• Journal of Microbiology and Biotechnology
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• v.4 no.4
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• pp.360-363
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• 1994

A colorimetric assay for $\gamma$-glutamyl transpeptidase ($\gamma$-CTP; E.C 2.3.2.2) employing 2, 4, 6-trinitrobenzene sulfonate (TNBS) to detect the amount of disappeared acceptor via transpeptidation, has been developed. Under the experimental conditions using L-$\gamma$-glutamyl ethyl ester and L-phenylalanine as $\gamma$-glutamyl donor and acceptor, respectively, it was found that the decreased absorbance of yellow color at 420 nm was strictly related to the amount of L-$\gamma$-glutamyl-L-phenylalanine (L-$\gamma$-Glu-L-Phe) formed, which was determined by DEAE-cellu-lose column chromatography. Concentrations of the enzyme and $\gamma$-glutamyl products were able to be determinedin the nanogram and nanomoles per milliliter range, respectively, with high precision and reliability. This novel assay system may therefore be a useful means for understanding of catalytic function of the $\gamma$-CTP spectrophotometrically without any usage of sophisticated instruments.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.163-166
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• 2003

Maintaining low temperature is very important in operating HTS cable termination in which Joule heat is generated at current lead. In this study, numerical analysis using FLUENT is performed to find an optimized flow conditions for effective cooling of HTS cable terminal system using subcooled liquid nitrogen (L$N_2$) as refrigerant. The variables considered here are mass flow rate of L$N_2$, location of inlet and diameter of inlet and outlet. Simplified models are investigated under these variables. Based on maximum temperatures in the cryostat, the configuration for effective cooling of HTS cable was determined.

• Journal of the Korean Ceramic Society
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• v.43 no.4 s.287
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• pp.253-258
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• 2006

In the lamination process of multi-layer ceramic modules, the occurrence of delamination comes into repeatedly. To completely improve the lamination process of LTCC sheets, a binder film was introduced between the layers. The binder film did not originate the delamination until the thickness under $40{\mu}m$. After lamination, the thickness of the binder film was determined by the infilteraion of binder by the pressure, and after the bake-out, was dependent on the decomposition of binder resin. Any detectable defect was not observed in the multilayer structure with Ag inner electrodes.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.51
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• pp.41-52
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• 1999

In this paper, a load balancing problem among operators is considered, when one or more machines can be assigned to an operator. The machines are grouped into two types and there are more than one machines in each group. The type of machine in which a job can be processed, is determined. However, an operator can handle both types of machine. The elementary operations of a job are classified into three classes : machine-controlled elements, operator-controlled elements and machine/operator- controlled elements. The objective is to balance the workloads among operators under the constraints of available machine-time and operator-time. A heuristic solution procedure is suggested for allocating jobs to machines and allocating machines to operators. The performance of the algorithm is evaluated with various data set.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.8
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• pp.1163-1172
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• 2001

The two dimensional problem of a layered tribological system(TiN/Steel) containing a vertical surface breaking crack and subject to rolling contact is considered in this study. Using finite elements and stress extrapolation method, a series of preliminary models are developed. Preliminary results indicate that the extrapolation technique is valid to determine Modes I and II stress intensity factors for cracks. In the case of TiN/Steel medium, KI and KII were determined for variations in crack length, layer thickness, and load location. The results show that KII reaches maximum values when the contact is adjacent to the crack where Mode I stresses are compressive. KII values decrease with decreased crack length and significantly decrease for reduced layer thickness.

• International Journal of Control, Automation, and Systems
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• v.2 no.4
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• pp.485-493
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• 2004

Open-loop position estimation methods are commonly used in mobile robot applications. Their strength lies in the speed and simplicity with which an estimated position is determined. However, these methods can lead to inaccurate or unreliable estimates. Two position estimation methods are developed in this paper, one using a single optical flow sensor and a second using two optical sensors. The first method can accurately estimate position under ideal conditions and also when wheel slip perpendicular to the axis of the wheel occurs. The second method can accurately estimate position even when wheel slip parallel to the axis of the wheel occurs. Location of the sensors is investigated in order to minimize errors caused by inaccurate sensor readings. Finally, a method is implemented and tested using a potential field based navigation scheme. Estimates of position were found to be as accurate as dead-reckoning in ideal conditions and much more accurate in cases where wheel slip occurs.

• Journal of Industrial Technology
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• v.27 no.A
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• pp.47-53
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• 2007

A theoretical model based on Rayleigh-Ritz method is proposed to predict the resonance frequency of a W/T(Wind Turbine) tower structure supported by guy cables. In order to verify the validity of the theoretical model, a reduced W/T tower system is manufactured and tested. Frequency response and mode data are determined by modal testing and finite element analysis is performed to calculate the natural frequency of the tower model. Numerical and experimental results are compared with those by the theoretical analysis. Parametric study by the theoretical model shows how the cable tension and cable elasticity influence the resonance frequency of the W/T tower structure. Finally, vibration response under various rotating speed is investigated to examine the possibility of severe resonance.

• ETRI Journal
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• v.26 no.5
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• pp.423-431
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• 2004

In earlier works on transmitter power control in cellular radio systems, the problem of whether a signal-to-interference ratio (SIR) threshold is achievable is determined by apparently different rules for homogeneous and heterogeneous SIR systems. In this paper, we present a unified and more universal framework for both cases. We also highlight the conditions under which a given SIR threshold vector for the heterogeneous SIR system is achievable, although so far there is no general solution to this problem.

• Structural Engineering and Mechanics
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• v.74 no.1
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• pp.121-128
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• 2020

This paper presents an experimental study on the dynamic characteristics of infilled reinforced concrete (RC) frames. A 1/3-scaled, one-bay, three-storey RC frame was produced and tested by using operational modal analysis (OMA). The experiments were performed on five specimens: one reference frame with no infill walls and four frames with infill walls. The RC frame systems included infill walls made of hollow clay brick, which were constructed in four different patterns. The dynamic characteristics of the patterns, including the frequency, mode shapes and damping ratios in the in-plane direction, were obtained by 6 accelerometers. Twenty-minute records under ambient vibration were collected for each model, and the dynamic characteristics were determined using the ambient vibration testing and modal identification software (ARTeMIS). The experimental studies showed that the infill walls significantly affected the frequency value, rigidity and damping ratio of the RC frame system.

• Structural Engineering and Mechanics
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• v.74 no.2
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• pp.215-225
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• 2020

Thin films easily wrinkle under compressive loading due to their small bending stiffness resulting from their tiny thickness. For a thin film deposited on a functionally graded substrate with non-uniform stiffness exponentially changes along the length span in this paper, the uniaxial wrinkling problem is solved analytically in terms of hyper-Bessel functions. For infinite, semi-infinite and finite length systems the wrinkling load and wrinkling wavenumber are determined and compared with those in literature. In comparison with a homogeneous substrate-bounded film in which the wrinkling pattern is uniform along the length span, for a functionally graded substrate-film system the wrinkles accumulate around the softer location of the functionally graded substrate. Therefore, the effective length of the film influenced by the wrinkles decreases, the amplitude of the wrinkles on softer regions of the functionally graded substrate grows and the wrinkling load of the functionally graded substrates with higher softening rate decreases more. The results of the current research are expected to be useful in science and technology of thin films and wrinkling of the structures especially living tissues.