• Journal of Korean Society of Forest Science
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• v.87 no.2
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• pp.173-178
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• 1998

Twelve Camellia sinensis populations were studied to investigate the biomass distribution related to stand structure. With increasing mean age of the population, mean root collar diameter increased, while mean height, density and root collar area had no correlation with the age. The result of dimension analysis after cutting the sample trees showed that dry weights of stems +branches and root were exponentially increased and dry weights of current leaves and twigs were linearly increased with increasing root collar diameter. However, the dry weight of older leaves was not related to the root collar diameter. The range of total biomass was 1,162~11,474kg/ha and the range of current leaf biomass was 165~1,341kg/ha. The range of T/R ratio was 1.5~2.8. The biomass of stems+branches and root were significantly correlated with the root collar area of the population and were not significantly correlated with the mean age, mean root collar diameter and density of the population. The biomass of current leaves and twigs were significantly correlated with the root collar area and density of the population.

• Korean Journal of Materials Research
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• v.9 no.7
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• pp.753-759
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• 1999

The microstructure and electrical properties of ZNR that W $O_3$ is added in the range 0.5~4.0mol%, were investigated. The major part of W $O_3$ were segregated at the nodal point and W-rich phase was formed. Three crystalline phases, such as W-rich phase (W $O_3$), Bi-rich phase (B $i_2$W $O_{6}$ ), and spinel phase (Z $n_{2.33}$S $b_{0.67}$ $O_4$) were confirmed to be co-existed at the nodal point The average grain size increased in the range 15.5~29.9$\mu\textrm{m}$ with increasing W $O_3$ additive content. Consequently. W $O_3$ acted as a promotion additive of grain growth. As the W $O_3$ additive content increases. the varistor voltage and the nonlinear exponent decreased in the range 186.82~35.87V/mm and 20.90~3.34, respectively, and the leakage current increased in the range of 22.39~83.01 uh. With increasing W $O_3$ additive content, the barrier height and the density of interface states decreased in the range 1.93~0.43eV and (4.38~1.22)$\times$10$^{12}$ $\textrm{cm}^2$, respectively. W $O_3$ acted as an acceptor additive due to the donor concentration increasing in the range (1.06~0.38)$\times$10$^{18}$ /㎤with increasing W $O_3$ additive content.t.t.

• Korean Journal of Food Science and Technology
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• v.30 no.5
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• pp.1085-1091
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• 1998

The purpose of this study was to investigate the rheological properties of surimi gels and imitation crab-leg products by stress-relaxation test and to examine the correlations between stress-relaxation parameters and T.P.A. parameters. The linear viscoelasticity of surimi gels and imitation crab-leg products was observed in the range of the strain of $5{\sim}20%$ at cross-head speed 2.4 mm/sec. The average tensile forces of surimi gels and imitation crab-leg products were similar, 370.4 g and 436.4 g, respectively, but surimi gels showed higher relaxation time and viscous component (17256.1 sec, $1.357{\times}10^{10}$ poise) than those of imitation crab-leg products (6110 sec, $0.519^{\ast}10^{10}$ poise). Estimated tensile force of each exponential term in relaxation test was highly related with hardness, gumminess and chewiness of T.P.A (r=0.93, 0.93, 0.95, p<0.01), the relaxation time of each exponential term was rrelated with cohesiveness (r=0.89, p<0.01) of T.P,A. and the elastic component of exponential term with gumminess, chewiness and hardness (r=0.92, 0.94, 0.93. p<0.01) of T.P.A.. The viscous component of exponential term was related with cohesiveness (r=0.83, p<0.05) of T.P.A.. The degree of texturization was negatively related with the relaxation time and viscous component (r=-0.92, -0.96, p<0.01).

• Journal of Applied Biological Chemistry
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• v.63 no.2
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• pp.153-159
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• 2020

The analytical method was established for simultaneous determination of fungicide prochloraz and its metabolites in several animal commodities using gas chromatography (GC) coupled with electron capture detector (ECD). Samples including beef meat, pork meat, chicken meat, milk, and egg were hydrolyzed with pyridine hydrochloride which converts prochloraz and its metabolites to 2,4,6-trichlorophenol (2,4,6-TCP) because residue definition for prochloraz was 'sum of prochloraz and its metabolites containing the 2,4,6-trichlorophenol moiety, expressed as prochloraz', for compliance with MRLs from animal commodities. Therefore, residual prochloraz was extracted with acetone, decomposed to 2,4,6-TCP, partitioned with dichloromethane, purified with aminopropyl SPE and quantified as 2,4,6-TCP with GC-ECD. The instrumental limit of quantitation and method LOQ (MLOQ) was 0.01 ㎍/mL and 0.02 mg/kg for prochloraz and 0.005 ㎍/mL and 0.01 mg/kg for 2,4,6-TCP, respectively. The linearity of the calibration curve was good with R² >0.995 in the range of 0.005-0.2 ㎍/mL. Fortification levels of prochloraz were 0.02 mg/kg (MLOQ) and 0.2 mg/kg (10MLOQ) for recovery tests. Overall recoveries of prochloraz were >90% with <10% of coefficient variation (C.V.). This established analytical method was fully validated and could be useful for quantification of prochloraz and its metabolites in animal commodities as official analytical method.

• Journal of Food Hygiene and Safety
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• v.33 no.5
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• pp.354-360
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• 2018

This study presents a method validation for extraction and quantitative analysis of trichothecene mycotoxins in nuts based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) approach for extraction and enhanced matrix removal (EMR)-lipid-disperive-SPE (d-SPE) cleanup method, with detection and quantification by high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) in positive- and negative-ion modes. Linearity, precision, and accuracy were validated for LC-MS/MS methods. Results obtained with LC-MS/MS were linear, with correlation coefficient ($R^2$) of 0.998. Limits of detection and quantification for mycotoxins were $0.41-3.57{\mu}g/kg$ and $1.23-10.82{\mu}g/kg$, respectively. Intra- and inter-day precisions (RSD, %) were 0.40-8.44% and 1.93-12.46%, respectively. Results indicated to be rapidly and accurately identifying trichothecene mycotoxins and may be used as a suitable safety management method for nuts and nuts related commodities.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.441-447
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• 1999

Changes in flavor characteristics of roasted coffee in 6 package models during storage were investigated by GC/MS analysis and sensory evaluation to establish the criteria of the shelf-life of the roasted coffee in three flavor quality-'fresh', 'satisfying' and 'minimally acceptable' levels. In direct headspace method of GC/MS, 47 volatile compounds were analyzed and the light volatile compounds were reduced sharply at initial stage of storage and faster in the package with air. The correlation between % retention of 2,3-butanedione and overall aroma of roasted coffee showed good linear-relation, of which correlation coefficient (R) were from 0.999 to 0.904 depending on package models, indicating that 2,3-butanedione would be an index chemical for evaluating the freshness of roasted coffee. In sensory evaluation of 6 package models during storage, roasted whole beans (RB) and roasted and ground (RG) coffee in air-package were preserved in 'fresh quality' for $0.5{\sim}1$ week, 'satisfying quality' for $2{\sim}3$ weeks and 'minimally acceptable quality' for 12 weeks, while roasted whole beans in valve-package and roasted and ground coffees in vacuum-package, nitrogen-package and oxygen absorbent-package were preserved in 'fresh quality' for $2{\sim}4$ weeks, 'satisfying quality' for $12{\sim}24$ weeks and 'minimally acceptable quality' for 52 weeks. The oxygen absorbent-package was slightly less effective than other three methods.

• Korean Journal of Food Science and Technology
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• v.35 no.1
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• pp.23-27
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• 2003

The effects of temperature and pH on color deterioration of anthocyanin in Schizandra fruit (Schizandra chinensis fructus) were determined with temperature range of $80{\sim}100^{\circ}C$ and pH range of $2.0{\sim}5.0$. Browning index was used as an index of color deterioration of crude anthocyanin extract from Schizandra fruit. As pH of crude anthocyanin extract was increased, color deterioration was accelerated, showing pH-dependency of thermal stability of anthocyanin extract from Schizandra fruit. Anthocyanin degradation could be modeled as a second-order rate reaction, with rate of $3.2{\times}10^{-3}\;h^{-1}\;(pH\;2.0){\sim}4.1{\times}10^{-3}\;h^{-1}\;(pH\;5.0)\;at\;100^{\circ}C$. Temperature dependence of deterioration was described by the Arrhenius relationship. Activation energies for pH $2.0{\sim}5.0$ ranged from $24.87{\sim}42.54\;kJ/mol^{-1}$.

• Korean Journal of Food Science and Technology
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• v.28 no.3
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• pp.545-551
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• 1996

Water-vapor transmission rate and water-vapor permeability of carrageenan-based edible film with three different thicknesses of 0.05, 0.08 and 0.11 mm were measured to investigate the potential applicability of the films to powder foods at five different temperatures (20, 25, 30. 35 and $4^{\circ}C$) and three different relative humidities (50. 70 and 90% RH). Water-vapor transmission rate of the carrageenan-based film was gound to be 2.3 times higher than that of polyethylene (PE) film and water-vapor permeability of the film was 45-230 times higher than that of PE film. Water-ydpor permeability of the film seemed to increase linearly with the film thicknees like other hydrophilic edible films. Water-vapor transmission rate were found to be dependent on the temperature. Activation energies of the water-vapor transmission rate of the film were found to be between 7.898 and 12.8702 kj/mol depending on the film thickness. The water-vapor transmission rate of the film showed the typical kinetic compensation effect between activation energies and preexponential factors. which was proved by the linear increase in the value of logarithms of preecponential factor.

• Water for future
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• v.14 no.4
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• pp.53-72
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• 1981

In this study, South Korea is divided into 5 zones and is studied about the analysis of time-regional distribution of previpitation frequency and rainfall intensity in Korea. In the previpitation frequency analysis, the basic data groups of 39 stations were selected. The diagram of previpitation frequency was drawn, and the time-regional distribution of precipitation frequency was analized. In the rainfall intensity analysis, the basic data groups of 36 stations were selected. The probable rainfall, I-D-F curve, and regression equation between 24hr. and 10min.-18hr. areal depth were obtained. The results of this study are following; 1) The precipitation class of max. recurrence probability in every season except summer was commonly (1) 1-5mm, (2) 0.1-1mm, (3) 5-10mm in order. 2) The zone of max. recurrence frequency owing to the precipitation class was zone II in precipitation frequency of below 20mm, zone IV in precipitation frequency of 30-40mm, zone I in precipitation frequency of above 70mm for a year. 3) The recurrence probability of precipitation in Korea can be represented to the equation of exponential function; $$W(x)=e^{\alpha+\beta}$$ 4) The first and third zones were expected heavy rain for the short and long duration. 5) The I.D.F. curves were drawn, and established that the time interval for the least deviation of I.D.F curve is 10~40min., 40min. -4hr., 4~24hr. 6) The regression equations of areal mean depth between 24hr. and 10min.-18hr. for each zone were obtained. 7)The probable rainfall of 36 points were calculated.

• Korean Journal of Food Science and Technology
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• v.51 no.5
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• pp.420-424
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• 2019

An HPLC analysis method was developed and standardized for the detection of dieckol as a functional food ingredient in Ecklonia cava extracts. HPLC was performed using a Capcell Pak C18 column ($250{\times}4.6mm$, $5{\mu}m$) with a gradient elution of water and acetonitrile, both containing 0.1% (v/v) trifluoroacetic acid, at a flow rate of 1.0 mL/min at $25^{\circ}C$. The eluate was detected at 230 nm. For validation, the specificity, linearity, accuracy, precision, limit of detection (LOD), and limit of quantification (LOQ) of dieckol were measured. The calibration curve for the detection of dieckol had high linearity ($R^2=0.9994$), with LOD and LOQ values of 0.38 and $1.16{\mu}g/mL$, respectively. Recovery of the quantified compound ranged from 99.61 to 100.71%. The relative standard deviation values of the intra-day and inter-day precisions were less than 1.7 and 1.25%, respectively. These results indicate that the reported HPLC method is simple, reliable, and reproducible for the detection of dieckol in Ecklonia cava extracts.