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이찬주(Lee Chan Joo),김용전(Kim Yong Jeon),김지성(Kim Ji Sung),김원(Kim Won) 대한토목학회 2010 대한토목학회논문집 B Vol.30 No.2B
본 연구는 국내 9개 하천에서 실측한 자료를 사용하여 하상재료의 입경에 기초한 자갈하천의 조도계수 특성을 분석하는데 그 목적이 있다. 조도계수는 Manning 식을 역산하여 산정하였다. 산정된 조도계수는 유량에 따라 대체로 감소하였으며, 일정한 유량 이상에서는 수렴하는 특성을 나타냈다. 마찬가지로, 상대수심(R/D)이 증가함에 따라 조도계수는 감소하는 경향을 보여주었으며, 실측 자료를 이용하여 적합식을 구한 결과 Limerinos(1970) 식과 매우 유사한 결과를 보여주었다. 일정한 유량 이상에서 수렴된 조도계수값은 0.024~0.045의 범위에 있었으며, 이를 기초로 하상재료만을 고려한 조도계수 산정식을 도출하고 기존의 식과 비교하였다. The purpose of this study is to analyse characteristics of roughness coefficient based on bed-material size of the gravel-bed rivers using field data obtained from nine domestic rivers. Roughness coefficient is calculated using Manning's equation. Roughness coefficient decreases with increasing discharge, but above a certain discharge, it tends to be constant. Similarly, roughness coefficient shows reverse relationship with relative smoothness (R/D). The regression equation adopting theoretically derived value of 2.03 as log coefficient indicates close similarity with the previous equation proposed by Limerinos (1970). Roughness coefficient values converged above certain discharges lie in the range from 0.024 to 0.045. From them, empirical equations based only on bed-material size are derived and compared with those suggested by the previous studies.
한국인 가족성 고콜레스테롤혈증 진료에 대한 2022년 합의안
이찬주 ( Chan Joo Lee ),윤민재 ( Minjae Yoon ),강현재 ( Hyun-jae Kang ),김병진 ( Byung Jin Kim ),최성희 ( Sung Hee Choi ),정인경 ( In-kyung Jeong ),이상학 ( Sang-hak Lee ) 대한내과학회 2022 대한내과학회지 Vol.97 No.6
Familial hypercholesterolemia (FH) is the most common monogenic disorder. Due to the marked elevation of cardiovascular risk, the early detection, diagnosis, and proper management of this disorder are critical. Herein, the 2022 Korean guidance on this disease is presented. Clinical features include severely elevated low-density lipoprotein cholesterol (LDL-C) levels, tendon xanthomas, and premature coronary artery disease. Clinical diagnostic criteria include clinical findings, family history, or pathogenic mutations in the LDLR, APOB, or PCSK9. Proper suspicion of individuals with typical characteristics is essential for screening. Cascade screening is known to be the most efficient diagnostic approach. Early initiation of lipid-lowering therapy and the control of other risk factors are important. The first-line pharmacological treatment is statins, followed by ezetimibe, and PCSK9 inhibitors as required. The ideal treatment targets are 50% reduction and < 70 or < 55 mg/dL (in the presence of vascular disease) of LDL-C, although less strict targets are frequently used. Homozygous FH is characterized by untreated LDL-C > 500 mg/dL, xanthoma since childhood, and family history. In children, the diagnosis is made with criteria, including items largely similar to those of adults. In women, lipid-lowering agents need to be discontinued before conception. (Korean J Med 2022;97:339-352)
Cohesive zone model을 이용한 접착제 물성평가 : 모드 Ⅰ
이찬주(C.J. Lee),이상곤(S.K. Lee),고대철(D.C. Ko),S. Marzi,박근환(G.H. Park),김병민(B.M. Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Fracture models and criteria of adhesive with two parameters, namely G<SUB>C</SUB> and σ<SUB>max</SUB>, have been developed to describe the fracture process of adhesive joints. Cohesive zone model(CZM) is a representative two parameter failure criteria approach. In CZM, σ<SUB>max</SUB> is a critical, limiting maximum value of the stress in the damage zone ahead of the crack and is assumed to have some physical significance in adhesive failure. Based on CZM and finite element analysis method, the relationship between fracture load and adhesive properties, as G<SUB>IC</SUB> and(σ<SUB>max</SUB>)<SUB>I</SUB>, was investigated in adhesively bonded joint tensile test and T-peel test. The two parameters in tensile mode loading were evaluated by using the relationship. The value of G<SUB>IC</SUB> evaluated by proposed method showed close agreement with analytical solution for tapered double cantilever beam(TDCB) test which proposed in an ASTM standard.
Cohesive Zone Model 을 이용한 접착제 물성평가 : 모드 I
이찬주(Chan-Joo Lee),이상곤(Sang-Kon Lee),고대철(Dae-Cheol Ko),김병민(Byung-Min Kim) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.5
Fracture models and criteria of adhesive with two parameters, namely GC and σmax , have been developed to describe the fracture process of adhesive joints. Cohesive zone model(CZM) is a representative two parameter failure criteria approach. In CZM, σmax is a critical, limiting maximum value of the stress in the damage zone ahead of the crack and is assumed to have some physical significance in adhesive failure. Based on CZM and finite element analysis method, the relationship between fracture load and adhesive properties, , as GIC and (σmax)I, was investigated in adhesively bonded joint tensile test and T-peel test. The two parameters in tensile mode loading were evaluated by using the relationship. The value of GIC evaluated by proposed method showed close agreement with analytical solution for tapered double cantilever beam(TDCB) test which proposed in an ASTM standard.