• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.91-91
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• 2004

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.436-436
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• 2004

• Journal of the Korean Society of Physical Medicine
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• v.8 no.3
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• pp.417-424
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• 2013

PURPOSE: We investigated the relationship between the segment of erector spinae during a core stability exercise according to visual control. METHODS: The subjects of this study were 20 healthy students. An 8-channel electromyograph was used to measure muscle activities of the erector spinae by segment(cervical, thoracic and lumbar) during a core stability exercise according to visual control. The collected data were analyzed using the independent t-test and Pearson-test. RESULTS: The activity of the erector spinae for all segment was higher without the vision than with. The activity of right cervical erector spinae was significantly increased by increasing the activity of the left thoracic erector spinae during a core stability exercise with vision (r= .555). The activity of left thoracic erector spinae was significantly increased by increasing the activity of the left lumbar erector spinae during a core stability exercise without vision (r= .472). CONCLUSION: There was a positive correlation between the cervical and thoracic segment of erector spinae during a core stability exercise with vision. There was a positive correlation between the thoracic and lumbar segment of erector spinae during a core stability exercise without vision.

• The Korean Journal of Emergency Medical Services
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• v.21 no.3
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• pp.35-48
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• 2017

Purpose: The purpose of the study was to investigate the core competency of disaster management of 119 paramedics. Methods: A self-reported questionnaire was completed by 242 paramedics in C area from April 28 to May 12, 2017. The study instrument included general characteristics of the subjects (4 items), disaster experience, recognition, and preparedness (20 items), and importance and performance of disaster management core competency (24 items) by Likert 5-point scale. Data were analyzed using t-test, ANOVA, Pearson's correlation coefficient using IBM SPSS 24.0. Results: The seriousness of personal disaster was 4.02 points and the importance of disaster-related education was 4.28 points. The importance to core competency of disaster management was 4.39 points and the ability to perform core competency was 3.58 points. The seriousness of personal disaster and the importance of disaster-related education were positively correlated (r=.600, p=.000). The importance and ability to perform core competency were positively correlated (r=.389, p=.000). Conclusion: It is necessary to strengthen core competency of disaster management in paramedics who are the first defense line of disaster.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.1
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• pp.30-40
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• 2004

Purpose : The purpose of this study was aimed to compare the shear bond strength on dentin of three dentin bonding agents and two resin cements used in conjunction with self-cured composite resin core material. Material and method : Control group and six experimental groups were divided for this study. Control group was designated as specimens bonded with Tenure$ A&B^{(R)}$. Experimental groups were as follows : PB-BL group : specimens bonded with Prime&Bond $NT^{(R)}$, $BondLink^{(R)}$ SB-BL group : specimens bonded with $^{(R)}$, BondLink$SingleBond^{(R)}$ PB group : specimens bonded with Prime&Bond $NT^{(R)}$ SB group : specimens bonded with $SingleBond^{(R)}$ PF group : specimens bonded with $Panavia-F^{(R)}$ BI group specimens bonded with Bistite $II^{(R)}$ All specimens were stored in $37^{\circ}C$ distilled water for 24 hours, followed by the shear bond strength was tested by universal testing machine. The data was analysed statistically by Mann-Whitney test. Results : 1. For Prime&Bond $NT^{(R)}$ and $SingleBonde^{(R)}$, the shear bond strength was 0.24 MPa and 7.19 MPa each by each, while Tenure $A&B^{(R)}$ group control was measured at 13.93 MPa (p<0.05). Especially for Prime&Bond $NT^{(R)}$ it did not get conjunction with dentin. 2. For Prime&Bond $NT^{(R)}$ and $SingleBond^{(R)}$ using $BondLink^{(R)}$, there was no significant difference as a result of 11.73 MPa and 14.00 MPa each by each (p<0.05). 3. For $Panavia-F^{(R)}$ and Bistite $II^{(R)}$, they showed the highest shear bond strength as measured by 18.24 MPa and 16.09 MPa each (p<0.05).

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.6
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• pp.91-97
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• 2015

The limit values of mechanical properties(MPs) of HTPB/AP/Al Solid Propellant was reviewed according to the rocket motor development procedures and the in-process values of MPs were analyzed by the tool of Process Capability Index. Based on finding the dependency among MPs, the optimization is proposed for reducing the properties defects and for improving the rocket grain safeties.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.1
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• pp.58-68
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• 2016

The propellant mixer for charging of solid rocket motors is one of the most important equipments. For the propellant mixer is export control item, it's hard to purchase it directly from abroad. The Mixer was developed locally to overcome export control which precludes us from import. This paper includes the introduction for general mixers and the process of mixer development progressed by LIGNex1. Finally, The mixer is verified the performance using measurements of clearance between blade-blade and blade-bowl and flow simulation with ADINA.

• Journal of Magnetics
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• v.13 no.4
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• pp.170-172
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• 2008

Fe-6.5% Si alloys have good magnetic properties due to their high electrical resistivity, very low magneto-striction, and low crystalline anisotropy. Despite their strong potential, these alloys have seldom been used in magnetic applications because of the very poor ductility of Si-steel above 3.0 wt% Si [1-4]. It is difficult to achieve compressed Fe-6.5% Si powder cores with excellent properties because of the low density due to poor ductility. In compressed powder cores, high density is essential in order to obtain high magnetization and permeability. In this study, an attempt was made to produce Fe-3%Si powder cores because the Fe-3.0 wt% Si alloys have relatively good magnetic properties and room temperature ductility. Gas atomized Fe-3.0 wt% Si powder was compressed into toroid shape cores. By reducing the Si content to 3.0 wt%, the hysteresis loss could be greatly reduced and thus the total core loss could be minimized. The total core loss is 600 mW/$cm^3$ at 0.1 T and 50 kHz.

• Advances in aircraft and spacecraft science
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• v.6 no.2
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• pp.169-187
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• 2019

This work presents a practical detailed finite element (FE) approach for the three-dimensional (3D) free-vibration analysis of actual aircraft and spacecraft-type lightweight and thin honeycomb sandwich panels. It consists of calling successively in $MATLAB^{(R)}$, via a developed user-friendly GUI, a detailed 3D meshing tool, a macrocommands language translator and a commercial FE solver($ABAQUS^{(R)}$ or $ANSYS^{(R)}$). In contrary to the common practice of meshing finely the faces and core cells, the proposed meshing tool represents each wall of the actual hexagonal core cells as a single two-dimensional (2D) 4 nodes quadrangularshell element or two 3 nodes triangular ones, while the faces meshes are obtained simply using the nodes at the core-faces interfaces. Moreover, as the same 2D FE interpolation type is used for meshing the core and faces, this leads to an automatic handling of their required FE compatibility relations. This proposed approach is applied to a sample made of very thin glass fiber reinforced polymer woven composite faces and a thin aluminum alloy hexagonal honeycomb core. The unknown or incomplete geometric and materials properties are first collected through direct measurements, reverse engineering techniques and experimental-FE modal analysis-based inverse identification. Then, the free-vibrations of the actual honeycomb sandwich panel are analyzed experimentally under different boundary conditions and numerically using different mesh basic cell shapes. It is found that this approach is accurate for the first few modes used for pre-design purpose.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3A
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• pp.368-376
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• 2006

This paper describes a Fcore_GenSim(Parameterized FFT Core Generation & Simulation Program), which can be used as an essential If(Intellectual Property) in various OFDM modem designs. The Fcore_Gensim is composed of two parts, a parameterized core generator(PFFT_CoreGen) that generates Verilog-HDL models of FFT cores, and a fixed-point FFT simulator(FXP_FFTSim) which can be used to estimate the SQNR performance of the generated cores. The parameters that can be specified for core generation are FFT length in the range of 64 ~2048-point and word-lengths of input/output/internal/twiddle data in the range of 8-b "24-b with 2-b step. Total 43,659 FFT cores can be generated by Fcore_Gensim. In addition, CBFP(Convergent Block Floating Point) scaling can be optionally specified. To achieve an optimized hardware and SQNR performance of the generated core, a hybrid structure of R2SDF and R2SDC stages and a hybrid algorithm of radix-2, radix-2/4, radix-2/4/8 are adopted according to FFT length and CBFP scaling.