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구조적 불연속에 기인하는 원통구조물의 응력집중현상에 관한 유한요소법에 의한 연구
김두만,정세헌 한국산업안전학회 1988 한국안전학회지 Vol.3 No.2
The stress concentration phenomena due to the structural incontinuty are studied by finite element method. In this study, a circular cylinder is treated. Under the axial load, the membrance action is dominate and the 24 D.O.F. cylindrical membrane finite element is used. The assembly of this element can successfully represent the original structure geometrically. The internal displacement function is such organized that the inter element compatibility condition is fully satisfied. In this study, the stress concentration factors due to the presence of a hole on the cylinder wall are obtained, and the factors versus the location of the hole is computed and plotted. It is found that the hole effect on the stress concentration disappears beyond the neighboring region of the hole size from the edge of the hole. Those results are useful for practical design in determining the region where the re-inforcing is necessary.
김두리,이정섭,최국명,김승형,고명주,송병철,이무숙,이경렬,고수연,김봉수 대한자기공명의과학회 2017 Investigative Magnetic Resonance Imaging Vol.21 No.2
Purpose: To compare three, motion-resistant, T1-weighted MR sequences on the hepatobiliary phase for gadoxetic acid-enhanced MR imaging of the liver. Materials and Methods: In this retrospective study, 79 patients underwent gadoxetic acid-enhanced, 3T liver MR imaging. Fifty-nine were examined using a standard protocol, and 20 were examined using a motion-resistant protocol. During the hepatocyte-specific phase, three MR sequences were acquired: 1) gradient recalled echo (GRE) with controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA); 2) radial GRE with the interleaved angle-bisection scheme (ILAB); and 3) radial GRE with golden-angle scheme (GA). Two readers independently assessed images with motion artifacts, streaking artifacts, liver-edge sharpness, hepatic vessel clarity, lesion conspicuity, and overall image quality, using a 5-point scale. The images were assessed by measurement of liver signal-to-noise ratio (SNR), and tumor-toliver contrast-to-noise ratio (CNR). The results were compared, using repeated posthoc, paired t-tests with Bonferroni correction and the Wilcoxon signed rank test with Bonferroni correction. Results: In the qualitative analysis of cooperative patients, the results for CAIPIRINHA had significantly higher ratings for streak artifacts, liver-edge sharpness, hepatic vessel clarity, and overall image quality as compared to, radial GRE, (P < 0.016). In the imaging of uncooperative patients, higher scores were recorded for ILAB and GA with respect to all of the qualitative assessments, except for streak artifact, compared with CAIPIRINHA (P < 0.016). However, no significant differences were found between ILAB and GA. For quantitative analysis in uncooperative patients, the mean liver SNR and lesion-to-liver CNR with radial GRE were significantly higher than those of CAIPIRINHA (P < 0.016). Conclusion: In uncooperative patients, the use of the radial GRE sequence can improve the image quality compared to GRE imaging with CAIPIRINHA, despite the data acquisition methods used. The GRE imaging with CAIPIRINHA is applicable for patients without breath-holding difficulties.
Effect of Having a Usual Source of Care on Medical Expenses – Using the Korea Health Panel Data
김두리,김솔잎,박혜경,하인혁,정보영,류원형,이상일,성낙진 대한의학회 2019 Journal of Korean medical science Vol.34 No.35
Background: There is a controversy about the effect of having a usual source of care on medical expenses. Although many studies have shown lower medical expenses in a group with a usual source of care, some have shown higher medical expenses in such a group. This study aimed to empirically demonstrate the effect of having a usual source of care on medical expenses. Methods: The participants included those aged 20 years and older who responded to the questionnaire about “having a usual source of care” from the Korean Health Panel Data of 2012, 2013, and 2016 (6,120; 6,593; and 7,598 respectively). Those who responded with “I do not get sick easily” or “I rarely visit medical institutions” as the reasons for not having a usual source of care were excluded. The panel regression with random effects model was performed to analyze the effect of having a usual source of care on medical expenses. Results: The group having a usual source of care spent 20% less on inpatient expenses and 25% less on clinic expenses than the group without a usual source of care. Particularly, the group having a clinic-level usual source of care spent 12% less on total medical expenses, 9% less on outpatient expenses, 35% less on inpatient expenses, and 74% less on hospital expenses, but 29% more on clinic expenses than the group without a usual source of care. Conclusion: This study confirmed that medical expenses decreased in the group with a usual source of care, especially a clinic-level usual source of care (USC), than in the group without a usual source of care. Encouraging people to have a clinic-level USC can control excessive medical expenses and induce desirable medical care utilization.
C-ITS 통신망 구축을 위한 통신 기술 동향 및 국내 C-ITS 통신 규격 선정에 대한 연구
김두리(DooRi Kim),김모세(MoSe Kim),김기천(KeeCheon Kim) 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.6
기존 ITS의 한계를 극복하고 최근 C-ITS 사업이 확장됨에 따라 사고를 방지하는 안전 운전과 사고를 빠르게 대응하여 2차 사고를 막을 수 있는 교통체계가 설립되고 있다. 단방향으로 정보를 수집하는 ITS와 달리 C-ITS는 차량과 차량, 차량과 인프라 간 양방향으로 정보를 공유할 수 있어 교통안전 관리에 더욱 효과적이다. 성공적인 C-ITS의 상용화를 위하여 국내 실정에 맞는 V2X 기술의 통신 규격의 결정이 필요하다. 본 논문에서 국내 V2X 통신 방식인 WAVE와 C-V2X의 차이점을 기술하고 국내 C-ITS 통신 규격 전망에 대해 소개한다.
지방정책네트워크가 분권적 규제집행에 미치는 영향: 한국 지방정부 환경규제를 중심으로
김두래 한국행정학회 2010 韓國行政學報 Vol.44 No.4
본 연구는 정책집행 권한이 지방정부로 부분적으로 위임되어 있는 분권적 정책과정에서 지방정책네트워크의 역할이 무엇인지를 환경정책의 영역에서 탐색하였다. 첫째, 지방정책네트워크는 일선관료의 직접적 과업환경을 구성하고 있고 정책결정자의 중요한 정치적 자원이므로 그 구성원들의 지배적 이념성향에 따라 지방정부의 규제집행이 조응할 것으로 보았다. 둘째, 지방정책네트워크를 구성하는 지역조직이 활성화되어 있을수록 정책문제와 규제활동에 대한 정보비대칭성을 저감시켜 지방정부의 규제집행을 강화시킬 것으로 보았다. 한국 지방정부 규제활동에 대한 분석의 결과는 지방정부의 정책역량, 환경문제의 심각성, 사회경제적 조건 등 다양한 요인들의 영향을 통제한 상태에서 지방정책네트워크의 진보적 이념성향과 시민조직의 활성화 수준이 지방정부의 환경규제 집행노력과 처벌강도를 증가시키는 경향이 있다는 실증적으로 보여주었다. 이러한 연구결과를 바탕으로 지방정책네트워크의 요인들이 분권적 집행체제에서 발생할 수 있는 환경규제의 지역격차를 완화시킴으로써 정책목표의 달성에 긍정적인 효과를 갖는다는 함의를 도출할 수 있다.