• Title, Summary, Keyword: sign test

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A SIGN TEST FOR UNIT ROOTS IN A SEASONAL MTAR MODEL

  • Shin, Dong-Wan;Park, Sei-Jung
    • Journal of the Korean Statistical Society
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    • v.36 no.1
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    • pp.149-156
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    • 2007
  • This study suggests a new method for testing seasonal unit roots in a momentum threshold autoregressive (MTAR) process. This sign test is robust against heteroscedastic or heavy tailed errors and is invariant to monotone data transformation. The proposed test is a seasonal extension of the sign test of Park and Shin (2006). In the case of partial seasonal unit root in an MTAR model, a Monte-Carlo study shows that the proposed test has better power than the seasonal sign test developed for AR model.

Study of the Influence of Condensation on Road Signs to Drivers (결로 발생 도로표지가 운전자에게 미치는 영향에 관한 연구)

  • Park, Jae Hong;Yun, Duk Geun;Sung, Jung Gon;Kang, Weon Eui
    • International Journal of Highway Engineering
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    • v.15 no.5
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    • pp.187-193
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    • 2013
  • PURPOSES : This research is to analyze the influence in terms of misreading rate and legibility time for drivers when condensation occurs on the road signs. METHODS : In this research, the dew occurred road signs provided to drivers to measure legibility time and misreading rate to compare with normal road sign. In order to identify the difference of legibility time between normal road sign and dew occurred road sign, the T-test and ANOVA test were used. And the vision system was used to recognize the region of dew occurrence on the road sign, then the brightness of dew occurrence region on the road sign was changed to check the misreading rate of drivers according to the change rate of brightness. RESULTS : The legibility times were measured 2.65s for normal road sign and 4.08s for dew occurrence road sign and misreading rates were measured 2.8% for normal road sign, 21.7% for dew occurrence road sign.

Femoral Condyle Cut-off Sign - New Indirect Sign of Radiologic Finding in Knee with Discoid Lateral Meniscus - (대퇴 외과 절삭 징후(cut-off sign) - 원판형 외측 반월상 연골 예에서 나타나는 새로운 단순 방사선 소견 -)

  • Ha Chul-Won;Sung Ki-Sun;Park Jae-Chul
    • Journal of the Korean Arthroscopy Society
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    • v.7 no.2
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    • pp.215-219
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    • 2003
  • Purpose : To report the 'condylar cut-off sign', a new radiographic sign in knees with discoid lateral meniscus and to report the sensitivity, specificity, positive predictive value and negative predictive value of the sign to elucidate the diagnostic significance of the sign for discoid meniscus. Materials and Methods : Fifty knees with complete discoid lateral meniscus and fifty normal knees formed the basis of this study. All of them were arthroscopically confirmed fer the discoid or normal lateral meniscus. The authors developed a method to measure the length of the medial and lateral condylar were compare and analyzed. Results : Tile average ratio was 0.716 in the discoid meniscus group, and 0.902 in the normal group. The stastistical analysis by the T-test revealed the t-value -11.13(p<0.0001). Stastistical analysis by chi-square test using cut point 0.8, also showed significant difference between the two groups, with $76\%$ sensitivity, $100\%$ specificity, $100\%$ positive predictive predictive value and $81\%$ negative predictive value. The 'condylar cut-off sign' was readily detectable in all cases of discoid lateral meniscus, suggesting that the cut off sign could serve as a simple and reliable radiographic sign fur the diagnosis of discoid meniscus. Conclusion : The condylar cut-off sign on the Tunnel view of simple radiography of the knee can serve as a good sign for the diagnosis of discoid lateral meniscus, with $100\%$ positive predictive value.

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Breakdown Points of Direction Tests

  • Park, Kyung-Mee
    • Journal of the Korean Statistical Society
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    • v.26 no.2
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    • pp.211-222
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    • 1997
  • We briefly review three Raleigh type location tests based on direction vectors, which have been shown to be efficient when the distribution is unknown, skewed, or heavy-tailed. Then we calculate their test breakdown points and discuss the robustness of Randles multivariate sign test for one-sample.

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A Study of Non-parametric Statistical Tests to Quantify the Change of Water Quality (수질변화의 계량화를 위한 비모수적 통계 준거에 관한 연구)

  • Lee, Sang-Hoon
    • Journal of Environmental Impact Assessment
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    • v.6 no.1
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    • pp.111-119
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    • 1997
  • This study was carried out to suggest the best statistical test which may be used to quantify the change of water quality between two groups. Traditional t-test may not be used in cases where the normality of underlying population distribution is not assured. Three non-parametric tests which are based on the relative order of the measurements, were studied to find out the applicability in water quality data analysis. The sign test is based on the sign of the deviation of the measurement from the median value, and the binomial distribution table is used. The signed rank test utilizes not only the sign but also the magnitude of the deviation. The Wilcoxon rank-sum test which is basically same as Mann-Whitney test, tests the mean difference between two independent samples which may have missing data. Among the three non-parametric tests studied, the singed rank test was found out to be applicable in the quantification of the change of water quality between two samples.

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DISTRIBUTiON-FREE TWO-SAMPLE TEST ON RANKED-SET SAMPLES

  • DONG HEE KIM;YOUNG CHEOL KIM;MYUNG HWA CHO
    • Communications for Statistical Applications and Methods
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    • v.5 no.1
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    • pp.133-144
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    • 1998
  • In this paper, we propose the two-sample test statistic using Wilcoxon signed rank test on ranked-set sampling(RSS) and obtain the asymptotic relative efficiencies(ARE) of the proposed test statistic with respect to Mann-Whitney-Wilcoxon statistic on simple random sampling(SRS), the Mann-Whitney-Wilcoxon statistic on RSS, sign statistic on RSS and Wilcoxon signed rank test on SRS. From the simulation works, we compare the powers of the proposed test statistic, Mann-Whitney-Wilcoxon statistic on RSS, the usual two-sample t statistic, sign statistic on RSS, where the underlying distributions are uniform, normal, double exponential, logistic and Cauchy distributions.

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Road Sign Recognition and Geo-content Creation Schemes for Utilizing Road Sign Information (도로표지 정보 활용을 위한 도로표지 인식 및 지오콘텐츠 생성 기법)

  • Seung, Teak-Young;Moon, Kwang-Seok;Lee, Suk-Hwan;Kwon, Ki-Ryong
    • Journal of Korea Multimedia Society
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    • v.19 no.2
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    • pp.252-263
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    • 2016
  • Road sign is an important street furniture that gives some information such as road conditions, driving direction and condition for a driver. Thus, road sign is a major target of image recognition for self-driving car, ADAS(autonomous vehicle and intelligent driver assistance systems), and ITS(intelligent transport systems). In this paper, an enhanced road sign recognition system is proposed for MMS(Mobile Mapping System) using the single camera and GPS. For the proposed system, first, a road sign recognition scheme is proposed. this scheme is composed of detection and classification step. In the detection step, object candidate regions are extracted in image frames using hybrid road sign detection scheme that is based on color and shape features of road signs. And, in the classification step, the area of candidate regions and road sign template are compared. Second, a Geo-marking scheme for geo-content that is consist of road sign image and coordinate value is proposed. If the serious situation such as car accident is happened, this scheme can protect geographical information of road sign against illegal users. By experiments with test video set, in the three parts that are road sign recognition, coordinate value estimation and geo-marking, it is confirmed that proposed schemes can be used for MMS in commercial area.

Cognitive Model-based Evaluation in Dynamic Traffic System (동적 교통 시스템의 인지공학적 평가에 관한 연구)

  • Kang, Myong-Ho;Cha, Woo-Chang
    • Journal of the Ergonomics Society of Korea
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    • v.21 no.3
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    • pp.25-34
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    • 2002
  • The road sign in dynamic traffic system is an important element which affects on human cognitive performance on driving. Web-based vision system simulator was developed to examine the cognition time of the road sign in dynamic environment. This experiment the cognition time of the road sign in dynamic environment. This experiment was designed in with-subject design with two factors: vehicle speed and the amount of information of the traffic sign. It measured the cognition time of the road sign through two evaluation methods: the subjective test with vision system simulator and computational cognitive model. In these two evaluations of human cognitive performance under the dynamic traffic environment, it demonstrated that subject's cognition time was affected by both the amount of information of traffic sign and driving speed.

A Note on the Median Control Chart

  • Park, Hyo-Il
    • Communications for Statistical Applications and Methods
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    • v.20 no.2
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    • pp.107-113
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    • 2013
  • This study reviews several well-known control charts for the location parameter with a discussion of the relationship between the maintenance of the control chart and a series of hypotheses testing. As a by-product, we then propose a new median control chart with the sign test statistic. We also modify the nonparametric control charts to easily understand the relation. Then we illustrate the construction of several median control charts with the industrial data and compare the efficiency among several control charts. Finally, we discuss some interesting features for the median control charts as concluding remarks.