• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.2
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• pp.220-228
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• 2012

In this paper, we explained the design technique about Ka-band active limiter for protecting the receiver of a millimeter wave seeker. To implement low flat leakage power, we proposed the control circuit of active limiter to control limiter voltage with PRF(Pulse Repetition Frequency) signal and input power. This active limiter consisted of the conventional 2 stage passive limiter, a feedback circuit with a directional coupler, detector, non-inverting amplifier and over-current protection resistance. As the test result of the fabricated Ka-band limiter, it had 1 GHz bandwidth, 3.5 dB insertion loss at the small input power and -7.5 dBm flat leakage at the 4 W RF input power, respectively.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.5
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• pp.557-563
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• 2007

Rain-wind induced cable vibration can cause serious problems in cable-stayed bridge. External dampers attached to the cables have become widely accepted as an effective means for stay-cable vibration suppression. For very long stay-cables, however, such damper systems are rendered ineffective, as the dampers need be attached near the end of cables for aesthetic reasons. A recent study by the authors proposed that a movable anchorage system is replaced direct fixed support of the cable with a support through a bearing and damper. This paper extends the previous work by adding active control system to mitigate the cable vibration. The response of a cable with the proposed active control system is obtained and then compared to those of the cable with and without an external passive damper. The results show that the active control system can provide superior protection than the passive control system for a cable vibration.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.4
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• pp.214-220
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• 2008

The Ballast Water Management Convention provides that ballast water treatment systems which make use of active substances shall be approved from IMO according to the procedure developed by the IMO. The Convention described that active substance means a substance or organism, including a virus or a fungus, that has a general or specific action on or against harmful aquatic organisms and pathogens. The Marine Environment Protection Committee of IMO gave basic approval to 13 ballast water management systems and final approval to 4 systems until October 2008. This paper considered the matter of procedure and documents of the basic and final approval based on the "Procedure for approval of ballast water management systems that make use of Active Substances (G9)" and "The Methodology for information gathering and the conduct of work of the GESAMP-BWWG" and summarized the specifications of the treatment systems which was granted the basic or final approval from IMO and raised several points.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.6
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• pp.569-576
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• 2012

In general, aluminum alloys forms the passive film($Al_2O_3$, $Al_2O_3{\cdot}3H_2O$) in neutral solution. However, the passive film created on the surface will be destroyed by chloride ions contained in sea water so the corrosion will occur. In this study, in order to solve the problem of corrosion under a seawater environment, potentiostatic protection techniques were applied to Al-4.5%Mg-0.6%Mn aluminum alloy in seawater. At polarization experiments, active state were observed at anodic polarization and concentration polarization by reduction of dissolves oxygen and activation polarization were found at anodic polarization. As a results of potentiostatic experiment, calcareous deposit were created much more as applying time increase from the turning point of the concentration polarization and activation polarization and crevice corrosion was partially observed between calcareous deposit and surface of base metal. Overall potentiostatic anodic polarization experiment was difficult to apply potentiostatic corrosion protection technology by occurrence of active state, whereas potentiostatic cathodic polarization experiment examined optimum corrosion protection condition of -1.1 V~-0.75 V within the range of concentration polarization considered various applying time.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.38 no.1
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• pp.91-101
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• 2012

This study's purpose is to research the antioxidant power of Calaguala (Polypodium leucotomos, PL) as an oral supplement: Calaguala, a native of Central America, is a fern which belongs to the family polypodiaceae protecting the skin from the ultraviolet and active oxygen free radicals. The total 14 volunteers, each female 7 & male 7, were divided into 2 groups, then exposed to UV for 30 min after taking Calaguala and placebo. The total antioxidant capacity (TAC) was analyzed by taking the blood samples from anticubital vein 3 hours after UV exposure. First, Calaguala siginifcantly decreased the concentration of active oxygen free radicals 4 weeks later. The concentration of active oxygen free radical in PL group declined more than placebo group, when measured 30 min and 3 hours after UV exposure. Second, Calaguala did not significantly increase TAC 4 weeks later, but significantly decreased TAC 3 hours after exposure, when compared with placebo group. Now days, the photo allergy and photo aging caused by air pollution and ozone destruction have drastically increased, and thus the amount of UV radiation reaching the earth's surface increased. The increase of active free oxygen radicals resulted in accelerating the diseases and aging. The first superficial protecting protection by reflection & dispersion and the second body internal protection by taking oral photo antioxidant such as Calaguala should be continuously researched.

• The Korean Journal of Pesticide Science
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• v.20 no.1
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• pp.30-34
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• 2016

To evaluate the efficacy of natural nematicides for the control of root-knot nematode in strawberry greenhouses, commercial essential oils were examined by 24-well culture plate bioassay for their nematicidal activities against second-stage juveniles and eggs of Meloidogyne hapla. Based on the mortality of M. hapla juveniles at a concentration of $125{\mu}g/mL$, the most active essential oil was Alpinia galanga (100%), followed by Carum carbi (22.3%), Eugenia caryophyllata (9.4%), Cinnamonum zeylanicum (7.2%), Mentha pulegium (2.4%), and Foeniculum vulgare (2.1%). Moreover, A. galanga significantly reduced hatching at 7, 14, and 21 days after treatment. The volatile constituents identified in the A. galangal oil were methyl cinnamate (87.4%), 1,8-cineole (4.4%), ${\beta}$-pinene (2.5%), ${\alpha}$-pinene (2.2%), and p-cymene (1.1%), as major constituents. Results of this study show that A. galangal essential oil and its major constituents may serve as an environmental friendly agent of a promising natural nematicide to control Meloidogyne spp.

• 한국환경농학회:학술대회논문집
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• 2009.07a
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• pp.220-227
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• 2009

For last about 10 years, the Republic of Korea experienced 3 times of outbreaks of highly pathogenic avian influenza (HPAI) from 10 December 2003 to 30 April 2004 (a total number of 19 outbreaks), 22 November 2006 to 6 March 2007 (a total number of 7 outbreaks), and 1 April 2008 to 12 May 2008 (a total number of 33 outbreaks). Among the totally 59 outbreaks, the infected premises included 35 chicken farms, 17 duck farms, 1 quail farm, and 6 farms rearing mixed species. Control measures were applied according to the HPAI standard operation procedure including depopulation of all infected and suspected flocks, movement restrictions, and disinfection of the infected farms within a 500-meter radius. Including movement restrictions, stringent control measures were additionally applied to two designated zones: the protection zone was an area within a 3-kilometer radius of the outbreak farm, and the surveillance zone was an area between a 3- to 10-kilometer radius of the outbreak farm. Farms with dangerous contacts and/or all of poultry within the protection zone was subjected to preemptive culling. Epidemiological investigations were also carried out including trace-back and trace-forward investigations to identify possible sources of spread and dangerous contact farms. Investigation teams conducted on-site examination of farm premises and facilities, interview with farm owner and staff, and review of records. Genetic and pathogenic characteristics of the virus isolates, and the results of the various surveillance activities were also analyzed. HPAI surveillance conducted in Korea includes passive surveillance of investigating notified cases, and active surveillance of testing high risk groups and areas. HPAI is a notifiable disease in Korea and all suspect cases must be reported to the veterinary authorities. Cases reported for other poultry diseases that require differential diagnosis are also tested for HPAI. Active surveillance includes annual testing of breeder duck farms, broiler duck farms and wild bird surveillance, which is concentrated during the autumn and winter. Surveillance activities conducted prior to the outbreaks have shown no evidence of HPAI infection in Korea.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.5
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• pp.22-28
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• 2002

A protection scheme for Unified Power Quality Conditioner (UPQC) is presented and analyzed in this paper. The proposed UPQC has the series active power filter operated as a high impedance k($\Omega$) to the fundamentals when the over current occurs in the power distribution system, and three control strategies are proposed in this paper. The first is the method by detecting the fundamental source current through the p-q theory,［1］ the second is the method by detecting the fundamental component of load current in Synchronous Reference Frame(SRF) and the third is the method by detecting the input voltage. When the over current occurs in the power distribution system, the proposed scheme protects the UPQC without additional protection circuits. The validity of proposed protection scheme is investigated through simulation results.

• Journal of KIISE:Information Networking
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• v.28 no.4
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• pp.641-650
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• 2001

In recent years, e-Commerce is very active on the Internet, especially the World Wide Web along with the popularization of Internet using high-speed networks. Especially, Electronic Software Distribution(ESD) is widely being focused as one of the popular researches. However, the existing models of ESD lack substantial illegal copy protection or copyright protection as they have the shortcomings of guaranteeing anonymity of users. This study suggests an ESD protocol that guarantees substantial copyright protection and anonymity based on the Public Key Infrastrncture(PKl). The suggested method does not give the information of a buyer who doesn't want to reveal to a seller, and protects illegal copy and distribution as well. When it happens that illegal copies are in circulation, this method provides a device to trace back its original distributor so that it helps protect the copyright. In addition, it provides more convenient environment to the user by not using the methods of serial number input and extra installation to use.

• Proceedings of KOSOMES biannual meeting
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• 2005.05a
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• pp.161-165
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• 2005

Recently, it is on the increase interest for Al alloy with new material for ship application to substitute for FRP ship. The reason is thatAl alloy ship has beneficial characteristics such as high sea speed, increase of loadage and easy to recycle compared with FRP ship. In this paper, mechanical and electrochemical properties are investigated by slow strain rate test experiment in various applied potential condition. These results will provide as reference data to design ship by deciding optimum protection potential regard to hydrogen embrittlement and stress corrosion cracking. In general, Al and Al alloys are not corroded with forming film which has the corrosion resistance property in neutral solution. However, it was observed that formation and destruction of passive film by $Cl^-$ ion in sea water environment. At comparison of current density after 1200 sec in potentiostatic experiment, the current density in the potential range of -0.68 $\~$-1.5 V is shown low value. The low current density means protection potential range. Elongation in applied potential of 0 V was high. However, the corrosion protection application in this condition is impossible potential because the toughness is low value by decreasing strength by active dissolution reaction at parallel part of specimen. The film composed with $CaCO_3$ and $Mg(OH)_2$ has a corrosion resistance property. However, the uniform electrodeposition coating at below -1.6 V potential is not formed since the time to form the uniform electrodeposition coating is short. Therefore, it is concluded that mechanical property is poor because effect by hydrogen gas generation is larger than that of electrodeposition coating. It is concluded that the optimum protection potential range from comparison of_maxim urn tensile strength, elongation and time to fracture is -1.3$\~$0.7 V (SSCE).