• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.8
• /
• pp.734-739
• /
• 2008

In this study, the nonlinear mechanical behavior of flexible textile composites was predicted by two-step analyses: micromechanics and mesomechanics. The effective material properties for fiber tows of flexible textile composite lamina were calculated in micromechanics, which were then used to calculate the effective tensile stress-strain curve of flexible textile composites in mesomechanics. A user defined material algorithm was developed and inserted in ABAQUS to account for the geometric non-linearity due to the large rotation and shear deformation of fiber tows in mesomechanics. It was found that the stress-strain behavior of flexible textile composites exhibited significant non-linearity. The effective tensile modulus agreed well with the test result.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.5 no.1
• /
• pp.13-15
• /
• 2004

The current driven in an MOSFET is limited by the intrinsic channel resistance. All the other parasitic elements in a device structure play a significant role and degrade the device performance. These other resistances need to be less than 15％ of the channel resistance. To achieve the requirements, we should investigate the methodology of separation and quantification of those resistances. In this paper, we developed the extraction method of resistances using calibrated TCAD simulation. The resistance of the extension region is also partially determined by the formation of a surface accumulation region that forms under the gate in the tail region of the extension profile. This resistance is strongly affected by the abruptness of the extension profile because the steeper the profile is, the shorter this accumulation region will be.

• School Mathematics
• /
• v.11 no.4
• /
• pp.607-623
• /
• 2009

This study aims to investigate a child's informal knowledge of carrying and borrowing in additive calculations. The additive word problems including three types of calculations are posed a child that is the first grader and has no lessons about carrying and borrowing. By analysing his answers, his informal knowledge, that is his methods and strategies for calculating the additive problems are revealed. As a result, conceptual aspects and procedural aspects of his informal knowledge are recognized, and the didactical implications are induced for connecting his informal knowledge and the formal knowledge about carrying and borrowing.

• Journal of Internet Computing and Services
• /
• v.6 no.2
• /
• pp.85-97
• /
• 2005

At th first time in 1985, Tetris appeared, it became game that are loved to many users until now. Existent Tetris employed way to give score according to number of that is destroyed whenever line are destroyed, and give advantage about serial attack and so on, But, these score calculation method gave so fixed and simple pattern. In this paper, We design and implement the new tetris game System by score calculation method per level that Is different with existent method. That Is, this method is to compare present and before with number of destroyed line and give advantage in basis score, Also, It is going to permit strategic utilization of still more developed tetris than existent tetris using score calculation method per level.

• Education of Primary School Mathematics
• /
• v.19 no.3
• /
• pp.223-247
• /
• 2016

Given the importance of developing algebraic thinking from early grades, this study investigated an overall performance and main characteristics of algebraic thinking from a total of 197 third grade students. The national elementary mathematics curriculum in Korea does not emphasize directly essential elements of algebraic thinking but indicates indirectly some of them. This study compared our students' performance related to algebraic thinking with results of Blanton et al. (2015) which reported considerable progress of algebraic thinking by emphasizing it through a regular curriculum. The results of this study showed that Korean students solved many items correctly as compatible to Blanton et al. (2015). However, our students tended to use 'computational' strategies rather than 'structural' ones in the process of solving items related to equation. When it comes to making algebraic expressions, they tended to assign a particular value to the unknown quantity followed by the equal sign. This paper is expected to explore the algebraic thinking by elementary school students and to provide implications of how to promote students' algebraic thinking.

• The KIPS Transactions:PartC
• /
• v.12C no.4 s.100
• /
• pp.559-570
• /
• 2005

ECN is accurate in determining traffic congestion since it explicitly notifies the incipient congestion. Therefore, ECN method has been thoroughly studied in the field of wireless TCP. This paper introduces a formula to find the optimal threshold for ECN marking. We have implemented a Petri net model of 'TCP with ECN strategy' and performed simulations on it in order to verify the validity of the formula. We have also introduced ideas of applying the formula in practice. The primary contribution of this paper is proposing a formula to find the optimal threshold for ECN marking. However, introducing the Petri net model of 'TCP with ECN strategy' is no less valuable contribution because it can be helpfully used by the researchers in studying network protocols. We have built the Petri net model by modifying the existing Petri net model of TCP. In order to add ECN strategy to the existing model, we have mainly modified the network part. We have also modified sender part and receiver part as well.

• Journal of Internet Computing and Services
• /
• v.21 no.1
• /
• pp.221-230
• /
• 2020

The effects-based operation, which would reduce unnecessary efforts and meaningless sacrifices incurred during a war and simultaneously reach the will of the enemy leadership by strategic attacks, was discarded for the reason that it was difficult to apply it to military power except for airpower. However, cyberspace, which can be thoroughly logical and calculated, can be suitable for conducting effects-based operations. This study examined a way to carry out effects-based operations in such cyberspaces. It laid the foundation for overcoming the limitations of effects-based operations revealed in previous battle cases and executing the operations in cyber battlespace where the boundary between physical and cyberspaces gradually disappeared. Futhermore, it demonstrated that effects-based operations could be carried out in cyberspace by establishing a military strategy, which could conduct the operations through an analysis of previous cyber-attack cases.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.37 no.5
• /
• pp.879-890
• /
• 2017

The US Pavement Design method (AASHTO) and HDM-4, a road pavement maintenance decision system, are not suitable for domestic pavement design, construction and maintenance. KPRP(Korea Pavement Research Program) has been developed to reflect Korea's environmental conditions and vehicle characteristics, thereby, extending pavement life. The main objective of this study is to select the best alternative through Life Cycle Cost $CO_2$ (LCCC) calculations among three representative maintenance strategies using KPRP design software since the environment cost resulting from the extended pavement life will also differ. The analysis of this study illustrates that cumulative carbon emissions for 40 years in alternative 2 (Cutting and Overlaying at Year 30) is the lowest option among them, and the basic cost of $CO_2$ emission by various road maintenance and repair work can be used for suggesting an optimal maintenance strategy for highway agency.

• Journal of Navigation and Port Research
• /
• v.36 no.5
• /
• pp.387-394
• /
• 2012

In an automated container terminal, automated stacking cranes(ASCs) take charge of handling of containers in a block of the stacking yard. This paper proposes a multi-criteria strategy to solve the problem of job dispatching of twin ASCs which are identical to each another in size and specification. To consider terminal situation from different angles, the proposed method evaluates candidate jobs through various factors and it dispatches the best score job to a crane by doing a weighted sum of the evaluated values. In this paper, we derive the criteria for job dispatching strategy, and we propose a genetic algorithm to optimize weights for aggregating evaluated results. Experimental results are shown that it is suitable for real time terminal with lower computational cost and the strategy using various criteria improves the efficiency of the container terminal.

• The Journal of the Acoustical Society of Korea
• /
• v.29 no.4
• /
• pp.258-264
• /
• 2010

In this paper, we propose an objective quality feature which is based on the human auditory system to measure vacuum cleaner noise. It is observed that some frequency bands are more sensitive to the human auditory system. Therefore, we divided the audible frequency range of vacuum cleaner noise into a number of frequency bands and the average energy of these bands was calculated. Among a number of average energies, an average energy of a frequency band was selected as the proposed feature. In order to test the performance of the proposed feature, fourteen vacuum cleaners were chosen and the noise was recorded in an anechoic-chamber. Then we performed subjective tests to obtain subjective scores of the noise data using the PCM (paired comparison method) and ACR (absolute category rating) subjective methods. The proposed objective quality feature shows high correlation with the subjective scores.