• The Korean Journal of Applied Statistics
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• v.27 no.7
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• pp.1229-1241
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• 2014

Most of sampling surveys have outliers and non-response missing values simultaneously. In that case, due to the effect of outliers, the result of imputation is not good enough to meet a given precision. To overcome this situation, outlier treatment should be conducted before imputation. In this paper in order for reducing the effect of outlier, we study outlier imputation methods and outlier weight adjustment methods. For the outlier detection, the method suggested by She and Owen (2011) is used. A small simulation study is conducted and for real data analysis, Monthly Labor Statistic and Briquette Consumption Survey Data are used.

• The Korean Journal of Applied Statistics
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• v.26 no.4
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• pp.635-647
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• 2013

Imputation is a commonly used method to handle missing survey data. The performance of the imputation method is influenced by various factors, especially an outlier. The removal of the outlier in a data set is a simple and effective approach to reduce the effect of an outlier. In this paper in order to improve the precision of multiple imputation, we study a imputation method which reduces the effect of outlier using various weight adjustment methods that include the removal of an outlier method. The regression method in PROC/MI in SAS is used for multiple imputation and the obtained final adjusted weight is used as a weight variable to obtain the imputed values. Simulation studies compared the performance of various weight adjustment methods and Monthly Labor Statistic data is used for real data analysis.

• Communications for Statistical Applications and Methods
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• v.18 no.3
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• pp.367-376
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• 2011

BLS weight adjustment is a widely used method for business surveys with non-responses and outliers. Recent surveys show that the non-response weight adjustment of the BLS method is the same as the ratio imputation method. In this paper, we suggested a modified BLS weight adjustment method by imputing missing values instead of using weight adjustment for non-response. Monthly labor survey data is used for a small Monte-Carlo simulation and we conclude that the suggested method is superior to the original BLS weight adjustment method.

• Communications for Statistical Applications and Methods
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• v.17 no.6
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• pp.899-907
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• 2010

Several non-response imputation methods are suggested, however, mainly cross-sectional imputations are studied and applied to this analysis. A simple and common imputation method for panel data is the cross-wave regression imputation or carry-over imputation as a special case of cross-wave regression imputation. This study suggests a multiple imputation method combined time series analysis and cross-sectional multiple imputation method. We compare this method and the cross-wave regression imputation method using MSE, MAE, and Bias. The 2008 monthly labor survey data is used for this study.

• The Korean Journal of Applied Statistics
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• v.32 no.6
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• pp.889-898
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• 2019

The problem of missing value imputation for variables in surveys that include item missing becomes complicated if outliers and logical boundary conditions between other survey items cannot be ignored. If there are outliers and boundaries in a variable including missing values, imputed values based on previous regression-based imputation methods are likely to be biased and not meet boundary conditions. In this paper, we approach these difficulties in imputation by combining various robust regression models and multiple imputation methods. Through a simulation study on various scenarios of outliers and boundaries, we find and discuss the optimal combination of robust regression and multiple imputation method.

• Information and Communications Magazine
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• v.31 no.11
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• pp.35-45
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• 2014

주성분 분석 기법(PCA)는 가장 널리 사용되는 데이터 차원 감소 (dimensionality reduction) 기법으로 알려져 있다. 하지만 데이터에 이상점 (outlier)가 존재하는 환경에서는 성능이 크게 저하된다는 단점을 가지고 있다. Rank-Sparsity(Robust PCA) 기법은 주어진 행렬을 low-rank 행렬과 저밀도(sparse)행렬의 합으로 분해하는 방식으로, 이상점이 많은 환경에서 PCA기법을 효과적으로 대체할 수 있는 알고리즘으로 알려져 있다. 본 고에서는 RPCA 기법을 간략히 소개하고, 그의 적용분야, 및 알고리즘에 관한 연구들을 대해서 알아본다.

• Journal of Hospice and Palliative Care
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• v.7 no.1
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• pp.37-48
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• 2004

Purpose: Population using complementary and alternative medicine (CAM) and the cost or it are increasing all over the world. In this study, we investigated the utilization state of CAM in the elderly people during the last 6 months of life. Methods: We found 4,210 persons in Seoul, older than 65 years who received a funeral subsidy from health insurance after death during the latter half of the year, 2001. We stratified them by age and gender and selected 301 persons and surveyed them by questionnaire. Results: 247 persons (83.1%) used at least one of CAM during their last 6 months of life. Diet and Nutrition remedy showed the highest utilatization rate (65.5%), and drug therapies also were much used (29.9%). Utilization rate was higher in female (60%) and according to the cause of death, the highest in a geriatric disease groups, and the lowest in the cancer group. Whole satisfaction to CAM was high with average 4.25 points out of total 6, and adverse effects were almost free with average 5.55 points out of total 6. Satisfaction was the highest in Diet and Nutrition remedy but the lowest in Manipulative and Body-Based methods. Adverse-effect score was best in Manipulative and Body-Based methods. According to age and the causative disease of death, there were significant differences in satisfaction and adverse effect levels. Conclusion: Majority of old people used at least one of CAM during their last 6months of life. Whole satisfaction and adverse-effect level were very excellent.

• Journal of the KSME
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• v.29 no.6
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• pp.618-626
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• 1989

자동차용 메타놀 연료는 석유파동 이후의 석유 대체연료라는 관점에 저공해 연료의 관점이 추가 되어 최근 그 도입에 대한 연구가 활발해지고 있다. 메타놀 자동차에 관해서는 종래의 기초검토 의 단계로부터 서서히 실용화를 향한 내구, 신뢰성을 포함한 많은 과제의 검토단계로 이행되고 있다. 수소엔진의 연구는 아직 초보단계에 있으며 안전성에 대해서는 일반이 염려하고 있는 것과 같은 위험성은 없지만 금후 자동차용으로서의 안전성에 관한 실험이 필요할 것이다. 수소의 장 점을 살려 결점을 없애기 위해서는 LH2탱크, LH2펌프 4사이클 실린더내 분사가 이상적으로 생 각되고 있다.

• Review of KIISC
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• v.32 no.1
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• pp.19-29
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• 2022

2011 Jao와 De Feo에 의해 제안된 SIDH가 기존 타원곡선 사이의 isogeny를 이용한 암호보다 효율적인 성능을 제공하고, 그 후 2016년 Costello 등의 효율적인 연산 방법으로 SIDH 속도가 3배 이상 향상되면서, 타원곡선 사이의 isogeny를 이용한 암호가 양자 컴퓨팅 환경에서 RSA와 ECC를 대체할 암호로 주목을 받기 시작했다. 특히 isogeny 기반 암호는 다른 PQC 암호에 비해 작은 키 사이즈를 제공한다는 장점으로 현재까지 활발히 연구가 진행되고 있으며, SIDH를 기반으로 둔 SIKE는 NIST PQC 표준화 공모전 Round 3의 대체 후보이다. 다른 PQC 암호에 비해 속도가 느리다는 점이 isogeny 기반 암호의 단점인 만큼, isogeny 기반 암호는 처음 제안된 후 10년 동안 최적화를 중심으로 큰 발전을 이뤄왔다. 본 논문에서는 isogeny 기반 암호의 최신 연구 동향을 소개한다.

• The Korean Journal of Applied Statistics
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• v.28 no.4
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• pp.763-779
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• 2015

This study estimate the adequate replacement rate of retirement income by income brackets and suggests roles of pension and non-pension income sources to achieve it for each income bracket. Priori research focused on elderly poverty; however, there has been little discussion about an adequate income level for retirement. We calculate an adequate income replacement rate separately for the poor, middle, and high income group as well as the average level of replacement rate for all groups. We also investigate the gap between the adequate income replacement rates and realized rates, and propose roles for each income source to curtail the gap. It is essential to recognize that the adequate income for retirement is unable to be met only by an annuity. To emove the gap, it is vital to utilize non-pension income although annuity is a primary source for retirement. Especially, the public and private pension plays a role to overcome poverty and live affluent in retirement, respectively.