• Korean Journal of Environmental Biology
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• v.32 no.1
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• pp.49-57
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• 2014

Orb-web spiders can be considered as an effective bio-indicative animal to monitor the ecological air pollution of certain habitat since they have limited shifting ability during their life spans. In this study we revealed the fine structural characteristics of booklung in the orb-web spider Nephila clavata, and its bio-indicative significance in the monitoring environmental asbestos exposure. The high resolution scanning electron microscopy results suggest that the cuticular spikes near the atrium could be act as an effective filtering structure for dust materials. Furthermore, inner cuticular spikes which protruded across the air sacs, have the functions not only sustaining appropriate respiratory volume of each air sac but also help to enhance respiratory capacity by maximizing the gross surface area for gas exchange. Interestingly, in spite of short exposure, the asbestose fibrils were effectively captured on the surface of the atrial cuticular spikes. Furthermore, histologic damages were observed due to penetration of asbestos fibrils through air sacs and fixed on the hemolymph space. In addition, although accumulated mass of hemocytes were observed near the fibrils, there were no asbestos bodies or coagulated hemocytes were found on the surface of the fibrils, This could be mainly due to the short exposure period towards asbestos. Briefly, these results indicate the spider's booklung could be valuable tool in the detection ecological air pollutants.

• Journal of the Institute of Convergence Signal Processing
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• v.14 no.2
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• pp.130-135
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• 2013

Recently, the needs of system performances such as working speed and processing accuracy in machine tools have been increased. Especially, the working speed increment generates harmful heat at both moving part of the machine tools and handicrafts. The heat is a main drawback to progress accuracy of the processing. Hence, a oil cooler to control temperature is inevitable for the machine tools. In general, two representative control schemes, hot-gas bypass and variable speed control of a compressor, have been adopted in the oil cooler system. In this paper, the compressor's speed are controlled to keep reference value of temperature at oil outlet. The precision processing of a machine tool is required for an oil cooler guaranteeing ${\pm}0.1^{\circ}C$ temperature control. But the oil cooler with precision temperature control is expensive. Therefore in this paper, instead of a on/off(relay) control method, a PID and phase angle electric power control method is proposed for the precision control of an oil cooler. The proposed controller is implemented and tested at the temperature of $23^{\circ}C$, $24^{\circ}C$ and $25^{\circ}C$.

• Journal of IKEEE
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• v.13 no.4
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• pp.37-42
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• 2009

In this study, nanopower ZnO and $SnO_2$ as sensing materials were prepared by hydrazine and hydrothermal routes, respectively, and were doped with Pd, Ru catalyst. The CO and $NO_2$ sensors were fabricated by coating of sensing materials on the MEMS-based structure with electrodes and heaters. The 0.1 wt% Pd doped $SnO_2$ sensor and Ru doped ZnO sensor showed the high sensor response to CO 30 ppm and $NO_2$ 1 ppm, respectively. The sensor signal was stable. This can be used for the detection of pollutant gases emitted from gasoline engine.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.635-638
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• 1999

The effect of proteolytic enzyme on the unhairing process has been studied. this enzyme significantly changed the physical properties of pelt for leather shoes. A SEM was used to examine physical properties of the pelt. Even though bio-tech treatment using proteolytic enzyme slightly reduced the degree of unhairing compared to chemical treatment. Physical property of the pelt is better and this method is environmentally favorable. $H_{2}S$ gas produced in the chemical treatment was not detected and the value of COD and BOD for waste water after the unhairing process were reduced to 939 mg/L and 5268 mg/L, respectively. We found that a process with 0.4~0.5% proteolytic enzyme for 20 h at $29{\sim}30^{\circ}C$ is most suitable for the unhairing process.

• Journal of the Korean GEO-environmental Society
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• v.1 no.1
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• pp.13-18
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• 2000

The purposes of this study are the analysis of landfill gases(LFGs) in old open dumping landfill site near middle city and offer the useful data for reusing the landfill site as the residental, commercial and other purposes. The concentration of $CO_2$ and $CH_4$ were lower as 8.28 vol% and 1,247 ppm but the concentrations of $NH_3$ and $H_2S$ were 7 times and 12 times higher than TLV-TWA standard. The concentration of $CH_4$ and other gases were lower than the ACGIH criterion. As the result of the environmental assessment on the open dumping landfill, if appears that this landfill is maturation phase and the formation of LFGs is reduced. If the treatment facility of $NH_3$ and $H_2S$ gases is prepared, it can be safely used as this landfill site.

• Journal of Environmental Health Sciences
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• v.46 no.5
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• pp.555-564
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• 2020

Objectives: To identify and investigate through qualitative and quantitative analysis the hazardous substances generated when compressed wood was burned at a live fire-training center. Methods: Four types of compressed wood that are actually used in live fire training were burned in a chamber according to KS F2271. The gaseous material was sampled with a gas detector tube and conventional personal samplers. Results: 1,3-butadiene, benzene, toluene, xylene, formaldehyde, hydrogen chloride, hydrogen cyanide, ammonia, carbon monoxide, and nitric acid were detected. In particular, 1,3-butadiene (497.04-680.44 ppm), benzene (97.79-125.02 ppm), formaldehyde (1.72-13.03 ppm), hydrogen chloride (4.71-15.66 ppm), hydrogen cyanide (3.64-8.57 ppm), and sulfuric acid (3.85-5.01 ppm) exceeded the Korean Occupational Exposure Limit as measured by sampling pump according to the type of compressed wood. Conclusions: We found through the chamber testing that firefighters could be exposed to toxic substances during live fire training. Therefore, firefighter protection is needed and more research is required in the field.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.1
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• pp.53-61
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• 2006

Recently, lots of researchers have been attracted to develop various alternative fuels and to use renewable fuels in order to solve the exhaust emission problems. DME (Dimethylether) is synthetic fuel, and can be produced from natural gas, coal and biomass. The emission is clean because it contains little sulfur and aromatic components In this study, the fuel was tested to investigate the applicability as an alternative fuel for diesel. This study was carried out by comparing the exhaust emissions and performance of diesel engine with DME, ULSD (ultra low sulfur diesel), LSD (low sulfur diesel) respectively. In order to measure regulated emissions, CO, $NO_{3}$, HC from vehicle different fuel types were used on chassis dynamometer CVS (constant volume sampler)-75 mode and EPA TO-I1A method was chosen for aldehydes analysis.

• Environmental Analysis Health and Toxicology
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• v.24 no.3
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• pp.181-191
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• 2009

As an effort to prevent serious accidents involving oxygen deficiency and suffocation in confined spaces and to identify the causes of such accidents, the present study investigated relevant accidents and systems in Korea and other countries. This study also conducted a number of experiments at lethal concentration levels of oxygen deficiency using SD rats and observed the changes of experimental animals with humidity, organic gas (toluene), hydrogen sulfide, carbon monoxide and so on at the oxygen deficient environment. The results of the study are as follows. 1. The results from the experiment conducted using SD rats at lethal concentration levels of oxygen showed that there were no casualties at the 7% oxygen concentration level, but the mortality increase to 20% at 6% oxygen, it was jumped to 90% at 5% oxygen, and it was also dramatically reached 100% at 4% oxygen concentration. Therefore, 5.5% was calculated as the $LC_{50}$ (rat, 4hr) from these dose-response experiments with oxygen deficiency. 2. When we changed the level of toluene, $H_2S$, CO, humidity, and so on, in an oxygen deficient environment, it was observed that the small concentrations of $H_2S$ and CO make the highest effect on animals. In case of 350 ppm $H_2S$, it resulted in 30% mortality, and the 100% mortality was shown in 1,200 ppm CO concentration. The mortality increased as an oxygen deficient condition. However in the case of toluene up to 1,000 ppm, it were not affected with oxygen deficiency, and it did not indicate any significant differences in mortality as 20%, 90% humidities.

• Journal of Sensor Science and Technology
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• v.7 no.5
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• pp.327-333
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• 1998

A new human sensibility (kansei) meter that can measure human sensibility at the indoor environment is developed in this paper. Four sensors that can measure temperature, humidity, $CO_2$ and $C_4H_{10}$ concentrations are used. Among these sensors, the first three are used to determine the human sensibility. And the last to protect human from the harmful gas. First of all, human sensibilities are defined for each sensor datum, and then those are linearly combined to make a final human sensibility (kansei). The efficiency and usefulness of the meter are verified using a simulator on Windows 95 and a stand-alone system constructed using a microprocessor.

• Analytical Science and Technology
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• v.26 no.1
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• pp.73-79
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• 2013

The allyl isothiocyanate, capsaicin and dihydrocapsaicin as main components in self defense sprays were determined by gas chromatography-mass spectrometer (GC-MS). Although self defense spray was used to protect by myself, a social problem could be caused by the hazard of spray chemical due to use pungent liquid. To identify this, the pH of pungent liquid solutions, solubility to detergents, the existence of other materials and the types and amounts of pungent material in spray chemicals were investigated in this work. Finally, the amounts of allyl isothiocyanate, capsaicin and dihydrocapsaicin as pungent materials in them were determined by GC-MS. The pH of chemicals were about 5.7 as weak acid, the detergents can emulsify them with water well. And they did not contain fluorescent materials and hazard organic solvents. The pungent components in three real samples were only allyl isothiocyanate [47,600 mg/kg (47.6%)] in one sample, and mixtures with capsaicin [228 mg/kg~368 mg/kg (1.14%~1.84%)] and dihydrocapsaicin [224 mg/kg~414 mg/kg (1.12%~2.07%)] in the others, respectively.