• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.1
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• pp.21-28
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• 2006

Since the usage of tributyltin(TBT) has been banned, many chemicals including Sea-Nine 211, Cu-pyrithione, and Zn-pyrithione were developed to use as antifouling agents for ships and coastal structures. However, the toxicity of these antifouling chemicals have not been systematically evaluated in ecotoxicological and biological studies. In this study, we investigated the effect of four antifouling substances on survival of estuarine rockfish, Sebastes schlegeli and amphipod, Monocorophium acherusicum. Survival of S. schlegeli and M. acherusicum during the 96-h exposure period were used to estimate the median lethal concentrations(LC50s) of test chemicals for each test species. Among antifouling agents, Cu-pyrithione($56{\mu}g{\cdot}1^{-1}$;96-h LC50) was most toxic to S. schlegeli, followed by $TBT(73{\mu}g{\cdot}1^{-1}),\;Sea-Nine(184{\mu}g{\cdot}1^{-1})\;and\;Zn-pyrithione(l707{\mu}g{\cdot}1^{-1})$, while TBT($26{\mu}g{\cdot}1^{-1}$) was most toxic to M. acherusicum followed by Sea-Nine($49{\mu}g{\cdot}1^{-1}$), Cu-pyrithione($119{\mu}g{\cdot}1^{-1}$) and Zn-pyrithione($334{\mu}g{\cdot}1^{-1}$). Effect concentrations of the antifouling chemicals estimated in this study can be used when assessing the potential risks of these substances, of which usage is increasing in the coastal environment.

• Journal of Bio-Environment Control
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• v.25 no.4
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• pp.225-231
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• 2016

Glasshouse heating package technologies to improve energy usage efficiency in winter were developed. Heating package was composed of the ground water source heat pump with heating capacity of 105kW, the aluminum multi-layer thermal curtain with six layers of different materials and the root zone local heater with XL pipes of ${\phi}20mm$. Venlo type glasshouse($461m^2$) with the heating package was compared with the same type and area control glasshouse with the light oil boiler, the usual non-woven fabric thermal curtain with respect to the glasshouse inside temperature, relative humidity, crop growth, and heating energy consumption. The results of test in paprika cultivation glasshouses showed that the air temperature inside glasshouse with aluminum multi-layer thermal curtain was maintained $2.2^{\circ}C$ higher than that of control glasshouse in un-heating night time and the temperature in bed with root zone local heating was $4.7^{\circ}C$ higher than that in bed without local heating. Average heating coefficient of performance(COP) of the ground water source heat pump used in paprika cultivation was 3.7 and the glasshouse inside temperature was maintained at $21^{\circ}C$ of heating set up temperature. The heating energy consumptions per 10a were measured at 14,071L of light oil and 364kWh of electric power for the control glasshouse and 35,082kWh for the glasshouse applied heating package. As results, the heating cost of the glasshouse applied heating package was 87 percent lower than that of control glasshouse. The growths of paprika in glasshouses of control and applied heating package did not show any significant difference.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.8
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• pp.588-595
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• 2014

Carbon nanomaterials such as fullerene, carbon nanotube and graphene are representative nanomaterials and widely used in various fields. Carbon nanomaterials can be exposed to environments during their production, usage and disposal, spreading to different systems and posing a great threat to various ecological receptors. Researches are conducted in order to determine the possibility of groundwater exposure to carbon nanomaterials due to their release and passage through soils. If soils can play a significant role in limiting the transport of carbon nanomaterials, the possibility of groundwater exposure to carbon nanomaterials can be reduced greatly. This review paper presented the research works performed for the mobility of carbon nanomaterials in soil media. Also, the paper provided the factors affecting the transport of carbon nanomaterials in soil media along with the DLVO theory/colloid filtration theory/transport model, which are used to describe the transport of carbon nanomaterials in soil media. Recently, production of carbon nanomaterials and their commercial and environmental applications increase rapidly in Korea. Therefore, researches regarding the fate and transport of domestic carbon nanomaterials in soil environments should be performed in various environmental conditions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.11
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• pp.581-586
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• 2015

In this study, an analysis was performed on the performance of the solar water heating system with geo-thermal heat pump for a detached house. This system has a flat plate solar collector ($8\;m^2$) and a 3 RT heat pump. The heat pump acts as an auxiliary heater of the solar water heating system. These systems were installed at four individual houses with the same area of $100\;m^2$. The monitoring results for one year are as follows. (1) The average daily operating time of the solar system appeared to be 313 minutes in spring (intermediate season), and 135 minutes and 76 minutes in winter and summer respectively. The reason for the short operating time in summer is the high storage temperature due to low water heating load. The high storage temperature is caused by a decrease in collecting efficiency as well as by overheating. (2) The geothermal heat pump as an auxiliary heater mainly operates on days of poor insolation during the winter season. (3) Despite controlling for total house area, hot water consumption varies greatly according to the number of people in the family, hot water usage habits, etc. (4) The yearly solar fraction was 69.8 to 91.5 percent, which exceeds the maximum value of 80% as recommended by ASHRAE. So the solar collector area of $8\;m^2$ appeared to be somewhat greater for the house with an area of $100\;m^2$. (5) The observed annual efficiency of solar systems was relatively low at 13.5 to 23.6%, which was analyzed to be due to the decrease in thermal efficiency and the overheating caused by a high solar fraction.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.3
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• pp.131-139
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• 2014

Infra-gravity waves (IGWs) with a period of 1~3 minutes are a factor that directly influences the motion analysis of moored ships inside a harbor and longshore sediment transport analysis. If significant levels of IGWs from far seas are transferred to a harbor and amplified, they may cause downtime of large ships and induce economic loss. In this study, transfer characteristics of the IGWs intruding from outside to inside Pohang New Harbor were analyzed using statistical analysis and transfer function of wave data measured at both outside and inside the harbor for around 5 years. Transfer characteristic analysis was limited to events where IGWs had wave heights above 0.1 m. The wave height distribution of inside the harbor was similar to that of outside the harbor, while the wave period variance of the former was larger than that of the latter. The parameters of the transfer function was optimally estimated according to each event. The estimated average RMS error of the wave height inside the harbor was around 0.013 m. The estimated parameters had a strong correlation with the linear combination information of IGW wave height, period, and direction (R = 0.95). The transfer function suggested in this study can quickly and easily estimate information on IGWs inside the harbor using IGW information predicted beforehand, and is expected to reduce damage due to unexpected restrictions on harbor usage.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.6
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• pp.379-386
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• 2008

Calcined clay granules (pellet) have been used as a soil conditioner. The space among the pellets can secure drainage of water in soil and, simultaneously, can keep water for plants in the inner pore of that. However, the usage of the pellet has been restrained because fabrication of that requires a high energy and cost for heating over the temperate of $1000^{\circ}C$. Recently, SCS(Self-propagating Combustion and Sintering) method was developed and this method use the combustion energy of the preliminary mixed combustible. The SCS method is suitable to fabrication of small porous aggregate and requires a very low cost. This research applied the SCS method to coal refuses for fabrication of soil conditioner pellets. The coal refuses were pulverized under the size of $100{\mu}m$ and the pulverized powders were pelletized to the size of 4~6mm. The pellets were heated at the temperature of $1200^{\circ}C$ in the SCS furnace that was specially prepared for this research. Characteristics of the pellets were investigated and were compared with that of ordinary calcined clay pellet of kaolin; porosity, pore size distribution, bulk density, pH and etc.. Characteristics of the moisture retention in the pellets were measured by the centrifugal method: ASTM D425-88. The pellets of the coal refuses showed the higher values of the field capacity and the plant-available water than that of kaolin pellet. These results suggest the very low cost process that can utilize the coal refuses and can fabricate the lightweight porous soil conditioner of the very high plant-available water.

• Journal of Energy Engineering
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• v.15 no.1 s.45
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• pp.52-59
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• 2006

This paper examined the conversion of methane to hydrogen and other higher hydrocarbons using dielectric barrier discharge with AC pulse power. Two metal electrodes of a coaxial-type plasma reactor were separated by gas gap and an alumina tube. The inner electrode was located inside the alumina tube. The alumina tube was located inside the stainless steel tube, which was used as the outer electrode. Effect of feed gas composition (methane, oxygen, argon, water and helium), flow rate, applied frequency, input volt-age on methane conversion and product distribution were studied. The major products of plasma chemical reactions were ethylene, ethane, propane, buthane, hydrogen, carbon monoxide and carbon dioxide. The increment of applied voltage and the usage of inert gas as the background (helium and argon) enhanced the selectivity of hydrocarbons and methane conversion. The addition of water in the feed stream enhanced the conversion of methane and yield of hydrogen. Higher voltage leads to higher yield of $C_2H_6,\;C_3H_8,\;C_4H_{10}$ and yield or $C_2H_2\;and\;C_2H_4$ appeared highly in lower voltage.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.1
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• pp.42-45
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• 2008

It has been reported that FRP (fiber reinforced plastic) can be recycled by separating into layers instead of crushing into powder. F-fiber obtained from roving layer separated from FRP, has bigger tensile strength than the bundle of glass fibers of which FRP was made (more than 90%). SEM image of F-fiber shows the presence of some resin. Under the proposition of usage of F-fiber in the concrete material, tensile strength is examined after soaking in a basic solution (NaOH+KOH). The reaction mechanism of strength loss may be considered as an attack of hydroxide ion ($OH^-$) on a chemical bond of Si-O-Si of glass fiber. The simulation graph of the strength loss data implies certain reaction mechanism. While in the early stage kinetically controlled reaction results in a fast drop of tensile strength, after 30 days dispersion rate of hydroxide ion plays a major role in strength loss. This result is similar to the one for the AR glass. An extrapolation of the graph would make an assumption about the lift time of F-fiber possible.

• Journal of Korea Foresty Energy
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• v.25 no.2
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• pp.1-8
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• 2006

The physical, mechanical and chemical properties of old and new Korean red pine (Pinus densiflora) were analyzed. The old woods were from dismantled timbers of Bonjungsa temple. The crystallized resin in the latewood was observed by microscopic analysis. Also, reduction of specific gravity, occurrence of microscopic cleavage of tracheid was observed in the old wood. The angle of microscopic cleavage of tracheid is estimated with the same angle of micro-fibril angle of 52 layer. The bending, compression and shear strength of old world were decreased about 35-27% than those of new wood. Dynamic modulus of elasticity measured by ultrasonic nondestructive test has the tendency of reducing by the time elapse of the wood usage. Therefore, deterioration of wood could be measured by reduction of specific gravity and dynamic MOE. The static MOE and mechanical properties of old wood could be predictable by measuring dynamic MOE in the longitudinal direction. Extractives of the old wood in 1-% NaOH solution are larger quantity than new wood. Therefore the decay of the wood could be evaluated by analyzing the chemical compound, especially 1-% NaOH solution. The results of this research could be used for understanding and prediction of the changing properties with elapsing time of wood.

• Spatial Information Research
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• v.20 no.1
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• pp.71-80
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• 2012

Carbon Point system is Climate Change Action Program by providing incentives in proportion to voluntary reduction of energy consumption such as electricity, gas and water for houses, commercial facilities. So far, existing researches have been limited to construction of GHG(Green House Gas) Inventory and have little attention to empirical impact analysis on carbon reduction policy regarding the residential section. Therefore, this paper is intended to provide convincing findings of impact analysis on carbon reduction, revolving around the carbon point system. For this, we firstly calculated the carbon emission by using electricity and gas usage data in household targeting to Seongbuk-Gu. Carrying out IPA and spatio-temporal analysis. Then, we are capable of visualizing spatial patterns from 2007 to 2009 as a macro analysis. Following that, we explored the effect on carbon point system through Ex ante-Ex post Analysis by paired t-test. To conclude, we can spatially identify the distribution with a significant difference between carbon emissions according to energy use as a micro analysis by Hot Spot to Analysis on point entities. It is to be hoped that this method will be utilized to establish various policies and to evaluate the effect of reduction of GHG.