• Journal of Korea Spatial Information System Society
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• v.11 no.2
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• pp.119-132
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• 2009

Owing to the GIS technology, a vast volume of spatial data has been accumulated, thereby incurring the necessity of spatial data mining techniques. In this paper, we propose a new spatial data mining system named SD-Miner. SD-Miner consists of three parts: a graphical user interface for inputs and outputs, a data mining module that processes spatial mining functionalities, a data storage model that stores and manages spatial as well as non-spatial data by using a DBMS. In particular, the data mining module provides major data mining functionalities such as spatial clustering, spatial classification, spatial characterization, and spatio-temporal association rule mining. SD-Miner has own characteristics: (1) It supports users to perform non-spatial data mining functionalities as well as spatial data mining functionalities intuitively and effectively; (2) It provides users with spatial data mining functions as a form of libraries, thereby making applications conveniently use those functions. (3) It inputs parameters for mining as a form of database tables to increase flexibility. In order to verify the practicality of our SD-Miner developed, we present meaningful results obtained by performing spatial data mining with real-world spatial data.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.5
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• pp.28-34
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• 2014

A planetary gear train is more compact and endures greater amounts of transmission power compared to other gear systems. Although planetary gear systems operate in small volumes, they are capable of very high efficiency due to the compact combination of their gears in the planetary gear system. They also have outstanding efficiency of only 3% for power transmission, tantamount to the power loss that occurs in each of the shift stages. Given these advantages, planetary gear systems are used in the driving systems of, which are widely used in automobile transmissions, machine tools, semiconductor equipment, and in other areas in industrial fields. Current structural equipment requires higher efficiency and greater torque levels. According to these needs, we have designed a complex planetary gear system which creates higher levels of torque. In this paper, an evaluation of strength designs for the proposed planetary gear system was conducted to ensure the stability of the gear. In addition, a durability analysis based on Miner's rule was performed using RS B 0095 device.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.5
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• pp.573-580
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• 2007

This paper presents the numerical estimation of the fatigue life for the frame box's welded parts of the marine vessel engine S60MC-C. The time-variations of the effective stresses at the critical points during a piston cycle are computed through the finite element analysis, by applying the dynamic loadings that were analytically derived in the previous paper. The fatigue lives of the welded parts are estimated by making use of the hot-spot stress extrapolation and the Palmgren-miner cumulative damage rule.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.166-169
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• 2004

A fatigue test was used to evaluate the fatigue life of an actual structure. The loaded state and the constraint condition of an actual structure must be same as the specimen in order to apply the test results to an actual structure by the specimen. The loaded state and constraint conditions can't be same as the specimen in the actual structure which is complicated. In order to reduce these differences, an actual structure test with a lot of frequencies is need to get a fatigue life curve. Therefore, ten sets of accelerated test units which attached unbalanced mass were composed in this study. Acceleration history about the vibration of an actual structure was acquired. Rainflow counting was used on acceleration history, and the life curve return formula was assumed. The return formula that damage satisfied `1' was acquired in a feedback process by the Miner's rule, which was the linear cumulative damage theory. A conservative fatigue life curve was determined with a return formula to have been presumed by each set. The fatigue life of regular rpm condition was calculated by these conservative fatigue life curves.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.4
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• pp.388-395
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• 2009

An accelerated fatigue test is essentially required to maintain the reliability of the actual structures of KTX under operation conditions. However, actual fatigue life cannot be obtained because the conventional fatigue tests are not adequate to the real load conditions. Moreover foreign component makers have not provided data of the loading stresses (S) versus cycles at the failure (N). In this study, we suggested a deduction method of the S-N curve for establishing an accelerating test under various load levels. Load history was acquired from the field tests. A Rainflow method was used on the cycle counting of the field load data. After that, an S-N curve was obtained through the iteration process under the condition that the damage index satisfies to 1 in the Miner's rule. The deduced S-N curve was applied to the performance evaluation of Korean-made sealed knuckles compared with imports.

• Steel and Composite Structures
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• v.33 no.3
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• pp.433-444
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• 2019

Fatigue failure of a grid structure using bolt-sphere joints is liable to occur in a high-strength bolt due to the alternating and reciprocal actions of a suspension crane. In this study, variable amplitude fatigue tests were carried out on 20 40 Cr steel alloy M30 high-strength bolts using an MTS fatigue testing machine, and four cyclic stress amplitude loading patterns, Low-High, High-Low, Low-High-Low, and High-Low-High, were tested. The scanning electron microscope images of bolt fatigue failure due to variable amplitude stress were obtained, and the fractographic analysis of fatigue fractures was performed to investigate the fatigue failure mechanisms. Based on the available data from the constant amplitude fatigue tests, the variable amplitude fatigue life of an M30 high-strength bolt in a bolt-sphere joint was estimated using both Miner's rule and the Corten-Dolan model. Since both cumulative damage models gave similar predictions, Miner's rule is suggested for estimating the variable-amplitude fatigue life of M30 high-strength bolts in a grid structure with bolt-sphere joints; the S-N fatigue curve of the M30 high-strength bolts under variable amplitude loading was derived using equivalent stress amplitude as a design parameter.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.1
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• pp.73-80
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• 2022

Sensors are applied to small aviation platforms for various purposes. Radio frequency (RF) antennas, which are representative sensors, are available in many forms but require the application of slot array RF antennas to ensure high performance and designation. Slot RF array antennas are applied to dip brazing techniques, but the yield and production time are determined by the proficiency of production personnel in a labor-intensive form. Unmanned aerial vehicles or drones, which are representative small aviation platforms, are continuously exposed to various random vibrations because propellers and multiple power sources are used in them. In this study, the fatigue life of slot array RF antennas applied with additive manufacturing was evaluated through the cumulative damage method (Miner's rule) in a vibration environment with a small aviation platform. For the evaluation, an S N curve obtained from a fatigue strength test was used.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.2
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• pp.75-84
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• 1997

The up-to-date fatigue strength assessment system for ship structures was developed based on the spectral analysis method and numerical calculation for a membrane type LNG carrier was carried out to verify the effectiveness of the developed system. The wave induced loads acting on the ship's hull were calculated based on strip theory. And introducing the concept of influence factor and 3-D fine mesh structural analysis, direct calculation of long-term distribution of wave induced stress components was realized. Using the derived long term distribution of stress components and Miner-Parmgren's linear damage accumulation rule, fatigue strength of structural components were investigated.

• Journal of the Korean Data and Information Science Society
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• v.20 no.2
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• pp.425-433
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• 2009

Data mining is the method to find useful information for large amounts of data in database. It is used to find hidden knowledge by massive data, unexpectedly pattern, relation to new rule. We need a data mining tool to explore a lot of information. There are many data mining tools or solutions; E-Miner, Clementine, WEKA, and R. Almost of them are were focused on diversity and general purpose, and they are not useful for laymen. In this paper we design and implement a web-based data mining tool using PHP and WEKA. This system is easy to interpret results and so general users are able to handle. We implement Apriori algorithm of association rule, K-means algorithm of cluster analysis, and J48 algorithm of decision tree.

• Journal of Welding and Joining
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• v.22 no.2
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• pp.28-32
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• 2004

Fatigue life at seam weldment of thick plate was estimated using the finite element and FEM-FAT(an exclusive fatigue solver). Finite element meshing at toe and root of weldment was based oil Radaj's theory. Also, the results of FE analysis were compared with experimental results in the point of Miner's Rule. The results of FE and FEM-FAT analysis were in accord with experimental results within 60% confidence. This result reveals that above techniques is useful in assessment of seam weldment and to be an alternative method instead of an object experiment.