• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.spc
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• pp.30-36
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• 2022

A sensor is needed to continuously and automatically measure the change in HNS concentration in industrial facilities that directly discharge to the sea after water treatment. The basic function of the sensor is to be able to detect ppb levels even at room temperature. Therefore, a method for increasing the sensitivity of the existing sensor is proposed. First, a method for increasing the conductivity of a film using a conductive carbon-based additive in a nanoparticle thin film and a method for increasing ion adsorption on the surface using a catalyst metal were studied.. To improve conductivity, carbon black was selected as an additive in the film using ITO nanoparticles, and the performance change of the sensor according to the content of the additive was observed. As a result, the change in resistance and response time due to the increase in conductivity at a CB content of 5 wt% could be observed, and notably, the lower limit of detection was lowered to about 250 ppb in an experiment with organic solvents. In addition, to increase the degree of ion adsorption in the liquid, an experiment was conducted using a sample in which a surface catalyst layer was formed by sputtering Au. Notably, the response of the sensor increased by more than 20% and the average lower limit of detection was lowered to 61 ppm. This result confirmed that the chemical resistance sensor using metal oxide nanoparticles could detect HNS of several tens of ppb even at room temperature.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.3
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• pp.149-155
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• 2004

This study was conducted to evaluate the availability of liquid pig manure (LPM) as a substitute for chemical fertilizer (CF) in double cropping system of rice followed by onion. The LPM applied for rice in silty clay loam soil cultivated in the double cropping system with onion contained $3.8g\;N\;kg^{-1}$, $1.8g\;P_2O_5\;kg^{-1}$ and $2.7g\;K_2O\;kg^{-1}$. The LPM applied for onion after rice contained $4.9g\;N\;kg^{-1}$, $1.4g\;P_2O_5\;kg^{-1}$ and $2.1g\;K_2O\;kg^{-1}$. Soil pH increased after rice culture irrespective of treatments. The rice growth and grain yield among CF and LPM applications were not significantly different. The application of LPM without top dressing of CF delayed onion growth at mid and late stage. But when the LPM was applied as basal fertilizer and CF was added for top dressing, onion growth was maintained until late growth stage. The nutrient uptake of LPM and top-dressing by CF (rice)/LPM and top-dressing by CF (onion) were similar to CF (rice)/CF (onion). The highest yield of onion bulb was 58.5 Mg ha-1 at CF (rice)/LPM and top-dressing by CF (onion) treatment, but showed no significant difference with other treatments except CF (rice)/LPM only (onion) and no fertilization (rice)/no fertilization (onion) treatments. In conclusion, in double cropping system of rice followed by onion, rice was capable of being grown by only liquid pig manure but additive chemical fertilizer was needed for optimal onion growth.

• Korean Journal of Food Science and Technology
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• v.34 no.6
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• pp.1048-1056
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• 2002

Quality of fresh ginger deteriorates rapidly during low temperature storage, and its storage life is short due to sprouting and microbial spoilage. The objectives of this research were to develop, using additives, a minced ginger product, which could maintain acceptable quality for over 30 days, and to investigate its quality changes during the cold storage. Storage stability of minced ginger product was investigated from the standpoint of the inhibition of brown discoloration, gas formation and liquid-solid separation. Fresh ginger was peeled and ground to produce minced ginger (control). Sodium bisulfite, L-cysteine, NaCl, sodium benzoate, modified starch, and/or xanthan gum were added to the control to minimize quality loss during storage, and to develop an optimum formula (A) of minced ginger. Samples were packed in Nylon/PE films, stored at $5^{\circ}C$, sampled at a 30-day interval, and subjected to quality evaluations. Changes in pH, surface color, gas formation, liquid-solid separation, contents of free amino acids, free sugars, organic acids, and fatty acids were determined. Gas formation was effectively inhibited in samples with sodium benzoate and/or NaCl. Samples with xanthan gum did not result in liquid-solid separation. L-Cysteine and sodium bisulfite were effective in controlling discoloration. pH decreased during storage in all samples, except sample A. Organic acid contents of all samples increased during storage, with lactic acid content showing the highest increase. Free amino acid content decreased with increasing storage time. Free sugar content of all samples decreased during storage. Sensory results showed sample A maintained acceptable quality until 90 days of storage. These results suggest that quality of minced ginger could be successfully maintained with the additions of selected additives for up to 90 days.

• Korean Journal of Poultry Science
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• v.33 no.4
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• pp.309-316
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• 2006

This study was conducted to investigate the effects of dietary natural mineral liquid complex on egg production and characteristics in laying hens. A total of two hundreds fifty two, 63-weeks-old, Hy-line brown commercial layers were used for 6 weeks. Seven dietary treatments included CON (Control), C1-M0.25 (CON diet+1% chitosan+0.25% natural mineral complex), C1-M0.5 (CON diet+1% chitosan+0.50% natural mineral complex), C2-M0.25 (CON diet+2% chitosan+0.25% natural mineral complex), C2-M0.50 (CON diet+2% chitosan+0.50% natural mineral complex), C3-M0.25 (CON diet+ 3% chitosan+0.25% natural mineral complex) and C3-M0.50 (CON diet+3% chitosan+0.50% natural mineral complex). For overall period, egg production, egg shall breaking strength, haugh unit, K and Fe concentrations of blood and Fe concentration of yolk were improved in additive natural mineral treatments compared to control treatment(P<0.05). K and Fe concentrations of blood and Fe concentration of yolk were increased in added 0.5% mineral treatment compared to added 0.25% mineral treatment(P<0.05). Additive 3% chitosan + 0.5% mineral treatments were improved on egg Production and egg shall breaking strength in laying hens(P<0.05). In conclusion, chitosan and natural mineral complex supplementation in lay hens diet improved egg oduction, egg all strength and mineral concentrations of blood and yolk.

• Journal of the Korean Ceramic Society
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• v.40 no.8
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• pp.751-757
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• 2003

Rapid densification of a SiC-30 wt% TiC powder with additive 10 wt% A1$_2$O$_3$-Y$_2$O$_3$-CaO was conducted by Spark Plasma Sintering(SPS). The fully-densified materials can be obtain through the SPS process with very fast heating rate and short holding time. In the present work, the heating rate and applied pressure were kept to be $100^{\circ}C$/min and 40 MPa, while sintering temperature varied from $1600^{\circ}C$ to $1800^{\circ}C$ for 10 min. The full densification of SiC-30 wt% TiC composites with the addition of $Al_2$O$_3$, $Y_2$O$_3$ and CaO was achieved at the temperature above $1700^{\circ}C$ by spark plasma sintering. The XRD found that 3C-SiC and TiC were maintained the entire SPS process temperature, without phase transformation of SiC and formation of YAG phase to $1800^{\circ}C$. The microstructures of the rapidly densified SiC-30 wt% TiC composites consisted of smaller equiaxed SiC grains and larger TiC grains. The biaxial strength of 635.2 MPa and fracture toughness of 6.12 MPaㆍ$m^{1/2}$ were found for the specimen prepared at $1750^{\circ}C$.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.1
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• pp.50-57
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• 2015

Portland cement production is under critical review due to high amount of $CO_2$ gas released to the atmosphere. Attempts to increase the utilization of a by-products such as fly ash and ground granulated blast-furnace slag to partially replace the cement in concrete are gathering momentum. Many researchs on alkali-activated concrete that does not need the presence of cement as a binder have been carried out recently. Instead, the sources of material such as fly ash, that are rich in Silicon(Si) and Aluminium(Al), are activated by alkaline liquids to produce the binder. Hence concrete with no cement is effect reduction of $CO_2$ gas. In this study, we investigated the influence of the fluidity, air content and compressive strength of mortar on alkaline activator in order to develop cementless fly ash and ground granulated blast-furnace slag based alkali-activated mortar with superplasticizer. In view of the results, we found out that Pn of fluidity and compressive strength is the best in four type of superplasticizer, and PNS of powder type of fluidity is better than that of liquid type in the case of AA.

• Toxicological Research
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• v.20 no.3
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• pp.195-203
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• 2004

4-Tert-Octylphenol (OP) is a surfactant additive widely used in the manufacture of a variety of detergents and plastic products. OP can disrupt endocrine function in humans and animals. This study was carried out to obtain toxicokinetic parameters of OP in male Sprague-Dawley (SD) rats. Male rats were administered with OP by single oral application of 200 mg/kg body weight. Blood, urine and tissues samples were taken at several time intervals after administration. Analysis of samples for OP was performed by column-switching high performance liquid chromatography (HPLC). In addition, we exam-ined tissue distribution and accumulation of OP after single oral application of 50, 100, and 200 mg/kg, single intravenous injection of 1, 5 and 10 mg/kg or daily application of 50 mg/kg for 14 consecutive days. After single oral administration of 200 mg/kg, Cmax of 213 $\pm$ 123 ng/ml was reached within the first 1.3 hr (Tmax) in the plasma. AUC was calculated for 1,333$\pm$484 ngㆍhr/ml. The final elimination half-life of plasma was longer than that of urine, but urinary clearance was lower than oral. A very small fraction of OP (Fe < 0.0017%) was excreted in urine within 24 hr. These results indicated that the major excretion route of OP was not urine. The mean maximal tissue distribution of OP was obserbed at 6 hr after treatment and slowly decreased time-dependently. High OP concentrations were detected in fat at 24 hr. The OP in fat was slowly released with longer elimination half-life and lower clearance than that of other tissues. OP was not accumulated in the liver following single oral application but 14-day oral treatments resulted in two-fold accumulation. It was probably due to the saturation of detoxification pathways. On the other hand, the mRNA expression of cytochrome P450 isoforms except CYP2C11 was not affected by OP at any dose. The expression of CYP2C11 mRNA decreased in a dose-dependent manner. This result suggests that OP changes expression of the male-specific cytochrome P450 isoforms in rat liver, and these changes are closely related to the toxic and estrogenic effect of OP.

• Food Science of Animal Resources
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• v.28 no.3
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• pp.373-389
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• 2008

This study was conducted to evaluate exposure level and risk of heavy metals in livestock foodstuffs and Korean foods. Based on the "Food Intake Data," a part of the 2005 National Health & Nutrition Survey and the "2005 Seasonal Nutrition Survey", 113 Korean foods items were selected. 3 samples from different manufacturers of each 113 items of Korean foods were purchased on summer and fall, so total 678 samples were used. The food groups were classified into 15 categories. For the livestock foodstuffs category, meats and poultry (chicken, pork, pork belly, beef, beef feet soup), milks and dairy products (milk, ice cream, liquid yoghourt, sherbet), eggs (egg) were selected. It was found that the daily amount of heavy metals intake (mg/person/day) from livestock foodstuffs is 0.00020 arsenic, 0.00000 cadmium, 0.00020 lead, and 0.00006 mercury, and the daily amount of heavy metals intake (mg/person/day) from Korean foods is 0.0265 arsenic, 0.0083 cadmium, 0.0067 lead, and 0.0028 mercury. Daily amount of heavy metals intake from livestock foodstuffs was low among the food groups. For risk assessment, PDI (Probable Daily Intake) was calculated and compared with PTWI (Provisional Tolerable Weekly Intake) of JECFA (Joint FAO/WHO Expert Committee on Food Additive). Relative hazard of these livestock foodstuffs was 0.006% in arsenic, 0.000% in cadmium, 0.085% in lead, and 0.149% in mercury. Relative hazard of Korean foods was 0.941% in arsenic, 14.676% in cadmium, 3.319% in lead, and 6.860% in mercury. Thus, livestock foodstuffs and Korean foods were as safe as satisfied with the recommended standards of JECFA.

• Applied Chemistry for Engineering
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• v.28 no.6
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• pp.607-618
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• 2017

Harmful air pollutants are exhausted from the various industrial facilities including the coal-fired thermal power plants and these substances affects on the human health as well as the nature environment. In particular, nitrogen oxides ($NO_x$) and sulfur dioxide ($SO_2$) are known to be causative substances to form fine particles ($PM_{2.5}$), which are also deleterious to human health. The integrated system composed of selective catalytic reduction (SCR) and wet flue gas desulfurization (WFGD) have been widely applied in order to control $NO_x$ and $SO_2$ emissions, resulting in high investment and operational costs, maintenance problems, and technical limitations. Recently, new technologies for the simultaneous removal of $NO_x$ and $SO_2$ from the flue gas, such as absorption, advanced oxidation processes (AOPs), non-thermal plasma (NTP), and electron beam (EB), are investigated in order to replace current integrated systems. The proposed technologies are based on the oxidation of $NO_x$ and $SO_2$ to $HNO_3$ and $H_2SO_4$ by using strong aqueous oxidants or oxidative radicals, the absorption of $HNO_3$ and $H_2SO_4$ into water at the gas-liquid interface, and the neutralization with additive reagents. In this paper, we summarize the technical improvements of each simultaneous abatement processes and the future prospect of technologies for demonstrating large-scaled applications.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.1
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• pp.41-46
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• 2011

The artificial aggregates (AAs) composing of 2 wastes, coal bottom ash and dredged soil (7 : 3, weight ratio) were fabricated as a function of red mud contents,0~30 wt% using direct sintering method at $1050{\sim}1250^{\circ}C$ for 10 min, and those physical properties were evaluated. Especially, in order to analyze the red mud addition effect on the bloating phenomenon of AAs manufactured, the specific gravity and water absorption were measured and studied linked with the microstructural observation results. The lightening of AAs was enhanced due to increased bloating with increasing temperature and red mud contents. The AAS sintered at $1050{\sim}1150^{\circ}C$ showed well-developed black-coring structure, but for the specimens containing red mud sintered over $1200^{\circ}C$ generated excessive liquid and gas caused by reduction of $Fe_2O_3$, thus the black-coring part was gradually burst open out of shell of AAs. Particularly, all specimens containing 30 wt% red mud was burst up when sintered over $1100^{\circ}C$. The AAs containing no red mud sintered at $1200^{\circ}C$ had a specific gravity of about 1.2 and those containing 20 wt% had below 1.0 which are characters of lightweight aggregate.