• Journal of Microbiology and Biotechnology
• /
• 제14권2호
• /
• pp.225-230
• /
• 2004

A plasminogen kringle domain 1 to 3, rKl-3, was expressed in Escherichia coli under the control of T7 promoter. For the cost-effective production of rKl-3, the induction process was analyzed and optimized. Induction characteristics with lactose were analyzed in terms of induction time and inducer concentration in various culture conditions including batch and high-cell-density fed-batch cultures. In the fed-batch culture, the induction around 6 h after initiation of the DO-stat fed-batch culture resulted in the highest expression level of rKI-3 among the induction points examined. The highest demand of oxygen at this point was crucial for the maximum expression level of rKI-3. As the lactose concentration increased, the expression level also increased, though the expression level showed a plateau above a concentration of 14 mM of lactose. Lactose acted less specifically than IPTG since most of it was hydrolyzed to glucose and galactose. However, using lactose, the cell growth and the maximum expression level of rKl-3 increased by 20% and 24%, respectively, compared with those using IPTG in the fed-batch culture. The lactose seemed to be hydrolyzed by intracellular and extracellular $\beta$-galactosidase liberated by cell lysis at the same time. Residual concentration of glucose was maintained to a a limit of detection by high performance liquid chromatography, and galactose was not consumed by the host strain Escherichia coli BL2l(DE3).

• 열처리공학회지
• /
• 제9권1호
• /
• pp.1-11
• /
• 1996

Mechanical alloying is an effective process to finely distribute inert dispersoids in an Al-TM(TM is a transition metal) system. It has been considered that high melting point aluminides are formed by precipitation from supersaturated Al(Ti) powder. This analysis is based on the fact that much higher content of TM than the solubioity can be dissolved in alpha aluminum during the high energy ball milling. Thus, decomposition behavior of Ti in the Al(Ti) was considered very important. But it is confirmed that the higher portion of Ti than Al(Ti) solid solution is existed as nano-sized Ti particles in the MA powders by high energy ball nilling from the XRD spectrum and TEM analysis in this study. Therefore, the role of undissolved TM particles affect the formation of aluminides should be suitably considered. In this study, we present experimental observation on the formation of $Al_3Ti$ fron mechanical alloyed Al-Ti alloys in the hyperperitectic region. This study showed that, in the mechanically alloyed Al-20wt%Ti specimen, intermediate phase of cubic $Al_3Ti$ and tetragonal $Al_{24}Ti_8$ formed at $300{\sim}400^{\circ}C$ and $400{\sim}500^{\circ}C$, respectively, before the MA state reaches to equilibrium at higher temperatures. The formation behavior of $Ll_2-Al_3Ti$ is interpreted by interdiffusion of Al and Ti in solid state based on the fact that large amount of nano-sized Ti particles exist in the milled powder. Present analysis indicated undissolved Ti particles of nanosize should have played an important role initiation the formation of $Al_3Ti$ phase during annealing.

• Journal of Welding and Joining
• /
• 제35권2호
• /
• pp.23-29
• /
• 2017

Mechanical properties and hardness distributions in arc brazed joints of Dual phase steel using Cu-Al insert metal were investigated. The maximum tensile shear load was 10.4kN at the highest brazing current. It was about 54% compared to tensile load of base metal. This joint efficiency is higher than that of joint of DP steel using Cu-based filler metals which are Cu-Si, Cu-Sn. Fracture positions can be divided into two types. Crack initiation commonly occurred at three point junction among upper sheet, lower sheet and the fusion zone. However crack propagations were different with increasing the brazing current. In case of the lower current, it instantaneously propagated along with the interface between fusion zone and upper base material. On the other hand, in case of higher current, a crack propagation occurred through fusion zone. When the brazing current is low (60, 70A), the interface shape is flat type. However the interface shape is rough type, when the brazing current is high (80A). It is thought that the interface shapes were the reason why the crack propagations were different with brazing current. The interface was the intermetallic compounds which consisted of $(Fe,Al)_{0.85}Cu_{0.15}$ IMC formed by crystallization at $1200^{\circ}C$during cooling. Therefore the maximum tensile shear load and the fracture behavior were determined by a interface shape and effective sheet thickness of the fracture position.

• Journal of Microbiology
• /
• 제43권1호
• /
• pp.44-48
• /
• 2005

In our previous study, the first structural gene (GGTI) encoding ${\gamma}-glutamyl$ transpeptidase was cloned and characterized from the fission yeast Schizosaccharomyces pombe, and its transcription, using the GGTI-lacZ fusion gene, containing the 1,085 bp upstream region from the translational initiation point, was found to be enhanced by sodium nitroprusside and L-buthionine-(S,R)-sulfoximine (BSO). In the present work, regulation of the GGTI gene was further elucidated. Non-fermentable carbon sources, such as acetate and ethanol, markedly enhanced the synthesis of ${beta}-galactosidase$ from the GGTI-lacZ fusion gene. However, its induction by non-fermentable carbon sources appeared to be independent of the presence of the Pap1 protein. Nitrogen starvation also gave rise to induction of GGTI gene expression in a Pap1-independent manner. The three additional fusion plasmids, carrying 754, 421 and 156 bp regions, were constructed. The sequence responsible for the induction by non-fermentable carbon sources and nitrogen starvation was identified to exist within a -421 bp region of the GGTI gene. Taken together, the S. pombe GGTI gene is regulated by non-fermentable carbon sources and nitrogen starvation.

• 열처리공학회지
• /
• 제6권3호
• /
• pp.166-177
• /
• 1993

Bending fatigue strength tests were made for VC coated die steels which were coated by immersing in a molten borax bath and for hardened die steels which were quenched and tempered, in order to clarify the effect of VC coating at $1000^{\circ}C$ and $1025^{\circ}C$. The material used in this investigation was a representative cold and hot die steels STD11, STD61. The results obtained are as follows. 1) The endurance limit of VC coated die steels was a little lower than that of hardened die steels. It is considered to be mainly due to the decfl.lase of hardness in the substrates. Accordingly, the endurance limit reo covered almost to the level of hardened die steels by an additional diffusion treatment. 2) The initiation point of fatigue fracture of VC coated die steels in reversed bening was on the substrate just under the VC layer. Hence, the endurance limit is corrected to the hardness of this part. 3) But, there is a considerable scatter in this relationship and the endurance limit of VC coated die steels was a little lower than that of hardened die steels with equal hardness. These results suggest that the fatigue strength of VC coated die steels is determined not only by the hardness but also by other factors. For example. the residual stress in the substrate just under VC coating layer is one of the factors besides hardness which is mainly related to the retained austenite(${\gamma}_R$).

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2017년도 학술발표회
• /
• pp.260-260
• /
• 2017

This study aims to compare the performance of TRIGRS (Transient Rainfall Infiltration and Grid-based Regional Slope-stability model) and TiVaSS (Time-variant Slope Stability model) in the prediction of rainfall-induced shallow landslides. TRIGRS employs one-dimensional (1-D) subsurface flow to simulate the infiltration rate, whereas a three-dimensional (3-D) model is utilized in TiVaSS. The former has been widely used in landslide modeling, while the latter was developed only recently. Both programs are used for the spatiotemporal prediction of shallow landslides caused by rainfall. The present study uses the July 2011 landslide event that occurred in Mt. Umyeon, Seoul, Korea, for validation. The performance of the two programs is evaluated by comparison with data of the actual landslides in both location and timing by using a landslide ratio for each factor of safety class ( index), which was developed for addressing point-like landslide locations. In addition, the influence of surface flow on landslide initiation is assessed. The results show that the shallow landslides predicted by the two models have characteristics that are highly consistent with those of the observed sliding sites, although the performance of TiVaSS is slightly better. Overland flow affects the buildup of the pressure head and reduces the slope stability, although this influence was not significant in this case. A slight increase in the predicted unstable area from 19.30% to 19.93% was recorded when the overland flow was considered. It is concluded that both models are suitable for application in the study area. However, although it is a well-established model requiring less input data and shorter run times, TRIGRS produces less accurate results.

• 공업화학
• /
• 제22권3호
• /
• pp.296-300
• /
• 2011

본 연구에서는 열병합 발전소의 원료로서 목질계 바이오매스로 임목 부산물, 폐목재, 야자수 부산물, 야자수 껍질의 연소 특성을 조사하기 위하여 열중량 분석기를 이용하여 연소 실험을 수행하였다. 목질계 바이오매스의 비교군으로는 일반적인 석탄을 사용하였다. 열중량 분석기 결과로부터, 목질계 바이오매스의 연소는 석탄과 비교하여 낮은 온도인 $280^{\circ}C$에서 $420^{\circ}C$ 구간에서 가장 활발한 연소반응을 보였음을 확인 할 수 있었다. 열중량분석에 의하여 측정된 활성화 에너지에 있어서 임목 부산물은 석탄 및 기타 목질계 바이오매스와 비교하여 가장 낮은 활성화 에너지 값을 나타내었으며, 또한 목질계 바이오매스의 경우 석탄과 비교하여 연소반응속도가 크게 증가함을 확인 할 수 있었다. 이는 목질계 바이오매스의 높은 연소개시 속도를 보이는 것을 나타내며, 이러한 결과는 석탄과 비교하여 낮은 비등점의 휘발분을 많이 포함하는 목질계 바이오매스의 특성에 기인하는 것으로 판단된다.

• 한국건설순환자원학회논문집
• /
• 제10권2호
• /
• pp.143-151
• /
• 2022

동결융해에 의한 콘크리트 손상 발생 시기를 평가하기 위하여 상대동탄성계수와 표면반발경도를 이용하여 비교하였다. 비교 결과 W/C 70 실험체군에서는 표면반발경도에 의한 콘크리트 손상 발생 평가가 200 싸이클 이상 빠르게 나타나는 것으로 관찰되었다. 뿐만 아니라 이후 점점 심해지는 동해를 표현할 수 있는 데이터를 지속적으로 제공해주어 동해 발생하는 초기 시점부터 동해를 확인할 수 있다는 것을 나타냈다. W/C 60과 50 실험체군에서도 표면반발경도가 콘크리트 동해 손상을 상대동탄성계수 보다 빠르게 평가했으며, 물-시멘트비에 변화에 상관없이 전반적으로 동결융해 손상시기 상대적으로 빠르고 정확하게 평가한 것으로 판단된다.

• 수산해양기술연구
• /
• 제20권1호
• /
• pp.30-36
• /
• 1984

대규모의 소성역을 동반하면서 파괴하는 고인성 재료의 탄소성 파괴 반가를 위하여 제안된 바 있는 CPE 모형의 유효성을 입증하고자 소성역의 영향을 보정한 선형 파괴역학과의 이론적 검토와 오오스테나이트계 스테인레스강에 대한 실험적 비교검토를 통하여 얻은 결론은 다음과 같다. 예측한 바와 같이 선형 파괴역학의 적용은 소규모 항복조건이 성립하는 경우에만 가능하며 CPE 모형은 대변형을 형성하면서 파괴하는 경우의 파괴모형으로서 유효하다. 더욱 엄밀한 유효성을 입증하기 위하여 다음의 사항이 필요하다고 본다. 1. 크랙의 길이가 짧은 시험편에 대한 실험이 필요하다. 2. 크랙성장 개시점을 정확하게 찾을 수 있는 방법이 필요하다. 3. 파괴 진행영역에 대한 두께의 영향을 고려해 보아야 할 필요성이 있다.

• Journal of Sport and Applied Science
• /
• 제7권2호
• /
• pp.1-12
• /
• 2023

Purpose: The purpose of this study was to investigate the possibility of modified swing to prevent shoulder injury by analyzing differences in the muscle activation patterns of upper limb by the swing method in wheelchair badminton players. Research design, data, and methodology: 10 wheelchair badminton players participated in the experiment as subjects and performed 10 high clears and 10 smashes in both traditional and modified swing methods toward a shuttlecock hung at the height of racket impact point. For each trial, activation patterns of biceps brachii, triceps brachii, anterior deltoid, and posterior deltoid were measured from the upper limb participating in the swing from which the duration, peak, and root mean square (RMS) of electromyography (EMG) activities from swing initiation to shuttle impact were calculated. The maximum swing velocity of the smash and the distance of the high clear were also measured with both methods to compare differences in the swing velocity and shuttle hit distance. Results: Differences in the EMG peak and RMS of the anterior deltoid by swing methods were shown to differ by the skill type, being higher in the traditional swing method than the modified during only the high clear. The EMG peak and RMS, and the duration of the posterior deltoid were higher and longer with the traditional swing method than the modified during both the smash and high clear. The intensities of the biceps brachii and triceps brachii activities measured during the smash and high clear were higher in the traditional swing method than the modified, and the biceps brachii and triceps activity durations during the high clear were shorter in the modified swing method than the traditional. The maximum swing velocity of the smash was faster with the traditional swing method than the modified, while the distance of the high clear did not differ significantly. Conclusions: These results suggest that the modified swing can be an effective performance method for preventing shoulder injuries without undue loss of impact power in wheelchair badminton players by reducing excessive loads imposed on the shoulder and allowing the optimal use of the elbow extension.