• Title/Summary/Keyword: Data Bias

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Current Research Trend on the Acupuncture and Moxibustion Treatment for Pancreatitis (국내외 췌장염 관련 침구치료 연구 현황)

  • Kang, Ha Ra;Lee, Yeon Sun;Kim, Hye Ryeon;Kim, Eun Jung;Kim, Kyung Ho;Kim, Kap Sung;Jung, Chan Yung;Lee, Jun Kyu
    • Korean Journal of Acupuncture
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    • v.35 no.2
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    • pp.56-69
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    • 2018
  • Objectives : The aim of this study is to review the current research trend on the acupuncture and moxibustion treatment for pancreatitis. Methods : Through nine search engines, articles were collected, which had involved the use of acupuncture and moxibustion treatment for pancreatitis. Data were extracted from the selected articles regarding the year, country, type of pancreatitis, study design, evaluation variable, intervention, point for acupuncture and moxibustion, and effectiveness of treatment. Results : Total 56 articles were reviewed. The number of studies increased gradually every ten years. Fifty-one studies(91%) were conducted in China. Most of clinical studies and animal experimentations reported on acute pancreatitis. Thirty-nine studies were randomized controlled trials(RCTs), but most of them were assessed as uncertain in the risk of bias evaluation. The degree of overall improvement(79%) was used mainly as evaluation variable of clinical studies. In animal experimentations, the examination of pancreatitis tissue(77%) and blood test(77%) were used the most. Most of studies were conducted with the acupuncture, one with moxibustion. Among them, electroacupuncture was the most common intervention of treatment group. ST36 was the most frequently used acupuncture point in the included studies. Effective rate increased and serum amylase, clinical symptoms, recovery time of gastrointestinal function decreased statistically significantly in the treatment group of clinical studies. Conclusions : The result of this study could be used for the future practice and research about the acupuncture and moxibustion treatment for pancreatitis.

The Effect of Uncinate Process Resection on Subsidence Following Anterior Cervical Discectomy and Fusion

  • Lee, Su Hun;Lee, Jun Seok;Sung, Soon Ki;Son, Dong Wuk;Lee, Sang Weon;Song, Geun Sung
    • Journal of Korean Neurosurgical Society
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    • v.60 no.5
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    • pp.550-559
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    • 2017
  • Objective : Subsidence is a frequent complication of anterior cervical discectomy and fusion. Postoperative segmental micromotion, thought to be a causative factor of subsidence, has been speculated to increase with uncinate process resection area (UPR). To evaluate the effect of UPR on micro-motion, we designed a method to measure UPR area based on pre- and postoperative computed tomography images and analyzed the relationship between UPR and subsidence as a proxy of micro-motion. Methods : We retrospectively collected clinical and radiological data from January 2011 to June 2016. A total of 38 patients (53 segments) were included. All procedures included bilateral UPR and anterior plate fixation. UPR area was evaluated with reformatted coronal computer tomography images. To reduce level-related bias, we converted UPR area to the proportion of UPR to the pre-operative UP area (pUPR). Results : Subsidence occurred in 18 segments (34%) and positively correlated with right-side pUPR, left-side pUPR, and the sum of bilateral pUPR (sum pUPR) (R=0.310, 301, 364; p=0.024, 0.029, 0.007, respectively). Multiple linear regression analysis revealed that subsidence could be estimated with the following formula : $subsidence=1.522+2.7{\times}sum\;pUPR$($R^2=0.133$, p=0.007). Receiver-operating characteristic analysis determined that sum $pUPR{\geq}0.38$ could serve as a threshold for significantly increased risk of subsidence (p=0.005, area under curve=0.737, sensitivity=94%, specificity=51%). This threshold was confirmed by logistic regression analysis for subsidence (p=0.009, odds ratio=8.471). Conclusion : The UPR measurement method confirmed that UPR was correlated with subsidence. Particularly when the sum of pUPR is ${\geq}38%$, the possibility of subsidence increased.

Validation and selection of GCPs obtained from ERS SAR and the SRTM DEM: Application to SPOT DEM Construction

  • Jung, Hyung-Sup;Hong, Sang-Hoon;Won, Joong-Sun
    • Korean Journal of Remote Sensing
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    • v.24 no.5
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    • pp.483-496
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    • 2008
  • Qualified ground control points (GCPs) are required to construct a digital elevation model (DEM) from a pushbroom stereo pair. An inverse geolocation algorithm for extracting GCPs from ERS SAR data and the SRTM DEM was recently developed. However, not all GCPs established by this method are accurate enough for direct application to the geometric correction of pushbroom images such as SPOT, IRS, etc, and thus a method for selecting and removing inaccurate points from the sets of GCPs is needed. In this study, we propose a method for evaluating GCP accuracy and winnowing sets of GCPs through orientation modeling of pushbroom image and validate performance of this method using SPOT stereo pair of Daejon City. It has been found that the statistical distribution of GCP positional errors is approximately Gaussian without bias, and that the residual errors estimated by orientation modeling have a linear relationship with the positional errors. Inaccurate GCPs have large positional errors and can be iteratively eliminated by thresholding the residual errors. Forty-one GCPs were initially extracted for the test, with mean the positional error values of 25.6m, 2.5m and -6.1m in the X-, Y- and Z-directions, respectively, and standard deviations of 62.4m, 37.6m and 15.0m. Twenty-one GCPs were eliminated by the proposed method, resulting in the standard deviations of the positional errors of the 20 final GCPs being reduced to 13.9m, 8.5m and 7.5m in the X-, Y- and Z-directions, respectively. Orientation modeling of the SPOT stereo pair was performed using the 20 GCPs, and the model was checked against 15 map-based points. The root mean square errors (RMSEs) of the model were 10.4m, 7.1m and 12.1m in X-, Y- and Z-directions, respectively. A SPOT DEM with a 20m ground resolution was successfully constructed using a automatic matching procedure.

Uncertainty investigation and mitigation in flood forecasting

  • Nguyen, Hoang-Minh;Bae, Deg-Hyo
    • Proceedings of the Korea Water Resources Association Conference
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    • 2018.05a
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    • pp.155-155
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    • 2018
  • Uncertainty in flood forecasting using a coupled meteorological and hydrological model is arisen from various sources, especially the uncertainty comes from the inaccuracy of Quantitative Precipitation Forecasts (QPFs). In order to improve the capability of flood forecast, the uncertainty estimation and mitigation are required to perform. This study is conducted to investigate and reduce such uncertainty. First, ensemble QPFs are generated by using Monte - Carlo simulation, then each ensemble member is forced as input for a hydrological model to obtain ensemble streamflow prediction. Likelihood measures are evaluated to identify feasible member. These members are retained to define upper and lower limits of the uncertainty interval and assess the uncertainty. To mitigate the uncertainty for very short lead time, a blending method, which merges the ensemble QPFs with radar-based rainfall prediction considering both qualitative and quantitative skills, is proposed. Finally, blending bias ratios, which are estimated from previous time step, are used to update the members over total lead time. The proposed method is verified for the two flood events in 2013 and 2016 in the Yeonguol and Soyang watersheds that are located in the Han River basin, South Korea. The uncertainty in flood forecasting using a coupled Local Data Assimilation and Prediction System (LDAPS) and Sejong University Rainfall - Runoff (SURR) model is investigated and then mitigated by blending the generated ensemble LDAPS members with radar-based rainfall prediction that uses McGill algorithm for precipitation nowcasting by Lagrangian extrapolation (MAPLE). The results show that the uncertainty of flood forecasting using the coupled model increases when the lead time is longer. The mitigation method indicates its effectiveness for mitigating the uncertainty with the increases of the percentage of feasible member (POFM) and the ratio of the number of observations that fall into the uncertainty interval (p-factor).

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Development of Climate Data Management System Based on Satellite Imagery for Asia-Pacific Regions (아시아-태평양 지역 대상 위성영상 기반 기후 자료 관리 시스템 개발)

  • Park, Jihoon;Park, Kyungwon;Jung, Imgook;Cho, Wonil
    • Proceedings of the Korea Water Resources Association Conference
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    • 2019.05a
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    • pp.23-23
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    • 2019
  • 본 연구의 목적은 아시아-태평양 지역을 대상으로 위성영상 기반 고해상도의 신뢰성이 있고 쉽게 접근할 수 있는 강수 자료를 제공하는 데 있다. 본 연구에서 개발한 기후 관리 시스템은 총 3가지의 위성자료(원시위성자료, 편의보정한 위성자료, 공간상세화한 위성자료)를 제공한다. 위성자료의 공간해상도는 $0.1^{\circ}$, $0.05^{\circ}$이며, 시간해상도는 1 day이다. 비교적 신뢰성이 높은 기후 자료가 구축된 한반도를 대상으로 위성영상 편의보정, 공간상세화 기법을 검증하고, 개발한 기법을 아시아-태평양에 위치한 바누아투에 적용하여 기후 자료를 생산하였다. 원시위성자료는 TRMM (Tropical Rainfall Measurement Mission) 위성과 GPM (Global Precipitation Mission) 위성을 사용하여 구축하였다. 편의보정은 GRA-IDW (Geographical Ratio Analysis-Inverse Distance Weighted), GRA-Kriging, QM (Quantile Mapping) 기법을 검토하여 본 연구에 적합한 알고리즘을 개발하고 이 중 최적의 결과를 보여주는 GRA-IDW 기법을 최종적으로 선정하였다. 공간상세화는 PRISM (Parameter-elevation Regressions on Independent Slopes Model)을 선정하여 수행하였다. 원시위성자료를 검증한 결과를 살펴보면 상관계수는 1998년부터 2017년까지 0.775로 비교적 정확도가 높게 나왔다. bias 값은 원시위성자료 값이 지상관측자료보다 과대추정하는 것으로 나타났다. 최종적인 편의보정 기법으로 GRA-IDW 기법을 선정하여 편의보정한 위성자료를 생산하였다. 공간상세화한 위성자료를 검증한 결과를 앞서 분석한 원시위성자료, 편의보정한 위성자료와 비교하면, 공간상세화를 수행하기 전보다 상관계수는 다소 작아지고, RMSE는 커지는 것으로 나타나나 그 차이가 크지 않아 공간상세화한 위성자료를 응용분야에 직접 사용할 수 있을 것으로 분석된다. 본 연구를 통해 개발된 기법을 활용하면 아시아-태평양에 신뢰성 있는 기후 관측 자료를 제공할 수 있다. 향후 본 연구에서 선정한 대상지역 이외에 기상관측소의 수가 희박하고 불균등하게 분포하고 있는 아시아-태평양 지역에 본 과업에서 개발한 시스템을 적용하여 신뢰성 있는 기후 자료를 제공할 수 있을 것으로 사료된다.

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Application Analysis of Short-term Rainfall Forecasting Model according to Bias Correlation in Rainfall Ensemble Data (강우앙상블자료 편의보정에 따른 단기강우예측모델의 적용성 분석)

  • Lee, Sanghyup;Seong, Yeon-Jeong;Bastola, Shiksha;Choo, InnKyo;Jung, Younghun
    • Proceedings of the Korea Water Resources Association Conference
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    • 2019.05a
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    • pp.119-119
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    • 2019
  • 최근 기후변화와 이상기후의 영향으로 국지성 호우 및 가뭄, 홍수, 태풍 등 재해 발생 규모가 커지고 그 빈도 또한 많아지고 있다. 이러한 자연재해 및 이상현상에 대한 피해를 예방하고 빠르게 대처하기 위해서는 정확한 강우량 추정 및 강우의 시간적 예측이 필요하다. 이러한 강우의 불확실성을 해결하기 위해서 기상청 등에서는 단일 수치예보가 가지는 결정론적인 예측의 한계를 보완한 초기조건, 물리과정, 경계조건 등이 다른 여러 개의 모델을 수행하여, 확률적으로 미래를 예측하는 앙상블 예측 시스템을 예보기술에 응용하고 있으며 기존 수치모델의 정보와 예보 불확실성에 대한 정보를 동시에 제공하고 있다. 그러나 다양한 자연조건에 대한 불완전한 물리적 이해와 연산 능력 등의 한계로 높은 불확실성이 내포되어 있으므로 불확실성을 최소화하기 위한 편의보정이 수행될 필요가 있다. 강우분석의 적용 이전에 해당 자료의 타당성과 신뢰도의 분석이 필요하다. 본 연구에서는 LENS(Local ENsemble prediction System) 예측값과 시강우 관측값을 단기예측모델에 맞추어 3시간 누적하여 비교하였다. 비교 기간은 호우가 집중되는 2016년 10월로 선정하였으며 대상지역은 울산중구로 선정하였다. LENS를 대상 지역의 관측소 지점값과 행정구역 면적값을 따로 추출한 후, 불확실성을 최소화하기 위해 활용되고 있는 CF 기법과 QM 기법을 이용하여 LENS 모델을 재가공하고 이에 따른 편의보정 기법에 따른 LENS 모델을 과거의 실제강우 관측값과의 비교분석을 이용해 적용성을 검토 및 평가하였다.

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Analysis of Sensitivity, Correlation Coefficient and PCA of Input and Output Parameters using Fire Modeling (화재모델링을 이용한 입출력 변수의 민감도, 상관계수 분석과 주성분 분석)

  • Nam, Gi Tae;Kim, Jeong Jin;Yoon, Seok Pyo;Kim, Jun Kyoung
    • Journal of the Korean Society of Safety
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    • v.34 no.5
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    • pp.46-54
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    • 2019
  • Even though the fire performance-based design concept has been introduced for various structures and buildings, which have their own specific fire performance level, the uncertainties of input parameters always exist and, then, could reduce significantly the reliability of the fire modeling. Sensitivity analysis was performed with three limited input parameters, HRRPUA, type of combustible materials, and mesh size, which are significantly important for fire modeling. The output variables are limited to the maximum HRR, the time reaching the reference temperature($60^{\circ}C$), and that to reach limited visible distance(5 m). In addition, correlation coefficient analysis was attempted to analyze qualitatively and quantitatively the degree of relation between input and output variables above. Finally, the relationship among the three variables is also analyzed by the principal component analysis (PCA) to systematically analyze the input data bias. Sensitivity analysis showed that the type of combustible materials is more sensitive to maximum HRR than the ignition source and mesh size. However, the heat release parameter of the ignition source(HRR) is shown to be much more sensitive than the combustible material types and mesh size to both time to reach the reference temperature and that to reach the critical visible distance. Since the derived results can not exclude the possibility that there is a dependency on the fire model applied in this study, it is necessary to generalize and standardize the results of this study for the fire models such as various buildings and structures.

A Systematic Review and Meta-analysis on the Effect of Delirium Prevention Intervention in Korean Intensive Care Units (국내 중환자실 섬망 예방 중재에 관한 체계적 고찰 및 메타분석)

  • Kang, Jiyeon;Choi, Min Jeong
    • Journal of Korean Critical Care Nursing
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    • v.14 no.3
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    • pp.141-156
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    • 2021
  • Purpose : This study aimed to systematically review the preventive interventions for delirium in Korean intensive care unit (ICU) patients and evaluate their efficacy. Methods : For this systematic review and meta-analysis, we searched the literature and selected studies from data sources that included the RISS, KISS, National Central Library, National Assembly Library, DBpia, Science on, MEDLINE, and Cochrane Library. We used Cochrane's revised tool for risk of bias in randomized trials and non-randomized studies of intervention tools to assess the quality of the selected studies. The effect size of the intervention was calculated as odds ratio (OR) and standardized mean difference (SMD). Results : Preventive interventions reported in 23 studies with a total of 4,799 ICU patients were effective in reducing the occurrence of delirium (OR=0.64, 95% CI : 0.49~0.91, p=.011), but not the duration (SMD=-0.22, 95% CI : -0.51~0.08, p=.148). As a result of a subgroup analysis, non-pharmacological interventions were effective in reducing the occurrence of delirium (OR=0.66, 95% CI : 0.47~0.94, p=.020), while pharmacological interventions had no effect (OR=0.68, 95% CI : 0.33~1.40, p=.295). Among the non-pharmacological interventions, multi-component intervention had the largest effect size (OR=0.38, 95% CI : 0.26~0.55, p<.001). Conclusion : Non-pharmacological interventions were effective in reducing the occurrence of delirium. We recommend the development and application of multi-component interventions to prevent delirium in the Korean ICU patients.

Effects of garlic intake on cancer: a systematic review of randomized clinical trials and cohort studies

  • Lee, Jounghee;Zhao, Naisi;Fu, Zhuxuan;Choi, Jihee;Lee, Hae-Jeung;Chung, Mei
    • Nutrition Research and Practice
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    • v.15 no.6
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    • pp.773-788
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    • 2021
  • BACKGROUND/OBJECTIVES: Due to the rapid increase of global cancer incidence and mortality and a high level of interest in cancer prevention, a systematic review of garlic intake and cancer risk is needed. SUBJECTS/METHODS: We implemented a systematic review to examine the effects of varying levels of garlic intake on cancer. We conducted comprehensive literature searches in three electronic databases (MEDLINE, Embase, and Web of Science) for studies published between database inception and July or September of 2018. Two investigators independently screened abstracts and full-texts, extracted data, and assessed risk of bias (RoB). A total of one medium-quality randomized controlled trial (RCT) and 13 cohort studies graded as high RoB were included. RESULTS: The 1-year follow-up results from a RCT showed that a significant decrease in the number and size of colorectal adenomas among participants with colorectal adenomas who received high-dose aged garlic extract (AGE) compared with those who received low-dose AGE (P < 0.05). The results of prospective observational studies provided inconsistent associations of colorectal cancer risk with garlic supplements and garlic intake as food. CONCLUSIONS: In summary, the AGE was effective in reducing the number and magnitude of colorectal adenomas in one RCT, but there were inconsistent associations between garlic intake and colorectal cancer in cohort studies. Therefore, we could not draw a firm conclusion regarding the effects of garlic on cancer, because the current strength of evidence is inadequate due to a lack of number of high-quality RCTs.

Efficacy and Safety of the Antidiabetic effect of Hwangryunhaedok-tang for Type 2 Diabetes Mellitus Patients without Complications: A Systematic Review and Meta-Analysis (합병증을 동반하지 않은 2형 당뇨병 환자에 대한 황련해독탕의 혈당 강하 효과에 대한 유효성과 안전성 : 체계적 문헌 고찰과 메타분석)

  • Baek, Ji-soo;Shin, Seon-mi;Shin, Dong-guk;Cho, Chung-sik
    • The Journal of Internal Korean Medicine
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    • v.42 no.4
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    • pp.605-621
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    • 2021
  • Objectives: The purpose of this review is to assess the efficacy and safety of Hwangryunhaedok-tang for type 2 diabetes without complications by systemic review and meta-analysis of randomized controlled trials (RCTs). Methods: We searched the following up to March 31. 2021: PubMed, EMBASE, The Cochrane Library, CNKI, CiNii, KISS, KMBASE, OASIS, ScienceON. Data extraction and assessment of Cochrane's risk of bias (RoB) tool were performed by two independent authors, and if there was disagreement between two researchers, it was resolved through the intervention of a third researcher. Results: A total of seven trials are included in this systemic review. The treatment group (Hwangryunhaedok-tang plus conventional treatment) showed more statistically significant effects than did the control group (conventional treatment only) in fasting plasma glucose level, 2-hour postprandial plasma glucose level, glycated hemoglobin A1c, fasting insulin level, and HOMA-IR. There was no significant difference between the treatment group (Hwangryunhaedok-tang alone) and the control group (metformin alone). Conclusion: Hwangryunhaedok-tang might have efficacy and safety in controlling blood sugar level and improving insulin-resistance. However, the number of studies included in the meta-analysis was insufficient, and the Hwangryunhaedok-tang used in the included studies was not standardized. Also, the quality of the involved studies was generally low. Therefore, further studies are needed to determine the efficacy and safety of Hwangryunhaedok-tang treatment for type 2 diabetes mellitus.