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홍성현,송명엽 대한금속·재료학회 2015 METALS AND MATERIALS International Vol.21 No.2
In order to prepare an additive-free sample with a single MgH2 phase, 90 wt% Mg-10 wt% MgH2 (named 90Mg-10MgH2) was milled under a hydrogen atmosphere in a horizontal ball mill, and then hydrided. The hydrogenabsorption and desorption properties of the prepared samples were investigated, and compared with thoseof milled pure Mg and purchased MgH2. X-ray diffraction analysis, measurement of specific BET surface areas,and observation of the prepared samples by scanning electron microscope were performed. The 90Mg-10MgH2sample after hydriding-dehydriding cycling had small and large particles with fine particles on their surfaces,and had much finer particles and more defects than the milled pure Mg sample after hydridingdehydridingcycling. The specific BET surface areas of the milled Mg and 90Mg-10MgH2 were measuredas 7.81 and 99.81 m2/g, respectively. A sample that had almost a single MgH2 phase could be prepared byhorizontal ball milling and the first hydriding reaction of 90Mg-10MgH2. 90Mg-10MgH2 released 5.82 wt% H forabout 70 min, while unmilled MgH2 (Aldrich) released 6.04 wt% H for about 100 min, at 648 K.
ISO/IEC 18000-7 433MHz 능동형 RFID 시스템 기반의 인식거리 향상을 위한 멀티홉 릴레이 시스템
홍성현,송인찬,장홍,장경희,신동범,이형섭,Hong, Sung-Hyun,Song, In-Chan,Zhang, Hong,Chang, Kyung-Hi,Shin, Dong-Beom,Lee, Heyung-Sub 한국통신학회 2009 韓國通信學會論文誌 Vol.34 No.5
In this paper, we analyze the active RFID systems ISO/IEC 18000-7 and ISO/IEC 18000-4. In order to improve the coverage in sensor networks, which consist active RFID tag, we propose RFID multi-hop relay system using active RFID relay tag. To compare the performance between the existing ISO/IEC 18000-7 system and the proposed RFID multi-hop relay system, we introduce new system efficiency measure and sensitivity-based measure of achieved coverage. Also, we analyze the performance of the proposed system and compare it with that of the existing system through MCL (Minimum Coupling Loss) analysis and SLS (System Level Simulation) analysis. 본 논문에서는 능동형 RFID 시스템인 ISO/IEC 18000-7 및 ISO/IEC 18000-4 시스템에 대하여 살펴보고, 능동형 RFID 태그로 구성된 센서 네트워크에서 인식거리 향상을 위해 능동형 RFID 릴레이 태그를 사용하는 RFID 멀티홉 릴레이 시스템을 제안한다. 기존 ISO/IEC 18000-7 시스템과 제안된 RFID 멀티홉 릴레이 시스템의 성능평가를 위하여 Sensitivity에 의한 인식거리 및 시스템 효율과 같은 항목을 새롭게 정의하며, MCL (Minimum Coupling Loss) 분석과 SLS(System Level Simulation) 분석을 통해 제안된 시스템의 성능을 비교 및 분석한다.
Improved Functionality of Soft Soybean Curd Containing Monascus Fermented Soybean Ethanol Extract
홍성현,이인형,김석중,임지영 한국식품과학회 2012 Food Science and Biotechnology Vol.21 No.3
Monascus fermented soybeans (MFS) were produced by solid state fermentation and ethanol extractions were carried out to recover monacolin K (MK) and isoflavones from the MFS. About 99 and 87% of monacolin K (891 mg/kg) and isoflavones (895 mg/kg)were recovered by 80%(v/v) ethanol extraction. The 80%ethanol extract also showed significantly higher antioxidant activities (DPPH, ABTS radical scavenging activity, and ferric reducing antioxidant power) than the other ethanol extracts prepared by either 40 or 60% ethanol. The 80%Monascus fermented soybeans extract (MFSE) also contained significant α-glucosidase inhibitory activity (2.7acarbose g equivalents/g MFS). Based on the results,MFSE can be used to enrich bioactive MK and isoflavone aglycones in soft soybean curd products.
홍성현,박성길,이종민,한태룡,백영숙,정인식 경희대학교 생명자원과학연구원 1999 硏究論文集 Vol.20 No.-
홍화로부터 열에 의한 안정성을 검토하였다. 황색소의 분해반응은 산성, 중성, 염기성 조건에서 UV/Vis spectral measurement에 의해 조사되었다. 시간변화에 다른 흡광도를 측정해 본 결과 온도가 상승함에 따라 황색소의 분해되는 정도가 점차적으로 증가하는 것을 확인 할 수 있었다. 40℃에서 황색소의 분해 반감기는 pH3.0, pH7.0, 그리고 pH12.0에서 각각 112.1, 39.3 과 25.3 시간이었다. 이것은 황색소가 pH3.0에서 비교적 더 안정함을 말한다. pH3.0, 7.0 그리고 12.0에서 황색소의 activation energy는 각각 519, 15.0 그리고 12.3 kJ/mol이었다 We investigated thermal stability of yellow pigment from Carthamus tinctorious L. Decomposition reactions of yellow pigment were monitored at acidic, neutral and alkaline conditions by UV/Vis spectral measurement. Decomposition of yellow pigment increased as temperature increased Decomposition half lives of yellow pigment at 40℃ were 112.1 39.3, and 25.3 hrs at pH 3.0 , pH 7.0, and pH 12.0, respectively, indicating that yellow pigment is more stable at pH 3.0. The activation energies of yellow pigment at pH 3.0, pH 7.0, and pH 12.0 were 51.9, 15.0, and 12. 3 kJ/mol, respectively.
홍성현,김현진 한국입자에어로졸학회 2009 Particle and Aerosol Research Vol.5 No.4
Tungsten carbide powder was fabricated with carbothermal reaction by pulsed electric current flowing in compact of tunsten oxide and carbon. The mixed powder of tunsten oxide and carbon was ball-milled into ultrafine powders. The mixed powder of tungsten oxide and carbon was put into carbon mold and heat-treated at 1050~1200℃ by pulsed electric current flowing. The formation of tungsten carbide powder could be achieved by heat treatment at 1200℃ for 10 minitues. Key words : Tungsten carbide, Tungsten oxide, Carbothermal reaction, Pulsed electric current, Powder
알루미늄 호일 스크랩 재활용에 의한 플레이크 분말 제조
홍성현,김병기 한국자원리싸이클링학회 2000 資源 리싸이클링 Vol.9 No.4
알루미늄 호일 스크랩의 건식 및 습식 볼밀링에 의하여 알루미늄 플레이크 분말을 체조하는 재활용 기술에 대해 여 연구하였다. 볼밀링시 알루미늄 호일 스크랩들은 볼에 의한 미소 단조에 의하여 서로 층상으로 겹쳐지고 연산되면서 작은 호일로 쪼개진 후 플레이크 분말로 변하였다. 이러한 스크랩중에 $60\mu\textrm{m}$ 이하의 호일 스크랩은 볼밀링에 의하여 알루미늄 페이스트로 재활용이 가능하였고 초기 호일의 두께가 작을수록 쉽게 플레이크 분말화가 가능 하였다. 알루미늄 호일 스크랩의 봉밀링에 의하여 얻은 풀레이크 분말을 함유하는 알루미늄 페이스트와 가스 분사된 분말을 초기원료로 사용하여 불밀링한 플레이크 분말을 함유하는 페]이스트를 유리관위에 폐인팅한 후 외관 및 광택도를 비교한 결과, 그 특성은 유사하였다. Recycling technology of aluminum foil scraps into aluminum flake powder by ball milling in dry or wet conditions was studied. Aluminum foil were laminated each other, elongated through microforging by the falling balls, fragmented into small foils and then changed into flake powder during ball milling. It is also possible to recycle foil scraps with thickness less than $60\mu\textrm{m}$ into aluminum paste by wet ball milling. As initial foil thickness decreases, foil is easily milled to flake powder by wet milling in mineral spirits. the appearance and the opaque character of glass painted with aluminum paste obtained by wet milling of foils are similar to those of aluminum paste made by ball milling of gas atomized powder.