• 한국기계가공학회지
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• 제15권4호
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• pp.40-45
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• 2016

Interrupted cutting has different cutting characteristics compared with continuous cutting. In interrupted cutting, the workpiece has a groove that regularly impacts the cutting tool and workpiece. Therefore, tool damage occurs rapidly, and this increases the cutting force and surface roughness. In this study, we performed interrupted cutting of carbon steel for machine structure (SM45C) using a coated carbide tool (TT7100). To predict the cutting force, we analyzed the experimental results with a regression analysis. The results were as follows: We confirmed that the factors affecting the principal force and radial force were cutting speed, depth of cut, and feed rate. From the multi-regression analysis, we deduced regression equations, and their coefficients of determination were 89.6, 89.27, and 28.27 for the principal, radial, and feed forces, respectively. This means that the regression equations were significant for the principal and radial forces but not for the feed force.

• 정보저장시스템학회논문집
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• 제1권2호
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• pp.121-126
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• 2005

Recently, an optical disc system has been proposed using blue laser diode, high NA objective lens and groove only disc structure. A new method is needed to readout CD and DVD in this Blu-Ray Disc Recorder. In order to readout CD and DVD in Blu-Ray Disc Recorder, we adopted dual-lenses actuator in consideration of optical utilization efficiency, optical performance and insurance of sufficient W.D(working distance). This dual-lenses actuator has two objectives in radial direction, one is for CD/DVD and the other is for BD. We had to solve the induced problems of collision between disc and lens, DC tilt increase, AC tilt increase, 2nd resonance deterioration and AC sensitivity drop caused by disposing two lenses in an actuator. Also we developed high response twin- objective actuator with radial tilt function to apply high-speed BD Recorder or BD Player. Consequently we presented that two kinds of dual-lenses actuators for BD Recorder have been possessed good performance in 3 axis directions. And we measured eye patterns of CD, DVD and BD by using one BD optical pick-up with dual-lenses actuator.

• 대한수의학회지
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• 제41권2호
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• pp.167-172
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• 2001

1999년 3월부터 12월에 걸쳐 대구지방에서 피부사상균증에 이완된 개 110두에서 57주(51.8%)의 Microsporum canis를 분리하여 표준균주 1주와 함께 육안적, 현미경적 및 생물학적 성상을 조사하고 고찰하였다. M canis 57주는 집락의 성상 및 현미경적 소견에 따라 4가지(A~D)형으로 나눌 수 있었다. A형(white-yellow type)은 73%(42주)이며 표준주(ATCC 18615)의 전형적인 집락과 동일한 형이며, B형(fluffy type)은 21.1%(12주)이고, C형(flat type)은 3.5%(2주)이며, D형(radial groove type)은 1.7%(1주)이었으며, 이들 형은 전형적인 대분생자의 수적 차이가 인정되었다. 한편 계대가 진행됨에 따라 3가지 변이형(E~G)이 출현하였다. E형은 B형 12균주 중 25%(3주)가 변이한 균주로 갈색색소를 산생하고 비전형적인 대분생자가 관찰되며, G형은 B형의 변이주로 색소 및 대분생자가 소실된 형으로 25%(3주) 이었고, F형은 A형 42균주 중 7.1%(3주)가 변이한 균주로 섬유다발 모양의 성상과 뒷면의 색소 소실 및 비전형의 대분생자, 아령 모양의 균사가 관찰되었다. M canis 58주(표준주 포함)의 urease test, rice medium test, 모발천공시험에서 정도의 차이는 있었지만 전 균주가 양성이었다.

• Tribology and Lubricants
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• 제25권5호
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• pp.324-329
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• 2009

In this study a complex design fitness analysis of journal bearings is carried out for the LPLi rotary-vane fuel pump application, as an external and horizontal installation, in LPG vehicles. Bearings considered in the analyses are plain and 3-axial groove journal bearings. Upon reflecting the fact that the primary failure mode of bearings in the application is a premature friction and wear failure of bearing metal due to a very low viscosity of liquid fuel LPG as a bearing lubricant, the performance factors of bearings used in an evaluation process of design fitness are a load carrying capacity and vibration suppression ability relative to a rated speed. At this time the design variables of bearings are a radial clearance and length. Results show that, in terms of both of the load carrying capacity and vibration suppression ability, the plain journal bearings are superior to the 3-axial groove journal bearings and among the plain bearings the smaller the bearing clearance (5>10>$15\;{\mu}m$) is and the longer the bearing length (6<8<10<12<14 mm) is, the better the bearing performance is.

• 한국정밀공학회지
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• 제17권9호
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• pp.145-150
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• 2000

Out-of-sphericity is degree of deformation of an air bearing sphere deviated from a perfect sphere. This paper investigates numerically the effect of out-of-sphericity error on the radial stiffness of an air bearing Three types of out-of-sphericity modes are considered. in this study the stiffness is calculated from pressure distribution at the bearing surface which is obtained by solving th Reynolds equation. in some cases large out-of-sphericity errors are found to improve the stiffnesses of air bearings. This implies that an air bearing of perfect hemispheres is not necessarily of the best performance. Thus much labor and cost in manufacturing air bearings can be saved, In addition the radial stiffness of an air bearing depends greatly on the application direction.

• 대한정형외과 초음파학회지
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• 제1권2호
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• pp.128-133
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• 2008

신경 압박의 원인은 외부로부터 가해지는 것도 있고, 신체 내부 병리가 발생하여 신경 주행에 따라 발생할 수 있다. 주관절 이하부에서 압박성 신경병증으로 정중 신경, 척골 신경, 요골신경병증이 있다. 정중 신경은 굴곡 지대부위에서 수근관 증후군이 대표적이며, 모든 신경 포착 증후군 가운데 가장 흔하다. 그 외 주관절 부위에서 스트러더스 인대, 상완 이두근 건막, 회내근, 천수지 굴근 기시부 그리고 비정상 근육들에 의한 회내근 증후군과 전 골간 신경 증후군이 있다. 척골 신경은 스트러더스 궁, 내측 상과 후방의 주관, 척수근 굴근 두 기시부 사이의 건막 등에서 눌리는 주관 증후군과, 수근부에서 결절종, 유구골 갈고리 골절 그리고 혈관성으로 오는 척골 관 증후군이 있다. 요골 신경의 심부 분지가 회외근속을 지나면서 만들어지는 부위에서 눌리는 경우 요골 관 증후군이라고 한다. 치료는 초기에는 소염제나 야간부목, 스테로이드 주사와 같은 보존적 치료를 시행할 수 있으며, 이에 호전되지 않을 경우 전기적 검사나 영상 검사에서 이상이 나타나면 수술적 감압술을 시행하여야 한다.

• Tribology and Lubricants
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• 제18권4호
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• pp.273-278
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• 2002

Grease deterioration of mineral oil type grease was investigated using sealed deep groove ball bearings (6203) and bearing life test rig. The bearing test was performed under 3,000 rpm and 245 N radial load at 120。C. Grease taken ken tested bearings was checked in using certain evaluation methods, for example, oxidation induction time (OIT), FT-IR peak intensity, leakage .ate, bleeding .ate, total acid number. (TAN) and bearing noise increase. Within these test conditions, OIT, TAN, bleeding rate were changed gradually in accordance with bearing operating time and showed useful indices for deterioration of grease.

• 한국자동차공학회논문집
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• 제6권5호
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• pp.199-210
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• 1998

The skill that utilizes atomization of the liquid has been widely used in the field of industry and engineering. Though there are dozens of methods to make atomization, the pressure type injection nozzle is frequently used in washing of parts, pastourization and painting because it has relatively simple system. This study is to reveal the characteristics of atomizing formed by three different types of the pressure type injection nozzle. We measured velocity and diameter of droplet to compare and analyze characteristic of each nozzle. In case of velocity, atomization of hollow-cone nozzle is irregular than others and change of radial direction is especially large. Atomization of flat nozzle is nearly uniform. In case of diameter, atomization of hollow-cone nozzle is increased rapidly, as measurement point become more distant from the center of nozzle. Atomization of flat nozzle has the most fixed magnitude. Accordingly, full-cone nozzle can be used irrespective of the form of subject and hollow-cone nozzle is proper to the occasion to spray large and smooth subject. Also, flat nozzle is proper to the occasion to spray a part of subject and long groove.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.777-781
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• 2002

Recently, an optical disc system has been proposed using blue laser diode, high NA objective lens and groove only disc structure. A new method is needed to readout CD and DVD in this blue system. In order to readout CD and DVD in HD-DVD system, we adopted dual-lenses actuator in consideration of optical utilization efficiency, optical performance and insurance of sufficient W.D (working distance). This dual-lenses actuator has two objectives in radial direction, one is for CD/DVD and the other is for HD-DVD. We had to solve the induced problems of DC tilt increase, $2^{nd}$ resonance deterioration and AC sensitivity drop caused by disposing two lenses in an actuator. Especially, to solve AC sensitivity drop, we introduced two 2-pole magnets and separated focus and track magnetic circuits. Consequently we presented that dual-lenses actuator has been possessed good performance. And we measured eye patterns of CD, DVD and HD-DVD by using HD-DVD optical pick-up with dual-lenses actuator.

• Tribology and Lubricants
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• 제8권2호
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• pp.64-72
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• 1992

The recent trends of rotating machinery demand high speed and high temperature operation, and the bearing with new material is required to be developed. Ceramic, especially silicon nitride, have been receiving attention as alternative material to conventional bearing steel. Ceramic ball bearing offers major performance advantages over steel bearing, for instance, high speed, maginal lubrication, high temperature, improved corrosion resistance and nonmagnetic capabilities etc.. In this paper, the mechanical characteristics of ceramic ball bearing (hybrid ceramic bearing and all ceramic bearing) were investigated, and the characteristics of ceramic bearing were compared with that of steel bearing. Deep groove ball bearing 6208 was taken the object of analysis. The main results of analysis were followings: the radial stiffness of hybrid and all ceramic bearing were 112% and 130% that of steel bearing, and the axial stiffness of all ceramic bearing was 110% that of steel bearing. According as rotating speed was up, the ball load, the contact angle, the contact stress and the spin-to-roll ratio between ball and raceway of ceramic bearing were far smaller than these of steel bearing. And there was not a significant difference between the minimum film thickness of ceramic bearing and steel bearing. It is expected that this research is contributed to enhanced fundamental technology for the practical applications of ceramic ball bearing.