• Korean Journal of Construction Engineering and Management
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• v.19 no.6
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• pp.124-134
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• 2018

Despite the many advantages of modular housing, low preference for modular housing for consumers who are familiar with RC structure leads to high construction cost of modular housing. The cost of modular buildings is about 130% of that of RC structures, so it is urgent to secure economical efficiency of modular buildings. Therefore, in this study, after calculating the savings amount of modular housing by type of construction work, economic analysis was conducted from a long - term perspective. In order to carry out the research, the authors compiled and analyzed the material cost, labor cost, and expenses incurred by each type of work by reclassifying the statement of the modular housing into the factory production and the site installation. After that, Pareto diagrams were created to find a core work that is included in the cost ratio of about 80%, and selected it as a cost reduction subject. Based on the assumption that the market size of domestic modular housing is similar to the level of modular advanced countries such as Japan and European countries, six cost reduction methods were set up that reflects the characteristics of the modular construction method and used for the expert interviews. Cost saving potentials in percentage from the interview were converted to the amount of savings that can be achieved by each type of method when applying the method. Finally, the findings of the study are expected to suggest long-term directions for technical development for modular construction and cost savings.

• Journal of the Korean Association of Geographic Information Studies
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• v.20 no.2
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• pp.47-59
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• 2017

This study aims to assess offshore wind energy resources around Jeju Island using the InVEST Offshore Wind model. First the wind power density around the coast of Jeju was calculated using reanalysis data from the Korean Local Analysis and Prediction System (KLAPS). Next, the net present value (NPV) for the 168MW offshore wind farm scenario was evaluated taking into consideration factors like costs (turbine development, submarine cable installation, maintenance), turbine operation efficiency, and a 20year operation period. It was determined that there are high wind resources along both the western and eastern coasts of Jeju Island, with high wind power densities of $400W/m^2$ calculated. To visually evaluate the NPV around Jeju Island, a classification of five grades was employed, and results showed that the western sea area has a high NPV, with wind power resources over $400W/m^2$. The InVEST Offshore Wind model can quickly provide optimal spatial information for various wind farm scenarios. The InVEST model can be used in combination with results of marine ecosystem service evaluation to design an efficient marine spatial plan around Jeju Island.

• Journal of Environmental Science International
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• v.26 no.2
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• pp.231-238
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• 2017

Rapid industrial development has led to a serious problem of pollution in the industrial sector. With the increasing social need for environmental protection, research on air pollution prevention equipment for reducing pollutants in industrial processes is actively being undertaken. The deterioration of existent, installed facilities, their increased emission rates, and the strengthening of the effluent quality standards make complying with permissible emission standards difficult. In fact, installing new electric precipitators or complementing existent facilities is inevitable. The expansion and complementation of the installed electrical precipitators have led to improvements in dust collection efficiency, shorter working times, and lower costs. Because of its easy installation and simple manufacturing process, the production method with the discharge electrode of an electric precipitator is widely used. The following conclusions were reached by classifying discharge electrodes into four types based on the production method and mutually comparing them by their dust collection efficiency. None of the four types used in this study were damaged by impact. However, we were able to confirm some strain from the compression sites of both type A and type B. Both type B and type C are expected to have greater dust collection efficiencies than the other models due to their large vibration transmissibility. Moreover, the high vibrational energy is expected to cause rapping damage during its operation. Particularly, in the case of type B, some of the strain was found at the end of the compression site. The coupling schemes of both type C and type D are out of vibration transmissibility. On the other hand, the ability to maintain straightness and solidity of the side is regarded as outstanding and stable. Type D has outstanding on-site workability, considering the presence of locking, structural stability, and work conditions. From these experiments, we determined that type C is the most ideal connection method of discharge electrode, considering its construction period of renovation. Type C is inferior to type D with regard to on-site workability. However, type C has outstanding dedusting transmission with regard to the straightness, solidity maintenance, and vibration of shearing stress.

• Journal of the Korea Organic Resources Recycling Association
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• v.20 no.4
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• pp.61-74
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• 2012

Industrial complexes in Korea have been vigorously established by economic development plan and development policy of industry in 1960s. Recently, Korean government has promoted Eco Industrial Park (EIP) project to recycle by-products and wastes in industrial park In this study, we analyzed the physical and chemical properties for the sludges discharged from A industrial complex. And we investigated the economic feasibility and environmental impact of sludge to energy facilities. The analysis results indicated that the petrochemical industry were 92% in sludge production, the highest treatment amount was landfill, followed by incineration and recycling and then ocean disposal. Wastewater sludge and process sludge samples are collected and analyzed to use as basic data on economic feasibility and environmental impact. Weighted average heating value of sludge samples was 3,891kcal/kg. Based on this data, installation and operation costs, operation returns of operating the drying facility are estimated, compared with cogeneration facility. And this study examines how the payback period of each simulation(total 8 case) with the important parameter changes. As a result, it was found that what needs the shortest payback period is 3years with connection of drying facility and cogeneration facility based on the government's financial subsidy system.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.20 no.4
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• pp.43-61
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• 2017

The wetlands are facing environmental changes such as desiccation that occurs with the passage of time and reduced ecosystem services from wetlands in the city. In order to maintain the ecosystem services provided by wetlands in urban areas, a system thinking about the trade-off phenomenon of ecosystem services occurring as the wetlands undergo environmental changes is needed. Therefore, the purpose of this study is to develop strategies for wetland design using system thinking approach to enhance the resilience of ecosystem services degraded by the desiccation of wetlands and other disturbances. The objectives of this study include the system boundary and variables. Second, analyzing the dynamics of wetland design strategy. Third, it analyzes the trade-off phenomenon of ecosystem services in terms of the hydrology, hydric soil, and plants strategies to mitigate these effects. Fourth, wetland basic design to improve the resilience of ecosystem services. A wetland in Abuk-Mountain Neighborhood Park, Miryang-si, Gyeongsangnam-do, has been selected as a case study. Causal loop diagrams(CLDs) are used to analyze feedback in the wetland regime. In summary, hydrology, hydric soil, and plants is suggested as system boundaries to design plan. Design strategies for the wetland focused on robustness, redundancy, rapidity, and resourcefulness as a result of CLD analysis are first proposed in order to effectively maintain the wetland regime over the long term. Secondly, in a section related to hydrology, the CLD results show the trade-offs between provisioning-cultural services and regulating services. In order to control these services, a "water cycling system" has been implemented due to its strength in terms of robustness. The CLDs for hydric soil showed the trade-offs between regulating services and supporting services. An "installation of storm drainage for maintaining water levels" was selected due to the strength offered in terms of redundancy and rapidity. The CLDs for plants showed the trade-offs between provisioning - cultural services and regulating services. In order to control the strategic points, the "planting of indigenous vegetation" was suggested given the strength in terms of redundancy. In this study, a wetland design method is proposed that can improve the resilience of wetland ecosystem services by analyzing the dynamics overtime. The results of this research can theoretically be applied to help restore ecosystem services in wetlands using ecological landscape design. In addition, this study will contribute to reducing maintenance costs by improving wetland resilience.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3121-3129
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• 2009

Conventional marine radar systems utilize pulse radar which is capable of high-power transmissions and is effective for remote detection purposes. A pulse radar is most commonly used on medium or large vessels due to its expensive installation and maintenance costs. I propose the use of a Frequency Modulated Continuous Wave (FMCW) radar system operated at low-power and high-resolution instead of the conventional pulse-radar based system. The transmitted and received signals of the FMCW radar system were theoretically analyzed and radar signal processing design and simulation experiments were performed to detect the range and speed. Intermediate Frequency (IF) signal mixed with virtual transmit and receive signals were generated to perform FMCW radar signal processing simulations where the IF signal underwent noise reduction through a lowpass filter. The maximum frequency was derived through the sample interval of the FFT size instead of using A/D converter. This maximum frequency was used to get the frequency range and frequency speed which were in turn used to calculate the range and speed. The virtual beat frequency generated using MATLAB is utilized to analyze the beat frequency used in the actual FMCW radar system signal processing. The differences in the range and speed of the beat frequency signals are processed and analyzed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.4
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• pp.533-540
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• 2012

The use of wind energy is gaining importance because of its many advantages. Nations worldwide are promoting the installation of wind farms to produce electricity in an attempt to tackle climate change and increasing oil costs. But, wind turbines can generate undesired signals which disturb the performance of military radar systems. Because the current generation of on and off-shore three bladed wind turbines have radar signatures consistent with their very large physical size. So this study considers the options available for the reduction of wind turbine radar signature and presents solutions for each of the main external turbine components. The radar signature reduction approaches are based on existing technologies developed for aerospaces stealth applications. However, the realization of these for the purposes of reduction wind turbine radar signatures is a novel development, particularly in the solutions proposed. This paper is presented techniques which reduce radar signatures of wind turbine. We know that radar signatures of wind turbine reduce by using these techniques.

• Journal of Korea Port Economic Association
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• v.35 no.4
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• pp.85-106
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• 2019

Offshore wind power is a representative renewable energy source and a rapidly growing industry. In Gyeongsangnam-do, offshore wind farms of 461.9MW are being pushed for in the Yokji island and are expected to expand further to over 1GW in the future. Accordingly, ports supporting the storage, assembly, transportation, and installation of offshore wind power equipment are expected to play an important role in the smooth progress of the offshore wind farm development project. Based on previous research and cases in major countries,this study prepared criteria for assessment of ports supporting offshore wind farmsand evaluated ports in Gyeongsangnam-do, which are linked to Yokji island offshore wind farms. The assessment criteria have been subdivided into distance from the offshore wind farm, port entry and exit restrictions, navigational areas, fishery rights factors, additional costs, berth length, depth of berth, size of the port yard, port berth bearing pressure, interference with other cargo, a civil appeal, and relevant industrial aggregation. The ports of Tongyeong, Samcheonpo, Kohyun, Masan, and Jinhae in Gyeongsangnam-do were selected and evaluated. As a result, the port of Tongyoung was superior in terms of distance from the Yokji island offshore wind farm. The ports of Samcheonpo, Masan, and Jinhae were evaluated as excellent in other criteria such as berth length, depth of berth, and so on. This study is expected to be used as a source of basic data for offshore wind power companies and policymakers to select and evaluate the supporting ports of offshore wind farms.

• Imaging Science in Dentistry
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• v.42 no.3
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• pp.139-146
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• 2012

Purpose: An individual surgical stent fabricated from computed tomography (CT) data, called a CT-guided stent, would be useful for accurate installation of implants. The purpose of the present study was to introduce a newly developed CT-guided stent with a simple design and evaluate the accuracy of the stent placement. Materials and Methods: A resin template was fabricated from a hog mandible and a specially designed plastic plate, with 4 metal balls inserted in it for radiographic recognition, was attached to the occlusal surface of the template. With the surgical stent applied, CT images were taken, and virtual implants were placed using software. The spatial positions of the virtually positioned implants were acquired and implant guiding holes were drilled into the surgical stent using a specially designed 5-axis drilling machine. The surgical stent was placed on the mandible and CT images were taken again. The discrepancy between the central axis of the drilled holes on the second CT images and the virtually installed implants on the first CT images was evaluated. Results: The deviation of the entry point and angulation of the central axis in the reference plane were $0.47{\pm}0.27$ mm, $0.57{\pm}0.23$ mm, and $0.64{\pm}0.16^{\circ}$, $0.57{\pm}0.15^{\circ}$, respectively. However, for the two different angulations in each group, the $20^{\circ}$ angulation showed a greater error in the deviation of the entry point than did the $10^{\circ}$ angulation. Conclusion: The CT-guided template proposed in this study was highly accurate. It could replace existing implant guide systems to reduce costs and effort.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.6
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• pp.140-146
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• 2011

As the demand of Variable Message Sign(VMS) has become pervasive in fulfilling the ITS policy, the costs of maintaining the Variable Message Sign operation have also increased. This paper proposes the U-curved figure, the C-curved figure and the ventilated figure type for aerodynamic drag reduction on Variable Message Sign and shows the analysis of aerodynamic drag effects using Flow Analysis. As a results of the flow analysis for right-angled, 45 degrees from side to side and 45 degrees from up or down, the C-curved figure and the ventilated figure type show about 30% aerodynamic drag reduction in all direction. And the U-curved figure type shows vivid aerodynamic drag reduction for right-angled and 45 degree from side to side, but trivial aerodynamic drag reduction for 45 degree from up or down. It is possible to reduce not only the damage on Variable Message Sign due to typhoon because of the aerodynamic drag reduction, but also installation constraints because of lighter Variable Message Sign support structure by appling the proposed structure and analysis in this paper.