• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.7 s.349
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• pp.50-59
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• 2006

The new communication paradigm is rapidly shifted from wireless mobile networks to an All-IP(Internet Protocol) network, led by service industry leaders and communication manufacturers. In this paradigm, providing authentication and session keys of a subscriber becomes one of the critical tasks because of IP open accessibility among heterogeneous networks. In this paper, we introduce authentication process procedure of heterogeneous wireless mobile networks and develop so-called IMAS(Integrated Mobile Authentication Server) which can securely inter-work among all mobile networks and support the legacy networks with backward compatibility. Especially, in designing IMAS, mobile authentication inter-working mechanism, key management technique, and other issues to be overcome are presented. We analyze and evaluate the performance of authentication algorithm which creates session key. A simulation environment of IMAS is established, and a performance(TPS; Transaction Per Second) result is analyzed and evaluated. It turned out that IMAS works among heterogeneous wireless mobile networks without compensating efficiency and functionalities of the legacy networks and decrease the entropy of data redundancy and data inconsistency among networks because of the integrity of the distributed Data Base(DB).

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.4
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• pp.403-415
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• 1999

To properly assess air pollution levels, application of quality assurance and quality control(QA/QC) is believed to be an essential step. In order to cope with such scientific principle, a field study was designed with an aim of comparing: 1) the methods of calibration for airborne pollutants and 2) the protocols developed for their measurements. Measurements were made at Han Yang University, Seoul during 29 May through 1 June 1998 under the management of the Division of Measurements and Analysis(DMA) of Korean Society for Atmospheric Environment(KOSAE). In this work, we report our results of intercomparative measurements on several gaseous criteria pollutants that were investigated mainly by the two institutes-Seoul National University(SNU) and the Korean Research Institute for Standards and Science(KRISS). Although measurements of major gaseous pollutants had been made routinely by many scientific institutes and organizations in Korea, most scientists involved in those studieswere obliged to do their experiments on the basis of their own procedural steps spaning from the preparation of gaseous standards to the methodological selections for the calibration. Hence, this campaign offered a unique opportunity to examine many important aspects on the measurements of these important gaseous pollutants. In the course of our study, we investigated the compatibility of data sets obtained by the two institutes in concert with reference data sets collected concurrently from a government-managed monitoring station. On the basis of our study, we conclude that different data sets made by different participants during this campaign agree well within the reasonable range of uncertainties.low, which indicated that during this period the potential acidity of precipitation was high but the neutralizing capacity was low. For Spring, pAi was very low but pH was slightly high. This was likely due to the large amount of $CaCO_3$ in the soil particles transported over a long range from the Chinese continent that were incorporated into the precipitation, and then neutralized the acidifying species with its high concentraton.

• Women's Health Nursing
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• v.27 no.3
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• pp.220-229
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• 2021

Purpose: The world saw a shift into a new society consequent to the coronavirus disease 2019 (COVID-19), which made home quarantine mandatory for a person in close contact with those who tested positive. For children, however, home quarantine was not limited only to themselves but parents, especially mothers were involved and required to quarantine. This qualitative study aims to explore and understand mothers' experience and their related psychosocial issues while caring for their school-aged children in Korea, who had to home quarantine after coming in close contact with COVID-19 positive individuals. Methods: Data were collected from October 2020 to January 2021 via in-depth, semi-structured interviews with nine mothers of children who had to home quarantine. Interviews were conducted face-to-face in an independent space near the participant's home or workplace (n=5) or via online platforms or telephone (n=4). The data were analyzed using thematic analysis through several iterative team meetings. Results: Thematic analysis revealed the following four themes: "Unable to be relieved due to uncertain situations surrounding me," "Blame and hurt toward me, others, and one another," "Pulling myself together for my children in my broken daily life," and "Changes in the meaning of life amid COVID-19." Conclusion: The narratives show that mothers experienced psychosocial difficulties while caring for their children during home quarantine. It is necessary to reduce the social stigma toward individuals in home quarantine and establish policies to ensure work-family compatibility for such mothers.

• Journal of Satellite, Information and Communications
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• v.12 no.3
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• pp.8-14
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• 2017

In 4G mobile communication, data services of mobile communication began to be provided in earnest. As a result, services such as the internet and multimedia including the video have become the main contents in the recent wireless traffic. Accordingly, research on 5G mobile communication with higher transmission rate has been actively carried out. 5G mobile communication is expected to be based on 4G for compatibility with existing terminals. Therefore, the simulation of this paper is based on 4G and we propose a new user scheduling scheme based on the Max throughput scheduling algorithm to improve system performance. This paper derives the frequency efficiency and fairness to compare the existing user scheduling algorithm with the proposed user scheduling algorithm. The proposed scheme shows better frequency efficiency and fairness than Max throughput in all situations. This paper contributes to the research for improving the system performance of 5G mobile communication technology, and I hope that it will help some of the ongoing standardization work.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.11
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• pp.1109-1117
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• 2017

In this work, a new control module and communication system associated with DSP are proposed to overcome the limitations of the contemporary prevailing PLC-based industrial equipment controller, and the performance of the proposed system was experimentally verified. In the light of this issue, a communication conversion scheme from RS-485 to Modbus, the dominant communication protocol used by PLC, was developed and shown to yield enhanced compatibility between devices. The proposed system allows for ~50％ cost reduction as well as downsizing of the industrial controllers. Furthermore, the design includes 24 V general digital I/O pins, which facilitate partial expansion of inputs and outputs. With Modbus communication implemented in DSP with the RS-485 interface, multi-to-multi communication may also be achieved.

• Korea-Australia Rheology Journal
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• v.19 no.3
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• pp.125-131
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• 2007

Biodegradable polymeric blends are expected to be widely used by industry due to their environmental friendliness and comparable mechanical and thermal properties. Poly (lactic acid) (PLA) and poly (butylene succinate) (PBS) are such biodegradable polymers which aim to replace commodity polymers in future applications. Since cost and brittleness of PLA is quite high, it is not economically feasible to use it alone for day to day use as a packaging material without blending. In this study, blends of PLA and PBS with various compositions were prepared by using a laboratory-scale twin-screw extruder at $180^{\circ}C$. Morphological, thermal, rheological and mechanical properties were investigated on the samples obtained by compression molding to explore suitability of these compositions for packaging applications. Morphology of the blends was investigated by scanning electron microscopy (SEM). Morphology showed a clear phase difference trend depending on blend composition. Modulated differential scanning calorimetry (MDSC) thermograms of the blends indicated that the glass transition temperature ($T_g$) of PLA did not change much with the addition of PBS, but analysis showed that for PLA/PBS blend of up to 80/20 composition there is partial miscibility between the two polymers. The tensile strength and modulus were measured by the Instron Universal Testing Machine. Tensile strength, modulus and percentage (%) elongation at break of the blends decreased with PBS content. However, tensile strength and modulus values of PLA/PBS blend for up to 80/20 composition nearly follow the mixing rule. Rheological results also show miscibility between the two polymers for PBS composition less than 20% by weight. PBS reduced the brittleness of PLA, thus making it a contender to replace plastics for packaging applications. This work found a partial miscibility between PBS and PLA by investigating thermal, mechanical and morphological properties.

• Journal of Powder Materials
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• v.17 no.2
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• pp.148-153
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• 2010

Thermal barrier systems have been widely investigated over the past decades, in order to enhance reliability and efficiency of gas turbines at higher temperatures. Yttria-stabilized zirconia (YSZ) is one of the most leading materials as the thermal barriers due to its low thermal conductivity, thermodynamic stability, and thermal compatibility with metal substrates. In this work, rare-earth oxides with pyrochlore phases for thermal barrier systems were investigated. Pyrochlore phases were successfully formed via solid-state reactions started from rare-earth oxide powders. For the heat-treated samples, thermo-physical properties were examined. These rare-oxide oxides showed thermal expansion of $9{\sim}12{\times}10^{-6}/K$ and thermal conductivity of 1.2~2.4 W/mK, which is comparable with the thermal properties of YSZ.

• Fire Science and Engineering
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• v.34 no.3
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• pp.58-66
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• 2020

Households are categorized as exceptions in the Fire Services Act; oftentimes, the 'Golden Time' is missed at the early stages of a fire, resulting in loss of life. As such, due to the high number of deaths caused by household fires, the Korean government amended the Fire Services Act to make it mandatory for all detached houses to be equipped with a fire extinguisher from 2017 onwards. Only 34.8% of households were properly equipped with a fire extinguisher, according to the 2018 factual survey on fire extinguishing facilities in households conducted by the Fire Department. Fire extinguishers are crucial in case of fire but many households avoid them because they are red and have a rough aesthetic, which does not suit the household environment. There is now a need for diverse simple fire extinguisher designs so that they can be used as interior décor in the household in the day-to-day while being available for putting out a fire when necessary. If fire extinguishers have designs that go well with any household space like other decorative ornaments, this will greatly increase consumers' motivation to purchase them. It is greatly anticipated that various companies will work on developing designs for fire extinguishers to commercialize them for households in the future.

• Journal of Family Resource Management and Policy Review
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• v.19 no.4
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• pp.71-94
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• 2015

The purpose of this study is to propose measures for social work practice to enhance the happiness of middle-aged married men and women by identifying the effects of family stress and social support resources (formal and informal support resources) on marital satisfaction among mid-life married couples. Subjects were selected through purposive sampling among married men and women aged between 40 and 59 and living in Seoul City and Gyeonggi province. The study results are follows. First, the average score of family stress was 3.06 points (SD=.56), slightly higher than the median value of 3 points. Of all subscales of family stress, the subjects experienced the most stress from family relationships, followed by financial problems, health and loss of families, and work-family compatibility. In regard to social support resources, the mean value of all social support resources categories was greater than the median. Among the subscales, informal support (family support and support from other people) was found to be higher than formal support. The level of marital satisfaction was higher than the median, and the score was 3.21 points (SD=.78). Second, in order to explore differences in marital satisfaction according to family stress and social support, differences in marital satisfaction were analyzed by grouping subjects who scored high, middle, and low levels of marital satisfaction. According to the results, marital satisfaction was statistically significantly higher in the group that experienced less family stress (F=6.25, p<.01). With respect to social support, marital satisfaction was statistically significantly higher in the group that received high social support (F=29.68, p<.001). Third, according to the analysis of factors affecting marital satisfaction in middle-aged married men and women, subjective economic status, family relationship stress, economic stress, and family support showed statistical significance. The higher the subjective economic status and the lower the family relationship stress and economic stress levels, the higher the marital satisfaction among middle-aged married men and women. In addition, the greater the family support, the higher the marital satisfaction. The results of this study underscore the need to improve family relationships in middle-aged married couples and to distribute family life education programs that can strengthen family support resources. For example, family relationship enhancement programs are currently performed, including "Family School for Middle-Aged Baby Boomers" and others as part of the Healthy Family Support Work regarding the promotion of marital satisfaction of middle-aged couples. In addition, continuing effort is warranted to include content on strengthening family support resources, maximizing the effectiveness of programs, and promoting service accessibility.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.9 no.3
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• pp.195-201
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• 2015

In this study, IT education contents have been developed based on the u-Learning approach for people with hearing impairment, focusing on allowing the user to learn from anywhere and anytime. Specifically, this study applies HTML5 to implementing IT education contents(JSP, Oracle) for the deaf because HTML5 enables the learner to access the contents through both web and mobile device on various platforms including android, Mac OS, and PC etc. The results of this study are as follows: First, the online computer courses are mostly supposed to be compatible with diverse types of mobile devices. However, some of the contents could not be run on applications residing in web and mobile devices because the contents tend to be developed using FLASH. HTML5 is the effective way to overcome the compatibility problem. Second, FLASH and HTML5 contents authoring tools have been compared in terms of their strong and weak points by applying the developed contents to those tools. The study also suggests that the future work would be needed in order to implement wide variety of event functions with HTML5. Lastly, design strategies enabling access through web and mobile devices have been analyzed in accordance with u-Learning design guidelines for the deaf and mobile application accessibility guidelines. However, in the latter case, the future work regarding design guidelines needs to be conducted to improve the educational accessibility depending on the level of impairment.