• 한국안전학회지
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• 제39권2호
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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.

• 제어로봇시스템학회논문지
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• 제5권1호
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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.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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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.

• 산업경영시스템학회지
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• 제17권30호
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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.

• 대한전자공학회논문지
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• 제17권1호
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• pp.31-35
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• 1980

일반적인 ladder회로의 전달함수를 구성하는 각항들 간의 관계로부터 전달함수의 전달함수의 수학적인 공식을 유도하였다. 이 공식의 성질로부터 단계적인 감절법을 개발하엿으며 관찰에 의해서 전달함수를 구할 수 있는 방법을 제시하였다.

• 천문학회보
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• 제40권1호
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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.

• 제어로봇시스템학회논문지
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• 제7권11호
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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.

• 한국공작기계학회논문집
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• 제16권2호
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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.

• 한국공작기계학회논문집
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• 제16권3호
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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.

• 한국음향학회지
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• 제21권2호
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• pp.102-109
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• 2002

본 논문에서는 위드로월 (withdrawal) 가중형 SAW필터를 자동으로 최적화할 수 있는 설계도구의 개발 내용을 제시하였다. SAW 공진기에 위드로월 가중법이 적용될 경우, 향상된 대역폭 및 천이대역 특성을 구현할 수 있으며, 이러한 위드로월 가중효과를 이용하여 사다리형 위드로월 SAW필터의 최적화도구를 완성하였다. 본 설계방법의 유효성을 검증하기 위하여 RF 대역 CDMA용 TX 및 RX SAW 필터를 본 설계도구를 이용하여 최적화하였으며 실제 실험 결과, 이론과 매우 잘 일치함을 알 수 있었다.