• Journal of Environmental Health Sciences
• /
• v.46 no.6
• /
• pp.694-701
• /
• 2020

Objectives: The main purpose of this study is to evaluate heavy metal concentrations (Cd, As, Hg, Pb, Cr6+), particle size distribution, hydrochloric acid solubility, and parasite eggs in sand in five non-designated sandy beaches in Gyeonggi Province. Methods: The sampling sites are five non-designated Gyeonggi-do sandy beaches located in Ansan and Hwaseong. ICP-OES and UV, a Vibratory Sieve Shaker, and PCM were respectively used to analyze heavy metal concentrations, particle size distribution, and parasite eggs in the sand. Results: Heavy metals were detected within the beach's safety management standards and some of the detected As and Pb before and after beach opening were lower than one-quarter of the average value. In addition, the results of the T-test to confirm the As and Pb concentration changes before and after opening showed a significant difference in some beaches. The composition of sand was 86.53% according to the particle size distribution standard (2.0-0.02 mm), and the hydrochloric acid solubility was the highest at Gubongsolsup (4.9%) and the lowest at Bangameo-li (0.2%). Parasite eggs were undetected in all beach sand before and after opening. Conclusions: The safety of heavy metal concentrations in sandy beaches was secured in the selected five beaches in Gyeonggi Province. However, continuous efforts are required to make Gyeonggi-do's beaches suitable according to the Act on the Use and Management of Beaches.

• Clean Technology
• /
• v.7 no.1
• /
• pp.81-88
• /
• 2001

Limestone has been used as absorbent in the FGD(Flue Gas Desulfurization) system, the DeSOx system of thermal power plant. This study investigated the desulfurization characteristics of the two different limestones, 325mesh and 200mesh particle size. Experimental analysis showed that the dissolving rate of limestone became much slower as the particle size increased. But the desulfurization efficiency depended on the L/G(liquid/gas) ratio and slurry pH regardless of the limestone particle size. The quality of gypsum produced in the FGD process increased as the limestone particle size or the slurry pH decreased. To reduce the cost of absorbent, the mixed limestone which were composed of 200 and 325mesh limestone with 5 different ratios were tested.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.11a
• /
• pp.435-442
• /
• 2000

Batch test and column test were performed to develop the design factors for permeable reactive barriers(PRBs) against ammonium and heavy metals, Clinoptilolite, a kind of natural zeolites having excellent cation exchange capacity(CEC), was choosen for the reacting materials through the ion-exchange mechanism. In the batch test, the reactivity of clinoptilolite for ammonium, lead, and copper was examined varying the initial concentration of contaminants(ammonium: 20, 40, 80 ppm, heavy metals: 10, 20, 40 ppm) and the particle size of clinoptilolites(0-0.15, 0.42-0.85, 1-1.25 mm). The reactivity is increasing as the initial concentration decrease and particle size decrease. In the column test, the permeability and the reactivity of the specimens were examined using flexible-wall permeameter. Specimens were made of clinoptilolite and Jumunjin-sand with 20 : 80 weight ratio varying particle size of clinoptilolite. The maximum permeability(1${\times}$10$\^$-4/-5${\times}$10$\^$-5/cm/s) was achieved in the specimen made of 0.42-0.85 mm clinoptilolite and sand.

• The Korean Journal of Food And Nutrition
• /
• v.11 no.5
• /
• pp.521-527
• /
• 1998

Removabilities of heavy metals(Cd and Pb) by the tea materials (barley-tea, corn-tea, jasmin-tea, brown rice-green tea, black-tea, cassia tora-tea, persimmon peel-tea, and rice-tea) in the tea-water were studied in the various conditions ; particle size of tea (20, 40, 70 mesh), concentration of heavy metal (25, 50, 100 ppm) and extraction temperature(20, 30, 50, 100$^{\circ}C$). The removabilities by the tea solids were increased as the particle size decreased, concentration of heavy metal increased, and extracting temperature increased. Of the nine kinds of tea, Cd and Pb removability by jasmin-tea was highest. In addition, heavy metal removability by cassia tora tea was better than that of other tea as extraction temperature was increased.

• Journal of Environmental Science International
• /
• v.5 no.6
• /
• pp.785-799
• /
• 1996

The incineration tests of mixed industrial wastes using the stoker type incinerator are carried out to investigate the partitioning characteristics of heavy metals during incineration. The results obtained from this study are as follow. The partitioning characteristics of heavy metals throughout this incinerator are found that, at given condition of $700^{\circ}C$, the elements with the relatively high boiling point such as Cr, Cu and Pb are partitioned into a bottom ash, a fry ash captured tv cyclone, and a flue gas stream, 67~88%, 2~19% and 6~16% of initial amount entering the incinerator, respectively, but the Cd and Hg of 75~81% is vaporized into the flue gas. It appears that the partitioning characteristics according to the particle size of ash is different between the bottom ash and the fly ash. For bottom ash, the fraction of partitioning into 75${\mu}{\textrm}{m}$ oversized particles is reatively high. For fly ash, the characteristics of distributions with the particle size can not be clearly shown.

• Radiation Oncology Journal
• /
• v.29 no.3
• /
• pp.135-146
• /
• 2011

With the advance of modern radiation therapy technique, radiation dose conformation and dose distribution have improved dramatically. However, the progress does not completely fulfi ll the goal of cancer treatment such as improved local control or survival. The discordances with the clinical results are from the biophysical nature of photon, which is the main source of radiation therapy in current field, with the lower linear energy transfer to the target. As part of a natural progression, there recently has been a resurgence of interest in particle therapy, specifically using heavy charged particles, because these kinds of radiations serve theoretical advantages in both biological and physical aspects. The Korean government is to set up a heavy charged particle facility in Korea Institute of Radiological & Medical Sciences. This review introduces some of the elementary physics of the various particles for the sake of Korean radiation oncologists' interest.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.1903-1908
• /
• 2003

The motion of a small, heavy rigid particle in the shear flow on a stationary wall is investigated in the context of Stokes flow. The lift force proposed by Saffman(1965) and later modified by Mclaughlin(1991) and Mei(1992) is considered in the prediction of the particle motion far away from the wall. Later, the expression of the lift force is modified to take into account the effect of wall(Cherukat and Mclaughlin, 1994). In the analysis the gravity and buoyancy effect are also taken into account. An analytical and numerical results for the terminal velocities and trajectories of the particle after the enough lapse of time are presented.

• Journal of Korean Society of Environmental Engineers
• /
• v.32 no.12
• /
• pp.1076-1086
• /
• 2010

Soil remediation technologies were experimented to evaluate whether the technologies could be used to apply remediation of contaminated marine sediment. In this research, marine sediments were sampled at "Ulsan" and "Jinhae" where remediation projects are considered, and then the possibility of heavy metal removal was evaluated throughout the technologies. Heavy metal concentration of silt and clay fraction was higher than that of sand fraction at "Ulsan". Heavy metal removal of the silt and clay fraction was arsenic (As) 81.5%, mercury (Hg) 93.8% by particle separation, cadmium (Cd) 72.2%, mercury (Hg) 93.8% by soil washing technology, cadmium (Cd) 70.8%, lead (Pb) 65.6% by another soil washing technology. Based on experimental results, tested particle separation and soil washing technologies could be used to remove heavy metals of sand fraction and silt and clay fraction. Heavy metal removal by soil washing technology which was composed of separation, washing and physical or chemical reaction by additives such as acid, organic solvents was more effective comparing to that of particle separation. Since heavy metal concentration of all treated samples was suitable for national soil standards, all the tested technologies were could be used not only to remove heavy metals of marine contaminated sediment but also to reuse treated samples in land.

• 한국전산유체공학회:학술대회논문집
• /
• 2003.10a
• /
• pp.251-251
• /
• 2003

• Journal of Ocean Engineering and Technology
• /
• v.28 no.2
• /
• pp.177-184
• /
• 2014

Heavy duty coating is playing an important role in the field of heavy industry in the development of the shipbuilding and plant industries. Heavy duty coating has the very important function of protecting steel under serious corrosive conditions. The airless tip used for heavy duty coating is an essential part that determines the spray pattern of the paint. This research investigated the injection properties of three airless tips(numbers 521, 523, and 525) by using particle image velocimetry(PIV). The velocity and turbulent intensity according to pressure change with each tip type were investigated by using PIV. If the pressure is greater, the turbulent intensity becomes stronger and the break up of particles becomes bigger as the tip number gets smaller. The velocity is the fastest in the center and decreases in the radial direction.