• Journal of Environmental Health Sciences
• /
• v.49 no.2
• /
• pp.108-117
• /
• 2023

Background: When particles are absorbed into the human body, they penetrate deep into the lungs and interact with the tissues of the body. Heavy metals in PM_2.5 can cause various diseases. The main source of PM_2.5 emissions in South Korea's atmosphere has been surveyed to be places of business. Objectives: The concentration of heavy metals in PM_2.5 near the Ulsan Industrial Complex was measured and a health risk assessment was performed for residents near the industrial complex for exposure to heavy metals in PM_2.5. Methods: Concentrations of heavy metals in PM_2.5 were measured at four measurement sites (Ulsan, Mipo, Onsan, Maegok) near the industrial complexes. Heavy metals were analyzed according to the Air Pollution Monitoring Network Installation and Operation Guidelines presented by the National Institute of Environmental Research. Among them, only five substances (Mn, Ni, As, Cd, Cr⁶⁺) were targeted. The risk assessment was conducted on inhalation exposure for five age groups, and the excess cancer risk and hazard quotient were calculated. Results: In the risk assessment of exposure to heavy metals in PM_2.5, As, Cd, and Cr⁶⁺ exceeded the risk tolerance standard of 10^-6 for carcinogenic hazards. The highest hazard levels were observed in Onsan and Mipo industrial complexes. In the case of non-carcinogenic hazards, Mn was identified as exceeding the hazard tolerance of 1, and it showed the highest hazard in the Ulsan Industrial Complex. Conclusions: This study presented a detailed health risk from exposure to heavy metals in PM_2.5 by industrial complexes located in Ulsan among five age groups. It is expected to be utilized as the basis for preparing damage control and industrial emission reduction measures against PM_2.5 exposure at the Ulsan Industrial Complex.

• The Journal of shipping and logistics
• /
• v.27 no.3
• /
• pp.457-474
• /
• 2011

The aim of this study is to analyze the efficiency of major ports in Northeast Asia such as Korea, China and Japan. For the empirical analysis, we tried to apply the data envelopment analysis (DEA), which is an efficiency evaluation model based on mathematical programming theory, and we also established a model to Northeast Asian ports. In our opinion, DEA analysis which involves multiple inputs as well as multiple outputs in its efficiency valuation makes analysis more suitable for port efficiency measurement because ports produce a number of different outputs. In this paper, we attempted to analyze the relative efficiency of 27 ports (5 Korean ports, 13 Chinese ports, 9 Japanese ports) through DEA-CCR, DEA-BCC models. According to the result, Chinese ports are relatively efficient than Korean and Japanese ports. The result of the analysis shows that 7 Chinese ports are efficient in DEA-CCR model in 2009, but in DEA-BCC model 8 Chinese ports and 1 Koran port are efficient. Most of inefficient ports have a value closed to 1 in efficiency for scale, it means that the reason of inefficiency is caused from the technical aspect. Furthermore, we also verified that there exists excess of input in Korean and Japanese ports than Chinese ports.

• Journal of Practical Agriculture & Fisheries Research
• /
• v.8 no.1
• /
• pp.43-51
• /
• 2006

An experiment was conducted to examine how the response of dairy cows to a change from twice to thrice-daily milking is affected by deficiencies in the dietary supplies of three amino acids, His, Met and Lys. The amino acid deficiencies were obtained by feeding the cows a diet of grass silage and a cereal-based supplement containing feather meal as the sole protein supplement. Taken overall, the results show that when cows were given the feather meal diet, even though dietary ME was in considerable excess, a deficiency of specific amino acids prevented any increase in milk yield in response to increasing the frequency of milking from twice to thrice daily. The results of half-udder milking showed that when cows consumed the diet deficient in amino acids, milking one half of the gland more frequently reduced the secretion of protein and lactose by the control gland. Neither MBF nor the ratio of 3-MH/creatinine in urine was affected by thrice-daily milking. The present results go a stage further in showing that, against a background of insufficient dietary amino acids, the stimulus of thrice-daily milking is not sufficient to induce a measurable change in the partition of amino acid use between body and udder.

• Clean Technology
• /
• v.15 no.3
• /
• pp.194-201
• /
• 2009

Reductive reactivity of zero-valent iron nanoparticles was investigated for removal of nitrate-nitrogen which is considered one of the major water pollutants. To elucidate the difference in reactivity between preparation methods, iron nanoparticles were synthesized respectively from microemulsion and aqueous solution of ferric ions. Iron nanoparticles prepared from microemulsion were deposited on aluminum by electrophoretic method, and their reaction kinetics was compared to that of the same nanoparticles suspended in aqueous batch reaction. With an approximation of pseudo-first-order reaction, rate constants for suspended nanoparticles prepared from microemulsion and dilute aqueous solution were $3.49{\times}10^{-2}min^{-1}$ and $1.40{\times}10^{-2}min^{-1}$, respectively. Iron nanoparticles supported on aluminum showed ca. 30% less reaction rate in comparison with the identical nanoparticles in suspended state. However, supported nanoparticles showed the superior effectiveness in terms of nitrate-nitrogen removal per zero-valent iron input especially when excess amounts of nitrates were present. Iron nanoparticles deposited on aluminum maintained reductive reactivity for more than 3 hours, and produced nitrogen gas as a final reduction product of nitrate-nitrogen.

• Resources Recycling
• /
• v.31 no.6
• /
• pp.60-65
• /
• 2022

This study presents the carburization process for recycling sludge, which was formed during silicon wafer machining. The sludge used in the carburization process is a mixture of silicon and silicon carbide (SiC) with iron as an impurity, which originates from the machine. Additionally, the sludge contains cutting oil, a fluid with high viscosity. Therefore, the sludge was dried before carburization to remove organic matter. The dried sludge was washed by acid cleaning to remove the iron impurity and subsequently carburized by heat treatment under vacuum to form the SiC powder. The ratio of silicon to SiC in the sludge was varied depending on the sources and thus carbon content was adjusted by the ratio. With increasing SiC content, the carbon content required for SiC formation increased. It was demonstrated that substoichiometric SiC_x (x<1) was easily formed when the carbon content was insufficient. Therefore, excess carbon is required to obtain a pure SiC phase. Moreover, size reduction by high-energy milling had a beneficial effect on the suppression of SiC_x, forming the pure SiC phase.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.27 no.3
• /
• pp.276-282
• /
• 1982

To estimate the responses of sesame plant in growth and yielding traits to different soil drainage conditions, a pot trial was conducted by using of sesame variety "Suweon-9" were introduced with 5 different mixing combinations of clay and sea-sand soils as 0:100, 25:75, 50:50, 75:25, and 100:0 percents in volumetric ratio. Also two irrigation methods as 20mm/6 days interval and 10mm/3 days interval were detected. As a result, water drainage was linearly decreased with increament of clay contents. And the excess drainage condition(such as pure sand soil) required more irrigation, however in crop growths, no significant differences among various soil drainage conditions except the pure sand were recognized. On the other hand, number of capsules per plant, among other yielding components, was most contributed factor to the yield, which was effectively given from the soil mixed with clay and sea-sand as 75% and 25%, respectively. Therefore, much similar responses were also detected from the seed yields per a sesame plant. However, the number of seeds per capsule and maturity function were more effectively composed under the soil mixed with clay and sea-sand as 25% and 75% respectively better than under the soil of 75% and 25%. As a conclusion, the yielding responses of sesame plant was advanced more effectively at the soil conditions of water conserved type (e.g. 25%/75% in clay/sand ratio) than of water-draining type (e.g. 75%/25% in clay/sand ratio).nd ratio).

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.31 no.2
• /
• pp.186-194
• /
• 1986

In an attempt to find better ways to relate growth with temperature and to estimate maturity differences in corn (Zea mays L.), various formulas of computing Growing Degree Days (GDD) were evaluated. Utilizing data from 17 plantings of a single cross, Suweon 19, over a 3 year period, 24 different methods of computing GDD were compared for their ability to reduce variations over different plantings. The best equation was to compute GDD with a base temperature of 10$^{\circ}C$ and an optimum of 30$^{\circ}C$. The excess temperature above 30$^{\circ}C$ was subtracted to account for high temperature stress. GDDs required for emergence and silking of Suweon 19 were 64${\pm}$12$^{\circ}$ and 794${\pm}$19$^{\circ}$, respectively. Based on these GDD values, emergence and silking dates could be estimated with a variation less than 3 days. The observed and estimated number of days from planting to emergence and silking were not significantly different.

• Journal of the Korean Geotechnical Society
• /
• v.26 no.8
• /
• pp.77-88
• /
• 2010

In this study, 1 g shaking table group pile tests were performed for various conditions of subgrade and pile spacing. The pile spacing was changed from three to seven times of pile diameters. It could be confirmed that the dynamic p-y curves for the group pile observed as the results of a series of shaking table tests show difference according to the pile spacing, the pile location within the pile group, the relative density of subgrade and the excess pore pressure during earthquake. The dynamic p-multipliers were calculated by comparing the dynamic p-y backbone curves of a single pile suggested by Yang (2009) and dynamic p-y curves for the group pile. Dynamic p-multiplier values overall increase as the relative density of subgrade and amplitude of input acceleration increase. The dynamic group pile effect was neglected, if the pile spacing was seven times as large as pile diameters. It was found that the exisiting p-multiplier values suggested by various researchers for the static and dynamic loading, and the values recommended by globally used specifications show difference with the test results by up to 0.7 (approximately 70%). Therefore, the dynamic p-multipliers were newly suggested according to the pile spacing and the relative density of subgrade using the test results.

• Journal of the Korean Geotechnical Society
• /
• v.23 no.2
• /
• pp.71-83
• /
• 2007

Liquefaction resistance depends strongly upon the degree of saturation, which is expressed in terms of the pore pressure coefficient, B. The B-value has been widely used to quantify the state of saturation of laboratory samples. However, it is practically impossible to determine in situ state of saturation by using the B-value. So, P-wave velocity can be alternatively used as a convenient index for evaluating the in situ state of saturation. In this paper, the Stokoe type torsional shear (TS) testing system was modified to saturate the specimen, with which it is also possible to measure P ($V_p$), S-wave velocity ($V_s$) and the excess pore water pressure buildup In order to examine the effect of B-value for nearly saturated sands. A series of the tests were carried out at 3 relative densities (40%, 50% and 75%) and various B-values using Toyoura sand. Based on the test results, the variations of $V_p\;and\;V_s$ with B-value were analyzed and compared with a existing theoretically derived formula. The normalized pore water pressure, $du/{\sigma}{_0}'$ and cyclic threshold shear strain, ${\gamma}^c_{th}$ with B-value were also analyzed. Additionally the test results related to pore water pressure were analyzed by $V_p$ to apply to the field seismic analysis.

• Journal of the Korean Geotechnical Society
• /
• v.22 no.8
• /
• pp.43-54
• /
• 2006

The scope of this paper covers the applications of bender element tests in consolidation, tomography, and liquefaction. Loading and unloading time during consolidation are evaluated based on shear wave velocity. As S-wave velocity is dependent on effective stress, the loading step may be determined. However, cautions are required due to the different mechanism between the settlement and effective stress criteria. The stress history may be evaluated because the S-wave shows the cement controlled regime and stress controlled regimes. A fixed frame complemented with bender elements permits S-wave tomography The tomography system is tested at low confinement within a true triaxial cell. Results show that shear wave velocity tomography permits monitoring changes in the velocity field which is related to the average effective stress. To monitor the liquefaction phenomenon, S-wave trans-illumination is implemented with a high repetition rate to provide detailed information on the evolution of shear stiffness during liquefaction. The evolution of shear wave propagation velocity and attenuation parallel the time-history of excess pore pressure during liquefaction. Applications discussed in this paper show that bender elements can be a very effective tool for the detection of shear waves in the laboratory.