• Journal of Ocean Engineering and Technology
• /
• v.10 no.3
• /
• pp.14-23
• /
• 1996

The corrosion fatigue test were carried out to evaluate the fatigue characteristics of accelerated cooled (ACC) TMCP high tensile strength steels and weld joint with high heat input by one side one run submerged are welding. In this paper, the fatigue crack growth behaviors were investigated with the center crack tension specimen of base metal and heat affected zone in substitute sea water and air, respectively Main results obtained are sunnarized as follows: 1. The fatigue crack growth rates in sea water faster than those in air environment for the different heat input values, crack growth rate of base metal is very fast and effect of heat input is not remarkable. 2. In HAZ (82kJ/cm, 116kJ/cm), the crack branching phenomena were observed in both air and sea water environment, 3. In SEM observation, the corrosion effect on base metal was larger than that on HAZ in corrosion environment.

• Journal of Smart Tourism
• /
• v.2 no.3
• /
• pp.5-15
• /
• 2022

As the utilization of technology in the tourism field becomes familiar, it greatly impacts people's tourism activities. These changes could also affect the behavior of tourists during the pandemic. To investigate consumers' adaptation to the self-service technology (SST) environment during the coronavirus disease of 2019 (COVID-19) pandemic, we adopted a model of absorptive capacity as the main framework for empirical research. To track the social effects of COVID-19, consumers' behavioral intentions for four different points in time are collected. The analysis was conducted using latent growth and structural equation modeling. We set the organizational and environmental characteristics as the first step of the model, with assimilation and trust as a middle step. Intention to use a kiosk is placed at the final step as an exploit. Findings indicate that organizational characteristics and environmental characteristics positively influenced assimilation and trust, except for environmental characteristics. Consumers' assimilation in SST encourages immediate intention to use a kiosk. Consumers' trust in kiosks positively impacts both immediate and continuance intention to use a kiosk during COVID-19.

• Proceedings of the KWS Conference
• /
• 2001.05a
• /
• pp.220-223
• /
• 2001

In this study, CT specimens were prepared hem ASTM SA516 which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$, -3$0^{\circ}C$, -6$0^{\circ}C$, -8$0^{\circ}C$, -l$0^{\circ}C$ and -l2$0^{\circ}C$ and in the range of stress ratio of 0.1, 0.3 by means of opening mode displacement. At the constant stress ratio, the threshold stress intensity factor range ΔK$_{th}$ in the early stage of fatigue crack growth ( Region I ) and stress intensity factor range ΔK in the stable of fatigue crack growth ( Region II) was increased in proportion to descend temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm da/dN - ΔK in Region II, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It assumed that the fatigue crack growth rate da/dN is rapid in proportion to descend temperature in Region H and the cryogenic-brittleness greatly affect a material with decreasing temperature.e.greatly affect a material with decreasing temperature.

• Korean Journal of Environment and Ecology
• /
• v.16 no.1
• /
• pp.1-9
• /
• 2002

This study was carried out to examine the tree-ring growth characteristics of Pinus thunbergii Parl. after replanting on the reclaimed land from the sea in Kwangyang bay, The factors, mostly affecting the growths of Pinus thunbergii Parl. , were the replanting stress and drought. The growth reduction due to replanting occurred in the replanting year and following year, but that due to drought after 2-3 years of replanting. The growth recovery after replanting differed with soil condition. The sites showing fast recovery were the covered ground of improve soil, the ground of medium mounding, the top and the slope ground of big mounding sites. The filled ground of improve soil and the lower ground of big mounding sites showed retarded growths. The mean sensitivity(year-to-year variation) and the coefficient of variation(tree-to-tree variation in a certain year) in tree rings of Pinus thunbergii Parl. were higher in the poor soil sites than in the favourable soil ones. The physical characteristics of the soil, especially soil hardness, were the most crucial. The mean sensitivity and the coefficient of variation were also low in the salty soil environment.

• Korean Journal of Agricultural Science
• /
• v.50 no.2
• /
• pp.223-234
• /
• 2023

Appropriate fertilization methods are required according to species to supply necessary nutrients to plants and prevent soil environmental contamination in nurseries. In this study, the effects of nitrogen and phosphorus fertilization on the growth of Liriodendron tulipifera and soil characteristics were investigated. After 16 fertilization treatments (4 levels of nitrogen × 4 levels of phosphorus) were applied to one-year-old L. tulipifera seedlings at the Yongmun Nursery Station of the Korea Forest Service, height, root collar diameter (RCD), biomass, leaf nutrients, and soil characteristics were investigated. The height increased as the amount of nitrogen and phosphorus fertilization increased, and the RCD was the highest in the ×2 treatment. Biomass growth was on average 40.0% higher for the treatment with high nitrogen fertilization compared to the low nitrogen treatment. The seedling quality index was the highest with nitrogen and phosphorus ×2 treatment. Leaf phosphorus and magnesium concentrations decreased when nitrogen fertilization was applied, and leaf potassium concentrations decreased as nitrogen fertilization increased. Soil pH and exchangeable potassium decreased as the amount of phosphorus application increased, and exchangeable magnesium decreased as the amount of nitrogen application increased and increased as the amount of phosphorus application increased. Considering the growth of L. tulipifera seedlings and changes in the soil characteristics at the nursery stage, twice the standard fertilization amount is the appropriate fertilization amount for nursery of the Yongmun Nursery Station. It is expected that this study will contribute to improving nursery soil fertilization management technology for healthy seedling production.

• Journal of Korean Society for Atmospheric Environment
• /
• v.3 no.1
• /
• pp.13-26
• /
• 1987

One-year-old seedlings of Ginkgo biloba, potted in three different soils (nursery soil, mixed and sandy soil), were treated with simulated acid rain (pH 2.0, 3.0, 4.0 and 5.0) and tap water (control, pH 6.4) during the growing seasons (1985. 4. 28 - 1985. 10. 19) to examine the effects of acid rain on growth and physiological characteristics, and the relations between seedling growth and physiological characteristics. The results obtained in this study were as follows: 1. The effects of soil types on the total, top and root dry weight per seedling were significant at 5% level, and those of the pH of the rain treated at 1% level. The total dry weight of the pH 3.0 sub-plots was the highest for nursery soil, while for mixed and sandy soils, those of the control and the pH 5.0 sub-plots were the highest, respectively. 2. The leaf surface areas of pH 2.0 sub-plots severely decreased after July, but those of other sub-plots were not affected. The correlations between growth and leaf surface area differed among soil-types, however, the highest positive correlation was found in September. 3. The injured leaf rate increased with decreasing pH levels of acid rain. Highly negative correlations between growth and injured leaf rate were found. 4. The lower the pH level of acid rain treated was, the more the chlorophyll content was measured at the beginning of treatment, and the more severely it decreased at late growing season. A negative correlations were found in August, September and Octobfer. 5. The photosynthetic ability decreased rapidly after July with decreasing pH levels. A highly positive correlation between growth and photosynthetic ability was found in August.

• Journal of Bio-Environment Control
• /
• v.20 no.1
• /
• pp.8-13
• /
• 2011

This research was carried out to investigate relationship between underground part environment control and growth or yield of sweet pepper in greenhouse as affected by covering materials. Daily amount of applied nutrient solution for research period in the greenhouse of plasticfilm house was more 1.6 times than that in glass house. But daily absorptance rate of nutrient solution and specific electrical conductance of rockwool between two greenhouses were not different in the range of 71.3-73.3% and $4.17{\sim}4.23dS{\cdot}m^{-1}$ respectively. Leaf area of sweet pepper, in leaf growth characteristics in two greenhouses, were $123.0cm^2$/leaf (in glass house) and $119.5cm^2$/leaf (in plasticfilm house), but the another (fresh and dry weight, dry matter) were not different. But weekly yield per square meter in glass house was more 1.3 times than that in plasticfilm house as $850g{\cdot}m^{-2}$ and $650g{\cdot}m^{-2}$, respectively. Effect of slab EC and absorptance rate of nutrient solution on leaf growth characteristics and yield between two greenhouses were not different. The results show when sweet pepper is cultured in greenhouse as affected by covering materials and above ground part environment, the plant growth and yield are little affected by underground part environment.

• Environmental Engineering Research
• /
• v.10 no.6
• /
• pp.283-293
• /
• 2005

Characteristics of sulfur-based autotrophic denitrification in a semi-continuous type reactor and the kinetic parameters were studied. Enriched autotrophic denitrifying culture was used for the reactor operation. Biomass growth on sulfur particles and in the liquid medium was monitored using the DAPI staining method. From the result of ion concentration changes and the biomass growth, maximum specific growth rate, ${\mu}_{max}$, and the half velocity constant, $K_M$, were estimated as $0.61\;d^{-1}$ and 3.66 mg/L, respectively. Growth yield coefficient, Y values for electron acceptor and donor were found as 0.49 gVSS/g N and 0.16 gVSS/g S. The biomass showed specific denitrification rate, ranging 0.86-1.13 gN/g VSS-d. A half-order equation was found to best simulate the denitrification process in the packed bed reactor operated in the semi-continuous mode.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.48 no.6
• /
• pp.434-437
• /
• 2003

This study was carried out to obtain basic information for environment of native area and growth characteristics under various mulching materials in Dendropanox morbifera $\textrm{L}_{EV}$, Dendropax c morbifera was grown wild at Wando area, particularly, distribution frequency was high at 20 to 280 meters above the sea level, and configuration of the ground of native area descended slowly toward the southeast. The soil characteristics of native area was pH 5.3-5.5, 8.8-9.5% in organic matter content and 19.8-22.0% in soil moisture. Growth of Dendropanox morbifera $\textrm{L}_{EV}$, was accelerated by transparent polyethylene film and black polyethylene film mulched.

• Korean Journal of Environmental Biology
• /
• v.30 no.1
• /
• pp.1-8
• /
• 2012

To understand growth characteristics of eight dominant red tide species ($Prorocentrum$ $minimum$, $Heterocapsa$ $triquetra$, $Scrippsiella$ $trochoidea$, $Akashiwo$ $sanguinea$, $Chattonella$ $marina$, $Heterosigma$ $akashiwo$, $Amphidinium$ $carterae$ and $Rhodomonas$ $salina$) in the Korean coastal water, the growth rates were examined in relation with the impacts of water temperature and bio-volume. Of these, $P.$ $minimum$, $C.$ $marina$, $H.$ $akashiwo$, $A.$ $carterae$ and $R.$ $salina$ were eurythermal species with relatively high growth rates in a borad ranges (15 to $25^{\circ}C$) of water temperature. On the other hand, the growth rate of $H.$ $triquetra$, $S.$ $trochoidea$ and $A.$ $sanguinea$ were high in relatively mid temperature (optimum: $25^{\circ}C$) condition. In particular, $H.$ $triquetra$ was well adapted in low temperature of 5 to $15^{\circ}C$, implying that the species can survive and grows even at very low temperature. Based on results of our experiment, the growth characterestics of five eurythermal species and three mid temperature species may have dominated in Korean coastal water during summer season and fall season, respectively. Contrastively, the growth characteristics of $H.$ $triquetra$ make a consistently dominant during the cold winter season. In addition, the growth rates of large bio-volume species were lower than those of small bio-volume species, indicates that growth of single cells of several flagellates might be depended on the cells sizes.