• Journal of Advanced Marine Engineering and Technology
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• v.34 no.2
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• pp.250-258
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• 2010

A numerical analysis of reactive flow in a liftoff flame is accomplished to elucidate the characteristics of flame propagation velocity and volume integral of reaction rate with the variation of nozzle diameter and fuel injection flow rate in a liftoff flame consisted with fuel rich region, fuel lean region and diffusion flame region. The increase of fuel injection velocity enhances flame propagation velocity for the selected three nozzle diameter(d=0.25, 0.30, 0.35mm), but its effect on the flame propagation velocity is not much greater than 4.3%. The increase of fuel flow rate is directly and linearly related with the volume reaction rate and so the volume reaction rate, not the flame propagation velocity, might be considered to accommodate the variation of fuel flow rate in a liftoff flame.

• Fire Science and Engineering
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• v.31 no.5
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• pp.19-27
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• 2017

The effects of changes in area and location of fire source, fire growth rate, and volume of compartment on the major fire characteristics, including heat release rate, in closed compartment fires were examined. To this end, a fire simulation using Fire Dynamics Simulator (FDS) was performed for ISO 9705 room with a closed opening. As main result, it was found that the changes in the area and location of fire source did not significantly affect the thermal and chemical characteristics inside the compartment, such as maximum heat release rate, total heat release, maximum temperature at upper layeras well as species concentrations. However, increasinthe fire growth rate and volume of compartment resulted in increase of the maximum heat release rate and total heat release, decrease in the limiting oxygen concentration and increase in the maximum CO concentration. Finally, a methodology for the application of fire growth curves to closed compartment fires was proposed by deriving the correlation of the maximum heat release rate expressed as a function of the fire growth rate and the volume ratio of compartment based on the ISO 9705 room.

• Journal of Korean Society of Transportation
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• v.30 no.3
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• pp.31-41
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• 2012

Due to growing interests in the distribution of traffic volume through information dissemination such as VMS and traffic broadcasting system, the research on the driver's reaction and effect of the traffic report has continued. In this study, we propose a methodology, which estimates the traffic volume of diversion and the consequential diversion rate using FTMS data and TCS data, and the estimation is based on the analysis of the national highway and IC, in which real-time FTMS and TCS data are established. We also calculate the diversion rate of actual targeted sections and analyze the changes in time and spatial diversion rate. In this study, we define a deviation (considering a deviation due to dynamic properties of traffic conditions) found when the outflow traffic volume is temporarily higher than the average outflow traffic volume on a relevant time slot after providing traffic information. The diverting volume is considered to be caused by the traffic information, and the study determines the ratio of traffic volume on highways to that of route diversion as the diversion rate. The analysis on changes in the diversion rate in accordance with the time flow, the initial change in the diversion rate on upstream IC that first acquires the report on the traffic congestion is significant. After that, the change in the diversion rate on upstream IC affects the route diversion on downstream IC with spatial and time flow, and this again leads the change in upstream IC. Thereby, we confirmed that there is a feedback-control circulation system in the route diversion.

• Archives of Plastic Surgery
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• v.36 no.5
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• pp.617-622
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• 2009

Purpose: Endoscopic transnasal correction of the blowout fractures has many advantages over other techniques. But after removal of packing material, there were some patients with recurrence of preoperative symptoms. Authors tried to make a quantitative anterograde analysis of orbital volume change over whole perioperative period which might be related with recurrence of preoperative symptoms. Methods: 10 patients with pure medial wall fracture(Group I) and 10 patients with medial wall fracture combined with fracture of orbital floor(Group II) were selected to evaluate the final orbital volume change, who took 3 CT scans, pre-, postoperative and 4 months after packing removal. By multiplying cross - section area of orbit in coronal view with section thickness, orbital volume were calculated. Then, mean orbital volume increment after trauma, mean orbital volume decrement after endoscopic correction and volume increment after packing removal were found out. And we tried to find correlations between type of fracture, initial correction rate and final correction rate. Results: The mean orbital volume increment of the fractured orbits were 7.23% in group I and 13.69% in group II. After endoscopic surgery, mean orbital volume decrement were 11.0% in group I and 12.46% in group II. Mean volume increment after packing removal showed 3.10% in group I and 6.50% in group II. The initial correction rate(%) showed linear correlation with final correction rate(%) after packing removal. And there were negative linear correlation between increment percentage of orbital volume by fracture and final correction rate(%). Conclusion: Orbital volume was proved to be increasing after removal of packing or foley catheter and it was dependent upon type of fracture. Overcorrection should be done to improve the final result of orbital blowout fracture especially when there are severe fracture is present.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.719-724
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• 2003

The present experimental study deals with noise reduction and improvements in cooling performance in a plasma display panel(PDP) television (TV). To reduce the noise, the effects of installation parameters are studied. The experimental parameters under investigation are the distance between the fan and the rear case of a PDP TV, position of the strut on the fan, and the fan RPM. The variance of RPM is the most significant facto., and a 250 RPM decrease from 910 RPM causes about 4㏈(A) reduction in the system noise. To increase performance, flow characteristics are investigated by using a visualization technique and measuring the volume flow rate. The visualized results show that a radial direction flow due to large system resistance is significant, and an axial velocity oscillation is observed from the measurement of the volume flow rate. To prevent both a radial direction flow and an axial velocity oscillation, sponges are inserted in the space between f3n and the rear case. Inserted sponges improve the volume flow rate of cooling fans up to 32% since they convert a radial direction flow to an axial direction flow. Also an axial velocity oscillation with large amplitude and low RPM disappears. Increasing volume flow rate causes the PDP TV to improve its cooling performance. Additionally the same volume flow rate can be obtained with a decreased fan speed due to the inserted sponge. Noise reductions of 4.2 ㏈(A) at the rear and 1.1 ㏈(A) at the front of the TV are obtained by the decreased RPM. An increase of 10% of the volume flow rate is also achieved by inserting sponges.

• Journal of Environmental Science International
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• v.12 no.12
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• pp.1235-1243
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• 2003

Under controlled conditions in an environmental chamber, 24 experiments were performed to compare the ability of a Variable-Air-Volume/Bypass Filtration System(VAV/BPFS) to remove indoor pollutants and to conserve energy with the ability of conventional Variable Air Volume(VAV) system. The specific conclusions of this paper were; first, the VAV/BPFS was more efficient than the VAV system in removing particulate matter, TVOC, and target VOCs. The total effective removal rate of PM for the VAV/BPFS was two times as high as that of the VAV system. The total effective removal rate of TVOC for the VAV/BPFS was 20 percent higher than that of the VAV system. Also each target VOC concentration was reduced by using the VAV/BPFS. Second, clean air delivery rate was increased by using VAV/BPFS due to additional filtration rate. Otherwise, the VAV/BPFS decreased outdoor supply air rate above 25 percent relative to the rate of VAV system. Third, total energy consumption by the VAV/BPFS was lower than that of the VAV system during the period with indoor thermal load, occupied time. The energy saving of the VAV/BPFS ranged from 11 to 16 percent. The VAV/BPFS improves indoor air quality more efficiently than the VAV system, and it reduced energy consumption. Retrofitting the VAV system with the VAV/BPFS was easy The use of VAV/BPFS is, therefore, recommended far buildings with VAV system as well as for buildings at designing stage.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.4
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• pp.564-573
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• 2001

The mechanical properties of short carbon/glass fiber reinforced polypropylene are experimentally measured as functions of fiber content and nozzle diameter. Also, these properties are compared with the survival rate of reinforced fibers and fiber volume fraction using image analysis after pyrolytic decomposition. The survival rate of fiber aspect ratio as well as fiber volume fraction is influenced by injection processing condition, the used materials and mold conditions such as diameter of nozzle, etc. In this study, the survival rate of fiber aspect ratio is investigated by nozzle size variations in injection/mold sides. It is found that the survival rate of glass fiber is higher that the survival rate of glass fiber is higher than that of carbon fiber. Both tensile modulus and strength of short-fiber reinforced polypropylene are improved s the fiber volume fraction and nozzle diameter are increased.

• Resources Recycling
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• v.8 no.4
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• pp.3-10
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• 1999

An experimental study for manufacturing lightweight aggregates from sewage sludge ash of sewage treatment facilities was carned out in senses of sludge disposal and utilization. In case of SA alone, aggregates with S.G. 1.67 was obtained at sintering temperature of $1250^{\circ}C$, and heating rate affects little to volume expansion rate and volume expansion rate was decreased more or less by heating time. In case of adding 10 wt% of RFCC to SA, lightweight aggregates with S.G. 1.07 was obtained and volume expansion rate was increased by heating time. The optimum adding amounts of RFCC to manufacture lightweight aggregates was 10wt% and the condition that shows maximum volume expansion rate was $20^{\circ}C/min$ of heating rate, $1250^{\circ}C$ of sintering temperature and 50 mmutes of heating time. According to adding amounts of RFCC, Compressive strength of sample results in 30 wt% RFCC>SA>20 wt% RFCC>10 wt% RFCC.

• The KSFM Journal of Fluid Machinery
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• v.1 no.1 s.1
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• pp.41-48
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• 1998

This study was carried out to investigate the effect of design parameters on the volume flow-rate and the noise level and to finally find the optimal design variables. Eighteen cross-flow fans were designed by the method of orthogonal array, and the flow-rate and the noise level were measured. These data were analyzed by the neural network system. The effects of eight design variables(scroll exit angle, scroll arc length et al.) on the fan performance and the noise level were valuated and discussed. This experiment shows that the design solutions suggested by neural network system may increase its volume flow-rate and reduce noise simultaneously.

• Journal of Korean Society of Forest Science
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• v.113 no.3
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• pp.361-371
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• 2024

This study was conducted to develop models of the xylem volume utilization rate and merchantable log utility rate of the Japanese larch (Larix kaempferi [Lamb.] Carrière), a major commercial species in South Korea. To develop these models, models were fitted together for the xylem volume utilization rate and merchantable log utility rate to the total stem volume. Data on the logs bucked by cut-to-length usage in the forestry field were used for modeling, and the tree diameter at breast height (DBH) and small-end diameter of the last log were used as major predictor variables. Considering the difference in the bucking rate between all logs and solely long-length logs, the models for merchantable log utility rate were classified into two types: short- and long-length logs as well as only long-length logs. Consequently, the models were significantly developed, and the predicted values showed high accuracy within the range of observed values. The tables for bucking rate by cut-to-length log usage were finally provided by applying the models of the xylem volume utilization rate and merchantable log utility rate. Because the bucking rate for all logs and long-length logs can be easily calculated with the easy-to-use DBH and the required small-end diameter of the last log, the developed models are highly expected to be applicable for predicting the timber assortment using the cut-to-length log usage.