• Journal of the Korean Society of Physical Medicine
• /
• v.6 no.2
• /
• pp.127-133
• /
• 2011

Purpose: 본 연구는 단하지 보조기를 사용하는 뇌졸중환자의 시-거리 보행변수에 대한 청각신호 효과에 대한 알아보고자 하는 것이다. Methods: 9명의 뇌졸중환자가 본 연구에 참여하였으며 대상자는 보조기 착용이 없는 경우, 기존 보조기 착용의 경우 그리고 청각신호 보조기 착용의 경우에 각각 시-거리 보행 변수에 대해 측정하였다. 8대의 동작분석 카메라 시스템(Motion Analysis Corporation, Santa Rosa, USA)을 사용하여 시-거리 보행 변수를 측정하였으며 Wilcoxon rank sum test을 이용하여 양하지의 대칭성을 분석하였고 Friedman test를 사용하여 다른 보조기 사용에 따른 효과를 알아보았다. Results: 청각 신호 보조기의 경우, 손상측과 비손상측의 보행속도, 활보장 그리고 분속수가 대칭적으로 되었다. 손상측의 경우, 단하지 보조기를 착용하였을 때가 착용하지 않았을 때보다 대체적으로 보행 변수들이 증가하였다. 청각 신호 단하지 보조기를 착용하였을 때 손상측 하지의 보행 속도, 활보장, 보장, 양하지 지지 시간이 증가하였고 단하지 지지 시간은 감소하였다. Conclusion: 청각 신호 단하지 보조기 착용 시 보행 속도, 활보장, 보장은 보조기를 착용하지 않았을 때보다는 증가하였으나 청각 신호 단하지 보조기와 기존 단하지 보조기 착용 사이에는 차이가 없었다. 하지만, 본 연구의 결과는 청각 신호 단하지 보조기가 뇌졸중 환자의 시-거리 보행 변수를 개선할 수 있음을 보여주었고 앞으로 다양한 보행 변수들에 대한 연구가 필요하다고 생각한다.

• Communications for Statistical Applications and Methods
• /
• v.15 no.6
• /
• pp.843-858
• /
• 2008

BLS adjustment methods have been able to provide more accurate estimates of total and make samples represent population characteristics by post-adjustment of design weights of samples. However, BLS methods use additional data, for instance number of employee, without this information or using other information, give different weight adjustment factors. In this paper we studied the sensitivity of the variables used in BLS adjustment. The 2007 monthly labor survey data is used in analysis.

• Communications for Statistical Applications and Methods
• /
• v.18 no.1
• /
• pp.47-55
• /
• 2011

Ratio and regression imputations depend on the model of a survey variable and the relation between the survey variable and auxiliary variables. If the model is not true, the unbiasedness of the estimator using the ratio or regression imputation cannot be guaranteed. In this paper, we develop the doubly robust imputation, which satisfies the approximate unbiasedness of the estimator, whether the model assumption is valid or not. The proposed imputation increases the efficiency of estimation by using the population information of the auxiliary variables. The simulation study establishes the theoretical results of this paper.

• Proceedings of the Korean Statistical Society Conference
• /
• 2001.11a
• /
• pp.63-68
• /
• 2001

조사과정에서 필연적으로 발생하는 무응답을 보정하기 위해 보조정보를 사용한다. 이 때, 이용 가능한 보조정보의 차원이 크면, 계산과정에서 많은 시간이 소요되며 데이터를 다루기가 매우 어렵다. 또한 추정량의 분산이 보조정보의 차원에 의존하기 때문에 과소추정의 문제가 발생한다. 이러한 문제를 해결하기 위해 무응답 보정에서 적절한 보조정보의 선택 방법을 제안하였고, 이에 대한 효율성을 모의실험을 통해 살펴보았다.

• Tunnel and Underground Space
• /
• v.26 no.3
• /
• pp.201-211
• /
• 2016

A method for estimating rock joint size distribution using contained traces length distribution from 3D cylindrical window survey was suggested. To reduce the numerical error, an improved technique was applied. The accuracy was verified by referring to Monte-Carlo simulation and it was found that the error can be decreased with suitable gamma values.

• The Korean Journal of Applied Statistics
• /
• v.30 no.6
• /
• pp.993-1004
• /
• 2017

A stratified sampling method is generally used with a sample selected using the same sample weight in each stratum in order to improve the accuracy of the sampling survey estimation. However, the weight should be adjusted to reflect the response rate if the response rate is affected by the value of the variable of interest. It may be also more effective to adjust the weights by subdividing the stratum rather than using the same weight if the variable of interest has a linear relationship with the continuous auxiliary variables. In this study, we propose a method to increase the accuracy of estimation using an informative sampling design technique when the response rate is an exponential function of the variable of interest and the variable of interest has a linear relationship with the auxiliary variable. Simulation results show the superiority of the proposed method.

• Proceedings of the Korean Statistical Society Conference
• /
• 2002.05a
• /
• pp.13-18
• /
• 2002

이중추출(two-phase)접근방법 이용의 주목적은 관심변수와 보조변수사이의 관계를 이용해서 더 좋은 추정을 하고자 하는 것이다. 특히 이 방법은 층화, 무응답 문제에 적용하는 경우 상당히 효과적이다. 본 논문에서는 무시할 수 있는 무응답이 발생했을 때 이중추출기법을 이용해서 g-가중치와 응답확률을 각 단계별로 조정해줌으로써 무응답 보정추정량과 분산추정량을 구했다.

• Survey Research
• /
• v.5 no.2
• /
• pp.49-70
• /
• 2004

This paper is a broad review about general regression estimators, which are very useful when auxiliary variables are available in survey sampling. We investigate the process of development of general regression estimators from birth to suggestion of variance estimation method and examine some properties of general regression estimators by comparing with calibration and QR estimators. We also present some forms of general regression estimators available under complex sampling designs such as stratified sampling and cluster sampling. Finally, we comment some advantages as well as disadvantages of general regression estimators and theoretical and practical development in the future.

• The Korean Journal of Applied Statistics
• /
• v.16 no.1
• /
• pp.33-44
• /
• 2003

Typically, it should be use auxiliary variable for calibrating the survey nonreponse in census or sampling survey. Where, if the dimension of auxiliary information is large, then it nay be spend a lot of computing time, and difficult to handle data set. Also because the variance estimator depends on the dimension of auxiliary variables, the variance estimator becomes underestimator. To deal with this problem, we propose the variable selection methods for calibration estimation procedure in unit nonreponse situation and we compare the efficiency by simulation study.

• Journal of the Korean Society of Radiology
• /
• v.16 no.5
• /
• pp.505-512
• /
• 2022

In this study, a 3D printed assistive device was applied to X-ray examinations to diagnose human diseases. Based on the results of evaluating the device, statistical and regression analyses were conducted to evaluate its clinical utility and purchase intention, respectively. In the experiment, 90 radiologists performed X-ray examinations on patients who agreed with the use of the assistive device in oblique view X-rays of the lumbar spine, and then statistical analyses were undertaken with a traditional aid and factor analysis. The non-standardized coefficient values of the multiple regression analysis performed by setting the purchase intention of the 3D printed device as the dependent variable and the 3D printed device and traditional aid calculated by factor analysis as independent variables were 0.893 (p<0.001) and 0.269 (p<0.001), indicating statistically significant results. The results show that the 3D printed assistive device proposed in this study has higher clinical utility than traditional aids used in oblique view X-rays of the lumbar spine.