• Tribology and Lubricants
• /
• 제31권6호
• /
• pp.281-286
• /
• 2015

Automotive transmission systems are assembled with a large number of gears and shafts, and rolling bearings are used to ensure their smooth operation. Gear oil in the gear box contains solid particles such as wear debris from contacting gears and metallic chips. This particle-enriched lubricating oil can cause premature failure of the rolling bearings. Research aimed at improving the service life of these rolling bearings has been confined mainly to design and lubrication of the inner/outer rings and the rolling elements. In this paper, we redesigned the shape of the cage pocket of a deep groove ball bearing to reduce the premature failure due to particle contamination. Test bearings are assembled with this new cage design containing a hole punched in the cage pocket. Endurance tests are carried out using the contaminated lubricating oil with miracle grid as hard particle. The duration and damaged bearing component shapes are compared for two different cages. The B₁₀ life of bearing with new cage is increased by about 66% compared to the conventional cage. This is because the hard particles can be easily discharged through the pocket hole without staying for a long time in the lubrication regions. This greatly decreases abrasive wear and dents on the highly stressed ball bearing surfaces. Therefore, the cage design of this study, containing a pocket hole, can significantly delay the premature failure of rolling bearings and improve the endurance life.

• 조명전기설비학회논문지
• /
• 제19권6호
• /
• pp.36-45
• /
• 2005

이 논문은 다른 종류의 유도전동기 구름베어링 손상을 유도전동기 고정자 전류신호해석을 통하여 검출하고 실시간으로 손상을 진단하는 알고리즘을 개발하였다. 유도전동기 구름베어링의 손상을 검출하기 위하여 정상적인 베어링을 갖는 유도전동기, 측정열에 불량을 가지고 있는 전동기와 베어링 외륜에 구멍을 가지고 있는 2가지 종류의 비정상 베어링을 갖는 유도전동기 3set를 실험시스템을 구축하였다. 또한 유도전동기의 구름베어링시스템의 비정상적인 상태에서 고정자전류을 검출하기 위하여 TMS320F2407 DSP 칩을 이용하여 데이터 획득보드를 개발하였다. 이 고정자전류신호를 해석을 통하여 베어링 손상을 검출하기 위한 방법으로 FFT, 웨이브렛 분석 및 내적에 의한 평균 신호패던에 의한 분석결과를 제시하였다. 특히 내적에 의한 신호분석 온 통하여 베어링 손상 여부를 실시간으로 진단할 수 있는 새로운 알고리즘과 분석방법을 제시하였다.

• 한국의상디자인학회지
• /
• 제18권3호
• /
• pp.71-83
• /
• 2016

This study attempted to analyze trends of structural changes in the front middle part of men's underwear and get basic data for the development of men's underwear patterns. In terms of a research method, the structure and pattern of the front middle part of men's underwear were analyzed by referring to the design and description of the drawing, focusing on men's underwear which targeted to isolate penis from scrotum among the 'men's underwear' or 'functional men's underwear'-related patents. According to the study, three topics were obtained as follows: a support attached to the inside of the front middle part; inner cloth attached to the inside of the front middle part; change in the structure of the front middle panel. The aspects by the specific topic targeted to isolate penis from scrotum and prevent the scrotum from adhered to a thigh are as follows: 1) When a support is attached to the inside of the front middle part, the following three methods are proposed: Penis isolated from scrotum by a rest which is designed using the band; penis and scrotum rested in the band and in a pocket respectively; protruded rest inside the front middle part of the underwear. 2) When an inner cloth is attached to the inside of the front middle part, the following methods are designed: A pocket-type inner cloth is attached; isolation of penis hole from the scrotum pocket using a rectangular separator; U-shaped pocket designed to rest penis and scrotum is attached. 3) Regarding change in the structure of the front middle panel, the integration of penis and scrotum resting parts can be divided into two cases: Securing a space using wrinkles; keeping it voluminous using the vertical line. In this all-in-one penis and scrotum-holding type, in addition, different front panel patterns were applied.

• 에너지공학
• /
• 제18권2호
• /
• pp.87-92
• /
• 2009

본 논문은 안쪽축이 회전하는 동심환형관 물과 비뉴튼유체의 고-액 2상 유동연구를 수행하였다. 점탄성유체의 유변학은 굴착구멍의 청결, 입자의 밖으로 수송하는 등 여러 가지 응용에 중요하다. 연구에서 투명한 아크릴관은 고체입자의 이동을 관찰하기 위하여 사용하였다. 환형관 속도는 0.3m/s에서 2.0m/s로 변한다. 머드시스템은 물과 CMC 수용액을 혼합하여 사용하였다. 연구에서 고려된 주요 변수들은 축회전속도, 유체 유동영역과 입자 주입율이다. 입자이송속도와 압력강하는 유체유량(Q, LPM)이 5~30의 범위에서 측정하였다. 물과 0.2% CMC 수용액에서 고체입자의 농도가 높을수록 압력손실이 커짐을 알 수 있었다.

• 대한기계학회논문집B
• /
• 제24권9호
• /
• pp.1139-1147
• /
• 2000

This paper describes that the size of inactive zone can be directly applied to design multiblade fan/scroll system. From the experimental studies using a five hole pitot tube and smoke test, it is found that the size of inactive zone has linear relations with the mean velocity of impeller inlet and cut-off angle gives a great influences to the fan efficiency. For the practical design, a function related with geometric parameters(i.e. inner radius, cord length, cut-off clearance and cut-off angle) of fan/scroll system is suggested. By using these formulas, the size and distribution of inactive zone can be predicted without the measurements through the full domain, it can be possible to use them to know the efficiency improvement for new model designed.

• 한국CDE학회논문집
• /
• 제18권4호
• /
• pp.243-249
• /
• 2013

This paper presents a tool-path generation methods for an automated robotic system for skull drilling, which is performed to access to some neurosurgical interventions. The path controls of the robotic system are classified as move, probe, cut, and poke motions. The four motions are the basic motion elements of the tool-paths to make a hole on a skull. Probing, rough cutting and fine cutting paths are generated for skull drilling. For the rough cutting path circular paths are projected on the offset surfaces of the outer top and the inner bottom surfaces of the skull. The projected paths become the paths on the top and bottom layers of the rough cutting paths. The two projected paths are blended for the paths on the other layers. Syntax of the motion commands for a file format is also suggested for the tool-paths. Implementation and simulation results show that the possibility of the proposed methods.

• 한국분말재료학회지
• /
• 제13권5호
• /
• pp.305-312
• /
• 2006

Amorphous carbon nanotubes were synthesized by a reaction of benzene, ferrocene and Na mixture in a small autoclave at temperatures as low as $400^{\circ}C$. The resulting carbon nanotubes were short and straight, but their inner hole was filled with residual products. The addition of quartz to the reacting mixture considerably promoted the formation of carbon nanotubes. A careful examination of powder structure suggested that the nanotubes in this process were mainly formed by surface diffusion of carbon atoms at the surface of solid catalytic particles, not by VLS(vapor-liquid-solid) mechanism.

• Journal of Information Display
• /
• 제7권1호
• /
• pp.1-6
• /
• 2006

A 10" carbon nanotube field emission display device was fabricated with a novel structure with a hopping electron spacer (HES) by screen printing technique. HES plays a role of preventing the broadening of electron beams emitted from carbon nanotubes without electrical discharge during operation. The structure of the novel tetrode is composed of carbon nanotube emitters on a cathode electrode, a gate electrode, an extracting electrode coated on the top side of a HES, and an anode. HES contains funnel-shaped holes of which the inner surfaces are coated with MgO. Electrons extracted through the gate are collected inside the funnel-shaped holes. They hop along the hole surface to the top extracting electrode. In this study the effects of the addition of HES on emission characteristics of field emission display were investigated. An active ozone treatment for the complete removal of residues of organic binders in the emitter devices was applied to the field emission display panel as a post-treatment.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
• /
• pp.545-546
• /
• 2006

A problem of oil supply for a reciprocating compressor is very significant for an evaluation of reliability. Since a rotational motion of a crank shaft for the reciprocating compressor with small capacity is used for a power source of oil supply, a centrifugal force of the rotational shaft provides a stroke of oil inside the shaft like a centrifugal pump. The pumped oil rises following an inner wall and provided to a bearing passed through an oil supply hole at the side of the shaft for lubrication of the bearing. In this study, the amount of oil supply has been investigated by a numerical analysis for various conditions such as a shape of a groove, rpm of the compressor, and a shape of a flow channel. Also, a method of increasing oil supply for a low rpm has been studied so that the function can be improved for a variable condition.

• 한국군사과학기술학회지
• /
• 제12권5호
• /
• pp.676-682
• /
• 2009

The idler wheel installed at the front side of the newly developed tracked vehicle didn't meet the durability requirement by showing the crack failure near the jointed region at the wheel during the field test. To find the crack developing mechanism we constructed finite element model for the idler wheel representing the behavior of interface between each suspension units, material properties from the material test data and actual loading conditions. This paper shows a result that maximum von Mises stress near the bolt hole on the outer rim is higher than inner idler coressponding to the actual test result and that result was reversed by adopting the reinforcement outside of the outer rim.