• New & Renewable Energy
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• v.9 no.2
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• pp.51-57
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• 2013

The Grid code is being strengthen as increase of renewable energy ratio. Especially, the grid connection regulations are continuously being updated for stable operation of power grids. Static grid support and Dynamic grid support must make an accurate measure at Grid connected point because they needs control algorithm individually. It has to exactly measure voltage including switching ripple at the output of the inverter generating system. In addition, it is necessary to have an accurate voltage measurement when the situation rapidly changing the grid impedance is caused by the input of serial impedance of transformer and line impedance as well as Grid Fault Device. In this paper, We propose a new detection method of grid voltage to calculate accurately the r.m.s voltage of the grid connection point along the standard required by the low voltage regulation. We verified performance through simulation grid fault device.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.1
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• pp.1-10
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• 2008

In order to evaluate performance of anti-vibration gloves, it is necessary to measure the transmitted vibration to the hand and the applied forces at the same time while gripping the vibrating handle. In the study a system was developed to measure both the vibration and the forces. The system consists of a measurement handle with eight strain gauges and two accelerometers and a PC-based system with a software for signal processing, evaluation of the hand-transmitted vibration and for control of applied forces in the pre-determined range. The handle was installed on the vibration shaker which is strong enough so as not to be affected by dynamic coupling with the hand-arm. Whole procedure of ISO 10819:1996 to determine the vibration transmissibility of anti-vibration gloves was programmed into the system. As an example of the application, three subjects joined the test to get vibration transmissibilities of 9 anti-vibration gloves where each glove was tested twice a subject. Average and standard deviation of the corrected vibration transmissibility were also calculated. All tested gloves fulfilled criterion for M-spectrum($\overline{TR_M}$<1.0), but one glove fulfilled criterion for H-spectrum($\overline{TR_H}$<6.0),

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.5
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• pp.609-615
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• 2016

Measuring similarity between two signals is a key element of the location template matching (LTM) method which is one of impact source localization technique. As a measure of similarity, the correlation coefficient is most widely used, and the group delay based method is recently proposed to improve the accuracy of finding the impact source. In practice, the LTM method assumes that the similarity between two signals decreases as the distance between two corresponding impact points increases, where the distance between two neighboring impact points defines the grid spacing. In this paper, it is shown that this assumption is not always true but the correlation coefficients fluctuate forming a main robe and many side robes as the distance between two neighboring impact points increases. On the other hand, the standard deviation of group delay sharply increases with a small increase of the grid spacing. These are demonstrated by using a simple cantilever beam. Based on these findings, an optimal way of implementing the LTM method may be suggested by combining the correlation coefficient and the group delay based approaches.

• Journal of Korea Multimedia Society
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• v.11 no.8
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• pp.1043-1050
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• 2008

XML has become a standard for data representation and exchange on the Internet. With a large number of XML documents on the Web, there is an increasing need to automatically process those structurally rich documents for information retrieval, document management, and data mining applications. In this paper, we propose a new method to measure the similarity between XML documents by considering their structures and contents. The similarity of document's structure is found by a simple string matching technique and that of document's contents is found by weights taking into account of the names and positions of elements. The overall algorithm runs in time that is linear in the combined size of the two documents involved in comparison evaluation.

• Journal of Drive and Control
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• v.15 no.1
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• pp.1-9
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• 2018

The spool displacement of directional control valve can be considered as the standard signal to measure the bandwidth frequency of a directional control valve. When the spool displacement is not available, the metering-orifice system is implemented in this research as an alternative way of measuring the 90 degrees phase bandwidth frequency of the hydraulic directional control valve. The inertia effect on the transmission line oil induces the phase lead of the valve load pressure when compared with the phase of spool displacement. The capacitance effect of the oil induces the phase lag of the valve load pressure. The phase of the load pressure can be adjusted to be the same as that of the spool displacement by controlling the opening area of the metering orifice. A series of experiments were conducted to verify the effectiveness of the metering orifice. The 90 degrees phase bandwidth frequency measured from the valve load pressure was significantly deviated in some cases from the frequency of the spool displacement. The metering orifice was hard to be applied to measure the -90 degrees phase bandwidth frequency of the high precision.

• Journal of Nutrition and Health
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• v.1 no.2
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• pp.87-91
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• 1968

Food and nutritional survey was made on two kinds of milk (one: 30 samples of bottled milk, the others: 30 samples of prepared milk), which are bottled market cow milk in Seoul city to examine the general ingredients, adulteration and degeneration. The results of survey indicated that the bottled milk delivered to home is relatively better than the prepared milk from the view point of food and nutrition. Moreover the quality of the prepared milk is poor because of adulteration through adding water or skim milk powder in order to increase quantity, consequently the prepared milk is under the nutritional standard. However it indicated that some of the bottled milk are rather inferior from the view point of food and nutrition, so certain measure is required for improving the quality of bottled and prepared milk. Most of the bottled milk and the prepared milk containing Coli-form bacteria have a possiblity to harm the citizen's health as a medium of infectious disease, such a fact is really serious problem from the view point of the national health, considering the general trend of milk consumption increase. It is urgent for us to take a scientific inspection on the sanitary management and take a formidable measure in handling of milk.

• Korea-Australia Rheology Journal
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• v.19 no.2
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• pp.75-80
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• 2007

The slotted plate technique has previously been shown to be a successful method for directly measuring the static yield stress of suspensions. In this study, we further establish the usefulness of the slotted plate device as a rheometer especially at low shear rates, taking advantage of the extremely low speeds of the slotted plate technique. Newtonian fluids, a shear thinning fluid, and yield stress fluids were tested using the slotted plate device and the results were compared with those from a commercial rheometer using different standard flow geometries. The relationship between the stress on the plate and the viscosity for the slotted plate device obtained by dimensional analysis (drag) predicts a linear relationship between the force at the plate and the plate speed, consistent with the experimental data. The slotted plate device can measure viscosities at very low shear rates. The apparent viscosity - shear-rate data obtained from the slotted plate device are complementary to those obtained using a commercial rheometer. That is : the slotted plate can measure viscosity in the shear rate range $10^{-7}<\dot{\gamma}<10^{-3}\;s^{-1}$, while the commercial rheometer measures viscosity at shear rates higher than $10^{-3}\;s^{-1}$.

• Geotechnical Engineering
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• v.3 no.4
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• pp.31-40
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• 1987

A helical probe test (HPT) suitable for in.situ soil exploration to a shallow depth and compaction control were developed and tested in different soils alongside traditional in-situ tests, including Standard Penetration Test (SPT), Cone Penetration Test (CPT) and in-situ density test. The helical probe test is economical and can be performed by a single person. The torque necessary to insert the probe Is used as a measure of soil characteristics. It was found that: the HPT test correlates well with the SPT test and the correlation is not sensitive to the soil type; the HPT test correlates well with the CPT test, but the correlation is sensitive to the soil type; the HPT torque provides a sensitive measure of relative compaction rind in-situ dry density of compacted soils; the reverse torque ratio decreases with increasing average grain sloe.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.469-472
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• 2002

We made ESD tester to measure ESD threshold voltage of semiconductor devices. The HBM ESD test is the most popular method to measure the ESD threshold voltage of MMIC. We use flyback method which is one of the DC-DC converter to get high ESD voltage. With flyback method, we can isolate the low voltage part from the high voltage part of HBM ESD tester. We use an air gap of the relay which is used for switch to satisfy the rise time of ESD standard(MIL-STll-883D). As a result, with the flyback method and the air gap of relay, we can make ESD tester whose parasitic components are minimized.

• Physical Therapy Rehabilitation Science
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• v.2 no.1
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• pp.57-61
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• 2013

Objective: To determine the correlation among three functional tests: single leg vertical jump (SLVJ), single leg hop for distance (SLHD), and single leg squat (SLSQ). Design: Cross sectional study. Methods: Twenty healthy men (n=10) and women (n=10) with no history of lower extremity dysfucntion participated in this study and performed in university research laboratory. The procedures consisted of a general warm-up, a task-specific warm-up, actual testing, and a cool down. All participants performed the three tests in random order. Each test was performed three times for the dominant and non-dominant lower extremity (LE). SLVJ, SLHD, SLSQ were measured using a standard tape measure. Results: Statistically significant difference was presented between dominant LE and non-dominant LE in each function test (p<0.05). The strongest correlation was between SLVJ and SLSQ, 0.939 and 0.883 for dominant and non-dominant LE, respectively (p<0.05). The weakest correlation was between SLVJ and SLHD, 0.713 for dominant (p<0.05) and between SLSQ and SLHD, 0.739 for non-dominant (p<0.05). Conclusions: There is a strong correlation between SLVJ and SLSQ, suggesting that each test measures similar constructs of function and can be substitutive, while weak correlation between SLSQ and SLHD suggest these two tests do not measure the same functional components and could be paired as outcome measures for the clinical assessment of LE function. It will provide physical therapist with scientific evidence for effective test combination of LE function assessment in clinical practice.