• Journal of Bio-Environment Control
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• v.15 no.4
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• pp.364-368
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• 2006

This experiment was carried out to figure out the $CO_2$ biomass and the growth response of Chinese cabbage and radish grown under the condition of high temperature and high $CO_2$ concentration to provide the information for the coming climatic change. Chinese cabbage and radish were cultivated in spring and autumn seasons under 4 treatments, 'ambient temp.+ambient $CO_2$ conc.', 'ambient temp.+elevated $CO_2$ conc.', 'elevated temp.+ ambient $CO_2$ conc.', and 'elevated temp. +elevated $CO_2$ conc.'. The 'elevated temp,' plot was maintained at 5 higher than 'ambient temp. (outside temperature)'and the 'elevated $CO_2$ cone.' plot was done in 650 ppm $CO_2$. The growth of spring-sown Chinese cabbage was worse than autumn-sown one, and was affected more by high temperature than high $CO_2$. concentration. The $CO_2$ biomass of Chinese cabbage was lower as 25.1-39.1 g/plant in spring-sown one than 54.8-63.4 g/plant of autumn-sown one. Daily $CO_2$2 fixation ability was not significantly different between spring- and autumn-sown Chinese cabbage as 1.9-2.9, 2.7-3.1 kg/10a/day, respectively. The $CO_2$ biomass of radish were 87.4-104.6 /plant in spring-sown one and 51.3$\sim$76.4 g/plant in autumn-sown one. Daily $CO_2$ fixation ability of radish were 6.2-10.1 kg/10a/day in spring-sown one and 4.6-6.9 kg/10a/day in autumn-sown one.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.8
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• pp.1159-1163
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• 2006

This experiment was performed to examine the influences of high ambient temperature on milk production, nutrient digestibility, energy and protein sufficiency ratio, and plasma metabolites concentration in lactating cows. In a $2{\times}2$ crossover design, four multiparous lactating Holstein cows were maintained in a chamber under treatment of constant moderate ($18^{\circ}C$) ambient temperature (MT) or high ($28^{\circ}C$) ambient temperatures (HT). The DMI and milk protein yield were significantly lower in HT (p<0.05). The milk yield, milk lactose yield, and milk SNF yield tended to be lower in HT (p<0.10). No statistical differences for 4% fat-corrected milk and milk fat yield were observed. Rectal temperatures were significantly higher in HT than MT (p<0.05). The apparent DM, OM, ether extract, CF, and ash digestibility did not differ between treatments. On the other hand, the apparent CP digestibility was increased significantly (p<0.05) and nitrogen free extract tended to increase (p<0.10) in HT. The sufficiency ratio of ME and DCP intake for each requirement tended to be lower in HT than in MT (p<0.10). Concentrations of total protein (TP), albumin, and urea nitrogen in plasma did not differ between treatments. Plasma 3-methylhistidine (3MH) concentration as a marker of myofibrillar protein degradation tended to be higher in HT (p<0.15). In conclusion, high ambient temperature was associated with a lower energy and protein sufficiency ratio, and decreased milk protein production, even though the body protein mobilization tended to be higher.

• Structural Engineering and Mechanics
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• v.89 no.4
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• pp.335-347
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• 2024

This study pioneers the exploration of creep and shrinkage behavior in ambient-cured geopolymer concrete (GPC), a vital yet under-researched area in concrete technology. Focusing on the influence of sodium hydroxide (NaOH) solution concentration, the research utilizes low calcium fly ash (Class-F) and alkaline solutions to prepare two sets of GPC. The results show distinct patterns in compressive strength development and dry shrinkage reduction, with a 14 M NaOH solution demonstrating a 26.5% lower dry shrinkage than the 16 M solution. The creep behavior indicated a high initial strain within the first 7 days, significantly influenced by curing conditions and NaOH concentration. This study contributes to the existing knowledge by providing a deeper understanding of the time-dependent properties of GPC, which is crucial for optimizing its performance in structural applications.

• Journal of Environmental Health Sciences
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• v.24 no.2
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• pp.110-117
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• 1998

This study was carried out to investigate the concentrations of TSP, Pb, Zn and Fe in ambient air adjacent to the heavy traffic road side in Seoul from October 1 to October 31, 1997. The results were as follows 1. The concentrations of TSP were 260 $\mu g/m^3$, 184 $\mu g/m^3$, 147 $\mu g/m^3$ in Chongro, Chungkechun and Kangnam-terminal, respectively. The concentration of TSP was correlated with the traffic volume of the sampling sites (r=0.77). 2. The concentrations of Pb were 638 ng/m$^3$, 335 ng/m$^3$, 233 ng/m$^3$ in Chungkechun, Kangnam-terminal and Chongro, respectively. The concentration of Pb was correlated with the Truck (over 1.4 ton) volume of the sampling sites (r=0.71). The Pb contents among these sites were significantly different (p < 0.05). 3. The concentrations of Zn were 535 ng/m$^3$, 461 ng/m$^3$, 439 ng/m$^3$ in Chongro, Kangnam-terminal and Chungkechun, respectively. The concentration of Zn was badly correlated with the traffic volume of the sampling sites (r=0.23). 4. The concentrations of Fe were 5.32 $\mu g/m^3$, 4.51 $\mu g/m^3$ and 3.18 $\mu g/m^3$ in Chongro, Kangnam-terminal and Chungkechun, respectively. The concentration of Fe was correlated with the traffic volume of the sampling sites (r=0.83). The Fe contents among these sites were significantly different (p < 0.05). 5. The concentrations of TSP, Pb, Zn, Fe investigated didn't exceed the Korean Ambient Air Quality Standards, but more researches in relation to these will be required in considering people working in these sites suffered from cough, asthma and chronic headache.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.49-52
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• 2003

Two types of ozone monitors using UV absorption method were tried in consideration of cost of the monitor and precision in measuring. The high concentration ozone monitor for high concentration real time ozone monitoring from ozone generator was composed of a low pressure mercury lamp as UV source, a photo multiplier tube as UV detector and signal processing unit for the most part. This structure could be very useful for low price high concentration ozone monitor due to simple system structure and fairly good monitoring characteristics. The developed system showed good linear output characteristics to ozone in the measuring concentration range of 0.05 and 2 wt.%. For accuracy ambient ozone monitoring in ambient in ppm level, the system composed of a high power pulsed xenon lamp as UV source, an optical spectrometer with a high sensitivity linear CCD array as UV detector and signal processing unit in brief speaking was proposed our study for the first time in the world. The developed system showed good linearity and sensitivity in relative low measuring range between 10ppm and 10,000ppm, and showed some feasibility of high resolution ozone monitor using CCD array as photodetector.

• Journal of Korean Society for Atmospheric Environment
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• v.10 no.3
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• pp.191-196
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• 1994

Concentration of particulate nitrate originated from sea salt in ambient air was determined from February to October 1993. Sampling was carried out using a two-stage Anderson air sampler at the top of a five-story building located at Kon-Kuk University in Seoul. Concentration of NaNO$_3$, which originated from sea salt was highest in spring time and lowest in summer the and the concentration range was between 0.10 and 0.66 $\mu\textrm{g}$/㎥. NaNO$_3$/TSP ratio was very low 0.05~0.39%) indicating that the portion of NaNO$_3$ in TSP was negligible.

• Wind and Structures
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• v.9 no.4
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• pp.315-330
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• 2006

Flow and scalar dispersion around Cheomseongdae are numerically investigated using a three-dimensional computational fluid dynamics (CFD) model with the renormalization group (RNG) $k-{\varepsilon}$ turbulence closure scheme. Cheomseongdae is an ancient astronomical observatory in Gyeongju, Korea, and is chosen as a model obstacle because of its unique shape, that is, a cylinder-shaped architectural structure with its radius varying with height. An interesting feature found is a mid-height saddle point behind Cheomseongdae. Different obstacle shapes and corresponding flow convergences help to explain the presence of the saddle point. The predicted size of recirculation zone formed behind Cheomseongdae increases with increasing ambient wind speed and decreases with increasing ambient turbulence intensity. The relative roles of inertial and eddy forces in producing cavity flow zones around an obstacle are conceptually presented. An increase in inertial force promotes flow separation. Consequently, cavity flow zones around the obstacle expand and flow reattachment occurs farther downwind. An increase in eddy force weakens flow separation by mixing momentum there. This results in the contraction of cavity flow zones and flow reattachment occurs less far downwind. An increase in ambient wind speed lowers predicted scalar concentration. An increase in ambient turbulence intensity lowers predicted maximum scalar concentration and acts to distribute scalars evenly.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.7
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• pp.611-617
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• 2006

We report the preparation of N doped, p-type ZnO films by post-annealing in $NH_3$ ambient. The properties were examined by XRD, Hall-effect measurement, PL, and SIMS. ZnO films showed better crystallinity and electron concentration of $10^{15}-10^{17}/cm^3$ with post-annealing in $NH_3$ ambient. These films were converted to p-type ZnO by activation thermal annealing process at $800^{\circ}C$ under $N_2$ ambient. The electrical properties of the p-type ZnO showed a hole concentration of $1.06\times10^{16}/cm^3$, a mobility of $15.8cm^2/V{\cdot}s$, and a resistivity of $40.18\Omega{\cdot}cm$. The N doped ZnO films showed a strong photoluminescence peak at 3.306 eV at 13 K, which is closely related to neutral acceptor bound excitons of the p-type ZnO:N. In the SIMS spectra, the incorporation of nitrogen was confirmed.

• Journal of ILASS-Korea
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• v.19 no.4
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• pp.188-196
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• 2014

The spray and combustion characteristics of n-dodecane fuel were investigated in a CVCC (constant volume combustion chamber). The selection of ambient conditions for the spray followed ECN (engine combustion network) guidelines, which simulates the ambient condition of diesel engines at start of fuel injection. ECN is a collaboration network whose main objective is to establish an internet library of well-documented experiments that are appropriate for model validation and the advancement of scientific understanding of combustion at conditions specific to engines. Therefore repeatability of the experiments with high accuracy was important. The ambient temperature was varied from 750 to 930 K while the density was fixed at around $23kg/m^3$. The injection pressure of the fuel was varied from 500 to 1500 bar. The spray was injected in both non-reacting ($O_2$ concentration of 0%) and reacting conditions ($O_2$ concentration of 15%) to examine the spray and the combustion characteristics. Direct imaging with Mie Scattering was used to obtain the liquid penetration length. Shadowgraph was implemented to observe vapor length and lift-off length at non-reacting and reacting conditions, respectively. Pressure data was analyzed to determine the ignition delay with respect to the spray and ambient conditions.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11a
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• pp.55-58
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• 2003

The ambient concentrations of benzene, toluene, and $\alpha$-/$\beta$-pinene were measured from July, 2002 to August, 2002 at the Gumsung mountain site in Jeonnam province. The mean concentration of benzene for this study was $62.6{\pm}43.9$ pptv (Min. 20.4 ~ Max. 151.2 pptv) , and that of toluene was 619.8 ${\pm}$ 330.2pptv (264.8~1, 386pptv). It was observed that the concentrations of $\alpha$ -pinene and $\beta$ -pinene were $169.0{\pm}97.7$ pptv (72.9~396.1pptv) and $11.2{\pm}27.9$pptv (7.5 ~95.9 pptv) , respectively. The ambient concentrations of aromatic and natural VOCs were found at the pptv level. In this study, the toluenelbenzene ratios were $13.9{\pm}11.2$ , but they were a little higher than those found in the domestic study and approximately 5 times greater than the values in the foreign study. The $\beta$ -/ $\alpha$ -pinene ratios ranged between 0.05 and 0.55, and this range was found to be similar in the foreign study.