• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.1
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• pp.88-94
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• 2012

One of the effective ways to reduce both $NO_x$ and PM at the same time in a diesel CI engine is to operate the engine in low temperature combustion (LTC) regimes. In general, two strategies are used to realize the LTC operation-dilution controlled LTC and late injection LTC - and in this study, the former approach was used. In the dilution controlled regime, LTC is achieved by supplying a large amount of EGR to the cylinder. The significant EGR gas increases the heat capacity of in-cylinder charge mixture while decreasing oxygen concentration of the charge, activating low temperature oxidation reaction and lowering PM and $NO_x$ emissions. However, use of high EGR levels also deteriorates combustion efficiency and engine power output. Therefore, it is widely considered to use increased intake pressure as a way to resolve this issue. In this study, the effects of intake pressure variations on performance and emission characteristics of a single cylinder diesel engine operated in LTC regimes were examined. LTC operation was achieved in less than 8% $O_2$ concentration and thus a simultaneous reduction of both PM and $NO_x$ emission was confirmed. As intake pressure increased, combustion efficiency was improved so that THC and CO emissions were decreased. A shift of the peak Soot location was also observed to lower $O_2$ concentration while $NO_x$ levels were kept nearly zero. In addition, an elevation of intake pressure enhanced engine power output as well as indicated thermal efficiency in LTC regimes. All these results suggested that LTC operation range can be extended and emissions can be further reduced by adjusting intake pressure.

• Journal of Bio-Environment Control
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• v.26 no.2
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• pp.115-122
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• 2017

Objective of this research was to investigate the influence of lowered substrate pH on the reduction of bicarbonate injury in the vegetative growth of 'Ssanta' strawberry. The acid substrate was formulated by mixing sphagnum peat moss with pine bark (5:5, v/v) and the pH, EC, and CEC of the substrate were 4.07, $0.46dS{\cdot}m^{-1}$, and $91.3cmol^+{\cdot}kg^{-1}$, respectively. To adjust the pH of acid substrate, various amount of dolomitic lime [$CaMg(CO_3)_2$] were incorporated with the rate of 0 (untreated), 1, 2, 3, and $4g{\cdot}L^{-1}$. Then, mother plants were transplanted and grown with fertilizer solution containing $240mg{\cdot}L^{-1}$ of the $HCO_3{^-}$ and equal concentrations of essential nutrients to Hoagland solution. In growth of 'Ssanta' strawberry, fresh weight of mother plants were the highest in the treatment of $2g{\cdot}L^{-1}$ dolomitic lime such as 102.1 g followed by 94.7 g in $1g{\cdot}L^{-1}$, 91.2 g in $3g{\cdot}L^{-1}$, 75.7 g in $0g{\cdot}L^{-1}$ and 72.3 g in $4g{\cdot}L^{-1}$ treatments. The dry weight showed a similar tendency to fresh weight. At 140 days after transplanting, 5.8, 9.8, 11.8, 8.8, and 5.0 daughter plants were derived from each of the mother plants in the treatments of 0, 1, 2, 3, and $4g{\cdot}L^{-1}$ dolomitic lime, respectively. The highest occurrence of daughter plants were observed in the treatments $2g{\cdot}L^{-1}$ dolomitic lime. The substrate pH and bicarbonate concentration of 'Ssanta' strawberry seedlings in the 1 and $2g{\cdot}L^{-1}$ dolomitic lime treatments were maintained at a proper range such as 5.6 to 6.2. The micro-nutrient contents of above ground tissue in mother plants were the highest in $2g{\cdot}L^{-1}$ and the lowest in $4g{\cdot}L^{-1}$ dolomitic lime treatment. The above results indicate that incorporation rate of dolomitic lime in acid substrate with the pH of around 4 is $2g{\cdot}L^{-1}$ to raise the 'Ssanta' strawberry in propagation.

• Horticultural Science & Technology
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• v.34 no.2
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• pp.220-227
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• 2016

The objective of this research was to investigate the influence of application rates of dolomitic lime in the acid substrate on the mitigation of high bicarbonate damage in 'Seolhyang' strawberry. For this purpose, an acid substrate was formulated by mixing of sphagnum peat moss and pine bark with the ratio of 5:5 (v/v). The pH, EC and CEC of the substrate analyzed before application of dolomite were 4.07, $0.46dS{\cdot}m^{-1}$, and $91.3cmol+/kg^{-1}$, respectively. To adjust the pH of substrate, various amounts of dolomitic lime [$CaMg(CO_3)_2$] such as 0 (control), 1, 2, 3, and $4g{\cdot}L^{-1}$ were added during substrate formulation. Then, seedlings with 3 leaf stage were transplanted as mother plants and those were fed with Hoagland solution containing $240mg{\cdot}L^{-1}$ of the $HCO_3{^-}$. The growth parameters of mother plants 140 days after transplanting, such as plant height, chlorophyll content, and fresh weight were the highest in the treatments of 2 and $3g{\cdot}L^{-1}$ of dolomitic lime. The physiological disorders in mother plants were not observed in the 1, 2 and $3g{\cdot}L^{-1}$ treatments, but the symptoms of Ca, K and B deficiencies were observed in the 0 and $4g{\cdot}L^{-1}$ treatments. During the propagation period, the number of daughter plants derived from each mother plant were 21.0, 29.5, 35.8, 27.3 and 16.0 in the treatments of 0, 1, 2, 3 and $4g{\cdot}L^{-1}$, respectively. The substrate pH during cultivation of mother plants were maintained at appropriate levels for the 1 and $2g{\cdot}L^{-1}$ treatments, whereas it was the highest in $4g{\cdot}L^{-1}$ treatment. The contents of macro- and micro-elements in the above ground tissue were the highest in $2g{\cdot}L^{-1}$ and the lowest in $4g{\cdot}L^{-1}$ lime treatments. Above results suggest that the bicarbonate injury originated from ground water can be mitigated by adjusting the amount of dolomitic lime incorporated into the acid substrate.

• Journal of Life Science
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• v.30 no.2
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• pp.162-168
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• 2020

Because of a continual reduction in its domestic market share, the quality of the Makgeolli, a Korean traditional liquor, needs to be upgraded. Among the several options for quality improvement, sufficient organoleptic expression of flavor is very important. We analyzed production changes of isoamyl acetate, which has a banana smell, based on fermentation temperature and sugar content through the cultivation of S. cerevisiae 98-5 KCCM 11396P using generally polished rice. The banana flavor of that fermentation mash was organoleptically high at 20℃, but a larger amount of isoamyl acetate was obtained with a higher sugar content at 10℃, based on analysis by GC-MS. Consequently, sufficient production of banana flavor from isoamyl acetate was based on the concentration of isoamyl alcohol as a substrate compound of isoamyl acetate, and the production depended highly on the maintenance of heat stability, since it is unstable in temperature and the minimized inhibition of alcohol acetyl transferase by unsaturated fatty acids. We also found that production of the flavor component required the addition of sugar and a slightly higher temperature of 20~25℃ at the beginning stage of fermentation, with additional mash fermentation and a gradual decrease in temperature to 10~15℃.

• Journal of Climate Change Research
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• v.8 no.1
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• pp.21-30
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• 2017

Recently, There has been much discussed about unused space. This space can be used in a variety of ways. Utilizing it as a facility, craft shop, and utilizing renewable energy generation facilities. Especially, in terms of climate change should be supplied renewable energy. Renewable energy needs to be developed in terms of responding to climate change, and the recent Paris agreement is also emphasizing the importance of renewable energy. In particular, renewable energy needs to be widely disseminated. And renewable energy is limited space. In this regard, idle land can provide opportunities for securing new renewable energy generation facilities. The introduction of new and renewable energy facilities in idle space can enhance the self-sufficiency rate of the local community, which is significant in terms of responding to climate. In this study, to investigate the possibility of utilizing a unused space for a photovoltaic power generation facility, we investigated the amount of electricity which could be generated through photovoltaic power generation, and the economic effects, using a RETScreen model. The results showed that 9,738 MWh of power can be generated and that $4,540tCO_2eqcan$ be saved. Regarding the economic effect, the net present value of the facility was shown to be 2,247,389,020 KRW. As the net present value was shown to be positive, we believe that the installation of a photovoltaic power generation facility in an unused space would have a positive economic effect. We found the net present value following the fluctuation of the SMP price to be positive, though there was some variation. However, as the economic efficiency was shown to be low because the net present value in relation to the maintenance costs was negative, we believe that maintenance costs must be taken fully into account when evaluating economic efficiency. In particular, as subsidies can be used to cover maintenance costs which must be factored into photovoltaic power generation, we believe that photovoltaic power generation can have an economic effect. Because spaces not currently in use can have a positive economic effect as renewable energy power generation facilities, and can also contribute to the reduction of greenhouse gas emissions, unused spaces are thought to greatly help local governments to cope with climate change as well as reinforcing their related capabilities. We believe our study will help local governments with decisions relating to unused real estate utilization in the future.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.1
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• pp.131-135
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• 2008

Purpose: To measure and quantify the factors of intraocular pressure (IOP) variation for normal Korean youth. Methods: The IOP of normal youth 805 persons (male: 367, female: 438) were measured as a function of time and quantity for fixation, reclining posture, hard blinking, drinking water, drinking hard liquor, tobacco and coffee by using non-contact tonometer (AT555, Reichert Co.). In the case of fixation, reclining posture and hard blinking, the intraocular pressure of right and left eye were measured for 6 males and 6 females every 10 minutes during 30 minute. In the case of water, liquor, tobacco and coffee, the measurement for 4 or 5 groups (6 persons/ group) having similar IOP were done for the IOP variation of right eye. Results: The mean IOP was 15.2 mmHg for males and 15.8 mmHg for females (slightly higher than male's), respectively and the 99% of those were in the range of the normal IOP. The measured IOP was increased by fixation, reclining posture and hard blinking with males and females. The gradient of increasing slope was 0.15/0.13/0.07/0.08, 0.09/0.08/0.08/0.08 and 0.19/0.08/0.26/0.31, respectively. The IOP variation was elevated by drinking water (especially in the case of 1000 ml) and lowered in proportion to the amount of drinking by hard liquor. Cigarette smoking was associated with rise in intra ocular pressure, but was not shown a definite relation. And coffee had virtually no effect. Conclusions: Fixation, reclining posture, hard blinking and Tobacco caused a transient increase in IOP, but alcohol elicited a slight reduction in IOP overall.

• Journal of the Korean GEO-environmental Society
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• v.15 no.2
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• pp.17-25
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• 2014

In the present study, it were performed an unconfined compression test and a field applicability test according to a mixed ratio of SS, soil type and curing period to analyze strength and deformation characteristic in order to evaluate engineering characteristics of soil mixed pavements using the eco-friendly soil stabilizer (SS). The test results revealed that SS mixed soil shows fast strength development at the initial curing time while 28-day strength amounted for 97% of the final strength. Furthermore, coarse-grained dredged sand (DS) and weathered granitic soil (WGS) have a larger ratio of deformation coefficient with respect to unconfined compressive strength than fine-grained dredged clay (DC) and organic soil (OS). Moreover, a comparison test between natural and forced drying conditions was conducted and test result showed 54% to 67% of strength degradation while having 55% to 63% of strength degradation in the freezing and thawing test result. Finally, a repeated loading test result showed that DS experiences up to 35% of strength reduction compared to initial strength under 10,000 times loading in maximum. Thus, it was validated that an appropriate amount of fine-grained sand is necessary to secure resistance capability to repeated loading.

• Resources Recycling
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• v.32 no.1
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• pp.50-59
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• 2023

The amount of dust generated during the dissolution of scrap in an electric arc furnace is approximately 1.5% of the scrap metal input, and it is primarily collected in a bag filter. Electric arc furnace dust primarily consists of zinc and ion. The processing of zinc starts with its conversion into pellet form by the addition of a carbon-based reducing agent(coke, anthracite) and limestone (C/S control). These pellets then undergo reduction, volatilization, and re-oxidation in rotary kiln or RHF reactor to recover crude zinc oxide (60%w/w). Next, iron is discharged from the electric arc furnace dust as a solid called Fe clinker (secondary by-product of the Fe-base). Several methods are then used to treat the Fe clinker, which vary depending on the country, including landfilling and recycling (e.g., subbase course material, aggregate for concrete, Fe-source for cement manufacturing). However, landfilling has several drawbacks, including environmental pollution due to leaching, high landfill costs, and wastage of iron resources. To improve Fe recovery in the clinker, we pulverized it into optimal -sized particles and employed specific gravity and magnetic force selection methods to isolate this metal. A carbon-based reducing agent and a binding material were added to the separated coarse powder (>10㎛) to prepare briquette clinker. A small amount (1-3%w/w) of the briquette clinker was charged with the scrap in an electric arc furnace to evaluate its feasibility as an additives (carbonaceous material, heat-generating material, and Fe source).

• Korean Journal of Weed Science
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• v.11 no.2
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• pp.128-136
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• 1991

This experiment was conducted to evaluate the effect of plant growth regulators, dichlorprop and MCPB on the reduced effect of fruit drop and fruit quality before and after storage in apples. Dichlorprop was tested with dilution of 1000 at 30, 40, 50 days before harvesting, and MCPB with dilution of 4000 at 15, 25, 35 days before harvesting. The results are summarized as follows : Percentage of fruit drop was appeared to the notable reduction as compared with the untreated control when regulators was applied with dilution of 1000 at 30 days before harvesting by dichlorprop and with dilution of 4000 at 35 days before harvesting by MCPB. Degree of fruit colour showed to the remarkable promotion at all the treatment of 30, 40, 50 days before harvesting by dichlorprop as compared with the untreated control. Sugar contents in flesh was increased a little at the treatment of 30 days before harvesting by dichlorprop, but acid contents in flesh was reduced at all the treatment of 30, 40, 50 days before harvesting by dichloroprop and at 15, 25, 35 days before harvesting by MCPB. Passed firmness of fruit after storage was maintained at the treatment with dilution of 4000 at 35 days before harvesting. Therefore, it was repressed a softening of fruit, but by dichlorprop treatment at 30, 40, 50 days before harvesting, fruit firmmess was appeared to reduce according to the passage of storage period. Amount of ethylene evolution after storage was showed to reduce at all the treatment by early treated time of dichoroprop and MCPB, but carbon dioxide increased at treatment conditions such as the front. Accordingly, these relationship showed to be contrary each other.

• Journal of Environmental Science International
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• v.22 no.7
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• pp.787-799
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• 2013

The aim of this study was to investigate the accumulation of metallic elements and the control effect of marine pollution caused by ocean dumping in the sediments at a waste disposal area in the Yellow Sea. In July 2009, concentrations of organic matter and metallic elements (Al, Fe, As, Cd, Cr, Co, Hg, Ni, Mn, Pb, and Zn) were measured in surface sediments at the site. The ignition loss (IL) in the surface sediments showed a mean value of 15.4%, about 1.5 times higher than the mean value of the sediments in the coastal areas of Korea. The chemical oxygen demand (COD) at some disposal sites exceeded 20 mg $O_2/g{\cdot}dry$, which signifies the initial concentration of marine sediment pollutants in Japan. The disposal sites contain higher concentrations of Cr, Cu and Zn than the sediments of bays and estuaries that might be contaminated. The magnitude of both metal enrichment factors (EF) and adverse biological effects suggest that pollution with Cr and Ni occurred due to the dumping of waste in the study area. In addition, the geoaccumulation index (Igeo) showed that the surface sediments were moderately contaminated. By the mid-2000s, when the amount of waste dumped at this site was the highest, the concentration of metallic elements was higher than ever recorded. On the other hand, in 2008-09, the need for environmental management was relatively low compare with the peak. As a result, the quality of marine sediment has been enhanced, considering the effect of waste reduction and natural dilution in the disposal area.