• Journal of Forest and Environmental Science
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• v.23 no.1
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• pp.21-28
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• 2007

In my study, I analysed and criticised the change of applied works based on a design drawing of a private forest road in Chungchengnam province from 1990 to 2003. The aim of this study is to obtain the fundamental resources for establishment the green forest road which is environment friendly. Working expenses of forest road was gradually increased by a business year. In particular, the working expenses dramatically increased in 1999-2000. In change rate of cost of construction by works, earth work rate of the cost of constructions was declined: from 25.4% in 1990-1999, to 18.5% in 2000-2003. However, the total cost of the construction of slope protection work and structural work increased. Nevertheless the rate of the cost of constructions are not increased where as the earth work rate of the cost of constructions were reduced. The rate of the price construction materials and the cost of construction was the main causes which was led by the extension of the standard requirement of applied work and the increase of the materials of applied work. In other word, materials of structural work and slope protection work increased. If the increase of the cost of construction has seem through the increase of contractual materials and extension of the standard requirement would led to weak competitiveness of forest road. Therefore, diverse method of constructions need to apply and a new method should be developed.

• Journal of Information Technology and Architecture
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• v.11 no.3
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• pp.359-369
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• 2014

This paper aims to analyze the change of dominion in Russian automotive market and Korea port to export cars to the Russia. First, we provide the current market structure and growth potentials of Russian automotive industry by using literature reviews and data survey. Next, we analyze the current situation to export cars through the Korean seaports using the BCG (Boston Consulting Group)'s matrix method. The analysis shows that the Russian car market has growth potential. The result of expectation of Russian major car export's port within 3~5 years since the year 2013 shows that the Pohang Port will maintain current market share because it has higher market share and growth potential. On the contrary, the Guangyang Port, Busan Port, and Ulsan Port will lose the market share because of the low growth potential. Also, the Incheon Port will become the cash cow market because it has more than 10 percent market share and higher growth potential. To increase the car export volume of ports to Russian market, this paper proposes that we should provide a differentiated service to Russian port based on the analysis of domestic or foreign car export logistics structure and flow. For further study, EA-based framework should be applied for efficient and effective policies.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.4
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• pp.341-349
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• 2002

Electrical, mechanical and sinterability properties of yttria-stabilized zirconia doped with 5.35wt% $Y_2$O$_3$(Y$_2$O$_3$- containing stabilized zirconia : YSZ) were studied as a function of $Al_2$O$_3$, CoO, Fe$_2$O$_3$ and MnO$_2$ addition. The ratio of monoclinic phase to tetragonal phase was changed by the addition of $Al_2$O$_3$, CoO, Fe$_2$O$_3$ and MnO$_2$ to 8.00 wt% and sintered density decreased with increasing $Al_2$O$_3$, CoO, Fe$_2$O$_3$ and MnO$_2$ addition. Fracture toughness increased with the increase of monoclinic to tetragonal phase ratio and was maximum at about 18%. When transition metals such as CoO, Fe$_2$O$_3$ or MnO$_2$ was added more than 1.5 wt%, the electrical conductivity of YSZ increased. But $Al_2$O$_3$ hardly affected the electrical conductivity of YSZ. The addition of $Al_2$O$_3$, CoO, Fe$_2$O$_3$ and MnO$_2$ into YSZ resulted in the more complex behavior of fracture toughness and hardness variation and the specimen with 1.5wt%-Fe$_2$O$_3$, 3.0wt%-Al$_2$O$_3$ and 1.5wt%-CoO showed the monoclinic to tetragonal phase ratio of 18% and the highest toughness of 10.8 MPa.m$^{1}$2/ and Vickers hardness of 1201 kgf/mm$^2$.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.10
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• pp.1267-1274
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• 2012

A guide vane plays a key role in controlling the flow rate of water supplied to the turbine of a hydropower plant. It has been reported that guide vane bearing bushings are subjected to considerable wear, which requires them to be maintained. An ancillary service such as frequency control and black start causes cyclic low opening operation of the guide vanes. It is empirically well known that such operation increases the wear rate of the guide vane bearing bushing. In this study, the effect of low opening operation on the increasing wear of the guide vane bearing bushing is quantitatively assessed via finite element flow analysis, finite element stress analysis, and relative wear evaluation. As a result of the assessment, it is identified that the pressure applied on the guide vane surface increases and the contact length between the outer surface of the guide vane stem and the inner surface of the bearing bushing decreases with a decrease in the opening of the guide vane. In addition, low opening of the guide vanes results in an increase in the relative wear owing to the generation of high contact pressure on the bearing bushing surfaces.

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.234-239
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• 2010

The irrigation interval and time for the supply of nutrient and water to the plant is important in the aeroponic system. This study was conducted to investigate the effect of irrigation interval on the growth of Phalaenopsis hybrid seedlings in the aeroponic system. Young bare-root plants (four leaves, 16 g in fresh weight) were used for this experiment. The composition of nutrient solution was, in $me{\cdot}L^{-1}$, 9 N, 3 P, 4 K, 4 Ca and 2 Mg. The electrical conductivity (EC) and pH of nutrient solution used was $1.2\;dS{\cdot}m^{-1}$ and 5.8, respectively. Irrigation intervals were 10, 20, 30, 40, and 50 minute and each irrigation time was 10 minute. The total fresh and dry weight, the number of branched roots, and relative growth rate at the 20 and 30 min. was greater than 10, 40, 50 min. interval. Especially, the fresh weight of roots at 30 min. interval was the highest. Leaf length was the highest at 30 min. interval but there was no difference in leaf width. The amount of water consumed for a month was 0.71 L per plant and it was reduced with increasing irrigation interval. There was no difference in the amount of consumed mineral contents for 15 days except for potassium. Potassium absorbed was the highest at 30 min. irrigation interval. As a result, the optimum irrigation interval was 30 min for the production of Phalaenopsis hybrid seedlings in the aeroponic system.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.7 no.3
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• pp.171-180
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• 2002

The temporal and spatial distributions of phosphorus have been investigated in the Gomso Bay, Korea. TP, PIP, TOP and DIP in sediment were found 548.8mg P kg$^{-1}$ , 426.1mg P kg$^{-1}$ , 122.6mg P kg$^{-1}$ , and 0.217mg P kg$^{-1}$ , respectively with a decreasing order of PIP>TOP>DIP. Any temporal or spatial trend has not been found on the distribution of TP in the sediment, except the high TP values near the mouth of Julpo-chun. We found seasonal patterns high TOP(28.90% of TP) and low TIP(71.10% of TP) in August, but low TOP(15.63% of TP) and high TIP(84.38% of TP) in November. There were three times higher DIP concentration in August than in November. Such case is probably not only due to the enhanced supply of DIP directly from the decomposition of organic matter from overlying water in summer, but also the released phosphate from the adsorbed particulate matter such as PIP under the low pH and Eh conditions at the subsurface layers of the sediment induced by the active microbial respiration of increased organic materials in summer. Primarily, the source of phosphorous from municipal sewage strongly influenced the early stage of the distribution of all the phosphorous in the Gomso tidal flat. Notwithstanding, through the processes of diagenesis in sediment, water temperature and organic contents probably functioned as the key parameters to control the temporal distributions of TOP, TIP and DIP in the Gomso tidal flat.

• Korean Journal of Ecology and Environment
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• v.33 no.4 s.92
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• pp.319-327
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• 2000

The feeding behavior of 1-year-old silver carp, Hypophthalmichthys molitrix (Val.) on phytoplankton species in a shallow hypertrophic lake was studied from 22 May to 18 September, 1997. Over the experimental period, the filter-pore sizes of the fish, the total biomass of the phytoplankton and the water temperature in each enclosure changed little with time. The fish biomass in each enclosure increased with time, while their percentage of weight gain correlated negatively to the stocking density, due perhaps to competition for prey. An analysis of gut contents of silver carp showed a strong similarity between the algal communities in the foregut and the water, and was significant for the fish enclosure with a low density (p<0.05). The presence of silver carp rarely suppressed the abundance of phytoplankton such as Oscillatoria, Anabaena and Melosira even at high ingestion levels. There were weak relationships between the IU values of each phytoplankton and the selectivity of fish on them (r = 0.001, p>0.5). There was no doubt that the silver carp fed unselectively when cyanobacteria populations were high, even though the selectivity index for diatoms was slightly higher than those for cyanobacteria, green algae and cryptomonads. Improvements in methodologies are needed to clearly understand and generalize the feeding behavior of silver carp.

• Journal of the Korea Institute of Building Construction
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• v.9 no.6
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• pp.161-168
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• 2009

In an architectural construction, underground construction is a critical path forming a major part of the total construction period and cost, and particularly in big cities, its size has been increasing every year. A basement wall currently constructed in the field needs a large functional work force, and the construction is under progress by the Euroform and Soldier system, which is disadvantageous in terms of the construction period. Therefore, in this research, non-supporting forms which are applicable to the buildings construction were developed, based on the non-supporting forms partly used in some civil engineering works. In addition, the size of a form was assumed and its economical efficiency was compared to that of the Euroform and Soldier system which is used most in construction fields, and the results were analyzed. The study results showed that the construction cost of composite non-supporting forms was higher than that of the Euroform and Soldier system by about 8%, and the construction cost of non-composite non-supporting forms were lower than that of the Euroform and Soldier system by about 9%. However, in the case of composite non-supporting forms, the amount of concrete and reinforcing rods remarkably decreased in structural construction, so it has the effect of an economical cost reduction compared to the construction cost of existing walls by about 35%

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.1
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• pp.1-9
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• 2014

In this paper, $CO_2$ amount is evaluated considering repairing timing and unit $CO_2$ amount per repair method including various stage of material manufacturing, moving, and construction. Four mix proportions with mineral admixture are considered and repairing timing/numbers are simulated based on the results from Life 365 which can handle chloride penetration. Furthermore two repair methods (simple cover concrete replacement and replacement with electro-chemical method for removing chloride content) are considered and the related $CO_2$ emissions are evaluated. From the study, the case with high W/B (water to binder ratio) ratio shows smaller $CO_2$ emission in construction stage but it increases more rapidly with increasing number of repair. $CO_2$ emission considering electro-chemical method greatly increases with the increasing unit $CO_2$ for the repairing method. The numbers of jumping step (repairing number) are evaluated to be 9 for WB37-OPC, 18 for WB50-OPC, 4 for WB40-SG, and 7 for WB47-SG respectively. RC structures with the longer maintenance free period are evaluated to be advantageous for saving $CO_2$ emission.

• Environmental and Resource Economics Review
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• v.19 no.1
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• pp.81-100
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• 2010

This paper measures the impacts of the Korea-China Free Trade Agreement (FTA) on the emissions of carbon dioxide ($CO_2$) in Korean export industries. The Korean industrial exports were forecasted by employing Bayesian Kalman Filter Vector Auto-Regression (BVAR) model. The emissions of $CO_2$ were then estimated by applying the $CO_2$ emission coeffcients on the conditionally forecasted values of export by industries. Under the conditional scenario of the 50% reduction in current tariff rate through FTA between Korea and China, the total $CO_2$ emissions in Korea were expected to increase by 1.96% compared to the BAU (Non FT A) trend at the end of 2010. Another conditional scenario with no tariff after 2012 was also adopted. In this case, the total $CO_2$ emlssions were estimated to increase by 2.06% compared to the BAU up until the end of 2014. These facts imply that the FTA between Korea and China would not result in the significant increase of $CO_2$ emissions in Korea.