• Bulletin of the Korean Chemical Society
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• v.20 no.12
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• pp.1409-1412
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• 1999

The spectrophotometric determination method of scandium with eriochrome cyanine R (ECR) and the composition ratio of the complex were investigated in the presence of surfactants. A volume of 5 mL of 1.0×$10^{-3}$ M ECR and 10 mL of 2.0×$10^{-4}$ M CTMAB are necessary for the determination of 1.0×$10 ^{-7}$ ~ 3.0×$10^{-6}$ M Sc(III) at pH 6.5. The apparent molar absorption coefficient of the Sc(III)-ECR-CTMAB, ternary complex at 610 nm is 5.6×$10^5$ $mol^{-1}cm{-1}$L and its detection limit is 1.0×$10^{-7}$ M. Separation studies were conducted by the column method. The effect of pH, elution solution and the influence of rare earth elements as interferents was discussed. Their separation was carried out in 0.1 M HCl-50% methanol solution and 1.0 M HCl media. The method was applied for the determination of Sc(III) in monazite.

• Bulletin of the Korean Chemical Society
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• v.20 no.3
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• pp.352-354
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• 1999

The spectrophotometric determination of Cu(Ⅱ) with α-(2-benzimidazolyl)-α',α"-(N-5-nitro-2-pyridylhydrazone)-toluene has been investigated. The optimum conditions of pH, stability, concentration of ligand and surfactant were evaluated. This method is a simple and sensitive method for determination of Cu(Ⅱ) and offers a selective separation of Cu(Ⅱ) from sample solution containin- I ppm below amount of Ni(Ⅱ), Co(Ⅱ), Zn(Ⅱ) and Sn(Ⅱ). Copper was determined by measuring the absorbance of Cu(Ⅱ)-BINPHT complex extracted with benzene in Brij 58 surfactant at 410 nm. Beer's law is obeyed over the concentration range 0∼2.5 μgmL-1 and the detection limit (S/N=2) is 0.06 μgmL-1. The relative standard deviation at the 0.3 μgmL-1 is 2.4% (N=7). The method was applied for the determination of Cu(Ⅱ) in various milks.

• Journal for History of Mathematics
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• v.22 no.3
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• pp.255-272
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• 2009

R. L. Moore's discovery methods are known to have been very effective with certain classes of students. However when the method was attempted by others at the undergraduate level, the results sometimes were disappointing. In this article we study the history of developing modified Moore methods with small group discovery method for the purpose of undergraduate education, and then we discuss some educational point of view in our universities.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.1
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• pp.64-69
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• 2009

Musty and earth odors caused by geosmin and 2-MIB are the major complaints from the drinking water consumers. Therefore, early detection of geosmin and 2-MIB is the key to prevent off-flavor occurrence. In this study, a rapid method using stir bar sorptive extraction (SBSE) in combination with the GC/MS was investigated to analyze geosmin and 2-MIB in water. The SBSE method, a solventless extraction technique, was optimized and then applied to the analysis of geosmin and 2-MIB in water. The SBSE technique was found to be a simple and fast procedure that allows many samples to be extracted simultaneously using very small volume (10~20 mL). In addition, the SBSE method offered high recovery and good linear regression coefficient for the geosmin and 2-MIB. The good repeatability of this method can be deduced from the low RSD (7.2~7.6%) at 10 ng/L for geosmin and 2-MIB. The limit of detection was determined 1~2 ng/L and the limit of quantitation was 3~6 ng/L. Above all, the SBSE method proved to be a very practical technique for the analysis of geosmin and 2-MIB in water.

• Journal of the Korean Society of Food Culture
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• v.27 no.6
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• pp.686-694
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• 2012

This study was conducted to develop a method to change the color of traditional Dongchimi using natural dyes to meet changing consumer demands. It was intended to improve the manufacturing process ability for color Dongchimi, and the best optimum extraction solvent and method from the natural dyes were proven to be confirmed and valid. The extraction process was evaluated using different solvents including distilled water, 20% ethyl alcohol, and 1% citric acid, and the quantity of the extracted anthocyanin was then measured based on the absorbance. The greatest absorbance was observed when 1% citric acid was used. Based on these findings, it would be most efficient to allow the traditional Dongchimi to produce citric acid naturally instead of using artificial additives during its production. Celosia cristata L. was extracted in its largest quantity when reacted with 20% ethyl alcohol. Therefore, instead of applying Celosia cristata L. to Dongchimi as the sub-ingredient during the preparatory stage, it will be more efficient to use Celosia cristata L. as the fractional ingredient in order to first extraction.

• Nutrition Research and Practice
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• v.18 no.2
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• pp.223-238
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• 2024

BACKGROUND/OBJECTIVES: The purpose of this study was to establish a fruit-cooking method suitable for older adults with masticatory dysfunction. MATERIALS/METHODS: Five types of fruits were selected to make fruit jelly and puree: apple, sweet persimmon, mandarin, Korean melon, and watermelon. Recipes were selected based on the Korean Industrial Standard (KS) for senior-friendly foods (KS H 4897), which classifies foods into 3 levels (L1-L3) based on their hardness and viscosity. RESULTS: In South Korea, senior-friendly foods are classified into 3 stages based on their hardness. Stage 1 is for foods that are able to eat with teeth (hardness greater than 50,000 N and less than 500,000 N), Stage 2 is for foods that are able to eat with gums (hardness greater than 20,000 N and less than 50,000 N), and Stage 3 is for foods that are able to eat with the tongue (hardness less than 20,000 N). As a result of measuring the hardness by varying the shape of the fruit, it was found that nearly all fruits could be eaten fresh by chewing with the teeth (L1) but did not meet the KS for mastication using the gums (L2) or tongue (L3), so the cooking method was selected as fruit jelly and fruit puree. Only sweet persimmon, which had a hardness of 61,624-496,393 N, was not suitable for consumption in fresh fruit, unprocessed form. Based on their hardness measurements, fruit jellies (27,869 to 36,343 N) and fruit purees (315 to 1,156 N) met the L2 and L3 requirements, respectively. The viscosity results of all fruit purees met the L3 requirement. CONCLUSION: These results offer a simple cooking method to prepare texture-modified fruits suitable for safe consumption by older adults living with masticatory difficulties in general households and nursing facilities.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.5
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• pp.497-504
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• 2013

This research uses numerical analysis to examine the tunnel portal landscape affecting the brightness level of interior lighting when designing lights for road tunnels through the L20 method. In order to extract the brightness recognition per form of a tunnel entrance and to evaluate the effects of the characteristics of the materials of facilities near a tunnel portal, brightness analysis was conducted by filming brightness on a video photometer called Hi-land Elf System, and a surface brightness photometer called LMK Mobile Advanced. Tunnels in Korea are mostly distributed in mountain areas; thus, the ratio occupied by the sky, which has the highest brightness within the angle of L20, is close to zero, while most of the ratio was occupied by brightness by the area near the tunnel entrance or road surface. However, for a tunnel portal retaing wall, which allows the width of a tunnel entrance to seem wider within the L20 angle, appeared to be have higher brightness compared to nearby areas or the surface, which is an element increasing the tunnel portal brightness within the tunnel, and the road facilities near the tunnel portal appeared to have an effect on the brightness as well. Thus, when designing tunnel lights based on brightness, the form of the tunnel entrance and the area width, material, and color of areas near the tunnel portal appeared to affect outside brightness and become an element affecting the establishment of the brightness level of the interior lights of tunnels. Consequently, reviewing such matters is a prerequisite when designing tunnel portal landscape.

• ALGAE
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• v.20 no.2
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• pp.151-155
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• 2005

To obtain basic data, we investigated the effect of blade length on transplants, the transplanting method of Laminaria japonica for creating L. japonica resources and the number of transplanting plates with surviving L. japonica. The survival rate of L. japonica, blade length of transplants and drag force of transplanting plates were also researched. The number of transplanting plates with surviving L. japonica, the survival rate and blade length of 20 cm long-initial transplants were greater than those of 1.5, 5 and 10 cm long-initial transplants in an outdoor aquarium. At the depth of 4 m in the coastal waters, the number of transplanting plates with surviving transplants, the survival rate and the blade length of 30 cm long-initial transplants were higher than those of 10 and 20 cm longinitial transplants. The drag force is calculated by cording up sporophytes of L. japonica into the transplanting plates under water. The drag force in the case of a 2.18 kg-weight transplanting plate and in a current speed of 0.5 m${\cdot}s^{-1}$ for considering stability of the plate was 631.50 g to a concrete substratum on the seabed, 703.92 g to a shingle substratum, 788.00 g to a sand substratum, and 1018.30 g to a silt substratum. If we consider the stability and economic efficiency of the transplanting plate, the proper weight of the plate per one individual of 18.11 cm in blade width and 190.20 cm in total blade length is regarded as 508.2 g when it is calculated with the concrete substratum that shows the lowest drag force.

• Korean Journal of Environmental Biology
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• v.23 no.4
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• pp.374-378
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• 2005

A diffusion - precipitation method was developed to determine acid volatile sulfide (AVS) concentrations in freshwater sediments. This method uses silver nitrate as a sulfide trap solution and the concentration of trapped sulfide is determined gravimetrically. The proposed diffusion - precipitation method is more rapid and less expensive than previously developed purge- and - trap methods. Spiked sodium sulfide recoveries using this method $(97\~120\%)$ were similar with a previously developed diffusion - absorption method $(93.8\~115\%)$ and about $20\%$ greater than a previously developed purge-and-trap method $(74.6\~105\%)$. Detection limit of this method $(0.1\;{\mu}mole\;S\;g^{-l})$ was comparable with that of diffusion-absorption method $(0.06\;{\mu}mole\;S\;g^{-l})$ and purge-and-trap method $(0.05\~0.5\;{\mu}mole\;S\;g^{-l})$.

• Journal of Food Hygiene and Safety
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• v.32 no.5
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• pp.343-347
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• 2017

The analytical method of silicon dioxide ($SiO_2$) in health functional food products was developed employing inductively coupled plasma optical emission spectrometry (ICP-OES) method assisted by acid (hydrofluoric acid and boric acid) digestion in open system without alkali fusion. The limit of detection (LOD) and limit of quantification (LOQ) of this method were found to be 0.07 and 0.20 mg/L, respectively. Linearity ($r^2$) and linear range were 0.99 and 0.20~20.0 mg/L, respectively. The accuracy and precision of $SiO_2$ (0.4, 1.0, and 2.0%, w/w) in spiked glucosamine exhibited to be the range of 90.22~94.14% and 0.72~1.67%, respectively. The contents of $SiO_2$ in 11 health functional food products were detected in range of 0.02~1.80% (w/w). Every sample showed below content of the permitted use level (2%, w/w) of $SiO_2$. Therefore ICP-OES method with acid can analyze the content of $SiO_2$ in health functional food products easily and rapidly. Consequently, the application of specification analysis of $SiO_2$ in health functional food products could be a significant work.