• 제목/요약/키워드: K-point

검색결과 28,023건 처리시간 0.046초

What Is the Ideal Entry Point for Transforaminal Endoscopic Lumbar Discectomy?

  • Lee, Jong Un;Park, Ki Jeoung;Kim, Ki Hong;Choi, Man Kyu;Lee, Young Hwan;Kim, Dae-Hyun
    • Journal of Korean Neurosurgical Society
    • /
    • 제63권5호
    • /
    • pp.614-622
    • /
    • 2020
  • Objective : The method of approach during transforaminal endoscopic lumbar discectomy (TELD) has been the subject of repeated study. However, the ideal entry point during TELD has not been studied in detail. Therefore, this study investigated the ideal entry point for avoiding complications using computed tomography (CT) scans obtained from patients in the prone position. Methods : Using CT scans obtained from patients in the prone position, we checked for retroperitoneal or visceral violations and measured the angles of approach with five conventional approach lines drawn on axial CT scans at each disc space level (L2-3, L3-4, and L4-5). We also determined the ideal entry point distance and approach angles for avoiding retroperitoneal or visceral violations. Correlation analysis was performed to identify the patient characteristics related to the ideal entry point properties. Results : We found that the far lateral approach at the L2-3 level resulted in high rates of visceral violation. However, rates of visceral violation at the L3-4 and L4-5 levels were remarkably low or absent. The ideal angles of approach decreased moving caudally along the spine, and the ideal entry point distances increased moving caudally along the spine. Weight, body mass index (BMI), and the depth of the posterior vertebral line from the skin were positively associated with the distance of the ideal entry point from the midline. Conclusion : We reviewed the risk of the extreme lateral approach by analyzing rates of retroperitoneal and visceral violations during well-known methods of approach. We suggested an ideal entry point at each level of the lumbar spine and found a positive correlation between the distance of the entry point to the midline and patient characteristics such as BMI, weight, and the depth of the posterior vertebral line from the skin.

A NONPARAMETRIC CHANGE-POINT ESTIMATOR USING WINDOW IN MEAN CHANGE MODEL

  • Kim, Jae-Hee;Jang, Hee-Yoon
    • Journal of applied mathematics & informatics
    • /
    • 제7권2호
    • /
    • pp.653-664
    • /
    • 2000
  • The problem of inference about the unknown change-point with a change in mean is considered. We suggest a nonparametric change-point estimator using window and prove its consistency when the errors are from the distribution with the mean zero and the common variance. a comparison study is done by simulation on the mean, the variance, and the proportion of matching the true change-points.

Multiple Structural Change-Point Estimation in Linear Regression Models

  • Kim, Jae-Hee
    • Communications for Statistical Applications and Methods
    • /
    • 제19권3호
    • /
    • pp.423-432
    • /
    • 2012
  • This paper is concerned with the detection of multiple change-points in linear regression models. The proposed procedure relies on the local estimation for global change-point estimation. We propose a multiple change-point estimator based on the local least squares estimators for the regression coefficients and the split measure when the number of change-points is unknown. Its statistical properties are shown and its performance is assessed by simulations and real data applications.

COMMON FIXED POINT THEOREMS FOR HYBRID MAPS IN NON-ARCHIMEDEAN FUZZY METRIC SPACES

  • Samanta, T.K.;Mohinta, Sumit
    • Journal of applied mathematics & informatics
    • /
    • 제31권1_2호
    • /
    • pp.155-164
    • /
    • 2013
  • In this paper, we have established some common fixed point theorems for two pairs of occasionally weakly compatible hybrid maps sat-isfying a strict contractive condition in a non-archimedean fuzzy metric space. Our result extend, generalized and fuzzify several fixed point theo-rems on metric space.

CIRCLE ACTIONS ON ORIENTED MANIFOLDS WITH FEW FIXED POINTS

  • Jang, Donghoon
    • East Asian mathematical journal
    • /
    • 제36권5호
    • /
    • pp.593-604
    • /
    • 2020
  • Let the circle act on a compact oriented manifold with a discrete fixed point set. At each fixed point, there are positive integers called weights, which describe the local action of S1 near the fixed point. In this paper, we provide the author's original proof that only uses the Atiyah-Singer index formula for the classification of the weights at the fixed points if the dimension of the manifold is 4 and there are at most 4 fixed points, which made the author possible to give a classification for any finite number of fixed points.

Some Properties of Sequential Point Estimation of the Mean

  • Choi, Ki-Heon
    • Journal of the Korean Data and Information Science Society
    • /
    • 제16권3호
    • /
    • pp.657-663
    • /
    • 2005
  • Under the minimum risk point estimation formulation of Robbins(1959), we consider the sequential point estimation problem for normal population $N({\theta},\;{\theta})$ with unknown parameter ${\theta}$. In the case of completely unknown ${\theta}$, Stein's(1945) two-stage procedure is known to enjoy the consistency property, but it is not even first-order efficient. In the case when ${\theta}>{\theta}_L\;where\;{\theta}_L(>0)$ is known, the revised two-stage procedure is shown to enjoy all the usual second-order properties.

  • PDF

A Nonparametric Bootstrap Test and Estimation for Change

  • Kim, Jae-Hee
    • Communications for Statistical Applications and Methods
    • /
    • 제14권2호
    • /
    • pp.443-457
    • /
    • 2007
  • This paper deals with the problem of testing the existence of change in mean and estimating the change-point using nonparametric bootstrap technique. A test statistic using Gombay and Horvath (1990)'s functional form is applied to derive a test statistic and nonparametric change-point estimator with bootstrapping idea. Achieved significance level of the test is calculated for the proposed test to show the evidence against the null hypothesis. MSE and percentiles of the bootstrap change-point estimators are given to show the distribution of the proposed estimator in simulation.

Edge Map-Based Fingerprint Reference-Point Detection (에지맵 기반 지문 기준점 검출)

  • Song, Young-Chul
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • 제56권7호
    • /
    • pp.1321-1323
    • /
    • 2007
  • A new reference point location method based on an edge map is proposed, where an orientation map is defined and used to find the edge map. Experimental results show that the proposed method can effectively detect the core point in poor quality and arch-type fingerprint images and produces better results in terms of the detection rate and accuracy than the sine map-based method.