• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.980-981
• /
• 2006

In this study, bottom-up type powder processing and top-down type SPD (severe plastic deformation) approaches were combined in order to achieve full density of Carbon nanotube (CNT)/metal matrix composites with superior mechanical properties by improved particle bonding and least grain growth, which were considered as a bottle neck of the bottom-up method using the conventional powder metallurgy of compaction and sintering. ECAP (equal channel angular pressing), the most promising method in SPD, was used for the CNT/Cu powder consolidation. The powder ECAP processing with 1, 2, 4 and 8 route C passes was conducted at room temperature.

• The Korean Journal of Applied Statistics
• /
• v.30 no.1
• /
• pp.181-193
• /
• 2017

The paper introduces bottom-up and optimal combination methods that can analyze and forecast hierarchical time series. These methods allow forecasts at lower levels to be summed consistently to upper levels without any ad-hoc adjustment. They can also potentially improve forecast performance in comparison to independent forecasts. We forecast regional traffic accident counts as time series data in order to identify efficiency gains from hierarchical forecasting. We observe that bottom-up or optimal combination methods are superior to independent methods in terms of forecast accuracy.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2003.08a
• /
• pp.163-163
• /
• 2003

• Proceedings of the Korean Vacuum Society Conference
• /
• 2003.08a
• /
• pp.189-189
• /
• 2003

• Journal of the Korean Geotechnical Society
• /
• v.37 no.3
• /
• pp.43-50
• /
• 2021

On the construction of new roads, the cut slope is inevitable and thus has been widely applied in the mountainous area. Particularly, the retaining wall with the precast concrete panel is often selected for its higher stability and mostly constructed in bottom-up method. However, the bottom-up method results in steeper slope as 1:0.05 before constructiong retaining wall and thus causes poor compaction at backfill which may induce instability during or after the construction. To overcome this problem, precast concrete panel retaining wall was attached in-situ ground (so called top-down). This paper presents the evaluation of drainage capacity of top-down method which has impermeable layer between panel and mortar being used to increase the ability of attachment of the precast concrete panel.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2004.08a
• /
• pp.711-714
• /
• 2004

A new design for improving the aperture ratio of bottom emission type AMOLED is investigated. In conventional, the TFT of AMOLED fabrication method is "Etch Stopper (7-mask)", so the aperture ratio is limited in 28${\sim}$33% by Cs(Storage Capacitor). A high aperture ratio TFT is designed by using BCE(Back Channel Etching 5-mask) fabrication way and the aperture ratio is up to 40% shown in 2.2"AMOLED display.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.16 no.5
• /
• pp.209-214
• /
• 2021

Panoptic segmentation, which is now widely used in computer vision such as medical image analysis, and autonomous driving, helps understanding an image with holistic view. It identifies each pixel by assigning a unique class ID, and an instance ID. Specifically, it can classify 'thing' from 'stuff', and provide pixel-wise results of semantic prediction and object detection. As a result, it can solve both semantic segmentation and instance segmentation tasks through a unified single model, producing two different contexts for two segmentation tasks. Semantic segmentation task focuses on how to obtain multi-scale features from large receptive field, without losing low-level features. On the other hand, instance segmentation task focuses on how to separate 'thing' from 'stuff' and how to produce the representation of detected objects. With the advances of both segmentation techniques, several panoptic segmentation models have been proposed. Many researchers try to solve discrepancy problems between results of two segmentation branches that can be caused on the boundary of the object. In this survey paper, we will introduce the concept of panoptic segmentation, categorize the existing method into two representative methods and explain how it is operated on two methods: top-down method and bottom-up method. Then, we will analyze the performance of various methods with experimental results.

• Nuclear Engineering and Technology
• /
• v.56 no.2
• /
• pp.506-519
• /
• 2024

To simulate the verification process using materials from a decommissioned reactor, a mock-up of the bottom-mounted instrument nozzle in the Kori 1 reactor, where the nozzle was attached to a plate by J-groove dissimilar metal welding, was fabricated. The mock-up distortion was quantified by measuring the plate surface displacement after welding. The residual stresses formed on the support plate surface and the inner surface of the nozzle were then analyzed using the hole-drilling method, contour method, and neutron diffraction. Welding simulations were performed using a 3D finite element method to validate the measured results. The measured and computed stress distributions on the support plate exhibited reasonable agreement. Conversely, the stresses on the inside of the nozzle were found to have an indisputable difference in the contour method and neutron diffraction measurements, which demonstrated strong tensile and compressive hoop stresses, respectively. The possible origins of such differences were investigated and we have provided some suggestions for a precise evaluation in the simulation. This study is expected to be useful in future research on decommissioned reactors.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 1996.10a
• /
• pp.198-207
• /
• 1996

Electro sensitive traffic system can't consider passenger car unit, so, it causes start up delay time and passenger waiting time. In this paper, it antecedently creates optimal traffic cycle of passenger car unit at the bottom traffic intersection. But, sometimes it can make mistakes due to changes in car weight, car speed, and control of feed-back data. Moreover, to prevent spillback, it can adapt control even though upper traffic intersection has a different saturation rate, road length, road slope and road width.

• Journal of Korean Society of Water and Wastewater
• /
• v.24 no.5
• /
• pp.527-536
• /
• 2010

Although the bubble-floc agglomerate floated and formed the float layer on the surface of the water in the DAF process, after inducing in the thickening tank a part of the bubble-floc agglomerate come up again to the surface and the other is settled at the bottom of the tank. The bubble-floc agglomerate divided into two group as the scum on the surface and the sludge of the bottom gives rise to operational troubles for the thickening process. In order to find out the cause of break-up and the effective thickening method for sludge from the DAF process, the composition of the bubble-floc agglomerate was investigated and a series of flotation experiments carried out. There was no difference of composition between the scum on the surface and the sludge of the bottom in the thickening tank. The coagulation was not effective to improve the trouble that the bubble-floc agglomerate divided into the scum and the sludge. It was estimated that for the bubble-floc agglomerate of thickening tank the trouble was caused by not the change or the difference of chemical composition but whether the bubble-floc agglomerate hold bubbles. Furthermore, for the effective thickening of sludge from the DAF process, it is required an additional flotation applied the AS ratio depending upon the solid concentration of sludge as the operation parameter.