• Ocean and Polar Research
• /
• v.30 no.4
• /
• pp.379-399
• /
• 2008

Spatial-temporal variations in physiochemical water qualities (temperature, salinity, DO, SPM, POC and nutrients) of surface and bottom waters were investigated along the mid-western coastal area (Taean Peninsula to Gomso Bay) of Korea. Spatial distribution patterns of temperature and salinity were mostly controlled by the physical mixing process of freshwater from Geum River and/or Gyunggi Bay with nearby coastal water. A strong tidal front is formed off Taean Peninsula during spring and summer. Seasonal variations in nutrient concentrations, lower in spring and summer and higher in fall and winter, are primarily regulated by magnitude of phytoplankton occurrence rather than freshwater loadings into the bay. Based on seasonal and spatial variability of physicochemical parameters, water quality of the study area can be divided into four water masses; Gyunggi Bay-influenced Water Mass (GBWM), Geum River-influenced Water Mass (GRWM), Yellow Sea Bottom Cold Water Mass (YSBCWM) and Cheonsu Bay Water Mass (CBWM). Water quality of the GBWM (Taean Peninsula coastal area), which has relatively low salinity and high concentrations of nutrients, is strongly controlled by the Gyunggi Bay coastal water, which is under influence of the Han River freshwater. In this water mass, the mixed layer is always developed by strong tidal mixing. As a result, a tidal front is formed along the offshore boundary of the mixed layer. Such tidal fronts probably play an important role in the distribution of phytoplankton communities, SPM and nutrients. The GRWM, with low salinity and high nutrients, especially during the flood summer season, is closely related to physiochemical properties of the Geum River. During the flood season, nutrient-enriched Geum River water mass extends up to 60 km away from the river mouth, potentially causing serious environmental problems such as eutrophication and unusual and/or noxious algal blooms. Offshore (<$30{\sim}40m$ in water depth) of the study area, YSBCWM coupled with a strong thermocline can be identified in spring-summer periods, exhibiting abundant nutrients in association with low temperature and limited biological activity. During spring and summer, a tidal front is formed in a transition zone between the coastal water mass and bottom cold water mass in the Yellow Sea, resulting in intensified upwelling and thereby supplying abundant nutrients to the GBWM and GRWM. Such cold bottom water mass and tidal front formation seems to play an important role in controlling water quality and further regulating physical ecosystem processes along mid-western Korean coastal area.

• Journal of the Korean Wood Science and Technology
• /
• v.44 no.3
• /
• pp.406-414
• /
• 2016

The lignin-based carbon nanofiber reinforced epoxy composite has been prepared by immersing carbon nanofiber mat in epoxy resin solution in order to evaluate the physical and mechanical properties. The thermal and mechanical properties of the carbon nanofiber reinforced epoxy composite were analyzed using thermogravimetric analysis (TGA), differential scanning calorimeter (DSC) and tensile tester. It was found that the thermal properties of the carbon nanofiber reinforced epoxy composite improved, with its glass-transition temperature ($T_g$) increased from $90.7^{\circ}C$ ($T_g$ of epoxy resin itself) to $106.9^{\circ}C$. The tensile strengths of carbon nanofiber mats made from both lignin-g-PAN copolymer and PAN were 7.2 MPa and 9.4 MPa, respectively. The resulting tensile strength of lignin-based carbon nanofiber reinforced epoxy composite became 43.0 MPa, the six times higher than that of lignin-based carbon nanofiber mats. The carbon nanofibers were pulled out after the tensile test of the carbon nanofiber reinforced epoxy composite due to high tensile strength (478.8 MPa) of an individual carbon nanofiber itself as well as low interfacial adhesion between fibers and matrices, confirmed by the SEM analysis.

• Economic and Environmental Geology
• /
• v.40 no.1 s.182
• /
• pp.47-66
• /
• 2007

The Sitting Buddha Carved on Rockcliff (National treasure No. 201) in Bukjiri consists of porphyritic biotite granite, which was fractured by three joint sets of NE-SW, EW and NS directions. They produced a physical weathering that broke many parts of the Buddha and background. The chemical index of alteration is 59 to 61 from the major elements in the granite that was weathered into producing kaolin minerals from alteration of feldspars and biotite. With weathering degree, major element compositions increase in $SiO_2$ and MnO, whereas decrease in $TiO_2,\;{Fe_2O_3}^t,\;MgO,\;CaO\;and\;K_2O$. Change proporations of trace elements to $Al_2O_3$ increase in all transition elements, Rb and Y, whereas decrease in Li, Sr and Ba. REE pattern increases only in HREE. Particularly, a decrease in CaO, $K_2O$, Sr and Ba results in what they are effluxed to dissolve from feldspars by groundwater. The Buddha image has been deteriorated into joints, color changes, brown rusts, granular decay, microorganic smears by the such weathering causes as deformation, moisture, temperature variation and microorganic living. The moisture, which leaks along the joints in the granite, not only dissolve to decompose minerals but also grows many microorganism and is frozen over during winter. NE-SW and NS joint sets affect to seep in water during rainy days to deteriorate the image because they extend outward.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.44 no.7
• /
• pp.585-592
• /
• 2016

Visualization was done by using $CH^*$ chemiluminescence images and PMT measurements in order to understand the origin of fluctuating pressure and chemical luminosity at about 500 Hz frequency even in stable combustion, which was observed in recent experimental tests, and to find the physical correlation leading to Low Frequency Instability(LFI) in terms of phase angle. In stable combustion, chemical reactions are distributed along the shear layer flow showing a negative coupling(about 180 degree in phase angle) with combustion pressure. However, phase difference is shifted to a positive coupling showing less than 90 degree in unstable case. Also a periodic change in the distribution of chemical reactions is observed along with local flame extinction and the appearance of big scale vortex flow. In the transition to LFI, local flame extinction and small vortex flow start to appear in a row. As seen in the bluff body wake in reactive flow, the periodic appearance of vortex flow seems to share the same physical process of BVK(Bernard Von Karman) instability generation. Thus, the appearance of local extinction in 500 Hz fluctuations is gradually amplified to complete extinctions of about 20 Hz, and it leads into LFI.

• Elastomers and Composites
• /
• v.46 no.3
• /
• pp.211-217
• /
• 2011

Wood Polymer Composite (WPC) has attracted a great deal of attention in environmental industries due to renewable resources, processability, excellent physical properties and logging regulations for application to housing units and engineering construction materials. In this study, commercial WPCs were prepared by using a modular intermeshing co-rotating twin screw extruder. The effect of three main factors such as wood flour contents, coupling agent concentrations and pre-treatment of wood flour on the properties of WPCs was extensively investigated. It was found that tensile strength and thermal stability were decreased with increasing wood flour contents whereas the water absorption was increased. Addition of maleic anhydride grafted polypropylene (PP-g-MA) into WPC exhibited better physical properties. On the contrary, the water absorption was slightly decreased with PP-g-MA. Finally the sample, which was prepared with pre-treated wood flour, represented the highest tensile strength. However, the water absorption of the sample was increased due to the transition of crystalline structure of cellulose.

• Korean Journal of Psychosomatic Medicine
• /
• v.5 no.1
• /
• pp.3-11
• /
• 1997

In becoming parents, the marital partners enter into a new developmental phase. The conception of the child is an act of mutual creativity during which the boundaries between the self and another were temporarily obliterated more completely than at any time since infancy. The infant is a physical fusion of the parents, and their personalities unite within the child. for many women, creativity as a mother becomes a central matter that provides meaning and balance to their lives. The husband usually has strong desires for an offspring and can be transformed by it. The child can profoundly affect one or both parents, and the influences are reciprocal-a child's needs or specific difficulties uncover a parent's inadequacy. following the child's development, each transition into a new developmental phase requires an adaptation by the parents, and one or another of these required adaptations may disturb a parent's equilibirium. And the personality changes, emotional difficulties, and regressions of a spouse that occur in response to some phase of parenthood can upset the marriage. Not only do children identify with parents, but parents also identify with their children. The parents take pleasure in child's joy and suffer with the child's pain more than in almost any other relationship. certain respects e parents lives again in the child. Through the process of identification the child can also provide one of the two parents with the opportunity to experience intimately the way in which a person of the opposite gender grows up. Parenthood also provides the opportunity to be loved, admired, and needed simply because one is a parent and, as such, a central and necessary object in the young child's life. The many potentialities for emotional satisfactions from parenthood manage to outweigh the tribulations and sacrifices that are required. The child also exerts an indirect effect through changing the parent's position in the society, for new sets of relationships are established as the parents are drawn to other couples with children of the same age, and for a new impetus toward economic and social mobility often possesses the parents. frequently the couple's relatedness to their own parents improves and grows firmer once again. Parenthood, the satisfactions it provides and the demands it makes, varies as life progresses : and changes with the parent's interests, needs, and age as well as with the children's maturation. There are phases in the child's life that the parents are reluctant to have pass, whereas they tolerate others largely through knowing that they will soon be over. The changing lives of the children provide many satisfactions that offset the tribulations, uncertainties, and regrets. The parents change. The young father, who was just starting on his carrier whom the first child was born, settles into a life pattern. He becomes secure with increasing achievement and interacts differently with the youngest child and provides a different model for him than for the oldest. The mother may have less time for a second or third child than for her first, but she may also be more assured in her handling of them. The birth of a baby when the parents art in their late thirties will find them Less capable of physical exertion with the child and less tolerant of annoyances, but they are less apt to be annoyed. Eventually the children min and leave home, but the couple do not cease to be parents.

• Korean Journal of Food Science and Technology
• /
• v.37 no.1
• /
• pp.30-37
• /
• 2005

To mass-produce useful biopolymer films, chitosan/gelatin blend films were prepared by solution casting method. Effects of mixing ratio, tensile strength (TS), elongation (E) at break, total color difference (${\Dalta}E$), opacity, water vapor permeability (WVP), oxygen permeability (OP), and thermal properties on chitosan/gelatin blend films properties were investigated. TS, E, ${\Dalta}E$, opacity, WVP, and OP values were 58.24-22.01 MPa, 13.11-24.67%, 1.86-17.45, 0.3104-1.2161 nmO.D./${\mu}m$, $1.6875-1.7225ng{\cdot}m/m^{2}{\cdot}s{\cdot}Pa$, and $2.2380{\times}10^{-7}-2.2975{\times}10^{-7}\;mL{\cdot}{\mu}m/m^{2}{\cdot}s{\cdot}Pa$, respectively. TS of blend films decreased, while E, ${\Dalta}E$, and opacity increased with increasing chitosan content. WVP of blend films did not show any significant relationship with mixing ratio and thickness of blend films. Miscibility of films was examined over entire composition range by thermogravimetric analyzer (TGA) and dynamic mechanical analyzer (DMA). TGA results showed gelatin is more thermally stable than chitosan and some interactions among functional groups of two biopolymers. Glass transition temperature $(T_{2})$ of films as determined by DMA decreased with increasing content of chitosan in the blend. Results of thermal analysis indicate high miscibility among polymer components in the blend.

• Clean Technology
• /
• v.24 no.1
• /
• pp.9-14
• /
• 2018

In this study, Material life cycle evaluation was performed to analyze the environmental impact characteristics of TiN-Zr membrane manufacturing process. The software of MLCA was Gabi. Through this, environmental impact assessment was performed for each process. Transition metal nitrides have been researched extensively because of their properties. Among these, TiN has the most attention. TiN is a ceramic materials which possess the good combination of physical and chemical properties, such as high melting point, high hardness, and relatively low specific gravity, high wear resistance and high corrosion resistance. With these properties, TiN plays an important role in functional materials for application in separation hydrogen from fossil fuel. Precursor TiN was synthesized by sol-gel method and zirconium was coated by ball mill method. The metallurgical, physical and thermodynamic characteristics of the membranes were analyzed by using Scanning Electron Microscope (SEM), Energy Dispersive X-ray (EDS), X-ray Diffraction (XRD), Thermo Gravimetry/Differential Thermal Analysis (TG/DTA), Brunauer, Emmett, Teller (BET) and Gas Chromatograph System (GP). As a result of characterization and normalization, environmental impacts were 94% in MAETP (Marine Aquatic Ecotoxicity), 2% FAETP (Freshwater Aquatic Ecotoxicity), 2% HTP (Human Toxicity Potential). TiN fabrication process appears to have a direct or indirect impact on the human body. It is believed that the greatest impact that HTP can have on human is the carcinogenic properties. This shows that electricity use has a great influence on ecosystem impact. TiN-Zr was analyzed in Eco-Indicator '99 (EI99) and CML 2001 methodology.

• Journal of Adhesion and Interface
• /
• v.17 no.2
• /
• pp.49-55
• /
• 2016

In this study, we designed an environment friendly, water-based adhesive using the acrylic emulsion method as a replacement for solvent-based adhesives, which are most commonly used in layered laminates for flexible food packaging. We designed adhesives with different combinations of anionic, non-ionic, and phosphoric ester surfactants, and with different concentrations of chain transfer agent (CTA). We also examined the effect of the degree of cross-linking by synthesizing and comparing 8 test group adhesives with different types of functional monomers. Additionally, we synthesized 2 other test group pressure-sensitive adhesives (PSA) using styrene/alpha-methyl styrene/acrylic acid (SAA) semipolymer dispersing agents (with molecular weights of 13,000 g/mol and 8,600 g/mol, respectively) to replace the conventional surfactants. We evaluated whether the 10 test group pressure-sensitive adhesives met the basic physical property criteria required for flexible food packaging by carrying out a physical analysis of their glass transition temperature (Tg), particle size, adhesion, and molecular weight. In our test, 2 test group adhesives manufactured with the combination of anionic and non-ionic surfactants, CTA concentration of 0.2%, and functional monomers of hydroxyethyl acrylate (HEA) and glycidyl methacrylate (GMA) demonstrated molecular weight and flexibility suitable for flexible packaging, with low adhesiveness and small particle size.

• Journal of Korean Society of Forest Science
• /
• v.101 no.1
• /
• pp.148-157
• /
• 2012

Korea, with 63.7% of the land being forests, has unique characteristics of forest landscapes coming into view for most residential areas and roads. This study was undertaken with a purpose of supporting forest landscape management by partitioning the areas that landscape management is needed. Through analysing the degree of forest landscape management needs and the visual absorption capability for landscape changes, the zoning process and method for landscape management were conducted. In order to select the areas that are managed by priority for landscape, the degree of forest landscape management needs was quantitatively analyzed with the main scenic sites, travel frequencies, major forest landscape resources, and areas with demand for walking and automobile travel as the basis. The visual absorption capability that means the visual acceptance capability against physical landscape changes of the designated areas was analyzed in order to select the areas that are suitable for artificial landscape management. As a result, it became possible to express the degrees of forest landscape management needs in high, middle, and low sub-areas, and the visual absorption capability in high, middle, and low sub-areas, for each of the three zones in terms of spaces in the forest landscape management areas. For example, among the forest landscape transition zones, if the degree of forest landscape management needs is high and the visual absorption capability is high, then aggressive landscape management would be possible; this would also mean that this area could accept certain levels of physical landscape changes. By applying zoning methods like these, it was possible to attain a conclusive result that proper means of landscape design and management of the forest landscape resources and the surrounding areas could be provided.