• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 한국윤활학회 1997년도 제25회 춘계학술대회
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• pp.136-141
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• 1997

Rotary compressor is one of the most useful mechanism that is widely applied in refrigeration and air-conditioning systems. That is due to character of rotary compressor -compact, simple etc.While there is a lot of strong points, there is room for improvement because it is composed of many parts which have wear problem, friction losses and leakage. In this paper, theoretical investigation about vane and slot parts at which we observe severe wear is carried out. Through the study of lubrication, the behavior of vane during one cycle can be predicted and the cause of wear at slot will be discovered. To solve the equations, fletcher-powell method is applied. The result of analysis show that vane bevell to the slot part with discharge port before rotation of shaft is 180 degree and bevell to the slot part with suction port after 180 degree. The motion of vane is divided 3 mode that depends on behavior of vane. This paper define the first mode when vane tilt to the compression chamber, the second mode when vane tilt to the suction chamber, and the third mode when vane move straightway.

• Journal of Mechanical Science and Technology
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• 제18권10호
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• pp.1772-1781
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• 2004

The mechanical as well as tribological characteristics of coating films as thin as a few nm become more crucial as applications in micro-systems grow. Especially, the amorphous carbon film has a potential to be used as a protective layer for micro-systems. In this work, quantitative evaluation of nano-indentation, scratching, and wear tests were performed on the 7nm thick amorphous carbon film using an Atomic Force Microscope (AFM). It was shown that AFM-based nano-indentation using a diamond coated tip can be feasibly utilized for mechanical characterization of ultra-thin films. Also, it was found that the critical load where the failure of the carbon film occurred was about 18${\mu}$N by the ramp load scratch test. Finally, the wear experimental results showed that the quantitative wear rate of the carbon film ranged 10$\^$-9/～10$\^$-8/ ㎣ /N cycle. These experimental methods can be effectively utilized for a better understanding the mechanical and tribological characteristics at the nano-scale.

• Tunnel and Underground Space
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• 제33권6호
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• pp.534-546
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• 2023

If the disc cutter is excessively worn or damaged, it becomes incapable of rotating and efficiently cutting rockmass. Therefore, it is important to appropriately manage the replacement cycle of the disc cutter based on its degree of wear. In general, the replacement cycle is determined based on the results of manual inspection. However, the manual measurements has issues related to worker safety and may lead to inaccurate measurement results. For these reasons, some foreign countries are developing the real-time measurement system of disc cutter wear by using different sensors. The ultrasonic sensors, eddy current sensors, magnetic sensors, and others are utilized for measuring the wear amount of disc cutters. In this study, the applicability of eddy current sensors for real-time measurement of wear amount in TBM disc cutters was evaluated. The distance measurement accuracy of the eddy current sensor was assessed through laboratory tests. In particular, the accuracy of eddy-current sensor was evaluated in various environmental conditions within the cutterhead chamber. In addition, the measurement accuracy of the eddy current sensor was validated using a 17-inch disc cutter.

• The Journal of Korean Academy of Prosthodontics
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• 제39권1호
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• pp.84-95
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• 2001

Titanium is widely used in dentistry for its low density, high strength, fatigue resistance, corrosion resistance, and biocompatibility. But it has a tendency of surface damage under circumstance of friction and impact for its low hardness of the surface. Coating is one of methods fir increasing surface hardness. Its effect is to improve surface physical characteristics without change of titanium. Diamond-like carbon and titanium nitride are known for its high hardness of the surface. So that this study was aimed at the wear test and the cytotoxicity test of the commercially pure titanium and Ti-6Al-4V alloy which were deposited by diamond-like carbon film or titanium nitride film to acertain improvement of the surface hardness and the biocompatibility. A disk (25mm diameter, 2mm thickness) was made of commercially pure titanium and Ti-6Al-4V alloy and these substrates were deposited by diamond-like carbon film or titanium nitride film. Diamond-like carbon film was deposited by the method of radiofrequency plasma assisted chemical vapor deposition and titanium nitride film was deposited by the method of reactive arc ion plating. Then these substrates were tested about wear characteristics by the pin-on-disk type wear tester in which ruby ball was used as a wear causer under the load of 32N, The fracture cycles were measured by rotating the substrates until their films were fractured. The wear volume was measured after 150 cycles and 3,000 cycles using surface profiler. The cytotoxicity test was peformed by the method of the MTT assay. The results were as follows : 1. In the results of the wear volume test, commercially pure titanium and titanium alloy which were coated by diamond-like carbon film or titanium nitride aim had higher resistance against wear than the substrates which were not coated by any films (P<0.05). 2. In the results of the fracture cycle test and the wear volume test, diamond-like carbon film had higher resistance against wear than titanium nitride film (P<0.05). 3. In both coatings of diamond-like carbon aim and titanium nitride film, Ti-6Al-4V alloy had higher resistance against wear than commercially pure titanium (P<0.05) 4. In the results of the cytotoxicity test, diamond-like carbon film and titanium nitride film had little cytotoxicity as like commercially pure titanium or Ti-6Al-4V alloy (P>0.05).

• Tribology and Lubricants
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• 제33권2호
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• pp.52-58
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• 2017

An ultra-high precise ejection process is essential in a dispensing system for fabricating various precision parts such as a semiconductor, LED, and camera module. The size of such parts has been decreasing, which implies that a precise ejecting technique is required. A phosphor-containing liquid is ejected via a dispenser using dual piezoelectric actuators that are used for generating a high-speed dispensing mechanism. The rod and nozzle continuously contact in high speed to eject the liquid. However, the high-strength filler or phosphor in the liquid causes wear on the surfaces of the rod and nozzle during the dispensing process. As a result, the ejection reliability decreases as the wear on the surfaces increases. Therefore, it is necessary to estimate the wear characteristics of the rod and nozzle via an experiment and FE analysis. Reliability rests up to 1,000 cycles are conducted under relatively severe conditions. The flow rate and surfaces roughness of the rod and nozzle are measured in each ejection cycle. The surface images and wear volume are obtained before and after the tests and the ejection reliability is confirmed by measuring the flow rate of the liquid. The experimental results show that the ejection reliability is maintained up to 1,000k cycles; these results are validated by the simulation results.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 한국염색가공학회 2012년도 제46차 학술발표회
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• pp.96-96
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• 2012

최근 주 5일제 근무 실행과 사회복지의 확산, 여가 선용에 대한 욕구와 더불어 건강증진에 대한 싸이클이 주목을 받고 있음. 싸이클웨어(Cycle Wear)에 요구되는 개발요소는 경기력 향상을 위한 기능적 요소와 패션성을 부여하는 심미적 요소로 크게 구분 가능하며 해외에서는 기능성과 패션성이 적절하게 조화를 이룬 제품을 계속 출시되고 있음. 본 연구에서는 운동 시 발생하는 열을 흡한속건 기능으로 효과적으로 발산하고 동절기에는 보온 기능을 갖는 세섬도 하이멀티 OY형 이형단면사 및 잠재권축사를 이용한 고신축 환편 및 경편물 개발하고, 극한환경에서도 고견뢰도를 유지할 수 있는 섬유의 염색법 및 기능성 발현 가공법의 적용, 내마모성과 필링이 우수한 아라미드+나일론 복합가공사 신축직물 제직 및 염색가공 공정 개발을 통해 기능성을 발현할 수 있는 싸이클 웨어 원단을 개발하였음. 또한 종래 Compression Wear에만 적용하던 테이핑 요법을 응용한 근력강화형 싸이클웨어 패턴과 디자인 개발을 통해 다양한 형태의 근력강화형 싸이클웨어를 개발하였으며, 무산소파워, 유산소파워, 젖산분석, EMG 분석 및 에너지 대사분석 등의 운동능력 성능평가를 통해 테이핑 요법이 적용된 싸이클웨어의 근력강화 효과를 확인하였음. 이와 같이 개발된 싸이클웨어는 무산소파워, 유산소파워, EMG 분석에서 각각 근력강화 효과를 보였으며, 피로물질인 젖산의 경우는 발생의 정도가 낮게 나타났음. 또한 여성에 비해 남성의 근력강화 효과가 크게 나타나는 경향을 보였음.

• Journal of the Korean Society of Costume
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• 제50권8호
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• pp.177-198
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• 2000

The major purpose of this study is to obtain the evident and visual data about the changes of Korean dress with a socio-cultural context through dress depicted in the Korean films since the 1960s. For this purpose, after were Korean socio-cultural background including the history of Korean films and mass fashion trends reviewed, total fifteen Korean films by ten year were selected on the basis of contemporaneity popularity, and fashionability, and analyzed with the data reviewed before. And the results can be summarized as follows : Dress in the Korean films of the 1960s shows sporty casual took influenced by western style, with the popularity of young fashion and youth film. The typical styles are sac dress and mini skirt fur women, and suit with American silhouette for men. Unisex mode including slim T-shirts and blue jeans with European silhouette supt appears mainly in the Korean films of the 1970s, with the change of sex roles and mass fashion trend. Dress in the Korean films of the 1980s is characterized by bold silhouette and decorative details. with the boom of erotic metro-drama and luxurious fashion trend, such as padded jacket, X silhouette ensemble, brig look coat for women, and American style suit for men. Dress in the Korean films of the 1990s shows the rapid cycle of fashion with the increase of casual wear, reflecting the popularity of romantic comedy film and various socio-cultural circumstances. As a result, the current of dress depleted in the Korean films since the 1960s is summarized as the cycle of fashion accelerated, the similarity between men's and women's wear, and the increase of sporty casual wear. Also, dress in the films reflects effectively the socio-cultural context related to fashion except for especially emphasizing characters in films.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 한국윤활학회 1998년도 제28회 추계학술대회
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• pp.91-99
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• 1998

A correlation between the low-cycle fatigue life and the scuffing-failure life is demonstrated using the plastic strain in boundary lubricated sliding. Loadings proportional to hardness with three different lubricated conditions were used to evaluate the plastic strain. As the results of scuffing tests using vacuum pump oils in nitrogen gas, plastic strain shows 0.0062, and In the mineral oils and commercial engine oils in air, plastic strain show 0.0042 and 0.00092. Those are very useful to describe quantitatively the real lubricated sliding conditions, and are very effective to find the relation between the low-cycle fatigue life and the scuffing life.

• Journal of the Korean institute of surface engineering
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• 제35권6호
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• pp.408-414
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• 2002

TiN and TiAlN coating layer were deposited on WC-Co steel substrates by an arc ion plating(AIP) technique. The crystallinity and morphology for the deposited coating layers were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The impact behaviors of the deposited TiN and TiAlN coating layer were investigated with a ball-on-plate impact tester. Beyond $10^2$ impact cycle, TiAlN coating layer showed superior impact wear resistance compared to TiN coating layer. On the other hand, both TiN and TiAlN coating layers started to be partially failed between $10^2$ and $10^3$ impact cycle. Above $10^3$ impact cycle, TiN and TiAlN coating layers showed similar impact behavior because of the substrate effect.

• Journal of Korean Tunnelling and Underground Space Association
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• 제24권1호
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• pp.57-78
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• 2022

The disc cutter and cutterbit, which are the most important factors to increase the excavation efficiency of TBM, are key factors in the design and construction of the cutter head. The arrangement, spacing, number, size, and material of disc cutters suitable for the ground conditions determine the success or failure of TBM construction. The disc cutter, which is a representative consumable part in TBM construction, can cause enormous disruption to the construction cost as well as the construction cost unless accurate prediction of wear and replacement cycle is accompanied. Therefore, in this study, the method of calculating the replacement cycle of the disc cutter calculated at the time of design for the slurry shield TBM field, and the depth of wear and replacement location of the disc cutter that occurred during actual construction were compared by analyzing the field data. For a quantitative comparison, weathered soil/weathered rock, soft rock, and hard rock were classified according to the ground in the section showing constant excavation data, and the trajectory of circle was different depending on the location of the disc cutter, so it was compared and analyzed.