• 한국세라믹학회지
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• 제43권10호
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• pp.653-659
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• 2006

The glass-SiC composites have been manufactured via viscous flow of glass for investigating their sinterability and various properties. The relative density of 99.6% could be achieved when 5 wt% SiC was mixed with glass powder, glass-rearranged at 460$^{\circ}C$ for 3 h and then sintered at 665$^{\circ}C$ for 1 h. The sintered density was decreased as adding more than 5 wt% SiC to glass powder. The resistance properties against hyper velocity copper jet formed by explosion of K215 warhead were compared with other ceramics such as $Al_2O_3$ and pyrex, resulting in lower values than that of $Al_2O_3$.

• 사물인터넷융복합논문지
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• 제9권6호
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• pp.83-92
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• 2023

본 연구 목적은 기업의 지식재산활동을 통한 경영성과를 제고할 수 있는 합리적인 경영전략을 제공하는 것이다. 이러한 연구를 통하여 변화하는 글로벌 환경에서 경쟁력을 강화할 수 있는 대응 방안을 모색하고자 한다. 2023년 9월 1일부터 10월 30일까지 200개 기업을 대상으로 설문조사를 실시하였다. 통계분석은 빈도분석, 탐색적 요인 분석, 신뢰도 분석, 상관관계분석, 다중회귀분석, 차이분석을 실시하였다. 결론은 다음과 같다. 첫째, 지식재산활동에서 경영성과에 미치는 영향은 창출활동과 활용활동으로 나타났다. 둘째, 경영전략에서 경영성과에 미치는 영향은 차별화 전략, 원가우위 전략, 집중화 전략으로 나타났다. 셋째, 원가우위 전략은 지식재산활동의 창출활동과 경영성과의 관계에서 부분매개효과가 확인되었다. 넷째, 차별화 전략은 지식재산활동의 창출활동과 경영성과의 관계에서 부분매개효과가 확인되었다. 또한 차별화 전략은 지식재산활동의 활용활동과 성과의 영향관계에서 완전매개효과가 확인되었다. 다섯째, 집중화 전략은 지식재산활동의 활용활동과 경영성과의 관계에서 부분매개효과가 확인되었다. 여섯째, 벤처인증 여부에 따른 창출활동, 보호활동, 활용활동, 원가우위 전략, 차별화 전략, 재무성과, 비재무성과는 차이가 나타났다. 기술패권 시대에 지식재산의 중요성은 높아지고 있기 때문에 사물인터넷 기업의 미래 경쟁력 확보를 위해서는 기업의 벤처 인증과 지식재산을 활용한 전략으로 경영성과를 상승시켜야 할 것이다. 이러한 연구를 기반으로 사물인터넷 기업이 지식재산활동을 고려한 효율적인 전략 추진으로 성과가 극대화되길 기대한다.

• 열처리공학회지
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• 제29권6호
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• pp.277-283
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• 2016

The influences of cooling pressure of quenching process on the mechanical properties such as hardness, impact endurance and anti-thermal fatigue behaviour of STD61 steel were investigated. The specimens were heat-treated using a vacuum furnace in which they were austenitized at $1,030^{\circ}C$ for 1hour under the pressure of $10^{-3}$ torr and cooled with quenching gas of various pressure, i.e. 1, 2 and 6 bar. According to the observation on the specimens prepared with quenching from austenizing temperature, the mechanical properties of the samples with higher quenching pressure were better than those of prepared at lower quenching pressure. The samples prepared with high quenching pressure showed the more homogeneous microstructure with finer carbides. The size of carbides such as VC and (Fe, Cr)C in quenched specimens decreased with increasing gas quenching pressure. It is considered that the rapid cooling with pressure may restrict the formation and growth of carbide.

• 열처리공학회지
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• 제10권3호
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• pp.172-180
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• 1997

The microstructure, tensile and impact properties of forgings of 7175 aluminium alloy have been studied as a function of intermediate thermo-mechanical treatment(ITMT) process. The ITMT process is consisted of warm working and recrystallization. In the case that the billet was warm-worked above 60% below $250^{\circ}C$ and recrystallized at $475^{\circ}C$, the grain size revealed about $17{\mu}m$ which corresponds to one third of that of conventional process. The refinement of grain size leaded to the improved ductility and impact energy without sacrifice of tensile strength. It was found that the ITMT processed specimen behaved isotropically due to the near equiaxed grains. It was observed that the ITMT processed specimen showed the mixed fracture mode of transgranular and intergranular, instead of intergranular mode. This change of fracture mode contributed to the improved ductility and impact property.

• Corrosion Science and Technology
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• 제7권3호
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• pp.145-151
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• 2008

Material degradation such as high temperature oxidation of metallic material is a severe problem in energy generation systems or manufacturing industries. The metallic materials are oxidized to form oxide films in high temperature environments. The oxide films act as diffusion barriers of oxygen and metal ions and thereafter decrease oxidation rates of metals. The metal oxidation is, however, accelerated by mechanical fracture and spalling of the oxide films caused by thermal stresses by repetition of temperature change, vibration and by the impact of solid particles. It is therefore very important to investigate mechanical properties and adhesion of oxide films in high temperature environments, as well as the properties in a room temperature environment. The oxidation tests were conducted for Ni and Ni-Co alloy under high temperature corrosive environments. The hardness distributions against the indentation depth from the top surface were examined at room temperature. Dynamic indentation tests were performed on Ni oxide films formed on Ni surfaces at room and high temperature to observe fractures or cracks generated around impact craters. As a result, it was found that the mechanical property as hardness of the oxide films were different between Ni and Ni-Co alloy, and between room and high temperatures, and that the adhesion of Ni oxide films was relatively stronger than that of Co oxide films.

• 한국재료학회지
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• 제29권3호
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• pp.189-195
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• 2019

The effect of C, Mn, and Al additions on the tensile and Charpy impact properties of austenitic high-manganese steels for cryogenic applications is investigated in terms of the deformation mechanism dependent on stacking fault energy and austenite stability. The addition of the alloying elements usually increases the stacking fault energy, which is calculated using a modified thermodynamic model. Although the yield strength of austenitic high-manganese steels is increased by the addition of the alloying elements, the tensile strength is significantly affected by the deformation mechanism associated with stacking fault energy because of grain size refinement caused by deformation twinning and mobile dislocations generated during deformation-induced martensite transformation. None of the austenitic high-manganese steels exhibit clear ductile-brittle transition behavior, but their absorbed energy gradually decreases with lowering test temperature, regardless of the alloying elements. However, the combined addition of Mn and Al to the austenitic high-manganese steels suppresses the decrease in absorbed energy with a decreasing temperature by enhancing austenite stability.

• 한국가시화정보학회지
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• 제18권1호
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• pp.18-25
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• 2020

The droplet impact behavior is dominated by some parameters such as surface temperature, We number, surface and fluid property. Especially, Leidenfrost effect which prevents the contact between surface and droplet is very powerful phenomenon for determining droplet impact behavior. Due to this effect, the impact regime is divided into contact boiling regime and film boiling regime whether the droplet contact with the surface. Many studies have found that surface micro-structures which processed by surface processing are effective to overcome the Leidenfrost effect. In this study, droplet impact behaviors were compared using ethanol both on flat and laser-ablated Al surface. On the flat surface, impact regime was mainly divided by surface temperature. And there is key dominant parameter for each regime. On the laser-ablated surface, we could see changed impact regime and different impact behavior such as jetting and ejection of tiny droplets despite of same impact conditions.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.930-935
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• 2005

In order to synthesis of the materials and modulus for floor impact sound reduction, we investigated effect on dynamic elastic modulus of floor impact sound reduction materials and module made by inorganic porous materials, EVA chips and so on. We find correlation property between dynamic elastic modulus and light-weight impact noise. And we measured the dynamic elastic modulus of materials and module for floor impact sound reduction. And we predicted reduction efficiency on floor Impact Noise of those. The dynamic elastic modulus is reduced by increase of filler contents and filler species. When the materials for floor impact sound reduction is consisted of l5wt% EVA Chip and l5wt% inorganic porous materials, its dynamic elastic material is the lowest. And when the module is consisted of PE (upper side), PS embossing board(lower side) and the materials for floor impact sound reduction(middle), its dynamic elastic material is the lowest.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2010년도 추계학술대회 논문집
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• pp.252-253
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• 2010

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1995년도 특별강연 및 추계학술발표 개요집
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• pp.154-156
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• 1995