• The Journal of Korean Academy of Prosthodontics
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• v.38 no.3
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• pp.348-357
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• 2000

The purpose of this study is to examine the effect of partial osseointegration situation on bone loading patterns around two different free-standing screw shaped implants (Nobel Biocare, Gothenburg, Sweden and Degussa-Huls, Hanau, German). Two dimensional axisymmetric Finite element models of two implants(10mm length and 4mm diameter) were created according to different bone quantity, quality and osseointegration ratio in maxilla and mandible bone. At the same time uni-cortical and hi-cortical fixation were analyzed. Generally, full bond case showed less stress than partial bond case in overall area and mandibular model showed less amount of stress than that of maxilla model. Maximum stress of the Branemark implant is higher than that of ANKYLOS regardless of bonding ratio at crestal and apex region. However, more stress concentration was noted in ANKYLOS implant at screw body area especially in mandible. The effect of bicortical fixation on crestal bone stress reduction is dramatical in mandible however, there was no significant effect in maxillary case. The effect of partial bond on stress distribution was more significant at screw body and apex region than in crestal region. Partial bond cases demonstrated greater stress accumulation in trabecular bone than cortical bone. It is concluded that the more accurate model of implant and bone which affects stress and strain distribution is needed to mimic in vivo behavior of implants.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.6
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• pp.71-77
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• 2010

Although the problems of defects and nonmetallic inclusion in metal fatigue are very complicated, it is particularly important to view these problems from the perspective that defects and inclusions are virtually equivalent to small cracks. This concept will help one to understand various fatigue phenomena caused by Ductile Cast Iron. For different ferrite-pearlite matrix structure, containing more than 90% spheroidal ratio of graphite, GCD 45-3, GCD 50, GCD 60 series and 70%, 80%, 90% spheroidal ratio of graphite, GCD 40, GCD 45-1, GCD 45-2 series, this paper has carried out image analyzer, estimated maximum and mean size of graphite, investigated correlation. It was concluded as follows. (1) A good quality of Ductile cast iron using in this experiment, the graphite was separated well. The effect of the interaction by graphite was verified by microscopic observation and by fracture mechanics investigation in surface, interior of the specimen. (2)${\sqrt{area}}_{max}$ of graphite can be used to predict fatigue limit of Ductile Cast Iron. The Statistical distribution of extreme values of ${\sqrt{area}}$ may be used as a guide line for the control of inclusion size in the steel making processes.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2615-2623
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• 2002

In this paper, a systematic design approach for a three shaft hydromechanical transmission(HMT) system is proposed by considering the power characteristics and speed ratio range. Using network analysis, possible configurations of the 3 shaft HMT are analyzed and it is found that the influence of HSU stroke on the power distribution of the HMT can be investigated by the network analysis. In addition, design methods are presented from the viewpoint of (1) power distribution and (2) speed ratio range. From the power distribution and the speed ratio range, a HMT configuration can be constructed, which minimizes the power circulation and provides the desired speed ranges. Based on the 3 shaft HMT analyses and the proposed design approach, a 3 shaft HMT is designed which provides 4 speeds in forward and 1 speed in reverse while keeping the power circulation less than 150% of the input power. It is expected that the design method suggested in this study can be used in a systematic design of the 3 shaft HMT.

• Steel and Composite Structures
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• v.33 no.6
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• pp.865-875
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• 2019

The current article proposed to develop a geometrical model for the analysis and modelling of the uniaxial functionally graded structure using the higher-order displacement kinematics with and without the presence of porosity including the distribution. Additionally, the formulation is capable of modelling three different kinds of grading patterns i.e., Power-law, sigmoid and exponential distribution of the individual constituents through the thickness direction. Also, the model includes the distribution of porosity (even and uneven kind) through the panel thickness. The structural governing equation of the porous graded structure is obtained (Hamilton's principle) and solved mathematically by means of the isoparametric finite element technique. Initially, the linear frequency parameters are obtained for different geometrical configuration via own computer code. The comparison and the corresponding convergence studies are performed for the unidirectional FG structure for the validation purpose. Finally, the impact of different influencing parameters like aspect ratio (O), thickness ratio (S), curvature ratio (R/h), porosity index (λ), type of porosity (even or uneven), power-law exponent (n), boundary condition on the free vibration characteristics are obtained for the FG panel and discussed in details.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.6
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• pp.61-69
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• 2004

The aim of the work described in this paper was to confirm the application of the equation of the soil-water characteristic curves on an unsaturated soil. A series of suction test for unsaturated soils was conducted on the selected 4 kinds of soil using modified pressure extractor apparatus. And it was carried out to analyse The experimental parameters which can be describe the soil-water characteristics, were determined by using the data obtained from the experiment. From the results, it was found that The matric suction varied according to the grain size distribution, amount of fine grain particles and void ratio. Also it was found that the residual degree of saturation was decreased with in crease of the void ratio, but the pore size distribution index and air entry value were increased with in crease of the void ratio. And The application of the soil-water characteristic curve equation was confirmed for the various conditions and the various state by the comparison between the measured degree of saturation and the predicted degree of saturation.

• The Journal of Korean Physical Therapy
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• v.7 no.1
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• pp.33-42
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• 1995

The purposes of this study were 1) to compare weight distribution and ratio of the extremities between normal and hemiplegic children in quadruped position and 2) to compare the effect of ATNR on weight bearing of the extremities between normal and hemiplegic children. The subjects fer the study were 48 children(24 normal, 24 hemiplegic) between the ages 3 to 6. They were teated weight distribution and ratio of the extremities in the neutral position of head and by passive right and left rotation of the head in the quadruped position. The data wert analized by paired t-test. The results were as follows: 1. In the neutral position of head, normal group was not difference on weight distribution and ratio of the extremities and hemiplegic group was more weight bearing on the sound upper extremity than the affected upper extremity(p<.01). 2. When the head rotated to the dominant side or sound side passively, there was not a significant difference between normal and hemiplegic group. 3. When the head rotated to the nondominant side or affected side passively, there was a significant difference between nondominant upper extremity nf normal and affected upper extremity of hemiplegic group(p<.05).

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.9
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• pp.24-36
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• 1996

In this paper, we discuss the errors in selectivity estimation using the multilevel grid file (MLGF). We first demonstrate that the estimatio errors stem from the uniformity assumption that records are uniformly distributed in their belonging region represented by an entry in a level of an MLGF directory. Bsed on this demonstration, we then investigate five factors affecting the accuracy of estimation: (1) the data distribution in a region (2) the number of records stored in an MLFG (3) the page size, (4) the query region size, and (5) the level of an MLFG directory. Next we present the tendancy of estimation errors according to the change of values for each factor through experiments. The results show that the errors decrease when (1) the distribution of records in a region becomes closer to the uniform one, (2) the number of records in an MLFG increases, (3) the page size decreases, (4) the query region size increases, and (5) the level of an MLFG directory employed as data distribution information becomes lower. After the definition of the granule ratio, the core formula representing the basic relationship between the estimation errors and the above five factors, we finally examine the change of estimation errors according to the change of the values for the granule ratio through experiments. The results indicate that errors tend to be similar depending on the values for the granule ratio regardless of the various changes of the values for the five factors. factors affecting the accuracy of estimation:

• Journal of Environmental Science International
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• v.12 no.11
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• pp.1145-1157
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• 2003

The surface sediments inside Hallim Harbor, one of the major harbors of Jeju Island, were sampled three times (June, September and December, 2001) and analyzed for 16 polycyclic aromatic hydrocarbons (PAHs), recommended by US-EPA as priority pollutants, to assess their distribution levels and to suggest their possible origins. The concentrations of PAHs ranged from 19 to 496 ng/g on a dry weight basis with a mean value of 245 ng/g, and the levels were low to moderate in comparison with other areas in the world. Based on comparisons of individual and total PAH concentrations with effects-based and equilibrium partitioning-based on sediment quality guidelines, the potential for the biological effects were expected to be low. The sedimentary PAHs may be correlated with organic carbon and mud contents to some extent. From the examinations of the four PAH origin indices, such as LMW/HMW (low molecular weight 2-3 ring PAHs over high molecular weight 4-6 ring PAHs), phenanthrene/anthracene ratio, fluoranthene/pyrene ratio, chrysene/benzo〔a〕anthracene ratio, it can be concluded that the sediment PAH contaminations were ascribed to both pyrolytic and petrogenic origins.

• The Journal of Engineering Geology
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• v.6 no.3
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• pp.111-118
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• 1996

In general, a three dimensional ground behaviour during tunneling is simulated by using two dimensional analysis programs in consideration of a certain ratio of stress or strain distribution to take into account the effect of construction stage by a tunnel face advance. A series of trree dimensional analyses was conducted to deduce a normalized displacement (surface or crown settlement) curve in longitudinal direction, of which curve is reflecting an effect of a tunnel advance under a various condition. And, by using try and error technique, two dimensional analyses were carried out to determine an optimum stress distribution ratio for a settiement curve coincided with the curve obtained by three dimensional analyses. Finally, monitored results from a subway tunnel were compared with two dimensional analysis results for varification of the deduced stress distribution ratio as well as the two dimensional analysis program employed in this study.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.790-793
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• 2005

In these days, the piezoresistive material has been applied to various sensors in order to measure the change of physical quantities. But the relationship between the sensitivity of a sensor and the position and size of piezoresistor has rarely been studied. Therefore, this paper was focused on the effect of residual stress induced in piezoresistor on the distribution of resistance change ratio and supposed the feasible position of piezoresistor. The resulting are following; The tensile residual stress in the vicinity of piezoresistor decreased the value of resistance change ratio and could not effect on all the area of diaphragm but local area around the piezoresistor. Also, the piezoresistor in the diaphragm type pressure sensor with boss should fabricate in the edge of boss in order to increase the sensitivity of pressure sensor.