In this study, the models with types A, B and C of the commercial electric kickboard suspensions were modeled and the structural analyses were carried out. Types A and C have the deformations less than type B. The coil spring can reduce the deformation by installing the suspension. In types A and C, the forces applied to the bolt became same, but more deformation occurred in type C. This is the difference due to whether or not there is a fixed part. Type A was fixed and type C not. This fixation indicates that the bolt has been fully tightened to the end. Therefore, the use of products thatarefully contacted to the end by tightening with bolts can reduce the deformation greatly. Based on the data obtained from this study, it is assumed that the more efficient and stable product will be designed if the suspension absorber of the suspension is designed. Without the test on the durability of electric kickboard suspension, the durability can be seen as the deformation and stress are investigated through the structural analysis.

The cast iron pipe protection of submarine cables has a bump in the connection, so the guide device for checking the position and location of the submarine cable must pass through the curved surface. Since the connection is present at a regular intervals, impact loads are periodically applied, affecting the durability of the guide device. In this study, the design was changed to improve the durability of guide device links. And for the analysis of the durability for link of guide device, the flexible dynamic analysis of the guide device was performed using MSC.Adams, and the dynamic stress acting on the link was calculated using MSR(Modal Stress Recovery) method. As a result, the dynamic stress is reduced by 17.9%~31.1%. In addition, durability was calculated for the initial model and the improved model. As a result, the durability of the new model was improved more than 200 % better than to the initial model.

In this study, quality keywords of frequent mention of failures were extracted by analyzing the field operational data of main battle tanks recorded for about 5 years. As a result of the data analysis, the leaf spring assembly of the crew hatches corrosion and failure was frequently occurred. FEA(Finite Element Analysis) and tests were performed to analyze the cause of the failure, and it was confirmed that durability of the leaf spring was insufficient. Therefore a design modification study was conducted to improve durability of the leaf spring, and FEA and durability tests demonstrated the improvement. As a result, the durability of leaf spring was improved at least 3.3 times compared to before improvement. This study will contribute to suggesting the use of data analysis in the defense area and improving the operability of the main battle tanks.

Pipe for water supply is one of the important parts that supply water to home, factory and so on. Water leakage in pipe for water supply due to deterioration, ground sinking and earthquake leads to enormous economical loss. Therefore, pipe for water supply should be designed to satisfy the requirement of, for instance, structural stability and fatigue durability. The purpose of this study was to investigate the fatigue durability of flexible joint for relaxing the impact due to earthquake and ground sinking. For this purpose, flexible joint was simulated using dynamic characteristics and fatigue life. As the results, the problem of fatigue durability may occur when flexible joint and pipe for water supply are treated as rigid body in simulation. Thus it means that the role of packing in flexible joint is very important and packing should be designed as optimal conditions that are considered fatigue durability as well as waterproof.

관광지 및 공공공간에서의 사인 시스템은 대상지에서의 즉각적이고 명확한 정보 안내는 물론 현장에서의 다양한 이용자 계층을 고려한다는 측면에서 여전히 중요한 과제로 남아 있다. 본 연구는 대표적 한국전통문화 관광지의 하나인 한국민속촌을 대상으로 정체성, 통일성, 가독성, 내구성, 위치의 적합성 등 5가지 조성원칙에 입각하여 문제점을 분석하였다. 이를 위해 사인시스템에 대한 문헌분석, 한국민속촌 사인시스템의 현황조사와 더불어 실제 이용자 150명을 대상으로 현장 설문조사를 실시하였으며, 이를 바탕으로 각각의 조성원칙이 전반적인 사인 이용 만족도와 어떤 상관성을 갖는지에 대해 분석하였다. 정체성, 통일성, 가독성, 내구성, 위치의 적합성 등 사인시스템의 5가지 주요 원칙들과 사인의 이용만족도와의 상관관계를 파악하기 위해 Pearson 상관계수 분석을 실시하였으며 그 결과, 한국민속촌의 경우 통일성과 가독성이 사인의 이용만족도와 통계적으로 유의한 상관관계가 있었으며 내구성과 위치의 적합성은 사인의 이용만족도와 낮은 상관성을 보였다. 5개의 주요 요소들간에는 정체성과 통일성이 가장 높은 상관관계를 보였으며, 통일성과 가독성, 정체성과 위치의 적합성도 유의한 상관관계를 나타냈다.

In this paper, the boom of a 30m class refracted insulation with outrigger on aerial elevating work platform is modeled as 3D CAD program of CATIA. The static and dynamic analyses are performed by using ANSYS and ADAMS programs, respectively. The refracted insulation boom uses acetal and the composite boom for insulation. And the composite insulation boom is modeled by using ACP (Ansys Composite Prepost) of ANSYS program. In order to analyze the durability of refracted insulation boom, the static analysis is performed and each analyzed part is stored as =MNF-type flexible body model. The dynamic analysis is performed with ADAMS by using the flexible model. As the result, these analyzes clarify the structural stability and dynamic durability (hot spot) of the refracted insulation boom.

This paper uses finite element analysis to analyze the equivalent stress and fatigue duration distributed in the timing belt pulley of the rotating part. The pulley structure used for analysis was categorized into one body type and separate axis type and their characteristics were analyzed when materials S45C and SCM440-870C were applied. A static structural analysis and durability analysis show that when external forces are applied to the pulley, the separate axis structure is structurally safer and more favorable in terms of fatigue, compared to the one body. In addition, the separate axis structure using SCM440-870C material was found to have the best safety factor at 10.4 and infinite fatigue life. These findings are expected to be useful when manufacturing timing belt pulleys.

PURPOSES : The use of roller-compacted concrete pavement (RCCP) is an environmentally friendly method of construction that utilizes the aggregate interlock effect by means of a hydration reaction and roller compacting, demonstrating a superb structural performance with a relatively small unit water content and unit cement content. However, even if an excellent structural performance was secured through a previous study, the verification research on the environmental load and long-term durability was conducted under unsatisfactory conditions. In order to secure longterm durability, the construction of an appropriate internal air-void structure is required. In this study, a method of improving the long-term durability of RCCP will be suggested by analyzing the internal air-void structure and relevant durability of roller-compacted concrete. METHODS: The method of improving the long-term durability involves measurements of the air content, air voids, and air-spacing factor in RCCP that experiences a change in terms of the kind of air-entraining agent and chemical admixture proportions. This test should be conducted on the basis of test criteria such as ASTM C 457, 672, and KS F 2456. RESULTS : Freezing, thawing, and scaling resistance tests of roller compacted concrete without a chemical admixture showed that it was weak. However, as a result of conducting air entraining (AE) with an AE agent, a large amount of air was distributed with a range of 2~3%, and an air void spacing factor ranging from 200 to 300 ㎛ (close to 250 ㎛) coming from PCA was secured. Accordingly, the freezing and thawing resistance was improved, with a relative dynamic elastic modulus of more than 80%, and the scaling resistance was improved under the appropriate AE agent content rate. CONCLUSIONS: The long-term durability of RCCP has a direct relationship with the air-void spacing factor, and it can be secured only by ensuring the air void spacing factor through air entraining with the inclusion of an AE agent.

본 연구에서는 텅스텐합금강의 상부구조와 폴리에틸렌소재로 구성된 하부구조의 인공관절이 하중을 받았을때의 인공관절의 하중분포와 인공관절의 설치를 위한 지지구멍에 가해지는 응력분포에 대하여 유한요소해석을 통하여 결과값을 도출하였으며, 실물을 이용한 다음 실험을 위한 기초자료를 얻을 수 있었다. 이를 통하여 나온 해석결과의 하중분포는 텅스텐합금의 상부구조가 모서리 끝부분부터 하중이 집중되어 크랙이 발생하며 이는 의학계에 보고된 인공관절파손에 의한 조직괴사사례와 그 거동이 일치 하였다.

본 논문에서는 와이어 하네스의 피로 내구 수명을 예측하기 위해 와이어, 번들, 실차단계의 유한요소 해석 방법론이 연구되었고 이를 위한 피로 내구 시험 기기가 개발되었다. 와이어 하네스 시스템을 구성하는 5가지 종류의 와이어에 대한 응력-수명 그래프를 얻기 위해 개발된 피로 시험기를 이용하여 반복 굽힘 움직임을 인가하였다. 와이어를 구성하는 도선과 피복의 재료 모델링을 위해 혼합의 법칙이 적용된 등가모델을 이용하였다. 번들 해석과 시험을 통하여 와이어 간의 접촉조건과 번들의 테이핑조건이 정립되었다. 와이어 및 번들 단계의 결과들은 실차 단계의 해석에 적용되었다. 실차단계의 해석을 위해 번들과 그로맷으로 구성된 와이어 하네스 시스템을 수치적으로 모델링 하였으며, 차량 문의 개폐조건이 와이어 간의 접촉조건과 함께 적용되었다. 유한요소 해석을 이용한 실차 모델의 피로 내구 해석을 통해 70만회 이상의 피로 수명이 도출 되었으며, 실차 조건의 시험 결과와비교하여 타당성을 검증하였다.

In this study, the stability of baby carriage is investigated through fatigue and vibration analyses according to the seat configuration.

This study analyzes lifes and damages at two automotive grills in use through the structural analyses with fatigue. As maximum equivalent stress in case of aftermarket grill frame becomes smaller more 15 times than horizontal grill frame, aftermarket grill is shown to be more stable. The lowest damage becomes 2968 in case of ‘SAE bracket history’ with the severest change of load at aftermarket grill. As it becomes smaller more 5 times than horizontal grill frame, aftermarket grill has more durability. Among the cases of nonuniform fatigue loads, ‘Sample history’ with the slowest change of load becomes most unstable in case of horizontal grill frame but ‘SAE bracket history’ with the severest change of load becomes most stable in case of aftermarket grill frame. The structural result of this study can be effectively utilized with the design of automotive grill frame by investigating prevention and durability against its damage.

본 연구에서는 페로니켈슬래그 기반 무기계 바인더와 혼합된 콘크리트를 사용한 강성관에 대하여 관로 내부 조사를 실시하였고, 경사계 및 스트레인게이지를 부착한 후 장기 계측을 위한 자동화계측시스템을 설치하여 장기 데이터를 분석하였다. 개발한 강성관과 일반관은 내부 상태를 촬영한 결과 모두 이상상태가 발견되지 않았고, 장기 변형률도 매우 유사한 결과가 측정되었다. 이를 통해 개발된 강성관은 상용품으로 활용하는데 문제가 없을 것으로 판단된다.

This study is to prepare prediction method of the durability establishment for the effective maintenance of reinforced concrete substation structures. For this study, we investigated research trends about the foreign practices relating durability design.

염해에 따라 발생하는 보수시기와 보수로 유지되는 내구수명은 보수비용 평가에 매우 중요한 요소이다. 일반적으로 사용하는 결정 론적 보수비용 평가는 사용기간의 연장에 따라 계단식으로 증가하게 되며, 보수로 인해 변동되는 내구수명의 변화를 고려하지 못한다. 본 연구 에서는 확률론적인 보수시기 및 비용을 평가하기 위해, 염해에 노출된 콘크리트 교각을 선정하였다. 두 가지 배합과 염화물에 노출된 외부 환 경조건을 고려하여 염화물 거동을 평가하였으며, 도출된 내구수명과 수명에 대한 확률변수를 변화시키면서 보수시기 및 비용 변화를 분석하 였다. 변동계수의 변화에 따른 보수회수는 큰 차이가 발생하지 않았으나, 초기의 내구수명 연장이 구조물의 보수시기 및 비용에 큰 영향을 미 치고 있었다. 또한 확률론적 보수비용 산정 모델은 결정론적 모델과 다르게 연속적인 보수비용이 평가되므로 목표내구수명에 따라 보수회수 를 감소시킬 수 있는 효과적인 기법임을 규명되었다.

Recently durability design based on deterministic or probabilistic method has been attempted since service life evaluation in RC(Reinforced Concrete) structure exposed to chloride attack is important. The deterministic durability design contains a reasonable method with time effect on surface chloride content and diffusion coefficient, however the probabilistic design procedure has no consideration of time effect on both. In the paper, a technique on PDF(Probability of Durability Failure) evaluation is proposed considering time effect on diffusion and surface chloride content through equivalent surface chloride content which has same induced chloride content within a given period and cover depth. With varying period to built-up from 10 to 30 years and maximum surface chloride content from 5.0 kg/m3 to 10.0 kg/m3, the changing PDF and the related service life are derived. The proposed method can be reasonably applied to actual durability design with preventing conservative design parameters and considering the same analysis conditions of the deterministic method.

This paper presents a comprehensive probabilistic model of reinforcement corrosion initiation under the combned action of carbonation and chloride ingress. The numerical results show that the probability of reinforcement corrosion initiation under the combined action is much higher than the case of only considering the action of single factor.