• Journal of the Korea Society of Computer and Information
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• v.23 no.12
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• pp.219-226
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• 2018

Collaborative filtering has been most popular approach to recommend items in online recommender systems. However, collaborative filtering is known to suffer from data sparsity problem. As a simple way to overcome this problem in literature, Jaccard index has been adopted to combine with the existing similarity measures. We analyze performance of such combination in various data environments. We also find optimal weights of factors in the combination using a genetic algorithm to formulate a similarity measure. Furthermore, optimal weights are searched for each user independently, in order to reflect each user's different rating behavior. Performance of the resulting personalized similarity measure is examined using two datasets with different data characteristics. It presents overall superiority to previous measures in terms of recommendation and prediction qualities regardless of the characteristics of the data environment.

• Journal of the Korean Statistical Society
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• v.26 no.1
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• pp.131-146
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• 1997

In this paper the problem of measuring the stochastic dependence among sets fo random variates is considered, and attention is specifically directed to forming a single well-defined measure of the dependence among sets of normal variates. A new information theoretic measure of the dependence called dependence index (DI) is introduced and its several properties are studied. The development of DI is based on the generalization and normalization of the mutual information introduced by Kullback(1968). For data analysis, minimum cross entropy estimator of DI is suggested, and its asymptotic distribution is obtained for testing the existence of the dependence. Monte Carlo simulations demonstrate the performance of the estimator, and show that is is useful not only for evaluation of the dependence, but also for independent model testing.

• Journal of Construction Engineering and Project Management
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• v.8 no.1
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• pp.22-30
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• 2018

Achieving sustainability targets on construction projects has increasingly become one of the prime strategies for construction organizations. To provide more detailed guidance on sustainability implementation on projects, Construction Industry Institute (CII) Research Team (RT) 304 developed a catalog of the Construction Phase Sustainability Actions (CPSAs). The primary objective of this paper was the development of two support tools, the CPSA Screening Tool and the CPSA Implementation Index, that could be used to enable efficient application of CPSAs, support sustainability-related decisions, and measure CPSA implementation and performance. The authors developed the tools in four stages: conceptual, detailed planning, tool programming, and testing. The tools were then demonstrated on a capital project to confirm their efficacy and applicability. This paper presents the background, inputs and outputs, and the algorithms of each tool. The CPSA Screening Tool can prioritize the CPSAs most relevant to a project; the CPSA Implementation Index enables continuous monitoring of implementation levels.

• Journal of Preventive Medicine and Public Health
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• v.34 no.3
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• pp.244-252
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• 2001

Objective : Health insurers and policy makers are increasingly examining the hospital mortality rate as an indicator of hospital quality and performance. To be meaningful, a risk-adjustment of the death rates must be implemented. This study reviewed 5 severity measurement methods and applied them to the same data set to determine whether judgments regarding the severity-adjusted hospital mortality rates were sensitive to the specific severity measure. Methods : The medical records of 584 patients who underwent coronary artery bypass graft surgery in 6 general hospitals during 1996 and 1997 were reviewed by trained nurses. The MedisGroups, Disease Staging, Computerized Severity Index, APACHE III and KDRG were used to quantify severity of the patients. The predictive probability of death was calculated for each patient in the sample from a multivariate logistic regression model including the severity score, age and sex to evaluate the hospitals' performance, the ratio of the observed number of deaths to the expected number for each hospital was calculated. Results : The overall in-hospital mortality rate was 7.0%, ranging from 2.7% to 15.7% depending on the particular hospital. After the severity adjustment, the mortality rates for each hospital showed little difference according to the severity measure. The 5 severity measurement methods varied in their statistical performance. All had a higher c statistic and $R^2$ than the model containing only age and sex. There was a little difference in the relative hospital performance evaluation by the severity measure. Conclusion : These results suggest that judgments regarding a hospital's performance based on severity adjusted mortality can be sensitive to the severity measurement method. Although the 5 severity measures regarding hospital performance concurred, more often than would be expected by chance, the assessment of an individual hospital mortality rates varied by the different severity measurement method used.

• The Journal of Korea Robotics Society
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• v.7 no.1
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• pp.9-19
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• 2012

This paper proposes a performance index for the multiple shape object handling of dual arm manipulator to determine whether a robot is good or not. When the dual-arm manipulator grasps a fixed object and is posed, the dual-arm manipulator should procure a space to freely control the manipulator. As a performance evaluation parameter, each joint torque from current sensor signal is utilized. From the current information, torque and energy for each joint are estimated. In this paper an performance index for an unstructured object is defined by an energy-cost function, and stability analysis for each motion is derived by the maximum force to the object. The maximum force to the object is computed by the inertia of object and acceleration information of end-effector. The acceleration data are derived by the double derivation of each encoder signal. Manipulability measure which implies how efficiently the dual-arm manipulator can move with the grasped object, can be represented by the intersection of the two manipulability ellipsoids for the left and right arms. Effectiveness of the proposed algorithm has been verified through the practical simulations and real experiments.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.3
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• pp.155-166
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• 2008

The performance evaluation of a new building is becoming more important because efficient design alone is often not sufficient to deliver an efficient building. However, there is a lack of standard evaluation methods to measure the energy performance of a new construction that has Energy Conservation Design Measures(ECDMs). This study presents an enhanced method based on calibrated whole-building simulation for evaluating the energy performance of new commercial buildings and demonstrates its use using a case-study building, including: an Energy Use Index(EUI) comparison with sub-metered data and an evaluation of the performance of specific ECDMs. The use of this method has determined that the case-study building was shown to use approximately 47% less energy than the base-case building that has the same shape and function as the case-study building(i.e., calibrated as-built simulation mode]), but doesn't include the simulated ECDMs.

• Journal of Korean Society for Quality Management
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• v.34 no.3
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• pp.66-72
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• 2006

The process capability indices are widely used to measure the capability of the process to manufacture items within the specified tolerance. Most evaluations on process capability indices focus on point estimates, which may result in unreliable assessments of process performance. The index $C_p$ has been widely used in various industries to assess process performance. In this paper, we propose new testing procedure on assessing $C_p$ index for practitioners to use in determining whether a given process is capable. The provided approach is easy to use and the decision making is more reliable. Whether a process is clearly normal or nonnormal, our bootstrap testing procedure could be applied effectively without the complexity of calculation. A numerical result based on the proposed approach is illustrated.

• PNF and Movement
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• v.9 no.2
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• pp.45-53
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• 2011

Purpose : Many researchers have attempted to identity the reliability used in clinical examination of balance and gait performance for individuals of hemiparetic stroke. The study aims to evaluate whether the reliabilities of three popular clinical measures of balance and gait performance was consistency regardless of applicate experience of those clinical measures compared with previous studies for persons with hemiparetic stroke. Methods : A total of three hemiparetic stroke populations and twenty-six physical therapists were recruited from Glory hospital, Inchen, Korea in this study. The three clinical measures, involving Berg balance test (BBT), dynamic gait index (DGI), and Tinetti performance-oriented mobility assessment (POMA), were assessed in two sessions that were seven days apart. Results : The POMA was showed a good intrarater and interrater reliabilities in people with hemiparetic stroke regardless of measure's experience in clinical field. However BBT and DGI were showed below moderate intrarater and interrater reliabilities. Conclusion : The POMA could be a reliable measure to evaluate functional postural stability and gait performance in hemiparetic stroke patients compared with other two clinical measures regardless of measure's experience of physical therapists.

• Journal of Technology Innovation
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• v.5 no.1
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• pp.15-43
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• 1997

This paper investigates empirically the relationship between various business portfolio properties (particularly technological properties) and chaebol's performance using data on the 50largest chaebols in Korea. In addition to the traditional indexes to measure diversification such as entropy index, we calculated inter-industry technological similarity using R'||'&'||'D expenditure data by industry and 1990 Input-output Table in korea, and obtained chaebol-level technological relatedness and internal transaction proportion from chaebols' business profile, inter-inustry technological similarity and 1990 input-output table. We applied factor analysis on 13 business portfolio property indexes and showed that they could be grouped into 3 dimensions. diversification scope, inter-business relatedness and degree of vertical integration. In this paper, using 50 largest chaebols' financial data (1989-1994), we analyzed empirically the effect of business portfolio properties on ROS(Return On Sales) which is conventional index for firm performance and on TFP(Total Factor Productivity) growth which is a pure measure of firm performance. To utilize the advantage of panel data, FEM(Fixed Effect Model) and REM(Random Effect Model) were used. The empirical result shows that the entropy index as a measurement of inter-business relatedness in not significant but technological relatedness index is significant. OLS estimates on pooled data were considerably different from FEM or REM estimates on panel data. By introducing interaction effect among the three variables for business portfolio properties, we obtained three findings. First, only VI(Vertical integration) has a significant positive correlation with ROS. Second, when using TFP growth as an dependent variable, both TR(Technological Relatedness) and VI are significant and positively related to the dependent variable. Third, the interaction term between TR and VI is significant and negatively affects TFP growth, meaning that TR and VI are substitutes. These results suggest strategic directions on restructuring business portfolio. As VI is increased, chaebols will get more profit. A higher level of either TR or VI will increase TFP growth rate, but increase in both TR and VI will have a negative effect on TFP growth. To summarize, certain business portfolio properties such as VI and TR can be considered "resources" themselves since they can affect profit rate and productivity growth. VI and TR have a synergy effect of change in profit rate and productivity growth. VI increases ROS and productivity growth, while TR increases productivity growth representing a technological synergy effect.t.

• The Journal of Korean Physical Therapy
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• v.17 no.3
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• pp.413-420
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• 2005

The purpose of this study was to determine differences of balance performance to upright standing, forward bending posture, and sudden load during forward bending posture in subjects with and without a history of low back pain. A study was conducted on 8 subjects with low back pain and 13 healthy subjects. Dynamic Balance System was used to measure the postural sway index, left-right sway index, and anterior-posterior sway index on balance performance. There were no differences between subject groups on balance performance during upright standing. Balance performance was increased in forward bending posture and decreased in sudden load during forward bending posture in subjects with low back pain. These results suggest that subjects with low back pain demonstrated increased activity and decreased reaction times of trunk muscles.