• 한국산학기술학회논문지
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• 제17권11호
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• pp.271-284
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• 2016

본 연구는 임부의 산전우울에 대한 인지행동치료 중재의 효과를 검증하기 위해 수행된 체계적 문헌고찰 및 메타분석 연구이다. 데이터베이스는 CINAHL, PubMed, EMBASE 및 Koreamed, 국회도서관, 한국학술정보(Korean studies Information Service System, KISS), 한국의학논문데이터베이스 등 국내외 domain을 활용하였다. 검색은 ((Perinatal OR Antenatal OR Antepartum OR Pregnant) AND Depression) AND Women AND (CBT OR (Cognitive behavioral AND (Therapy OR Treatment)))와 '산전우울', '임부', '인지행동치료' 등의 검색어로 2016년 5월까지 출판된 문헌을 검토하였다. 분석은 R을 이용한 임의효과모형을 적용하여 산전우울과 불안의 효과크기를 각각 산출하였으며, 효과크기의 이질성을 검증하기위해 메타 ANOVA를 활용하여 조절효과분석을 실시하였다. 그리고 funnel plot, Egger's regression test, fail-safe N, trim-and-fill 분석을 활용한 출간오류분석과 민감성 분석을 실시하여 전체 연구 결과의 타당성을 검증하였다. 연구결과 총 180편의 문헌이 검색되었으며, 선택배제기준에 따라 최종적으로는 clinical trials 16편을 분석하였다. 분석에 포함된 개별문헌은 Scottish Intercollegiate Guideline Network (SIGN)의 checklist를 통해 비뚤림 위험을 평가하였으며, 대체로 비뚤림 위험은 낮았다. 연구결과 본 연구에서 중재의 산전우울에 대한 효과크기는 Hedges' g=-0.55(95% CI: -0.76~-0.33)로 통계적으로 유의하게 낮았으며, 불안에 대한 효과크기는 Hedges' g=-0.20(95% CI: -0.48~-0.08)이었으나, 통계적으로 유의한 차이는 없었다. 문헌의 이질성, 출판오류의 위험성 등은 낮았다. 본 메타분석결과에 의하면 인지행동치료는 임신부의 산전우울 증세 완화에 보통 정도의 효과가 있음이 밝혀졌다.

• 대한통합의학회지
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• 제9권3호
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• pp.87-97
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• 2021

Purpose : The purpose of this meta-analysis was to evaluate the effects of transcranial direct current stimulation on the lower extremity function of stroke patients. Methods : Domestic data were gathered from studies that conducted clinical trials associated with transcranial direct current stimulation and its impact on lower extremity function of stroke patients. A total of 592 studies published between 2012 and 2020 were identified, with 7 studies satisfying the inclusion data. The studies consisted of patient, intervention, comparison, and outcome (PICO) data. The search outcomes were items associated with muscle activity, balance, muscle strength and walking ability. Cochrane risk of bias (ROB) was used to evaluate the quality of 3 randomized control trials. The quality of 4 non-randomized control trials was evaluated using risk of bias assessment tool for non-randomized studies (RoBANS). Effect sizes in this study were computed as the corrected standard mean difference (SMD). A random-effect model was used to analyze the effect size because of the high heterogeneity among the studies. Egger's regression and 'trim-and-fill' tests were carried out to analyze the publishing bias. Results : The following factors had a large total effect size (Hedges's g=2.10, 95 %CI=1.54~2.66) involving transcranial direct current stimulation on stroke patients: muscle activity (Hedges's g=2.38, 95 %CI=1.08~3.68), balance (Hedges's g4=2.41, 95 %CI=1.33~3.60), walking ability (Hedges's g=1.54, 95 %CI=0.49~2.59), and muscle strength (Hedges's g=2.45, 95 % CI: 0.85~4.05). Egger's regression test showed that the publishing bias had statistically significant differences but 'trim-and-fill' test showed that there was still statistical difference. Conclusion : This study provides evidence for the effectiveness of transcranial direct current stimulation on the lower extremity in terms of muscle activity, balance, walking ability, and muscle strength in stroke patients. However, due to the low quality of studies and high heterogeneity factors, the results of our study should be interpreted cautiously.

• ETRI Journal
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• 제15권3_4호
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• pp.61-69
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• 1994

A new analytical model for the base current of Si/SiGe/Si heterojunction bipolar transistors(HBTs) has been developed. This model includes the hole injection current from the base to the emitter, and the recombination components in the space charge region(SCR) and the neutral base. Distinctly different from other models, this model includes the following effects on each base current component by using the boundary condition of the excess minority carrier concentration at SCR boundaries: the first is the effect of the parasitic potential barrier which is formed at the Si/SiGe collector-base heterojunction due to the dopant outdiffusion from the SiGe base to the adjacent Si collector, and the second is the Ge composition grading effect. The effectiveness of this model is confirmed by comparing the calculated result with the measured plot of the base current vs. the collector-base bias voltage for the ungraded HBT. The decreasing base current with the increasing the collector-base reverse bias voltage is successfully explained by this model without assuming the short-lifetime region close to the SiGe/Si collector-base junction, where a complete absence of dislocations is confirmed by transmission electron microscopy (TEM)[1].The recombination component in the neutral base region is shown to dominate other components even for HBTs with a thin base, due to the increased carrier storage in the vicinity of the parasitic potential barrier at collector-base heterojunction.

• Transactions on Electrical and Electronic Materials
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• 제14권4호
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• pp.177-181
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• 2013

In this paper, silicon solar cells are analyzed regarding power conversion efficiency by changed capacitance in the depletion region. For the capacitance control in the depletion region of silicon solar cell was applied for 10, 20, 40, 80, 160 and 320 Hz frequency band character and alternating current(AC) voltage with square wave of 0.2~1.4 V. Academically, symmetry formation of positive and negative change of the p-n junction is similar to the physical effect of capacitance. According to the experiment result, because input of square wave with alternating current(AC) voltage could be observed to changed capacitance effect by indirectly method through non-linear power conversion (Voltage-Current) output. In addition, when input alternating current(AC) voltage in the silicon solar cell, changed capacitance of depletion region with the forward bias condition and reverse bias condition gave a direct effect to the charge mobility.

• Communications for Statistical Applications and Methods
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• 제23권1호
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• pp.1-20
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• 2016

Causal inference methodologies have been developed for the past decade to estimate the unconfounded effect of an exposure under several key assumptions. These assumptions include, but are not limited to, the stable unit treatment value assumption, the strong ignorability of treatment assignment assumption, and the assumption that propensity scores be bounded away from zero and one (the positivity assumption). Of these assumptions, the first two have received much attention in the literature. Yet the positivity assumption has been recently discussed in only a few papers. Propensity scores of zero or one are indicative of deterministic exposure so that causal effects cannot be defined for these subjects. Therefore, these subjects need to be removed because no comparable comparison groups can be found for such subjects. In this paper, using currently available causal inference methods, we evaluate the effect of arbitrary cutoffs in the distribution of propensity scores and the impact of those decisions on bias and efficiency. We propose a tree-based method that performs well in terms of bias reduction when the definition of positivity is based on a single confounder. This tree-based method can be easily implemented using the statistical software program, R. R code for the studies is available online.

• 대기
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• 제18권1호
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• pp.71-81
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• 2008

In this study, in order to estimate high resolution precipitation with monthly time scales, Parameter-elevation Regressions on Independent Slopes Model (PRISM) was modified and configured for Korean precipitation based on elevation, distance, topographic facet, and coastal proximity. Applying this statistical downscaling model to Korean precipitation for 5 years from 2001 to 2005, we have compiled monthly grid data with a horizontal resolution of 5-km and evaluated the model using bias, root mean square error (RMSE), and correlation coefficient between the observed and the estimated. Results show that bias, RMSE, and correlation coefficient of the estimated value have a range from 0.2% to 1.0%, 19.6% (June) to 43.9% (January), and 0.73 to 0.84, respectively, indicating that the modified Korean PRISM (K-PRISM) is reasonably worked by weighting factors, i.e., topographic effect and rain shadow effect.

• 한국학교수학회논문집
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• 제18권1호
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• pp.149-167
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• 2015

본 연구의 목적은 수학의 학업성취도에 미치는 영향요인에 대하여 기존의 연구들을 분석하고, 특히 학교수준에서 실시하고 있는 수학과 수준별 이동수업이 실질적으로 학생들의 수학 학업성취도에 영향을 미치는지를 실증적으로 분석하고자 한다. 선택편의를 최소화하기 위해 한국교육종단연구2005의 6차년도 데이터를 바탕으로 경향점수매칭법(propensity score matching)을 사용하여 수학 교과 수준별 이동수업이 수학성취도의 지표인 수능 수리영역 표준점수에 미치는 영향을 살펴보았다. 그 결과 수준별 이동수업과 수학성취도 사이의 양의 관계가 있음을 확인하였으며, 수준별 이동수업의 효과적 운영을 위해 정책적인 노력이 요구된다.

• 부모자녀건강학회지
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• 제22권1호
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• pp.10-21
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• 2019

Purpose: This study was carried out to evaluate the efficacy of exercise program on recovery of functional and quality of life in breast cancer patients through systematic literature review and meta-analysis. Methods: The following databases were used to search the literature: RISS, KISS, KMbase, and KoreaMed. Keywords included 'breast cancer', 'mastectomy' 'exercise', 'rehabilitation', 'intervention' and the evaluated articles were published from 2009 to 2018. The statistical was used R program, the effect size of shoulder functionality, grip strength, upper limb, pain and QOL were calculated by random-effects model. Results: 7 RCT studies were meta-analyzed and were evaluated for the risk of bias by the RoB of Cochrane Collaboration; the overall risk of bias was low. The effect sizes of exercise program was flexion (g=1.11), abduction (g=0.97) as indicated by a "large effect size". Conclusion: It is necessary to study the develop and apply a exercise programs to improve the function and quality of life in breast cancer patients.

• Journal of Dental Anesthesia and Pain Medicine
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• 제21권5호
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• pp.397-411
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• 2021

This systematic review aimed to assess the effect of premedication on postoperative pain after root canal treatment in vital teeth. Five electronic databases were searched for randomized clinical trials, and two independent reviewers selected eligible studies, extracted data, and assessed the quality of studies using the Cochrane Risk of Bias tool. Meta-analysis was conducted using the random-effects model, and the pooled effect estimate of the standardized mean difference (SMD) between premedication and placebo was calculated. Subgroup analysis was conducted based on the class and route of the drug. Studies with a high risk of bias were excluded from the sensitivity analysis. Ten trials satisfied the inclusion criteria, of which eight were included in the meta-analysis. Premedication was more effective in reducing postoperative pain than placebo at 6 hours (SMD = -1.00; 95% confidence interval [CI] = -1.33 to -0.66), 12 hours (SMD = -0.80; 95% CI = -1.05 to -0.56), and 24 hours (SMD = -0.72; 95% CI = -1.02 to -0.43). The results of the sensitivity analysis confirmed the findings of the primary analysis. Based on these results, it can be concluded that premedication is effective in reducing postoperative pain in teeth with irreversible pulpitis. However, additional quality studies are required for further validation.

• 한국재료학회지
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• 제29권11호
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• pp.709-714
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• 2019

In order to observe the microstructure and morphology of porous titanium -oxide thin film, deposition is performed under a higher Ar gas pressure than is used in the general titanium thin film production method. Black titanium thin film is deposited on stainless steel wire and Cu thin plate at a pressure of about 12 Pa, but lustrous thin film is deposited at lower pressure. The black titanium thin film has a larger apparent thickness than that of the glossy thin film. As a result of scanning electron microscope observation, it is seen that the black thin film has an extremely porous structure and consists of a separated column with periodic step differences on the sides. In this configuration, due to the shadowing effect, the nuclei formed on the substrate periodically grow to form a step. The surface area of the black thin film on the Cu thin plate changes with the bias potential. It has been found that the bias of the small negative is effective in increasing the surface area of the black titanium thin film. These results suggest that porous titanium-oxide thin film can be fabricated by applying the appropriate oxidation process to black titanium thin film composed of separated columns.