• 소성∙가공
• /
• 제16권1호
• /
• pp.67-74
• /
• 2007

This study is aimed to find out the optimal forming conditions by comparing and analyzing material flow, deformation pattern, and a forming load through rigid-plastic FEM for a flange using pipe. Flanges are widely used for various purposes as connectors of industrial steel pipes which are manufactured by drawing process. The forming feature of flange was reviewed through both heading process and radial extrusion process in a cold working condition. As a result of simulation, the shape of flange can not be made by heading process, but made by radial extrusion process. The effects of design factors, such as gap-height, die-comer radius, and frictional factors on maximum forming load and deformation pattern are investigated for radial extrusion process.

• 상하수도학회지
• /
• 제26권1호
• /
• pp.123-129
• /
• 2012

A septic tank is a purification treatment system where night soil and other waste matter is converted into harmless material by the activities of bacteria. Effluent from the septic tank flows into the sewer pipe, and then this effluent affects the quality of water environment and makes foul smell. In this study, through the proper maintenance of septic tank it was tried to minimize the impact of sewer pipe on water quality and fouling smell. BOD removal rate from the septic tank's effluent which exceeded legal cleaning period was investigated for the proper maintenance. BOD Removal rate of the twelve septic tank's effluent is -62.5% to 43.9%. According to the result of BOD removal rate, septic tank cleaning should be done at least once a year. And the pathogenic coliform bacillus in the twelve septic tank's effluent is average 768,000 (MPN/$100m{\ell}$). The chlorine disinfection is needed to remove the pathogenic coliform bacillus in septic tank effluent.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2012년도 춘계학술대회 논문집
• /
• pp.1059-1060
• /
• 2012

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2012년도 춘계학술대회 논문집
• /
• pp.1057-1058
• /
• 2012

• 한국측량학회지
• /
• 제11권2호
• /
• pp.43-51
• /
• 1993

도시 시설물에 관한 도면들은 시민의 생활과 도시 발전에 있어 매우 중요한 기반시설자원이다. 현재 이들에 대한 관리에 있어 존재하는 비효율성 방지를 위해 전산화의 필요성이 대두되고 있다. 본 연구에서는 PC용 GIS 소프트웨어를 이용하여 도시시설물중 하수도 시설의 관리 방법에 관하여 연구하였다. 경기도 안산시 일부지역을 표본으로 하여 하수도관리를 전산화하는 시스템구축을 위하여 도형 자료의 입력에는 1:38,000 안산시 행 정구역도와 1:3,000 도시 계획 총괄도, 그리고 1:500 시설물 도면을 이용하였고, 속성자료로서는 토지의 지번, 하수도의 설치 년도, 관의 재질, 관경, 길이 등을 입력하였다. 데이타베이스의 구축은 관계형(Relational) 자료모형을 이용하였으며, 자료의 검색, 분석, 처리를 위하여 위상관계를 설정하였다. 또한 본 연구에서는 노후관의 교체, 보수를 위한 공사와 관련된 물량, 시간, 비용 등을 계산할 수 있는 프로그램을 작성하였다.

• 한국산업융합학회 논문집
• /
• 제23권5호
• /
• pp.757-763
• /
• 2020

City gas buried pipes are managed by corrosion protection to prevent corrosion. In the case of the press-in section, the double pipe and the main pipe may cause corrosion under the influence of stray current, which can shorten the life of the pipes. In addition, if the insulator is filled in the press-in section, the press-in section itself is a single structure, and can be directly affected by external impact, and when the surrounding ground subsidence occurs, the stress may be concentrated, resulting in serious consequences. In this study, a serration-type shock absorber in the form of a sliding support was proposed as a new buried double piping construction method using EPS. The serration-type shock absorber can contribute to the improvement of the integrity of the buried double piping, as it can utilize the gas piping's own ductility and stress distribution characteristics with proper anti-corrosion management and shock-absorbing material properties by preventing contact inside the buried double pipe. However, for application to ground piping, there remains a task to supplement the vulnerability against fire due to the characteristics of EPS materials.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 춘계학술대회
• /
• pp.400-405
• /
• 2004

In this study, the optimal welding condition of the input power was selected experimentally through the ERW simulator, which is equal to welding status of ERW part in pipe. This condition is the input power 250kW in the heat treatment of the $900^{\circ}C$ normalizing derived from the nondestructive technique and impact energy. In order to evaluate the variation of the fatigue life in the pipe, fatigue surface crack growth test of base and optimal welded metal were performed statistically. As stress intensity factor range (${\Delta}K_s$) increases, the fatigue crack propagation rate (da/aN) of the base metal is faster than that of the welded joint. The variation of the fatigue life in the ERW pipe was estimated statistically using Monte-Carlo simulation with the standard deviation of material constants (C and m) of the paris law in the specimen.

• 한국압력기기공학회 논문집
• /
• 제16권1호
• /
• pp.42-48
• /
• 2020

The effect of improving the tensile and J-R fracture toughness properties of SA508 Gr.1a on the LBB margin for the main steam pipe is investigated. The material properties and microstructure images of the existing main steam piping material SA106 Gr.C used in domestic nuclear power plants and the newly selected material SA508 Gr.1a were compared. For each material, LBB margins were calculated and compared through finite element analysis and crack instability evaluation. The LBB margin of the improved SA508 Gr.1a is found to be greatly improved compared to that of the existing SA106 Gr.C and SA508 Gr.1a. This is because of the increased material's strength and J-R fracture toughness compared to the previous materials. In order to analyze the effect of physical property change on the LBB margin, the sensitivity of each LBB margin according to the variation of tensile strength and J-R fracture toughness was analyzed. The effect of the change in tensile strength was found to be greater than that of the change in fracture toughness. Therefore, an increase in strength significantly influenced the improvement of the LBB margin of the improved SA508 Gr.1a.

• 대한환경공학회지
• /
• 제30권3호
• /
• pp.331-338
• /
• 2008

본 연구에서는 국내에서의 생산되는 강관의 도복장 재료 및 방법별로 관체 시편을 이용하여 도복장강관의 성능을 시험하였다. 도복장강관의 원관의 물성 및 화학조성의 분석결과 모두 기준에 적합하였다. 강관의 도복장 재료의 물성시험 결과, 블론아스팔트와 콜타르에나멜은 비용이 저렴하고 기계적 성질은 매우 우수하나, 유기용매에 녹는 단점을 지니고 있고, 도복장강관이 도복장재료로서 성능이 떨어지는 것으로 나타났다. 또한 두껍게 도복할 경우, 강관 자체의 하중이 필요 이상으로 높아지는 문제가 발생할 수 있다. 당김강도 시험과 음극박리 시험결과, PE-3층 도복장방식이 우수하였으며, PE의 도복장방법에 따라서는 압출식(T-Die) 3층 폴리에틸렌(PE 3-Layer)이 분말용착식 폴리에틸렌(PE Fluidized)보다 당김강도가 강하며 음극박리 면적도 작았다. 압출식(T-Die) 3층 폴리에틸렌(PE 3-Layer)은 기계적 특성, 열적 특성 모두 우수하였고, 내화학성도 뛰어났다. 액상에폭시는 수지 선정과 경화 조건에 따라서 도장재의 특성을 변화시킬 수 있다. 본 시험에서 사용된 폴리우레탄은 강관과의 접착력도 에폭시에 비하여 낮았으며, 수분 흡수율은 에폭시 보다 높은 결과를 나타내었다. 폴리우레탄을 도복장재료로 사용하기 위해서는 우레탄의 기본물성과 최적의 도장조건을 도출하는 연구가 진행되어야 할 것으로 판단된다. 본 연구에서 실험한 시편 중에서는 현재 압출식으로 제조한 PE-3층 도복장방법이 가장 우수한 것으로 평가되었지만, 앞으로 기타 다른 도복장재료와의 추가 검증시험이 필요할 것으로 판단된다.

• 대한기계학회논문집
• /
• 제18권5호
• /
• pp.1106-1116
• /
• 1994

Leak Before Break(LBB) design concept is applied to piping systems of newly-built Yonggwang 3, 4 nuclear generating stations as a design alternative to the provision of pipe whip restraints, in recognition of the questionable benefits of providing such restraints. The objective of this paper is to evaluate the material properties (tensile and fracture toughness) of SA312 TP316 stainless steel and their associated welds manufactured for shutdown cooling system of Yonggwang 3, 4 nuclear generating stations. Effect of various parameters such as specimen orientation, test temperature, welding on material properties were examined.