• Journal of ILASS-Korea
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• v.28 no.1
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• pp.1-9
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• 2023

In the cylinder of gasoline direct injection engines, the spray targeting from injectors is of great significance for fuel consumption and pollutant emissions. The automotive industry is putting a lot of effort into improving injector targeting accuracy. To improve the targeting accuracy of injectors, it is necessary to develop models that can predict the spray targeting positions. When developing spray targeting models, the most used technique is computational fluid dynamics (CFD). Recently, due to the superiority of machine learning in prediction accuracy, the application of machine learning in this field is also receiving constant attention. The purpose of this study is to build a machine learning model that can accurately predict spray targeting based on the design parameters of injectors. To achieve this goal, this study firstly used laser sheet beam visualization equipment to obtain many spray cross-sectional images of injectors with different parameters at different injection pressures and measurement planes. The spray images were processed by MATLAB code to get the targeting coordinates of sprays. A total of four models were used for the prediction of spray targeting coordinates, namely ANN, LSTM, Conv1D and Conv1D & LSTM. Features fed into the machine learning model include injector design parameters, injection conditions, and measurement planes. Labels to be output from the model are spray targeting coordinates. In addition, the spray data of 7 injectors were used for model training, and the spray data of the remaining one injector were used for model performance verification. Finally, the prediction performance of the model was evaluated by R² and RMSE. It is found that the Conv1D&LSTM model has the highest accuracy in predicting the spray targeting coordinates, which can reach 98%. In addition, the prediction bias of the model becomes larger as the distance from the injector tip increases.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.9
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• pp.569-576
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• 2016

The objective of this study was to investigate, using a numerical method, the fuel injection targeting for improving the combustion performance in a HSDI diesel engine. In this work, the ECFM-3Z model was applied as the combustion model, and the injection mass, inclined spray angle, and injection timing were varied for the study on the targeting of fuel spray. The results of this work were compared in terms of cylinder pressure, rate of heat release, and exhaust emissions characteristics. It was found that the cylinder pressure increased when the injection timing was advanced, and the rate of heat release increased when more fuel was injected into the piston bowl. In addition, $NO_x$ emission increased owing to the increase in the rate of heat release. On the other hand, CO and soot emissions decreased because of the improvement in combustion performance.

• Journal of ILASS-Korea
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• v.26 no.4
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• pp.189-196
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• 2021

Spray drift of agricultural nozzles has become a big issue because it causes low precision targeting and environmental pollution. In order to reduce the spray drift, study spray characteristics of agricultural nozzles is virtually important. In this study, shadowgraph and Mie-scattering visualization techniques were used to study the macroscopic spray and atomization characteristics of an agricultural nozzle. PDPA was used to measure the atomization characteristics of spray. The injection pressure is set to 1 bar, 3 bar and 5 bar, which covers the working range of the nozzle. For the PDPA experiment, 75 points were measured in an area of 160 mm × 120 mm at 10 mm intervals directly below the nozzle to grasp the overall atomization characteristics of the spray. It was found that the spray width and sheet width showed a linear correlation. As the injection pressure increased, the sheet expansion in the 0-degree direction and the sheet swing in the 90-degree direction jointly promoted the breakup of the sheet. In addition, the area close to the central axis had a large droplet velocity, and since a large droplet velocity promoted atomization of spray, the area close to the central axis had a smaller spray droplet diameter than the left and right regions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.270-275
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• 2016

The characteristics of the fuel quantity, injection rate and macro spray development was investigated under a range of diesel fuel temperatures. The actual injection quantity decreased despite the same signal of the injection start and injection duration as the fuel temperature decreased. The injection rate measurements confirmed that the actual injection commencement was delayed and the actual injection duration was shortened under lower fuel temperature conditions, which explains why the injection quantity decreased. Spray tip penetration with a lower fuel temperature was longer than that with a higher fuel temperature due to the deteriorated atomization. As a pre-test for the combustion experiment under low temperature conditions, piston targeting with pilot injection was accomplished, which showed that the fuel droplet from pilot injection was introduced into the crevice area. This suggests that the pilot injection quantity and timing should be chosen with careful consideration for actual applications.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.4
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• pp.444-453
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• 2014

A throttleable rocket engine enables operational possibilities such as the docking of spacecraft, maneuvering in a certain orbit and landing on a planet's surface, altitude control, and entrance to atmosphere-less planets. Thus, throttling methods have long been researched. However, dual-manifold injectors, which represent one throttling method, have been investigated less than others. In this study, dual-manifold and single-manifold injectors were compared to determine the characteristics of dual-manifold injectors. Also, the effects of gas injection were investigated with various F/O ratios. To investigate the characteristics, mass flow rate, spray pattern, spray angle, and droplet size were measured. The spray angle and droplet size were captured by indirect photography. About 30 images were taken to assess the spray patterns and spray angle. Also, 700 images were analyzed to understand the droplet distribution and targeting area, moving to the right from the centerline with 1.11-cm intervals. The droplet size was obtained from an image processing procedure. From the results, the spray angle showed two transition regions, due to swirl momentum in the swirl chamber regardless of the F/O ratio. The droplet size showed similar trends in both dual-manifold and single-manifold injectors except in the low mass flow rate region. In the case of the dual- manifold injector, the spray cone was not fully developed in the low mass flow rate region due to low angular momentum in the swirl chamber.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.25 no.3
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• pp.56-64
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• 2012

Objectives : This study was performed in order to investigate an immediate improvement effect of nasal obstruction after having patient with chronic rhinitis use nasal spray in nasal cavity after distilling Korean medicine, satisfaction for its fragrance and irritation and its effect continuance time. Methods : A questionnaire was performed for an immediate therapeutic effect of nasal spray 1, 2 and 3 weeks later after using spray by targeting 13 patients who used Korean medicine distillate spray for over 3 weeks among the patients who visited Sangji University Korean Medicine Hospital and whose symptoms were determined as chronic rhinitis and for whom Korean medicine distillate spray was prescribed. 3 weeks later after using spray, a questionnaire was performed for fragrance, irritation and continuance effect of Korean medicine. Immediate therapeutic effect being felt right after spraying was also surveyed and symptom scores was expressed from 10 to 0 and on the assumption that nasal obstruction symptom just before spraying was 10 points, symptom score after spraying was surveyed. In case of evaluation of satisfaction, satisfaction for fragrance and irritation of nasal spray was evaluated by scale based on full score of 5 point from 'very satisfied=5', 'satisfied=4', 'average=3', 'unsatisfactory=2' and 'very unsatisfactory=1', respectively. Effect continuance time after spraying was surveyed by dividing it into within 5 minutes, within 5-10 minutes, within 10-30 minutes and over 30 minutes. All the data was statistically analyzed by Friedman Test that is non-parametric test of Paired t-test and descriptive statistics. Results : Total surveyed patients were 13 persons including 6 males and 7 females and total average age was represented to be $27.1{\pm}17.7$ years old. Score of immediate nasal obstruction improvement effect at 1st week was $6.3{\pm}2.4$ points, at 2nd week $5.7{\pm}2.5$ points and at 3rd week $5.5{\pm}2.5$ points and when comparing 1st week, 2nd week and 3rd week statistically, p value was 0.047<0.05 and from this, it could be seen that the longer spray was used, the more was improvement effect represented with slight significance. In case of fragrance and irritation, both of its score was represented to be high as average $4.0{\pm}1.08 $points and average $4.4{\pm}0.8$ points, respectively. Effect continuance time below 10 minutes was represented in 8 persons who accounted for 61.5%. Conclusions: Immediate improvement effect of nasal obstruction being felt by the patients by using Korean medicine nasal spray could be confirmed and by having the patients use such spray for 3 weeks continuously, it could be realized that such effect was sustained and satisfaction for fragrance or irritation of Korean medicine nasal spray was significant. However, rather short sustained time was considered to be unsatisfactory and this shortcomings is required to be improved in the future.

• Transactions of the KSME C: Technology and Education
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• v.2 no.2
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• pp.73-80
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• 2014

Drug delivery in human upper airway was studied by the numerical simulation of oral airflow. We created an anatomically accurate upper airway model from CT scan data by using a medical image processing software (Mimics). The upper airway was composed of oral cavity, pharynx, larynx, trachea, and second generations of branches. Thin sliced CT data and meticulous refinement of model surface under the ENT doctor's advice provided more sophisticated nasal cavity models. With this 3D upper airway models, numerical simulation was conducted by ANSYS/FLUENT. The steady inspiratory airflows in that model was solved numerically for the case of flow rate of 250 mL/s with drug-laden spray(Q= 20, 40, 60 mL/s). Optimal parameters for mechanical drug aerosol targeting of predetermined areas was to be computed, for a given representative upper airways. From numerical flow visualization results, as flow-rate of drug-laden spray increases, the drag spray residue in oral cavity was increased and the distribution of drug spray in trachea and branches became more homogeneous.

• International Journal of Automotive Technology
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• v.6 no.5
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• pp.437-444
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• 2005

Unburned hydrocarbon (UBHC) emissions from gasoline engines remain a primary engineering research and development concern due to stricter emission regulations. Gasoline engines produce more UBHC emissions during cold start and warm-up than during any other stage of operation, because of insufficient fuel-air mixing, particularly in view of the additional fuel enrichment used for early starting. Impingement of fuel droplets on the cylinder wall is a major source of UBHC and a concern for oil dilution. This paper describes an experimental study that was carried out to investigate the distribution and 'footprint' of fuel droplets impinging on the cylinder wall during the intake stroke under engine starting conditions. Injectors having different targeting and atomization characteristics were used in a 4-Valve engine with optical access to the intake port and combustion chamber. The spray and targeting performance were characterized using high-speed visualization and Phase Doppler Interferometry techniques. The fuel droplets impinging on the port, cylinder wall and piston top were characterized using a color imaging technique during simulated engine start-up from room temperature. Highly absorbent filter paper was placed around the circumference of the cylinder liner and on the piston top to collect fuel droplets during the intake strokes. A small amount of colored dye, which dissolves completely in gasoline, was used as the tracer. Color density on the paper, which is correlated with the amount of fuel deposited and its distribution on the cylinder wall, was measured using image analysis. The results show that by comparing the locations of the wetted footprints and their color intensities, the influence of fuel injection and engine conditions can be qualitatively and quantitatively examined. Fast FID measurements of UBHC were also performed on the engine for correlation to the mixture formation results.

• KSBB Journal
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• v.28 no.2
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• pp.115-122
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• 2013

Volatile flavor compounds of Chamaecyparis obtuse essential oil were extracted by simultaneous steam distillation extraction (SDE) and supercritical fluid extraction (SFE) and analyzed by GC-MS. A total of 48 and 50 components were identified in essential oil by SDE and SFE, respectively. Monoterpenes, oxygenated monoterpenes, sesquiterpenes, oxygenated sesquiterpenes, and diterpenes in essential oil by SDE were 37.24, 10.9, 9.61, 0.22, and 0.22%, respectively. In the case of SFE, they were 19.1, 23.3, 22.66, 1.31, and 10.57%, respectively. Antioxidant activities were increased with the increase of essential oil up to $80{\mu}L/mL$, irrespective of extraction method. Especially, when the essential oil concentration extracted by SDE was increased from 20 to $80{\mu}L/mL$, the antioxidant activity was increased from 10.5 to 55.1%. However, over $80{\mu}L/mL$ of essential oil, an equilibrium state was maintained. In the case of essential oil extracted by SFE, it was decreased compared to that of SDE. For the improvement of atopic dermatitis, various cosmetics such as an ato-cide soap, ato-cide spray, and ato-cide lotion containing essential oil extracted by SFE were tested. About over 90% was useful for the improvement of atopic dermatitis after 4 weeks of clinical trial targeting 40 female adults. These results demonstrate that ato-cide soap, ato-cide spray, and ato-cide lotion containing essential oil extracted by SFE could be used in functional cosmetics.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.3
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• pp.141-147
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• 2012

A direct injection diesel engine with large amount of exhaust gas recirculation was used to investigate low temperature diesel combustion. Pilot injection strategy was adopted in low temperature diesel combustion to reduce high carbon monoxide and hydrocarbon emissions. Combustion characteristics and exhaust emissions of low temperature diesel combustion under different pilot injection timings, pilot injection quantities and injection pressures were analyzed. Retarding pilot injection timing, increasing pilot injection quantity and higher injection pressure advanced main combustion timing and increased peak heat release rate of main combustion. As a result of these strategies, carbon monoxide and hydrocarbon emissions were reduced. Soot emission was slightly increased with retarded pilot injection timing while the effect of pilot injection on nitrogen oxides emission was negligible under low combustion temperature condition. Spatial distribution of fuel from the spray targeting visualization was also investigated to provide more insight into the reason for the reduction in carbon monoxide and hydrocarbon emissions.