• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1712-1717
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• 1991

The paper describes estimation errors of unsteady flowrate measurements due to parameter changes in a quasi-remote instantaneous flowrate measurement method (abbreviate as QIFM) and an instantaneous flowrate measurement method using two points pressure measurements (abbreviate as TPFM). By introducing error performance index, the influence of parameter changes on the accuracy, and dynamic response of the estimated unsteady flowrate are evaluated. Of four parameters, the variation of the length of the pipeline and speed of sound produce large errors in the estimated unsteady flowrate during transient periods. The effect of kinematic viscosity of the working fluid(oil) is relatively insensitive in unsteady flowrate estimation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1271-1280
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• 2000

A sensor placement technique to identify structural parameter was developed. Experimental results must be acquired to identify unknown dynamic characteristics of a targeting structure for the comparison between analytical model and real structure. If the experimental environment was not equipped itself properly, it can be happened that some valuable information are distorted or ill-condition can be occurred. In this work the index to determine exciting points was derived from the criterion of maximizing parameter sensitivity matrix and that to choose measurement points was from that of preserving the invariant of sensitivity matrix. This idea was applied to a compressor hull structure to verify its performance. The result shows that the selection of measurement and excitation points using suggested criteria improve the ill-conditioning problem of inverse type problems such , as model updating.

• Journal of Navigation and Port Research
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• v.26 no.5
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• pp.571-575
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• 2002

An immersion-type on-line refractometer useful for the in-situ measurement of salinity and temperature of sea water is developed, and its performance is examined by applying the refractometer to known salt solution having salt concentration between 2 and 4 % similar to practical sea water salinity. Since refractive index and temperature are measured simultaneously, it is possible to compensate the effect of temperature for fast and direct measurement. The outcome of salinity measurement for the different concentrations of salt solution indicates that the device is suitable for the salinity measurement by yielding stable and reproducible reading.

• Journal of Sasang Constitutional Medicine
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• v.33 no.4
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• pp.1-9
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• 2021

Objectives The purpose of this study was to check whether the classification of the individual's Body Mass Index (BMI) could be predicted by analyzing the voice data constructed at the Korean medicine data center (KDC) using machine learning. Methods In this study, we proposed a convolutional neural network (CNN)-based BMI classification model. The subjects of this study were Korean adults who had completed voice recording and BMI measurement in 2006-2015 among the data established at the Korean Medicine Data Center. Among them, 2,825 data were used for training to build the model, and 566 data were used to assess the performance of the model. As an input feature of CNN, Mel-frequency cepstral coefficient (MFCC) extracted from vowel utterances was used. A model was constructed to predict a total of four groups according to gender and BMI criteria: overweight male, normal male, overweight female, and normal female. Results & Conclusions Performance evaluation was conducted using F1-score and Accuracy. As a result of the prediction for four groups, The average accuracy was 0.6016, and the average F1-score was 0.5922. Although it showed good performance in gender discrimination, it is judged that performance improvement through follow-up studies is necessary for distinguishing BMI within gender. As research on deep learning is active, performance improvement is expected through future research.

• Structural Engineering and Mechanics
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• v.54 no.2
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• pp.337-362
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• 2015

This paper presents a feasibility study on structural damage alarming and localization of long-span cable-supported bridges using multi-novelty indices formulated by monitoring-derived modal parameters. The proposed method which requires neither structural model nor damage model is applicable to structures of arbitrary complexity. With the intention to enhance the tolerance to measurement noise/uncertainty and the sensitivity to structural damage, an improved novelty index is formulated in terms of auto-associative neural networks (ANNs) where the output vector is designated to differ from the input vector while the training of the ANNs needs only the measured modal properties of the intact structure under in-service conditions. After validating the enhanced capability of the improved novelty index for structural damage alarming over the commonly configured novelty index, the performance of the improved novelty index for damage occurrence detection of large-scale bridges is examined through numerical simulation studies of the suspension Tsing Ma Bridge (TMB) and the cable-stayed Ting Kau Bridge (TKB) incurred with different types of structural damage. Then the improved novelty index is extended to formulate multi-novelty indices in terms of the measured modal frequencies and incomplete modeshape components for damage region identification. The capability of the formulated multi-novelty indices for damage region identification is also examined through numerical simulations of the TMB and TKB.

• Journal of ILASS-Korea
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• v.24 no.2
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• pp.51-57
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• 2019

In this study, the spray atomization characteristics of urea injector used in SCR system for construction machinery was analyzed, and the uniformity index at the front of mixer and NOx conversion efficiency were evaluated through numerical analysis. Spray visualization and droplet size/velocity measurement were performed and the measured results were used to verify the spray analysis model to calculate the uniformity index in the exhaust gas after-treatment system. For the flow analysis, STAR-CCM, a three-dimensional CFD, was used and the uniformity index of the SCR system at the front of the mixer was calculated using the droplet dissociation model and the wall collision model. Finally, the DeNOx performance for the average condition of the NRTC driving mode was calculated to understand the NOx conversion efficiency reflecting the exhaust gas temperature. The simulation results show that the uniformity index at the front of mixer was calculated as 0.862 and DeNOx efficiency was 75.9%.

• 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.

• Journal of the Korean Society of Safety
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• v.27 no.1
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• pp.76-85
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• 2012

This paper proposes a robust damper design technique for adjacent structures against model uncertainty. This approach introduces multi-objective optimization based system identification using measurement information which enables reasonable selection of the perturbation range in the robust design. Moreover, in order to improve the numerical efficiency in sampling the structural models required for the robust design of large structures, we define new objective functions which enable us to minimize the number of candidate models suitable to the purpose of the robust design. In addition, the performance index is newly employed to evaluate the robust performance of the sampled structural models, and the robust design has been performed according to the performance index. As a numerical example to demonstrate the efficiency of the proposed method, 5-story and 10-story two adjacent buildings are taken into account, and the existing and newly proposed robust design approaches are compared with each other. The results demonstrate that the proposed approach can guarantee more robust damper system only using small number of samples of the structural models because of using the measurement information which leads to improvement in the numerical efficiency, compared with the existing robust design methods.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.49-52
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• 2006

should be in English, A make out an economical, reliable and easy to adoptable instrument in turbine discharge measurement was restricted from lots of it's foundational condition. Not with standing the brilliant progress in new technology of these day, useful instrument for flow measurement in turbine is still ongoing. Nowaday, the increasing importance of renewable energy makes it more important that the measuring turbine efficiency as a decision making index of old turbines' replacement. In Turbine performance diagnosis, Kwater(Korea Water Corporation) got an enough ability and decent reputation for who has invested lots of time and effort for buildup and development. In Korea as a public corporation who should take a crucial roll in Turbine business, Kwater has introduced some developed new technology for other domestic concerned one. With this writing, I'd like to introduce ASFM system as a newly developed instrument that can cope with lots restriction in discharge measurement in turbine. Kwater adopted the system in 2005, and performed 2 times of trial test. The test result was good enough to use the system as a reference test method.

• Korean Journal of Construction Engineering and Management
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• v.10 no.4
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• pp.119-128
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• 2009

The construction R&D(Research & Development) has various performance according to research charater. But present performance evaluation form evaluates project rather than charater of research. The important reasons that evaluats the performance are to try conclusions with evaluated objects in the short run, but to forecast the performance of future construction R&D and to get the better performance. Thus this study extracts the RPI(Research Performanc Index) with output as the conter, developes the estimation method and measures the quantitative performance. Applying the ANOVA(Analysis of Variance), it is proved that the performance according to research charater is various. And applying the Correspondence Analysis, it is analised the relationship with performance and research charater. The purposes of this study are to idetify the problem of uniform performance evaluation and to improve it.