• Journal of Semiconductor Engineering
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• 제1권1호
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• pp.13-30
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• 2020

Radio frequency (RF) energy harvesting technology have become a reliable and promising alternative to extend the lifetime of power-constrained wireless networks by eliminating the need for batteries. This emerging technology enables the low-power wireless devices to be self-sustaining and eco-friendly by scavenging RF energy from ambient environment or dedicated energy sources. These attributes make RF energy harvesting technology feasible and attractive to an extended range of applications. However, despite being the most reliable energy harvesting technology, there are several challenges (especially power conversion efficiency, output DC voltage and sensitivity) poised for the implementation of RF energy harvesting systems. In this article, a detailed literature on RF energy harvesting technology has been surveyed to provide guidance for RF energy harvesters design. Since signal strength of the received RF power is limited and weak, high efficiency state-of-the-art RF energy harvesters are required to design for providing sufficient DC supply voltage to wireless networks. Therefore, various designs and their trade-offs with comprehensive analysis for RF energy harvesters have been discussed. This paper can serve as a good reference for the researchers to catch new research topics in the field of RF energy harvesting.

• 상하수도학회지
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• 제31권1호
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• pp.73-81
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• 2017

The UV/chlorine process is a UV-based advanced oxidation process for removing various organic pollutants in water. The process is becoming increasingly popular because of its effectiveness in practice. It is important to the safe and efficient operation of a UV/chlorine process that the optimal operating conditions for both target removal objective and saving energy are determined. Treatment efficiency of target compounds in UV/chlorine process was mainly affected by pH and scavenging factor. In this study, kinetic based mathematical model considering water characteristics and electrical energy dose calculations model was developed to predict of treatment efficiency and optimal operating conditions. The model equation was validated for the UV/chlorine process at the laboratory scale and in pilot tests at water treatment plants.

• Food Science and Biotechnology
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• 제17권2호
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• pp.287-294
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• 2008

Protective effects of cheonggukjang fermented with 20% red ginseng (RC) were observed in streptozotocin (STZ)-induced diabetic rats by measuring levels of blood glucose, serum lipid profiles, and hepatic reactive oxygen species generating and scavenging enzymc activities. RC diet was prepared by mixing with AIN-76 diet at the final concentration 2%, and it was fed to STZ-induced diabetic rats for 3 weeks. The RC dict was significantly improved body weight, feed efficiency ratio, levels of serum glucose, and serum and hepatic lipids in diabetes. The significantly elevated O type activity of xanthine oxidase in diabetes was also greatly decreased by the RC diet. The treatment of RC showed the improved hepatic glutathione s-transferase activities in the diabetic animals. The present study indicates that cheonggukjang fermented with red ginseng could ameliorate STZ-induccd diabetic symptoms such as aggravated blood glucose levels, serum lipid profiles, and even the conditions of oxidative stress.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권5호
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• pp.949-966
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• 2013

Recently, Wireless Body Area Network (WBAN) has promise to revolutionize human daily life. The need for multiple sensors and constant monitoring lead these systems to be energy hungry and expensive with short operating lifetimes. In this paper, we offer a review of existing work of WBAN and focus on energy-aware management in it. We emphasize that nodes computation, wireless communication, topology deployment and energy scavenging are main domains for making a long-lived WBAN. We study the popular power management technique Dynamic Voltage and Frequency Scaling (DVFS) and identify the impact of slack time in Dynamic Power Management (DPM), and finally propose an enhanced dynamic power management method to schedule scaled jobs at slack time with the goal of saving energy and keeping system reliability. Theoretical and experimental evaluations exhibit the effectiveness and efficiency of the proposed method.

• 한국환경과학회지
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• 제27권10호
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• pp.853-863
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• 2018

In order to increase the medicinal herbs efficiency of drug delivery, vesicles contained with medicinal herbs were prepared by phosphatidylcholines and surface active agent. Vesicles loaded with medicinal herbs were characterized by UV-spectroscopy, Zetasizer. The antioxidant activity of vesicles was measured by DPPH assay and ABTS radical scavenging assays. Also, an analysis was conducted to determine the effects of anti-inflammatory of vesicles contained medicinal herbs. In addition, the whitening effects of vesicles contained medicinal herbs extract were studied via tyrosinase inhibition assay. The results of vesicles were as follows. Vesicles appeared an average diameter of approximatively 164-599 nm. All studied vesicles contained with medicinal herbs showed antioxidant, anti-inflammatory and whitening effects in a dose-dependent manner. Therefore, this experiment achieves its purpose of synthesizing of vesicles. In conclusion, we recommended that the vesicles loaded with medicinal herbs have ability for anti-aging materials. Specifically, it will apply to cosmetic ingredients.

• 대한의생명과학회지
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• 제12권1호
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• pp.49-52
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• 2006

To elucidate the effect of antioxidant complex containing $\beta-carotene$, vitamin E, vitamin C, Ginkgo Biloba leaf extract and selenium on oxygen :tree radical production and detoxification system, rats were fed normal diet and normal diet with antioxidant complex 0.1%, 0.3% and 0.5% for 3 weeks. Feed efficiency ratio, changes in body weight, weight gain and amounts of feces of rat are similar in four groups. Liver weight per body weight and hepatic lipid peroxide weight increased in 0.5% group. However, hepatic glutathione contents in all antioxidant complex added groups were significantly increased compare with normal control group. On the other hand, the activity of xanthine oxidase was a little increased due to the amounts of antioxidant complex. Superoxide dismutase and gutathione peroxidase activity of 0.1% antioxidant complex added group were increased about $10{\sim}20%$ in comparison to normal control group. These results suggest that the supplementation of antioxidant complex 0.1% to basal diet may reduce the hepatic damage caused by free radicals.

• 한국환경과학회지
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• 제26권2호
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• pp.239-248
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• 2017

Green synthesis of gold nanoparticles(GNPs) considered more ecofriendly and cost effective than other chemical methods use of dangerous reagents and solvents, improved material and energy efficiency and enhanced design of non-toxic products. In this study, we developed a green synthesis method for using Caulis in Taeniam (BCT). BCT were characterized by UV-vis, Zetasizer, TEM, XRD, and FTIR. The antioxidant activity of BCT was determined by DPPH and ABTS radical-scavenging assays, and heme oxygenase-1 induction in RAW 264.7 macrophages. The resulting BCT appeared spherical with an average diameter of 67.171.39 nm The aAntioxidant activity was increased in a dependent manner. To conclude, the green synthesis of BCT-GNPs was successful, and it appers to be useful in the for future applications.

• Journal of Advanced Marine Engineering and Technology
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• 제13권3호
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• pp.26-36
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• 1989

Recently digital governor system is commonly adapted for the speed control of the marine diesel engine because of too much fluctuation of rpm resulted by the low speed, long stroke, high efficiency and a small number of cylinder of it, and versatile studies on the development of digital governor system are progressed. On this subject the new control method in which the fuel is controlled by feedforwarding the change of load as well as the feedback of angular velocity in case of disregarding the engine dead time and influence of scavenging air was proposed by the authors, and found the method has shown quite a good control performance in comparision to the conventional control method by the simulation using a digital computer for various load change. In this paper the speed control system of a diesel engine is simulated in case of regarding the engine dead time by the proposed method, and also confirm a good control performance of it under even more realistically simulated environment.

• 한국지반환경공학회 논문집
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• 제13권7호
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• pp.49-54
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• 2012

본 연구에서는 전자빔(E-beam) 공정을 이용한 펜타클로로페놀(Pentachlorophenol, PCP)의 분해 특성을 조사하였다. 이를 위해 주어진 반응시간(0.6 s) 동안 생성될 수 있는 각종 반응성 화학종의 농도를 예측하였으며, PCP 분해에 미치는 pH와 과산화수소의 영향 및 이에 따른 G-value 등을 조사하였다. 실험결과, 전자빔공정에서 PCP의 분해는 pH의 영향을 받지 않았다. 1mM 이하의 과산화수소의 주입은 PCP 분해를 촉진시킬 수 있으나 그 이상의 과산화수소의 주입은 오히려 PCP의 분해를 감소시키거나 부산물의 형성을 유도할 것으로 관찰되었다. 특히, 옥살산과 미확인된 유기염소 성분의 농도를 증가시키는 것으로 나타났다. 그래서 전자빔공정에서 수산화라디칼의 발생원으로써 적절한 농도의 과산화수소 주입이 고려되어야 할 것으로 생각된다.

• 한국약용작물학회지
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• 제17권4호
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• pp.233-237
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• 2009

Astragalus membranaceus has a long history of medicinal use in Chinese herbal medicine. It has been shown to have immunostimulant, tonic, antioxidant, antiperspirant, diuretic, anti-diabetic, expectorant properties, and a supplementary medicine during cancer therapy. In this study, we investigated the effect of anti-oxidation of Astragalus membranaceus root extract. The anti-oxidative activities of water, 80% methanol, and 100% methanol extracts from Astragalus membranaceus were analyzed by DPPH free radical scavenging activity, Superoxide dismutase-like activity, reducing power, and crude ash. The water extract demonstrated to be more effective than methanol extract for a DPPH radicals scavenging activities and reducing power. Superoxide dismutase-like activity showed higher efficiency in 80% methanol extract. Our results indicate that Astragalus membranaceus extracts could be used as a source of antioxidant ingredients in the food industry.