• 한국생산제조학회지
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• 제24권5호
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• pp.530-534
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• 2015

Ultrasonic nanocrystal surface modification (UNSM) is an example of a nanoscale-surface modification that has become noticeable because of its effects on the mechanical improvement of metallic materials. UNSM equipment needs to be both utilized and improved. The equipment is based on an ultrasonic waveguide whose role is to strike surfaces of metallic materials to achieve nanoscale deformation. In this paper, we introduce the development of one kind of UNSM equipment. Using piezoelectric elements, we repeatedly design and fabricate a 20-kHz ultrasonic waveguide. With respect to the composition of the equipment, the waveguide is automatically transferred by two axial stages automatically. In addition, a static force is constantly applied by pneumatic devices. We perform an experiment to verify the feasibility of the equipment.

• 한국기계가공학회지
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• 제18권12호
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• pp.7-14
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• 2019

A marine turning gear controls the position of the piston-crank mechanism by rotating the flywheel of the marine engine at a low speed, which is the main auxiliary machine that enables the disassembly and maintenance of the engine. In this study, the safety factor for surface durability and tooth bending strength was improved by the design modification of the marine turning gear based on the spur planetary gear. Angular velocity, torque, and efficiency of the turning gear were measured using a reliability evaluation tester, and a multibody dynamics model for analysis corresponding to the test results was developed. Finally, it was confirmed that the design improvements improved the tooth surface damage of the sun gear in the 3^rd reduction stage.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.213-213
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• 2011

Gold catalysts supported on TiO2 have shown a unique catalytic behavior on CO oxidation, depending on surface effects. Particle size has an influence on the surface activity. To make monodisperse Au nanoparticles, organic capping ligands, such as alkylthiols, were used by a "greener" synthesis method [1,2] and Au nanoparticles were deposited on TiO2. However, organic capping ligands must be removed for high catalytic activities by the Au nanoparticles without changing the Au size [3]. We used UV ozone treatment to decompose thiol ligands. The samples have been characterized by X-ray photoelectron spectroscopy to examine the surface modification by UV ozone treatment. We show the size distribution of the gold nanoparticles by light scattering analysis and transmission electron microscopy. Au/TiO2 have been prepared using the wetness impregnation method. The catalytic performance of CO oxidation over Au supported on TiO2 under oxidizing reaction conditions (40 Torr CO and 100 Torr O2) were tested. The results show that the catalytic activity depends on particle size and the time of UV ozone exposure, which suggests the role of sulfur bonding in determining the catalytic activity of Au/TiO2 catalysts.

• Applied Microscopy
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• 제45권4호
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• pp.236-241
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• 2015

Carbon-coated Ni, Cu and Sn nanocapsules were investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) and a four-point probe device. All of these nanocapsules were prepared by an arc-discharge method, in which the bulk metals were evaporated under methane ($CH_4$) atmosphere. Three pure metals (Ni, Cu, Sn) were typically diverse in formation of the carbon encapsulated nanoparticles and their different mechanisms were investigated. It was indicated that a thick carbon layers formed on the surface of Ni(C) nanocapsules, whereas a thin shell of carbon with 1~2 layers covered on Cu(C) nanocapsules, and the Sn(C) nanocapsules was, in fact, a longger multi-walled carbon nanotubes partially-filled with metal Sn. As one typical magnetic/dielectric nanocomposite particles, Ni(C) nanocapsules and its counterpart of oxide-coated Ni(O) nanocapsules were compared in the electrically conductive behaviors for further applications as the electromagnetic materials.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.157-158
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• 2002

A surface hardenable low alloy carbon steel was implanted with medium energy (20 - 50KeV) $N_2^+$ ions to produced a modified hardened surface. The implantation conditions were varied and are given in several doses. The surface hardness of treated and untreated steels were measured using depth sensing ultra micro indentation system (UMIS). It is shown that the hardness of nitrogen ion implanted steels varied from 20 to 50GPa depending on the implantation conditions and the doses of implantation. The structure of the modified surfaces was examined by X-ray photoelectron spectroscopy (XPS). It was found that the high hardness on the implanted surfaces was as a result of formation of non-equilibrium nitrides. High-resolution XPS studies indicated that the nitride formers were essentially C and Si from the alloy steel. The result suggests that the ion implantation provided the conditions for a preferential formation of C and Si nitrides. The combination of evidences from nano-indentation and XPS, provided a strong evidence for the existence of $sp^3$ type of bonding in a suspected $(C,Si)_xN_y$ stoichiometry. The formation of ultra hard surface from relatively cheap low alloy steel has significant implication for wear resistance implanted low alloy steels.

• 한국해양공학회지
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• 제25권6호
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• pp.80-85
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• 2011

The Ultrasonic Nanocrystal Surface Modification (UNSM) technology improves the fatigue life of a torsion bar by inducing compressive residual stress on the surface layer. The UNSM is applied to replace the presetting method and shot peening technology. The torsion bar must be changed periodically because of a lack of durability and a phenomenon related to the stress relaxation. The torsion fatigue test specimens were made of DIN17221 material, and the results showed that the fatigue life was 5 times more than under durability test conditions. A comparison test between the commercial vehicles' presetting method and shot peened torsion bar and the UNSM torsion bar showed that the UNSM could replace the presetting method and shot peening.

• 폴리머
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• 제29권3호
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• pp.221-230
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• 2005

복합재료에 있어서 계면상호작용과 상계면은 이를 구성하고 있는 성분의 함량이나 형태 또는 구조와는 관계없이 입자가 충전된 고분자 또는 고분자 블렌드, 섬유강화 복합재료, 나노복합재료 그리고 생체재료 등의 기본적 물성에 매우 중요한 역할을 한다 계면접착에 영향을 미치는 주요 성분들의 역할에 대한 인식과 이에 따른 적절한 표면처리는 관련기술로의 적용뿐만 아니라 다른 여러 연구 및 개발 분야에도 중요한 기술적 진보를 가져다준다. 그러나 모든 복합재료에서 계면과 상계면의 역할이 중요할지라도 이러한 표면처리 방법은 특정 시스템의 특성뿐만 아니라 그 목적에 맞게 적절하게 선택되어야 한다. 본 연구에서는 복합재료 시스템의 두 성분간의 계면상호작용을 향상시켜 최종 복합재료의 요구 물성을 증가시키기 위하여 여러 종류의 표면처리를 행하였으며, 그 결과들에 대하여 고찰하였다.

• 대한기계학회논문집 C: 기술과 교육
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• 제1권1호
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• pp.115-121
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• 2013

최근 플랜트산업분야에서는 발전설비와 해양 플랜트 및 선박, 교량 건설등 핵심 구조물들에 대한 내구성 향상 및 평가를 위한 기술이 크게 확장 적용될 것으로 본다. 이에 본 연구에서는 초음파 탄성진동에너지를 이용한 초음파 나노표면개질(Ultrasonic Nanocrystalline Surface Modification) 기술과 초음파 피로시험(Ultrasonic Fatigue Test)기술을 통해서 현재까지 국내산업분야에서 활발하게 진행중인 적용사례를 분석하고자 하였으며. 플랜트분야 특히 발전설비와 해양선박 플랜트 및 교량 건설구조물들의 핵심 용접부에 대한 내구성 향상을 위해 크게 확장 적용될 수 있는 새로운 응용기술 연구방향에 대한 방법들을 제시하고자 한다.

• 한국포장학회지
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• 제28권1호
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• pp.23-30
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• 2022

본 연구에서는 바이오매스 부산물을 바이오 플라스틱에 첨가할 수 있는지 여부를 찾고자 바이오매스 부산물인 왕겨, 옥 피, 밀박, 대두박에 대해 일반성분을 조사하였다. 그리고 왕겨에 대해 분체화, 표면 개질 특성을 조사하였다. 부산물 중에서는 왕겨의 입도가 6.44 ㎛로 가장 적합하였으며, silane 처리 후 ESO(Epoxidiz soybean oil)와 3-aminopropyl triethoxysilane를 1:1로 혼합한 용액을 2% 첨가 시 표면개질 상태가 가장 우수하였고, SEM에 의한 입자형상도 가장 좋은 것으로 나타났다. 따라서 ACM(air classifying mill) 처리한 왕겨를 silane 처리한 후 혼합용액을 2% 첨가하는 것이 표면이 개질된 바이오플라스틱 원료로 첨가하여 사용할 수 있을 것으로 사료되었다.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 The Korea-Japan Joint Symposium
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• pp.35-36
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• 2003

The purpose of this work is to investigate the surface modification of LDPE film via corona discharge treatment and subsequent graft polymerization, and their effect on the resulting dyeability is studied in terms of the surface functional groups, surface energetics, and acid-base interaction between the modified LDPE and the dyes used.