철근콘크리트 휨부재의 최소철근비에 대한 고찰

최승원,Choi, Seung-Won 한국구조물진단유지관리공학회 2017 한국구조물진단유지관리공학회 논문집 Vol.21 No.6

The minimum reinforcement ratio is an important design factor to prevent a brittle failure in RC flexural members. A minimum reinforcement ratio is presented by assuming an effective depth of cross-section and moment arm lever in CDC and KHBDC. In this study, it suggests that a rational method for minimum reinforcement ratio is calculated by material model and force equilibrium. As results, a minimum reinforcement ratio using a p-r curve in KHBDC is evaluated about 52~80% of recent design code's value and it induces an economical design. And also, a ductility capacity in case of placing this minimum reinforcement amount is evaluated about 89% of recent design code's value, but ductility in a member is 7 or more, so it has a sufficient ductility capacity. Therefore, it is judged that a minimum reinforcement ratio using p-r curve has a theoretical rationality, safety and economy in a flexural member design.

산화제 NaOCl와 $H_2O_2$를 이용한 광산배수 정화에 관한 연구

최승원,장윤득,김영훈,김정진,Choi, Seung-Won,Jang, Yun-Deug,Kim, Young-Hun,Kim, Jeong-Jin 대한자원환경지질학회 2010 자원환경지질 Vol.43 No.1

Mine and leachate waters were collected from the Okdong mine for study on reaction with oxidizing agents such as NaOCl and $H_2O_2$. The pH and EC of the mine and leachate waters are 5.77, 831 uS/cm, and 6.38, 1920 uS/cm, respectively. The concentrations of Mg, Mn, and Zn are 23.25 mg/l, 14.90 mg/l, and 22.99 mg/l for the mine water and 98.75 mg/l, 3.38 mg/l, and 6.16 mg/l for the leachate water. The concentrations of Mg, Mn and Zn decreased after the reaction with the oxidizing agents and mine water. The concentrations of Mg, Mn and Zn rapidly decreased when oxidizing agents increased. The saturation indices that were computed by visual MINTEQ for initial mine and leachate water were undersaturated with Mg, Zn and Mn compounds. The precipitates after the reaction with the oxidizing agents are composed mainly of mangano-calcite[(Mn, Ca)$CO_3$] with small amount of calcite-magnesian and calcite.

유로코드 2 재료모형을 사용한 철근콘크리트 부재의 연성도 평가

최승원,Choi, Seung Won 대한토목학회 2015 대한토목학회논문집 Vol.35 No.2

In concrete structural design provisons, there is a minimum allowable strain of steel to ensure a ductility of RC members and a c/d is limited for the same purpose in EC2. In general, a ductility capacity of RC members is evaluated by a displacement ductility which is a ratio of ultimate displacement to yield displacement, and it is necessary to calculate accurately a yield displacement and an ultimate displacement to evaluate a displacement ductility. But a displacement in members is affected by various member characteristics, so it is hard to calculate a displacement exactly. In this study, a displacement ductility is calculated by calculating a yield displacement and an ultimate displacement through a moment-curvature relationship. The main variables examined are concrete strength, yield strength, steel ratio, spacing of confinement, axial force ratio and concrete ultimate strain. As results, as a concrete strength is increased, a ductility displacement is increased. But as yield strength, steel ratio, spacing of confinement and axial force ratio are increased, a displacement ductility is decreased. And a displacement ductility is necessary to calculate a response modification factor (R) of columns for seismic design, so it is appeared that it is important to calculate a displacement ductility more accurately.

전자정부의 법적 기본틀

최승원(Seung Won Choi) 행정법이론실무학회 2007 행정법연구 Vol.- No.18

The more the importance of the Electronic Space in human beings increases, the closer the core of the society comes to it. So the relation ship of a nation and a person changes and the role of government must to turn to. Accordingly, I intend to write the basement of the e-Government Act as the legal order in the Electronic space. The e-Government Act has the peculiarity as a combination law of T-Code and L-Code. It has to be the balance ; on the one hand, as the actualized law of constitutional law, and on the other hand as the technology law. The e-Government Act has the basic principles of the constitutional law ; the e-democracy, the e-legalism, the e-welfare. But they are alike the substance of protecting human rights in comparison with the those of former times. The e-democracy reinforces the participation-democracy, so the more citizen have a say in legislation and take part in the conduct of state affairs. And there are the global rules standardization, the regulation by the Governance, and the combination of T -Code and L-Code etc. as the distinctive things of the e-legalism. And the e-welfare demands to close a gap in digital divide, but also expends the free use of com positive contents ; various typical, interactive, contents by the multimedia units. As the technical law, The e-Government Act has to playa important role in developing the competitive power of the knowledge-industry. Although Korea was an underdeveloped country in the Industrial Revolution, in the Electronic Space must to be one of forward countries, IT G8 in information technology days. It needs very much to make the mutual- complementary network of GㆍBㆍC.

유효탄성계수를 반영한 철근콘크리트 휨부재의 균열제어를 위한 철근 간격

최승원(Seung-Won Choi) 한국산학기술학회 2018 한국산학기술학회논문지 Vol.19 No.5

철근 콘크리트 부재에서 균열은 구조적 요인 뿐만 아니라 재료적 인자에 의해서도 발생한다. 이러한 균열의 크기와 발생 위치를 파악하는 것은 매우 어렵다. 도로교설계기준(한계상태설계법)과 콘크리트구조기준(2012)에서는 균열을 제어하기 위해 직접균열제어 방법과 간접균열제어 방법을 제시하였다. 콘크리트구조기준 본문에서는 사용하중 하에서 철근 간격을 사용하여 간접적으로 균열을 제어한다. 이에 반해, 콘크리트구조기준 부록에서는 지속하중 하에서 균열폭을 통해 직접적으로 균열을 제어한다. 즉, 균열 제어를 위해 고려하는 하중 상태가 상이하다. 그러나 도로교설계기준에서는 사용하중조합에서 균열을 제어하고, 유효탄성계수를 사용하고 있다. 따라서 이 연구에서는 고정 하중과 활하중의 비율을 반영할 수 있는 유효탄성계수를 적용한 설계 균열폭으로부터 최대철근간격을 산정하였다. 그리고 변수 해석을 수행하여 합리적인 균열 검증 방법에 대하여 모색하였다. 해석 결과 콘크리트구조기준으로부터 유도된 철근 간격은 도로교설계기준으로부터 유도된 값보다 작아 보수적인 설계를 유도하였다. 또한, 이 연구에서 제시한 최대철근간격은 직접균열제어와 간접균열제어 사이의 차이를 제거하여 해석의 일관성을 확보할 수 있는 것으로 판단된다. Cracks in RC members occurred as a result of material and structural factors. The crack width and a crack location are very difficult to examine. A direct crack control method and indirect crack control method to control a crack are presented in the KHBDC (LSD) and KSCDC (2012). In the KSCDC text, cracks are controlled by steel spacing indirectly under a service load. On the other hand, in the KSCDC appendix, cracks are controlled by a crack width directly under a sustained load. In particular, the loading state considered is different. On the other hand, cracks are controlled under a combination of service load and an effective elastic modulus is used in KHBDC. Therefore, in this study, an effective elastic modulus that can reflect the ratio of the sustained load and live load was applied, and a maximum steel spacing was calculated through a design crack width. A variable interpretation was carried out, and a rational crack control method was assessed. As a result, a steel spacing through the design crack width in the KSCDC was smaller than that from the design crack width in the KHBDC, which leads to a conservative design. In addition, the maximum steel spacing suggested in this study has a consistency eliminating the difference between direct crack control and indirect crack control.

유효탄성계수를 반영한 간접처짐제어 연구

최승원(Choi, Seung Won) 한국콘크리트학회 2019 한국콘크리트학회 학술대회 논문집 Vol.31 No.1

행정법과 공익

최승원(Choi Seung Won) 행정법이론실무학회 2006 행정법연구 Vol.- No.15

콘크리트 압축 모델에 따른 휨부재의 설계 강도에 대한 비교 연구

최승원(Seung-Won Choi) 한국산학기술학회 2021 한국산학기술학회논문지 Vol.22 No.9

철근콘크리트 구조물의 휨-압축 해석을 위해서는 콘크리트와 철근의 합리적 재료모델에 대한 제시가 필수적이다. 최근 개정된 콘크리트구조 학회기준(2017)에서는 콘크리트 압축력 산정을 위해 두 가지 압축응력 모델이 제시되었다. 첫 번째 모델은 등가직사각형 압축응력블록이고, 두 번째 모델은 포물선-사각형 응력-변형률 곡선이다. 포물선-사각형 응력-변형률 곡선은 도로교설계기준에서 제시된 모델과 동일한 형태를 가지고 있으며, 극한시 강도 뿐만 아니라 사용성 검토 등에도 이용될 수 있다는 장점이 있다. 또한, 등가직사각형 압축응력블록은 기존의 콘크리트구조기준(2012)에서 제시한 재료모델과 동일한 형태를 가지고 있으며, 이는 극한 강도를 쉽게 산정할 수 있다는 장점이 있다. 그러나 기존 모델과는 압축 응력 분포의 폭과 중립축 깊이를 산정하는 과정에 차이가 있다. 이 연구에서는 콘크리트구조기준(2012)과 콘크리트구조 학회기준(2017)의 콘크리트 압축 모델에 대하여 살펴보고, 이 압축 모델에 대하여 철근콘크리트 휨-압축 부재의 거동을 고찰하였다. 이로부터 휨-압축 해석을 위한 합리적인 콘크리트 압축모델에 대하여 분석하였다. 해석 결과 콘크리트구조 학회기준(2017)의 등가직사각형 압축응력블록은 특히, 고강도 콘크리트에 대하여 보수적인 설계 강도를 나타내었다. For the flexure-compression analysis of RC structures, it is essential to present a rational material model of concrete and steel. In the recently revised KCI(2017), two compressive stress models were proposed to calculate the compressive force of concrete: an equivalent rectangular stress block and a parabola-rectangular curve (p-r curve). A p-r curve is the same as the Korea Highway Bridge Code, and can be used for ultimate strength and serviceability analysis. An equivalent rectangular stress block has the same shape as the material model presented in the existing KCI(2012) and can easily calculate the ultimate strength. On the other hand, there is a difference in the process of calculating the width of the stress block and the depth of the neutral axis from the existing model. In this study, the concrete compression models of KCI(2012) and KCI(2017) were examined, and the behavior of RC flexural-compression members was investigated for this compression model. From this, a rational concrete compression model was analyzed for axial-flexural analysis. The equivalent rectangular stress block in KCI(2017) led to a conservative design strength, especially for high-strength concrete.

행정조직법의 기초

최승원(Seung Won Choi) 행정법이론실무학회 2010 행정법연구 Vol.- No.27

國家賠償責任의 性質 小考

최승원(Choi Seung-Won) 행정법이론실무학회 2008 행정법연구 Vol.- No.20