• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.11
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• pp.1177-1184
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• 2011

Gas-to-Solid (GTS) technology is composed of three stages: hydrate production, transportation, and regasification. For efficient operation of regasification plants, it is crucial to predict the temperature and flow rate of hot water necessary to dissociate the hydrate pellets. Dissociated gas escaping from the pellet surface, when in contact with hot water, will alter the flow field and consequently alter the heat transfer rate. Methane hydrate pellet dissociation characteristics in low- to moderatetemperature water were investigated by taking images of the changes in the hydrate pellets' shapes in a pressurized reactor and measuring the total time required for complete melting of the pellets. The effects of water temperature, hydrate conversion rate, and flow speed on the dissociation completion time were also investigated. Bubbling gas released from the pellet surface induced a secondary flow that enhanced the heat transfer rate and thus decreased the dissociation time. It was also found that a considerable flow rate was needed to significantly decrease the dissociation time.

• Journal of Energy Engineering
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• v.24 no.3
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• pp.13-19
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• 2015

The wood pellet is standardized of woody type fuel which of small cylindrical shape that is produced compress wood remnants in process of woody processing. The pellet is critical energy which expects to increase of the amount used in future. It consumes fuel which of home, common facilities stove and boiler, district heating, and CHP, etc. This study was to develop a movable pellet manufacturing equipment that can be mounted on a truck. The pellet production volume is approximately 309kg per hour, daily output is about 2ton. One days work based on the expected revenue of approximately \268,000 feasibility is considered sufficient.

• Journal of Energy Engineering
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• v.23 no.3
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• pp.203-210
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• 2014

In this study, combustion behaviour were to analyze by comparing experimental data against predicted values. In developing pellet boiler performance, various factors such as combustion chamber shape, input air velocity, the amount of fuel, temperature, and fuel characteristics need to be analyzed. Analytical model using a numerical method is useful to overcome time and cost consuming by practical experiment. By controlling feeding rate of fuel, flue gas composition and temperature distribution obtained form experiment were compared with predicted values using FLUENT(ANSYS, Inc., Southpointe). Measurement were in good agreement with model predictions : with 0.60 % for $CO_2$ 0.73% for $O_2$ when compared with independent data sets.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.45 no.8
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• pp.22-31
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• 2016

• Journal of Korean Society of Forest Science
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• v.98 no.4
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• pp.426-434
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• 2009

This study was carried out to derive the most optimal production process for the wood fuels(chip and pellet), by collecting cost data on each procedure through the life cycle assessment approach, and to compare between the profitability and efficiency, from the view points of producers and consumers, irrespectively. The costs accounted in this analysis were based on the opportunity cost. The results show that wood chips are cheaper than wood pellets in production costs. In respect to the process with the lowest production cost, while wood chips should be to crush collected residues into pieces on the spot for merchandizing, wood pellets need to be transported to manufactory for pelletizing. The study findings also include that the profits, which is estimated by subtracting expenses from gained sale revenue, were a bit higher for wood chips than wood pellets. Additionally, the price ratio of wood pellets to wood chips for getting the same caloric value appears to be 1.27. Despite of economic benefits of processing wood chips, there are several problems in practice. For producers, there is a possible increase in not only transportation cost for conveying crushers to the dispersed places, but storage cost due to the lack of the marketplaces in the immediate surroundings. For consumers, on the other hand, there are some challenging issues, such as bulky storage facility requirement, additional labor for fuel supplement, frequent ashes disposal, and decomposition in summer and freezing in winter caused by wood chips' own moisture.

• Journal of the Korean Wood Science and Technology
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• v.41 no.4
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• pp.346-357
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• 2013

In this study, it was conducted to produce wood pellets using domestic forest thinning residues and examine their quality according to Korean pellet quality standard. Raw materials were composed of larch and mixed broad leaves species. Based on the small-end diameter (6 cm), they were classified into four different types of raw materials such as LM (larch with middle diameter), LS (larch with small diameter), MM (mixed broadleaf with middle diameter), and MS (mixed broadleaf with small diameter). After crushing and drying process, wood pellets were produced by a ring-die type pelletizer using each raw material. Wood pellets made from four different types of raw materials were tested for their quality such as calorific value, moisture content, ash content, inorganic matters and so on. As results of quality analysis, the calorific values of all wood pellets were higher than 198 kcal/kg, and satisfied with the first grade of Korea wood pellet standard. The ash content was slightly increased after pelletizing. Mechanical durability of wood pellets was highly dependent on the types of raw materials. The quality differences among wood pellets were turned out due to different physical and chemical characteristics of raw materials even though the same pelletizing condition was applied.

• Journal of the Korean Wood Science and Technology
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• v.42 no.3
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• pp.318-326
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• 2014

This study was conducted to investigate the potential of non-used forest biomass residues as raw materials for making wood pellets with additives such as wood tar and starch and to evaluate fuel characteristics of the pellets. Wood tar, a by-product provided from the carbonization process of wood, could be a suitable additive for wood pellet production due to its higher calorific value and lower hazardous heavy metals, such as cadmium and mercury, compared to woody biomass. When the wood tar (10 wt%) was added, the calorific value was increased from 4,630 kcal/kg (wood pellet without additive) to 4,800 kcal/kg (wood pellet with additive). With the increase of additive amount into wood pellet, the length and individual density of wood pellet increased. In addition, bulk density of the pellets was increased, whereas the fine content was decreased. Consequently the overall productivity of wood pellets was improved by adding 2 w% additives into wood pellets; the percentage of productivity increase was 5.9% and 4.9% for adding starch and wood tar, respectively.

• Journal of the Korean Wood Science and Technology
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• v.34 no.3
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• pp.15-21
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• 2006

The objective of this research is to develop the technique for carbonization of wood pellet and analyze a possibility for the utilization of carbonized wood pellet. The properties of wood pellet charcoals, such as density, yield, elemental composition, higher heating value, and methyleneblue adsorption, were analyzed. Wood pellet was made of sawdust of Hyunsasi-poplar, Japanese larch, Korean pine, Korean red pine, and Jolcharn-oak (serrate oak), respectively. The high density charcoal ($0.5{\sim}0.7g/cm^3$) was yielded from densified wood pellet. The carbon contents and calorific values of wood pellet charcoals were increased with the increase of carbonization temperature. The methyleneblue adsorptivity of wood pellet charcoal was similar to that of wood charcoal.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.4
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• pp.324-329
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• 2010

Fuel rods using in nuclear power plants consist of uranium dioxide pellets enclosed in zirconium alloy(zircaloy) tubes. It is vitally important for the pellet surface to remain free from pits, cracks and chipping defects after it is loaded into the tubes to prevent local hot spots during reactor operation. This paper investigates the feasibility study for detecting surface flaws of pellets contained within nuclear fuel rod through X-ray tomography simulation. Reconstructed images used by parallel and fan-beam filtered back projection method were presented and confirmed the accessibility between simulation data and MPS(missing pellet surface) image data.

• Korean Journal of Plant Resources
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• v.27 no.1
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• pp.60-71
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• 2014

This study was conducted to identify the potential of rape stalk as a raw material for biorefinery process of rape flower. At first, rape stalk (RS) was immersed in distilled water (DW), acetic acid (AA), oxalic acid (OA), sulfuric acid (SA) and sodium hydroxide (SH) solutions, and the content of reducing sugars liberated from immersed RS was analyzed. Glucose, xylose, arabinose and sucrose were detected varying with the immersion type. In particular, 1% AA-immersion of RS for 72 hr was the most effective conditions to liberate glucose from RS. Secondly, the RS residues were used for elementary analysis and fabrication of fuel pellets. In addition to the solution type, concentration of immersion solutions (0%, 1%, 2%) and immersion time (24, 72, 120 hr) were used as experimental factors. The contents of nitrogen, sulfur and chlorine reduced effectively through the immersion of RS in DW, AA and OA solutions. For properties of RS-based pellets, bulk density and higher heating value of RS-based pellets greatly increased with the immersion of RS, and the qualities were much higher than those of the A-grade pellet of the EN standards. Ash content decreased remarkably through the immersion of RS, and was satisfied with the A-grade pellet standard. Durability was negatively affected by the immersion of RS, and did not reached to B-grade of the EN standard. In conclusion, acid immersion of RS can be a pretreatment method for the production of fuel pellet and bioethanol, but use of the immersed RS for the production of high-quality pellets might be restricted due to low durability of immersed-RS pellets. Therefore, further studies, such as investigation of detailed immersion conditions, fabrication of mixed pellets with wooden materials and addition of binders, are needed to resolve the problems.