• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1B
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• pp.71-82
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• 2007

Recent advances in optical-network technologies have led to the advent of broadband networks reaching 10 Gbps. The increase of available network bandwidth envisions wide-spread use of broadband applications such as uncompressed Internet HDTV, which would be a cutting-edge application for networked collaborations. Despite of breakthroughs in high-performance systems and networks, expensiveness blocks wide-range deployments of uncompressed Internet HDTV systems. In this paper, we propose a low-cost uncompressed Internet HDTV system and discuss its software architecture in depth. We conducted several network-based experiments utilizing a research network test-bed to evaluate the performance of the proposed system.

• Tunnel and Underground Space
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• v.14 no.5
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• pp.345-352
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• 2004

In a shotcrete support system, the cooperation of the ground and the shotcrete lining makes it possible to transfer the shear stress to the shotcrete lining, which is dedicated to form a stable structure. In this study, a homogeneous model ground with constant strength was produced by using gypsum and the tunnel was excavated with a top heading method under the definite initial stress. During the excavation, the stress in the ground around the tunnel and the deformation of shotcrete lining were measured, The tensile stress was generated in tangential direction in the ground near the tunnel and in the shotcrete lining due to tunnel excavation. This shows the unified behavior of the ground and shotcrete lining, which is the most typical characteristic of the shotcrete support. As a result, the rates of in-situ stress during the excavation at a top boundary line was 9% and at top arch heading 15%. It was 48% right after excavating the heading and 94% before cutting the bench.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.3
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• pp.315-325
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• 2017

The design dimension may not be satisfactory at the final stage due to the welding during the assembly stage, leading to cutting or adding the components in large structure constructions. The productivity is depend on accuracy of the welding quality especially at assembly stage. Therefore, it is of utmost importance to decide the component dimension during each assembly stage considering the above situations during the designing stage by exactly predicting welding deformation before the welding is done. Further, if the system that predicts whether welding deformation is equipped, it is possible to take measures to reduce deformation through FE analysis, helping in saving time for correcting work by arresting the parts which are prone to having welding deformation. For the FE analysis to predict the deformation of a large steel structure, calculation time, modeling, constraints in each assembly stage and critical welding length have to be considered. In case of fillet welding deformation, around 300 mm is sufficient as a critical welding length of the specimen as proposed by the existing researches. However, the critical length in case of butt welding is around 1000 mm, which is far longer than that suggested in the existing researches. For the external constraint, which occurs as the geometry of structure is changed according to the assembly stage, constraint factor is drawn from the elastic FE analysis and test results, and the magnitude of equivalent force according to constraint is decided. The comparison study for the elastic FE analysis result and measurement for the large steel structure based on the above results reveals that the analysis results are in the range of 80-118% against measurement values, both matching each other well. Further, the deformation of fillet welding in the main plate among the total block occupies 66-89%, making welding deformation in the main plate far larger than the welding deformation in the longitudinal and transverse girders.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.22 no.2
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• pp.174-183
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• 2000

This study was performed to investigate the characteristics of soft tissue profile of the class III malocclusion and to test the yardstick far differential diagnosis between surgical and orthodontic patients. Initial lateral cephalograms of orthodontic group(30 patients) that have acceptable occlusion and profile by orthodontic treatment alone and surgical group(30 patients) that have favorable occlusion and profile by combined surgical-orthodontic treatment were selected in Ajou university hospital. Powell and Burstone II analysis were made on the tracing. Descriptive, comparative, factor, cluster, and discriminant analysis were carried out with computer program. The results were as followings : 1. Patients who received surgery had a more concave profile and a longer lower facial height than patients who received orthodontic treatment alone. 2. Nasolabial angle, ratio of vertical height, and mentolabial sulcus were significantly different at the 5% level. And facial protuberance, upper lip protuberance, mentocervical angle, nasofrontal angle, nasomental angle, mandibular vertical height, angle between cervix and lower face, ratio of mandibular vertical height divided by cervical depth, ratio of vertical height between upper and lower lip, and maxillary protuberance were significantly different at the 1% level. 3. 8 factors were extracted and factor 2, 3, and 8 showed significant differences by factor analysis. 4. Orthodontic group (25) and surgical group (35) were classified by cluster analysis. 5. Discriminant function was D = 0.079Nasomental angle + 0.081Sn-Gn + 3.343Sn-Gn/C-Gn + 1.734Sn-St/St-Me' -26.460, and cutting score was 0, so we can discriminate that orthodontic group has the score above 0, and surgery group below 0. And 91.7% of original grouped cases were correctly classified.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.1C
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• pp.27-35
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• 2012

The relieving platform has the advantage of decreasing the total lateral earth pressure on the retaining wall and increasing the overall stability of the structure. Several modeling tests were performed to determine the earth pressure distribution on the retaining wall with a relieving platform and to compare it with that of the cantilever retaining wall. Different types of soil and angle of cutting surface were used to determine the effect of the soil characteristics and the backfill conditions on these earth pressure distributions. From the modeling tests, comparisons between the retaining wall with a relieving platform and the cantilever retaining wall show that the reduction of the lateral earth pressure and deformation of wall was indicated clearly on the retaining wall with a relieving platform. And the overall stability was increased by the relieving platform.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.5
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• pp.45-52
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• 2020

Recently, design for additive manufacturing (DfAM) technology has become a prominent design methodology for exploiting 3D printing, which leads the Fourth Industrial Revolution. When manufactured by the 3D printing method, it is possible to produce several shapes compared to the conventional casting or cutting process. DfAM-as a newly-proposed design methodology-can be used to specially design products with various shapes to apply functional requirements. Topology optimization verifies load paths to determine the draft design, and a shape-optimized design with objective functions for weight reduction enables efficient lightweight product design. In this study, by using these two DfAM technologies, a lightweight and optimal design is constructed for a node part of a vehicle body with a space frame designed for a lightweight vehicle. DfAM methodologies for concept design and detailed design, and the associated results, are presented. Finally, the product was additively manufactured, a fatigue performance test was performed, and the design reliability was verified.

• Steel and Composite Structures
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• v.27 no.3
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• pp.337-353
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• 2018

In previous weak-axis moment connection tests, brittle fracture always initiated near the edge of the beam flange groove weld due to force flow towards the stiffer column flanges, which is the opposite pattern as strong-axis moment connections. As part of the China NSFC (51278061) study, this paper tested two full-scale novel weak-axis reduced beam section moment connections, including one exterior frame connection specimen SJ-1 under beam end monotonic loading and one interior frame joint specimen SJ-2 under column top cyclic loading. Test results showed that these two specimens were able to satisfy the demands of FEMA-267 (1995) or ANSI/AISC 341-10 (2010) without experiencing brittle fracture. A parametric analysis using the finite element software ABAQUS was carried out to better understand the cyclic performance of the novel weak-axis reduced beam section moment connections, and the influence of the distance between skin plate and reduced beam section, a, the length of the reduced beam section, b, and the cutting depth of the reduced beam section, c, on the cyclic performance was analyzed. It was found that increasing three parametric values reasonably is beneficial to forming beam plastic hinges, and increasing the parameter a is conducive to reducing stress concentration of beam flange groove welds while increasing the parameters b and c can only reduce the peak stress of beam flange groove welds. The rules recommended by FEMA350 (2000) are suitable for designing the proposed weak-axis RBS moment connection, and a proven calculation formulation is given to determine the thickness of skin plate, the key components in the proposed weak-axis connections. Based on the experimental and numerical results, a design procedure for the proposed weak-axis RBS moment connections was developed.

• Journal of the Optical Society of Korea
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• v.20 no.1
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• pp.94-100
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• 2016

A novel optical design for high resolution, large field of view (FOV) and multispectral remote sensing is presented. An f/7.3 Korsch and two f/17.9 Cook three-mirror optical systems are integrated by sharing the primary and secondary mirrors, bias of the FOV, decentering of the apertures and reasonable structure arrangement. The aperture stop of the Korsch system is located on the primary mirror, while those of the Cook systems are on the exit pupils. High resolution image with spectral coverage from visible to near-infrared (NIR) can be acquired through the Korsch system with a focal length of 14 m, while wide-field imaging is accomplished by the two Cook systems whose focal lengths are both 13.24 m. The full FOV is 4°×0.13°, a coverage width of 34.9 km at the altitude of 500 km can then be acquired by push-broom imaging. To facilitate controlling the stray light, the intermediate images and the real exit pupils are spatially available. After optimization, a near diffraction-limited performance and a compact optical package are achieved. The sharing of the on-axis primary and secondary mirrors reduces the cost of fabrication, test, and manufacture effectively. Besides, the two tertiary mirrors of the Cook systems possess the same parameters, further cutting down the cost.

• Journal of the Korean Society for Heat Treatment
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• v.28 no.5
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• pp.239-249
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• 2015

Various amount of NbC carbide was intentionally formed in a matrix-type cold-work tool steel by controlled amount of Nb and C addition. And the effect of NbC addition on the mechanical properties was investigated. Four alloys with different Nb and C contents were cast by vacuum induction melting, then hot forging and spheroidizing annealing were conducted. The machinability of the annealed specimens was examined with 3 different cutting tools. And tensile tests at room temperature were conducted. After quenching and tempering, hardness and impact toughness were measured, while wear resistance was evaluated by disk-on-plate type wear test. The increasing amount of NbC addition resulted in degraded machinability with increased strength, whereas the absence of NbC also led to poor machinability due to high toughness. After quenching and tempering, the additional NbC improved wear resistance with increasing hardness, whereas it deteriorated impact toughness. Therefore, it could be found that a moderate addition of NbC was desirable for the balanced combination of mechanical properties.

• Journal of Korean Home Economics Education Association
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• v.4 no.1
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• pp.57-75
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• 1992

The purpose of this study was to survey the actual condition of education on the western clothing construction in Home Economics and Housework curriculum of high school. And the finding of this study will the helpful to the persons in authority who take part in the course of compilation of the western clothing contruction. The subjects of this study were 101 high school teachers in Chonbuk province. Their responses to the questionaires were analyzed by frequencies and percentiles. The major findings of the study were as follows. 1. Most high school had only a little educational facilities for learning of clothing construction of, if any, they could only show examples in practice. 2 In case of making clothes, students who sew by hand carried out drafting and cutting on their desks in the classroom. When they have practical training, 56.4% of them cheese only one of one-piece dress trousers, and skirt which are presented in the textbook. The related teachers indicated that content composition of the texbook was not fit for the purpose of the students level, and also pointed out the deficiencies of educational facilities, lack of teacher’s research and training, and lack of school hours of evaluation, practical skill was performed in parallel with paper-test at 73.3%. 3. Pajamas and one-piece dress presented in the textbook were the most suitable for the practice at 64.7%. They hoped that illustrations in textbook are so large and full that clothes made through the practice can be worn. Also they hoped that their opinions and wearable guidance will be reflected in the textbook. They emphasized the need of western clothing construction unit because of acquistion of elementary knowledge. The current amount of content composition was enough or excessive. In addition, they understood the curriculum of high school is rather closely connected with that of middles school. Their recognition of the rate of difficulty is very similar to that of other school teachers. They recognized the goal of learning should be applied to the real home life.