• Journal of Environmental Science International
• /
• v.28 no.8
• /
• pp.655-667
• /
• 2019

This research aims to identify the possibility of developing A horizon resources that can be used for construction and civil engineering work. As such, the utility of A horizon resources was examined by establishing planting ground through a mixture of soil layers and by analyzing the growth and development of Pinus densiflora. The physicochemical and physical properties of the soil were as follows: the A horizon was sandy clay loam, B horizon was sandy loam, and the mixture of two layers appeared as sandy loam, which was identical to the B horizon. The experimental groups did not show any significant difference in their physical properties of porosity and degree of water-stable aggregates. With regards to chemical properties, the A horizon as well as the mixture of A and B horizon showed acidity while the B horizon showed alkalinity. The figures of organic matter, total nitrogen, available phosphate, and replaceable potassium were greater as the A horizon content increased, whereas the figures of replaceable calcium, replaceable magnesium, and conductivity increased as the A horizon content decreased. As a result of the growth and development of Pinus densiflora in each planting ground, the final survival rates were all above 100%. However, the tree height and the rate of growth for the diameter of root were higher in the order of A horizon > A horizon + B horizon > B horizon,indicating that the increased A horizon content is related to the growth and development of Pinus densiflora. The treatment of soil with improvement agents, used to recover the functions of in-situ soil showing poor growth and development, did not have a clear impact on the soil texture and porosity. However, the degree of water-stable aggregates increased significantly when using O horizon as the soil improvement agent among the types of in-situ soil. In contrast, all items related to the chemical properties showed significant differences following the treatment by soil improvement agents. The survival rate according to the treatment of soil improvement agents for the growth and development of Pinus densiflora was higher in the order of organic horizon = no treatment > compound fertilizer > organic fertilizer + compound fertilizer > organic fertilizer; this result was statistically significant with a marginal significance value of the log-rank test(p < 0.05).

• Journal of Korea Water Resources Association
• /
• v.54 no.3
• /
• pp.181-190
• /
• 2021

In this study, a large-scale levee breach experiment from lateral overflow was conducted to verify the effect of the new reinforcement method applied to the levee's surface. The new method could prevent levee failure and minimize damage caused by overflow in rivers. The levee was designed at the height of 2.5 m, a length of 12 m, and a slope of 1:2. A new material mixed with biopolymer powder, water, weathered granite, and loess in an appropriate ratio was sprayed on the levee body's surface at a thickness of about 5 cm, and vegetation recruitment was also monitored. At the Andong River Experiment Center, a flow (4 ㎥/s) was introduced from the upstream of the A3 channel to induce the lateral overflow. The change of lateral overflow was measured using an acoustic doppler current profiler in the upstream and downstream. Additionally, cameras and drones were used to analyze the process of the levee breach. Also, a new method using 3D point cloud for calculating the surface loss rate of the levee over time was suggested to evaluate the performance of the levee reinforcement method. It was compared to existing method based on image analysis and the result was reasonable. The proposed 3D point cloud methodology could be a solution for evaluating the performance of levee reinforcement methods.

• Journal of Korean Society of Forest Science
• /
• v.100 no.2
• /
• pp.305-313
• /
• 2011

Fertilization is essential to seedling production in nursery culture, but excessive fertilization can contaminate surface and ground water around the nursery. The objective of this study was to find optimal fertilization practice of container seedling production for reducing soil and water contamination around the nursery without compromising seedling quality. This study was conducted to investigate growth performance, photosynthesis, chlorophyll fluorescence, and chlorophyll contents of Liriodendron tulipifera growing under three different fertilization treatments (Constant rate, Three-stage rate, and Exponential rate fertilization). Root collar diameter, height, and biomass of L. tulipifera were the highest at Constant treatment. Like growth performance, seedling quality index (SQI) were higher at Constant than at other treatments, but not significantly different among treatments. L. tulipifera showed good photosynthetic capacity at all treatments. Photochemical efficiency and chlorophyll contents were significantly lower at Exponential than at other treatments. Therefore, Exponential fertilization which is 50% fertilizer of other treatments would maximize seedling growth and minimize nutrient loss.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.41 no.1
• /
• pp.41-46
• /
• 2021

Sorghum×sudangrass hybrid (Sorghum bicolor (L.) Moench, SSH) is one of the most important summer forage crop and it is widely used for silage in Korea. Agriculture is highly dependent on the climate condition and experiencing significant loss of productivity due to climate change. This study was conducted to investigate the correlation analysis between productivity of forage SSH and climatic factors in Central Northern region of South Korea for 3 years (2017 to 2019). Plant height and dry matter yield of SSH were significantly higher in Gyeonggi-do than Ganwon-do. The productivity of SSH is more closely related with temperature than other climatic factors. Maximum temperature and Growing degree days in May and June showed a positive correlation. However, correlation between production of SSH and precipitation was not clear in this study, but rainy days showed a negative correlation (0.42). In conclusion, temperature is most important climatic factor to the maintenance of plant yield.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.26 no.7
• /
• pp.922-930
• /
• 2020

Marine accidents involving fishing boats, caused by a loss of stability, have been increasing over the last decade. One of the main reasons for these accidents is a sudden wind attacks. In this regard, the wind loads acting on the ship hull need to be estimated accurately for safety assessments of the motion and maneuverability of the ship. Therefore, this study aims to develop a computational model for the inlet boundary condition and to numerically estimate the wind load acting on a fishing boat. In particular, wind loads acting on a fishing boat at the wind speed profile boundary condition were compared with the numerical results obtained under uniform wind speed. The wind loads were estimated at intervals of 15° over the range of 0° to 180°, and i.e., a total of 13 cases. Furthermore, a numerical mesh model was developed based on the results of the mesh dependency test. The numerical analysis was performed using the RANS-based commercial solver STAR-CCM+ (ver. 13.06) with the k-ω turbulent model in the steady state. The wind loads for surge, sway, and heave motions were reduced by 39.5 %, 41.6 %, and 46.1 % and roll, pitch, and yaw motions were 48.2 %, 50.6 %, and 36.5 %, respectively, as compared with the values under uniform wind speed. It was confirmed that the developed inlet boundary condition describing the wind speed gradient with respect to height features higher accuracy than the boundary condition of uniform wind speed. The insights obtained in this study can be useful for the development of a numerical computation method for ships.

• Journal of Forest and Environmental Science
• /
• v.38 no.3
• /
• pp.184-194
• /
• 2022

Triplochiton scleroxylon K. Schum is the plant species most affected by logging activities in the East Region of Cameroon due to its market value. This logging has impacted the ecological niche of the fern plant for which limited research has been done. The aim of this study is to contribute towards improving knowledge of fern richness and biomass on T. scleroxylon within the Central African sub-region. Fern data collection was done on 20 felled/harvested T. scleroxylon where, in addition to fern inventory, fern biomass was collected by the destructive method. The diameter and height of T. scleroxylon measured were used as explanatory variables in allometric equations for fern biomass estimation. Fern inventory was characterized using diversity index. Eight fern species were recorded on T. scleroxylon (≈5 species/T. scleroxylon). The minimum diameter where fern could be found is 59.4 cm. The average fern biomass found was 23.62 kg/T. scleroxylon. Pearson correlation coefficient showed a positive correlation (r>0.55) between fern biomass and T. scleroxylon diameter. For allometric equation, the logarithmic model improved better the adjustment than the non-logarithmic model. However, the quality of the adjustment is improved more when only the diameter is considered as an explanatory variable. Fern biomass is estimated to 90.08 kg/ha^-1 with 76.02 kg/ha^-1 being lost due to T. scleroxylon exploitation in the study area. This study is a contribution towards increasing knowledge of fern diversity specific to T. scleroxylon, and also fern biomass contribution to climate change mitigation and the potential carbon loss due to T. scleroxylon exploitation.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.35 no.3
• /
• pp.224-232
• /
• 1990

This study was conducted to find out the improvement of water-logging injury which is an important factor of yield loss in sesame. Water-logging was treated at 10, 25, 40, 55 and 70 days after emergence for 24, 48 and 72 hours in sesame variety 'Ansanggae'. Some important agronomic characters were investigated after treatment. The important agronomic characters such as plant height, leaf area, dry matter weight, capsule setting stem length, number of capsules per plant, ripenning rate and 1,000 grain weight were most susceptible at 55 days after emergence by the water-logging treatment, and the longer period of water-logging, the more susceptible. Allmost of the useful agronomic characters were able to get over injury of water-logging only within 25days after emergence, but could not get it over since 40days. Grain yield was decreased due to the water-logging treatment by 69 to 86% in 55 days after emergence that is most susceptible stage for water-logging as compared with the untreated control which is 13g per pot, and the longer period of water-logging induced the lower yield. Oil content of grain showed significant decrease only in 55 days after emergence but the composition of fatty acid did not influenced by the water-logging.

• Korean Journal of Ecology and Environment
• /
• v.55 no.3
• /
• pp.221-230
• /
• 2022

The spread of invasive alien plants is one of the most important causes of habitat and biodiversity loss. This research was conducted to secure basic data for the control of the invasive alien plant Solidago altissima. The following research objects were examined: the control; one-time mowing in June (1M6); two-time mowing in June and July (2M6M7); one-time mowing in Jun plus one-time Uprooting in July (2M6U7). The length growth in October, when the growth of S. altissima was completed, was in the order of control (199±19.96 cm), 1M6 (152±13.41 cm), 2M6U7 (54±3.17 cm), and 2M6M7 (45±19.96 cm). The 2M6M7 and 2M6U7 treatment was the most effective at inhibiting S. altissima of density, of 50.8% and 26.2% compared to the control, respectively. In contrast, one-time mowing (1M6) resulted in an increase in density compared to the control by 119.7%. In addition, this treatment also reduced flowering rate (%) of S. altissima. The most effective treatment among those tested was 2M6U7.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.28 no.7
• /
• pp.1244-1251
• /
• 2022

Marine accidents due to a loss of stability, have been gradually increasing over the last decade. Measures must be taken on the roll reduction of a ship. Amongst the measures, building an anti-roll tank in a ship is recognized as the most simple and effective way to reduce the roll motion. Therefore, this study aims to develop a computational model for a U-tube type anti-roll tank and to validate it by experiment. In particular, to validate the developed computational model, the height of the free surface in the tank was measured in the experiment. To develop a computational model, the mesh dependency test was carried out. Further, the effects of a turbulence model, time step size, and the number of iterations on the numerical solution were analyzed. In summary, a U-tube type anti-roll tank simulation had to be performed accurately with conditions of a realizable k-𝜖 turbulence model, 10^-2s time step size, and 15 iterations. In validation, the two cases of measured data from the experiment were compared with the numerical results. In the present study, STAR-CCM+ (ver. 17.02), a RANS-based commercial solver was used.

• 한국체육학회지인문사회과학편
• /
• v.51 no.4
• /
• pp.407-417
• /
• 2012

The purpose of the study was to determine the effects of pilates mat exercise on cardiovascular disease risk factors and inflammation markers in sarcopenic obesity elderly. All subjects were sarcopenic obesity(height for each of the arms, legs, appendicular muscle mass ratio of 1.16kg/m², 4.31kg/m², 5.21kg/m² under and % body fat is more than 30%) elderly performed the pilates mat exercise during 12-week for 60 minutes 3 times a weeks. All subjects of this study were examined the changes in cardiovascular disease risk factors(TC, TG, HDL-C, LDL-C, Glucose, Insulin) and inflammation markers(fibrinogen, adiponectin, leptin, CRP). The results of the study in the exercise group were as follows; The weight, % body fat, TC, TG, LDL-C, fibrinogen, CRP had significantly decreased and muscle mass, HDL-C, adiponectin had significantly increased. And also, pilates mat exercise can effective to improve sarcopenic obesity, and pilates mat exercises performed coy shrink obesity to cardiovascular disease and inflammatory response indicators of older women as old man's physical features of the deterioration of the prevention of obesity and muscle strength loss, causing the effective exercise method is meant to be.