• Journal of Advanced Marine Engineering and Technology
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• 제24권1호
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• pp.127-133
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• 2000

A numerical study of the flow of incompressible fluid in a polar cavity is presented. Irregular grids is proposed by applying the interior division principle to the variables on polar coordinate grid formation. Stability analysis and the pressure correction method of SOLA algorithms were discussed in detail on cylindrical coordinates. The results present that unsteady flow behavior appears over $Re=3{\times}10^4$ on polar cavities but nearly steady state at $Re=10^4$. Furthermore, with increasing Reynolds numbers, vortices behaviors indicate more complicated flow phenomena and more severe temporal fluctuation of total kinetic energy and time variation of velocity components at arbitrary pick-up points are detected in case of $Re=5{\times}10^4$.

• 한국염색가공학회:학술대회논문집
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• 한국염색가공학회 2011년도 제44차 학술발표회
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• pp.68-68
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• 2011

A new chemosensor based on rhodamine B (1) for $Hg^{2+}$ and $Cu^{2+}$ was synthesized by one-step condensation reaction of rhodamine B hydrazide and Azo dye. Studying for its fluorogenic and colorimetric behaviors towards various metal ions, extreme sensitivity and selectivity were achieved by the detection of $Hg^{2+}$ and $Cu^{2+}$ over other commonly coexistent metal ions, which were accompanied by ring opening of a rhodamine spirocycle framework. In acetonitrile, the presence of $Hg^{2+}$ and $Cu^{2+}$ induces the formation of a Dye 1-ion complex, which was deduced by spectroscopy.

• 한국전산유체공학회지
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• 제5권3호
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• pp.1-7
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• 2000

In high-pressure diesel engine, the injected fuel spray impinges on the piston cavity surface due to the short distance between the injection nozzle and the cavity wall. The behavior of the impinging spray has the great influence on the dispersion of fuel, the evaporation, and the mixture formation process. In this study, the numerical simulation using the GTT code was performed to study the gas flows, the spray behaviors, and the fuel vapor distributions in the combustion of a D.I engine for variation of spray angle and swirl ratio.

• 대한기계학회논문집
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• 제7권2호
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• pp.123-129
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• 1983

The effect of the micro-internal stress which is induced in the ferrite grain by plastic constraint, on fracture behavior was investigated. The specimen used has combined microstructure with matrix of ferrite encapsulated by second phase of martensite. The micro-internal stress in the ferrite grain was estimated using a simple mechanical model, and its effect on micro and macro fracture behaviors was discussed. The results obtained are summarized as follows; The micro-internal stress promotes the formation of cleavage cracks in the ferrite during deformation. Consequently, it was concluded that the internal stress is one of the significant factors which cause the fracture ductility to decrease.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.158.1-158.1
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• 2011

In this work, we prepared ultramicroporous carbons (UC) prepared by pyrolyzing poly(vinylidene fluoride) with different carbonization temperatures, and investigated the hydrogen storage behaviors. The surface functional groups and specific elements of UC were confirmed by Fourier-transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), respectively. Textural properties were analyzed using $N_2$ adsorption isotherms at 77 K. The hydrogen storage capacity of the UC samples were investigated by BEL-HP at 298 K/10 MPa. From the results, it was found that the hydrogen storage capacity was enhanced with increasing of specific surface area, resulting from the formation of ultramicropore on the UC.

• 정신신체의학
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• 제6권2호
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• pp.210-220
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• 1998

The relationships between emotion, stress and gastro-intestinal dysfunction were briefly reviewed. Until now, several kinds of theories on about pathophysiology, such as motility dysfunction, changes of pain perception on the lumen, dysregulations on the central nervous system associated with psychosocial factors were reported. However, none of those factors could'nt give any clues for the causes of the functional bowel disorders. For understanding the meaning of the symptoms and for the treatment approach, clinicians should give attention to the comprehensive point of view, i.e., not only biological but also psychological aspects of the patients with non-organic bowel dysfunctions. Giving warm and kind explanations to the patient about symptom formation and progression and understanding the patient's illness behaviors, and good and strong doctor-patient relationship is essentials for the treatment.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.801-804
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• 2002

Electrochemical capacitors are becoming attractive energy storage systems particularly for applications involving high power requirements such as hybrid systems consisting of batteries and electrochemical capacitors for electric vehicle propulsion. Both of amorphous cobalt oxide and manganese dioxide were prepared by sol-gel process reported in our previous work. Nanostructured supramolecular oligomer of 1,5-diaminoanthraquinone(DAAQ) coated metal oxides were successfully prepared by electrochemical oxidation from an acidic non-aqueous medium. We established process parameters of the technique for the formation of nano-structured materials. Furthermore, improved the capacitive properties of the nano structured metal oxide electrodes using controlled solution chemistry. $CoO_2$ and $MnO_2$-based composite electrode showed relatively good electrochemical behaviors in acidic electrolyte system with respect to specific capacity and scan rate dependency.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2006년 추계학술발표대회 개요집
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• pp.181-183
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• 2006

This paper studies the mechanical behaviors of Sn-3.5Ag solder joint against substrate(such as Au/Ni/Cu, Au/cu, Ni/Cu and Cu pad) after induction heating, a new soldering method. It was found that the solder bump formation depends on the time and current of the induction heating system. Also the heating value of the solder bump were found to vary with respect to the thermal conductivity of the pads on the substrate. In case of Au/Ni/Cu pad and Au/Cu pad, solder bump's shear strength were high for the heating time of $1.5{\sim}2sec$. For Ni/Cu pad, solder bump's shear strength were found to increase with time increment.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 추계학술대회 논문집
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• pp.49-52
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• 2000

The hole flanging experiments are performed on a flat circular plates with a hole in the center and the flangeability and fracture behavior of TRIP steel and ferrite-bainite duplex steel were examined. Over the ranges of conditions investigated, the flangeability of ferrite-bainite duplex steel is better than TRIP steel and the term 'hole flanging capacity' introduced in this study. Fracture behavior of TRIP steel and ferrite-bainite duplex steel was characterized by petal formation at the edge of flange. In case of crack propagation, crack tip diversion that is supposed to be responsible for flangeability occurs more severely on HSLA Steel.

• 소성∙가공
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• 제10권6호
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• pp.465-470
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• 2001

Hole flanging experiments are performed on flat circular plates with a hole in the center and the flangeability and fracture behaviors of TRIP steels and ferrite-Bainite duplex steels were examined. In the hole flanging, deformation by lip and petalling occurs when plates are struck by punches of various shapes and high circumferential strains induced in the target material cause radial cracking and the subsequent rotation of the affected plate material in a number of symmetric petals. In all cases, failure of the plate was due to lip fracture that results from multiple localized neckings that take place around the hole periphery where straining is most severe and a somewhat regular pattern was observed in a fracture shape. The neck characteristics in flange formation and the transition from the lip to petal mode at which fracture occurs were compared with two materials.