• Design & Manufacturing
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• v.15 no.4
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• pp.32-36
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• 2021

In this study, the cause of the decrease in transmittance of the outer lens among the causes of the decrease in the amount of light in the automobile headlamp was identified, and the improvement method was selected to determine the effect. The causes of defects that lower the transmittance of the outer lens are divided into a moisture problem and a haze problem. The moisture problem is caused by the temperature difference between the inside and the outside of the head lamp, and the haze problem occurs when the heat inside the head lamp evaporates the haze component contained in the plastic material and attaches it to the outer lens. In order to improve the haze problem that occurs in plastic raw materials, the structures of the bulb light source type headlamp and the LED chip light source type headlamp were analyzed. Among them, the housing material of the LED chip light source type headlamp, which is structurally prone to haze gas, was selected as the test target. In the mass-production injection process of the housing, the drying process was selected as a method to minimize haze gas without adding a separate production process. After extracting a sample every drying time at a constant drying temperature, the sample was put into a haze tester and the residual amount of haze gas was measured. As a result, it was confirmed that the residual amount of Haze gas in the material decreased as the drying time increased.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.493-495
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• 2005

This paper proposes a swarm-based fuzzy system modeling technique for coke oven combustion control diagnosis. The coke plant produces coke for the blast furnace plant in steel making process by charging coal into oven and supplying gas to carbonize it. A conventional mathematical model for coke oven combustion control has been used to control the amount of gas input, but it does not work well because of highly nonlinear feature of coke plant. To solve this problem, swarm-based fuzzy system modeling technique is suggested to construct a diagnosis model of coke oven combustion control. Based on the measured input-output data pairs, the fuzzy rules are generated and the parameters are tuned by the PSO(Particle Swarm Optimizer) to increase the accuracy of the fuzzy system is operated. This system computes the proper amount of gas input taking the operation conditions of coke oven into account, and compares the computed result with the supplied gas input.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.E4
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• pp.169-175
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• 2003

The effect of gas composition on the discharge characteristics and the ozone production in silent discharge (SD) process was investigated. The major gas components, $N_2$, $O_2$, and $H_2O$ influence the discharge properties according to their relative magnitude of ionization thresholds and electron affinities. The generated amount of ozone increased with the discharge energy by increasing the electron mean energy. The higher oxygen content injected, the higher ozone produced. A small amount of water vapor significantly lowered the discharge onset voltage by the ionization threshold decreasing effect and high electrical conductivity. However, the further increase of water vapor contributes to decrease the electron density by the electron affinity The addition of water greatly reduced the ozone generation through the formation of OH radical and the catalytic ozone destruction process.

• Journal of Welding and Joining
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• v.12 no.1
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• pp.51-58
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• 1994

Amount of spatter, welding conditions and welding costs were investigated for MAG welding. $CO_2$, Ar+18%;$CO_2$ and Ar+8%$O_2$ were used for shielding gases. As results, arc characteristics and appropriate range for welding were obtained. Amount of spatter in Ar+18%$CO_2$ gas welding was 20% of that of $CO_2$ welding, and Ar+8%$O_2$ was 10% of that of $CO_2$ welding. Therefore by using Ar+18%$CO_2$and Ar+8%$O_2$ gases, welding costs could be reduced compared with $CO_2$ welding due to avoiding spatter.

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.3
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• pp.179-182
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• 2003

Anaerobic fermentation was attempted to produce methane from the wood chip (Eucalyptus globulus). By the pretreatment of the wood chip using hot water with high temperature, NaOH, and steam explosion, the production of methane gas was enhanced. The pretreatment using Steam explosion resulted in more amount of methane gas produced than the treatment using either hot water or 1% (w/w) NaOH with high temperature, and the steam explosion at a steam pressure of 25 atm and a steaming time of 3 min was the most effective for the methane production. The amount of methane gas produced depended on the ratio of weight of Klason lignin, a high molecular weight lignin, in the treated wood chip.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1114-1119
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• 2004

In a foaming process of microcellular plastics (MCPs) with a injection molding, research on the viscosity change that occurs when the gas is injected to the polymer has received little attention despite its importance. The purpose of this paper is to provide the basic data required to determine the processing condition by measuring viscosity changes against the gas injection rates of the blowing agent, and to verify the influence of the viscosity change on the flow condition of polymer inside the mold at the injection process.

• Journal of the Korean Institute of Gas
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• v.17 no.2
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• pp.1-8
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• 2013

In this study, 120 cases of damage due to ground subsidence of city gas pipeline which is hanging on apartment outer wall were investigated. From the survey results, it was determined to be approximately 100m~200mm ground subsidence occurred and at severe damage, pipeline was cut and the gap was about 50mm between two cut pipeline. Device for measuring the amount of deformation of standing gas pipeline was designed and fabricated. And installed it on apartment outer wall for measuring the deformation due to ground subsidence, after 5 months measurement the amount of ground subsidence was measured to 1.3mm. Stress assessment was conducted based on results of ground subsidence occurred on standing gas pipeline.

• Analytical Science and Technology
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• v.35 no.5
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• pp.205-211
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• 2022

Deuterium (D) is an isotope with one more neutron number than hydrogen (H). Heavy elements rarely change their chemical properties with little effect even if the number of neutrons increases, but low-mass elements change their vibration energy, diffusion rate, and reaction rate because the effect cannot be ignored, which is called an isotope effect. Recently, in the semiconductor and display industries, there is a trend to replace hydrogen gas (H₂) with deuterium gas (D₂) in order to improve process stability and product quality by using the isotope effect. In addition, as the demand for D₂ in industries increases, domestic gas producers are making efforts to produce and supply D₂ on their own. In the case of high purity D₂, most of them are produced by electrolysis of heavy water (D₂O), and among D₂, hydrogen deuteride (HD) molecules are present as isotope impurities. Therefore, in order to maximize the isotope effect of hydrogen in the electronic industry, HD, which is an isotope impurity of D₂ used in the process, should be small amount. To this end, purity analysis of D₂ for industrial processing is essential. In this study, HD quantitative analysis of D₂ for high purity D₂ purity analysis was established and hydrogen isotope RM (Reference material) was developed. Since hydrogen isotopes are difficult to analyze with general gas analysis instrument, they were analyzed using a high-precision mass spectrometer (Gas/MS, Finnigan MAT271). High purity HD gas was injected into Gas/MS, sensitivity was determined by a signal according to pressure, and HD concentrations in two bottles of D₂ were quantified using the corresponding sensitivity. The amount fraction of HD in each D₂ was (4518 ± 275) μmol/mol, (2282 ± 144) μmol/mol. D₂, which quantifies HD amount using the developed quantitative analysis method, will be manufactured with hydrogen isotope RM and distributed for quality management and maintenance of electronic industries and gas producers in the future.

• International journal of advanced smart convergence
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• v.11 no.4
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• pp.57-67
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• 2022

The demand for personal training (PT), through which high exercise effects can be achieved within short-term, has recently increased. PT can achieve an exercise amount improvement effect, only if accurate postures are maintained upon performing PT, and exercise with inaccurate postures can cause injuries. However, research is insufficient on exercise amount comparisons and judging exercise accuracy on PT. This study proposes an exercise accuracy measurement algorithm and compares differences in exercise amounts according to exercise postures through experiments using a respiratory gas analyzer. The exercise accuracy measurement algorithm acquires Euler anglesfrom major body parts operated upon exercise through a motion device, based on which the joint angles are calculated. By comparing the calculated joint angles with each reference angle in each exercise step, the status of exercise accuracy is judged. The calculated results of exercise accuracy on squats, lunges, and push-ups showed 0.02% difference in comparison with actually measured results through a goniometer. As a result of the exercise amount comparison experiment according to accurate posture through a respiratory gas analyzer, the exercise amount was higher by 45.19% on average in accurate postures. Through this, it was confirmed that maintaining accurate postures contributes to exercise amount improvement.

• Journal of Welding and Joining
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• v.17 no.6
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• pp.38-45
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• 1999

Shielding gas has significant effects on arc stability, metal transfer and weld quality in the gas metal arc welding (GMAW) process. The double gas-shielded MAG(DMAG) and auxiliary gas-shielded MAG (AMAG) torches are investigated for their capability to provide argon-rich gas mixture using small amount of argon gas through the inner and auxiliary nozzles, respectively. Argon composition with the DMAG torch is calculated numerically, and compared with the measured data using the gas chromatogrphy. Gas flow pattern of the DMAG torch is calculated to change from the laminar to turbulent flow when total gas flow rate becomes larger than 4.5 liter/min at room temperature. While argon-rich shielding gas was obtained using both the AMAG and DMAG torches, the AMAG torch provides higher argon composition than the DMAG torch, which demonstrates that argon gas can be utilized more efficiently with the AMAG torch.