• Journal of Welding and Joining
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• v.20 no.6
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• pp.809-815
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• 2002

Metallurgical behavior of laser welded cold rolled low carbon steel was investigated. Welding was performed with CW Nd:YAG laser system. Applied laser power, travel speed and nitrogen blowing pressure were 720W CW, 17mm/s and 196kPa, respectively. According to the test results, many carbide particles were observed on the base metal surface that was polished and etched with nital solution. The carbide particles at the welding heat affected zone were thought to be dissolved during welding process. Microstructural inspection revealed that dissolved carbide particles formed mixed phase of very fine martensite and bainite. Test results also demonstrated that the hardness of matrix remained constant value of around 160Hv over the welding heat affected zone. Dissolved carbide particles, however, showed higher average hardness values of around 276Hv near the fusion boundary and 700Hv at the welding heat affected zone of 0.4mm apart from the fusion line. It was considered that care should be given to minimize the test error when measuring the hardness value since many of the dissolved particles were so small that it was not easy to aim the indentor of the testing machine just on the objects.

• Korean Journal of Materials Research
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• v.14 no.6
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• pp.425-431
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• 2004

A laser welding was applied between sintered tip of Fe-Co-W and low carbon steel shank for the diamond saw blade. The welding characteristics and formation of defects were investigated carefully for the weld fusion zone in different welding condition. Dendrite arm spacing in weld bead decreased with decrease of heat input. Co and W increased and Fe decreased in the weld fusion zone with increase of the heat input. The corresponding change of composition was observed with the change of beam position. The maximum and total length of crack decreased with increase of the heat input. The crack in weld bead was propagated along the dendrite boundary and was caused mainly by the segregation of constituent during the solidification.

• Korean Journal of Remote Sensing
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• v.37 no.4
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• pp.763-776
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• 2021

This paper introduces a method of selecting priority update areas for subdivided land cover maps by training orthoimages and serial cadastral maps in a deep learning model. For the experiment, orthoimages and serial cadastral maps were obtained from the National Spatial Data Infrastructure Portal. Based on the VGG-16 model, 51,470 images were trained on 33 subdivided classifications within the experimental area and an accuracy evaluation was conducted. The overall accuracy was 61.42%. In addition, using the differences in the classification prediction probability of the misclassified polygon and the cosine similarity that numerically expresses the similarity of the land category features with the original subdivided land cover class, the cases were classified and the areas in which the boundary setting was incorrect and in which the image itself was determined to have a problem were identified as the priority update polygons that should be checked by operators.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.2
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• pp.60-67
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• 2015

The finite element (FE) model updating is a commonly used approach in civil engineering, enabling damage detection, design verification, and load capacity identification. In the FE model updating, acceleration responses are generally employed to determine modal properties of a structure, which are subsequently used to update the initial FE model. While the acceleration-based model updating has been successful in finding better approximations of the physical systems including material and sectional properties, the boundary conditions have been considered yet to be difficult to accurately estimate as the acceleration responses only correspond to translational degree-of-freedoms (DOF). Recent advancement in the sensor technology has enabled low-cost, high-precision gyroscopes that can be adopted in the FE model updating to provide angular information of a structure. This study proposes a FE model updating strategy based on data fusion of acceleration and angular velocity. The usage of both acceleration and angular velocity gives richer information than the sole use of acceleration, allowing the enhanced performance particularly in determining the boundary conditions. A numerical simulation on a simply supported beam is presented to demonstrate the proposed FE model updating approach.

• Korean Journal of Metals and Materials
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• v.48 no.4
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• pp.297-304
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• 2010

The microstructure and hardness of $CO_2$ laser welds were investigated in the Ti-stabilized ferritic stainless steel 409L. The observed specimen was welded in a fully penetrated condition in which the power was 5 kW and the welding speed 5 m/min. The grain structure near the bond line of the laser welds was produced by epitaxial growth. The grain size was the largest in the fusion zone, and HAZ showed nearly the same grain size as that of the base metal. The HAZ microstructure consisted of subgrains and precipitates that were less than 100 nm in size and that were located along the subgrain boundaries. On the other hand, the hardness was the highest in the fusion zone due to the large amount of small precipitates present. These were composed of TiN, Ti(C,N) and $TiO_2$+Ti(C,N). The hardness decreased continuously from the fusion zone of the base metal. The HAZ hardness was slightly greater than that of the base metal due to the existence of subgrains and precipitates in the subgrain boundary.

• Journal of Powder Materials
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• v.28 no.2
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• pp.110-119
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• 2021

In this study, the high-temperature oxidation properties of austenitic 316L stainless steel manufactured by laser powder bed fusion (LPBF) is investigated and compared with conventional 316L manufactured by hot rolling (HR). The initial microstructure of LPBF-SS316L exhibits a molten pool ~100 ㎛ in size and grains grown along the building direction. Isotropic grains (~35 ㎛) are detected in the HR-SS316L. In high-temperature oxidation tests performed at 700℃ and 900℃, LPBF-SS316L demonstrates slightly superior high-temperature oxidation resistance compared to HR-SS316L. After the initial oxidation at 700℃, shown as an increase in weight, almost no further oxidation is observed for both materials. At 900℃, the oxidation weight displays a parabolic trend and both materials exhibit similar behavior. However, at 1100℃, LPBF-SS316L oxidizes in a parabolic manner, but HR-SS316L shows a breakaway oxidation behavior. The oxide layers of LPBF-SS316L and HR-SS316L are mainly composed of Cr₂O₃, Fe-based oxides, and spinel phases. In LPBF-SS316L, a uniform Cr depletion region is observed, whereas a Cr depletion region appears at the grain boundary in HR-SS316L. It is evident from the results that the microstructure and the high-temperature oxidation characteristics and behavior are related.

• Journal of the Korean Society of Costume
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• v.60 no.3
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• pp.110-122
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• 2010

The purpose of this study is to analyze the expressional traits and internal meanings of fake design in the 2000s' fashion, based on study of art and design area. For achieving the purpose, this study performed related research works and a demonstrative analysis of fashion collection photographs. The scope of this study is from 2000 to 2009. The results are as follows. Fake design uses trompe-l'oeil which is an art technique related to the meanings of 'deceive or fool the eye'. This eye-deceiving technique has been used for a long time in the art, and particularly noticed as one of techniques of Surrealism. Art works using trompe-l'oeil express familiar and unreasonable world at the same time, and also the fusion of reality and fabrication. Fake design in design area of the 2000s makes people take daily life in unfamiliar way by unusualness and breaking the boundary between real and fake. By fake design, people can enjoy fun and a sense of freedom with amusement rather than unpleasant of being deceived. Fake design in the fashion of the 2000s uses eye-deceiving technique and also focuses on the concept of 'fake'. The expressional traits were categorized as realistic expression, surrealistic expression and fake value expression. The internal meanings were analyzed as breaking boundary between real and fake, rediscover dailiness, new attitude to traditional thinking. In conclusion, fake design in the fashion of the 2000s gives playfulness, fun, feeling of release and will be pursued continually.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.8
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• pp.1996-2015
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• 2023

High-definition (HD) maps can provide precise road information that enables an autonomous driving system to effectively navigate a vehicle. Recent research has focused on leveraging semantic segmentation to achieve automatic annotation of HD maps. However, the existing methods suffer from low recognition accuracy in automatic driving scenarios, leading to inefficient annotation processes. In this paper, we propose a novel semantic segmentation method for automatic HD map annotation. Our approach introduces a new encoder, known as the convolutional transformer hybrid encoder, to enhance the model's feature extraction capabilities. Additionally, we propose a multi-level fusion module that enables the model to aggregate different levels of detail and semantic information. Furthermore, we present a novel decoupled boundary joint decoder to improve the model's ability to handle the boundary between categories. To evaluate our method, we conducted experiments using the Bird's Eye View point cloud images dataset and Cityscapes dataset. Comparative analysis against stateof-the-art methods demonstrates that our model achieves the highest performance. Specifically, our model achieves an mIoU of 56.26%, surpassing the results of SegFormer with an mIoU of 1.47%. This innovative promises to significantly enhance the efficiency of HD map automatic annotation.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.5
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• pp.479-485
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• 2011

A number of case studies that find distribution of longevity population and influencing factors through the spatial data fusion using GIS techniques are growing. The majority cases of these studies are adopt census administrative boundary data for the spatial analysis. However, these methods cannot fully explain the phenomenon of longevity because there are a variety of spatial characteristics within the census administrative boundaries. Therefore, studies of spatial unit are required that realistically reflect the phenomenon of human longevity. The dasymetric mapping method enables to product of spatial unit more realistic than census administrative boundary map and statistic estimates of small area utilizing diversity spatial information. In this study, elderly population of small area has been estimated within statistically significant level that applied the vector based dasymetric mapping method. Also, the cluster analysis confirmed that the variation of local spatial relationship within census administrative boundary. The result of this study implied that the need for local-level studies of the human longevity and the validity of the dashmetric mapping techniques.

• Journal of Korean Neurosurgical Society
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• v.30 no.2
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• pp.201-206
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• 2001

Objective : The purpose of this study was to assess the complications, duration of admission, cost effectiveness, radiologic stabilization of the anterior cervical bone fusion in the treatment of cervical disc disease with and without plating. Materials and Methods : Fifty-two surgically treated patients for cervical disc disease were reviewed. Group I consisted of consecutive treated patients with iliac auto-bone graft without instrumentation after anterior cervical discectomy. Group II consisted of consecutive treated patients with iliac autologous-bone graft with CASPER cervical plate fixations. Radiologic fusion was decided when loss of end plate boundary between graft bone and vertebral body and immobile, maintenance of the disc space were evident on simple dynamic plain films. The patients were discharged after the stabilization of cervical motion by films was of tained. These groups were analysed multiple variably with Mann-Whitney U-test. Results : Group I consisted of 18 patients, group II consisted of 34 patients. Mean age was $49.0{\pm}8.1years$, mean duration of admission was $17.27{\pm}10.51days$, mean costs for treatment was $1,970,000{\pm}475,000won$. In group I, mean age was 47.7(34-60) years, 16 patients had undergo on one-level operation, 2-patients had undergo on two-level operation, mean duration of admission was $28.7{\pm}10.4days$, mean costs for treatment was $2,194,473{\pm}561,639won$. The periods of stabilization was $6.6{\pm}3.36weeks$ on radiologic study. Mean periods of out patient follow up was 16.8(6-64) weeks after discharge. Mean period of radiologic follow up was 17.3(4-6) weeks after surgical operation. In group II, mean age was 49.7(37-62) years and 18 patients one-level operation, 14- patients had undergo on two-level operation and 2-patients three-level operation. Mean duration of admission was $11.24{\pm}3.29days$, mean costs for treatment was $1,850,823{\pm}389,372won$. The periods of stabilization was $5.88{\pm}7.07weeks$ on radiologic study. Mean period of out patients follow up was 16.7(4-60) weeks after discharge. Mean period of radiologic follow up was 12.4(3-52) weeks after surgical operation. The duration of admission showed statistical significance in Group II but other items showed no significant difference between two groups. Conclusions : The more economic, early life return and effective method of cervical disc disease in our series were evident in patients who had undergone, iliac bone graft and plate fixations after anterior discectomy.