• Composites Research
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• v.32 no.5
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• pp.279-283
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• 2019

A flight training simulator of a fully spherical configuration is being developed to precisely and quickly control six degrees of freedom (Dof) motions especially with unlimited rotations. The full-scale simulator should be designed with a lightweight material to reduce inertial effects for fast and stable feedback controls while no structural failure is ensured during operations. In this study, a sandwich composite consisting of glass fiber reinforced plastics and a foam core is used to obtain high specific strengths and specific stiffnesses. T-type stainless steel frames are inserted to minimize the deformation of the sphere curvature. Finite element analysis is carried out to evaluate structural safety of the simulator composed of the sandwich sphere and steel frames. The analysis considers the weights of the equipment and trainee and it is assumed to be 200 kg. Gravity acceleration is also considered. The stresses and displacement acting on the simulator are calculated and the safety is assessed under two different situations.

• Journal of the Korean GEO-environmental Society
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• v.20 no.12
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• pp.57-64
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• 2019

A man-made slope has been increased due to the construction of road. This slope lies at risk of rock falling, induced mostly by heavy rainfall. The MOLIT (Ministry of Land, Infrastructure and Transport) recommends the specific dimension of rockfall protection fence (post, wire-rope, and mesh) which should resist 48~61 kJ. However, the energy absorption capacity of each component of rockfall protection fence is not clearly presented. Hence, this study made an effort to compute the energy absorption capacity of each component in analytical and numerical method, and compared with each other.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.1
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• pp.59-65
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• 2008

In security layer in the CDMA2000 1x EV-DO, a standard - C.S0024-a v2.0 is being accomplished under the project of 3GPP2(3rd Generation Partnership Project2). Therefore, a security device is needed to implement the security layer which is defined on the standard document for data transfer security between AT(Access Terminal) and AN(Access Network) on CDMA2000 1x EV-DO environment. This paper realizes the security layer system that can make safe and fast transfer of data between AT and AN. It could be applied to various platform environments by designing and implementing the Security Layer in the CDMA2000 1x EV-DO Security Layer to which applies C.S0024-A v2.0 of 3GPP2.

• Journal of the Korea Convergence Society
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• v.12 no.8
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• pp.187-195
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• 2021

In order to assess the cell toxicity of 10 instruments made of polymers, the MTT assay which utilizes the L-929 cell was selected. Specimens were eluted at a temperature of 37℃ for 24 hours at a rate of 4g per 20mL, RPMI 1640, and then was positively and negatively contrasted with a control test solution, in accordance with the Notification No. 2020-12 Protocols of Medical Apparatus Biological Safety from the Ministry of Drug and Food Safety. As a result of 24 hours of incubation in 37℃, 5% CO₂ Incubator and assessment using an ELISA reader, the results of Intraoral camera indiciated a cellular viability of more than 70% at a 50% eluate. But, the Plastic impression tray, 3D printing tweezer, Impression disposable syringe, Dental floss holder, Hand implant scaler, Surgical retractor, Oral scanner tip, Dental mirror, and the Water pick tip all reported a cellular viability of more than 70% at a 100% eluate, which indicates that do not exhibit cytotoxicity, thus allowing it to be used in contact with the mucous membrane of the oral cavity.

• Journal of Convergence for Information Technology
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• v.12 no.4
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• pp.1-8
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• 2022

With the development of communication infrastructure, the number of network equipment owned by one person is gradually increasing. General-purpose devices such as smartphones can implement theft/loss prevention function by implementing S/W. However, other small devices lack practicality such as long-distance communication problems due to standard communication technology specifications or H/W limitations, and lack of functions(authentication and security). This study combines the Lora communication protocol in the LPWA standard environment and the blockchain technology. Anti-theft and security functions were added to the protocol, and the PBFT consensus algorithm was applied to build a blockchain network. As a result of the test, the effectiveness of safety(authentication and trust network) and performance(blockchain processing performance) were confirmed. This study aims to contribute to the future development of portable or small device anti-theft products as a 4th industrial convergence research.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.10
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• pp.739-745
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• 2022

In various environmental requirements of a fighter aircraft, the explosive atmosphere is a test to verify whether or not military products are ignited for the safety of the aircraft system and crew. For the test, the explosive atmosphere test chamber owned by the Korea Institute of Industrial Technology (KITECH) was applied, and n-hexane, which has more sensitive ignition characteristics than general fuel, was used to conduct the test conservatively. Based on Procedure I, Method 511.6, MIL-STD-810G w/Change 1, the US military environmental test specification, the scope of application, tailoring guide, and detailed test procedures are checked, and the necessity of this test for each subsystem of the fighter aircraft is considered. In this study, we present the correct tailoring method by analyzing the explosive atmosphere test results for the components installed in the fighter aircraft and sharing the derived essential points.

• Journal of Internet of Things and Convergence
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• v.9 no.2
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• pp.47-54
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• 2023

The MyData service makes anyone possible to apply the personal information for the personal credit management or the financial management by proactive managing his/her own information. The MyData means that the anyone is able to control or manage the its own information by changing from the company-oriented or the organization-oriented information to his/her own information. It is mandatory to develop the API G/W which transforms the different user format to the standard format to support the MyData service. This study is to design the API G/W for the MyData service and the designed API G/W supports the 4 major functions - Validation function, Throttling function, Authentication&Authorization function, Mediation function. The designed API G/W make it possible to support the safely and efficient MyData service by serving the various queries with the different formats.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.14 no.1
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• pp.35-42
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• 2008

Twenty eight gas impermeable plastic films for food-contact application were collected in the domestic market and material and/or migration tests for overall migration, antioxidants, potassium permanganate consumption, heavy metal, and plasticizers were carried out. The average overall migration values for NY/PE or NY/LLDPE, PETP/PE, and PVDC packaging films obtained by using n-heptane as fatty food simulant were 7.6, 6.9 and 14.1 mg/L, respectively. These values were much lower than the limit values of 150 and 30 mg/L for polyethylene and polyvinylidene chloride prescribed in the Korea Food Code. In almost of the packaging materials tested, the antioxidants such as Irganox 1010, Irganox 1076 and Irgafos 168 were found. The migration test result showed that almost of all samples except PVDC film contained Irganox 1076 and Irgafos 168, while the maximum migration value of Irganox 1076 into n-heptane was found in the Ny/PE/LLDPE(15/25/50 ${\mu}m$) sample at the concentration of 216.9 ${\mu}g/g$. From the plastic packaging samples tested, plasticizers such as DEP, DPRP, DBP, DPP, BBP, DCHP, DEHP, DEHA and observed above the detection limit. Consumption amount of potassium permanganate was much lower than the limit value of 10 mg/L. In the material test for heavy metals, cadmium and lead were determined at the concentrations far below the limit value of 100 mg/kg. The migration test for cadmium and lead showed a lower value than the detection limit. Therefore, it can be concluded that the safety status of the plastic films tested met the requirement of limit values as prescribed for the material and migration tests of food packaging utensils, containers and packages of the Korea Food Code.

• Journal of Food Hygiene and Safety
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• v.32 no.5
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• pp.411-417
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• 2017

This study was conducted to establish the analysis method for the contents of choline in infant formulas and follow-up formulas by ion chromatograph (IC). To optimize the method, we compared several conditions for extraction, purification and instrumental measurement using spiked samples and certified reference material (CRM; NIST SRM 1849a) as test materials. IC method for choline was established using Ion Pac CG column and 18 mM $H_2SO_4$ mobile phase. The parameters of validation were specificity, linearity, LOD, LOQ, recovery, accuracy, precision and repeatability. The specificity was confirmed by the retention time and the linearity, $R_2$ was over 0.999 in range of 0.5~10 mg/L. The detection limit and quantification limit were 0.14, 0.43 mg/L. The accuracy and precision of this method using CRM were 95%, 2.1% respectively. Optimized methods were applied in sample analysis to verify the reliability. All the tested products were acceptable contents of choline compared with component specification for nutrition labeling. The standard operating procedures were prepared for choline to provide experimental information and to strengthen the management of nutrient in infant formula and follow-up formula.

• Journal of Food Hygiene and Safety
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• v.32 no.6
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• pp.477-484
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• 2017

This study was conducted to investigate the content of sulfur dioxide, carotenoids and the degree of contamination of Bacillus cereus in 33 kinds of dried sweet potato from domestic mainly dried agricultural products in Korea. According to the characteristics of dried sweet potato samples, it was classified into four clusters and as a result of analyzing the contents of sulfur dioxide, carotenoids and the degree of contamination B. cereus was no significant difference among the clusters. The detection ranges of residual sulfur dioxide from 33 dried sweet potatoes ranged from 0.38 to 28.16 mg/kg, three cases (9.09%) were detected at the reference level of 10 mg/kg or more. But no samples exceeding 30 mg/kg, the tolerance level of sulfur dioxide in dried sweet potatoes were detected. Since dried sweet potato does not have a standard for carotenoids, when comparing the national and international standards of carotenoids, the range of detection of carotenoids in dried sweet potato was $46{\sim}2,663{\mu}g$/100 g, which was within the reference range of $0{\sim}9,826{\mu}g$/100 g. In principle colonies suspected to be B. cereus in dried sweet potato were not detected. In 7 cases (21.21%), there were detected in the range of 0.05~1.59 log CFU/g but not more than 3 log CFU/g as the reference value. The results of this study are expected to be used as basic data to establish quality standard for dried sweet potatoes. In order to control the quality of dried sweet potatoes in domestic market, raw materials, drying method and packaging after distribution, it is necessary to maintain and maintain the process steadily.