• KIISE Transactions on Computing Practices
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• v.21 no.3
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• pp.223-238
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• 2015

Ramp metering is the most effective and direct method to control a vehicle entering the freeway. This paper proposed the new density-based ramp metering method. Existing methods that use the flow data had low reliability data and can have various problems. Also, when the ramp metering was operated by freeway congestion, the additional congestion and over-capacity can occur in the ramp. To solve this problem with the existing method, the proposed method used the density and acceleration data of the freeway and considered the ramp status. The developed strategy was tested on Trunk Highway 62 west bound (TH-62 WB) in Minnesota Twin-City and compared with Stratified Zone Metering(SZM), which had been operating in the Twin-City freeway. To constitute the experiment environment, the VISSIM simulator was used. The Traffic Information and Condition Analysis System (TICAS) was developed to control the PTV VISSIM simulator. The experiment condition was set between 2:00 PM and 7:00 PM, Oct 5th, 2014 during severe traffic congestion. The simulation results showed that total travel time was reduced by 20% for SZM. Thus, we solved the problem of ramp congestion and over-capacity.

• The Korean Journal of Emergency Medical Services
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• v.14 no.1
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• pp.65-80
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• 2010

Objective : The objective of this study was to survey the job satisfaction and turnover intention of 119 emergency medical technicians who are fire fighters and, at the same time, provide emergency patients with first aid, to examine the correlation between their job satisfaction and turnover intention, and to provide basic materials for the human resource management of 119 emergency medical technicians. Method : The survey was conducted with 152 119 emergency medical technicians working at fire stations in an area of Gyeonggi-do during the period from July 15 to September 14, 2009. Job satisfaction was measured with a tool developed by Kim Sun-sim and Kwon Hye-ran (2002) based on the Index of Work Satisfaction, and turnover intention with the tool developed by Becker (2002) and translated and used by Cho Yeong-sook (2002). The questionnaire was composed of 11 questions on general characteristics, 35 on job satisfaction, and 4 on turnover intention, so a total of 50 questions. The reliability of the questionnaire was Cronbach's ${\alpha}=0.922$ for job satisfaction and Cronbach's ${\alpha}=0.854$ for turnover intention. Using SPSS 14.0, we obtained frequencies, percentages, means, and standard deviations, and performed independent two-sample t-test, one-way ANOVA, and Pearson correlation analysis, and Cronbach's ${\alpha}$. Results : 1) The mean score of the 119 emergency medical technicians' job satisfaction was 2.71, and that of their turnover intention was 2.64. By area of job satisfaction, the mean score was 3.44 for the area of job itself, 2.92 for the interaction area, 2.67 for the organizational demand area, 2.64 for the autonomy area, 2.14 for the wage area, and 1.91 for the working condition area, showing that emergency medical technicians were generally satisfied with their job itself but not with their working condition. 2) As to difference according to the 119 emergency medical technicians' general characteristics, statistically significant difference was observed in job satisfaction according to license type (F = 4.729, p < .010), and in turnover intention according to position (F = 3.768, p < .025). 3) The 119 emergency medical technicians' job satisfaction and turnover intention was in a negative correlation with each other (r = -.44, p < .000) in general, and by the sub-areas of job satisfaction, the correlation with turnover intention was high in order of the autonomy area (r = -.42, p = .000), interaction area (r = -.42, p = .000), job itself (r = -.35, p < .000), organizational demand area (r = -.30, p = .000), wage area (r = -.23, p = .000), and working condition area (r = -.21, p = .008). Conclusion : The 119 emergency medical technicians' job satisfaction showed a negative correlation with their turnover intention. This suggests that turnover intention can be reduced by improving job satisfaction. Furthermore, 119 emergency medical technicians' job satisfaction was high with the job itself, showing their high pride in their job, but was low with working condition and wage. Thus, it is necessary to enhance their job satisfaction by improving the 24-hour work system through supplementing manpower, compensating for overtime works, adjusting work hours per week, etc. These results are expected to be useful in making human resource management plans to lower turnover intention by enhancing 119 emergency medical technicians' job satisfaction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.477-477
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• 2008

For more than three decades, the gate dielectrics in CMOS devices are $SiO_2$ because of its blocking properties of current in insulated gate FET channels. As the dimensions of feature size have been scaled down (width and the thickness is reduced down to 50 urn and 2 urn or less), gate leakage current is increased and reliability of $SiO_2$ is reduced. Many metal oxides such as $TiO_2$, $Ta_2O_4$, $SrTiO_3$, $Al_2O_3$, $HfO_2$ and $ZrO_2$ have been challenged for memory devices. These materials posses relatively high dielectric constant, but $HfO_2$ and $Al_2O_3$ did not provide sufficient advantages over $SiO_2$ or $Si_3N_4$ because of reaction with Si substrate. Recently, $HfO_2$ have been attracted attention because Hf forms the most stable oxide with the highest heat of formation. In addition, Hf can reduce the native oxide layer by creating $HfO_2$. However, new gate oxide candidates must satisfy a standard CMOS process. In order to fabricate high density memories with small feature size, the plasma etch process should be developed by well understanding and optimizing plasma behaviors. Therefore, it is necessary that the etch behavior of $HfO_2$ and plasma parameters are systematically investigated as functions of process parameters including gas mixing ratio, rf power, pressure and temperature to determine the mechanism of plasma induced damage. However, there is few studies on the the etch mechanism and the surface reactions in $BCl_3$ based plasma to etch $HfO_2$ thin films. In this work, the samples of $HfO_2$ were prepared on Si wafer with using atomic layer deposition. In our previous work, the maximum etch rate of $BCl_3$/Ar were obtained 20% $BCl_3$/ 80% Ar. Over 20% $BCl_3$ addition, the etch rate of $HfO_2$ decreased. The etching rate of $HfO_2$ and selectivity of $HfO_2$ to Si were investigated with using in inductively coupled plasma etching system (ICP) and $BCl_3/Cl_2$/Ar plasma. The change of volume densities of radical and atoms were monitored with using optical emission spectroscopy analysis (OES). The variations of components of etched surfaces for $HfO_2$ was investigated with using x-ray photo electron spectroscopy (XPS). In order to investigate the accumulation of etch by products during etch process, the exposed surface of $HfO_2$ in $BCl_3/Cl_2$/Ar plasma was compared with surface of as-doped $HfO_2$ and all the surfaces of samples were examined with field emission scanning electron microscopy and atomic force microscope (AFM).

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.3
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• pp.253-259
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• 2004

The sheetwise cadastral map data needs to become a Serial Cadastral Map (SCM) database for the promotion of the reliability of cadastral surveying, for the efficient operation of the Parcel Based Land Information System, and for the convenient use of land information as well. A large amount of money and time are required for the editing process of producing SCM DB in accordance with the $\ulcorner$Guideline for the Production of Serial Cadastral Maps$\lrcorner$ by the Ministry of Construction & Transportation if any of field surveying techniques is accompanied by. In addition, a boundary line that extends to a neat line does not meet the counterpart of the neighboring map sheet at a point. Such cases frequently occur and are much dependent upon the decisions of individuals in charge of editing or inspecting. The core processes of the research, firstly overlay SCM produced by the edition of the sheetwise cadastral maps with Autodesk Map on orthophoto images, secondly adjust the parcel boundaries which are delineated over more than one map sheet, and lastly compare the original boundary coordinates and areas with the corresponding adjusted ones and calculate root mean square errors (RMSEs). The research aims at promoting the quality of SCM by minimizing the inconsistency of parcel boundaries by means of the comparative analysis of the calculated RMSEs.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.4
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• pp.287-296
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• 2015

Recent navigation systems provide quick guide services, based on processing real-time traffic information and past traffic information by applying predictable pattern for traffic information. However, the current pattern for traffic information predicts traffic information by processing past information that it presents an inaccuracy problem in particular circumstances(accidents and weather). So, this study presented a more precise predictive traffic information system than historical traffic data first by analyzing route search data which the drivers ask in real time for the quickest way then by grasping traffic congestion levels of the route in which future drivers are supposed to locate. First results of this study, the congested route from Yang Jae to Mapo, the analysis result shows that the accuracy of the weighted value of speed of existing commonly congested road registered an error rate of 3km/h to 18km/h, however, after applying the real predictive traffic information of this study the error rate registered only 1km/h to 5km/h. Second, in terms of quality of route as compared to the existing route which allowed for an earlier arrival to the destination up to a maximum of 9 minutes and an average of up to 3 minutes that the reliability of predictable results has been secured. Third, new method allows for the prediction of congested levels and deduces results of route searches that avoid possibly congested routes and to reflect accurate real-time data in comparison with existing route searches. Therefore, this study enabled not only the predictable gathering of information regarding traffic density through route searches, but it also made real-time quick route searches based on this mechanism that convinced that this new method will contribute to diffusing future traffic flow.

• Journal of the Korean Society for Railway
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• v.20 no.3
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• pp.311-319
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• 2017

The primary suspension system of a railway vehicle restrains the wheelset and the bogie, which greatly affects the dynamic characteristics of the vehicle depending on the stiffness in each direction. In order to improve the dynamic characteristics, different stiffness in each direction is required. However, designing different stiffness in each direction is difficult in the case of a general suspension device. To address this, in this paper, an optimization technique is applied to design different stiffness in each direction by using a conical rubber spring. The optimization is performed by using target and analysis RMS values. Lastly, the final model is proposed by complementing the shape of the weak part of the model. An actual model is developed and the reliability of the optimization model is proved on the basis of a deviation average of about 7.7% compared to the target stiffness through a static load test. In addition, the stiffness value is applied to a multibody dynamics model to analyze the stability and curve performance. The critical speed of the improved model was 190km/h, which was faster than the maximum speed of 110km/h. In addition, the steering performance is improved by 34% compared with the conventional model.

• Journal of radiological science and technology
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• v.44 no.5
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• pp.513-523
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• 2021

The purpose of this study was to discuss the required items and feasibility of medical records of radiological examinations performed by radiological technologists at medical institutions. An online survey was conducted to a total of 10,000 radiation-related workers, of which 1,026 (10.3%) responded. As a research method, self-made questionnaires were used. The online survey was conducted from September 10 to September 20, 2021 for the survey period. For response data, a Chi-square test was performed according to demographic characteristics using SPSS 27.0 version (IBM Inc., Chicago, Ill, USA), and it was judged to be significant when the P value was less than 0.05. The reliability of the questionnaire response was found to be Chronbach α=0.933. More than 90% of the medical records related to radiological examinations are necessary, and they answered that a curriculum, remuneration curriculum, and legal system for medical records should be prepared. More than 90% of the respondents agreed with the proposal of the Radiological Technologist Independent Act for legal preparation, and most of the information required for medical records is currently recorded in DICOM images. According to the demographic characteristics, the medical record requirement for radiological examination, curriculum, continuing education, and legislation were found to be higher with higher education and higher with longer working experience. In addition, most of the radiology departments showed a high demand for medical records, so most of them responded positively to the medical records requirements for radiological examinations. This study analyzed the medical record requirements for radiological examinations, and as shown in the results, medical record requirements for radiological examinations was found that most radiological technologists felt need for the new law and supported it. In addition, if the information recorded in the DICOM image is used, it is considered that medical records could be easily prepared without additional work by the radiological technologists.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.5
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• pp.542-549
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• 2019

Maritime accidents, such as the collision of a fishing boat in Incheon's Yeongheung Island, result in several casualties and property damage, even if they occur just once. To prevent such accidents, the Incheon Metropolitan Government is implementing safety management policies; further, they will provide ship collision warning services to prevent collisions on WAVE (Wireless Access in Vehicular Environment) communication-based ship safety operation pilot projects. However, to realize these objectives, a service standardization method is required that defines specific service types, configurations, and systems, which should be prepared based on user requirement analyses. In this study, a standardization method of WAVE communication-based collision warning service was developed by analyzing the requirements of the vessel operators subject to the services and related authorities. This will help improve the quality of service, ensuring professionalism and reliability through continuous improvement and efforts for standardization, as well as data derived from demonstration projects. Therefore, it is expected to help prevent maritime accidents to a considerable extent.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.705-713
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• 2021

Because the cage assembly serves as the launch platform, an accurate aim is essential to ensure shooting accuracy for the target. On the other hand, the abnormal rotation of the cage due to the directional errors of the K-MLRS has continuously caused quality problems. The quality problem of weapon systems may have a negative impact on the military's power loss. In this study, improvement plans were derived by examining the defects and analyzing the directional errors of the K-MLRS launcher. In addition, all possible causes of directional errors were derived from the flow diagram for cage directionality. Based on the results, the defense design through the software program was intended to prevent the loss of direction. Through this study, the signal error of the resolver was improved by preventing unspecific signals in the data. Furthermore, the directional judgment method was improved to minimize the impact of data distortion. Lastly, directional storage and verification methods were improved so that data for the cage rotation direction would not be affected by errors. For the design improvement method, the reliability was verified through the system applicability. This study is expected to be a reference for failure analysis and design for similar weapon systems in the future.

• Applied Chemistry for Engineering
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• v.31 no.6
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• pp.639-645
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• 2020

Among the components of redox flow battery (RFB), the electrode serves as a diffusion layer of an electrolyte and a path for electrons and also is a major component that directly affects the RFB performance. In this paper, chloric/sulfuric mixed acidwas used as a supporting electrolyte in RFB system with Fe2+/Fe3+ and V2+/V3+ as redox couple. The optimum electrode and activation temperature were suggested by comparing the capacity, coulombic efficiency and energy efficiency according to the electrode type and activation temperature. In the RFB single cell evaluation using 5 types of carbon electrodes used in the experiments, all of them showed close to the theoretical capacity to retain the reliability of the evaluation results. GFD4EA showed relatively excellent energy efficiency and charge/discharge capacity. In order to investigate the electrochemical performance according to the activation temperature, GFD4EA electrode was activated by heat treatment at different temperatures of 400, 450, 500, 600 and 700 ℃ under an air atmosphere. Changes in physical properties before and after the activation were observed using electrode mass retention, scanning electron microscope (SEM), XPS analysis, and electrochemical performance was compared by conducting RFB single evaluation using electrodes activated at each temperature given above.