• Journal of the Korean Society of Safety
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• v.39 no.2
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• pp.44-53
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• 2024

In addition to being used for ascending and descending to work locations, portable ladders are widely used as a substitute for work platforms when working at heights in homes and industrial sites. However, accidents continue to occur in industrial sites owing to structural instabilities of ladders and the negligence of safety measures by users. To prevent accidents involving workers using portable ladders, it is important to encourage workers to use them correctly through laws and regulations; however, establishing effective preventive measures that go beyond regulations can increase acceptance in industrial sites and maximize the effect of reducing industrial accidents. Therefore, this study conducts a fact-finding survey and portable safety ladder product analysis and collects stakeholder opinions to develop a Korean-style safety ladder that can replace step ladders with a high risk of accidents.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.1
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• pp.33-38
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• 1999

This paper proposes a translation approach for PLCs (Programmable logic controllers) converting ladder diagrams directly to native codes, and describes detailed steps of the method followed by performance evaluation. A general-purpose DSP (Digital signal processor) based implementation validates the approach as well. A benchmark test shows that the Proposed translation framework fairly speeds up execution in comparison with the existing interpretation approach.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.671-676
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• 2001

Reinforcement corrosion is major problem for those who own and maintain reinforced concrete structures exposed to chlorides. It is well understood that the form of corrosion is more problematic than corrosion found elsewhere, Because concrete has no apparent signs that there is anything amiss until the process of deterioration is relatively far advanced. The objective of this research is to develop the ladder system which monitors the corrosion of reinforcing steels in concrete. This system can be used to assess the corrosion condition and corrosion rate of steel in concrete, which can give timely repair and strengthening of steel in concrete structure.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.17 no.30
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• pp.153-160
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• 1994

In this paper, we present the application of knowledge-based system technique for generating of PLC ladder diagram The developed prototype system receives a time chart as an input and generates a ladder logic as its output This results in the computerization and intellegent processing of PLC programming. The system can be effectively applied to sequence control where the PLC programs need to be frequently changed and generated.

• Journal of the Korean Institute of Telematics and Electronics
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• v.17 no.1
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• pp.31-35
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• 1980

A mathematical formula for transfer functions of general multimesh ladder is introduced in terms of series branch impedances and shunt admittances. From the properties of the mathematical formula. a method finding transfer function is developed by reduction methods and the inspection method is also developed.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.46.2-46.2
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• 2015

Modern methods in determining the value of the Hubble constant are divided into two main ways: the classical distance ladder method and the inverse distance ladder method. The classical distance ladder method is based on Cepheid calibrated Type Ia supernovae (SNe Ia), which are known as powerful distance indicator. The inverse distance ladder method uses cosmic microwave background radiation, which emitted from the high-z universe, and the cosmological model. Recent estimations of the Hubble constant based on these two methods show a $2{\sim}3{\sigma}$ difference, which called the "Hubble tension". It is currently an issue in the modern cosmology. We have been working on the luminosity calibration of SNe Ia based on the Tip of the Red Giant Branch (TRGB), which is a precise population I distance indicator. We present the TRGB distance estimates of 5 SNe Ia host galaxies with the archival Hubble Space Telescope image data. We derive the mean absolute maximum magnitude of 5 SNe Ia and the value of the Hubble constant. Cosmological implications of our estimate will be discussed.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.11
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• pp.939-943
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• 2001

PLC(programmable Logic Controller)s essential components of modern automation systems encompassing almost every industry. Ladder Diagrams (LD) have been widely used in the design of such PLC since the LD is suitable for the modeling of the sequential control system. However, the synthesis of LD itself mainly depends on the experience of the industrial engineer, which may results in unstructured or inflexible design. Hence, in this paper, we propose a ladder diagram conversion algorithm which systematically produces LDs for PLCs based on discrete event models to enhance the structured and flexible design mechanism.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.2
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• pp.8-13
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• 2007

The purpose of this study is to reduced the weight of ladder boom and to improve the manufactor process by the section modification. The Conventional model consists of integral section stiffener, while the proposed model consists of truss type stiffener to reduce the weight of ladder boom and wind effector. In the two analysis models, one is based on the single boom, and the other is based in the coupling model of two booms. We present the analysis results for the case when applying the weight, bending and twisting moment and wind pressure. Finally, a comparison between these results is presented to show the performance of our method.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.3
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• pp.96-102
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• 2007

An Optimal shape design of the boom system in high ladder vehicles is performed using 3-D finite element method (FEM). Results of structural analyses providing displacements, stresses are implemented for the optimum shape design. Lanzcos algorithm is used for the modal analysis in order to find natural frequencies. The optimal shape including cross sectional thickness and length of the boom system is controlled by the subproblem method besed on displacement and Von Mises stress. It is found that a plenty of materials can be saved by using shape design optimization in high ladder vehicles. It is also found that the natural frequency is increased until 6th mode and maintained similarly or decreased after 6th mode.

• The Journal of the Acoustical Society of Korea
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• v.21 no.2
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• pp.102-109
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• 2002

This paper proposes a new design algorithm to optimize the withdrawal weighted SAW ladder devices, Withdrawal weighting on SAW resonators gives enhanced bandwidth and transition band characteristics, so an optimization algorithm was developed for ladder type SAW filters. To illustrate the validity of the technique, this method was applied to the design of RF band CDMA TX SAW filters, and the design results were confirmed to show good agreement with experimental performance.