• Journal of the Korean Society of Mechanical Technology
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• v.20 no.6
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• pp.763-769
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• 2018

In this research, in order to improve the heat retention of greenhouse, comparative analysis of the heat flux of the marketed multi-later insulating curtain was carried out. Experiments is conducted by fabricating a test apparatus for investigating the heat flux characteristics. The multi-later insulating curtain used for the experiment was compared using the P, N, S, U and T company, which are commercially available, and the heat flux due to temperature difference between the experimental apparatus and the outside was compared and analyzed. When the internal temperature of the experimental result is the maximum temperature $60^{\circ}C$, the heat flux of multi-later insulating curtain is T Co.($73.1W/m^2$) > S Co.($119.5W/m^2$) > U Co.($155W/m^2$) > N Co.($163.1W/m^2$) > P Co.($177.7W/m^2$). The heat flux means the quantity of heat passing through the unit time per unit area, and the higher the numerical value, the higher the quantity of heat passing through the multi-layer insulating curtain. This can be determined that high heat fluxes produce low heat resistance. Further, it has been found that the weight of the insulating curtain is largely unrelated to the heat insulating property, and the heat insulating curtain having a thickness containing a high internal air layer is excellent in the heat insulating property. In the future when manufacturing a heat insulating curtain, It is judged that it is desirable to manufacture a combination of heat insulating materials that contain a high internal air layer content and that can maintain the air layer even for long-term use while minimizing the volume.

• Animal Bioscience
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• v.34 no.1
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• pp.154-160
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• 2021

Objective: The effect of environmental enrichment on the behaviour of piglets in the nursery phase was evaluated. Methods: A total of 450 hybrid pigs (21 day old), including both females and uncastrated males, weighing approximately 6 kg, were distributed in a completely randomised design with 3 treatments and 3 replicates of 50 animals each. The treatments were: i) pen without environmental enrichment (control), ii) treatment consisting of continuous environmental enrichment (CEE) with rubber balls throughout the experimental period, and iii) treatment consisting of environmental enrichment with washed balls (EEWB) during the whole experimental period which were removed daily for washing. For the behavioural evaluation, 10 animals were randomly selected per replicate. The behavioural assessments were performed once a week, from 8 am to 6 pm, using images captured with a video camera. The data were submitted to non-parametric analyses, the means were compared using the Bonferroni test, and Person's correlations were also calculated. Results: A statistical difference (p = 0.001) was observed in the B5 (playful) behaviour; the animals in the EEWB treatment group had a higher frequency of this behaviour than animals in the control treatment group. The animals in the control group showed a higher frequency of B7 behaviour (lying down) (p = 0.026) than those in the EEWB and CEE treatment groups. The animals in the control group had a higher frequency of the B9 (belly nosing) behaviour than those in the EEWB group (p = 0.015). There was a tendency towards a higher frequency of behaviour B3 (walking in the pen) (p = 0.067) when the animals received the control treatment than treatments EEWB or CEE. Conclusion: The use of an enriching object improved the animal welfare and altered the correlation between the evaluated behaviours compared to the animals that did not have environmental enrichment.

• 한국사회정책
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• v.24 no.4
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• pp.63-87
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• 2017

Self-employed women are highly vulnerable to social risks like unemployment and poverty as job instability has increased in recent decades. Despite this, the Korean public policy focus has been on employees, not the self-employed. This may be closely linked to the legacy of the East Asian welfare model policy logic. Therefore, this study explores social risk levels by gender and employment status and examines the relation between social risks of self-employed women and the East Asian welfare model policy logic, through comparing-means analysis and ordered logit regression analysis using the 9th wave data of the Korea Welfare Panel Study Korea. The study yields evidence of divisions in social risk levels according to gender and employment status: that is, a gender difference, and a substantial gap between self-employed workers and regular employees. Furthermore, the findings of the study indicate that self-employed women — especially in small businesses — are more vulnerable to social risks than are self-employed men. This strongly supports the conclusion that the higher social risks of self-employed women in Korea are closely linked to the legacy of East Asian welfare model policy logic, which focuses on social protection for core workers and largely neglects women.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.5
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• pp.93-106
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• 2006

With the rapid growth of the wireless Internet communication, a new generation of mobile devices have made possible the broad distribution of mobile digital contents, such as image, music, video, games and applications over the wireless Internet. Mobile devices are rapidly becoming the major means to extend communication channels without copy Protection, usage rule controlling and authentication. As a result, mobile digital contents may be illegally altered, copied and distributed among unauthorized mobile devices. In this paper, we take a look at Open Mobile Alliance (OMA) DRM v2.0 in general, its purpose and function. The OMA is uniquely the focal point for development of an open standard for mobile DRM. Next we introduces features for an active content and illustrates the difference between an active content and an inactive content. Enabling fast rendering of an active content, we propose an OMA-based DRM framework. This framework include the following: 1) Extending DCF Header for supporting an selective encryption, 2) Content encryption key management, 3) Rendering API for an active content. Experimental results show that the proposed framework is able to render an active content fast enough to satisfy Quality of Experience. %is framework has been proposed for a mobile device environment, but it is also applicable to other devices, such as portable media players, set-top boxes, or personal computer.

• Korean Chemical Engineering Research
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• v.59 no.1
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• pp.60-67
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• 2021

This study presented techno-economic analysis of a 500 MWe oxy-coal power plant with CO2 capture. The power plant included a circulating fluidized-bed (CFB), ultra-supercritical steam turbine, flue gas conditioning (FGC), air separation unit (ASU), and CO2 processing unit (CPU). The dry flue gas recirculation (FGR) was used to control the combustion temperature of CFB. One FGR heat exchanger, one heat exchanger for N2 stream exiting ASU, and a heat recovery from CPU compressor were considered to enhance heat efficiency. The decrease in the temperature difference (ΔT) of the FGR heat exchanger that means the increase in heat recovery from flue gas enhanced the electricity and exergy efficiencies. The annual cost including the FGR heat exchanger and FGC cooling water was minimized at ΔT = 10 ℃, where the electricity efficiency, total capital cost, total production cost, and return on investment were 39%, 1371 M$, 90 M$, and 7%/y, respectively.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.4
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• pp.465-473
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• 2021

Since the past, ships have hoisted national flags as a means of indicating their nationality. Both domestically and internationally, laws and conventions related to the nationality and hoisting of the flag have been enacted because it is significant that the nationality of a ship is a matter of the jurisdiction of the ship. Nevertheless, there are differences in domestic and international regulations related to the hoisting of the flag of a ship, and if the flag is not hoisted irrespective of the intention, there may be a difference in interpretation as to whether or not the ship will be regarded unconditionally as a stateless ship. However, there is no disagreement locally or abroad about the necessity of indicating the nationality of ships. Therefore, I would like to propose a method to indicate and confirm the nationality of the ship by using wireless communication equipment with hoisting the flag as the only way to express its nationality, reflecting the situation of the era such as high-speed, larger and unmanned ship. Representatively, the method utilizes the automatic identification system(AIS), which is one of the equipment legally installed in the ship, and includes the ship's nationality in its information. If the nationality information is included in the AIS, nationality can be identified earlier and even from a distance, and there will not be instances of nationality not being identified because the flag is not hoisted or the flag is damaged. In addition, it is expected that the problem of nationality indication can be solved even when vessels are unmanned in future.

• Korea Journal of Hospital Management
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• v.25 no.4
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• pp.76-93
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• 2020

Purpose: In this study, the general characteristics of subjects who spent more than a certain amount of cost for general medical examination at the general hospital health promotion center, and the characteristics of disease, family history, and lifestyle (smoking, alcohol, physical activity, oral care) significantly differed in cost expenditure. We intend to provide basic data for establishing an appropriate marketing strategy for comprehensive examination. Method: It was conducted for users who received comprehensive checkups at a health promotion center at a general hospital in Seoul. The research data collection period is for 979 people who performed comprehensive examinations from January 2019 to December 2020. In order to carry out a comprehensive examination, a questionnaire before the examination was distributed to the subjects who visited the hospital to prepare, and the investigation was conducted in a way that the subjects of the investigation directly filled in. Results: There was a significant influence on the difference in expenditure for comprehensive examination according to the gender, age, and type of health insurance of the subject. In addition, there were significant differences in expenditure according to the presence or absence of disease and the type of family history. Weight loss, smoking history, smoking period, smoking frequency, drinking history, and drinking frequency all had significant effects on cost expenditure. Also, strength training and oral treatment management showed a significant effect on the cost of comprehensive examination. The number of flossing and interdental brushing was also found to have a significant effect. According to the results of multiple regression analysis, disease history (t=2.683, p<.01) and mean smoking frequency (t=4.315, p<.001) appeared to have the most significant effect on expenditure statistically. In other words, when the subject has a history of disease and when the average number of smoking is large, it means that the comprehensive examination cost is remarkably large. Conclusion: By using these contents, hospitals can further refine the marketing of the examination center. In addition, a more convenient and specialized process should be used by patients by linking the general medical department and the examination center well. In terms of management of operating medical institutions, this can be expected to create patients and increase profits.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.6
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• pp.597-604
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• 2020

This is a narrative research study conducted on the subject in order to understand the relationship between the meta-cognition, learning flow, and problem solving ability of nursing students in online class, and to find out the factors that influence problem solving ability, 88 students enrolled in 2nd and 3rd grade students who participated in online classes at G city universities. The analysis method was analyzed by means, standard deviation, t-test, one-way ANOVA, Pearson correlation, and stepwise multiple regression using SPSS version WIN 23.0. As a result of the study, the difference between learning flow and problem-solving ability according to general characteristics was significantly different depending on the perception of nurses after learning and the motivation for admission to the department of nursing, and the problem-solving ability was positively correlated with metacognition and learning flow. There was a relationship, and metacognition and learning flow were significant variables that influenced problem solving ability. The conclusion of the study is considered to be the basic data for the development of a systematic program that can increase the learning flow and meta-cognition to increase problem solving ability amid the change from nursing education to online classes, and to change the teaching method.

• Explosives and Blasting
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• v.39 no.1
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• pp.10-21
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• 2021

Brittle materials such as rocks and concretes exhibit large strain-rate dependency under dynamic loading conditions. This means that the mechanical properties of such materials can significantly be varied according to load velocity. Thus, the strain-rate dependency is recognized as one of the most important considerations in solving problems of blast engineering or rock dynamics. Unfortunately, however, studies for characterizing the dynamic properties of domestic rocks and other brittle materials are still insufficient in the country. In this study, dynamic tensile tests were conducted using the Hopkinson pressure bar apparatus to characterize the dynamic properties of Geochang granite and high-strength concrete specimens. The dynamic Brazilian disc test, which is suggested by ISRM, and the spalling method were applied. In general, the latter is believed to have some advantages in experiments under high-strain rate deformation. It was found from the tests that there were no significant difference between the dynamic tensile strengths obtained from the two different test methods for the two materials given. However, this was not the expected result before the tests. Actually, authors expected that there be some differences between them. Hence, it is thought that further investigations are needed to clarify this results.

• The Journal of the Korea Contents Association
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• v.21 no.8
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• pp.201-212
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• 2021

Curriculum content interest has been studied in terms of teachers rather than students in ways that help revise curriculum and develop textbooks. In this study, 227 first-year high school students were interested in what they learned in middle school and what they learned in high school, focusing on meaningful assumptions and contents for middle school and high school students. We analyze this difference in interest by gender and achievement level. According to the research results, first-year high school students, who are in the middle and high school transition period, have relatively high interest in themselves, such as youth development, compared to family needs or interest in family life. There were no gender differences, but there were differences in content interest depending on the level of achievement. This means that the content interest should be interpreted by considering various variables such as the development of learners, the situation of learners in the school-level transition period, and the entrance examination of universities. The results of this study will provide implications for future curriculum revisions, textbook development, and curriculum considerations, and will need to be carefully analyzed and utilized based on a learner-centered perspective.