• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.3
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• pp.551-564
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• 2016

Earthworks are the fundamental steps in a construction job, and are mainly comprised of smaller tasks performed by construction machinery. The productivity of the construction job can be improved by optimizing excavation, filling, and other such operations. Earthworks involve a lot of mechanical work performed by the collaboration between various kinds of construction equipment, which in turn leads to higher fuel consumption. Actual earthworks depend mostly on the intuition and experience of the driver of the machines, thus leading to inefficiency and environmental problems caused by unnecessary emission of carbon, Recently automated and information-oriented technologies are consistently being researched towards the improvement of efficiency of earthworks in the construction industry. The present research involves the introduction and understanding of the decision-making elements of heuristics which can be applied to the earthwork planning. A method is also suggested for creating an effective work path for construction machine to perform task packages (TP) for cutting and filling processes. A simulation test is performed to verify the effectiveness of suggested methods in terms of space interference and total moving distance of construction equipment.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.870-875
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• 2015

Diesel engines are widely used due to superior power and fuel consumption, however there are many challenges in exhaust gas management. Exhaust gas recirculation (EGR) is the most effective technique for reducing mono-nitrogen oxide (NOx) emissions in a diesel engine, in comparison with other catalytic technologies. In addition, the technology has a number of advantages in terms of economic efficiency and implementation. In this study, the effects on the power and exhaust characteristics of diesel engines equipped with EGR systems were investigated. It was found that as the EGR rate increased, horsepower expressed as IHP and BHP decreased. The net effect of the application of EGR was measured at various engine speeds. EGR technology caused decreases in BHP of around 9% during low engine speed and 3.5% during high engine speed. Additionally, NOx emissions reduced as the EGR rate increased, and increased as engine speed increased. However, smoke emissions increased as the EGR rate increased, and decreased as engine speed increased. The optimum operating conditions and ERG rate to simultaneously achieve minimum NOx and smoke emissions were investigate. It was found that as the EGR rate increased, optimal operating speed for minimal NOx and smoke also increased. Keywords: Diesel engine, Exhaust gas recirculation, Power perfomance, Emission characteristics, NOx, Smoke

• Microbiology and Biotechnology Letters
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• v.16 no.6
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• pp.494-498
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• 1988

The optimum conditions for glucoamylase production, and ethanol productivity of the transformant TSD-14 were investigated as compared with the parental strains. The properties of TSD-14 were comparatively similar to the donor S. diastaticus IFO 1046 as regards the conditions of glucoamylase production and ethanol productivity. The soluble starch was the most effective carbon source for the glucoamylase production. While inorganic nitrogen sources did not prompt cell growth and enzyme production, the organic nitrogen sources generally enhanced both cell growth and glucoamylase production. The metal salts such as FeSO$_4$, MgSO$_4$, MnCl$_2$, and NiSO$_4$were favorable to the enzyme production. And the optium temperature and initial pH for glucoamylase production were 3$0^{\circ}C$ and 5. The transformant TSD-14 produced 8.3%(v/v) ethanol from 15% sucrose medium, 4.8%(v/v) ethanol from 15% soluble starch medium, and 7.5%(v/v) ethanol from 15% liquefied potato starch medium. The corresponding fermentation efficiency were 84% , 45% and 70%, respectively.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.1
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• pp.53-60
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• 2020

Objective: The current study was carried out to examine the response of different levels of fat and protein in calf starter on nutrient utilisation, nitrogen metabolism, weight gain, blood parameters, and immunity level in pre-ruminant calves. Methods: Twenty four calves (5 days old) were divided into six groups in a 2×3 factorial design, with two levels of fat (10% and 14%) and three levels of protein (18%, 21%, and 24%). The calves were kept in individual pens for 120 days and fed with whole milk (1/10th of body weight) and calf starter ad-libitum. Daily dry matter intake was recorded; whereas body weight was taken on fortnightly basis to calculate average daily gain. During the growth trial blood samples were collected at 30 days interval to estimate blood glucose, albumin, total protein, total leucocyte count, total immunoglobulins and immunoglobulin G levels. A metabolic trial of seven days was carried out to find out the digestibility of different nutrients. Results: The dry matter intake was reduced (p<0.05) with higher fat and protein levels whereas feed conversion efficiency was improved (p<0.05) with higher protein level. Different levels of fat and protein in calf ration did not affect average daily gain in calves. The dry matter, organic matter, and crude protein digestibility were significantly (p<0.01) higher with increased level of protein. The nitrogen retention was also significantly higher (p<0.05) at 24% protein level, similarly the total immunoglobulin was significantly (p<0.05) high in higher protein fed groups, showed better immunity. Conclusion: The present finding suggested that 10% fat and 18% protein level of calf starter could be used in Sahiwal calves for optimum performance in terms of weight gain and immunity.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.4
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• pp.201-212
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• 2016

A Wind resource assessment and optimal micrositing of wind turbines were implemented for the development of an onshore wind farm of 30 MW capacity on Gadeok Island in Busan, Republic of Korea. The wind data measured by the automatic weather system (AWS) that was installed and operated in the candidate area were used, and a reliability investigation was conducted through a data quality check. The AWS data were measured for one year, and were corrected for the long term of 30 years by using the modern era retrospective analysis for research and application (MERRA) reanalysis data and a measure- correlate-predict (MCP) technique; the corrected data were used for the optimal micrositing of the wind turbines. The micrositing of the 3 MW wind turbines was conducted under 25 conditions, then the best-optimized layout was analyzed with a various wake model. When the optimization was complete, the estimated park efficiency and capacity factor were from 97.6 to 98.7 and from 37.9 to 38.3, respectively. Furthermore, the annual energy production (AEP), including wake losses, was estimated to be from 99,598.4 MWh to 100,732.9 MWh, and the area was confirmed as a highly economical location for development of a wind farm.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.260-260
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• 2011

SWAT is semi-distributed and continuous-time distributed simulation watershed model, which can simulate point and nonpoint source pollutants as well as hydrology and water quality. It was developed to predict the effects of alternative management decisions on water, sediment, and chemical yields with reasonable accuracy. It is able to predict and manage hydrology, sediments, nutrients, and pesticides with Best Management Practices (BMPs) in a watershed. SWAT model also has potential for use in ungauged basins to predict streamflow and baseflow from saturated source area in watersheds. According to various cultivation practices and climate change, SWAT model is available to analyze relative change in hydrology and water quality. In order to establish optimum management of water quality, both monitering and modeling have been conducted actively using SWAT model. As SWAT model is computer program to simulate a lot of natural phenomena, it has limitation to predict and reflect them with on hundred percent accuracy. Thus, it is possible to analyze the effect of BMPs in the watershed where users want to simulate hydrology and water quality only if model accuracy and applicability are assessed first of all and the result of it is well for the study watershed. For assessment of SWAT applicability, most researchers have used $R^2$ and Nash and Sutcliffe Efficiency (NSE). $R^2$ and NSE are likely to show different results according to a warm up period and sometimes its results are very different. There have been hardly any studies of whether warm up period can affect simulation results in SWAT model. In this study, how warm up period has a effect on SWAT results was analyzed and a appropriate warm up period was suggested. Lots of SWAT results were compared after using measured data of Soyanggang-dam watershed and applying various warm up period (0 ~ 10 year(s)). As a result of this study, when there was no warm up period, $R^2$ and NSE were 0.645, 0.602 respectively, when warm up period was 2 years, $R^2$ and NSE were 0.648, 0.632, and when warm up period was 4 years, $R^2$ and NSE were 0.663, 0.652 separately. Through this study, sensitive analysis of warm up period in SWAT model was conducted, and this study could give a guideline able to simulate hydrology and water quality for more accuracy than before as users change a lot of warm up periods as well as any simulation parameters.

• Korean Journal of Construction Engineering and Management
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• v.12 no.3
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• pp.73-82
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• 2011

The term 'green' has become an important way of survival for the construction industry in 21th century in accordance with the emergence of the environmental crisis due to the climatic change. Especially the policy of carbon taxation, planed to be introduced from 2012, is expected to be a considerable burden to the construction industry which has abundant carbon emission during the resource transportation due to the complexity of resources and local distribution of the construction sites. In this regard, this study shows an optimizing strategy for delivery frequency, which downsizes the net distribution costs based on the assumption that, despite of its other advantagements, the frequent small lot mode of JIT delivery would take negative effects due to the increase of costs of transportation and carbon emission once the carbon taxation policy carried out. To simulate the efficiency of the management strategies, the System Dynamics modeling has been used. The results show that the frequent small lot transportation strategy is now always efficient method to these changes, and that the frequency of transportation should be re-determinated according to the extent of the imposition of carbon tax. This study provides the conceptual frame for an efficient management of transportation system of the construction industry, showing necessity of change of the resource transportation systems through analysing JIT deliver system in accordance with the global changes in environmental economy.

• Resources Recycling
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• v.11 no.2
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• pp.3-13
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• 2002

The characteristics of cyanide decomposition in aqueous phase by hydrogen peroxide have been explored in an effort to develop a process to recycle waste water. The self-decomposition of $H_2O$$_2$at pH 10 or below was minimal even in 90 min., with keeping about 90% of $H_2O$$_2$undissociated. On the contrary, at pH 12 only 9% of it remained during the same time. In the presence of copper catalyst at 5 g Cu/L, complete decomposition of $H_2$O$_2$was accomplished at pH 12 even in a shorter time of 40 min. The volatility of free cyanide was decisively dependent on the solution pH: the majority of free cyanide was volatilized at pH 8 or below, however, only 10% of it was volatilized at pH 10 or above. In non-catalytic cyanide decomposition, the free cyanide removal was incomplete in 300 min. even in an excessive addition of $H_2$$O_2$at a $H_2$$O_2$/CN molar ratio of 4, with leaving behind about 8% of free cyanide. On the other hand, in the presence of copper catalyst at a Cu/CN molar ratio of 0.2, the free cyanide was mostly decomposed in only 16 min. at a reducedH202/CN molar ratio of 2. Ihe efnciency of HBO2 in cyanide decomposition decreased with increasing addition of H2O2 since the seu-decomposition rate of $H_2$$O_2$increased. At the optimum $H_2$$O_2$/mo1ar ratio 0.2 of and Cu/CN molar ratio of 0.05, the free cyanide could be completely decomposed in 70 min., having a self-decomposition rate of 22 mM/min and a H$_2$$O_2$ efficiency of 57%.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.4
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• pp.466-471
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• 2007

The purpose of study is to obtain basic but important information for the operation of the greenhouse facility located in the suburb of town. Special emphasis is given on the aspect of energy saving method, which can be easilyapplicable in a practical sense. For this end numerical calculation has been made systematically in order to increase the energy efficiency by the evaluation of the temperature distribution in greenhouse. Major parameters considered are primarily the overall shape of greenhouse together with the various conditions of baffle installion inside greenhouse. Further, the performance of heating system is also carefully compared each other for a number of typical arrangements of heating duct. The performance of the computer program developed in this study is evaluated by the observation of the famous fluid trapping phenomenon occurred in staggered baffle condition in the enclosure of greenhouse. Based on the this study, a number of useful conclusions can be drawn, that is, the installation of baffles are quite effective in energy saving method with a minor modification of facility. Also, it is found that the change of the heating duct system can contribute significantly to the uniform temperature distribution in greenhouse. Further other findings obtained by numerical calculation were not only physically consistent and meaningful but also useful for the determination of optimum condition of practical operation of greenhouse.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.12
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• pp.1268-1272
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• 2008

Low temperature plasma applied with partial oxidation is a technique to produce synthesis gas from methane. Low temperature plasma reformer has superior miniaturization and start-up characteristics to reformers using steam reforming or CO$_2$ reforming. In this research, a low temperature plasma reformer using GlidArc discharge was proposed. Reforming characteristics for each of the following variables were studied: gas components ratio (O$_2$/CH$_4$), the amount of steam, comparison of reaction on nickle and iron catalysts and the amount of CO$_2$. The optimum conditions for hydrogen production from methane was found. The maximum Hydrogen concentration of 41.1% was obtained under the following in this condition: O$_2$/C ratio of 0.64, total gas flow of 14.2 L/min, catalyst reactor temperature of 672$^{\circ}C$, the amount of steam was 0.8, reformer energy density of 1.1 kJ/L with Ni catalyst in the catalyst reactor. At this point, the methane conversion rate, hydrogen selectivity and reformer thermal efficiency were 66%, 93% and 35.2%, respectively.