• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.9
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• pp.1818-1825
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• 2017

An Acoustic Doppler Current Profiler(ADCP) measures the current velocity and analyzes the degree of turbulence using Doppler effects of ultrasonic waves. Therefore, the autocorrelation or FFT spectrum estimates are obtained for extraction of current velocity in each spatial region. However, if the correlation method does not satisfy the assumption that the return signal spectra are symmetric Gaussian, the large bias errors can occur. Also, the accurate estimation of autocorrelation or FFT spectrum is difficult due to the short acquisition interval when the rapid changes of current velocity occur. Thus, in this paper, the estimation method of the autoregressive spectrum peak is suggested for the accurate current velocity measurement of both symmetric and asymmetric spectra. It is shown that estimation quality can be improved using the suggested method comparing with the conventional methods. Many return signals under the various environment are simulated and the results are compared and analyzed for evaluation of the suggested method.

• Journal of Korean Academy of Nursing
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• v.16 no.2
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• pp.13-28
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• 1986

The main purpose of th study was to evaluate he validity of Korean Pain Measurement Tool composed of pain terms. The specific purposes of this study were 1. to examine whether pain intensities of pain terms are congruent with those classified in three previous studies. 2. to evaluate the relative intensity of each term by panel of judges. 3. to explore the difference of ranks of pain terms according to the sex, education, and ages. One hundred and sixty normal individuals were selected by 2$\times$2$\times$4 sampling design. Sex (male, female), education (high school, college), and age (20s, 30s, 40s, 50s) were matched. Each individual was asked to rate the ranks of 3~8 pain terms in each subclass. The data measured by ordinal scale were transformed to the interval scale to compare with the pain intensities gained from the previous study. The pain ranks different from previous results were finally rearranged or cancelled through the consultation of 4 panel of judges and sunmed up to 91 pain terms in the scale. As a result, the ranks of pain terms within each of eleven subclasses among the twenty subclasses completely were congruent with the Previous pain ranks, while the ranks of nine subclasses were different from the previous pain ranks. In addition, there was significant relation between sex and pain ranks in skin punctuate pressure pain and cavity pressure. (sp : $\chi$$^2$=5.18 ø=0.26； cp : $\chi$$^2$=5.83 ø=0.24) In conclusion, seven terms from subclasses of inflammatory repeated pain, traction pressure pain, fatigue-related pain, fear-related pain, dull pain, and pulsation. related pain were cancelled. The ranks of four terms in subclasses of incisive Pressure pain and constrictive pressure pain were tentatively rearranged. Ranks of two terms in the tract pain were left as shown in the third study. As a result, six terms must be studied repeatedly for obtaining exact scores from ratio scale.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.41-46
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• 2006

This paper describes a marine watch system on a ship, which is aided by an image processing method. The system detects other ships through a navigational image sequence to prevent oversights, and it measures their bearings to maintain their movements. The proposed method is described, the detection techniques and measurement of bearings techniques are derived, and the results have been reported. The image is divided into small regions on the basis of the brightness value and then labeled. Each region is considered as a template. A template is assumed to be a ship. Then, the template is compared with frames in the original image after a selected time. A moving vector of the regions is calculated using an Excel table. Ships are detected using the characteristics of the moving vector. The video camera captures 30 frames per second. We segmented one frame into approximately 5000 regions; from these, approximately 100 regions are presumed to be ships and considered to be templates. Each template was compared with frames captured at 0.33 s or 0.66 s. In order to improve the accuracy, this interval was changed on the basis of the magnification of the video camera. Ships’ bearings also need to be determined. The proposed method can measure the ships’ bearings on the basis of three parameters: (1) the course of the own ship, (2) arrangement between the camera and hull, and (3) coordinates of the ships detected from the image. The course of the own ship can be obtained by using a gyrocompass. The camera axis is calibrated along a particular direction using a stable position on a bridge. The field of view of the video camera is measured from the size of a known structure on the hull in the image. Thus, ships’ bearings can be calculated using these parameters.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.2
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• pp.261-284
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• 2017

This paper describes the results of a low-frequency oscillation analysis using data measured in PMU installed in the KEPCO system, and the comparison with eigenvalues computed from the linear model. The dominant oscillation modes are estimated by applying various algorithms. The algorithms are: the extended Prony method; multiple time interval parameter estimation method; subspace system identification method; and spectral analysis. From the measurement data, modes of frequency 0.68[Hz] and 0.92[Hz] were estimated, and modes of frequency 0.63[Hz] and 0.80[Hz] were computed from the eigenvalue calculation. There was a difference between the mode estimated from measurement data and that from the linear model. This is possibly because of an error in the dynamic data of the KEPCO system used in eigenvalue calculation. Because wide area modes exist in the KEPCO system, these modes should be monitored continuously for the reliable operation of the system. In order to prevent total blackouts caused by wide area oscillation, moreover, contingency analysis should be performed in relation to this mode and appropriate measures should be established.

• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.134-142
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• 2005

This study is to find out how organic solvent will be propagated from painting inside the steel box girder of bridge. $2.9m{\times}3.0m$ of inside size of steel box girder is not suitable for painters to do his work comfortably and hygienically. Substance density(ppm)inside the space of the box unsatisfactory hygienical condition. Most of organic solvent(mainly toluene) came down to 0.5m in two minutes and 53sec. But personal protection for painter should be properly kept against flying this heavy organic solvent. longitudinally 27.1m in length is a cell unit of the whole length of bridge. Model XP-3l6A made in Japan is a main instrumentation adjusted to sense organic solvent especially toluene which can be measured up to 10,000ppm. Scenario analysis by computer program, safer release 2.0 has been performed first to estimate how the organic solvent will be propagated. And then actual test was done as a model. This has been measured for approximately five(5) minutes, with 30 sec interval. Actual measurement results showed much higher $10{\sim}20%$ than result analyzed by the computer program, meaning that this painting work can give worse effect to the worker who is painting inside the box girder of the bridge. The first meas urement level over the floor set up at 30cm height from the floor, because organic solvent was estimated to stay at the level. and then, they were measured at 1.0m, 1.5m level respectively, more.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.914-919
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• 2010

It is confirmed that as the distance measurements accuracy of the SDS-TWR(Symmetric Double-Sided Two-Way Ranging) based on CSS(Chirp Spread Spectrum) is considerably degraded due to frequency interference and it causes to severe errors in the localization applications. In this paper, the compensation algorithm based on error rate offset of distance measurement ($CA_d$) is proposed for the purpose to reduce the ranging errors due to by the SDS-TWR ranging problems. The $CA_d$ measures the distance values between two nodes by means of 1m interval about 1~25m distances in the SDS-TWR, and compensates the distance values using the parameters related to the distance compensation. From the experiments, it is analyzed that the $CA_d$. have reduced the distance error to average 95cm and maximum 526cm, and the distance error by the $CA_d$ was below about 60cm in the 25m distances. In particular, the performance of the distance measurements accuracy by the $CA_d$ is very high in LOS(Line Of Sight) environments.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.310-310
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• 2018

Generally, precipitation measurement were conducted with various authrities. Among these, the MOLIT conduct the hydrological survey for the water resource management such as flood and low-flow forecasting, drought countermeasure, streamflow management. There is totally 424 observatory were existed and each precipitation measurement were obtained and quality assuranced with 10-min interval. It could be arranged or estimated with nearby observatory and radar reflectivity when the total amount of precipitation are existed. The objective of the study is therefore to suggest the method to estimate missing data with rain radar reflectivity. To validate suggested method, 50 observartory were obtained, and the efficiency were analyzed with estimated and observed precipitation. As the result of the study, the suggested method has reliability, and can be used as a method for quality assurance.

• Physical Therapy Rehabilitation Science
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• v.7 no.2
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• pp.54-60
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• 2018

Objective: Persons with chronic stroke fall more often than healthy elderly individuals. The Timed Up and Go test (TUG) is used as a fall prediction tool, but only provides a result for the total measurement time. This study aimed to determine the optimal cut-off values for each of the 6 components of the TUG. Design: Retrospective study. Methods: Thirty persons with chronic stroke participated in the study. TUG evaluation was performed using a wearable miniaturized inertial sensor. Sensitivity, specificity, and predictive values were calculated using the Receiver Operating Characteristic (ROC) curve analysis for the measured values in each section. Optimal values for fall risk classification were determined. Logistic regression analysis was used to investigate the risk of future falls based on TUG. Results: The cut-off values of the 6 sections of the TUG were determined, as follows: sit-to-stand >2.00 seconds (p<0.05), forward gait >4.68 seconds (p<0.05), mid-turn >3.82 seconds (p<0.05), return gait >4.81 seconds (p<0.05), end-turn >2.95 seconds (p<0.05), and stand-to-sit >2.13 seconds (p<0.05). The risk of falling increased by 2.278 times when the mid-turn value was >3.82 seconds (p<0.05). Conclusions: The risk of falls increased by 2.28 times when the value of the mid-turn interval exceeded 3.82 seconds. Therefore, when interpreting TUG results, the predictive accuracy for falls will be higher when the measurement time for each section is analyzed, together with the total time for TUG.

• Journal of the Korea Organic Resources Recycling Association
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• v.19 no.4
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• pp.53-59
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• 2011

In this study, as a tool of evaluating biological stability of landfilled waste, influencing factors of $AT_4$ method was studied for standardizing the method. As influencing factors, initial lag time, exchanging period of $CO_2$ absorbing agent, and interval of pressure measurement were discussed, and also the relationship between content of dried food waste and $AT_4$ value were compared. Considering heterogeneity of landfilled waste and statistical error range of measurement, authors suggest that the criteria of stabilized landfill waste is $10mg\;O_2/g\;DM$ by $AT_4$ method.

• Phonetics and Speech Sciences
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• v.12 no.4
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• pp.73-80
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• 2020

In this study, a method for measuring the jitter component in continuous speech is presented. In the conventional jitter measurement method, pitch variabilities are commonly measured from the sustained vowels. In the case of continuous speech, such as a spoken sentence, distortion occurs with the existing measurement method owing to the influence of prosody information according to the sentence. Therefore, we propose a method to reduce the pitch fluctuations of prosody information in continuous speech. To remove this pitch fluctuation component, a curve representing the fluctuation is obtained via polynomial interpolation for the pitch track in the analysis interval, and the shift is removed according to the curve. Subsequently, the variability of the pitch frequency is obtained by a method of measuring jitter from the trajectory of the pitch from which the shift is removed. To measure the effects of the proposed method, parameter values before and after the operations are compared using samples from the Kay Pentax MEEI database. The statistical analysis of the experimental results showed that jitter components from the continuous speech can be measured effectively by proposed method and the values are comparable to the parameters of sustained vowel from the same speaker.