• Title/Summary/Keyword: AP

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Study on the Long-term Thermal Stability by DSC & ARC and its ISCO behaviors with different AP Quality (DSC, ARC, ISCO를 활용한 다양한 순도를 가진 AP의 장기 열적안정성 연구)

  • Kim, Seunghee;Kwon, Kuktae;Lee, So Jung
    • Journal of the Korean Society of Propulsion Engineers
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    • v.22 no.2
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    • pp.59-65
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    • 2018
  • We conducted an isothermal slow cook-off(ISCO) test for an aluminized explosive containing AP. The sample bulged before the run-away reaction, and therefore we were unable to obtain the ISCO data. However, these phenomena did not occur for a certain AP grade, which means that the quality of the AP exerted a significant effect on the thermal stability of the explosive formulation. In this study, we investigated the thermal stability difference between a good and bad AP grade. First, we characterized the thermal properties of all APs by Differential Scanning Calorimeter(DSC) and correlated them to the ISCO phenomena. In addition to the DSC study and ISCO test, we also investigated and calculated the SADT and self-heating rate by the ARC of the different AP qualities to interpret the thermal stability of the explosive formulation. Moreover, we investigated the impurity of the AP and a preparation method to remove the included impurity and crystallization. Finally, we implemented qualification methods to identify the quality of AP by DSC using a high-pressure crucible.

A Survey on Congestion Control for CoAP over UDP

  • Lim, Chansook
    • International Journal of Internet, Broadcasting and Communication
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    • v.11 no.1
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    • pp.17-26
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    • 2019
  • The Constrained Application Protocol (CoAP) is a specialized web transfer protocol proposed by the IETF for use in IoT environments. CoAP was designed as a lightweight machine-to-machine protocol for resource constrained environments. Due to the strength of low overhead, the number of CoAP devices is expected to rise rapidly. When CoAP runs over UDP for wireless sensor networks, CoAP needs to support congestion control mechanisms. Since the default CoAP defines a minimal mechanism for congestion control, several schemes to improve the mechanism have been proposed. To keep CoAP lightweight, the majority of the schemes have been focused mainly on how to measure RTT accurately and how to set RTO adaptively according to network conditions, but other approaches such as rate-based congestion control were proposed more recently. In this paper, we survey the literature on congestion control for CoAP and discuss the future research directions.

Antioxidant and Alcohol Dehydrogenase Activity of Water Extracts From Abalone Containing Medicinal Plants (전복과 천연 식물류 복합물의 항산화 및 알코올대사 효소 활성)

  • Shin, Jung-Hye;Lee, Soo-Jung;Choi, Duk-Ju;Kang, Min-Jung;Sung, Nak-Ju
    • Korean journal of food and cookery science
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    • v.24 no.2
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    • pp.182-187
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    • 2008
  • This study was performed to evaluate the possible production of a functional beverage derived from abalone and with several plants (AP). Five types of AP composites were prepared having different medicinal plant compositions (AP- I : abalone, garlic, jujube, Chinese matrimony fruit, dried orange peel, licorice root, zinger, honey; AP- II: abalone, garlic, black bean, Chinese matrimony fruit, cornus fruit, licorice root, zinger, honey; AP-III : abalone, jujube, arrow root, milk vetch, dried orange peel, licorice root, zinger, honey; AP-N: abalone, black bean, arrow root, milk vetch, cornus fruit, liquorice root, zinger, honey; AP-V : abalone, garlic, Chinese matrimony fruit, milk vetch, licorice root, zinger, honey). In vitro analysis were performed to examine the antioxidant contents and alcohol dehydrogenase activities of the composites. AP- II had the highest total phenol contents ($28.55{\pm}1.56\;mg/l00\;g$), and AP- V the highest level of flavonoids ($47.61{\pm}1.58\;mg/l00\;g$). At $78.89{\pm}0.16%$, AP- V displayed the strongest electron donating ability followed by AP-II($57.99{\pm}0.21%$) and API ($37.66{\pm}0.20%$). Reducing power was also significantly higher in AP- V. The Hydroxyl radical scavenging and SOD-like activities of all composites were less than 15% and 20%, respectively. At 12.5% alcohol concentration, ADH activity ranged from $114.47{\pm}2.18{\sim}121.39{\pm}4.36%$ and ALDH activity ranged from $100.04{\pm}2.90{\sim}129.54{\pm}4.80%$; AP- I , AP- II, and AP- Vin 12.5% of alcoholic concentration. The composites of AP- I , AP- II, and AP- V, all containing garlic and Chinese matrimony fruit, were significantly stronger than AP-III and AP-N. Finally, also at 12.5% alcoholic concentration, the ALDH activity of AP- V was higher than its ADH activity.

Combustion Characteristics of HTPB/AP/Zr Propellant (HTPB/AP/Zr 추진제의 연소 특성)

  • Min Byoung-Sun;Hyun Hyung-Soo;Yim Yoo-Jin
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • v.y2005m4
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    • pp.61-65
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    • 2005
  • In HTPB/AP propellants, zirconium(Zr) addition to formulation was shown to be less specific impulse than aluminum(Al) by the theoretical calculation because of the lower flame temperature and higher molecular weight of Zr oxide. It was found that the burning rate was faster with the finer size of Zr and the more content of $2{\mu}m$ Zr the faster burning rate is in HTPB/AP/Zr propellants caused by the more conduction energy transfer from Zr flame to the burning surface. Also the burning rate of HTPB/AP/Zr propellant could be reduced by addition of 150nm Al, depending on AP size distribution in formulation with Butacene and $1{\mu}m$ AP.

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A Study on the mathematics AS program (수학과 AP(Advanced Placement) 결과 분석 및 교육과정 연구 - 2005학년도 교육인적자원부 지원 AP제도를 중심으로 -)

  • Bang Seung-Jin;Choi Jung-Oh
    • Communications of Mathematical Education
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    • v.20 no.1 s.25
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    • pp.103-115
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    • 2006
  • We integrated and utilized the currently existing international AP(Advanced Placement) program in mathematics. In 2005, the KMEHRD(Korean Ministry of Education and Human Resources Development) began the mathematics AP program; we attempt to maximize its effectiveness through continuous development. In boosting educational excellence, our AP program will affect the intellectual desire and enhance the performance of mathematically gifted leaners. This program assists high school students to achieve their fullest potential.

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Combustion Characteristics of HTPB/AP/Zr Propellant (HTPB/AP/Zr 추진제의 연소 특성)

  • Min Byoung-Sun;Hyun Hyung-Soo;Yim Yoo-Jin
    • Journal of the Korean Society of Propulsion Engineers
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    • v.9 no.2
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    • pp.9-16
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    • 2005
  • Zirconium(Zr) addition to formulation of HTPB/AP propellants, was shown to be less specific impulse than aluminum(Al) by the theoretical calculation because of the lower flame temperature and higher molecular weight of Zr oxide. It was found that the burning rate was faster with the finer size of Zr and the more content of $2{\mu}m$ Zr the faster burning rate is in HTPB/AP/Zr propellants caused by the more conduction energy transfer from Zr flame to the burning surface. Also the burning rate of HTPB/AP/Zr propellant could be reduced by addition of 150nm Al, depending on AP size distribution in formulation with Butacene and $1{\mu}m$ AP.

Chemical Analysis of Acidic Proteo-heteroglycans with Anti-complementary Activity from the Hot-Water Extract of Fomitella fraxinea (장수버섯 자실체로부터 분리한 항보체 활성 단백다당체의 화학적 분석)

  • Yoon, Sang-Hong
    • The Korean Journal of Mycology
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    • v.26 no.4 s.87
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    • pp.502-510
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    • 1998
  • The hot-water extract of fruiting bodies in Fomitella fraxinea had potent anti-complementary activities. After fractionation of water-soluble polysaccharides by DEAE-Sephadex A-25 column chromatography, major anti-complementary activity was concentrated into the FF-AP1 among three polysaccharides (FF-NP, FF-AP1, FF-AP2). FF-AP1 was fractionated into $FF-AP1{\alpha}$ and $FF-AP1{\beta}$ obtained from the adsorbed fraction and unadsorbed fraction by affinity chromatography using a ConA-sepharose 4B column, respectively. $FF-AP1{\beta}$, which exihibited the highest anti-complementary activities had an IR absorption peak of $890cm^{-1}$, and a M.W. of about 15,000 (gel filtration). Anti-complementary activity of FF-AP1 decreased greatly by pronase treatment and periodate oxidation. $FF-AP1{\beta}$ responsible for potent anti-complemenary activities of Fomitella fraxinea was an acidic protein-containing heteroglycan consisted of 48% glucose, 13% mannose, and 12% galactose as major component sugars, 9.6% protein, 6% uronic acids.

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Fuel-rich Combustion with AP added Propellant in a Staged Hybrid Rocket Engine (다단 하이브리드 로켓에서 AP 첨가 추진제의 연료과농 연소)

  • Lee, Dongeun;Lee, Changjin
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.44 no.7
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    • pp.576-584
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    • 2016
  • In this study, AP added propellant has been proposed as a method of enhancing the low specific impulse performance found for staged hybrid rocket engine. Experimental tests were carried out to analyze and evaluate the effect of AP added propellant on specific impulse performance as well as fuel-rich combustion characteristics in a staged hybrid rocket engine. Upper limit of AP content in propellant was set to be 15 wt% to maintain the hybrid rocket engine advantages. As a result, 15 wt% AP added propellant showed 3% higher specific impulse performance compared to 0 wt% AP added propellant. Moreover, AP addition proved to offer less injected oxidizer mass flow, less O/F variation, and less combustion pressure while producing fuel-rich gas of the same combustion temperature. Future studies will carry out more combustion tests with metal additives to further enhance specific impulse.

Design and Implementation of a Multi-Interface Access Point with Inter-interface Dynamic Load Balancing (인터페이스간 동적 부하 분배를 고려한 다중 인터페이스 액세스 포인트 설계 및 구현)

  • Kim, Tae-Keun;Seo, Hyung-Yoon;Kim, Jong-Deok
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37 no.5A
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    • pp.348-357
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    • 2012
  • Recently, smartphone, notebook, PC and other supporting wireless LAN device have come into wide use. By increasing user that use wireless LAN device, wireless traffic also increased. If wireless traffic through one AP is increase, it causes throughput decrease. To solve this problem, wireless LAN service provider install more AP where overload occurred. But this is not enough. Because stations can't know AP's load factor, and APs do nothing for load balancing. In this paper, we propose Multi-Interface Access Point(MIAP) to solve this problem. MIAP operate same as multiple APs with multi-interface, and MIAP measure each interface's load periodically. If MIAP detect overloaded interface, MIAP transfer station from overloaded interface to under-loaded interface. We conducted an experiment for verifying existing problem, and we found this problem occurred. We plan an experiment scenario for a comparison between existing AP and MIAP, and excute these experiment. In the result, we show MIAP with load balancing can improve total throughput about 72% and stabilize delay jitter than existing AP.