• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.849-859
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• 2000

This study was conducted to identify the characteristics of methane fermentation and lysis effects of pre-treated microalgae. Chemical compositions of microalgae showed that the VS(volatile solid) was 86.1% of TS(total solid), and the protein was 63.5% of VS. These values were higher than those of activated sludge. The cell lysis test of raw microalgae biomass was conducted by many physicochemical methods. presenting that the degree of cell lysis was affected by following order: ultrasonic(100min.), alkali(pH 13), ultrasonic(10min), thermal($120^{\circ}C$), thermal($50^{\circ}C$), and acidic(pH 3) treatment. Methane fermentation with many pre-treated samples was performed, showing that the concentration of acetic acid was the highest. followed by propionic acid, butylic acid and valerie acid among all VFA(volatile fattic acid). In methane production. ultrasonic samples were only more effective than untreated one in total gas and methane productivity. but other samples were less effective. Especially. the alkalic sample had an inhibitation effect on methanogens.

• The korean journal of orthodontics
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• v.31 no.5 s.88
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• pp.535-548
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• 2001

The purpose of this study was to evaluate changes in soft tissue chin thickness and to investigate correlations between hard and soft tissues measurements after orthodontic treatment conducted by premolars extraction and incisor retraction. The sample consisted of 35 female adults with Angle classification class I or class II division 1 malocclusion. Using lateral cephalometric radiographs taken before and after treatment, hard and soft tissue structures were measured and reproducible six landmark on soft chin tissue were used to locate the various points of soft tissue contour of the chin. The res에ts were as follows : 1. There were signigicant correlations between pretreatment B-B', Pm-Pm' and pretreatment vortical skeletal measurements such as $MP{\perp}HP,\;MP{\perp}PP$, ALFH and between a-a', b-b', Me-Me' and measurements of sym-physeal morphology such as SL, SW, PL. 2. There were significant decreases at B-B', Pm-Pm' and significant increases at a-a', b-b' between pre-and posttreatment mea surements. 3. There were significant correlations among soft tissues changes and hard tissue changes except for changes at B-B' and the range of correlation coefficient was about 0.3-0.4. 4. There were significant differences at ${\Delta}UI-VP,\;LI{\perp}, and B-B' measurements between subgroups divided by posttreatment Pog-Pog' changes. 5. There were significant differences at ${\Delta}overbite,\;NPog{\perp}HP,\;and\;Me-Me'$ measurements between subgroups divided by posttreatment Me-Me' changes.

• Journal of the Korean Society of Food Culture
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• v.17 no.1
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• pp.70-77
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• 2002

Jangachi(salted and fermented vegetable) has been made by Korean traditionally using several kinds of vegetables, which is a good source of variety of nutrients and vitamins. There are many methods for making Jangachi. Generally soy sauce Jangachi is made through two steps. First, as a pretreatment, vegetables are soaked in salt water. Second, soaked vegetables are fermented in various ingredients like soy sauce, sugar, garlic, ginger and so on. This study was performed to observe changes in contents of chemical components and sensory evaluation of pretreated perilla leaf. Perilla leaf was soaked in water with different levels of salt concentration(2, 5 and 8 %) and soaking time(1, 3 and 5 days). The optimal level of salt and soaking time was determined with the results of sensory evaluation by response surface methodology and analysis of composition. The moisture contents decreased as the levels of salt and soaking time increased. The moisture content of untreated sample was 87.5 % and when soaked for 5 days in the water of 8 % salt concentration, it became 78.27 %. pH of Perilla leaf was high in high levels of salt concentration and short soaking time. Total acidity was so opposite to pH that was low in high levels of salt concentration and short soaking time. In the water of 8 % salt concentration, total acidity was 0.14 % when soaked for 1 day, 0.20 % for 3 days and 0.30 % for 5 days. Salt contents became greater as the soaking time increased. As the results of puncture test, soaked Perilla leaf's toughness increased as the levels of salt increased and soaking time decreased. Among the sensory attributes, greenness increased as the levels of salt concentration increased when soaked for more than 3 days. Saltiness and bitterness became greater as the levels of salt concentration increased. Perilla flavor decreased with the short soaking time. Off-flavor increased with the increased levels of soaking time and decreased salt concentration when soaked for more than 3 days. Toughness decreased as the levels of soaking time increased. Crispness increased with the increased levels of salt concentration. The condition of pretreated Perilla was optimum when it soaked for 42 hours in 4 % salt concentration.

• Analytical Science and Technology
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• v.16 no.5
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• pp.399-406
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• 2003

This study was conducted to find out the analysis condition of selenium(Se) in oil refinery wastewater with a high concentration of Se using the atomic absorption spectrometry with hydride generation system (HG-AAS). From various experiments that reduced Se(VI) to Se(IV), the optimum pretreatment condition was determined to be a sample volume of 10 mL, HCl 10 mL, with a 30 min heating time in a water bath. In oil refinery wastewater, as the concentration of organics and constitution became higher, the recovery rates of Se decreased. Therefore, three acid digestion methods ($HNO_3/HClO_4$ digestion, $KMnO_4$ digestion, and microwave acid digestion) were tested on the recovery rates of Se in reference to the digestion of organics, petroleum and oxidation from organic Se(org.), Se(IV) to Se(VI). The experiment results showed that the average recovery rate of Se was the highest in microwave acid digestion, although all of the digestions were more than 90%. In consequence, the pretreatment procedure of microwave digestion followed by HCl addition was the most suitable for selenium analysis in oil refinery wastewater by using HG-AAS.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.9
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• pp.1279-1283
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• 2009

In order to investigate the potential characteristics of horseweed (Erigeron canadensis L.) recognized with weeds for the application to food industry, the antioxidative properties of horseweed were measured with total polyphenol, flavonoid, tannin, chlorophyll contests and antioxidant activities. Total polyphenol, flavonoid, tannin, and chlorophyll content were 63.32, 27.71, 161.19, and 428.85 mg/g in the extracts of fresh horseweed (FHE), respectively. The extracts of dry horseweed (DHE) on $40^{\circ}C$ for 48 hr were 89.25, 33.44, 210.44, and 229.29 mg/g, and the extracts of dry horseweed after blanching (BDHE) were 115.49, 45.51, 252.54, and 283.07 mg/g, respectively. $IC_{50}$ of EDA (electron donating ability, %) and AEAC (L-ascorbic acid equivalent antioxidant capacity) were 5.5527 mg/mL and 192.78 mg AA eq/g sample in the FHE, respectively. The DHE were 0.4710 mg/mL and 194.05 mg AA eq/g sample, and the BDHE were 0.4135 mg/mL and 242.40 mg AA eq/g sample, respectively. Horseweed, where the antioxidant activity is excellent, is thought to be potentially useful with foodstuffs.

• Journal of the Korean Chemical Society
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• v.39 no.7
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• pp.513-523
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• 1995

Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) are the most concerned toxic organic pollutants to human. Because of their extremely high toxicity and uncertain genotoxic potential, their determination in environmental and biological samples is of great interest. Municipal solid waste incinerator facilities have been reported as the major contributors of dioxins and furans to the environment, and their formation from combustion is a universal phenomenon, everywhere. In this study dioxins and furans were analyzed from the bottom ash produced during combustion in an municipal waste incinerator located in Seoul. The EPA method was modified for sample pretreatment: the soxhlet method was used for extraction and clean-up procedures were performed by using silica and basic alumina, excluding active-carbon. The extract was then analyzed by HRGC/HRMS. A general trend of increase in the amounts of 6∼7 chlorine-substituted dioxins and furans was observed. Total dioxins, furans and 2,3,7,8-TCDD were determined as 8.05 ng/g, 4.75 ng/g, and 6.93 pg/g, respectively.

• Fire Science and Engineering
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• v.33 no.6
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• pp.80-86
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• 2019

In Korea, a total of 556 chemical accidents occurred from 2012 to 2018 caused by adverse reactions of two or more chemicals, which required significant amounts of time to identify the causative chemicals. Rapid analysis is required for effective incident response and probing. In this study, a quantum transition time-of-flight mass spectrometer was used to identify the causative agents of chemical accidents caused by adverse reactions. The analyzer enabled fast real-time analysis without the need for sample collection and pretreatment. Quantitative and qualitative analysis of most volatile organic compounds with high hydrogen affinity was performed to investigate the cause of the chemical accidents. In fact, in the month of 201◯, methanol and toluene were detected as causative agents of the accident using a quantum transition time mass spectrometer, and were also the cause of the reported odor.

• Journal of the Korean Chemical Society
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• v.38 no.11
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• pp.819-826
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• 1994

This study described a simple, rapid and cost effective analytical technique for the ultra-trace analysis of dioxins in environmental samples. Liquid-Liquid extraction methods were used for the initial extraction and enrichment of the analyte. Subsequent clean-up procedures were achieved by using strong cation exchanger, silica and Florisil cartridges. Extracts were analysed by HRGC/HRMS-SIM. The efficiency of these analytical methods was tested by recovery and selectivity for elimination of interferences such as phenols, pesticides and PCBs in each step. The mean recovery of 1,2,3,4-TCDD spiked at 10 ppt in sea water was about 92(${\pm}$1.6)%. This analytical method was applied to Kwangyang sea water and 4.5pg/L of 2,3,7,8-TCDD was determined.

• Analytical Science and Technology
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• v.33 no.3
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• pp.125-133
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• 2020

Methylisothiazolinone (MIT) and chloromethylisothiazolinone (CMIT) cause allergic contact dermatitis and are banned cosmetics ingredients, except in rinse-off products. However, their presence has been detected in cosmetics. We report a UPLC-tandem MS/MS screening method for their simultaneous determination in cosmetics. To facilitate extraction from various matrices, pretreatment methods were developed for each sample type. The method was optimized through a series of assessments, including specificity, LOD, LOQ, linearity, recovery, stability, precision, and accuracy. The LODs and LOQs for MIT ranged from 0.054 and 0.163 ㎍ mL^-1 whereas those for CMIT ranged from 0.040 and 0.119 ㎍ mL^-1. The linear correlation coefficients (r²) were higher than 0.999. Relative standard deviations (RSDs) for both intra- and inter-day measurements ranged from 0.3 ~ 13.6 %. Recoveries at three different concentrations were within 87.9 ~ 118.9 %. The RSD for stability measurements of spiked samples was within 7 %. These results confirm the suitability of the developed method for the simultaneous quantitation of MIT and CMIT in cosmetics. Samples of 320 color cosmetics, including eyeshadows, solid lipsticks, liquid lipsticks, and nail polishes were analyzed using the developed method, and two of them were found to contain both MIT and CMIT and one of them was found to contain only MIT. This data and the method will aid the regulation of ingredients used in cosmetics.

• The korean journal of orthodontics
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• v.13 no.2
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• pp.177-183
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• 1983

The soft tissue covering of the face plays an important role in facial esthetics, speech and other physiologic functions. Thus, it is recognised by all clinical orthodontists that success of orthodontic treatment is closely related to the changes in soft tissues of the face. The purpose of this study was to evaluate the changes of bony and soft tissues in prepost treatment of Angle's Class III malocclusion. The sample consisted of 18 males and 37 females, pretreatment age of 9 years to 11 years. For this study 11 landmarks were plotted, 14 linear length, 4 soft tissue thickness and 2 angles were measured. The obtained results were as follows; 1. In the linear measurements of bony and soft tissue changes, A, Is, Ss, Ls and Li were located more anteriorly in both sexes. However Si and B showed more remarkable anterior movement in female. 2. In the comparison of the changes of the soft tissue thickness, Ss and Li in male subjects and Ss in female subjects increased. 3. In the degree of correlation between changes in the soft tissue profile and changes in the skeletal profile, Is: Ls, Il: Li and B: Si in both sexes had significant correlations. However A:Ss had remarkable significant correlation in female. 4. There were significant correlations between change in ${\angle}A$ and change in ${\angle}B$ in all sexes. 5. There were little correlation between changes in distance difference of Is and Ii and Change in distance difference of Ls and Li in all sexes.