• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.474-486
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• 2015

This paper proposes a multi-objective optimal placement method of Phasor Measurement Units (PMUs) in large electric transmission systems. It is proposed for minimizing the number of PMUs for complete system observability and maximizing measurement redundancy of the buses, simultaneously. The measurement redundancy of the bus indicates that number of times a bus is able to monitor more than once by PMUs set. A high level of measurement redundancy can maximize the system observability and it is required for a reliable power system state estimation. Therefore, simultaneous optimizations of the two conflicting objectives are performed using a binary coded firefly algorithm. The complete observability of the power system is first prepared and then, single line loss contingency condition is added to the main model. The practical measurement limitation of PMUs is also considered. The efficiency of the proposed method is validated on IEEE 14, 30, 57 and 118 bus test systems and a real and large- scale Polish 2383 bus system. The valuable approach of firefly algorithm is demonstrated in finding the optimal number of PMUs and their locations by comparing its performance with earlier works.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1994.04a
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• pp.596-605
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• 1994

An efficient measurement and evaluation system for hand tool tasks will provide a practical solution to the problem of designing and evaluating manual tool tasks in the workplace. Few studies on the biomechanical analysis of hand postures and tool handling tasks exist because of the lack of appropriate measurement techniques for hand force. A measurement system for the finger forces and joint angles for analysis of manual tool handling tasks was developed in this study. The measurement system consists of a force sensing glove made from twelve Force Sensitive Resistors and an angle-measuring glove (Cyberglove$\^$TM/, Virtual technologies) with eighteen joint angle sensors. A biomechanical model of the hand using the data from the measurement system was also developed. Systems of computerized procedures were implemented integrating the hand posture measurement system, biomechanical analysis system, and the task analysis system for manual tool handling tasks. The measurement system was useful in providing the hand force data needed for an existing task analysis system used in CTD risk evaluation. It is expected that the hand posture measurement developed in this study will provide an, efficient and cost-effective solution to task analysis of manual tool handling tasks. These tasks are becoming increasingly important areas of occupational health and safety of the country.

• Journal of the Korean Society of Costume
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• v.55 no.5 s.95
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• pp.55-64
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• 2005

The concern with three-dimensional measurement has been growing in recent years. And over the last few years, several studies have been made on three-dimensional measurement. Some of the studies using a three-dimensional measurement have focused on type of form of human body and evaluation of fitness. But there has been no study about applications of three-dimensional measurement system for shape analysis. So, the purpose of this study was to investigate about application of three-dimensional mea-surement system lot shape analysis. The instrument and tools for three-dimensional measurement was Whole Body 3D scanner(model name: Exyma-WBS2H). Analysis program used in experiment is Rapid Form 2004 PPI (INUS technology, Int, Korea). The following results were obtained; 1. The point data using three-dimensional measurement system built 3D model. 2. The three-dimensional data were used to analyze length and curvature of shape. 3. The shape using three-dimensional measurement system could be used in variety field.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.5
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• pp.93-99
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• 1998

Although laser interferometer measurement system has advantages of measurement range and accuracy, it has some disadvantages when measurement of multi degrees of freedom of motion are required. Because the traditional error measurement methods for geometric errors (two straightness and three angular errors) of a slide of machine tools measures error components one at a time. It may also create an optical path difference and affect the measurement accuracy. In order to identify and compensate for geometric errors of a moving rigid body in real time processes, an on-line error measurement system for simultaneous detection of the five error components of a moving object is required. Using laser alignment technique and some optoelectronic components, an on-line measurement system with 5 degrees of freedom was developed for the geometric error detection in this study Performance verification of the system has been performed on an error generating mechanism. Experimental results show the feasibility of this system for identifying geometric errors of a slide of machine tools.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.19 no.3
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• pp.233-239
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• 2009

The regulatory recognition, regulatory approval, and observance for employer, inspector, and worker groups were investigated for the Korean measurement system in working environments. The employer, worker, and inspector showed an agreement of 90~97 % for the measurement of working environments. This survey showed that the measurement system of working environments has been settled in Korea. However, this survey showed an agreement of 81~87 % for reporting the results of working environment, involvement of worker representative, improvement of working environment, and holding presentations for working environment measurement. The employer recognized well for the measurement of working environments, involvement of worker representative, improvement of working environment, and holding presentations for working environment measurement, but the employee did not recognize well them as much as the employer did. Thus, the improvements for the recognition for involvement of worker representative, improvement of working environment, and holding presentations for working environment measurement by the employee are needed.

• Journal of Korean Elementary Science Education
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• v.30 no.4
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• pp.430-441
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• 2011

We investigated the elementary students' epistemological views on the nature of scientific measurement. The Views About Scientific Measurement (Ibrahim, 2005) was administered to 117 sixth graders. The analyses of the results indicated that there was an inconsistency in their epistemological views depending on the contexts of the measurement. They also had some difficulties in understanding a distribution of the data, which is needed to understand the necessity of repeating measurements, choosing a best representative value, and comparing data sets. They were found to have some naive views on scientific measurement which influenced negatively for fostering modern epistemological views on the nature of scientific measurement. The results suggest that the nature of scientific measurement should be emphasized explicitly in the national curriculum, and an effective method which improves elementary students' epistemological views on the nature of scientific measurement also be developed.

• Transactions of The Korea Fluid Power Systems Society
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• v.5 no.1
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• pp.6-12
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• 2008

ISO pneumatic cylinder reliability test requires air leakage measurement. Air cylinder has many parts and the leakage shall be measured before, during and after endurance test, and, the leakage should smaller than the specified value. The existing measurement method needs complex operation and the calibration of leak detector, and, has to separate the testing cylinder from endurance test device, which causes the change of contact condition of seal in the cylinder. Therefore, it is hard to evaluate the air leakage during endurance test, and guarantee the reliability of the conventional measurement method. In this paper, a new method for air leakage measurement using isothermal chamber, which does not requires calibration or temperature compensation, and, can measure air leakage accurately with quite simple operations, is proposed. As a result, reliability of air leakage measurement can be improved because the proposed method does not have to separate the testing cylinder from the endurance test device for air leakage measurement. The effectiveness of the proposed method is proved by error analysis of leak measurement from experimental result.

• Journal of Astronomy and Space Sciences
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• v.35 no.3
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• pp.163-173
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• 2018

This paper presents relative navigation using intermittent laser-based measurement data for spacecraft flying formation that consist of two spacecrafts; namely, chief and deputy spacecrafts. The measurement data consists of the relative distance measured by a femtosecond laser, and the relative angles between the two spacecrafts. The filtering algorithms used for the relative navigation are the extended Kalman filter (EKF), unscented Kalman filter (UKF), and least squares recursive filter (LSRF). Numerical simulations reveal that the relative navigation performances of the EKF- and UKF-based relative navigation algorithms decrease in accuracy as the measurement outage period increases. However, the relative navigation performance of the UKF-based algorithm is 95 % more accurate than that of the EKF-based algorithm when the measurement outage period is 80 sec. Although the relative navigation performance of the LSRF-based relative navigation algorithm is 94 % and 370 % less accurate than those of the EKF- and UKF-based navigation algorithms, respectively, when the measurement outage period is 5 sec; the navigation error varies within a range of 4 %, even though the measurement outage period is increased. The results of this study can be applied to the design of a relative navigation strategy using the developed algorithms with laser-based measurements for spacecraft formation flying.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.1
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• pp.92-99
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• 2006

The swirl ratio of a charge in the cylinder was estimated by calculating the ratio of the rotary speed of charge which could be simulated from the rotary speed of paddle in the swirl measurement apparatus, to the engine speed which could be calculated by measuring intake air flow rate. The automation of the swirl ratio measurement for cylinder head was achieved by controling both valve lift in cylinder head and a suction pressure of surge tank using two step-motors. The number of measurement position for calculating mean swirl ratio was varied by adjusting the interval of valve lift. The mean swirl ratio with varying the number of measurement position showed nearly constant value. Two measurement methods for measuring the swirl ratio were compared, one was to control the suction pressure of the surge tank with PID (proportional, integral, differential) mode with by-pass valve controlled by the step motor and the other did not control the surge tank pressure by fixing the by-pass valve. The difference of the mean swirl ratio between the two measurement methods showed nearly constant value with varying the number of measurement position. This means that the w/o PID control method could be preferred to the PID control method which has been used, due to the simpleness of the swirl measurement.

• KSBB Journal
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• v.32 no.1
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• pp.54-62
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• 2017

This study aimed to estimate the measurement uncertainty related to determination of hyaluronic acid used as a dietary supplement by high-performance liquid chromatography. According to the guidelines of the Association of Official Analytical Chemists, the analytical processes for determination of hyaluronic acid were performed. And the measurement uncertainty obtained during the analytical processes were expressed in accordance with mathematical/ statistical guidances of GUM (Guide to the Expression of Uncertainty in Measurement) & EURACHEM (Focus for Analytical Chemistry in Europe) for the analytical operations. For the uncertainty in measurement produced based on this analytical method, the expanded uncertainty was calculated by using the relative standard uncertainty between analytical results and sources of uncertainty in measurement (sample weight, final volume, extraction volume, standard solution, matrix and instrument etc). In the results of 95% confidence interval, it was calculated that the uncertainty in measurement was $57.75{\pm}8.76{\mu}g/kg$ (k=2.0). Therefore, it showed that the measurement uncertainty obtained by this analytical method influences on 15.2% of the contents of hyaluronic acid as the analytical results.