• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.34-42
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• 2017

Since existing nonintrusive appliance load monitoring (NIALM) studies assume that voltage fluctuations are negligible for load identification, and do not affect the identification results, the power factor or harmonic signals associated with voltage are generally not considered parameters for load identification, which limits the application of NIALM in the Smart Home sector. Experiments in this paper indicate that the parameters related to voltage and the characteristics of harmonics should be used to improve the accuracy and reliability of the load monitoring system. Therefore, in this paper, we propose an improved NIALM method that can efficiently analyze the types of household appliances and electrical energy usage in a home network environment. The proposed method is able to analyze the energy usage pattern by analyzing operation characteristics inherent to household appliances using harmonic characteristics of some household appliances as recognition parameters. Through the proposed method, we expect to be able to provide services to the smart grid electric power demand management market and increase the energy efficiency of home appliances actually operating in a home network.

• Journal of Advanced Navigation Technology
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• v.22 no.4
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• pp.271-278
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• 2018

For ionospheric correction of low earth orbiter (LEO) satellites using single frequency global navigation satellite system (GNSS) receiver, ionospheric scale factor should be applied to the ground-based ionosphere model. The ionospheric scale factor can be calculated by using a NeQuick model, which provides a three-dimensional ionospheric distribution. In this study, the ionospheric scale factor is calculated by using NeQuick G model during 2015, and it is compared with the scale factor computed from the combination of LEO satellite measurements and international GNSS service (IGS) global ionosphere map (GIM). The accuracy of the ionospheric delay calculated by the NeQuick G model and IGS GIM with NeQuick G scale factor is analyzed. In addition, ionospheric delay errors calculated by the NeQuick G model and IGS GIM with the NeQuick G scale factor are compared. The ionospheric delay error variations along to latitude and solar activity are also analyzed. The mean ionospheric scale factor from the NeQuick G model is 0.269 in 2015. The ionospheric delay error of IGS GIM with NeQuick G scale factor is 23.7% less than that of NeQuick G model.

• Journal of Korean Neurosurgical Society
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• v.55 no.3
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• pp.136-141
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• 2014

Objective : The aims of this study are to identify interpersonal differences in defining coordinates and to figure out the degree of distortion of the MRI and compare the accuracy between CT, 1.5-tesla (T) and 3.0T MRI. Methods : We compared coordinates in the CT images defined by 2 neurosurgeons. We also calculated the errors of 1.5T MRI and those of 3.0T. We compared the errors of the 1.5T with those of the 3.0T. In addition, we compared the errors in each sequence and in each axis. Results : The mean difference in the CT images between the two neurosurgeons was $0.48{\pm}0.22mm$. The mean errors of the 1.5T were $1.55{\pm}0.48mm$ (T1), $0.75{\pm}0.38$ (T2), and $1.07{\pm}0.57$ (FLAIR) and those of the 3.0T were $2.35{\pm}0.53$ (T1), $2.18{\pm}0.76$ (T2), and $2.16{\pm}0.77$ (FLAIR). The smallest mean errors out of all the axes were in the x axis : 0.28-0.34 (1.5T) and 0.31-0.52 (3.0T). The smallest errors out of all the MRI sequences were in the T2 : 0.29-0.58 (1.5T) and 0.31-1.85 (3.0T). Conclusion : There was no interpersonal difference in running the Gamma $Plan^{(R)}$ to define coordinates. The errors of the 3.0T were greater than those of the 1.5T, and these errors were not of an acceptable level. The x coordinate error was the smallest and the z coordinate error was the greatest regardless of the MRI sequence. The T2 sequence was the most accurate sequence.

• KIPS Transactions on Software and Data Engineering
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• v.2 no.10
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• pp.713-722
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• 2013

This paper proposes a method of using depth information to detect the hand region in real-time based on the cascade method. In order to ensure stable and speedy detection of the hand region even under conditions of lighting changes in the test environment, this study uses only features based on depth information, and proposes a method of detecting the hand region by means of a classifier that uses boosting and cascading methods. First, in order to extract features using only depth information, we calculate the difference between the depth value at the center of the input image and the average of depth value within the segmented block, and to ensure that hand regions of all sizes will be detected, we use the central depth value and the second order linear model to predict the size of the hand region. The cascade method is applied to implement training and recognition by extracting features from the hand region. The classifier proposed in this paper maintains accuracy and enhances speed by composing each stage into a single weak classifier and obtaining the threshold value that satisfies the detection rate while exhibiting the lowest error rate to perform over-fitting training. The trained classifier is used to classify the hand region, and detects the final hand region in the final merger stage. Lastly, to verify performance, we perform quantitative and qualitative comparative analyses with various conventional AdaBoost algorithms to confirm the efficiency of the hand region detection algorithm proposed in this paper.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.4
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• pp.65-73
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• 2002

It has been recognized that the damage control must become a more explicit design consideration. In an effort to develop design methods based on performance it is clear that the evaluation of the nonlinear response is required. The methods available to the design engineer today are nonlinear time history analyses, monotonic static nonlinear analyses, or equivalent static analyses with simulated nonlinear influences. Some building codes propose the capacity spectrum method based on the nonlinear static analysis(pushover analysis) to determine the earthquake-induced demand given by the structure pushover curve. These procedures are conceptually simple but iterative and time consuming with some errors. This paper presents a nonlinear direct spectrum method(NDSM) to evaluate seismic performance of structures, without iterative computations, given by the structural initial elastic period and yield strength from the pushover analysis, especially for MDF(multi degree of freedom) systems. The purpose of this paper is to investigate the accuracy and confidence of this method from a point of view of various earthquakes and unloading stiffness degradation parameters. The conclusions of this study are as follows; 1) NDSM is considered as practical method because the peak deformations of nonlinear system of MDF by NDSM are almost equal to the results of nonlinear time history analysis(NTHA) for various ground motions. 2) When the results of NDSM are compared with those of NTHA. mean of errors is the smallest in case of post-yielding stiffness factor 0.1, static force by MAD(modal adaptive distribution) and unloading stiffness degradation factor 0.2~0.3.

• Journal of Ocean Engineering and Technology
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• v.34 no.5
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• pp.294-303
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• 2020

This study discusses data collection, calculation of wind and wave-induced resistance, and speed-power analysis of an 8,600 TEU container ship. Data acquisition system of the ship operator was improved to obtain the data necessary for the analysis, which was accomplished using SPA (Ship Performance Analysis, Park et al., 2019) in conformation with ISO15016:2015. From a previous operation profile of the container, the standard operating conditions of mean draft were 12.5 m and 13.6 m, which were defined with the mean stowage configuration of each condition. Model tests, including the load-variation test, were conducted to validate new ship performance and for the speed-power analysis. The major part of the added resistance of container ship is due to the wind. To check the reliability of wind-resistance calculation results, the resistance coefficients, added resistance, and speed-power analysis results using the Fujiwara regression formula (ISO15016:2015) and Computational fluid dynamics (Ryu et al., 2016; Jeon et al., 2017) analysis were compared. Wind speed and direction measured using an anemometer were used for wind-resistance calculation and the wave resistance was calculated using the wave-height and direction-data from weather information. Also, measured water temperature was used to calculate the increase in resistance owing to the deviation in water density. As a result, the SPA analysis using measured data and weather information was proved to be valid and able to identify the ship's resistance propulsion performance. Even with little difference in the air-resistance coefficient value, both methods provide sufficient accuracy for speed-power analysis. The differences were unnoticeable when the speed-power analysis results using each method were compared. Also, speed-power analysis results of the 8,600 TEU container ship in two draft conditions show acceptable trends when compared with the model test results and are also able to show power increase owing to hull fouling and aging. Thus, results of speed-power analysis of the existing 8,600 TEU container ship using the SPA program appropriately exhibit the characteristics of speed-power performance in deal conditions.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.2
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• pp.50-62
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• 2016

With programmable applications that utilize sensors, such as global positioning systems and accelerometers, smartphones provide an unprecedented opportunity to collect behavioral data in an unobtrusive and cost-effective manner. This paper assesses the relative accuracy and reliability of the Future Mobility Sensing (FMS), a smartphone-based prompted-recall travel survey. We compared the data extracted from FMS with the data collected from the Korea Passenger Trip Survey (PTS), a traditional self-reported, paper-based travel survey. In total, 46 undergraduate students completed the PTS for seven consecutive days, while also carrying their smartphones with the activated FMS applications for the same time span. After completing the PTS, the participants validated their FMS data on the web-based prompted recall surveys. We then matched the validated FMS data with the PTS-based records. The FMS turns out to be superior in detecting short trips, which are usually under-reported in self-reported travel surveys. The reported PTS travel times are longer than for the FMS, suggesting that participants tend to overestimate their travel time in the PTS. This study contributes to the ongoing development of smartphone-based travel behavior data collecting methods.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.1
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• pp.1-9
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• 2015

This paper introduces the development of imaging luminance meter which measures the luminances of external/internal road tunnel. The developed imaging luminance meter complies with both L20 method and Veiling luminance method of the international standards, CIE88. In this paper the L20 method is mainly presented because most of tunnels currently adapt L20 method. The developed system has an embedded computer to operate at stand-alone. The system has a ethernet port, a heater, a fan, a defroster, a wiper and sun shielder. Compensation algorithm is applied for correcting non-linear responses to the luminance and integration time. The accuracy of measurement is less than 1% when it calibrated at the public certification institute. The developed system was also tested at the real field, road tunnel. The test results were very similar with the reference luminance meter and showed that the developed system operates well at the real field. Partial sensor saturations were happened to show the less luminance, because there were the high reflecting objects in the real field. Further study should be followed for high luminance measurement.

• Women's Health Nursing
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• v.4 no.3
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• pp.309-321
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• 1998

The purpose of this study was to analyze the contents related to health in the three major monthly women's magazine that was printed from March, 1997 to February, 1998. The unit of analysis was the section of health, living life, and reaing child. The total number of related story of health was 317. The analysis was done according to the target, health management, topics and the informer by using frequency and number. The findings are as follows : 1. The contents were categorized by target people. The number of items for women was 113(35.6%), child(17.4%), family(15.5), husband(4.7%) and others(26.8%). Others were the contents that are impossible to classify. 2. The number of items of contents by health management was the related to health maintenance and promotion 120(47.8%), health care when they were deviated from health 26(10.3%), and those of both attributes 105(41.8%). 3. The number of items of contents by topics was the related to the occurrence, prevention and treatment of various kinds of disease 41(12..9%), diet 37(11.7%), academic information 11.3%, women's disease 10.4%, the effect of foods 6.0%, child's growth & development and child care 5.75, various kinds of therapy for health care 5.7%, sexual life 5.4% and exercise 4.7%. 4. The number of items of contents by informer was medical doctor 215(49%), lay person's case report or report of a struggle against a disease 12.3%, relevant organization of a related story(eg. family therapy research institute, physical therapist's or teacher's) 11.2%, and the contents of existing books or lecture 8.9%. Among those contents, only the one case from nurse or Korean nurses association as informer was founded, which is related to "skinship child care." In conclusion, this finding showed that women's magazine took a role as a important resource providing informations of health to women. it provides a challenge to the health professionals to have concerns on women's needs, and the content, source, and accuracy of the health related information and take part in the process producing information through such as screening and examining so as to give accurate information to women. Then women's magazine can take a role as a major resource for maintaining and promoting women's health. Finally, nurses's, who are professional health care providers, important and active role as informers toward the lay persons, especially for the women who are non-professional care givers at the family unit should be stressed. More active and continual monitoring and analyzing the contents related health in the mass media including magazine and Internet network in detail, and participating in establishing the system of adequate and precise information for women and lay persons from the nursing profession are required absolutely.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.4
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• pp.716-723
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• 2008

With rapid development of science and technology and recent widening of mankind's range of activities, development of coastal waters and the environment have emerged as global issues. In relation to this, to allow more extensive analyses, the use of satellite images has been on the increase. This study aims at utilizing hyperspectral satellite images in determining the depth of coastal waters more efficiently. For this purpose, a partial image of the research subject was first extracted from an EO-1 Hyperion satellite image, and atmospheric and geometric corrections were made. Minimum noise fraction (MNF) transformation was then performed to compress the bands, and the band most suitable for analyzing the characteristics of the water body was selected. Within the chosen band, the diffuse attenuation coefficient Kd was determined. By deciding the end-member of pixels with pure spectral properties and conducting mapping based on the linear spectral unmixing method, the depth of water at the coastal area in question was ultimately determined. The research findings showed the calculated depth of water differed by an average of 1.2 m from that given on the digital sea map; the errors grew larger when the water to be measured was deeper. If accuracy in atmospheric correction, end-member determination, and Kd calculation is enhanced in the future, it will likely be possible to determine water depths more economically and efficiently.