• 대기
• /
• 제25권2호
• /
• pp.205-219
• /
• 2015

In this study, the simulation results of temperature by regional climate model (Reg- CM4) over South Korea were corrected by Hempel et al. (2013)'s method (Hempel method), and evaluated with the observation data of 50 stations from Korea Meteorological Administration. Among the 30 years (1981~2010) of simulation data, 20 years (1981~2000) of simulation data were used as a training data, and the remnant 10 years (2001~2010) data were used for the evaluation of correction. In general, the Hempel method and parametric quantile mapping show a reasonable correction both in mean and extreme climate of temperature. As the results, the systematic underestimation of mean temperature was greatly reduced after bias correction by Hempel method. And the overestimation of extreme climate, such as the number of TN5% and freezing day, was significantly recovered. In addition to that, the Hempel method better preserved the temporal trend of simulated temperature than other bias correction methods, such as the quantile mapping. However, the overcorrection of the extreme climate related to the upper quantile, such as TX5% and hot days, resulted in the exaggeration of the simulation errors. In general, the Hempel method can reduce the systematic biases embedded in the simulation results preserving the temporal trend but it tends to overcorrect the non-linear biases, in particular, extreme climate related to the upper percentile.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2015년도 학술발표회
• /
• pp.522-522
• /
• 2015

In this study, the effect of threshold applied to the radar rain rate on the comparison of the radar and rain gauge rain rate was theoretically examined. The result derived was also evaluated theoretically, using the Bernoulli random field, and empirically, using Mt. Kwanak weather radar data. The results are summarized as follows. (1) In the application to the Bernoulli random field, it was found that the comparison of the radar and rain gauge rain rate with threshold does not introduce any systematic bias. (2) The same results could also be derived in the application to Mt Kwanak weather radar data. In all cases with several radar bin sizes and thresholds considered, the bias was estimated to be far less than 10% of the mean of the rain gauge rain rate. (3) However, in the comparison with threshold applied to both the radar and rain gauge rain rate, the bias was estimated to be higher than 20%. That is, the systematic bias was introduced. This result indicates that the comparison with threshold applied to both the radar and rain gauge rain rate should not be used.

• Restorative Dentistry and Endodontics
• /
• 제47권4호
• /
• pp.40.1-40.18
• /
• 2022

Objectives: This study aimed to investigate the influence of different obturation techniques compared to cold lateral compaction on the success rate of primary non-surgical endodontic treatments. Materials and Methods: Systematic searches were performed for studies published up to May 17^th, 2022 in MEDLINE/PubMed, Cochrane Library, Web of Science, Scopus, EMBASE, and Grey Literature Reports. Randomized clinical trials and nonrandomized (nonrandomized clinical trials, prospective or retrospective) studies that evaluated the success rate of primary non-surgical endodontic treatments obturated with the cold lateral compaction (control) and other obturation techniques were included. The revised Cochrane risk of bias tools for randomized trials (RoB 2) and nonrandomized studies of interventions (ROBINS-I) were used to evaluate the risk of bias. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) tool was used to evaluate the certainty of evidence. Results: Eleven studies (4 randomized clinical trials (RCTs), 4 prospective, and 3 retrospectives) were included. Two RCTs were classified as having some concerns risk of bias and 2 as a low risk of bias. Two nonrandomized studies were classified as having a critical risk of bias and 5 as having a moderate risk of bias. The GRADE analysis demonstrated a very low to moderate certainty of evidence. Conclusions: This systematic review generally evidenced no differences in the success rate of primary non-surgical endodontic treatments when the cold lateral compaction technique and other obturation techniques are performed. Further well-designed studies are still necessary.

• Asia Marketing Journal
• /
• 제26권1호
• /
• pp.23-30
• /
• 2024

Firms often engage in manipulating online reviews as a promotional activity to influence consumers' evaluation on their products. With the prevalence of the promotional activities, consumers may notice and discount the reviews generated by the promotional activities. Discounting the firm-generating reviews may cause systematic measurement errors in the valence variable and lead to a negative bias when estimating the effect of consumers' organic reviews on demand. To correct the bias, this study proposes including product-specific bias-correction terms representing the proportion of extreme reviews in analysis. For illustration, the proposed method is applied to a demand model for data of movies released in South Korea. The results confirm a negative bias in the estimate of the valence sensitivity of demand. The negative bias potentially leads to an underestimation of the magnitude of the contagion effect through social interactions, a key component of evaluating the value of a satisfied consumer.

• 척추신경추나의학회지
• /
• 제11권2호
• /
• pp.11-21
• /
• 2016

Objectives : To determine the effectiveness of Chuna manual therapy for neck pain Methods : We searched 7 electronic databases(OASIS, NDSL, Ovid-MEDLINE, Ovid-EMBASE, Cochrane library, AMED, CNKI) to find all Randomized controlled trials that used Chuna manual therapy as a treatment for neck pain. The methodological quality of each RCT was assessed by the Cochrane risk of bias tool. Results : 7 RCTs met our inclusion criteria. The meta-analysis of 7 studies showed favorable results for the use of Chuna manual therapy. High risk of bias were observed for performance bias and detection bias. Conclusions : Our systematic review found favorable results using Chuna manual therapy for neck pain. But there are several limitations in our study due to lack of well-designed RCT. To obtain stronger evidence, further clinical trials would be needed.

• 동의생리병리학회지
• /
• 제34권6호
• /
• pp.299-308
• /
• 2020

This study aimed to evaluate the effects of Chuna therapy for Sciatica. We searched the following 16 online databases without a language restriction (Pubmed, Cochrane, Embase, CINAHL, Ovid, Kmbase, RISS, NDSL, OASIS, KISS, KNAL, KTKP, DBpia, CNKI, Wangfang, J-stage) to find randomized controlled clinical trials that used Chuna therapy for Sciatica. The methodological quality of randomized controlled clinical trials (RCTs) were assessed using the Cochrane risk of bias tool and meta-analysis were performed. Among 496 articles that were searched, 15 RCTs were finally selected for systematic review. 14 studies showed that Chuna therapy has positive effect on sciatica. Two studies noted that there were side effects, and the difference between the intervention group and the control group was statistically insignificant. One study noted no side effects and the rest of the study, there was no mention of side effects. Meta-analysis showed positive results for Chuna single therapy in terms of efficiency rate compared to painkiller, herb medicine excepting acupuncture. When comparing Chuna therapy plus acupuncture and acupuncture, Chuna therapy plus acupuncture had a more positive result than acupuncture in terms of efficiency rate. Cochrane Risk of Bias (RoB)evaluation method, most of the studies's selection, performance, detection and reporting bias were unclear. The studies showed that Chuna therapy can significantly effective on sciatica. However, most of the studies's Risk of Bias included in the analysis were not low enough. In the future, to prove the level of evidence of Chuna therapy, more high-quality studies will be needed.

• 척추신경추나의학회지
• /
• 제16권2호
• /
• pp.1-8
• /
• 2021

Objectives This study aimed to evaluate the effect of chuna manual therapy (CMT) for postpartum low back pain using a systematic review. Methods We performed a literature search using 12 electronic databases up to the end of September 2021. We included randomized controlled trials (RCTs) that evaluated the effect of CMT in the treatment of postpartum low back pain. The risk of bias was evaluated using the Cochrane risk-of-bias tool. Results Four randomized controlled trials were reported statistically significant effect in pain VAS, ODI and JOA of chuna manual therapy compared with moxibution, electro acupuncture, hyperthermia or usual care. As a result of assessing the risk of bias tool, most of the contents of the evaluation items were not identified, so it was evaluated as an uncertain risk. Conclusions CMT may be effective in treating postpartum low back pain. However, evidence was limited due to the small sample size, lack of well-designed RCTs and regional bias. Further well-designed studies are required to obtain stronger evidence.

• Korean Journal of Radiology
• /
• 제23권3호
• /
• pp.355-369
• /
• 2022

Objective: To evaluate the completeness of the reporting of systematic reviews and meta-analyses published in a general radiology journal using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. Materials and Methods: Twenty-four articles (systematic review and meta-analysis, n = 18; systematic review only, n = 6) published between August 2009 and September 2021 in the Korean Journal of Radiology were analyzed. Completeness of the reporting of main texts and abstracts were evaluated using the PRISMA 2020 statement. For each item in the statement, the proportion of studies that met the guidelines' recommendation was calculated and items that were satisfied by fewer than 80% of the studies were identified. The review process was conducted by two independent reviewers. Results: Of the 42 items (including sub-items) in the PRISMA 2020 statement for main text, 24 were satisfied by fewer than 80% of the included articles. The 24 items were grouped into eight domains: 1) assessment of the eligibility of potential articles, 2) assessment of the risk of bias, 3) synthesis of results, 4) additional analysis of study heterogeneity, 5) assessment of non-reporting bias, 6) assessment of the certainty of evidence, 7) provision of limitations of the study, and 8) additional information, such as protocol registration. Of the 12 items in the abstract checklists, eight were incorporated in fewer than 80% of the included publications. Conclusion: Several items included in the PRISMA 2020 checklist were overlooked in systematic review and meta-analysis articles published in the Korean Journal of Radiology. Based on these results, we suggest a double-check list for improving the quality of systematic reviews and meta-analyses. Authors and reviewers should familiarize themselves with the PRISMA 2020 statement and check whether the recommended items are fully satisfied prior to publication.

• 척추신경추나의학회지
• /
• 제16권2호
• /
• pp.21-28
• /
• 2021

Objectives To investigate the effectiveness of manual therapy for neck pain caused by traffic accidents. Methods We searched six electronic databases (OASIS, KISS, RISS, NDSL, MEDLINE, and Cochrane Library) to gather randomized controlled trials using the keywords 'manual theray OR chuna OR tuina' and 'whiplash injury OR neck sprain'. Results Eight RCTs were selected based on the inclusion criteria. Four studies were meta-analyses. The systematic review found a positive effect of manual therapy for whiplash injury. All studies showed a high risk of performance bias. Conclusions The systematic review reported favorable results using manual therapy for neck pain caused by traffic accidents. However, this study has several limitations owing to the high risk of bias. Further clinical studies and the development of a study design are required for stronger evidence.

• Restorative Dentistry and Endodontics
• /
• 제48권4호
• /
• pp.34.1-34.12
• /
• 2023

This systematic review aimed to investigate whether minimally invasive root canal preparation ensures higher fracture resistance compared to conventional root canal preparation in endodontically treated teeth (ETT). A comprehensive search strategy was conducted on the "PubMed, Web of Science, and Scopus" databases, alongside reference and hand searches, with language restrictions applied. Two independent reviews selected pertinent laboratory studies that explored the effect of minimally invasive root canal preparation on fracture resistance, in comparison to larger preparation counterparts. The quality of the studies was assessed, and the risk of bias was categorized as low, moderate, or high. The electronic search yielded a total of 1,767 articles. After applying eligibility criteria, 8 studies were included. Given the low methodological quality of these studies and the large variability of fracture resistance values, the impact of reduced apical size and/or taper on the fracture resistance of the ETT can be considered uncertain. This systematic review could not reveal sufficient evidence regarding the effect of minimally invasive preparation on increasing fracture resistance of ETT, primarily due to the inherent limitations of the studies and the moderate risk of bias.