• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.2
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• pp.137-145
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• 2022

Objectives: This study aimed to identify PM₁₀ mass concentration levels and conduct peak identification during five tasks in agricultural works. Methods: We investigated five agricultural tasks in 12 farms, which were harvesting, plowing, sowing, planting, and decapitation. All samples were measured by using the portable aerosol spectrometer(PAS 1.108) and the aerosol monitor(SidePak AM520). The collected data were compared with the national PM₁₀ concentrations. They were calculated to descriptive statistics, independent t-test, or ANOVA, and the peak identification on time series graph. Results: The ten investigated farms showed no significant difference with the national PM₁₀ concentrations, but the two greenhouses(AM, 143.31, 85.16 ㎍/m³) showed significant difference(p<0.05). As a result of the peak identification, the harvesting tasks showed repeated peak occurrence with the background concentration level of about 50 ㎍/m³. For plowing and sowing tasks, the peak occurred intermittently when the working was conducted near the sampling sites. Among the five tasks, the arithmetic mean of the harvesting task was 138.84±294.71 ㎍/m³, which was significantly higher than the other tasks(p<0.05). In addition, the case of using a tractor was higher than the case of not using the tractor(p<0.05), and the driver's seat showed the highest concentration(AM, 95.81 ㎍/m³). Conclusions: Works in greenhouses might have exposure to PM₁₀, while outdoor works is similar to general atmospheric PM₁₀ concentration levels. However, there is a possibility of intermittent exposure to high concentrations of PM₁₀ depending on the characteristics of agricultural tasks.

• Korean Journal of Organic Agriculture
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• v.24 no.4
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• pp.919-929
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• 2016

This study investigated the effect of organic materials (Bordeaux, Loess-sulfur) and the removal of apical shoot against downy mildew disease on cucumber cultivated in greenhouse. Five kinds of Bordeaux were made by adjusting mixing ratio of lime and copper sulfate in order to elucidate the optimal combination. The 4-6type Bordeaux was selected as the most effective combination for controlling cucumber downy mildew. Loess-sulfur showed inhibitory activity against cucumber downey mildew, but it was less effective than Bordeaux. It was confirmed that apical shoot cutting could reduce the incidence of cucumber downy mildew disease by 56.3%. When apical shoots of susceptible cucumber variety were cut at different leaf stages, disease incidence by early apical shoot cutting treatment was lower than that of late apical shoot cutting treatment. However in a resistant variety, 'Heukryungsamcheok', disease incidences of all cucumber apical shoot cutting treatments were lower than that of non-cutting treatment, but there was no differences between apical shoot cutting treatments due to low disease incidences. In addition, when organic materials and apical shoot cutting treatment were carried out in parallel, the combined treatments of organic materials and apical shoot cutting showed low disease incidence of cucumber downy mildew compared to untreated control. The lowest disease incidence of cucumber downy mildew was recorded in the combined treatment of 4-6type Bordeaux and apical shoot cutting. This study confirmed that apical shoot cutting can reduce the disease incidence of cucumber downy mildew and the combined treatment of apical shoot cutting and organic materials showed higher suppressive effect against cucumber downy mildew.

• Korean Journal of Applied Biomechanics
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• v.17 no.4
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• pp.201-208
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• 2007

The purpose of this study is to compare 4 different body punch types(type 1: a punch using a shoulder, type 2: a punch using a waist, type 3: a punch using lower extremities, and type 4: a punch with elbows by your side at chest level) in horseback-riding stance and establish suitable teaching theory and method, which would be a useful reference to Taekwondo instructors on the spot(in Taekwondo dojangs all around Korea). Five exhibition players from Korean national Taekwondo exhibition team participated in this study. Each participant was asked to perform the four different types of punches and their kinematic and kinetic data were recorded with 7 vicon cameras(125Hz) and two force plates(AMTI, 1200Hz). We analyzed displacement, time, resultant center of body mass trajectory, velocity, trunk angular velocity, and ground reaction force(GRF) from each body segment in body punch and the result. I performed 1-way ANOVA(RM) for average values of each player after standardization and statistical significance was set as p<.05. was as the following ; First, they showed a tendency to take the body punch posture with the biggest motion at a shoulder and on descending order a waist and a knee. Second, a mean time for each body punch on ascending order 0.46sec. for type 2, 0.49sec for type 3, 0.50sec. for type 4, and 0.56sec. for type 1. Third, a mean resultant center of body mass trajectory for each body punch the longest 4.07cm for type 3 and the shortest 2.458cm for type 1. Fourth, a mean of maximal velocity of a fist strike was the fastest 5.99m/s for type 3, 5.93m/s for type 4, 5.67m/s for type 2, and 5.01m/s for type 1 on the descending order. Fifth, a mean of maximal trunk angular velocity of the fastest 495.6deg./sec. for type 4 and 337.7deg./sec. for type 1 on the descending order. Sixth, strongest value was type 3, 2 for anterior-posterior ground reaction force(left -54.89N, right 60.58N), type 4 for medial-lateral GRF(left 83.59N, right -80.12N), and type 3 for vertical GRF(left 341.79N, right 426.11N).