• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.329-334
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• 1997

A tomography algorithm to maximize the entropy of image using Lagrangian multiplier technique and conjugate gradient method has been designed for the measurement of 2D spatial distribution of intense neutral beams of KSTAR NBI(Korea Superconducting Tokamak Advanced Research Neutral Beam Injector) which is now being designed. A possible detection system was assumed and a numerical simulation has been implemented to test the reconstruction quality of given beam profiles. This algorithm has the good applicability for sparse projection data and thus, can be used for the neutral beam tomography.

• Journal of Korean Vacuum Science & Technology
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• v.7 no.1
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• pp.1-7
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• 2003

The pressure distributions in the test stand built for developing KSTAR NBI ion sources were obtained using a network system composed of conductance elements modeling the ion source, the neutralizer, and other beam line components. The allowable regime was defined on the coordinates of the gas supply rate to the ion source and the neutralizer, considering the proper conditions of the three critical parameters, the ion source pressure for good arc discharge, the pressure integral in the neutralizer for sufficient neutralization, and the chamber pressure for minimum neutral beam loss. The neutral beam evolution along the path from the ion source extraction grid to the calorimeter through the neutralizer, the bending magnet and the vacuum chamber was estimated for typical pressure distributions.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.2
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• pp.79-84
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• 2016

A flexible electronic device deformed by external force causes the failure of a semiconductor die. Even without failure, the repeated elastic deformation changes carrier mobility in the channel and increases resistivity in the interconnection, which causes malfunction of the integrated circuits. Therefore it is desirable that a semiconductor die be placed on a neutral line where the mechanical stress is zero. In the present study, we investigated the effects of design factors on the position of neutral line by finite element analysis (FEA), and expected the possible failure behavior in a flexible face-down packaging system assuming flip-chip bonding of a silicon die. The thickness and material of the flexible substrate and the thickness of a silicon die were considered as design factors. The thickness of a flexible substrate was the most important factor for controlling the position of the neutral line. A three-dimensional FEA result showed that the von Mises stress higher than yield stress would be applied to copper bumps between a silicon die and a flexible substrate. Finally, we suggested a designing strategy for reducing the stress of a silicon die and copper bumps of a flexible face-down packaging system.

• Journal of the Semiconductor & Display Technology
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• v.21 no.2
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• pp.144-149
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• 2022

A cryogenic Mixed Refrigerant Joule-Thomson refrigeration cycle was designed to be applied to the semiconductor etching process with non-flammable constituents. 3-stage cascade refrigerator, single mixed refrigerant Joule-Thomson refrigerator, and 2-stage cascade type mixed refrigerant Joule-Thomson refrigerator are analyzed to figure out the coefficient of performance. Non-flammable mixture of argon(Ar), tetrafluoromethane(R14), trifluoromethane (R23) and octafluoropropane(R218) were utilized to analyze the refrigeration cycle efficiency. The designed refrigeration cycle was adapted to cool down the coolant of HFE7200(Ethoxy-nonafluorobutane, C₄F₉OC₂H₅) with certain constraints. Maximum coefficient of performance of the refrigeration system is obtained as 0.289 for the cooling temperature lower than -100℃. The detailed result of the coefficient of performance according to the mixture composition is discussed in this study.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.6
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• pp.1268-1273
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• 2011

The study on power capacity increase of superconducting fault current limiter (SFCL) is one of the most important researches to apply a SFCL in the power system. To achieve this, we thought that the unbalanced quenching problem generated in series connection of superconducting units should be solved. In this paper, we investigated the quenching characteristics of superconducting units in the transformer-type SFCL with or without the neutral line between secondary windings and superconducting units. In case of transformer-type SFCL without neutral line, the connection structure of superconducting units is identical to that of the resistive-type SFCL connected in series. Therefore, the unbalanced quenching was occurred by difference of critical current between superconducting units. However, in case of transformer-type SFCL with neutral line, the superconducting units with different critical current were simultaneously quenched. It was because the currents induced by secondary winding were separately flowed through the superconducting units. By these results, we confirmed that the resistances and consumption powers of the superconducting units were equally generated.

• Journal of the Korean Solar Energy Society
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• v.37 no.6
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• pp.1-12
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• 2017

The DC link of Grid-Connected 3-Phase 3-Level T-type Photovoltaic PCS (PV-PCS) consists of two series connected capacitors for using their neutral voltage. The mismatch between two capacitor characteristics and transient states happened in load change cause the imbalance of neutral voltage. As a result, PV-PCS performance is degraded and the system becomes unstable. In this paper, a mathematical model for analyzing the imbalance of neutral voltage is derived and a compensation method using offset voltage is proposed, where offset voltage adjusts the applying time of P-type and N-type small vectors. The validity of the proposed methods is verified by simulation and experiment.

• Journal of the Korean Vacuum Society
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• v.19 no.2
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• pp.121-127
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• 2010

Neutral gas in a Hall-effect thruster in a small satellite is simulated using a molecular dynamics code. Investigated are neutral density, pressure, axial average velocity, and temperature for the variation of diffusive reflection ratio, initial gas temperature, and channel length. Expected through this research are improving of discharge simulation through the neutral simulation and understanding of real system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.10
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• pp.76-83
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• 2008

The neutral current is made of both the load unbalanced current and the 3rd harmonic. The 3rd harmonic which is the source of the main neutral current is generated from the loads using bridge rectifier circuits on their input produce currents. TV, computer and monitor which are belong to IEC 61000-3-2 Class D are the main 3rd harmonic current sources. In order to show the affect of the distribution system by these disturbances, this paper has studied the current standards of the Korea Electric and considers the problem of the neutral common.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.32 no.1
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• pp.8-15
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• 2023

In case with severely atrophied mandibular ridges, it may be difficult to achieve adequate retention and stability of dentures through the normal functional impression process of complete dentures. In these patients, an approach using the neutral zone raising technique may be an effective alternative. The neutral zone is defined as the area where the pressure of the tongue towards the outside of the mouth and the pressure of the cheek and lips towards the inside are balanced during the normal oral function of the muscular-nervous system. Complete dentures made through neutral zone impression not only improve retention and stability, but also provide adequate tongue space in the posterior teeth area. Additionally, food residues are reduced in the area around artificial teeth, and aesthetics are improved through appropriate facial support.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.4
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• pp.419-427
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• 2011

The characteristics for hydrogen production and the thermochemical properties of high temperature steam electrolysis(HTSE) device have been numerically analyzed in a two-dimension, steady-state with using the COMSOL $Multiphysics^{(R)}$. The main parameters for the calculation are applied voltage, ASR(Area-specific Resistance), temperature and pressure of the inlet gas flow. The results showed that thermal-neutral voltage was 1.2454 V and rather than the cell temperature increases or decreases with increasing applied voltage by thermal-neutral voltage starting this voltage the temperature in high voltage tended to rise and temperature in the low voltage tended to fall. And with, increasing the values of ASR, temperature inside the cell and the hydrogen production rate were decreased.