• Journal of the Korean Society for Precision Engineering
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• v.11 no.6
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• pp.28-41
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• 1994

An efficient algorithm is proposed to select the proper tools and generate their paths for NC rough cutting of dies and molds with sculptured surfaces. Even though a milling process consists of roughing, semi-finishing, and finishing, most material is removed by a rough cutting process. Therfore it can be said that the rough cutting process occupy an important portion of the NC milling process, and accordingly, an efficient rough cutting method contributes to an efficient milling process. In order work, the following basic assumption is accepted for the efficient machining. That is, to machine a region bounded by a profile, larger tools should be used in the far inside and the region adjacent to relatively simple portion of the boundary while smaller tools are used in the regions adjacent to the relatively complex protion. Thus the tools are selected based on the complexity of the boundary profile adjacent to the region to be machined. An index called cutting path ratio is proposed in this work as a measure of the relative complexity of the profile with respect to a tool diameter. Once the tools are selected, their tool paths are calculated starting from the largest to the smallest tool.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.2
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• pp.65-72
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• 2007

As embedded system has strict cost and space constraints, it is impossible to apply conventional fault-tolerant techniques directly for increasing the dependability of embedded system. In this paper, we propose software fault-tolerant mechanism which requires only minimum redundancy of system component. We define an utility metric that reflects the dependability of each embedded system component, and then measure the defined utility of each reconfiguration combinations to provide fault tolerance. The proposed utility evaluation process shows exponential complexity. However we reduce the complexity by hierachical subgrouping at the software level of each component. When some components of embedded system are tailed, reconfiguration operation changes the system state from current faulty state to pre-calculated one which has maximum utility combination.

• Journal of Korea Multimedia Society
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• v.13 no.11
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• pp.1575-1585
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• 2010

It is very important to forecast a back resource of a software development effort at the early stage of development life cycle for successful project processing, and it is carried out through software size estimation. The recent trend of software size estimation method is focused on the user's value such as FPA. We measure the actual development effort through case study and calculate CFP directly according to the cosmic-ffp manual V.3.0. in this paper. We also propose the software development effort estimation model by using the produced data. COSMIC-FFP does not use weights of necessary function elements, and so it has disadvantage in estimating sizes. This paper proposes the estimation model to estimate the precision software size by using system complexity as weight.

• Journal of Korean Institute of Industrial Engineers
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• v.41 no.2
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• pp.121-127
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• 2015

A reduction of motor performance due to brain disorders can be screened by evaluating force tracking capabilities (FTCs). Existing studies have examined FTCs mainly using simple sinusoidal waves, of which repeated profiles have a critical limitation due to a learning effect in force tracking. The present study examined the effects of personal factors (age and gender) and sinusoidal wave factors (central force and complexity) on FTCs of healthy adults using composite sinusoidal wave profiles (CSWPs). FTCs were measured using Finger $Touch^{TM}$ for 30 seconds and quantified in terms of time within the target range (TWR, accuracy measure) and relative RMSE (RRMSE, variability measure). A total of 90 healthy adults in 20s to 70s with the equal gender ratio participated in the experiment consisting of combinations of 2 central force levels (6 N and 10 N) and 2 complexity levels (approximate entropy, ApEn = 0.03 and 0.06) of CSWPs. Significantly decreased FTCs (lower TWR and higher RRMSE) were found in aged adults, females, the low central force, and the high complexity. The detailed FTC decrements include a 43% reduced TWR and a 85% increased RRMSE of older adults in 70s as compared to those in 20s, a 17% reduced TWR and a 17% increased RRMSE of female as compared to those of male, a 30% reduced TWR and a 108% increased RRMSE at central force = 6N when compared to those at central force = 10N, and a 19% reduced TWR and a 30% increased RRMSE at ApEn = 0.06 as compared to those at ApEn = 0.03. The characteristics of FTCs for CSWPs can be of use in establishing an assessment protocol of motor performance for screening brain disorders.

• The Journal of the Acoustical Society of Korea
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• v.27 no.3
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• pp.119-128
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• 2008

This paper analyzes the relationship between two representative statistical methods for bandwidth extension (BWE): Gaussian Mixture Model (GMM) and Hidden Markov Model (HMM) ones, and compares their performances. The HMM method is a memory-based system which was developed to take advantage of the inter-frame dependency of speech signals. Therefore, it could be expected to estimate better the transitional information of the original spectra from frame to frame. To verify it, a dynamic measure that is an approximation of the 1st-order derivative of spectral function over time was introduced in addition to a static measure. The comparison result shows that the two methods are similar in the static measure, while, in the dynamic measure, the HMM method outperforms explicitly the GMM one. Moreover, this difference increases in proportion to the number of states of HMM model. This indicates that the HMM method would be more appropriate at least for the 'blind BWE' problem. On the other hand, nevertheless, the GMM method could be treated as a preferable alternative of the HMM one in some applications where the static performance and algorithm complexity are critical.

• Journal of Korean Port Research
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• v.10 no.2
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• pp.17-29
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• 1996

It is required to consider pricing and non-pricing factors and external economy in order to achieve the objects of physical distribution system in a port. Recently, among the three factors, much attention has been paid to non-pricing factor in the system. Although physical distribution service in a port(PDSP)has been frequently mentioned in documents and literature related to port and shipping studies, few study on it has not been systematically and scientifically made due to the following problems; $\circ$ there are not proper criteria to evaluate level and quality of PDSP and as a result it is difficult to set up a unified standard for doing so. $\circ$ algorithms to evaluate problems with complex and ambiguous attributes and multiple levels in PDSP are not available. This thesis aims to establish a paradigm to evaluate PDSP and to abvance existing decision making methods to deal with complex and ambiguous problems in PDSP. To tackle the first purpose, extensive and thorough literature survey was carried out on general physical distribution service, which is a corner stone to handle PDSp. In addition, through interviews and questionnaire to the expert, it have extracted 82 factors of physical distribution service in a port. They have been classified into 6 groups by KJ method and each group defined by the expert's advice as follows; a. Potentiality b. Exactness c. safety d. Speediness e. Convenience f. Linkage Prior to the service evaluation, many kinds of its attributes must be identified on the basis of rational decision owing to complexity and ambiguity inherent in PDSP. An analytical hierarchy process (AHP) is a method to evaluate them but it is not applicable to PDSP that have property of non-additivity and overlapped attributes. Therefore, probablility measure can not be used to evaluate PDSP but fuzzy measure is required. Hierarchical fuzzy integral method, which is merged AHP with fuzzy measure, is also not effective method to evaluate attributes because it has vary complicated way to calculate fuzzy measure identification coefficient of attributes. A new evaluation algorithm has been introduced to solve problems with multi-attribute and multi-level hierarchy, which is called hierarchy fuzzy process(HFP).Analysis on ambiguous aspects of PDSP under study which is not easy to be defined is prerequisite to evaluate it. HFP is different from algorithm existed in that it clarified the relationship between fuzzy measure and probability measure adopted in AHP and that it directly calculates the family of fuzzy measure from overlapping coefficient and probability measure to treat and evaluate ambiguous and complex aspects of PDSP. A new evaluation algorithm HFP was applied to evaluate level of physical distribution service in the biggest twenty container port in the world. The ranks of the ports are as follows; 1. Rotterdam Port, 2. Hamburg Port, 3. Singapore Port, 4. Seattle Port, 5. Yokohama Port, 6. Long beach Port, 7. Oakland Port, 8. Tokyo Port, 9. Hongkong Port, 10. Kobe Port, 11. Los Angeles Port, 12. New york Port, 13. Antwerp Port, 14. Felixstowe Port, 15. Bremerhaven Port, 16. Le'Havre Port, 17. Kaoshung Port, 18. Killung Port, 19. Bangkok Port, 20. Pusan Port

• The Transactions of the Korea Information Processing Society
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• v.4 no.9
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• pp.2299-2308
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• 1997

While most machine learning research has been primarily concerned with the development of systems that implement one type of learning strategy, we use a multistrategy approach which integrates rule induction learning and instance-based learning, and show how this marriage allows for overall better performance. In the rule induction learning phase, we derive an entropy function, based on Hellinger divergence, which can measure the amount of information each inductive rule contains, and show how well the Hellinger divergence measures the importance of each rule. We also propose some heuristics to reduce the computational complexity by analyzing the characteristics of the Hellinger measure. In the instance-based learning phase, we improve the current instance-based learning method in a number of ways. The system has been implemented and tested on a number of well-known machine learning data sets. The performance of the system has been compared with that of other classification learning technique.

• The KIPS Transactions:PartB
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• v.11B no.4
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• pp.477-484
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• 2004

The technique of sequential pattern mining means generating a set of inter-transaction patterns residing in time-dependent data. This paper proposes a new method for generating sequential patterns with the use of Hellinger measure. While the current methods are generating single dimensional sequential patterns within a single attribute, the proposed method is able to detect multi-dimensional patterns among different attributes. A number of heuristics, based on the characteristics of Hellinger measure, are proposed to reduce the computational complexity of the sequential pattern systems. Some experimental results are presented.

• Journal of KIISE:Software and Applications
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• v.36 no.4
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• pp.320-328
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• 2009

In general, there are two types of noun phrases(NP): Base Noun Phrase(BNP), and Maximal-Length Noun Phrase(MNP). MNP identification can largely reduce the complexity of full parsing, help analyze the general structure of complex sentences, and provide important clues for detecting main predicates in Chinese sentences. In this paper, we propose a 2-phase hybrid approach for MNP identification which adopts salient features such as expanded chunks and classified punctuations to improve performance. Experimental result shows a high quality performance of 89.66% in $F_1$-measure.

• Journal of Korean Society on Water Environment
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• v.21 no.2
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• pp.109-117
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• 2005

Understanding the condition of our nation's water resources, identifying what caused problems, and determining how to solve these problems are essential but difficult undertakings. The natural water cycle is itself intricate, and the addition of human activities increased this complexity. Consequently, answering the basic question "How clean and safe is our water?" is not easy. One way to present the condition of our water resources and the impacts of related human activities is to develop understandable measures, or indicators, that singly or in combination provide information on water quality. Managers and scientists can then use this information to develop effective solutions and make sound decisions to protect our water resources. It is important to note that environmental indicators can be used to measure a variety of phenomena. Indicators can present information on status or trends in the state of the environment, can measure pressures or stressors that degrade environmental quality, and can evaluate society's responses aimed at improving environmental conditions.