• The Journal of the Acoustical Society of Korea
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• v.16 no.5
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• pp.76-82
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• 1997

The paper describes simulations and experimental results using a measuring system which utilizes the acoustic holographic method in order to exactly estimate an absolute position of a sound source. The measuring surface is installed to satisfy with a far field to the sound source and is composed of linear arrayed seven microphones. A measurement is simultaneously recorded by a reference microphone setting up a neighbour sound source and the linear arrayed seven microphones which are moved to the same interval. An absolute position of sound source is estimated by the cross-spectrum method to the received sounds between a reference and the measuring microphones. Phase differences of each microphone and time delays during scanning are compensated to the reference microphone and the measuring time of the first column. An optimal interval for each microphone in the measuring surface is decided by a numerical simulation. A source signal makes use of a sinusoid, and S/N ratio is 30dB in the experiment. The optimal microphone's interval in the simulation and the experiment is decided in order to satisfy with the Nyquist space sampling condition related to the wave length of 2kHz sinusoid. Mainlobe width of a estimated 3D hologram in the case of 2kHz source signal is decreased to 87% and 30% in comparison to 500Hz and 1kHz, and then a valid of simulation results is confirmed. Therefore, we verified a utilization of the study for a sound source estimation using 3ㅇ acoustic holographic method.

• Journal of Korea Port Economic Association
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• v.36 no.1
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• pp.91-104
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• 2020

Seosan-Daesan Port is the sixth largest port in Korea, and it promotes port infrastructure expansion, regular route development, overseas marketing, and port incentive systems for continuous growth. In addition, the port is planning to open a regular car ferry line to Weihai, China. This study aims to provide useful research data for effective decision making by analyzing the feasibility of opening the Chinese (Weihai) car ferry route of Seosan-Daesan Port. Currently, some car ferry routes that operate between Korea and China are open at Incheon Port, the Port of Pyeongtaek-Dangjin, and the Port of Gunsan. In order to estimate the volume of cargo that will be created when the car ferry route from Seosan-Daesan Port to Weihai opens, this research analyzes the domestic cargo volume from the Chungcheongnam-do region, where Seosan-Daesan Port is located, to each of the regions where the other ports are located. We estimated the volume of cargo that can be transported on the car ferry from Seosan-Daesan Port to Weihai. As a result, by 2020, about 76,000 passengers and about 50,000 tons of cargo could be created. Suggestions were made for policy strategies that would revitalize passenger numbers and secure the cargo volume of the car ferry, along with a discussion of and the port incentive system.

• Journal of Korean Society of Forest Science
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• v.104 no.3
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• pp.476-487
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• 2015

This study was conducted to analyze the potential of Baekdu-daegan Mountain System (BDMS) in the Republic of Korea for World Heritage inscription and undertook preliminary global comparative analysis. UNEP WCMC global datasets, World Heritage global gap analyses and thematic studies conducted by IUCN were reviewed to see if the BDMS could have been identified within these as a priority area for World Heritage. With respect to potential Outstanding Universal Value this study found that the case for BDMS was weak. The BDMS lies within biogeographic regions which are already represented on the World Heritage List and at a global scale its natural values do not stand out. It was emphasized that a more fine scale analysis of the values should be undertaken. The BDMS stands out at a global scale in terms of the degree of contiguity between protected areas along its length and the legal and institutional frameworks established in the Republic of Korea. The BDMS has potential for a trans-national and serial properties along the full length of the BDMS, if two Koreas agree to work together.

• Korean Journal of Construction Engineering and Management
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• v.16 no.3
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• pp.91-100
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• 2015

An increase in energy such as natural gas, coal, oil, has occurred to a large amounts of environment impact emissions, it is necessary to reduce in the construction industry for the energy consumption. To encourage remodeling project in developed countries of the majority, on the basis of this, remodeling project in the construction industry has grown to a large amount. Results of analysis of the research related to the advanced remodeling, analysis of the economic validity in accordance with the production and process and building elapsed years of selection alternative of remodeling there has been a problem that has not been properly reflected. In this study, a decision support model that can simultaneously choose the most cost-effective and energy-efficiency alternative. Developed process model, generates a "Remodeling Solution" that combines the renewable energy equipment and envelope system, energy performance evaluation of the application of international standards(ISO-13790, DIN V 18599), perform the economic evaluation through LCCA(Life Cycle Cost Analysis) technique, circulated evaluation and configured to output the optimal Remodeling Solution. The results of applying the model developed in the case, it was confirmed that it is possible to select a choice of cost-effective energy-saving alternative. Then, developed model through this study, it is expected to be able to help highly effective remodeling alternative to selecting by decision-makers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.127-132
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• 2016

This study evaluated the economic value of the development of a new variety of Citrus unshiu using the income approach, Net Present Value (NPV), Internal Rate of Return (IRR), and Benefit/Cost (B/C) ratio. The new variety of Citrus unshiu was developed by the national institute of horticultural and herbal science in Korea, rural development administration. The technological evaluation of the development of a new variety of Citrus unshiu can be used to improve the efficiency and practicality of the development of a new variety of citrus. From the research results, the technological value of development of a new variety of Citrus unshui was evaluated at 109,455(discount rate=8%, minimum), 195,040(discount rate=4%, maximum), and 145,375(discount rate=6%, average) million won. The IRR was 51.4%, which was greater than the discount rate(4~8%). The NPV was evaluated at 145.3 billion won(discount rate=6%, average), 195.0 billion won(discount rate=4%, maximum) and 109.4 billion won(discount rate=8%, minimum), all of which were greater than 0. The B/C ratio was evaluated at 60.9(discount rate=6%, average), 81.3(discount rate=4%, maximum) and 46.1(discount rate=8%, minimum), all of which were greater than 1. Therefore, the economic validity of the development of a new variety of Citrus unshiu was identified by this technological evaluation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.74-79
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• 2017

The fire extinguishing performance of hybrid nozzle systems is improved by injecting an extinguishing agent concentrically into the target site and, in this study, water mist is used as a water curtain to confine the droplets of the agent. In this study, we numerically investigated the effect of the foundation angle and injection pressure on the performance of a hybrid nozzle by evaluating the mean radius of the volume fractions of the agent and water mists. An experiment involving a water mist nozzle was carried out to validate the numerical method and then the droplet behaviors, e.g., stochastic collision, coalescence and breakup, were calculated with 2-way interaction Discrete Particle Modeling (DPM) in the steady state for the hybrid nozzle system. The mean radius of the water mists increased by about 40 %, whereas that of the agent decreased by about 21 %, when the injection pressure was increased from 30 bar to 60 bar. In addition, the mean radius of the agent increased by about 24 % as the foundation angle of the hybrid nozzle head increased from $30^{\circ}$ to $60^{\circ}$. As a result, it can be inferred that the injection angle and pressure are important factors for hybrid water mist designs.

• Journal of the Korean Institute of Intelligent Systems
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• v.7 no.3
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• pp.43-54
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• 1997

Knowledge acquisition is one of the most difficult problems in designing fuzzy systems. As application domains of fuzzy systems become larger and more complex, it is more difficult to find the relations among the system's input- outpiit variables. Moreover, it takes a lot of efforts to formulate expert's knowledge about complex systems' control actions by linguistic variables. Another difficulty is to define and adjust membership functions properly. Soin conventional fuzzy systems, the membership functions should be adjusted to improve the system performance. This is time-consuming process. In this paper, we suggest a new approach to design a fuzzy system. We design a fuzzy system using two neural networks, Kohonen neural network and backpropagation neural network, which generate fuzzy rules automatically and construct inference network. Since fuzzy inference is performed based on fuzzy relation in this approach, we don't need the membership functions of each variable. Therefore it is unnecessary to define and adjust membership functions and we can get fuzzy rules automatically. The design process of fuzzy system becomes simple. The proposed approach is applied to a simulated automatic car speed control system. We can be sure that this approach not only makes the design process of fuzzy systems simple but also produces appropriate inference results.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.873-883
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• 2014

This study proposed an estimation method of allowable wave height for loading and unloading of the ship considering ship motion that is affected by ship sizes, mooring conditions, wave periods and directions. The method was examined validity by comparison with wave field data at pier $8^{th}$ in Pohang new harbor. The wave field data obtained with wave height of 0.10~0.75m and wave period of 7~13s in ship sizes of 800~35,000ton when a downtimes have occurred. On the other hand, the results of allowable wave height for loading and unloading of the ship in this method have obtained with wave heights of 0.19~0.50m and wave periods of 8~12s for ship sizes of 5,000, 10,000 and 30,000ton. Thus this method well reproduced the field data respond to various a ship sizes and wave periods. And the results of this method tended to decrease in 16~62% when have considered long wave, and it is decreased in 0~46% when didn't consider long wave than design standards in case of the ship sizes of 5,000~30,000ton, wave period of 12s and wave angle of $75^{\circ}C$. The allowable wave heights for loading and unloading of the ship proposed by design standards are didn't respond to various the ship sizes and wave periods, and we have found that the design standards has overestimated on smaller than 10,000ton.

• Journal of Energy Engineering
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• v.21 no.3
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• pp.265-270
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• 2012

The delay in the construction permit for the building, which obtained the approval of business proposal, may lead to a difference in the maintenance cost ranging between 20% and 30% in the neighborhood where the residents moved in, along with the new project under construction in the surrounding area amidst rigorous regulations that aim to promote energy-saving and the heightened interest of the public in energy conservation, and such problem would become the major source of serious public complaints. Thus, the energy-saving plan needs to be prepared when the approval is granted to the business plan. In order to prevent public complaints or ensure effectiveness of government's energy plan, it may be effective to apply the energy-saving plan based on current standards upon the award of construction permit when two years have elapsed since the date of the scheduled commencement of construction or when the start of construction is delayed as stipulated in the Article 18 of the Enforcement Decree of Housing Act. If the energy-saving plan and related technologies are merely the parts of license and permit process without fully serving their purposes and functions, it would be waste of time to deploy a lot of workforce and review and seek consultation. The government or owners of buildings need to fully understand the energy-saving aspects and exert effort to enhance the energy efficiency of buildings.

• Journal of the Korean Wood Science and Technology
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• v.38 no.6
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• pp.470-479
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• 2010

In this study, the visual grading based on the visual characteristics and structural timber bending test were conducted for domestic yellow poplar dimension lumber. Structural performance of domestic yellow poplar dimension lumber was conducted through the evaluation of strength and stiffness. Visual grading rule of yellow poplar dimension lumber did not exist in Korea. Visual grading of yellow poplar dimension lumber was performed according to the NSLB (Northern Softwood Lumber Bureau) standard grading rules including several hardwood dimension lumber. The allowable bending stress was calculated from the results of a visual grading. Compared with NDS (National Design Specification), the yellow poplar dimension lumber showed enough strength for structural uses. In addition, the visual grading was performed according to the KFRI (Korea Forest Research Institute) grading rule to calculated allowable bending stress and to evaluated the feasibility. The yellow poplar was classified into the pine groups by the KFRI criteria regulated by specific gravity. Allowable bending stress based on weibull distribution had became highly than KFRI criteria, as No. 1 (10.0 MPa), No. 2 (7.4 MPa) and No. 3 (4.1 MPa). And the availability of yellow poplar dimension lumber for structural uses had been confirmed. The Modulus of Elasticity (MOE) of domestic yellow poplar dimension lumber had not met the NDS and KFRI criteria. However, for the use of domestic yellow poplar, average values of MOE which obtained through this test were suggested as design value for domestic yellow poplar. Design values were supposed No. 1, 2 (9,000 MPa) and No. 3 (8,000 MPa).