• Korean Journal of Environmental Agriculture
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• v.42 no.1
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• pp.21-27
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• 2023

Pre-harvest residue limits (PHRLs) have been proposed as criteria for a proactive role to exceed the maximum residue limit (MRL) of pesticides in agricultural products at harvest. However, PHRL numbers are significantly less than those of established MRLs. This study was performed to determine the dissipation constants and residual concentrations of lufenuron after application on crown daisy and chamnamul under green house conditions. Two residue field trials for each crown daisy and chamnamul were selected to consider a different geographical site at least 20 km far from one another. The pesticide was treated according to critical GAP. After samples were sprayed with lufenuron, they were collected at 0, 1, 3, 5, 7, 10, and 14 days and analyzed using HPLC-DAD. The mean recoveries of crown daisy and chamnamul were within the range of 70-120% with below 20% coefficient variation, which is within the acceptable limits specified by the manual of pre-harvest residue study for pesticides (MFDS, 2014). The biological half-lives in field I and field II were 7.0 and 4.6 days for crown daisy and 2.7 and 2.8 days for chamnamul, respectively. The lower bounds of 95% confidence intervals of dissipation rate constants of lufenuron in crown daisy were determined to be 0.0692 and 0.1298 for field I and field II, respectively, and in chamnamul were 0.2067 for both field I and field II. After applying lufenuron 5% EC, the lufenuron residues on crown daisy and chamnamul at the pre-harvest intervals (14 days for crown daisy and 7 days for chamnamul) were below the safe levels. The dissipation rates of lufenuron in crown daisy and chamnamul were evaluated for similarities with leafy vegetables based on a 95% confidence interval.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.1
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• pp.95-104
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• 2020

The purpose of this study is to develop a pipe type soil sampler that can easily collect soil cross section servey and soil samples to conduct ecological environment surveys while minimizing ecological disturbance in the area subject to soil survey. Furthermore, this study develop the exponential type estimation specific weight formula (ESWF) that uses pipe type soil sampler to easily carry out soil cross section survey and soil sample while estimating the specific weight of the area using water content and soil sample length variation ratio (SLVRs) and to obtain apparent specific gravity, hardness, and max. porosity which are used as growth of corps and ecological environment index. The calibration results of ESWF showed a high degree of significance, with NSE for actual specific weight (γ₀) and calibration estimation specific weight (γ_ec) 0.95, R² for 0.954, and RMSE for 0.051. The verification results of ESWF showed a high significance, with NSE for actual specific weight (γ₀) and verification estimation specific weight (γ_ev) 0.881, R² for 0.978, and RMSE for 0.055.

• Analytical Science and Technology
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• v.36 no.4
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• pp.152-160
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• 2023

Adenosine and cordycepin are bioactive compounds with health benefits. Therefore, both substances are often used to assess the quality of Cordyceps products. Optimization and validation of the HPLC/DAD method for determining two nucleosides were studied. The samples were prepared using an ultrasound-assisted extraction (ultrasonic bath). The result was optimal conditions for aqueous extraction, an extraction time of 35 min, and an extraction temperature of 40 ℃. The Chromatographic separation was achieved using a reverse phase column (InfinityLab Poroshell 120 EC-C18, 4.6 × 250 mm, 2.7 ㎛) at 30 ℃ with a mobile phase gradient elution of water and methanol at a flow rate of 0.7 mL/min. The eluents were monitored via a diode array detector at 260 nm. Two nucleosides were separated by less than 12 min after injection. The developed method was found to be excellent linear (r² > 0.9999), accurate (% recovery 95.34-98.51), and precise (% relative standard deviation < 2.0). The limit of detection (LOD) and quantification (LOQ) were 0.45 and 1.38 mg/mL for adenosine and 0.47 and 1.43 mg/mL for cordycepin, respectively. This method was satisfactory for simultaneously quantitating two nucleoside contents, which were used to evaluate Cordyceps products.

• Proceedings of the Korean Society for Quality Management Conference
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• 2004.04a
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• pp.298-301
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• 2004

European Union Member States shall ensure that, from 1 July 2006, new electrical and electronic equipment put on the market does not contain mercury, cadmium, lead, hexavalent chromium, polybrominated biphenyls(PBB) or polybrominated diphenyl ethers(PBDE) (by Directive 2002/95/EC of The European Parliament and the Council of 27 january, 2003 on the restriction of the use of certain hazardous substances in electrical and electronic equipment ). So, It is important to develop lead free solder and to assure the reliability of appliance. But lead free solder(i.e. Sn-3Ag-0.5Cu) have some problems such as lift off, whisker, migration and crack, etc. In this paper we discuss the reliability assurance method in lead free solder and appliance.

• Korean Journal of Environmental Biology
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• v.32 no.3
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• pp.234-242
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• 2014

In this study, gametotoxicity and embryotoxicity experiments using Hemicentrotus pulcherrimus were carried out to investigate the ecotoxicological effects of bisphenol A (BPA). We examined the effects of BPA on fertilization and normal embryogenesis at various concentrations (0, 300, 500, 800, 1000, and 1500 ppb). The results demonstrated that the fertilization rates were not changed. The normal embryogenesis rates were gradually decreased in a dose-dependent manner, and were significantly lowered following 800 ppb BPA treatment ($EC_{50}$=1056.1 ppb, 95% Cl=981.8~1163.9 ppb). The observed effective concentration and the lowest observed effective concentration of the normal embryogenesis rate were 500 ppb and 800 ppb, respectively. The embryos showed retarded development at each tested concentration, indicating the fact the embryonic development was delayed due to the increasing concentrations of BPA. Furthermore, we examined the expression of glutathione S-transferase (GST) mRNA at various concentrations of BPA in H. pulcherrimus. Interestingly, it was found that the expression level of GST mRNA was significantly increased in the experimental group exposed to BPA. Based on these results, we suggested that BPA at greater than 800 ppb has a toxic effect during the early embryonic stages of H. pulcherrimus, and GST mRNA may be used as a biomarker for risk assessment of BPA contamination.

• Journal of Life Science
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• v.25 no.10
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• pp.1169-1175
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• 2015

Although many studies have described the physiological effects of bee products, such as honey, propolis, pollen, and royal jelly, the health benefits of honeycomb remain incompletely characterized. We performed a comparative study of the antioxidant properties of honey and honeycomb extracts using two different solvents (water and 95% ethanol). The results showed that the total phenolic and flavonoid content of the honeycomb extract was higher than that of the honey extract. They also demonstrated that water was more effective than ethanol in extracting total phenols. The in vitro antioxidant properties of the water honeycomb extract were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide (NO^•) radical scavenging assays and ferrous ion chelating and reducing power assays. The antioxidant activity of the honeycomb extract exhibited was higher than that of the honey extract. The 50% effective concentrations (EC₅₀) of the honeycomb extract were 7.3±0.26 mg/ml for scavenging DPPH radicals, 6.1±0.22 mg/ml for scavenging NO^• radicals, 6.9±0.44 mg/ml for chelating ferrous ions, and 8.2±0.11 mg/ml for reducing power. A correlation analysis revealed that the total phenolics and flavonoids of the honeycomb extract were the major contributors to the radical scavenging activity, ferrous ion chelating, and reducing power. The honeycomb extract was effective in protecting biological systems against various oxidative stresses in vitro. This is the first report on the antioxidant properties of honeycomb.

• Physical Therapy Korea
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• v.28 no.2
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• pp.154-160
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• 2021

Background: Theoretically, balance is affected by the height of center of mass (COM) during quiet standing. However, no one examined this in humans with variables derived from the center of pressure (COP). Objects: We have conducted balance experiment to measure COP data during quiet standing, in order to examine how the COP measures were affected by the height of COM, vision, floor conditions, and gender. Methods: Twenty individuals stood still with feet together and arms at sides for 30 seconds on a force plate. Trials were acquired with three COM heights: 1% increased or decreased, and not changed, with two vision conditions: eyes closed (EC) and eyes open (EO), and with two floor conditions: unstable (foam pad) and stable (force plate) floor. Outcome variables included the mean distance, root mean square distance, total excursion, mean velocity, and 95% confidence circle area. Results: All outcome variables were associated with the COM height (p < 0.0005), vision (p < 0.0005), and floor condition (p < 0.003). The mean velocity and 95% confidence circle area were 5.7% and 21.8% greater, respectively, in raised COM than in lowered COM (24.6 versus 23.2 mm/s; 1,013.4 versus 832.3 mm²). However, there were no interactions between the COM height and vision condition (p > 0.096), and between the COM height and floor condition (p > 0.183) for all outcome variables. Furthermore, there was no gender difference in all outcome variables (p > 0.186). Conclusion: Balance was affected by the change of COM height induced by a weight belt in human. However, the effect was not affected by vision or floor condition. Our results should inform the design of balance exercise program to improve the outcome of the balance training.

• The Korean Journal of Pesticide Science
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• v.14 no.1
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• pp.65-71
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• 2010

This study was performed to investigate the inhibiting activity of etridiazole and thiophanate-mthyl on mycelial growth of Rhizoctonia solani and Pythium ultimum and the effect of inoculum density of each pathogen on the control efficacy of the mixture of etridiazole and thiophanate-methyl in a seedling assay test. In mycelial growth inhibition test, $EC_{50}$ values of etridiazole and thiophanate-methyl against R. solani were 15.87 and 9.34 ${\mu}g\;mL^{-1}$, while those were 0.2 and more than $500\;{\mu}g\;mL^{-1}$ against P. ultimum, respectively. Controlling activity of the mixture of etridiazole and thiophanate-methyl against damping-off of pepper and cucumber, caused by R. solani and P. ultimum was tested in a greenhouse. With the inoculation of R. solani, disease incidences of seedling in pepper were 73% and 95% at 0.5% and 1.0% of inoculum concentration, while in cucumber those were 55% and 62% at 1.0% and 2.0%. When P. ultimum was inoculated into soil by 2.0% of inoculum concentration, those in pepper and cucumber were 66.7% and 96.8%, respectively. The efficacy of the mixture was somehow affected by the concentration of R. solani. While each control value of the mixture was 94.4% and 90.7% in pepper and cucumber at low inoculum concentration (0.05%), the efficacy of the fungicide decreased in pepper and cucumber by 70.7% and 72.9% at high concentration of R. solani (0.1% in pepper and 0.5% in cucumber). However, the control value of the mixture was 100% in pepper and cucumber, irrespective of the inoculum concentration of P. ultimum, however, the increase of inoculum concentration in soil did not result in the decrease of the fungicide efficacy.

• Microbiology and Biotechnology Letters
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• v.19 no.3
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• pp.253-258
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• 1991

- An exoinulinase (EC 3.2.1.80) was purified from a commercial inulinase preparation from Aspergillus ficuum using ion exchange chromatography on CM-Sephadex C-50 and DEAESepharose 6B and HPLC gel filtration on a Protein Pak 125 column. Native exoinulinase had a molecular weight of 83, 000$\pm$ 1, 000 and was glycoprotein. Optimal pHs of the enzyme were ranged from 4.4 to 4.7. About ninety five percent of the whole activity was maintained even after incubation of 8 hours at $55^{\circ}C$.The enzyme was a typical non-specific P-fructofuranosidase, of which I/S ratio appears to be 0.35.

• Journal of the Korean Wood Science and Technology
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• v.45 no.1
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• pp.96-106
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• 2017

This study aims to identify the chemical compositions and antioxidant activities of essential oil, extracted from the leaves of Neolitsea aciculata (Blume) Koidz by the hydrodistillation method. To the end, the chemical composition of N. aciculata leaf oil was firstly analyzed through GC/MS. The major constituents of essential oil were found to be: cis-ocimene (11.00%), trans-ocimene (9.65%), elemol (9.15%), ${\beta}$-elemene (8.75%), germacrene-D (7.55%), trans-caryophyllene (5.90%), ${\gamma}$-elemene (5.40%) and ${\tau}$-muurolol (4.95%). Then, the antioxidant potential of the essential oil was evaluated by the methods of total polyphenolic content (TPC) assay, DPPH radical scavenging activity, ABTS radical scavenging activity and ferric reducing antioxidant power (FRAP). It was estimated that the total polyphenolic content of the oil was $136.7{\pm}0.13\;mg\;GAE/g$ and the efficient concentration of the oil required to scavenge 50% DPPH radicals ($EC_{50}$ value) was $639.33\;{\mu}g/m{\ell}$. Also, ABTS radical scavenging activity was identified to be concentration dependent, while the FRAP value was $31.21{\pm}0.12\;{\mu}M$ $FeSO_4{\cdot}7H_2O/g$. Such figures, as a result, suggest that the essential oil extracted from the leaves of N. aciculata has its antioxidant activity, which can serve as significant health functional benefits.