Study of volatile organic acids in freeze-dried Cheonggukjang formed during fermentation using SPME and stable-isotope dilution assay (SIDA)

Volatile organic acids in freeze-dried Cheonggukjang were quantified using a stable-isotope dilution assay (SIDA) according to the fermentation period. Five organic acids, acetic acid, propanoic acid, 2-methylpropanoic acid, butanoic acid, and 3-methylbutanoic acid, were identified using solid-phase microextraction (SPME) in conjunction with gas chromatography–mass spectrometry (GC–MS). The contents of volatile organic acids in Cheonggukjang were highly dependent on the fermentation period and they increased during fermentation. Moreover, the branched-chained organic acids (namely 2-methylpropanoic acid and 3-methylbutanoic acid) were formed earlier and were present at much higher contents than the corresponding straight-chained organic acids during Cheonggukjang fermentation.     

Effects of cosolvents on the decaffeination of green tea by supercritical carbon dioxide

Due to the adverse effects of the caffeine in a variety of plant products, many methods have been explored for decaffeination, in efforts to remove or reduce the caffeine contained in plant materials. In this study, in order to remove caffeine from green tea (Camellia sinensis) leaves, we have employed supercritical carbon dioxide (SC–CO₂), which is known to be an ideal solvent, coupled with a cosolvent, such as ethanol or water. By varying the extraction conditions, changes not only in the amount of caffeine, but also in the quantities of the principal bioactive components of green tea, including catechins, such as epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG) and epicatechin (EC), were determined. The extraction conditions, including temperature, pressure and the cosolvent used, were determined to affect the efficacy of caffeine and catechin extraction. In particular, the type and concentration of a cosolvent used constituted critical factors for the caffeine removal, combined with minimal loss of catechins, especially EGCG. When the dry green tea leaves were extracted with SC–CO₂ modified with 95% (v/v) ethanol at 7.0 g per 100 g of CO₂ at 300 bar and 70 °C for 120 min, the caffeine content in the decaffeinated green tea leaves was reduced to 2.6% of the initial content. However, after the SC–CO₂ extraction, a substantial loss of EGCG, as much as 37.8% of original content, proved unavoidable.     

Investigation on thermal characteristics of heat sinks for power module using STM

The device that controls dynamic motions in a washing machine is called as MICOM. This device includes an IPM that controls the rotation of a tub. Also, the overheating of IPM gives cause for lowering the service life of an applied chip and is directly linked with its faults. A heat sink that is larger than the volume of the applied chip more than 50 times is installed to prevent such overheating. In the operation of the IPM, the temperature specification of the heat sink can be determined as 80°C under the air temperature of 25°C. However, the heat sink used at the present time cannot satisfy this condition, so it is necessary to redesign such a heat sink to satisfy this condition. This study proposes an STM that is able to precisely calculate the temperature applied to IPM in a system level prior to redesigning the heat sink. The STM can be considered as a model that complements a JEDEC analysis model. This model implements a parameter analysis to perform the optimization of a heat sink and verifies the priority of parameters to reduce material costs. Furthermore, it investigates a counterproposal that replaces the conventional cooling methods in which it seeks a counterproposal that performs heat dissipation in a device according to the SoC of chips and is able to suppress EMI. This paper was recommended for publication in revised form by Associate Editor Jae Dong Chung Chung-Hyo Jung acquired the doctoral degree in the Dept. of Science for Open and Enviromental Systems at Keio University in 2003. The specialty in the doctoral course was GSMAC-FEM and studied on MHD (magnetohydrodynamics). Dr. Jung joined Samsung Electronics Co., Ltd. as a CFD engineer in 2003. Also, he has worked at Samsung Advanced Institute of Technology and has charged in the thermal analysis of semi-conductors (system LSI). One of the Dr. Jung’s major concerning fields is the mechanical application of Lie-Groups.     

Determination of methanol and fusel oils in various types of wines distributed in Korea

Food Science and Biotechnology - The contents of methanol and fusel oils in various types of wines were determined using headspace-gas chromatography (HS-GC). The HS-GC analysis method showed good...     

Evaluation of the plastic yield locus for embossed sheet using biaxial tensile tests

3D-structured (embossed) aluminium sheets have been used as heat insulation materials in automotive exhaust parts because the embossments on the sheets increase the surface area and reinforce the stiffness of exhaust components. Unlike the press-forming process for flat (non-embossed) sheets, however, that for embossed aluminium sheets is constrained by many restrictions given the distinct mechanical properties and geometric 3D shape of the latter. In designing sheet-stamping tools, manufacturers have recently used CAE technologies based on finite element analysis. Guaranteeing the effectiveness of CAE technologies necessitates information about the plastic yield criterion, which is determined primarily by performing a biaxial tensile test on cruciform-shaped specimens. We measured the yield locus of an embossed aluminium 3004-P sheet by using the camera vision method instead of strain gauge measurement because of the difficulty in attaching a strain gauge to the central region of the aluminium body. The measured yield locus of the studied sheet shows that its yield stress in equi-biaxial stress is smaller than the flat sheet yield locus measured by the strain gauge method. The shape of the yield locus of the embossed aluminium sheet also adequately corresponds with Logan-Hosford anisotropic yield function.     

A Gray-Level Dependent Pre-Emphasis Column Driver With Fast Settling for Active-Matrix LCD Applications

In this brief, simple analytical solutions for pre-emphasis driving conditions in active-matrix liquid crystal display (AMLCD) applications are presented. According to the solutions presented, the column driver with a gray-level dependent pre-emphasis (GLDP) function is designed for fast settling. The GLDP column driver is implemented without using additional frame memory. Also, modifications to the display system and integrated circuit fabrication process changes are not required. The GLDP column driver provides output voltage signals with variable pre-emphasis durations according to the magnitude of the gray-level shift to be driven. By applying the GLDP column driver, 8-mus reduction of the required one row line time was achieved on average. This one row line time reduction makes it possible to realize high performance and low cost AMLCDs. The 640 channel, full function GLDP column driver is fabricated by a 13.5-V 0.35-mum CMOS process.     

Volatile Compounds in Fermented and Acid-hydrolyzed Soy Sauces

ABSTRACT: Volatile compounds in fermented and acid-hydrolyzed soy sauces were isolated and analyzed using solvent extraction and solid-phase microextraction. Quantitatively, alcohols and esters were dominant in the volatiles of fermented soy sauce, whereas heterocyclic compounds, including pyrazines and furans, and acids were relatively abundant in the acid-hydrolyzed soy sauce. The odor-active compounds were also evaluated. The major odor-active compounds of fermented soy sauce were acetic acid, furfuryl alcohol, 2-methoxyphenol, benzeneethanol, benzoic acid, butyric acid, 2-ethyl-4-hydroxy-5-methyl-3(2H) furanone, and 2-methylbutanal, whereas acetic acid, 2-methoxyphenol, formic acid, benzoic acid, 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, butyric acid, 2,6-dimethoxyphenol, 3-hydroxy-2-methyl-4H-pyran-4-one, 2-acetyl-5-methylfuran, 2,5-dimethyl-3-ethylpyrazine, and 2-methylbutanal constituted the major odor-active compounds of acid-hydrolyzed soy sauce.     

Coupled stability analysis of thin-walled composite beams with closed cross-section

For the coupled stability analysis of thin-walled composite beam with closed cross-section subjected to various forces such as eccentric constant axial force, end moments, and linearly varying axial force, the efficient numerical method to evaluate the element stiffness matrix is newly presented based on the homogeneous form of simultaneous ordinary differential equations. The general bifurcation type of buckling theory for thin-walled composite box beam is developed based on the energy functional corresponding to semitangential rotations and semitangential moments. The coupled stability equations including variable coefficients and the force–displacement relationships are derived from the energy principle and explicit expressions for displacement functions are presented based on power series expansions of displacement components. The element stiffness matrix is evaluated by applying member force–displacement relationships to these displacement functions. In addition, the finite element model based on the cubic Hermitian interpolation polynomial is presented. In order to verify the accuracy and validity of this study, numerical solutions are presented and compared with the finite element solutions using the Hermitian beam elements and the available results from other researchers. Particularly, the influence of the eccentricity and the force ratio of axial forces, the fiber orientation, and the boundary conditions on the buckling behavior of composite box beam are parametrically investigated. Also the emphasis is given in showing the phenomenon of buckling mode change.     

Effect of Plastic Anisotropy on the Formability of Aluminum 6016-T4 Sheet Material

Sheet metal formed of lightweight materials such as aluminum sheeting has received great attention related to the reduction of vehicle emissions. This paper evaluates the anisotropic yield locus using Kuwabara’s biaxial tensile tester and stretches formability using Hecker’s hemispherical punch stretching test for aluminum 6016-T4 sheet material. The anisotropic yield locus of the Al6016-T4 sheet measured is fitted well by the modified Drucker yield function. Moreover the best fitting to the experimental stress-strain curve from the tensile test was obtained by taking an appropriate hardening model. Analytical study to predict the stretch formability by using Hora’s Modified Maximum Force Criterion (MMFC) was performed. The predicted forming limit curves (FLC) based on various yield functions were compared with the experiments and discussed.     

Facial Expression Recognition of Various Internal States via Manifold Learning

Emotions are becoming increasingly important in human-centered interaction architectures.Recognition of facial expressions,which are central to human-computer interactions,seems natural and desirable.However,facial expressions include mixed emotions,continuous rather than discrete,which vary from moment to moment.This paper represents a novel method of recognizing facial expressions of various internal states via manifold learning,to achieve the aim of humancentered interaction studies.A critical review ...