• Journal of Microbiology
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• 제44권2호
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• pp.155-161
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• 2006

Comparative analysis of microbial communities in a sequencing batch reactor which performed enhanced biological phosphorus removal (EBPR) was carried out using a cultivation-based technique and 16S rRNA gene clone libraries. A standard PCR protocol and a modified PCR protocol with low PCR cycle was applied to the two clone libraries of the 16S rRNA gene sequences obtained from EBPR sludge, respectively, and the resulting 424 clones were analyzed using restriction fragment length polymorphisms (RFLPs) on 16S rRNA gene inserts. Comparison of two clone libraries showed that the modified PCR protocol decreased the incidence of distinct fragment patterns from about 63 % (137 of 217) in the standard PCR method to about 34 % (70 of 207) under the modified protocol, suggesting that just a low level of PCR cycling (5 cycles after 15 cycles) can significantly reduce the formation of chimeric DNA in the final PCR products. Phylogenetic analysis of 81 groups with distinct RFLP patterns that were obtained using the modified PCR method revealed that the clones were affiliated with at least 11 phyla or classes of the domain Bacteria. However, the analyses of 327 colonies, which were grouped into just 41 distinct types by RFLP analysis, showed that they could be classified into five major bacterial lineages: ${\alpha},\;{\beta},\;{\gamma}-$ Proteobacteria, Actinobacteria, and the phylum Bacteroidetes, which indicated that the microbial community yielded from the cultivation-based method was still much simpler than that yielded from the PCR-based molecular method. In this study, the discrepancy observed between the communities obtained from PCR-based and cultivation-based methods seems to result from low culturabilities of bacteria or PCR bias even though modified culture and PCR methods were used. Therefore, continuous development of PCR protocol and cultivation techniques is needed to reduce this discrepancy.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권2호
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• pp.144-149
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• 2001

For the production and purification of a single chain human insulin precursor, four types of fusion peptides $\beta$-galactosidase (LacZ), maltose binding protein (MBP), glutathione-S-transferase (GST), and (His)(sub)6-tagged sequence (HTS) were investigated. Recombinant E. coli harboring hybrid genes was cultivated at 37$\^{C}$ for 1h, and gene induction occurred when 0.2mM of isopropyl-D-thiogalactoside (IPTG) was added to the culture broth, except for E. coli BL21 (DE3) pLysS harboring a pET-BA cultivation with 1.0mM IPTG, followed by a longer than 4h batch fermentation respectively. DEAE-Sphacel and Sephadex G-200 gel filtration chromatography, amylose affinity chromatography, glutathione-sepharose 4B affinity chromatography, and a nickel chelating affinity chromatography system as a kind of immobilized metal ion affinity chromatography (IMAC) were all employed for the purification of a single chain human insulin precursor. The recovery yields of the HTS-fused, GST-fused, MBP-fused, and LacZ-fused single chain human insulin precursors resulted in 47%, 20%, 20%, and 18% as the total protein amounts respectively. These results show that a higher recovery yield of the finally purified recombinant peptides was achieved when affinity column chromatography was employed and when the fused peptide had a smaller molecular weight. In addition the pET expression system gave the highest productivity of a fused insulin precursor due to a two-step regulation of the gene expression, and the HTS-fused system provided the highest recovery of a fused insulin precursor based on a simple and specific separation using the IMAC technique.

• 국제초고층학회논문집
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• 제3권4호
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• pp.255-271
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• 2014

A method of smart system identification of super high-rise buildings is proposed in which super high-rise buildings are modeled by a shear-bending system. The method is aimed at finding the story shear and bending stiffnesses of a specific story only from the horizontal floor accelerations. The proposed method uses a set of closed-form expressions for the story shear and bending stiffnesses in terms of the limited floor accelerations and utilizes a reduced shear-bending system with the same number of elements as the observation points. A difficulty of prediction of an unstable specific function in a low frequency range can be overcome by introducing an ARX model and discussing its relation with the Taylor series expansion coefficients of a transfer function. It is demonstrated that the shear-bending system can simulate the vibration records with a reasonable accuracy. It is also shown that the vibration records at two super high-rise buildings during the 2011 Tohoku (Japan) earthquake can be simulated with the proposed method including a technique of inserting degrees of freedom between the vibration recording points. Finally it is discussed further that the time-varying identification of fundamental natural period and stiffnesses can be conducted by setting an appropriate duration of evaluation in the batch least-squares method.

• 한국결정성장학회지
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• 제6권1호
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• pp.88-97
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• 1996

태양전지의 전극형성은 전지의 가격과 성능 그리고 시스댐의 신뢰성을 결정하는데 매우 중요한 변수이다. 기폰의 스크련 프린팅 기술은 전면전극에 냐쁜 영향을 미치는 여러가지 제약들을 가지고 었다. 전극함몰형 태양전지는 기존의 전극에서 발생하는 문제점을 극복하고 저가격 대량생산을 위해서 고안된 것이다. 본 논문에서는 무전해 도금방법을 사용하여 함몰형 전지의 전극을 형성하는 공정을 최적화함으로써 값싸고 재현성있게 전지를 제조할 수 있었다. 무전해 도금용액으로는 상엽적으로 사용되는 니켈, 구리, 은 용액을 사용하었으며, 전지의 효울 을 최고 18.8 %까지 얻었다. 이때 전지의 개방전압은 651 mV, 단락전류밀도는 37.1 mA/$\textrm{cm}^2$, 충실도는 77.8 % 었으며 배치에서 90 % 이상의 전지가 18 % 이상의 효율을 나타내었다.

• 한국재료학회지
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• 제14권2호
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• pp.141-145
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• 2004

Silicon nitride thin films were deposited by atomic layer deposition (ALD) technique in a batch-type reactor by alternating exposures of precursors. XJAKO200414714156408$_4$ or$ SiH_2$$Cl_2$ was used as the Si precursor, $NH_3$ was used as the N precursor, and the deposited films were characterized comparatively. The thickness of the film linearly increased with the number of deposition cycles, so that the thickness of the film can be precisely controlled by adjusting the number of cycles. As compared with the deposition using$ SiCl_4$, the deposition using $SiH_2$$Cl_2$ exhibited larger deposition rate at lower precursor exposures, and the deposited films using $SiH_2$$Cl_2$ had lower wet etch rate in a diluted HF solution. Silicon nitride films with the Si:N ratio of approximately 1:1 were obtained using either Si precursors at $500^{\circ}C$, however, the films deposited using $SiH_2$$Cl_2$ exhibited higher concentration of H as compared with those of the $SiC_4$ case. Silicon nitride thin films deposited by ALD showed similar physical properties, such as composition or integrity, with the silicon nitride films deposited by low-pressure chemical vapor deposition, lowering deposition temperature by more than $200^{\circ}C$.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.15-22
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• 2006

This paper presents a novel signal tracking algorithm for GNSS receivers using a MLE technique. In order to perform a robust signal tracking in severe signal environments, e.g., high dynamics for navigation vehicles or weak signals for indoor positioning, the MLE based signal tracking approach is adopted in the paper. With assuming white Gaussian additive noise, the cost function of MLE is expanded to the cost function of NLSE. Efficient and practical approach for Doppler frequency tracking by the MLE is derived based on the assumption of code-free signals, i.e., the cost function of the MLE for carrier Doppler tracking is used to derive a discriminator function to create error signals from incoming and reference signals. The use of the MLE method for carrier tracking makes it possible to generalize the MLE equation for arbitrary codes and modulation schemes. This is ideally suited for various GNSS signals with same structure of tracking module. This paper proposes two different types of MLE based tracking method, i.e., an iterative batch processing method and a non-iterative feed-forward processing method. The first method is derived without any limitation on time consumption, while the second method is proposed for a time limited case by using a 1st derivative of cost function, which is proportional to error signal from discriminators of conventional tracking methods. The second method can be implemented by a block diagram approach for tracking carrier phase, Doppler frequency and code phase with assuming no correlation of signal parameters. Finally, a state space form of FLL/PLL/DLL is adopted to the designed MLE based tracking algorithm for reducing noise on the estimated signal parameters.

• 자원리싸이클링
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• 제4권3호
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• pp.2-9
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• 1995

탈황 폐촉매 중에 함유되어 있는 Ni, V 및 Mo을 배소, 암모니아 침출 및 용매추출법을 이용하여 분리.회수하는 프로세스에 대하여 연구하였다. 폐촉매를 $400^{\circ}C$로 3시간 동안 배소한 후, 20mesh 이하로 분쇄하여, 고액비 50g/d㎥의 조건에서 100g/d㎥-(NH$_4$)$_2$CO$_3$를 침출제로 하여 $80^{\circ}C$에서 침출한 결과 Ni, V 및 Mo의 침출율은 각각 81.2%, 65%, 87.5%이었다. 이 침출액을 방냉하면 침출액 중의 74%의 V이 바나듐산 나트륨염의 형태로 침전되어 순도 95.7%의 V을 회수할 수 있었다. 1차 침출 후의 잔사에$ Na_2$$CO_3$를 가하여 $1000^{\circ}C$에서 재차 배소한 후, 온수에 침출하여 잔존된 Mo과 V을 95%이상 침출되었다. 1차 침출액 중의 Ni, V 및 Mo을 용매추출법으로 분리.정제하였다. 용액 중의 Ni는 MSP-8, V은 TOMAC을 추출제로 하여 추출.분리하고 Mo은 raffinate로 분리하였다. Batch 추출에 의하여 Ni은 95%, V은 98%가 유기상에 추출되었으며, 역추출액에 환원제를 첨가하여 순도 99%이상의 V을 회수하였다.

• 한국산학기술학회논문지
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• 제21권1호
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• pp.560-567
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• 2020

점진판재성형은 금형을 제작하지 않고 판재를 가공하는 방법으로서 빠른 시제품 제작과 소량 생산에 적합한 성형법이다. 이러한 점진판재성형의 공정 변수로 공구 직경, 매 스탭당 Z-방향 깊이, 공구 이송 속도, 공구 회전 속도 등은 성형품의 품질에 크게 영향을 미친다. 본 연구에서는 두께가 1.0mm인 Al3004판재를 사용하여 원뿔절두체(VWACF: Varying Wall Angle Conical Frustum) 모델의 점진성형을 실시하였으며, 각각의 변수들의 조합에서 성형성을 판단하였다. BP신경망 (BPNN: Back Propagation Neural Network)를 기반으로 Minitab 소프트웨어를 사용하여 성형 각도를 예측하는 2 차 수학적 모델을 구축하였다. 또한 이 모델을 유전 알고리즘의 목적함수로 사용하였으며 최대 성형 각도로 얻기 위한 최적의 변수 조합을 찾아내었다. 공구 직경은 6mm, 회전 속도는 180rpm, Z-방향 피치는 0.401mm, 이송 속도는 772.4mm/min일 경우 가장 큰 성형 각도인 87.071°를 갖는 컵을 성형할 수 있었다.

• 폴리머
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• 제37권6호
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• pp.685-693
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• 2013

반응 컴파운딩으로 개질한 poly(lactic acid)를 초임계 $CO_2(scCO_2)$를 사용하여 발포하였다. 발포는 $105{\sim}135^{\circ}C$와 12~24 MPa 범위에서 실시하였다. 발포체의 발포 배율과 셀 구조는 온도, 압력 및 감압 속도와 같은 발포 조건에 크게 영향을 받았다. 발포 온도와 포화 압력 증가에 따라서 발포 배율은 증가하다가 감소하였으며, 그 결과로 $120^{\circ}C$ 발포 온도 및 20 MPa 포화 압력에서 최대 발포 배율이 얻어졌다. 감압 속도가 느린 경우에는 셀이 장시간 동안 팽창함으로써 보다 큰 셀 구조를 가지는 발포체가 얻어졌다.

• 공업화학
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• 제9권5호
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• pp.661-666
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• 1998

고시리카제올라이트 (HSZ), 거대망상수지입자(MR) 및 입상활성탄(GAC)에 의한 수용액중의 12가지 아민유도체의 평형흡착 실험 데이터와 Freundlich, Langmuir, Toth, Redlich-Peterson 식의 인자들을 각각 구하였다. 아민류의 흡착특징에 있어서는 고시리카제올라이트는 unfavourable, 입상활성탄은 favourable로 비선형이나, 거대망상수지흡착제는 선형관계의 특성을 나타내며, 변수가 2개인 Freundlich 식과 3개인 Redlich-Peterson 흡착등온식에 잘 일치하였다. HSZ, MR, GAC에 의한 아민류의 흡착능은 방향족>1급아민>2급아민 순이었으며, Freundlich상수 k와 n의 곱인 (k n)값은 HSZ와 MR 및 GAC에서 아민류의 끓는 점 $T_B$, 몰부피 $V_m$, 그리고 해리상수 $pK_a$에 비례하여 증가하였다.