• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.617-618
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• 2006

A CMOS quadrature Up-converter for a direct-conversion receiver of 5.15-5.825GHz wireless LAN is described. The Up-converter consists of two sub-harmonic mixers, for I and Q channels, and an LO generation network. In order to decrease the number of inductor, I and Q path are merged. The simulation results including all the parasitics show -17.3dB conversion gain at center and -8 dBv oIP3 while consuming 22.968mW under 1.8V supply. The quadrature Up-converter is under fabrication with the other transmitter blocks in a $0.18{\mu}m$ CMOS technology.

• 대한화학회지
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• 제14권3호
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• pp.221-228
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• 1970

The tendency of forming a charge transfer complex between furfuryl derivatives (2-methyl furan, furfuryl acetate, and Ethyl 2-furoate) and halides(Iodine, Iodine monochloride, and Trichloro bromo methane) was studied by means of ultra violet spectrophotometry. In case of furfuryl acetate the formation of the complex could not be distinctly detected by this method. Iodine and trichloro bromo methane could show a distinct formation of charge transfer complex in the U.V. region, whereas iodine monochloride shows a possibility of forming an addition compound rather than the charge transfer complex itself. The results were discussed in conjunction with the stability of the furfuryl ring.

• 정보관리학회지
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• 제6권1호
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• pp.3-14
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• 1989

본 연구는 학술 잡지의 발달 과정과 그 특징, 연구 논문 편수의 증가와 학회의 발달 과를 고찰하므로서 우리나라 학자들의 논문 발표의 주된 수단이 무엇인지, 학술 정보의 생 산과 축적 수단으로서 학술 잡지의 기능을 밝히고 도서관 정보 봉사를 설계하거나 개선함에 있어 올바른 방향 설정에 도움이 될 객관적 근거를 마련하는데 그 목적이 있다.

• Design & Manufacturing
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• 제15권3호
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• pp.19-25
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• 2021

The bending process of a press die is to bend a flat blank to the required angle. There are V-bending, U-bending, Z-bending, O-bending etc. for bending processing, and the basic principle of calculating the unfolding length of die processing is used as the neutral plane length. Since the constant of the length value of the neutral surface is different depending on the type of bending, it is impossible to accurately calculate it. In particular, Z-bending processing is performed twice, and it is set on the upper and lower surfaces of the blank, and bending processing occurs at the same time as the upward and downward bending, and the elongation of the material occurs and the material increases. It is not possible to check with the calculated value, and it occurs in many cases where the mold is modified after start-up. This study aims to minimize die modification by developing a formula to calculate the development length of Z-bend.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.86.2-86.2
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• 2015

Cu2ZnSn(S,Se)4 thin film solar cells have been fabricated using sputtered Cu/Sn/Zn metallic precursors on Mo coated sodalime glass substrate without using a toxic H2Se and H2S atmosphere. Cu/Sn/Zn metallic precursors with various thicknesses were prepared using DC magnetron sputtering process at room temperature. As-deposited metallic precursors were sulfo-selenized inside a graphite box containing S and Se pellets using rapid thermal processing furnace at various sulfur to selenium (S/Se) compositional ratio. Thin film solar cells were fabricated after sulfo-selenization process using a 65 nm CdS buffer, a 40 nm intrinsic ZnO, a 400 nm Al doped ZnO, and Al/Ni top metal contact. Effects of sulfur to selenium (S/Se) compositional ratio on the microstructure, crystallinity, electrical properties, and cell efficiencies have been studied using X-ray diffraction, Raman spectroscopy, field emission scanning electron microscope, I-V measurement system, solar simulator, quantum efficiency measurement system, and time resolved photoluminescence spectrometer. Our fabricated Cu2ZnSn(S,Se)4 thin film solar cell shows the best conversion efficiency of 9.24 % (Voc : 454.6 mV, Jsc : 32.14 mA/cm2, FF : 63.29 %, and active area : 0.433 cm2), which is the highest efficiency among Cu2ZnSn(S,Se)4 thin film solar cells prepared using sputter deposited metallic precursors and without using a toxic H2Se gas. Details about other experimental results will be discussed during the presentation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.624-627
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• 2003

The BLT thin-films were one of the promising ferroelectric materials with a good leakage current and degradation behavior on Pt electrode. The BLT target was sintered at $1100^{\circ}C$ for 4 hours at the air ambient. $Bi_{3.25}La_{0.75}Ti_3O_{12}$ (BLT) thin-film deposited on $Pt/Ti/SIO_2/Si$ wafer by rf magnetron sputtering method. At annealed $700^{\circ}C$, (117) and (006) peaks appeared the high intensity. The hysteresis loop of the BLT thin films showed that the remanent polarization ($2Pr=Pr^+-Pr^-$) was $16uC/cm^2$ and leakage current density was $1.8{\times}10^{-9}A/cm^2$ at 50 kV/cm with coersive electric field when BLT thin-films were annealed at $700^{\circ}C$. Also, the thin film showed fatigue property at least up to $10^{10}$ switching bipolar pulse cycles under 7 V. Therefore, we induce access to optimum fabrication condition of memory device application by rf-magnetron sputtering method in this report.

• 한국미생물·생명공학회지
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• 제20권4호
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• pp.395-400
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• 1992

토양으로부터 cholesterol oxidase 생산성이 있는 균주를 분리하고, 이들 분리된 균주들로 부터 여러 단계의 균주 선발 실험을 통하여 cholesterol oxidase 생산성이 가장 우수한 미생물을 선별하여 HSL613이 라고 명명하였다. 이 HSL613은 $37^{\circ}C$에서 보다 $30^{\circ}C$에서 배양했을 때 더 높은 효소생산성을 나타내었고 배양시간이 경과함에 따라 pH가 높아지면서 효소생산이 증가하여, 144시간 배양하였을 때 pH는 8.5로 높아졌고 효소생산량도 가장 높았다. 균체량은 120 시간 배양하였을 때 가장 많았다. 본 실험에서 HSL613의 효소생산조건을 검토한 결과 최적 배지조성은 2.0% glucose, 2.0% yeast extract, 0.2% $K_2HP0_4$, 0.1% NaCl. 0.005% $CaCl_22H_2O, 0.001% $FeSO_47H_20$ 로 판명되었으며, $30^{\circ}C$에서 144시간 (6일때) 배양하였을 때 효소생성이 가장 많았고 (10.3U/ml), 종균의 접종량은 1.0%(v/v)일때가 가장 효소생성이 잘 되었다.

• 현장농수산연구지
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• 제14권1호
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• pp.181-193
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• 2012

1) LAE지역으로 강우량이 풍부하고 햇볕의 양이 많은 지역으로 토양산도는 마 재배에 이상적인 pH(H₂O)가 평균 6.40이다. 그러나 포장에 따라 편차가 심하게 나타나고 있어 재배 기술 보급이 시급한 실정이다. 2) 평균 pH(H₂O)는 6.4이지만, pH(KCL)가 3.9로 나타났다. 두 pH 차이가 2.5로 심한 양분부족 현상을 보이고 있다. 토양 EC는 0.18 mS/cm로 심각한 토양 수탈현상을 보이고 있다. 3) 토양의 산화환원전위 (ORP)는 393mV로 아주 이상적인 토양을 보이고 있다. 토양산도와 함께 산화환원전위(ORP)는 좋은 유기농 마를 만드는데 큰 역할을 하고 있다. 4) 마는 연중 양분(養分)을 흡수하고 있는데, 측정 결과는 전 항목에서 심한 양분의 부족현상을 보여 향후 유기물의 투입이 요구되고 있다. 그러나 전반적으로 토양은 심한 양분부족 현상을 보이며 부분적으로 심각한 토양 수탈현상을 보이고 있었다. 토양영양에 대한 조사 연구가 지속가능한 유기농 마를 생산할 수 있는 기반임을 인식하는 계기가 되었다.

• 농약과학회지
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• 제2권1호
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• pp.46-52
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• 1998

[ $45^{\circ}C$ ]의 15%(v/v) dioxane 수용액중에서 살충성 buprofezin(IUPAC : tert-butylimino-3-iso-propyl-5-phenylperhydro-1,3,5-thiadiazin-4-one)의 가수분해 반응속도상수와 pka상수(5.60)를 측정하고 pH-효과, 용매효과(m=0.34, n=2.45 및 $1{\gg}m$), 열역학적 활성화 파라미터(pH 4.0, ${\Delta}H^{\neq}$= 11.12 $kcal{\cdot}mol^{-1}$, ${\Delta}S^{\neq}$=-5.0e.u. 및 $E_{act.}$=11.76Kcal), 반응 속도식등의 반응 속도론적 및 생성물분석(1-isopropyl-3-phenyl urea) 등의 비속도론적 실험결과를 얻었다. 이들 자료의 검토로부터 pH 8.0이하의 산성용액에서는 특정($k_{H3O+}$)및 일반 산-촉매반응에 의한 $A-S_{E}2$형 및 A-2(또는 $A_{AC}2$)형 반응, 그리고 pH 9.0이상의 알카리성 용액에서는 일반염기 촉매반응($k_{H2O}$)에 의한 친핵성 첨가-제거 ($Ad_{N}-E$) 반응이 사면체($sp^{3}$) 중간체를 경유하는 궤도-조절 반응으로 진행되는 일련의 가수분해 반응메카니즘을 제안하였다. 또한, Buprofezin은 산성(pH8.0이하)용액보다 염기성(pH8.0이상) 용액중($k=10^{-8}sec.^{-1}$)에서 더욱 안정하였으며 $45^{\circ}C$의 중성(pH 7.0) 수용액 중에서 반감기($t=\frac{1}{2}$)는 약 3개월이었다.

• The Journal of Advanced Prosthodontics
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• 제12권4호
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• pp.189-196
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• 2020

PURPOSE. The aim of the present study was to investigate the effects of surface treatments on the bond strengths between polymer-containing restorative materials and two dual-cure resin cements. MATERIALS AND METHODS. In the present study, rectangular samples prepared from Lava Ultimate (LU) and Vita Enamic (VE) blocks were used. The specimen surfaces were treated using CoJet sandblasting, 50 ㎛ Al₂O₃ sandblasting, % 9 HF (hydrofluoric) acid, ER,Cr:YSGG laser treatment, and Z-Prime. Dual-cure resin cements (TheraCem and 3M RelyX U 200) were applied on each specimen's treated surface. A micro-tensile device was used to evaluate shear bond strength. Statistical analysis was performed using the SAS 9.4v3. RESULTS. While the bond strength using TheraCem with LU or VE was not statistically significant (P=.164), the bond strength using U200 with VE was statistically significant (P=.006). In the TheraCem applied VE groups, Z-Prime and HF acid were statistically different from CoJet, Laser, and Sandblast groups. In comparison of TheraCem used LU group, there was a statistically significant difference between HF acid and other surface treatments. CONCLUSION. The bonding performance between the restorative materials and cements were material type-dependent and surface treatment had a large effect on the bond strength. Within the limitations of the study, the use of both U200 and TheraCem may be suggested if Z-prime was applied to intaglio surfaces of VE. The cementation of LU using TheraCem is suitable after HF acid conditioning of the restoration surfaces.