• Journal of Welding and Joining
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• 제19권3호
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• pp.298-304
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• 2001

Turbine blade is subject to force of three types ; the torsional force by torsional mount, the centrifugal force by the rotation of rotor and the cyclic bending force by steam pressure. The cyclic bending force was a main factor on fatigue strength. SEM fractography in root of turbine blade showed micro-clack width was not dependent on stress intensity factor range. Especially, fatigue did not exist on SEM photograph in root of turbine blade. To clear out the fracture mechanism of turbine blade, nanofractography was needed on 3-dimensional crack initiation and crack growth with high magnification. Fatigue striation partially existed on AFM photograph in root of turbine blade. Therefore, to find a fracture mechanism of the torsion-mounted blade in nuclear power plant, the relation between stress intensity factor range and surface roughness measured by AFM was estimated, and then the load amplitude ΔP applied to turbine blade was predicted exactly by root mean square roughness.

• 한국통신학회논문지
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• 제40권9호
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• pp.1793-1801
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• 2015

최근 KRLS-T라고 하는 커널 기반의 RLS 알고리즘이 제안되었다. 이 알고리즘은 비정재 환경에서 베이지안 이론에 기반한 망각 기저를 사용하고 있다. 이런 망각 기저의 핵심은 고정 망각인자를 사용하는 것이다. 그러나 실제 환경에서는 시스템의 비정재 정도까지도 시변인 경우가 많다. 이 경우 고정 망각인자로는 시스템의 바른 추정이 불가하다. 본 논문에서는 가변 망각인자를 사용한 KRLS-T를 제안한다. 그리고 모의 실험에서 가변 망각인자를 가진 KRLS-T가 시변 시스템의 추정에 더 효과적임을 보인다.

• Biomolecules & Therapeutics
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• 제30권1호
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• pp.64-71
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• 2022

Norovirus (NV) is the most common cause of viral gastroenteritis, with the potential to develop into a fatal disease in those who are immuno-compromised, and effective vaccines and treatments are still non-existent. In this study, we aimed to elucidate the molecular mechanism of the previously identified NV replication inhibitor utilizing a vinyl-stilbene backbone, AC-1858. First, we confirmed the inhibition of the NV RNA replication by a structural analog of AC-1858, AC-2288 with its exclusive cytoplasmic sub-cellular localization. We further validated the induction of one specific host factor, the phosphorylated form of heat shock factor (HSF)-1, and its increased nuclear localization by AC-1858 treatment. Finally, we verified the positive and negative impact of the siRNA-mediated downregulation and lentivirus-mediated overexpression of HSF-1 on NV RNA replication. In conclusion, these data suggest the restrictive role of the host factor HSF-1 in overall viral RNA genome replication during the NV life cycle.

• 경영과정보연구
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• 제36권5호
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• pp.1-26
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• 2017

그 동안의 기업 정보화 성과 관련 연구들은 정보화 자체의 구축 완성도 및 그 재무적 효과에 초점을 맞추고 있어 정보화의 방향성이 경영전략을 지원할 수 있는지에 대한 연구가 미흡하였다. 기업의 정보화를 통해 기업의 경영전략 이행이 주도될 수 있는지, 주요 메커니즘 요인과 정보화 성과와의 연관관계 대한 검증이 필요하며, 이는 정보화 성공요인들을 경영학적 관점으로 재해석하는 연구가 필요하다는 것을 의미한다. 본 연구는 국내 대표적인 IT서비스 기업의 사례를 중심으로 3가지 선택, 학습 그리고 조정 메커니즘 관점에서 기업이 정보화 성과창출 과정에서 어떠한 메커니즘 요인이 적용되고 있는지에 대한 문제를 중심으로 연구하였다. 본 연구를 수행한 결과 8개의 명제를 도출하였다. 기업의 주체는 정보화 성과 실현을 위해 조직의 정보역량 확보를, 조직 분권화 문제 해결을 위해서는 정보화 투자를 가장 중요한 전략적 요인으로 선택하였다. 또한, 산업 내 경쟁이 치열해질수록 정보화 투자가 기업의 전략 실행의 활용 수단으로 전환되었고, 공식화된 프로세스나 정보기술을 통해 투자 의사결정 활동이 이루어지고 있었다. 조직의 차별화된 역량은 기술지식 습득을 중심으로 이루어지며 조직의 지식은 정보시스템을 통해 전사로 확대되고 있음을 알 수 있었다. 그리고 정보화 변화관리와 외부 협력업체 관리가 조직의 중요한 조정 요인으로 인식되고 있음을 발견하였다. 본 연구의 시사점은 선행 정보화 성과 관련 연구에서 실증적으로 다루지 못한 메커니즘 요인에 대해 직접적으로 사업 담당 임원, 정보화 담당 임원 등의 경험을 바탕으로 사례연구를 진행했기 때문에 IT서비스 기업의 정보화 성과를 위해 중점적으로 관리해야 할 요인들에 대해 실무적인 시각을 제공해 줄 수 있다고 생각하며 IT서비스 기업에 대해 최초로 SER-M 프레임워크를 적용하였기 때문에 정보화 성과 창출을 위한 메커니즘 요인에 대한 보다 깊은 이해와 경험적 사례를 바탕으로 타 산업군의 기업에도 적용할 수 있는 학문적인 기여를 제공할 수 있다고 생각된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.173-174
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• 2008

• 대한기계학회논문집
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• 제18권10호
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• pp.2773-2778
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• 1994

Tumbling motion is very effective for turbulence enhancement during compression process in the cylinder of 4-valve engines. In this paper the tumble decay mechanism for different intake port configuration were measured using laser Doppler velocimetry. Analysis of the tumble decay mechanism was achieved by means of two non-dimensional parameters, defined as tumble eccentricity and shape factor in tumble velocity profile, in addition to the tumble moment.

• Journal of Welding and Joining
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• 제8권3호
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• pp.31-38
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• 1990

The bonding mechanism and bond strength were investigated for the cold pressure welding of Al to Al, Cu to Cu and Al to Cu by upsetting. A phenomenon of bonding betweenthe metallic components has been observed by a scanning electron microscope and metallurgical microscope. A modified equation for bond strength with respect to the reduction of height shows reasonably a good agreement with the experimental data. When the values of the hardening factor and threshold deformation for the given materials could be determined, the theoretical bond strength can be calculated.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.454-458
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• 2001

In this paper, contact between the coupler-roller and guide in elevator door mechanism is modeled and analyzed with DADS 3D program. The contact force of coupler-roller is an important factor for impact and noise reduction when doors of elevator are opened or closed. To minimize the maximum contact force, an optimal cam profile for the door guide is suggested. To find an optimal shape of the guide, several types of motion curve are tested with DADS contact module.

• Structural Engineering and Mechanics
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• 제63권1호
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• pp.23-35
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• 2017

A nonlinear static procedure considering work-energy principle and global failure mechanism to estimate base shears of reinforced concrete (RC) frame-type structures is presented. The relative energy equation comprising of elastic vibrational energy, plastic strain energy and seismic input energy is obtained. The input energy is modified with a factor depending on damping ratio and ductility, and the energy that contributes to damage is obtained. The plastic energy is decreased with a factor to consider the reduced hysteretic behavior of RC members. Given the pre-selected failure mechanism, the modified energy balance equality is written using various approximations for modification factors of input energy and plastic energy in scientific literature. External work done by the design lateral forces distributed to story levels in accordance with Turkish Seismic Design Code is calculated considering the target plastic drift. Equating the plastic energy obtained from energy balance to external work done by the equivalent inertia forces considering, a total of 16 energy-based base shears for each frame are derived considering different combinations of modification factors. Ductility related parameters of modification factors are determined from pushover analysis. Relative input energy of multi degree of freedom (MDOF) system is approximated by using the modal-energy-decomposition approach. Energy-based design base shears are compared with those obtained from nonlinear time history (NLTH) analysis using recorded accelerograms. It is found that some of the energy-based base shears are in reasonable agreement with the mean base shear obtained from NLTH analysis.

• BMB Reports
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• 제51권2호
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• pp.59-64
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• 2018

The airway epithelium is the first place, where a defense mechanism is initiated against environmental stimuli. Mucociliary transport (MCT), which is the defense mechanism of the airway and the role of airway epithelium as mechanical barriers are essential in innate immunity. To maintain normal physiologic function, normal oxygenation is critical for the production of energy for optimal cellular functions. Several pathologic conditions are associated with a decrease in oxygen tension in airway epithelium and chronic sinusitis is one of the airway diseases, which is associated with the hypoxic condition, a potent inflammatory stimulant. We have observed the overexpression of the hypoxia-inducible factor 1 (HIF-1), an essential factor for oxygen homeostasis, in the epithelium of sinus mucosa in sinusitis patients. In a series of previous reports, we have found hypoxia-induced mucus hyperproduction, especially by MUC5AC hyperproduction, disruption of epithelial barrier function by the production of VEGF, and down-regulation of junctional proteins such as ZO-1 and E-cadherin. Furthermore, hypoxia-induced inflammation by HMGB1 translocation into the cytoplasm results in the release of IL-8 through a ROS-dependent mechanism in upper airway epithelium. In this mini-review, we briefly introduce and summarize current progress in the pathogenesis of sinusitis related to hypoxia. The investigation of hypoxia-related pathophysiology in airway epithelium will suggest new insights on airway inflammatory diseases, such as rhinosinusitis for clinical application and drug development.