• Journal of the Korean Society of Radiology
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• v.13 no.2
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• pp.261-270
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• 2019

The separation permeation characteristics of $N_2-O_2$ gas in air at cell membrane model of skin which irradiated by high energy electron(linac 6 MeV) were investigated. The cell membrane model of skin used in this experiment was a sulfonated polydimethyl siloxane(PDMS) non-porous membrane. The pressure range of $N_2$ and $O_2$ gas were appeared from $1kg_f/cm^2$ to $6kg_f/cm^2$. In this experiment(temperature $36.5^{\circ}C$), the permeation change of $N_2$ and $O_2$ gas in non-porous membrane by non-irradiation were found to be $1.19{\times}10^{-4}-2.43{\times}10^{-4}$, $1.72{\times}10^{-4}-2.6{\times}10^{-4}cm^3(STP)/cm^2{\cdot}sec{\cdot}cmHg$, respectively. That of $N_2$ and $O_2$ gas in non-porous membrane by irradiation were found to be $0.19{\times}10^{-4}-0.56{\times}10^{-4}$, $0.41{\times}10^{-4}-0.76{\times}10^{-4}cm^3(STP)/cm^2{\cdot}sec{\cdot}cmHg$, respectively. The irradiated membrane was significantly decreased about 4-10 times than membrane which was not irradiated. And ideal separation factor of $N_2$ and $O_2$ gas by non-irradiation was found to be from 1.32 to 0.42 and that of $N_2$ and $O_2$ gas by irradiation was found to be from 0.237 to 0.125. The irradiated membrane was significantly decreased about 4-5 times than membrane which was not irradiated. When the operation change(cut) and pressure ratio(Pr) by non-irradiation were about 0, One was increased to the oxygen enrichment and the other was decreased to the oxygen enrichment. The irradiated membrane was significantly decreased about 4-19 times than membrane which was not irradiated. As the pressure of $N_2$ and $O_2$ gas was increased, the selectivity was decreased. As separation permeation characteristics of $N_2-O_2$ gas in cell membrane model of skin were abnormal, cell damages were appeared at cell.

• Korean Journal of Agricultural Science
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• v.41 no.4
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• pp.321-326
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• 2014

The aim of this study was to investigate which hydroponic system is the optimum for growth and photosynthetic characteristics of Angelica gigas during experiment. Angelica gigas 'Manchu' were sowed and managed under a growth room chamber. The environmental conditions (temperature $22^{\circ}C/18^{\circ}C$ (day/night), relative humidity 50-70%, photosynthetic photon flux density (PPFD) $120{\pm}6{\mu}mol\;m^{-2}s^{-1}$) were maintained for 3 weeks. Forty eight seedlings with 4-5 leaves were transplanted in deep flow technique (DFT), substrate, and spray culture systems [culture bed: 800 (L) ${\times}$ 800 (W) ${\times}$ 400 mm(H)] under $150{\pm}5{\mu}mol\;m^{-2}s^{-1}$ PPFD provided with fluorescence lamps and cultivated for 11 weeks. At the end of the experiment, fresh and dry weights, leaf lenghth and width, SPAD, root fresh, and dry weights, and root volume of Anglica gigas were measured. Photosynthetic rate of Anglica gigas were measured with portable photosynthesis systems to investigate optimum PPFD, $CO_2$ concentration, and air temperature conditions. Fresh and dry weights of Anglica gigas grown in substrate were significantly greater than DFT-treated, but there were not significant with spray treatment. Leaf photosynthesis of Anglica gigas showed the tendency to sharply increase as PPFD was increased from 50 to $200{\mu}mol\;m^{-2}s^{-1}$. Though $CO_2$ saturation point was around $1000-1200{\mu}mol\;mol^{-1}$, increase in air temperature from 16 to $26^{\circ}C$ did not quite affect photosynthesis of Anglica gigas. In conclusion, Anglica gigas may be optimally cultivated with a spray culture system as air temperature, PPFD, and $CO_2$ concentration for environment are controlled at $20{\pm}3^{\circ}C$, $150{\mu}mol\;m^{-2}s^{-1}$, and around $1000{\mu}mol\;mol^{-1}$ for mass production.

• Economic and Environmental Geology
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• v.42 no.4
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• pp.315-333
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• 2009

In this study, the hydrochemical and the isotopic characteristics of major streams in the Daejeon area were investigated during rainy and dry seasons. The stream water shows the electrical conductivity of the range of $37{\sim}527{\mu}s$/cm, and pH $6.21{\sim}9.83$. The chemical composition of stream waters can be grouped as three types: the upper streams of Ca(Mg)-$HCO_3$ type, Ca(Mg)-$SO_4(Cl)$ type of middle streams flowing through urban area, and Na(Ca)-$HCO_3$(Cl, $SO_4$) type of the down streams. Based on in-situ investigation, the high pH of stream waters flowing through urban area is likely to be caused by the inflow of a synthetic detergent discharging from the apartment complex. The electrical conductivity of stream waters at a dry season is higher than those of at a rainy season. We suggest that the hydro-chemical composition of stream waters in the Daejeon area was affected by the discharging water from the sewage treatment facilities and anthropogenic contaminants as well as the interaction with soil and rocks. ${\delta}D$ and ${\delta}^{18}O$ values of the stream waters show the relationship of ${\delta}D=6.45{\delta}^{18}O-7.4$, which is plotted at a lower area than global meteoric water line(GMWL) of Craig(1961). It is likely that this isotopic range results from the evaporation effect of stram waters and the change of an air mass. The isotope value shows an increasing trend from upper stream to lower stream, that reflects the isotopic altitude effect. The relationship between ${\delta}^{13}C$ and $EpCO_2$ indicates that the carbon as bicarbonate in stream water is mainly originated from $CO_2$ in the air and organic materials. The increasing trend of ${\delta}^{13}C$ value from upper stream waters to lower stream waters can be attributed to the following reasons: (1) an increasing dissolution of $CO_2$ gas from a contaminated air in downtown area of the Daejeon, and (2) the increment of an inorganic carbon of groundwater inflowed into stream by base flow. Based on the relationship between ${\delta}^{34}S$ and $SO_4$ of stream waters, the stream waters can be divided into four groups. $SO_4$ content increases as a following order: upper and middle Gab stream${\delta}^{34}S$ value decreases as above order. ${\delta}^{34}S$ value indicates that sulfur of stream waters is mainly originated from atmosphere, and is additionally supplied by pyrite source according to the increase of sulfate content. The sulfur isotope analysis of a synthetic detergent and sewage water as a potential source of the sulfur in stream waters is furtherly needed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.2
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• pp.197-206
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• 2023

Recently, the international community, including the International Maritime Organization (IMO), has strengthened regulations on air pollution emissions of ships, and eco-friendly ships are actively being developed to reduce exhaust gas emissions. Among them, rotor sail (RS), a wind-assisted ship propulsion system, is attracting attention again. RS is a cylindrical device installed on the ship deck, that generates hydrodynamic lift using a magnus effect. This is a next generation eco-friendly auxiliary propulsion technology, and Enercon company, which developed RS-applied ships, announced that fuel savings of more than 30% are possible. In this study, optimal installation conditions such as RS spacing and arrangement type were selected when multiple RSs were installed on ships. AR=5.1, SR=1.0, and D_e/D was fixed at 2.0 according to the RS arrangement, and the wind direction was considered only for the unidirectional +y-axis. Regarding arrangement conditions, five conditions were set at 3D intervals in the +x-axis direction from 3D to 15D and five conditions in the +y-axis direction from 5D to 25D. C_L, C_D and aerodynamic efficiency (C_L/C_D) were compared according to the square(□) and diamond(◇) shape arrangements. Consequently, the effect of RS on the longitudinal distance was not significantly different. However, in the case of RS flow characteristics according to the transverse distance, the interaction effect of RS was the greatest when the two RSs almost matched the wind direction. In the case of the RS flow characteristics according to the arrangement, notably, when the wind blew in the forward (0°) direction, the diamond (◇) arrangement was least affected by the backward flow between RSs.

• Journal of the Korean Society of Radiology
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• v.11 no.5
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• pp.297-302
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• 2017

Recently, building materials and air purification filters with eco-friendly charcoal are actively studying to reduce the concentration of radon gas in indoor air. In this study, radon reduction performance was assessed by designing and producing new panel-type activated carbon filter that can be handled more efficiently than conventional charcoal filters, which can reduce radon gas. For the fabrication of our panel-type activated carbon filter, first the pressed molding product after mixing activated carbon powder and polyurethane. Then, through diamond cutting, the activated carbon filter of 2 mm, 4 mm and 6 mm thickness were fabricated. To investigate the physical characteristics of the fabricated activated carbon filter, a surface area and flexural strength measurement was performed. In addition, to evaluate the reduction performance of radon gas in indoor, the radon concentration of before and after the filter passes from a constant amount of air flow using three acrylic chambers was measured, respectively. As a result, the surface area of the fabricated activated carbon was approximately $1,008m^2/g$ showing similar value to conventional products. Also, the flexural load was found to have three times higher value than the gypsum board with 435 N. Finally, the radon reduction efficiency from indoor gas improved as the thickness of the activated carbon increases, resulting in an excellent radon removal rate of more than 90 % in the 6 mm thick filter. From the experimental results, the panel-type activated carbon is considered to be available as an eco-friendly building material to reduce radon gas in an enclosed indoor environment.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.3
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• pp.202-210
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• 2013

As incomes increase, interest in ocean leisure picks up. As a result, a lot of research and developments on hull form design and production of planing boats, mostly used for ocean leisure, are needed. Analysis in researches on resistance of planing boats shows that resistance characteristic of planing boats is different from resistance characteristic of general boats because the former is fast, and its wetted surface is very small. Using Savitsky formula widely used in the calculation of effective horse power in shipbuildingyards, and propulsion system and engine manufacturers, this study calculated total resistance of a research planing boat. Then it analyzed the flow characteristics of the planing boat through theoretical analysis and wind tunnel experiment, and computed air resistance and lift force by changes of speed and trim angle. It also compared and analyzed result of theoretical analysis and experiment of the ratio of air resistance to total resistance under variations of velocity and trim angle. When the study is used to estimate more accurate effective horse power, it is expected to remedy abuses of unnecessarily installing high-powered engine. As nature disasters due to abnormal changes of weather increase, interest in greenhouse gas grows. International Maritime Organization (IMO) legislated Energy Efficiency Design Index (EEDI) and Energy Efficiency Operational Indicator (EEOI) to reduce ship greenhouse gas emissions. But this index will be applied to over 400 tons ships, small ships, emitting more greenhouse gases than larege ships per unit power, will dodge the regulations. Thus, this study indicated a problem by calculating greenhouse gas emissions of an ocean leisure planning boat (a small ship), and suggested the need for EEDI of small ships.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.4
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• pp.156-161
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• 2020

Recently, as there has been growing demand for aesthetic quality in structural materials, the development of excellent color cement concrete having good coloration properties has become a requirement. This study is designed to analyze the basic physical properties of mortar and the properties of keeping the coloration under an ultraviolet ray accelerated weathering test environment according to changes in the mixing ratio between carbon black and iron oxide used as colorants. The test results show that the use of carbon black and iron oxide reduces the initial flow by 6.3~17.2 % and the air content by 3.5~31.5 % but increases the unit volume weight by 3.4~5.5 %, compared to ordinary Portland cement (OPC). In addition, the study shows that the addition of iron oxide increases the self drying shrinkage. So, caution needs to be taken on the workability of the concrete. The brightness value L^⁎ represented by black showed the most excellent black colour when carbon black 3 % and iron oxide 5 % are added. According to UV accelerated weatherproof test, the brightness value L^⁎ was found to increase in all experiment specimens by 4.28~11.97 %, and the color change by UV was found to be higher for the case where carbon black colorant was not used. Therefore, in terms of color revelation characteristics, the case using carbon black 3 % and iron oxide 5 % was found to show the best black color.

• Journal of architectural history
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• v.20 no.2
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• pp.7-22
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• 2011

This study primarily aims to illuminate the characteristics of $Meoreum$ in Korean traditional fitting system according to the respective types and its periodical changes. Using the research findings as a chronological indicator by which to estimate the construction date of the building is the secondary purpose. In this study 42 of $Byeoldang$ and pavilion architecture remaining in $Yeongnam$ district were examined through the field surveys and methods of documentary research. The research results are as follows. First, $Meoreum$, which is located below the windows or doors, provides protection against the outer wind and has the function to prevent some warm air of the room from flowing outside. Second, $Meoreum$ was recorded as $Yoeum$(了音), $Woneum$(遠音), and $Maleum$(末音) in $Yeong-geon-ui-gwe$(營建儀軌) of Joseon period. While $Yoeum$(了音) was used in $Yeong-geon-ui-gwe$(營建儀軌) of 1776 and 1856, $Woneum$(遠音) had been also used continuously since the year of 1800. The word, $Maleum$(末音) can be seen in $Lim-won-gyeong-je-ji$(林園經濟志), published in 1827. $Woneum$(遠音) and $Maleum$(末音) seem to be the $Yi-du$(吏讀) types of expression of $Meoreum$ which is being extensively used now. Third, the kinds of $Meoreum$ can be classified as $TohMeoreum$, $TongMeoreum$, $TongpanMeoreum$, and $JjaneunMeoreum$. $TongMeoreum$ and $TohMeoreum$ were mostly used at the front part of $Ondol-rooms$, the backside of main floor called $Daechung$(大廳), and at the space between $Daechung$ and rooms in the Pavilions and $Byeoldangs$(Annexes) that had been built in the early Joseon dynasty. $TohMeoreum$ was usually used at the bottom parts of windows between $Daechung$ and $Ondol-rooms$. $TongpanMeoreum$ was mainly used in the mid-Joseon period and relatively high height was the distinctive feature of $Meoreum$ at that time. $Jjaneun$ $Meoreum$, used mainly in the late Joseon dynasty, has become lower and lower gradually in height since 19th century, so people could enter the room through the windows(fittings). Such changes in $Meoreums$ types has brought about the flow of human traffic directly from $Toenmaru$, narrow wooden porch running along the outside of a room to $Ondol-rooms$.

• Clean Technology
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• v.23 no.1
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• pp.80-89
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• 2017

The bubbling fluidized bed (BFB) reactor with a diameter of 0.1 m and a height of 1.2 m was used for experimental study of co-firing and emission characteristics fueled by sewage sludge (SS) and wood pellet (WP). The facility consists of a fluidized bed reactor, feeding system, cyclone, condenser and gas analyzer, The mean particle diameter and minimum fluidization velocity are $460{\mu}m$ and $0.21ms^{-1}$ respectively. SS produced from Korea and WP from Canada were examined. The various mixing ratios of WP were 20, 50, and 80% based on HHV. The equivalence ratio of 1.65, reactor temperature of $800^{\circ}C$, air flow rate of $100Lmin^{-1}$, and fluidization number of 4 were fixed in the BFB experiment. In TGA, the range of combustion temperature of SS was wider than that of WP. It represents that the combustibility of WP is higher than that of SS. The BFB reactor temperature was maintained between 800 and $900^{\circ}C$. CO emission of SS was high because of lower combustibility. $NO_X$ and $SO_X$ formation of SS were higher than that of WP since high nitrogen and sulfur contents of SS. CO, $NO_X$, and $SO_X$ formation were suppressed as the mixing ratio of WP was increased. The slagging and fouling tendencies show high in all test conditions.

• Journal of Energy Engineering
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• v.24 no.2
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• pp.120-128
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• 2015

This study reports the combustion characteristics, such as burner temperature and the concentration of exhausted gas ($O_2$, $CO_x$, $NO_x$) due to the different types and pitches of the fuel supply feeder of the wood pellet boiler. The 1st grade wood pellets composed of mainly larch have been used for the experiment. In case of using the spring feeder, mean temperature of burner was approximately $821.76^{\circ}C$, and the mean concentration of oxygen, carbon monoxide, carbon dioxide and nitrogen oxide were approximately 8.88%, 93.35ppm, 12.15% and 139.83 ppm, respectively. The test result with the spring feeder was shown to approach the condition of complete combustion compared to that of a screw feeder and were in good agreement with authentication judgement standard. Furthermore, the combustion efficiency was improved according to the growth of screw pitch. The control of air flow rate from the blower and ventilator is needed to achieve the complete combustion.