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선형탄성해석과 m<sub>α</sub>-tangent방법을 이용한 배관 한계하중 평가 적용성
김재민,김상현,배경동,김윤재,김종성,Gim, Jae-Min,Kim, Sang-Hyun,Bae, Kyung-Dong,Kim, Yun-Jae,Kim, Jong-Sung 대한기계학회 2017 大韓機械學會論文集A Vol.41 No.6
본 연구에서는 선형탄성 유한요소해석 방법과 $m_{\alpha}-tangent$ 방법으로 한계하중을 계산하고 이를 기존의 연구들에 의해 제시된 한계하중 식들과 비교하였다. 해석의 대상은 배관계의 대표 형상인 곡관과분기관을 선정하였다. 곡관과 분기관의 형상 변수를 다양하게 바꿔가면서 $m_{\alpha}-tangent$ 방법의 적용가능성을 살펴보았다. 하중은 내압하중과 면내굽힘하중을 각각 고려하였으며 곡관의 경우에는 기존의 한계하중식과 $m_{\alpha}-tangent$방법이 비교적 잘 일치함을 확인하였다. 하지만 분기관의 경우 형상의 특수성으로 인해 뚜렷한 경향 없이 기존의 한계하중 식과 $m_{\alpha}-tangent$ 방법이 일치하지 않는 것을 확인할 수 있었다. 이는 $m_{\alpha}-tangent$ 방법이 불연속부의 응력집중현상에 의해 왜곡된 결과를 갖기 때문으로 보인다. In this study, the limit loads calculated by the $m_{\alpha}-tangent$ method based on the linear finite element analysis are compared with the closed form solutions that are proposed by various authors. The objects of the analysis is to select the elbow and the branch pipe which are representative structure of piping system. The applicability of the $m_{\alpha}-tangent$ method are investigated by applying it to cases with various geometries. The internal pressure and the in-plane bending moment are considered and the $m_{\alpha}-tangent$ method is in good agreement with the existing solutions in case of elbows. However, the limit loads calculated by the $m_{\alpha}-tangent$ method for branch junctions do not agree well with the existing solutions and do not show any tendency. The reason is a biased result due to the stress concentration of the discontinuous parts.
광섬유센서가 내장된 강연선을 이용한 교량의 장력 모니터링 방법
김재민,김현우,김영상,김진원,윤정방,Kim, Jae-Min,Kim, Hyun-Woo,Kim, Young-Sang,Kim, Jin-Won,Yun, Chung-Bang 한국전산구조공학회 2008 한국전산구조공학회논문집 Vol.21 No.3
이 연구에서는 교량 상부구조물의 보수 보강에 많이 사용되는 7연 강연선의 공용중 긴장력 관리를 위한 새로운 방법은 제안하였다. 제안된 스마트 강연선은 기존 강연선의 중앙 킹와이어를 강제튜브로 대체하고, 강제튜브의 내부에 FBG 광섬유센서를 설치하여 강연선의 변형률을 측정할 수 있도록 하였다. 내장된 센서를 통하여 이 스마트 강연선의 변형률을 쉽게 측정할 수 있으므로, 공용중 강연선의 긴장력을 모니터링할 수 있다. 본 연구에서 제안된 장력 모니터링 방법의 효용성을 증명하기 위하여 FBG센서 2개가 내장된 길이 7.0m인 스마트 강연선을 제작하고, 이를 길이 6.4m, 높이 0.6m인 RC T형 모형거더에 외장형 텐던으로 적용하였다. 그리고 이 시험거더에 대한 재하-제하시험을 실시하고 로드셀에서 계측된 긴장력과 스마트 강연선을 이용하여 예측한 긴장력을 비교하였다. 비교 결과, 제안된 스마트 강연선은 긴장력이 작용된 강연선의 장력을 정확하게 모니터링 하는데 유용함을 확인할 수 있었다. This study proposes a novel method for in service evaluation of tension force of a prestressed 7-wire strand which is frequently employed for retrofitting bridge superstructure. The smart strand is made by replacing the straight king wire of the strand with an instrumented steel tube in which the FBG sensor is embedded. Since the strain of the smart strand can easily be measured using the sensor, it is possible to monitor tension force of the strand during the service. For the sake of demonstrating effectiveness of the proposed strand, we came up with a 7.0m long prototype with 2 FBG sensors, and it is applied as an external tendon to a 6.4m long and 0.6 high RC T-shaped beam. A loading-unloading test has been carried out, and estimated tension forces using the smart strand are compared with measured forces by load cell. The comparison showed that the proposed smart tendon is useful and accurate for monitering tension force of the prestressed tendon.
Ghrelin Modifies the Impact of Life Stress on Suicidality in Patients With Acute Coronary Syndrome
김재민,Kang Hee-Ju,Kim Ye-Jin,Kim Ju-Wan,Choi Wonsuk,Lee Ju-Yeon,Kim Sung-Wan,Kim Jung-Chul,Ahn Youngkeun,Jeong Myung Ho 대한신경정신의학회 2023 PSYCHIATRY INVESTIGATION Vol.20 No.4
Objective This study investigated associations of life stressors and serum ghrelin levels with suicidal ideation (SI), and evaluated the potential mediating effect of ghrelin on associations between life stressors and SI in patients with acute coronary syndrome (ACS).Methods In total, 969 ACS patients recruited from a tertiary university hospital in Korea within 2 weeks of disease onset were evaluated in terms of life stressors (using the List of Threatening Events Questionnaire), serum ghrelin levels, and SI (using the “suicidal thoughts” item of the Montgomery–Asberg Depression Rating Scale). Covariates included sociodemographics, depression, vascular risk factors, and disease severity. After 1 year, 711 patients were re-evaluated in terms of SI; logistic regression was performed with adjustment for covariates.Results Life stressors were significantly associated with SI at baseline and follow-up. Serum ghrelin showed no such associations, but high levels thereof mediated associations of life stressors with SI; significant interaction terms were also observed after adjustment for covariates.Conclusion By evaluating life stressors and serum ghrelin levels, clinical prediction of SI in the acute and chronic phases of ACS could be improved.
노인의 인지감퇴에 미치는 아포지단백 E4와 교육수준의 상호작용
김재민,신일선,김성완,양수진,박상욱,신희영,윤진상,Kim, Jae-Min,Shin, Il-Seon,Kim, Sung-Wan,Yang, Su-Jin,Park, Sang-Wook,Shin, Hee-Young,Yoon, Jin-Sang 대한생물정신의학회 2008 생물정신의학 Vol.15 No.1
Objectives : This study aimed to test potential modifying effects of education on the association between apolipoprotein E ${\varepsilon}4$ (Apo E4) and cognitive decline. Methods : A community cohort(N=683) aged 65 or over completed the Korean version of Mini-Mental State Examination(MMSE-K) at baseline and two years later(1999-2001). Apo E polymorphisms were genotyped, and classified into that with or without Apo E4. Educational levels were categorized into people with or without education. Covariates included demographic(age, gender), life style(smoking, alcohol drinking), clinical (depression, sleep disorder, vascular risk factors) characteristics. Results : The association between Apo E4 and cognitive decline was significant only in the old persons with no education. The interaction term between education and Apo E4 on cognitive decline was significant(p=0.040). Conclusion : Elders with no education might be more vulnerable to the impact of Apo E4 on cognitive decline, which suggests gene-environment interaction.
지혜 깊어지는 건강_50대를 지키는 밥상: 기름기를 쏙 뺀 웰빙초계탕
김재민,Kim, Jae-Min 한국건강관리협회 2011 건강소식 Vol.35 No.7
날씨가 더운 여름이면 남녀노소 누구나 땀으로 흘린 원기를 보충하기 위해 보양 음식, 찬 음식을 찾게 된다. 그러나 보양 음식은 기름진 육식이 대부분이라 장에 무리를 줄 수 있고 찬 음식은 장에 탈이 날 수 있는데 닭고기는 찬 성질을 가지고 있지만, 장과 위를 보호해 차게 먹어도 탈이 나지 않는 음식이다.
식재료 표준화 체계에 대한 학교 급식 영양(교)사 인식 조사
김재민,김창식,장윤정,한지희,함선옥,Kim, Jae-Min,Kim, Chang-Sik,Jang, Yoon-Joung,Han, Ji-Hee,Ham, Sunny 한국식생활문화학회 2018 韓國食生活文化學會誌 Vol.33 No.5
The standardization of food ingredients in the procurement system is essential to maintain the quality of food services. Currently, school food services in Korea do not have such a standardized system, which results in inconsistency of the procurement procedure of food ingredients. This study examined how school foodservice nutritionists perceive the standardization of food ingredients in the procurement system. In particular, this study investigated school foodservice nutritionists' perception on the appropriateness, convenience, and necessity of newly proposed standardized procurement system consisting of a classification and attribute system. A total of 311 nutritionists from 123 elementary schools, 99 middle schools, and 84 high schools were surveyed via both online and offline from June 16-24, 2016. The major findings of the study are as follows. First, three quarters of the nutritionists perceived the newly proposed standardized procurement system to be necessary, while approximately sixty percent of the respondents reported that the newly proposed standardized procurement system is convenient. More than half of the respondents perceived the newly proposed standardized procurement system to be appropriate. The results suggest that the new standardized system directs a better way in terms of the classification and attribute systems of food ingredients. This study suggests that the standardization of food ingredients should be implemented at the operation of school food services.