• 응용통계연구
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• 제23권6호
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• pp.1093-1102
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• 2010

비모수적 판별분류방법인 k-Nearest Neighbors Classification(KNNC) 방법은 널리 사용되고 있지만 고정된 이웃의 개수를 사용하며 또한 집단변수의 정보를 활용하지 않음으로서 자료의 국소적 특징을 반영하지 못하는 단점이 있다. Adaptive Nearest Neighbors Classification(ANNC) 방법과 Modified k-Nearest Neighbors Classification(MKNNC) 방법은 각각 이러한 단점들을 보완하기 위해 제안된 방법이다. 본 연구에서는 ANNC 방법과 MKNNC 방법의 장점을 결합한 Modified Adaptive Nearest Neighbors Classification(MANNC) 방법을 제안하였다. 나아가, 제안된 방법의 활용 가능성을 살펴보고자 실제자료에 대한 분석과 모의실험을 통해 기존의 방법들과 비교하였다.

• Journal of Periodontal and Implant Science
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• 제46권4호
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• pp.266-276
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• 2016

Purpose: The aim of the present study was to retrospectively investigate the influence of potential risk indicators on the development of peri-implant disease. Methods: Overall, 103 patients referred for implant treatment from 2000 to 2012 were randomly enrolled. The study sample consisted of 421 conventional-length (>6 mm) non-turned titanium implants that were evaluated clinically and radiographically according to preestablished clinical and patient-related parameters by a single investigator. A non-parametric Mann-Whitney U test or Kruskal-Wallis rank test and a logistic regression model were used for the statistical analysis of the recorded data at the implant level. Results: The diagnosis of peri-implant mucositis and peri-implantitis was made for 173 (41.1%) and 19 (4.5%) implants, respectively. Age (${\geq}65$ years), patient adherence (professional hygiene recalls <2/year) and the presence of plaque were associated with higher peri-implant probing-depth values and bleeding-on-probing scores. The logistic regression analysis indicated that age (P=0.001), patient adherence (P=0.03), the absence of keratinized tissue (P=0.03), implants placed in pristine bone (P=0.04), and the presence of peri-implant soft-tissue recession (P=0.000) were strongly associated with the event of peri-implantitis. Conclusions: Within the limitations of this study, patients aged ${\geq}65$ years and non-adherent subjects were more prone to develop peri-implant disease. Therefore, early diagnosis and a systematic maintenance-care program are essential for maintaining peri-implant tissue health, especially in older patients.

• 한국임상보건과학회지
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• 제4권3호
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• pp.603-614
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• 2016

Purpose. The purpose of this study was to provide basic data regarding the intention to use community care service based on special grading for dementia in the South Korean Society. Methods. A survey was conducted using a questionnaire adapted on the basis of literature review regarding the first to fourth grade under the long-term care insurance system for the aged from May 1 to 30, 2015 and a total of 272 questionnaires were statistically processed using SPSS 21.0. Frequency analysis, descriptive statistics, and cross-tabulation analysis were performed. The non-parametric type of test, ${\chi}^2$ test, was used for statistical testing. Results. This study obtained the following results: First, caregivers had greater intention to ask recipients to use daytime and nighttime care service. Second, there were statistically significant differences in caregivers' education, occupation, monthly average income, co-residence status, intimacy, and care-giving burden (emotional, financial, and social) and recipients' activities of daily living, instrumental activities of daily living, mental health status, dementia status, and intention to use community care service based on special grading for dementia. Conclusions. There are very few statistical data and academic materials regarding special grading for dementia, which has recently been established. The results of this study are therefore expected to help make a systematic analysis of the intention to use community care service by caregivers based on special grading for dementia.

• PNF and Movement
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• 제15권3호
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• pp.317-331
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• 2017

Purpose: Balance and walking ability are important elements of functional independence for people with stroke and are major goals in rehabilitation. These abilities require trunk performance, but most chronic stroke patients reach a plateau in their rehabilitation. Therefore, the purpose of this study was to investigate the effects of a self-training trunk program to improve balance and walking ability in people with stroke, and to suggest such a self-training program for integrated rehabilitation of people with stroke. Methods: The study recruited 7 people with stroke. The subjects performed trunk training for 30 min per day, 6 days per week, for 3 weeks. Participants were measured on the Trunk Impairment Scale (TIS), the Berg Balance Scale (BBS), the Korean Activities-specific Balance Confidence (K-ABC) scale, the Falls Efficacy Scale (FES), the Functional Gait Assessment (FGA), the 6 Minute Walk Test (6MWT) and a gait analysis to measure the training effects. Statistical analysis used the Wilcoxon signed-rank test as a non-parametric statistical test. Results: TIS was not significantly different after the self-training trunk program, but BBS (p>0.05), K-ABC, and FES were significantly improved after the training program (p<0.05). Furthermore, the 6MWT, stride/height %, and one-leg stance were significantly improved after the training program (p<0.05), but cadence, stance, and swing duration were not significantly different after the training (p>0.05). Conclusion: These results suggest that a self-training trunk program should be integrated into stroke rehabilitation to improve balance and walking ability, and further research is needed to develop the program to be more effective for chronic stroke patients.

• 응용통계연구
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• 제22권3호
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• pp.479-488
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• 2009

비모수적 판별분류방법으로 널리 사용되는 ${\kappa}$-Nearest Neighbors Classification(KNNC) 방법은 자료의 국소적 특징을 고려하지 않고 전체 자료에 대해 고정된 이웃의 개수 ${\kappa}$를 사용하여 개체를 분류하는 방법이다. 본 연구에서는 KNNC의 대안으로 자료의 국소적 특징을 고려하는 Adaptive Nearest Neighbors Classificaion(ANNC) 방법을 제안하였다. 제안된 방법의 특징을 규명하기 위하여 실제 자료에 대한 분석을 통하여 제안된 방법의 응용 가능성을 제시하였으며, 나아가 모의실험을 통하여 기존의 방법과의 효율성을 비교하였다.

• 한국습지학회지
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• 제6권4호
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• pp.35-43
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• 2004

경향성을 분석하기 위한 여러 기법 가운데 비모수적 방법인 Mann-Kendall 검정(MK 검정)은 수문 시계열의 분석에서 널리 사용되어지고 있다. 이 검정 방법은 분석 대상 자료가 독립이라는 가정 하에 수행되며, 자료가 계열상관되어 있는 경우에는 그 상관성의 영향으로 경향성 존재의 유무를 정확하게 판단할 수 없게 된다. 따라서 MK 검정을 이용할 때 자료의 상관성으로 인해 받게 되는 영향을 소거시키기 위해 효과적인 자료의 크기(Effective Sample Size, ESS)를 이용하는 수정된 MK 검정 방법을 이용하고자 한다. 본 연구에서는 ESS가 얼마만큼 계열상관성을 제거할 수 있는지 Monte Carlo모의를 통해 검토하였다. MK 검정 결과 계열상관계수의 증가에 따라 자료가 경향성을 나타내는 비율이 높아 졌으나, ESS에 의해 수정된 MK 검정을 수행한 결과 계열상관계수의 영향이 제거되었음을 알 수 있었다. 또한 실측 자료의 적용을 통해 수정 MK검정이 경향성 분석에 매우 유용함을 확인 하였다.

• 응용통계연구
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• 제34권3호
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• pp.439-447
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• 2021

범지구적 이상기후의 잦은 출현으로 기상 변화에 대한 관련 연구가 활발히 진행되고 있지만, 장기간 축적된 기상자료를 이용한 경향성 분석 연구는 부족하였다. 본 연구에서는 비모수적 분석방법을 이용해 40년간 종관기상관측장비(ASOS)로 부터 축적된 기온 시계열 자료의 경향성을 분석하였다. 남한지역의 연평균 기온과 계절별 평균기온 시계열 자료에 대한 Mann-Kendall 검정 결과 상승 경향성이 존재하는 것으로 나타났다. 또한 Pettitt 검정을 적용해 탐색된 변동점을 전후로 경향성의 정도를 파악할 수 있는 Sen's slope를 계산한 결과, 변동점 이후의 최근 자료에서 기온의 상승 경향성이 더욱 큰 것을 확인하였다.

• Investigative Magnetic Resonance Imaging
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• 제26권2호
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• pp.104-116
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• 2022

The purpose of this study is to systematically determine an optimal percentile cut-off in histogram analysis for calculating the mean parameters obtained from a non-Gaussian continuous-time random-walk (CTRW) diffusion model for differentiating individual glioma grades. This retrospective study included 90 patients with histopathologically proven gliomas (42 grade II, 19 grade III, and 29 grade IV). We performed diffusion-weighted imaging using 17 b-values (0-4000 s/mm²) at 3T, and analyzed the images with the CTRW model to produce an anomalous diffusion coefficient (D_m) along with temporal (𝛼) and spatial (𝛽) diffusion heterogeneity parameters. Given the tumor ROIs, we created a histogram of each parameter; computed the P-values (using a Student's t-test) for the statistical differences in the mean D_m, 𝛼, or 𝛽 for differentiating grade II vs. grade III gliomas and grade III vs. grade IV gliomas at different percentiles (1% to 100%); and selected the highest percentile with P < 0.05 as the optimal percentile. We used the mean parameter values calculated from the optimal percentile cut-offs to do a receiver operating characteristic (ROC) analysis based on individual parameters or their combinations. We compared the results with those obtained by averaging data over the entire region of interest (i.e., 100th percentile). We found the optimal percentiles for D_m, 𝛼, and 𝛽 to be 68%, 75%, and 100% for differentiating grade II vs. III and 58%, 19%, and 100% for differentiating grade III vs. IV gliomas, respectively. The optimal percentile cut-offs outperformed the entire-ROI-based analysis in sensitivity (0.761 vs. 0.690), specificity (0.578 vs. 0.526), accuracy (0.704 vs. 0.639), and AUC (0.671 vs. 0.599) for grade II vs. III differentiations and in sensitivity (0.789 vs. 0.578) and AUC (0.637 vs. 0.620) for grade III vs. IV differentiations, respectively. Percentile-based histogram analysis, coupled with the multi-parametric approach enabled by the CTRW diffusion model using high b-values, can improve glioma grading.

• 대한치과교정학회지
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• 제47권1호
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• pp.11-20
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• 2017

Objective: This randomized controlled trial aimed to compare the stability of mandibular arch orthodontic treatment outcomes between passive self-ligating and conventional systems during 6 months of retention. Methods: Forty-seven orthodontic patients with mild to moderate crowding malocclusions not requiring extraction were recruited based on inclusion criteria. Patients (mean age $21.58{\pm}2.94years$) were randomized into two groups to receive either passive self-ligating ($Damon^{(R)}$ 3MX, n = 23) or conventional system (Gemini MBT, n = 24) orthodontic treatment. Direct measurements of the final sample comprising 20 study models per group were performed using a digital caliper at the debonding stage, and 1 month, 3 months, and 6 months after debonding. Paired t-test, independent t-test, and non-parametric test were used for statistical analysis. Results: A significant increase (p < 0.01) in incisor irregularity was observed in both self-ligating and conventional system groups. A significant reduction (p < 0.01) in second interpremolar width was observed in both groups. Mandibular arch length decreased significantly (p = 0.001) in the conventional system group but not in the self-ligating system group. A similar pattern of stability was observed for intercanine width, first interpremolar width, intermolar width, and arch depth throughout the 6-month retention period after debonding. Comparison of incisor irregularity and arch dimension changes between self-ligating system and conventional system groups during the 6 months were non-significant. Conclusions: The stability of treatment outcomes for mild to moderate crowding malocclusions was similar between the self-ligating system and conventional system during the first 6 months of retention.

• 대한족부족관절학회지
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• 제28권1호
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• pp.15-20
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• 2024

Purpose: Achilles tendon rupture is a frequently encountered ankle pathology associated with a substantial burden of intense pain and functional deficits. Chronic Achilles tendon ruptures with considerable defects pose intricate repair challenges that are often marred by complications such as re-rupture and persistent pain. Various treatment methods, including allograft transplantation, have been proposed, but the literature on this technique is limited. In this study, we propose a surgical approach utilizing allotendon transplantation and a calcaneal tunneling technique and provide clinical evaluation details. Materials and Methods: Fifteen patients with chronic Achilles tendon ruptures treated with allotendon between 2020 and 2022 were included in the study. Patients were evaluated at 1, 3, and 6 months postoperatively using Visual Analog Scale (VAS) scores and Achilles Tendon Total Rupture Scores (ATRSs). Complications were assessed postoperatively. Results: The average VAS score was 7 before surgery, 7.3 immediately after surgery, and 4.3 at 1 month, 2.5 at 3 months, and 1.3 at 6 months after surgery. Because the sample was limited to 15 individuals and distributions were non-normal, the analysis was conducted using the non-parametric Wilcoxon's signed-rank test, and statistical significance was accepted for p-values<0.05. Results showed a significant improvement in ATRS and VAS scores versus preoperative and immediate postoperative values. VAS scores showed a decreasing trend after surgery, whereas average ATRS scores increased from 14 before surgery, 33.8 at 1 month, 82.7 at 3 months, and 93.9 at 6 months. Conclusion: This study suggests that allograft transplantation using the described calcaneal tunnel technique provides an effective treatment for chronic Achilles tendon ruptures. However, extensive research and long-term clinical trials are required to validate and better understand the technique's efficacy.