• Bulletin of the Korean Chemical Society
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• v.31 no.1
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• pp.157-161
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• 2010

A sensory element against carbaryl, as a widely used pesticide was prepared based on adsorbed acetylcholine esterase (AChE) from Torpedo california. Octadecyl was substituted on macro-porous silica, confirmed by infra-red (IR) spectroscopy and quantitatively estimated through thermo-gravimetric analysis (TGA). Immobilization of the enzyme was achieved by adsorption on this support. Activity of the immobilization product was measured as a function of the loaded enzyme concentration, and maximum binding capacity of the support was estimated to be 43.18 nmol.mg-1. The immobilized preparations were stable for more than two months at storage conditions and showed consistency in continuous operations. Possible application of the immobilized AChE for quantitative analysis of carbaryl is proposed in this study.

• The Korean Journal of Pesticide Science
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• v.6 no.1
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• pp.16-24
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• 2002

Research trends in the measurement of foliar uptake of pesticides and the recently proposed action mechanism of the surfactant-induced uptake of pesticides were reviewed with the related reports and studies. Major techniques used in those fields are bioassay, radiotracer techniques with leaves or cuticular membrane. Recently, a new method using Congo Red as a tracer was proposed. The limiting factor in the pesticides uptake into leaves is the waxy layer which consists of the epicuticular and cuticular wax. Physico-chemical parameters such as molar volume, water solubility and partition coefficient of pesticides have limited influences on the pesticide uptake into leaves. Polydisperse ethoxylated fatty alcohol surfactants are well known as the good activator for many pesticides. It is now generally agreed that uptake activation is not related to the intrinsic surface active properties of surfactants such as surface activity, solvent property, humectancy and critical micelle concentration. Recent studies using ESR-spectroscopy revealed that the surfactants have an unspecific plasticising effect on the molecular structure of the wax and cuticular matrix, leading to increased mobilities of pesticides. Penetration of surfactants into waxy layer altered the pesticide mobility in wax and the partition coefficient of pesticide, and then the pesticides penetration into leaves was enhanced temporally. The enhancing effect of surfactant could be significantly different depending on the carbon number of aliphatic moiety and the number of ethoxy group in polyoxyethylene chain of surfactants. It is suggested that the rate of penetration of surfactants should have a significant relationship with the rate of penetration of pesticides.

• Journal of Biosystems Engineering
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• v.33 no.1
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• pp.14-20
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• 2008

An agricultural unmanned helicopter was suggested for an alternative to current pesticide application methods to solve such problems as high cost, low efficiency, shirking task and unsafe work. To pursuit this trend, researches on the development of unmanned helicopters have been accelerated in Korea as well. In this research, a guide type centrifugal clutch that plays an important role in the unmanned helicopter was studied. Theoretical analyses and experimental tests were conducted for designing an optimal clutches. Main design factors of the guide type centrifugal clutch were found to be spring constant, free length of spring, mass of friction sector, contact area, allowable pressure, number of friction sector, friction coefficient, radius of drum, and clutch arrangement. And these design factors could be the functions of engaging engine speed and desired power transfer capacity. The result of the single clutch test showed the power transfer capacity of 14.1 PS at 5,800 rpm and the result of the dual clutch test showed that the capacity of 17.7 PS at 5,600 rpm. These experimental results agreed well the theoretical simulations.

• The Korean Journal of Community Living Science
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• v.24 no.2
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• pp.187-194
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• 2013

The purpose of this study was to define the optimal boxthorn berries washing method for developing the boxthorn berries cleaner. We analyzed the rate of removal of residual pesticides according to washing methods; 1st - habitual washing method, 2nd - drum rotation washing method, 3th - drum rotation and air bubble washing method, 4th - drum rotation and nozzle spray washing method, 5th - drum rotation and air bubble and nozzle spray washing method. A rate of removal of residual pesticides of 88% was detected in the drum rotation and air bubble and nozzle spray washing method, and a rate of 82% was detected in the habitual washing method. The drum rotation and air bubble and nozzle spray washing method appeared to be the best good washing effect compared to the habitual washing method(about 6% compared to 82.0% higher). Clothianidin Triadimefon, Triforine ingredients, the drum rotation and air bubble and nozzle spray washing method efficiency was lower compared to the habitual washing method removal efficiency.

• Korean Journal of Agricultural Science
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• v.39 no.4
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• pp.545-553
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• 2012

In Asia, including Japan and Korea, rice paddies occupy the largest cultivated area in agricultural land. Rice paddies provide the habitats for many organisms including endemic species, sustaining high biodiversity. Insect natural enemies inhabiting rice paddies have an important function for rice production as agents of 'ecosystem services' because they play a major role in suppressing rice pests. The diversity and abundance of natural enemies can be a good index reflecting the 'healthiness' of agro-ecosystem services in rice paddies. The present study investigates whether insect natural enemies could be good biological indicators for general arthropod biodiversity and agricultural practice. First, the concept of ideal bio-indicators was summarized. The strategy to explore and select such bio-indicators was then proposed. Lastly, field survey was made to evaluate the abundance and biodiversity of natural enemies in Japanese rice paddies where chemical inputs, i.e., insecticide use, were different. The results showed that reduction of chemical inputs led to an increase in species richness or diversity of natural enemies including parasitoids and predators. Then, the data were analyzed to examine suitable indicator species to assess environmental soundness of agricultural practice and biodiversity in rice paddies. The density of several species of natural enemies did respond both to pesticide use and to general arthropod biodiversity. The analyses thus have indicated that natural enemies can be suitable as bio-indicators. Usefulness of indicator species in rice paddies is discussed in the context of ecologically sound agriculture.

• The Korean Journal of Pesticide Science
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• v.17 no.2
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• pp.107-116
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• 2013

Polar pesticides like pymetrozine (log $P_{ow}$: -0.18) are known to be difficult to analyze. The analytical method of pymetrozine using hydromatrix included in the official method of KFDA was uncommon and provided ambiguous evidence to confirm both the identity and the quantity. Therefore, precise single residue analytical method was developed in representative crops for using liquid-liquid extraction (LLE). The pymetrozine residue was extracted with methanol from 11 representative crops which comprised apple, blueberry, broccoli, cabbage, cherry, crown daisy, hulled rice, Korean cabbage, potato, rice and watermelon. The extract was purified serially by liquid-liquid extraction (LLE) and silica solid phase extraction (SPE). For rice and hulled rice samples, n-hexane partition was additionally adopted to remove nonpolar interferences, mainly lipids. The residue levels were analyzed by HPLC with DAD, using $C_8$ column. LOQ (limit of quantitation) of pymetroizinie was 1 ng (S/N > 10) and MQL (method quantitation limit) was 0.01 mg/kg. Mean recoveries from 11 crop samples fortified at three levels (MQL, 10 ${\times}$ MQL and 50 ${\times}$ MQL) in triplicate were in the range of 83.1~98.5% with coefficients of variation (CV) of less than 10%, regardless of sample type, which satisfies the criteria of KFDA. The method established in this study could be applied to most of crops as an official and general method for analysis of pymetrozine residue.

• The Korean Journal of Pesticide Science
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• v.3 no.2
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• pp.86-89
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• 1999

A series of methanesulfonamide (I a- I g) and phenylhydrazone (IIa-IIh) derivatives were synthesized and their fungicidal activity in vitro against gray mold (BC: Botrytis cinerea), phytophthora blight (PC: Phytophthora capsici) and sheath blight (RS: Rhizoctonia solani) were measured by agar dilution method. The (II) deriviatives showed higher activity than ( I ) derivitives. And the relative orders of the fungicidal activity are BC=PC>RS, Among these compounds, 3-chlorophenyl substituent, IIg showed the most highest activity ($pI_{50}=3.96$) against PC. From the parameter focusing technique, major factors on the activity were ovality, polar and logP constant and so on.

• The Korean Journal of Pesticide Science
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• v.11 no.2
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• pp.82-86
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• 2007

Methanol extract obtained from aerial parts of Vitis vinifero L. was successively fractionated with n-hexane, ethylacetate, n-butanol, and water. From ethylacetate fraction, an active compound was isolated through silica gel column chromatography and recrystallization, and was identified as Lup-20(29)-ene-3,28-diol on the basis of EI-MS data. The compound, at 100 mg $mL^{-1}$, inhibited the mycelial growth of Phytophthora capsici and Colletotrichum acutatum by 52.1 % and 40.8%, respectively.

• Korean Journal of Organic Agriculture
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• v.22 no.4
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• pp.695-703
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• 2014

We experimented with the effect of oleic acid and its appropriate concentration to prevent powdery mildew eco-friendly in a cucumber greenhouse cultivation. 'Baekbongdadaki' (Nongwoo Bio. co. Korea) was treated in the plastic greenhouse at Sangmyung University. We treated four levels of concentration of oleic acid, which were 0, 2000, 4000, 6000, and 8000 ppm. There were investigated diseased severity, diseased leaf area, control value, and pesticide injury. The degree of control values by oleic acid treatments was investigated at 3 days after treatment. The recurrence of powdery mildew was checked for 55 days. The day and night temperature in the greenhouse were controlled to 23 and $15^{\circ}C$ respectively. The humidity inside the greenhouse was not controlled to prevent outbreak of the disease. From the experimental results, oleic acid was very efficient to control powdery mildew. 2000 ppm of oleic acid was shown to be the most control efficiency without any pesticide injury. The recommended method to treat it was to spray three times every 3 weeks.

• The Korean Journal of Pesticide Science
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• v.16 no.1
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• pp.78-83
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• 2012

The recommended species in fish acute toxicity test for pesticide registration in korea are common carp (Cyprinus carpio), killifish(Oryzias latipes) and loach(Misgurnus anguillicaudatus). But most of fish toxicity was evaluated using common carp. The common carp has several problems such as difficulty of room breeding, difference of sensitivity to breeding condition, limited experimental period, etc. For that reason, it is necessary to reexamine of test species. The present study investigated the sensitivity and correlation of $LC_{50}$ values that determined using the acute toxicity test with common carp and killifish. And this study is a realistic approach to evaluated appropriate species for fish acute toxicity test of pesticide. As a result, correlation coefficient(R) of the commom carp and killifish was high correlation of 0.8480 and the $LC_{50}$ values was not significant in the interspecies sensitivity. When the $LC_{50}$ values of common carp and killifish was compared with fish toxicity guideline in Korea, fish toxicity class has fluctuated in 18 pesticides with not very special tendency. Therefore, it is necessary to review of killifish has more advantage to standardization of fish culture and in the side of correlation and sensitivity of acute toxicity.