• Tribology and Lubricants
• /
• v.36 no.2
• /
• pp.82-87
• /
• 2020

In thrust bearings, the thrust collar and bearing surface need to be parallel to each other to ensure that all pads share the same load. In rotating machines, the shaft system cannot achieve perfect alignment. Misalignment of the thrust collar results in some pads supporting a higher load than others and excessive loads being placed on some pads. Consequently, high loads and high temperatures may occur in the bearing. Thus, in this study, we aim to analytically evaluate the performance of a misaligned non-equalizing direct lubricated tilting pad thrust bearing. We define the oil film thickness of the misaligned thrust bearing using the Byrant angle. Additionally, we calculate the pressure distribution and temperature distribution of the thrust bearing using the generalized Reynolds equation and energy equation. The design limit of the thrust bearing is defined by the load and temperature. Therefore, we evaluate the allowable misalignment angle as the limit of the maximum load and temperature. The analysis results demonstrate that an increase in the speed and load corresponds to a smaller allowable misalignment angle. However, as this is not the same for all thrust bearings, evaluating the allowable misalignment angle at each thrust bearing is essential.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.21 no.5
• /
• pp.104-112
• /
• 2013

This study investigates the structural analysis result with vibration and fatigue on 3 kinds of bicycle saddle models. When the static load applies on the upper plane of model, maximum stress becomes within the allowable stress in case of model 1. As the value of Stress or deformation becomes lower on the order of model types 1, 2 and 3, these models become more stabilized or safer at durability in this order. On the vibration analysis, model type 1 has the maximum stress or deformation more than 5 times by comparing with model type 1 or 2. Model type 1 becomes most excellent on vibration durability. As maximum displacement due to vibration happens in case of model type 3, it becomes unstabilized. But the stresses of model types 1, 2 and 3 become within the allowable stress and these models are considered to be safe. At the status of the severest fatigue load, model type 3 becomes safer than model type 1 or 2. This study result is applied with the design of safe bicycle saddle and it can be useful to improve the durability by predicting prevention against the deformation due to its vibration and fatigue.

• Journal of the Architectural Institute of Korea Structure & Construction
• /
• v.35 no.10
• /
• pp.191-198
• /
• 2019

In this paper the evaluation scheme for determining torsional irregularity of Hanok has been proposed. The proposed method can evaluate torsional irregularity of Hanok easily only with characteristics of Hanok shapes, arrangement of lateral load resisting frames and their lateral stiffness without time consuming and complicate 3-dimensional structural analysis. The proposed formula is expressed as allowable maximum eccentricity, and torsional irregularity is evaluated by comparing this value with actual eccentricity. The applicability of the proposed scheme was evaluated by applying it to the line shape plan Hanok with two symmetrically arranged walls and the result was expressed by formula and graph. The results showed that the allowable maximum eccentricity is 10% of plan dimension perpendicular to the seismic load when the walls are placed at the extreme end. The proposed formula was expressed as a generalized formula so it can be applied generally to the various plan shape and wall arrangement of Hanok.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.7
• /
• pp.1263-1269
• /
• 2009

Stable and sustainable power supply means maintaining a certain level of power quality and service while securing energy resource and resolving environmental issues. Distributed generation (DG) has become an essential and indispensable element from environmental and energy security perspectives. It is known that voltage violation is the most important constraint for load variation and the maximum allowable DG. In distribution system, sending voltage from distribution substation is regulated by ULTC (Under Load Tap Changer) designed to maintain a predetermined voltage level. ULTC is controlled by LDC (Line Drop Compensation) method compensating line voltage drop for a varying load, and the sending voltage of ULTC calls for LDC parameters. The consequence is that the feasible LDC parameters considering variation of load and DG output are necessary. In this paper, we design each LDC parameters determining the sending voltage that can satisfy voltage level, decrease ULTC tap movement numbers, or increase DG introduction. Moreover, the maximum installable DG capacity based on each LDC parameters is estimated.

• Proceedings of the KSME Conference
• /
• 2000.11a
• /
• pp.357-362
• /
• 2000

Allowable stress design(ASD) method has been widely used to design steel structures such as boiler and heat recovery steam generator(HRSG) of power plant. However, many researchers are recently intrested in road and resistance factor design(LRFD) method which may take the place of ASD. In this work, the weight calculation of steel structure was compared when ASD and LRFD were applied respectively. For the calculation of weight of steel structure, computer program was developed and applied to obtain beam weight. Using this program and GTSTRUDL, structural design program, weight of steel structure is calculated. As a result of weight calculation, maximum 5.4% of weight reduction is achieved among examples of this study by applying LRFD comparing with the result of ASD, and those results quite dependent on the applied load and member classification.

• Journal of the Korean Geosynthetics Society
• /
• v.18 no.3
• /
• pp.45-53
• /
• 2019

In this study, it was analyzed the cases of bored PHC piles designed for the building foundations. The overall length of the piles varies within a maximum of 35 m. However, the average length was 17.0 to 18.9 m depending on the kind of the bedrock, with no significant difference. The socket length entered into the bedrock was designed with approximately 58% of the whole piles being 1m, the minimum length of the specification, and up to 5m. Although the range in design efficiency was very large, on average it was about 70%, consistent with the usual known extent. Applications with low design efficiency were mainly shown on the foundation of low-rise buildings or rides with low design load. On the weathered rock, the design load, which governs the design result was widely distributed at 65 to 97% of allowable bearing capacity of ground. The ratio of allowable axial load of piles to allowable bearing capacity of ground is also widely distributed between 36 and 115%, so optimization efforts are required along with design efficiency. On the other hand, the allowable bearing capacity on the soft or hard rock was highly equal, mostly within 90% of the allowable axial load of piles. In the design, the end bearing resistance averaged over 75% of the allowable bearing capacity. However, the results of the dynamic pile load test show that the end bearing resistance was predominant under the E.O.I.D conditions, and in some cases, the end bearing resistance was at least 25% under the restrike conditions.

• The Journal of Engineering Geology
• /
• v.29 no.3
• /
• pp.211-222
• /
• 2019

This study evaluates the yield load and allowable bearing capacity of ground in compressive loading tests to confirm the effect of CPR foundation reinforcement. The average compressive strength of the injection materials was higher than the planned compressive strength. Standard penetration tests for each stratum showed that foundation reinforcement improved the average N values, thereby increasing the bearing capacity of the ground. Compressive loading tests on two CPR piles revealed that the total and net settlement due to the maximum load exceed that permissible for the CPR pile diameter. The yield load and allowable bearing capacity calculated by the settlement criterion and the load-settlement curves varied greatly with the method applied. Therefore, it seems to be necessary to determine the optimum value through comprehensive analysis after applying various yield load calculation methods.

• Steel and Composite Structures
• /
• v.7 no.3
• /
• pp.201-217
• /
• 2007

Two combinatorial optimization algorithms, tabu search and simulated annealing, are presented for the minimum-weight design of geometrically non-linear steel plane frames. The design algorithms obtain minimum weight frames by selecting suitable sections from a standard set of steel sections such as American Institute of Steel Construction (AISC) wide-flange (W) shapes. Stress constraints of AISC Load and Resistance Factor Design (LRFD) specification, maximum and interstorey drift constraints and size constraints for columns were imposed on frames. The stress constraints of AISC Allowable Stress Design (ASD) were also mounted in the two algorithms. The comparisons between AISC-LRFD and AISC-ASD specifications were also made while tabu search and simulated annealing were used separately. The algorithms were applied to the optimum design of three frame structures. The designs obtained using tabu search were compared to those where simulated annealing was considered. The comparisons showed that the tabu search algorithm yielded better designs with AISC-LRFD code specification.

• Journal of the Korean Geotechnical Society
• /
• v.35 no.9
• /
• pp.15-28
• /
• 2019

Long-term allowable compressive Loads of PHC piles were analyzed based on qualification tests results by 17 small and medium PHC pile producing companies and product specifications by 6 major and 17 small and medium PHC pile producing companies. At the present stage, an average long-term allowable compressive load of PHC pile was designed at 70% level from current design data, and safety factor of 4.0 was applied to long-term allowable compressive loads of PHC pile despite of its excellent quality. Most quality standards of PHC pile are specified at KS F 4306. But compressive strength test method of spun concrete is specified at KS F 2454. As a result of analyzing quality test data supplied by each manufacturer, all quality test results showed higher performances than standard values. Therefore, it was considered that the capacity of PHC pile can be used up to the maximum allowable compressive load of PHC pile when PHC pile is designed.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.18 no.1
• /
• pp.116-121
• /
• 2019

The LVDT (Linear Variable Displacement Transducer) type sensor used for the existing ship's steering gear is simple on / off that does not perform proportional control operation to the control & unloading device. When the main spool is located at both extremes, It is reflected in the price by using an expensive sensor for import. In this paper, the Hall Effect Sensor is applied to Hydraulic Locking Alarm to analyze classification rules, structure, characteristics and operation principle of valves, and research on localization development in terms of cost reduction. The comparative analysis of the existing prototypes and the cause analysis of the problems were carried out, and the structural analysis showed satisfactory results within the allowable stress range. In addition, it was verified through experiments that the actual operation is realized by applying the actual developed product, and it was confirmed that the load on the maximum value exceeds the allowable maximum load even in the case of the universal tensile test in preparation for the departure of the rod casing.