• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.7 no.1
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• pp.33-48
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• 1997

Korean diffusive sampler (KDS) and charcoal tube (CT) were used for sampling n-hexane, trichloroethylene and toluene in air KDS was made by Department of Environmental Health, SNU-SPH in 1995. Surveys were conducted at ten industrial plants with organic solvents. The relationship between two sampling methods was examined by linear regression analysis, and concentrations by two sampling methods were compared using paired t-test. The results are as follows: 1. The geometric means by CT and KDS methods were 3.26ppm and 3.32ppm for n-hexane, 5.07ppm and 6.34ppm for toluene, and 7.18ppm and 7.90ppm for toluene, respectively. There was no significant difference between results by CT and KDS methods in three organic vapors (p>0.05). When linear regression analysis was performed, two sampling methods were highly related ; correlation coefficients were 0.98, 0.90 and 0.96 for n-hexane, toluene and trichloroethylene, respectively. 2. Airborne concentrations of n-hexane (n=21) were below 0.5 TLV level. The GM by two methods were almost same (3.09 ppm). And there was no significant difference between results by two methods (p>0.05). 3. Since toluene and trichloroethylene concentrations showed several levels, appropriate sampling rates were applied for each level. The GM of toluene concentrations by two methods at 0.5 TLV level were 3.75ppm and 5.48ppm. The KDS method overestimated the toluene concentrations at 0.5 TLV level (p<0.05). The GM values of toluene concentrations at 1 TLV level were 31.80ppm and 25.38ppm and at 2 TLV level were 64.13 ppm and 51.37 ppm. The KDS method underestimated concentration at both level (p<0.05). For trichloroethylene, the GM at 0.5 TLV level were 4.97 ppm and 7.11ppm. The KDS method overestimated the concentration of trichloroethylene (p<0.05). In conclusion, concentrations of three organic vapors measured by CT and KDS were not significantly different and results by two methods were highly related. But at contain concentrations, the levels by method were significantly different. Therefore, it is suggested that sampling rate of KDS should be studied simultaneously using CT method for organic vapors.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1990.10a
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• pp.35-40
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• 1990

Temperature distribution of high pressure mercury lamp has been mesured as a function of time using spectroscopic method. Sampling signal which is synchronized by lamp voltage was used to mesure temporal line intensity at each radius. To obtain radial temprature distribution, the mesured intensity was transformed into radial line intensity by Abel's formula. Absolute temperature profile was calculater from relative intensities of spectral lines as a function of line and tube radius. The temperature profile is very similar to the electrical tube current profile.

• Proceedings of the KWS Conference
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• 2003.05a
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• pp.117-119
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• 2003

Power plant efficiency and availability depend greatly on condenser performance. However, during commissioning of Yeonggwang #1/2 steam condenser sodium leakage occurred, because of tube to tubesheet only roll expanding. Therefore this report is explaining that pre-test for the shake of improvement reliable repair processes & selected sampling tube re-expansion in-situ applications.

• Environmental Analysis Health and Toxicology
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• v.17 no.2
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• pp.95-107
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• 2002

This study was designed to investigate the characteristics of atmospheric concentrations of toxic volatile organic compounds (VOCs) in Korea. Target compounds included 1,3-butadiene, aromatics such as BTEX, and a number of carbonyl compounds. In this paper, as the first part of the study, the performance of sampling and analytical methods was evaluated for the measurement of selected VOCs and carbonyl compounds in the ambient air. VOCs were determined by the adsorbent tube sampling and automatic thermal desorption coupled with GC/MSD analysis, while carbonyls by the DNPH-silica cartridge sampling with HPLC analysis. The methodology was investigated with a wide range of performance criteria such as repeatability, linearity. lower detection limits, collection efficiency, thermal conditioning, breakthrough volume and calibration methods using internal standards. In addition, the sampling and analytical methods established in this study were applied to real field samples duplicately collected in various ambient environments. Precisions for the duplicate samples appeared to be comparable with the performance criteria recommended by USEPA TO-17. The overall precision of the sampling and analytical methods was estimated to be within 20 ∼ 30% for major aromatic VOCs such as BTEX, whereas the precision for major carbonyl compounds such as formaldehyde and acetaldehyde was within 10 ∼ 20% for field samples. This study demonstrated that the adsorbent sampling and thermal desorption method can be reliably applied for the measurement of BTEX in ppb levels frequently occurred in common indoor and ambient environments.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1365-1369
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• 2008

A large diameter sampler (KICT-type large diameter sampler) was developed to take undisturbed samples from not only soft ground but also sandy and weathered ground. The KICT-type large diameter sampler was manufactured with the principle of triple core barrel sampling. In this study, the applicability to offshore ground sampling of the KICT-type large diameter sampler was confirmed at Inchoen Port construction site. And, in order to compare the quality of samples taken by the sampler with that of the traditional piston sampler, a series of laboratory tests were performed. From the test results, the samples taken by the KICT-type large diameter sampler showed higher quality than the traditional thin-walled tube samples.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.3
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• pp.398-405
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• 2003

A fast response analyzer for measuring carbon dioxide concentration has been developed for transient characteristic and researches tested on internal combustion engine. The analyzer uses the well known NDIR(Non-Dispersive Infrared) method with miniaturized detection system, giving a time constant of approximately 30 microsecond, and sampling module consists of capillary tube. Since the transit time and the time constant of the sampling system depend on the sampling conditions, it is necessary to investigate the characteristics of sampling system before applied to exhaust gas measurement in engine. A unique method was designed to study the influence of the diameter of transfer sample line and operating conditions of the FRNDIR on transit time and time constant. A database of transit time and time constant was built up for different measured and simulated pressure conditions. The database can be used for correcting eventual $CO_2$ concentration measurement.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.1
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• pp.126-146
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• 2000

To develop and evaluate formaldehyde measurement method using 2,4-dinitro-phenylhydrazine (2,4-DNPH) coated sampler and gas chromatography, laboratory test and field test were conducted. Results of this study are as follows. Limit of detection(LOD) of measurement methods, HPLC-UVD, GC-NPD and GC-FID, is $0.008{\mu}g/m{\ell}$ $0.060{\mu}g/m{\ell}$, $0.472{\mu}g/m{\ell}$ respectively. Coefficiency of measurement methods, HPLC-UVD, GC-NPD and GC-FID, is 0.008, 0.009, 0.020 respectively. Desorption efficiency of sep-pak xposure aldehyde sampler and sorbent sample tube is 1.05(range : 0.99 - 1.12), 1.02(range : 0.99 - 1.06) respectively. Samples of sorbent sample tube and sep-pak xposure aldehyde sampler turned out to be stored at refrigerator, according to storage test results. Measurement methods of HPLC-UVD, GC-NPD, GC-FID, according to results of precision for the combined sampling and analytical procedure, became acceptable to OSHA evaluation standard. Field test using exposure chamber met the NIOSH overall uncertainty recommendation(less than 25%). Overall uncertainty of Sepak-HPLC(UVD), Tube-GC(NPD), Tube-GC(FID) is 11.0% - 17.0%. Consequently gas chromatography(GC-NPD, GC-FID) and high performance liquid chromatography(EPA TO-11) using 2,4-DNPH coated sampler for formaldehyde measurement turned out to be suitable to measure personal formaldehyde exposure at workplaces.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.9 no.1
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• pp.173-186
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• 1999

To utilize diffuse sampling of formaldehyde in air, a new sampler was designed. A glass fiber filter was impegnated with 2,4-dinitrophenylhydrazine(DNP) and phosphoric acid and mounted 37mm cassette. The formaldehyde vapor was sampled in the dynamic chamber and measured by high performance liquid chromatograph and compared with solid sorbent tube. The results were as follows ; 1. The desorption efficiencies of diffusive sampler between 97.0% and 100%. 2. the sampling rate is constant as in $58{\sim}61.8m{\ell}/min$ when sampling times are between 120 and 360 min. 3. There was a significant relationship between concentrations of diffusive samples and active samples with the coefficient of determination(R2) of 0.92. 4. Desorbed amount of formaldehyde diffusive sampler was increased by high relative humidity. 5. Wheth diffusive samplers were stored at room temperature or at refrigerator there was no statistically significant difference in the accuracy of result. 6. When the diffusive samplers, which collected formaldehyde vapor, were exposed to clean air for three hours, there was no significant loss of formaldehyde due to reverse diffusion. In conclusion, this study suggest that developed diffusive samplers will be a reasonable substitute for the solid sorbent tube for sampling formaldehyde and practical comparative study of developed diffusive sampler should be performed at workplaces of manufacturing industry.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.2
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• pp.127-136
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• 1994

Diffusional sampling devices offer many advantages for measuring concentration levels of industrial contaminants than the conventional pump and charcoal tubes because they are lightweight, require no power, pump or tubing. This study designed to evaluate and compare the sampling performance of passive sampler to charcoal tube from mixed organic solvent workplace with 181 organic solvent using workers working in different concentration of organic solvents. All study workers kept both devices in their breathing zone simultaneuosly in the workplaces, and the sampling analytical results were compared with those of charcoal tube. The results obtained are as follows: 1. The concentrations of toluene and xylene measured by passive sampler were slightly higher than those of charcoal tube, but there were no significant statistical differences between two methods. 2. The concentrations of MEK and cyclo-hexanone measured by passive sampler in low exposure workplace (below 0.20 of MEK TLV levels and 0.1 of cyclo-hexanone TLV levels) were about 2 times higher than that of charcoal tube sampling. While, absorption efficiency of passive sampler was reduced according to increasing concentration measurements of MEK and cyclo-hexanone in air. 3. The ratios of concentrations of toluene, xylene, MEK and cyc1o-hexanone measured by passive sampler over those measured by charcoal tube were 1.11, 1.07, 1.63 and 3.65 respectively. 4. The percentages of concentration of passive samplers within 0.75 and 1.25 of charcoal tube value as a reference value of 1.0 were 57% in toluene, 74% in xylene, 34% in MEK and 32% in cyclo-hexanone respectively. 5. The correlation coefficients of toluene, xylene, MEK and cyclo-hexanone between passive sampler and charcoal tube sampler were 0.963, 0.957, 0.943 and 0.562 with statistical significance.

• Journal of Korea Soil Environment Society
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• v.3 no.1
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• pp.3-9
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• 1998

This paper presents soil-gas surveying technique to delineate an area contaminated with volatile organic compounds, which are common solvents and constituents of gasoline. The sampling method of soil-gas surveying is 1) grab sampling, which actively takes sample using a pump, or 2) passive sampling, which takes sample through diffusion in a trap filled with absorbent. The grab sampling shows the level of contamination at a certain location at a certain time, while the passive sampling shows the change in the contamination at a certain location. The analysis of soil gas can be performed with 1) a small portable detectors such as PID (photoionization detector) or FID (flame-ionization detector) to measure the total hydrocarbon in the soil gas, 2) a gas detector tube, which is filled with indicator reagents and changes its color with concentrations of the gas of interest, or 3) a portable GC (gas chromatograph), which can analyze different compounds simultaneously. The soil-gas surveying technique is a much less expensive method to investigate area contaminated volatile organic compounds and thus can be used as a screening tool to identify an area, which needs to be further investigated.