• Journal of Microbiology and Biotechnology
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• 제20권3호
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• pp.518-524
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• 2010

A mannanase gene (man26B) was obtained from a sea bacterium, Paenibacillus sp. BME-14, through the constructed genomic library and inverse PCR. The gene of man26B had an open reading frame of 1,428 bp that encoded a peptide of 475- amino acid residues with a calculated molecular mass of 53 kDa. Man26B possessed two domains, a carbohydrate binding module (CBM) belonging to family 6 and a family 26 catalytic domain (CD) of glycosyl hydrolases, which showed the highest homology to Cel44C of P. polymyxa (60% identity). The optimum pH and temperature for enzymatic activity of Man26B were 4.5 and $60^{\circ}C$, respectively. The activity of Man26B was not affected by $Mg^{2+}$ and $Co^{2+}$, but was inhibited by $Hg^{2+},\;Ca^{2+},\;Cu^{2+},\;Mn^{2+},\;K^+,\;Na^+$, and $\beta$-mercaptoethanol, and slightly enhanced by $Pb^{2+}$ and $Zn^{2+}$. EDTA did not affect the activity of Man26B, which indicates that it does not require divalent ions to function. Man26B showed a high specific activity for LBG and konjac glucomannan, with $K_m,\;V_{max}$, and $k_{cat}$ values of 3.80 mg/ml, 91.70 ${\mu}mol$/min/mg protein, and 77.08/s, respectively, being observed when LBG was the substrate. Furthermore, deletion of the CBM6 domain increased the enzyme stability while enabling it to retain 80% and 60% of its initial activity after treatment at $80^{\circ}C$ and $90^{\circ}C$ for 30 min, respectively. This finding will be useful in industrial applications of Man26B, because of the harsh circumstances associated with such processes.

• 지질공학
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• 제11권2호
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• pp.175-190
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• 2001

오염된 연약지반에 편재하중이 작용하는 경우에 있어서 지반의 소성화에 따른 측방유동에 대한 거동을 규명하기 위하여 기존의 이론적인 배경을 고찰하고, 모형실험을 통하여 실측한 결과를 상호 비교.분석하였다. 모형실험은 모형재하장치인 토조와 재하틀 및 재하판을 제작하여 토조 안에 함수비를 일정하게 유지한 상태에서 자연지반의 시료와 오염물질을 점진적으로 증가시킨 지반시료에 대하여 일정한 시간 간격으로 편재하중을 증가시키면서 침하량과 측방변위량 및 융기량 등을 관측하였다. 그 결과 한계하중은 실험값이 Tschebotarioff(q$_{cr}$=3.0$_{cu}$)의 제안값과 Meyerhof(q$_{cr}$=(B/2H+$\pi$/2)$_{cu}$)의 제안값에 근접하여 q$_{cr}$=2.78$_{cu}$값을 나타냈고, 극한하중은 Prandtl의 제안값에 근접하여 q$_{ult}$=4.84$_{cu}$값을 나타냈다. 측방유동압은 Matsui.Hong의 이론식에 의해서 산정함이 비교적 적절하며, 측방유동압의 최대값은 토층두께(H)의 0.3H 부근에서 발생하였으며, 복합형과 Poulos의 분포형태 및 오염되지 않는 연약점토(CL, CH)지반 보다 지표면측으로 상승하여 발생하였다. 안정관리방법은 지반의 측방유동에 의한 소성변위량을 많이 이용하고 있는 부영.교본, 자전.관구, 송미.천촌 등의 안정관리도에 적용한 결과 송미.천촌의{S$_{v}$-(Y$_{m}$/S$_{v}$)}관리도와 자전.관구의 {(q/Y$_{m}$)-q}관리도에서 얻어진 극한하중은 하중-침하량곡선 (q-S$_{v}$)에서 얻어진 극한하중 보다 적은 경향을 나타냈다.

• Steel and Composite Structures
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• 제24권2호
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• pp.213-226
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• 2017

The behavior of building industry metal sheeting under shear forces has been extensively studied and equations have been developed to predict its shear stiffness. Building design engineers can make use of these equations to design a metal deck form bracing system. Bridge metal deck forms differ from building industry forms by both shape and connection detail. These two factors have implications for using these equations to predict the shear stiffness of deck form systems used in the bridge industry. The conventional eccentric connection of bridge metal deck forms reduces their shear stiffness dramatically. However, recent studies have shown that a simple modification to the connection detail can significantly increase the shear stiffness of bridge metal deck form panels. To the best of the author's knowledge currently there is not a design aid that can be used by bridge engineers to estimate the stiffness of bridge metal deck forms. Therefore, bridge engineers rely on previous test results to predict the stiffness of bridge metal deck forms in bracing applications. In an effort to provide a design aid for bridge design engineers to rely on bridge metal deck forms as a bracing source during construction, cantilever shear frame test results of bridge metal deck forms with and without edge stiffened panels have been compared with the SDI Diaphragm Design Manual and ECCS Diaphragm Stressed Skin Design Manual stiffness expressions used for building industry deck forms. The bridge metal deck form systems utilized in the tests consisted of sheets with thicknesses of 0.75 mm to 1.90 mm, heights of 50 mm to 75 mm and lengths of up to 2.7 m; which are representative of bridge metal deck forms frequently employed in steel bridge constructions. The results indicate that expressions provided in these manuals to predict the shear stiffness of building metal deck form panels can be used to estimate the shear stiffness of bridge metal deck form bracing systems with certain limitations. The SDI Diaphragm Design Manual expressions result in reasonable estimates for sheet thicknesses of 0.75 mm, 0.91 mm, and 1.21 mm and underestimate the shear stiffness of 1.52 and 1.90 mm thick bridge metal deck forms. Whereas, the ECCS Diaphragm Stressed Skin Design Manual expressions significantly underestimate the shear stiffness of bridge metal deck form systems for above mentioned deck thicknesses.

• 한국강구조학회 논문집
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• 제13권4호
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• pp.363-372
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• 2001

본 연구의 목적은 보항복형 비가새 골조의 $P-{\Delta}$영향을 실험적 방법을 통하여 조사하는데 있다. 이를 위하여 4개의 1층 1스팬의 보항복형 비가새 골조에 대한 가력실험을 실시하였다. 실험의 변수로는 기둥의 강성과 축력비를 적용하였다. 실험결과 저축력 상태의 보항복형 비가새 골조에서는 축력의 정량적인 크기가 $P-{\Delta}$효과로서 골조의 안정성에 영향을 미치는 것으로 나타났다. 그리고 최대수평하중은 기둥의 강성과 지점 회전강성에 비례하여 증가하며 저축력상태의 보항복형 비가새 골조는 붕괴가구 형성이 비교적 안정적인 상태에서 이루어짐을 알 수 있었다. 그리고 한계상태설계기준의 $B_2$ 계수는 골조의 비탄성거동시 $P-\Delta$효과를 적절히 고려하지 못하는 것으로 판단된다.

• Journal of Microbiology and Biotechnology
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• 제20권6호
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• pp.995-1000
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• 2010

A novel deoC gene was identified from Paenibacillus sp. EA001 isolated from soil. The gene had an open reading frame (ORF) of 663 base pairs encoding a protein of 220 amino acids with a molecular mass of 24.5 kDa. The amino acid sequence was 79% identical to that of deoxyribose 5-phosphate aldolase (DERA) from Geobacillus sp. Y412MC10. The deoC gene encoding DERA was cloned into an expression vector and the protein was expressed in Escherichia coli. The recombinant DERA was purified using Ni-NTA affinity chromatography and then characterized. The optimum temperature and pH of the enzyme were $50^{\circ}C$ and 6.0, respectively. The specific activity for the substrate deoxyribose 5-phosphate (DR5P) was $62\;{\mu}mol/min/mg$. The $K_m$ value for DR5P was determined to be 145 mM with the $k_{cat}$ value of $3.2{\times}10^2/s$ from Lineweaver-Burk plots. The EA001 DERA showed stability toward a high concentration of acetaldehyde (100 mM).

• 대한의용생체공학회:의공학회지
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• 제28권3호
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• pp.429-440
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• 2007

A coded excitation has been studied to improve the performance for ultrasound imaging in term of SNR, imaging frame rate, contrast to tissue ratio, and so forth. However, it requires a complicated arbitrary waveform transmitter for each active channel that is typically composed of a multi-bit Digital-to-Analog Converter (DAC) and a linear power amplifier (LPA). Not only does the LPA increase the cost and size of a transmitter block, but it consumes much power, increasing the system complexity further and causing a heating-up problem. This paper proposes an optimized 1.5bit fourth order sigma-delta modulation technique applicable to design an efficient arbitrary waveform generator with greatly reduced power dissipation and hardware. The proposed SDM can provide a required SQNR with a low over-sampling ratio of 4. To this end, the loop coefficients are optimized to minimize the quantization noise power in signal band while maintaining system stability. In addition, the decision level for the 1.5 bit quantizer is optimized for a given input waveform, which results in the SQNR improvement of more than 5dB. Computer simulation results show that the SQNR of a FM(frequency modulated) signal generated by using the proposed method is about 26dB, and the peak side-lobe level (PSL) of its compressed waveform on receive is -48dB.

• 수산해양기술연구
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• 제42권4호
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• pp.217-227
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• 2006

This research aims at establishing the application of canvas kite to the fishing gear through the analysis of the lift/drag tests of the kites have been performed in our previous finding. Now that several methodologies were designed to find the most effective triangular model as a buoyancy device applied to the fishing gear. Comparisons of drag/lift were made by installing the model in an installation frame instead of the prototype. Also, we have considered the application of canvas kite to the prototypic fishing gear by calculation using the result of this test. The results obtained from the above approaches are summarized as follows, where attack angle, lift coefficient, maximum lift coefficient and drag coefficient are denoted as $B,\;C_L,\;C_Lmax\;and\;C_D$ respectively. The camber showed a gradual increase with an increase of fluid velocity. There was a big discrepancy in B=20 unlike B=30. Even if the kite retreats along the fluid flow, there is little relationship with the velocity variation. Lifts calculated with the kites were bigger and drags were smaller than those of the calculations with the float only. The kite as the buoyancy device will be very useful when the appropriate applications and the stability are met.

• Steel and Composite Structures
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• 제9권5호
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• pp.419-444
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• 2009

Flange and web local buckling in beam plastic hinge regions of steel moment frames can prevent beam-column connections from achieving adequate plastic rotations under earthquake-induced forces. Reducing the flange-web slenderness ratios (FSR/WSR) of beams is the most effective way in mitigating local member buckling as stipulated in the latest seismic design specifications. However, existing steel moment frame buildings with beams that lack the adequate slenderness ratios set forth for new buildings are vulnerable to local member buckling and thereby system-wise instability prior to reaching the required plastic rotation capacities specified for new buildings. This paper presents results from a research study investigating the cyclic behavior of steel I-beams modified by a welded haunch at the bottom flange and reinforced with glass fiber reinforced polymers at the plastic hinge region. Cantilever I-sections with a triangular haunch at the bottom flange and flange slenderness ratios higher then those stipulated in current design specifications were analyzed under reversed cyclic loading. Beam sections with different depth/width and flange/web slenderness ratios (FSR/WSR) were considered. The effect of GFRP thickness, width, and length on stabilizing plastic local buckling was investigated. The FEA results revealed that the contribution of GFRP strips to mitigation of local buckling increases with increasing depth/width ratio and decreasing FSR and WSR. Provided that the interfacial shear strength of the steel/GFRP bond surface is at least 15 MPa, GFRP reinforcement can enable deep beams with FSR of 8-9 and WSR below 55 to maintain plastic rotations in the order of 0.02 radians without experiencing any local buckling.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2000년도 Proceedings of 2000 KSAM International Symposium and Spring Meeting
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• pp.157-167
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• 2000

A thermostable chitosanase gene from the isolated strain, Bacillus sp. CK4, was cloned, and its complete DNA sequence was determined. The thermostable chitosanase gene was composed of an 822-bp open reading frame which encodes a protein of 242 amino acids and a signal peptide corresponding to a 30 kDa enzyme in size. The deduced amino acid sequence of the chitosanase from Bacillus sp. CK4 exhibits 76.6%, 15.3%, and 14.2% similarities to those from Bacillus subtilis, Bacillus ehemensis, and Bacillus circulans, respectively. C-terminal homology analysis shows that Bacillus sp. CK4 belongs to the Cluster III group with Bacillus subtilis. The size of the gene was similar to that of a mesophile, Bacillus subtilis showing a higher preference for codons ending in G or C. The functional importance of a conserved region in a novel chitosanase from Bacillus sp. CK4 was investigated. Each of the three carboxylic amino acid residues were changed to E50D/Q, E62D/Q, and D66N/E by site-directed mutagenesis. The D66N/E mutants enzymes had remarkably decreased kinetic parameters such as $V_{max}$ and k$\sub$cat/, indicating that the Asp-66 residue was essential for catalysis. The thermostable chitosanase contains three cysteine residues at position 49, 72, and 211. Titration of the Cys residues with DTNB showed that none of them were involved in disulfide bond. The C49S and C72S mutant enzymes were as stable to thermal inactivation and denaturating agents as the wild-type enzyme. However the half-life of the C211S mutant enzyme was less than 60 min at 80$^{\circ}C$, while that of the wild type enzyme was about 90 min. Moreover, the residual activity of C211S was substantially decreased by 8 M urea, and fully lost catalytic activity by 40% ethanol. These results show that the substitution of Cys with Ser at position 211 seems to affect the conformational stability of the chitosanase.

• 한국항행학회논문지
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• 제13권3호
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• pp.327-336
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• 2009

본 논문은 항공 무선 데이터 통신의 STDMA MAC 프로토콜 방식을 분석하여 모델링하고, 시뮬레이션을 통하여 성능 검증을 수행하였다. 현재 VDL Mode 4에서 사용하는 STDMA 프로토콜은 하나의 프레임을 여러 개의 슬롯으로 시분할 하여 사용하는 TDMA 시스템 특성을 갖는다. 모델링한 STDMA 프로토콜의 데이터 채널 성능 분석 결과 처리효율 면에서는 전송확률 0.045, 0.2, 0.3에서 모두 0.7에 가까운 채널 효율을 나타냈으며, 그때의 지연시간은 각각 2.32434sec, 2.0293sec, 2.12128sec로 일정한 지연시간을 나타내어 안정적인 성능을 나타내는 것으로 분석되었다. 따라서 STDMA 프로토콜을 앞으로의 CNS/ATM 기반기술로 점-대-점 통신과 데이터/위치 방송에 적용함으로서 항공교통량 증가에 따른 국내 통신수요와 감시체제 개선요구에 효과적으로 대처할 수 있을 것이라 기대된다.