• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.156-161
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• 2006

The rivulet is a narrow stream of liquid flowing down a solid surface. Heat transfer of rivulet flow over on inclined heated surface has been investigated experimentally. This problem is of particular interest in the understanding of fundamental mechanism on rivulet heat transfer as well as in the design of a regenerative evaporative cooler. The rivulet is seem to be meandering flow, single wide flat flow. and film flow as rivulet flow rate is increased. Even though the wetted surface area is increased with an increase in the rivulet flow rate, the absorbed heat transfer of rivulet flow from a heated surface strongly depends on the flow pattern of rivulet.

• 대한기계학회논문집
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• 제14권3호
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• pp.624-635
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• 1990

본 연구에서는 마멸과정을 선형파괴역학적 관점에서 해석하여, 탄성체의 표면 에 산재되어 있는 표면균열의 전파거동을 마멸과정규명의 입장에서 살펴보고자 한다. 우선 마멸거동에 관한 파괴역학적 접근방식에 의한 마멸이론의 확립을 위해서, 표면균 열이 내부균열보다 그 전파 가능성이 높다고 한 Keer등의 주장에 착안하여 Hertz 접촉 압력하의 경사진 표면균열의 전파거동을 선형파괴역학적으로 해석하고자 한다. 이론 해석에 있어서는 표면균열을 인상전립의 연속분포로 치환하고, 전립밀도분포함수에 관 한 특이적분방정식을 유도해서 Erdogangupta의 방법을 이용하여 그 해를 구하였다.

• 한국터널지하공간학회 논문집
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• 제10권3호
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• pp.245-256
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• 2008

터널 주지보재의 하나인 강지보재는 굴착 후 숏크리트 또는 록볼트의 지보기능이 발휘되기까지 터널 굴착면의 안정을 도모하는데 매우 중요한 역할을 수행한다. 일반적으로 수평터널의 강지보재는 중력방향으로 설치되고 있으며 시공성 및 안정성 측면에서 모두 유리한 것으로 알려져 있다. 그러나 경사터널의 경우는 터널 벽면에 작용하는 주응력 방향과 중력방향이 서로 다르기 때문에 최적의 강지보재 설치방향은 수평터널에서의 중력방향과는 다를 수 있다. 본 연구에서는 수치해석 방법을 이용하여 경사터널 벽면에 작용하는 힘의 작용방향을 규명하였으며 그 방향이 최적의 강지보재 설치방향이 될 수 있다. 즉, 강지보재의 지보효율은 터널 변위가 발생하는 방향으로 저항하도록 설치하는 경우에 최대가 될 수 있다. 국내 터널설계기준에서 제안하고 있는 경사터널에서의 세 가지 강지보재 설치방향을 모델로 설정하여 단계별 해석을 통한 비교검토를 수행하였다. 연구결과 경사터널 벽면에서의 변위 발생각은 막장경사와 관계없이 모두 터널 굴착면에 수직한 방향과 유사한 각도로 발생하므로 경사터널에서의 강지보재는 터널 굴착면에 수직인 방향으로 설치하는 경우가 지보효율 측면에서 보다 유리한 것으로 검토되었다.

• 대한치과보철학회지
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• 제42권4호
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• pp.356-372
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• 2004

Statement of problom: In the internal connection system the loading transfer mechanism within the inner surface of the implant and also the stress distribution occuring to the mandible can be changed according to the abutment form. Therefore it is thought to be imperative to study the difference of the stress distribution occuring at the mandible according to the abutment form. Purpose: The purpose of this study was to assess the loading distributing characteristics of 3 implant systems with internal connection under vertical and inclined loading using finite element analysis. Material and method: Three finite element models were designed according to the type of internal connection of ITI(model 1), Friadent(model 2), and Bicon(model 3) respectively. This study simulated loads of 200N in a vertical direction (A), a $15^{\circ}$ inward inclined direction (B), and a $30^{\circ}$ outward inclined direction (C). Result: The following results have been made based on this numeric simulations. 1. The greatest stress showed in the loading condition C of the inclined load with outside point from the centric cusp tip. 2. Without regard to the loading condition, the magnitudes of the stresses taken at the supporting bone, the implant fixture, and the abutment were greater in the order of model 2, model 1, and model 3. 3. Without regard to the loading condition, greater stress was concentrated at the cortical bone contacting the upper part of the implant fixture, and lower stress was taken at the cancellous bone. 4. The stress of the implant fixture was usually widely distributed along the inner surface of the implant fixture contacting the abutment post. 5. The stress distribution pattern of the abutment showed that the great stress was usually concentrated at the neck of the abutment and the abutment post, and the stress was also distributed toward the lower part of the abutment post in case of the loading condition B, C of the inclined load. 6. In case of the loading condition B, C of the inclined load, the maximum von Misess stress at the whole was taken at the implant fixture both in the model 1 and model 2, and at the abutment in the model 3. 7. The stress was inclined to be distributed from abutment post to fixture in case of the internal connection system. Conclusion: The internal connection system of the implant and the abutment connection methods, the stress-induced pattern at the supporting bone, the implant fixture, and the abutment according to the abutment connection form had differenence among them, and the stress distribution pattern usually had a widely distributed tendency along the inner surface of the implant fixture contacting the a butment post.

• 소성∙가공
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• 제10권4호
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• pp.302-310
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• 2001

The twisting and extrusion process of the product with involute helical fin from the round billet is developed by the upper bound analysis. The twisting of extruded product is caused by the twisted inclined die surface connecting the die enterance section and the die exit section linearly. In the analysis, the internal shear surface is defined as the curved twisted plane from the twisting of die surface and the shear work is calculated by the consumption of shear energy. The increase rate of angular velocity is determined by the minimization of plastic work. The angular velocity of die exit can be controlled by the land length and the length of inclined die. The alular velocity assums to be increased linearly by the axial distance from the die enterance to the die exit. The results of the analysis show that the angular velocity of the extruded product increases with the die twisting angle, the reduction of area, and decreases with the die length, the friction constant.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.1085-1088
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• 2001

The process of styrofoam pattern that has been used for material of press die pattern depends chiefly on handwork. Laser manufacturing system developed to increase precision and efficiency of process that is also able to convert the design easily. Applying the RP(rapid prototyping) concept reversely, the unnecessary part of section is vapored away by heat source of laser beam after converting 3-D CAD model into cross-sectional shape information. Laser beam is line-scanned in plane specimens to measure the depth and width of cut, surface roughness, cross-sectional shape as converting laser power, scanning speed, cutting gas pressure. With these basic data, plane surface, inclined surface, hole, outer contour trimming process is experimented and optimum condition are obtained. In plane and inclined surface experiments, 15W laser power and 50mm/s scanning speed make superior processing property and 30W, 10mm/s make processing efficiency increase in trimming process. With these results, simple patterns were manufactured and the possibility of applying laser manufacturing system to styrofoam pattern was convinced.

• Tribology and Lubricants
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• 제38권5호
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• pp.191-198
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• 2022

With the world's fast expanding energy usage comes a slew of new issues. Because one-third of energy is lost in overcoming friction, tremendous effort is being directed into minimizing friction. Surface texturing is the latest surface treatment technology that uses grooves and dimples on the friction surface of the machine to significantly reduce friction and improve wear resistance. Despite the fact that many studies on this issue have been conducted, most of them focused on parallel surfaces, with relatively few cases of converging films, as in most sliding bearings. This study investigated the lubrication performance of surface-textured inclined slider bearings. We analyzed the continuity and Navier-Stokes equations using a commercial computational fluid dynamics code, FLUENT. The results show the pressure and velocity distributions and the lubrication performance according to the number and orientation of rectangular dimples. Partial texturing somewhat improves the lubrication performance of inclined slider bearings. The number of dimples with the maximum load-carrying capacity (LCC) and minimum friction is determined. When the major axis of the dimple is arranged in the sliding direction, the LCC and friction reduction are maximized. However, full texturing significantly reduces the LCC of the slider bearing and increases the flow rate. The results have the potential to improve the lubrication performance of various sliding bearings, but further research is required.

• 한국기계가공학회지
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• 제9권4호
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• pp.53-58
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• 2010

In this paper, the output characteristics of PSD(Position Sensetive Detector) used in measurement system are described. Most of the precision measurment systems are accomplished by a laser diode(LD), a photo diode(PD) and PSD(Position Sensetive Detector), which are used in reflection of mirror or projection of infrared spectrometer. But it is especially restricted by resolution of PD and PSD in nano-measurement. A new inclined light methods into the PSD are employed in the surface measurement system for increasing the resolution. As the results, we can know that the output characteristics of detective senser (PSD) become more than 2 or 3 times by changing inclined angle(range: 5 degree) compared with common angle. In addition, the experiment results are confirmed that the change of inclined angle is not affecting to the linearity and repeating.

• Journal of Advanced Marine Engineering and Technology
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• 제22권1호
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• pp.52-66
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• 1998

An experimental study on the flow characteristics was performed for a two-dimensional turbulent wall attaching offset jet at different oblique angles to a surface. The flow characteristics were investigated by using a split film probe with the modified Stock's calibration method. The jet mean velocity, turbulent intensity, wall static pressure coefficient profiles, and time-averaged reattachment point were measured at the Reynolds number Re (based on the nozzle width, D) ranging from 17700 to 53200, the offset ratio H/D from 2.5 to 10, and the inclined angle .alpha. from 0.deg. C to 40.deg. C. The Correlations between the maximum pressure position, minimum pressure position, and reattachment point and offset ratios, and inclined angles are presented.

• Advances in materials Research
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• 제11권1호
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• pp.23-39
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• 2022

This work deals with the two-dimensional deformation in a homogeneous isotropic nonlocal magneto-thermoelastic solid with two temperatures under the effects of inclined load at different inclinations. The mathematical model has been formulated by subjecting the bounding surface to a concentrated load. The Laplace and Fourier transform techniques have been used for obtaining the solution to the problem in transformed domain. The expressions for nonlocal thermal stresses, displacements and temperature are obtained in the physical domain using a numerical inversion technique. The effects of nonlocal parameter, rotation and inclined load in the physical domain are depicted and illustrated graphically. The results obtained in this paper can be useful for the people who are working in the field of nonlocal thermoelasticity, nonlocal material science, physicists and new material designers. It is found that there is a significant difference due to presence and absence of nonlocal parameter.