• 마이크로전자및패키징학회지
• /
• 제20권4호
• /
• pp.25-30
• /
• 2013

Pb-free ferroelectric $(Na_{0.5}Bi_{0.5})TiO_3$ (NBT) thin films were prepared by a modified sol-gel process. Their structural, dielectric and pyroelectric properties were investigated as a function of the excess Na/Bi ratio and the annealing temperature. In the case of thin films containing no excess Na and Bi, only partial amounts of the perovskite NBT were crystallized, where the films consisted mainly of the pyrochlore phase of $Bi_2Ti_2O_7$ for annealing conditions of $600{\sim}800^{\circ}C$. With increasing excess Na/Bi ratio, the proportion of the perovskite phase effectively increased due to the compensation of the volatile Na and Bi components. For a Na/Bi ratio of 2.0, the thin film with single NBT perovskite phase was obtained within XRD detection limit after annealing at $700^{\circ}C$ for 10 min and it showed the excellent dielectric properties, ${\varepsilon}r$ of ~550 and tan ${\delta}$ of 0.03. While these properties were degraded for Na/Bi ratio of 2.5 despite the existence of pure perovskite phase. The NBT thin film with Na/Bi ratio of 2.0 are also promising candidates for applications requiring pyroelectric devices because it was found to have pyroelectric coefficients of $1.3{\sim}7nC/cm^2K$ in the temperature range of $30{\sim}100^{\circ}C$.

• ALGAE
• /
• 제21권3호
• /
• pp.311-316
• /
• 2006

The effects of light quality and irradiance on the growth of Cochlodinium polykrikoides were investigated in the laboratory. At 25°C and 30 psu the irradiance-growth curve was described as μ = 0.34 (I-9.76)/(I+12.5), (r=0.98). This suggests half-saturation photon flux density (PFD) (Ks) of 32.0 μmol photons m–2 s–1, and a compensation PFD (Ic) of 9.76 μmol photons m–2 s–1. Because the Ic equates to a depth of ca. 15.4 m, these responses suggest that irradiance at the depth around and below the thermocline in Yeosuhae Bay would provide favorable conditions for C. polykrikoides. Photoinhibition did not occur at 300 μmol photons m–2 s–1, which was the maximum irradiance used in this study. Blue (450 nm), yellow (590 nm) and red (650 nm) light had different effects on the growth of C. polykrikoides: it grew well under blue light, but not under yellow light. This implies that C. polykrikoides is more likely to cause an outbreak of red tide in the open sea where blue-green wavelengths predominate, rather than in enclosed water bodies where suspended particles absorb most of the blue wavelengths, and yellow-orange wavelengths predominate.

• 대한화학회지
• /
• 제36권5호
• /
• pp.697-708
• /
• 1992

역상 액체 크로마토그래피에 의하여 Ni(IEAA-NH)(IEAA-NR)(R = H, $CH_3,\;C_2H_5,\;n-C_3H-7,\;n-C_4H9-,\;CH_5-CH_$) 킬레이트의 동시 분리 및 분석을 위한 최적조건을 Micropak MCH-5 분리관을 사용하여 조사하고, 이들의 용리거동에 대한 인자들과의 관계를 검토하였다. 용리액에서 methanol/water의 이성분 용매를 사용하였으며, 모든 금속 킬레이트의 용매 세기 인자는 $0{\le}logk'{\le}1$의 범위임을 확인하였고, 각 금속 킬레이트의 logk'값과 이성분용매계 중의 물의 부피분율을 도시한 결과 직선 관계가 성립하였다. 또한 뱃치법으로 측정한 분포비(Dc)값과 k'값을 도시하여 본 결과 직선 관계가 성립됨으로써 금속 킬레이트의 용리 메카니즘이 주로 소용매성 효과 즉 소수성효과에 기인함을 확인하였다. 한편 금속 킬레이트의 머무름에 미치는 용량 인자와 온도와의 관계를 조사한 결과 좋은 직선성을 나타내고 있으며, 뿐만 아니라 직선의 기울기로부터 엔탈피(${\delta}H$)와 엔탈피(${\delta}S$)를 구하고, 엔탈피와 용량 인자와의 값을 도시한 결과도 직선관계가 성립하였다. 직선의 기울기로부터 구한 보정 온도(${\beta}$)는 $773.47^{\circ}K$이었다. 이 결과 역상 HPLC에서 Ni(II)-Isonitrosoethylacetoacetate imine 킬레이트의 용리 메카니즘의 주로 소수성 효과에 기인함을 재확인 할 수 있었다.

• 센서학회지
• /
• 제16권1호
• /
• pp.44-51
• /
• 2007

A hybridized simulator for generating blood pressure waveform is proposed to study the remedy and/or evaluation of the conventional sphygmomanometer utilizing the oscillometric method which is widely applied. The blood pressure of a flowing fluid was controlled for the blood vessel's condition caused by a rhythmical and periodical contraction/relaxation because of the special excitatory and conductive system of the heart. In this study, a hybridized controller composed of the PI feedback controller and the feedforward controller. The inverse dynamics function is proposed to operating the control valve while the pressure is applied in an oil pressure tank. The proposed hybrid simulator reproducing the blood pressure waveform in an artificial blood vessel has kept the control performance consistent over all range. Based on these results, the proposed simulators could be applied to the development and compensation of the non invasive sphygmomanometer type as well as to study the characteristics of the blood pressure and blood vessel.

• Journal of Power Electronics
• /
• 제18권3호
• /
• pp.863-870
• /
• 2018

The traditional power control theories for the harmonic reduction methods in multilevel inverters are found to be unreliable under unbalanced load conditions. The unreliability in harmonic mitigation is caused by voltage fluctuations, non-linear loads, the use of power switches, etc. In general, the harmonics are reduced by filters. However, such devices are an expensive way to provide a smooth and fast response to secure power systems during dynamic conditions. Hence, the Decoupled Double Synchronous Reference Frame (DDSRF) theory combined with a State Delay Controller (SDC) is proposed to achieve a harmonic reduction in power systems. The DDSRF produces a sinusoidal harmonic that is the opposite of the load harmonic. Then, it injects this harmonic into power systems, which reduces the effect of harmonics. The SDC is used to reduce the delay between the compensation time for power injection and the generation of a reference signal. The proposed technique has been simulated using MATLAB and its reliability has been verified experimentally under unbalanced conditions.

• 대한전자공학회논문지SD
• /
• 제45권9호
• /
• pp.71-78
• /
• 2008

본 논문에서는 H.264AVC baseline 디코더를 ARM926EJ-S 코어를 탑재한 FPGA(XC4VLX60)기반의 타겟 보드와 임베디드용 Linux Kernel 2.4.26의 개발환경에서 SW/HW 분할을 통해 설계 및 구현하였다. 하드웨어 가속기로는 움직임 보상 모듈 디블록킹 필터 모듈, YUV2RGB 변환 모듈을 사용하였으며 AMBA 버스 프로토콜을 통하여 소프트웨어와 함께 동작한다. 참조 소프트웨어(JM 11.0)를 OS(Linux)상에서 하드웨어 가속 모듈을 추가하고 메모리 접근 등을 최소화함으로써 성능을 향상시키고자 노력하였다. 설계된 하드웨어 IP와 시스템은 여러 단계로 검증하였으며 시스템의 복호화 속도 개선을 도모하였다. QCIF (176$\times$144) 영상을 24MHz의 클록 주파수의 타겟 보드상에서 약 2 frames/sec의 결과를 얻었으며 타겟 보드의 주파수를 증가시키고 FPGA영역의 IP를 ASIC으로 구현하면 더 좋은 성능을 기대할 수 있다.

• 폴리머
• /
• 제37권6호
• /
• pp.744-752
• /
• 2013

배향된 상태에서 복굴절이 없는 zero-${\Delta}$n 재료를 개발할 목적으로 용융혼합된 폴리락타이드(PLLA, (+)복굴절)/폴리(메틸 메타크릴레이트)(PMMA, (-)복굴절) 블렌드의 상용성과 PMMA의 공단량체인 메틸 아크릴레이트(MA)가 PLLA와의 상용성에 미치는 영향을 살펴보았다. MA 함량에 상관없이 모든 블렌드에서 조성에 따라 변하는 단일 $T_g$와 90% 이상의 투명도가 관찰되었으며, 이로부터 용융혼합된 PLLA/PMMA 블렌드는 분자수준에서 상용성을 보임을 확인하였다. 이들 블렌드는 $280^{\circ}C$의 온도에서도 안정한 단일상을 유지하였다. MA가 17 mol%첨가된 PMMA17과 PLLA의 블렌드의 경우 Hoffman-Weeks 방법을 적용하여 평형융점으로부터 구한 상호작용 에너지 밀도(B)는 $-0.74J/cm^3$이었다. PLLA/PMMA 블렌드는 배향되었을 때 조성고분자들의 고유 배향복굴절이 상쇄되어 특정 혼합비에서 "0" 가까운 복굴절 특성을 나타내었다. PLLA/PMMA5 블렌드의 경우 혼합비에 따른 복굴절 분산을 측정한 결과 zero-${\Delta}$n 특성을 보이는 혼합비에서 역분산이 나타나며, 파장의존성이 없는 복굴절 특성을 보이는 조성이 존재함을 확인하였다.

• ALGAE
• /
• 제19권4호
• /
• pp.293-301
• /
• 2004

여수해만에서 분리한 Gymnodinium catenatum의 성장에 있어서 최적 수온과 염분 조건을 파악하기 위해 수온 6단계,염분 5단계의 조합에 의한 30단계의 배치배양을 실시하여, 성장속도를 계산하였다. C. catenatum은 약 18${^{\circ}C}$ 이상의 수온과 전 염분단계에서 0.3day$^{-1}$ 이상의 성장속도를 보였으며 수온의 감소와 함께 성장속도도 감소하였다. 하지만 염분은 성장에 그다지 영향을 미치지 않았다. 최대성장속도(0.5day$^{-1}$)는 수온 25${^{\circ}C}$와 염분 30psu에서 얻어졌다. 따라서, 수온과 염분에 따른 성장속도를 고려할 때, C. catenatum은 이른 여름부터 가을까지 한국남해연안해역에서 서식 가능한 것으로 판단된다 이 종의 출현을 예측하기 위한 모델식은 $\mu$ = 0.005-T$^2$ - 0.0001164 T$^3$ - 0.063-S + 0.005-S$^2$ - 0.00007608-S$^3$ - 0.003-T-S + 0.00005308-T$^2$-S로 나타났다. 한편. 수온 18${^{\circ}C}$와 염분 30psu 조건하에서 6단계의 광도 실험을 실시한 결과, 광량에 따른 C. catenatum의 성장은 $\mu$ = 0.16 (I - 10.4)/(1+21.8), (r=0.96)의 관계식으로 Ks는 42.6$\mu$mol m$^{-2}$s$^{-1}$, I$_0$는 10.4$\mu$mol m$^{-2}$s$^{-1}$이었다. 따라서 수온, 염분과 광 조건만을 고려할 경우 C. catenatum은 고수온기 한국 남해 내만과 연안해역에서 우점종으로 출현할 가능성이 높을 것으로 판단되었다.

• 한국수산과학회지
• /
• 제43권6호
• /
• pp.715-722
• /
• 2010

The effects of temperature, salinity and irradiance on the growth of the harmful red tide dinoflagellate Cochlodinium polykrikoides Margelef isolated from the South Sea of Korea were examined in the laboratory. Growth was examined under the following combinations of temperature and salinity: 15, 20, 25 and $30^{\circ}C$, and 15, 20, 25, 30 and 35 psu at a constant irradiance of $180\;{\mu}mol/m^2/s$. No growth was observed with a temperature of $15^{\circ}C$ and a salinitiy of 15 psu. Moderate growth rates of more than 0.30 /day were obtained at $25^{\circ}C$ with salinities of 25.35 psu. These values are similar to in situ observations for this species. The maximum growth rate, 0.35 /day, was obtained at $25^{\circ}C$ and 30 psu. In light experiments, cell growth of C. polykrikoides was conducted with constant temperature ($20^{\circ}C$) and salinity (30 psu) under light photon flux densities (PFD) of 10, 25, 50, 70, 100, 150, 250 and $350\;{\mu}mol/m^2/s$. C. polykrikoides did not grow at $10\;{\mu}mol/m^2/s$. Cell growth was observed at irradiance values of $25\;{\mu}mol/m^2/s$ and above. The irradiance-growth curve was described as ${\mu}=0.30{\cdot}(I-15.27)/(I+27.22)$, (r=0.99). This suggests a compensation PFD of $15.27\;{\mu}mol/m^2/s$ and a maximum growth rate of 0.30 /day. In conclusion, C. polykrikoides prefers high salinity, temperature and irradiance in summer in Korea. These results provide important information for understanding the mechanism of C. polykrikoides blooms and developing technology to predict blooms of this organism in the field.

• Asian-Australasian Journal of Animal Sciences
• /
• 제12권6호
• /
• pp.871-880
• /
• 1999

The effects of dry roasting (110, 130, $150^{\circ}C$ for 15, 30, 45 min) on potential ruminant protein nutritional values in terms of: a), rumen bypass protein (BCP); b), rumen bypass starch (BST); c), fermented organic matter (FOM); d), true absorbed bypass protein (ABCP); e) microbial protein synthesized in the rumen based on available energy (E_MP); f), microbial protein synthesized in the rumen based on available nitrogen (N_MP); g), true protein supplied to the small intestine (TPSI); h), true absorbed rumen synthesized microbial protein (AMP); i), endogenous protein losses (ENDP); j), true digested protein in the small intestine (DVE); k), degraded protein balance (OEB) of whole lupin seeds (WLS) and faba beans (WFB) were evaluated by the new Dutch DV/OEB protein evaluation system. Dry roasting significantly increased BCP, BST, TPSI, ABCP, DVE (p<0.001) and decreased FOM, E_MP, AMP, N_MP and OEB (p<0.001) with increasing temperatures and times except that when temperature was at $110^{\circ}C$. The values of BCP, BST, TPSI, ABCP and DVE at $150^{\circ}C/45min$ for WLS and WFB were increased 2.2, 3.7; -, 2.0; 1.7, 1.7; 2.3, 3.7 and 1.7, 1.7 times and the values of FOM, E_MP, AMP, N_MP and OEB at $150^{\circ}C/45min$ for WLS and WFB were decreased by 15.3, 25.8; 18.1, 25.8; 18.7, 25.8; 54.6, 41.6 and 82.3% 54.7%, respectively, over the raw WLS and WFB. The results indicated that though dry roasting reduced microbial protein synthesis due to reducing FOM, TPSI didn't decrease but highly increased due to increasing BCP more than enough for compensation of the microbial protein decreasing. Therefore the net absorbable DVE in the small intestine was highly increased. The OEB values were significantly reduced for both WLS and WFB but not to the level of negative. It indicated that microbial protein synthesis might not be impaired due to the sufficient N supplied in the rumen, but the high positive OEB values in the most treatments except of $150^{\circ}C$ for 30 and 45 min of WLS (The OEB values: 54.8 and 26.0 g/kg DM) indicated that there were the large amounts of N loss in the rumen. It was concluded that dry roasting at high temperature was effective in shifting protein degradation from rumen to intestines and it increased the DVE values without reaching the negative OEB values. No optimal treatment was found in WLS due to the too high OEB values in all treatments. But dry roasting at $150^{\circ}C$ for 30 and 45 min might be optimal treatments for WLS due to the very lower OEB values.