• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.387-388
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• 2008

In this paper, we have designed and fabricated hyperabrupt varactor diodes. Capacitance variations of hyperabrupt-doped varactor diodes are larger than those of uniform-doped varactor diodes. The measured reverse breakdown voltage of the fabricated varactor diodes was about 20 V. For the anode contact diameter of $50\;{\mu}m$, the maximum capacitance of the fabricated varactor diode was 2.1 pF and the minimum capacitance 0.44 pF. Therefore, the $C_{max}/C_{min}$ ratio was 4.77. Also, for the anode contact diameter of $60\;{\mu}m$, the maximum and minimum capacitances were 2.9 and 0.62 pF, respectively. And, thus, the $C_{max}/C_{min}$ ratio was 4.64.

• 자원환경지질
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• 제4권4호
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• pp.225-234
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• 1971

With the advance of civilization and steadily increasing population rivalry and competition for the use of the sewage, culverts, farm irrigation and control of various types of flood discharge have developed and will be come more and more keen in the future. The author has tried to calculated a formula that could adjust these conflicts and bring about proper solutions for many problems arising in connection with these conditions. The purpose of this study is to find out effective sewage, culvert, drainage, farm irrigation, flood discharge and other engineering needs in the Taegu area. If demands expand further a new formula will have to be calculated. For the above the author estimated methods of control for the probable expected rainfall using a formula based on data collected over a long period of time. The formula is determined on the basis of the maximum daily rainfall data from 1921 to 1971 in the Taegu area. 1. Iwai methods shows a highly significant correlation among the variations of Hazen, Thomas, Gumbel methods and logarithmic normal distribution. 2. This study obtained the following major formula: ${\log}(x-2.6)=0.241{\xi}+1.92049{\cdots}{\cdots}$(I.M) by using the relation $F(x)=\frac{1}{\sqrt{\pi}}{\int}_{-{\infty}}^{\xi}e^{-{\xi}^2}d{\xi}$. ${\xi}=a{\log}_{10}\(\frac{x+b}{x_0+b}\)$ ($-b<x<{\infty}$) ${\log}(x_0+b)=2.0448$ $\frac{1}{a}=\sqrt{\frac{2N}{N-1}}S_x=0.1954$. $b=\frac{1}{m}\sum\limits_{i=1}^{m}b_s=-2.6$ $S_x=\sqrt{\frac{1}{N}\sum\limits^N_{i=1}\{{\log}(x_i+b)\}^2-\{{\log}(x_0+b)\}^2}=0.169$ This formule may be advantageously applicable to the estimation of flood discharge, sewage, culverts and drainage in the Taegu area. Notation for general terms has been denoted by the following. Other notations for general terms was used as needed. $W_{(x)}$ : probability of occurranec, $W_{(x)}=\int_{x}^{\infty}f_{(n)}dx$ $S_{(x)}$ : probability of noneoccurrance. $S_{(x)}=\int_{-\infty}^{x}f_(x)dx=1-W_{(x)}$ T : Return period $T=\frac{1}{nW_{(x)}}$ or $T=\frac{1}{nS_{(x)}}$ $W_n$ : Hazen plot $W_n=\frac{2n-1}{2N}$ $F_n=1-W_x=1-\(\frac{2n-1}{2N}\)$ n : Number of observation (annual maximum series) P : Probability $P=\frac{N!}{{t!}(N-t)}F{_i}^{N-t}(1-F_i)^t$ $F_n$ : Thomas plot $F_n=\(1-\frac{n}{N+1}\)$ N : Total number of sample size $X_l$ : $X_s$ : maximum, minumum value of total number of sample size.

• 설비공학논문집
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• 제1권3호
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• pp.244-251
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• 1989

A numerical study has been performed on the natural convection heat transfer from a conducting tube with two axial fins to a surrounding cylinder. As increasing dimensionless fin length ($L_F$), the center of flow moves to the bottom of annulus and the recirculating flow rate is decreased. The maximum local Nusselt number of conducting tube appears at ${\theta}=180^{\circ}$ for $L_F=0.0$, but at ${\theta}=130^{\circ}$ for $L_F{\geq}0.3$ and that of outer cylinder appears at ${\theta}=13^{\circ}$ for $L_F{\leq}0.6$ but at ${\theta}=33^{\circ}$ for $L_F=1.0$. The fin temperature is decreased by increasing radial distance and the temperature distribution of the downward fin is generally less than that of the upward fin. By increasing fin length, the local Nusselt number of the upward fin appears negative values for $L_F=1.0$, but appears positive values for $L_F<0.8$, and that of the downward fin appears positive values.

• 대한물리의학회지
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• 제4권4호
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• pp.275-280
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• 2009

Purpose：We have investigated to analysis biomechanics for pinch strength due to elbow flexion degree. Methods：Pinch strength was measured by Electro Dynamometer(G-100) using four elbow flexion degree ($0^{\circ}$, $45^{\circ}$, $90^{\circ}$, $135^{\circ}$). Results：In experimental results, we found that pinch strengths were 5.4kg($0^{\circ}$), 4.8kg($45^{\circ}$), 5.6kg($90^{\circ}$) and 5.2kg($135^{\circ}$), respectively. The Pinch strengths got maximum at $90^{\circ}$ degree, minimum at $45^{\circ}$ degree. We have calculated F1 values using $\sum$T=0. As a result F1 values were 540N($0^{\circ}$), 480N($45^{\circ}$), 560N($90^{\circ}$) and 520N($135^{\circ}$), respectively. F1 values got maximum at $90^{\circ}$ degree, minimum at $45^{\circ}$ degree. Data curve line of $F_1$ values was increased in 45~90 section and decreased in 0~45, 90~135 sections, respectively. Conclusion：$F_1$ (Flexor digitorum superficialis and profundus) values were 10 times bigger than pinch strengths. Data curve line of $F_1$ values was similar to active length-tension curve in 45~90, 90~135 sections.

• Bulletin of the Korean Chemical Society
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• 제29권1호
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• pp.139-147
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• 2008

New PPV derivatives which contain electron-withdrawing CF3F4phenyl group, poly[2-(2-ethylhexyloxy)-5-(2,3,5,6-tetrafluoro-4-trifluoromethylphenyl)-1,4-phenylenevinylene] (CF3F4P-PPV), and poly[2-(4-(2-etylhexyloxy)-phenyl)-5-(2,3,5,6-tetrafluoro-4-trifluoromethylphenyl)-1,4-phenylenevinylene] (P-CF3F4P-PPV), have been synthesized by GILCH polymerization. As the result of the introduction of the electron-withdrawing CF3F4phenyl group to the phenyl backbone, the LUMO and HOMO energy levels of CF3F4P-PPV (3.14, 5.50 eV) and P-CF3F4P-PPV (3.07, 5.60 eV) were reduced. The PL emission spectra in solid thin film are more red-shifted over 50 nm and increased fwhm (full width at half maximum) than solution conditions by raising aggregation among polymer backbone due to electron withdrawing effect of 2,3,5,6-tetrafluoro-4-trifluoromethylphenyl group. The EL emission maxima of CF3F4P-PPV and P-CF3F4P-PPV appear at around 530-543 nm. The current density-voltage-luminescence (J-V-L) characteristics of ITO/PEDOT/polymer/Al devices of CF3F4P-PPV and P-CF3F4P-PPV show that turn-on voltages are around 12.5 and 7.0 V, and the maximum brightness are about 82 and 598 cd/m2, respectively. The maximum EL efficiency of P-CF3F4P-PPV (0.51 cd/A) was higher than that of CF3F4P-PPV (0.025 cd/A).

• Journal of Microbiology and Biotechnology
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• 제14권6호
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• pp.1129-1133
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• 2004

The effects of Pluronic F-68, a non-ionic surfactant, on the growth and physical characteristics of Digitalis lanata suspension cultures were investigated in aqueous two-phase systems (ATPSs) composed of $4.5\%$ polyethylene glycol (PEG) 20,000 and $2.8\%$ crude dextran. In the range of 0.1-10.0 g $1^{-1}$, Pluronic F-68 enhanced the maximum cell density in a medium with ATPSs, even though Pluronic F-68 did not affect cell growth in a normal growth medium. In terms of physical properties of ATPSs with cell suspension cultures, 0.2 g $1^{-1}$ of Pluronic F-68 reduced viscosity by up to $40\%$, while 0.1 g $1^{-1}$ of Pluronic F-68 significantly enhanced the oxygen transfer rate. In addition, we successfully performed aqueous two-phase cultivation in a 5-1 stirred tank bioreactor with 0.5 g $1^{-1}$ of Pluronic F-68, and discovered that cell growth in ATPSs was similar to that in normal growth medium.

• 한국식품영양과학회지
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• 제41권11호
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• pp.1619-1625
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• 2012

김장김치를 김치냉장고에서 6개월간 '숙성 후 저장'과 '저온 저장' 모드에서 저장하였을 때 발효 양상을 비교해 보았다. 본 연구에 사용한 '숙성 후 저장' 모드에 보관한 김치는 $10^{\circ}C$에서 5일간 발효시킨 후 $-2.5^{\circ}C$에 저장한 F1김치, $15^{\circ}C$에서 1일 발효시킨 후 $-2.5^{\circ}C$에서 저장한 F2김치이고, '저온 저장'에 보관한 김치는 담금 즉시 $-1^{\circ}C$에 저장한 S1김치와 $-2.5^{\circ}C$에 저장한 F2김치 4종류이다. '숙성 후 저장'한 F1김치는 2주에 pH 4.4, 그리고 산도는 0.6%로 숙성기에 접어들었으나 F2김치는 8주, '저온 저장'한 S1김치는 12주에 그리고 S2김치는 저장 말기에 숙성기로 접어들었다. Lactobacillus spp. 생육은 F1 및 F2김치에서는 저장 초기부터 급속히 증식하여 8주에 최대 균수인 8.0~9.0 log CFU/mL에 도달한 후 F1김치에서는 균수가 6개월간 지속된 반면, F2김치에서는 저장 12주 이후 감소하였다. S1과 S2김치에서는 8주에 최대 균수인 6.8 log CFU/mL에 도달하여 적숙기 최대 균수에 미치지 못하였다. Leuconostoc spp.는 저장모드에 따라 최대 생육 시점은 다르나 8.0~9.0 log CFU/mL에 도달하였다. F1김치의 Leuconostoc spp.는 6개월 동안 지속적으로 성장하여 최대 생육에 도달한 반면, 다른 김치 시료에서는 최대 생육 후 균이 감소하였다. 고온 젖산균인 Lactobacillus spp.의 생육은 '저온 저장'한 김치에서 억제되었으나 Leuconostoc spp.의 생육은 $-2.5^{\circ}C$와 같이 낮은 온도에서도 최대 생육을 하였다. 김장김치의 관능은 저장 3개월까지 외관, 신맛, 탄산미, 아삭아삭함에서 F1김치가 가장 높은 평가를 받았는데 이는 Lactobacillus spp.와 Leuconostoc spp.의 균수가 가장 높았기 때문으로 생각된다. 6개월 후에는 F1와 S1김치가 높은 평가를 받았는데, S1김치는 저장 말기에 신맛과 탄산미가 증가하는 현상을 보였는데, 이는 Leuconostoc spp.의 균수 저장 후기에 높아졌기 때문으로 생각된다. 이상의 결과를 종합해 보면 김장김치를 저장 기간 내 맛있게 먹기 위해서는 김치를 완전히 숙성시킨 후 저온에서 저장하는 방법인 $10^{\circ}C$에서 5일 동안 발효시켜 $-2.5^{\circ}C$로 온도 변환하는 시스템이 가장 우수하였다. '저온 저장' 온도로는 $-1^{\circ}C$가 $-2.5^{\circ}C$보다 우수하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.204.1-204.1
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• 2013

Fluorine, the radius of which is close to that of oxygen, could be an appropriate anion doping candidate. A lower lattice distortion could be expected for F doping, compared with Al, Ga, and In doping. F-doped ZnO (FZO) and undoped ZnO nanorods were grown onto glass substrate by the hydrothemal method. The doping level in the solution, designated by F/Zn atomic ratio of was varied from 0.0 to 10.0 in 2.0 steps. To investigate the effects of the structure and optical properties of FZO nanorods were investigated using X-ray diffraction, UV-visible spectroscopy and photoluminescence (PL). For the PL spectra, the maximum peak position of NBE moves to higher energy, from 0 to 4 at.%. As the doping concentration increases, the maximum peak position of NBE gradually moves to lover energy, from 4 to 10 at.%.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
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• pp.166-166
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• 2000

We studied electronic structure of magnetic semiconductors EuO, EuS, and EuTe. The photoemission spectra show localized Eu 4f states and broad anion p bands. As the size of anion increases from oxygen to tellurium, anion p band width increases and eventually overlaps Eu 4f states. Hence in EuO and EuS, Eu 4f states are the highest occupied stated lying above anion p band, while Te 5p band spreads widely over Eu 4f states to become valence band maximum in EuTe. It was also observed that Eu 4f states have width of 0.7eV and dispersion of 0.2eV in EuS by angle resolved photoemission spectroscopy. The width of the 4f spectra mainly originates from atomic multiplets, but the much larger dispersion than that of Eu metal is due to p-f mixing.

• Journal of Advanced Marine Engineering and Technology
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• 제36권5호
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• pp.635-644
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• 2012

해양 파력 발전 시스템의 설계를 위하여 본 연구에서는 6-자유도운동해석 기법을 적용한 3차원 CFD 해석으로 단일 부유체에 대한 거동을 유입되는 파의 성질에 따라 해석하였다. 입력파는 한반도 제주도 서남해역 마라도인근 연평균 주기 5.5s, 진폭 0.57m로 가정하여 부유체 고유진도주기가 1.25~2.8s에서 총 12개를 모델링하였다. 생성된 파를 이용하여 동조율과 피치각 변화의 상호관계를 분석하고 부유체 질량관성모멘트, 각속도, 각가속도 등 변수와 최대 에너지 흡수 관계를 비교 분석하였다. 해석결과 부유체 L의 에너지흡수가 가장 높은 6kW인 결과를 확인하였고 에너지 흡수가 가장 높은 D, F, L 모델중 F모델이 최대 각도변화가 가장 높은 $1.91^{\circ}$이며 부유체 끝부분에서의 최대 변위는 L모델이 가장 높은 약 0.7m이다.