• Journal of Biosystems Engineering
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• v.39 no.3
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• pp.205-214
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• 2014

Purpose: Phytosanitary irradiation treatment can effectively control regulated pests while maintaining produce quality. The objective of this study was to establish the best irradiation treatment for mangosteen, a popular tropical fruit, using a Monte Carlo simulation. Methods: Magnetic resonance image (MRI) data were used to generate a 3-D geometry to simulate dose distributions in a mangosteen using a radiation transport code (MCNP5). Microsoft Excel with visual basic application (VBA) was used to divide the image data into seed, flesh, and rind. Radiation energies used for the simulation were 10 MeV (high-energy) and 1.35 MeV (low-energy) for the electron beam, 5 MeV for X-rays, and 1.25 MeV for gamma rays from Co-60. Results: At 5 MeV X-rays and 1.25 MeV gamma rays, all areas (seeds, flesh, and rind) were irradiated ranging from 0.3 ~ 0.7 kGy. The average doses decreased as the number of fruit increased. For a 10 MeV electron beam, the dose distribution was biased: the dose for the rind where the electrons entered was $0.45{\pm}0.03$ kGy and the other side was $0.24 {\pm}0.10$ kGy. Use of an electron kinetic energy absorber improved the dose distribution in mangosteens. For the 1.35 MeV electron beam, the dose was shown only in the rind on the irradiated side; no significant dose was found in the flesh or seeds. One rotation of the fruit while in front of the beam improved the dose distribution around the entire rind. Conclusion: These results are invaluable for determining the ideal irradiation conditions for phytosanitary irradiation treatment of tropical fruit.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.3
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• pp.231-237
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• 2007

The torque ripple of the hydraulic pumps for the Electro-hydrostatic Actuators can disturb the cylinder position control under slewing speed operation condition. In principle, the periodic change of the reaction torque generated by a piston type pump is highly dependent on the waveform of its cylinder chamber pressure. In case of uni-directional pumps operating at constant speed, the transient overshoot and rising slope of the cylinder pressure can be adjusted by the precompression angle and notch shape of their valve plates. Therefore, the influence of the valve plate geometry on the torque ripple magnitude of a bent-axis type piston pump for EHA application was investigated in this study. The results showed that any improvement of the torque ripple of such a bi-directional pump can not be achieved by modifying the valve plate geometry, regardless of its operation speed.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.2
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• pp.145-149
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• 2017

One of the challenges facing precision manufacturers is the increasing feature complexity of tight tolerance parts. All engineering drawings must account for the size, form, orientation, and location of all features to ensure manufacturability, measurability, and design intent. Geometric controls per ASME Y14.5 are typically applied to specify dimensional tolerances on engineering drawings and define size, form, orientation, and location of features. Many engineering drawings lack the necessary geometric dimensioning and tolerancing to allow for timely and accurate inspection and verification. Plus-minus tolerancing is typically ambiguous and requires extra time by engineering, programming, machining, and inspection functions to debate and agree on a single conclusion. Complex geometry can result in long inspection and verification times and put even the most sophisticated measurement equipment and processes to the test. In addition, design, manufacturing and quality engineers are often frustrated by communication errors over these features. However, an approach called profile tolerancing offers optimal definition of design intent by explicitly defining uniform boundaries around the physical geometry. It is an efficient and effective method for measurement and quality control. There are several advantages for product designers who use position and profile tolerancing instead of linear dimensioning. When design intent is conveyed unambiguously, manufacturers don't have to field multiple question from suppliers as they design and build a process for manufacturing and inspection. Profile tolerancing, when it is applied correctly, provides manufacturing and inspection functions with unambiguously defined tolerancing. Those data are manufacturable and measurable. Customers can see cost and lead time reductions with parts that consistently meet the design intent. Components can function properly-eliminating costly rework, redesign, and missed market opportunities. However a supplier that is poised to embrace profile tolerancing will no doubt run into resistance from those who would prefer the way things have always been done. It is not just internal naysayers, but also suppliers that might fight the change. In addition, the investment for suppliers can be steep in terms of training, equipment, and software.

• Journal of Welding and Joining
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• v.35 no.2
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• pp.43-51
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• 2017

The automatic welding systems, have received much attention in recent years, because they are highly suitable not only to increase the quality and productivity, but also to decrease manufacturing time and cost for a given product. Automatic welding work in semiconductor or space industry to be carried out in pipe line and butt joint mostly and plasma arc welding(PAW) is actively applied. To get the desired quality welds in automated welding system is challenging, a mathematical model is needed that has complete control over the relevant process parameters in order to obtain the required mechanical properties. However, In various industries the welding process mathematical model is not fully formulated for the process parameter and on the welding conditions, therefore only partial variables can be predicted. Therefore, this paper investigates the interaction between the welding parameters and mechanical properties for predicting the weld bead geometry by analyzing the S/N ratio.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.144-144
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• 2013

Non-thermal atmospheric pressure plasmas have recently garnered much attention due to their unique physical and chemical properties that are sometimes significantly different from those of low pressure plasmas. It can offer many possible application areas including nano and bio/medical areas. Many different types of plasma sources have been developed for specific needs, which can be one of the important merits of the atmospheric pressure plasmas since characteristics of the produced plasma depend significantly on operating parameters such as driving frequency, supply gas type, driving voltage waveform, gas flow rate, gas composition, geometrical factor etc. Among many source configurations, parallel plate type geometry is one of the simplest configurations so that it can offer many insights for understanding basic underlying physics. Traditionally, the parallel plate type set up has been studied actively for understanding low pressure plasma physics along with extensive employment in industries for the same reason. By considering that understanding basic physics, in conjunction with plasma-surface interactions especially for nano & bio materials, should be pursued in parallel with applications, we investigated atmospheric pressure discharge characteristics in a parallel plate type capacitive discharge source with two parallel copper electrodes of 60 mm in diameter and several millimeters in gap distance. In this presentation, some plasma characteristics by varying many operating variables such as inter-electrode distance, gas pressure, gas composition, driving frequency etc will be discussed. The results may be utilized for plasma control for widening application flexibility.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.6
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• pp.764-772
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• 2016

This paper presents on the evaluation of numerical analysis model of a ball valve used for a gas pipeline. The ball valve has important role to control the gas flow of the pipeline as well as safety operation to prevent gas explosion at the emergency. For the validation of numerical simulation, the computational domains are introduced three different types: a hexahedron chamber connected to a pipeline outlet without considering the geometry of pressure tubes, a pipeline only considered the geometry of pressure tubes, and a pipeline connected both of the a hexahedron chamber and pressure tubes. The commercial code, SC/Tetra, is introduced to solve the three-dimensional steady-state Reynolds-averaged Navier-Stokes analysis in the present study. The valve flow coefficient and valve loss coefficient with respect to the valve opening rate of 30%, 50%, and 70% are compared with experimental results. Throughout the numerical analysis for the three analysis domains, pressure computed along the pipeline is affected by computational domains. It is noted pressure obtained by the computational model considering both of the a hexahedron chamber and pressure tubes has a relatively good agreement to the experimental data.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.4
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• pp.74-80
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• 2003

Ionic wind is produced by a corona discharge when a DC high voltage is applied across the point-to-plane gap geometry. The corona discharge phenomena have been investigated in several beneficial application fields such as electrostatic cooling, ozone generation, electrostatic precipitation and electrostatic spraying. Recently ionic wind might be used in aerodynamic, for example, heat transfer, airflow modification, and etc. In this work, in order to analyze the control behavior of the velocity and amount of ionic wind produced by the positive DC corona discharges. The ionic wind velocity was measured as a function of the applied voltage, diameter of the punched hole on plate electrode and separation between the point-to-plate electrodes. As a results, the airflow is generated from the tip of needle to the plate electrode in the needle-to-punched-plate electrode systems. The ionic wind velocity is linearly increased with an increase in applied voltage and ranges from 1 to 3 m/sec at the locations of 100-200 mm from the punched-plate.

• Journal of Drive and Control
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• v.16 no.3
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• pp.51-58
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• 2019

The objective of this study was to investigate a simulation technology for the AM field based on ANSYS Inc.. The introduction of metal 3D printing AM process, and the examining of the present status of AM process simulation software, and the AM process simulation processor were done in the previous study (part 1). This present study (part 2) examined the use of the AM process simulation processor, presented in Part 1, through direct execution of Topology Optimization, Ansys Workbench, Additive Print and Additive Science. Topology Optimization can optimize additive geometry to reduce mass while maintaining strength for AM products. This can reduce the amount of material required for additive and significantly reduce additive build time. Ansys Workbench and Additive Print simulate the build process in the AM process and optimize various process variables (printing parameters and supporter composition), which will enable the AM to predict the problems that may occur during the build process, and can also be used to predict and correct deformations in geometry. Additive Science can simulate the material to find the material characteristic before the AM process simulation or build-up. This can be done by combining specimen preparation, measurement, and simulation for material measurements to find the exact material characteristics. This study will enable the understanding of the general process of AM simulation more easily. Furthermore, it will be of great help to a reader who wants to experience and appreciate AM simulation for the first time.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.4
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• pp.205-211
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• 2021

Recently, it is necessary for study on renewable energy due to environmental pollution and fossil fuel depletion. Therefore, in this study, the filling temperature according to the nozzle geometry was evaluated based on the limit temperature specified in SAEJ2601 for charging hydrogen, a new energy. There are three types of nozzles, normal, angle and round, fixed the average pressure ramp rate at 52.5 MPa/min, and the injection temperature was set at 293.4 K. As a result, the lowest temperature distribution was found in the round type, although the final temperature did not differ significantly in the three types of nozzles. In addition, Pearson's coefficient was calculated to correlate the mass flow rate with the heat transfer rate at the inner liner wall, which resulted in a strong linear relationship of 0.98 or higher.

• Journal of Mechanical Science and Technology
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• v.17 no.3
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• pp.357-369
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• 2003

Electromagnetic valve (EMV) actuation system is a new technology for improving fuel efficiency and at the same time reducing omissions in internal combustion engines. It can provide more flexibility in valve event control compared with conventional variable valve actuation devices. The electromagnetic valve actuator must be designed by taking the operating conditions and engine geometry limits of the internal combustion engine into account. To help develop a simple design method, this paper presents a procedure for determine the basic design parameters and dimensions of the actuator from the relations of the valve dynamics, electromagnetic circuit and thermal loading condition based on the lumped method. To verify the accuracy of the lumped method analysis, experimental study is also carried out on a prototype actuator. It is found that there is a relatively good agreement between the experimental data and the results of the proposed design procedure. Through the whole speed range, the actuator maintains proper performances in valve timing and event control.