• Analytical Science and Technology
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• v.17 no.6
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• pp.443-453
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• 2004

Toluene is currently used as a major organic solvent of glues which are abused by the youngster for its hallucinogenic effect. In this study, toluene determination method using headspace gas chromatography (HS-GC) in the biological fluids like blood, urine and saliva of glue sniffers was validated and related uncertainties were estimated. LOD of $0.01{\mu}g/mL$ in saliva and LOQ of $0.1{\mu}g/mL$ in blood were the highest among LODs and LOQs in urine, blood and saliva. Other performance characteristics such as linearity, working range, accuracy, precision and recovery were also measured. The uncertainty at toluene concentration of $1{\mu}g/mL$ was estimated to be 0.13, 0.09 and $0.17{\mu}g/mL$ for blood, urine and saliva, respectively, and the uncertainty contribution from the least linear regression was dominant at the lower concentration of toluene.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1836-1843
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• 2017

In this paper, we investigated fire cases those are believed to be caused by explosion of a electrolytic motor start capacitor. Using two types of commercially available electrolytic motor start capacitors, capacitor current and the possibility of capacitor explosion were tested. And the ignition possibility of the internal material leaked from a capacitor was also tested. In addition, experiments were conducted to see if the fire could spread when a capacitor was exposed to an external flame. From our test we observed that the current of the electrolytic motor start capacitor rose continuously to a certain level by product, if the capacitor was continuously energized with working voltage, and then the capacitor was exploded. The gas and liquid leaked from the capacitor by the explosion could ignite by an electric arc and an external flame. The capacitor current at explosion was different product by product, but each product had a certain current level at explosion. And the increase rate of the capacitor current until explosion was 24% and 31% for the products used in the experiment. We proposed the capacitor explosion prevention method that cuts off power when the capacitor current rises to a certain threshold level. The proposed method can be used if the current of the applied electrolytic motor start capacitor rises continuously and then the capacitor is exploded at a certain current level when the capacitor is energized continuously.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.393-396
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• 2004

본 논문에서는 완충층용 MgO 박막을 P-type(100)Si 기판위에 작업가스 $Ar:O_2=80:20$, RF 파워 50W, 기판온도 $400^{\circ}C$, 10mtorr의 작업진공에서 $500{\AA}$ 증착하였다. 제작된 MgO/Si 기판위에 RF Magnetron sputtering법으로 작업가스 $Ar:O_2$의 비율을 90:10, 80:20, 70:30으로 변화하면서 $BST(Ba_{0.5}Sr_{0.5}TiO_3)$ 박막을 약 $2000{\AA}$ 증착하였다. XRD 측정결과 작업가스비의 변화에 관계없이(110)BST와 (111)BST 피크만이 관찰되었으며 작업가스 $Ar:O_2=80:20$에서 가장 양호한 결정성을 나타내었다. I-V 측정결과 인가전계 ${\pm}100kV/cm$에서 $10^{-7}A/cm^2$이하의 양호한 누설전류 특성을 보여주고 있으며 C-V 측정결과 작업가스 $Ar:O_2$의 비율 90:10, 80:20, 70:30에서의 비유전율은 각각 283, 305, 296으로서 작업가스비 80:20에서 제작된 박막의 특성이 가장 우수하였다. 작업가스비 80:20에서 제작된 박막의 SEM 측정결과 결정이 성장되었음을 확인할 수 있었고 그레인의 크기는 약 10nm였다.

• Applied Chemistry for Engineering
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• v.19 no.3
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• pp.338-344
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• 2008

The improvement of energy conservation is mandatory to decrease consumption of fossil fuels and to minimize negative impacts on the environment which originates from large cooling and heating demand. The absorption heat pump technology has a large potential for energy-saving in this respect. Absorption heat pump is a means to upgrade waste heat without the addition of extra thermal energy. The higher performance of absorber is of great importance for absorption heat pump cycle. In this study, in order to improve the performance of absorber, the absorber of tangential feed of a liquid phase with spiral tube has been investigated using methanol-glycerine as a working fluid. The spiral tube and tangential feeding generate the turbulence into the liquid flow while increasing the mass and heat transfer coefficients. The simultaneous heat and mass transfer were found to take place in a liquid turbulent film in the absorber with the spiral tube during the process of gas absorption. By calculating mass and heat transfer coefficients by measurement of the concentration and the temperature of each position in the absorber, the entrance was found to be more effective in enhancing mass and heat transfer.

• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.986-994
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• 2017

In this paper, $CO_2$ absorption of scrubber was tested for removal of high concentration $CO_2$. Liquid to gas ratio($18L/m^3$) and Superficial velocity(0.14 m/s) was determined through Lab-scale test. As flow rates increase 1, 2, 3, 4 and $5m^3/min$, $CO_2$ removal efficiency decrease 98.47%, 96.46%, 92.95%, 89.71% and 85.49%. Also, the scrubber operation made energy improvement(5.4%), energy saving(11.5 TOE/year) and greenhouse gases reduction(6.5 TC/year).

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.359-365
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• 2008

Turbopump test for a 30-ton-thrust liquid rocket engine was carried out using real-propellant. Liquid oxygen, kerosene, cold hydrogen gas were used for the oxidizer pump, the fuel pump, the turbine, respectively. The turbopump was run stably at the design and off-design conditions and the performance requirements were satisfied, which implies that the turbopump development at the engine subsystem level is successfully accomplished in the point of performance validation. This paper presents the results of a test where the turbopump was run for 75 seconds at three operating modes. In terms of performance characteristics of pumps and turbine, the results from turbopump assembly test using real-propellant showed a good agreement with those from the turbopump component tests using simulant working fluid.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.545-550
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• 2012

High Energy density metal powder has high melting point of oxide film. By this, the ignition source that can make a thermal effect of high-temperature during short time is needed to overcome ignition disturbance mechanism by oxide film. So effective ignition does not occurred with hydrocarbon ignitor, $H_2-O_2$ ignitor, high power laser. But steam plasma can be generate about 5000 K temperature field in short order. Because a steam plasma uses steam as the working gas, it is environmental-friendly and economical. Therefore in this study, we analyze steam plasma temperature field and radical species with optical emission spectroscopy method in order to apply steam plasma ignitor to metal combustion system and cloud particle ignition was identified in visual.

• Safety and Health at Work
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• v.5 no.4
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• pp.227-233
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• 2014

Background: The aims of this study were to determine hippuric acid levels in urine samples, airborne toluene levels, acute and chronic neurological symptoms, and to describe any correlation between urinary hippuric acid and airborne toluene. Methods: The hippuric acid concentration in the urine of 87 paint workers exposed to toluene at work (exposed group), and 87 nonexposed people (control group) was studied. Study participants were selected from similar factories in the same region. Urine samples were collected at the end of a shift and analyzed for hippuric acid by high performance liquid chromatography. Air samples for the estimation of toluene exposure were collected with diffusive personal samplers and the toluene quantified using gas-liquid chromatography. The two groups were also interviewed and observed about their work practices and health. Results: The median of the 87 airborne toluene levels was 55 ppm (range, 12-198 ppm). The median urinary hippuric acid level was 800 mg/g creatinine (range, 90-2547 mg/g creatinine). A statistically significant positive correlation was found between airborne toluene exposure and urine hippuric acid levels (r = 0.548, p < 0.01). Workers with acute symptoms had significantly higher hippuric acid levels than those who did not (p < 0.05). It was concluded that there was a significant correlation between toluene exposure, hippuric acid levels, and health (p < 0.001). Conclusion: There appears to be a significant correlation between workers exposure to toluene at work, their urine hippuric acid levels, and resulting symptoms of poor health. Improvements in working conditions and occupational health education are required at these workplaces. There was good correlation between urinary hippuric acid and airborne toluene levels.

• Journal of The Korean Ophthalmological Society
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• v.59 no.11
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• pp.1077-1081
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• 2018

Purpose: We report two cases of corneal edema in patients who presented with bilateral blurry vision due to vaporized amines while working in a polyurethane processing plant. Case summary: A 28-year-old male presented with bilateral blurred vision. His work involved solidifying polyurethane liquid and he often found himself exposed to polyurethane heat and gas. Purpose: We report two cases of corneal edema in patients who presented with bilateral blurry vision due to vaporized amines while working in a polyurethane processing plant. Case summary: A 28-year-old male presented with bilateral blurred vision. His work involved solidifying polyurethane liquid and he often found himself exposed to polyurethane heat and gas. On examination, the patient's uncorrected visual acuity (UCVA) was 20/40 (right) and 30/50 (left). A slit lamp examination revealed subepithelial microbullae in both eyes. The central corneal thickness (CCT) was also increased in both eyes, measuring $698{\mu}m$ (right) and $672{\mu}m$ (left). After prescribing 0.5% moxifloxacin and, 1% fluorometholone eye drops for 3 days in both eyes, the UCVA recovered to 20/40 (right) and 20/20 (left). The CCT decreased to $644{\mu}m$ (right) and $651{\mu}m$ (left), and the microbullae improved significantly in the left eye. The second patient was a 34-year-old female who presented with bilateral decreased visual acuity while at work. She worked in a factory that produced car seat filling. Her UCVA was 20/25 (right) and 20/20 (left). The CCT by specular microscopy was $537{\mu}m$ (right) and $541{\mu}m$ (left). On slit lamp examination, both eyes demonstrated bilateral central subepithelial edema. The patient did not attend any follow-up outpatient appointments after the initial presentation. Conclusions: Exposure to vaporized amines such as polyurethane may causereversible corneal toxicityeven without direct contact. Further consideration should be given to ocular safety and protection from amine compounds in the industrial field.On examination, the patient's uncorrected visual acuity (UCVA) was 20/40 (right) and 30/50 (left). A slit lamp examination revealed subepithelial microbullae in both eyes. The central corneal thickness (CCT) was also increased in both eyes, measuring $698{\mu}m$ (right) and $672{\mu}m$ (left). After prescribing 0.5% moxifloxacin and, 1% fluorometholone eye drops for 3 days in both eyes, the UCVA recovered to 20/40 (right) and 20/20 (left). The CCT decreased to $644{\mu}m$ (right) and $651{\mu}m$ (left), and the microbullae improved significantly in the left eye. The second patient was a 34-year-old female who presented with bilateral decreased visual acuity while at work. She worked in a factory that produced car seat filling. Her UCVA was 20/25 (right) and 20/20 (left). The CCT by specular microscopy was $537{\mu}m$ (right) and $541{\mu}m$ (left). On slit lamp examination, both eyes demonstrated bilateral central subepithelial edema. The patient did not attend any follow-up outpatient appointments after the initial presentation. Conclusions: Exposure to vaporized amines such as polyurethane may causereversible corneal toxicityeven without direct contact. Further consideration should be given to ocular safety and protection from amine compounds in the industrial field.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.1
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• pp.103-113
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• 2020

Jack-up drilling rigs are widely used in the offshore oil and gas exploration industry. Although originally designed for use in shallow waters, trends in the energy industry have led to a growing demand for their use in deep sea and harsh environmental conditions. To extend the operating range of jack-up units, their design must be based on reliable analysis while eliminating excessive conservatism. In current industrial practice, jack-up drilling rigs are designed using the working(or allowable) stress design (WSD) method. Recently, classifications have been developed for specific regulations based on the load and resistance factor design (LRFD) method, which emphasises the reliability of the methods. This statistical method utilises the concept of limit state design and uses factored loads and resistance factors to account for uncertainly in the loads and computed strength of the leg components in a jack-up drilling rig. The key differences between the LRFD method and the WSD method must be identified to enable appropriate use of the LRFD method for designing jack-up rigs. Therefore, the aim of this study is to compare and quantitatively investigate the differences between actual jack-up lattice leg structures, which are designed by the WSD and LRFD methods, and subject to different environmental load-to-dead-load ratios, thereby delineating the load-to-capacity ratios of rigs designed using theses methods under these different enviromental conditions. The comparative results are significantly advantageous in the leg design of jack-up rigs, and determine that the jack-up rigs designed using the WSD and LRFD methods with UC values differ by approximately 31 % with respect to the API-RP code basis. It can be observed that the LRFD design method is more advantageous to structure optimization compared to the WSD method.