Seung Hee Park

A peptide inhibitor for S-adenosyl-l-methionine-dependent transmethylation reactions: Purification and characterization

1. A. proteinaceous inhibitor for S-adenosyl-L-methionine (AdoMet)-dependent transmethylation reactions has been purified to apparent homogeneity from rat liver cytosolic fraction. 2. The peptide was made up of 29 amino acid residues with a molecular weight of 2,584. Glycine accounted for 52% of the total amino acids. 3. Employing AdoMet: protein-carboxyl O-methyltransferase (Protein methylase II) and bovine serum gamma-globulin as in vitro substrate, the mode of inhibition was found to be non-competitive with Ki value of 1.9 x 10(-8) M. 4. When the inhibitor was present in the reaction mixture together with S-adenosyl-L-homocysteine (AdoHcy), which is a competitive inhibitor for AdoMet, the extent of inhibition exceeded that exerted by each individual inhibitor alone, suggesting that the sites of the inhibitors on the enzyme molecule are different. 5. Almost a stoichiometric relationship exists between the enzyme and the inhibitor molecule, the ratio being approx one.

Optimization of Energy Consumption Using BIM-Based Building Energy Performance Analysis

Recently, the interest in increasing energy efficiency of building energy management system (BEMS) has become a high-priority and thus the related studies also increased. In particular, since the energy consumption in terms of heating and cooling system takes a large portion of the energy consumed in buildings, it is strongly required to enhance the energy efficiency through intelligent operation and/or management of HVAC (Heating, Ventilation and Air Conditioning) system. To tackle this issue, this study deals with the BIM (Building Information Modeling)-based energy performance analysis implemented in Energyplus. The BIM model constructed at Revit is updated at Design Builder, adding HVAC models and converted compatibly with the Energyplus environment. And then, the HVAC models are modified throughout the comparison between the energy consumption patterns and the real-time monitoring in-field data. In order to maximize the building energy performance, a genetic algorithm (GA)-based optimization technique is applied to the modified HVAC models. Throughout the proposed building energy simulation, finally, the best optimized HVAC control schedule for the target building can be obtained in the form of “supply air temperature schedule”.

Magnetic Flux Leakage Sensing-Based Steel Cable NDE Technique Incorporated on a Cable Climbing Robot for Bridge Structures

In this study, an automated cable monitoring system using a NDE technique and a cable climbing robot is proposed. MFL (Magnetic Flux Leakage- based inspection system was applied to monitor the condition of cables. This inspection system measures magnetic flux to detect the local faults (LF) of steel cable. To verify the feasibility of the proposed damage detection technique, an 8-channel MFL sensor head prototype was designed and fabricated. A steel cable bunch specimen with several types of damage was fabricated and scanned by the MFL sensor head to measure the magnetic flux density of the specimen. To interpret the condition of the steel cable, magnetic flux signals were used to determine the locations of the flaws and the level of damage. Measured signals from the damaged specimen were compared with thresholds set for objective decision making. In addition, the measured magnetic flux signal was visualized into a 3D MFL map for convenient cable monitoring. Finally, the results were compared with information on actual inflicted damages to confirm the accuracy and effectiveness of the proposed cable monitoring method.

Auto-Mesh Generation Technique of Near Field Zone for Soil-Structure Interaction Analysis Using Coupled FE-IE Methodology

This paper presents an auto-mesh generation technique using KIESSI (KAIST Infinite Elements for Soil-Structure Interaction) of near field zone for soil-structure interaction analysis (SSI). The working principle of KIESSI is based on coupled three dimensional finite element-infinite element methodology. Also, KIESSI is based on finite element method (FEM) for structure and near-field soil medium and infinite element method for layered half-space far-field. This study utilizes the auto mesh generation technique of near field zone on KIESSI package. The verification example for the effectiveness of automatically meshing technique may be shown through a compliance analysis of layered surface footing. For application example, seismic response analysis at a typical nuclear power plant is carried out in consideration of SSI. The obtained floor response spectrum results in good agreement as compared with the measured response data and the results from SSI analysis package such as SASSI (A System for Analysis of Soil-Structure Interaction).

Visualization of Structural Defects Based on Ultrasonic Wave Propagation Imaging Technique Using Pulsed Laser System

In this study, structural defects are visualized and localized based on a noncontact nondestructive testing (NDT) method which utilizes an ND: YAG pulsed laser system. The ND: YAG pulsed laser is used to generate Lamb waves of a plate-like structure and to scan specific area of the target structure for the visualization of the structure. Wave responses are measured using only single piezoelectric sensor. The measured responses are analyzed using 3 dimensional Fourier transform. The damage-sensitive features are extracted by wave-number filtering based on the 3D FT. Then, flaw imaging technique of a plate-like structure is conducted using the damage-sensitive features. Finally, the plate with a notch is investigated to verify the effectiveness and the robustness of the proposed NDT approach.

Curing Strength Monitoring of Early-Age Concrete Based on Velocity of Guided Wave Using Embedded Plate-Type PZT Sensor Module

In this study, a guided wave based nondestructive curing strength monitoring method is proposed to monitor the curing strength of the early-age concrete. This approach used the embedded steel plate-type PZT sensor module which was fabricated by bonding the two pieces of piezoelectric sensor to a steel plate. The steel plate provided the constant path for guided wave propagation and it protected the piezoelectric sensors from impacts and environmental variations. To measure the guided wave signals from the early-age concrete, fabricated sensor modules were landfilled at the same time with concrete placement.While the concrete was curing, guided wave signals were measured by pitch-catch method continuously at regular intervals. Wavelet transform process was performed to improve the quality of the signal by removing the signal’s noise of undesired frequencies. The TOF (Time of flight) of guidedwave was extract from de-noised signal using peak tracing algorithm to calculate the velocity of wave. The calculated wave velocity hysteresis according to the curing time was traced to analysis the pattern of variations of wave velocity. Finally, specific equations to estimate the strength of the concrete were derived using regression analysis based on the wave velocity and compressive strength from destructive compressive strength test.

Cross-Sectional Damage Localization and Quantification for Steel Cables Using MFL 3D Imaging Technique

In this study, a MFL (Magnetic Flux Leakage) based 3D inspection system which is incorporated into a cable climbing robot was investigated to monitor the healthy condition of steel cables. Firstly, a MFL sensor head prototype composed of two permanent magnets and eight hall sensors was designed and fabricated. A steel cable specimen with several types of damage, such as corrosion and cutting, was inflicted and scanned by the MFL sensor head to measure the magnetic flux density of the specimen. The measured MFL signals were used to interpret the healthy condition of the steel cable. For improving the resolution and quantification of the damage level, digital signal processing techniques were performed. In addition, the measured MFL signals were visualized into a 3D MFL map for real-time and online cable monitoring. This visualized MFL map can provide the information about location, shape and size of damages very intuitively. Finally, the results were compared with information on actual inflicted damages to confirm the accuracy and effectiveness of the MFL based cable inspection system.

Augmented Reality-Based Embedded Sensor Location Recognition and Data Visualization Technique for Concrete Structural Health Monitoring

In recent years, numerous mega-sized and complex civil infrastructures are being constructed all over the world. Therefore, more precise construction and maintenance technologies are required for these complicated construction projects. So a variety of sensors-based structural health monitoring (SHM) techniques have been studied, but these techniques could not manage the sensors efficiently access the database obtained from the sensors. Recently, Quick response (QR) code and AR-based data access technologies have been developed. In this paper, an AR-based concrete curing strength monitoring technique for sensor management and efficient access of the measured data is introduced. It is confirmed that the AR-based concrete curing strength monitoring technique is useful for construction process. In addition, it is concluded that both efficient sensor location recognition and data visualization at anytime, anywhere, and any smart PC devices are promising.

Inhibition of C-terminal O-methyltransferase by a rat liver cytosolic peptide

The activity of S-famesylcysteine O-methyltransferase was assayed by incubating the enzyme with a syntheticin vitro substrate, [N-acetyl-S-trans, trans-famesyl-L-cysteine (AFC)], together with S-adenosyl-L-[methyl-14C]methionine. The resulting methylesterification product, [N-acetyl-S-trans, trans-famesyl-L-cysteine (methyl-14C) ester (AFCME)], was then analyzed either directly on HPLC or by converting the AFC[methyl-14C]ME to [methyl-14C] alcohol by basehydrolysis. Employing these two analytical methods, it was established that a peptide purified from rat liver cytosol fraction [Int. J. Biochem., 25, 1157 (1993)] strongly inhibited the above enzyme activity with IC50 of 7.1X10−8 M. Also, the S-famesylcysteine O-methyltransferase from several human colon cancer cells was also equally inhibited by the peptide.