• 대한기계학회논문집A
• /
• 제25권10호
• /
• pp.1651-1658
• /
• 2001

It is necessary to evaluate fatigue strength and reliability of the connecting rod which is core part in automotive engine to assure the high level of durability of automobile. For this purpose, the loading conditions in automotive engine is obtained by the dynamic analysis. Based on these results, the critical section was identified by the finite element analysis. The fatigue strength under constant amplitude was evaluated and the mean of the fatigue limit at R = -2.27 derived from the staircase method was 311.2MPa. And the failure probability( F$\sub$p/ ) derived from the strength-stress interference model is 0.0003% at the 99.99% confidence level and the mean factor of safety was 4.2.

• 한국정밀공학회지
• /
• 제27권7호
• /
• pp.101-108
• /
• 2010

Domestic three-way catalyst satisfies exhaust gas conversion efficiency or pressure drop etc. but doesn't satisfy thermal durability. Thermal stress analysis for three-way catalyst was performed based on experimental temperature distribution. Thermal safety of three-way catalyst was estimated by safety factor. Aspect ratio variable had the most significant effect on thermal stress. Thickness variable had the least significant effect on thermal stress. Optimal conditions for premature failure prevention of three-way catalyst were as follows : (1) aspect ratio of three-way catalyst : 0.6:1 (2) 2.84mm thick (3) silicon nitride. The safety of Taguchi-optimized three-way catalyst were 4.7 times higher than that of existent three-way catalyst.

• 한국농공학회:학술대회논문집
• /
• 한국농공학회 2005년도 학술발표논문집
• /
• pp.102-107
• /
• 2005

All concrete structure in agricultural improvement project must satisfied durability, serviceability, safety. It is important for structure that satisfied these natures to good quality at design and construction step, and must continuous maintenance. Most of the concrete structures is construct at winter season, is contacted with water, has various type and sporadic in wide area. The objective of this study is to make the Concrete-Quality-Control diagram for agricultural infrastructure project using GIS. And, analyze the diagram with external factor(terrain, stream, economic etc.) to know the factor of concrete quality control.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
• /
• pp.213-216
• /
• 2005

Salt attack and freezing & thawing test, one of the combined deterioration tests was performed to explore the mechanism of concrete structure deterioration under marine environment. Simple submerging test was proceeded to draw out its diffusion factor with salt water at the same time. Some of the mechanisms were driven with using three types of cements and four kinds of salt water concentrations. $\circ$ TBC was more durable than OPC or SRC for freezing and thawing action $\circ$ The higher chloride concentration of salt water was, the faster relative dynamic elastic modulus decreased and the higher the loss of weight was. $\circ$ The diffusion factor of TBC was smaller than those of TBC or SRC at simple submergence of concrete specimens into salt water.

• Computers and Concrete
• /
• 제3권2_3호
• /
• pp.145-161
• /
• 2006

This article involves architecting prototype-fuzzy expert system for designing the nominal cover thickness by means of fuzzy inference for quantitatively representing the environment affecting factor to reinforced concrete in chloride-induced corrosion environment. In this work, nominal cover thickness to reinforcement in concrete was determined by the sum of minimum cover thickness and tolerance to that defined from skill level, constructability and the significance of member. Several variables defining the quality of concrete and environment affecting factor (EAF) including relative humidity, temperature, cyclic wet and dry, and the distance from coast were treated as fuzzy variables. To qualify EAF the environment conditions of cycle degree of wet-dry, relative humidity, distance from coast and temperature were used as input variables. To determine the nominal cover thickness a qualified EAF, concrete grade, and watercement ratio were used. The membership functions of each fuzzy variable were generated from the engineering knowledge and intuition based on some references as well as some international codes of practice.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2005년도 춘계학술대회 논문집
• /
• pp.239-245
• /
• 2005

Through the fatigue test of plastic gears using polyacetal polymer, this research aims at providing basic data for not only specifying operation conditions of plastic gears, but also designing dimensions of plastic gears with giving fatigue life and the estimated equation of fatigue life of plastic gears. That is, from the fatigue life curves, the estimated equation of fatigue life of plastic gears is taken out. For the estimated equation of fatigue life of plastic gears, this research provides two test methods; one is preserving non-limited temperature of tooth flank, the other is preserving limited temperature of tooth flank. As results, how the temperature of tooth flank affects the fatigue life is shown. In addition, based on the endurance limit, the essential factors of the unit load and K-factor are determined, which are needed in the design of gear by bending strength and surface durability.

• 한국자동차공학회논문집
• /
• 제22권5호
• /
• pp.50-58
• /
• 2014

The PRT(Personal Rapid Transit) system is highly interested to meet a need for demand-responsive transport service and increasing demands of traffic in Korea recently. And it is being spotlighted as an eco-friendly transportation system. For these reasons, researches on the PRT system are actively undergoing in Korea. In this study, we evaluated the static structural and fatigue strengths based on ASCE-APM standards and ERRI B 12/RP 17 by means of FE simulation. We also evaluate the running stability by multi-body dynamic analyses and the rollover safety by a theoretical static stability factor according to the road modeling scenarios for the PRT system. From the results of this study, we confirmed the durability and running stability of the Korean PRT under development.

• 한국강구조학회 논문집
• /
• 제19권1호
• /
• pp.79-86
• /
• 2007

도장, 용사 및 도금 등의 강교용 방청법의 장기내구성 평가에는 대기노출실험법이 사용되고 있으나, 노화데이터를 얻기까지는 수년에서 수십 년이라는 장기간의 실험기간을 필요로 한다. 본 연구에서는 기존의 방청법을 포함하여 최근에 개발, 사용되고 있는 강교용 방청법의 장기내구성의 단기간 평가를 위한 기초단계로서 무도장 강재의 부식내구성 평가를 위한 부식환경 촉진실험법의 활용에 대해 검토하였다. 본 실험에는 일본공업규격(JIS)에 규정되어 있는 S6-cycle 부식환경 촉진실험조건을 이용하여, 30, 60, 90, 120, 150일간의 무도장 강재의 부식 중량감소량 및 두께감소량의 경시변화를 정량적으로 평가하였다. 그리고 기존의 대기노출실험과 본 실험으로부터 구한 중량감소량을 이용하여 촉진배율을 산출하고, 대기노출실험지의 지역환경구분, 해안선으로부터 거리, 아황산가스량 및 비래(飛來)염분량과의 관계를 검토하였다. 그 결과, 촉진배율을 비래염분량으로 정식화하였으며, S6-cycle 부식촉진실험결과의 대기노출환경에의 활용 가능성을 제시하였다.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2010년도 추계학술대회 초록집
• /
• pp.189.2-189.2
• /
• 2010

The purpose of this study is fatigue damage assessment for large sized casting parts (hub and mainframe) of the 3MW offshore wind turbine by computer simulation. Hub and mainframe durability assessment is necessary because wind turbine have to guarantee for 20 years. Fatigue life evaluation must be considered all of fatigue load conditions as the components are wind load transmission path. Palmgren-Miner linear damage accumulation hypothesis is applied for fatigue life estimation with stress-life approach. S-N curve for the spheroid graphite cast iron EN-GJS-400-18-LT is derived according to durability guidelines. Reduction factors were applied for survival probability, surface roughness, material quality and partial safety factor according to Germanischer Lloyd rules. To calculate fatigue damage, stress tensors, extracted from the unity load calculation from ANSYS is multiplied with time track of fatigue loads extracted from GH bladed. Damage accumulation is performed with all of fatigue load conditions at each finite element nodes. In this study maximum nodal damage value is under 1.0. casted parts are safe. This research was financially supported by the Ministry of Knowledge Economy(MKE), Korea Institute for Advancement of Technology(KIAT) and Honam Leading Industry Office through the Leading Industry Development for Economic Region.

• 한국자동차공학회논문집
• /
• 제24권2호
• /
• pp.225-231
• /
• 2016

A military vehicle is driven at different usage modes with the army application and servicing conditions. For practical durability validation, DT(Development Test) on a new military vehicle should be run up to the durability target kilometers on test courses in the specified proving ground. Driving velocities with test courses at the endurance mode of DT are established definitely. However, OT(Operational Test) and initial endurance test of production car can't be performed only in the DT courses due to the development period limit. Therefore, this paper focuses on the method to analyze the relative road damages between the endurance test in DT and other endurance test. Road load acquisition tests on KLTV(Korean Light Tactical Vehicle) were implemented at 15 driving modes in off-road and cross-country courses of two tests. Wheel accelerations were processed through band-pass filter, and then the main frequency and maximum power of the signals were computed by PSD analysis. Finally, using the proving ground optimization based on RDS(Relative Damage Spectrum) characterization, the damage factors between off-roads of test courses were determined.