• Journal of the Korean Wood Science and Technology
• /
• v.37 no.4
• /
• pp.364-371
• /
• 2009

This study was carried out to investigate the bending strength of the Larix glulam beams which were reinforced with CFRP (Carbon fiber reinforced plastic) of which the reinforcement ratios were 0.7% and 2.1% by volume. In the bending test, the rupture shape of the reinforced glulam shows that the reinforced glulam broke firstly in the lowest bottom layer on which tension was loaded, but did not in the upper part reinforced with the CFRP layer. The upper part of the reinforced layer kept strength and did not break when the reinforced glulam broke firstly at the bottom part of the reinforced layer, but broke secondly as loading was increased. In the glulam beams reinforced with CFRP of which the reinforcement ratio was 0.7% by volume, the bending strength of the reinforced beams was increased by 28% at the first break. When beams broke up to the upper part of the reinforced layer, the bending strength of the reinforced beams was increased by 55%, compared to those of control glulam beams. When the glulam beams were reinforced with CFRP of which the reinforcement ratio was 2.1% by volume, the bending strength of the reinforced beams was increased by 77%, compared to those of control glulam beams. The ratio of the height of calculated neutral axis using failure mode recommended by Romani and the height of actual neutral axis using strain gauge was 1.03 and agreed well.

• Journal of the Korean Wood Science and Technology
• /
• v.37 no.4
• /
• pp.357-363
• /
• 2009

This study was carried out to investigate whether adhesive used in manufacturing glulam can be used to bond wood and GFRP, when considering working process and economical efficiency. The six different glulams were manufactured, changing the adhesives and the mixing ratios of the adhesives, and investigated by the block shear test and the delamination of the water soaking or boiling water soaking. The three glulams were manufactured, using the resocinol resin based adhesive, the PVAc resin based adhesive and the epoxy resin adhesive, and the other three glulams, using the adhesives mixing resocinol resin and PVAc resin. The block shear strength is higher than $7.1N/mm^2$ in all types, which is standard of KS F3021. However, in the wood failure the block shear strength was the highest as 65.9% in the PVAc. The delamination of glulams glued with PVAc adhesive, which was 1.08% in water soaking and 4.16% in boiling water soaking, was lower than 5.00% which is the standard of KS F 3021, and the adhesive strength is good. In glulams glued with only resocinol resin adhesive, the wood layers were good as 1.26% in the water soaking delamination and 0.00% in the boiling water soaking delamination. The GFRP layers were not good as 21.85% in the water soaking delamination but were good as 1.45% in the boiling water soaking delamination.

• The Korean Journal of Emergency Medical Services
• /
• v.14 no.1
• /
• pp.47-63
• /
• 2010

Objective : The objective of this study was to survey the job-related empowerment and job satisfaction of 119 emergency medical technicians provide emergency patients with first aid, to examine the correlation between their empowerment and job satisfaction, and to provide basic materials for developing programs to enhance 119 emergency medical technicians' empowerment and job satisfaction. Methods : The survey was conducted with 249 119 emergency medical technicians working at fire stations in an area of Gyeonggi-do during the period from June 26 to August 21, 2009. Using SPSS 14.0 program, we obtained frequencies percentages, means, and standard deviations, and performed independent two sample t-test, one way ANOVA, and Pearson correlation analysis, and Cronbach's ${\alpha}$. Results : 1) The mean score of the subjects' empowerment was 3.32, and that of their job satisfaction was 2.94. 2) As to difference according to general characteristics, no statistically significant difference was observed in empowerment but job satisfaction was statistically significantly different according to gender(t = 2.296, p = .023). 3) As to difference according to job related characteristics, empowerment was significantly different according to license type(F = 3.767, p = .011), and job satisfaction was statistically significantly different according to position(t = 3.222, p = .042), fire fighting experience(t = 2.689, p = .035), and first aid experience(t = 3.991, p = .007). 4) Empowerment was in a positive correlation with job satisfaction(r = .502, p = .000) in general, and by the sub areas of job satisfaction, the correlation with empowerment was high in order of job itself(r = .695, p = .000), interaction area(r = .493, p = .000), organizational demand area(r = .328, p = .000), working condition area(r = .153, p = .015), and wage area(r = .137, p = .031). By the sub areas of empowerment, the correlation with job satisfaction was high in order of significance(r = .424, p = .000), influence(r = .397, p = .000), competence(r = .372, p = .000), and self determination(r = .259, p = .000). Conclusion : The 119 emergency medical technicians' empowerment was in a high correlation with their job satisfaction, and had a strong effect on it. This suggests that 119 emergency medical technicians' job performance can be enhanced by improving their empowerment. These results are expected to be useful in making human resource management plans to enhance 119 emergency medical technicians' job satisfaction by empowering them.

• Journal of Korean Society of Forest Science
• /
• v.108 no.4
• /
• pp.592-599
• /
• 2019

This study aimed to develop an equation for estimating stem volume for Larix kaempferiin South Korea using independent variables, diameter at breast height (DBH), and height as being closely associated with stem volume. Analysis was conducted on the growth performance of 2,840 Larix kaempferi samples across South Korea after felling them and gleaning diameter data according to both stem height and stem analyses. In order to test the fitness of six different stem taper equations, empirical assessment was conducted for fitness index (FI), bias, mean, and absolute deviation (MAD), and coefficient variation (%CV). The two selectedmodels found to be optimal were the following: model one (V=a+bDBH²), established by employing DBH only; and model four (V=a+bDBH²H), established by utilizing DBH and height, respectively. The findings of non-linear regression indicated statistical significance (p < 0.05) in a and b, which were the coefficients for the intercepts and slopes of the models. The FI of the models ranged between 94% and 99%, and the bias was close to zero, while MAD ranged from 0.01 to 0.05, and %CV from 5.97 to 14.43, indicating a high level of fitness. Thus, using the suggested models, the basic information necessary for forest management was obtained, and an estimation of the stem volume was effected without delay soon after effecting DBH and height measurements.

• Journal of the Korea Concrete Institute
• /
• v.28 no.6
• /
• pp.685-693
• /
• 2016

The outer tank of a liquefied natural gas (LNG) storage tank is a longitudinally and meridionally pre-stressed concrete (PSC) wall structure. Because of the current trend of constructing larger LNG storage tanks, the pre-stressing forces required to increase wall strength must be significantly increased. Because of the increase in tank sizes and pre-stressing forces, an extreme loading scenario such as a bomb blast or an airplane crash needs to be investigated. Therefore, in this study, the blast resistance performance of LNG storage tanks was analyzed by conducting a blast simulation to investigate the safety of larger LNG storage tanks. Test data validation for a blast simulation of reinforced concrete panels was performed using a specific FEM code, LS-DYNA, prior to a full-scale blast simulation of the outer tank of a 270,000-kL LNG storage tank. Another objective of this study was to evaluate the safety and serviceability of an LNG storage tank with respect to varying amounts of explosive charge. The results of this study can be used as basic data for the design and safety evaluation of PSC LNG storage tanks.

• Convergence Security Journal
• /
• v.5 no.4
• /
• pp.41-48
• /
• 2005

Objective of this study is to design and implement security system based on intrusion tolerance technology for the improvement of dependability in defense system. In order to do so, I identify and extract core technologies through the research and analysis into characteristics, structures, main functions, and technologies of intrusion tolerance architecture. And I accomplish a design of security system through the redundant system based on these core technologies. To implement and verify intrusion tolerance system, I chose 'wargame system' as a subjected system, and accomplished 'Wargame Intrusion Tolerance System' and verified security required functions through a performance test. By applying showed security system into the development of application software based on intrusion tolerance, systematic and efficient system could be developed. Also applying 'WITDS' can solve the current security problems, and this will be basic model for design of security architecture in the federation system after.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.11 no.5
• /
• pp.23-32
• /
• 2007

The goal of this study is to perform several bending tests on a shape memory alloy bar and to analyze the characteristics of the bending behavior. The other goal is to verify the seismic performance of an SMA bar bending application. Single and double bending tests were conducted with varying loading speeds and maximum displacement. The loading and the unloading stiffness were estimated from the force-displacement curves and the equivalent damping ratio of each test was also assessed. In single bending, the SMA bar showed the stiffness hardening after the displacement of 32 mm. It is assumed that this phenomenon is due to the stress-induced-martensite hardening. The increasing loading speed did not influence on the stiffness of the single bending SMA bar. The stiffness of the double bending bar is about 5 times of that of the single bending. This study introduced a seismic application of SMA bending bars as seismic restrainers for bridges and showed its practicality. SMA bars in bending are used for seismic restrainers in a three-span-simply-supported bridge. They showed the effectiveness to reduce the responses of the bridge and the applicability for a seismic restrainer. The significance of this study is to provide basic knowledge of SMA bending and its seismic applications.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.8
• /
• pp.789-798
• /
• 2011

We carry out an experimental investigation to analyze the basic performance of NO(nitric oxide) storage in a lean phase and also analyze the NO reduction achieved by the spraying of reducing agents in the rich phase of the exhaust gas in an LNT(Lean NOx Trap). This is an after-treatment system used to reduce the NOx emissions from a diesel engine. If the stored NO is reduced, we measure the outlet concentration downstream of the LNT. The test LNT material used in the experiments is commercial LNT. After being canned into stainless-steel(SUS304), it was built in a micro bench-flow reactor. Compositions of feed gases, three heated and three no heated gases were sprayed upstream of the LNT to analyze the characteristics. We use various temperatures and space velocities as response variables.

• Korean Journal of Optics and Photonics
• /
• v.4 no.1
• /
• pp.15-21
• /
• 1993

This paper describes the design and development of a KrF excimer laser stepper and discusses the detailed system parameters and characterization data obtained from the performance test. We have developed a deep UV step-and-repeat system, operating at 248 nm, by retrofitting a commercial modules such as KrF excimer laser, precision wafer stage and fused silica illumination and 5X projection optics of numerical aperture 0.42. What we have developed, to the basic structure, are wafer alignment optics, reticle alignment system, autofocusing/leveling mechanisms and environment chamber. Finally, all these subsystem were integrated under the control of microprocessor-based controllers and computer. The wafer alignment system comprises the OFF-AXIS and the TTL alignment. The OFF-AXIS alignment system was realized with two kinds of optics. One is the magnification system with the image processing technique and the other is He-Ne laser diffraction type system using the alignment grating on the wafer. 'The TTL alignment system employs a dual beam inteferometric method, which takes advantages of higher diffraction efficiency compared with other TTL type alignment systems. As the results, alignment accuracy for OFF-AXIS and TTL alignment system were obtained within 0.1 $\mu\textrm{m}$/ 3 $\sigma$ for the various substrate on the wafers. The wafer focusing and leveling system is modified version of the conventional systems using position sensitive detectors (PSD). This type of detection method showed focusing and leveling accuracies of about $\pm$ 0.1 $\mu\textrm{m}$ and $\pm$ 0.5 arcsec, respectively. From the CD measurement, we obtained 0.4 $\mu\textrm{m}$ resolution features over the full field with routine use, and 0.3 $\mu\textrm{m}$ resolution was attainable under more strict conditions.

• Journal of the Institute of Convergence Signal Processing
• /
• v.15 no.1
• /
• pp.15-22
• /
• 2014

This paper presents the implementation of a control system of pellet boiler using wood pellet as carbon neutral material. The system also has the additional features to provide remote controlling and monitoring based on home networking technology through either public switched telephone networks or mobile communication networks. It consists of three kinds of sub-modules; a main controller provides basic and additional features such as a setting of temperature, a supplying of wood pellet, a controlling of ignition and fire-power, and a removing of soot. The second is temperature controller of individual rooms which is connected to the main controller through RS-485 links. And interface modules with PSTN and mobile networks can support remote controlling and monitoring the functions. The test results under the heating area of $172m^2$ show a thermal efficiency of 93.6%, a heating power of 20,640kcal/hr, and a fuel consumption of 5.54kg/hr. These results are superior to those of the conventional pellet boilers. In order to obtain the such high performance, we newly applied a 3-step ignition flow, a flame detection by $C_dS$ sensor, and a fire-power control by fine controlling of shutter to our pellet boiler.