• Journal of Welding and Joining
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• 제27권4호
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• pp.67-72
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• 2009

In this paper, arc characteristics of V groove joints using pulsed GMA welding were found out. The bevel angles of $22.5^{\circ}$ and $30.0^{\circ}$ were chose to make the V groove configuration with the groove angles of $45^{\circ}$ and $60.0^{\circ}$, respectively. In the experiment, the arc current waveform measurement and the high speed photography were taken to investigate the arc characteristics for a single-beveled asymmetric workpiece. Consequently, the welding current was changed abnormally around the edge of groove. As the arc moved close to the groove face, the welding current was increased rapidly because the welding arc was affected by the inclined surface. Also the welding current waveforms were measured for the double-sided symmetric workpiece to verify the previous measurements for the single-beveled workpiece, and similar current waveforms were found.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제29회 춘계학술대회
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• pp.162-169
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• 1999

Herringbone groove journal bearing (HGJB) is developed to improve the static and dynamic performances of hydrodynamic journal bearing. Conventional studies on HGJB were based on the Narrow Groove theory assuming that the number of grooves approaches infinity. In this study, an oil lubricated HGJB is analyzed using Finite Element Method. Load carrying capacity, attitude angle, stiffness and damping coefficients are obtained numerically for various bearing configurations especially for the inclined width ratio and asymmetric ratio and compared with the results obtained using Finite Volume Method. The bearing load and stability characteristics are dependent on geometric parameters such as inclined width ratio, asymmetric ratio, groove depth ratio, groove width ratio, groove angle.

• Tribology and Lubricants
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• 제16권6호
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• pp.425-431
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• 2000

Herringbone groove journal bearing (HGJB) is developed to improve the static and dynamic performances of hydrodynamic journal bearing. Conventional studies on HGJB were based on the Narrow Groove theory assuming that the number of grooves approaches infinity. In this study, an oil lubricated HGJB is analyzed using Finite Element Method. Load carrying capacity, attitude angle, stiffness and damping coefficients are obtained numerically for various bearing configurations especially for the inclined width ratio and asymmetric ratio and compared with the results obtained using Finite Volume Method. The bearing load and stability characteristics are dependent on geometric parameters such as inclined width ratio, asymmetric ratio, groove depth ratio, groove width ratio, and groove angle.

• Tribology and Lubricants
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• 제24권6호
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• pp.291-296
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• 2008

In order to improve the leakage prediction and rotordynamic analysis of an annular seal with a smooth rotor and circumferentially grooved stator, CFD analysis using FLUENT has been performed to determine the groove penetration angle a which is the angle of separation line between control volumes II and III in groove section of Ha and Lee's three-control-volume theory. Validation to the present analysis using new penetration angle determined by the CFD analysis is achieved by comparisons with the results of published Ha and Lee's analysis. For the leakage prediction the present analysis shows slight improvement and CFD results yields the best. Direct damping and cross-coupled stiffness coefficients are predicted better to the experimental ones. However, direct stiffness coefficient is predicted worse.

• 한국해양공학회지
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• 제13권3호통권33호
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• pp.68-76
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• 1999

The welding residual stresses produced by the welding frequently caused a crack and promote stress corrosion etc. in HAZ(heat affected zone) contained with external load and weakness of material. Therefore, PWHT(post welding heat treatment) is widely used to reduce wekdubg residuss, to relax hardening of heat affected zone and to get rid of impurity. In this study, in order to define the effect on shappes of T-welded joint, during the post welding heat treatment, we have carried out numerical analyses on the several test pieces by using computer program which was based on thermal-elasto-plato-plasto-creep theories for the study. The main results obtained form this study is as follows: 1) The mechanical difference for change the thickness of plate and groove angle did not appear. 2) The distribution modes of welding residual stresses are same on the all test specimens during the post welding heat treatment. 3) In a mecharical point of view, minimum groove groove angle($40^{circ}$) is more suitable than maximum groove angle($60^{circ}$). 4) Therefore, it is appropriate to minimize the size of groove shape in strength and safety.

• 한국자동차공학회논문집
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• 제16권5호
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• pp.15-21
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• 2008

It is generally known that the PRAT(Plysteer Residual Aligning Torque) is one of indicating a performance factors of a tire for assessing the vehicle pull, also tire pattern shape, which means lateral groove angle, is very important tire design factor in relation to the PRAT. Lateral grooves of tire pattern are widely divided into center and shoulder parts. So, this paper has studied the correlation between the PRAT and their lateral groove angles using FEM. Especially, the steady state rolling analysis among tire rolling analysis methods has been used for the PRAT performance study. Firstly, analysis result data have been compared with the experimental data to validate FE analysis for PRAT. Next, the PRAT due to the lateral groove angle about PCR(Passenger Car Radial) tire and SUV tire has been analyzed. The tendency of the PRAT due to the lateral groove angles can be used as a guide line for the tire design in relation to vehicle pull.

• Tribology and Lubricants
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• 제38권6호
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• pp.261-266
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• 2022

Notably, laser surface patterning facilitates tribological applications under lubricated sliding contacts. Consequently, a special pattern that can reduce the coefficient of friction under contact is considered necessary for improved machine efficiency. However, inappropriate pattern designs produce higher friction coefficients and cannot reduce friction. In this study, we use cast iron pins as specimens to investigate their friction and wear characteristics. Moreover, we experimentally investigate the correlation between the friction reduction effect and the design of groove crosshatch patterns fabricated with various angles and widths. We conduct a friction test using a pin-on-disc type tribometer under grease lubrication to study the friction reduction effect of the specimens, and we observe that the average coefficient of friction changes with the crosshatch angle and width. The experiment reveals that grooved crosshatch specimens with a crosshatch angle of 135°maximize friction reduction. The coefficient of friction of the groove specimens with a width of 120 ㎛ is lower than that of the specimens with a width of 200?. The friction reduction effect of the width of the groove is attributed to the density of the groove pattern. Thus, grooved crosshatch patterns can be designed to maximize friction reduction, and the friction property of a grooved crosshatch pattern is found to be related to its width and angle.

• 대한치과보철학회지
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• 제42권1호
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• pp.58-72
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• 2004

Statement of problem : Clinically, maxillary first premolar has a high risk of fracture. This is thought to be caused by the susceptible figure which the maxillary first premolar has In other words, sharp cusp angles of the premolar is thought to influence this situation. Purpose : This study was to know stress distribution of all-ceramic crown according to the cusp angle. Material and Method : It was manufactured a three dimensional finite element model simplified maxillary first premolar, and then analyzed stress distribution when cusp angle was each $80^{\circ}$, $90^{\circ}$, $100^{\circ}$, $110^{\circ}$ and $120^{\circ}$. Results and conclusion : 1. The von Misses stress showed that stress decreases as cusp angle increases in the central groove of the occlusal surface. 2. It showed that maximum principal stress was centered at the region of the central groove of the occlusal surface and a region which the force was inflicted. And also it appeared high on the lingual and buccal side of finish line. 3. The X axis of normal stress was focused in the central groove of the occlusal surface. The Y axis normal stress appeared high in the central groove of the occlusal surface, buccal and lingual side. 4. The Stress near the finish line showed a low value compared with stress in the region of the central groove of the occlusal surface. 5. It shows that the most dangerous angle for tooth fracture was on $80^{\circ}$ of the cusp angle and low on $120^{\circ}$ of its.

• 대한방사선기술학회지:방사선기술과학
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• 제33권4호
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• pp.335-340
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• 2010

T형 금속판을 이용한 요골 원위부 골절 수술 후 나사못의 요골구 관통 유무를 확인하기 위한 요골구 촬영 방법을 알아보고자 하였다. Wrist CT 환자 51명의 3D 영상과 건조된 요골 표본 20본에서 요골구 각도를 분석하였고, 석고를 이용하여 요골 모형을 제작 한 다음 나사못이 요골구를 2.4 mm 관통 하도록 하고 요골구 원위부 거상 각도 및 외회전 각도를 0~30도까지 5도씩 변화시켜 X-선 영상으로 촬영하였다. 그 결과 요골구 각도는 Wrist CT 영상에서 평균 14.4도, 건조된 요골 표본에서 평균 16.3도였다. 요골 모형에서 요골구를 관통한 나사못의 길이는 거상 각도 및 외회전 각도에 따라 묘출 정도가 다름을 알 수 있었다. 결론적으로 T형 금속판을 이용한 요골 원위부 골절 수술 후 나사못의 요골구 관통을 알기 위한 접선방향촬영에서 요골 원위부 거상각은 $5^{\circ}$, 외회전 각은 $20^{\circ}$를 추천한다.

• Tribology and Lubricants
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• 제20권5호
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• pp.259-265
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• 2004

The sealing performance of O-rings is affected by working conditions such as applied pressure, operation temperature, pre-compressed ratio and material properties. In this paper, a pressurized and compressed elastomeric bi-polymer O-ring in which is inserted into a rectangular groove is analyzed by non-linear MARC finite element program based on the Taguchi experimental method. O-rings with 9 different profile models are analyzed for design parameters that are related to the diameter ratio between outer diameter and inner one of bi-polymer O-ring, compressive ratio, groove angle and groove depth. The calculated FEM results showed that the affection ratio of design parameter dlD, which may control sealing pressure of O-rings, is the most influential parameter among the groove angle, groove depth and compression ratio.