• Title/Summary/Keyword: 발견율

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Application of False Discovery Rate Control in the Assessment of Decrease of FDG Uptake in Early Alzheimer Dementia (조기 알츠하이머 치매의 뇌포도당 대사 감소 평가에서 오류발견률 조절법의 적용)

  • Lee, Dong-Soo;Kang, Hye-Jin;Jang, Myung-Jin;Cho, Sang-Soo;Kang, Won-Jun;Lee, Jae-Sung;Kang, Eun-Joo;Lee, Kang-Uk;Woo, Jong-In;Lee, Myung-Chul
    • The Korean Journal of Nuclear Medicine
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    • v.37 no.6
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    • pp.374-381
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    • 2003
  • Purpose: Determining an appropriate thresholding is crucial for PDG PET analysis since strong control of Type I error could fail to find pathological differences between eariy Alzheimer' disease (AD) patients and healthy normal controls. We compared the SPM results on FDG PET imaging of early AD using uncorrected p-value, random-field based corrected p-value and false discovery rate (FDR) control. Materials and Methods: Twenty-eight patients ($66{\pm}7$ years old) with early AD and 18 age-matched normal controls ($68{\pm}6$ years old) underwent FDG brain PET. To identify brain regions with hypo-metabolism in group or individual patient compared to normal controls, group images or each patient's image was compared with normal controls usingthe same fixed p-value of 0.001 on uncorrected thresholding, random-field based corrected thresholding and FDR control. Results: The number of hypo-metabolic voxels was smallest in corrected p-value method, largest in uncorrected p-value method and intermediate in FDG thresholding in group analysis. Three types of result pattern were found. The first was that corrected p-value did not yield any voxel positive but FDR gave a few significantly hypometabolic voxels (8/28, 29%). The second was that both corrected p-value and FDR did not yield any positive region but numerous positive voxels were found with the threshold of uncorrected p-values (6/28, 21%). The last was that FDR was detected as many positive voxels as uncorrected p-value method (14/28, 50%). Conclusions FDR control could identify hypo-metaboiic areas in group or individual patients with early AD. We recommend FDR control instead of uncorrected or random-field corrected thresholding method to find the areas showing hypometabolism especially in small group or individual analysis of FDG PET.

Neuroimaging of Traumatic Brain Injury (외상성 뇌손상의 영상진단)

  • Choi, Woo Suk
    • Korean Journal of Biological Psychiatry
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    • v.2 no.2
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    • pp.169-176
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    • 1995
  • 두부 외상은 많은 발생율과 사망율을 차지하고 있으며, 건강한 생활을 위해 큰 관심을 갖게 되었다. 신경방사선영상은 외상성 뇌손상 환자들의 진단과 치료에 필수적인 방법이다. 뇌손상의 기본 기전, 병리, 그리고 영상 소견을 이해 하는 것은 매우 중요하다. 1970년대에 Glasgow coma scale의 형상과 전산화단층촬영(CT)의 발달은 임상의사들이 두부외상에 대한 평가와 환자들의 경과를 예상하는데 극적인 변화를 주었다. 최근 자기공명영상(MRI)의 발달로 외상성 뇌손상의 형태를 더욱 이해 하게 되었고, 두부 외상의 발견율이 높아지게 되었다.

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A Parameter Estimation of Software Reliability Growth Model with Change-Point (변화점을 고려한 소프트웨어 신뢰도 성장모형의 모수추정)

  • Kim, Do-Hoon;Park, Chun-Gun;Nam, Kyung-H.
    • The Korean Journal of Applied Statistics
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    • v.21 no.5
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    • pp.813-823
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    • 2008
  • The non-homogeneous Poisson process(NHPP) based software reliability growth models are proved quite successful in practical software reliability engineering. The fault detection rate is usually assumed to be the continuous and monotonic function. However, the fault detection rate can be affected by many factors such as the testing strategy, running environment and resource allocation. This paper describes a parameter estimation of software reliability growth model with change-point problem. We obtain the maximum likelihood estimate(MLE) and least square estimate(LSE), and compare goodness-of-fit.

A Study on the Effectiveness of Screening for Selective Breast Cancer Using Digital Mammography Centered on General Hospital (디지털 유방촬영술을 이용한 선별적 유방암 검진의 효용성에 대한 연구(2차 병원을 중심으로))

  • Kim, Hyeon-Jin
    • Journal of the Korean Society of Radiology
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    • v.15 no.2
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    • pp.147-152
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    • 2021
  • This study is a retrospective analysis of the results of tests at three general hospitals in Busan that perform mammography using digital mammography devices. There were 5,320 people in the study, and the results of their breast cancer screening were analyzed to verify the efficacy of breast cancer screening for digital mammography. The average age of patients who performed breast cancer screening was 57.7 years (range 30 to 87 years), and the cancer detection rate was 26, with 4.6 cases per 1,000 people. According to the cancer detection rate by risk factor in patients who conducted breast cancer screening, breast cancer was found in patients without underlying diseases more than in patients with underlying diseases. Additional ultrasound examinations show that the gastronomic rate identified is 3.6%, which is relatively very low compared to that of the Film-Screen system.

Seabird Distribution Patterns by Sighting Survey in the East Sea in Spring (목시조사(Sighting survey)에 의한 동해 봄철 해양성 조류의 분포 양상)

  • Kim, Hyun-Woo;Kim, Zang-Geun;Choi, Seok-Gwan
    • Korean Journal of Environment and Ecology
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    • v.25 no.2
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    • pp.123-131
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    • 2011
  • Seabird distribution in the East Sea was studied from April to May 2007 using line transect counts. We observed a total of 1,379 individuals of 23 species including 14 species of seabird. The overall seabird sighting rate was 2.5 birds $km^{-2}$. The Streaked shearwater(Calonectris leucomelas)(74.5%) was the numerically dominant species. Ancient murrelets(Synthliboramphus antiquus)(8.3%), red-throated divers(Gavia stellata)(5.0%), common terns(Sterna hirundo)(2.1%), Pacific divers(Gavia pacifica)(2.0%), and black-tailed gulls (Larus crassirostris)(1.1%) were also frequently observed. The sightings of seabirds was highest between $36^{\circ}N$ and $37^{\circ}N$ of the coastal area of the Korean peninsular. However, the index of species diversity(H') was higher between $35^{\circ}N$ and $36^{\circ}N$. The sighting rates of most observed species decreased with distance from the coastline. The distribution patterns of Streaked shearwater were linked to the variation in the distribution pattern of minke whales(Balaenoptera acutorostrata). Also, spatial segregation was found in the distributions of the two species of divers(Gavia spp.).

Optimal Time to Localize Bleeding Focus and the Usefulness of Flexible Bronchoscopy in Hemoptysis (객혈에서 굴곡성 기관지경의 출혈부위 결정을 위한 적절한 시행시기 및 그 유용성)

  • Lee, Jae-Ho;Koh, Won-Joong;Lee, Chan-Ju;Chung, Hee-Soon
    • Tuberculosis and Respiratory Diseases
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    • v.49 no.3
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    • pp.353-364
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    • 2000
  • Background : Bronchoscopy is a useful diagnostic tool, for accurate localization of the bleeding site and the management of hemoptysis. However, there is some controversy about the optimal timing of bronchoscopy. Method : To determine the optimal timing of bronchoscopy in hemoptysis, we reviewed the medical records of 118 patients and analyzed the following relationships amongst simple chest PA findings, namely, the duration and amount of hemoptysis, and the timing of bronchoscopy retrospectively. Results : The major causes of hemoptysis were active tuberculosis(28.8%), inactive tuberculosis(10.2%), bronchiectasis(17.0%), lung cancer(7.6%), and aspergilloma(7.6%). Localization of the bleeding focus by bronchoscopy was possible in 87.5% (21/24 cases) during active bleeding, and it was possible in 40.4% after bleeding had stopped(p<0.05). The localization rate of bleeding focus was 59.8% when the chest PA showed certain abnormalities, but it decreased to 27.8% when the chest PA finding was normal(p<0.05). When chest PA showed diffuse abnormalities or its finding was normal, the localization rate of bleeding focus significantly increased if bronchoscopy was performed during bleeding or within 48 hours of the cessation of active bleeding. The localization rate was higher as the amount of hemoptysis became larger(p<0.05). The localization rate of early bronchoscopy(during bleeding or within 48 hours of the cessation of active bleeding) was significantly higher when the duration of hemoptysis was less than 1 week, but there was no advantage if the duration was 1 week or longer. Early bronchoscopy was also necessary to localize the bleeding focus for surgical resection in 4 patients, and the bronchoscopy itself was therapeutic in 1 patient whose bleeding was successfully managed with thrombin-application via bronchoscope. Conclusion : It is concluded that flexible bronchoscopy is useful at not only localizing the bleeding focus but also in preparing a therapeutic plan, and early bronchoscopy is more favorable in hemoptysis.

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Comparison and analysis of multiple testing methods for microarray gene expression data (유전자 발현 데이터에 대한 다중검정법 비교 및 분석)

  • Seo, Sumin;Kim, Tae Houn;Kim, Jaehee
    • Journal of the Korean Data and Information Science Society
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    • v.25 no.5
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    • pp.971-986
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    • 2014
  • When thousands of hypotheses are tested simultaneously, the probability of rejecting any true hypotheses increases, and large multiplicity problems are generated. To solve these problems, researchers have proposed different approaches to multiple testing methods, considering family-wise error rate (FWER), false discovery rate (FDR) or false nondiscovery rate (FNR) as a type I error and some test statistics. In this article, we discuss Bonferroni (1960), Holm (1979), Benjamini and Hochberg (1995) and Benjamini and Yekutieli (2001) procedures based on T statistics, modified T statistics or local-pooled-error (LPE) statistics. We also consider Sun and Cai (2007) procedure based on Z statistics. These procedures are compared in the simulation and applied to Arabidopsis microarray gene expression data to identify differentially expressed genes.

성공적인 인공수정

  • 김윤식
    • 종축개량
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    • v.20 no.2
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    • pp.118-121
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    • 1998
  • 인공수정은 정확한 발견, 고도의 기술, 우군의 수태율, 정액의 질 등이 정상적인 임신을 하기 위해 필요한 요소들이다. 분만율을 높이기 위해 가능하는 한 위의 모든 사항을 염두에 두고 경영을 해야 ?다.

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거래량은 주가에 선행하는가? - 한국 주식시장에서의 실증분석 -

  • Kim, Yeong-Bin
    • The Korean Journal of Financial Studies
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    • v.3 no.1
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    • pp.301-327
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    • 1996
  • 본 연구에서는 한국 주식시장에 있어서 거래량이 주가에 선행하는가를 일별자료를 이용하여 전통적인 선형Granger인과관계의 검증법과 Baek and Brock(1992a)의 비선형Granger인과관계의 검증법에 따라 전체기간과 주식시장 장세별로 실증분석을 실시하였다. 본 연구에서 발견된 실증분석 결과는 다음과 같이 요약될 수 있다. 첫째, 선형인과관계 검증의 결과, 전체기간에서 거래량변화율과 주식수익률간의 상호인과관계가 존재하였다. 주식시장 장세별로는 침체기에만 주식수익률이 거래량변화율에 선행하는 것으로 나타났다. 둘째, 비선형인과관계 검증의 결과, 전체기간에서는 선형인과관계의 검증결과와 동일하였다. 장세별 분석에서는 상승기와 회복기에는 거래량변화율과 주식수익률간에 인과관계가 없지만, 침체기에는 주식수익률이 거래량변화율에 선행하는 것으로 나타났다. 본 연구에서 발견된 실증분석 결과는 우리나라 주식시장에서 거래량이 주가의 예측변수로서 활용될 수 없다는 점을 시사하고 있는 것으로 생각된다.

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