• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1503-1505
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• 2005

The Cold cathode fluorescent lamp(CCFL) are widely used to illuminate the liquid crystal display(LCD). Ballasts are required for CCFL because the lamp need high starting voltage and behave negative dynamic resistant characteristics in the desired region of operation. Dimming methods of CCFL are used to pulse frequency modulation(PFM) or pulse width modulation(PWM). In this paper, CCFL driving and control circuit is designed by half-bridge type series and parallel resonant inverter that variable frequency modulation method to control the output voltage current. The validity of this study is confirmed from the simulation and experimental results.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.413-415
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• 1995

This paper presents a new approach in the design of multiple power output electronic ballasts for compact fluorescent lamps which power output range of 11W, 15W, 20W by using equivalent resistance and RLC equivalent circuit concept and frequency control. A multiple power output electronic ballast which adopts half-bridge inverter topology is set up to compare the results of PSpice simulation with experimental ones. Starting characteristics of lamp voltage, lamp current and light output are better than the existing electronic ballasts, and therefore is verified the validity of the proposed method.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.19 no.3
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• pp.217-234
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• 2015

In this tutorial the theoretical background of LQ optimal guidance is reviewed, starting from calculus of variations. LQ optimal control is then introduced and applied to missile guidance to obtain the basic form of LQ optimal guidance laws. Extension of LQ optimal guidance methodology for handling weighted cost function, dynamic lag associated with the missile dynamics and the autopilot, constrained impact angle, and constrained impact time is also described with a brief discussion on the asymptotic properties of the optimal guidance laws. Furthermore, an introduction to polynomial guidance and generalized impactangle-control guidance, which are closed related with LQ optimal guidance, is provided to demonstrate the current status of missile guidance techniques.

• Journal of Yeungnam Medical Science
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• v.35 no.1
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• pp.36-39
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• 2018

In the personalized medicine era, utilizing paraffin blocks in pathology archives for investigating human diseases has come into the limelight. This archived material with clinical data will reduce the research time and could prevent new patient recruitment to obtain tissue for research. However, the clause indicating the necessity of consent from human material providers in the Korean Bioethics and Safety Act has made the Institutional Review Board (IRB) deny permission to use paraffin blocks for research without consent, and alternatively to get the same before starting an experiment. Written consent may be waived off in studies using paraffin blocks with anonymous status or conditions not linked to personal information by applying the paragraph 3, article 16 of the current Bioethics and Safety Act. Also, the IRB should recommend researchers to preserve the blocks as medical records of patients in long-term archives.

• Journal of the Korean Society of Safety
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• v.34 no.4
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• pp.6-14
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• 2019

There are about 38,977 CNG cars and 247 natural gas vehicle charging stations in operation in order to improve the urban air environment. With the introduction of natural gas vehicles, the atmospheric environment, which was the main cause of air pollution in the metropolitan area, was remarkably improved. However, unlike these positive effects, CNG bus accidents, which occurred more than 10 times since 2005, have caused concern among the majority of citizens using public transportation. It is necessary to make a judgment on the feasibility and future direction of CNG pressure vessel safety management that can safeguard the safety of CNG pressure vessel at the time of starting. In this study, we investigates production and use of CNG vessel, the current status of safety management of CNG bus transportation companies & charging stations and then proposes measures to prevent accident recurrence and safety management based on the actual situation investigation and analysis.

• Journal of Industrial Convergence
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• v.12 no.1
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• pp.24-37
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• 2014

An increasing numbers ot enterprises are involving in the Contents marketing. The reason is that Contents Marketing owns the stronger influences on the market which relative to that of other media. In this research the aim is presenting of the effective schemes that suitable for the domestic contents marketing climate, through analytical research of current situations and pointing of potential issues of contents marketing progress. Enterprises may have the abundant and essential cognitions about the contents marketing before the starting of the contents marketing project. Then, it is useful to develop the correlative communication strategies, customers' management strategies and crisis-resolution strategies. All of that done may bring the functional benefits for the domestic enterprises investment in the contents marketing.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.41.2-41.2
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• 2019

The B-fields In STar-forming Region Observations (BISTRO 1 and 2) is a large program of the James Clerk Maxwell Telescope (JCMT) using SCUBA-2 and POL-2, starting in 2016. We aim to study the roles of magnetic fields in star formation by observing 32 fields of nearby low-mass and high-mass star forming regions. The angular resolution and the wavelength provided by JCMT (14 arcsecond at 850 micrometer) are ideal to investigate the intermediate scales of magnetic fields (1000-20000 au) associated in cold dense cores and filaments. We report the current status of this project and discuss the magnetic fields of the Serpens Main molecular cloud in which several filaments with various physical properties have been identified.

• Current Optics and Photonics
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• v.6 no.5
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• pp.473-478
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• 2022

To overcome the capture-range problem in phase-diversity phase retrieval (PDPR), a geometrical-optics initial-estimate method is proposed to avoid a local minimum and to improve the accuracy of laser-wavefront measurement. We calculate the low-order aberrations through the geometrical-optics model, which is based on the two spot images in the propagation path of the laser, and provide it as a starting guess for the PDPR algorithm. Simulations show that this improves the accuracy of wavefront recovery by 62.17% compared to other initial values, and the iteration time with our method is reduced by 28.96%. That is, this approach can solve the capture-range problem.

• Journal of Korean society of Dental Hygiene
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• v.21 no.3
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• pp.227-234
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• 2021

Objectives: The objective of this study was to investigate the relationship between smoking history and periodontal disease among the elderly in South Korea. Methods: The study subjects comprised 2,703 elderly people who underwent oral health examination as part of the 7th South Korea National Health and Nutrition Examination Survey (KNHANES; 2016-2018). Data were analyzed using frequency analysis, Rao-Scott chi-square test, t-test, and binary logistic regression analysis. Results: A complex sample logistic regression analysis showed that the odds for periodontal disease development were higher in past smokers (odds ratio [OR]=1.461; 95% CI=1.070-1.994) and current smokers (OR=1.601; 95% CI=1.011-2.536) than in lifetime non-smokers. Conclusions: Smokers must actively participate in smoking cessation programs and interventions starting from middle age.

• Smart Structures and Systems
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• v.32 no.5
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• pp.339-347
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• 2023

Both the first author and the company of the second author were involved, directly or indirectly, in the design stage of a permanent link between the bottom of the Italian peninsula and the nearby Sicily island. This ambitious project was left in stand-by from 2013 to 2023. The current political revival originates some thoughts on the updated desired performance of suspension bridges, without any immediate reference to that specific crossing. It is simply regarded as a starting point. After an update on recent worldwide realizations, the authors focus their attention on four basic aspects: the span length, the girder scheme, the foundation technology and the bridge runability. Eventually, structural control and monitoring aspects are discussed as potentially innovative options in designing suspension bridges with railway crossing.