• Journal of the Korean Society for Railway
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• 제17권1호
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• pp.7-13
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• 2014

Stiffness variations and wave propagation/reflection in railway catenaries are the primary sources of contact loss between a pantograph and a railway contact wire. This paper analyzes which design parameter is more important for 200km/h conventional rail and 300km/h high-speed rail, in order to effectively reduce the contact loss. For the high-speed rail, the wave propagation and reflection in the overhead contact lines are more influential than the stiffness variation over a span. When the high-speed rail needs to speed-up, it is necessary to develop higher strength contact wires in order to increase the wave propagation speed. In addition, the dropper clamp mass should be reduced in order to alleviate the wave reflection. However, it is noted that the increase in the tension to a messenger wire could deteriorate the current collection quality, which contrasts with expectations. For the 200km/h conventional rail, the stiffness variation over a span is more influential than the wave propagation and reflection. Therefore, shortening span length, increasing the tension in the contact wire and optimizing the location of the droppers are recommended for a smoother stiffness variation over the span.

• Journal of Korean Academy of Nursing
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• 제36권2호
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• pp.381-388
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• 2006

Purpose: The purpose of this study was to analyze and assess the current situation of Korea's school health education program and to establish measures to efficiently carry out school health education in Korea. Method: The survey was conducted through the internet with the health educators of elementary, middle, and high schools nationwide to assess the current condition of school health education programs, and 2,459 samples were collected which accounted for 23.4% of the total respondents. Results: According to school health educators on the enforcement of health education, the higher the education became, the less the health education was enforced. The enforcement rate was 96.9% in elementary schools, 76.7% in middle schools, and 67.3% in high schools. The major reasons were found as difficulty in securing class time (54.5%) and other excessive workloads (20.9%). As a result of the health education awareness survey, over 99% answered that health education is needed, over 80% answered that the education requires independent health textbooks, and over 95% answered that health educators are suitable for the person in charge of the education. Conclusion: This study will be a useful in establishing a detailed policy on enhancing school health education in the future.

• Fashion & Textile Research Journal
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• 제24권5호
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• pp.557-566
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• 2022

This study aims to investigate Jinju silk companies, production items, and silk industry supporting projects from 2019 to 2021 in order to discuss the current status of the silk industry. The following are this study's methods: First, a list of Jinju silk companies that have been operating for the past three years (2019-2021) was prepared to investigate the current status of the Jinju silk industry. Second, an investigation was conducted into the representative products produced in Jinju over the past three years; this investigation was conducted using direct interview. Third, an investigation was conducted on the projects that supported the Jinju silk industry over the past three years, and the list of members of the Gyeongnam Textile and Jinju Silk Industry Cooperative Association-a facility of Gyeongsangnam-do Province, the Jinju City Hall brochure (2019), and the SMINFO(SMall business status INFOrmation System) were utilized for this purpose. The following are the results: First, Jinju silk companies are classified into four categories, namely weaving, dyeing, twisting, and designing companies. According to data from 2021, 83% (34 of 41) of silk companies were weavers. Second, the demand for solid fabrics has increased over the past three years. The demand for patterned jacquard fabrics in producing Hanbok and Western-style clothing has decreased. Third, support for the Jinju silk industry could be classified into five categories: support for the operation of silk research institutions, support for the diversification of Jinju silk, support for the promotion of Jinju silk, support for the operation of silk manufacturers, and others.

• Journal of Astronomy and Space Sciences
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• 제19권1호
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• pp.75-88
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• 2002

The climatological characteristics of the polar ionosphere is examined in terms of the ionospheric conductance and electric field. For this purpose, 109 days of measurements from the Sondrestrom incoherent scatter radar are utilized. By combining these two quantities, it is possible to deduce the overhead ionospheric current distributions. The ionospheric current density thus obtained is compared with the corresponding ground magnetic disturbance. Also examined is the effect of the field-aligned current on the ground magnetic disturbance, particularly on the D component Several interesting climatological characteristics about the ionosphere over the Sonderstrom are apparent from this study. (1) The conductance distribution is mainly due to solar EUV radiation during day-time On the other hand, the conductance distribution during the night-time is very low. (2) The conductance distribution one. the polar cap region during the day-time is controlled mostly by the solar EUV radiation, while it is extremely low during night-time wish the Hall and Pedersen conductances being 1.6 and 1.2 siemen, respectively (3) The region of the maximum N-S electric field tend to locate in the dayside sector. The E-W component of the electric field is stronger than that over Chatanika (4) The E-W auroal inospheric current (J/sub E/) is more important in the sunlit hemisphere than the night hemisphere. And a strong southward current is noted in the prenoon sector (5) There is a significant correlation between the overhead ionospheric current and the simultaneously observed ground magnetic disturbance. However, the assumption for the infinite sheet current approximation is far from realistic, underestimating the current density. And the correlation between ${\Delta}H$ and J/sub E/ is higher than the one between ${\Delta}D$ and J/sub N/ , indicating that field-aligned current affects significantly ${\Delta}D$.

• Journal of the Institute of Electronics Engineers of Korea SD
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• 제38권11호
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• pp.836-845
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• 2001

A Novel fully-differential bipolar current subtracter(FCS) and its application to current controlled current amplifier(CCCA) for high-accuracy current-mode signal processing were designed. To obtain full-differential current output, the FCS was symmetrically composed of two current follower with low current-input impedance. The CCCA to control output current by the bias current was consisted of the subtracter and a current gain amplifier(CGA) with single-ended current output.. The simulation result shows that the FCS has current-input impedance of 5 Ω and a good linearity. The CCCA has 3-dB cutoff frequency of 20 MHz for the range over bias current 100 $\mu$A to 20 mA. The power dissipation of the FCS and CCCA are 1.8 mW and 3 mW, respectively.

• Asia pacific journal of information systems
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• 제26권2호
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• pp.322-337
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• 2016

Research on information systems and software engineering has often neglected behavioral effects, which may play a role in decision making on software development. The current study addresses this issue by empirically investigating the behavioral roots of over-requirement in the context of a software development project via an experiment. The negative phenomenon of over-requirement refers to specifying a software system beyond the actual needs of the customer or the market, which overload the system with unneeded features. The research question addressed here is whether over-requirement is due in part to the emotional involvement of developers with the software features they developed because of behavioral effects. Previous studies have demonstrated that under the endowment, I-designed-it-myself, and IKEA effects, people become emotionally involved and overvalue physical items that they respectively possess, self-design, or self-create. The findings of our experiment show that participants over-valued features they were assigned to be responsible for, to specify, or to construct, thereby confirming that the three behavioral effects play a role in software development decisions and affect over-requirement. Thus, the study contributes to software development research and practice from the behavioral economics perspective, highlighting the roots of over-requirement.

• Journal of KIISE:Information Networking
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• 제30권5호
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• pp.573-580
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• 2003

Increasing user demand for the more bandwidths in wireless communications has motivated a new challenge to utilize the benefits of wireless ATM technology This paper focuses on how to provide IP services to a mobile user over wireless ATM networks. By enhancing the NHRP standard, several shortcomings are improved that are resulted from the naive combinations of Mobile IP over ATM and IP over wireless ATM. This paper presents a mobile location management algorithm that is referred to as the Mobile NHRP scheme. The mobile tracking procedure and the mobile locating procedure are explicitly defined in the proposed scheme. On the locating procedure, the source station may obtain the current location of the destination from NHSs(Next Hop Servers). Therefore the optimized connection can be setup directly. The total costs per move and per setup over ATM/IP overlaid networks are estimated.

• Proceedings of the KIEE Conference
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.961-963
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• 2002

When high temperature superconducting(HTS) tapes are wound on former for HTS cable application, their critical characteristics are likely to be degraded seriously because of mechanical stress. In this study, prior to fabricate prototype HTS cables, we investigated the variation of critical characteristics of HTS tapes according to their pitch angles. For this work, we prepared the samples of HTS tapes on the former of which diameter is 3cm. Pitch angles of HTS tapes are $0^{\circ}$, $00^{\circ}$, $20^{\circ}$, $30^{\circ}$, $40^{\circ}$, respectively. We applied current up to 160 $A_{rms}$ to HTS tapes and investigated E-I characteristics. The critical current of HTS tapes was decreased as pitch angle increased. In addition, when the applied current was beyond their critical current, the rate of resistance increase of HTS tapes was in proportion to their critical current. Finally, We concluded that the pitch angles affected resistance increase of HTS tapes as well as critical current.

• Journal of the Korean housing association
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• 제22권6호
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• pp.83-95
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• 2011

This study was conducted to guarantee elderly housing for the increasing number of elderly people over 85. It examined their preference of living with their children and continuously living in their current houses when they reach the age of 85. First, research shows that 69.8% of the elderly wish to live separately from their children in later years. Second, 61.9% of the elderly wish to continue to live in their current houses. Third, the elderly without a spouse, with lower levels of education and with a longer period of time in their current houses, prefer to live with their children. Fourth, the elderly who own a house, who have lived in their current house for a long time, who have a religion and who are satisfied with their houses, wish to continue to live in their current houses in later years. However, most of the houses have safety defects such as a difference of floor-level at the entryway, lack of gas and smoke detectors and slippery bathroom floors. Thus, the elderly need to be supported by providing proper housing renovations for their safety and wellbeing.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 한국조명전기설비학회 2009년도 추계학술대회 논문집
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• pp.51-54
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• 2009

Total monitoring device of leakage current in transformer can detects the flowing leakage current on the ground wire connected with the neutral point, and that is monitored at real-time by the transfer. If the over-flowing current is detected, Total monitoring device of leakage current in transformer will warn the administrator to prevent electrical accident. In this thesis, we are going to explain about Total monitoring device of leakage current in transformer. Also we measure leakage current and judge safety in customer.