• Journal of the Korean Society of Safety
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• v.21 no.2 s.74
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• pp.138-142
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• 2006

Occupational asthma is commonly known to be induced by isocyanate exposure. Spray painters generally use isocyanates for 2-pack spray painting to coat wooden panel surfaces in the furniture industry in South Australia. Due to a lack of actual exposure data, this study conducted environmental and dermal/ocular monitoring from a company in the furniture industry. According to this study, there was no significant airborne contamination, due to the use of high volume low pressure (HVLP) spray guns, low concentration of hardener in paint solutions and appropriate respirator like full face-air line respirator. There was no significant HDI detection in the general work area around the spray booths. Owing to the use of disposable nitrile gloves during the spray painting, no significant dermal exposure was found. According to color monitoring, there was a possible dermal exposure from surfaces in the workplace, unless either protective gloves were worn or appropriate working practices like clean-up process and storage in a secure places. No eye contamination was detected from the spray painters. No significant exposure levels from inhalational, dermal, ocular were found. The area of most concern was work practices.

• Explosives and Blasting
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• v.38 no.1
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• pp.1-13
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• 2020

Gas explosion accidents are steadily being issued due to increased gas consumption in Korea and foreign countries. To analyze the effects of these gas explosions, a TNT equivalent method is used. In this study, the TNT equivalent was calculated in the event of an explosion due to the volume content in the air of CO, CH₄ and C₂H₄, the typical flammable gases emitted by coal. Also, the peak overpressure and impulse variation with the distance from explosion point were compared and analyzed by gas using the calculated equivalent value of TNT. The upper limit of the TNT equivalent for the three mixed gases is up to five times larger than the other gases mixture. In addition, the peak overpressure and impulse, which are factors of the TNT characteristic curve, are also increasing as the number of gases increases.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.3
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• pp.160-166
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• 2014

In this research, as a measure of reducing energy lost through external wall, we used Glass Hollow Micro Sphere (HMS) to improve insulation performance to structural concrete. The following is a result of experimenting concrete using HMS. As usage of HMS, decrease in slump arose and it is judged as a need of using superplasticizer. Replacement ratio increasing more and more, amount of air showed tendency to decrease and compressive strength decreased for interfacial adhesion had not been formed. as replacement ratio and unit volume decreased. It appears that thermal conductivity decreased about 30.0~46.5 percent as compared with normal weight concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.4
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• pp.60-67
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• 2018

As the lack of specific aggregation intensifies, the development of alternative resources is urgent. Construction waste is increasing every year, but recycled aggregate is used as a low value added material. Various studies are currently underway at the national level. In this paper, the mechanical performance of the concrete according to the concrete mixing method and the replacement amount of the circulating coarse aggregate was compared and evaluated. Concrete mixing method was normal mixing approach(NMA) method, two-stage mixing approach1 (TSMA1) method, two-stage mixing approach2 (TSMA2) method. Fresh concrete was tested for air content, slump test, and unit volume weight. Compressive strength and flexural strength were tested in hardened concrete. According to the TSMA method, the mechanical performance difference of concrete is shown, and the strength is decreased according to the circulating coarse aggregate replacement amount.

• Journal of the Korean Geosynthetics Society
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• v.2 no.2
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• pp.25-31
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• 2003

Most recently, environmental problems arise from management waste tires by increasing number of automobiles. Waste tires are not compressible and not easy for degradation in landfill. Even if it were landfill, it is difficult to treat. Total amount of waste tires is about 20 million per year and the collection is 68.6% in this country. Structure of slope stability using waste tire blocks filled with concrete increases durability, reduce construction period, and it can be utilized as an example. Therefore, it reduces the volume of waste and recycles waste. Also, it prevents the air pollution due to the incineration and creates economic value.

• Korean Chemical Engineering Research
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• v.40 no.6
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• pp.757-762
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• 2002

The interest of incineration, which is one of the effective methods for municipal waste disposal, has gradually increased because the incineration could reduce the volume and weight of the waste, and produce useful energy from the waste. This study has developed the 3-dimensional numerical model, and applied for the investigation of combustion characteristics and optimized operating conditions in MSW incinerator in Gwangju. The model developed in this study has been verified through the comparison between the predicted and the measured temperature in combustion chamber which is operating. By predictive results, the Sangmoo incinerator has a good characteristics of combustion efficiency and a low emission by the second burning in the main flame zone, even though after burning zone produces incomplete products by which primary air is introduced not enough.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2007-2009
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• 1999

In this paper, discharge domain of wire-cylindrical plasma reactor was separated from a gas flow duct to avoid unstable discharge by aerosol particle deposited on discharge electrode and grounded electrode. The NOx, SOx removal was experimentally investigated by a reaction induced to ammonium nitrate, ammonium sulfate using a low price of aqueous NaOH solution and a small quantity of ammonia. Volume percentage of aqueous NaOH solution used was 20% and $N_2$ flow rate was 2.5[$\ell$/min] for bubbling aqueous NaOH solution. Ammonia gas(14.82%) balanced by argon was diluted by air and was introduced to a main simulated flue gas duct through $NH_3$ injection system which was in downstream of reactor. The $NH_3$ molecular ratio[MR] was determined based on $NH_3$ to [NO+$SO_2$]. MR is 1.5. The NOx removal rates increased in the order of DC, AC and pulse, but SOx removal rates was not significantly effected by source of electricity. The NOx removal rate slightly decreased with increasing initial concentration but SOx removal rate was not significantly effect by initial concentration, and NOx, SOx removal rates decreased with increasing gas flow rate.

• Journal of ILASS-Korea
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• v.22 no.4
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• pp.210-217
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• 2017

A gasoline direct injection engine has an intake air temperature can be lowered by the fuel vaporization in the combustion chamber increase the volume efficiency is high compression ratio. Therefore, study for injection rate and characteristics which influence mixture formation in combustion chamber is important. Movement of the injector needle has a direct effect on the injection of the fuel, such as formation of cavitation, the fuel injection rate, etc. Therefore, recent studies on the dynamic characteristics of the injector considering the movement of the needle have been reported, but it takes a lot of time and cost to experimentally confirm the movement of the needle inside the injector. In this study, AMESim, a commercial 1-D code, and Star-CCM+, a 3-D CFD code, were used to predict the dynamic performance of the injector with needle motion. In order to predict the movement of the needle under the high pressure, the result of the surface pressure distribution according to the movement of the needle was derived by using the morphing technique of flow analysis. In addition, we predicted the injection rate of the injector considering the movement of the needle in conjunction with the 1-D code. The injection rate of the injector was measured by the BOSCH's method and the results were similar to those of the simulation results. This method can predict the injection rate and injection characteristics and this result is expected to be used to predict the performance of gasoline direct injection engines with low cost and time in the future.

• Asian Journal of Turfgrass Science
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• v.10 no.3
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• pp.263-270
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• 1996

This experiment was conducted to investigate the loss of various herbicides by means of vola-tility from the turfgrass field and the hare ground with the different soil moisture contents and temperatures. Different herbicides were applied at the rates of 375 g a.i. /l0a of pendimethalin,250 g a.i. /l0a of napropamide, and 96.4 g a.i. /l0a of dicamba with 200 \ulcorner/10a of spray volume in the turfgrass(Zoysia japonica cut off 5cm) grown in pots(265.8 $cm^2$) and bared soil. The pots were placed in the growth chamber with 10,000 lux of light intensity(12h per day) at 25 and 35˚C for 7days. Amberlite XAD polymeric resin(20/50 mesh) was used as sampling media for herbicide airborne residues. Air flow was maintained at 10 \ulcorner /min by vacuum pump regulated with a factory calibrated flow meter. Herbicide airborne residues were extracted from the XAD resin with 300 ml of 1:1 acetone and hexane. The extracts were concentrated by rotary evaporation at 35˚C and dissolved in 1 ml MeCN for HPLC analysis. The airborne losses of the herbicide applied in the turfgrass and bare soil increased as the temperature and soil moisture contents were increased, regardless of the kinds of herbicide. Higher airborne residues was observed in the turfgrass pots than the bare soil pots. Pendimethalin and dicamba with higher vapor pressure gave rise to the increased loss of airborne herbicides, showing that 6.26 and 6.4% of average airborne loss in pendimethalin and dicamba, respectively, compared to 0.56% in napropamide. The amount of airborne losses in turfgrass was highest at one day after application and then a declined trend was observed as the time was prolonged. Key words. Herbicides, Turfgrass field, Bare ground, Volatility.

• Korean Journal of Materials Research
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• v.28 no.7
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• pp.391-397
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• 2018

This study deals with the microstructure and tensile properties of 700 MPa-grade high-strength and seismic reinforced steel bars. The high-strength reinforced steel bars (600 D13, 600 D16 and 700 D13 specimens) are fabricated by a TempCore process, while the seismic reinforced steel bar (600S D16 specimen) is fabricated by air cooling after hot rolling. For specimens fabricated by the TempCore process, the 600 D13 and 600 D16 specimens have a microstructure of tempered martensite in the surface region and ferrite-pearlite in the center region, while the 700 D13 specimen has a microstructure of tempered martensite in the surface region and bainite in the center region. Therefore, their hardness is the highest in the surface region and shows a tendency to decrease from the surface region to the center region because tempered martensite has a higher hardness than ferrite-pearlite or bainite. However, the hardness of the 600S D16 specimen, which is composed of fully ferrite-pearlite, increases from the surface region to the center region because the pearlite volume fraction increases from the surface region to the center region. On the other hand, the tensile test results indicate that only the 700 D13 specimen with a higher carbon content exhibits continuous yielding behavior due to the formation of bainite in the center region. The 600S D16 specimen has the highest tensile-to-yield ratio because the presence of ferrite-pearlite and precipitates caused by vanadium addition largely enhances work hardening.