• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.196-202
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• 2011

In this paper, a series of alkyl succinic acid esters for base oil were synthesized by condensation reaction of succinic anhydride and fatty alcohol. The structures of the synthesized esters were confirmed by $^1H-NMR$, FT-IR spectrum and GC analysis. Basic properties of esters such as kinematic viscosity (KV), refractive index (RI), total acid number (TAN) and pour points were measured and lubricating properties such as SRV wear scar diameter (SRV WSD), fraction coefficient (COF) and 4-ball wear (4-ball WSD) were also evaluated. As the results of basic properties, KV, RI and pour point of synthetic esters increased as the carbon chain of the esters increased. Measurement value of total acid number (TAN) was indicated between 0.2~4 mgKOH/g, and that metal working fluids and pressure working oils are acceptable to use as base oil. Also, lubricating properties of the esters showed as follows: 0.391~0.689 mm of SRV WSD, 0.110~0.138 of SRV COF and 0.49~0.55 mm of 4-ball WSD depended on the structure of the esters. In a comparison on the lubrication capacity of the SRV test based on polyester TMPTO, SRV WSD result showed that a better performance caused by the alkyl group. On the other hand, SRV COF test was not influenced of the alkyl group which the capacity of the lubricant was sightly diminished than the comparison material, regardless of the alkyl group.

• Journal of Radiation Protection and Research
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• v.41 no.1
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• pp.49-55
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• 2016

Background: For the purpose of baseline data collection and enhancement of environmental monitoring the distribution studies of $^{137}Cs$ and $^{90}Sr$ in the soil of Uljin province was performed and the relation between surface soil activities and soil properties (pH, TOC and median of the surface soil) was analyzed. Materials and Methods: For 14 spots within 10 km from the NPP surface soil samples were collected and soils for depth profile were sampled for 3 spots in April 2011. Using ${\gamma}$-ray spectrometry with HPGe detector, the concentrations of $^{137}Cs$ were determined and the concentrations of $^{90}Sr$ were measured by counting ${\beta}$-activity of $^{90}Y$ (in equilibrium with $^{90}Sr$) in a gas flow proportional counter. Results and Discussion: The concentration ranges of $^{137}Cs$ and $^{90}Sr$ were $<0.479-39.6Bq{\cdot}(kg-dry)^{-1}$ (avg. $7.51Bq{\cdot}(kg-dry)^{-1}$) and $0.209-1.85Bq{\cdot}(kg-dry)^{-1}$ (avg. $0.74Bq{\cdot}(kg-dry)^{-1}$) which were similar to the reported values from other regions in Korea. The activity ratio of $^{137}Cs$ to $^{90}Sr$ in surface soils was around 9.67, which is much bigger than the initial value of 1.75 for worldwide fallouts because of faster downward movement of $^{90}Sr$ after fallout than that of $^{137}Cs$. For depth profile studies soils were collected down to 40 cm depth for the locations of Deokgu, Hujeong and Maehwa. The $^{137}Cs$ concentration distribution of the first two showed maximum values at top soils and decreased rapidly in exponential manner, while $^{90}Sr$ showed two local maximum values for soils near top and about 30 cm depth. Through linear fittings between the $^{137}Cs$ and $^{90}Sr$ concentrations of surface soil and pH, TOC and median of the surface soil, the only probable relationship obtained was between $^{137}Cs$ and TOC (determination coefficient $R^2=0.6$). Conclusion: The concentration ranges of $^{137}Cs$ and $^{90}Sr$ in Uljin were similar to the reported values from other regions in Korea. The only probable relationship obtained between activities and soil properties was between $^{137}Cs$ and TOC.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.2
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• pp.71-78
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• 2000

Preferential flow has recently been the subject of increasing interest because these phenomena contribute to solute transport in soils. Commonly, preferential flow paths are associated with macropores or highly structured soils. We presented an analysis of the measured breakthrough curves (BTCs) of $Cl^-$ and $Cu^{2+}$ ions to test the occurrence of preferential flow in soils using miscible displacement technique under steady flow conditions. We also analyzed soil water retention curves and from this curves induced cumulative pore size distribution of undisturbed soils, which sampled from Ap1, B1, and C horizons of Songjeong series soils (the fine loamy, mesic family of Typic Hapludults). In this study, miscible displacement experiment on C horizon was excluded, because it is structureless sandy loam with saturated hydraulic conductivity of $5.2cmhr^{-1}$. The saturated hydraulic conductivity of Ap1 horizon was $2.0cmhr^{-1}$, which was about 7 times higher than that of B1 horizon ($0.27cm hr^{-1}$). Cumulative pore size distribution predicted that Ap1 horizon had more macropores (pore diameter larger than $49{\mu}m$, equivalent to -6 kpa of soil matric potential) than B1 horizon. The hydrodynamic dispersion coefficient from chloride BTCs was estimated as $1.3cm^2hr^{-1}$ for B1 and $34cm^2hr^{-1}$ for Ap1 horizon. However the retardation factors of B1 and Ap1 horizon were significantly different, i.e. 1 and 0.6, respectively, which means that there was distinct partition between mobile water and immobile phase in Ap1 horizon. The copper retardation effect of Ap1 horizon was less than that of B1 horizon, even though cation exchange capacity of Ap1 horizon was higher than that of B1 horizon. Thus, breakthrough curves of $Cl^-$ and $Cu^{2+}$ obviously showed the probability that preferential flow would occur in Ap1 horizon.

• Korean Journal of Plant Resources
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• v.35 no.5
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• pp.641-651
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• 2022

The biodiversity research of barley, a functional food, is proceeding to conserve germplasms and develop new cultivar of barley to improve its functional effects. In this study, with 25,104 barley germplasms in the National Agrobiodiversity Center, South Korea, the biodiversity index of species was much lower (1.17) than the origins (24.73) because of the presence of a biased species, Hordeum vulgare subsp. vulgare, but the species and origin of germplasms were significantly different with regard to genetic traits. In the clustering analysis based on genetic traits, we found that 97% barley germplasms could mostly be distributed between 1~7 clusters out of a total of 15 clusters; 'normal and uzu type', 'lodging', and 'loose smut' were commonly represented in the 1~7 clusters and some clusters showed specific differences in five genetic traits including 'growth habit'. In correlation of each genetic trait, the infection of 'barley yellow mosaic virus' was highly correlated to 'number of grains per spike'. '1000 grain weight' was weakly correlated with seven genetic traits including 'number of grains per spike'. Our analysis for barley's biodiversity can provide a useful guide to the species' phenotypes that need to be collected to conserve biodiversity and to breed new barley varieties.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.10 no.1
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• pp.1-18
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• 1974

Some coastal oceanographic investigations in Kwang Yang Bay were carried out bimonthly from April to September (The first half period of the research project) in 1974. The behaviour of the waters, distributions of water temperature and salinity and diffusion characteristic by dye release experiments in the bay are studied for the problems of practical importance in connection with water pollution. Velocities and directions of tidal currents at five fixed stations were observed. And dye diffusion experiment was also carried out on the sea. According to the results from this study, the salinity of the water is lower, ranging from about $28\;\textperthousand\;to\;32\textperthousand$, on all over the surface in the bay with the cause that the fresh water flows in from the Sumjin river. Diffusivities in this sea by means of Rhodamine B diffusion elliperiment were $785.6\;{\times}\;10^2\;\textrm{m}^2/sec$ in major axis, $15.6\;{\times}\;10^2 \;\textrm{m}^2/sec$/sec in minor axis in the direction on patch after 30 minutes from the dye release.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.2
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• pp.188-193
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• 2015

It has been generally recognized that $N_2O$(Nitrous Oxide) emission from marine diesel engines has a close correlation with $SO_2$(Sulfur Dioxide) emission, and diversity of fuel elements using ships affects characteristics of the $N_2O$ emission. According to recent reports, in case of existence of an enough large NO(Nitric Oxide) generated as fuel combustion, effect of the $SO_2$ emission in exhaust gas on the $N_2O$ formation is more vast than effect of the NO. Therefore, $N_2O$ formation due to the $SO_2$ element operates on a important factor in EGR(Exhaust Gas Recirculation) systems for NOx reduction. An aim of this experimental study is to investigate that intake gas of the diesel engine with increasing of $SO_2$ flow rate affects $N_2O$ emission in exhaust gas. A test engine using this experiment was a 4-stroke direct injection diesel engine with maximum output of 12 kW at 2600rpm, and operating condition was set up at a 75% load. A standard $SO_2$ gas with 0.499%($m^3/m^3$) was used for changing of $SO_2$ concentration in intake gas. In conclusion, the diesel fuel included out sulfur elements did mot emit the $SO_2$ emission, and the $SO_2$ emission in exhaust gas according as increment of the $SO_2$ standard gas had almost the same ratio compared with $SO_2$ rate in mixture inlet gas. Furthermore, the $N_2O$ element in exhaust gas was formed as $SO_2$ mixture in intake gas because increment of $SO_2$ flow rate in intake gas increased $N_2O$ emission. Hence, diesel fuels included sulfur compounds were combined into $SO_2$ in combustion, and $N_2O$ in exhaust gas should be generated to react with NO and $SO_2$ which exist in a combustion chamber.

• Journal of the Korean Society of Hazard Mitigation
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• v.2 no.1 s.4
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• pp.135-141
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• 2002

Both non-linear damping values of the deep and shallow crustal materials and seismic source parameters are found from the observed near-field seismic ground motions at the South-eastern Korean Peninsula. The non-linear numerical algorithm applied in this study is Levenberg-Marquadet method. All the 25 sets of horizontal ground motions (east-west and north-south components at each seismic station) from 3 events (micro to macro scale) were used for the analysis of damping values and source parameters. The non-linear damping values of the deep and shallow crustal materials were found to be more similar to those of the region of the Western United States. The seismic source parameters found from this study also showed that the resultant stress drop values are relatively low compared to those of the Western United Sates. Consequently, comparisons of the various seismic parameters from this study and those of the United States Seismo-tectonic data suggest that the seismo-tectonic characteristics of the South eastern Korean Peninsula is more similar to those of the Western U.S.

• Journal of Animal Environmental Science
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• v.9 no.2
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• pp.103-112
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• 2003

In this study, the distributions of internal climates such as air temperature, humidity, dust, ammonia gas, and air velocity were systematically measured at a mechanically ventilated broiler houses during summer season, with local weather data. The analysis was focused on the suitability, stability, and uniformity of internal climate, resulting in serious stress on chickens and decrease of productivity In the mechanically ventilated broiler house, the difference between measured and recommended air temperatures(suitability) was 10.4C in maximum during the summer time. The difference of air temperature in the house between day and night was $8.7^{\circ}C$ in maximum. And maximal hourly range of internal air temperature at 0.4m height from the floor was $3.7^{\circ}C$ suggesting it maintained thermal uniformity in the broiler house. The $NH_3$ and dust concentrations were pretty low because ventilation was fully performed. The air speed at chicken location was measured 2.2m/s and 1.7m/s, respectively without and with chicken existence.

• Journal of Chest Surgery
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• v.38 no.2 s.247
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• pp.123-131
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• 2005

Background: The number of elderly patients undergoing coronary artery bypass grafting (CABG) is increasing. Elderly patients are at increased risk for a variety of perioperative complications and mortality. We identified determinants of operative complications and mortality in elderly patients undergoing CABG. Material and Method: Between January 1995 and July 2003, 91 patients older than 75 years underwent isolated CABG at Asan Medical Center. There were 67 men and 24 women with mean age of $77.0\pm2.4$ years. Thirty clinical or hemodynamic variables hypothesized as predictors of operative mortality were evaluated. Result: CABG was performed under emergency conditions in 5 patients. The internal thoracic artery was used in 85 patients and 10 patients received both internal thoracic arteries. The mean number of distal anastomosis was 3.7 per patient. Operative mortality was $3.3\%$. Twenty-two patients had at least one major postoperative complication. Low cardiac output syndrome was the most common complication, followed by reoperation for bleeding, pulmonary dysfunction, perioperative myocardial infarction, stroke, acute renal failure, ventricular arrhythmia, upper gastrointestinal bleeding, infection, and delayed sternal closure. None were the predictors of mortality. Renal failure, peripheral vascular disease, emergency operation, recent myocardial infarction, congestive heart failure, New York Heart Association (HYHA) class III or IV, Canadian Cardiovascular Society (CCS) angina scale III or IV, and low left ventricle ejection fraction below $40\%$ were univariate predictors of overall complications. Actuarial probability of survival was $94.9\%,\;89.8\%,\;and\;83.5\%$ at postoperative 1, 3 and 5 years respectively. During the follow-up period $93.3\%$ of patients were in NYHA class I, or II and $91.1\%$ were free from angina. Conclusion: Although operative complication is increased, CABG can be performed with an acceptable operative mortality and excellent late results in patients older than 75 years.

• 한국해양학회지
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• v.30 no.2
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• pp.91-115
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• 1995

Air-sea heat fluxes in the East Sea were estimated from the various ship's data observed from 1961 to 1990 and the JMA buoy #6 data from 1976 to 1985. The oceanic heat transport in the sea was also determined from the fluxes above and the heat storage rate of the upper layer of 200m from the sea surface. In winter, The incoming solar radiation is almost balanced with the outgoing longwave radiation. but the sea loses her heat through the sea surface mainly due to the latent and sensible heat fluxes. The spatial variation of the net surface heat flux is about 100 Wm/SUP -2/, and the maximum loss of heat is occurred near the Tsugaru Strait. There are also lots of heat losses in the southern part of the East Sea, Korea Strait and Ulleung Basin. Particularly, the heat strong loss in the south-western part of the sea might be concerned with the formation of her Intermediate Homogeneous Water. In summer, the sea is heated up to about 120∼140 Wm/SUP -2/ sue to strong incoming solar radiation and weak turbulent heat fluxes and her spatial variation is only about 20 Wm/SUP -2/. The oceanic heat flux is positive in the southeasten part f the sea and the magnitude of the flux is larger than that of the net surface heat flux. This shows the importance of the area. In the southwestern part of the sea, however, the oceanic heat flux is negative. This fact implies cold water inflow, the North Korean Cold Water. The sigh of net surface heat flux is changed from negative to positive in March and from positive to negative in September. The heat content in the upper surface 200 m from the sea surface reaches its minimum in March and maximum in October. The annual variation of the net surface heat flux is 580 Wm/SUP -2/ in southwestern part of the sea. The annual mean values of net surface heat fluxes are negative, which mean the net heat transfer from the sea to the atmosphere. The magnitude of the flux is about 130 Wm/SUP -2/ near the Tsugaru Strait. The net surface fluxes in the Korea Strait and the Ulleung Basin are relatively larger than those of the rest areas. The spatial mean values of surface heat fluxes from 35$^{\circ}C$ to 39$^{\circ}$N are 129, -90, -58, and -32 Wm/SUP -2/ for the incoming solar radiation, latent hear flux, outgoing longwave radiation, and sensible heat flux, respectively.