• Fire Science and Engineering
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• v.28 no.6
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• pp.52-57
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• 2014

The present study suggests the fundamental method for the prediction time of the fire origin by analyzing the combustion phenomenon of inflammable material in the building structure. The heat release rate (HRR) with time variant is evaluated for the interphone as a inflammable material, which is opted from the fire incidents in the stairwell. the fire dynamics simulator (FDS ver. 6.1) is applied in order to analyze the difference of the smoke inflow time to the downstair from the fire event area with various fire pattern. The results show that the maximum inflow time difference for the case of the interphone made from ABS materials is about 4.93 times with the input conditions of heat flux values and the environment in the FDS for the fixed stairwell which composed of total volume $291.3m^3$, floorage $23.3m^2$ and the height of each floor 2.5 m. This research can be practical information for the application method of simulation scheme with experimental data to the fire Identification.

• Journal of Wetlands Research
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• v.16 no.4
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• pp.433-441
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• 2014

It has been known that sewage containing high-concentration nitrogen affects the efficiency of municipal wastewater treatment plants harmfully. Therefore, research has been actively conducted to treat sewage containing high-concentration nitrogen. The current study has analyzed organic compounds, conducted foaming tests, and operated a laboratory-level nitritation reactor with the subjects of anaerobic digester supernatant and livestock wastewater which are the typical kinds of sewage containing high-concentration nitrogen. According to the results of analyzing organic compounds, soluble inert components form the largest part of anaerobic digester supernatant while particle biodegradable components occupy the most part of livestock wastewater. About the retention time proper for the reaction of nitritation, anaerobic digester supernatant shows 2 days while livestock wastewater indicates 6 days. It seems that the difference in the proper retention time is resulted from the difference of properties in organic compounds and ammonium nitrogen concentration. In addition, livestock wastewater's reactor foam is generated comparatively more than anaerobic digester supernatant's, but it tends to be eliminated faster. It is expected that the findings of this study can be utilized as foundational data afterwards in applying the reaction of nitritation to municipal wastewater treatment plants.

• Resources Recycling
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• v.21 no.2
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• pp.34-40
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• 2012

$Pt_{10}$/C, $Pt_9Mn_1$/C, $Pt_7Mn_3$/C electrocatalysts for Polymer Electrolyte Membrane Fuel Cells(PEMFCs) were synthesized by reduction with HCHO and their activity as a oxygen reduction reaction(ORR) was examined at half cell. The electrochemical oxygen reduction reaction(ORR) was studied by using a glaasy carbon electrode through cyclic voltammetric curves(CV) in a 1 M $H_2SO_4$ solution. The ORR activities of $Pt_9Mn_1$/C were higher than $Pt_{10}$/C, $Pt_7Mn_3$/C. Also potential-current curves of $Pt_9Mn_1$/C at 0.9, 0.8, 0.7, 0.6V for 5minutes respectively were higher than $Pt_{10}$/C, $Pt_7Mn_3$/C. Physical characterization was made by using x-ray diffraction(XRD) and transmission electron microscope(TEM). The TEM images of $Pt_9Mn_1$/C, $Pt_{10}$/C catalysts showed homogenous particle distribution with particle size of about 2.7 nm, 3 nm respectively and then the XRD results showed that the crystalline structure of the synthesized catalysts are seen FCC structure.

• Elastomers and Composites
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• v.40 no.2
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• pp.93-103
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• 2005

In this study, surface treatment of the elastomeric matrix was investigated to develop a substituting material for steel dynamic damper of automobile. The key technology is to get ultra high density elastomeric compound in order to substitute steel dynamic damper. The optimum matrix material(chloroprene rubber) and filler(metal powder) were selected for this. The several properties of elastomeric compound were examined. According to the results, the $t_{s2}$ of filled elastomeric compound was decreased with increasing the filler loading whereas the $t_{90}$ was increased. Also, tensile strength and rebound resilience were decreased with filler loading. To solve the problem of high filler loading, the photo grafting technique was employed on elastomeric matrix. The degree of grafting was determined by FTIR-ATR. Also, the filler surface was modified by chemical etching and the surface morphology was examine by SEM. After chemical treatment of filler, the particle size analyzer was used to examined the particle size, size distribution, and morphology of the modified filler.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.451-457
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• 2019

In this study, the characteristics of coffee grounds were reviewed by making them from solid fuel through heat-drying and oil-drying method. The differences in the higher calorific power by each dried sample were compared. And industrial analysis using the thermogravimetric analyzer was considered for applicability to organic waste and oily samples. Before and after drying, the surface of the specimen was observed with SEM equipment and the ingredients were measured through the EDS equipment. As a result, no other hazardous substances, such as heavy metals, were measured. Next, The differences between thermal decomposition and combustion reactions were considered through the TG and DTG curves. As a result, it is that the oil-dried coffee grounds is longer to burn than the heat-dried coffee grounds. Finally, the combustion gases emitted through the thermogravimetric analyzer were collected and the carbon monoxide and carbon dioxide performed qualitative and quantitative analysis using GC over time.

• Polymer(Korea)
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• v.29 no.6
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• pp.593-598
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• 2005

This work studied the loading capabilities and release behaviors of poly(ethylene-alt-maleic anhydride) (PEMAh)/poly(4-vinyl pyridine) (P4VP) multilayer films formed by the layer-by-layer(LbL) sequential self-assembly method, using Rodamine 6G(R6G) as an indicator. Thickness of the multilayer, and loading and subsequent release behavior of R6G from the multilayer were studied using UV-visible spectroscopy. The amount of R6G loaded in multilayer film increased linearly with increasing film thickness. pH-Sensitive permeability was observed, where lower pH environments increased both release rate and release amount. By additional assembling of PEMAh/poly(ethyleneimine) (PEI) capping layers on top of (PEMAh/P4VP)n multilayers, the release of R6G was better controlled.

• Journal of Wetlands Research
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• v.17 no.3
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• pp.311-319
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• 2015

The Korean government has made progress in its project for sewage distribution in rural areas to ensure the balanced development of the country and its water conservation system. The project for sewage distribution in rural areas was analyzed with the yearly operational results of municipal wastewater treatment plant (MWTP). The sewage characteristics of the MWTP in a rural area changed according to seasonal variations, and the lowest pollution concentrations were obtained in the summer. The treatment efficiency of nutrients in the biological treatment process changed slightly more than the treatment efficiency of organic compounds, and the lowest treatment efficiency was obtained in winter. In addition, the relationship between treatment efficiency and retention time and F/M ratio showed similar results despite seasonal variations. It was considered that sewage characteristics and treatment efficiency changed according to seasonal variations when the treatment process was selected in MWTPs in rural areas. Especially, Maintenance of MWPT is need for the stable treatment efficiency of nutrients in the winter.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.4
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• pp.97-107
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• 2013

Underwater wireless communication systems can be useful for underwater environment observation, catastrophe prevention, ocean resources exploration, ocean organism research, vessel sinking exploration, and so on. However, unlike terrestrial wireless communication, underwater wireless communication should consider factors such as long propagation delay, limited transmission capacity, high bit-error rate due to potential loss in power, ambient noise, man-made noise, multi-path, etc., because of the inherent characteristics of water. Thus, in this paper, we propose a suitable media access control(MAC) protocol that applies a combination of the ALOHA MAC protocol and the CSMA/CA MAC protocol to underwater environment. We further propose a mathematical analysis model to evaluate performance. We also verify performance improvement in the proposed scheme in comparison with existing MAC protocols.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.4
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• pp.19-26
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• 2010

We found that saturated water vapor pressure is the most dominant stress factor for the degradation phenomenon in the package for high-power phosphor-converted white light emitting diode (high power LED). Also, we proved that saturated water vapor pressure is effective acceleration stress of LED package degradation from an acceleration life test. Test conditions were $121^{\circ}C$, 100% R.H., and max. 168 h storage with and without 350 mA. The accelerating tests in both conditions cause optical power loss, reduction of spectrum intensity, device leakage current, and thermal resistance in the package. Also, dark brown color and pore induced by hygro-mechanical stress partially contribute to the degradation of LED package. From these results, we have known that the saturated water vapor pressure stress is adequate as the acceleration stress for shortening life test time of LED packages.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.1022-1027
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• 2011

A diesel engine works in high compression ratio due to injection of diesel fuel after compression of air. Therefore the engine has a high thermal efficiency, while nitrogen oxide is produced a lot in high flame temperature regions. In order to solve the problem this study HHO gas is added into the intake air of the industrial diesel engine. The test conditions are loads of 0%, 50% and 100% and engine speeds of 700 to 1900 rpm. The results show the maximum torque and pressure is increased, fuel consumption, smoke and CO emissions are decreased and NOx emission is remained at same level.