원심주조법에 의한 주철-Babbitt Metal 복합관 제조에 관한 연구

이충도,강춘식 ( Chung Do Lee,Choon Sik Kang ) 한국주조공학회 1993 한국주조공학회지 Vol.13 No.1

N/A Conventional manufacturing process for cast iron-babbitt metal composite is complicate and bimetallic bonding by centrifugal casting is also difficult because their melting point is largely different and nonmetallic inclusion exists on outer shell. This study is aiming to simplify multistage process by adding Cu-powder as insert metals during cast iron solidification. The variables on fabrication of composite pipe are mold rotating speed and inner surface temperature of outer metal. The optimum temperature range for fusion bonding between cast iron and Cu-layer was 1100℃-1140℃ in case of mold rotating speed was 700rpm. When the inner surface of Cu-layer was at 900℃, the value of interfacial hardness between Cu-layer and babbitt metal were higher than Cu-matrix by forming diffusion layer, interfacial products between Cu-layer and babbitt metal are proved to be Cu_6Sn_5(η)by XRD.

Dependence of Fatigue Life of Low-Pressure Die-Cast A356 Aluminum Alloy on Microporosity Variation

이충도,Suk Jong Yoo 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.4

The aim of the present study was to investigate the dependence of the high cycle fatigue property on themicroporosity variation of a low-pressure die-cast A356 alloy. Also, it aimed to describe quantitatively therelationship between the fatigue property and monotonic tensile strength using modified Basquin’s equationwhich takes into account the microporosity variation. The fatigue life of the A356 alloy can be described by anexponential dependence on the variation of the fractographic porosity, in terms of the modified Basquin’s equationwhich is composed of the defect susceptibility of fatigue life to microporosity variation and the maximum tensilestrength achievable in the defect-free condition. Using a modified form of Basquin’s equation, the maximumvalues of the fatigue strength coefficient and exponent in the defect-free condition are 341.5 MPa and-0.076, respectively, even though the nominal values of fatigue strength coefficient and exponent withoutconsideration of microporosity variation are 237.6MPa and -0.048, respectively. Also, the difference betweenthe maximum tensile strength and the fatigue strength coefficient on modified Basquin’s equation is about120MPa, and it arises from variation in the deformation behavior due to the difference of loading conditionbetween the monotonic and cyclic test modes such as the strain rate, Bauschinger effect, cyclic work hardeningand damage accumulation on loading condition.

Defect Susceptibility of Sensile Strength to Microporosity Variation in As-Cast Magnesium Alloys with Different Grain Sizes

이충도 대한금속·재료학회 2010 METALS AND MATERIALS International Vol.16 No.4

The variability in the tensile strength of as-cast AM60 and AZ91 alloys was investigated in terms of the defect susceptibility to the variation in grain size and microporosity. The microporosity was measured from the quantitative fractography analysis through scanning electron microscopy (SEM) observation on fractured surface after tensile test. The ultimate tensile strength (UTS) of both alloys can be characterized as a power law relationship to microporosity variation in terms of the defect susceptibility and maximum strength achievable in the defect-free condition. The defect susceptibility of tensile strength to microporosity variation is decreased remarkably with grain refinement. The defect susceptibility of AZ91 alloy to microporosity variation exhibits more sensitive dependence on the variation in grain size than AM60 alloy. Also, the dependence of UTS on the variation in grain size is described as a power law relationship for various levels of microporosity. The variation on effective void area fraction by the damage evolution of Mg17Al12 phase may introduce a practically significant decrease of load bearing capacity, less than by microporosity variation. The Hall-Petch relation of both alloys in the defect-free condition could be suggested as maximum values of friction stress and locking parameter.

Effect of Strain Rate on Elastic-Plastic Deformation in High Cycle Fatigue Properties

이충도 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.6

The aim of the present study was to investigate the contribution of the strain rate to the transition of elastic-plastic deformation behavior and the difference between the fatigue strength coefficient and monotonictensile strength in terms of the modified Basquin’s relation, which considers microporosity variation. Thetransition phenomena of elastic-plastic deformation were evaluated through comparison of the overall contour ofthe hysteresis loops measured in high cycle fatigue tests of a low-pressure die-cast A356 alloy. The increase ofthe alternating stress amplitude at a given excitation frequency causes a variation in the strain rate per unit timeinterval that depends fundamentally on the excitation frequency. In addition, the transition of elastic-plastic deformationbehavior is induced by variation of strain rate in high cycle fatigue test, i.e., typically, a variation ofthe elastic modulus and extension of the elastic deformation region, compared with monotonic deformationunder a very slow strain rate. The dependence of the elastic modulus on the strain rate due to the variation of thestress amplitude can be described in an exponential form of strain rate. The modified Basquin’s equation whichincludes the contribution of the strain rate and microporosity to the fatigue strength coefficient and fatigue lifewas re-established, including the dependence of the elastic modulus and transition of elastic-plastic deformationon the variation of the strain rate.

A356합금의 품질지수에 미치는 미소기공율의 영향

이충도 한국주조공학회 2018 한국주조공학회지 Vol.38 No.5

The dependence of the tensile properties on variations in the porosity of A356 aluminium alloys was investigated in terms of the quality index of the tensile properties based upon the ultimate tensile strength and elongation as well as the variation of the strength coefficient and strain-hardening exponent with regard to a T6 treatment. The test specimens were prepared by low-pressure die-casting and a subsequent T6 treatment, and the experimental results of a tensile test carried out at room temperature were compared to the theoretical description using a modified constitutive model. The nominal value of the quality index of A356 alloys increases gradually with a lapse of the ageing time upon a T6 treatment, despite the fact that this value is temporarily decreased during the initial stage of ageing from a solutionised condition. Additionally, the quality index depends practically upon the porosity variation with a power law relationship without regard to whether in solutionised or artificial aged conditions. The theoretical description indicates that the strength coefficient directly determines the nominal level of the quality index. Moreover, the overall dependence of the quality index on the porosity variation is remarkably weakened with an increase in the tensile strain, whereas the quality index depends sensitively upon the porosity variation with a low value of the strain-hardening exponent.

7. 極地에서의 海洋建設

李忠東(이충동) 대한토목학회 1986 대한토목학회지 Vol.34 No.6

주거권 보호를 위한 강제퇴거금지법 도입에 관한 연구

이충은 ( Choong Eun Lee ) 제주대학교 법과정책연구소 2013 국제법무 Vol.5 No.1

2009년 1월 20일의 용산참사는 우리 모두에게 씻을 수 없는 상처로 남았다. 그로부터 4년여가 지난 지금 구속되었던 철거민들의 석방을 제외하고는 아무것도 해결된 것이 없다. 주거는 인간의 기본적인 권리이다. 개발을 향한 탐욕은 사람의 생명과 삶을 빼앗아 기본적인 권리마저 박탈시키고 있다. 이제는 우리나라에서 추진되고 있는 재개발 사업과 관련하여 철거민의 주거권 보장과 함께 사업을 추진할 때 발생할 수 있는 물리력 행사를 원천적으로 차단하기 위한 입법적 대응방안의 마련이 필요한 시점이다. 이에 본 논문에서는 잘못된 도시개발 정책의 문제점을 되짚어보고 강제퇴거금지법(안)의 주요내용을 살펴보고 있다. On January 1, 2009, the horrible accident of Y eng-san left all the people with indelible scars. There has not been any solution for 4 years but release of evictees who had been prisoned since the disaster in 2009. The right of housing is the basic human right. Greed for development deprives the human`s lifes and natural right. It is the just time to make a plan to prevent forces and violences caused by redevelopment project in Korea and legalize to guarantee evictees` residential right. This paper is mainly on indicating the problems of civil development policy and explaining critical contents of the Protection From Eviction Act.

인권영향평가의 제도화 방안에 관한 연구

이충은 ( Lee Choong-eun ),노진석 ( Noh Jin-seok ) 제주대학교 법과정책연구원 2018 法과 政策 Vol.24 No.2

인권영향평가라는 것은 국가 및 지방자치단체에서 시행하는 정책 및 사업과정에서 인권에 미치는 부정적 영향을 방지하고, 긍정적인 영향을 극대화하기 위한 것으로, 각종 법령·제도, 정책 그리고 사업이 시행되기 전에 인권약자에게 미칠 수 있는 부정적인 영향을 제거하거나 최소화함으로써, 양극화를 방지하고, 나아가서는 사회적 정의를 실현할 수 있는 매우 유용한 제도다. 우리나라는 환경영향평가, 부패영향평가, 성별영향평가, 교통영향평가, 개인정보영향평가 등 많은 사회영향평가 제도를 시행하고 있지만, 인권의 측면에서 중앙정부가 영향평가를 하는 경우는 존재하지 않으며, 일부 지방자치단체에서 조례를 근거로 시행하고 있을 뿐이다. 인권침해는 언제 어디서든 일어날 수 있으며, 그 침해를 가장 많이 겪는 피해자는 지역의 구성원이다. 그러한 면에서 인권 침해의 피해를 최소화 할 수 있는 인권영향평가는 가장 효과적인 조치라 할 수 있다. 그럼에도 불구하고, 인권영향평가가 법률로서 제도화되지 못하여 여러 지방자치단체에서 많은 어려움을 겪고 있다. 따라서 사회적 약자 및 소수자뿐만 아니라 일반 국민 모두가 권리로서 인권을 당당히 추구하고, 국가 및 지방자치단체의 각종 법령·제도, 정책 그리고 사업의 무분별한 시행으로 모든 국민이 인권침해를 입지 않도록 제도적 장치가 마련되어야 할 것이다. 본 논문에서는 그 제도적 장치로서 인권영향평가의 제도화 방안을 제시하고 있다. 인권영향평가의 제도화는 인권 행정의 핵심제도가 될 것이고, 사회적 갈등을 최소화함으로써 행정의 효율성, 경제성뿐만 아니라 공공성을 확보하여 일상생활에서 국민의 인권증진에 이바지할 수 있을 것이다. As a system that could prevent negative effects and maximize positive effects on human rights in the process of projects and policies enforced by the state and local government, the human rights impact assessment is a very useful system that could prevent the polarization, and furthermore, practice the social justice by removing or minimizing the negative effects on human rights before the enforcement of all sorts of legislation, system, policy, and project. Even though Korea has many social impact assessments, such as environmental impact assessment, corruption impact assessment, gender impact assessment, traffic impact evaluation, and personal information impact assessment, there are no cases of impact assessment in the aspect of human rights. Such human rights impact assessment is only conducted in the level of local government based on ordinances. The violation of human rights could happen anytime and anywhere, and the most effective action to minimize damages from the violation of human rights is the human rights impact assessment. For this reason, the institutionalization of human rights impact assessment could be a core system of human rights administration, and also contribute to the enhancement of residents’ human rights in daily life by securing the efficiency, economic feasibility, and publicness of administration by minimizing social conflicts. Institutional devices should be provided so that not only the socially weak and minority, but also the general public can pursue human rights as rights, and all citizens are not infringed by various laws, regulations, policies and projects of the national and local governments something to do. Thus, this paper suggests the institutionalization measures of human rights impact assessment.

정수식물의 내염성 및 NH$_4$^+$-N 흡수제거능 평가

이충일,곽영세 한국생태학회 2000 Journal of Ecology and Environment Vol.23 No.1

부들, 갈대, 줄, 물고랭이 등의 정수식물을 이용하여 5개월 동안 용기재배로 산업폐수 정화용 정수식물을 선발하였다. 전기전도도가 3.0 dS/m이고, NH₄/sup +/-N 농도가 130 ppm인 산업폐수를 관수하였을때 증발산량(ETc)이 감소하지 않는 정수식물은 부들과 줄로서 내염성이 강하였고, 갈대는 폐수처리에 의하여 배양액재배시 보다 증발산량이 30% 감소하였으나 증발산량의 절대치가 가장 높아 수분요구량이 매우 높은 식물로 판명되었다. 부들과 줄의 건물생산량은 증발산량의 경우에서와 같이 배양액 관수구보다 오히려 산업폐수 관수구에서 높았고, 갈대는 폐수처리에 의하여 건물생산량이 14% 감소하였음에도 불구하고 4종식물중에 건물생산량이 가장 높았다. 물고랭이는 산업폐수를 관수하였을 때 건물생산량이 71.3% 감소하여 내염성과 고농도 암모니아성 질소에 대한 내성이 극히 불량한 것으로 나타났다. 줄과 갈대는 산업폐수 관수시에 총건물중과 조직내 질소 축적물이 부들이나 물고랭이 보다 훨씬 높아 단위면적당 질소 흡수제거량이 큰 정수식물로 판명되었다. Tolerances of aquatic plants (emergent plants) of cattail (Typha orientalis), water oats (Zizania latifolia), reed (Phragmites communis), and bulrush (Scirpus nipponicus) to salts and high NH₄/sup +/-N cone. of industrial wastewater were evaluated. Evapotranspiration of cattail and water oats plants was not affected when the wastewater containing 130 ppm NH₄/sup +/-N with electrical conductivity of 3.0 dS/m was supplied for 5 months. Shoot and root dry wt. of cattail and water oats were rather increased by irrigation of the wastewater while the biomass production of bulrush was greatly reduced. Storage nitrogen concentration in tissues of water oats and reed plants were higher than those in cattail and bulrush. Thus, water oats and reed plants were found to be the better aquatic plants to use in constructed wetlands for treating industrial wastewater of high salt and NH₄/sup +/-N.

NF-κB 신호전달과정의 음성적 조절 -배아줄기세포에서의 조절을 포함하여

이충일 ( Choong Il Lee ),심상형 ( Sang Hhyung Sim ),김영은 ( Young Eun Kim ),황유원 ( Yoo Weon Hwang ),하양화 ( Yang Hwa Ha ),한재민 ( Jae Min Han ),김경아 ( Kyeong A Kim ),황보은 ( Eun Hwang Bo ),이영희 ( Young Hee Lee ) 한국조직공학과 재생의학회 2010 조직공학과 재생의학 Vol.7 No.3

NF-κB is a transcriptional factor which is involved in many biological processes including immunity, inflammation, and cell survival. Many investigators studied on the mechanism involved in activation of NF-κB signalling pathway via ubiquitination and degradation of IkB. Recently, termination of NF-κB signaling after activation is regarded as another essential regulating step. In addition to the negative feedback by IkB protein, ubiquitination and degradation of nuclear p65/RelA, a crucial subunit of NF-κB, is considered another mechanism to terminate the NF-κB signaling. COMMD1, PDLIM2, GCN5 and NMRAL1 are recently reported as proteins related with p65/ RelA ubiquitination. Interestingly, ubiquitination and degradation of p65/RelA through viral protein was also found in the process of viral infection to escape from host defence mechanism. In contrast with somatic cells, expression of NF-κB is relatively low in undifferentiated embryonic stem (ES) cells, and activity of NF-κB is down-regulated by Nanog via direct interaction. Furthermore, enforced expression of NF-κB resulted in differentiation suggesting that down regulation of NF-κB contributes to the maintenance of ES cells. Therefore, better understanding on the negative regulation of NF-κB signaling in somatic cells as well as in ES cells might give more insights into therapeutics targeting NF-κB signaling.