• Journal of Fisheries and Marine Sciences Education
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• v.17 no.3
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• pp.340-360
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• 2005

Fishery resource rents(i.e. windfall gains or excess profit), which tend to lead a variety of important economic, social, political problems, have been a fundamental cause of unbalance between fishery resource use and management. Thus, there may exist several sorts of optimal level of resource utilization such as economic maximum sustainable yield, biological maximum sustainable yield, social optimum production, socio-political optimum yield, etc. The fishery resource use level seems to a large extent to be determined by the characteristics of fishermen's rent seeking structure. As well known, fishery resources as common properties have a characteristic of being difficult to establish private property rights. Therefore, their use rights are controlled by the permit and/or the license system. As a result, absolute or differential rents are formed by the changes in institutional arrangements. Rent problems are often transformed into serious socio-political issues when the rent in a given industry is much higher to a socially unacceptable extent than the average of other industries. However, individual fishermen or fishermen's groups tend to behave aggressively to change the existing fishery institutions towards maximizing fishery rents. These rent-seeking behaviors often tend to nullify fishery management schemes. The larger is the relative rent difference between fisheries and other industries, the more aggressive tend to be the rent-seeking behaviors in fisheries.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.2
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• pp.67-73
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• 2016

When assessing crack initiation of fiber reinforced concrete, usually tensile strength or flexural strength is becomes indicator, but also depend on the curing effect take place during the production of specimen. In general, after conducting concrete specimen is cured by water at temperature $20{\pm}3^{\circ}C$ in laboratory, and accomplished the assessment of strength, but most of concrete structure is kept in drying condition after moist curing through the prescribed period. However, unlike these trends that technological advances have been made, influence of the difference of curing method on crack strength is not yet clear. Therefore, in this study, it is examined on the effect of curing methods affecting the mechanical property of fiber reinforced concrete, especially crack strength.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.11 s.104
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• pp.1262-1267
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• 2005

The paper presents the identification of dynamic property of a rotor system with a squeeze film damper (SFD) using magnetic fluid. An electromagnet Is installed in the inner damper of the SFD. The magnetic fluid is well known as a functional fluid. Its rheological property can be changed by controlling the applied current to the fluid and the fluid can be used as lubricant. Basically, the proposed SFD has the characteristics of a conventional SFD without an applied current, while the damping and stiffness Properties change according to the variation of the applied electric current. Therefore, when the applied current is changed, the whirling vibration of the rotor system can be effectively reduced. The clustering-based hybrid evolutionary algorithm (CHEA) is used to identify linear stiffness and damping coefficients of the SFD based on measured unbalance responses.

• Journal of Radiation Industry
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• v.5 no.4
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• pp.383-391
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• 2011

This study was conducted to investigate the applicability of gamma irradiation for improving the quality of paprika and Japanese apricot extract-treated nitrite free pork jerky. Pork jerky was gamma-irradiated at 0, 3, 5, 7 and 10 kGy and physiochemical properties such as proximate composition, 2-thiobarbituric acid (TBARS) values, color stability, texture, and sensory property were then evaluated. The results showed that the treatment of paprika and Japanese apricot extract to the pork jerky increased Hunter color value and texture property and at the same time decreased TBARS values. When gamma irradiated, natural pigment extract-treated pork jerky did not produce any change in its proximate composition (moisture, crude protein, crude lipid contents), and TBARS values. However, the redness (a-value) of pork jerky increased as the irradiation dose increased, whereas shear force of pork jerky was decreased. Sensory result showed that gamma irradiation induced to decrease the sensory scores. Therefore, these results suggest that gamma irradiation and the addition of paprika and Japanese apricot extracts could be an effective mean to improve color and texture of restructured pork jerky without use of nitrite.

• Geomechanics and Engineering
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• v.11 no.1
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• pp.161-175
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• 2016

A series of experimental studies are conducted on the deformation and shear strength property of compacted loess. The results reveal that the relationships of both the initial moisture content (w) and the initial degree of compaction (K) of compacted loess with cohesion (w) and the angle of internal friction (${\varphi}$) are linear. The relationship between the secant modulus ($E_{soi}$) and K is also linear. The relationship between $E_{soi}$ and w can be fitted well by a second-order polynomial. Further, when the influences of w and K are ignored, the relationship between the confined compression strain (${\varepsilon}$) and vertical pressure (p) can be expressed by a formula. A correction formula for the deformation of compacted loess caused by a change in w and K is derived on the basis of the study results.

• Korean Journal of Metals and Materials
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• v.47 no.3
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• pp.195-201
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• 2009

This paper is concerned with effects of Mn and heat-input on the mechanical properties of EGW welds. Four different kinds of welding consumables were fabricated by varying Mn contents such as 1.3, 1.5, 1.7, 2.0%Mn and each consumable was welded for EGW on four heat-input conditions between 190 and 340 KJ/Cm. Mn contents were decreased as heat-input increases and alloy elements (C, Si, Ti, B, Al) to deoxidize easily also revealed similar tendency to Mn. Their microstructure, Charpy impact property and strength were investigated, and it is found that Charpy impact property and strength exhibit a strong dependence on change of microstructure by Mn contents and heat-input. The increase of Mn contents or the decrease of heat-input made the microstructure fine and increase volume fraction of acicular ferrite, thereby leading to the great improvement of Charpy impact property and strength. In case of single EGW, optimum Mn contents are over 1.7% for the toughness and strength.

• Transactions of Materials Processing
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• v.32 no.2
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• pp.67-73
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• 2023

To overcome a climate change, manufacturing complex-shaped electric mobility parts becomes one of the important issues for enhancing a performance of motor with reducing their weight. Therefore, development of laser-based additive manufacturing shed on light due to their flexible manufacturing capacity that can be suitable to solve the poor formability of Fe-Si alloys for electric mobility parts. Although there are several studies existed to optimize the performance of additively manufactured Fe-Si alloys, the post-annealing effect was not well investigated yet though this is important to control the texture and mechanical properties of additively manufactured parts. In the present work, annealing effect on the mechanical property and microstructure of additively manufactured Fe-4.5Si alloy was investigated. Because of the ordered phase initiation after annealing, the hardness of additively manufactured Fe-4.5Si alloy increased up to 1173 K while a hardness drop occurs at the 1273 K condition due to the micro-crack initiation. The response surface methodology result represents the 1173 K-5 h sample is an optimal condition to maximize the mechanical property of additively manufactured alloy without micro-cracks.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.184-184
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• 2022

This study was aimed to evaluate the antioxidant activity and bioactive property of extracts from a purple-colored wheat variety 'Arriheuk' (Triticum aestivum L.) wheatgrass, affected by light emitting diode irradiation (LED). The wheatgrass was cultivated for 10 days after sowing in a growth chamber under the following LED conditions: R1B1 (Red:Blue = 1:1), R7B3 (Red:Blue = 7:3), and R3B7 (Red:Blue = 3:7). We examined antioxidant activity of the hot water extracts of wheatgrass using DPPH and ABTS free radicals scavenging assays. At the concentration of 10,000 ㎍/ml, the extract from R1B1 showed the highest DPPH free radical scavenging activity(79.29%), but its ABTS free radical scavenging activity was the lowest(32.0%). To evaluate bioactive property of the wheatgrass, we examined the change of natural killer (NK) cell activity affected by the wheatgrass extracts in vitro. At the concentration of 500㎍/ml, NK cell activity was most highly enhanced by the extract from R1B1(181.6%), and the activity was 176.1% (R7B3) and 144.6%(R3B7), respectively. These results suggest that the functional property of 'Arriheuk' wheatgrass would be enhanced by LED irradiation condition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.590-596
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• 2020

The fabric used for military winter inner clothing(top) is quilted with padded cotton to provide warmth. This quilting fabric is generally manufactured with yarns that intersect and are sewn substantially between the fabric and cotton. Thus, it is impossible to separate the fabric and cotton once after the quilting fabric is manufactured, which can result in a significant loss of fabric and cotton when separated. In this study, after fabricating the quilting fabric, we investigated a method to stabilize change rate of thickness and increase the warmth keeping property through subsequent processing without damaging the fabric. A relatively method of passing the quilting fabric through a part of the cotton production facility was used generally, and the following results were obtained. This indicates that after the quilting fabric was manufactured, the warmth keeping property was improved through the subsequent processing steps, so that the change rate of thickness due to washing was stabilized.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.16 no.1
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• pp.42-48
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• 2020

The effect of improving the tensile and J-R fracture toughness properties of SA508 Gr.1a on the LBB margin for the main steam pipe is investigated. The material properties and microstructure images of the existing main steam piping material SA106 Gr.C used in domestic nuclear power plants and the newly selected material SA508 Gr.1a were compared. For each material, LBB margins were calculated and compared through finite element analysis and crack instability evaluation. The LBB margin of the improved SA508 Gr.1a is found to be greatly improved compared to that of the existing SA106 Gr.C and SA508 Gr.1a. This is because of the increased material's strength and J-R fracture toughness compared to the previous materials. In order to analyze the effect of physical property change on the LBB margin, the sensitivity of each LBB margin according to the variation of tensile strength and J-R fracture toughness was analyzed. The effect of the change in tensile strength was found to be greater than that of the change in fracture toughness. Therefore, an increase in strength significantly influenced the improvement of the LBB margin of the improved SA508 Gr.1a.