• Journal of the Korean Applied Science and Technology
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• v.17 no.1
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• pp.55-61
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• 2000

$Zn_{x}Fe_{3-x}O_{4}(0.00.<X<0.08)$ was synthesized by air oxidation method for the decomposition of carbon dioxide. We investigated the characteristics of catalyst, the form of methane by gas chromatograph after decomposition of carbon dioxide and kinetic parameter. $Zn_{x}Fe_{3-x}O_{4}(0.00.<X<0.08)$ was spinel type structure. The surface areas of catalysts($Zn_{x{Fe_{3-x}O_{4}(0.00.<X<0.08)$) were $15{\sim}27$ $m^{2}/g$. The shape of $Zn_{0.003}Fe_{2.997}O_{4}$ was sphere. The optimum temperature for the decomposition of carbon dioxide into carbon was $350^{\circ}C$. $Zn_{0.003}Fe_{2.997}O_{4}$ showed the 85% decomposition rate of carbon dioxide and the degree of reduction by hydrogen(${\delta}$) of $Zn_{0.003}Fe_{2.997}O_{4}$ was 0.32. At $350^{\circ}C$, the reaction rate constant and activation energy of $Zn_{0.003}Fe_{2.997}O_{3.68}$ for the decomposition of carbon dioxide into carbon were 3.10 $psi^{1-{\alpha}}/min$ and 0.98 kcal/mole respectively. After the carbon dioxide was decomposed, the carbon which was absorbed on the catalyst surface was reacted with hydrogen and it became methane.

• Journal of Korean Neurosurgical Society
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• v.53 no.1
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• pp.6-12
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• 2013

Objective : This consecutive retrospective study was designed to analyze and to compare the efficacy and outcomes of anterior cervical discectomy and fusion (ACDF) using a fibular and femur allograft with anterior cervical plating. Methods : A total of 88 consecutive patients suffering from cervical degenerative disc disease (DDD) who were treated with ACDF from September 2007 to August 2010 were enrolled in this study. Thirty-seven patients (58 segments) underwent anterior interbody fusion with a femur allograft, and 51 patients (64 segments) were treated with a fibular allograft. The mean follow-up period was 16.0 (range, 12-25) months in the femur group and 19.5 (range, 14-39) months in the fibular group. Cage fracture and breakage, subsidence rate, fusion rate, segmental angle and height and disc height were assessed by using radiography. Clinical outcomes were assessed using a visual analog scale and neck disability index. Results : At 12 months postoperatively, cage fracture and breakage had occurred in 3.4% (2/58) and 7.4% (4/58) of the patients in the femur group, respectively, and 21.9% (14/64) and 31.3% (20/64) of the patients in the fibular group, respectively (p<0.05). Subsidence was noted in 43.1% (25/58) of the femur group and in 50.5% (32/64) of the fibular group. No difference in improvements in the clinical outcome between the two groups was observed. Conclusion : The femur allograft showed good results in subsidence and radiologic parameters, and sustained the original cage shape more effectively than the fibular allograft. The present study suggests that the femur allograft may be a good choice as a fusion substitute for the treatment of cervical DDD.

• Tunnel and Underground Space
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• v.21 no.2
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• pp.128-137
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• 2011

The shut-in pressure calculated in common hydrofracturing test for vertical borehole equals generally to the minimum horizontal principal stress, so it should be considered as an essential parameter for determining the in-situ stress regime around the rock mass. It shows usually an ambiguous value in pressure-time history curves, however, because of the relationship between the behavior of hydraulic fractures and the condition of remote stress regime. In this study, a series of numerical analyses have been carried out to compare several methods for determining the shut-in pressure during hydrofracturing. The hydraulic-mechanical coupling has been applied to numerical analysis for simulating the fracture propagation by hydraulic pressure, and the different discontinuity geometry has been considered in numerical models to examine the effect of numerical element shape on fracture propagation pattern. From the numerical simulations with the four different discontinuity geometries, it was revealed that the shut-in pressure obtained from graphical methods rather than statistical method was relatively small. Consequently a care should be taken in selecting a method for determining the shut-in pressure when a stress anomaly around borehole and a fracture propagation with complicate mechanism are considered.

• Journal of the Korean Solar Energy Society
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• v.30 no.4
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• pp.9-14
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• 2010

The main cause of global warming is carbon dioxide generated from the use of fossil fuels, and active research on the reduction of carbon is in progress to slow down the increasing global warming. Wind turbines generate electricity from kinetic energy of wind and are considered as representative for an energy source that helps to reduce carbon emission. Since the kinetic energy of wind is proportional to the cube of the wind speed, the intensity of wind affects wind farm construction validity the most. Therefore, to organize a wind farm, validity analysis should be conducted first through measurement of the wind resources. To facilitate the approval and permission and reduce installation cost, measuring sensors should be installed at locations below the actual wind turbine hub. Wind conditions change in shape with air density, and air density is most affected by the variable sterrain and surface type. So the magnitude of wind speed depends on the ground altitude. If wind conditions are measured at a location below the wind turbine hub, the wind speed has to be extrapolated to the hub height. This correction of wind speed according to height is done with the Deacon equation used in the statistical analysis of previously observed data. In this study, the optimal Deacon equation parameter was obtained through the analysis of the correction of the wind speed error with the Deacon equation based on the characteristics of terrain.

• Transactions of Materials Processing
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• v.29 no.3
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• pp.157-162
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• 2020

Blind rivet nuts are increasingly used in automotive for the joining of sheets. Their application, however, requires appropriate design guides to prevent catastrophic events arising from the failure of joints. In this study, the shaft shape of a frequently used M8 blind rivet nut is optimized based on 3D numerical analysis of the blind rivet nut considering the characteristics of thread. The thread needs to be modeled to suitably consider the fastening of the M8 bolt after the crimping process. FE analysis showed that while the friction in the contact between crimp flange and plate has no significant effect on the crimp geometry, shaft thickness (t) and shaft height (h) are the most significant design variables. The parameter study including various combinations of t and h reveals that they affect the gap (the distance between the crimped flange and the plate that develops through riveting) and the load acting on the plate. The gap is an indicator of the tightening force. It is found that t is inversely proportional to the gap, and proportional to the load, whereas h is proportional to the gap and inversely proportional to the load. Based on our FE analysis results, we propose the range 0.062 < t/h < 0.1 to ensure sufficient fastening (high clamping load, small gap) of the M8 blind rivet nut. The design guide for determining the t/h ratio proposed in this study can be used for general quantitative analysis of the size and the t/h ratio of blind rivet nuts.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.1
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• pp.11-13
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• 2013

Background: Esophagus cancer, the third most common gastrointestinal cancer overall, demonstrates high incidence in parts of Iran. The counties of Iran vary in size, shape and population size. The aim of this study was to account for spatial support with Area-to-Area (ATA) Poisson Kriging to increase precision of parameter estimates and yield correct variance and create maps of disease rates. Materials and Methods: This study involved application/ecology methodology, illustrated using esophagus cancer data recorded by the Ministry of Health and Medical Education (in the Non-infectious Diseases Management Center) of Iran. The analysis focused on the 336 counties over the years 2003-2007. ATA was used for estimating the parameters of the map with SpaceStat and ArcGIS9.3 software for analysing the data and drawing maps. Results: Northern counties of Iran have high risk estimation. The ATA Poisson Kriging approach yielded variance increase in large sparsely populated counties. So, central counties had the most prediction variance. Conclusions: The ATAPoisson kriging approach is recommended for estimating parameters of disease mapping since this method accounts for spatial support and patterns in irregular spatial areas. The results demonstrate that the counties in provinces Ardebil, Mazandaran and Kordestan have higher risk than other counties.

• The Journal of the Acoustical Society of Korea
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• v.34 no.6
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• pp.487-492
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• 2015

A short-range underwater target detection and identification techniques using mid- and high-frequency bands have been highly developed. However, nowadays the long-range detection using the low-frequency band is requested and one of the most challengeable issues. The waveform inversion technique is widely used and the hottest technology in both academia and industry of the seismic exploration. It is based on the numerical analysis tool, and could construct more than a few kilometers of the subsurface structures and model-parameters such as P-wave velocity using a low-frequency band. By applying this technique to the underwater acoustic circumstance, firstly application of underwater target detection is verified. Furthermore, subsurface structures and it's parameters of the war-field are well reconstructed. We can confirm that this technique greatly reduces the false-alarm rate for the underwater targets because it could accurately reproduce both the shape and the model-parameters at the same time.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.2
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• pp.29-33
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• 2011

Research about the geometry design of lead pin was carried based on the normal or shear stress of the interface between a lead pin and a PCB in terms of delamination failure. The taguchi method with four design factors of three levels and FEA(Finite element Analysis) are carried under $20^{\circ}$ bending and 50 ${\mu}m$ tension of lead pin. The contact width, d2, between head round and copper pad in PCB is the highest affection factor among design factors by analysis of contribution analysis. Equivalent von Mises stress of 18.7% reduction design is obtained by the parameter design of the taguchi method. Maximum normal stress occurred at contact position between solder outer surface and a Cu pad in PCB. Also, maximum shear stress happened at contact position between solder outer surface and SR layer of PCB. From these calculated results, delamination of the PGA package may be occurred from outer interface of solder to inner interface of solder.

• Korean Chemical Engineering Research
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• v.49 no.2
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• pp.195-199
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• 2011

Mo thin films were deposited on soda lime glass at room temperature by using DC magnetron sputtering The electrical and structural properties of the films were investigated by varying DC power and gas pressure as the deposition parameter. As DC power increased, the deposition rate of Mo films was increased and the electrical resistivity was decreased. It was observable that the crystallinity of the films was improved with increasing DC power. As gas pressure decreased, the deposition rate and resistivity of the films were decreased, and long rectangular grains were densely formed. With increasing gas pressure, the grains were transformed to a round shape and the voids on the film surface were increased. It was confirmed that the electrical resistivity of Mo films was increased as the amount of oxygen combined with Mo atoms increased. It was also disclosed that the films have low resistivity as the degree of coupling of oxygen with Mo was reduced due to the enhancement of the crystallinity of the films.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.3
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• pp.385-396
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• 1993

In this paper, a improved method of digital image analysis required in basic medical science for diagnosis of cells was proposed. The object image was the thyroid gland cell image, and the purpose was automatic discrimination of three classes cells(normal cell, follicular neoplastic cells, and papillary neoplastic cells) by difference of chromatin patterns. To segment the cell nucleus from background, the region segmentation algorithm by edge tracing was proposed. And feature parameter was obtained from discrete Fourier transformation of image. After construct a feature sample group of each cells, experiment of discrimination was executed with any verification cells. As a consequency of using features proposed in this paper, get a better recognition rate(70-90%) than previously reported papers, and this method give shape to get objectivity and fixed quantity in diagnosis of cells, The methods described in this paper be used immediately for discrimination of neoplastic cells.