• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.4
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• pp.8-15
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• 2015

The demand for environmental consideration is on the increase in civil engineering. This study focuses on the development of technology to reduce the use of carbonate cement and improve its performance by using a silicate mineral and hardening agents, and presents the test results for the demonstrative evaluation of the properties of the raw material. Highly active feldspar was used as a binder to augment the bonding of the carbonate cement, and their change in strength was observed after test piece construction with the addition of soluble hardening agent. The uniaxial compression strength of the test piece of the general Portland cement with the addition of 0.5% soluble hardening agent, showed an increase by 33% and that of the test piece of cement with the addition of 70% substituted with feldspar increased by 28%. The strength of viscous soil; classified as soft ground, showed an increase of a maximum of 1.7 times when it was mixed with cement and solidifier depending on the curing period. These tests confirmed that a soluble solidifier is effective for improving the strength of a cement binder and that the highly active feldspar can be used as a binder.

• Journal of The Korean Association of Information Education
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• v.15 no.4
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• pp.635-644
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• 2011

This research analyzed the brainwave activities and brain hemispherity to find out any implications to design the connections between the activities of the brain function and the computerized arithmetic addition in two difficulty levels: easy: 1-5 vs. hard: 6-9. Thus, in developing the brain based math learning for the computer education by implicit association test(IAT) indicated the significant results for the exclusive brain location and the brain hemispherity on the theta, alpha, low alpha, beta brainwaves by QEEG analysis. The results of this study physiologically supported the theoretical background for the computerized math learning skills as well as the math learning material development. It shows the difficulty levels of math information education and the brain activities on cognitive process of the learner continued on the possible investigation of the brain science.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.1
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• pp.51-56
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• 2015

The object of this study is to obtain the optimum mix proportion of halogen free compound with flame resistance and, for the purpose, thermal/electrical characteristics test are conducted using compatibilizing agents, flame resistance agents, hydroxide aluminum, sunscreen, antioxidant and silicon oil on the base resin of linear low density polyethylene (LLDPE), Ethylene vinyl acetate copolymer (EVA). Existing compound method accompanies many requirements to be satisfied including a lot of addition of flame resistance agents, prohibition of impact on mixing capability with base and property and etc. In this study, different from the existing method, the optimum mix proportion is determined and experimented by adding nano clay. Oxygen index test shows no difference between specimens while T-6, T-9 shows oxygen index of 29[%] and 26[%], respectively. This is concluded that hydroxide aluminum, which is a flame resistance agent, leads low oxygen index. From UL94-V vertical flame resistance test, the combustion behavior is determined as V-0, Fail based on UL94-V decision criteria. Viscometry shows low measurements in specimens with separate addition of compatibilizing agents or nano clay. Volume resistivity test shows low measurement mainly in specimens without compatibilizing agents. Therefore, with the flame resistance compound shows better performance for thermal/electrical property and the optimum mix proportion are achieved among many existing materials.

• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2387-2395
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• 2021

Seismic qualifications of electrical equipment, such as cabinet systems, have been emerging as the key area of nuclear power plants in Korea since the 2016 Gyeongju earthquake, including the high-frequency domain. In addition, electrical equipment was sensitive to the high-frequency ground motions during the past earthquake. Therefore, this paper presents the rocking behavior of the electrical cabinet system subjected to Reg. 1.60 and UHS. The high fidelity finite element (FE) model of the cabinet related to the shaking table test data was developed. In particular, the first two global modes of the cabinet from the experimental test were 16 Hz and 24 Hz, respectively. In addition, 30.05 Hz and 37.5 Hz were determined to be the first two local modes in the cabinet. The high fidelity FE model of the cabinet using the ABAQUS platform was extremely reconciled with shaking table tests. As a result, the dynamic properties of the cabinet were sensitive to electrical instruments, such as relays and switchboards, during the shaking table test. In addition, the amplification with respect to the vibration transfer function of the cabinet was observed on the third floor in the cabinet due to localized impact corresponding to the rocking phenomenon of the cabinet under Reg.1.60 and UHS. Overall, the rocking of the cabinet system can be caused by the low-frequency oscillations and higher peak horizontal acceleration.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.419-424
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• 2000

The primary objectives of this study are to investigate the properties of strength and durability of recycled aggregate concrete was added polypropylene as variables and to fabricate fine concrete in some conditions. The variables are substitution ratios of recycled aggregate(0, 30, 50, 100%) and additions of polypropylene(0, 0.2, 0.5, 1.0%). Compressive strength test to investigate strength properties and freeze-thawing test and drying shrinkage test to durability properties were done. As the result of this study, When variables are substitution ratio(30%) of recycled aggregated and addition(0.5%) of polypropylene, fine concrete was fabricated.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10b
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• pp.1037-1040
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• 1988

In this study, we performed the recognition test on Korean vowel using peripheral auditory model. In addition, for the purpose of objective comparision, the recognition test is performed by extracting LPC cepstrum coefficients from the same data. And the same speech data are mixed with the Guaussian white noise quantitatively, then we repeated the same test, too. So we verified that this auditory model has a adaptability on noise.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.969-974
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• 2002

Recently, many studies are performed according to increased interests about factory or room acoustics. In this study, the inside and environmental noise conditions of Diesel-locomotive load test building were investigated by multi-channel noise measurement system. In addition to this, the mitigation effects of environmental noise from this test building were analyzed using commercial software.

• International Journal of Highway Engineering
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• v.19 no.2
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• pp.17-24
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• 2017

PURPOSES : This study aims to develop a sealant for use in the installation of Weigh-In-Motion (WIM) sensor for asphalt concrete or cement concrete pavements. METHODS : In order to investigate the properties of various sealants that were mixed with latex and carbon fiber, various test methods were adopted, such as bituminous bond strength test, softening point test, and cone penetration test. To evaluate moisture susceptibility, the BBS test was conducted under moist condition. The bond strength ratio (BSR) was calculated based on tensile strength ratio method. RESULTS : The sealant's properties significantly varied according to the amount of latex or carbon fiber. The usage of latex marginally enhanced the cone penetration test result, notwithstanding reduced asphalt content. This implies that the sealant will be proper cold temperature reason. Moreover, the addition of latex and carbon fiber evidently increased the softening point. This indicates that the tendency of the material to flow at elevated temperatures is encountered during service. With the addition of latex and carbon fiber, the moisture susceptibility measured with BSR improved marginally, while the bond strength under dry condition decreased marginally. Sealant F displays the highest bond strength and BSR under limited test conditions. CONCLUSIONS : According to the proportion of latex and carbon fiber mixed, properties of sealant, such as softening point, cone penetration, and BSR varied marginally. This indicates that the sealant has to be applied considering the environmental condition, to improve service life.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.56-65
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• 2019

Recently, automobiles have been developed for safety and environmental reasons. Particularly, awareness of automobile safety is changing significantly. As a result, safety systems developed by ADAS have emerged. However, the period of mass production through ADAS development and test evaluation is long. Therefore, in this paper, we develop a brake dynamometer to shorten the time required for ADAS development and test evaluation. In addition, the developed brake dynamometer satisfies the international standard JIS D-0210, and the user can evaluate the braking force by selecting test conditions and test method for each mode of ADAS. We use the ACC, LKAS, and AEB scenarios proposed in previous studies to verify the reliability of the developed brake dynamometer. The developed brake dynamometer was verified by comparing the test values and the calculated values using theoretical formulas of the proposed ADAS mode based on previous studies. In addition, it is expected that the performance evaluation of brake parts for each ADAS mode will be possible in an environment where the vehicle test of ADAS is not possible in the future.

• The Korea Journal of Herbology
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• v.33 no.4
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• pp.53-58
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• 2018

Objectives : Kaempferia parviflora Rhizome is black ginger indigenous to Laos and Thailand. It has been used as a folk medicine to improve blood flow and promote vitality and longevity with good health and well being. For these reasons, Kaempferia parviflora Rhizome has been focused on developing it as a food or food supplement. In addition, Kaempferia parviflora Rhizome could be under consideration of new prescription based on its characteristic compounds, polymethoxyflavonoids. However, it needs to be certified as safe before it can be used. Here, a single-oral toxicity test and safety classification was carried out to identity acute information of the toxicity of Kaempferia parviflora Rhizome powder and to make sure of its safety in clinical applications. Methods : Test substance was orally administered to male and female SD-rat at dose levels of 5000 mg/kg to estimate approximate lethal dose(ALD). Based on the acute information of the toxicity, the safety classification was estimated using the HED(human equivalent dose)-based MOS(margin of safety). Results : At 14 days after treatment with test substance. there were no of test substance related with mortalities and clinical signs. In addition, no changes in the body or organ weights and no gross or histopathological findings were observed. Thus, the ALD of Kaempferia parviflora Rhizome powder was considered over 5,000 mg/kg in both female and male mice. Conclusions : Based on the single oral toxicity test using the highest and limit dose, 5,000 mg/kg and the decision guideline for safety classification based on HED-based MOS, it was estimated that Kaempferia parviflora Rhizome powder is classified as "Specified class B" indicating that clinical dose is not limited to patients as safe as food.