• KDI Journal of Economic Policy
• /
• v.41 no.4
• /
• pp.67-99
• /
• 2019

This paper, focusing on the renewable portfolio standard (RPS), evaluates alternative renewable energy policies. We propose a tractable equilibrium model which provides a structural representation of Korea's electricity market, including its energy settlement system and renewable energy certificate (REC) transactions. Arbitrage conditions are used to define the core value of REC prices to identify relevant competitive equilibrium conditions. The model considers R&D investments and learning effects that may affect the development of renewable energy technologies. The model is parameterized to represent the baseline scenario under the currently scheduled RPS reinforcement for a 20% share of renewable generation, and then simulated for alternative scenarios. The result shows that the reinforcement of the RPS leads to higher welfare compared to weakening it as well as repealing it, though there remains room to enhance welfare. It turns out that subsidies are welfare-inferior to the RPS due to financial burdens and that reducing nuclear power generation from the baseline yields lower welfare by worsening environmental externalities.

• Asian-Australasian Journal of Animal Sciences
• /
• v.15 no.1
• /
• pp.111-116
• /
• 2002

This study investigated quantitative changes in the spaces between and within myofibrils and the impact of high and low voltage electrical stimulation on muscle ultrastructure as seen in electron micrographs. In addition, the relationships of these spaces and the impact to meat tenderness were investigated. The degradation of myofibrils during aging appeared to be localized across the muscle fibre. Structural deterioration of muscle fibres was evident 1 day post-mortem, involving the weakening in the lateral integrity of the myofibrils and Z-disc regions. Meat tenderisation, as shown by objective measurements, coincided with these increases in degradation, as assessed by the sum of the gaps between and within myofibrils. The results showed that the total size of gaps between and within myofibrils can be used as an indicator of meat tenderization during aging, but that ultrastructural alteration in electrically stimulated muscle had little relationship with meat tenderness.

• Journal of Auto-vehicle Safety Association
• /
• v.6 no.2
• /
• pp.36-42
• /
• 2014

In order to prevent the sharp edge during the side impact, a cause analysis and CAE based risk prediction were carried out in this study. It was found that sharp edge occurs mainly because of stiffness difference between the major parts and structural stress concentration. It could be improved by directly reinforcing the crack initiation region or by weakening the joints connecting the parts. The fracture criterion based on major in-plain strain was suggested and the risk prediction process for sharp edge prevention was established.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.05a
• /
• pp.88-93
• /
• 2003

This paper presents an efficient dynamic modeling method for open cracked rotor-bearing systems. An equivalent bending spring model is introduced to represent the structural weakening effect in the presence of cracks. The proposed modeling method is validated through a series of simulations and experiments. First, the proposed method is rigorously compared with a commercial finite element code. Then, an experiment is performed to validate the proposed modeling method. Finally, a numerical example is introduced to demonstrate the possible application of the proposed method in the crack diagnosis fur rotor systems.

• Earthquakes and Structures
• /
• v.16 no.4
• /
• pp.375-389
• /
• 2019

During earthquakes, the performance of structures needs to be evaluated, which provides guidance for selecting suitable retrofitting schemes. The purpose of this paper is to accomplish seismic assessment of a simple steel residential building. Once the responses of the system are determined, the scope of the study extends to evaluate selected retrofitting strategies that are intended to rehabilitate the flaws of the structure under prescribed ground motions with high probability of occurrence at the site. After implementing the retrofits, seismic assessment of the upgraded structure is carried out to check if the remediation at various seismic performance levels is acquired or not. Outcomes obtained from retrofitted scenarios are compared to the results obtained from the initial un-retrofitted configuration of the structure. This paper presents the process for optimal selection of rehabilitation solutions considering the cost of implementation, downtime and disruption to property owners while improving the seismic performance level of the structure.

• Bulletin of the Korean Chemical Society
• /
• v.17 no.2
• /
• pp.168-172
• /
• 1996

The variations of the structural detail of layered perovskite-type oxides, Na2Ln2Ti3O10 (Ln=La, Nd, Sm, Gd), have been refined by Rietveld analyses of their powder X-ray diffraction data. Although the c-axis strongly decreases from Ln=La to Nd, Sm, or Gd, the length of Na-O bond along the c-axis that is regarded as the sodium layer spacing is not dependent on the unit cell parameter. Such a behavior is explained by the fact that Na-O bond is in competition with Ti-O one of the perovskite slab. Increased covalency of this Ti-O bond by the lattice contraction leads to weakening of the attaching strength of Na ion. This picture is consistent with the experimental observation that Na ion conductivity of Na2Ln2Ti3O10 increases from Ln=La to Nd, Sm, or Gd despite strong contraction of the unit cell volume.

• Tunnel and Underground Space
• /
• v.30 no.2
• /
• pp.109-135
• /
• 2020

Globally, the deepening depth in the underground is a situation of the high interest for a purpose of the development of various facilities. The development of deep underground space should be based on the structural stability of rocks. Spalling is known to have an impact on the structural stability degradation in deep underground space. As an attempt to predict spalling, many researchers have proposed predicted conditions in accordance with stress states which occur around the tunnel, rock conditions, and types of rock. In addition, the analysis on spalling method has been verified by using computer modeling such as FLAC, EXAMINE, Insight 2D, UDEC and FRACOD, along with in-situ measurement results. In Canada URL (Underground Research Tunnel), CWFS model (Cohesion Weakening Frictional Strengthening) was used to precisely predict for the state of spalling, comparing spalling modeling. CWFS model has been identified as a reliable method for predicting such phenomena. This study aims to analyze several cases of spalling, and then make a comparison between the conditions for spalling occurrence and the predicted results of model CWFS. With this, it investigates the applicability of prediction of spalling, targeting pillar under deep depth condition.

• The Journal of Korean Association of Computer Education
• /
• v.14 no.1
• /
• pp.23-33
• /
• 2011

The purpose of the study is to investigate the structural relations between variables which give influences on cyber-violence. On the basis of literal materials, those variables as self-control ability, social identity, and norm consciousness are selected as the variables of having influences on cyber-violence, and the analysis is focused on the influence that anonymity, the representative characteristic of Internet, gives them. The validation of the Model is to be done through AMOS 6.0, and the degree of Model validity is to be estimated through the values of ${\chi}^2$, RMSEA, CFI, NNFI. As the result of the analysis, it is found that social identity and norm consciousness are direct causes of cyber-violence. Anonymity does not have any direct relations with it, but it indirectly gives influences on cyber-violence, for it gives some influences on social identity and norm consciousness. That is, anonymity is a cause of weakening social identity and degrading norm consciousness, by which, it is assumed, cyber-violence is triggered.

• The Korean Journal of Food And Nutrition
• /
• v.21 no.4
• /
• pp.518-523
• /
• 2008

Experiments were conducted to assess the quality properties of steamed fish paste by addition level, along with a fish meat replacement(dried bovine plasma). The moisture, crude protein, crude fat and ash contents evidenced partially significant difference among the controls, DBP1, DBP2 and DBP3 groups(p<0.05). The pH values of the steamed samples were higher than those of the non-steamed samples, and when the content of the dried bovine plasma as meat replacement agent was increased, the pH was increased. The water holding capacity of the steamed fish past samples, along with the replacement levels were significantly higher than in the samples without the meat replacer(p<0.05). The range of cooking loss was $5.19{\sim}5.38%$. Structural weakening of the boiled samples was significantly higher than that observed in the fried sample. Hardness and chewiness were increased slightly by the addition of bovine plasma, but gel strength evidenced a pattern of decreased in DBP1, DBP2 and DBP3 groups. The result of our sensory evaluation on taste, texture, color and overall acceptance evidenced significant differences among the controls, DBP1, DBP2 and DBP3 groups, and the sensory score of color was the highest.

• Structural Engineering and Mechanics
• /
• v.14 no.1
• /
• pp.99-118
• /
• 2002

The scaled-boundary finite element method is a novel semi-analytical technique, combining the advantages of the finite element and the boundary element methods with unique properties of its own. The method works by weakening the governing differential equations in one coordinate direction through the introduction of shape functions, then solving the weakened equations analytically in the other (radial) coordinate direction. These coordinate directions are defined by the geometry of the domain and a scaling centre. This paper presents a general development of the scaled boundary finite-element method for two-dimensional problems where two boundaries of the solution domain are similar. Unlike three-dimensional and axisymmetric problems of the same type, the use of logarithmic solutions of the weakened differential equations is found to be necessary. The accuracy and efficiency of the procedure is demonstrated through two examples. The first of these examples uses the standard finite element method to provide a comparable solution, while the second combines both solution techniques in a single analysis. One significant application of the new technique is the generation of transition super-elements requiring few degrees of freedom that can connect two regions of vastly different levels of discretisation.