• Structural Engineering and Mechanics
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• v.57 no.1
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• pp.91-103
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• 2016

This investigation is concerned with the disturbances in a homogeneous transversely isotropic thermoelastic rotating medium with two temperature, in the presence of the combined effects of Hall currents and magnetic field due to normal force of ramp type. The formulation is applied to the thermoelasticity theories developed by Green-Naghdi Theories of Type-II and Type-III. Laplace and Fourier transform technique is applied to solve the problem. The analytical expressions of displacements, stress components, temperature change and current density components are obtained in the transformed domain. Numerical inversion technique has been applied to obtain the results in the physical domain. Numerically simulated results are depicted graphically to show the effects of Hall current and anisotropy on the resulting quantities. Some special cases are also deduced from the present investigation.

• Journal of the Korean GEO-environmental Society
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• v.23 no.9
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• pp.25-31
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• 2022

Attaching shelf to retaining structure leads to a decrease in the total lateral earth pressure. This decrease enables the retaining structures to become more stable, to have small displacement, and to exhibit lower bending moments, the relief shelves effects are analyzed using FEM in order to understand how they stabilize cantilever wall in this study. Several models are varied by changing location and width of shelves to realize earth pressure and displacements of retaining wall. The displacement is getting smaller because earth pressure acting on shelf increases as shelves locations are lower and width is longer. The ground settlement variation effects caused by relief shelves are studied also. The ground settlement increases abruptly where shelf location is between of 0.5H and 0.625H, and settlement decreases suddenly where shelf width is between b/h=0.375 and b/h=0.500. The shelf significantly reduces earth pressure and movement of the wall. This decrease in the lateral pressure increases the retaining structure stability.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.835-841
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• 2013

Modern solid-state gyroscopes (HRG) with hemispherical resonators from high-purity quartz glass and special surface superfinishing and ultrathin gold coating become the best instruments for precise-grade inertial reference units (IRU) targeting long-term space missions. Designing of these sensors could be a notable contribution into development of Korea as a space nation. In participial, 40mm diameter thin-shell resonator from high-purity fused quartz, fabricated as a single-piece with its supporting stem has been designed, machined, etched, tuned, tested, and delivered by STM Co. (ATS of Ukraine) several years ago; an extremely-high Q-factor (upto 10~20 millions) has been shown. Understanding of the best way how to match such a unique sensor with inner glass assembly of the gyro means how to use the high potential in a maximal extent; and this has become the urgent task. Inner quartz glass assembly has a very thin indium (In) layer soldered the resonator and its silica base (case), but effects of internal resonances between operational modal pair of the shell-cup and its side (parasitic) modes can notable degrade the potential of the sensor as a whole, instead of so low level of resonator's intrinsic losses. Unfortunately, there are special combinations of dimensions of the parts (so-called, "resonant sizes"), when intensive losses of energy occurs. The authors proposed to use the length of stem's fixture as an additional design parameter to avoid such cases. So-called, a cyclic scheme of finite element method (FEM) and ANSYS software were employed to estimate different combinations of gyro assembly parameters. This variant has no mismatches of numerical origin due to FEM's discrete mesh. The optimum length and dangerous "resonant lengths" have been found. The special attention has been paid to analyses of 3D effects in a cup-stem transient zone, including determination of a difference between the positions of geometrical Pole of the resonant hemisphere and of its "dynamical Pole", i.e., its real zone of oscillation node. Boundary effects between the shell (cup) and 3D short "beams" (inner and outer stems) have been ranged. The results of the numerical experiments have been compared with the classic model of a quasi-hemispherical shell band with inextensional midsurface, and the solution using Rayleigh's functions of the $1^{st}$ and $2^{nd}$ kinds. To guarantee the truth of the recommended sizes to a designer of the real device, the analytical and FEM results have been compared with experimental data for a party of real resonators. The consistency of the results obtained by different means has been shown with errors less than 5%. The results notably differ from the data published earlier by different researchers.

• Korean Journal of Construction Engineering and Management
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• v.21 no.1
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• pp.12-20
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• 2020

To estimate collusion effects on bid award in Public Construction works, this paper uses Logit Model, which is a choice variable model. Price, design, competition, and other factors are included, with a special focus on collusion, as independent variables in the model. The empirical results are as follows. First, collusion has little effects on bid award, but great impacts on bidding behavior. Secondly, the score of design is the most important and significant factors among all variables. Thirdly, competition has also significant effects on bid award. Finally it is analyzed that institutional framework and characteristics of public work have some effects on bidding award.

• Journal of Environmental Health Sciences
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• v.35 no.3
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• pp.143-152
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• 2009

Indoor air quality at classrooms is of special concern since students are susceptible and indoor air problems can be so subtle that it does not always produce easily recognizable health effects. The main objectives of the study were to investigate the time-activity pattern of school students, to determine the sources of poor indoor air quality in schools, and to demonstrate how indoor air quality in schools causes adverse health effects such as headache, upper airway irritation, fatigue, and lethargy. Recent articles ranging from 1987-2009 related to school indoor air quality were systematically reviewed. Building-associated health effects can increase student absences from school and degrade the performance of children while in school. The reduced ventilation rate was associated with a decreased ability to concentrate along with increased adverse health symptoms. There was an association between residential proximity to busy roads and a variety of adverse respiratory health outcomes in children. Consequently, the current findings suggest the need for control strategy for school indoor air pollutants with multidisciplinary approach methods because Korea has no other natural resources except manpower especially.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2004.09a
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• pp.257-261
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• 2004

Recently, Pb free solder technologies are developed, and start using for many packaging items. But this technology contains many problems. They are very high re-flow temperature and high cost than normal solder paste. Specially, high re-flow temperature effects heavy damage to packaging and occur many crack to packaging. We developed special ACI (anisotropic conductive ink) that becomes substitution of solder paste. This technology cans adhesive lower temperature such as $120\~150^{\circ}C$. Adhesion time is very short, too. This technology is suitable for mass production.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.313-318
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• 2002

The use of carbon fiber rods is a promising technology of increasing flexural and shear strength of deficient reinforced concrete members. The purpose of this experimental study is to investigate the fatigue behavior and strengthening effects of the strengthened bridge deck with isotropic and othortropic carbon fiber rod. This study shows a fatigue loading, compliance and S-N Curve between strengthened isotropically and othortropically. Then estimate the effective fatigue behavior of RC slab using composite rods that are inserted in high special purposed polymer mortar.

• Journal of Korea Technology Innovation Society
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• v.1 no.2
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• pp.153-164
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• 1998

This study attempts to provide policy makers and other interested parties with policy implications throughout an economic analysis of software sector. Chapter 2 is designed to provide an overview of market characteristics in the software sector. Chapter 3 reviews an overview of the evolution stage of the software industry and the effects these trends have on firm strategies. Chapter 4 reviews the relationships between software economic characteristics and intellectual property rights. Some suggestions are offered in the conclusion, with special attention given to an examination of market characteristics, firm strategies, government policies, and some economic factors.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1361-1364
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• 2004

There is a need for fundamental understanding of biotribological characteristics of various biomaterials sliding against biological materials in order to develop a moving mechanism of medical microsystems having high energy efficiency. A special experimental equipment was designed and built to study the frictional behavior of various biomaterials sliding against a small intestine specimen of a pig. Friction experiments for six biomaterials were performed. Particularly, the effects of load and speed on frictional behavior were investigated. The results of this work will aid in the development of the actuator for a self-propelling micro-endoscope.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.973-978
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• 2002

This study was performed to verify the effect of various testing conditions affecting measured compressive strength of concrete core and to compute the correction coefficients for it. Conditions of specimens affecting test results include size(diameter), height-diameter ratio, humidity of specimen, amount and arrangement of bar, core direction from structure and method of end preparation. In testing core strength of concrete, special cares should be taken on various testing conditions whose effects have been latent in conventional concrete.