• Korean Journal of Materials Research
• /
• v.22 no.1
• /
• pp.16-23
• /
• 2012

Research into the development of high strength (1 GPa) and superior formability, such as total elongation (10%), and stretch-flangeability (50%) in hot-rolled steel was conducted with a thermomechanically controlled hot-rolling process. To improve the overall mechanical properties simultaneously, low-carbon steel using precipitation hardening of Ti-Nb-V multimicroalloying elements was employed. And, ideal microstructural characteristics for the realization of balanced mechanical properties were determined using SEM, EBSD, and TEM analyses. The developed steel, 0.06C-2.0Mn-0.5Cr-0.2(Ti + Nb + V), consisted of ferrite as the matrix phase and second phase of granular bainite with fine carbides (20-50 nm) in both phases. The significant factor of the microstructural characteristics that affect stretch-flangeability was found to be the microstructural homogeneity. The microstructural homogeneity, manifest in such characteristics as low localization of plastic strain and internally stored energy, was identified by grain average misorientation method, analyzed by electron backscattered diffraction (EBSD) and hardness deviation between the phases. In summar, a hot-rolled steel having a composition 0.06C-2.0Mn-0.5Cr-0.2(Ti + Nb + V) demonstrated a tensile strength of 998 MPa, a total elongation of 19%, and a hole expansion ratio of 65%. The most important factors to satisfy the mechanical property were the presence of fine carbides and the microstructural homogeneity, which provided low hardness deviation between the phases.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2007.11a
• /
• pp.252-255
• /
• 2007

Recently military industrial company, utilizing company funded R&D and goverment and industry contracts, has developed ACTS/DACS technology. This technology can be utilized to rapidly steer "smart" bullets, "smart" rounds, tactical missile, cruise missile and kill vehicles for both endo- and exoatmospheric applications. The ACTS/DACS typically consists of a Smart Bus Controller(SCB), a proprietary network firing bus, Smart Pyrotechnic Devices(SPD), rocket motors, and a structure. The SCB communicates with the SPDs over the propretary network firing bus. Each rocket motor contains an SPD which provides rocket motor ignition. Firing energy is stored locally in the SPD so surge currents do not occur in the system as rocket motors are fired. This approach allows multiple, truly simultaneous firings without the need for large, dedicated batteries. Each SPD also functions as a network tranceiver and high reliability fir set all in the space of a single-sided 10 millimeter diameter circuit. The present work develops a new means for igniting explosive materials. The volume of semiconductor bridge (SCB) is over 30 times smaller than a conventional hot wire. We believe that the present work has a potential for development of a new igniter such as smart pyrotechnic device.

• Nuclear Engineering and Technology
• /
• v.41 no.1
• /
• pp.135-142
• /
• 2009

In this investigation, we prepared a 1 and 3-parallel serpentine single PEMFC, which has an active area of $100\;cm^2$ and a flow channel cross section of $1{\times}1mm$. Distribution and transport of water in a non-operating PEMFC were observed by varying flow types and the flow rates (250, 400, and 850 cc/min). This investigation was performed at the neutron imaging facility at the CO1d Neutron RAdiography facility (CONRAD), HMI, Germany of which the collimation ratio and neutron fluence rate are 250, $1{\times}10^{6}n/s/cm^2$, respectively. The neutron image was continuously recorded by a scintillator and lens-CCD coupled detector system every 10 seconds. It has been observed that although the distilled water was supplied into the cathode channel only, the neutron image showed a water movement from the cathode to the anode channel. The water at the cathode channel was completely discharged as soon as the pressurized air was supplied. But the water at the anode channel was not easily removed by the pressurized air except for the 3-parallel serpentine type with 850cc/min of air flow rate. Moreover, the water at the MEA wasn't removed for any of the cases.

• Journal of Korean Foot and Ankle Society
• /
• v.2 no.2
• /
• pp.71-75
• /
• 1998

The fact that, under similar training activities performed in the same environment, march fractures develop in only a certain percentage of the trainees indicates that intrinsic factors are affecting the prevalence of these fractures. Among these intrinsic factors, the relation between foot arch type and the occurance of march fractures was investigated in this study. From 1997 to 1998, at one infantry medical company of infantry corps in Korea, 15 march fracture patients were detected among infantry soldiers. Quantitative measures of the foot arch (longitudinal) structure of 15(30feet) march fracture patients were established and compared with those of 15(30feet) normal person. The results were as follows. 1. From the lateral X-ray film, three parameters (i.e. calcaneal angle, forefoot angle, height to length ratio)were defined to describe the structure of the longitudinal arch of the foot. 2. The mean value of the calcaneal angle of march fracture group and normal control group showed 16.4 degree, 20.5 degree respectively. The difference between two groups was statistically significant (P>0.006), but those of forefoot angle and height to length ratio were not. 3. In the calcaneal angle twenty-six feet(87%) of march fracture group were lower than 17 degrees but twenty-five feet(83%) of normal control group were more than 17 degrees. That is, march fracture were more prevalent in feet with low calcaneal angle. 4. In the low arch foot, the orthotic device might relieve the energy load carried by the foot, thus reducing the incidence of march fractures, and should be analyzed in further study.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.22 no.11
• /
• pp.1071-1077
• /
• 2012

Low frequency noises(up to about 200 Hz) such as booming are mainly caused by particular modes, and in general the solutions may be found based on mode controls where conventional methods such as FEM can be used. However, at higher frequencies between 0.3~1 kHz, as the number of modes rapidly increases, radiation characteristics from structures, performances of damping sheets and sound packages may be more crucial rather than particular modes, and consequently the conventional FEM may be less practical in dealing with this kinds of structure-borne problems. In this context, so-called 'mid-frequency simulation model' based on FE-SEA hybrid method is studied and validated to reduce noise in this frequency region. Energy transmission loss(i.e. air borne noise) is also studied. A dash panel component is chosen for this study, which is an important path that transmits both structure-borne and air borne energies into the cavity. Design modifications including structural modifications, attachment of damping sheets and application of different sound packages are taken into account and the corresponding noise characteristics are experimentally identified. It is found that the dash member behaves as a noise path. The damping sheet and sound packages have similar influences on both sound radiation and transmission loss. The comparison between experiments and simulations shows that this model could be used to predict the tendency of noise improvement.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.31 no.8
• /
• pp.1262-1272
• /
• 2007

The purpose of this study was to examine the development trend of smart fiber by textile companies in Daegu/North Gyeongsang Province. This examination includes the development fields of smart fiber, investment size, information sources and the use degree of those, research-related infrastructure, relationship between companies' characteristics and their interests in smart fiber. Research data were collected by a survey. The definition and classification(4 areas and 12 development products) of smart fiber followed ones of Smart Fiber Technology Roadmap by the Ministry of Commerce, Industry and Energy. Data were analyzed using SPSS 11.0 program for frequency, means, t-test, and $X^2$-test. Among respondents, the numbers of dying and finish companies and export traders were the highest. It revealed that 19.6% of companies were developing smart fibers. Within 12 development products, vapor permeable/waterproof fiber showed to be most being developed, while medical fiber for human has not been developed and wasn't made an investment plan for developing. It was discovered that the biggest problem of smart fiber development was the lack of experts and the best outcome of smart fiber development was preoccupation of future market. It showed that companies got information from textile fairs but didn't often use information sources. The companies appeared to have a weak intention about research of smart fiber. The more important a company considered functionality of textile products and the more innovative and stabler the company was, the higher interest in smart fiber companies had. It was concluded that textile companies in Daegu/North Gyeongsang Province were aware of the importance of smart fiber development but they were not strongly interested in it and not enthusiastic in taking action on it.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.14 no.3
• /
• pp.125-132
• /
• 2006

Transient kinetics of $NH_3$ adsorption/desorption and of SCR(selective catalytic reduction) of NO with $NH_3$ were studied over vanadium based catalysts, such as $V_2O_5/TiO_2$ and $V_2O_5-WO_3/TiO_2$. In the present catalytic reaction process, NO adsorption is neglected while $NH_3$ is strongly chemisorbed on the catalytic surface. Accordingly, it is ruled out the possibility of a reaction between strongly adsorbed $NH_3$ and NO species in line with the hypothesis of an Eley-Rideal mechanism. The present kinetic model assumes; (1) non-activated $NH_3$ adsorption, (2) Temkin-type $NH_3$ coverage dependence of the desorption energy, (3) non-linear dependence of the SCR reaction rate on the $NH_3$ surface coverage. Thus, the surface heterogeneity for adsorption/desorption of $NH_3$ is taken into account in this model. The present study extends the pure chemical kinetic model based on a powdered-phase catalytic system to the chemico-physical one applicable to a realistic monolith reactor.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.43 no.3
• /
• pp.101-111
• /
• 2020

Companies struggle to make their best products with high quality and service at a competitive price in global markets. However, customer needs and requirements keep changing with a variety of situations. Companies that face the changes can not stay the same and make an effort to adapt themselves to new circumstances. They would probably review the overall management system that is currently implementing to improve management efficiency. Among other things, quality might be considered to be a crucial element if they are manufacturing industries to be sustained in global markets. KSA (Korean Standards Association) is a government-affiliated organization under the Ministry of Trade, Infrastructure, and Energy. It is a Korean standards provider for quality and service industry. KSA confers national commendations for organizations, quality circles, artisans, QCEC (Quality Competitive Excellent Company), and the most honorable KNQA (Korean National Quality Award) every year. KSA established KNQA on the basis of Malcom Baldrige National Quality Award, Deming Prize, and European Quality Award. Research on quality awards shows that there are many similarities in the framework. Although KSA summarizes two factors for 13 evaluation indicators in the quality competitive excellent model of QCEC, the categorization is ambiguous to explain them according to earlier studies. We performed a deep analysis of foreign quality awards and background for KNQA and QCEC. We conducted a content analysis of KNQA and QCEC and matched evaluation items that were closely related. We proposed a quality competitiveness model with three factors, Technology, System, and Tools, summarizing 13 evaluation indicators in QCEC. Based on audit data for six years from 2012 to 2017 we carried out a confirmatory factor analysis for the proposed model by examining the model validity and fitness.

• Journal of Advanced Navigation Technology
• /
• v.19 no.2
• /
• pp.161-167
• /
• 2015

This paper proposed system for providing the national competency standards learning module, which has changed and updated from time to time. The provisioning server of the proposed system provides learning module, and the management server carry out fault management, billing, request management, statistics and aggregate, etc, and the target server requests the learning module in the provisioning server through the domain. The proposed system determines provide of the learning module by CORS based on filter, which is to determine whether matches or not with domain of the provisioning server and the target server. The proposed system can be patch and maintenance remotely about NCS based learning module to be new update and removed. Also, the proposed system may provide contents in conjunction with existing educational systems, and may be extended in the future to enable the management for domain of the target server.

• Journal of Navigation and Port Research
• /
• v.32 no.10
• /
• pp.813-819
• /
• 2008

Many shipping companies have suffered about high oil cost and environment regulation as people are concerned about the environment, therefore concentrating on energy using efficiency of the ship. The Skysails Company of Germany developed Skysails System for 4 years, making Shipping Company take interest under such situation. Skysails System uses a large kite in the ship, decreasing fuel expenses. So examination and utility analysis on Skysails System application are a necessity by using weather condition in the Coastal Waters of Korea where feeder network was well-developed. As a result, we could find out the system's efficacy on fuel saving and environment cost saving.