• Transactions of Materials Processing
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• v.18 no.8
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• pp.589-595
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• 2009

The hot forming process of an exhaust CAM for vessel engine was designed by finite element(FE) simulation and experimental analysis. An aim of process design was to achieve the near-net shaped CAM forgings by hot forging process. Based on the compression test results of the low alloy steel, power dissipation map was generated using the the dynamic materials model(DMM). From the map, the initial heating temperature was determined as 1200oC. FE analysis was simulated to predict the formation of forging defects and deformed shape with different forging designs. Optimum process design suggested in this work was made by comparing with the CAM for vessel engine manufactured by actual forging process.

• Current Optics and Photonics
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• v.1 no.2
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• pp.125-131
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• 2017

We propose a new graphical method for selecting a pair of optical and housing materials to simultaneously athermalize and achromatize an LWIR optical system. To have a much better opportunity to select the IR glasses and housing materials, an athermal glass map is expanded by introducing the DOE with negative chromatic power. Additionally, from the depth of focus in an LWIR optical system, the tolerable housing boundary is provided to realize an athermal and achromatic system even for not readily available housing material. Thus, we can effectively determine a pair of optical and housing materials by reducing the thermal shift to be less than the depth of focus. By applying this method to design a night vision camera lens, the chromatic and thermal defocuses are reduced to less than the depth of focus, over the specified waveband and temperature ranges.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.417-420
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• 2009

The hot forming process of a CAM for vessel engine was designed by finite element (FE) simulation and experimental analysis. An aim of process design was to achieve the near-net shaped CAM forgings by hot forging process. Based on the compression test results of the low alloy steel, deformation processing map was generated using the superposition approach between the dynamic materials model (DMM) and flow stability and/or instability criteria. From the processing map, the initial heating temperature was determined as $1200^{\circ}C$. FE analysis was simulated to predict the formation of rolling defects and deformed shape with different forging designs. Optimum process design suggested in this work was made by comparing with the CAM for vessel engine manufactured by actual forging process.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.5 no.1
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• pp.9-16
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• 1996

This is an experimental investigation of the temperature generated in a cutting tool during the machining of stainless steel. The temperature results from the wear of the cutting tool are considered in order to investigate the relation between cause and effect of these factors. This possibility has been tested using a thermocouple technique to record temperature vs. time curves for a variety of cutting conditions. This is done by employing a thermocouple inserted on the tool tip near the major cutting edge. Temperature distributions are calculated using finite element method and compared to the contour maps measured by an optical system. It suggests that the temperature gradients and the tool performance will be dependent on certain facotrs in tool geometry when cutting this material.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.383-386
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• 2006

Subsurface temperature is affected by heat advection due to groundwater advection. Temperature-depth profile can be perturbed especially when there are significant vertical groundwater flux caused by external force such as injection or extraction. This research is to clarify the change of subsurface temperature distribution when the 40m x l0m sandy aquifer is stimulated by two different vertical flux($case1:\;{\pm}10^{-5}m^3/s,\;case2:\;{\pm}4{\times}10^{-5}m^3/s$) using a program called HydroGeoSphere. The resulting temperature distribution contour map shows pumping causes vertical attraction of water from deeper and warmer place which result in rising up isotherm. Additionally more injection/extraction rate, more vertical groundwater flux leads to faster Increase in temperature near the pumping well.

• The Journal of Korea Robotics Society
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• v.13 no.4
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• pp.213-219
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• 2018

In this paper, we introduce a target position reasoning system based on Bayesian network that selects destinations of robots on a map to explore compound disaster environments. Compound disaster accidents have hazardous conditions because of a low visibility and a high temperature. Before firefighters enter the environment, the robots notify information in advance, such as victim's positions, number of victims, and status of debris of building. The problem of the previous system is that the system requires a target position to operate the robots and the firefighter need to learn how to use the robot. However, selecting the target position is not easy because of the information gap between eyewitness accounts and map coordinates. In addition, learning the technique how to use the robots needs a lot of time and money. The proposed system infers the target area using Bayesian network and selects proper x, y coordinates on the map based on image processing methods of the map. To verify the proposed system, we designed three example scenarios based on eyewetinees testimonies and compared time consumption between human and the system. In addition, we evaluate the system usability by 40 subjects.

• Journal of Animal Science and Technology
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• v.51 no.4
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• pp.337-342
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• 2009

The feasibility of reutilization of magnesium ammonium phosphate (MAP) or struvite slurry recovered from the process through microwave irradiation was studied in this experiment. For this purpose, 4 different operations were performed with or without Mg source addition and different levels of MAP recycled in a batch reactor. Dissolution rate of MAP, ${NH_4}^+$ elimination pattern and physicochemical changes of MAP during microwave irradiation were also studied. The result showed that only 33% orthophosphate ($PO_4-P$) and 27% $NH_4-N$ removal occurred without adding any external Mg source (run A), whereas 87% $PO_4-P$ and 40% $NH_4-N$ removed when 1.0 M ratio of $MgCl_2$ (run B) was added based on $PO_4-P$ in influent. Although the addition of 1.0 molar ratio of microwave irradiated MAP (Run C) removed lower $PO_4-P$ and $NH_4-N$ than 1.0 M $MgCl_2$ (run B), $PO_4-P$ removal was double when compared with no Mg addition (run A). Addition of half MAP and half $MgCl_2$ (run D) showed the similar removal efficiency (88% $PO_4-P$ and 35% $NH_4-N$) with sole $MgCl_2$ addition (run B). Based on these results, the reutilization of MAP irradiated by microwave would be a feasible way to enhance the removal efficiencies of N and P, as well as curtail the Mg chemical usage. Track study showed that $NH_4-N$ gradually increased at initial stage of microwave irradiation of MAP, and then started eliminating from liquor as temperature increased over $45^{\circ}C$. Dissolution rate of ${PO_4}^{-3}$ during microwave irradiation was proportional to the initial MAP concentration, having $0.0091x^{0.6373}$ mg/sec. It was found from the scanning electron microscope (SEM) study that physical structure of MAP crystal started breaking down into small cube granules within very short time by electromagnetic vibration force during microwave irradiation and then gradually melted down into solution.

• Food Science and Preservation
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• v.15 no.6
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• pp.804-809
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• 2008

Modified atmosphere packaging (MAP) was assessed in terms of extending the shelf life of Solidago virgaurea spp. gigantea. In June 2005 Solidago virgaurea spp. gigantea were harvested from Ulleung Island, packaged in $30\;{\mu}m$ PP, $30\;{\mu}m$ Antifogging-OPP, $30\;{\mu}m$ LDPE, $18\;{\mu}m$ Macroperforated-HDPE, $60\;{\mu}m$ nylon/PE, or $85\;{\mu}m$ PVC/PE film, then stored at 4, 10 or $20^{\circ}C$ for up to 14 days. The $O_2$ concentration decreased to $9{\sim}10%$ in the PP and A-OPP packaging, to $12{\sim}16%$ in LDPE packaging, and to 2% in nylon/PE and PVC/PE packaging at $10^{\circ}C$. The $CO_2$ concentration increased to 5% at $10^{\circ}C$ in PP, A-OPP and LDPE packaging, but increased consistently in the nylon/PE and PVC/PE packaging. Weight loss was markedly reduced by all MAP films except M-HDPE, and which was enhanced with decreasing storage temperature. The soluble solids and pH were not affected by the packaging material at $4^{\circ}C$ and $10^{\circ}C$, but were affected at $20^{\circ}C$. The highest score for sensory qualities (appearance, color and overall acceptability) was obtained for vegetables stored at $4^{\circ}C$ in PP films. Our results show that MAP using PP films and $4^{\circ}C$ storage can effectively maintain the quality of Solidago virgaurea spp. gigantea.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.183-186
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• 2000

The high temperature deformation behavior of spray-formed Al-19wt%Si-1.87wt%Mg-0.085wt.%Fe alloy was studied by torsion testing in the strain rate range of 0.001-1 sec-1 and in the temperature range of 300-500 $^{\circ}C$. The relationship between stress temperature and strain rate is expressed using the Power law. the behavior of dynamic recrystallization is showed in 300-35$0^{\circ}C$, 1-0.1sec-1 and the behavior of dynamic recovery is showed in 450-50$0^{\circ}C$, 0.01-0.001sec-1 The size of Si particles is mall when the temperature is low and the strain rate is high. The strain rate sensitivity(m) and the apparent activation energy(Q) indicate the dependence on strain rate and temperature for flow stress respectively. The hot ductility is high when m is high and Q is low. The maps of strain rate sensitivity and apparent activation energy suggest the optimum processing conditions.

• Atmosphere
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• v.31 no.5
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• pp.525-537
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• 2021

Black ices on road surfaces in winter tend to cause severe and terrible accidents. It is very difficult to detect black ice events in advance due to their localities as well as sensitivities to surface and upper meteorological variables. This study develops a methodology to detect the road sections vulnerable to black ice with the use of road surface temperature data obtained from a mobile road weather observation vehicle. The 7 experiments were conducted on the route from Nam-Wonju IC to Nam-Andong IC (132.5 km) on the Jungang Expressway during the period from December 2020 to February 2021. Firstly, temporal road surface temperature data were converted to the spatial data with a 50 m resolution. Then, the spatial road surface temperature was normalized with zero mean and one standard deviation using a simple normalization, a linear de-trend and normalization, and a low-pass filter and normalization. The resulting road thermal map was calculated in terms of road surface temperature differences. A road ice index was suggested using the normalized road temperatures and their horizontal differences. Road sections vulnerable to black ice were derived from road ice indices and verified with respect to road geometry and sky view, etc. It was found that black ice could occur not only over bridges, but also roads with a low sky view factor. These results are expected to be applicable to the alarm service for black ice to drivers.