• Research in Mathematical Education
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• v.18 no.3
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• pp.187-208
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• 2014

This study engages in the features of interaction in elementary school mathematics lessons as reflected in the class discourse. 28 pre-service teachers documented the discourse during observation of their tutor-teachers' lessons. Mapping the interaction patterns was performed by a unique graphic model developed for that purpose and enabled providing a spatial picture of the discourse conducted in the lesson. The research findings present the known discourse pattern "initiation-response-evaluation / feedback" (IRE/F) which is recurrent in all the lessons and the teacher's exclusive control over the class discourse patterns. Hence, the remaining time of the lesson for the pupils' discourse is short and meaningless.

• Journal of Positioning, Navigation, and Timing
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• v.5 no.4
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• pp.193-202
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• 2016

The Korea Augmentation Satellite System (KASS), which is under development in Korea as a Satellite Based Augmentation System (SBAS) is expected to broadcast SBAS messages to air space in Korea according to the international standards defined by the International Civil Aviation Organization (ICAO) and the Radio Technical Commission for Aeronautics (RTCA). Around 13 SBAS messages are broadcast in every second to transmit augmentation information which can be applicable to a wide area in common. Each of the messages requires a different update interval and time-out according to the characteristics, purpose, and importance of transmitted information, and users should receive and combine multiple SBAS messages to calculate SBAS augmented information. Thus, a time to take acquiring first SBAS position by users differs depending on broadcasting various SBAS messages with which order and intervals. The present paper analyzes the considerations on message scheduling for broadcasting of KASS augmentation information and proposes a design of KASS message scheduler using the considerations. Compared to existing SBAS systems, which have a wide range of service area, a service area of the KASS is limited to Korea only. Thus, the numbers of ionosphere grid points and satellites to be augmented are expected to be smaller than those of existing SBAS. By reflecting this characteristic to the proposed design, shortening of broadcast interval of KASS message is verified compared to existing SBAS and a measure to increase a speed of acquisition of user navigation solution is proposed utilizing remaining message slots. The simulation result according to the proposed measure showed that the maximum broadcast interval can be reduced by up to 20% compared to that of existing SBAS, and users can acquire KASS position solution faster than existing SBAS.

• Journal of Korean Academy of Nursing Administration
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• v.3 no.2
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• pp.123-136
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• 1997

The purpose of this study was to confirm the classification of nursing activity and to analyze the time of nursing workload in a new open hospital. The data were collected from 20 nurses working in 6 general nursing units by 4 trained observers. The tools used for this study were an observation recording sheet and a classification sheet of nursing activity. The classification sheet was constructed to be adaptable to each hospital system based on the instrument described in the literature. The results of the study are as follows : The direct nursing activities consisted of 6 sections, 33 subsections and the indirect nursing activities consisted of 14 sections, 53 subsections. The direct nursing activities included medication, measuring and observation, care of therapies, care of physical comfort, laboratory and treatment. The indirect nursing activities included preparation of medical utensils, collection of information and assessment, recording, phone communication, professional interaction related to patients, personal time, assigning work to staff, patient eaucation and training, interaction with lab, transfer of administration of utensils, checking physician's order, dietary service, management of pollution and contagion, guide direction. Nurses spent 127.6min for direct nursing activity during day duty. It was 24.5% of total nursing activity. Within that activity medication had the highest percentage of time(40.09%), followed by communication and education with patient(24.76%), measuring and observation (16.93%), laboratory and treatment (12.85%), care of therapies(3.21%) and care of physical comfort (2.16%). The time breakdown for indirect nursing activities is as follows ; the preparation of medical utensils 22.3%, collection of information and assessment 20.29%, recording 20.27%, phone communication 8.14%, professional interaction related to patients 7.33%, personal time 7.24%, with the remaining timeshared by staffing, patient education and training, interaction with lab, transfer of administration of utensils, checking physician's order, dietary service, management of pollution and contagion, guide direction. In the analysis of the relationships between the working time and the work allocation characters of the nurses(including nurse's experiences. nurse-patients ratio, nurse-rooms ratio, and character of nursing unit) ; There were no significant differences in direct-indirect nursing times between nurse's career years. There was significant difference in direct nursing time between assigned patient numbers. The nurses assigned larger number of patients spent significantly more time in direct nursing care than that of the smaller. On the other hand, there was no significant difference in indirect nursing workload between the assigned patient numbers. There were no significant differences in direct-indirect nursing time between an allocated patient's room numbers. There was significant difference in working time between working places. The nurse in the medical unit spent more time in direct nursing care than her counterpart in the surgical unit. However there was no difference in direct nursing time between two groups. The study results indicate that nurses spent less time in the direct nursing care than in the previous studies even though the hospital system has been modernized. On the other hand they spent much more time for the coordinating role within the interdisciplinary team and for the overlapping paperwork. Therefore it is recommended that patient oriented job description and more efficient usage of modernized utilities be made.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.4
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• pp.139-146
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• 2008

Conductors in overhead transmission lines are exposed under various environmental conditions for a long period of time, so that they may be slowly degraded due to air pollutant or thermal history. Aged conductors may reduce power system reliability and public safety. Therefore, diagnosis of aged conductors in service becomes more important concerns with respect to keeping power delivery stable with a proper capability, replacing aged conductors, or constructing a new line. In this paper, we posed a new method to diagnose the refurbishment life and estimate the remaining life of aged conductors by measuring dips. As analyzing some relations of conductor temperature, conductor current, and tension load, it could be verified that dip exactly shows mechanical tension loss for aged conductor. Based on several simulation results, it was shown that the proposed method may be effectively used to diagnose the refurbishment life or remaining one of overhead conductors.

• Journal of the Korean Institute of Telematics and Electronics
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• v.17 no.6
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• pp.33-37
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• 1980

The information display control system is designed and implemented on an automobile in which the conventional panel displays are replaced by electronic ones. The system hardware consists of three main parts, i. e., (i) the function select keyboard (ii) the central processing unit (iii) the displays, The system software consists of main routine and several interrupt service routine such as keyboaiuand display interrupt service routine:. The main routine handles various sensor inputs to generate the appropriate information for the driver such as running speed, available fuel quantity. coolant temperature, battery voltage, remaining distance to the destination , time of day, and so on. Finally the results of the field test of the system and some associated difficulties of realization problems are discussed.

• Journal of the Korean Operations Research and Management Science Society
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• v.42 no.2
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• pp.1-17
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• 2017

Based on increased popularity and use of social network services as a marketing tool, social commerce became an emerging trend in e-commerce platforms. Social commerce involves sellers offering potential consumers the products and services at a lower price in a limited time period. Through comparison of the performances of domestic social commerce websites, we found that the buying environment such as price, number of available products, and the remaining time period for sale has a significant difference influencing on the purchase decisions of consumers. This study aims to analyze the interaction effects and preference levels of four characteristics (price, discount rate, number of purchases and purchase time) by conducting choice-based conjoint analysis. Survey experiment was performed using a sample of 146 undergraduate and graduate students. The results showed that consumers importantly consider purchase time, discount rate, price, number of purchases in the order of their preference. Also, discount effect is more significant on purchase decisions than price effect and consumers distinguish less the differences among the buying environment characteristics in the closing days of purchase period. Customer segmentation using the preference levels of characteristics indicates that the preference levels have different effects in the purchase utility of each segment. The proposed customer segmentation and differences in feature utilities are expected to be valuable in forming future sales promotion strategies in social commerce.

• Smart Structures and Systems
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• v.23 no.3
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• pp.263-278
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• 2019

Moving train load parameters, including train speed, axle spacing, gross train weight and axle weights, are identified based on strain-monitoring data. In this paper, according to influence line theory, the classic moving force identification method is enhanced to handle time-varying velocity of the train. First, the moments that the axles move through a set of fixed points are identified from a series of pulses extracted from the second derivative of the structural strain response. Subsequently, the train speed and axle spacing are identified. In addition, based on the fact that the integral area of the structural strain response is a constant under a unit force at a unit speed, the gross train weight can be obtained from the integral area of the measured strain response. Meanwhile, the corrected second derivative peak values, in which the effect of time-varying velocity is eliminated, are selected to distribute the gross train weight. Hence the axle weights could be identified. Afterwards, numerical simulations are employed to verify the proposed method and investigate the effect of the sampling frequency on the identification accuracy. Eventually, the method is verified using the real-time strain data of a continuous steel truss railway bridge. Results show that train speed, axle spacing and gross train weight can be accurately identified in the time domain. However, only the approximate values of the axle weights could be obtained with the updated method. The identified results can provide reliable reference for determining fatigue deterioration and predicting the remaining service life of railway bridges.

• The Journal of Korean Academy of Prosthodontics
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• v.62 no.2
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• pp.140-145
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• 2024

Removable partial denture wearers are exposed to the risks that remaining teeth get damaged by caries, attritions, erosion, and fracture. In the case of damaged abutment tooth which should fit to Removable partial denture (RPD), the fabrication of surveyed crown is followed by the making of RPD. However, making new denture takes a long time, and needs several processes and costs. Also, patients should get used to new denture. If other abutment teeth and edentulous ridges provide the existing denture with support, retention, and stability, use of existing denture is considered clinically acceptable. In this situation, fabricating retrofit crowns to an existing removable partial denture makes patient use existing denture, cuts costs, and reduces discomfort. In this case, severely worn teeth were restored using monolithic zirconia crown which fit to an existing removable partial denture by CAD-CAM. Moreover, support, retention, and stability of the denture were improved, and both doctor and patient were satisfied with the result.

• Smart Structures and Systems
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• v.20 no.1
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• pp.11-22
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• 2017

The long-term effect of ambient temperature on bridge strain is an important and challenging problem. To investigate this issue, one year data of strain and ambient temperature of a long-span cable-stayed bridge is studied in this paper. The measured strain-time history is decomposed into two parts to obtain the strains due to vehicle load and temperature alone. A linear regression model between the temperature and the strain due to temperature is established. It is shown that for every $1^{\circ}C$ increase in temperature, the stress is increased by 0.148 MPa. Furthmore, the extreme value distributions of the strains due to vehicle load, temperature and the combination effect of them during the remaining service period are estimated by the average conditional exceedance rate approach. This approach avoids the problem of declustering of data to ensure independence. The estimated results demonstrate that the 95% quantile of the extreme strain distribution due to temperature is up to $1.488{\times}10^{-4}$ which is 2.38 times larger than that due to vehicle load. The study also indicates that the estimated extreme strain can reflect the long-term effect of temperature on bridge strain state, which has reference significance for the reliability estimation and safety assessment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.12
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• pp.2995-3002
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• 2000

The remaining life estimation for the aged components in power plants as well as chemical plants are very important beacuse mechanical properties of the components are degraded with time of service exposure in high temperature. Since it is difficult to take specimens from the operating components to evaluate mechanical properties of components nondestructive techniques are needed to estimate the degradation. In this study, test materials with 4 different degradation levels were prepared by isothermal aging heat treatment at 630$\^{C}$. And the DC potential drop method and destructive methods such as tensile, K(sub)IC and hardness tests were used in order to evaluate the degradation of 1-Cr-1Mo-0.25V steels. The objective of this study is to investigate the possibility of the application of DCPD method to estimated the material degradation, and to analyse the relationship between the electrical relationship between the electrical resistivity and the degree material degradation.