• International Journal of Aeronautical and Space Sciences
• /
• v.16 no.1
• /
• pp.28-40
• /
• 2015

This paper aims to address the intelligent active vibration control problem of a flexible rectangular plate vibration involving parameter variation and external disturbance. An adaptive sliding mode (ASM) MIMO control strategy and smart piezoelectric materials are proposed as a solution, where the controller design can deal with problems of an external disturbance and parametric uncertainty in system. Compared with the current 'classical' control design, the proposed ASM MIMO control strategy design has two advantages. First, unlike existing classical control algorithms, where only low intelligence of the vibration control system is achieved, this paper shows that high intelligent of the vibration control system can be realized by the ASM MIMO control strategy and smart piezoelectric materials. Second, the system performance is improved due to two additional terms obtained in the active vibration control system. Detailed design principle and rigorous stability analysis are provided. Finally, experiments and simulations were used to verify the effectiveness of the proposed strategy using a hardware prototype based on NI instruments, a MATLAB/SIMULINK platform, and smart piezoelectric materials.

• Journal of Welding and Joining
• /
• v.35 no.1
• /
• pp.68-73
• /
• 2017

During welding of Ni based superalloy, hot cracking was usually happen in the fusion zone of a weld. In this study, the laser weldability of Inconel 713C alloy for the turbocharger wastegate valve (WGV) was evaluated with various welding conditions, such as laser power, welding speed, shielding gas. Welding conditions were optimized by bead-on-plate (BOP) and butt joint welding. For the evaluation of laser weldability, bead shapes and weld microstructures were investigated and tensile test was conducted. The fracture surfaces were investigated for the understanding the cause of the fracture.

• Journal of Korean Ophthalmic Optics Society
• /
• v.1 no.1
• /
• pp.115-118
• /
• 1996

The study on the cytotoxicities of heavy metals, metal-metal and metal-chelator combinations was carried out to evaluate the cytotoxic effect of those on mouse L929 fibroblasts. The colorimetric assays (NR and MTT) were conveniently carried out in 96-well microtiter plates. The rank order was Cd > Zn Ni > Cr(III) for the heavy metals tested. Examination of the effect of metal-metal interaction on cytotoxicity showed a moderate reduction of cadmium toxicity by zinc. The colorimetric assays were also effectively used to investigate the effect of the chelators, ethylenediamine tetra acetic acid (EDTA) and chitosan. Reduction of heavy metal toxixity by chelator was efficient.

• Advances in Energy Research
• /
• v.1 no.1
• /
• pp.53-78
• /
• 2013

Methane carbon dioxide reforming (MCDR) is a promising way of utilizing greenhouse gas for hydrogen-rich fuel production. Compared with other types of reactors, Compact Reformers (CRs) are efficient for fuel processing. In a CR, a thin solid plate is placed between two porous catalyst layers to enable efficient heat transfer between the two catalyst layers. In this study, the physical and chemical processes of MCDR in a CR are studied numerically with a 2D numerical model. The model considers the multi-component gas transport and heat transfer in the fuel channel and the porous catalyst layer, and the MCDR reaction kinetics in the catalyst layer. The finite volume method (FVM) is used for discretizing the governing equations. The SIMPLEC algorithm is used to couple the pressure and the velocity. Parametrical simulations are conducted to analyze in detail the effects of various operating/structural parameters on the fuel processing behavior.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.13 no.12
• /
• pp.983-988
• /
• 2000

The leadframe of thin plate fabricated by stamping method generates a lot of burr and stress in the processing surface because of the mold. The electropolishing equipment was produced in order to increase accuracy and surface roughness for 42%Ni-Fe leadframe. An electrolyte consisted of phosphoric acid, ethylene glycol and deionized water. Experiments were accomplished as polishing conditions were changed such as current density, polishing time, electrode gap and sample shape. The burr from the cutting was eliminated and surface characteristics of high flatness and high luster wre obtained after electropolishing. In addition, the electroplishing had good characteristic in 1.0 A current density and 4㎜ of electrode spaces, and it was affected by the composition of electrolyte and the sample shape.

• YAKHAK HOEJI
• /
• v.46 no.1
• /
• pp.24-29
• /
• 2002

Enoyl-Acyl Carrier Protein Reductase (Fabl) of bacteria is hem as an important target for new antibacterial drugs and plays a determinant role in completing cycles of elongation in type-H fatty acid synthase system. In this study, a fabI gene from Staphylococcus aureus 6538p cloned in pET-l4b vector and FabI protein was over-produced in Escherichaia coli BL2l (DE3). $NH_2$-terminal His-tagged FabI protein was purified by nickel-nitrilotriacetic acid (Ni-NTA) metalaffinity chromatography Purified 6xHis-tagged FabI showed a catalytic activity on tram - 2 - octenoyl - N -acethlcysteamine by utilizing NADPH as a cofactor. For the discovery of new FabI inhibitors from chemical libraries, a target-oriented screening system using a 96-well plate was developed. About 10,000 chemical libraries from Korea Chemical Bank wore tested in this screening system, and 26 chemicals (0.25%) among them showed an inhibitory activity against FabI enzyme. This result showed that a new screening system can be used for the discovery of new FabI inhibitors.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05a
• /
• pp.26-29
• /
• 2006

A flat plate-column connection is susceptible to brittle punching shear failure, which may result in the necessity of shear reinforcement. In present study, experimental tests were performed to study the capacity of slab-column connections strengthened with lattice, stud rail, shear band and stirrup under gravity and cyclic lateral load. Among them, the capacity of the specimens with lattice are superior to the others due to the truss action of the lattice bars and dowel action of the longitudinal bars as well as the shear resistance of the web re-bar. On the other hand, the strengths of the specimens with stud rail, shear band and stirrup are lower than the estimated strength by the ACI, therefore design formulas of the ACI are needed to revise.

• Proceedings of the KIEE Conference
• /
• 2001.07c
• /
• pp.1884-1886
• /
• 2001

In this study, we fabricated Al mirror driven by electromagnetic force. Because the mirror has Ni staple joint, it reduces the deflection angle of torsion spring for the maximum deflection of mirror. Therefore the magnetic field for maximum deflection can be reduced, By additional electrostatic force, the deflection angle of mirror plate can be increased to $90^{\circ}$. The fabricated mirror is actuated by electromagnetic force of a simple solenoid. The maximum deflection angle by magnetic field is about $86^{\circ}$ with $1.2{\times}10^4$ A/m.

• Journal of Welding and Joining
• /
• v.13 no.3
• /
• pp.8-17
• /
• 1995

LNG를 저장할 수 있는 탱크는 주로 지상식이거나 반지하식이며 그 용량은 매우 다양하다. 우리나라에서는 지상식 탱크가 평택 인수기지에 10만m$^{3}$급 Membrane Type 6기가 건설되었고 1기는 거의 완성단계이며, 현재 추가로 건설 중인 3기를 포함하면 총 10기의 탱크를 확보하게 된다. 또한 제2인수기지인 인천에도 동급 으로서 9%Ni강을 사용하는 Double Wall Type LNG 탱크 3기를 건설 중이다. 전세계적 으로 볼 때 LNG 저장 탱크의 78%는 지상식으로 Double Wall Type 또는 Membrane 저장 탱크 형식을 취하고 있으나, 최근에는 안전성 측면, 토지 가격의 상승, 토지의 합리적 이용 측면 등을 감안하여 LNG 탱크를 지하화, 대형화하는 추세이다. 본고에서는 Fig. 1과 같은 구조의 Double Wall Type LNG 저장탱크 중 초저온의 LNG에 직접 접하는 저 온용 재료(9%니켈강)로 만들어지는 내조 용접에 대해서 중점적으로 논하기로 하며, 특히 9% 니켈강 Shell Plate Horizontal Joint에 채용되는 Automatic Submerged ARC 용접에 대해 실제 현장 용접 시공상태를 나타내고자 한다.

• Journal of the Korean institute of surface engineering
• /
• v.31 no.1
• /
• pp.3-11
• /
• 1998

Molten Carbonate Fuel cell is a promising new type electric power generation system which can achieve high efficiency, lower matrrial cost and high operating temperature Making internal reforming possible. Although the development of the MCEC is progressing rapidly toward commercialization, two important tchological problems such as dissolution of NiO cathode and not corrosion of metallic separator plate must be resolved. Because MCFC is operated at $650^{\circ}C$ and the electrolyte is very corrosive, corrosion-resistance of separator plated against oxidation abd molten carbonate is required. Al-coating on separator material for corrosion-resistance was carried out by painting, thermal spraying. hot dipping and vacuum vapour deposition. The corrosion of Al-coated STS 316S and 316L in molten carbonate at $700^{\circ}C$was studied. Vacuum vapour deposition and thermal spraing for Al-coating on STS 310S and 316L were the most effective methods for protecting thestainless steel corrosion in molten carbonate.