• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.1
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• pp.35-42
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• 2007

This paper develops a Sustainable Regional Economic Growth Model (SREG) which estimates the relation of labor population change and employment increase in each occupation and maximum limits and minimum requirements of employment increase by labor population change in a specified region using multiplier theory. To develop the proposed model, sustainable regional economic growth is defined as a steady increase of labor population over a long term period and the limit of employment increase is defined as the estimated labor population change in the region with no need for commutation from the surrounded areas. Developed model was applied to 67 county in Pennsylvania State and the results revealed that the investment in infrastructure occupations, such as transportation, warehousing, utilities, information, communication, and other public utilities, maximizes the effects for increasing employment, whereas finance, insurance, and real estate occupations have minimum effects for increasing employment. Calculated minimum requirements of occupations show that infra-structure occupations is a critical factor for labor population change and maximum limits of occupations show that agriculture and finance occupations are difficult to increase independently.

• Journal of the Korean Ceramic Society
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• v.27 no.8
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• pp.979-990
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• 1990

The possible use of bioglass as implant materials is due to its biocompatibility to human body. Even if many animal studies for the bioglasses have been performed, their structures and physical properties are not fully understood. In the present work, several investigations such as Raman spectroscopic analysis, density, thermal expansion coefficient, softening temperature, and refractive index measurement were carried out to find the structures and physical properties of bioglasses, where MgO is substituted for CaO in bioglass composition (46.1%SiO2, 24.4%Na2O, 26.9%CaO, 2.6%P2O5 ; mole%). Hydroxyapatite formation on the glass surface reacted in Tris-buffer solution was also examined. When CaO was replaced by MgO, nonbridging oxygen in glass structuer was diminished but the degree of disorder increased. Thermal expansion and softening properties showed the mixed oxide effect. Hydroxyapatite were formed on the surface of 0~11mole% of MgO containing bioglasses, and the thickness of SiO2-rich layer as well as hydroxyapatite layer were unchanged with MgO content. However, the hydroxyapatite was not formed on the surface of the bioglasses containing over 11 mole percent MgO, even if the glasses were reacted for long period.

• Journal of the Korean Ceramic Society
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• v.44 no.6 s.301
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• pp.308-312
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• 2007

Ferroelectric, magnetic, and magnetoelectric effects for lanthanum modified $BiFeO_3-PbTiO_3$ ceramics have been investigated. The data show that magnetoelectric polarization coefficient, ${\alpha}_p$ is due to a linear coupling between polarization and magnetization, and that ${\alpha}_p$ is independent of dc magnetic bias and ac magnetic field. The values of ${\alpha}_p$ and magnetic induced susceptibility for lanthanum modified $BiFeO_3-PbTiO_3$ ceramics are much larger than those of single $BiFeO_3$ crystal. We believe that the magnetoelectric effect is significantly enhanced by breaking of the cycloidal spin state of a long-period spiral spin structure due to randomly distributed charged imperfections.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.333-339
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• 2003

Recently, the bridges become greater according to development of a construction technology. This phenomenon requires long span bridge, so that increases the dead weight. The orthotropic steel deck bridges have much advantages such as the light dead weight and the reduction of construction period. And almost whole process of carried out is manufactured at factory, so it can cause the increase of quality authoritativeness. But orthotropic steel deck bridge is consist of structure by welding, it can not avoid a lot of welding jobs, defects and transformation by welding are becoming problem accordingly. Specially, topical stress concentration phenomenon in cross connection area of longitudinal and transverse rib causes fatigue failure. The Bulkhead Plate for prevention of this stress concentration phenomenon was applied by changing the orthotropic steel deck of Williamsburg bridge in USA. But, it is principle that a Bulkhead Plate is not established in the domestic design standard. Therefore, it is estimated that the study for installation of Bulkhead Plate is needed. This treatise with considering these circumstances proves efficiency of Bulkhead Plate and will be presented optimal design details through finite element analysis according to change the geometrical of Bulkhead Plate and tile cross-connection area of longitudinal and transverse rib.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.5
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• pp.1417-1434
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• 2016

Starting from the February 2008 till the end of November 2014, abundance of phytoplankton and their composition living in the coastal waters of Kyoungju city were investigated. Environmental and biological properties were also observed at 10 different stations on a seasonal basis. Due to the environmental variables, fluctuating pattern was appeared during the entire period of observation with different degree, as compared to those found in other costal waters in the East Sea. The concentration of phosphate was turned out to be very low which was even less than threshold level in the study area. Phytoplankton community structure was dominated by diatoms (both micro- and nanoplankton fractions) for several years and seasonal succession was also relied on the diatoms. The importance of dinoflagellates in the community was relatively low. Abundance of phytoplankton was heavily affected by physical factors in the surface water, however, affected more by chemical factors including nutrients in the deep water. For periods of this study, the phosphate concentrations was observed in an extremely low, which indicates that the main limiting factor affecting phytoplankton growth could be phosphate.

• International Journal of High-Rise Buildings
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• v.2 no.2
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• pp.131-139
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• 2013

The field of structural fire engineering has evolved within the construction industry, driven largely by the acceptance of performance-based or goal-based design. This evolution has brought two disciplines very close together - that of structural engineering and fire engineering. This paper presents an overview of structural systems that are frequently adopted in tall building design; typical beams and columns, concrete filled steel tube columns and long span beams with web openings. It is shown that these structural members require a structural analysis in relation to their temperature evolution and failure modes to determine adequate thermal protection for a given fire resistance period. When this is accounted for, a more explicit understanding of the behaviour of the structure and significant cost savings can be achieved. This paper demonstrates the importance of structural fire assessments in the context of tall building design. It is shown that structural engineers are more than capable of assessing structural capacity in the event of fire using published methodologies. Rather than assumed performance, this approach can result in a safe and quantified design in the event of a fire.

• Management & Information Systems Review
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• v.7
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• pp.227-245
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• 2001

The object that we have researched the design for a long life of product is to search for the method to cope with the various environment problems where our mankind is confronting in the field of Production Design. The environment problem on earth is affecting seriously the enterprise which produces the product, the user who consumes it and even the field of product design. Now we live our daily life with a lot of artifacts while the citification and modernization have been progressing around us. Especially, 20 century was the times of the highly advanced scientific civilization and industrialization. Therefore it affected decisively our life environment base nowadays. The result was that our human life became rich because of the advanced development of industry, productivity and distribution structure. On the other side, the industrial system in the period of these massive production and massive consuming is bearing various problems proportionally. Those are the depletion of resources and energy, earth environmental pollution and various kinds of waste. In addition, the material which cannot recycle is appearing at the large quantity. This is the actuality of now. Our subject is how product design will cope with it as counter measures and the subject is very important to our mankind and earth environment.

• Geotechnical Engineering
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• v.8 no.3
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• pp.75-88
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• 1992

In this study the foundation methods which our ancestors, through a historical age as early as three kingdom's period, adopted for their civil structures and buildings have been reviewed by investigating the discovered relics. It is shown that they already, from about 2000 years ago, had applied various foundation techniques considering the structure types and the foundation soil conditions. The ancient foundation methods are categorized as artificially laid alternating soil and boulder layers under heavy structures, compacted soil base under wide loaded area, stone column under pillars of buildings, stacked long stone footing for special buildings such as palace buildings, and piling for bridges, They are analyzed with respect to current foundation techniques.

• Journal of the Korean Society of Safety
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• v.27 no.6
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• pp.59-63
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• 2012

The use of dry chemical powder has been increased as it can be stored for a long period and sustain in stable condition compared to gas or liquid phase extinguishing agents. A new type of dry chemical powder using Zeolite was produced in the research. Chemical powder was adsorbed into Zeolite 13X, a porous material appearing negative catalytic effect, to create extinguishing powder obtaining core shell structure and measured physical properties and run a small scale fire extinguishment. SEM, XRD, TA analysis was also executed, and extinguishing characteristics were measured by fire extinguishing experiment on oil pool fire. The experiment showed that the average particle size of Zeolite 13X was equivalent, indicating about $3{\pm}1{\mu}m$ and thermal analysis result illustrated that Zeolite 13X showed exothermic reaction peaks at $900^{\circ}C$ due to solid-state transformation. Extinguishing characteristics on oil fire of $NaHCO_3$/Zeolite 13X and $NH_4H_2PO_4$/Zeolite were improved, influenced by adsorbed extinguishing powders on Zeolite 13X and Zeolite 13X that contains high phase transition temperature.

• Biomaterials and Biomechanics in Bioengineering
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• v.2 no.2
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• pp.85-96
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• 2015

This study developed biodegradable bi-layered drug-eluting beads and investigated the in-vitro release of fluorouracil and cisplatin from the beads. To manufacture the drug-eluting beads, poly[(d,l)-lactide-co-glycolide] (PLGA) with lactide:glycolide ratios of 50:50 and 75:25 were mixed with fluorouracil or cisplatin. The mixture was compressed and sintered at $55^{\circ}C$ to form bi-layered beads. An elution method was employed to characterize the release characteristic of the pharmaceuticals over a 30-day period at $37^{\circ}C$. The influence of polymer type (i.e., 50:50 or 75:25 PLGA) and layer layout on the release characteristics was investigated. The experiment suggested that biodegradable beads released high concentrations of fluorouracil and cisplatin for more than 30 days. The 75:25 PLGA released the pharmaceuticals at a slower rate than the 50:50 PLGA. In addition, the bi-layered structure reduced the release rate of drugs from the core layer of the beads. By adopting the compression sintering technique, we will be able to manufacture biodegradable beads for long-term drug delivery of various anti-cancer pharmaceuticals.