• 대한수학회지
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• 제57권6호
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• pp.1435-1449
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• 2020

In this article we make a local classification of n-dimensional Riemannian manifolds (M, g) with harmonic curvature and less than four Ricci eigenvalues which admit a smooth non constant solution f to the following equation $$(1)\hspace{20}{\nabla}df=f(r-{\frac{R}{n-1}}g)+x{\cdot} r+y(R)g,$$ where ∇ is the Levi-Civita connection of g, r is the Ricci tensor of g, x is a constant and y(R) a function of the scalar curvature R. Indeed, we showed that, in a neighborhood V of each point in some open dense subset of M, either (i) or (ii) below holds; (i) (V, g, f + x) is a static space and isometric to a domain in the Riemannian product of an Einstein manifold N and a static space (W, gW, f + x), where gW is a warped product metric of an interval and an Einstein manifold. (ii) (V, g) is isometric to a domain in the warped product of an interval and an Einstein manifold. For the proof we use eigenvalue analysis based on the Codazzi tensor properties of the Ricci tensor.

• 한국세라믹학회지
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• 제37권6호
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• pp.552-558
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• 2000

LiMn2O4 thin fiolm cathodes for Li-ion secondary battery were fabricated by r.f. magnetron sputtering technique. As-deposited films were amorphous. A spinel structure could not be obtained LiMn2O4 films by in-situ thermal annealing. After post thermal annealing over $700^{\circ}C$ in oxygen atmosphere, LiMn2O4 films prepared above 100 W r.f. power could be crystallized into a spinel structure. The electrochemical property of the LiMn2O4 film cathodes was tested in a Li/1 M LiClO4 in PC/LiMn2O4 cell. From cyclic voltammetry at scan rate of 2mV/sec of 2.5~4.5V, LiMn2O4 electrode prepared by post annealing at 75$0^{\circ}C$ showed good initial capacity. LiMn2O4 electrode prepared by post annealing at 80$0^{\circ}C$ showed the best crycling performance.

• 한국광학회지
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• 제6권3호
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• pp.201-213
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• 1995

전자빔여기 XeF$(C\rightarrowA$ 엑시며 레이저의 상준위 B-와 C-상태에 대하여 충동혼합 운동과정을 포함하는 모델을 컴퓨터 시뮬레이션하여 이의 출력특성을 해석하였다 $XeF^*(B)$ 의 수밀도에 관련되는 $XeF^*(C)$의 형성에 대하여 레이저 에너지를 실험치와 비교하였다. 이 결과는 70ns[FWHM]의 전자빔(800kV, 21kA)을 사용한 대기압 매질에서 매우 좋은 일치$(28.5 mJ\pm5%)$를 보였고, $Xe/F_2/Ar=5.26/0.49/94.28%$의 최적화된 가스혼합비를 확인하였다. 또한 시뮬레이션으로 $XeF^*(C)$의 형성경로, $XeF^*(C)$의 완화경로, 청록색 파장대역의 흡수경로에 대한 $F_2$ 할로겐 도우너 및 Xe 압력의 함수관계를 조사하였다.

• 전자공학회논문지D
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• 제36D권10호
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• pp.31-36
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• 1999

질소 화합물의 새로운 형광체를 개발하기 위하여 $CaSiN_2:Eu,\;CaSiN_2:Tb$ 형광체를 합성한 후, 빛 발광 (photoluminescence, PL) 및 전계 발광(electroluminescence, EL) 특성을 평가하였다. $Ca_3N_2$, $Si_3N_4$ 및 $EuF_3$ 또는 $TbF_3$의 미분말을 혼합, 성형 및 소결하여 질소 화합물 형광체를 합성하였다. 합성된 $CaSiN_2:Eu,\;CaSiN_2:Tb$ 형광체의 PL 특성이 각각 Eu, Tb 이온에 의한 고유한 발광 파장과 일치하여 형광체로의 활용 가능성을 확인하였다. 스퍼터링 방법으로 제작된 $CaSiN_2:Eu$ 박막 전계 발광(thin-film electroluminescence, TFEL) 소자의 문턱 전압과 280 V에서의 발광 휘도는 각각 90 V, 1.62 $cd/m^2$ 임을 알 수 있었다. 또한 change-voltage(Q-V) 및 transferred charge-phosphor Field($Q_t-F_p$)의 전기적 특성도 함께 측정되었다.

• Parasites, Hosts and Diseases
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• 제58권6호
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• pp.709-714
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• 2020

Knockdown resistance (kdr) mutations in the voltage-gated sodium channel (VGSC) of mosquitoes confer resistance to insecticides. Although insecticide resistance has been suspected to be widespread in the natural population of Aedes aegypti in Myanmar, only limited information is currently available. The overall prevalence and distribution of kdr mutations was analyzed in Ae. aegypti from Mandalay areas, Myanmar. Sequence analysis of the VGSC in Ae. aegypti from Myanmar revealed amino acid mutations at 13 and 11 positions in domains II and III of VGSC, respectively. High frequencies of S989P (68.6%), V1016G (73.5%), and F1534C (40.1%) were found in domains II and III. T1520I was also found, but the frequency was low (8.1%). The frequency of S989P/V1016G was high (55.0%), and the frequencies of V1016G/F1534C and S989P/V1016G/F1534C were also high at 30.1% and 23.5%, respectively. Novel mutations in domain II (L963Q, M976I, V977A, M994T, L995F, V996M/A, D998N, V999A, N1013D, and F1020S) and domain III (K1514R, Y1523H, V1529A, F1534L, F1537S, V1546A, F1551S, G1581D, and K1584R) were also identified. These results collectively suggest that high frequencies of kdr mutations were identified in Myanmar Ae. aegypti, indicating a high level of insecticide resistance.

• Bulletin of the Korean Chemical Society
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• 제35권10호
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• pp.2963-2968
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• 2014

We report synthesis and photovoltaic properties of two new conjugated copolymers, PCPDTQxF and PDTSQxF, with 6,7-difluoro-2,3-dihexylquinoxaline unit prepared by Stille coupling reaction. The advantage of 6,7-difluoro-2,3-dihexylquinoxaline based copolymer are high PCEs due to lower HOMO energy level, long wavelength absorption and high hole mobility. The solid films of PCPDTQxF and PDTSQxF showed absorption bands with maximum peaks at about 623 and 493 nm and the absorption onsets at 711 and 635 nm, corresponding to band gaps of 1.74 and 1.95 eV, respectively. The oxidation onsets of the PCPDTQxF and PDTSQxF polymers were estimated to be 0.68 and 0.95 V, which correspond to HOMO energy levels of -5.48 and -5.75 eV, respectively. The PDTSQxF has lower HOMO energy level as compared to PCPDTQxF to lead higher $V_{OC}$ value. The device comprising PCPDTQxF:PCBM (1:2) dissolved to a concentration of 1 wt % in ODCB showed $V_{OC}$ value of 0.62 V, $J_{SC}$ value of $1.14mA/cm^2$, and FF of 0.35, which yielded PCE of 0.25%.

• 수산해양기술연구
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• 제31권1호
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• pp.29-44
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• 1995

A model experiment on the pair midwater trawl net applicable to 800 PS class Korean pair bottom trawlers was carried out in the special-prepared experimental thank. the tank was prepared as a reverse trapezoid shape in its vertical section by digging out flat soil. The dimension of the tank showed the 9.6 W$\times$43.0 L(m) of the upper fringe and the 4.8 W$\times$38.0 L(m) of the bottom with 3.0m in depth. The depth of water was maintained 2.7m during experiment. The model net was prepared based on the Tauti's similarity law of fishing gear in 1/30 scale considering the dimension of the experimental tank. Mouth performance of the model net during towing were determined by the photographs taken in front of the net mouth with the combinations of towing velocity, warp length and distance between paired boats. The results obtained can be summarized as follows: 1. Vertical opening of the model nets A and B was varied in the range of 0.18~0.88 m and 0.21~0.78 m (which can be converted into 5.4~26.4m and 6.3~23.4 m in the full-scale net) respectively, and was varied predominantly by towing speed. Vertical opening (H which is appendixed m for the model net. f for the full-scale net. A and B for the types of the model net) can be expressed as the function of towing velocity$V_t$as in the model net $V_t$ : m/ sec)$H_{mA}$=1.67$e^{-1.65V_t}$ $H_{mB}$=1.15$e^{-1.13V_t}$, in the full-scale net ($V_t$ : k't) $H_{fA}$=50.27$e^-0.37V_t$ $H_{fB}$=34.46$e^{-0.26Vt}$. 2. Horizontal opening of the model nets An and b was varied in the range of 1.03~1.54m and 1.04~1.55 m (which can be converted into 30.9~46.2 m and 31.2~46.5m in the full-scale net) respectively, and was varied predominantly by distance between paired boats. Horizontal opening (W, appendixes are as same as the former) an be expressed as the function of distance between paired boats $D_b$as in the model net $W_{mA}$=0.69+0.09$D_b$ $W{mB}$=0.73+0.09$D_b$, in the full-scale net $W_{fA}$=20.81+0.09$D_b$ $W_{fB}$=22.11+0.09$D_b$ 3. Net opening area of the model net A and B was varied in the range of 0.28~1.04 $m^2$ and 0.33~0.94$m^2$(which can be converted into 252~936$m^2$ and 297~846$m^2$ in the full-scale net) respectively, and was varied predominantly by towing velocity. Net opening area ($S$, appendixes are as same as the former) van be expressed as the function of towing velocity$V_t$ as in the model net $v_t$ : m/sec) $S_{Ma}$=2.01$e^{-1.54V_T}$ $S_{mA}$=1.40$e^{-1.65V_t}$, in the full-scale net ($V_t$ : k't) $S_{fA}$=1.807$e^-0.35V_t$ $S_{fA}$=1.265$e^{-0.24V_t}$. 4. Filtering volume of the model nets A and B was varied in the range of 0.32~0.55 $m^3$ and 0.37~0.55$m^3$(which can be converted into 8.640~14.850 $m^3$ and 9.990~14.850$m3$in the full~scale net) respectively, and was predominantly varied by towing speed. filtering volume of the model net-A showed the maximum at the towing speed 0.69 m/sec(3 k't in the full-scale net), compared with that of the model net B showed at 0.92 m/sec(4 k't in the full-scale net).

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.303-304
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• 2009

We fabricated organic field-effect transistors (OFETs) based a fluorinated copper phthalocyanine. ($F_{16}CuPc$) as an active layer. And we observed the surface morphology of the $F_{16}CuPc$ thin film. The $F_{16}CuPc$ thin film thickness was 40nm, and the channel length was $50{\mu}m$, channel width was 3mm. We observed the typical current-voltage (I-V) characteristics and capacitance-voltage (C-V) in $F_{16}CuPc$ FET and we calculated the effective mobility.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.389-390
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• 2008

We fabricated organic field-effect transistors (OFETs) based a fluorinated copper phthalocyanine ($F_{16}CuPc$) as an active layer. And we observed the surface morphology of the $F_{16}CuPc$ thin film. The $F_{16}CuPc$ thin film thickness was 40nm, and the channel length was $50{\mu}m$, channel width was 3mm. We observed the typical current-voltage (I-V) characteristics and capacitance-voltage (C-V) in $F_{16}CuPc$ FET and we calculated the effective mobility.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 춘계학술대회 논문집
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• pp.43-44
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• 2009

We fabricated organic field-effect transistors (OFETs) based a fluorinated copper phthalocyanine ($F_{16}CuPc$) as an active layer. And we observed the surface morphology of the $F_{16}CuPc$ thin film. The $F_{16}CuPc$ thin film thickness was 40nm, and the channel length was $50{\mu}m$, channel width was 3mm. We observed the typical current-voltage (I-V) characteristics and capacitance-voltage (C-V) in $F_{16}CuPc$ FET and we calculated the effective mobility.