• Nuclear Engineering and Technology
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• v.33 no.4
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• pp.397-408
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• 2001

A marine reactor shows very different thermal-hydraulic characteristics compared to a land- based reactor. Especially, study on the variation of flow field due to ship motions such as inclination, heaving and rolling is essential since the flow variation has great influence on the reactor cooling capability. In this study, the natural circulation characteristics of integral type marine reactor with modular steam generators were analyzed using computational fluid dynamics code, CFX-4, for inclined conditions. The numerical analyses are performed using the results of natural circulation experiments for integral reactor which are already conducted at Seoul National University. From the results, it was found that the flow rate in the ascending steam generator cassettes increases due to buoyancy effect. Due to this flow variation, temperature difference occurs at the outlets of the each steam generator cassettes. which is mitigated through downcomer by thermal mixing. Also, around the upper pressure header the flow from descending hot leg goes up to the ascending steam generator cassettes due to large natural circulation driving force in ascending steam generator cassettes. From this result, the increase of How rate in the ascending steam generator cassettes could be understood qualitatively.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.3
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• pp.283-289
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• 2011

In this research a controller based on velocity estimator for a Wheeled Inverted Pendulum (WIP) is designed and various numerical simulation studies are carried out. The WIP has stable and unstable equivalent points. To Keep the unstable equilibrium point, a controller should control carefully the wheels persistently. There are angle, angular velocity, displacement, and velocity of the WIP for controller inputs. The velocity is obtained by differentiating the encoder signals from the motor and is subject to the resolution of the encoder. An improved velocity detection method is proposed based on low resolution encoder and velocity estimator. Various numerical simulations are carried out for showing the validation of the velocity estimator in case of the inclined road condition.

• Geomechanics and Engineering
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• v.13 no.5
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• pp.825-844
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• 2017

This study aimed to find out the pullout capacity of inclined strip anchor plate embedded in anisotropic and nonhomogeneous fully saturated cohesive soil in undrained condition. The ultimate pullout load has been found out by using numerical lower bound finite element analysis with linear programming. The undrained pullout capacity of anchor plate of width B is determined for different embedment ratios (H/B) varying from 3 to 7 and various inclination of anchor plates ranging from $0^{\circ}$ to $90^{\circ}$ with an interval of $15^{\circ}$. In case of anisotropic fully saturated clay the variation of cohesion with direction has been considered by varying the ratio of the cohesion along vertical direction ($c_v$) to the cohesion along horizontal direction ($c_h$). In case of nonhomogeneous clay the cohesion of the undrained clay has been considered to be increased with depth below ground surface keeping $c_v/c_h=1$. The results are presented in terms of pullout capacity factor ($F_{c0}=p_u/c_H$) where $p_u$ is the ultimate pullout stress along the anchor plate at failure and $c_H$ is the cohesion in horizontal direction at the level of the middle point of the anchor plate. It is observed that the pullout capacity factor increases with an increase in anisotropic cohesion ratio ($c_v/c_h$) whereas the pullout capacity factor decreases with an increase in undrained cohesion of the soil with depth.

• Ocean Systems Engineering
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• v.11 no.4
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• pp.373-392
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• 2021

The present paper purposes a numerical evaluation of the Thai Long-Tail Boat propeller (TLTBP) performance by without and with propeller boss cap fins (PBCF) in full-scale operating straight shaft condition in the first. Next, those are applied to inclined shaft conditions. The actual TLTBP has defined an inclined shaft propeller including the high rotational speed, therefore vortex from the propeller boss and boss cap (hub vortex) have been generated very much. The PBCF designs are considered to weaken of vortex behind the propeller boss which makes the saving energy for the propulsion systems. The blade sections of PBCF developed from the original TLTBP blade shape. The integrative for the TLTBP and the PBCF is analyzed to increase the performance using computational fluid dynamics (CFD). The computational results of propeller performance are thoroughly compared between without and with PBCF. Moreover, the effects of each PBCF component are computed to influence the TLTBP performance. The fluid flows around the propeller blades, propeller boss, boss cap, and vortex have been investigated in terms of pressure distribution and wake-fields to verify the increasing efficiency of propulsion systems.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.5
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• pp.91-97
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• 2022

The Directed Energy Deposition (DED) is a representative metal additive manufacturing method. Owing to its strong point of repairment, its application is gradually spreading in aerospace applications, power generation, military components, and mold making. 5-axis cladding is needed to repair damage, such as wear and scratches on cylindrical surfaces to circular-shaped parts, including sleeves and liners. Furthermore, the condition of cladding on inclined parts must also be considered to prevent interference between the nozzle and the part. In this study, the effects of changes in scanning speed due to the 5-axis control system and differences from the height of laser beam irradiation due to inclination are evaluated among the items that should be additionally considered in 5-axis cladding compared to 3-axis cladding. Moreover, the trends of the width and height of the clad are identified by different tilting angles via single line cladding. Lastly, cladding methods on cylindrical surfaces at various angles are proposed to enhance the clad quality and post-processing efficacy. These results can be applied with 5-axis cladding on inclined surfaces, including cylindrical surfaces.

• Journal of Biosystems Engineering
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• v.26 no.3
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• pp.271-278
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• 2001

Many workers in the garlic peeling factory are separating the sound peeled garlics from the unpeeled and defective ones in a manual way. In order to reduce the seasonal labor requirement and operating cost, the mechanized garlic sorting system such as the vision-based garlic sorter should be developed. This study was conducted as one of basic studies on developing quality evaluation technique for peeled garlics, especially to developed the system for acquiring the whole surface images of garlics with a CCD camera. The following results were obtained from this study. 1. The belt-type garlic rotation system was devised to apply for the vision-based garlic sorter and was tested to decide the criteria of design and optimum conveying speed. 2. To evaluate the performance of the developed garlic rotation system, feeding rate and rotating rate were measured under the conditions of four experimental factors such as the inclined angle of rotating belt, the inclined angle of feeding belt, the height of plate arrays on feeding belt and the conveying speed of belts. And the capacity of the system according to mixture ratios of peeled garlics and unpeeled garlics was analyzed as a feasibility test. 3. For the inclined angle of rotating belt 20°and height of plate array on feeding belt 22㎜, the maximum rotating rate for garlic samples including unpeeled ones was 81.1% at the conveying speed of 4.2 garlic/sec. And under these condition, the maximum feeding rate was 85% at the inclined angle of feeding belt 6.5°. 4. The capacity of the developed garlic rotation system was almost constant regardless of mixture ratio of peeled garlics and unpeeled garlics and its range was 2.95∼3.92 garlic/sec. At the conveying speed of 4.2 garlic/sec, the capacity of the garlic rotation system was calculated ad 58∼64 kg/hr. 5. To improve performance of the garlic rotation system, it is recommended to develop a device to slide garlics into feeding belt.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.161-168
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• 2006

The recent unpredictable weather condition, especially abnormal heavy precipitation which is on the verge of PMF, made implement more rigorous design standard. Following these trends, the idea of additional auxiliary spillway, most of them are tunnel around existing one, is adopted to many sites. Tunnel spillway, having free water table is generally consisted of several compartments such as inlet, transition, inclined, curved and stilling parts. It may has some technical problems to be considered. Among them, the surface deterioration due to cavitation is reported many times in the part of irregularities on lining. Including this kind of problem, several technical considerations for tunnel spillway will be handled in this paper during design procedure.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.714-718
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• 1996

The interference phenomenonof a dynamic crack propagation in a inclined DEN(double edge notched) specimen has been investigated by using the dynamic photoelasticity. One crack initiated by static loading is propagated dynamically and experiences a mixed mode condition(interference) as the crack approaches to the inclined edge notch. We use the overdeterministic least-square method to extract dynamic $K_{Id}$ K sub IId/and .sigma. $_{ox}$from the recorded dynamic photoelastic pattern surounding a running crack. The evaluated $K_{Id}$ $K_{IId}$and .sigma. $_{ox}$together with the crack propagation velocity estimate the dynamic crack interference phenomenonenonon

• 한국터널공학회:학술대회논문집
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• 2005.04a
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• pp.359-371
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• 2005

The Cutting slope is to be minimized when a tunnel meets the contour of slope terrain at a right angle around its portal. However, a tunnel portal has been generally installed at a right angle to the longitudinal axis of a tunnel with no consideration of the intersection angle with the slope terrain. This sometimes tended to cause huge cutting slope that resulted in many disadvantage in terms of safty, economy and environment. Therefore, the minimization of cutting slope is studied by taking the intersection angle into account, and the result is compared with that by the conventional method. In addition a design method for the inclined portal to the tunnel axis is proposed through 3D-FEM analysis, also the applicable ground condition is suggested.