• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.30 no.4
• /
• pp.106-113
• /
• 2002

In spacecraft system, structure subsystem has the mission of supporting all the components safely under various space environmental conditions. The safety of spacecraft structure is finally verified from the coupled load analysis, which is a branch of load analysis which combines the launch vehicle and satellite. This study introduces the optimization algorithm to reduce the weight of spacecraft structure under launch environmental conditions directly. The acceleration responses are obtained by the introduction of coupled load analysis, which lead to check the failure of spacecraft structural members. The results show a 12% saving of structural weight and this saving is mainly driven by the thickness of honeycomb core, which strongly affects the natural frequencies of platforms and panels.

• Journal of the Korean Society of Costume
• /
• v.61 no.5
• /
• pp.1-20
• /
• 2011

As a follow-up of a study on design strategies to improve Korea's Korean coast guarduniforms, this study set out to propose Korean coast guard uniforms of a new concept that would meet the changing needs of the times and match the advanced technology and work environments. Three concepts of classical, nautical and techno chic were identified from the design strategies of the previous study. Using the results from a prototype show and preference survey, the investigator divided items into design, color, material, and detail and reflects demands for each of them. As a result, design was examined in four aspects of identity, acknowledgement, unity, and practicality and focused its improvement factors on design differentiated from other organizations' uniforms including ground police, segmentation of size system, adjustment of the length of upper garment to consider activity, and changes to the lines and silhouette to give out a modern image. As for color, the focus was placed on differentiated colors from other organizations' uniforms including ground police through dark blue and ocean color, change toward colors that reflect environmental characteristics, and unity in colors between the summer and winter uniform. As for material, the focus of improvement was put on elasticity, resistance against contamination, warmth retention, texture, wearing sensation, and functionality by taking into account convenience for field workers on coast guard vessels and branch offices who have much time in contact with ocean environments in order to make the materials high-grade. As for detail, structural details were added to give out a modern image such as changing the detail lines, efficiency of storage space, buttons, sleeve hems, ironing lines, and neck collars by taking into account environmental characteristics. The significance of the study lies in that it proposed a development model for large-scale uniform copy design by establishing copy design that secures functionality and is proper for an organization's social and cultural environment.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.3
• /
• pp.1488-1494
• /
• 2011

In this paper, we propose an algorithm using linear regression model that forecasts the demand of heated water in winter. To supply heated water to apartments, stores and office buildings, Korea District Heating Corp.(KDHC) operates boilers including electric power generators. In order to operate facilities generating heated water economically, it is essential to forecast daily demand of heated water with accuracy. Analysis of history data of Kangnam Branch of KDHC in 2006 and 2007 reveals that heated water supply on previous day as well as temperature are the most important factors to forecast the daily demand of heated water. When calculated by the proposed regression model, mean absolute percentage error for the demand of heated water in winter of the year 2006 through 2009 does not exceed 3.87%.

• Journal of Chest Surgery
• /
• v.11 no.3
• /
• pp.326-332
• /
• 1978

There appears some conduction defects frequently after total correction of Tetralogy of Fallot. Common defect is right bundle branch block due to surgical intervention. We experienced complete A-V block which occured 3 months later after total correction of Tetralogy of Fallot in a 8 year old boy. The patient was completely free of any A-V block after the operation for 3 months, and sudden onset of A-V block with coupled premature ventricular contractions resulted him in shock state during the attack of severe bronchopneumonia for 4 days prior to the second visit. Emergency implantation of Cordis demand type temporary pacemaker was necessary to control the complete heart block with bradyarrhythmia and frequent ventricular fibrillation. Permanent cardiac pacemaker was implanted two weeks later as indicated with Cordis Stanicor lambda demand pacemaker, and the patient was discharged uneventfully on the 8th post implantation day with the heart rate of 72/min. Another 3 months after the implantation, the patient was transported to this hospital as dead on arrival after an accidental fall from a 2 meter height, and all possible cardiopulmonary resuscitation was performed for 60 minutes at the emergency room in vain. Autopsy was done to find out the cause of sudden death and the etiology of complete heart block. Microscopic focal infarctions with scar formation were noted along the course of conduction system in the interventricular septum, which might be the main cause of complete heart block during the attack of severe bronchopneumonia complicated with acute bacterial endocarditis. The tip of the pacemaker wire was slipped from the granulation scar at the apex of the right ventricular cavity, and this might be the direct cause of pacing failure and death.

• Journal of the Korean Institute of Gas
• /
• v.9 no.3 s.28
• /
• pp.1-8
• /
• 2005

We studied on the nondestructive evaluation of the elastic wave signals of locally wall thinned straight pipe. Wavelet transform was applied for the time-frequency analysis of waveforms obtained by fracture wave detector due to the dropping steel ball. The time-frequency analysis provides time variation of each frequency component involved in a waveform, which makes it possible to evaluate the shape of local wall thinning at each frequency. In this study, comparison by wavelet transform of the AE signals and monotonic bending tests without internal pressure are conducted on 1.91 inch diameter full-scale carbon steel pipe specimens. As the results of tests, fracture behaviors could be shown by the characteristic of mechanical strength of locally wall thinned pipes and the waveforms could be evaluated for the integrity insurance of the piping system according to the length and depth range of the deffeted shape pipes in the real field.

• Transactions on Electrical and Electronic Materials
• /
• v.14 no.4
• /
• pp.221-224
• /
• 2013

Effects of ambient temperature on the ac electrical treeing and breakdown behaviors in an epoxy/layered silicate (1 wt%) were carried out in needle-plate electrode geometry. A layered silicate was exfoliated in an epoxy base resin,, using our ac electric field apparatus. To measure the treeing initiation and propagation, and the breakdown rate, constant alternating current (ac) of 10 kV (60 Hz) was applied to the specimen in a needle-plate electrode arrangement, at $30^{\circ}C$, $90^{\circ}C$ or $130^{\circ}C$ of insulating oil bath. At $30^{\circ}C$, the treeing initiation time and the breakdown time in the epoxy/layered silicate (1 wt%) system were 1.4 times higher than those of the neat epoxy resin. At $90^{\circ}C$ (lower than Tg), electrical treeing was initiated in 55 min, and propagated until 1,390 min at the speed of $0.35{\times}10^{-3}mm/min$, which was 4.4 times higher than that at $30^{\circ}C$; however, there was almost no further treeing propagation after 1,390 min. At $130^{\circ}C$ (higher than Tg), electrical treeing was initiated in 44 min, and propagated until 2,000 min at the speed of $0.96{\times}10^{-3}mm/min$. Typical branch type electrical treeing was obtained from the neat epoxy and epoxy/layered silicate at $30^{\circ}C$, while bush type treeing was observed out from the needle tip at $90^{\circ}C$ and $130^{\circ}C$.

• International Journal of Highway Engineering
• /
• v.18 no.5
• /
• pp.105-115
• /
• 2016

PURPOSES : This study was initiated to analyze the characteristics of bus traffic accidents, by bus types, using the decision tree in order to establish customized safety alternatives by bus types, including the intra-city bus, rural area bus, and inter-city bus. METHODS : In this study, the major elements involved in bus traffic accidents were identified using decision trees and CHAID algorithm. The decision tree was used to identify the characteristics of major elements influencing bus traffic accidents. In addition, the CHAID algorithm was applied to branch the decision trees. RESULTS : The number of casualties and severe injuries are high in bus accidents involving pedestrians, bicycles, motorcycles, etc. In the case of light injury caused by bus accidents, different results are found. In the case of intra-city bus accidents, the probability of light injury is of 77.2% when boarding a non-owned car and breaching of duty to drive safely are involved. In the case of rural area bus accidents, the elements showing the highest probability of light injury are boarding an owned car, vehicle-to-vehicle accidents, and breaching of duty to drive safely. In the case of intra-city bus accidents, boarding owned car, streets, and vehicle-to-vehicle accidents work as the critical elements. CONCLUSIONS : In this study, the bus accident data were categorized by bus types, and then the influential elements were identified using decision trees. As a result, the characteristics of bus accidents were found to be different depending on bus types. The findings in this study are expected to be utilized in establishing effective alternatives to reduce bus accidents.

• Journal of Korean Society of Transportation
• /
• v.32 no.2
• /
• pp.119-129
• /
• 2014

This study aims to evaluate the accident reduction effects of 'Section Speed Enforcement System' (SSES) operation in freeways. In pursuing the above, this study collects the accident data for 5 years (2 years before operation and 3 years after operation) at all 9 sections where SSESs are operated, and evaluates annually the effects before and after operation using the comparison group method (C.G. Method). The measures of effectiveness are total accidents (TAs), fatal and serious accidents (FSAs), total injuries (TIs) and fatal and serious injuries (FSIs). The main results are as follows. First, TAs and TIs are reduced to 41.7 and 17.1%, respectively. Second, FSAs and FSIs are reduced to 41.7 and 32.2%, respectively. Therefore, SSES has more effectiveness at fatal and serious accident. Third, the accident reduction effect has been increasing, and particularly the effect of 'after three years' is evaluated to be notable.

• Toxicological Research
• /
• v.25 no.4
• /
• pp.243-251
• /
• 2009

Present study was conducted to evaluate the anti oxidative activity of the Agrimonia pilosa-Ledeb leaves on non-lipid oxidative damage. The antioxidative activity of methanolic (MeOH) extract of the Agrimonia pilosa-Ledeb leaves on non-lipid oxidation, including liposome oxidation, deoxyribose oxidation, protein oxidation, chelating activity against metal ions, scavenging activity against hydrogen peroxide, scavenging activity against hydroxyl radical and 2'-deoxyguanosine (2'-dG) oxidation were investigated. The MeOH extract of the Agrimonia pilosa-Ledeb leaves exhibited high anti oxidative activity in the liposome model system. Deoxyribose peroxidation was inhibited by the MeOH extract of the Agrimonia pilosa-Ledeb leaves and MeOH extract of the Agrimonia pilosa-Ledeb leaves provided remarkable protection against damage to deoxyribose. Protective effect of MeOH extracts of the Agrimonia pilosa-Ledeb leaves on protein damage was observed at $600{\mu}g$ level (82.05%). The MeOH extracts of the Agrimonia pilosa-Ledeb leaves at $300{\mu}g$ revealed metal binding ability (32.64%) for hydrogen peroxide. Furthermore, the oxidation of 2'-deoxyguanosine (2'-dG) to 8-hydroxy-2-deoxyguanosine (8-OH-2'dG) was inhibited by MeOH extracts of the Agrimonia pilosa-Ledeb leaves and scavenging activity for hydroxyl radical exhibited a remarkable effect. From the results in the present study on biological model systems, we concluded that MeOH extract of the Agrimonia pilosa-Ledeb leaves was effective in the protection of non-lipids against various oxidative model systems.

• Journal of Microbiology and Biotechnology
• /
• v.19 no.10
• /
• pp.1153-1160
• /
• 2009

Lactosucrose ($4^G-\beta$-D-galactosylsucrose) is an oligosaccharide consisting of galactose, glucose, and fructose. In this study, we prepared lactosucrose from lactose and sucrose using a levansucrase derived from Zymomonas mobilis. Optimum conditions for lactosucrose formation were $23^{\circ}C$, pH 7.0, 18.0% (w/v) lactose monohydrate, and 18% (w/v) sucrose as substrates, and 1 unit of enzyme/ml of reaction mixture. Under these conditions, the lactosucrose conversion efficiency was 28.5%. The product was purified and confirmed to be O-$\beta$-D-galactopyranosyl-($1{\rightarrow}4$)-O-$\beta$)-D-glucopyranosyl-($1{\rightarrow}2$)-$\beta$-D-fructofuranoside, or lactosucrose. A mixed-enzyme system containing a levansucrase and a glucose oxidase was applied in order to increase the efficiency of lactose and sucrose conversion to lactosucrose, which rose to 43.2% as a result.