• Journal of the Society of Naval Architects of Korea
• /
• v.35 no.4
• /
• pp.98-108
• /
• 1998

Hull design data is currently prepared by a 2D CAD system and re-input to 3D CAD systems specialized for detail design or to a structural analysis system. In this paper, sharing design data among different CAD systems has been studied. Based on STEP methodology, a neutral model is generated from 2D AutoCAD drawings. To handle a geometric data of this model, the non-manifold model of ACIS is used because it can support various CAD data representation such as 2D graphic entities, 3D wireframe, 3D surface model, and solid B-Rep/CSG model. It is observed that a mon-manifold model can easily be transformed to a 3-D wireframe model for the hull detail design system AutoDef or a FE model for the structural analysis system Nastran.

• Journal of the Korean Society of Physical Medicine
• /
• v.13 no.2
• /
• pp.157-165
• /
• 2018

PURPOSE: The purpose of this study was carried out to investigate the effect of plyometric training combined with core strength training on the balance and agility of adolescent soccer players. METHODS: A total of 36 subjects participated in this study. Subjects were randomly divided 3 groups and assigned PG (plyometric training group), CSG (core strength training group) and PCG (plyometric training combined with core strength training group). Each group was assigned to 12. Intervention was performed three times a week for 4 weeks. The training was performed for 60 minutes a day. Subjects were warmed up for 10 minutes, and performed main exercise for 40 minutes. Finally, subjects performed cool-down exercise including stretching for 10 minutes. A Statistical analysis was performed the paired t-test for the comparison pre and post intervention. A comparison among the groups was using one-way ANOVA, and the LSD was used for the post-test. RESULTS: The balance and agility were statistically significant differences in all group (p<.05). There was no significant difference in the balance factors between the three groups, but there was a significant difference in the agility factor (p<.05). CONCLUSION: Plyometric training and plyometric training combined with core strength training were effective for the balance and agility of adolescent soccer players.

• International Journal of Aerospace System Engineering
• /
• v.9 no.1
• /
• pp.1-15
• /
• 2022

Pyrotechnic initiators provide a source of pyrotechnic energy used to initiate a variety of space mechanisms. Pyrotechnic systems build in electromagnetic environment that may lead to critical or catastrophic hazards. Special precautions are need to prevent a pulse large enough to trigger the initiator from appearing in the pyrotechnic firing circuits at any but the desired time. The EMC verification shall be shown by analysis or test that the pyrotechnic systems meets the requirements of inadvertent activation. The MIL-STD-1576 and two range safeties, AFSPC and CSG, require the safety margin for electromagnetic potential hazards to pyrotechnic systems to a level at least 20 dB below the maximum no-fire power of the EED. The PC23 is equivalent to NASA standard initiator and the 1EPWH100 squib is ESA standard initiator. This paper verifies the two safety margins for electromagnetic potential hazards. The first is verified by analyzing against a RF power. The second is verified by testing against a DC current. The EMC safety margin requirement against RF power has been demonstrated through the electric field coupling analysis in differential mode with 21 dB both PC23 and 1EPWH100, and in common mode with 58 dB for PC23 and 48 dB for 1EPWH100 against the maximum no-fire power of the EED. Also, the EMC safety margin requirement against DC current has been demonstrated through the electrical isolation test for the pyrotechnic firing circuits with greater than 20 dB below the maximum no-fire current of the EED.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.2 s.233
• /
• pp.333-340
• /
• 2005

Feedrate is one of the factors that have the significant effects on the productivity, qualify and tool life in the cutting mechanism as well as cutting velocity, depth of cut and width of cut. In this study, in order to realize the high-efficient machining, a new feedrate optimization method is proposed based on the concept that the optimum feedrate can be derived from the allowable cutting power since the cutting power can be predicted from the cutting parameters as feedrate, depth of cut, width of cut, chip thickness, engagement angle, rake angle, specific cutting force and so on. Tool paths are extracted from the original NC program via the reverse post-processing process and converted into the infinitesimal tool paths via the interpolation process. And the novel NC program is reconstructed by optimizing the feedrate of infinitesimal tool paths. Especially, the fast feedrate optimization is realized by using the Boolean operation based on the Goldfeather CSG rendering algorithm, and the simulation results reveal the availability of the proposed optimization method dramatically reducing the cutting time and/or the optimization time. As a result, the proposed optimization method will go far toward improving the productivity and qualify.

• The Plant Pathology Journal
• /
• v.30 no.3
• /
• pp.279-287
• /
• 2014

KYC 3262 was selected as a biocontrol agent against anthracnose on hot pepper from 813 extracts of myxobacterial isolates. Dual culture with Colletotrichum acutatum and 813 myxobacterial extracts was conducted, and 19 extracts were selected that inhibited germination and mycelial growth of C. acutatum. All selections were Sorangium cellulosum, which are cellulolytic myxobacteria from soil. With the infection bioassay on detached fruits in airtight containers, KYC 3262, KYC 3512, KYC 3279, and KYC 3584 were selected. The listed four myxobacteria were cultured in CSG/1 liquid media, and harvested filtrates were sprayed on the infected fruits. KYC 3262 was selected from the studies of attached fruit in a greenhouse study. KYC 3262 filtrate was applied for 3 years (from 2011 to 2013) in a field study in Asan, Republic of Korea. Control values of the KYC 3262 in the field were 31%, 89%, and 82% in 2011, 2012, and 2013, whereas values of the fungicide spray treatment were 19%, 97%, and 91%, respectively. Yields (kg/20 plants) of the KYC 3262 were 2.66 kg and 18.6 kg in 2011 and 2013, respectively, and those of the fungicide treatment were 2.0 kg and 20.2 kg, in 2011 and 2013, respectively.

• Korean Journal of Computational Design and Engineering
• /
• v.20 no.2
• /
• pp.145-158
• /
• 2015

ISO 15926 is an international standard for the sharing and integration of plant lifecycle information. Plant design data consist of logical configuration, equipment specifications, 2D piping and instrument diagrams (P&IDs), and 3D plant models (shape data). Although 3D computer-aided design (CAD) data is very important data across the plant lifecycle, few studies on the exchange of 3D CAD data using ISO 15926 have been conducted so far. For this, we analyze information requirements regarding plant 3D design in the process industry. Based on the analysis, ISO 15926 templates are defined for the representation of constructive solid geometry (CSG) - based 3D design data. Since system environments for 3D CAD modeling and Semantic Web technologies are different from each other, we present system architecture for processing and visualizing plant 3D design data in the Web Ontology Language (OWL) format. Through the visualization test of ISO 15926-based 3D design data for equipment with a prototype system, feasibility of the proposed method is verified.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.3
• /
• pp.1060-1068
• /
• 2018

Droop control schemes have been widely employed in the control strategies for Multi-Terminal Direct Current (MTDC) system for its high reliability. Under the conventional DC voltage-active power droop control, the droop slope applies a proportional relationship between DC voltage error and active power error for power sharing. Due to the existence of DC network impedance and renewable resource fluctuation, there is inevitably a DC voltage deviation from the droop characteristic, which in turn results in inaccurate control of converter's power. To tackle this issue, a piecewise droop control with DC voltage dead band or active power dead band is implemented into controller design. Besides, an advanced droop control scheme with versatile function is proposed, which enables the converter to regulate DC voltage and AC voltage, control active and reactive power, get participated into frequency control, and feed passive network. The effectiveness of the proposed control method has been verified by simulation results.

• Journal of the Architectural Institute of Korea Structure & Construction
• /
• v.36 no.1
• /
• pp.155-162
• /
• 2020

The aim of the research is to investigate the fundamental properties and heat of hydration reducing performance of the fly ash incorporated concrete mixture when the coal gas slag (CGS) from integrated gasification combined cycle (IGCC) is used as fine aggregate. From the results of the experiment, the workability was generally increased and the air content was decreased up to one to four percent with increasing the replacing ratio of CGS to fine aggregate. The compressive strength was similar or increased within five percent to the Plain mixture when the CGS was used as a fine aggregate. When the CGS and fly ash were used same time, the heat of hydration reducing performance was improved than single using cases either CGS or fly ash. Based on the results, for the concrete mixture using CSG as a portion of the combined fine aggregate, the general properties were improved and heat of hydration was decreased approximately 16 % when the fly ash was replaced 30 % to cement and the CGS was replaced less than 50 % to fine aggregate.

• Korean Journal of Computational Design and Engineering
• /
• v.20 no.4
• /
• pp.385-400
• /
• 2015

ISO 15926 is an international standard for the integration and sharing of plant lifecycle data. Plant 3D design data typically consist of logical configuration, equipment specifications and ports, and 3D shape data. This paper presents the method for the ISO 15926-based integration of plant 3D design data. For this, reference data (class, attribute, and template) of ISO 15926 were extended to describe plant 3D design data. In addition to the data model extension, a plant design information integration platform which reads plant 3D design data in ISO 15926 and displays 3D design information was developed. Finally, the prototype platform is verified through the experiment of loading and retrieving plant 3D design data in ISO 15926 with the platform.

• Structural Engineering and Mechanics
• /
• v.71 no.3
• /
• pp.291-303
• /
• 2019

In the paper the analysis of natural vibrations of the transmission line with use of spectral elements and the laboratory experiments is performed. The purpose of the investigation is to analyze the natural vibrations of the transmission line and compare with the results obtained in the numerical simulations. Particular attention is paid to the hysteretic and aerodynamic damping analysis. Sensitivity of the wave number is performed for changing of the tension force, as well as for the different damping parameters. The numerical model is made using the Spectral Element Method. In the spectral model, for various parameters of stiffness, damping and tension force, the system response is checked and compared with the results of the accelerations obtained in the measurements. A frequency response functions (FRF) are calculated. The credibility of the model is assessed through a validation process carried out by comparing graphical plots of FRF and time history analysis and numerical values expressing differences in acceleration amplitude (MSG), phase angle differences (PSG) and differences in acceleration and phase angle total (CSG) values. The next aspect constituting the purpose of this paper is to present the wide possibilities of modelling and simulation of slender conductors using the Spectral Element Method. The obtained results show good accuracy in the range of both experimental measurements as well as simulation analysis. The paper emphasizes the ease with which the sensitivity of the conductor and its response to changes in density of spectral mesh division, tensile strength or material damping can be studied.