• Applied Chemistry for Engineering
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• v.20 no.1
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• pp.67-74
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• 2009

Nowadays, recycling of recycled aggregates from the waste concrete is seriously demanded for the protection of environment and the shortage of aggregates owing to the large scale construction project. In this study, for the development of polymer composite recycling recycled aggregates from the waste concrete, twenty five specimens of the polymer composite were prepared with the five levels of replacement ratios of recycled aggregates (0, 25, 50, 75, 100%) and polymer-cement ratios (0,5, 10, 15, 20%), respectively. For the evaluation of the performance of polymer composite specimens, various physical properties such as compressive and flexural strengths, water absorption, hot water resistance, total pore volume and porosity were investigated. As a result, physical properties of polymer composite were remarkably improved with an increase of polymer cement ratios, but greatly decreased with the replacement ratios of recycled aggregates.

• Journal of Physiology & Pathology in Korean Medicine
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• v.29 no.5
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• pp.403-408
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• 2015

Traditionally, 5 kinds of fruits with "ja(子)" in their name, including Rubus coreanus, Schisandra chinensis, Lycinum chineuse, Torilidis fructus, and Cuscuta seed, collectively called Oja(五子), are long known to enhance stamina. In the present study, we replaced tosaja with gyeolmyeongja(Cassiae semen ) and examined the effects of extracts from these fruits on andropause. This study investigated the antioxidant effect and testosterone synthesis of Oja water extract on Leydig TM3 cells. To investigate whether hydrogen peroxide induces oxidative stress in Leydig cells, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay, nitric oxide assay, and testosterone assay were performed on mouse Leydig TM3 cells. The results were obtained as follows: Leydig TM3 cells viability was assessed by a modified MTT assay, and the protection effect of Oja water extract against hydrogen peroxide-induced cell oxidative stress were examined by mitochondrial activity. Oja water extract could efficiently protect cytotoxicity induced by H₂O₂. Oja water extract promoted testosterone synthesis. These results suggest that Oja water extract has protective roles and promotes steroidogenesis in Leydig cells through its anti-oxidant action.

• Steel and Composite Structures
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• v.23 no.2
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• pp.153-160
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• 2017

It is extremely important to be aware of the ballistic performances of engineering materials in order to be able to choose the lightest armor providing full ballistic protection in civil and military applications. Therefore, ballistic tests are an important part of armor design process. In this study, ballistic performance of plates made of carbon steel and cold worked tool steel against 7.62 mm AP (armor-piercing) bullets was examined experimentally and numerically in accordance with NIJ standards. Samples in different sizes were prepared to demonstrate the effect of target thickness on ballistic performance. Some of these samples were coated with titanium nitride using physical vapor deposition (PVD) method. After examining all successful and unsuccessful samples at macro and micro levels, factors affecting ballistic performance were determined. Explicit non-linear analyses were made using Ls-Dyna software in order to confirm physical ballistic test results. It was observed that the ballistic features of steel plates used in simulations comply with actual physical test results.

• Journal of Sensor Science and Technology
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• v.27 no.1
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• pp.59-63
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• 2018

Among Internet of things (IoT) applications, the most demanding requirements for the widespread realization of many IoT visions are security and low power. In terms of security, IoT applications include tasks that are rarely addressed before such as secure computation, trusted sensing, and communication, privacy, and so on. These tasks ask for new and better techniques for the protection of data, software, and hardware. An integral part of hardware cryptographic primitives are secret keys and unique IDs. Physical Unclonable Functions(PUF) are a unique class of circuits that leverage the inherent variations in manufacturing process to create unique, unclonable IDs and secret keys. In this paper, we propose a low power Arbiter PUF circuit with low error rate and high reliability compared with conventional arbiter PUFs. The proposed PUF utilizes a power gating structure to save the power consumption in sleep mode, and uses a razor flip-flop to increase reliability. PUF has been designed and implemented using a FPGA and a ASIC chip (a 0.35 um technology). Experimental results show that our proposed PUF solves the metastability problem and reduce the power consumption of PUF compared to the conventional Arbiter PUF. It is expected that the proposed PUF can be used in systems required low power consumption and high reliability such as low power encryption processors and low power biomedical systems.

• Journal of Families and Better Life
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• v.31 no.6
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• pp.39-51
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• 2013

Because of the increasing demand for day care centers, The Korean government has enforced childcare accreditation. The government has created the evaluation certification system for child care facilities. But the system includes variable items, and the physical rules are not sufficient for ensuring security and quality amenities. So this study, through literature search, examined the rules of Child Care Centers in the U.S. and compared them with those in Korea focusing on the provision of security and amenities. The standards found in 4 U.S. states were investigated, and the results are as follows. The rule pertaining to the size of indoor activity spaces in C.C.C. allows the spaces to be smaller in Korea than in the U.S. There is no specific criterion for infants and toddlers in our standard. When comparing the standards of Korea with those of the United States, Korea's standards do not state specific rules about child care facilities such as indoor furniture, finishes and space planning. Additionally, the binding force ensuring compliance with the standards of physical facilities is weak. Thus, the ratings of child care standards for the physical environment should be presented in detail. And if a center does not comply with the criteria, stronger penalties will have to be imposed.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.1
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• pp.47-54
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• 2008

As the demands of environment protection increases, the pulp mold container is developed to substitute for EPS (expanded polystyrene) as a shock absorbing packaging material. The water-absorbing ratio and mechanical properties such as tensile strength and compressive strength of pulp mold are important factors to evaluate its shock absorbing characteristics. Influences of mixing ratios of ONP (old newspaper) and OCC (old corrugated container) on physical properties of pulp mold were investigated at various conditions of temperature and relative humidity. The optimum mixing ratio of ONP and OCC was also searched based on physical properties. The results showed that when relative humidity was increased from 60% to 90%, the water absorption ratio of pulp mold increased significantly, tensile strength decreased 20$\sim$30%, and compressive strength decreased 10$\sim$20%. In addition, the optimum mixing ratio of ONP and OCC was found to be 50%:50%.

• Nuclear Engineering and Technology
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• v.56 no.5
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• pp.1932-1940
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• 2024

The current work deals with investigation of the gamma ray shielding properties for various natural stones from Vietnam to be applied in the radiation shielding applications. The physical and chemical properties affecting the γ-ray shielding performance were examined. The MH-300A density meter was utilized to measure the density (ρ, g/cm³) of stone samples, as well as the chemical composition of Vietnamese natural stones was measured using the X-ray fluorescence analyzer (Olympus X-5000). The study shows that the increase in Fe + Ca concentrations within the stone samples increases their density (from 2.48 to 2.86 g/cm³) accompanied with a reduction in the porosity (Φ, %) (from 8.23 to 0.15%) and water absorption (K, %) (from 3.42 to 0.05%) factors. Additionally, the increase in Fe + Ca concentrations increases the linear attenuation coefficient (μ, cm^-1) of the studied stones, where the Vietnamese marble stone (M 3.1) with the highest Fe + Ca concentration (65.97 wt%) has the highest linear attenuation coefficient which varied between 3.781 and 0.155 cm^-1 with raising the gamma ray energy between 0.040 and 1.332 MeV.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.2
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• pp.203-211
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• 2008

More recently, the massive marine bridges in a ship passage have been constructed on the sea. Therefore, the ship impact protection for the bridge-piers are installed to consider the possibility of vessel collision danger. Due to the ship impact protection, the pier-scour characteristics are changed in comparison with the condition without the ship impact protection (SIP). In this study, the physical modeling for the Incheon Sea-Crossing Bridge was performed to analyze the pier-scour characteristics with respect to the vessel collision protection. The rigid and movable bed tests were conducted to evaluate the flow pattern, scour depth, and scourhole with and without the ship impact protection. The experimental results for the maximum scour depth is increased 0.24 m in W1 pier at the same location and 2.4 m in W2+3+4 piers due to the SIP installation. Especially, the maximum scour depth in W2+3+4 piers was occurred around the SIP.

• Journal of the Korean Society of Clothing and Textiles
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• v.28 no.12 s.138
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• pp.1554-1561
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• 2004

In the U.S., outdoor enthusiasts such as golfers have been focused on skin cancer prevention practices since their outdoor activities lead to extensive sun exposure during peak sun hours. The purposes of this study were to investigate golfers current sun protection behaviors and five attributes and their impacts on the intention to adopt UV specialized clothing based on Rogers' theory. UV specialized clothing as a preventive innovation is related to sun protection behaviors. However, there has been little effort to explain the intention to adopt a preventive innovation regarding health-related practices. With a convenience sampling method, a total of 158 useful questionnaires were collected. Ninety one percent were male golfers, and their age ranged from 16 to 80 years old(mean age=30 years). About $25\%$ reported to practice sun protection behaviors. About $70\%$ disagreed on the relative advantage, compatibility, observability, and triability of UV specialized shirts and reported the low intention to purchase it. Current sun protection behaviors and five attribute variables were entered in the multiple regression equation to explain the dependent variable of intention to adopt the innovation. Triability was the best predictor of the intention to adopt UV specialized shirts, followed by current sun protection behaviors, compatibility, and relative advantage. With four predictors, $45\%$ of the variance of intention to adopt was explained. The present study provides how the golfers current sun protection behaviors play important roles in explaining the intention to adopt the preventive innovation. Physical and functional features of UV specialized clothing were also significantly associated with their intentions to adopt it.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.37 no.3
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• pp.247-256
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• 2011

Existing organic UV protection materials seem to be problematic due to their penetration and irritation to skin. Inorganic UV protection materials are also at issue for safety of their nano-type transformation. Therefore, the recent studies of UV protection materials have been focused not only on the effectiveness but also on their safety. One of the UV protection materials in study which have higher safety is the organic-inorganic conjugation type UV protection material. Previously, we have reported the manufacturing process, physical property and UV protection efficiency of methoxychinnamidoprophy poloysilsesquixan as a new cross-linked polymer type UV protection material. In this study, we have evaluated the effect of the methoxychinnamidoprophy poloysilsesquixan on embryo-fetal development in SD rats. This study is expected to show some definite information related to the effect on pregnancy or embryo-fetal abnormality in case of the clinical exposure of the methoxychinnamidoprophy poloysilsesquixan.