• Journal of radiological science and technology
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• v.38 no.4
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• pp.355-363
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• 2015

Advancement in the medical field provides an opportunity for the development of medical equipment and also enable accurate diagnosis for the inspection and the treatment of diseases. The aging of equipment due to the frequent operation produce uncertainty in the patient exposure dose, so a quality control was implemented by establishing a safety management system on a regular basis. The x-ray tube voltage (kVp), which is directly involved in the patient exposure dose and the life of the equipment, needs periodic performance for the quality control, but it has a limitation due to the time and the cost. In this study, we proposed a new method for measuring the kVp with ease by using the Y and Cu to solve the problem of the time and cost. We also evaluated the usefulness and the effectiveness of the new method and its accuracy through the kVp measurement. After securing the condition, the amount of the tube current and evaluating the usefulness and effectiveness of kVp measured using Y and Cu. The density range used was at 0.5-1.0, kVp was in the range of ${\pm}10%$, then, we recorded the change in concentration as % of Y and Cu. This experiment showed that when Cu and Y was at 75 kVp, concentration was the same, and when the kVp was changed to 65 ~ 85 %, a gradual increase in concentration to 85 ~ 110 % was noted.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.169-173
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• 2015

This study is to predict the life exponent by measuring, over 7 years, the insulation resistance of high-voltage cables in 22 kV operation for 13 years. We found out the lifetime index in order to determine the time-dependent trend of deteriorating performance of power cables. The insulation resistances decreased according to elapsed time. We found that: the initial measurements of the cable systems were in agreement with the deterioration properties of the Arrhenius Law. By analyzing the life curve of the cable system, we also verified that the value of the life exponent (n) in the v-t characteristics defined by Weibull distribution has values from 10 to 11. When designing the cable system, the initial value of life exponent was chosen as 9 without any grounding. We have verified that the theoretical grounding based on the design safety of n=9 was actually the best one available. In the short term, we apply our research result to the diagnosis and evaluation of the power cables. In the long run, however, we plan to reduce the cost of the installation and management of cable systems in operation at power stations.

• The Journal of the Acoustical Society of Korea
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• v.39 no.4
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• pp.303-317
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• 2020

Extracorporeal Shock Wave Therapy (ESWT) is an innovative treatment in chronic musculoskeletal pain management and cardiovascular diseases. In this study, we surveyed the acoustic shock wave outputs from the domestically used focal type ESWT devices. The survey data were collected through 30 technical documents registered to the Ministry of Food and Drug Safety (MFDS), Rep. Korea. The results show that the focusing geometry varies largely, 5 mm to 65 mm in the focal length, 3 mm to 30 mm in focal width, and 4 mm to 108 mm in focal depth. The maximum positive pressure (P+) ranges from 7 MPa to 280 MPa, the focal Energy Flux Density (EFD) from 0.0035 mJ/㎟ to 35 mJ/㎟, and the energy per pulse (E) from 0.737 mJ to 80.86 mJ. All domestic PE-type (five) and one EM-type domestic devices included in the analysis of the correlation between P+ and EFD are shown to be far beyond the usual ranges and do not comply with expected correlation so that the reliability of their data was suspected. For the suspected, post-performance tests are required by a recognized testing agency. MFDS guidelines need to be revised so that the pass criteria for the shock wave acoustic outputs can be based on the clinical tests for indications.

• Journal of the Korean GEO-environmental Society
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• v.11 no.12
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• pp.47-56
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• 2010

The construction of new roads and the consistent extension of already-existing roads or the line-shape revision of those roads are increased with the governmental investment to SOC facilities currently. Accordingly, the road cut slopes are in the trend of rapidly increasing. As the road slope has increased, a lot of human and property damages has entailed consequently and in the local case, numerous studies have carried out aiming at minimizing this damages caused by the rockfall and landslide. In general, standard falling rock prevention facility has employed for most of the local road slope based on "Guide for Installation and Management of Road Safety Facilities" published by MLTM(the Ministry of Land, Transport, and Maritime Affairs) but profound doubt has raised as to whether this rockfall prevention facility would function properly enough to prevent rockfall efficiently without any damages in case of actual occurrence of rockfall. In addition, it is a reality that in most cases, such work is relied on overseas technology as a whole as the local technical level is low and in case of rockfall prevention net, it is judged that a study on rockfall prevention net that is able to endure more powerful rockfall energy is required as the problem including net bursting is taken place as a result of enough bearing force being failed to be demonstrated due to its partial weak point(not uniformly made). Under this background, in this study, three kinds of model depending on mesh size of expanded metal that is considered to have an adoptability as rockfall prevention net, as target are selected and characteristics depending on mesh size of expanded metal is intended to be researched through a pull-out test performance by using pull-out test equipment rockfall prevention net.

• Journal of Korean Society of Transportation
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• v.30 no.6
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• pp.27-36
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• 2012

In Korea, 28,641 cases of traffic accidents were caused by drunk driving in 2010. These statistics accounted for 12.62% of total number of traffic accidents. Moreover, the percentages of deaths and injuries from them were nearly 15% of those from whole traffic accidents. While police has emphasized enforcement efforts in order to reduce drunk driving, culture generous to drunk driving in addition to the absence of an appropriate intervention system for habitual drunk drivers have contributed to the increasing number of the drunk driving accidents in Korea. This study examined specific behavioral changes in drunk driving by comparing drivers' behavior pattern in non-alcoholic condition to those in alcoholic condition, using a psychomotor test and a driving simulator. In the psychomotor test measuring participants' reactions to the target stimulus, it was revealed that participants' correct responses were decreased, false responses were increased, and no responses also were increased after drinking. Furthermore, in the driving simulator performance after drinking, not only driving speed was faster but also the deviation of an accelerator pedal pressure and of the vehicle's lateral position were much increased. These results indicated that alcohol consumption would impair visio-cognitive ability and deteriorate driving safety. Finally, the implications and limitations of our findings and suggestions for the future research were discussed.

• Journal of the Korea Institute of Building Construction
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• v.21 no.5
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• pp.433-443
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• 2021

Value Engineering(VE) is an organized effort to create the most value through a functional analysis and creation of alternatives. Depending on the VE job plan, a VE Workshop must be performed in a certain place within a certain period of time. A VE Workshop, which is an organized activity that aims to create the best value through functional analysis and creation of alternatives, should be held in a certain place and at a scheduled time according to the VE job plan. In the Pre-Study, VE Study and Post-Study phases of VE, functional assessments, performance evaluations and idea evaluations are driven by variable management techniques and analysis methods, respectively. Generally, VE is executed for about 3 to 5 days in a particular place to create value. However, there are many problems associated with limiting all VE processes to a specific place and schedule. Moreover, in Korea, VE teams are required to finish all VE processes in a limited time because of the short duration of VE workshops, the necessity of which has been overlooked. Therefore, an efficient VE support system is required to resolve the problem of time and space limitations. In this study, a VE support system based on the Mobile environment was developed to support the VE Workshop process. This VE support system enables participants to review design documents, drawing sheets and all VE-related documents using mobile devices. After the Workshop, participants can conveniently rearrange the result(evaluation of function and ideas) at the workshop. Not only can the members of VE team can review the design documents, drawing sheet and all VE-related documents in the step before the workshop, but also the result(evaluation of function and ideas) of the workshop can be easily rearranged in the phase after the workshop under the developed supporting system using mobile devices.

• Journal of Korean Society of Disaster and Security
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• v.14 no.3
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• pp.29-38
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• 2021

Riverfront facilities are river space facilities used by citizens for the rest and convenience. Recently, although the importance of efficient maintenance of riverfront facilities is increasing, damaging facilities cases are increasing due to frequent floods. Currently, the inspections and diagnosis of river space facilities are limited to the main flood control facilities. And the standards for the maintenance and management of the riverfront facilities are insufficient. Utilization survey, which is the standard for managing river space facilities, is also inefficient in terms of manpower consumption and economic feasibility. This study uses mobile big data to classify river usage and conducts a survey for usability of river facilities to derive economic evaluation for usage performance. In the future, if economical method system that considers safety, usability, and durability is conducted and demanding analysis for each convenience facility is evaluated, it is expected that the efficient maintenance of riverfront facilities is perfomed better and the use of rivers by citizens will further increase.

• Journal of the Korea Society of Computer and Information
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• v.26 no.12
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• pp.247-254
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• 2021

As COVID-19 spread, non-face-to-face activities were required, and the use of service robots is gradually increasing. This paper analyzed the relationship between the increasing trend of service robots before and after COVID-19 through keyword search containing the keyword 'service robot AND non-face-to-face' over the past three years (2018.10-20219) using BigKines, a news big data analysis system. As a result, there were 0 cases in the first period (2018.10~2019.9), 52 cases in the second period (2019.10~2020.9) and 112 cases in the third period (2020.10~2021.9), an increase of 115% compared to the second period. The keywords commonly mentioned in the analysis of related words in the second and third periods were COVID-19, AI, the Ministry of Trade, Industry, and Energy, and LG Electronics, and the weight of COVID-19 was the largest, confirming that the analysis keyword. Due to the spread of Corona 19, non-face-to-face is required, and with the development of information and communication technology, the field of application of service robots is rapidly increasing. Accordingly, for the commercialization of service robots that will lead the non-face-to-face economy, there is an urgent need to nurture human resources that require standardization and expertise in safety and performance fields.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.115-123
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• 2021

In recent years, the automobile industry has been facing a major change with the introduction of new technologies represented by autonomous driving, electrification, and digitalization. Major domestic and overseas automakers are trying to use a systematic approach to customer satisfaction through user interfaces to provide customers with a special experience and value beyond just making products with high performance. This study proposes the Kano model as a systematic and qualitative research method for satisfaction. As a case study, 17 functions of a product were sorted (3 operation functions, 7 safety functions, and 7 convenience functions). This was done by analyzing the use case and the customers' requirements for a smart trunk system. 18 new functions were derived via creative ideation codes. In addition, a scientific analysis method is proposed for product quality attributes and the strength of customer satisfaction. Using the Kano methodology, 25 functions were classified into quality attributes: 18 attractive qualities, 3 one-dimensional qualities, and 4 complex qualities, which are combinations of one-dimension qualities and must-have qualities. The functions that have one-dimensional quality and complex qualities were found to have higher customer ratings than the functions that have attractive qualities. Based on this, enterprises could effectively reduce customer complaints and enhance customer satisfaction.

• Fire Science and Engineering
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• v.33 no.2
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• pp.145-154
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• 2019

The purpose of this study is to analyze the self-status of fire service personnel to identify their effect on self-efficacy and job satisfaction, and to improve the performance of their tasks in the field and perform their tasks efficiently. A survey of 177 current firefighters in the southern city of Gyeonggi Province conducted a correlation analysis and regression analysis through SPSS 22.0. The first study found that in relation to the self-status factor and the self-efficacy factor of firefighting services, the self-efficacy is rather high and the self-regulating effect is very high. Second, the effects of the self-status factor on the self-efficacy were significant in order of type Adult (A), type Free Child (FC), and type Adapted Child (AC). Third, analysis of correlation between self-status factors and job satisfaction factors showed inadequate correlation in all job satisfaction factors for Critical Parent (CP) types, and static correlation in all job satisfaction for Nurturing Parent (NP) types. Type Adapted Child (AC) was less satisfying to itself, to itself, to pay, to promote, to co-workers. Thus, the current strategic approach based on rationality needs to be strengthened by lowering the authority of the Critical Parent (CP) function in terms of self-status factors and enhancing the Adapted Child (AC) function in the lower satisfaction level of the parent.