• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.2
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• pp.27-32
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• 2000

The main objective of this work is to investigate the effect of ambient conditions on the spray behavior and spray characteristics of high-pressure fuel injector. For this purpose, the effects of ambient pressure and temperature on the spray characteristics have been studied by applying the analysis of visualization system and phase Doppler particle analyzer. In this experiment, the visualization of spray behavior was performed under various ambient gas conditions and injection parameters such as gas temperature, ambient pressure, injection pressure of injector, and axial distance from the nozzle tip. Based on the investigation results, the spray tip penetration and spray width decrease with the increase of ambient gas pressure in the spray chamber. The effects of the spray parameters on the microscopic characteristics of gasoline spray were discussed.

• Journal of the korean Society of Automotive Engineers
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• v.9 no.1
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• pp.40-48
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• 1987

A Mini-Dilution Tunnel is described as a scaled down comparision of a Standard Tunnel. The paper presents the result of experimental investigations on measuring the particulate emission of a diesel engine in a Mini and a Standard Dilution Tunnel. The result offers a contribution to understanding about the influence of several parameters including dilution ratios, mixture temperatures, mixture conditions, filter temperatures, and flow conditions. In the experiment either increasing the filter temperature and mixture temperature at a fixed dilution ratio or increasing the dilution ratio at a fixed filter temperature and mixture temperature resulted in a decrease in the total particulate mass. These changes in total particulate mass were attributed to the changes in the soluble organic fraction of the particulate sample. Also, mass differences between the Mini and the Standard Dilution Tunnel for the same engine conditions were within approximately 15% of each other.

• Journal of the Korean Society of Safety
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• v.18 no.3
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• pp.22-28
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• 2003

This study proposes the construction of chaos simulator for cutting characteristics evaluation of non-ferrous metals. Also this paper aims to find the optimal cutting conditions of diamond turning machine by measuring surface form and roughness to perform the cutting experiment of non-ferrous metals, which are aluminum, with diamond tool. As well, according to change cutting conditions such as fled rate, using diamond turning machine to perform cutting processing, by measuring cutting force and surface roughness and according to cutting conditions the aluminum about cutting properties. Trajectory changes in the attractor indicated a substantial difference in fractal characteristics. Constructed chaos simulator in this study can be used for cutting characteristics evaluation of non-ferrous metals.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.284-287
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• 2004

Micro-structures fabricated by X-ray lithography are largely affected by doses, development conditions and other factors. For these reasons, PMMA development rates and its surface profiles under various development conditions were obseued. Development rates were measured in the rage from 1 to 6 $kJ/cm^3$ using the 9C1 white beamline of Pohang light source(PLS). In this experiment, we observed that development rates of stacked PMMA sheet using Si filter were relatively higher than that of not using Si filter. Furthermore, development rates in condition with the acoustic agitation(1 MHz, 3.67 $W/cm^3$) were twice than that in dipping condition with $35^{\circ}C$ developer considering the PMMA sheets-substrate bond strength

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.06a
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• pp.319-326
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• 2001

The sliding wear characteristics of carbon steel castings were Investigated using a ball on disk type tester. The experiment was conducted using high carbon steel wire rods as ball material and carbon steel castings as disk material and different operating conditions, at room temperature under a lubrication and dry conditions. The results showed that the carbon steel castings appeared average wear volume Is lowed after annealing under a lubrication conditions and wear curve linear Increased. The specific wear rate of carbon steel castings Increased with wire diameter lubrication and dry also Increased 125 times In Ory. The sliding wear mechanism were Investigated due to fatigue wear lubrications and abrasive wear dries also wire Included fatigue and abrasive wear by plastic flow.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.21-22
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• 2015

The maximum power point of a photovoltaic array alters with changing atmospheric conditions, temperature conditions, shadow conditions, so it is required to track maximum power point. As much as MPPT(Maximum Power Point Tracking) is important in photovoltaic systems, many MPPT techniques have been developed. In this paper, several major existing MPPT methods are comparatively analyzed and novel hybrid MPPT algorithm is proposed. The proposed hybrid MPPT algorithm is developed in combination with traditional MPPT methods to complement each other for improving performance and mitigating partial shading effects. The proposed algorithm is validated by using PISIM simulation tool and experiment in 3kW system.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.663-668
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• 2006

In the present paper, a single stage fresh water generator was modified and extended to 2 effect desalination system. The inlet temperatures of hot water and feed water were selected as experiment parameters to get operating conditions and fresh water generating rates. The impacts of these parameters on operating conditions and fresh water generating rates were described in detail.

• Journal of the Semiconductor & Display Technology
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• v.18 no.4
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• pp.46-50
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• 2019

In this paper, We used the regression model of machine learning for improve the print quantity problem when which print scaffold with 400 ㎛ pore using FDM 3d printer. We have difficult to experiment with changing all factors in the field. So we reduced print quantity by selected two factors that most impact the pore size. We printed and measured scaffold 5 times under same conditions. We created regression model using scaffold pore size and print conditions. We predicted pore size of untested print condition using the regression model. After print scaffold with 400 ㎛ pore, we printed scaffold 5 times under same conditions. We compare the predicted scaffold pore size and the measured scaffold pore size. We confirmed that error is less than 1 % and we verified the results quantitatively.

• Journal of Korean Society on Water Environment
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• v.27 no.5
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• pp.617-624
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• 2011

In order to confirm the creation of the OH radical which influences to RNO bleaching processes, it experimented using laboratory reactor of dielectric barrier discharge plasma (DBDP). The experiments performed in about 4 kind process variables (diameter of ground electrode, diameter of discharge electrode, diameter of quartz tube and effect of air flow rate) which influence to process. In order to examine optimum conditions of design factors as shown in Box-Behnken experiment design, ANOVA analysis was conducted against four factors. The actual RNO removal at optimized conditions under real design constraints were obtained, confirming Box-Behnken results. Optimized conditions under real design constraints were obtained for the highest desirability at 1, 1 mm diameter of ground and discharge electrode, 6 mm diameter of quartz tube and 5.05 L/min air flow rate, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.11
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• pp.82-91
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• 1996

In this study, we put our object to carry out adaptive modeling of cutting process in turning system, and to find out the optimal cutting conditions to maximize material removal rate under some constraints. We used a back-propagation neural network to model the cutting process adaptively and a genetic algorithm to find out optimal cutting conditions. The experimental results show that a back-propagation neural network could model the cutting process effciently, and optimized cutting conditions for maximizing the material removal rate were obtained through the adaptive process model and genetic algorithms. Therefore, the proposed approach can be applied to the real machining system.