• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.2
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• pp.68-75
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• 2017

Demand for dwarf mondo grass (DMG; Ophiopogon japonicus 'Nanus') as an ornamental garden plant is expected to grow in the future. The purpose of this study was to investigate the levels of shade tolerance and ground cover by growing DMG under a variety of shade conditions for 18 months (May 2015~October 2016). DMG plants grown in bare ground for 3 years in Jangheung-gun, Jeonnam were used for testing. In an experimental site created in Naju city in Jeonnam, the DMG was planted in planters ($70cm{\times}70cm{\times}24cm$) and covered with a shading curtain to block natural light. Shaded conditions were then arranged under different levels of shade (0%, 55% and 75%). When the plants were grown, growth (leaf size, the number of leaves, fresh weight and dry weight) and ground coverage of DMG were analyzed. According to the results, DMG growth in terms of leaf size and the number of leaves was statistically higher under zero shade (full sunlight), when compared to other shaded conditions. DMG's fresh and dry weights were significantly greater under 0% and 55% shade, compared to those under 75% shade. The degrees of shade tolerance required for normal growth of DMG were found in the range of 0~50%, meaning that more than 50% shade may decrease plant growth. There were no statistical differences in ground coverage rates of DMG under different levels of shade. When 220 tillers were planted per $1m^2$ of plot, up to 80% of the area was covered by DMG after 18 months. Since DMG requires nutrient-rich soil to grow, sufficient nitrogen fertilizers are proposed to accelerate the ground cover of DMG. As DMG remained alive over the winter in the experiments, this study also suggests that DMG can be planted in the southern temperate region.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.6
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• pp.1-5
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• 2008

As bare Fiber Bragg Grating (FBG) sensors are very fragile, bare FBG without encapsulation is not properly applied in practical infrastructures directly due to the harsh environment in practical engineering. Steel sleeve packaged FBG strain sensor is widely used in civil engineering. Since FBG senses both strain and temperature simultaneously, for accurate measurement of strain, temperature compensation for FBG strain sensors is indispensable. In this paper, based on the FBG's strain and temperature sensing principles, the temperature compensation techniques for steel sleeve packaged FBG sensors are brought forward. And the experiment of concrete early-age shrinkage monitoring by dual FBG sensors is carried out to test the feasibility of the temperature compensation technique.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3A
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• pp.265-275
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• 2010

Concrete filled steel tube and concrete encased steel tube columns are expected to have confined effects of concrete by steel and reinforced effects of local buckling by concrete. On the basis of confined state concrete models of previous researches, stress-strain and load-displacement relations of RC, CFT and CET columns are analyzed by steel ratio. After comparing analysis results with experimental results, Modified stress-strain relations are derived through evaluation the influence upon confined effects of concrete in each cases. Also, the modified stress-strain models are carried out to be compared with specified strength of various countries.

• Korean Journal of Remote Sensing
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• v.39 no.5_3
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• pp.1009-1029
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• 2023

Urban trees play a vital role in urban ecosystems,significantly reducing impervious surfaces and impacting carbon cycling within the city. Although previous research has demonstrated the efficacy of employing artificial intelligence in conjunction with airborne light detection and ranging (LiDAR) data to generate urban tree information, the availability and cost constraints associated with LiDAR data pose limitations. Consequently, this study employed freely accessible, high-resolution multispectral satellite imagery (i.e., Sentinel-2 data) to estimate fractional tree canopy cover (FTC) within the urban confines of Suwon, South Korea, employing machine learning techniques. This study leveraged a median composite image derived from a time series of Sentinel-2 images. In order to account for the diverse land cover found in urban areas, the model incorporated three types of input variables: average (mean) and standard deviation (std) values within a 30-meter grid from 10 m resolution of optical indices from Sentinel-2, and fractional coverage for distinct land cover classes within 30 m grids from the existing level 3 land cover map. Four schemes with different combinations of input variables were compared. Notably, when all three factors (i.e., mean, std, and fractional cover) were used to consider the variation of landcover in urban areas(Scheme 4, S4), the machine learning model exhibited improved performance compared to using only the mean of optical indices (Scheme 1). Of the various models proposed, the random forest (RF) model with S4 demonstrated the most remarkable performance, achieving R² of 0.8196, and mean absolute error (MAE) of 0.0749, and a root mean squared error (RMSE) of 0.1022. The std variable exhibited the highest impact on model outputs within the heterogeneous land covers based on the variable importance analysis. This trained RF model with S4 was then applied to the entire Suwon region, consistently delivering robust results with an R² of 0.8702, MAE of 0.0873, and RMSE of 0.1335. The FTC estimation method developed in this study is expected to offer advantages for application in various regions, providing fundamental data for a better understanding of carbon dynamics in urban ecosystems in the future.

• The Hankook-Saengyark Bo
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• no.240
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• pp.5-5
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• 2000

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.3
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• pp.274-285
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• 1996

These experiments were conducted to evaluate the effects of seed coating with ten environmentally acceptable polymers, on germination percentage, water uptake, respiration, emergence and seedling growth characteristics. The water absorption of polymer-coated seeds in saturation condition was highest in klucel and lowest in polyvinyl pyrrolidone(PVP), and that in water was highest in klucel and lowest in maltrin. Respiration rates of polymer-coated seeds in Hwayoungbyeo and Ilpumbyeo were lower than those of none-coated seeds, and those in Daecheongbyeo and Jinmibyeo were higher than that of none-coated seeds, and those of sepiret coated seeds were higher than PVP coated seeds. The germination polimer-coated seed was reduced by one percentage by coating with seed coating machine. Germination percentage was not affected by any of polymer coating in high quality seed, but there were significant effects in low quality seed coating with waterlock, surelease 46 and sepiret significantly reduced germination some cultivars. Germination percentage after accelated ageing treatment were slightly higher most of polymer-coated seeds than in none-coated seeds, but those of sepiret-and klucel-coated seeds were lower significantly. Germination percentage of seeds coated with daran 8600, rnaltrin, sacrust and opadry were enhanced slightly under cold test other polimers reduced germination. The seedling height of polymer-coated seeds were longer than those of none-coated seeds, but those of waterlock, PVP and maltrin coating seeds were shorter, seedling hight was shortened by polimer coating under cold test. Polymer-coated seeds showed higher emergence percentage, shorter emergence time in field condition. The highest emergence percentage and the shortest emergence time was shown at 90% soil moisture content.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.4
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• pp.79-86
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• 2006

This study was investigated to corrosion resistance of Cr-bearing rebars to macrocell corrosion caused by concrete with crack. Ten types of steel bars having different Cr contents were embedded in concretes with imitation crack. The corrosion resistance of the Cr-bearing rebar was examined by measuring half-cell potential, macrocell corrosion current, corrosion area and weight loss up to 105 cycles of salt spray testing. The results revealed that the Cr content required for corrosion resistance in a macrocell corrosion environment caused by chloride ion gap of $3kg/m^3$ was 9% or more. The corrosion-resisting performance of Cr-bearing rebar was particularly noticeable with a Cr content of 11% or more.

• Journal of the Korean Vacuum Society
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• v.4 no.2
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• pp.150-155
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• 1995

Mo 단결정 표면에 황을 흡착시켜 형성된 상층구조를 AES와 LEED로써 연구하였다. 황의 피복률은 sulfur gun으로부터 생성되는 S2 flux로써 조절하였으며, 여러 가지 흡착된 황의 상층구조를 LEED로써 관찰하였다. 황화된 Mo 표면에서 탈산소반응(HDO)의 모델 분자로서, Furan의 흡착과 반응을 승온반응분광법(TPRS)으로 조사하였다. 낮은 온도에서 Furan 분자의 헤테로 원자는 직접 이탈하여 안정한 기체상의 반응 생성물인 일산화탄소를 형성하였으며, 이 반응은 Mo의 (100) 및 (110)면에서 각각 깨끗한 표면 및 황화된 표면에 관계없이 일어났다. 이를 바탕으로 Mo 표면에서 Furan의 분해반응에 대한 메카니즘을 제안하였다.

• Journal of the Korean Institute of Gas
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• v.2 no.4
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• pp.34-41
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• 1998

To oxide film, $A1_2O_3,\;Ta_2O_5$ and $ZrO_2$, coated on stainless steel (SUS410, SUS304) and pure Fe using RF magnetron sputtering method, the corrosion resistance on oxide coatings was studied using electrochemical measurement. Also, the adherence between film and substarte was studied. The adherence index ( $\chi$ ) was determined by the measure of micro hardness test. In this paper, we know that oxide film coated on SUS304 have better corrosion resistance than that coated on SUS410. In oxide film, the difference of corrosion resistance due to crystal structure have not been showed. In evaluating defect area rate of ceramic coated materials, CPCD method can be used effectively. In the micro-hardness test, with $1{\mu}m$ thickness film, it has only one the value of $\chi$. Above $2{\mu}m$ thickness film, however, get another value of $\chi$ as the cracks in film. The oxide film adhere well on the mild materials such as pure steel than high intensity materials like stainless.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.2
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• pp.15-23
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• 2012

This study was accomplished by analyzing the change of land cover pattern in high-rise buildings in Korea. For this study, we selected 15 locations of high-rise buildings. The ratio of average building coverage and paved area was 79.7%, and both green and water area were low, relatively. The biotope area factor of the site showed low percentage by 15.90% due to the underground space development. As a result of correlation analysis between the time of construction and land-cover type, building coverage has been decreased according to the stream of time. However, biotope area factor has been increased And, the paved area has m correlation. It was identified that reducing paved area is effective to enhance the ecological functions of a high-rise building outdoor.