• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.996-1006
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• 2017

Phasor Measurement Unit (PMU) placement is a crucial problem for State Estimation (SE) of the power system, which can ensure that the power network is fully observed. Further, the observation reliability problem of the system has been concerned in the operation conditions. In this paper, based on modified weighted adjacent matrix ($A_w$), an optimal placement method is proposed to solve simultaneously two problems involving the optimal PMU placement problem and the observation reliability enhancement problem of the system. The purpose of the proposed method is to achieve both the minimum total cost and the maximum observation reliability, with a focus on increasing the security of observability, strengthening the observation reliability of buses as well as enhancing the effectiveness of redundancy. Simulations on IEEE 14, 24, 30 and 57 bus test systems are presented to justify the methodology. The results of this study show that the proposed method is not only ensuring the power network having the observability effectively but also enhancing significantly the observation reliability. Therefore, it can be a useful tool for SE of the power system.

• Korean Journal of Childcare and Education
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• v.19 no.6
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• pp.39-54
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• 2023

Objective: This study aimed to develop a parent play interaction observation scale (PPIOS-Toddler) and analyze it in terms of item discrimination, reliability, and validity. Methods: The subjects of the study were 97 toddlers and mothers. This scale consisted of three categories, six domains and 22 items on a 5-point scale. For the item discrimination of the observation scale, an independent standard t-test was conducted to analyze the significant difference in average between the upper and lower groups for each item. The reliability of the observation scale was calculated by Cronbach's α, the intra-item agreement, and the validity was examined through content validity, the correlation between subdomains and total scores, and official validity using PICCOLO. Results: In item discrimination analysis, all items exhibited differences between upper and lower groups. The overall internal agreement for the observation scale was 0.95, with factor-specific internal agreement ranging from 0.83 to 0.95. The observation scale demonstrated notable correlations between total scores and sub-factors (0.45 to 0.93) and significant correlations with PICCOLO total scores (0.66 to 0.86). Conclusion/Implications: The study successfully verified the item discrimination, reliability, and validity of the Parent Play Interaction Observation Scale (PPIOS-Toddler).

• Korean Journal of Child Studies
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• v.32 no.5
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• pp.167-183
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• 2011

The purpose of this study is to develop a valid and reliable infant observation scale based on the national curriculum for childcare centers. The study was carried out using the final draft of the Infant Observation Scale for 1 year old infants. The scale consists of 42 items in 6 areas. Whereas the final draft of the Infant Observation Scale for 2 year old infants consists of 52 items in 6 areas. The subjects of this observation scale were 120 infants from the city of Busan. The results of the Infant Observation Scale for the 1 year old infant analysis for the purpose of test adequacy indecates that the internal consistency reliability is from .88 to .97. The results of the Infant Observation Scale for 2 year old infant analysis for test adequacy shows that the internal consistency reliability is from .76 to .97.

• Korean Journal of Child Studies
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• v.24 no.3
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• pp.135-149
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• 2003

This study aimed to develop an observation scale for assessing the quality of day care programs and to examine reliability and validity of the scale. Instruments included 3 self-assessment scales, the Evaluation Scale for Early Childhood Programs and an observation scale completed by 8 trained observers in 89 day care sites. Item analysis indicated that most items were acceptable in terms of item discrimination and item response distribution. Cronbach ${\alpha}^{\prime}s$ and inter-observer reliability were relatively high. Validity of the scale was evidenced by correlations between the observation scale and the criterion measure and inter-correlations among sub-areas of the observation scale. Scores on the observation scale were validated by quality ratings from self-assessment scores.

• Journal of Applied Reliability
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• v.3 no.2
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• pp.127-136
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• 2003

This paper investigates the effect of individual observations in regression models with MA(1) errors through the 'hat matrix' It shows that the first observation has the largest hat matrix diagonal component for $\theta$＜0 in the regression model with an intercept. This provides additional evidence for retaining the first observation in performing estimation in this setting. When the regression model goes to the origin and the independent variable has a deterministic trend, the last observation has the greatest leverage for │$\theta$│＜1 and may have potentially large impact on parameter estimation.

• Korean Institute of Interior Design Journal
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• v.25 no.3
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• pp.51-59
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• 2016

The technique for Eye-tracking is to trace the movements of pupils so that the eye's exploration response to be digitized. The procedure of Observation Experiment shows a mutual environmental characteristics between men and measuring devices. In order to improve the reliability and to secure the objectivity of the data acquired from eye-tracking, it is very important to analyze the procedures for the experiment to be prepared and the test data to be saved. Based on this viewpoint, the convergent exploration activities at the observation experiment with the objects of sport images were examined to find out what influences the context effect given by experimental environments have on this experiment. In addition, the starting time of attention affecting the reliability of observation data has been estimated. When the observation time is to be subdivided by the unit of second. The attention disperses for the individual characteristics to be appreciated. However, in case of analysis by the overall average, there was the problem that the section of attention dispersed to make it difficult to analyze the subjects' observation features. The study results made it possible to understand the physiological characteristics which were near unconsciousness, when there was an intensive attention for the first 3 seconds and the observation data were shown to be in ordinary range after 4 seconds. The analysis of observation with the focus of the intensive attention enabled the analysis with the first 3 seconds excepted so that it might approach the ordinary range of observation data. The distribution of attention for the first 3 seconds showed the intensive attention, which was on the center. The emergence of intensive attention and the overlapping of the centers can be considered as a context effect due to the correction for the preparing process of experiment. Accordingly, it is thought to be helpful to the security of objectivity and the construction of reliability of eye-tracking data to analyze the observation features shown after the deletion of the data for the first 3 seconds.

• Journal of the Korea Safety Management & Science
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• v.6 no.3
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• pp.77-86
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• 2004

Observational methods to evaluate postural load have an intrinsic week point that is the problem of reliability in observing postures subjectively, although they have been widely used in assessing risk factors of work-related musculoskeletal disorders in the industry. In this study, observational reliability was discussed based on reviewing several previous studies. Practical guidelines was presented to reduce the observational errors when using video recording for the assessment of risk factors. In addition, previous studies on observational reliability were summarized and analyzed according to body parts to be observed, media for observation, objective measures, analysis, statistics, etc. It is expected that this basic study can be used to increase the applicability and accuracy of the observational methods.

• Korean Journal of Child Studies
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• v.34 no.1
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• pp.141-159
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• 2013

This study was conducted in order to develop an observation scale for analyzing the responses of child and therapist in child-centered play therapy in terms of item discrimination, validity, and reliability. The observation scale was developed on the basis of child-centered play therapy literature, the author's experience of child-centered play therapy, the observation of video tapes of play therapy session, and discussions with child-centered play therapy experts. The participants in this study were 54 children aged from 4 to 9 years old who have emotional and behavioral problems, and 7 therapists who consult with the children. The reliability of factors, as measured by inter-rater reliability and Cronbach's', ranged from .72 to .77. The results of factor analysis identified 2 factors and 21 items associated with the reponses of the children, and 2 factors and 19 items associated with the responses of the therapists. The significant factors identified were as follows; (1) the child's response style; (2) the child's response content (adaptability, initiation, structuring, flexibility); (3) the therapist's response style, and (4) the therapist's response content (facilitative response, structuring, nonfacilitative response). In conclusion, these results demonstrated that the observation scale provides a valid and reliable means of analyzing the responses of child and therapist in child-centered play therapy.

• Journal of Wind Energy
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• v.14 no.3
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• pp.5-13
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• 2023

Floating LiDAR systems (FLSs) are used in many countries because they are easier to install than stationary weather towers, have low maintenance costs, and can be installed in deep sea areas. However, FLSs are rarely used in Korea due to a lack of clear evaluation criteria to verify the reliability and uncertainty of their measurements. This study is the first to verify the reliability of FLSs in Korea with one-year simultaneous observation of six lidar systems - two fixed and four floating systems - in sea areas of Gunsan and Yeonggwang. The reliability of FLSs measurement data was verified by comparison between fixed and floating systems. Moreover, differences between existing wind resource maps and the data observed from the six points were analyzed and wind resource maps were calibrated. The results show a return rate of more than 95 % of the observed data and strong correlations between fixed and floating systems (average R2 of 0.977). Additionally, errors in wind speed predictions to produce a wind resource map could be significantly reduced from 5.7 % to 0.6 % after calibrations with the observation data.

• Atmosphere
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• v.27 no.2
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• pp.235-249
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• 2017

This paper describes methodology verifying near-surface predictability of numerical weather prediction models against the surface synoptic weather station network (SYNOP) observation. As verification variables, temperature, wind, humidity-related variables, total cloud cover, and surface pressure are included in this tool. Quality controlled SYNOP observation through the pre-processing for data assimilation is used. To consider the difference of topographic height between observation and model grid points, vertical inter/extrapolation is applied for temperature, humidity, and surface pressure verification. This verification algorithm is applied for verifying medium-range forecasts by a global forecasting model developed by Korea Institute of Atmospheric Prediction Systems to measure the near-surface predictability of the model and to evaluate the capability of the developed verification tool. It is found that the verification of near-surface prediction against SYNOP observation shows consistency with verification of upper atmosphere against global radiosonde observation, suggesting reliability of those data and demonstrating importance of verification against in-situ measurement as well. Although verifying modeled total cloud cover with observation might have limitation due to the different definition between the model and observation, it is also capable to diagnose the relative bias of model predictability such as a regional reliability and diurnal evolution of the bias.