• Journal of Korea Multimedia Society
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• v.17 no.11
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• pp.1313-1324
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• 2014

Korea has high quality level of ICT Technologies, however it still have a long way to go before invigoration of ICT in agriculture industry. The government of Korea supply to agriculture ICT systems, however these are the enclosed type and insufficient the level of connectivity, compatibility, and integrity between ICT systems. Farmers can not share crop information and one system can not use with others in combination. Recently, IoT(Internet of Things) become popular to emphasize the vision of a global internet and ICT industry. The IoT is a critical technology that leads future internet generation. We believe that IoT will change status of agriculture industry and appearance of various agriculture business model. Using IoT technology is provided a platform of opportunities to optimize work processes and efficient use of energy, time and labour in farm. It can automatically control temperature, humidity, sunshine system and so on for optimal growth conditions at greenhouse and plant factory. Growth setting can even be controlled and monitored crop condition and disease by a smartphone app or PC. It is possible to improve quality of farming and farm product. We suggest that construction of IoT platform through open API in agriculture industry.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.10
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• pp.2396-2402
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• 2015

Air compressor, as an essential equipment used in the factory and plant operations, accounts for around 30% of the total electricity consumption in U.S.A, thereby being proposed advanced technologies to reduce electricity consumption. When the fluctuation of the compressed airflow rate is small, the system stability is increased followed by the reduction of the electricity consumption which results in the efficient design of the energy system. In the statistical analysis, the normal distribution, log normal distribution, gamma distribution or the like are generally used to identify system characteristics. However a single distribution may not fit well the data with long tail, representing sudden air flow rate especially in extremes. In this paper, authors decouple the compressed airflow rate into two parts to present a mixture of distribution function and suggest a method to reduce the electricity consumption. This reduction stems from the fact that a general pareto distribution estimates more accurate quantile value than a gaussian distribution when an airflow rate exceeds over a large number.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.6
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• pp.639-647
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• 2014

Due to global warming and depletion of fossil fuels, technologies reducing $CO_2$ emission and increasing fuel efficiency simultaneously are required. An exhaust gas heat recovery system is a technology to satisfy both issues. This study analyses three types of heat exchanger installed on an exhaust pipe. In case of plate type heat exchanger, back pressure rapidly increased and maximum cylinder pressure reduced in high speed and maximum load, and back pressure increased over twice and specific fuel consumption also increased up to 2% which were the highest increasing rate. In case of fin tube type, the amounts of exhaust emissions and specific fuel consumption rate were less than the other two types. The effect of shell and tube was in the middle. Making a decision by only the effect on engine performance, a fin tube type is the best for exhaust heat recovery systems.

• Korean Journal of Materials Research
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• v.27 no.5
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• pp.281-288
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• 2017

In this study, Fe-Ni slag, converter slag and dephosphorization slag generated from the steel industry, and fly ash or bottom ash from a power plant, were mixed at an appropriate mixing ratio and melted in a melting furnace in a mass-production process for glass ceramics. Then, glass-ceramic products, having a basalt composition with $SiO_2$, $Al_2O_3$, CaO, MgO, and $Fe_2O_3$ components, were fabricated through casting and heat treatment process. Comparison was made of the samples before and after the modification of the process conditions. Glass-ceramic samples before and after the process modification were similar in chemical composition, but $Al_2O_3$ and $Na_2O$ contents were slightly higher in the samples before the modification. Before and after the process modification, it was confirmed that the sample had a melting temperature below $1250^{\circ}C$, and that pyroxene and diopside are the primary phases of the product. The crystallization temperature in the sample after modification was found to be higher than that in the sample before modification. The activation energy for crystallization was evaluated and found to be 467 kJ/mol for the sample before the process modification, and 337 kJ/mol for the sample after the process modification. The degree of crystallinity was evaluated and found to be 82 % before the process change and 87 % after the process change. Mechanical properties such as compressive strength and bending strength were evaluated and found to be excellent for the sample after process modification. In conclusion, the samples after the process modification were evaluated and found to have superior characteristics compared to those before the modification.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1795-1800
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• 2014

The temperature change in the biologically activated sludge wastewater treatment process was predicted using the heat transfer model. All incoming and outgoing heats in wastewater treatment processes were considered. Incoming heats included the solar radiation heat, the heat from impeller mechanical energy, and the biochemical heat in the aeration process. Outgoing heats comprised the radiation heat from the waste itself, the heat of vaporization and surface aeration, the wind convection heat and the conduction heat between the surface and aerator. All heats were used as an input to the existing empirical heat transfer model. The heat transfer model of wastewater treatment processes is presented also. To test the validity of the heat transfer model, the operating conditions of the actual wastewater treatment plant were used. The temperatures were compared with the model temperatures. Model predictions were consistent within the $1.0^{\circ}C$.

• International Journal of Fluid Machinery and Systems
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• v.2 no.4
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• pp.286-294
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• 2009

Hydroelectric power plants are known for their ability to cover variations of the consumption in electrical power networks. In order to follow this changing demand, hydraulic machines are subject to off-design operation. In that case, the swirling flow leaving the runner of a Francis turbine may act under given conditions as an excitation source for the whole hydraulic system. In high load operating conditions, vortex rope behaves as an internal energy source which leads to the self excitation of the system. The aim of this paper is to identify the influence of the full load excitation source location with respect to the eigenmodes shapes on the system stability. For this, a new eigenanalysis tool, based on eigenvalues and eigenvectors computation of the nonlinear set of differential equations in SIMSEN, has been developed. First the modal analysis method and linearization of the set of the nonlinear differential equations are fully described. Then, nonlinear hydro-acoustic models of hydraulic components based on electrical equivalent schemes are presented and linearized. Finally, a hydro-acoustic SIMSEN model of a simple hydraulic power plant, is used to apply the modal analysis and to show the influence of the turbine location on system stability. Through this case study, it brings out that modeling of the pipe viscoelastic damping is decisive to find out stability limits and unstable eigenfrequencies.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.24 no.6
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• pp.400-403
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• 2012

Laboratory experiments were conducted for tsunami inundation to an urban area with large building roughness. The waterfront portion of the city of Seaside which is located on the US Pacific Northwest coast, was replicated in 1/50 scale in the wave basin. Tsunami heights and velocities on the inundated land were measured at approximately 31 locations for one incident tsunami heights with an inundation height of approximately 10 m (prototype) near the shoreline. The inundation pattern and speed were more severe and faster in some areas due to the arrangement of the large buildings. Momentum fluxes along the roads were estimated using measure tsunami inundation heights and horizontal fluid velocities. As expected, the maximum momentum flux was near the shoreline and decreased landward. Inundation heights and momentum flux were slowly decreased through the road with buildings on each side. The results from this study showed that the horizontal inundation velocity is an important factor for the external force of coastal structures.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.1
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• pp.46-61
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• 2017

In the present work, the interaction analysis between tsunami bore and onshore bridge is approached by a numerical method, where the tsunami bore is generated by difference of upstream side and downstream side water levels. Numerical simulation in this paper was carried out by TWOPM-3D(three-dimensional one-field model for immiscible two-phase flows), which is based on Navier-Stokes solver. In order to verify the applicability of force acting on an onshore bridge, numerical results and experimental results were compared and analyzed. From this, we discussed the characteristics of horizontal force and vertical force(uplift force and downward force) changes including water level and velocity change due to the tsunami bore strength, water depth, onshore bridge form and number of girder. Furthermore, It was revealed that the entrained air in the fluid flow highly affected the vertical force.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.5
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• pp.385-393
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• 2013

In this paper, the mechanism identification and the avoidance measures on the phenomena of transient acoustic vibration amplified at the water-supply piping system to regulate the steam temperature of the boiler reheater in 500MW class supercritical power plant are presented. The pressure pulsation waves induced by the impeller passing of two feed-water pumps with five blades are coincident with the local acoustic modes of boiler reheater water-supply piping system. There are the phenomena amplified at the peaks of 5X, 10X, 15X and 20X in spectrums of piping vibration, sound pressure, and the feed-water's pressure pulsation waves. The shut-off device is installed in the piping system for the interception of pressure pulsation waves transmitted from two feed-water pumps and the modified design change of the piping layout is applied for the acoustic resonance avoidance. The acoustic natural frequencies are separated from the harmonics of pressure pulsation waves induced by the pump impellers passing through the design change of the span length. The acoustic vibration is gone by resonance avoidance measures. As a result, more than 20 dBA reduction is achieved from 100 dBA to 80 dBA.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.2
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• pp.156-164
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• 2003

STS316L had been used as the structural material for energy environmental facilities, because austenite stainless steels like 316L have superior mechanical properties of which toughness, ductility, corrosion resistant and etc. However, those welded structures are receiving severe damage due to increasing of the aged degradation. Most studies until now have been carried out against fatigue behaviors of weldments, and were not well studied on nondestructive evaluation methods. In this study, the fatigue crack propagation behavior of STS316L weldment usually used for vessels of the nuclear power plant was investigated. Also, the degradation characteristics of 316L stainless steel weldments were evaluated by the ultrasonic parameter such as ultrasonic velocity, attenuation factor and time-frequency analysis. The results of this study can be used as a basic data for the prediction of the fatigue crack life of weldments structures without disjointing or stopping service of structures in service.