• Journal of Advanced Marine Engineering and Technology
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• 제18권1호
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• pp.114-122
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• 1994

A cold temperature control system for the BAF(batch annealing furnace) has been established in order to reduce energy consumption to imrpove productivity and stabilize the properties of products. Therefore we confirmed a relation between annealing cycle time and atmospheric gas, changing annealing cycle time according to BAF temperature with time during heating and actual temperature measurements cold spot during soaking. The results of the temperature variation effect on the batch annealing are as follows. 1) Cooling rate is increasing gradually with increasing atmospheric gas flow, but heating rate is hardly increasing without atmospheric gas component. Heating time is reduced to one half with increasing atmospheric gas flow rate and changing of atmospheric gas component from HNx to Ax gas and annealing cycle time is reduce to 2.7 times. 2) With enlarging the difference between furnace temperature and soaking temperature at the HNx BAF, heating time becomes short, but cooling time is indifferent. 3) If temperature difference of 300.deg. C in the temperature change of cold spot according to the annealing cycle control temperature, Hi-CON/H2BAF is interchanging at each other at 26hours, but HNxBAF at 50 hours. 4) Soaking time at batch annealing cycle determination is made a decision by the input coil width, and soaking time for quality homogenization of 1219 mm width coil must be 2.5 hours longer then that of 914mm width coil for the same coil weight at Hi-CON/H2BAF. But, it is necessary to make 2 hours longer at HNxBAF.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 추계학술대회 논문집
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• pp.47-48
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• 2006

• 한국환경농학회지
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• 제27권4호
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• pp.389-394
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• 2008

The ecophysiological changes occurring upon cold stress were studied using cold tolerant transgenic and wild-type tobacco plants. In a previous study, cold tolerance in tobacco was induced by the introduction of a gene encoding the zinc finger transcription factor, PIF1. Gas-exchange measurements including net photosynthesis and stomatal conductance were performed prior to, in the middle of, and after a cold-stress treatment of $1{\pm}2^{\circ}C$ for 96 h in each of the four seasons. In both transgenic and wild-type plants, gas-exchange parameters were severely decreased in the middle of the cold treatment, but had recovered after 2-3 h of adaptation in a greenhouse. Most t-test comparisons on gas-exchange measurements between the two plant types did not show statistical significance. Wild-type plants had slightly more water-soaked damage on the leaves than the transgenic plants. A light-response curve did not show any differences between the two plant types. However, the curve for assimilation-internal $CO_2$ in wild-type plants showed a much higher slope than that of the PIF1 transgenic plants. This means that the wild-type plant is more capable of regenerating Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and has greater electron transport capacity. In conclusion, cold-resistant transgenic tobacco plants demonstrated a better recovery of net photosynthesis and stomatal conductance after cold-stress treatment compared to wild-type plants, but the ecophysiological recoveries of the transgenic plants were not statistically significant.

• 한국정밀공학회지
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• 제28권3호
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• pp.383-388
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• 2011

The cold hollow cathode gas ion source is under development for multi aperture focused ion beam (FIB) system. In this paper, we describe the cold hollow cathode ion source design and the general ion source performance using Ar gas. The glow discharge characteristics and the ion beam current density at various operation conditions are investigated. This ion source can generate maximum ion beam current density of approximately 120 mA/$cm^2$ at ion beam potential of 10 kV. In order to effectively transport the energetic ions generated from the ion source to the multi-aperture focused ion beam(FIB) system, the einzel lens system for ion beam focusing is designed and evaluated. The ions ejected from the ion source can be forced to move near parallel to the beam axis by adjusting the potentials of the einzel lenses.

• Journal of Microbiology and Biotechnology
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• 제32권6호
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• pp.768-775
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• 2022

In this study we aimed to derive the response surface models for Escherichia coli reduction in wheat flour using atmospheric cold plasma (ACP) with three types of gas. The jet-type atmospheric cold plasma wand system was used with a 30 W power supply, and three gases (argon, air, and nitrogen) were applied as the treatment gas. The operating parameters for process optimization considered were wheat flour mass (g), treatment time (min), and gas flow rate (L/min). The wheat flour samples were artificially contaminated with E. coli at a concentration of 9.25 ± 0.74 log CFU/g. ACP treatments with argon, air, and nitrogen resulted in 2.66, 4.21, and 5.55 log CFU/g reduction of E. coli, respectively, in wheat flour under optimized conditions. The optimized conditions to reduce E. coli were 0.5 g of the flour mass, 15 min of treatment time, and 0.20 L/min of nitrogen gas flow rate, and the predicted highest reduction level from modeling was 5.63 log CFU/g.

• 대한기계학회논문집B
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• 제23권5호
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• pp.653-660
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• 1999

This work describes analysis on the effect of inlet air cooling by the cold energy of liquefied natural gas(LNG) on the performance of gas turbines. Gas turbine off-design analysis program to simulate the influence of compressor inlet temperature variation is prepared and an inlet air cooler is modeled. It is shown that the degree of power augmentation is much affected by the humidity of inlet air. If the humidity is low enough, that is the water content of the air does not condense, the temperature drop amounts to $18^{\circ}C$, which corresponds to more than 12% power increase, in case of a $1350^{\circ}C$ class gas turbine with methane as the fuel. Even with 60% humidity, about 8% power increase is possible. It is found that even though the fuel contains as much as 20% ethane in addition to methane, the power improvement does not change considerably. It is observed that if the humidity is not too high, the current system is feasible oven with conceivable air pressure loss at the inlet air cooler.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권7호
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• pp.331-337
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• 2001

With the increasing reliability of analysis schemes and the dramatically increased calculating speed, the computer simulation has become and indispensable process to predict the interruption capacity of circuit breakers. Generally, circuit breakers have to possess both the small current and large current interruption abilities and the circuit breaker designers need to evaluate its capacities to save the time and the expense. The analysis of small current and the large current interruption performances have been considered separately because the phenomena occurring in a interrupter are quite different. To analyze the dielectric recovery after large current interruption many physical phenomena such as heat transfer, convection and arc radiation, the nozzle ablation, the ionization of high temperature SF(sub)6 gas, the electric and themagnetic forces and so forth mush be considered. However, in the analysis of small current interruption performance only the cold gas flow analysis needs to be carried out because the capacitive current is to small that the influence from the current can be neglected. In this paper, an empirical equation which is obtained from a series of tests to estimate the dielectric recovery strength has been applied to a real circuit breaker. The results of analysis have been compared with the test results and the reliability has been investigated.

• 한국자동차공학회논문집
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• 제16권3호
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• pp.66-72
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• 2008

Fuel reforming technology for the fuel cell vehicles could be adopted to internal combustion engine for the reduction of engine out emissions. Since syngas which is reformed from fossil fuel has hydrogen as a major component, it has abilities to enhance the combustion characteristics with wide flammability and high speed flame propagation. In this paper, syngas was feed to 2.0 liter gasoline engine during the cold start and early state of idle condition. Not only cold start HC emission but also $NO_x$ emission could be dramatically reduced due to the fact that syngas has no HC and has nitrogen up to 50% as components. Exhaust gas temperature was lower than that of gasoline feeding condition. Delayed ignition timing, however, resulted in increased exhaust gas temperature approximated to gasoline condition. It is supposed that the usage of syngas in the gasoline internal combustion engine is an effective solution to meet the future strict emission regulations by the reduction of cold start THC and $NO_x$ emissions.

• Korean Chemical Engineering Research
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• 제60권3호
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• pp.371-376
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• 2022

액화 천연 가스는 도시가스로 공급되기 위해 기화의 과정을 거치는데 이 때 약 800 kJ/kg의 냉열이 발생한다. 현재 이 에너지는 모두 바다로 버려지고 있어 에너지 재순환 관점에서 보면 아주 심각한 에너지 낭비를 초래하고 있다. 본 연구에서는 이 점에 착안하여 버려지는 액화 천연 가스의 냉열을 활용할 수 있는 해수담수공정을 제안하고 이 공정을 최적화하여 고유 전력 소비와 경제성에 대해 분석하였다. 그 결과 제안된 공정의 에너지 소모량은 -5.2 kWh/m³, 담수생산 단가는 0.148 USD/m³으로 계산되어 현재까지 개발된 어떤 공정보다도 우수함을 확인하였다.

• Nuclear Engineering and Technology
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• 제46권3호
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• pp.395-406
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• 2014

This study provides a fundamental understanding of a cold finger melt crystallization technique by exploring the heat and mass transfer processes of cold finger separation. A series of experiments were performed using a simplified LiCl-CsCl system by varying initial CsCl concentrations (1, 3, 5, and 7.5 wt%), cold finger cooling rates (7.4, 9.8, 12.3, and 14.9 L/min), and separation times (5, 10, 15, and 30 min). Results showed a potential recycling rate of 0.36 g/min with a purity of 0.33 wt% CsCl in LiCl. A CsCl concentrated drip formation was found to decrease crystal purity especially for smaller crystal formations. Dimensionless heat and mass transfer correlations showed that separation production is primarily influenced by convective transfer controlled by cooling gas flow rate, where correlations are more accurate for slower cooling gas flow rates.