• Asian Journal of Turfgrass Science
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• v.23 no.1
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• pp.61-76
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• 2009

The purpose of this study are to investigate the reasonable maintenance expense of golf course according to the size and management system of each golf course. The maintenance cost per hole per golfer of 29 golf courses and the maintenance cost for items and locations of 8 golf courses were analyzed. 1. As golfers per hole increased, maintenance cost per hole per golfer decreased. 2. The decisive cost factors for maintenance cost of golf course are the number of annual golfers, the total course size, the management system, and automation of course facilities. 3. Maintenance cost of golf courses contained the landscaping areas except for building and parking lots is $869^{\}/_{m^2}$ Korean won. 4. Average maintenance cost of 8 golf courses is $44,325,000^{\}/_{hole}$. 5. Labor cost marked the largest portion in the total cost. Among the items of labor cost, repair cost for green ball mark was the highest with the ratio of 26%(\4,163,000). 6. Material cost for Fairways which reaches 30% of the total area was composed of $22%{\sim}44%$ of the total cost of materials. Cost of imported fertilizers, pestcides for insects and diseases, and sands for top dressing was the highest. 7. Material cost for Green which reaches 2% of the total area was composed of $28%{\sim}36%$ of the total cost. Cost of imported products such as particle-shaped fertilizers, micro mineral fertilizers, and soil conditioners was the highest. 8. There is no difference in cost between chemical fertilizers and the environmentally friendly fertilizers even if environmentally friendly fertilizers using microorganism or chitosan materials are also expensive.

• Asian Journal of Turfgrass Science
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• v.23 no.1
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• pp.45-60
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• 2009

Occurrence ecology and possibility of mass trapping of Popillia quadriguttata, one of the most serious turfgrass insect pest in domestic golf courses was investigated using pheromone traps in Gimpo and Jinhae. Peak period of adult occurrence of P. quadriguttata was late June and early July in Gimpo Seaside Country Club from 2006 to 2008. It was early and middle July in Youngwon Country Club in 2006. The first catched day of P. quadriguttata adult was 20 June, while the last day was 10 September in Gimpo Seaside Country Club, 2006. Mean catched number of P. quadriguttata adult in Japanese beetle pheromone trap per day in peak period of occurrence were 18.2, 25.7, 29.0, and 15.7 at 2005, 2006, 2007 and 2008 respectively. Mean catched number of P. quadriguttata adult in Japanese beetle pheromone trap were more in fairways or roughs than tees or greens. Possibility of control of scarab beetle using pheromone trap with pesticide treatment was investigated against oriental beetle, Blitopertha orientalis in Dongrae Benest Golf Club. Mean number of dead oriental beetle adult were more higher(2.9 folds) in fenitrothion EC treatment than fenitrothion EC treatment after set oriental beetle pheromone trap.

• Journal of the Korean Data and Information Science Society
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• v.24 no.3
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• pp.543-555
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• 2013

This study is to analyze effectiveness of golf skills (driving distance, rating of fairway, green in regulation, sand save ratio, recovery ratio, putting average) to average score using records of PGA, LPGA, KPGA, KLPGA. Independent variables were driving distance, rating of fairway, green in regulation, sand save ratio or recovery ratio, putting average. Dependent variable was the scoring average in this study. To analyze these variables, multi-group (PGA vs LPGA, KPGA vs KLPGA, PGA vs KPGA, LPGA vs KLPGA) path analysis was used through AMOS 18.0 program and significance level was set at 0.05. As the result, the variables that show significant differences of path coefficient between PGA model and LPGA model were driving distance and green in regulation to average score. The variables that show significant differences of path coefficient between KPGA model and KLPGA model were driving distance, recovery ratio, and putting average to average score. The variables that show significant differences of path coefficient between PGA model and KPGA model were driving distance, recovery ratio, and putting average to average score. There was not significant difference of path coefficient between LPGA model and KLPGA model.

• Asian Journal of Turfgrass Science
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• v.17 no.1
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• pp.35-44
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• 2003

Popillia quqdriguttata is a serious insect pest in Korean golf courses. The adult feeds on leaves of latifoliate trees and herbaceous plants while the larva feeds on roots of turfgrass. Thus, control of p. quadriguttata adults was tried with registered insecticides in golf courses in Korea. The insecticides used in the experiments were carbaryl + phosalone WP, chlorpyrifos + diflubenzuron WP, chlorpyrifos-methyl EC, deltamethrin EC, etofenprox WP, etofenprox + diazinon WP, etofenprox + tebufenozide EC, fenitrothion EC, imidacloprid SC, pyraclofos WP, and tralomethrin EC. Mortalities of P. quadriguttata were over 95% in carbaryl + phosalone WP, chlorpyrifos + diflubenzuron WP, etofenprox + diazinon WP, and fenitrothion EC at petri dish and in greenhouse. In the field test, corrected mortality of P. quadriguttata was 95.2% and 80.9% in carbaryl 40% +phosalone 20% WP and fenitrothion 50% EC, respectively. Spreading agent enhanced toxic effect of used insecticides to p. quadriguttata adults except carbaryl + phosalon 20% EC. p. quadriguttata adult was firstly observed to feed on leaves of Canna generalis at the Yongwon golf club in Jinhae, Gyeongnam and Prunus ameriaca var. ansu and p. salicina at the Anyang Honest golf club in Gunpo, Cyeonggi. Therefure, host plants off quadriguftata became 29 species of 26 genera in 19 families. Zoysia matreila at the fairway and roughs of Anyang Benest golf club was damaged by p. quadriguttata larvae in Octomber, 2002 and not recovered in April, 2003. Damaged turfgrass became yellowish and wilted and that retarded recovering in the following spring.

• The Korean Journal of Applied Statistics
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• v.30 no.1
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• pp.41-55
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• 2017

This study predicts the average scores of top 150 PGA golf players on 132 PGA Tour tournaments (2013-2015) using data mining techniques and statistical analysis. This study also aims to predict the Top 10 and Top 25 best players in 4 different playoffs. Linear and nonlinear regression methods were used to predict average scores. Stepwise regression, all best subset, LASSO, ridge regression and principal component regression were used for the linear regression method. Tree, bagging, gradient boosting, neural network, random forests and KNN were used for nonlinear regression method. We found that the average score increases as fairway firmness or green height or average maximum wind speed increases. We also found that the average score decreases as the number of one-putts or scrambling variable or longest driving distance increases. All 11 different models have low prediction error when predicting the average scores of PGA Tournaments in 2015 which is not included in the training set. However, the performances of Bagging and Random Forest models are the best among all models and these two models have the highest prediction accuracy when predicting the Top 10 and Top 25 best players in 4 different playoffs.

• Research in Plant Disease
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• v.14 no.1
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• pp.43-50
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• 2008

Rhizoctonia blight (large patch) caused by Rhizoctonia solani AG2-2 is one of the major diseases on zoysiagrass in golf courses. In this study, anatgonistic bacteria to R. solani AG2-2 were selected in vitro tests using confrontation bioassay and triple layer agar diffusion method. The most active bacteria, Bacillus subtilis CJ-9 were tested for controlling large patch in pots. Relative Performance Indies (RPI) was used as a criterion for the selection of potential biocontrol agent. B. subtilis CJ-9 showed resistance to major synthetic agrochemicals used in golf course. In field tests at golf course, B. subtilis CJ-9 was more effective in suppression of large patch severity and population development of R. solani AG2-2 in soil than chemical fungicides. B. subtilis CJ-9 could be an alternative to chemical fungicides for eco-friendly management of large patch on zoysiagrass.

• Horticultural Science & Technology
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• v.17 no.5
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• pp.572-577
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• 1999

Research was initiated to evaluate plant growth regulator effects on the vertical shoot growth of Korean lawngrass and to determine desirable growth regulator and its rate. The experiments were conducted twice at different sites in 1995. All the tested growth regulators inhibited the growth, but the inhibition period was variable among the product in Experiments I and II. During the first week after treatment, there was approximately 10 to 20% growth reduction in most of the treated plots. In the amidochlor-treated plots, growth suppression was effective for 3 to 4 weeks at low to medium rates ($0.60mL{\cdot}m^{-2}$). A Type II growth regulator, trinexapac-ethyl exceeding the medium rate of $0.08mL{\cdot}m^{-2}$ consistently tended to suppress vertical shoot growth for 8 weeks, being above 35% reduction in both experiments. In the plots applied with mefluidide, growth suppression appeared with foliar discoloration 3 or 4 days earlier than the other growth regulators and continued to work till the 8 weeks after treatment. Suppression intensity on vertical shoot growth increased with time after treatment up to a certain period of time, depending on growth regulators. Generally, the higher the application rate, the greater the suppression intensity. Seasonal variation of activity and effectiveness of growth regulators was observed, resulting in lower suppression intensity in July than in June. It is expected to reduce mowing requirements by 30 to up to 60% for a certain period with a specific growth regulator. In low to medium maintenance of Korean lawngrass turf, a long-term suppression may be more effectively accomplished with trinexapac-ethyl rather than mefluidide and amidochlor in terms of vertical shoot growth inhibition. Therefore, turf managers will need to select proper growth regulator and determine optimum rate of application for turfgrass management, based on a defined period of mowing reduction.

• Journal of the Korean Applied Science and Technology
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• v.37 no.5
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• pp.1190-1199
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• 2020

The purpose of this study is to analyze the variables affecting the effective stroke in the swing performed through 12 weeks of training for golf beginners, and to provide basic data on the effective stroke factors for the golf beginners to settle on the fairway. Twenty subjects were participate in the study (age: 21.35±1.69 yrs, height: 176.75±7.99 cm, weight: 70.70±9.76 kg). All subjects were subjected to a 12-week golf training, and trackman 4 was used in the 12th week to calculate variables affecting the effective stroke during a golf swing. Trackman data was divided into club-variables and ball-variables, and a binary logistic regression analysis was performed to find out the variables affecting effective strokes. In club-variables, high dynamic loft and low face angles were found in effective stroke, and in ball-variables, fast ball speed, large smash factor, high launch angle, and many spin rates were also found in effective stroke. As a result of the binary logistic regression analysis of club-variables, the probability of an effective stroke increased as the club speed and dynamic loft increased, and the probability of an effective stroke decreased as the face angle increased. The influence of effective stroke in the club-variables was in the order of dynamic loft, face angle, and club speed. In the ball-variable, the probability of an effective stroke increased when the lunch angle increased, and the probability of an effective stroke decreased as the lunch direction increased. As a condition to increase the probability of effective stroke based on the results, it is necessary to increase the club speed through high dynamic loft and low face angle during swing through continuous practice. Through this, the probability of effective stroke through increasing the launch angle and decreasing the launch direction will increase.

• Asian Journal of Turfgrass Science
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• v.23 no.2
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• pp.219-228
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• 2009

The construction procedures and artificial turf maintenance program on golf course definitely influence on the distortion of its environment. Soil microbial communities in soil profile were affected directly by those practises on turf areas. In Jeju island, the environmental impact assessment has been required to apply the first quality class granular activated carbon(GAC), which has a high absorbent character to agricultural chemicals, on the soil profiles of golf green system to reduce the pesticide leaching to ground water. This research was carried out to analyze the changes of microbial communities and chemical properties on soil profiles where GAC had been applied at the construction stage at two golf courses in Jeju. The changes of soil microbial population and chemical properties associated with construction methods of soil profile and agrochemical management program were analyzed by monthly at the surface and sub-soil profiles during April through October, 2007. The total numbers of bacteria and fungi, soil moisture content, soil physio-chemical properties were measured on greens and fairways of the both golf courses with different GAC treatment on the green and fairway soil profiles. The results showed that GAC had positive effects on the water holding capacity, pH and EC, however, it did not improved the holding capacity of available nutrients ${NO_3}^-,{NH_4}^+$, and phosphorus by its sorption phenomenon. In microbial count test, the total numbers of bacteria and fungi showed a great variation during sampling dates. That may directly relate to the agrochemical application, however, the ratio of total bacterial number versus total fungus number showed a constant value on a sub-soil of 15~30cm depth. Thus, the construction method of GAC in soil profile, and application of fertilizer and pesticide, both impacted on the changes of microbial population. It's means that the construction method of soil profile and turf management using agro-materials might greatly affect on the turfgrass culture and the environment of golf course.