• Korean Journal of Food Science and Technology
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• v.38 no.1
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• pp.59-67
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• 2006

Effects of ${\alpha}-amylases$ and emulsifiers on characteristics of frozen bread dough were examined during 12 weeks of storage. Fungal or bacterial ${\alpha}-amylase$ and various emulsifiers, including monoglyceride (MG), sodium stearoyl-2-lactylate (SSL), and diacetyltartaric acid ester of mono- and diglycerides (DATEM), were added to frozen dough individually and as mixtures Height of frozen dough at maximum development time, total volume of $CO_2$ gas, and retention volume increased with increasing content of emulsifiers. indicating addition of enzymes and emulsifiers had significant effect on flexibility of starch-gluten complex in dough. Frozen dough made with bacterial ${\alpha}-amylase$ showed slightly higher pH during storage than that of frozen dough with fungal ${\alpha}-amylase$. Bread made from frozen dough prepared with both enzymes and emulsifiers showed lower specific loaf volume than that of control during storage, whereas highest specific loaf volume was obtained with addition of fungal ${\alpha}-amylase$ with SSL+MG and bacterial ${\alpha}-amylase$ with MG.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3336-3344
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• 2014

The purpose of this study is small scale coagulation module is developed and demonstrated through a lab-scale test. Recent as a sewage treatment rate increases, have heightened the interest in the necessity on the nonpoint source and developing a small processing unit has been increased. Coagulation sedimentation module in this study is additional growth of floc through swirling in the outside zone, reduction of microstructure floc number and the internal settling zone through vertical/level flow complex sedimentation method after the coagulation process precipitation method as an effective high separation efficiency can be divided was also assessed. Coagulation sedimentation module can increase the load factor was 4.4 times compared to conventional clarifier base on the same volume and surface area through vertical/level flow. In this study, this process was selected formation and maintenance of swirling and uniform flow distribution in the internal settling zone as an important design factor, to derive its FLUENT was used to characteristics of the flow model. Through the simulation of swirling, influent velocity, dimensions of external basin, hopper depth of bottom cone was determined and through analysis of velocity distribution, flow distribution detailed specifications are derived like as diameter and number of effluent hole. Lab-scale($120{\ell}/hr$) test results, influent of 300~800 NTU to less than 10 NTU without polymer feeding was able to operate in the 20minutes retention time(surface loading rate $37.3m^3/m^2$-day), and through analysis FLUENT the possibility of using design parameters were derived.

• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.1076-1084
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• 2017

For analyzing the qualitative and quantitative analysis of fuel marker in petroleum products, the applicability of HPLC was studied. For the qualitative analysis of fuel marker in kerosene and automotive diesel, optimal analytical conditions(ratio of mobile phase solvent, flow rate, etc) in HPLC were selected and calibration curve for quantitative analysis of fuel marker was prepared based on the result of qualitative analysis. In particular, the correlation coefficient of calibration curve in kerosene and automotive diesel was shown to be 0.999 in a certain concentration range and it could be applied to the quantitative analysis. The results of analysis using the UV/Vis spectrometer, which is the current analysis method of fuel marker, were compared with the analysis results using the HPLC. The kerosene showed a low deviation of about 7 % and the automotive diesel showed a somewhat large deviation of about 20 %.

• Ecology and Resilient Infrastructure
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• v.8 no.4
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• pp.281-289
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• 2021

Commercially used disposable cups undergo fragmentation in the environment and become microplastics (MPs). These MPs can be ingested by aquatic organisms and cause a range of adverse effects. We assessed the acute and chronic toxicity of disposable cup-derived MP fragments in Daphnia magna. MP fragments were identified as a polyethylene terephthalate (PET) fragment with a size of 33.18 ± 7.76 ㎛. The presence of three additives including 1- Propanone. 1-phenyl-3-[2-(phenylmethoxy)phenyl]-, p-Xylene and ethylbenzene was analyzed from MP fragments. The 48 h acute toxicity revealed that 20 % of immobilization and mortality were found at the highest concentration of PET MP (200 mg L^-1). The 21 d chronic toxicity revealed that PET MP fragments significantly (p < 0.05) more reduced survival rate (31 %), total offspring (52 %) in D. magna compared with control group. The developmental abnormality of offspring (3.5%) by PET MP fragments was significantly (p < 0.05) higher than control groups (0.3%). These results are possibly induced by gut blocking by ingestion of MP fragments and their longer retention time. These findings indicate that the fragmentation of disposable cups (PET polymers) into small-sized MP fragments pose a significant ecological risk to aquatic organisms. Further studies are required to elucidate the underlying toxicity mechanisms.

• Journal of vocational education research
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• v.37 no.2
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• pp.77-99
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• 2018

The purpose of this study was to investigate the employment possibility of the humanities college graduates to science and engineering field occupations, and to identify the occupational characteristics related to employability perceived by workers. To do this, basic statistical analysis, correlation analysis, and hierarchical multiple regression analysis were conducted using the data surveyed on 2,600 workers in the science and engineering field in the 'Research on Korean Occupational Index for Career and Employment Service(2017)'. The main results are as follows. First, the employment possibility of the humanities college graduates to science and engineering field was low, except for some occupations in the information communication, manufacturing and processing fields. Second, the occupational characteristics affecting the employment possibilities of the humanities college graduates to science and engineering field are as follows: low importance of the final education, low importance of the major, low importance of qualification, high importance of vocational training, easy to return after the career break, high level of gender equality, high level of pleasant work environment, high employment retention, easy to self-employment or start-up, and increasing number of jobs. Based on the results of this study, to support employment of humanities college graduate from the occupational aspect, it is necessary to find out some detailed jobs or to develop convergence occupations. At this time, it is possible to utilize the occupational characteristics factors that increase the employment possibility of humanities college graduates to science and engineering occupations.

• Food Engineering Progress
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• v.15 no.3
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• pp.209-213
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• 2011

Changes of rancidity of soybean powder from Yeonhaeju (Bazaz) during storage were evaluated by TBA, and compared with those of Korean soybean (Baektae). Lipoxygenase (LOX) in the soybean powder was inactivated by high pressure processing (HPP) to increase the stability of soybean powder during storage. The level of inactivation of LOX was measured by spectrophotometer at 234 nm. HPP decreased the activity of LOX in the soybean powder of Baektae, compared to that of the control (i.e., soybean powder without HPP treatment) of Baektae, while TBA values of both HPP treated Baektae and the control were increased up to 24 days of storage. However, in case of Bazas, both LOX activity TBA values decreased after HPP treatment, compared to those of controls. The antioxidant compounds in both soybeans were measured and quantitatively evaluated by on-line $ABTS^{+}$ assay. Based on the trolox equivalent (TE) value at the retention time 38.2 and 40.1 min, the antioxidant components in Bazaz were higher than that of Baektae. It might indicate that relatively lower TBA values of HPP treated Bazaz was due to lower LOX activity as well as higher antioxidant compounds in the species.

• The Korean Journal of Archival Studies
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• no.18
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• pp.281-315
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• 2008

This paper reviews recent records issues surrounding former president Roh Moo-Hyun's private possession of the copies of the presidential records in Korea. While the former president transferred his records to the National Archives of Korea, he copied his electronic presidential records and kept them in his house after the term. His retention of the "records copies" arouse critical records issues and criminal charges. In this paper, I examined the definition of presidential records and legal status of records copies, authenticity of electronic copies of public records in public and private records systems, nature and scope of presidential privilege of access to his records, and most importantly, political neutrality of national archives. I examined these issues comparing with foreign experience, especially that of the United States which has the Presidential Records Act like Korea. All issues are examined in the professional spirit of archives principles and archives ethics. Legal status of the electronic copies of presidential records is not firmly established and the criminal charge seems groundless. However, it is against public archives principles and ethics that private former president privately possesses and manages private information and national security information held in the electronic copies of the presidential records. Presidential Records Act of Korea provides an effective tool to protect the presidential records for 15 years and it should be respected. It is time to consolidate the public records management institutions in Korea, not to disintegrate them.

• Journal of Food Hygiene and Safety
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• v.34 no.1
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• pp.52-57
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• 2019

Method development and validation of decursin for the standardization of Angelica gigas Nakai as a functional ingredient and health food were accomplished. The quantitative determination method of decursin as a marker compound of aerial parts of Angelica gigas Nakai extract (AAGE) was optimized by HPLC analysis using a C18 column ($3{\times}150mm$, $3{\mu}m$) with 0.1% TFA in water and acetonitrile as the mobile phase at a flow rate of 0.5 mL/min and detection wavelength of 330 nm. The HPLC/PDA method was applied successfully to quantification of the marker compound in AAGE after validation of the method with linearity, accuracy, and precision. The method showed high linearity in the calibration curve at a coefficient of correlation ($R^2$) of 0.9994 and the limit of detection and limit of quantitation were $0.011{\mu}g/mL$ and $0.033{\mu}g/mL$, respectively. Relative standard deviation (RSD) values of data from intra- and inter-day precision were less than 1.10% and 1.13%, respectively. Recovery of decursin at 0.5, 1, 5 and $10{\mu}g/mL$ were 92.38 ~ 104.11%. These results suggest that the developed HPLC method is very useful for the determination of marker compound in AAGE to develop a health functional material.

• Journal of the Korean Society of Mineral and Energy Resources Engineers
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• v.55 no.6
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• pp.527-537
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• 2018

Column tests of a sulfate reducing bacteria (SRB) bioreactor were conducted to determine the design factors for sulfate-rich mine drainage. Various substrates were applied to the bioreactor, including cow manure and its mixture with a mushroom compost, with rice straw and limestone as subsidiary materials. This procedure provided a removal efficiency of up to 82% of the total sulfur with the mixture of cow manure (70%), mushroom compost (10%) and rice straw (20%), and higher efficiencies were observed after 2 days of retention time. In the downflow condition of the flow direction, oxygen supply and re-oxidation of the sulfates occurred, causing a decrease in sulfate removal efficiency. The addition of an inorganic sludge containing heavy metals, which was intended for production of metal-sulfides in the bioreactor, had a negative effect on the long-term operation owing to arsenic release and toxicity to the SRB. The results thus show that a bioreactor using a mixed substrate with cow manure and operating in the downflow direction could reduce sulfates and total dissolved sulfur content; this process confirms the applicability of the SRB bioreactor to sulfate-rich saline drainage.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.1
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• pp.12-18
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• 2019

The spherical $SiO_2$ powders were synthesized by the scaled-up ultrasonic pyrolysis (USP). The aqueous $SiO_2$ sol, which contained 20~30 nm $SiO_2$ particles, was used as a precursor for the scaled-up USP. The effects of the USP operating conditions and precursor conditions were systematically investigated, including reaction temperature, gas flow rate, and the concentration of $SiO_2$ sol on the morphologies of synthesized $SiO_2$ particles. the synthesized $SiO_2$ particle showed a pseudo-crystal phase, spherical morphology, and a smooth surface. The size of the spherical $SiO_2$ particle decreased as both reaction temperature increased and precursor concentration decreased. In addition, the synthesized $SiO_2$ particle size was increased by increasing the gas flow rate. Lastly, the scaled-up USP was compared with the lab-scale USP based on the same process conditions. Due to a short retention time in the reaction tube during the USP process, the $SiO_2$ particle synthesized via the lab-scale USP showed a larger particle size.