• Fire Science and Engineering
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• v.34 no.3
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• pp.8-17
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• 2020

In this study, the characteristics of HFIX insulated wire sheaths contaminated by pollutants were examined. KS C IEC 60811-1-3 standard was followed in performing the water-resistance wire tests. Pollutants were selected, and the specimens were exposed to the pollutants for a maximum duration of four weeks. The maximum tensile load and the elongation rate were measured each week. As the period of pollution exposure increased, the maximum tensile load of the specimens decreased by 6.22% and 6.52% at room temperature and high temperature, respectively, and 19.94% for specimens coated with a rust-proof lubricant. The elongation rate also decreased rapidly, such that the reductions in the properties of the sheath were significant. From the analysis of the surfaces using a scanning microscope, as the contamination period increased, structural changes such as perforation, split, and melting occurred, and the mechanical properties of the specimens decreased. Therefore, it is necessary to develop and follow an inspection cycle and periodically carry out repairs to prevent the deterioration of insulated wires.

• Journal of Korea Society of Industrial Information Systems
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• v.5 no.2
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• pp.47-55
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• 2000

To date many software engineering cost models have been developed to predict cost, schedule, and effort of the software under development. The COCOMO Ⅱ is well- suited for the new software development life cycle such as non-sequential and rapid- development processes. The traditional regression approach based on the least square criterion is the most commonly used technique for empirical calibration in the COCOMO Ⅱ model. It has a few assumptions frequently violated by software engineering data sets. The source data is also generally imprecise in reporting size effort, and cost-driver ratings, particularly across different organizations. And that the outlier for the source data is a peculiarity and indicates a data point. To cope with difficulties, in this paper, we propose a new regression method for calibrating COCOMO Ⅱ post-architecture model based on the minimum relative error(MRE) criterion. The characteristic of the proposed method is insensitive to the extreme values of the data in the empirical calibration. As the experimental results, It is evident that our proposed calibration method MRE was shown to be superior to the traditional regression approach for model calibration, as illustrated by the values obtained for standard deviation(^σ), and prediction at level LPRED(L) measures.

• Korean Institute of Interior Design Journal
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• v.21 no.3
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• pp.103-110
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• 2012

Interior Coordination is the activity of making characteristic living space by planning and harmonizing various interior elements. In modern society, the taste and needs of the residents are getting varied and segmented, and the role of interior coordination is getting more important because that reflects cultural codes and trends and satisfies residents' needs. This study aims to investigate awareness and needs about interior coordination targeting apartment residents, and to provide fundamental data that could attribute to the planning of unique and diverse residential spaces. Methods of study include the literature research and the empirical study. Elements of interior coordination were extracted through the literature review, and the questionnaire was developed using these elements. And then a survey was carried out targeting apartment residents of Busan. The result shows that most of the residents were much interested in interior coordination, and they recognized it's importance. They wanted to plan and select the elements by themselves, but were passive in actual execution because of the difficulties in execution methods and economical conditions. There were certain differences between the styles of their own houses and the preferred styles, but they did not try actively to reconcile the differences. Therefore, various methods of interior coordination should be developed and proposed which are easy and effective for actual execution, and various media should be provided by which residents could easily get informations on design elements. Also, the concept and method of interior coordination should be considered from the very first stage of residential planning, and the replacement and modification of interior coordination could be easily done according to the change of life cycle and life styles.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.143-151
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• 2018

In this paper, a novel hybrid configuration combining a phase-shift full-bridge (PSFB) and a half-bridge resonant LLC converter is proposed for the On-Board Charger of Electric Vehicles (EVs). In the proposed converter, the PSFB converter shares the lagging-leg switches with half-bridge resonant converter to achieve the wide ZVS range for the switches and to improve the efficiency. The output voltage is modulated by the effective-duty-cycle of the PSFB converter. The proposed converter employs an active reset circuit composed of an active switch and a diode for the transformer which makes it possible to achieve zero circulating current and the soft switching characteristic of the primary switches and rectifier diodes regardless of the load, thereby making the converter highly efficient and eliminating the reverse recovery problem of the diodes. In addition an optimal power sharing strategy is proposed to meet the specification of the charger and to optimize the efficiency of the converter. The operation principle the proposed converter and design considerations for high efficiency are presented. A 6.6 kW prototype converter is fabricated and tested to evaluate its performance at different conditions. The peak efficiency achieved with the proposed converter is 97.7%.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.321-327
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• 2006

This paper presents low power and high frequency design of instructions using ad-hoc techniques at transistor level for full custom and semi-custom ASIC(Application Specific Integrated Circuit) designs. The proposed design has been verified at high level using Verilog-HDL and simulated using ModelSim for the logical correctness. It is then observed at the layout level using LASI using $0.25{\mu}m$ technology and analyzed for timing characteristic under Win-spice simulation environment. The result shows the significant reduction up to $35\%$ in the power consumption by any general purpose processor like RISC or CISC. A significant reduction in the propagation delay is also observed. increasing the frequency for the fetch and execute cycle for the CPU, thus increasing the overall frequency of operation.

• Journal of Information Technology Services
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• v.15 no.4
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• pp.63-72
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• 2016

Critical infrastructure has been operating in a closed environment with a completely separate information system and in the private area. However, with the current ICT environment changes due to convergence and open platforms it has increased the threats and risks to critical infrastructure. The importance of cyber security is increasing in the infrastructure control system, such as the outbreak of Ukraine blackout in 2015 by a malicious code called 'black energy'. This thesis aims to recognize the importance and necessity of protecting the critical infrastructure service, designing a security framework reflecting environmental and characteristic changes, and analyzing the management system suitable for a security framework. We also propose a theoretical basis for constructing a new security framework by comparing and analyzing seven international security management system standards, such as NIST 800-82 and IEC 62443-2-1, which are used in the control system. As a result, the environment surrounding critical infrastructure changes with the characteristics of connectivity, openness, and finality was studied, and as a response to this, many scholars and institutions present critical infrastructure security frameworks as cycle enhancement type structures, risk management structures, and management domain expansion structures. In response, the security framework encompassing these structures, CISF (Critical Infrastructure Security Framework), was designed. Additionally, through the security related international standard and criterion analysis, as a newly designed security standard suitable for CISF, IEC 62443-2-1 is reviewed and suggestions are made.

• Development and Reproduction
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• v.14 no.3
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• pp.155-162
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• 2010

The trophectoderm is one of the earliest cell types to differentiate in the forming placenta. It is an important for the initial implantation and placentation during pregnancy. Trophoblast stem cells (TBSCs) develop from the blastocyst and are maintained by signals emanating from the inner cell mass. However, several limitations including rarity and difficulty in isolation of trophoblast stem cells derived from blastocyst still exist. To establish a model for trophoblast differentiation, we isolated TBSCs from human term placenta ($\geq$38 weeks) and characterized. Cell cycle was analyzed by measuring DNA content by FACS analysis and phenotype of TBSCs was characterized by RT-PCR and FACS analysis. TBSCs have expressed various markers such as self-renewal markers (Nanog, Sox2), three germ layer markers (hNF68, alpha-cardiac actin, hAFP), trophoblast specific markers (CDX-2, CK7, HLA-G), and TERT gene. In FACS analysis, TBSCs isolated from term placenta showed that the majority of cells expressed CD13, CD44, CD90, CD95, CD105, HLA-ABC, cytokeratin 7, and HLA-G. Testing for CD31, CD34, CD45, CD71, vimentin and HLA-DR were negative. TBSCs were shown to decrease the growth rate when cultured in conditioned medium without FGF4/heparin as well as the morphology was changed to a characteristic giant cell with a large cytoplasm and nucleus. In invasion assay, TBSCs isolated from term placenta showed invasion activities in in vivo using nude mice and in vitro Matrigel system. Taken together, these results support that an isolation potential of TBSCs from term placenta as well as a good source for understanding of the infertility mechanism.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.6
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• pp.118-124
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• 2009

In order to know the range of install possibles of the horizontal stay without general stay, strength characteristic tests were performed for the Vertical and 80[$^{\circ}$] inclined concrete poles. From the results of one cycle strength tests, the safety factors were 2.8, 2.5 and 2.1 for the poles of general load, heavy load and high strength load, respectively. However, the crack was occurred when the bending bounds of upper part of pole was above 2[$^{\circ}$], and working load was similar to the rated load of pole at this time. Therefore, it could be concluded that the reinforcement by the installation of the stay and the support was necessary certainly, if the bending bounds of pole, which was installed on a solid foundation, are above 2[$^{\circ}$].

• Korean Journal of Optics and Photonics
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• v.1 no.2
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• pp.198-203
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• 1990

In this paper, a system has been proposed for the measurement of the spectral characteristic of semiconductor light sources driven by very short pulse currents. This system has been constituted a monochrometer of 600 groovedmm grating and of 275 mm focal length, X-Y recorder, scanning motor which enables the system to get the analog data, and amplifier coupled with peak detector. Especially, peak detector was used to convert the short pulse signal to continuous one. In order to verify the resolution with slit width, several slits were made by the hands. By using this system, the spectra of commercial LEDs, AlGaAdGaAs LD, and InGaAsPIInP BH-LD which were driven with pulse current (duty cy$e = 0.01) were measured. From these measurements, it has been shown that the proposed system has about 1 A1$\AA$ resolution and 10$\mu$W sensitivity.

• Women's Health Nursing
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• v.4 no.1
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• pp.47-66
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• 1998

The purpose of this study is to investigate the relationship between menopausal symptoms and spiritual well-being. In order to collect the research data, 350 questionaries were sent to the middle aged women who were 40-59 years old. During the collection period, March 20, 1977-April 20, 1977, 264 questionaries were collected. The questionnaire was prepared by using other researchers' scale, such as menopausal symptom scale by Neugarton and spiritual well-being scale by Paloutzian & Ellison. The research data were analyzed by various testable methods, such as frequency, t-test or ANOVA, and Pearson's correlation. The main results of this study were as follows ; Among the general characteristic variables, some variables have statistical significancy in explaining the difference of the menopausal symptoms. Such variables include age(F=5.17, p=0.002), years get married(F=4.23, p=0.002), number of children(F=3.08, p=0.028), income level of family(F=3.07, p=0.017), life style at leisure time(F=2.47, p=0.045). Some variables related to health condition could explain the differences of the menopausal symptoms among middle aged women. current menstruation stage(F=9.82, p=0.000), current health condition(F=9.82, p=0.000), and experience being operated in the past(F=9.82, p=0.000) are related to the menopausal symptoms. Serious menopausal symptoms which could be found in this study were 'back pain and joint pains(2.6)', nervousness(2.4), and psychosomatic symptom(1.97). Spiritual well-being inquiries could be classified into two subgroups, existential and religious. The mean score of existential well-being(3.04) was higher than that of religious well-being(2.76). Relatively higher existential well-being(3.10) was found in the women who have stable menstruation cycle. The age when the menopause began was related to spiritual well-being(F=3.29, p=0.046). The correlation between menopausal symptoms and spiritual well-being was statistically significant(r=-0.133, p=0.031). Based on the above results, nursing intervention program of menopausal symptoms is recommended in order to promote the health of middle-aged women.