Waist Girths), ratio values (i.e. waist height divided by height) and Body Mass Index (BMI) between the two countries, we determined that American women's figures were shapelier than Korean women's. American women had higher hip heights and longer leg lengths for their height compared to Korean woman. Furthermore, the back shapes of Korean women were flatter than American women and BMI values indicated American women were relatively more overweight than Korean women.

A Study on the Size of the Alterated School Uniforms of High School Girls in Cheju and the Level of Their Satisfaction (제주지역 여고생의 교복 변형에 따른 치수 및 교복만족도에 관한 연구)

  • Kwon, Sook-Hee;Kim, Hye-Jung
    • Korean Journal of Human Ecology
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    • v.11 no.4
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    • pp.401-413
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    • 2002
  • The purpose of this study was to survey the high school girls' alteration of school uniforms concerned about both size satisfaction and dissatisfaction and to improve the size of school uniforms. The subjects were 1,007 girls attending high schools in Cheju. The questionnaire survey was done from July 8th to Sep. 21th, 2001. According to the survey, 67.3 percentile of the interviewed girls alterated their uniforms. It was appeared that they alterated skirts more than blouses as a way of shortening. The main reason of alteration is ill-fitting uniforms, most of girls had a positive idea to alterate uniforms. Dissatisfaction of uniforms is mainly caused by the large size not by the small size. It was appeared that dissatisfaction rate of skirt was higher than that of blouse. The large part of dissatisfaction was appeared on waist circumference of blouse and hem circumference of skirt. The girls who experienced alterating the part of uniforms such as waist circumference of skirt, skirt length and hem circumference had high satisfaction rate. And a result of analyzing the level of satisfaction with uniforms-size-satisfaction/dissatisfaction showed the significant differences in fashion, factors-aesthetics and factors-activity of skirt and blouse.

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