The Joint Load Transfer (LTE) is important for both design and evaluation of concrete pavements. Numerous researches have been published to determine different factors that affect the load transfer efficiency through Finite Element Method (FEM) and field measurements. Most of these researches are using static analysis. Previous study pointed out the weakness of the assumption of this analysis and successfully differentiate the dynamic stress-based LTE with static stress-based LTE through FEM. Usually deflection based LTE(w) is being evaluated in the field through Heavy Weight Deflectometer (HWD). This test is a dynamic test which typically uses peak displacement and assumed to be static displacement when similar amount of static loading is applied. The calculation of LTE(w) in the field involves the ratio of the peak displacement of unloaded to loaded slab. Using this LTE(w) calculation, there were instances that high values were obtained from spalled joints and joints with wider opening. This study attempts to provide a better characterization of the condition of the joint. A time-based LTE(t) using the time delay were investigated and correlated with the current LTE(w) using a 24 hour measurement of deflection from asphalt and concrete pavement, with a 3-hour interval done in Gimpo International Airport. Wider values of LTE(t) were obtained while the deflection-based LTE(w) shows almost similar values. The time-based LTE(t) shows better relationship with the physical condition of the joint than LTE(w). It shows that LTE(t) can characterized the condition of the joint. This result will be used for further study to improve the measurement of load transfer efficiency of concrete pavement joints

The Kingery-Bulmash equation is the most common equation to calculate blast load. However, the Kingery-Bulmash equation is complicated. In this paper, a modified equation for surface blast load is proposed. The equation is based on Kingery-Bulmash equation. The proposed equation requires a brief calculation process, and the number of coefficients is reduced under 5. As a result, each parameter obtained by using the modified equation has less than 1% of error range comparing with the result by using Kingery-Bulmash equation. The modified equation may replace the original equation with brief process to calculate.

Recently, the trend is emerging a variety of irregular tall buildings. It is important to design the building for lateral load according to this trend. Fluid Structure Interaction(FSI) simulation can be performed to understand the vibrations of the structure against dynamic wind loads. In order to make the physical characteristics of the actual structure and the analytical model the same, we studied core inserting equivalent stiffness modeling method. As a result of this analysis, the stiffness of the structure can be set similar to that of the two axes of the structure, and turbulence can be reproduced through the acceleration tendency.

In this study, a winch and load motion control system design method is introduced. Especially, the winch and load (moving cart) are connected with long wire rope which is extended to few kilometers long. Therefore, the rope length changes such that many dynamic parameter values are changed as well by winding and releasing the rope from the winch system. In this paper, the authors designed the control system by considering the real time parameter variation to occupy and keep good control performance continuously. The effectiveness of introduced method was evaluated by simulation results.

PURPOSES :The purpose of this study is to perform a reliability analysis of the proposed wind load combination which governs the design of support structures of subsidiary road facilities, and to evaluate whether the target reliability of the design is satisfied.METHODS :The statistical estimation method is applied and the design period of the support structure is used to obtain the statistical property of the wind load. In addition, the statistical properties of the strength of support structures are obtained from a literature review and simulation study. Actual support structures are designed by the proposed load combination and are used as the examples to examine if the target reliability is obtained.RESULTS :The result of the reliability analysis performed by using the statistical properties of load and resistance for the support structure in this study indicates that the proposed wind load combination satisfied the target reliability index of the design. Also, the convenience of the design is achieved by adopting the same design wind velocity given in the bridge design code by applying the wind velocity ratio defined for the design period of the support structure.CONCLUSIONS :It is presented that the design using the wind load combination proposed in this study achieved the target reliability index and the design wind load for different design periods can be conveniently defined by applying the velocity ratio proposed in this study.

To study the behavior of structures subject to blast loads it is important to calculate the loads due to the explosives accurately, especially in the case of interior explosions. It is known that numerical method based on computational fluid dynamics can estimate relatively accurate blast load due to the interior explosion including reflection effect. However, the numerical method has disadvantages that it is difficult to model the analysis and it takes much time to analyze it. Therefore, in this study, the analytical method which can include the reflection effect of the interior explosion was studied. The target structures were set as the slabs of residential buildings subject to interior explosion that could lead to massive casualties and progressive collapses. First, the numerical method is used to investigate the interior explosion effect and the maximum deflection of the slab which was assumed to be elastic, and compared with the analytical method proposed in this study. In the proposed analytical method, we determine the weighting factor of the reflection effect using the beam theory so that the explosion load calculation method becomes more accurate.

Cylindrical steel shell sections have been applied in various engineering fields particularly in recent installations of wind turbine towers. Hence, many researchers are interested in studying cylindrical steel shell structures. However, studies on the effect of the presence or absence of openings are insufficient. Thus, the design criteria for the opening as well as the behavior of wind turbine tower are not clearly presented. Therefore, this study examines the ultimate strength and the behavior of wind tower in consideration of openings, presence of stiffeners, changes in opening width, and thickness variation of stiffeners. ABAQUS, a universal finite element analysis program, was used in to conduct this research. Finally, the results of this study can be a reference for the design and production of wind towers with openings.

As the ridges become larger and larger, a structural type that enables effective utilization of the long span and space is required. In the construction stage, the steel column supports the installation load. However, in order to secure the stability against the out - of - plane deformation of the steel column due to the lateral pressure when the concrete is laid, a binding frame is installed inside the steel pipe at constant intervals to resist the concrete installation pressure. When the concrete is cured and its performance as a composite section is exerted, a stress is generated which pushes the steel pipe out of the plane by the column compressive force. In this case, since the binding frame controls the deformation, the local buckling is delayed and the constraining effect on the concrete is increased. In order to evaluate the structural performance and behavior of the composite mega column according to the eccentricity effect and the effect of the binding frame, we carried out a structural test by fabricating eight monopole specimens with the binding frame reinforcement, reinforcing gap, reinforced cross section and eccentricity , And the experimental results are compared with the KBC2016 design formula.

Corrosion is one of the most typical aging phenomena associated with long-term use of steel structures. Corrosion of high-tension bolted connections causes problems such as reduction of thickness of member and relaxation of axial force of high-tension bolt, thereby reducing load-carrying capacity of high-tension bolted connections. In this study, three specimens were subjected to natural corrosion in order to evaluate the residual load-carrying capacity of high-tension bolted connections where corrosion occurred. Two specimens were newly fabricated for comparison with the corroded specimens. In addition, the static bending test was performed to compare and investigate the behavior characteristics of the high-tension bolted connections and the final failure modes. The residual load-carrying capacity of the corroded high-tension bolted connections was evaluated.

Companies are pursuing the management of small quantity batch production or JIT(Just-in-time) system for improving the delivery response and LOB(Line Balancing) in order to satisfy consumers’ increasing demands in the current global economic recession. And in order to improve the growth of production for reducing manufacturing cost, improvements of the Load Balancing have become an important reformation factor. Thus this paper is aimed at warehouse which procures materials on the assembly line in procurement logistics of automotive logistics and proceed with research on heuristic algorithm development which can increase the Load Balancing of workers. As a result of this study, when applied the primary target value, it was verified that the whole workers decreased from 28 to 24. Furthermore, when specified the secondary target value and applied algorithm once more, it was verified that the Load Balance Ratio was improved from 44.96% to 91.7%.

In this study, load transfer tests based on KCI-PS101 were conducted to verify the performance of spiral anchorage zone reinforcement for banded post-tensioning (PT) monostrands. With results, the compressive strength of spiral reinforcement was increased by about 20% than that of specimens with two horizontal steel bars and 8% than that of U-shaped bars. Advanced spiral reinforcement for corner increases compressive strength and can resist the spalling forces or fall-out effect at the corner by shear. The ratio of maximum load to amount of steel of the spiral reinforcement is about twice than that of U-shaped reinforcement. With increase of compressive strength capacity and improvement of constructability, the spiral reinforcement is considered to have advantages of promoting the performance of PT anchorage zone compared to conventional methods.

본 연구는 두꺼운 난류경계층 내에 놓인 구조물의 높이와 방위각이 달라짐에 따라서 나타나는 구조물 주위의 유동특성을 파악하고자 하였다. 구조물 주위의 유동특성을 파악하기 위해 대기경계층 풍동실험을 수행하었다. 구조물의 높이는 3가지로 변화시켰으며, 방위각은 0∼90°까지 변화시켰다. 풍동실험의 레이놀즈수는 각 구조물 높이에 따라 다르게 나타나며 각각의 레이놀즈수는 10.4×104(H1), 29.4×104(H2), 43.2×104(H3) 이다. 연구결과로서 높이와 방위각이 변화함에 따라 모서리에서 발생하는 박리현상이 변화하고 이는 구조물의 표면압력과 섭동압력에 상당한 영향을 끼치는 것을 확인할 수 있었다.

최근 콘크리트 궤도 슬래브 하면과 교량 바닥판 사이에 저마찰 슬라이드층을 형성하는 궤도 시스템인 슬라이딩 궤도와 관 련된 연구가 활발히 진행되고 있다. 본 연구에서는 슬라이딩 궤도에서 열차 주행에 따른 횡방향 하중을 저항하기 위해 설치 되는 횡방향 지지 콘크리트 블록의 전단 내하력에 대한 연구를 수행하였다. 횡방향 지지 콘크리트 블록의 전단 내하력 산정 을 위해 타설경계면에서의 콘크리트 마찰 및 철근의 다월 거동을 고려한 산정 기법을 개발하다. 제안된 산정 기법은 기존의 실험에서 측정된 전단 내하력을 13∼23% 정도 보수적으로 예측하는 것으로 나타났다. 이는 균열면 골재 맞물림 효과를 무 시한 것에 따른 것으로, 현장에서의 타설경계면 상태가 불확실한 것을 고려할 때 횡방향 지지 콘크리트 블록에 대한 안전측 설계를 위해 제안된 산정 기법이 합리적인 것으로 판단된다. 제안된 전단 내하력 산정 기법을 토대로 횡방향 지지 콘크리트 블록에 대한 설계 방안을 마련하였다

This study was conducted to investigate the microbial loads in mulberry fruits depending on cultivation environment and fruit ripeness. The population levels of total aerobic bacteria in mulberry fruits collected from open field orchards were higher than those from three plots protected within plastic green houses. In regards to fruit ripeness, the levels of total aerobic bacteria in ripe black fruits were higher than those in unripe green and red mulberry. From the farms into where livestock animals were allowed to enter, Escherichia coli was detected in soil at a level of 4.26~4.94 log CFU/g and in mulberry fruits at 5.03~6.07 log CFU/g, while no coliform and E. coli were detected from where the intrusion of livestock was prevented. We also examined the density change of inoculated E. coli in mulberry fruits as they were becoming mature. While E. coli did not increase in green fruits, two and four log CFU/g increases at 20oC and 37oC, respectively, were observed with red and fully mature black mulberries during 48 hours incubation. To ensure the food safety of mulberry, it is suggested that the introduction of E. coli into a farm through livestock should be prevented and more hygienic caution should be taken especially when the fruits are ripe.

This paper presents the resizing method of columns and beams that considers column-to-beam strength ratios to simultaneously control the initial stiffness and ductility of steel moment frames. The proposed method minimizes the top-floor displacement of a structure while satisfying the constraint conditions with respect to the total structural weight and column-to-beam strength ratios. The design variable considered in this method is the sectional area of structural members, and the sequential quadratic programming(SQP) technique is used to obtain optimal results from the problem formulation. The unit load method is applied to determine the displacement participation factor of each member for the top floor lateral displacement; based on this, the sectional area of each member undergoes a resizing process to minimize the top-floor lateral displacement. Resizing members by using the displacement participation factor of each member leads to increasing the initial stiffness of the structure. Additionally, the proposed method enables the ductility control of a structure by adjusting the column-to-beam strength ratio. The applicability of the proposed optimal drift design method is validated by applying it to the steel moment frame example. As a result, it is confirmed that the initial stiffness and ductility could be controlled by the proposed method without the repetitive structural analysis and the increment of structural weights.

본 연구는 축산관련차량에 적재물질을 상하차 할 때 발생하는 적재하중을 측정 할 수 있는 로드셀을 개발하고, 개발 로드셀의 성능을 평가한 것이다. 축산관련차량의 차체 하단에 평행 판스프링은 하중이 적재함에 따라 변위가 발생하며, 발생 변위를 개발 로드셀로 측정하여 하중 데이터를 수신하였다. 실험을 위해 실제 차량의 평행 판스프링을 이용하여 실험용 지그를 설계하였고, 실제하중은 프레스(press)를 통해 조성하였다. 실험은 하중이 선형적으로 측정되는지 확인하기 위한 직진성 테스트와 평행 판스프링의 복원력을 확인하기 위해 하중의 증·감소를 통한 히스테리시스 테스트를 진행하였다. 실험결과는 실제하중과 로드셀을 통해 측정한 하중은 비교적 차이를 나타냈지만, 일부 보정을 통해 정확도를 향상 시킬 수 있을 것으로 판단된다. 히스테리시스 테스트의 경우 하중이 감소할 때 평행 판스프링의 탄성으로 인한 오차 발생은 추가적인 센싱을 통해 수정이 필요할 것으로 판단된다.

The efficiency of the purchasing and procurement logistics is important in automotive industry. The rationalization of production system is directly impact on productivity and quality. For this reason importance of logistics is high. Despite we are continuously making effort, our country are still below the level than developed country on logistics efficiency. Rising labor costs is an important factor in increasing logistics costs. So workforce reduction in logistics department is a large part. We deal with A-company inbound logistics, especially procurement logistics in automotive logistics as research object. So in this study we do research on work load balance about workers. We do research on 1,475 kinds of components in procurement process. We applied work load balance algorithm on chassis, final, sequence, trim warehouses workers. According to number of workers and average M/H, algorithm is applied in two ways. After applied work load balance algorithm we reduced numbers of workers from 28 to 20 and improved worker load balance rate from 47.1% to 93.7%

OBJECTIVES : The objective of this study is to analyze the nonlinear behavior of block pavements using multi-load level falling weight deflectometer (FWD) deflections. METHODS: Recently, block pavements are employed not only in sidewalks, but also in roadways. For the application of block pavements in roadways, the structural capacities of subbase and subgrade are important factors that support the carry traffic load. Multi-load level FWD testing was conducted on block pavements to analyze their nonlinear behavior. The deflection ratio due to the increase in load was analyzed to estimate the nonlinearity of block pavements. Finite element method with nonlinear soil model was applied to simulate the actual nonlinear behavior of the block pavement under different levels of load. RESULTS: The results of the FWD testing show that the center deflections in block pavements are approximately ten times greater than that in asphalt pavements. The deflection ratios of the block pavement due to the increase in the load range from 1.2 to 1.5, indicating that the deflection increased by 20~50%. The material coefficients of the nonlinear soil model were determined by comparing the measured deflections with the predicted deflections using the finite element method. CONCLUSIONS: In this study, the nonlinear behavior of block pavements was reviewed using multi-load level FWD testing. The deflection ratio proposed in this study can estimate the nonlinearity of block pavements. The use of nonlinear soil model in subbase and subgrade increases the accuracy of predicting deflections in finite element method.

The blast load is classified into free-air blast and surface blast following the location of explosion and surface. In this paper, several equations for blast load calculation are explained briefly and a modified equation for free-air blast load is suggested. The modified equation is based on Kingery-Bulmash equation which is used in UFC 3-340-02 and Conwep model. In this modified equation, the process of calculation is simplified against the original equation, and the number of coefficients is reduced under 5. As a result, each parameter of estimated data by modified equation has less than 1% of error range comparing with Kingery-Bulmash equation.

Middle size of membrane retractable roof is under 25m span which consists of various moving systems. Trolley is the system that leads the membrane to parking place, transferring the load from the membrane to structural cable. When membrane closes roof completely, thus, structural behavior of trolley, which may contain various material with different friction coefficients, should be investigated by vertical load. Nummerical simulation of trolley prototypes, in this research, was performed by incrementation of vertical load. Consequently, this paper studied proper friction characteristics and provided the effective inner materials of trolley.