• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.6
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• pp.468-472
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• 2005

In order to prevent adhering of molten glass on a mold wall, the wall is swabbed with lubricant oil before forming. However, the swabbing process can be removed from the entire processes of the glass forming if the mold wall is made of a porous sintered material. The purpose of the present study is to manufacture a sintered material(having a sintered density of $85{\~}90\%$)which is the most appropriate into. plane material for a glass mold. For the research, SUS310L-based coarse powder (${\~}150{\mu}m$) and SUS420J2-based fine powder ($40{\~}50{\mu}m$) were used for the compact materials, and effects of compaction pressure and sintering condition(atmosphere, temperature) were investigated. The results obtained were as fellows. (1) By means of solid phase sintering, a desired sintering density could not be achieved in any case when using a 310L-based powder having a large particle size. (2) When sintering green compacts(compaction pressure of $2ton/cm^2$) in a commercial vacuum furnace(at $1300^{\circ}C$ for 2 hours), the sintered compacts had densities of $6.2g/cm^3(79\%)$ for 310L + 0.03$\%$B, $6.6g/cm^3 (86\%)$ for 420J2, $7.3g/cm^3(95\%)$ for 420J2+(0.03)$\%$B, and $7.6g/cm^3(99\%)$ for 420j2+(0.06)$\%$B, respectively. As a result, it is regarded that sintered compacts having a desired porosity may be achieved by vacuum sintering the 420J2-based powder (low pressure compaction) and the 310L+0.03$\%$B-based powder (high pressure compaction).

• Economic and Environmental Geology
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• v.33 no.2
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• pp.91-100
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• 2000

It has been more than ten years since Dukun mine was abandoned. Tailings of waste deposits and slime dumps in the abandoned Dukum mine have been left to be deserted for fifty years. The results of fifty years of neglecting are nothing short of major environmental problems. Slime dumps have been exposed to air and water in the mine over ten years and then soil profile has been formed well. Soil in the upper layer (A horizon) is the light gray color due to the leaching of cations. Soil in the lower layer (A2 horizon, 0.2∼0.3m)is tinted with reddish brown and yellowish brown color due to the development of iron oxides and iron hydroxides. Soil in the lower part of B horizon of (1.0∼3.0m) with the growth of copper and zinc oxides exposes to the bluish green, light blue, and dark gray. Ranging from 3m to 8m in depth, 85 samples were taken from 22 sampling sites with 50m intervals located on the slime dump area with hand auger and trench (open cut). As tailings was distributed, heavy metal elements extracted by the process of surface water and ground water move and disperse in to the hydrosphere. Waste dumps were distributed in and around the mine and water draining from those dumps be a potential source of contamination. Soils, thus, can be dispersed into downslope and downstream through wind and water by clastic movement. These materials may be deposited in another horizon if the water is withdrawn, or if the materials are precipitated as a result of differences in pH, or other conditions in deeper horizons. These were primarily associated with acid mine drainage. The characteristics and rate of release of acid mine drainage are influenced by various chemical and biological reactions at the source of acid generations. Prolonged extration of heavy metal elements has a detrimental effect on the agricultural land and residental area. Twenty soil samples were collected from the agricultural land in the area (0∼30 cm). Seventeen samples were also taken from the sediment in the stream running alongside the dumps. The dispersion patterns of heavy metal elements are as follows: The content of As ranged 2∼6 ppm in a horizon, 20∼125 ppm in B horizon with large amount of clay mineral is concentrated and the content of Cd ranged 1∼2 ppm in A horizon, 4∼22 ppm in B horizon. Like Cd, the content of As, Cu, Zn, Pb in B horizon is higher than that in A horizon (approximately 5∼100 times). When soil formation proceeds in stages, it is necessary to investicate the B horizon with the concentration of heavy metal and preventive measures will have to established.

• Journal of Conservation Science
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• v.30 no.4
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• pp.457-466
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• 2014

Rigorous analysis was performed to identify the structure and materials of the murals to study techniques used on mural tombs of ancient Daegaya era(6th century). The murals were painted by applying mortar on the walls and the ceiling after building a stone chamber and creating ground layers on mortar layers. Mud was applied on most of the mortar layers on four sides of the walls except the ceiling. Sand was not used in mortar but was made of materials with pure calcium substances. In addition, shells in irregular sizes with incomplete calcination were mixed; and the mortar's white powder was inferred as lime obtained by calcination of oyster shells. Kaolinite($Al_2Si_2O_5(OH)_4$) was used in the ground layer, Cinnabar(HgS) was used for red pigment, Malachite($Cu_2CO_3(OH)_2$) for green and Lead white($PbCO_3{\cdot}Pb(OH)_2$) for white. Mud plaster was applied on the mortar and was composed thinly and densely using clayey of particle size smaller than that of medium sand. It was assumed that the finishing was for repair after long time had passed since the mortar layer came off. Using lime made with oyster shells as mortar is unprecedented in ancient Korean mural tombs and its durability was very poor, suggesting that Gaya's mortar production technique was relatively behind compared to that of Koguryo's in the same era.

• Clean Technology
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• v.26 no.1
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• pp.1-6
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• 2020

Rapid expansion of supercritical solution (RESS) process was used to make molsidomine (MOL) loaded peracetyl-β-cyclodextrin (PAc-β-CD) nanoparticles, which were collected into the air. The effect of the concentration of the drug PAc-β-CD (0.5 and 1 wt%), extraction temperature (45 ~ 60 ℃), nozzle length (5 ~ 20 mm) and internal diameter (ID) (50 ~ 150 μm) of a capillary, and spray distance on the particle size and morphology of the resulting particles were investigated. The interaction of a drug and PAc-β-CD was confirmed by ¹H-NMR spectroscopy while the particle size was measured by means of a scanning electron microscope. It was found that increasing the temperature from 45 ℃ to 60 ℃ and decreasing the nozzle diameter from 150 μm to 50 μm had an increasing effect on the average particle size, while increasing the spray distance led to a decrease in the average particle size at a constant pressure of 34.5 MPa and temperature of 45 ℃. With 0.5 wt% of PAc-β-CD, the capillary nozzle of short length (5 mm) and small ID (50 μm) gave the smallest size (165 nm). The obtained nanoparticles showed increased dispersity and solubility in oil. The oil suspension of the inclusion complex showed increased sustainability, which can increase the in-vitro controlled release time of the drug.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.4
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• pp.637-642
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• 2010

Pre-treatment steps of fresh produce as Saengshik raw materials are followed by initial clean-up, dipping, primary washing, and cutting. Hypochlorous acid solution was applied in the dipping step to reduce natural microflora. Also, procedures were changed by cutting, dipping and then primary washing, and the efficacy of hypochlorus acid was evaluated. Potatoes, carrots, kales, and angelicas were submerged in water or 100 ppm of hypochlorous acid for 5 min. After initial clean-up, the aerobic plate counts of potatoes, carrots, kales and angelicas were 4.7, 5.3, 5.6, and 5.7 log CFU/g, respectively. When samples were submerged into water, it only reduced the population of natural microflora by 0.2 to 1.1 log CFU/g, whereas when treated with hypochlorous acid, it reduced the population by 0.5 to 2.8 log CFU/g. Reductions of natural microflora in green leafy vegetables were more highly achieved than bulbs such as potatoes and carrots. However, the numbers of natural microflora were increased after cutting step. To control the cross contamination at the cutting process, the process was changed as follows: initial clean-up, cutting, dipping in hypochlorous acid, and then primary washing. It showed effective reduction of the population by 2.3 to 3.2 log CFU/g. Hypochlorous acid solution could be useful as a sanitizer for surface washing of fresh vegetables.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.6
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• pp.577-583
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• 2011

To meet the requirements of the Tier 4 interim regulations for off-road vehicles, emissions of particulate matter (PM) and nitrogen oxides (NOx) must be reduced by 95% and 30%, respectively, compared to current regulations. In this research, both the DPF and HPL EGR systems were investigated, with the aim of decreasing the PM and NOx emissions of a 56-kW off-road vehicle. The results of the experiments show that the DOC-DPF system is very useful for reducing PM emissions. It is also found that the back pressure is acceptable, and the rate of power loss is less than 5%. By applying the HPL EGR system to the diesel engine, the NOx emissions under low- and middle-load conditions are reduced effectively because of the high differential pressure between the turbocharger inlet and the intake manifold. The NOx emissions can be decreased by increasing the EGR rate, but total hydrocarbon (THC) emission increases because of the increased fuel consumption needed to compensate for the power loss caused by EGR and DPF.

• Journal of Food Hygiene and Safety
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• v.15 no.2
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• pp.95-100
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• 2000

The effect of natural foods, utilizing the extracts or juices of teas(Green tea; Camellia sinesis, Du'chung; Eucommia ulmoides Oliver), medicinal plants(Eu sung cho; Houttuynia cordata Thunb, Sam back cho; Saurus Chinensis, Baek hwa sa seal cho; Oldenladia diffusa Roxb.) seaweeds(Laver; Porphyra tenera, Sea mustard; Undaria pinnatifida, Sea staghorn; Condium fragile) and vegetables(Sweet pepper; Capsicum annuum var. angulosum, Kale; Brassia oleracea var.. acephala, Cucumber; Cucumis sativus, Onion; Allium cepa) and fruits(Tomato; Lycopericon esculentum, Maesil; Prunus mume, Plum; Prunus saticina and Grape; Vitis spp.)on the inhibition of N-Nitrosodimethylamine(NDMA) formation was investigated from the various conditions. The inhibition effect was observed in vitro using the reaction fluids of pH 1.2, 4.2 and 6.0. From the teas and medicinal plants, there was a positive response of NDMA formation; however, From the seaweed extracts, there was a negative response of the inhibition effect of NDMA formation, and as the pH of reaction fluids and the amount of materials increase, the inhibition of NDMA formation was strengthened. The inhibition ratios by the level of pH are as follows: under pH 1.2 vegetable juice were 57.6∼99.7% and fruits were 35.9∼99.7%; under pH 4.2 vegetable juice were 55.0∼97.5% and fruits were 21.3∼96.8%. All of the materials observed has been proved and shown the inhibition effect of NDMA formation.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.3
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• pp.43-49
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• 2010

Direct printing technology is an attractive metallization method, which has become immerging as "Green technology" to the conventional photolithography, on account of low cost, simple process and environment-friendliness. In order to commercialize the printed electronics in industry, it is essential to evaluate the electrical properties of conductive circuits using direct printing technology. In this contribution, we focused on the electrical characteristics of inkjet-printed circuits. A Cu nanoink was inkjet-printed onto a Bisaleimide triazine(BT) substrate with parallel transmission line(PTL) and coplanar waveguide(CPW) type, then was sintered at $250^{\circ}C$ for 30 min. We calculated the resistivity of printed circuits through direct current resistance by the measurement of I-V curve: the resistivity was approximately 0.558 ${\mu}{\Omega}{\cdot}cm$ which is about 3.3 times that of bulk Cu. Cascade's probe system in the frequency range from 0 to 30 GHz were employed to measure the Scattering parameter(S-parameter) with or without a gap between the substrate and the probe station chuck. The result of measured S-parameter showed that all printed circuits had over 5 dB of return loss in the entire frequency range. In the curve of insertion loss, $S_{21}$, showed that the PTL type circuits had better transmission of radio frequency (RF) than CPW type.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.137-143
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• 2020

To ensure safety of raw materials for military foods, hazard assessment and monitoring of residual pesticides was conducted on agricultural products consumed by 9 companies based in Gyeongin and Gangwon. Residual pesticides were analyzed for 142 different products, by applying the multi-species pesticide polycomponent analysis method. Of the 36 samples analyzed, residual pesticides were detected in 7 samples, representing a detection rate of 19.4%. One particular pesticide residue was detected in peanuts, green onions, and red pepper powder, and 20 types of pesticide residues were detected in red pepper powder used in combat foods. However, all residues were found to be below the permissible level. Moreover, the hazard assessment results for Cypermethrin, Tebuconazole and EPN showed the highest concentration among the residual pesticides detected. Since the estimated intake was less than 100% as compared to the ingestion limit, it was considered to be safe. I have suggested the edit as per my understanding. Please review for accuracy, and revise appropriately if required. This is the first pesticide Risk Assessment study encompassing military requirements. Considering the results, we expect further application research, including research on reducing hazardous materials.

• The Korea Journal of Herbology
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• v.23 no.4
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• pp.21-29
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• 2008

Objectives: To determine the standards for discrimination of Magnoliae Cortex, the experiment of specific external-internal characters and the physicochemical pattern analysis were performed. Methods: External characteristics was observed using a stereoscope. Paraffin-mediated sectioned materials were stained by Ju's method. Physicochemical patterns of materials were analyzed using HPLC. Results: 1. Botanical characteristics: Magnolia officinalis had one seed and a white flower, while M. obovata had two seeds and a white flower. Machilus thunbergii had berry and spherical fruits and yellowish green panicles. 2. External characteristics: M. officinalis and M obovata were dark and thick. M. officinalis was gray brown and greasy while M. obovata was light-gray, less oily and smoothly sectioned. Machilus thunbergii was thin and relatively light or yellow-brown, coarsely sectioned and faintly specific scents. 3. Internal characteristics: The bast parts of M. officinalis and M. obovata were commonly wider than Machilus thunbergii The cork cortex of M. officinalis was $10{\sim}mg/L$ cell layers with many oil cells, while that of M. obovata was $4{\sim}7$ cell layers with less oil cells. Machilus thunbergii's xylem which consisted of ring-shaped cambium at 1st and 2nd part was occupied in large portion. 4. Physicochemical pattern: Both M. officinalis and M. obovata involved honokiol and magnolol. All kinds of M. officinalis involved Magnatriol B but one kind of M. ovobata and all of Machilus thunbergii didn't. Machilus thunbergii showed different pattern of chromatogram from that of 2 species above. Conclusions: These results could be used as standards for discrimination of Magnoliae Cortex and as the method of objectification in medicinal herbs giving the basic resource for bioactivity research.