• Molecules and Cells
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• 제41권4호
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• pp.264-270
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• 2018

Cells cope with diverse intrinsic and extrinsic stimuli in order to make adaptations for survival. The epigenetic landscape plays a crucial role in cellular adaptation, as it integrates the information generated from stimuli. Signaling pathways induced by stimuli communicate with chromatin to change the epigenetic landscape through regulation of epigenetic modifiers. Metabolic dynamics altered by these stimuli also affect the activity of epigenetic modifiers. Here, I review the current understanding of epigenetic regulation via signaling and metabolic pathways. In addition, I will discuss possible ways to achieve specificity of epigenetic modifications through the cooperation of stimuli-induced signal transduction and metabolic reprogramming.

• 한국공작기계학회논문집
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• 제11권2호
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• pp.103-111
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• 2002

Out of all metal-cutting process, the hole-making process is the most widely used. It is estimated to be more than 30% of the total metal-cutting process. It is therefore desirable to monitor and detect drill wear during the hole-drilling process. One important aspect in controlling the drilling process is monitoring drill wear status. There are two systems, Basic system and Online system, to detect the drill wear. Basic system comprised of spindle rotational speed, feed rates, thrust torque and flank wear measured by tool microscope. Outline system comprised of spindle rotational speed feed rates, AE signal, flank wear area measured by computer vision, On-line monitoring system does not need to stop the process to inspect drill wear. Backpropagation neural networks (BPNs) were used for on-line detection of drill wear. The output was the drill wear state which was either usable or failure. This paper deals with an on-line drill wear monitoring system to fit the detection of the abnormal tool state.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.245-247
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• 2004

고속철도는 수많은 하이테크 기술의 결정체이며, 이 중에서도 추진장치는 차량의 성능을 결정하는 매우 중요한 요소이다. 이러한 전장품들에 대한 다양한 성능을 평가하고 진단하기 위해 상시계측시스템을 구축하여 활용하고 있다. 이러한 계측장비들은 여러 전장품에 대한 계측 및 분석을 통한 시험평가와 동시에 완성차 시험이나 본선시운전 시험시에 발생할 수 있는 고장원인을 찾아내고 해결하는데 많은 도움을 주고 있다. 본 논문에서는 강시계측 시스템을 통해 추진장치에 대한 고장진단을 실시한 내용에 대하여 기술하였다.

• 대한기계학회논문집A
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• 제20권7호
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• pp.2134-2140
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• 1996

This study was carried out to anlayze the heat-resistant characteristics of functionally gradient material(FGM) composed with ceramic and metal. The thermal fracture behavior of plasma-sprayed FGM and conventional coating material(NFGM) was exaimined by acoustic emession technique under heating and cooling. Furnace cooling and rapid cooling tests were used to examine the effect of temperature change under various conditions, respectively. At the high temperature above $800^{\circ}C$, it was shown that FGM gives higher thermal resistance compared to NFGM by AE signal and fracture surface analysis.

• 대한산업공학회지
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• 제39권5호
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• pp.383-392
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• 2013

Taguchi method is a technique widely used in industries to attain a reliable quality even under existence of various noise variables. Basically, it relies on the interactions between the controllable and the noise factors. Under insignificant interactions between the design parameters and noises, the effectiveness of Taguchi methodology will be doubtful. Furthermore, existence of strong interactions among controllable factors may undermine the power of Taguchi approach. An abundant crop may be expected by a well planned Taguchi approach. A well designed set of experiments is one of the important prerequisites for its successful result. For this, we must have a clear understanding on strengths and weaknesses of Taguchi methodology together with a sound knowledge on the applicable system. This study provides some insights on Taguchi approach based on two case examples of one successful and the other unsuccessful. Eventually, this research aims to facilitate deeper understanding and right application of Taguchi methodology in industries.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제2권1호
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• pp.33-37
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• 2002

Insulation aging diagnosis system provides early warning regarding electrical equipment defects. Early warning is very important in that it can avoid great losses resulting from unexpected shutdown of the production line. Since relations of insulation aging and partial discharge dynamics are non-linear. it is very difficult to provide early warning in an electrical equipment. In this paper, we propose the design method of insulation aging diagnosis system that use a electromagnetic wave and acoustic signal to diagnose an electrical equipment. Proposed system measures the partial discharge on-line from DAS(Data Acquisition System and acquires 2D patterns from analyzing it. For filtering the noise contained in sensor signals we used ICA algorithms. Using this data, we design of the neuro-fuzzy model that diagnoses an electrical equipment and is investigated in this paper. Validity of the new method is asserted by numerical simulation.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.161-164
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• 2002

Optical fiber vibrations sensors (OFVSs) and extrinsic Fabry-Perot interferometer (EFPI) were used in damage monitoring of fiber-metal laminates(FML). The optical fiber vibration sensor and EFPI were applied in order to detect and evaluate the strain, damage and failure of FML. Damages in composites, such as matrix cracks, delamination and fiber breakage may occur as a result of excessive load, fatigue and low-velocity impacts. Tensile test was performed with the measurement of optical signal and acoustic emission (AE). The signals of the optical fiber vibration sensor due to damages were quantitatively evaluated by wavelet transform. EFPI was less sensible to the damage signals compared with the optical fiber vibration sensor. It was found that damage information of comparable in quality to acoustic emission data could be obtained from the optical fiber vibration sensor signals.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.821-826
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• 2001

Out of all metal-cutting processes, the hole-making process is the most widely used. It is estimated to be more than 30% of the total metal-cutting process. It is therefore desirable to monitor and detect drill wear during the hole-drilling process. One important aspect in controlling the drilling process is monitoring drill wear status. Accordingly, this paper deals with Basic system and Online system. Basic system comprised of spindle rotational speed, feed rates, thrust, torque and flank wear measured tool microscope. Online system comprised of spindle rotational speed, feed rates, AE signal, flank wear area measured computer vision. On-line monitoring system does not need to stop the process to inspect drill wear. Backpropagation neural networks (BPNs) were used for on-line detection of drill wear. This paper deals with an on-line drill wear monitoring system to fit the detection of the abnormal tool state.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.370-375
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• 2003

Optical fiber vibrations sensors (OFVSs) and extrinsic Fabry-Perot interferometer (EFPI) were used in damage monitoring of fiber-metal laminates(FML). The optical fiber vibration sensor and EFPI were applied in order to detect and evaluate the strain, damage and failure of FML. Damages in composites, such as matrix cracks, delamination and fiber breakage may occur as a result of excessive load, fatigue and low-velocity impacts. Tensile and indentation test was performed with the measurement of optical signal and acoustic emission (AE). The signals of the optical fiber vibration sensor due to damages were quantitatively evaluated by wavelet transform. It was found that damage information of comparable in quality to acoustic emission data could be obtained from the optical fiber vibration sensor signals.

• 한국공작기계학회논문집
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• 제11권5호
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• pp.53-57
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• 2002

The chatter to raise grinding operating is reduce the precision and the quality. In this study, In reply to AE signal and the normal force generated in the grinding operating were measured (1) the amplitude in the mathematical model of the normal force is the form as to transform an exponential (2) the chatter growth is minus point of an exponent. (3) From the observed wheel aspect after the chatter growth, it was to investigated the concern of the chatter growth and the wheel life.