• Journal of environmental and Sanitary engineering
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• v.7 no.1
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• pp.1-16
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• 1992

Corrosion of pipes Is one of the most serious problems in the maintenance of water worlds. Corrosion is promoted not only by physical factors such as temperature, but also by electrochemical factors including concentration of soluble metal ions, chlorine ion, pH, DO and microorganisms. Corrosion products also affect corrosion rate. In this research, study results are summarized as follows ; 1) Corrosion test was performed for 4 weeks at $70^{\circ}C$, pH 7.0 with specimens of 4 types of metal materials used as service pipes. Corrosion rate and S.E.M were analyzed. The results were showed that corrosion 1.ate of carbon steel pipe was 4.10~5.22 $mg/\textrm{cm}^2$ . week, galvanized steel pipe 0.98~1.34$mg/\textrm{cm}^2$. week, Copper pipe 0.02~0.04$mg/\textrm{cm}^2$. week, stainless steel pipe 0.05~ 0.10$mg/\textrm{cm}^2$ . week. 2) When corrosion rate was tested for tile types of pipes at pH 7 and both $25^{\circ}C$ and $75^{\circ}C$, avaerage corrosion rate for 6 weeks at $25^{\circ}C$ Ivas 2.26$mg/\textrm{cm}^2$ . week in carbon steel pipe, 1.99$mg/\textrm{cm}^2$. week in galvanized steel pipe, 0.26 $mg/\textrm{cm}^2$. week in stainless steel pipe. At $87^{\circ}C$, average corrosion rate for 4 weeks u.3s 4.56 $mg/\textrm{cm}^2$. week in carbon steel pipe,

• Journal of the Korean Society of Combustion
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• v.5 no.1
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• pp.7-18
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• 2000

Numerical simulations of counterflow non-premixed $CH_4/C_2HCl_3/Air$ flames added 8%(by volume) C2HCl3 on the fuel side are conducted at atmospheric pressure using a detailed chemical reaction mechanism in order to understand the effect of strain rates. A detailed sensitivity analysis is also performed in order to assess the relative influence of each reaction on the flame established at a strain rate of 200s-1. The structure of flames (i.e., temperature, velocity, and concentration of species) established at both a strain rate of 150s-1 and 300s-1 are investigated. As the strain rate increases, the "flame zone" is restricted to a narrower range and the position of maximum temperature is shifted to the fuel side. The concentrations of major species, H2O, CO, H2, HCl, Cl2, and Cl are decreased with increased strain rate. The reaction involving chlorine, CH4 + Cl $\rightarrow$ CH3 + HCl, instead of the reaction, CH4 + H $\rightarrow$ CH3 + H2 influences the consumption of methane. C2HCl3 + OH $\rightarrow$ CHCl2 + CHOCl and HCl + OH $\rightarrow$ H2O + Cl, are major reactions, through which OH radicals are consumed.

• Korean Journal of Food Science and Technology
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• v.24 no.4
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• pp.301-305
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• 1992

Effect of heating medium and evaporation temperatures on a concentration ratio, a evaporation rate and a overall heat transfer coefficient during concentration of garlic juice by a centrifugal thin film evaporator were investigated. At constant feeding rate and evaporation temperature, the concentration ratio, the evaporation rate and the overall heat transfer coefficient increased with the increase of the steam temperature but those values increased slowly or decreased as a steam temperature exceeded $110^{\circ}C$. At the feeding rate of 50 kg/h and the steam temperature of $100^{\circ}C$ and below, those values decreased with the increase of evaporation temperature. But if a steam temperature became $100^{\circ}C$ and up, those values increased slowly and then decreased with the increase of the evaporation temperature until the evaporation temperature reached a critical value. At constant feeding rate, those values increased until the temperature difference between steam and evaporation temperatures became $70^{\circ}C$. But if they become larger than $70^{\circ}C$, those values increased slowly and then decreased.

• Journal of Power System Engineering
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• v.3 no.2
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• pp.51-56
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• 1999

Fatigue crack propagation rates and characteristics of the SA516-70 steel which is used for the low temperature pressure vessels, were studied in the room temperature of $10^{\circ}C$ and low temperature ranges of $-10^{\circ}C,\;-30^{\circ}C,\;-50^{\circ}C,\;and\;-70^{\circ}C$ with stress ratio of R=0.05. The obtained experimental results are as follows; 1) In the logarithmic relationship between the fatigue crack propagation rate(da/dN) and stress intensity factor K, the linear relationship was obtained up to da/dN > $8{\times}10^3$ mm/cycle in the same of room temperature, but in low temperature case, the relationship was extended to the range of low crack propagation rate. 2) The lower limit stress intensity factor of SA516-70 ${\Delta}K_{th}\;was\;23MPa\sqrt{m}$ and in the case of low temperature $-50^{\circ}C\;and\;-70^{\circ}C$, the crack propagation rate da/dN which showed a linear relation, reached rapidly to the ${\Delta}K_{th}$. As the results, the crack propagation rates of $-50^{\circ}C\;and\;-70^{\circ}C$ were lower than that of room temperature and according to the testing temperature the rates were decreased rapidly to the ${\Delta}K_{th}$. 3) On the relationship between the stress intensity factor ${\Delta}K$ and the track propagation cycle, the stress intensity factors of low cycle region was rapidly increased at low temperature, but ${\Delta}K$ was increased rapidly at room temperature of high cycle. 4) On the relationship between the fatigue crack propagation rate and cycle, the fatigue crack propagation rate showed higher gradient in the room temperature than the low temperature due to the increment in ductility at low temperature.

• The Journal of Fisheries Business Administration
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• v.42 no.3
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• pp.79-93
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• 2011

Water temperature of Oliver flounder farm affects Oliver flounder growth and mortality rate. In laboratory experimental tanks, optimal water temperature was $22.5^{\circ}C$($21{\sim}24^{\circ}C$) and cultivatable water temperature was $12{\sim}28^{\circ}C$. The purpose of this study is to identify applicable and useful water temperature of Oliver flounder farm in case of actual farming. The data applied in the analysis was collected from Jeju island. In the study, various analytical methods including productivity analysis, regression analysis, statistical analysis were conducted for 13 Oliver flounder culture farms. The result of analysis can be summarized as follows : First, growth rate on the Oliver flounder culture farms was related to mean of water temperature, variation of water temperature and low water temperature. Second, survival rate on the Oliver flounder culture farms was related to mean of water temperature. In case of including Oliver flounder stocking density, defined as the surface area of Oliver flounder per $m^2$ of water surface area, survival rate strongly related to mean of water temperature, variation of water temperature, cultivating capability and stocking density. Third, production weight per $m^2$ of water surface area was strongly related to mean of water temperature, low water temperature and cultivating capability. Growth rate and survival rate was analyzed into mediate variable character.

• Korean Journal of Plant Resources
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• v.11 no.2
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• pp.124-130
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• 1998

It failed occasionally to take a reasonable emergence rate since tobacco (Nicotiana tabacum L.) seeds were planted on late Jan. showing lowest temperature. This experiment was done to measure the effect of GA3 (concentration ; period) , light quality (red ; white ; dark) during or after its treatment, daily irradiation hours( 0 ; 8 ; 12 ;16) and germination termperature (20 or 10 $^{\circ}C$ ocnstant ; 20/1$0^{\circ}C$ alternating) on the germination rate. Red and white light given during grmination showed no differences between the other daily irradiation hours except that 8 hours red light delayed germination although their 12 hours irradiation had the gratest rate. The rate was increased with increased concentration to GA3 0.01 mM or increased imbibition period to 3 days although the rate of cv. NC 82 was less than that of cv. Burley 21 in the case of dark imbibition of GA3 but daily 12 hours irradiation during germination. Light quality forced during GA3 imbibition eliminated such effect of GA3 shown in the darkness so that only light quality pretreatment and termperature during germinition were affected on the rate. The germination rate of thecultivars was decreased in the order of red, white light, darkness meaning that it was highly influenced by the light quality during GA3 treatment. Regardless of GA3 or light quality treatment,on the other hand, the rate was greater in 20 $^{\circ}C$ constat than 1$0^{\circ}C$ constant and 20/1$0^{\circ}C$ alternating germination temperature having similar germinative patterns.

• Journal of Ecology and Environment
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• v.31 no.4
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• pp.261-267
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• 2008

Growth and photosynthetic responses of one $C_3$ and two $C_4$ plants in the family Chenopodiaceae in three $CO_2$ concentration $([CO_2])$ conditions-low (about $243{\mu}mol\;mol^{-1}$, LC), present (about 378, PC), and high (about 465, HC)-were investigated in open top chambers. The relative growth rate (RGR) and net assimilation rate in the $C_3$ plant, Chenopodium album, increased with increasing $[CO_2]$, though the RGR was not enhanced significantly in the HC condition. The leaf area ratio and leaf weight ratio of the $C_3$ plant drastically decreased with increasing $[CO_2]$, suggesting that the $C_3$ plant invests more biomass to leaves in lower $[CO_2]$ conditions. The two $C_4$ plants, Atriplex glauca and A. lentiformis, showed relatively small changes in those growth parameters. These photosynthetic-pathway-dependent responses suggest that growth patterns of $C_3$ and $C_4$ plants have been altered by past increases in atmospheric $[CO_2]$ but that there will be relatively little further alteration in the future high-$CO_2$ world.

• Journal of the Korean Ceramic Society
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• v.35 no.7
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• pp.721-725
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• 1998

In this study solid-phase sintered silicon caribide samples composed of SiC powder having boron and car-bon black as additives were prepared by pressureless sintering at $1950^{\circ}C$. The bending strength the frac-ture toughness and the specific werar rate of the samples were examined and the micro structures of the broken and the worn surface were observed by SEM to understand the relationship between the tri-bological charcteristics and the micro structure. Additionally the relationship between the micro struc-tures and the tribological characteristics of the samples for the frictional opponents SiC and $Al_{2}O_{3}$ pins were investigated Conclusions are as follows ; 1. The specific were rate of the samples for the SiC pin was larger than that for the $Al_{2}O_{3}$ pin. HOwever the specific wear rate for the $Al_{2}O_{3}$ pin was increased about 6,45 times as that for the SiC pin under the load increasing. 2. The specific wear rate of the SiC pin was larger than that of the $Al_{2}O_{3}$ pin. owever the specific wear rate of the $Al_{2}O_{3}$ pin was increased about 4 times as that of the SiC pin under the load increasing 3. The micro stucture of the worn surface showed a flat face without cracks in the case that the frictional opponents has the low friction coefficient but in the case of without cracks in the case that the frictional opponents has the low friction coefficient but in the case of the high friction coefficient the micro structure of the worn surface showed an uneven face having spread-ed cracks. 4. The tribological characteristics of thesolid-phase sintered SiC samples was similar to that of li-quid-phase sintered ones when the pin having the high friction coefficient was used.

• Journal of the korean academy of Pediatric Dentistry
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• v.8 no.1
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• pp.89-102
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• 1981

1147 preschool children aged from 3 to 6 living in some farm villages in Kyungki-do were surveyed on dmf and distribution of dental caries in primary dentition. The results were as follows: 1. dmf rate ... 92.76 % boy ... 94.52 % girl ... 90.5.5 % 2. dmf t rate ... 37.07 % dmf t index ... 7.09 3. dmf s rate ... 13.74 % dmf s index ... 13.14 % 4. df t index ... 6.94 5. Each percentage of d, m & f per dmf teeth d rate ... 89.96 % m rate ... 7.24 % f rate ... 2.67 % 6. Most frequent site of dental caries in each tooth $\underline{A}$ mesial $\overline{A}$ distal $\underline{B}$ mesial $\overline{B}$ distal $\underline{C}$ distal $\overline{C}$ distal $\underline{D}$ disto-occlusal $\overline{D}$ disto-occlusal $\underline{E}$ linguo-occlusal $\overline{E}$ occlusal 7. Order of caries susceptibility $\overline{E}$ $\underline{E}$ $\overline{D}$ $\underline{D}$ $\underline{A}$ $\underline{B}$ $\overline{C}$ $\underline{C}$ $\overline{B}$ $\overline{A}$ 8. All the values in caries criteria showed a marked increae from those of 1968.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.2
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• pp.108-111
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• 2000

Osmoconditioning and hardening effects for the seed germination of normal and naturally aged rice seeds were studied through analyzing the total sugars and $\alpha$-amylase activity. The normal seeds which used to have high germination rate accelerated germination with the osmoconditioning at the suboptimal temperature of 17$^{\circ}C$. On the other hand, the aged seeds did not affect germination rate at $25^{\circ}C$, while increased germination rate and accelerated germination a little at 17$^{\circ}C$, Hardening of aged seeds increased germination rate by 10-15% compared with control seeds at both 17 and $25^{\circ}C$ and accelerated germination. Total sugar content and $\alpha$-amylase activity of normal seeds were higher than did aged seeds. The aged seeds with treatment of osmoconditioning and hardening increased total sugar content and $\alpha$--amylase activity, but hardening was more effective than osmoconditioning. The $\alpha$--amylase activity was positively correlated with the total sugar content and germination rate.