• 생명과학회지
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• 제26권12호
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• pp.1376-1382
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• 2016

Xylitol은 식품 및 의료산업에서 이용가치가 높은 물질로, lignocellulosic biomass인 xylose의 환원으로부터 생산되며, 대부분 유전적으로 안전한 Saccharomyces cerevisiae 균주를 사용하여 생산되고 있다. 따라서 본 연구에서는 S. cerevisiae에서 xylitol을 효율적으로 생산하기 위해 xylose reductase를 code하는 GRE3 (YHT104W)유전자의 발현시스템을 구축하여, xylose reductase의 분비생산 및 xylitol 생산성을 조사하고자 하였다. 먼저 GRE3 유전자의 발현에 적합한 promoter의 선별을 위해 GAL10 promoter와 ADH1 promoter 하류에 각각 mating factor ${\alpha}$ ($MF{\alpha}$) signal sequence와 GRE3 유전자를 가진 pGMF-GRE3와 pAMF-GRE3 plasmid를 구축하였다. 각각의 plasmid는 S. cerevisiae $SEY2102{\Delta}trp1$균주에 형질전환되었고, $SEY2102{\Delta}trp1$/pGMF-GRE3와 $SEY2102{\Delta}trp1$/pAMF-GRE3 형질전환주가 선별되었다. 그 중 $SEY2102{\Delta}trp1$/pGMF-GRE3 균주에서 NADPH를 cofactor로 사용했을 때 0.34 unit/mg-protein의 xylose reductase 활성(total activity)을 보였고, ADH1 promoter를 가진 $SEY2102{\Delta}trp1$/pAMF-GRE3 균주에 비해 1.5배 높은 활성증가를 확인 할 수 있었다. 또한 두 균주에서 모두 91%의 분비효율을 보여 대부분의 재조합 xylose reductase가 세포 밖으로 효율적으로 발현 분비되었음을 알 수 있었다. $SEY2102{\Delta}trp1$/pGMF-GRE3 균주를 사용한 baffled flask 배양에서 xylitol 생산량을 조사해 본 결과, 20 g/l의 xylose로부터 12.1 g/l의 xylitol을 생산하였고, 소모된 xylose의 약 83%정도가 xylitol로 환원되었음을 알 수 있었다.

• ETRI Journal
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• 제40권2호
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• pp.167-179
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• 2018

This paper proposes an IEEE 802.15.4m compliant TV white-space orthogonal frequency-division multiplexing (TVWS)-(OFDM) radio frequency (RF) transceiver that can be adopted in advanced metering infrastructures, universal remote controllers, smart factories, consumer electronics, and other areas. The proposed TVWS-OFDM RF transceiver consists of a receiver, a transmitter, a 25% duty-cycle local oscillator generator, and a delta-sigma fractional-N phase-locked loop. In the TV band from 470 MHz to 698 MHz, the highly linear RF transmitter protects the occupied TV signals, and the high-Q filtering RF receiver is tolerable to in-band interferers as strong as -20 dBm at a 3-MHz offset. The proposed TVWS-OFDM RF transceiver is fabricated using a $0.13-{\mu}m$ CMOS process, and consumes 47 mA in the Tx mode and 35 mA in the Rx mode. The fabricated chip shows a Tx average power of 0 dBm with an error-vector-magnitude of < 3%, and a sensitivity level of -103 dBm with a packet-error-rate of < 3%. Using the implemented TVWS-OFDM modules, a public demonstration of electricity metering was successfully carried out.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.341-344
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• 2003

This paper proposes a tree-winding transformer protective relaying algorithm based on the ratio of increment of flux linkages (RIFL). The RIFL of the two windings is equal to the turns ratio for all operating conditions except an internal faults. For a single-phase transformer and three-phase transformer containing the wye-connected windings, the increments of flux linkages are calculated. for a three-phase transformer containing the delta-connected windings, the difference of the increments of flux linkages between the two phases are calculated using the line currents, because the winding currents are practically unavailable. Their ratios are compared with the turns ratio. The results of various tests show that the algorithm successfully discriminates internal faults from normal operation conditions such as magnetic inrush, overexcitation and external faults. The algorithm can not only detect internal winding faults, but reduce the operating time of a relay.

• Kyungpook Mathematical Journal
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• 제56권1호
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• pp.185-220
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• 2016

We study the Gauss and Poisson semigroups connected with the Riemann-Liouville operator defined on the half plane. Next, we establish a principle of maximum for the singular partial differential operator $${\Delta}_{\alpha}={\frac{{\partial}^2}{{\partial}r^2}+{\frac{2{\alpha}+1}{r}{\frac{\partial}{{\partial}r}}+{\frac{{\partial}^2}{{\partial}x^2}}+{\frac{{\partial}^2}{{\partial}t^2}}};\;(r,x,t){\in}]0,+{\infty}[{\times}{\mathbb{R}}{\times}]0,+{\infty}[$$. Later, we define the Littlewood-Paley g-function and using the principle of maximum, we prove that for every $p{\in}]1,+{\infty}[$, there exists a positive constant $C_p$ such that for every $f{\in}L^p(d{\nu}_{\alpha})$, $${\frac{1}{C_p}}{\parallel}f{\parallel}_{p,{\nu}_{\alpha}}{\leqslant}{\parallel}g(f){\parallel}_{p,{\nu}_{\alpha}}{\leqslant}C_p{\parallel}f{\parallel}_{p,{\nu}_{\alpha}}$$.

• 약학회지
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• 제27권3호
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• pp.185-205
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• 1983

Penicillins and cephalosporins are biosynthesized from L-.alpha.-aminoadipic acid, L-cysteine and L-valine. A tripeptide, LLD-$\delta$-($\alpha$-aminoadipyl)cysteinylvaline(LLD-ACV) was isolated from fermentation broths of Cephalosporium acremonium as well as of Penicillium chrysogenum and it was proved that the LL-$\delta$-($\alpha$-aminoadipyl cysteine was formed first in mycelia, to which valine would be connected to give LLD-ACV. However, several points are still unsolved; first, what mechanism is involved in the configurational change from L-valine to D-valine, second, what kind of cyclization mechanism gives a $\betha$-lactam ring and a thiazolidine ring and third, what is the pathways for the ring expansion from penicillins to cephalosporins. At present, it seems clear that LLD-ACV is cyclized to give isopenicillin N, which is transformed to penicillin N and further to cepbalosporin C. Other hydrophobic penicillins, including benzyl penicillin and penicillin V, are formed from isopenicillin N by acyl-exchange reactions catalyzed by penicillin transferase, rather than by acylation reaction on 6-aminopenicillanic acid(6-APA), which was isolated from the fermentation broth of P. chrysogenum and which would be formed by hydrolysis of $\delta-(\alpha$-amincadipyl)amido moiety at the C-6 position in isopenicillin N or penicillin N by penicillin acylase. Acylation of 6-APA is catalyzed also by penicillin acylase, but the reaction is proved not to be involved in penicillin biosynthesis. Understanding the biosynthesis of penicillins and cephalsoporins would provide solutions to increase in fermentation yields of penicillins, especially of cephalosporins and a solution to biological production of 7-aminocepbalosporanic acid (7-ACA) which is of importance in pharmaceutical industry. Still regulation mechanisms in penicillin and cephalosporin biosynthesis are unveiled at all.

• 말소리와 음성과학
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• 제11권2호
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• pp.57-64
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• 2019

본 논문에서는 음성 합성을 위한 오픈소스 시스템인 Merlin 툴킷을 이용하여 한국어 TTS 시스템을 구성한다. TTS 시스템에서 HMM 기반의 통계적 음성 합성 방식이 널리 사용되고 있는데, 이 방식에서 문맥 요인을 포함시키는 음향 모델링 구성의 한계로 합성 음성의 품질이 저하된다고 알려져 있다. 본 논문에서는 여러 분야에서 우수한 성능을 보여 주는 심층 신경망 기법을 적용하는 음향 모델링 아키텍처를 제안한다. 이 구조에는 전연결 심층 피드포워드 신경망, 순환 신경망, 게이트 순환 신경망, 단방향 장단기 기억 신경망, 양방향 장단기 기억 신경망 등이 포함되어 있다. 실험 결과, 문맥을 고려하는 시퀀스 모델을 아키텍처에 포함하는 것이 성능 개선에 유리하다는 것을 알 수 있고, 장단기 기억 신경망을 적용한 아키텍처가 가장 좋은 성능을 보여주었다. 그리고 음향 특징 파라미터에 델타와 델타-델타 성분을 포함하는 것이 성능 개선에 유리하다는 결과가 도출되었다.

• Journal of Power Electronics
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• 제19권3호
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• pp.784-793
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• 2019

Two objectives can be pursued simultaneously with the ${\delta}$ control of a single-phase electric spring (ES). These objectives are the stabilization of the voltage across the critical load (CL) of a power system, and the achievement of a specific functionality similar to the pure compensation of reactive power or the correction of the power factor. However, existing control systems implementing the ${\delta}$ control do not cope with non-ideal operating conditions, such as line voltage distortions, and exhibit a somewhat sluggish regulation of the CL voltage. In an effort to improve both the steady-state and transient performances of an ES power system, this paper proposes implementing the ${\delta}$ control by means of a control system built up on the repetitive control and assisted by state feedback with pole assignment. This paper starts by analyzing the dynamics of an ES power system in terms of its poles and zeros. After that, a reduced second-order model of the dynamics is formulated to avoid a notch filter in the pole assignment. A repetitive control for an ES power system is then designed to meet the two above mentioned objectives. Experimental tests carried out on a laboratory setup demonstrate the effectiveness of the proposed control system in significantly improving the ES power system performance, while reaching the two objectives. In particular, the tests outline the large mitigation of harmonics in the CL voltage under line voltage distortions and its fast stabilization action.

• Earthquakes and Structures
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• 제9권6호
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• pp.1133-1152
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• 2015

A frequency-domain method is developed for evaluating the earthquake input energy to two building structures connected by viscous dampers. It is shown that the earthquake input energies to respective building structures and viscous connecting dampers can be defined as works done by the boundary forces between the subsystems on their corresponding displacements. It is demonstrated that the proposed energy transfer function is very useful for clear understanding of dependence of energy consumption ratios in respective buildings and connecting viscous dampers on their properties. It can be shown that the area of the energy transfer function for the total system is constant regardless of natural period and damping ratio because the constant Fourier amplitude of the input acceleration, relating directly the area of the energy transfer function to the input energy, indicates the Dirac delta function and only an initial velocity (kinetic energy) is given in this case. Owing to the constant area property of the energy transfer functions, the total input energy to the overall system including both buildings and connecting viscous dampers is approximately constant regardless of the quantity of connecting viscous dampers. This property leads to an advantageous feature that, if the energy consumption in the connecting viscous dampers increases, the input energies to the buildings can be reduced drastically. For the worst case analysis, critical excitation problems with respect to the impulse interval for double impulse (simplification of pulse-type impulsive ground motion) and multiple impulses (simplification of long-duration ground motion) are considered and their solutions are provided.

• Steel and Composite Structures
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• 제50권6호
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• pp.627-641
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• 2024

This paper presents an experimental and numerical study to investigate the behavior of the precast segmental concrete beams (PSCBs) utilizing high-strength concrete (HSC) connected in the zone of the maximum bending moment using steel extended endplate connections (EECs). The experimental study consisted of five beams as follows: The first beam was the control beam for comparison, which was an unconnected one-piece beam made of HSC. The other four other beams consisted of two identical pieces of precast concrete. An important point to be noted is that at the end of each piece, a steel plate was used with a thickness of 10 mm. Moreover, this steel plate was welded to the lower and upper reinforcing bars of the beam. Furthermore, the steel plate was made to connect the two pieces using the technique of EECs. Several variables were taken in these four beams, whether from the shape of the connection or enhancing the behavior of the connection using the post-tensioning technique. EECs without stiffeners were used for some of the tested beams. The behavior of these connections was improved using stiffeners and shear bolts. To get accurate results, a comparison was made between the behaviors of the five beams. Another important point to be noted is that Abaqus and SAP2000 programs were used to investigate the behavior of PSCBs and to ensure the accuracy of the modeling process which showed a good agreement with the experimental results. Additionally, the simplified modeling using SAP2000 was able to model the nonlinear behavior of PSCBs connected using steel EECs. It was found that the steel pre-tensioned bolted EECs, reinforced with steel stiffeners and shear anchors, could be used to connect the precast HSC segmental beams via the internal pre-stressing technique.

• 한국컴퓨터정보학회논문지
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• 제21권5호
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• pp.41-47
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• 2016

This paper considers simple polygon search problem. How many searchers find a mobile intruder that is arbitrarily faster than the searcher within polygon art gallery? This paper uses the visibility graph that is connected with edges for mutually visible vertices. Given visibility graph, we select vertex u that is conjunction ${\Delta}(G)$ in $N_G(v)$ for $d_G(v){\leq}4$. We decide 1-searchable if $1{\leq}{\mid}u{\mid}{\leq}2$ and 2-searchable if ${\mid}u{\mid}{\geq}3$. We also present searcher's shortest path. This algorithm is verified by varies 1 or 2-searchable polygons.