• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.1
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• pp.75-94
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• 2019

As the present single-layer repository concept requires too large an area for the site of the repository, a multi-layer repository concept has been suggested to improve the disposal density. The effects of the excavation damaged zone around the multi-layer repository constructed in the deep host rock on the temperature distribution in the repository were analyzed. For the thermal analysis of the multi-layer repository, the hydrothermal model was used to consider the resaturation process occurring in the buffer, backfill and rock. The existence of an excavation damaged zone has a significant effect on the temperature distribution in the repository, and the maximum peak temperatures of double-layer and triple-layer repositories can rise to $7^{\circ}C$ and $12^{\circ}C$, respectively depending on the size of the excavation damaged zone and the degree of decrease of the thermal conductivity. The dominant factor affecting the peak temperature in the multi-layer repository is the decrease of thermal conductivity in the excavation damaged zone, and the excavation damaged zone formed around the deposition hole has more significant effects on the peak temperature than does the excavation damaged zone formed around the disposal tunnel.

• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.790-803
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• 2019

The dioctyl terephthalic acid (DOTP) process produces plastic plasticizers by esterification of terephthalic acid with powder in the form of octanol. In this study, the dust explosion characteristics of terephthalic acid directly injected into the manhole in the form of powder in the presence of flammable solvent or vapor in the reactor of this process were investigated. Dust particle size and particle size distribution dust characteristics were investigated, and pyrolysis characteristics of dust were investigated to estimate fire and explosion characteristics and ignition temperature. Also, the minimum ignition energy experiment was performed to evaluate the explosion sensitivity. As a result, the average particle size of terephthalic acid powder was $143.433{\mu}m$. From the thermal analysis carried out under these particle size and particle size distribution conditions, the ignition temperature of the dust was about $253^{\circ}C$. The lower explosive limit (LEL) of the terephthalic acid was determined to be $50g/m^3$. The minimum ignition energy (MIE) for explosion sensitivity is (10 < MIE < 300) mJ, and the estimated minimum ignition energy (Es) based on the ignition probability is 210 mJ. The maximum explosion pressure ($P_{max}$) and the maximum explosion pressure rise rate $({\frac{dP}{dt}})_{max}$ of terephthalic acid dust were 7.1 bar and 511 bar/s, respectively. The dust explosion index (Kst) was 139 mbar/s, corresponding to the dust explosion grade St 1.

• 한국해양학회지
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• v.9 no.2
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• pp.52-58
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• 1974

The water temperature distribution and the water movement closely related with it, in the east side of Korea, was condidered. Special emphasis was paid on the low temperature phenomenon near Ulgi. It was known from the temperature distribution in the east side of Korea that the Tsushima current continues to flow northward at the surface near Sokcho. Also the influence of the cold water extends from the North to the South with increasing depth. The formation of the cold core near Ulgi was explained as due mainly to the existence of the boundary layer near the surface, and partly to the effect of the wind. This inclination of the boundary layer has the value of about 3.0m/Km, and the lower cold current velocity computed using this value lies in the range of those observed by Nishida(1926, 1927). The upwelling velocity was computed approximately as 1.4 10$\^$-3/ cm/sec, and the maximum distance to which the boundarylayer can rise or fall from it's equilibrium position was considered as below 10m.

• Journal of Life Science
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• v.34 no.4
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• pp.264-270
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• 2024

This study is conducted to analyze environmental factors that affect the ecology of boreal digging frog and use them as basic data for selecting (or creating) suitability of alternative habitats for survival and monitoring method from 2020 to 2022 after boreal digging frog were relocated to the alternative habitats in 2019. Analyzing the environment of the alternative habitats showed that the criteria suited the followings: distance from wetlands, grasslands and rivers was within 5 m, the low-rise grassland was 6,000 m², soft soil was at a depth of ≥20 cm, and the area of permanent wetlands was 5,000 m² wide. As a result of the correlation analysis between meteorological factors and population (n) and breeding, there was a significant correlation between rainfalls and breeding (p<0.01). During the monitoring, it was confirmed that the SVL (Snout-Vent Length) and BM (Body Mass) of the translocated population were maintained (p>0.05), and it was found that the proximity of the habitat and spawning pond, securing food space (grasslands), soil quality, and wetlands could function as an alternative habitat if conditions were met. As a result of analyzing the meteorological factors affecting the population of boreal digging frog, the SVL had a statistical impact on the minimum temperature, maximum temperature, relative humidity, and the rainfall (p<0.05). In the case of breeding, rainfall was found to be affected (p<0.01), and the population was statistically affected by the average temperature, minimum temperature, and relative humidity (p<0.05).

• Korean Journal of Soil Science and Fertilizer
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• v.18 no.1
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• pp.27-31
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• 1985

To get well matured farm yard manure from ricestraw as quickly as possible during winter season, straw piles wrapped with polyethylene film and/or straw thatch were stored in the vinyl house or open air. Their maturities and changes of temperature in heap were investigated from the beginning of December 1983 to March of next year. Heat increment in vinyl house was high $2-5^{\circ}C$ than at open air at the lowest temperature but it didn't rise over the freezing point. However, the highest temperature was arisen over than $20^{\circ}C$ averagely at the vinylhouse compared to those of open air during three months. Temperature in piles of straw manure was reached to about $70^{\circ}C$ in maximum and rose again very rapidly after repiling in the vinyl house, whereas increment of temperature after repiling was delayed and took long times to reach the maximum temperature at open air. Wrapping with P.E. film also affected the insulation of decomposing heat of straw pile and promoted the repeat of piling even at open air. By these results, ricestraw would be decomposed rapidly by insulation with P.E. film in the vinyl house and could be reached to matured compost for application to field on next spring season. P.E. film covered for vinyl house was endured until May of next year without tear by weathering.

• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.356-361
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• 2020

Propylene is widely used in petrochemical manufacturing at over 200 ℃. However, since propylene is a flammable gas with fire and explosion risks, inert nitrogen is injected to prevent them. In this study, experiments were conducted using propylene-nitrogen-oxygen upon pressure changes at 200 ℃. At 21% oxygen, as pressure increased from 0.10 MPa to 0.25 MPa, lower explosion limit (LEL) decreased from 2.2% to 1.9% while upper explosion limit (UEL) increased from 14.8% to 17.6%. In addition, minimum oxygen concentration (MOC) decreased from 10.3% to 10.0%, indicating higher risks with the expanded explosive range as pressure increased. With increase of pressure from 0.10 MPa to 0.25 MPa, explosion pressure increased from 1.84 MPa to 6.04 MPa, and the rate of rise of maximum explosion pressure increased drastically from 90 MPa/s to 298 MPa/s. It is hoped that these results can be used as basic data to prevent accidents in factories using propylene.

• Journal of the Korean Society of Food Science and Nutrition
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• v.15 no.2
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• pp.119-127
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• 1986

The rheological properties of mayonnaise were studied with cylindrindrical viscometer. It was observed that mayonnaise showed pseudoplastic behavior, yield stress and time dependent characteristics. In the initial period of shear time, the decay of viscosity of mayonnaise was followed by a second-order kinetic equation. The influence of temperature on viscosity could be described by Arrhenius equation. The apparent viscosity of mayonnaise markedly increased with an rise in the concentration of egg yolk; and the emulsion was most stable at the concentration of 12%. At the concentration of $65{\sim}75%$ oil, the apparent viscosity was increased; the maximum value was reached at 75% oil, and above 75% oil, the remarkable decreased was observed. The size of oil drops was decreased with an increase in oil concentration of 75% oil. The apparent viscosity of mayonnaise was increased with an rise in water contents, while being decreased with one in the concentration of vinegar.

• Korean Journal of Microbiology
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• v.21 no.2
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• pp.51-60
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• 1983

Cultural characteristics of Strptomyces griseolus isolated from the soil were investigated. This strain was disclosed to utilize D-xylose, and D-glactose in preference order as a carbon source with the formation of glucose isomerase. The addition of sweet potato starch also proved effective promoting the total enzyme activity measured at 29% higher than the control. Corn cob, one of waste agricultural resources, was hydrolyzed in 2~3% $H_2SO_4$ solution at $100^{\circ}C$, 3~5 hours to produce a xylose syrup which gave rise to the recovery of 19.9% in a batch system and 28.2% in a repeated system. By the addition of both 2% of xylose syrup(Be'28) prepared by and us 65% of corn steep liquor (total nitrogen 1.2%), enzyme induction was maximized. The enzyme activity was stimulated by the xylose and the cell growth by the C.S.L. Also, remarkable increase of enzyme activity was noticed by the addition of protein acid hydrolysate 86.2% higher than the control. $QO_2$ of the biomass cultured in 30L capacity jarfermentor recorded low oxygen requirement of 251.2 1/hr. Maximum activity of glucose isomerase was observed noted at the 9th hour after inoculation which is 2 hours faster than the stationery was observed noted at the 9th hour after inoculation which is 2 hours faster than the stationery phase of the biomass growth. Glucose isomerase from the strain was activated by adding the $Co^{++}\;and\;Mg^{++}$ with optimum temperature of $73^{\circ}C$ and pH of 7.2. Conversion ratio of 60% glucose to frutose was 42.5% after 70 hours reaction.

• Journal of Environmental Science International
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• v.27 no.10
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• pp.883-899
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• 2018

In this study, water quality data of eight main sites in the Geumho River watershed were collected and analyzed for long-term changes in water quality over the period from 2005 to 2015. The results showed that BOD concentration was gradually improved by the Total Maximum Daily Load (TMDL), stages 1 and 2. Recently, a tendency of increasing BOD concentration was observed in the downstream section of the river. The concentration of COD was analyzed to be contaminated throughout the water system regardless of the water quality improvement project, and the TN concentration tended to increase in the midstream of the river from 2013. The TP concentration has clearly decreased from 2012 after the second stage of TMDL. For the statistical analysis of PCA ordination, monthly water qualities (pH, DO, Electrical Conductivity (EC), Water Temperature (WT), BOD, COD, TN, TP, TOC, and SS) and flow rate data for 5 years from 2012 to 2016 were used. Seasonally the Geumho River showed an increase in the TN concentration at point sources during the dry season (December to February). TP showed the effect of non-point sources in the summer, because rainfall has caused a rise in flow rate in the upstream. Besides, the origin of pollution source was changed from non-point sources with BOD, COD, and TOC.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.6
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• pp.572-581
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• 2001

A heat pipe heat sink device which is to evacuate maximum heat of about 1800W from a powersemiconductor was designed and manufactured One set of cooling device os composed of an Aluminum block (130${\times}$160${\times}$35mm) 4 PFC heat pipes $(d_0 22.23mm)$ and 126 Aluminium fins (250${\times}$58${\times}$0.8mm) Experimental data obtained at a power of 1~2kW revealed that the total thermal resistance of the device varied 0.02~0.018$^{\circ}C$/W along with increasing air velocity from 2m/s to 3 m/s. The result represented a good satisfaction of requirement condition to maintain temperature rise of semiconductor lowe that $40^{\circ}C$ at 1800W and air velocity of 3 m/s Some important resistance such as convective resistances at both fins and heat pipes showed good agreement between mathematical predictions and measurement data.