• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.34 no.3
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• pp.214-221
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• 2024

Objectives: People using pedestrian walkways within tunnels may be exposed to environmental hazards that can have adverse effects on their health. This study aimed to measure changes in the levels of particulate matter (PM10), black carbon (BC), and noise after the installation of safety walls on pedestrian walkways within tunnels. Methods: Measurements were taken at the entrances on both sides of a tunnel and at the central point, both before and after the installation of pedestrian safety walls. Additionally, measurements were conducted by distinguishing between non-rush hour and rush hour periods to account for variations in the number of vehicles using the tunnel. A SidePak was used for PM10 measurements, an aethalometer for BC, and a sound level meter for noise. Results: PM10 showed the highest concentrations at the center of the tunnel at both pre- and post-installation of safety walls, as well as during rush hour periods. After the installation, the concentration at the center was 31.09 ± 14.02 ㎍/m³ (19.44 ± 8.02% increase). During rush hour, BC concentration reached 2.28 ± 1.55 ㎍/m³, indicating a 26.71 ± 13.19% increase compared to non-rush hour. As for noise, installation of safety walls reduced noise levels about 3 - 6 dB (8.10 ± 3.31% decrease). Conclusions: It was confirmed that installing safety walls on pedestrian walkways within the tunnel can reduce noise levels. However, the interior of a tunnel is a poorly ventilated environment, and exposure levels vary depending on the length of the tunnel. Therefore, the development of safety measures related to this issue is warranted, and further research on harmful substances within the tunnel should be conducted.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.4
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• pp.88-95
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• 2015

The main sources of recovered paper for newsprint are old newsprint (ONP) and old magazine (OMG). Recently, a lot of advertisement flyers are flowing into bales of ONP and portion of OMG is increasing in recovered paper because the consumption level of coated paper increases. In this study, nonionic surfactant and fatty acid were used as the de-inking agent for froth-flotation process of mixed recovered paper to investigate the effect of increased mixing ratio of OMG. De-inking efficiency of nonionic surfactant decreased as the mixing ratio of OMG increased; ink removal efficiency of froth-flotation is poor, however, the reject ratio increases due to ash from OMG. In comparison with nonionic surfactant, the ash from OMG had a little effect on reject ratio and optical properties of fatty acid applied flotation accept. If nonionic surfactant and fatty acid are added to pulper and flotation cell sequentially, excessive ash from OMG may not give an adverse effect on de-inking efficiency of mixed recovered paper.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.4
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• pp.109-114
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• 2015

In this study, the effects of chlorine dioxide (D) bleaching conditions on the delignification of hemp bast fiber were elucidated. Chlorine dioxide bleaching was carried out through three stages (DED) and five stages (DEDED), respectively. Applied amounts of chlorine dioxide at $D_1$ and $D_2$ stages were varied to find the optimum bleaching condition. It was found that the optical properties of its handsheet as well as the delignification of hemp bast fiber increased as the concentration of chlorine dioxide at $D_1$ stage increased. It was also notable that the bleachability of the DEDED bleaching stages was slightly more effective than that of the DED bleaching stages. The burst index of the handsheets made with bleached hemp bast fiber was higher than that of the unbleached samples, but the burst index of these samples decreased as their delignification increased. These results indicated that the higher concentration of chlorine dioxide at $D_1$ stage was major factor to improve the bleaching efficiency of hemp bast fiber.

• Clean Technology
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• v.19 no.1
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• pp.65-72
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• 2013

In this study, we investigated the activity of Pd and Cu co-incorporated on mesoporous silica support such as MCM-41 and SBA-15 for catalytic nitrate reduction in water. In pure hydrogen flow, nitrate concentration was gradually decreased with the reaction time, but nitrogen selectivity was too low due to very high pH of reaction medium after the reaction. In order to acquire high nitrogen selectivity, we utilized carbon dioxide as a pH buffer, which resulted in higher nitrogen selectivity (about 40%). For the above reaction conditions, Pd-Cu/MCM-41 showed better performance than Pd-Cu/SBA-15. The physicochemical properties of both catalysts were investigated to figure out the relationship between the characteristics of the catalysts and the catalytic activity on the catalytic nitrate reduction by $N_2$ adsoprtion-desorption, X-ray diffraction (XRD), $H_2$-temperature programmed reduction, X-ray photoelectron spectroscopy (XPS) techniques.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.6
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• pp.1411-1420
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• 2015

Lawful interception(LI) standard of telephone networks has technical limitations to lawfully intercept IMS/SIP-based mobile communication network subscriber who using Android and iPhone device. In addition, the technical standards related to legal interception of the IMS/SIP of the wireless network is insufficient compared to the systematic study of the development of a wireless network infrastructure. The architecture proposed in the standard of ETSI(European Telecommunications Standards Institute) for the seamless LI is insufficient to overcome the limitations of traditional voice-centric LI techniques. This paper proposes an IMS/SIP-based architecture to perform LI under 3G networks that focuses on mobility-supported environments with merging cellular networks and the Internet. We implemented the simulation to verify the efficiency of the proposed architecture, and the experimental results show that our method achieves higher lawful interception rate than that of existing interception methods.

• Korean Journal of Animal Reproduction
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• v.14 no.1
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• pp.23-30
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• 1990

These studies were carried out to investigate the effects of fetal calf serum(FCS), estrous porcine serum(EPS), porcine follicular fluid(PFF), hormone and matured cumulus cell(MCC) on in vitro maturation and fertilization of porcine follicular oocytes. The ovaries and testes were obtianed from slaughtered Landrace sow and boars, respectively. The follicular oocytes surrounded with cumulus cells were recovered by aspirating follicular fluid from the visible follicles of diameter 3~5 mm and the semen were prepared from boar's epididymal cauda. The follicular oocytes were cultured in TCM-199 medium containing hormones, FCS, EPS, PFF and MCC for 48hrs. in a incubator with 5% CO2 in air at 36$^{\circ}C$ and then matured oocytes were again cultured for 18~20 hrs. with $1.5\times$106/ml motile capacitated sperm in the modified Tyroide solution containing 100$\mu\textrm{g}$/ml of heparin. The results obtained in these experiments were summarized as follows : 1. The maturation and fertilization rate of the follicular oocytes, cultured in the TCM-199 medium supplemented with 10% FCS and PMSG＋HCG were 55.6~64.5% and 33.3~37.1%, respectively. 2. The maturation and fertilization rate of the follicular oocytes cultured in the TCM-199 medium supplemented with 20% EPS and PMSG＋HCG were 50.0~55.0% and 30.3~33.3%, respectively. 3. The maturation rate(59.0~64.2%) and fertilization rate(34.8~39.3%) of follicular oocytes cultured in TCM-199 medium supplemented 20% FCS and 50% PFF were higher than those of follicular oocytes cultured in TCM-199 medium supplemented with 5%, 10% and 15% FCS and 10% and 50% PFF. 4. The maturation rate(60.0%) and fertilization rate(40.0%) of follicular oocytes cultured in TCM-199 medium supplemented with 20% FCS and granulosa cell (1$\times$106/ml) were significantly higher than those of fiollicular oocytes cultured in TCM-199 medium supplemented with 5%, 10% and 15% FCS and granulosa cell.

• Korean journal of communication and information
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• v.78
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• pp.141-176
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• 2016

This study investigates changes of market structure from 2001 to 2015 in the Korean daily newspaper industry using concentration and mobility measures. The main empirical results are as follows. First, the industry's total asset shows a U-shaped trend, despite the downward trend of the industry's total sales revenue. Second, the market concentration, measured in terms of assets, shows the trend of an inverted-U shape. The relatively small firms, measured in terms of assets, have on average gained in market share while the relatively large firm have lost. Third, market concentration, measured in terms of sales revenues, shows a U-shaped trend. the relatively small firms, measured in terms of sales revenues, have on average gained in market share while the relatively large firm have lost. My central argument has been that it is desirable to supplement traditional concentration measures with mobility statistics and trend analyses in investigating and regulating market structure.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.1
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• pp.139-142
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• 2013

The feasibility of incorporating sweet pumpkin powder as a value-added food ingredient, using a model food system of jelly, was investigated. Sweet pumpkin powder was incorporated into jelly at 0, 2, 4, 6, and 8% (w/w) levels. Qualities, such as moisture content, pH, soluble solids content, color, hardness, and consumer preferences were determined. The moisture content of jelly decreased, but pH and soluble solids content increased significantly with increasing levels of sweet pumpkin powder (p<0.05). Lightness decreased but redness and yellowness increased significantly (p<0.05). Hardness also increased significantly with higher amounts of sweet pumpkin powder in the formulation (p<0.05). Finally, the consumer acceptance test indicated that the highest level of incorporation (8%, w/w) had a considerable adverse effect on consumer preferences in all attributes. The jellies with 2% sweet pumpkin powder are recommended (with respect to overall preference score) for taking advantage of the functional properties of sweet pumpkin powder without sacrificing consumer acceptability.

• Economic and Environmental Geology
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• v.46 no.5
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• pp.445-453
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• 2013

The Uiseong Tapriri Five-Storied Stone Pagoda (National Treasure No. 77) is typical stone cultural heritage in Unified Silla Dynasty, Korea. The pagoda has been occurred black, brown discoloration and microcrack, exfoliation, granularity decomposition with white discoloration because of continuous weathering. As the results of analysis for the contaminants, chemical weatherings are generated that black contaminant by manganese oxide, brown contaminant by iron oxide, white contaminants by gypsum and taranakite. And physical weatherings, such as microcrack, exfoliation, are occurred by salt(gypsum) crystallization. Therefore, these need to remove the contaminants according to the conservation treatment manual, and regular monitoring using P-XRF to preserve long-term the Five-Storied Stone Pagoda at Tapri-ri, Uiseong.

• Laser Solutions
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• v.12 no.3
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• pp.18-22
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• 2009

Experimental results for the laser shock peening of stainless steels, duplex stainless steel and STS304, for the enhancement of surface hardness are reported. A high power Nd:YAG laser (532 nm, 2nd harmonics) was used to irradiate the workpiece in water at the irradiances of 5, 10, $15\;GW/cm^2$. The surface of a workpiece was covered with Fe or Al foil for protection of the original surface and reduction of laser reflection. The laser pulse densities were varied from $25\;pulse/mm^2$ to $75\;pulse/mm^2$. In the case of the STS304, the surface hardness increased with increasing pulse density and the maximum increase of about 29% was achieved using Fe foil at $10\;GW/cm^2$ and $75\;pulse/mm^2$ conditions. The maximum increase in surface hardness of duplex stainless steel was about 8% at $10\;GW/cm^2$ and $75\;pulse/mm^2$ with also Fe foil. In the case of the Al foil, less increase of surface hardness was obtained, possibly due to the thermal expansion effect.