• Journal of KIISE:Computer Systems and Theory
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• v.31 no.1_2
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• pp.125-134
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• 2004

Recently, an on-chip compressed cache system was presented to alleviate the processor-memory Performance gap by reducing on-chip cache miss rate and expanding memory bandwidth. This research Presents an extended on-chip compressed cache system which also significantly expands main memory capacity. Several techniques are attempted to expand main memory capacity, on-chip cache capacity, and memory bandwidth as well as reduce decompression time and metadata size. To evaluate the performance of our proposed system over existing systems, we use execution-driven simulation method by modifying a superscalar microprocessor simulator. Our experimental methodology has higher accuracy than previous trace-driven simulation method. The simulation results show that our proposed system reduces execution time by 4-23% compared with conventional memory system without considering the benefits obtained from main memory expansion. The expansion rates of data and code areas of main memory are 57-120% and 27-36%, respectively.

• Journal of the Korea Computer Industry Society
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• v.5 no.1
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• pp.131-146
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• 2004

As Electronic Commerce(EC) has been emerged and has developed, many researchers have tried to establish EC framework for automated contract and negotiation using agent technologies. Traditional researches, however, often had limitations. They often enforced the user's participations during the automated contract process of agents. They also could only consider a few of the user's requirements for a specific goods and did not have supported the procedures and methodologies for making the best contract. In this paper, we propose business model on EC based on multiagents to overcome the defects of the previous researches. We apply CSP techniques to brokerage process to satisfy various preferential requirements from the user. We also propose efficient negotiation mechanism using negotiation model of game theory. The contract candidates automatically negotiate and mediate in terms of their benefits through the proposed negotiation mechanism. For the optimal brokerage and automated negotiation, the agents process activities for contract on three layers, which are called competition layer, constraint satisfaction layer and negotiation layer in the proposed model. We also design the message driven communication protocol to support the automated contract among the agents. Finally, we have implemented prototype systems applying the proposed model and have shown the various experimental results for efficiency of the proposed model.

• Journal of Intelligence and Information Systems
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• v.10 no.1
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• pp.109-123
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• 2004

Corporate financial distress and bankruptcy prediction is one of the major application areas of artificial neural networks (ANNs) in finance and management. ANNs have showed high prediction performance in this area, but sometimes are confronted with inconsistent and unpredictable performance for noisy data. In addition, it may not be possible to train ANN or the training task cannot be effectively carried out without data reduction when the amount of data is so large because training the large data set needs much processing time and additional costs of collecting data. Instance selection is one of popular methods for dimensionality reduction and is directly related to data reduction. Although some researchers have addressed the need for instance selection in instance-based learning algorithms, there is little research on instance selection for ANN. This study proposes a genetic algorithm (GA) approach to instance selection in ANN for bankruptcy prediction. In this study, we use ANN supported by the GA to optimize the connection weights between layers and select relevant instances. It is expected that the globally evolved weights mitigate the well-known limitations of gradient descent algorithm of backpropagation algorithm. In addition, genetically selected instances will shorten the learning time and enhance prediction performance. This study will compare the proposed model with other major data mining techniques. Experimental results show that the GA approach is a promising method for instance selection in ANN.

• Journal of Intelligence and Information Systems
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• v.17 no.3
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• pp.147-168
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• 2011

As personalized recommendation of products and services is rapidly growing in importance, a number of studies provided fundamental knowledge and techniques for developing recommendation systems. Among them, the CF technique has been most widely used and has proven to be useful in many practices. However, current collaborative filtering (CF) technique has still considerable rooms for improving the effectiveness of recommendation systems: 1) a similarity function most systems use to find so-called like-minded people is not well defined in that similarity is computed from a single perspective of similarity concept; and 2) temporal information that contains the changing preference of customers needs to be taken into account when making recommendations. We hypothesize that integration of multiple aspects of similarity and utilization of temporal information will improve the accuracy of recommendations. The objective of this paper is to test the hypothesis through a series of experiments using MovieLens data. The experimental results show that the proposed recommendation system highly outperforms the conventional CF-based systems, confirming our hypothesis.

• Journal of the Korean Institute of Landscape Architecture
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• v.43 no.6
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• pp.138-149
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• 2015

In order to search for the reasonable planning directions for representing traditional landscape, this study conducted the comparative analysis of the designs on the panels and their constructions from both winners of "The Landscape Design Competitions for City Infrastructure of Minlak(2) District in Uijeongbu" and "The Design Competition for Dongtan(2) District Land Development Phase 1". The representing targets and views, the composition and placement of representing space, the design of representing facilities and landscape planting were examined based on the text, master plans, elevations and cross sections, diagrams, images, and perspective drawings proposed from the competition panels. Then, the landscape constructions were reviewed. The results are as follows: First, the types of the representing targets and views are the agricultural landscape, as the local landscape of target area, which are divided into the life space of a traditional village, the traditional water space, and the traditional culture. Second, as to the composition and placement of representing space, the traditional theme spaces are formulated considering the surrounding land use and the local cultural heritage. However, some spaces were changed to the exercise space or convenient facility spaces required in a neighborhood park. Third, in the case of the representing facilities, a round island in the square pond, a traditional pavilion and Hwagye(terraced flower bed) were made without the facilities designed creatively. Fourth, the application of traditional planting techniques was focused on planting trees in the village forest on an island in the square pond and on Hwagye. Fifth, the traditional representing work has gradually advanced with the selection of subject and experimental facility designs based on the professional references. Sixth, the choice of the realizable subject, the expertise for information analysis and the creative design of the traditional facility are required in the future.

• Journal of Biomedical Engineering Research
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• v.38 no.2
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• pp.62-73
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• 2017

To identify a solution for the restricted availability of healthy lungs and the high risk of immune rejections following organ transplantation, tissue engineering techniques for culturing lungs have been studied by many research groups. The most promising method for culturing lungs is the utilization of a bio-scaffold that was prepared using harvested organs from human donors or other animals by removing their original cells. In this study, a pulsatile perfusion pump was used to alleviate the cell removal effect with the high fluid-dynamic power of the perfusion stream during the decellularization process, while other conventional studies focused on chemical methods to identify efficient detergents. The purpose of this study was to analyze the developed device by using energy equivalent pressure (EEP), which is an indicator of pulsatility, to understand the characteristics of pulsatile energy transmitted according to the load size by using the artificial model and compare it with the measured EEP. The pulsatility of the device can be estimated with the concept of fluid-dynamic energy during a particular constant time period or fluid-dynamic power represented as EEP and EEP increment. Because the measured EEP of perfusion flow during decellularization can be changed by the amount of fluid leakage and the degree of clogging in the capillary vessels, EEP should be measured to determine whether the decellularization is progressing without problems. The decrement of EEP caused by the high perfusion resistance was observed from some experimental results that were obtained with artificial models. EEP can be used to monitor the decellularization process after analyzing the varying EEP according to the amount of load. It was confirmed that the EEP was maintained at a high level in the experiment using the harvested lungs from 12-13-week-old rats. In addition, it was confirmed that the cell removal time was faster than when continuous perfusion was performed. In this study, pulsatile power delivered to the lungs was measured to monitor the process of cell removal, and it serve as the evidence for efficient decellularization.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.692-699
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• 2017

The purpose of this study is to investigate the display fatigue quantitatively when operating 2D and HMD-based 3D VR bicycles. Though it is generally accepted that the display fatigue induced by 3D VR is greater than that induced by 2D VR, there have been few studies which attempted to measure the display fatigue scientifically. The subjective degree of cybersickness and quantitative flicker fusion frequency (FFF) were measured in twenty subjects (Male 10, Female 10) before and after they operated 2D and 3D VR bicycles for 5 min. Two dependent variables affected by the 2D and 3D VR displays were analyzed and compared statistically based on scientific evidence and research. This study showed that 3D VR resulted in a significantly higher cybersickness rate and a significant lower FFF rate than 2D VR. Given the current propensity to couple VR techniques with exercise equipment, it seems appropriate to verify the general beliefs through scientific methods and experimental measures such as the FFF and cybersickness questionnaires.

• The KIPS Transactions:PartA
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• v.18A no.3
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• pp.109-114
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• 2011

We describe a technique for automatically proving compiler optimizations sound, meaning that their transformations are always semantics-preserving. As is well known, IR (Intermediate Representation) optimization is an important step in a compiler backend. But unfortunately, it is difficult to detect and debug the IR optimization errors for compiler developers. So, we introduce a C level error check system for detecting the correctness of these IR transformation techniques. In our system, we first create an IR-to-C converter to translate IR to C code before and after each compiler optimization phase, respectively, since our technique is based on the Memory Comparison-based Clone(MeCC) detector which is a tool of detecting semantic equivalency in C level. MeCC accepts only C codes as its input and it uses a path-sensitive semantic-based static analyzer to estimate the memory states at exit point of each procedure, and compares memory states to determine whether the procedures are equal or not. But MeCC cannot guarantee two semantic-equivalency codes always have 100% similarity or two codes with different semantics does not get the result of 100% similarity. To increase the reliability of the results, we describe a technique which comprises how to generate C codes in IR-to-C transformation phase and how to send the optimization information to MeCC to avoid the occurrence of these unexpected problems. Our methodology is illustrated by three familiar optimizations, dead code elimination, instruction scheduling and common sub-expression elimination and our experimental results show that the C level error check system is highly reliable.

• The KIPS Transactions:PartA
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• v.18A no.3
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• pp.99-108
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• 2011

Processor technology is currently continued to parallel processing techniques, not by only increasing clock frequency of a single processor due to the high technology cost and power consumption. In this paper, a SIMD (Single Instruction Multiple Data) based parallel processor is introduced that efficiently processes massive data inherent in multimedia. In addition, this paper proposes pixel subword parallel processing instructions for the SIMD parallel processor architecture that efficiently operate on the image and video pixels. The proposed pixel subword parallel processing instructions store and process four 8-bit pixels on the partitioned four 12-bit registers in a 48-bit datapath architecture. This solves the overflow problem inherent in existing multimedia extensions and reduces the use of many packing/unpacking instructions. Experimental results using the same SIMD-based parallel processor architecture indicate that the proposed pixel subword parallel processing instructions achieve a speedup of $2.3{\times}$ over the baseline SIMD array performance. This is in contrast to MMX-type instructions (a representative Intel multimedia extension), which achieve a speedup of only $1.4{\times}$ over the same baseline SIMD array performance. In addition, the proposed instructions achieve $2.5{\times}$ better energy efficiency than the baseline program, while MMX-type instructions achieve only $1.8{\times}$ better energy efficiency than the baseline program.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.2
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• pp.95-104
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• 2017

As the technology in smart device is growing and Social Network Services(SNS) are becoming more common, the data which is difficult to be processed by existing RDBMS are increasing. As a result of this, NoSQL databases are getting popular as an alternative for processing massive and unstructured data generated in real time. The demand for the technique of digital investigation of NoSQL databases is increasing as the businesses introducing NoSQL database in their system are increasing, although the technique of digital investigation of databases has been researched centered on RDMBS. New techniques of digital forensic investigation are needed as NoSQL Database has no schema to normalize and the storage method differs depending on the type of database and operation environment. Research on document-based database of NoSQL has been done but it is not applicable as itself to other types of NoSQL Database. Therefore, the way of operation and data model, grasp of operation environment, collection and analysis of artifacts and recovery technique of deleted data in HBase which is a NoSQL column-based database are presented in this paper. Also the proposed technique of digital forensic investigation to HBase is verified by an experimental scenario.