• YAKHAK HOEJI
• /
• v.34 no.1
• /
• pp.1-10
• /
• 1990

Total suspended particulate (TSP) in the atmosphere was collected and size-fractionated by Andersen high volume air sampler for the past two years (Mar. 1987-Feb. 1989) in Seoul. The concentrations of several polycyclic aromatic hydrocarbons and heavy metals were determined to investigate the atmospheric concentrations, seasonal variations and its relationship with the size distribution of suspended particulate matter. The arithmetic mean concentration of total suspended particulate was $229.48\;{\mu}g/m^3$. The concentrations of heavy metals were $2971.94\;ng/m^3$ for Fe, $767.75\;ng/m^3$ for Zn, $765.80\;ng/m^3$ for Pb, $218.40\;ng/m^3$ for Cu, $129.91\;ng/m^3$ for Mn, respectively. And the concentration of PAHs were $3.23\;ng/m^3$ for benzo(a)pyrene, $2.71\;ng/m^3$ for benzo(k)fluoranthene, $4.53\;ng/m^3$ for benzo(ghi)perylene, respectively. The mass-size distribution of TSP was lowest in the particle size range $1.1-3.3\;{\mu}m$ increased as the particle size increased or decreased. But PAHs, Pb and Zn abounded in particles below $2.0\;{\mu}m$, while Fe and Mn abouned in particles above $2.0\;{\mu}m$. TSP and its chemical compositions showed the seasonal variations. The concentrations of anthrophogenic origin like TSP, PAH and heavy metals in the fine particles were highest in winter and lowest in summer. PAH and Ph analyzed showed significant correlations with each other and with TSP concentration in fine particles, indicating that the particles in which they are contained have a similar behavior in the atmosphere.

• Journal of the Korean Geosynthetics Society
• /
• v.12 no.2
• /
• pp.13-23
• /
• 2013

The Korean Peninsula is considered as a seasonal frozen area that is thawed in the spring and frozen in the winter. The influence of fines of the frost susceptibility of subgrade soils were established by laboratory freezing tests simulating closely the thermal conditions in the field. During the winter season, the climate is heavily influenced by the cold and dry continental high pressure. Because of siberian air mass, the temperature of January is $-6{\sim}-7^{\circ}C$ on average. This chilly weather generate the frost heaving by freezing the moisture of soil and damage potential of the geotechnical structure. In the freezing soil, the ice lenses increase the freeze portion of soil by absorbing the ground water with capillary action. However, the capillary characteristics differ from the sort of soil on the state of freezing condition. In this study, ten soil samples are prepared. The basic physical property tests were performed by following the Korean Industrial Standard and the soil specimens were classified by the Unified Soil Classification System (USCS). These classified soils are used to perform the laboratory opened systems freezing test in order to determine the frost heaving characteristics of soils such as unfrozen water content, heaving amount, and freezing depth.

• Korean journal of applied entomology
• /
• v.56 no.4
• /
• pp.395-402
• /
• 2017

Overuse of synthetic pesticides caused negative side-effects such as environmental contamination, development of insect pests' resistance, and effects on non-target organisms. Plant origin substances without/or with low mammalian toxicity have been considered as promising alternatives to the synthetic pesticides. Fumigant toxicity of the essential oil of Iranian Yarrow, Achillea millefolium L., was investigated against a cosmopolitan stored-product insect pest: saw-toothed grain beetle (Oryzaephilus surinamensis L.). Chemical profile of this essential oil was studied by Gas Chromatography-Mass Spectrometry. Tested concentrations were significantly effective to the mortality of insect pest. A positive correlation between essential oil concentrations and pest mortality were realized. LC50 value (lethal concentration needed to 50% mortality) was achieved as $17.977(16.195{\pm}20.433){\mu}l/l$ air. The main components were 1,8-Cineole (13.17%), nerolidol (12.87%), ${\alpha}$-cubebene (12.35%), artemisia ketone (6.69%), ${\alpha}$-terpineol (5.27%), alloaromadendrene oxide (4.71%) and borneol (3.99%). Terpenic compounds including monoterpene hydrocarbons (8.19%), monoterpenoids (44.23%), sesquiterpene hydrocarbons (21.69%) and sesquiterpenoids (22.24%) were 96.35% of the total identified compounds. Results indicated that the terpene-rich A. millefolium essential oil may be considered as a safe bio-agent in the O. surinamensis management.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.30 no.2
• /
• pp.167-172
• /
• 2004

In the human skin, vitamin C (L -ascorbic acid) that is well known as the activated materials has effects that is skin anti-aging and wrinkle repair by giving impetus to collagen biosynthesis and anti-oxidation, and that is the sun screen, a wound recovering, inhibition melanogenesis and so on. In spite of its effects, vitamin C has the defects of the skin stimulation and easily oxidized instability by water, air, heat and light. For solving their matters, many investigation is advanced and its results are synthesized the various vitamin C derivatives. And yet they have not solved the unstable property of vitamin C and were still insufficient for the comparing with the effect of the pure vitamin C itself. In this study, in order to prepare vitamin C derivative of being improved the stability and to apply vitamin C effect in the skin, we prepared new vitamin C derivative, phytosphingosine ascorbate, by using phytosphingosine, one of sphingolipids, which have a distinguished skin affinity. Phytosphingosine ascorbate can be prepared as the ionic bond between amine group (-NH$_2$) of phytosphingosine and hydroxy group (-OH) of vitamin C by way of the relatively simple reaction. So the structure and properties of the synthesized phytosphingosine ascorbate was confirmed the use of elemental analysis (C 58.3 : H 9.3 : N 2.8 : O 29.5), MALDI TOF-MS (Mw=492.58), Ultraviolet spectra (268.5nm), lH NMR, FT-IR spectra, thermal analysis (m.p=l54$^{\circ}C$), HPLC and so on. And we could confirm the anti-bacterial and anti-oxidation effects. Based on these results, we could confirm to prepare a new material that was expected of both effects of vitamin C and phytosphingosine and that is improved properties of vitamin C.

• Journal of National Security and Military Science
• /
• s.4
• /
• pp.289-350
• /
• 2006

The world has been rapidly restructured in an agenda of national security from center of military strength to that of economic strength since the post cold-war era China military leadership-division carried out RMA through learning of a lesson from Gulf war in 1990 -1991 and Iraq war in 2003, thus the leadership-division made an attempt to convert the military system to a technical intensive system. The principle based on RMA of China military is (National defense strategy) drafted by the central military committee 1985 and (Four modernization general principles) 1978. China has introduced Russian high-technological arms and equipment in order to build up the military arms greatly thanks to an economical development, and they take pragmatism line as chinese socialism with their strategy to make secure a position as military powers such as they successfully launched a manned spacecraft and are building an air-craft carrie and soon. USA has a theory of dichotomy whether a country is a cooperator for USA, or not. and also enemy or friend since 9.11terror, thus USA is different from their direction of police. This is because USA stands a position as the superpower of the supremacy hegemony of the world. We must be carefully aware that USA considers as important area for Middle east, West south Asia, Central Asia and Northwest Asia to meet the demands of 2lcentury. Accordingly, the focus of USA's military strategy will be probably concentrated at the above mentioned four areas. On the other hand, USA enjoys such a superpower position due to collapse of USSR which was the past main enemy since the post cold war era. We could give an conclusive example as fact that USA has recurred to unilateralism But USA carry on the military operations to the terror groups at global around by converting thje military strike strategy to pre-emptive strike strategy since9.11 terror, 2001. USA seeks for transformation to the mobile military forces with light-quantity oriented in order to carry on such the military operations and makes progress GPR, And the USA forces in Korea makes progress a military renovation as part of such a military strategy. On the other hand, USA promotes the measures of choose for the countries standing at the crossroads of strategy and carries forward a main scheme of provision for four priority aims that the leaders of a hostile country and mis-country shall be prohibited from use and obtainment of weapons of mass destruction. Accordingly, this treatise found out a significant meaning to have an effect on the national security in the korean peninsula.

• Clean Technology
• /
• v.14 no.1
• /
• pp.53-60
• /
• 2008

The condensation heat transfer coefficients and pressure drops of hydrocarbon refrigerants (R-290 and R-600a) and hydrochlorofluorocarbon (HCFC) refrigerants were measured in the two horizontal double pipe heat exchangers with inner diameters of 10.07 mm and 5.80 mm at a mass flux of $35.5{\sim}210.4\;kg/m^2s$ and the condensation temperature of $40^{\circ}C$. The average condensation heat transfer coefficients of hydrocarbon refrigerants were higher than that of HCFC refrigerant(R-22). The pressure drop had a magnitude in the order of R-600a > R-290 > R-22. The pressure drops in the tubes with inner diameter of 10.07 mm were approximately $6{\sim}15%$, $9.8{\sim}12.5%$ and $2.1{\sim}4.6%$ higher for R-600a, R-290 and R-22, respectively, than those with inner diameter of 5.80 mm. The condensation heat transfer coefficients were compared with the published experimental data, and showed the best agreement with Haraguchi et al.'s correlation.

• Journal of Environmental Health Sciences
• /
• v.36 no.5
• /
• pp.343-350
• /
• 2010

This study was performed to investigate laboratory workers' exposures to airborne nanoparticles at a university laboratory where acid treatment experiments were conducted on the surfaces of engineered carbon nanotubes (CNTs). The surface area concentrations, number concentrations, and mass concentrations of airborne nanoparticles were measured at personal breathing zones (PBZs) for various tasks using direct reading instruments. For all three metrics, airborne nanoparticle concentrations during the experiments were higher than background levels measured before and after the experiments for all three metrics. Among the various tasks that were performed as part of these experiments, one task that involved filtering a mixture of acid and CNTs showed the highest concentrations in all three metrics, with concentrations of $116.6\;{\mu}m^2$/cc, 24320 pt/cc, and $9.0\;{\mu}g/m^3$, respectively. Nanoparticle surface area concentrations measured at a representative area fluctuated with those at the PBZs in the laboratory. This result indicates that nanoparticles generated during the experiments were not just limited to the PBZs of the workers but were also present throughout the room, potentially exposing co-located workers. CNTs were detected by a transmission electron microscope in an air sample collected while handling the CNTs. All the tasks were performed inside fume hoods, with the sliding sashes open to their required heights. It was noted that the capture velocities of the fume hoods were much lower than the American National Standards Institute (ANSI)'s recommendation level (0.4 to 0.6 m/s). In conclusion, this study showed that, due to inadequate control, laboratory researchers performing acid treatment experiments on surfaces of CNTs were exposed to airborne nanoparticles generated during the tasks.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.7 no.4
• /
• pp.287-294
• /
• 2019

GGBFS(Ground Granulated Blast Furnace Slag) has been widely used in concrete for its excellent resistance chloride and chemical attack, however cracks due to hydration heat and dry shrinkage are reported. In many International Standards, GGBFS with low fineness of 3,000 grade is classified for wide commercialization and crack control. In this paper, the mechanical and durability performance of concrete were investigated through two mix proportions; One (BS) has 50% of w/b(water to binder) ratio and 60% replacement ratio with low-fineness GGBFS, and the other (TS) has 50% of w/b and 60% replacement ratio with 4000 grade and FA (Fly Ash). The strength difference between TS and BS concrete was not great from 3 day to 91 day of age, and BS showed excellent performance for chloride diffusion and carbonation resistance. Two mixtures also indicate a high durability index (more than 90.0) for freezing-thawing since they contain sufficient air content. Through improvement of strength in low fineness GGBFS concrete at early age, mass concrete with low hydration heat and high durability can be manufactured.

• Economic and Environmental Geology
• /
• v.35 no.3
• /
• pp.273-284
• /
• 2002

The Gravity-Geologic Method (GGM) was implemented for bathymetric determinations in the Drake Passage, Antarctica, using global marine Free-air Gravity Anomalies (FAGA) data sets by Sandwell and Smith (1997) and local echo sounding measurements. Of the 6548 bathymetric sounding measurements, two thirds of these points were used as control depths, while the remaining values were used as checkpoints. A density contrast of 9.0 gm/㎤ was selected based on the checkpoints predictions with changes in the density contrast assumed between the seawater and ocean bottom topographic mass. Control depths from the echo soundings were used to determine regional gravity components that were removed from FAGA to estimate the gravity effects of the bathymetry. These gravity effects were converted to bathymetry by inversion. In particular, a selective merging technique was developed to effectively combine the echo sounding depths with the GGM bathymetiy to enhance high frequency components along the shipborne sounding tracklines. For the rugged bathymetry of the research area, the GGM bathymetry shows correlation coefficients (CC) of 0.91, 0.92, and 0.85 with local shipborne sounding by KORDI, GEODAS, and a global ETOPO5 model, respectively. The enhanced GGM by selective merging shows imploved CCs of 0.948 and 0.954 with GEODAS and Smith & Sandwell (1997)'s predictions with RMS differences of 449.8 and 441.3 meters. The global marine FAGA data sets and other bathymetric models ensure that the GGM can be used in conjunction with shipborne bathymetry from echo sounding to extend the coverage into the unmapped regions, which should generate better results than simply gridding the sparse data or relying upon lower resolution global data sets such as ETOPO5.

• Korean Journal of Environmental Biology
• /
• v.31 no.4
• /
• pp.288-294
• /
• 2013

Recently, sustainable production of biofuel using algal biomass is being pursued because of its enormous potential. First and foremost, securing superior strains to develop an efficient production system for algal biodiesel through screening or genetic improvement of microalgae is necessary. The genus of Botryococcus is regarded as one of the superior microalgae for biodiesel production due to its ability to accumulate high amounts of lipids and hydrocarbons. However, its low growth rate is a bottleneck for large-scale production and commercialization. The purpose of this study is to obtain indigenous Botryococcus strains which possess high lipid content and biomass productivity. The Botryococcus sp. was isolated from the Seobu Reservoir in Jeju Island and identified as Botryococcus sudeticus J2 by comparative analysis of 18s rRNA gene and ITS regions. The biomass productivity and lipid content of B. sudeticus J2 were 0.116 g $L^{-1}day^{-1}$ and 40.1% of dry wt., respectively. This was higher than the value of B. braunii UTEX 572, which is widely regarded as a superior strain among Botryococcus species. The relatively high growth rate of B. sudeticus J2 was achieved under a light intensity of 240 ${\mu}mol$ photons $m^{-2}s^{-1}$ with ambient air spargingwhen compared to 120 ${\mu}mol$ photons $m^{-2}s^{-1}$ with 2% $CO_2$ supply. In summary, it is likely that the isolated B. sudeticus J2 can be used for the mass cultivation and biodiesel production.