• The Journal of the Acoustical Society of Korea
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• v.12 no.3
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• pp.68-75
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• 1993

포락선 인텐시티는 신호의 진폭 변화에 비해 상대적으로 천천히 벼놔한다. 본 논문에서는 이러한 성질을 이용하여 종래의 순시 음향 인덴시티법을 수정한 새로운 포락선 인텐시티법을 제안하여 비정상 신호 해석에 이 기술을 적용하였다. 이 기술의 유효성은 반사체가 있는 무향실 내의 충격성 음원에 대해 수치계산 결과와 실험결과의 비교로부터 검증되었고 또한, 이 기술은 무향실 및 잔향실 내의 평판 타음 음원의 지향특성 해석에 응용되었다. 수치계산 결과 및 측정결과는 일치하였고, 제안된 방법은 종래의 순시 인텐시티법보다 특히 과도특성을 갖는 충격성 음원 분석에 보다 유효함이 확인되었다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.383.2-383
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• 2002

In this paper, an experimental technique using a reference accelerometer has been developed to measure the in-plane vibration intensity of a beam. It has the advantages of shortening measurement time and reducing accelerometer phase error comparing with the cross spectral Intensity measurement technique using an accelerometer array. The distribution of the in-plane vibration Intensity over the beam has been measured. (omitted)

• Clean Technology
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• v.13 no.1 s.36
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• pp.72-78
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• 2007

As a basic research fur the separation of effective components included in pyrolysis gas oil, the crystallization on each system of naphthalene with 2-methylnaphthalene, indene and 1-methylnaphthalene as impurity has been carried out in column and cold-finger type crystallizer, respectively. In crystallization operation, the purity of naphthalene has been a tendency of increase with decreasing of cooling rate and in the presence of impurity with lower melting point. In comparison of crystallizer types, naphthalene purity in column type crystallizer was a higher value than that in cold-finger type due to effective sweating operation after crystallization.

• Korean Journal of Materials Research
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• v.13 no.1
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• pp.53-58
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• 2003

For the rib materials in PDP(plasma display panel), an effective method to improve the mechanical properties is to form a composite material by reinforcing a glass matrix with rigid fillers, such as alumina and titania powders. In this study, two types of ribs with different volume percent of fillers and with different glass matrix were tested for hardness, Young's modulus with the Berkovich indentation. As a result, cracks appeared around at the load of 1345 mN for the dense type of rib, while porous one endured until 2427 mN without any crack formation. Young's modulus and hardness decreased at the range: 90∼65 GPa, 9∼4 GPa, respectively as a function of indent load. Thus, a new method with nanoindenter represents a possible evaluation method for mechanical properties of barrier ribs.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.130-131
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• 2007

초고경도 박막을 얻기 위해 질화물을 이용한 CrN / CrAlN 초격자 박막을 CFUBM 시스템을 통해 합성하였다. 초격자 박막의 각층의 두께 (${\lambda}$)는 기판의 회전 속도를 이용하여 제어하여 4.4 에서 44.1 nm 까지 합성하였다. 박막의 결정구조 및 미세구조를 분석하기 위하여 고분해능 X선 회절 분석기 (HR-XRD)를 이용하였으며, 박막의 기계적 성질은 나노 인덴터와 ball on disk tester를 통해 분석하였다. CrN / CrAlN 초격자 박막은 각층의 두께 (${\lambda}$)에 따라 28.77 GPa에서 31.97 GPa의 경도 값을 나타내었으며, 미세구조와 기계적 특성이 변화를 관찰할 수 있었다.

• Polymer(Korea)
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• v.30 no.5
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• pp.432-436
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• 2006

The new dinuclear CGC (constrained geometry complexes) with indenyl and methyl sub-stituted indenyl and polymethylene bridge have been synthesized, and the copolymerization of ethylene and styrene has been studied in the presence of methylalumionoxane. The activity of 12-methylene and 9-methylene bridged dinuclear CGC were 4 times higher than that of 6-methylene bridged dinucleay CGC. This result might be understood by the implication that the steric effect rather than the electronic effect nay play a major role to direct the polymerization behavior of the dinuclear CGC. The dinuclear CGCs are very efficient to incorporate styrene in backbone. The styrene contents in the formed co-polymers ranged from 6 to 45 mol% according to the polymerization conditions. The melting temperature of copolymers disappeared at high content of styrene (about 11 mol%) There is no styrene-styrene diblock sequence in copolymers. This result Indicates that the dinuclear CGC are very effective to generate random copolymer of ethylene and styrene.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.12
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• pp.1139-1143
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• 2007

A simple method for the fabrication of 3D micro-nano hybrid patterns was presented. In conventional fabrication methods of the micro-nano hybrid patterns, micro-patterns were firstly fabricated and then nano-patterns were formatted on the micro-patterns. Moreover, these micro-nano hybrid patterns could be fabricated on the flat substrate. In this paper, we suggested the fabrication method of 3D micro-nano hybrid patterns using micro-indentation on the anodized aluminum substrate. Since diameter of the hemispherical nano-pattern can be controlled by electrolyte and applied voltage in the anodizing process, we can easily fabricated nano-patterns of diameter of loom to 300nm. Nano-patterns were firstly formatted on the aluminum substrate, and then micro-patterns were fabricated by deforming the nano-patterned aluminum substrate. Hemispherical nano-patterns of diameter of 150nm were fabricated by anodizing process, and then micro-pyramid patterns of the side-length of $50{\mu}m$ were formatted on the nano-patterns using micro-indentation. Finally we successfully replicated 3D micro-nano hybrid patterns by hot-embossing process. 3D micro-nano hybrid patterns can be applied to nano-photonic device and nano-biochip application.

• Composites Research
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• v.24 no.3
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• pp.17-24
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• 2011

The EAM simulation of nanoindentation was performed to investigate misfit dislocation slip in the Ag/Cu. The film layer, whose thickness in the range of 2-5nm, was indented by a spherical indenter with the N$\'{o}$se-Hoover thermostat condition. The simulation shows that the indentation position relative to misfit dislocation (MFD) has the effect on the dislocation, glide up or cross slip, for Ag film layer thickness less than 4 nm. Elastic energy variation during MFDs slip was revealed to be a key factor for the softening of Ag/Cu. The critical film layer thickness was evaluated for each case of Ag/Cu according to the spline extrapolation technique.

• Journal of the Korean Chemical Society
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• v.41 no.10
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• pp.524-534
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• 1997

Analysis of additives in cured rubber is often a difficult task for analytical chemists because of a wide variety of complex components. Conventional analyses of additives and rubbers have been done in multistep, off-line processes with large sample size and extensive sample preparations. The coumarone-indene resin, resorcinol-formaldehyde resin, and prevulcanization inhibitor have been characterized by their pyrolysis pathways and mass spectra of characteristic pyrolyzates. Pyrolysis Gas Chromatography/Mass Spectrometry (Py-GC/MS) was used in the identification of additives without any sample pretreatment. This result shows that several organic additives in cured rubber can be directly analyzed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1398-1401
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• 2005

The nano/microstructure, the aging response (in T5 heat treatment), and the mechanical/tribological properties of the eutectic regions in squeeze-cast A356 alloy were investigated using nano/micro-indentation and mechanical scratching, combined wit optical microscopy and atomic force microscope(AFM). Most eutectic Si crystals in the A356 alloy showed a modified morphology as fine-fibers. The loading curve for the eutectic region was more irregular than that of the primary Al region due to the presence of various particles of varying strength. In addition, the eutectic region showed lower pile-up and higher elastic recovery than the primary Al region. The aging responses of the eutectic regions in the squeeze-cast A356 alloys aged at $150^{\circ}C$ for different times(0, 2, 4, 8, 10, 16, 24, 36 and 72 h) were investigated. As the aging time increased, acicular Si particles in the eutectic regions gradually came to a fine structure. Both Vickers hardness ($H_V$) and indentation ($H_{IT}$) test results showed almost the same trend of aging curves, and the peak was obtained at the same aging time of 10 h. A remarkable size-dependence of the tests was found. The friction coefficient for the eutectic region was lower than that for the primary Al region.