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열증착법으로 성장된 ZnO 나노구조물의 산소유량 변화에 대한 성장 변화
김경범,장용호,김창일,정영훈,이영진,조정호,백종후,남산,Kim, Kyoung-Bum,Jang, Yong-Ho,Kim, Chang-Il,Jeong, Young-Hun,Lee, Young-Jin,Jo, Jeong-Ho,Paik, Jong-Hoo,Nahm, Sahn 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.10
ZnO nanostructures were developed on a Si (100) substrate from powder mixture of ZnO and 5 mol% Pd (ZP-5) as reactants by ${\times}$ sccm oxygen pressures(x= 0, 10, 20, 40). DTA (differential thermal analysis) result shows the Pd(5 mol%)+ZnO mixtured powder(PZ-5) is easily evaporated than pure ZnO powder. The PZ-5 mixtured powder was characterized by DTA to determine the thermal decomposition which was found to be at $800^{\circ}C$, $1,100^{\circ}C$. Weight loss(%) and ICP (inductively coupled plasma) analysis reveal that Zn vaporization is decreased by increased oxygen pressures from the PZ-5 at $1,100^{\circ}C$ for 30 mins. Needle-like ZnO nanostructures array developed from 10 sccm oxygen pressure, was well aligned vertically on the Si substrate at $1,100^{\circ}C$ for 30 mins. The lengths of the Needle-like ZnO nanostructures is about 2 ${\mu}m$ with diameters of about 65 nm. The developed ZnO nanostructures exhibited growth direction along [001] with defect-free high crystallinity. It is considered that Zn vaporization is responsible for the growth of Needle-like ZnO nanostructures by controlling the oxygen pressures. The photoluminescence spectra of ZnO nanostructures exhibited stronger 376.7 nm NBE (near band-edge emission) peak and 529.3 nm DLE (deep level energy) peak.
바이몰프형 압전세라믹 캔틸레버를 이용한 수력에너지 하베스터 모듈 제작 및 발전 특성
김경범,김창일,윤지선,정영훈,남중희,조정호,백종후,남산,성태현,Kim, Kyoung-Bum,Kim, Chang-Il,Yun, Ji-Sun,Jeong, Young Hun,Nahm, Jung Hee,Cho, Jeong-Ho,Paik, Jong-Hoo,Nahm, Sahn,Seong, Tae-Hyeon 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.12
A new water energy harvester module, which is composed of piezoelectric bimorph cantilevers, harvesting circuit and a shaft with 16 impellers at a center axis, was fabricated for energy harvesting application. High energy density $Pb(Zr_{0.54}Ti_{0.46})O_3$ + 0.2 wt% $Cr_2O_3$ + 1.0 wt% $Nb_2O_5$ (PZT-CN) thick film obtained by tape casting method was used for the bimorph cantilever. The PZT-CN bimorph cantilever with a proof mass of 49 g exhibited extremely high output power of 22.5 mW (24 $mW//cm^3$) at resonance frequency of 11 Hz. In addition, the fabricated water energy harvester has a cylindrical structure with 48 bimorph cantilevers clamped at inner surface. A significantly high output power of 433 mW was obtained at a rotation speed of 120 rpm with a resistive load of $500{\Omega}$ for the water energy harvester.
김경범,김창일,윤지선,정영훈,남중희,조정호,백종후,남산,성태현,Kim, Kyoung-Bum,Kim, Chang-Il,Yun, Ji-Sun,Jeong, Young Hun,Nahm, Jung Hee,Cho, Jeong-Ho,Paik, Jong-Hoo,Nahm, Sahn,Seong, Tae-Hyeon 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.12
We fabricated piezoelectric unimorph cantilever generators (UCG) using $Pb(Zr_{0.54}Ti_{0.46})O_3$ + 0.2 wt% $Cr_2O_3$ + 1.0 wt% $Nb_2O_5$ (PZCN) piezoelectric thick films, which were produced by a tape casting method. The PZCN thick films were tailored with same width and thickness but different lengths from 7.7 to 57.7 mm in order to evaluate optimized UCG for energy harvesting device applications. When the length of PZCN film was increased, the resonance frequency of UCG was slightly increased from 7 Hz to 8 Hz, which could be due to enlarged area of the highly stiff piezo-ceramic film. However, the output power was proportionally increased with the length of PZCT film and it reached 4.68 mW (1.221 $mW/cm^3$) when the film's length was 57.7 mm under 25 g of tip mass at 8 Hz, which is sufficient for micro-scale device applications.
수열합성에 의한 c축 배향 ZnO 나노로드 배열의 성장과 구조, 광학적 특성
김경범,김창일,정영훈,이영진,백종후,Kim, Kyoung-Bum,Kim, Chang-Il,Jeong, Young-Hun,Lee, Young-Jin,Paik, Jong-Hoo 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.3
ZnO nanorods array have been grown on the seed crystal coated Si(100) substrate by hydrothermal method. The growth, structural and optical properties of ZnO nanorods array were investigated with a variation of precursor concentration from 0.01 M to 0.04 M. The array density of grown ZnO nanorods per same area was increased with increasing the concentration of precursor solution. Vertically aligned ZnO nanorods with hexagonal wurtzite structure have highly preferred c-axis orientation along (002) lattice plane. Especially, ZnO nanorods array developed from 0.04 M precursor solution showed a diameter of about 85 nm and length of 1.2 {\mu}m$ without any crystallographic defects. The photoluminescence spectra of ZnO nanorods from heavier precursor concentration exhibited stronger UV emission around 380 nm corresponding with near-band-edge emission.
김경범,김창일,정영훈,이영진,백종후,이우영,김대준,Kim, Kyoung-Bum,Kim, Chang-Il,Jeong, Young-Hun,Lee, Young-Jin,Paik, Jong-Hoo,Lee, Woo-Young,Kim, Dae-Joon 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.12
$(1-x)BaTiO_3-x(Bi_{0.5}Na_{0.5})TiO_3$ ($0.01{\leq}x{\leq}0.10$) ceramics were fabricated with muffled sintering by a modified synthesis process. Their positive temperature coefficient of resistivity (PTCR) characteristics were investigated systematically. All specimen showed a perovskite structure with a tetragonal symmetry. Both the lattice parameter of a and c axes were slightly decreased with increasing $(Bi_{0.5}Na_{0.5})TiO_3$ (BNT) content. Grain growth was achieved when the incorporated BNT was increased to 6 mol% and the inhibition of grain growth is considered to be due to the appearance of Ba vacancy ($V^{"}_{Ba}$) in the $(1-x)BaTiO_3-x(Bi_{0.5}Na_{0.5})TiO_3$ ($0.08{\leq}x$). With 4 mol% BNT addition, room temperature resistivity decreased to $48 \Omega{\cdot}cm$ and a resistivity jump ($\rho_{max}/\rho_{min}$) was as high as $1.1{\times}10^4$, respectively. Curie temperature was also increased to $171^{\circ}C$ with increasing BNT content.
압전 캔틸레버 스프링 구조물(SPCS)의 에너지 하베스팅 특성
김경범,김창일,정영훈,이영진,조정호,백종후,남산,성태현,Kim, Kyoung-Bum,Kim, Chang-Il,Jeong, Young-Hun,Lee, Young-Jin,Cho, Jeong-Ho,Paik, Jong-Hoo,Nahm, Sahn,Seong, Tae-Hyeon 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.10
Spring supported piezoelectric cantilever structures (SPCS) were fabricated for vibration-based energy harvester application. We selected four elastic springs (A, B, C, and D type) as cantilever's supporter, each elastic spring has a different spring constant (S). The C type of SPCS ($S_C$: 4,649 N/m) showed a extremely low resonance frequency of 81 Hz along with the highest power output of 38.5 mW while the A type of SPCS ($S_A$: 40,629 N/m) didn't show a resonance frequency while. Therefore, it is considered that the lower spring constant lead to a lower resonance frequency of the SPCS. In addition, a tip mass (18 g) at one end of the SPCS could further reduce the resonance frequency without heavy degradation of power output.
김경범(Kyoung-Bum Kim),임종빈(Jong-Bin Im),강동우(Dong-Woo Kang),고성철(Sung-Chul Go),이호준(Ho-Joon Lee),이주(Ju Lee) 한국철도학회 2009 한국철도학회 학술발표대회논문집 Vol.2009 No.11월
The switched reluctance motor(SRM) uses the reluctance torque and the rotor does not consist of the magnet and coil. The SRM has many advantages such as simple electromagnetic structure, robustness, high-efficiency, high-torque, and variable speed driving in a wide range. Therefore range of many applications is extended from home appliances to industrial machinery in lately. However, because of the switching mechanism, it has some disadvantage of noise and vibration. So the using SRM of home appliances is restricted. This paper is about reduction of torque ripple which is one of the reason of noise and vibration. Also, it deals with the important basic parameters of SRM design and analyzed torque ripple according to change shape of the pond by using the finite element method.
고속 스위치드 릴럭턴스 모터의 철손저감을 위한 최적 설계
김경범(Kyoung-Bum Kim),임종빈(Jong-Bin Im),조수연(Su-Yeon Cho),강동우(Dong-Woo Kang),이주(Ju Lee) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.4
In this paper, the single phase SRM of 45000rpm will be designed in more consideration of the elements that might be caused in case of the high speed than the single phase SRM of 40000rpm established previously. Furthermore, the methods for core loss reduction such as using a Stator form and a steel plate for the better efficiency will be presented.
대용량 LSM의 Thrust Force Ripple 저감을 위한 근사 최적 설계
김경범(Kyoung-Bum Kim),안한웅(Han-Woong Ahn),김상욱(Sang-Wook Kim),이주(Ju Lee) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.10
In this paper, the basic design of LSM(Linear Synchronous Motor) is performed. Designed LSM required an application of MPSS in order to reduce the Thrust Force Ripple. Therefore, the approximate optimization design was established additionally.