• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기물성,응용부문
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• pp.215-216
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• 2006

Solid insulation exposed to voltage is degraded by electrical tree process. And the degradation of the insulation is accelerated by voltage application. For this experimental, specimen of e1ectrical tree model is made by XLPE (cross-linked polyethylene). And the size of the specimen is $7*5*7\;mm^3$. Distance of need1e and plane is 2 mm. Voltages applied for acceleration test are 12 kV to 15 kV. And distribution characteristic of degraded stage is studied too. As a PD detecting and data process, discharge data acquire from PD detecting system (Biddle instrument). The system presents statistical distribution as phase resolved. Moreover the processing time of electrical tree is recorded to know the speed of degradation according to voltage.

• 설비공학논문집
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• 제14권7호
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• pp.552-559
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• 2002

The fault detection and diagnosis (FDD) technology may be applied in order to decrease the energy consumption and the maintenance cost of the air conditioning system. In this study, rule bases and curve fitting models were used to detect faults in an air handling unit. Gradually progressed faults, such as the fan speed degradation, the coil water leakage, the humidifier nozzle clogging, the sensor degradation and the damper stoppage, were applied to the developed FBD system. Simulation results show good detections and diagnoses of these faults. Therefore, this method may be effectively used for the fault detection and diagnosis of the air handling unit.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.669-672
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• 2006

Recently, large efforts have been made to develop and understand the behavior of Fiber Reinforced Concrete. As in the static loading cases, many researches have been done. However, a few studies have been conducted in cyclic behaviors of FRC. The main objective of the present work is to investigate the cyclic behavior of fiber reinforced concrete with theoretical method. First, cyclic constitutive relations which describe the crack bridging stress considering non-uniform interfacial bond degradation in short randomly oriented fiber reinforced matrix composites under uniaxial cyclic tension were considered. A cyclic degradation model of single fiber based on micromechanics also taken into consideration. As an example, fatigue analysis for ECC with PVA fiber was conducted using proposed equations. Results shows that proposed method can establish a basis for analyzing cyclic behavior of fiber reinforced composites.

• 한국세라믹학회지
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• 제49권6호
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• pp.511-517
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• 2012

Pd/MWCNT/$TiO_2$ composites were synthesized by a sol-gel technique using multi-walled carbon nanotubes (MWCNT), palladium (II) chlorite ($PdCl_2$) and titanium tetrachloride ($TiCl_4$) as the carbon, palladium and titanium precursors. The Pd/MWCNT/$TiO_2$ composites prepared were characterized by BET surface area measurements, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The photocatalytic activity of the composites was evaluated using the degradation of methylene blue (MB) under UV and visible light irradiation as a model.

• International Journal of Aeronautical and Space Sciences
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• 제18권3호
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• pp.535-544
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• 2017

In-flight aircraft engine performance estimation is one of the key techniques for advanced intelligent engine control and in-flight fault detection, isolation and accommodation. This paper detailed the current performance degradation estimation methods, and an improved hybrid Kalman filter via velocity-based LPV (VLPV) framework for these needs is proposed in this paper. Composed of a nonlinear on-board model (NOBM) and VLPV, the filter shows a hybrid architecture. The outputs of NOBM are used for the baseline of the VLPV Kalman filter, while the system performance degradation factors on-line estimated by the measured real system output deviations are fed back to the NOBM for its updating. In addition, the setting of the process and measurement noise covariance matrices' values are also discussed. By applying it to a commercial turbofan engine, simulation results show the efficiency.

• The Korean Journal of Physiology and Pharmacology
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• 제25권1호
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• pp.15-26
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• 2021

Peptides are short chain of amino acids linked by peptide bonds. They are widely used as effective and biocompatible active ingredients in cosmetic industry. In this study, we developed novel peptide mixture and identified its anti-pigmentation effect on melanocytes and keratinocytes. Our results revealed that peptide mixture inhibited melanosome biogenesis through the regulation of microphthalmia-associated transcription factor, a key factor of melanogenesis in melanocytes. And we observed that peptide mixture inhibited melanosome uptake through the reduction of protease-activated receptor 2, a phagocytosis-related receptor in keratinocytes. Furthermore, peptide mixture activated autophagy system resulting in degradation of transferred melanosomes in keratinocytes. The anti-pigmentation effect of multi-targeting peptide mixture was assessed in a human skin equivalent model (MelanoDerm). Melanin contents in epidermal layer were significantly decreased by topical treatment of peptide mixture, suggesting that it can be applied as a novel cosmetics material having a whitening function.

• 한국초전도ㆍ저온공학회논문지
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• 제25권3호
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• pp.7-12
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• 2023

Isolation of pollutant-degrading bacteria is important in bioaugmentation, one of the methods for biological degradation of environmental contaminants. We focused on the magnetic activated sludge (MAS) process as a culture method that efficiently concentrates degrading bacteria, and cultured activated sludge with 1,4-dioxane as a model pollutant. After 860 days of operation, MLVSS, which indicates the amount of sludge, increased from 390 mg/L to 10,000 mg/L, and the removal rate of organic matter including 1,4-dioxane, tetrahydrofuran, and glucose in the artificial wastewater reached up to 97%. Based on these results, the MAS process was successfully used to acclimate activated sludge with 1,4-dioxane. Bacterial flora analysis in the MAS showed that bacteria of the genus Pseudonocardia, already reported as 1,4-dioxane degrading bacteria, play an important role in the degradation of this pollutant. The MAS process is a suitable culture method for acclimation of environmental pollutants, and the findings indicate that it can be used as an enrichment unit for pollutant-degrading bacteria.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1275-1280
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• 2004

This paper presents the construction of an active suspension system of a one-wheel car model by using fuzzy reasoning. The car model is approximately described by a nonlinear two degrees freedom system subject to excitation from a road profile, and the active control force is constructed by actuating a pneumatic actuator, and the degradation of the performance due to the delay of the pneumatic actuator is improved by inserting a compensator. The fuzzy control is obtained by single input rule modules fuzzy reasoning, and the excitation from the road profile is estimated by using a disturbance observer. The experimental result shows that the proposed active suspension system much improves the performance in the vibration suppression of the car model.

• Geomechanics and Engineering
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• 제14권6호
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• pp.509-517
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• 2018

This paper proposes a numerical methodology for capturing the complete curve of a pressuremeter test including initial or disturbed parts and loops through a stiffness-based approach adopted in three dimensional finite difference code, FLAC3D. In order to enable this, a new hyperbolic model was used to replace the conventional linear elastic model prior to peak strength of Mohr-Coulomb soil model and update or degradation of shear modulus was considered. Presented modeling approach and implemented constitutive model are impressively successful. It leads to obtain the whole set of parameters for characterizing sands and seems promising for modeling the most of geotechnical structures.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1386-1390
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• 2007

This paper presents the equipment condition monitoring technology for the process or the equipment using statistical techniques. The equipment condition monitoring system consists of an empirical model to estimate the expected sensor values of process variables and a diagnose model to detect the abnormal condition and to identify the root source of the problem. The empirical model is constructed by the analysis of historic data. The diagnose model uses the sequential probability ratio test (SPRT) technique. The monitoring system was tested with real operating data acquired from the Reactor Coolant Pump Seal in the Nuclear Power Plant. It can detect the system degradation or failure at the early stage since it is able to catch the subtle deviation of process variables from normal condition.