• Analytical Science and Technology
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• v.34 no.5
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• pp.202-211
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• 2021

Volatile organic compounds (VOCs) in hazardous air pollutants (HAPs) have been regulated by the Air Pollution Control Act (1978) and their atmospheric concentrations have been monitored in 39 monitor sites in Korea. However, measurement standards of volatile organic compounds (VOCs) in HAPs at ambient levels have not been established in Korea. Primary reference gas mixtures (measurement standards) at ambient levels are required for accurately monitoring atmospheric VOCs in HAPs and managing their emissions. In this study, primary reference gas mixtures (PRMs) at 5 nmol/mol were developed in order to establish primary national standards of VOCs in HAPs at ambient levels. Primary reference gas mixtures (PRMs) were prepared in pressurized aluminum cylinders with special internal surface treatment using gravimetric method. Analytical methods using gas chromatography-flame ionization detector (GC-FID) coupled with a cryogenic preconcentrator were also developed to verify the consistency of gravimetrically prepared HAP VOCs PRMs. Three different columns installed in the GC-FID were evaluated and compared for the retention times and separation of eighteen target components in a chromatogram. Results show that the HAP VOCs PRMs at 5 nmol/mol were consistent within a relative expanded uncertainty (k=2) of less than 3 % except acrylonitrile (less than 6 %) and the 18 VOCs were stable for 1 year within their associated uncertainties.

• Bulletin of the Korean Chemical Society
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• v.22 no.12
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• pp.1341-1344
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• 2001

Comparison of sulfur dioxide primary standard gases of the Korea Research Institute of Standards and Science (KRISS, Korea) and the National Physical Laboratory (NPL, UK) was performed. 100 ${\times}$10-6 mol/mol and 1,000 ${\times}$10-6 mol /mol primary standard gases (designated NPL S115 and S114, respectively) prepared gravimetrically and validated in NPL were used as transfer standards. Transfer standards were analyzed by NDIR sulfur dioxide analyzer and compared with KRISS PSM 112-03-624 and PSM 112-03-625 prepared gravimetrically. Adsorption corrected relative deviations of the primary standard gases were agreed to within 0.1%, and this agreement is within the expanded uncertainties (k = 2) of the primary standards at the two laboratories.

• Analytical Science and Technology
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• v.27 no.6
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• pp.357-363
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• 2014

Isoprene is a one of the biogenic volatile organic compounds (BVOCs) and it is known as a source of the tropospheric ozone and formaldehyde. In addition, isoprene is a trace component of the exhaled breath and it is a potential biomarker for the diagnosis of diseases such as lung cancer. In these regards, isoprene gas standards are required for the accurate measurement of isoprene in air samples. To establish a standard for isoprene gas, gravimetric preparation and characterization of primary gas standards were studied. The primary gas standards were produced independently in 4 aluminum cylinders and concentrations were examined by GC-FID. As a result, the uncertainty of the gravimetric preparations including purity of the raw material was 0.01% and reproducibility of the preparation of independent 4 cylinders was 0.08%. The primary gas standards for isoprene showed 14 months of long-term stability. The relative expended uncertainty of 2.8% (95% of confidence level, k=1.96) was assigned to the certified value of 10 ${\mu}mol$/mol level of isoprene based on the quantitative evaluation of the purity, weighing, reproducibility, adsorption and long-term stability.

• School Mathematics
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• v.3 no.2
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• pp.325-354
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• 2001

The study aims to develop balanced performance assessment tasks for primary school mathematics which can be implemented in the primary school easily. In order to these purposes, I suggest the types of performance assessment tasks and the framework of assessment standards for the balanced performance assessment with describing the procedures of developing tasks and rubrics. The types of task are journal writing, problem posing, constructed task, and descriptive task. In the framework of assessment standards, I suggest holistic scoring which are classified as four levels according to the degree of excellence which students perform totally concerning about the criterion of implication, reasoning, accuracy, and communication. Also I analyse the responses of children to the task “make a beautiful pattern” and suggest its assessment rubric and anchor papers for each level for illustrating the process of developing a rubric in holistic scoring. In order to reflect the viewpoints of children and their Parents concerning about the tasks, the responses in self assessment and parent assessment are analysed. Finally, methods of implementing the assessment tasks and considerations are discussed.

• Progress in Superconductivity
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• v.11 no.2
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• pp.96-99
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• 2010

We measured electrical shot noise in a metal-insulator-metal tunnel junction, which was made by using electron-beam lithography and double-angle evaporation technique. Since the dependence of the shot noise on bias voltage and temperature is theoretically well known, we can determine the temperature of the junction by measuring the noise as the voltage across the junction is changed. A cryogenic low noise amplifier was used to amplify the noise signal in the frequency range of 600-800 MHz, which enabled fast measurement of noise signal and thus temperature. With further study, this method could be useful for primary thermometry in cryogenic temperatures.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.2
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• pp.89-95
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• 2017

This study aimed to compare the primary heating energy consumption of regional apartment houses based on the enhanced thermal insulation performance of building envelope standards. The difference of the heating energy consumption based on the enhanced thermal insulation performance of building envelope standards in the southern region, the largest regional difference in primary heating energy consumption, is $10.3kWh/(m^2{\cdot}year)$. The difference of the heating energy consumption based on the enhanced thermal insulation performance of building envelope standards in the central region is $8.0{\sim}8.5kWh/(m^2{\cdot}year)$ and that of the Jeju region is $0.5kWh/(m^2{\cdot}year)$. These energy consumption differences do not result in building energy efficiency ratings changing. The building energy efficiency ratings have the possibility to be changed.

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.2
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• pp.331-341
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• 2018

Hazardous air pollutants(HAPs) in the atmosphere are regulated as major air pollutants in Korea by the Air Pollution Control Act. In order to manage and control HAPs, accurate standards, which are traceable to the International System of Units(SI), are required. In this study, primary standard gas mixtures(PSMs) of volatile organic compounds(VOCs) which are specified as HAPs were developed at $1{\mu}mol/mol$ levels. The selected fourteen VOCs include Benzene, Toluene, Ethylbenzene, m-Xylene, Styrene, o-Xylene, Chloroform, 1,1,2-Trichloroethane, Trichloroethylene, Tetrachloroethylene, 1,1-Dichloroethane, Carbon tetrachloride, 1,3-Butadiene, and Dichloromethane. The HAPs PSMs were gravimetrically prepared in aluminum cylinders and their consistency was verified within the relative expanded uncertainty of 0.71% (k=2). Potential adsorption loss onto the internal surface of cylinders was estimated by cylinder-to-cylinder division method. No adsorption loss was observed within the uncerainty of 0.53%. The long-term stability of the HAPs PSMs was evaluated comparing with freshly prepared HAPs PSMs. The HAPs PSMs were stable for one year within the uncertainty of 0.38%. The final uncertainty of the PSMs was determined by combining the preparation uncertainty, verification uncertainty, and stability uncertainty. Finally, traceable and stable HAPs PSMs at $1{\mu}mol/mol$ levels were developed with the uncertainty of less than 0.76% in high-pressure aluminum cylinders.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1698-1702
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• 2013

Glucose is a common medical analyte measuring in human serum or blood samples. The development of a primary method is necessary for the establishment of traceability in measurements. We have developed an isotope dilution liquid chromatography tandem mass spectrometry as a primary method for the measurement of glucose in human serum. Glucose and glucose-$^{13}C_6$ in sample were ionized in ESI negative mode and monitored at mass transfers of m/z 179/89 and 185/92 in MRM, respectively. Glucose was separated on $NH_2P$-50 2D column, and the mobile phase was 20 mM $NH_4OAc$ in 30% acetonitrile/70% water. Verification of this method was performed by the comparison with NIST SRMs. Our results agreed well with the SRM values. We have developed two levels of glucose serum certified reference material using this method and distributed them to the clinical laboratories in Korea as samples for proficiency testings. The expended uncertainty was about 1.2% on 95% confidence level. In proficiency testings, the results obtained from the clinical laboratories showed about 3.6% and 3.9% RSD to the certified values. Primary method can provide the traceability to the field laboratories through proficiency testings or certified reference materials.

• Journal of the Korean Dietetic Association
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• v.10 no.2
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• pp.235-245
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• 2004

The Korea School Lunch Program mandates that school meals should safeguard the health and well-being of our children. School meals provide a nutritious diet that contains at least ⅓ of the daily Recommended Dietary Allowances of necessary nutrients at reasonable prices. This study was performed to assess the nutritional management of primary school meals, and to provide basic data for improvement of school meal nutritional guidelines. Three hundred and thirty six dietitians who worked at primary schools were recruited using a stratified sampling method. A survey was done by e-mail with a set of questionnaires about nutritional meal management. During school lunch planning, dietitians referred nutrition standards with priority, followed by students' food preferences and food hygiene. They considered energy as a most important nutrient during primary school lunch planning, followed by protein and calcium. Protein is usually over-served, whereas iron, vitamin A and calcium are usually under-served during primary school meal planning. For first and second grade primary students, grains, meat and vegetable side dishes seemed to be large compared to their eating capacity. Over 92% of school dietitians agreed the needs of food group standards for primary school lunch program. For making a checklist of the school lunch program, energy, protein and calcium were highly recommended, and meat.fish.egg group, vegetable.fruit group and dairy group were also highly recommended by school dietitians. Cooking method was also highly recommended. School dietitians proposed that remodeling of school kitchens and new cooking machine were the most important factors for improving school lunch system. These results suggest that food standards should be established for health-oriented nutritional management of primary school lunch programs. Nutritional checklists could include nutrient-rich foods and food groups, and items about cooking methods.

• Journal of Korean Vacuum Science & Technology
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• v.6 no.3
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• pp.109-115
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• 2002

This paper describes a CCM key comparison of low absolute-pressure standards at seven National Measurement Institutes that was carried out during the period March 1998 to September 1999 in order to determine their degrees of equivalence at pressures in the range 1 Pa to 1000 Pa. The Korea Research Institutes of Standards and Science(KRISS) participated from 10 Pa to 1000 Pa pressure range in 1999. The primary standards, which represent two principal measurement methods, included five liquid-column manometers and four static expansion systems. The transfer standard package consisted of four high-precision pressure transducers, two capacitance diaphragm gauges to provide high resolution at low pressures, and two resonant silicon gauges to provide the required calibration stability.