Sang Ha Noh

Measurement of grain moisture content using microwave attenuation at 10.5 GHz and moisture density

The dielectric properties of Korean short-grain rough rice, brown rice and barley with moisture content ranges of 11% to 27%, 11% to 18%, and 11 to 21%, wet basis, respectively, were characterized to develop a prototype grain moisture meter using microwave attenuation at 10.5 GHz and moisture density. A third-order polynomial regression model was proposed to describe the relationship between dielectric properties and moisture density. The prototype grain moisture meter consisted of a dielectric resonator type oscillator of 10.5 GHz, horn antenna, rectangular sample holder, load cell, temperature sensor, detector, and digital voltmeter. The calibration equation for measurement of grain moisture content was developed and estimated with Korean short-grain rough rice (12% to 26%). The coefficient of determination, standard error of prediction (SEP), and bias were 0.986, 0.52% moisture content and 0.07% moisture content, respectively.

ON-LINE MEASUREMENT OF GRAIN MOISTURE CONTENT USING RF IMPEDANCE

The dielectric properties of Korean short– and medium–grain rough rice, brown rice, barley, and wheat with moisture ranges of 11% to 27%, 11% to 18%, 11% to 21%, and 11% to 22%, wet basis, respectively, were characterized at 1 to 10 MHz for use in developing a prototype on–line moisture meter using RF impedance and moisture density (moisture content . bulk density). Moisture density was a materially significant parameter for moisture measurement. A linear regression model including oscillation frequency of the LC oscillator, moisture density, and grain temperature indicated coefficients of determination of 0.985 for rough rice, 0.934 for brown rice, 0.996 for barley, and 0.991 for wheat. The root mean square error of an on–line moisture meter was .0.40% moisture content, wet basis, compared with the oven method for moisture determination.

Hyperspectral Imaging for Detecting Defect on Apples

The reflectance spectra from the hyperspectral images of apples were used to find the optimal wavelengths to discriminate the defect region from the normal region. The optimal wavelength was selected from the correlation analysis between the band ratio or wavelength difference and target regions. The spectral images of selected wavelength were used to validate the correlation analysis. The correlation coefficient value using the band ratio at correlation analysis was 0.91 and the using the difference was 0.79. Thus, the correlation analysis method is feasible to select the wavelength to discriminate defects from normal regions.

MATHEMATICAL MODELS FOR THE DIELECTRIC CONSTANTS OF RICE

Models for estimating the dielectric constants of rough, brown, and white rice are developed from measured dielectric constants and bulk densities of rice samples of a long-grain and medium-grain cultivar. The models are based on the straight-line relationships between the square and cube roots of the dielectric constant and the bulk density of the grain. Slopes of these lines were also linear with moisture content of the grain and with the log10 of the frequency. Both the quadratic and cubic models provide practical methods for calculating the dielectric constants of these types and forms of rice of any bulk density over the frequency range from 5 MHz to 12 GHz at moisture contents of practical interest with average errors of 3 to 5%.

Simple instrument for moisture measurement in grain by free-space microwave transmission

A simple microwave moisture meter for grain was introduced with reduction of the size and volume of the instrument by means of 2×2 microstrip patch array antennas. The attenuation and phase shift produced by Korean short-grain rough rice, brown rice, and barley were analyzed to estimate the relationships between moisture density in the grain and the attenuation and phase shift. Second- and third-order polynomial attenuation models were a better measure of moisture density than were phase shift models. A grain moisture meter using microwave attenuation in free-space was constructed. A prototype grain moisture meter consisting of a 10.5 GHz oscillator, patch array antennas, isolator, detector, and digital voltmeter provided a coefficient of determination, standard error of prediction (SEP), and bias of 0.975, 0.62% moisture content, and -0.05% moisture content, respectively.

Development of a portable 3CCD camera system for multispectral imaging of biological samples.

Recent studies have suggested the need for imaging devices capable of multispectral imaging beyond the visible region, to allow for quality and safety evaluations of agricultural commodities. Conventional multispectral imaging devices lack flexibility in spectral waveband selectivity for such applications. In this paper, a recently developed portable 3CCD camera with significant improvements over existing imaging devices is presented. A beam-splitter prism assembly for 3CCD was designed to accommodate three interference filters that can be easily changed for application-specific multispectral waveband selection in the 400 to 1000 nm region. We also designed and integrated electronic components on printed circuit boards with firmware programming, enabling parallel processing, synchronization, and independent control of the three CCD sensors, to ensure the transfer of data without significant delay or data loss due to buffering. The system can stream 30 frames (3-waveband images in each frame) per second. The potential utility of the 3CCD camera system was demonstrated in the laboratory for detecting defect spots on apples.

Internal Quality Estimation of Watermelon by Multiple Acoustic Signal Sensing

Watermelons are usually sorted by theirs weight and internal quality. Some automated watermelon weight sorters have been developed and operated in watermelon production areas. However, inspection of internal quality of watermelon is still performed by manually. Principal method of identifying internal defect of watermelon is analyzing the percussion sound of watermelon by human experts. Development of non-destructive evaluation technique for internal quality of watermelon is required to reduce human decision errors. The objective of this study was to develop a non-destructive sorting system which can detect internal defect of watermelons. The internal defect evaluation system has a constant-force hitting hammer to generate the acoustic sound, a multi-point sound signal acquiring system, a noise removal circuit, and a signal processing and quality evaluation program. An internal quality prediction model by PLSR (Partial Least Square Regression) was developed by analyzing the percussion sound of watermelons. Using the developed model, the prediction result shows that the overall prediction accuracy was 90.1%, and severely defected watermelons were identified perfectly.

RESEARCH OF S-ALLYL-(L)-CYSTEINE CONTENT CHANGES IN AGED GARLIC

SAC (S-Allyl-(L)-cysteine) is one of the bioactive compounds in garlic that has been reporting conducive to good health. However SAC is found only in trace in raw garlic bulb and there is no clear research results of the accumulation method of SAC. We discovered a new method for accumulating SAC during aging period of frozen/thawed garlic. A marked increase of SAC content of frozen and thawed garlic surveyed. It was 2.6391± 0.0022 mg/dry g which is 1.64 times than fresh garlic’s (1.7363 ± 0.218mg/dry g). Moreover maximum accumulation (8.0212 mg/dry g) was achieved for 15 days aging at 40°C.

Multispectral Wavelength Selection to Detect `Fuji` Apple Surface Defects with Pixel-sampling Analysis

Purpose: In this study, we focused on the image processing method to determine the external quality of Fuji apples by identifying surface defects such as scabs and bruises. Method: A CCD camera was used to capture filter images with 24 different wavelengths ranging between 530 nm and 1050 nm. Image subtraction and division operations were performed to distinguish the defect area from the normal areas including calyx, stem, and glaring on the apple surface image. All threshold values of the image were examined to reveal the defect area of pretreated filter images. Results: The developed operation methods were [image (720 nm) – image (900 nm)]/image (700 nm) for bruise detection and [image (740 nm) – image (900 nm)]/image (590 nm) for scab detection, which revealed 81% and 90% recognition ratios, respectively. Conclusions: Our results showed several optimal wavelengths and image processing methods to detect Fuji apple surface defects such as bruises and scabs.

Optimum conditions for S-allyl-(L)-cysteine accumulation in aged garlic by RSM

The objective of this study was to determine the optimum conditions for accumulating SAC [S-allyl-(L)- cysteine]. Although SAC is one of the bioactive compounds in garlic that has been reported to be beneficial for good health, it is found only in trace amounts in raw garlic bulbs and there are no clear research results indicating the accumulation method. We discovered a new method for accumulating SAC by adding a freezing and thawing process. Furthermore the aging process was undertaken at a lower temperature to reduce energy consumption. A 1.64-fold increase in the SAC content of thawed garlic surveyed was noted compared to fresh garlic (2.6391±0.0022 mg/dry g vs. 1.7363±0.2180 mg/dry g). Maximum accumulation (8.0212 mg/dry g) was achieved after 15 days of aging at 40°C, and response surface analysis was performed to determine the optimum conditions including aging period and temperature.