• Journal of the Korea Institute of Building Construction
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• v.19 no.5
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• pp.449-456
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• 2019

Recent developments in architectural technologies and programs have enabled architects to think creatively and design free-form architecture. however, there are many problems in the production technology of FCP(Free-Form Concrete Panel). In particular, reduced accuracy due to lack of free-form panel production technology can lead to redesign of buildings as a result, problems such as an increase in construction cost and period. Therefore, this experiment aimed to compensate the decrease of the accuracy according to the displacement difference and to derive the proper mixing ratio for maintaining the shape during the free-form panel curing. In this study, molds were made using paraffin that is a recyclable phase change material. Concrete Panel is usually produced from Portland cement, dead burn magnesia, phosphate, borax and fine aggregate. In this study, four mixing ratios of FCP were selected after each material was blended to determine the proper blending ratio of the fluidity phase, the water absorption rate and the water content of the test piece. FCP was fabricated on the basis of the selected four compounding ratios and thickness and error rate were measured. Based on the error rate of the measured FCP, the quality standard was satisfied among the four compounding ratios.

• Korean Journal of Agricultural Science
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• v.47 no.4
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• pp.1057-1069
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• 2020

For most upland crops in Korea, underground water is used to ensure an adequate water supply. Thus, surface water storage tanks are needed to supply surface water from reservoirs or streams. This study discusses the design, manufacture and monitoring of a water storage tank capable of reliably supplying water to crops and preventing the inflow of floating debris. The study was conducted in an apple orchard in Yesan-gun, Chungcheongnam-do in Korea. Based on the water requirements of the crops and size of the orchard, a required flow volume of about 0.6 ㎥·h-1 was determined, along with a surface water storage tank capacity of 1.2 ㎥. Following a comparison with other materials, stainless steel (STS) was used to construct the water tank. The tank was designed to provide 14 hours of irrigation, enabling a small-capacity, cost-efficient tank design to be used. A surface water irrigation test was performed using the surface water storage tank. The average surface water irrigation flow rate was 0.00045 ㎥·m-2·h-1. The water quality test showed that the pH, suspended solids (SS), total nitrogen (TN), and total phosphorus (TP) values satisfied the reference values for agricultural water. The test results showed that the surface water storage tank evaluated in this study allows for crop irrigation when there is a lack of groundwater during droughts.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.5
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• pp.363-370
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• 2013

Small scale hydropower is one of most attractive and cost-effective energy technologies for installation within sewage treatment plants. This study was conducted to evaluate the potential of a semi-kaplan micro-hydropower (MHP) system for application to sewage treatment plants with high flow fluctuations and a low head. The semi-kaplan MHP is equipped with an adjustable runner blade, and is without a guide vane, so as to reduce the incidence of mechanical problems. A MHP rating 13.4 kWp with a semi-kaplan turbine has been considered for Kiheung Respia sewage treatment plant, and this installation is estimated to generate 86.8 MWh of electricity annually, which is enough to supply electricity to over 25 households, and equivalent to an annual reduction of 49 ton $CO_2$. The semi-kaplan turbine showed a 90.2% energy conversion efficiency at the design flow rate of 0.35 $m^3/s$ and net head of 4.7 m, and was adaptable to a wide range of flow fluctuations. Through the MHP operation, approximately 2.1% of total electricity demand of Kiheung Respia sewage treatment plant will be achievable. Based on financial analysis, an exploiting MHP is considered economically acceptable with an internal rate of return of 6.1%, net present value of 15,539,000 Korean Won, benefit-cost ratio of 1.08, and payback year of 15.5, respectively, if initial investment cost is 200,000,000 Korean Won.

• Korean Journal of Construction Engineering and Management
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• v.16 no.5
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• pp.86-96
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• 2015

According to previous research, the reason why Design-Build(hereinafter "DB") outperforms Design-Bid-Build(hereinafter "DBB") in terms of cost is due to less change orders(hereinafter "COs"). However, if biddropping was low for DBB resulting into increasing COs, then it would be wrong to conclude that DB is superior due to less COs. Therefore, in order to confirm such misjudgment, the attempt to comprehensively analyze biddropping, COs and delivery method was made as previous methods had analyzed either the relationship between delivery method and COs, or biddropping and COs. This research uses path analysis, which simultaneously compares effect sizes on COs according to delivery method and biddropping based on the project type, and validated the mediator effect. The research proved that DB outperforms DBB due to less COs cannot be validated as biddropping caused a mediator effect by intervening between the delivery method and COs for specific project types. Therefore, the mechanism of delivery method acts on COs through biddropping was established. Also, the identity of biddropping was investigated in a different perspective from previous research. Based on this result, this research is expected to help determine a delivery method by considering the mediator effect of specific projects and evaluate performance.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.1
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• pp.64-71
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• 2015

Silica fume is generally adopted as admixture for Ultra High Strength Concrete (UHSC) owing to its remarkable contribution to the strength and durability but increases significantly the fabrication cost of UHSC. Accordingly, this study investigates the replacement of silica fume by blast furnace slag (BS) and fly ash (FA) in order to lower the fabrication cost of 80MPa-UHSC. To that goal, experiment is conducted on the mix proportions of mortar in terms of its binder combination, water-to-binder ratio (W/B) and unit binder content. Based on the experimental data, a mix design of concrete is derived and its properties are verified. The results reveal that a W/B of 21% and unit binder content of $720kg/m^3$ are appropriate to achieve 80MPa-UHSC using a binder composed of 60% of OPC, 30% of BS and 10% of FA. The properties of the corresponding UHSC are seen to be satisfactory with a slump flow of 715mm and compressive strength of 97MPa at 28days. The application of the binder combination derived in this study is analyzed to reduce the cost by 50% of binder compared to the mix using silica fume while realizing equivalent performance.

• Journal of the Korea Society of Computer and Information
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• v.25 no.2
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• pp.221-229
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• 2020

As the cosmetics beauty industry grows into a key next-generation industry, the establishment of an industrialization center is needed, but failure to verify the adequacy and feasibility of the investment could lead to financial burdens. In this study, the project costs and facilities of an industrial center are reviewed to analyze its economic feasibility based on the cost estimates, revenue estimates, estimated profit or loss calculations, and estimated operating cash flows. The profit estimation criteria were analyzed by applying 90 per cent of expected orders for research projects (24 billion won) and 12 per cent of rental rates for testing equipment (4.5 billion won for construction), and the benefit/cost ratio is higher than 1.02 per cent and the net present value is higher than '0' won, and the internal rate of return is also more than 5.06 per cent for all three analytical methods. Therefore, in order for the construction of a cosmetics beauty industrialization center to be economically feasible, it is necessary to maintain research project orders of more than 90 percent and return on equipment rent of more than 12 percent, and a strategic approach is needed to diversify business profits.

• Korean Journal of Construction Engineering and Management
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• v.12 no.2
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• pp.101-110
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• 2011

Because bridges can cause more significant damage than other infrastructure a certain level of safety shall necessarily be secured for users. As most of bridges' service life become 20-30 years there will be a dramatic increase in the maintenance and repair cost but the budget and human resource will be limited. Asset management technique can help the efficiency in maintenance and budget management with the limited resource. For its application, there must be a way to evaluate how bridges provide service to users. The level of service can be quantified by a performance measure. This study introduces performance measures and an evaluation process for the determination of level of service. The evaluation results will be used as a fundamental information in the determination of maintenance/repair/management targets and in the decision making process of the bridge asset management.

• Journal of the Korea Institute of Building Construction
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• v.10 no.2
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• pp.81-88
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• 2010

Under the law of Management of Apartment Complexes, the Apartment Supplier should satisfy the demands of residents for the repair of defects found in Apartment Housing. But in the cost of defect repair, the expense of resident complaints is not included, and only the actual defect repair expense is counted. So in this study, the actual use state of defect deposits for 3 years after moving in is analyzed based on the actual use data of 39 apartment complexes. The study shows that more than 50% of defect repair deposits are spent to satisfy expenses arising from complaints by residents. This is not only caused by irrational demands of residents, but also by the adoption of a stopgap policy by Apartment Suppliers.

• Korean Journal of Construction Engineering and Management
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• v.10 no.4
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• pp.111-118
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• 2009

This study is to analyze the performance of SWH(Solar Water Heating) and GSHP(Ground Source Heat Pump) systems by evaluating their energy efficiency and LCC(Life Cycle Cost) as being applied to the OO hall as a selected building in the Army. The OO hall, used as bathrooms, dining rooms, accommodations and offices, has reinforced concrete structure system with three floors above the ground and one underground, and its total floor area is approximately 2,917$m^2$. Two energy simulations are conducted to predict the yearly cooling and heating energy of the selected building: One is for analysis of an air-conditioning energy consumption using the e-Quest program, and another is for two new-renewable energy facilities as a water heating source using the RETScreen. The installed capacity of two new-renewable energy facilities is determined according to the 5% level of total standard construction cost. As a briefly result, SWH system is more energy-effective than GSHP system. Considering the break-even point, it is expected that SWH can take only 3 years 11 months to pay for itself in savings while the investment of GSHP can be recovered in more than 16 years 6 months.

• Journal of Korean Society of Forest Science
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• v.102 no.4
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• pp.506-514
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• 2013

This study examined the feasibility on the construction of a wood industrialization service center for a wood industry cluster establishment in Jeollanam-do. Construction of the wood industrialization service center is based on a discount rate of 3.5%, an investment period of 4 years, a business operations period of 16 years and an investment cost of 24600 million won; the total amount of the net present value, the cost-benefit ratio and the internal rate of return were assumed to be 2.579 million won, 2.51%, and 10.1%, respectively. In addition, the production inducement coefficient, the induced production effect, the income-induced coefficient, the income inducement effect, the employment inducement coefficient, and the employment inducement effect were estimated 1.4345, 35287 million won, 0.1655, 4000.7 million won, and 0.4665, 1,145 people, in the effects of the wood related industries using the multi-regional input-output model, respectively. Financial independence of operating income to cover its own costs incurred in accordance with the operating project might be practicable.