• Journal of the Korean Mathematical Society
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• v.45 no.2
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• pp.377-392
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• 2008

Let X be a real reflexive Banach space with a uniformly $G\hat{a}teaux$ differentiable norm, C a nonempty closed convex subset of X, T : C $\rightarrow$ X a continuous pseudocontractive mapping, and A : C $\rightarrow$ C a continuous strongly pseudocontractive mapping. We show the existence of a path ${x_t}$ satisfying $x_t=tAx_t+(1- t)Tx_t$, t $\in$ (0,1) and prove that ${x_t}$ converges strongly to a fixed point of T, which solves the variational inequality involving the mapping A. As an application, we give strong convergence of the path ${x_t}$ defined by $x_t=tAx_t+(1-t)(2I-T)x_t$ to a fixed point of firmly pseudocontractive mapping T.

• Journal of KIISE:Computer Systems and Theory
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• v.37 no.4
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• pp.215-225
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• 2010

The NAND flash memory based SSDs are considered to replace the existing HDDs. To maximize the I/O performance, SSD is composed of several NAND flash memories in parallel. However, to adopt the hybrid mapping scheme in SSD may cause degradation of the I/O performance. In this paper, we propose a new mapping scheme for the SSD called WADPM. WADPM loads only necessary mapping information into RAM and dynamically adjusts the size of mapping information in the RAM. So, WADPM avoids the shortcoming of page-level mapping scheme that requires too large mapping table. Performance evaluation using simulations shows that I/O performance of WADPM is 3.5 times better than the hybrid-mapping scheme and maximum size of mapping table of WADPM is about 50% in comparison with the page-level mapping scheme.

• Journal of The Korean Association For Science Education
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• v.28 no.4
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• pp.340-349
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• 2008

This study investigated the mapping errors induced in learning the concept of reaction rate with analogies, and compared these mapping errors by the analogy presentation types. Tenth graders (N=418) at a high school were assigned to the four groups by the target concepts and the analogy presentation types. The target concepts were 'concentration and reaction rate' and 'temperature and reaction rate'. In presenting analogy, the verbal and the verbal/pictorial analogs were used. After the students learned one of the analogs, a mapping test was administered. From the analysis, eight types of mapping errors were identified: overmapping, artificial mapping, failure to map, rash mapping, mismapping, mapping of a superficial feature, retention of a base feature, and impossible mapping. According to the analogy presentation types and the features of the target concepts, there were some differences in the frequencies of mapping errors. Educational implications of these findings are discussed.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.12
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• pp.918-922
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• 2009

Naturally, block mapping FTL works well for sequential writes while page mapping FTL does well for random writes. To exploit their advantages, a practical FTL should be able to selectively apply a suitable scheme between page and block mappings for each write pattern. To meet that requirement, we propose a hybrid mapping FTL, which we call Janus-FTL, that distributes data to either block or page mapping areas. Also, we propose the fusion operation to relocate the data from block mapping area to page mapping area and the defusion operation to relocate the data from page mapping area to block mapping area. And experimental results of Janus-FTL show performance improvement of maximum 50% than other hybrid mapping FTLs.

• The KIPS Transactions:PartD
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• v.17D no.6
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• pp.383-394
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• 2010

Flash memory based SSDs are currently being considered as a promising candidate for replacing hard disks due to several superior features such as shorter access time, lower power consumption and better shock resistance. However, SSDs have different characteristics from hard disk such as difference of unit and time for read, write and erase operation and impossibility for over-writing. Because of these reasons, SSDs have disadvantages on hard disk based systems, so FTL(Flash Translation Layer) is designed to increase SSDs' efficiency. In this paper, we propose an advanced logical address mapping method for increasing SSDs' performance, which is named HAMM(Hybrid Address Mapping Method). HAMM addresses drawbacks of previous block-mapping method and super-block-mapping method and takes advantages of them. We experimented our method on our own SSDs simulator. In the experiments, we confirmed that HAMM uses storage area more efficiently than super-block-mapping method, given the same buffer size. In addition, HAMM used smaller memory than block-mapping method to construct mapping table, demonstrating almost same performance.

• Journal of The Korean Association For Science Education
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• v.15 no.2
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• pp.223-232
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• 1995

The purpose of this study is to investigate the effect of concept mapping strategies on the learner's achievement and their attitude change in science learning. The subject was 159 male students in a middle school in Seoul. Three experimental groups were instructed with different kinds of teaching methods about the unit of photosynthesis and digestive organs. Group I was instructed with traditional teaching method, GroupII was instructed with guided concept mapping strategy, GroupIII was instructed with student-centered concept mapping strategy. The major findings of this study are as follows. 1. Student-centered concept mapping strategy was observed effective at 0.05 significance level in achievement and retention. 2. Only student-centered concept mapping strategy changed students' attitude toward science learning positively. 3. It was observed that there was very significant correlation between the learning ability and science achievement (p<0.01). 4. Student-centered concept mapping strategy was found effective in upper learning-ability group, and guided concept mapping strategy in middle learning-ability group(p < 0.05). 5. Student-centered concept mapping strategy was effective to the groups of upper and middle learning-ability in changing students' attitude toward science learning(p < 0.05).

• Progress in Superconductivity and Cryogenics
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• v.17 no.2
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• pp.31-35
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• 2015

Mapping is a useful tool in the magnetic field analysis and design. In some specific research area, such as the nuclear magnetic resonance (NMR) or the magnetic resonance imaging (MRI), it is important to map the magnetic field in the interesting space with high accuracy. In this paper, an indirect mapping method in the center volume of an air-core solenoid is presented, based on the solution of the Laplace's equation for the field. Through the mathematical analysis on the mapping calculation, we know that the condition number of the matrix, generated by the measurement points, can greatly affect the error of mapping result. Two different arrangement methods of the measurement points in field mapping are described in this paper: helical cylindrical line (HCL) method and parallel cylindrical line (PCL) method. According to the condition number, the HCL method is recommended to measure the field components using one probe. As a simple example, we mapped the magnetic fields in a MRI main magnet system. Comparing the results in the different methods, it is feasible and convenient to apply the condition number to reduce the error in the field mapping calculation. Finally, some guidelines were presented for the magnetic field mapping in the center volume of the air-core solenoid.

• Journal of the Korea Society of Computer and Information
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• v.22 no.7
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• pp.1-7
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• 2017

As the capacity of NAND flash module increases, the amount of RAM increases for caching and maintaining the FTL mapping information. In order to reduce the amount of mapping information managed in the RAM, a demand-based address mapping method stores the entire mapping information in the flash and some valid mapping information in the form of cache in the RAM so that the RAM can be used efficiently. However, when cache miss occurs, it is necessary to read the mapping information recorded in the flash, so overhead occurs to translate the address. If the RAM space is not enough, the cache hit ratio decreases, resulting in greater overhead. In this paper, we propose a method using two tables called TPMT(Translation Page Mapping Table) and SMT(Segmented Translation Page Mapping Table) to utilize both temporal locality and spatial locality more efficiently. A performance evaluation shows that this method can improve the cache hit ratio by up to 30% and reduces the extra translation operations by up to 72%, compared to the TPM scheme.

• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.150-157
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• 2010

In this study, we investigated the differences of mapping understanding and the types of mapping errors by the levels of students' cognitive/affective variables and the relationships between mapping understanding and these variables in learning 'concentration and reaction rate' with analogy. After administering the tests regarding logical thinking ability, visual imagery ability, analogical reasoning ability, self efficacy, and need for cognition as pretests, students learned with analogy. Then, students' familiarity and mapping understanding were examined. Analyses of the results revealed that the scores of the mapping understanding for the students with higher levels of all cognitive/affective variables except visual imagery ability and familiarity were significantly higher than those for the students with lower levels. The differences in the types of the mapping errors such as overmapping, failure to map, impossible mapping, artificial mapping, mismapping, rash mapping, and retention of a base feature were also found by the levels of students' cognitive and affective variables. The scores of students' mapping understanding were positively correlated with those of all cognitive and affective variables. The results of multiple regression analysis indicated that students' science achievement, logical thinking ability, and familiarity were significant predictors of mapping understanding. Educational implications of these findings are discussed.

• Journal of KIISE:Software and Applications
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• v.33 no.1
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• pp.114-129
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• 2006

Ontology mapping is the task of finding semantic correspondences between two ontologies. In order to improve the effectiveness of ontology mapping, we need to consider the characteristics and constraints of data models used for implementing ontologies. Earlier research on ontology mapping, however, has proven to be inefficient because the approach should transform input ontologies into graphs and take into account all the nodes and edges of the graphs, which ended up requiring a great amount of processing time. In this paper, we propose a multi-strategic mapping approach to find correspondences between ontologies based on the syntactic or semantic characteristics and constraints of the topic maps. Our multi-strategic mapping approach includes a topic name-based mapping, a topic property-based mapping, a hierarchy-based mapping, and an association-based mapping approach. And it also uses a hybrid method in which a combined similarity is derived from the results of individual mapping approaches. In addition, we don't need to generate a cross-pair of all topics from the ontologies because unmatched pairs of topics can be removed by characteristics and constraints of the topic maps. For our experiments, we used oriental philosophy ontologies, western philosophy ontologies, Yahoo western philosophy dictionary, and Yahoo german literature dictionary as input ontologies. Our experiments show that the automatically generated mapping results conform to the outputs generated manually by domain experts, which is very promising for further work.