• Journal of Korean Society of Environmental Engineers
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• v.33 no.10
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• pp.774-781
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• 2011

Nitric acid and hydrofluoric acid are used for acid pickling in zirconium alloy tubing manufacturing process. Nitrate and fluoride in the wastewater were treated by chemical coagulation and SOD (Sulfur Oxidation Denitrification) process. This study is investigated the effect of fluoride concentration and the optimal condition for SOD process. The limited fluoride concentration for SOD process was below 20 mg F-/L. The adjusted pH and alkalinity by NaOH and $NaHCO_3$ was shown to be more effective for removal of nitrate compared with using NaOH. Furthermore, the microbial activator mixed trace elements and ingredient for alkalinity did not only supplement with alkalinity but also enhance the growth and proliferation for sulfur-oxidizing bacteria. As a result, the inorganic industrial wastewater was successfully treated by the microbial activator in SOD process without continuous addition of seed sludge. Finally, SOD process was shown to remove nitrate in industrial wastewater and to contribute the microbial activator for activation of sulfur-oxidizing bacteria.

• Journal of Welding and Joining
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• v.34 no.2
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• pp.1-10
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• 2016

The use of materials for modern lightweight auto-bodies is becoming more complex than hitherto assemblies. The high strength materials nowadays frequently used for more specific fields such as the front and rear sub frames, seat belts and seats are mounted to the assembled body structure using bolt joints. It is desirable to use nuts attached to the assembled sheets by projection welding to decrease the number of loose parts which improves the quality. In this study, nut projection welding was carried out between a nut of both boron steel and carbon steel and ultra-high strength hot-stamped steel sheets. Then, the joints were characterized by optical and scanning electron microscope. The mechanical properties of the joints were evaluated by microhardness measurements and pullout tests. An indigenously designed sample fixture set-up was used for the pull-out tests to induce a tensile load in the weld. The fractography analysis revealed the dominant interfacial fracture between boron steel nut weld which is related to the shrinkage cavity and small size fusion zone. A non-interfacial fracture was observed in carbon steel nut weld, the lower hardness of HAZ caused the initiation of failure and allowed the pull-out failure which have higher in tensile strengths and superior weldability. Hence, the fracture load and failure mode characteristics can be considered as an indication of the weldability of materials in nut projection welding.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.6
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• pp.743-749
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• 2016

We compared two different processing methods for preparing high quality frozen in-shell baby clam products. In the first method, sand and mud were removed from the clams, then they were vacuum packed in polyethylene film, boiled at $97^{\circ}C$ for 6 min, and snap frozen in a cold air blast freezer (sample 1). The second processing method was similar, except the boiling process was excluded (sample 2). Both frozen products were boiled for 4 min, and then shucked and minced. Various quality metrics, such as the opening rates of shells, chemical composition, pH, volatile basic nitrogen (VBN), salinity, thiobarbituric acid (TBA), amino-N, total amino acids and free amino acids were measured, and sensory evaluation was conducted. The opening rates of shells of sample 1 and sample 2 were 98.3% and 4.67%, respectively. The proximate composition of sample 1 and sample 2 was 75.2% and 78.7% moisture, 19.7% and 16.2% crude protein, 2.45 and 2.2% crude lipid, 2.8% and 2.1% ash, and 2.1% and 1.9% salinity, respectively. The L, a, b and ${\Delta}E$ values were similar: 48.6 and 49.2, 3.9 and 3.9, 15.7 and 15.5, and 50.7 and 50.1 for sample 1 and sample 2, respectively. The sensory evaluation score of sample 1 was higher than that of sample 2. Sample 1 was deemed to be superior to sample 2; therefore, we determined that the boiling process is needed for manufacturing high-quality frozen clam products.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.28 no.1
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• pp.108-116
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• 2018

Objectives: This study investigated to the analytical work environment, analyst's expert and status of analytical instrument in the designated organization's laboratory for measuring work environment, and carried out to ensure reliability of analytical results. Methods: This study was conducted by 114 analysts who work in designated organization's laboratory for measuring work environment. Information on the working environment and personal characteristics of the analysts were collected using a self-reported questionnaire and were analyzed using the SPSS program through analysis of frequency and t-test. Results: The speciality of subjects was occupational health(57.0%), environmental health(38.6%) and environmental engineering(4.4%), and they had a higher level of academic ability than workers in other industries. Analysts had to handle a large number of sample analysis and many tasks other than analytical work. The analysts answered that it was difficult to analyze organic substances than inorganic substances, and the difficult parts were the analytical methods setting of new substances(55.3%), instrument analysis(24.6%) and principle of analysis(23.7%). Analytical instruments mainly have legally required instruments. The difficulty of the analysis is solved from the senior analyst in the laboratory and analytical information is mainly exchanged through seminar organized by the Association of Occupational Health Analysts. The analysts who are planning to move or considering the company were 48.2%, and the reasons for moving the company were difficult to work(14.0%), low salary(9.6%), employment type(8.8%) and job stress(7.0%). Conclusions: The conclusions of our study were that it was possible to secure reliability by solving the problems such as implementing professional education to improve expertise of analysts, strengthening analytical instruments through institutional improvement and improving work environment.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.27 no.3
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• pp.193-201
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• 2021

Patents for postharvest technology of fresh fruits, vegetables and mushrooms fluctuated in their filing number until the 2000s, but then there has been a steady increase in the 2010s, indicating that the technology has high growth potential in the international agricultural market. Using 551 valid patents for fresh fruits and 337 for fresh vegetables of 5 countries, patent trend of postharvest technology was analyzed in this study with two categorized technologies as packaging and storage. In Korea, patents from national research institutes such as the Korea Food Research Institute and Korea (Rural Development Administration) are dominated, and a number of patents for the postharvest storage of fresh vegetables by Mitsui Chemicals, a Japanese chemical company, have been registered. Agrofresh, a multinational company in the USA, holds a number of patents for postharvest storage of fresh fruit not only in its own country, but also in Japan and Europe. Postharvest technology of fresh fruits and vegetables was found to has a number of patents, mainly from national research institutes and multinational corporations, and this suggests that R&D and commercialization of the technologies are actively taking place.

• Clean Technology
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• v.28 no.2
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• pp.193-200
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• 2022

The term environmental, social and governance (ESG) was first used in the 2003 United Nations Environmental Programme Finance Initiative (UNEP FI). Among the three areas of ESG, environment refers to the impact of companies on the environment. Environmental factors address climate change policies and attempts to reduce emissions, waste and natural resource consumption. Social factors refer to the direction in which a company can improve the social impact of stakeholder includes employees, customers, communities, and governments involved in direct or indirect interaction with the organization itself and the company. Governance factors refer to stakeholders who make major decisions, the composition of the board of directors, their diversity and independence, and the internal policies that set limits and expectations for decision-making. Research related to ESG management is part of corporate social responsibility, sustainability, corporate or financial performance, and social responsibility investment. Through case studies and data-based empirical studies, it was confirmed that ESG management companies had positive results for most of the ESG related fields. Through literature analysis of domestic and international ESG history, introduction background, and management performance, this paper presents theoretical, practical implications by confirming that ESG's introduction and operation strategies are strong competitive strategies that directly affect corporate growth by creating attractive factors.

• Proceedings of the Membrane Society of Korea Conference
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• 1999.07a
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• pp.39-42
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• 1999

Perfluoropolymers represent the ultimate resistance to hostile chemical environments and high service temperature, attributed to the presence of fluorine in the polymer backbone, i.e. to the high bond energy of C-F and C-C bonds of fluorocarbons. Copolymers of Tetrafluoroethylene (TEE) and 2, 2, 4Trifluoro-5Trifluorometoxy- 1, 3Dioxole (TTD), commercially known as HYFLON AD, are amorphous perfluoropolymers with glass transition temperature (Tg)higher than room temperature, showing a thermal decomposition temperature exceeding 40$0^{\circ}C$. These polymer systems are highly soluble in fluorinated solvents, with low solution viscosities. This property allows the preparation of self-supported and composite membranes with desired membrane thickness. Symmetric and asymmetric perfluoropolymer membranes, made with HYFLON AD, have been prepared and evaluated. Porous and not porous symmetric membranes have been obtained by solvent evaporation with various processing conditions. Asymmetric membranes have been prepared by th wet phase inversion method. Measure of contact angle to distilled water have been carried out. Figure 1 compares experimental results with those of other commercial membranes. Contact angles of about 120$^{\circ}$for our amorphous perfluoropolymer membranes demonstrate that they posses a high hydrophobic character. Measure of contact angles to hexandecane have been also carried out to evaluate the organophobic character. Rsults are reported in Figure 2. The observed strong organophobicity leads to excellent fouling resistance and inertness. Porous membranes with pore size between 30 and 80 nanometers have shown no permeation to water at pressures as high as 10 bars. However high permeation to gases, such as O2, N2 and CO2, and no selectivities were observed. Considering the porous structure of the membrane, this behavior was expected. In consideration of the above properties, possible useful uses in th field of gas- liquid separations are envisaged for these membranes. A particularly promising application is in the field of membrane contactors, equipments in which membranes are used to improve mass transfer coefficients in respect to traditional extraction and absorption processes. Gas permeation properties have been evaluated for asymmetric membranes and composite symmetric ones. Experimental permselectivity values, obtained at different pressure differences, to various single gases are reported in Tab. 1, 2 and 3. Experimental data have been compared with literature data obtained with membranes made with different amorphous perfluoropolymer systems, such as copolymers of Perfluoro2, 2dimethyl dioxole (PDD) and Tetrafluorethylene, commercialized by the Du Pont Company with the trade name of Teflon AF. An interesting linear relationship between permeability and the glass transition temperature of the polymer constituting the membrane has been observed. Results are descussed in terms of polymer chain structure, which affects the presence of voids at molecular scale and their size distribution. Molecular Dyanmics studies are in progress in order to support the understanding of these results. A modified Theodoru- Suter method provided by the Amorphous Cell module of InsightII/Discover was used to determine the chain packing. A completely amorphous polymer box of about 3.5 nm was considered. Last but not least the use of amorphous perfluoropolymer membranes appears to be ideal when separation processes have to be performed in hostile environments, i.e. high temperatures and aggressive non-aqueous media, such as chemicals and solvents. In these cases Hyflon AD membranes can exploit the outstanding resistance of perfluoropolymers.

• Journal of the Korean Institute of Gas
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• v.16 no.6
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• pp.80-86
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• 2012

From 1982, the Korean Ministry of Employment and Labor has executed the risk assessment regulation for manufacturing industries. When a manufacturing company install, transfer, or modify the major facilities, the program inspects and verifies safety of the working place to ensure safety against risks. This study performed cost-benefit analysis of the program for the eight industrial categories that were free from the program. The cost-benefit analysis is the basic method to estimate the effect of the policy execution, and used to justify the policy effectiveness. As a result, there is the biggest benefit in the manufacture of basic metal products and then motor vehicles, trailers and semitrailers, other manufacturing, other machinery and equipment, wood products of wood and cork, rubber and plastic products, food products, furniture in order. Thus the hazard prevention program should be applied into the 8 industrial categories in order to strengthen national competitiveness, protect labors's safety, reduce the social cost and improve the welfare.

• Journal of Computational Design and Engineering
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• v.3 no.3
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• pp.198-214
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• 2016

Oval substrates are widely used in automobiles to reduce the exhaust emissions in Diesel oxidation Catalyst of CI engine. Because of constraints in space and packaging Oval substrate is preferred rather than round substrate. Obtaining the flow uniformity is very challenging in oval substrate comparing with round substrate. In this present work attempts are made to optimize the inlet cone design to achieve the optimal flow uniformity with the help of CATIA V5 which is 3D design tool and CFX which is 3D CFD tool. Initially length of inlet cone and mass flow rate of exhaust stream are analysed to understand the effects of flow uniformity and pressure drop. Then short straight cones and angled cones are designed. Angled cones have been designed by two methodologies. First methodology is rotating flow inlet plane along the substrate in shorter or longer axis. Second method is shifting the flow inlet plane along the longer axis. Large improvement in flow uniformity is observed when the flow inlet plane is shifted along the direction of longer axis by 10, 20 and 30 mm away from geometrical centre. When the inlet plane is rotated again based on 30 mm shifted geometry, significant improvement at rotation angle of $20^{\circ}$ is observed. The flow uniformity is optimum when second shift is performed based on second rotation. This present work shows that for an oval substrate flow, uniformity index can be optimized when inlet cone is angled by rotation of flow inlet plane along axis of substrate.

• Journal of the Korean Ceramic Society
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• v.16 no.1
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• pp.31-37
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• 1979

The middle point of composition within the system $MgO-Al_2O_3-SiO_2$ has been studied for applicability as ceramics dielectrics. A Kyul Sung Tale of high purity, magnesia clinker of Sam-wha chemical company, C.P. aluminium oxide, calcium carbonate, red lead, barium carbonate which was made into frit were used the raw materials. A number of steatite ceramics were prepared under carefully controlled condition and the water absorption, linear shrinkage, power factor, dielectric constant and dielectric loss were measured at elevated temperature. When we used magnesia clinker as flux, the quantity of this flux was 0.05mole, sintering temperature was continued for 2 hrs. at 1, 27$0^{\circ}C$. From this conditions, we could get the data whose power factor was 0.142%, water absorption was zero, linear shrinkage was 8.76%, dielectric constant was 5.63, dielectric loss was 0.00799. When we used red lead as flux, the quantity of this flux was 0.033mole and 0.066mole, sintering temperature was continued for 2hrs. at 1, 26$0^{\circ}C$. From this conditions, we could get the data whose water absorption was zero, linear shrinkage was 8.03%, and 8.48%, power factor was 0.136% and 0.062%, dielectric loss was 0.0072 and 0.0037. When we used barium carbonate made into frit as flux, the quantity of this flux was 0.02mole, sintering temperature was continued for 2hrs. at 1, 27$0^{\circ}C$. From this conditions, we could get the data whose water absoption was zero, linear shrinkage was 8.44%, power factor was 0.138%, dielectric constant was 5.69, dielectric loss was 0.0074.