• Steel and Composite Structures
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• 제34권5호
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• pp.625-641
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• 2020

The realistic modeling of the beam-column semi-rigid connection in steel frames attracted the attention of many researchers in the past for the seismic analysis of semi-rigid frames. Comparatively less studies have been made to investigate the behavior of steel frames with semi-rigid connections under different types of earthquake. Herein, the seismic behavior of semi-rigid steel frames is investigated under both far and near-field earthquakes. The semi-rigid connection is modeled by the multilinear plastic link element consisting of rotational springs. The kinematic hysteresis model is used to define the dynamic behavior of the rotational spring, describing the nonlinearity of the semi-rigid connection as defined in SAP2000. The nonlinear time history analysis (NTHA) is performed to obtain response time histories of the frame under scaled earthquakes at three PGA levels denoting the low, medium and high-level earthquakes. The other important parameters varied are the stiffness and strength parameters of the connections, defining the degree of semi-rigidity. For studying the behavior of the semi-rigid frame, a large number of seismic demand parameters are considered. The benchmark for comparison is taken as those of the corresponding rigid frame. Two different frames, namely, a five-story frame and a ten-story frame are considered as the numerical examples. It is shown that semi-rigid frames prove to be effective and beneficial in resisting the seismic forces for near-field earthquakes (PGA ≈ 0.2g), especially in reducing the base shear to a considerable extent for the moderate level of earthquake. Further, the semi-rigid frame with a relatively weaker beam and less connection stiffness may withstand a moderately strong earthquake without having much damage in the beams.

• 한국미생물·생명공학회지
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• 제30권3호
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• pp.264-269
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• 2002

Zoogloea ramigera l15SLR로부터 zooglan다당류의 생산을 위한 최적조건에 관한 연구를 수행하였다 탄소원으로 2.5%의 glucose와 lactose를 이용하였을 때 각각 10.7, 10.5 g/L의 다당류를 생산하였으며 , galactose, white sugar, brown sugar의 경우는 각각 6.4, 6.7, 8.7 g/L의 다당류 생산 을 보였다. 2.5% glucose가 첨가된 제한배지에서 종균 배양액(TSB 배지)을 7ml 이상 접종함으로서 종균 1 ml를 접종 하석 생산된 다당류(2.37 gt) 보다 약 4배의 높은 다당류 생산(10.28 g/L)을 보였다. 종균 배양액을 5 ml이상 접종시에 배양 36시간 이후부터 다당류를 생산하였으며 48시간 배양시에 10g/L이상의 다당류 생산이 가능하였다. 탄소원으로서 또한, 종균 배양액의 흡광도가 1.0~l.7일 경우에 10g/L 이상의 다당류를 생산하였으며, 이 범위를 벗어나는 경우에는 다당류 생산이 저해되었다. 배양액에 rifampicin첨가는 12 g/L이상의 다당류 생산을 보였으며, 다당류 분자량은 1.367$\times$106(g/mol)로서 rifampicin을 가하지 경우 1.711$\times$106(g/mol)와 약간의 차이를 보였다.

• Journal of Microbiology and Biotechnology
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• 제23권9호
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• pp.1327-1338
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• 2013

The humanized anti-hepatocyte growth factor (HGF) monoclonal antibody (mAb) YYB-101 is a promising therapeutic candidate for treating various cancers. In this study, we developed a bioprocess for large-scale production of YYB-101 and evaluated its therapeutic potential for tumor treatment using a xenograft mouse model. By screening diverse chemically defined basal media formulations and by assessing the effects of various feed supplements and feeding schedules on cell growth and antibody production, we established an optimal medium and feeding method to produce 757 mg/l of YYB-101 in flask cultures, representing a 7.5-fold increase in titer compared with that obtained under non-optimized conditions. The optimal dissolved oxygen concentration for antibody production was 70% $pO_2$. A pH shift from 7.2 to 7.0, rather than controlled pH of either 7.0 or 7.2, resulted in productivity improvement in 5 L and 200 L bioreactors, yielding 737 and 830 mg/ml of YYB-101, respectively. The YYB-101 mAb highly purified by affinity chromatography using a Protein A column and two-step ion exchange chromatography effectively neutralized HGF in a cell-based assay and showed potent tumor suppression activity in a mouse xenograft model established with human glioblastoma cells.

• 한국IT서비스학회지
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• 제17권2호
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• pp.1-16
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• 2018

Large corporations have the work and roles of employees clearly defined in accordance with their established internal structure whereas small and mid-sized firms may lack an official job specification or a written job description, causing ambiguity in the role of employees. In IT service companies, especially, there is a relatively large number of tasks requiring one person to play multiple roles and they are often highly dependent on few key players. In this reality where about 80% of the job seekers end up in SMEs, it is therefore necessary to look into how the turnover factors such as job strain and occupational burnout caused by the role ambiguity from extra work affect the turnover intentions of small and medium sized IT service firm employees. The outcome of this study is as follows. First, the relationship between job strain and turnover intention has been examined to find that a weak inverted U shaped relationship exists between role overload, which is a subset of job strain, and turnover intention. Second, the hypothesis based on the competing values framework has been tested that the fitness with organizational leadership and culture would moderate the relationship between job strain and turnover intention and it has been confirmed that the degree of relationship between role conflict and role ambiguity, the subsets of job strain, and turnover intention has changed. In conclusion, in order to discourage turnover intention, it is necessary to increase the fitness with the organization and leadership or generate a sufficient level of strain in case of an organization with low fitness.

• 한국통신학회논문지
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• 제31권12B호
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• pp.1058-1067
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• 2006

무선 인지 기술 환경에서 CR 기지국이 숨겨진 인컴번트 시스템의 등장으로 인해 CR 사용자와 통신이 불가하고 인컴번트 사용자가 간섭을 받을 때, 이를 해결하기 위한 시그널링 방법에 관한 것으로 숨겨진 인컴번트 시스템의 검출을 위한 프로토콜을 제안한다. 특히 아웃밴드 시그널링 검출 방법을 통해 상향링크 및 하향링크 프레임 구조를 이용하여 단말의 채널상태 보고 방법과 이에 대한 기지국의 확인방법 및 절차를 제안한다. 서로 다른 CR 기지국이 공존하는 방법으로 낮은 충돌 확률로 아웃밴드 시그널링 메시지를 전송할 수 있도록 하고 이 때 주파수 사용 효율을 높이기 위해 분할 주파수 대역을 사용한다. 이를 통해 무선 인지 기술에서의 신뢰성 있고 효율적인 아웃밴드 시그널링 프로토콜을 제안한다.

• Archives of Pharmacal Research
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• 제28권1호
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• pp.120-126
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• 2005

The objective of this study was to investigate the effects of sodium lauryl sulfate upon the saturation solubility of carbamazepine, its dissolution kinetics, and $T_{50\%}$ defined as the time required for dissolving $50\%$ of carbamazepine. Water, 0.1N-HCI, and phosphate buffers at pH 4.0 and 6.8 containing 0.1, 0.5, 1, and $2\%$ sodium lauryl sulfate were used as dissolution media. The dissolution study was conducted by using the USP dissolution apparatus II with an agitation rate of 75 rpm. Samples of the dissolution media were taken in 7, 15, 30, 45, 60, 75, and 90 min, and the amounts of carbamazepine were determined spectrophotometrically at 285 nm. All dissolution data were fitted well into a four-parameter exponential equation: $Q\;=\;a(1\;-\;e^{-bxt})\;+\;c(1\;-\;e^{-dxt})$. In this equation Q represented $\%$ carbamazepine dissolved at a time t, and a, b, c, and d were constants. This equation led to the calculation of dissolution rates at various time points and $T_{50\%}$. It was found that the dissolution rate of carbamazepine was directly proportional to the aqueous concentration of sodium lauryl sulfate. In addition, under our experimental conditions $T_{50%}$ values ranged from 37.8 to 4.9 min. It was interesting to note that $T_{50\%}$ declined rapidly as the surfactant concentration increased from 0.1 to $0.5\%$, whereas it declined more slowly at concentrations greater than $1\%$. These results clearly demonstrated that the dissolution rate of carbamazepine and duration of its dissolution test could be tailored by optimizing the amount of sodium lauryl sulfate in a dissolution medium.

• 한국정보통신학회논문지
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• 제13권5호
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• pp.922-930
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• 2009

유도 전동기를 전압 제어하기 위한 최적 PWM 스위칭 방법을 제시하려한다. 전압 인버터의 공간 벡터 변조 방식은 DC-버스 이용을 향상시키고 정류 손실을 감소시키기 때문에 디지털 구현의 경우 특히 선호하는 PWM 방법이다. 유도 전동기 전압 제어를 위한 최적 PWM 스위칭 방법은 제시한 최적 PWM 알고리즘을 사용하여 두 개의 활성 전압 벡터(active voltage vector)와 하나의 영 전압 벡터(zero voltage vector)로 구성하였다. 선택된 스위칭 순차 열은 변조 지수(modulation index)와 운송파(carrier wave) 주기의 함수로 정의 된다. 순차 열은 인버터 스위칭 손실과 전류 리플 값을 기준으로 사용하여 선택된다. 실험 결과 중 저 전력용으로 사용할 경우 스위칭 주파수를 증가시킴에 따라 고조파 왜곡이 감소하고 동특성이 좋아짐을 확인할 수 있었다.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2004년도 제5회 정기학술발표대회 논문집
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• pp.462-467
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• 2004

설계와 시공을 단일 업체가 일괄책임을 지는 턴키발주제도는 '96년 정부의 턴키활성화 대책 수립 후 대형국책사업을 위주로 그 적용이 확대되어 왔다. 그러나 업체간 과다 수주 경쟁과 대형업체들의 수주편중현상 등이 부각되면서 시민 단체와 중소기업을 중심으로 턴키/대안입찰제도에 대한 축소 적용 또는 최저가 제도로의 흡수통합방안 등이 제시되기에 이르렀다. 이에 따라 이에 따라 본 논문에서는 그 동안 국내에서 완료되었거나 진행 중인 51건의 턴키/대안 공사에 대해 시공자와 발주자에게 공기, 공사비, 품질, 신기술 적용정도 조사와 시공업체의 턴키/대안 입찰제도에 대한 의견 조사를 통해 턴키/대안 공사에 대한 객관적인 성과평가와 턴키/대안 입찰제도에 대한 실무자들의 인식을 파악하여 제도의 실효성을 평가해 보고 국내 턴키/대안 제도의 개선방안에 대해 제시해 보고자 한다.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.255-259
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• 2002

To reduce the uncertainty in the calibration of radiation beams, absorbed dose to water for high energy electrons is recommended as the standards and reference absorbed dose by AAPM Report no.51 and IAEA Technical Reports no.398. In these recommendations, water is, defined as the reference medium, however, the water substitute solid phantoms are discouraged. Nevertheless, when accurate chamber positioning in water is not possible, or when no waterproof chamber is available, their use is permitted at beam qualities R$\_$50/ < 4 g/cm$^2$ (E$\_$0/ < 10 MeV). For the electron dosimetry using solid phantom, a depth-scaling factor is used for the conversion of depth in solid phantoms to depth in water, and a fluence-scaling factor is used for the conversion of ionization chamber reading in plastic phantom to reading in water. In this work, the properties, especially depth-scaling factors c$\_$p1/ and fluence-scaling factors h$\_$pl/ of several commercially available water substitute solid phantoms were determined, and the electron dosimetry using these scaling method was evaluated. As a result, it is obviously that dose-distribution in solid phantom can be converted to appropriate dose-distribution in water by means of IAEA depth-scaling.

• Coupled systems mechanics
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• 제6권3호
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• pp.229-249
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• 2017

A new technique to mitigate irregular buildings with soil structure interaction (SSI) effect subjected to critical seismic waves is presented. The L-shape in plan irregular building for various reasons was selected, subjected to seismic a load which is a big problem for structural design especially without separation gap. The L-shape in plan building with different dimensions was chosen to study, with different rectangularity ratios and various soil kinds, to show the effect of the irregular building on the seismic response. A 3D building subjected to critical earthquake was analyzed by structural analysis program (SAP2000) fixed and with SSI (three types of soils were analyzed, soft, medium and hard soils) to find their effect on top displacement, base shear, and base torsion. The straining actions were appointed and the treatment of the effect of irregular shape under critical earthquake was made by using tuned mass damper (TMD) with different configurations with SSI and without. The study improve the success of using TMDs to mitigate the effect of critical earthquake on irregular building for both cases of study as fixed base and raft foundation (SSI) with different TMDs parameters and configurations. Torsion occurs when the L-shape in plan building subjected to earthquake which may be caused harmful damage. TMDs parameters which give the most effective efficiency in the earthquake duration must be defined, that will mitigate these effects. The parameters of TMDs were studied with structure for different rectangularity ratios and soil types, with different TMD configurations. Nonlinear time history analysis is carried out by SAP2000 with El Centro earthquake wave. The numerical results of the parametric study help in understanding the seismic behavior of L-shape in plan building with TMDs mitigation system.