• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.9
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• pp.1366-1372
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• 2010

This study investigated the quality characteristics of brown rice vinegar (agitated culture and static culture) derived from brown rice Takju with different types of yeasts. The alcohol content by yeast was the highest in B (brown rice Takju produced by S. cerevisiae GRJ) at 14.3% and the titratable acidity was less than 0.6% in all ranges. When quality characteristics of agitated and static culture brown rice vinegar using them were compared, acidity of agitated culture vinegar recorded the highest level or 6.05% at 7 day of fermentation DV (brown rice vinegar produced by S. kluyveri DJ97) with the initial acidity of 1.0% and the initial pH of 3.9~4.0, and AV (brown rice vinegar produced by S. cerevisiae JK99), CV (brown rice vinegar produced by S. cerevisiae H9) and BV (brown rice vinegar produced by S. cerevisiae GRJ) recorded as 5.64, 5.55 and 5.32%, respectively. In addition, acidity of static culture vinegar increased continuously to 5.01~5.31% until the 14 day of fermentation and then tended to decrease slightly from the 16 day of fermentation. Difference in acidity and pH of brown rice vinegar according to types of yeast was not significant. Comparison of free amino acid of brown rice vinegar showed that for agitated culture brown rice vinegar, the content of total free amino acid was higher in the order of BV, DV, AV and CV and the content of essential amino acid was the highest in BV by recording over 1,000 ppm. The content of total free amino acid of static culture brown rice vinegar was higher than that of agitated culture vinegar in all ranges and especially static culture brown rice vinegar contained more serine, alanine, valine, isoleucine, leucine and $\gamma$-aminobutyric acid than agitated culture vinegar. In particular, $\gamma$-aminobutyric acid recorded over ten times higher level or 456.91~522.66 ppm. From these results, quality characteristics of brown rice vinegar was affected by acetic acid fermentation methods rather than types of yeast. However, as future aging process is expected to change flavor components and sensory characteristics, studies on various quality factors of vinegar are needed.

• Journal of Electrical Engineering and Technology
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• v.1 no.2
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• pp.161-169
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• 2006

Load representation has a significant impact on power system analysis and control results. In this paper, composite load models are developed based on on-line measurement data from a practical power system. Three types of static-dynamic load models are derived: general ZIP-induction motor model, Exponential-induction motor model and Z-induction motor model. For the dynamic induction motor model, two different third-order induction motor models are studied. The performances in modeling real and reactive power behaviors by composite load models are compared with other dynamic load models in terms of relative mismatch error. In addition, numerical consideration of ill-conditioned parameters is addressed based on trajectory sensitivity. Numerical studies indicate that the developed composite load models can accurately capture the dynamic behaviors of loads during disturbance.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.162-169
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• 1999

Herringbone groove journal bearing (HGJB) is developed to improve the static and dynamic performances of hydrodynamic journal bearing. Conventional studies on HGJB were based on the Narrow Groove theory assuming that the number of grooves approaches infinity. In this study, an oil lubricated HGJB is analyzed using Finite Element Method. Load carrying capacity, attitude angle, stiffness and damping coefficients are obtained numerically for various bearing configurations especially for the inclined width ratio and asymmetric ratio and compared with the results obtained using Finite Volume Method. The bearing load and stability characteristics are dependent on geometric parameters such as inclined width ratio, asymmetric ratio, groove depth ratio, groove width ratio, groove angle.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.351-352
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• 2002

In this paper, studies were made on the palm oil methyl ester (POME) added lubricants using FT-IR for monitoring oil degradation. In order to assess the degradation characteristics of POME added lubricant by FT-IR, static oxidation test was conducted using three different blended lubricants (viz, zero percent POME, five percent POME and ten percent POME with mineral-based oil) for 280 hrs. The oxidation temperature was set at $140^{\circ}C$. FT-IR quantitative data indicate an increased in oxidation products which was formed from 10% POME added lubricants after 280 hrs of oxidation test. The 5% POME added lubricant and mineral-based lubricant (without POME) showed less oxidation product after the test. From the FT-IR spectrum analysis of the oxidized oils it could be concluded that 5% POME can improve the performance of mineral-based oil by forming protective films.

• Earthquakes and Structures
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• v.1 no.1
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• pp.129-146
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• 2010

This paper proposes an approximate procedure to estimate seismic displacement capacity - defined as yield displacement times the displacement ductility - of piles in marine oil terminals. It is shown that the displacement ductility of piles is relatively insensitive to most of the pile parameters within ranges typically applicable to most piles in marine oil terminals. Based on parametric studies, lower bound values of the displacement ductility of two types of piles commonly used in marine oil terminals - reinforced-concrete and hollow-steel - with either pin connection or full-moment-connection to the deck for two seismic design levels - Level 1 or Level 2 - and for two locations of the hinging in the pile - near the deck or below the ground - are proposed. The lower bound values of the displacement ductility are determined such that the material strain limits specified in the Marine Oil Terminal Engineering and Maintenance Standard (MOTEMS) are satisfied at each design level. The simplified procedure presented in this paper is intended to be used for preliminary design of piles or as a check on the results from the detailed nonlinear static pushover analysis procedure, with material strain control, specified in the MOTEMS.

• Structural Engineering and Mechanics
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• v.14 no.4
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• pp.473-489
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• 2002

A static linear programming formulation for minimum weight design of frames that is based on a matrix displacement method is presented in this paper. According to elementary theory of plasticity, minimum weight design of frames can be carried out by using only the equilibrium equations, because the system is statically determinate when at an incipient collapse state. In the present formulation, a statically determinate released frame is defined by introducing hinges into the real frame and the bending moments in yield constraints are expressed in terms of unit hinge rotations and the external loads respectively, by utilizing the matrix displacement method. Conventional Simplex algorithm with some modifications is utilized for the solution of linear programming problem. As the formulation is based on matrix displacement method, it may be easily adopted to the weight optimization of frames with displacement and deformation limitations. Four illustrative examples are also given for comparing the results to those obtained in previous studies.

• Structural Engineering and Mechanics
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• v.48 no.1
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• pp.103-124
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• 2013

This paper studies the static and dynamic characteristics of composite plates subjected to an arbitrary periodic load in hygrothermal environments. The material properties of composite plates are depended on the temperature and moisture. The governing equations of motion of Mathieu-type are established by using the Galerkin method with reduced eigenfunction transforms. A periodic load is taken to be a combination of axial pulsating load and bending stress in the example problem. The regions of dynamic instability of laminated composite plates are determined by solving the eigenvalue problems based on Bolotin's method. The effects of temperature rise and moisture concentration on the dynamic instability of laminated composite plates are investigated and discussed. The influences of various parameters on the instability region and dynamic instability index are also investigated. The numerical results reveal that the influences of hygrothermal effect on the dynamic instability of laminated plates are significant.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.711-716
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• 2003

This study considers the implementation issues of the inter-vehicle communication system for the vehicle platoon experiments via a testbed. The testbed, which consists of three scale vehicles and one RCS(remote control station), is developed as a tool for functions evaluation between simulation studies and full-sized vehicle researches in the previous study. The cooperative communication of the vehicle-to-vehicle or the vehicle-to-roadside plays a key role for keeping the relative spacing of vehicles small in a vehicle platoon. The static platoon control, where the number of vehicles remains constant, is sufficient for the information to be transmitted in the suitably fixed interval, while the dynamic platoon control such as merge or split requires more flexible network architecture for the dynamical coordination of the communication sequence. In this study, the wireless communication device and the reliable protocol of the flexible network architecture are implemented for our testbed, using the low-cost, ISM band transceiver and the 8-bit microcontroller.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.337-341
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• 2003

This paper provides a design method for a dynamic output feedback controller which stabilizes a class of linear time invariant systems. We suppose all the states of the given system is not measurable and only the outputs are used to stabilize the system. The systems considered cannot be stabilized by a static output feedback only. In the scheme we first assume that the given system can be stabilized by a state feedback composed of its output, velocity of the output and its higher order derivative terms. Instead of using the derivatives of the output, however, a dynamic system is constructed systematically which replaces the role of the derivative terms. Then, a high-gain output feedback stabilizes the composite system together with the newly constructed system. The performance of the proposed control law is illustrated in the comparative simulation studies of a numerical example with an observer-based control law.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1995.04a
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• pp.136-143
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• 1995

The problem of the structural identification becomes important, particularly with relation to the rapid increase of the number of the damaged or deteriorated structures, such as highway bridges, buildings, and industrial facilities. This paper summarizes the recent studies related to those problems by the present authors. The system identfication methods are generally classified as the time domain and the frequency domain methods. As time doamin methods, the sequential algorithms such as the extended Kalman filter and the sequential prediction error method are studied. Several techniques for improving the convergences are incorporated. As frequency domain methods, a new frequency response function estimator is introduced. For damage estimation of existing structures, the modal perturbation and the sensitivity matrix methods are studied. From the example analysis, it has been found that the combined utilization of the measurement data for the static response and the dynamic (modal) properties are very effictive for the damage estimation.