• Communications for Statistical Applications and Methods
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• 제30권1호
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• pp.1-19
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• 2023

Observational data with missing or incomplete data are common in biomedical research. Multiple imputation is an effective approach to handle missing data with the ability to decrease bias while increasing statistical power and efficiency. In recent years propensity score (PS) matching has been increasingly used in observational studies to estimate treatment effect as it can reduce confounding due to measured baseline covariates. In this paper, we describe in detail approaches to competing risk analysis in the setting of incomplete observational data when using PS matching. First, we used multiple imputation to impute several missing variables simultaneously, then conducted propensity-score matching to match statin-exposed patients with those unexposed. Afterwards, we assessed the effect of statin exposure on the risk of heart failure-related hospitalizations or emergency visits by estimating both relative and absolute effects. Collectively, we provided a general methodological framework to assess treatment effect in incomplete observational data. In addition, we presented a practical approach to produce overall cumulative incidence function (CIF) based on estimates from multiple imputed and PS-matched samples.

• Preventive Nutrition and Food Science
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• 제10권3호
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• pp.285-289
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• 2005

In this double-blind, placebo-controlled trial, we assessed the efficacy and safety of beef tallow extract (BTE) including Cis-9-cetylmyristoleate in patients with arthritis. Between May and December 2003, we selected 80 patients (n=80) who showed/manifested arthritic symptoms and whose radiological findings were suggestive of arthritis, and randomly assigned them to placebo-controlled (n=40) and treatment group (n=40). The placebo (corn starch 350 mg) and BTE (208 mg) were orally administered to placebo-controlled and treatment group three times a day, respectively. We assessed the efficacy and safety based on the visual analogue scale (V AS) and modified knee society knee scores (MKSKS) at baseline and endpoint, respectively. To assess the safety, we monitored the adverse effects noted in liver, kidney, cardiovascular and gastrointestinal system for 3 weeks. Then, we performed not only a questionnaire study but also laboratory tests (e.g., liver function test, kidney function test, urinalysis, electrocardiography [EKG], complete blood cell counts [CBC] and chest X-ray). For statistical analysis, Student (-test and paired (-test were done using SPSS■ Version 11.0. Statistical significance was set at p < 0.05. The scores between V AS and MKSKS showed statistical significance (p < 0.05) with an improvement of $69.2\%$ (27/39) and $3.8\%$ (21/39) of treatment-group patients, respectively. Abnormal laboratory findings were noted in neither placebo-controlled nor treatment group. In conclusion, our results indicate that the administration of BTE was a safe and effective treatment regimen for patients with arthritis. In addition, the efficacy of BTE was more remarkable in alleviating the symptoms rather than improving the function.

• 대한방사선기술학회지:방사선기술과학
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• 제45권6호
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• pp.491-502
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• 2022

The purpose of this study was to retrospectively investigate the upper and lower control limits of treatment planning parameters using EBT film based delivery quality assurance (DQA) results and to analyze the results of statistical process control (SPC) in helical tomotherapy (HT). A total of 152 patients who passed or failed DQA results were retrospectively included in this study. Prostate (n = 66), rectal (n = 51), and large-field cancer patients, including lymph nodes (n = 35), were randomly selected. The absolute point dose difference (DD) and global gamma passing rate (GPR) were analyzed for all patients. Control charts were used to evaluate the upper and lower control limits (UCL and LCL) for all the assessed treatment planning parameters. Treatment planning parameters such as gantry period, leaf open time (LOT), pitch, field width, actual and planning modulation factor, treatment time, couch speed, and couch travel were analyzed to provide the optimal range using the DQA results. The classification and regression tree (CART) was used to predict the relative importance of variables in the DQA results from various treatment planning parameters. We confirmed that the proportion of patients with an LOT below 100 ms in the failure group was relatively higher than that in the passing group. SPC can detect QA failure prior to over dosimetric QA tolerance levels. The acceptable tolerance range of each planning parameter may assist in the prediction of DQA failures using the SPC tool in the future.

• 스마트미디어저널
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• 제3권3호
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• pp.15-19
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• 2014

지문 인식 시스템은 지문인식 장치(fingerprint acquisition device)를 통하여 아날로그(analog) 지문으로부터 변환된 디지털(digital) 지문에서 특이점을 추출하고 추출한 특이점들에 대한 정보를 데이터베이스에 등록하는 오프라인(off-line) 처리와 사용자가 시스템에 접근 할 때 입력한 지문으로부터 특이점을 추출한 후 데이터베이스에 저장되어 있는 특이점들과 정합(matching) 하여 사용자의 시스템 접근 여부를 결정하는 온라인(on-line) 처리로 이루어져 있다. 본 논문에서는 다양한 생체인식시스템 중, 통계 지문 인식 정합 방법인 지문의 특이점 을 사용한다. 좌표를 기준으로서 유사성 거리 측정을 하고, 그리고 특정한 각도, 통계 배포 판에 따라서 지문 인식 모델을 찾는 것이다.

• 전기학회논문지
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• 제59권5호
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• pp.912-917
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• 2010

It was known that oil-filled transformer's life depended on insulating paper which was applied to transformers for insulating of transformer. Therefore when paper was aged, its electrical, mechanical and chemical characteristics were changed. Especially if operating temperature was high, paper was quickly damaged. As cellulose paper which was mainly used for solid insulation of transformers was degraded, the cellulose polymer chains broke down into shorter lengths and gases such as CO, $CO_2$, $CH_4$, $C_2H_4$ and so on were produced from paper. Also by-product known as furan compounds were producted from paper and it were dissolved within insulating oil. In this paper accelerating aging cell was aged during 60 hours at 100, 150, 180 and $200^{\circ}C$, respectively, so evaluating the chemical characteristics of cellulose paper by thermal. An it were performed analysis such as tensile strength(TS), dissolved gas analysis(DGA) and high performance liquid chromatography(HPLC). Also for analyzing of correlation between insulating degradation characteristics, it was performed linear regression method as statistical treatment.

• Child Health Nursing Research
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• 제11권3호
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• pp.356-364
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• 2005

Purpose: This study is to assess and compare the analgegic effects of $25\%$ sucrose coating pacifier and pacifier. Method: The participants are 75 healthy infants of neonatal age 1-7 days and randomized to receive heel prick before 2 minutes to blood sampling and physiological test in Nursery of A Medical Center from 24. January to 28, February, 2003. The experimental group assigned to one of three treatment groups: no treatment, a pacifier, $25\%$ sucrose coating pacifier. Collected data were analyzed with the SPSS 11.0 program using $x^2$-test, one-way ANOVA and Scheffe, repeated mesured ANOVA. Results: The pain score of $25\%$ sucrose coating pacifier is lower than no treatment group and pacifier group. In heart rate, there were statistical significant differences between three groups. In repiratory rate, there were no statistical significant differences between three groups. In $SaO_2$, there were statistical significant difference between three groups. Conclusion: The $25\%$ sucrose coating pacifier showed pain relief effect in behavior responses and heart rate and $SaO_2$. Accordingly, the sucrose coating pacifier should be applied nursing intervention for simple pain management as heel prick.

• Communications for Statistical Applications and Methods
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• 제25권3호
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• pp.321-328
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• 2018

In clinical trials with repeated measurements, the time-averaged difference (TAD) may provide a more powerful evaluation of treatment efficacy than the rate of changes over time when the treatment effect has rapid onset and repeated measurements continue across an extended period after a maximum effect is achieved (Overall and Doyle, Controlled Clinical Trials, 15, 100-123, 1994). The sample size formula has been investigated by many researchers for the evaluation of TAD in two treatment groups. For the evaluation of TAD in multi-arm trials, Zhang and Ahn (Computational Statistics & Data Analysis, 58, 283-291, 2013) and Lou et al. (Communications in Statistics-Theory and Methods, 46, 11204-11213, 2017b) developed the sample size formulas for continuous outcomes and count outcomes, respectively. In this paper, we derive a sample size formula to evaluate the TAD of the repeated binary outcomes in multi-arm trials using the generalized estimating equation approach. This proposed sample size formula accounts for various correlation structures and missing patterns (including a mixture of independent missing and monotone missing patterns) that are frequently encountered by practitioners in clinical trials. We conduct simulation studies to assess the performance of the proposed sample size formula under a wide range of design parameters. The results show that the empirical powers and the empirical Type I errors are close to nominal levels. We illustrate our proposed method using a clinical trial example.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제46권5호
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• pp.321-327
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• 2020

Objectives: This study is aimed to evaluate and compare the effect of moist heat fomentation therapy with ultrasound therapy in patients with the masticatory myalgia. Materials and Methods: The study was conducted on 42 patients with masticatory myalgia, dividing them into two groups; Group A (21 patients), received moist heat therapy and Group B (21 patients), received ultrasound therapy for seven effective days. Prior and after the treatment the numeric rating scale (NRS) and the electromyography (EMG) scores were recorded and compared. The observations were analyzed clinically and statistical support was taken to assess the NRS and EMG data. Results: Irrespective of the groups, patients testified a significant reduction in pain after the treatment. From the EMG readings; even though the standard deviation for each group was varied considerably, EMG recorded an improved muscle activity. Statistical analysis was used to assess and identify the best treatment methodology between the two modalities. Conclusion: From the statistical analysis, it is concluded that, though both the therapies had significantly reduced the symptomatic response, it is moist heat fomentation that improved muscle activity both statistically and clinically in comparison to ultrasound.

• Communications for Statistical Applications and Methods
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• 제28권5호
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• pp.411-424
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• 2021

Inference following two-stage adaptive designs (also known as two-stage randomization designs) with survival endpoints usually focuses on estimating and comparing survival distributions for the different treatment strategies. The aim is to identify the treatment strategy(ies) that leads to better survival of the patients. The objectives of this study were to assess the performance three commonly cited methods for estimating survival distributions in two-stage randomization designs. We review three non-parametric methods for estimating survival distributions in two-stage adaptive designs and compare their performance using simulation studies. The simulation studies show that the method based on the marginal mean model is badly affected by high censoring rates and response rate. The other two methods which are natural extensions of the Nelson-Aalen estimator and the Kaplan-Meier estimator have similar performance. These two methods yield survival estimates which have less bias and more precise than the marginal mean model even in cases of small sample sizes. The weighted versions of the Nelson-Aalen and the Kaplan-Meier estimators are less affected by high censoring rates and low response rates. The bias of the method based on the marginal mean model increases rapidly with increase in censoring rate compared to the other two methods. We apply the three methods to a leukemia clinical trial dataset and also compare the results.

• Journal of Korean Dental Science
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• 제13권2호
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• pp.59-66
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• 2020

Purpose: The purpose of this study was to investigate the masseter muscle thickness before and after treatment using ultrasound sonography in patients with parafunctional habits. Materials and Methods: From September 2019 to March 2020, a total of 27 patients who visited the Department of Oral and Maxillofacial Surgery at Ewha Womans University Seoul Hospital were collected. The thickness of both masseter muscles was measured using a tablet ultrasound scanner. Statistical analysis was performed by using the IBM SPSS version 26.0 statistical package (IBM Corp) with significance level at 0.05. Result: According to the statistical results, the thickness of the masseter muscle was thicker on the right side than on the left, with no correlation with sex or age. The severity and duration of pain did not have a significant correlation with the thickness of the masseter muscle. Botulinum A toxin injection in the masseter muscle was the most effective way to reduce pain and reduce the thickness of the masseter muscle. Splint treatment also showed some effects in reducing the thickness of the masseter muscle. Conclusion: Based on the findings, it can be claimed that ultrasonography is simple, inexpensive and easily repeatable method to get real-time diagnosis and treatment results for masseter muscles.