• International Journal of Aeronautical and Space Sciences
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• v.16 no.3
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• pp.347-359
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• 2015

A method of describing the rovibrational energy transitions and coupled chemical reactions in the direct simulation Monte Carlo (DSMC) calculations is constructed for $H(^2S)+H_2(X^1{\Sigma}_g)$ and $He(^1S)+H_2(X^1{\Sigma}_g)$. First, the state-specific total cross sections for each rovibrational states are proposed to describe the state-resolved elastic collisions. The state-resolved method is constructed to describe the rotational-vibrational-translational (RVT) energy transitions and coupled chemical reactions by these state-specific total cross sections and the rovibrational state-to-state transition cross sections of bound-bound and bound-free transitions. The RVT energy transitions and coupled chemical reactions are calculated by the state-resolved method in various heat bath conditions without relying on a macroscopic properties and phenomenological models of the DSMC. In nonequilibrium heat bath calculations, the state-resolved method are validated with those of the master equation calculations and the existing shock-tube experimental data. In bound-free transitions, the parameters of the existing chemical reaction models of the DSMC are proposed through the calibrations in the thermochemical nonequilibrium conditions. When the bound-free transition component of the state-resolved method is replaced by the existing chemical reaction models, the same agreement can be obtained except total collision energy model.

• Journal of the Semiconductor & Display Technology
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• v.23 no.3
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• pp.64-68
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• 2024

Thermodynamic solution stability of aqueous copper-nickel-sulfur system was numerically analyzed to produce thin copper-nickel nano-multi-layers by pulse electro-forming. The main program for numerical analysis was written by C# language, which was composed of the data input, numerical calculation, decision and plotting sub-programs. From the thermodynamic data of 32-feasible phases of the Cu-Ni-S-H₂O system, the phase stability diagram of the Cu-Ni-S-H₂O system was constructed. It revealed the electro-forming condition of the copper and the nickel was V_SHE<0.35 for copper deposition, V_SHE<-0.24 for nickel deposition, pH=1.0 and 25℃ in the sulfide bath. The coppernickel multi-layers was well produced by electro-forming in the sulfide bath with two-wave pulse voltages of - 0.2V_SHE, -0.5 mA/cm², and 25 seconds for copper deposition and -1.7 V_SHE, -50 mA/cm² and 80 seconds for nickel deposition, at pH=1.0 and 25℃. From TEM and EDX analysis the Cu-Ni multi-layers with about 5 ㎛ thick had the copper-rich phase of about 20 nm in thick and the nickel rich phase of about 25 nm in thick, respectively.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.7
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• pp.60-66
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• 2020

In order to improve fatigue life of transmission gear carburizing is normally used. Carburizing is a very good process to achieve low cost and high performance. The machined gears are heated up to carburizing temperature and then cooled rapidly in an oil bath to produce high surface hardness. The gears may undergo excessive thermal distortion during heating and rapid cooling. In order to predict the distortion during heating and rapid cooling, a coupled thermo-mechanical simulation is needed. In the current research, the simulation of heating and cooling was performed. The results show that the thermal distortion and the residual stresses are well predicted by the coupled simulation. In addition, induction heating and rapid cooling simulation is carried out to predict the thermal distortion. The amount of distortion is compared. It is shown that induction heating is very effective to reduce thermal distortion.

• Corrosion Science and Technology
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• v.15 no.2
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• pp.78-83
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• 2016

The e-coating to inhibit induced corrosion can deposit a coating not only on the exterior surface but also on the inside of whole metallic components of body-in-white (BIW). But it is difficult to deposit paint films on the inside area because metallic components are multi layered. It may cause shortness of e-coating thickness. The only way to properly verify e-coating thickness is by performing the use of tear-down prototypes. When paint films' thickness is inadequate, a structural modification on each metallic component is needed. Verification of the thickness improvement for a structural modification requires much manual effort and leads to increasing development time. Recently, the simulation technology has been developed to predict the e-coating thickness in e-coating field. By applying the simulation to BIW, improvement in paint thickness quality and shortening of development period are expected. The paper explains a validated solution that allows simulating the effect of design changes to the e-coating thickness and current density, thereby delivering results within a time frame of a few days.

• Journal of the Korean Society of Safety
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• v.22 no.2 s.80
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• pp.41-46
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• 2007

This paper considers the electrical shock risk of the human body due to underwater leakage current in such places of public baths. Many submerged electric facilities in a public bath may create a severe electric shock hazard for the human body, since wet body in an accidentally energized bathtub can result in low electrical resistance through the human body for leakage or fault currents. Therefore a major consideration, in the context of electrical safety underwater, is the shock risk to the bather as a result of electric current flowing through the water in bathtub. To assess the electric shock risk and to analyze the potential distribution in a bathtub, 2 different situation cases are set up, then experimental and simulation methods are adopted. The validity of 2 cases of simulation and experiment data in a bathtub for electric distribution underwater are compared and analyzed. Also electric shock risk assessment underwater in a real public bathtub by simulation program package, Flux 3D, was conducted herein, and the results are presented and discussed.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.3
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• pp.336-342
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• 2019

Introduction: An unexpected death was reported in a beginner immediately after starting the work at a plating factory. After the incident, air sampling was performed using a simulation of the situation as it had been at the time. Methods: To evaluate the airborne concentration of hydrogen cyanide, a total of six samples were collected: one personal sample, three area samples, and two background samples (office and outdoors). Hydrogen cyanide measurement was performed according to the standard sampling protocol recommended by the U.S. NIOSH (National Institute of Occupational Safety and Health). Results: The highest concentration of hydrogen cyanide was 0.938 ppm measured in a sample collected from the plating bath area with local exhaust ventilation. This value was approximately 20% of the ceiling occupational exposure limit. The personal sample showed a concentration of 0.135 ppm. Samples collected near the bath in which the incident occurred and a dehydrator showed hydrogen cyanide concentrations of 0.236 ppm and 0.101 ppm, respectively. Hydrogen cyanide was not detected in the background samples (office and outdoors). Conclusions: It is necessary to use proper ventilation systems and respirators in plating factories to prevent acute poisoning. Furthermore, it is important to educate and train new workers dealing with toxic substances.

• KIEE International Transactions on Power Engineering
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• v.4A no.1
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• pp.26-32
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• 2004

Digital technology has advanced significantly over the years both in terms of software tools and hardware availability. It is now applied extensively throughout many area of electrical engineering including protective relaying in power systems. Digital relays have numerous advantages over traditional analog relays, such as the ability to accomplish what is difficult or impossible using analog relays. Although non real-time simulators like PSCAD/EMTDC are employed to test the algorithms, such simulations are disadvantaged in that they cannot test the relay dynamically. Hence, real-time simulators like RTDS are used. However, the latter requires large space and is very expensive. This paper uses EMTP MODELS to simulate the power system and the distance relay. The distance relay algorithm is implemented and the distance relay is interfaced with a test power system. The distance relay's performance is then assessed interactively under various fault types, fault distances and fault inception angles. The test results show that we can simulate the distance relay effectively and we can examine the operation of the distance relay very closely including its drawbacks/limitations by using EMTP MODELS. Equally important, this approach facilitates any changes that need to be carried out in order to enhance the Distance Relay under test/examination.

• Journal of the Ergonomics Society of Korea
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• v.30 no.5
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• pp.629-636
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• 2011

Objective: The aim of this study is developing an elderly automatic showering system by optimizing nozzle position and angle of water injection on ergonomics approach. Background: The elderly living in nursing home or hospital were increased by an aging population. Helping the elderly on showering is so hard. In addition, the existing showering/bathing systems are not effective because shower pattern of the elderly and washed range of nozzle were not considered. Method: Firstly, basic specification were determined by anthropometric approach. Secondly, position of nozzle and angle of water injection were determined through observation of elderly behavior on showering. And, finally, they were optimized by washing test and showering simulation. Results: On showering importance of body parts were able to analysis through observation of elderly behavior. The position of nozzle and angle of water injection was able to optimize by showering simulation. The automatic showering system was developed by considering their results. Conclusion: The most important technology of developing a showering system is the determining position of nozzle and angle of water injection, number of nozzle. It was developed by applying its results through user centered-research. Application: The user centered-research of developing products was able to apply directly to develop automatic bath, showering products etc. Further more it was available to apply senior friendly products.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1639-1645
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• 1991

Because of the important role LD converters play in the production of high quality steel, various dynamic models have been attempted in the past by many researchers not only to understand the complex chemical reactions that take place in the converter process but also to assist the converter operation itself using computers. And yet no single dynamic model was found to be completely satisfactory because of the complexity involved with the process. The process indeed involves dynamic energy and mass balances at high temperatures accompanied by complex chemical reactions and transport phenomena in the molten state. In the present study, a mathematical model describing the dynamic behavior of LD converter process has been developed. The dynamic model describes the time behavior of the temperature and the concentrations of chemical species in the hot metal bath and slag. The analysis was greatly facilitated by dividing the entire process into three zones according to the physical boundaries and reaction mechanisms. These three zones were hot metal (zone 1), slag (zone 2) and emulsion (zone 3) zones. The removal rate of Si, C, Mn and P and the rate of Fe oxidation in the hot metal bath, and the change of composition in the slag were obtained as functions of time, operating conditions and kinetic parameters. The temperature behavior in the metal bath and the slag was also obtained by considering the heat transfer between the mixing and the slag zones and the heat generated from chemical reactions involving oxygen blowing. To identify the unknown parameters in the equations and simulate the dynamic model, Hooke and Jeeves parttern search and Runge-Kutta integration algorithm were used. By testing and fitting the model with the data obtained from the operation of POSCO #2 steelmaking plant, the dynamic model was able to predict the characteristics of the main components in the LD converter. It was possible to predict the optimum CO gas recovery by computer simulation

• Progress in Superconductivity and Cryogenics
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• v.6 no.3
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• pp.1-5
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• 2004

This paper presents a study on the stability of bare and cu-laminated YBCO-coated conductor. we investigate the characteristics of quench/recovery behavior of YBCO test samples. bare and copper-laminated, by subjecting each test sample. immersed in a bath of liquid nitrogen boiling at 77.3 K. to a transport current pulse superimposed to a baseline DC current of 90-95% the critical current. The current pulse has an amplitude up to ∼4.5 times the critical current and a duration of 300 ms. This paper presents both experimental and simulation results.