• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1542-1543
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• 2007

This paper presents the effect of driving waveform for piezoelectric bend mode inkjet printhead with optimized mechanical design. Experimental and theoretical studies on the applied driving waveform versus jetting characteristics were performed. The inkjet head has been designed to maximize the droplet velocity, minimize voltage response of the actuator and optimize the firing frequency to eject ink droplet. The head design was carried out by using mechanical simulation. The printhead has been fabricated with Si(100) and SOI wafers by MEMS process and silicon direct bonding method. To investigate how performance of the piezoelectric ceramic actuator influences on droplet diameter and droplet velocity, the method of stroboscopy was used. Using the water based ink of viscosity of 11.8 cps and surface tension of 0.025N/m, it is possible to eject stable droplets through 64 nozzles average velocity of 4.05 m/s with standard deviation of 0.06 m/s and average diameter of $29.2\;{\mu}m$ with standard variation of $0.5\;{\mu}m$.

• 한국전기전자재료학회논문지
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• 제28권11호
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• pp.690-693
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• 2015

In this paper, in order to develop excellent Pb-free composition ceramics for ultrasonic sensor. The $SnO_2$-doped ($Na_{0.525}K_{0.443}Li_{0.037})(Nb_{0.883}Sb_{0.08}Ta_{0.037})O_3$)(abbreviated as NKL-NST) ceramics have been synthesized using the ordinary solid state reaction method. The effect of $SnO_2$-doping on their dielectric and piezoelectric properties was investigated. The ceramics doped with 0 wt% $SnO_2$ have the optimum values of piezoelectric constant($d_{33}$), piezoelectric figure of merit($d_{33}.g_{33}$), planar piezoelectric coupling coefficient($k_p$) and density : $d_{33}=195[pC/N]$, $d_{33}.g_{33}=5.62pm^2/N.kp=0.40$, $density=4.436[g/cm^3]$. suitable for duplex ultrasonic sensor application.

• 대한조선학회지
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• 제21권1호
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• pp.35-42
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• 1984

In the present study, rotating bending fatigue tests have been carried out in three kinds of carbon steel specimens; an annealed low carbon steel, an annealed high carbon steel and quenched-tempered high carbon steel; with a small artificial surface defect that might exist in real structures. Fatigue crack lengths have been observed by a method of replication in order to investigate the growth characteristic of fatigue crack in the viewpoints of strength of materials and fracture mechanics. The main results obtained are as follows: 1) The effect of a small surface defect upon the reduction of fatigue limit is considerably large, and the rate of fatigue limit reduction grows in the following order; annealed low carbon steel(mild steel), annealed high carbon steel, quenched-tempered high carbon steel. 2) When the growth rate of surface crack length(2a) was investigated in the viewpoints of fracture mechanics based upon $ ${\Delta}K_{\varepsilon}$, the dependence of stress level and of surface defect size disappear, and there exists a linear relationships between d(2a)/dN and ${\Delta}K_{{\varepsilon}t},\;\Delta_{{\varepsilon}t}\sqrt{{\pi}a}$, on log. plot, i.e, $d(2a)/dN={C{\cdot}{\Delta}K_{\varepsilon}}^3_t$, where ${\Delta}_{{\varepsilon}t}\sqrt{{\pi}a}$ a is the cyclic total strain intensity factor range.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 ICEIC The International Conference on Electronics Informations and Communications
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• pp.343-347
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• 2004

High oxidation temperature of SiC shows a tendency of carbide formation at the interface which results in poor MOSFET transfer characteristics. Thus we developed oxidation processes in order to get low interface charge densities. N-type 6H-SiC MOS capacitors were fabricated by different oxidation processes: dry, wet, and dry­reoxidation. Gate oxidation and Ar anneal temperature was $1150^{\circ}C.$ Ar annealing was performed after gate oxidation for 30 minutes. Dry-reoxidation condition was $950^{\circ}C,$ H2O ambient for 2 hours. Gate oxide thickness of dry, wet and dry-reoxidation samples were 38.0 nm, 38.7 nm, 38.5 nm, respectively. Mo was adopted for gate electrode. To investigate quality of these gate oxide films, high frequency C- V measurement, gate oxide leakage current, and interface trapped charge densities (Dit) were measured. The interface trapped charge densities (Dit) measured by conductance method was about $4\times10^{10}[cm^{-1}eV^{-1}]$ for dry and wet oxidation, the lowest ever reported, and $1\times10^{11}[cm^{-1}eV^{-1}]$ for dry-reoxidation

• 분석과학
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• 제19권5호
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• pp.415-421
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• 2006

채소류 및 과일류 중 PAHs 분석방법을 확립하고 오염실태 파악을 위하여 서울, 춘천, 대전, 광주, 부산의 5대 도시 시장에서 채소류 13종, 과일류 5종 총 210건을 채취하였다. 균질화된 시료를 dichloromethane으로 초음파추출하고 탈수한 후 Sep-Pak Florisil Cartridge로 정제하여 HPLC/FLD로 동시 정량 분석하였다. 시료에 표준물질을 spike하여 전처리 후 기기분석한 결과, 각각의 PAH에 대한 회수율은 약 95~102%였으며, 검출한계는 PAH에 따라 차이는 있으나 0.002~0.5 ng/g 수준이었다. 채소류 및 과일류 중 8가지 총 PAHs의 평균 함량은 0.19 ng/g이었으며 개별 평균 PAH 함량은 benzo(a)anthracene 불검출, chrysene 0.014 ng/g, benzo(b)fluoranthene 0.031 ng/g, benzo(k)fluoranthene 0.016 ng/g, benzo(a)pyrene 0.019 ng/g, dibenzo(a,h)anthracene 0.091 ng/g, benzo(g,h,i)perylene 0.016 ng/g, indeno(1,2,3-c,d)pyrene 불검출 수준이었다.

• 공업화학
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• 제7권2호
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• pp.221-227
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• 1996

N-아실 아미노산계 음이온성계면활성제 중 sodium N-acyl-N-methyl-${\beta}$-alaninate, sodium N-acyl sarcosinate 그리고 sodium N-acyl-N-methyl taurate 유도체 12종을 선택하여 묽은 수용액내에서 임계미셀농도와 미셀화 영역을 결정하는 새로운 방법으로서 컴퓨터프로그래밍에 의한 표면장력 곡선의 최대화를 제안하였다. 임계미셀농도와 미셀화 영역은 몇몇 실험치를 직접 프로그램에 대입함으로써 곡선의 최대화에 의해서 이론적으로 산정할 수 있다. 이론적으로 구한 임계미셀농도값들은 실측치와 거의 일치함을 알 수 있다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1010-1013
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• 2006

To understand the exact charge carrier photogeneration properties of photoactive thin films consisting of a ${\pi}-conjugated$ polymer matrix and a triplet dopant, we prepared two types of polymer, poly(9-vinylcarbazole) (PVK) and poly[9,9-bis(2- ethylhexyl)fluorene-2,7-diyl] (PF2/6) doped with triplet emitters for organic light-emitting diodes (OLED), either iridium(III)fac-tris(2-phenylpyridine) $(Ir(ppy)_3)$ or iridium(III)bis[(4,6-fluorophenyl)- $pyridinato-N,C^2'$]picolinate (FIrpic), as thin film devices by using the conventional method. Those doped film devices, as well as pristine film devices, on ITO substrates were characterized by means of steady state photocurrent measurement for a wide spectral range.

• 생약학회지
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• 제2권1호
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• pp.39-40
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• 1971

An alkaloidal component was extracted from the root of Aconitum koreanum R. $R_{AYMOND}$ of the commercial origin. Crude extract was obtained in ca. 2% yield out of dried root with ether-methanol (10:1). White amorphous compound was precipitated out from the HCl solution upon the addition of ammonia water, and crude base was obtained by extraction of its mother liquid with chloroform. This crude base was purified by the alumina-column chromatographic method. A pure alkaloidal component(500mg) was yielded from its crude base. Its pure base comes as needle crystals melting at $250{\sim}252^{\circ}C$ (decomp.), $[\alpha]^{20}_D$ D+9.82 (methanol) and Anal. calcd. for $C_{19}H_{27}O_{8}N$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1882-1884
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• 2003

This paper introduced the characteristics of fiber-optic Mach-Zehnder interferometer to detect ultrasonic waves by discharges in oil. Noise-reduction method with wavelet and frequency-domain analysis was performed.

• 한국결정학회지
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• 제15권2호
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• pp.74-77
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• 2004

Dinitroethylenediaminepalladium(II), $Pd(C_2H_8N_2)\;(NO_2)_2$의 결정구조는 a=7.425(3), b=8.480(4), c=11.885(2)${\AA}$, 사방정계(Orthorhombic), 공간군 $A2_1ma$, 공간군 번호 36이며, Z=4, V=748.3(4)${\AA}^3,\;D_c=2.295\;gcm^{-3},\;{\mu}=2.457mm^{-1}$이었다. 구조분석은 중금속법으로 풀었으며, 최소 자승법으로 정밀화하였고, 최종 신뢰도 값들은 377개의 회절반점에 대하여 $(R_1=0.0306,\;R_w=0.0802,\;R_{all}=0.0320,\;S=1.166)$이었다. 최종 분석한 착염의 결합거리와 각들은 기존에 알려진 해당 자료들에 상응하였다. 착염의 구조는 Reiset's salt type 유사체와 같은 일차원 구조로써 c축을 따라서, Pd-Pd 거리가 3.762(2) $(\AA)$이고, 각 $161.41(5)^{\circ}$인 지그재그 사슬구조를 형성하고 있다. 사슬내에서나 사슬간에는 질소와 산소사이에 각각 3.05(1)과 3.15(1) ${\AA}$인 수소결합으로 연결되어 있다.