• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.5 s.120
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• pp.496-502
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• 2007

In this paper, a slotted waveguide feeder for the electric field uniformity in multi-mode cavity is designed and fabricated. In case of the conventional feeder, a mode stirrer or a turntable is used for improving electric field uniformity in the multi-mode cavity. The proposed feeder has four slots, which have uniform radiation characteristic, on broad wall and shorted terminations at both ends. The electric field uniformity is simulated by CST's MWS(Microwave Studio) for the conventional and proposed feeders, respectively. The fabricated feeder shows the return loss of less than -20 dB at 2.45 GHz. To verify the validity of our proposal, the temperature distribution of the water samples in the multi- mode cavity is observed after a few minutes' heating. The proposed feeder is confirmed to have much better field uniformity in the multi-mode cavity than the conventional feeder.

• Korean Journal of Environmental Biology
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• v.32 no.1
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• pp.49-57
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• 2014

Orb-web spiders can be considered as an effective bio-indicative animal to monitor the ecological air pollution of certain habitat since they have limited shifting ability during their life spans. In this study we revealed the fine structural characteristics of booklung in the orb-web spider Nephila clavata, and its bio-indicative significance in the monitoring environmental asbestos exposure. The high resolution scanning electron microscopy results suggest that the cuticular spikes near the atrium could be act as an effective filtering structure for dust materials. Furthermore, inner cuticular spikes which protruded across the air sacs, have the functions not only sustaining appropriate respiratory volume of each air sac but also help to enhance respiratory capacity by maximizing the gross surface area for gas exchange. Interestingly, in spite of short exposure, the asbestose fibrils were effectively captured on the surface of the atrial cuticular spikes. Furthermore, histologic damages were observed due to penetration of asbestos fibrils through air sacs and fixed on the hemolymph space. In addition, although accumulated mass of hemocytes were observed near the fibrils, there were no asbestos bodies or coagulated hemocytes were found on the surface of the fibrils, This could be mainly due to the short exposure period towards asbestos. Briefly, these results indicate the spider's booklung could be valuable tool in the detection ecological air pollutants.

• Restorative Dentistry and Endodontics
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• v.17 no.1
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• pp.22-35
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• 1992

The aim of this study was to investigate the effect of herbal organic extracts on the pain response provoked by noxious stimuli on dental nerve and the peripheral nerve conduction. Cats (2-2.5Kg regardless of sex) that were chosen as experimental animals were classified into control group, Asiasari radix application group and Zingiberis rhizoma application group. They were anesthetized with ${\alpha}$-chloralose, then anterior belly of digastric muscle of both sides were exposed and wire electrodes were inserted for recording of Electromyogram (EMG). Cavities were prepared on canines until pulp of the teeth were exposed. And after the drugs solubilized for 2% and 4% concentration (W/V) in vehicle were applied, their effects were compared through the recording of EMG immediately after drug application, 30 minutes, 60 minutes, 120 minutes and 5 days after, respectively. And after both inferior alveolar nerves were exposed, 4% organic extracts of Zingiberis rhizoma and Asiasari radix were applied for 30 minutes then the change of jaw opening reflex provoked by noxious stimuli on pulpal nerves were observed immediately after washing out, at 30, 60 and 90 minutes after drug had been washed out. After saphenous nerve of both sides were exposed, one side of nerve was used for vehicle application and the other side was used for drug application for 30 minutes. Then conduction of action potential of A-${\delta}$ and C-fiders of saphenous nerves, which have changed with time, was recorded. With analysis of these records, the following results were obtained: 1. Organic extract of Zingiberis rhizoma (2% or 4% concentration) greatly suppressed EMG of digastric muscle provoked by noxious stimuli on pulpal nerve at five days after application, the suppressive: effect was greater than that of organic extract of Asiasari radix. 2. Organic extract of Asiasari radix (2% or 4% concentration) suppressed jaw opening reflex provoked by noxious stimuli on pulpal nerve, at 5 days after drug application. 3. Organic extract of Zingiberis rhizoma and Asiasari radix (immediately after 30 minutes application) suppressed neural conduction of A-${\delta}$ and C-fibers, the suppressive effect was greater on A-${\delta}$ fibers than on C-fibers. 4. Jaw opening reflex provoked by noxious stimuli on pulpal nerve in inferior alveolar nerve was greatly suppressed 30 minutes after drug application, this effect was greater by Zingiberis rhizoma than by Asiasari radix.

• Journal of the Korea Institute of Building Construction
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• v.11 no.5
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• pp.435-441
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• 2011

The life cycle assessment on greenhouse gas emission of reinforced concrete buildings shows that more than 70 percent of greenhouse gas that is discharged by a building is discharged in the building maintenance stage, including cooling and heating. To reduce the greenhouse gas emission, maintenance planning to minimize the energy consumption is necessary in the design stage. In this paper, two heat storage rooms are tested to save the air cooling energy of the buildings. The specimens are essentially identical, except that chamber A contained paraffin sheets as the finishing material, while the other, chamber B, served as a control. The test results show that chamber A with the paraffin sheets exhibited less temperature change than chamber B without the sheets when temperature was increased outside of the specimens. The heating energy was probably consumed in the phase change of the paraffin sheets, which can be useful for reducing energy consumption related to air cooling during the summer.

• International Journal of Highway Engineering
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• v.11 no.4
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• pp.143-152
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• 2009

The purpose of this study is to evaluate the freezing index and frost penetration depth. The freezing index and frost penetration depth were analyzed using air temperature and temperature profile of pavement system in Korea LTPP-SPS(Long Term Pavement Performance-Specific Pavement Study) site. The predicted frost penetration depth were then compared with the measured one from the LTPP sites. And the trend of annual freezing index was analyzed using the temperature data of meteorological stations located in the vicinity of Korea LTPP-SPS site. The result showed that the freezing index was rapidly decreased since 1987, and it was known that the use of freezing index determined from the past 30 years temperature data could cause the over estimates in the pavement thickness design. The temperature profile measured at 3 sections of LTPP-SPS sites showed that the temperature of subbase layer was above $0^{\circ}C$, even though anti-frost layers were found in these sections. Comparing the measured and calculated frost depth, the frost depth calculated from the subgrade frost penetration permissible method showed a similar trend with the measured frost depth.

• Korean Journal of Optics and Photonics
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• v.9 no.5
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• pp.277-281
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• 1998

One dimensional inhomogeneous aperture modulation effects on the MTF of optical system was investigated. The lens under test was a doublet made in Korea. It has 10 mm effective diameter, 87.8 mm effective focal length. The ray-fans and spot diagrams were calculated and presented on the picture for on-axis and off-axis (field of view, $1^{\circ}$ and $2^{\circ}$). Aperture modulation was carried out by positioning a aperture modulator close contacter with the lens under test. We bought two modulators from Edmud Company in U.S.A. One was linear type and the other was stepped type. The MTFs were measured on the best of focus for each modulated aperture where the MTF has the highest value for 60 line/mm and were compared with one another. For on-axis, the MTFs of some modulated apertures had higher values than the MTF of unmodulated aperture in the high frequency region. In the case of off-axis, at the field of view $1^{\circ}$, the MTF values of some modulated aperture are improved prominently and some other one are disimproved. At the field of view $2^{\circ}$ most of the MTFs of modulated apertures had lower values than the MTF of unmodulated aperture except the MTFs of linear and inverse linear type aperture in the high frequency area. But the values of MTFs in high frequency region were too low for actual use.

• Parasites, Hosts and Diseases
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• v.25 no.1
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• pp.51-58
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• 1987

Tegumental ultrastructures of Echinochasmus japonicus were observed by scanning electron microscopy. The worms were recovered from albino rats which were experimentally infected with the metacercariae obtained from Pseudorasbora parva. Followings are summarized findings. 1. The worms were minute and plumpy gourdshaped with attenuated anterior and round posterior end. The tegument of whole body was wrinkled transversely and covered with cobblestone-like cytoplasmic processes. 2. Head crown was armed with 24 collar spines which were embedded in cytoplasmic pockets. The spines were arranged in a row with an interruption at dorsomedian line, however, the 2nd and the 4th spines were outstretched more than others. Oral and ventral suckers were muscular with numerous type II sensory papillae, and genital pore opened between the two suckers. 3. Tegumental spines were spade-shaped with broad base and pointed tip. They were compact in ventra-lateral tegument or dorsal surface of anterior body. They were not found between the two suckers and dorsal surface of posterior body. 4. Two types of sensory papillae, uni-ciliated (Type I) and roundly swollen sensory papillae (Type II), were observed. The type I papillae were chiefly distributed on ventral surface of tegument and type II were on the lips of suckers. Arrangement of collar spines, shape and distribution of tegumental spines or sensory papillae are regarded as characteristic features of E. japonicus.

• Fire Science and Engineering
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• v.18 no.2
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• pp.20-26
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• 2004

The purpose of this study is to investigate the transition mechanism and prevention mechanism of gas explosion to fire. Transition phenomena of explosion to fire of LPG in the explosion vessel of its size of TEX>$100 cm {\times} 60 cm {\times} 45 cm$ was visualized using the high speed video camera and the mechanism was analysed from the videograph. Newspaper size of $30cm {\times} 20cm$ was used for combustible sample in this experiments and LPG-air mixture was ignited by 10 ㎸ electric spark. Experimental parameter was gas concentration, size of vent area and position of combustible solid. Size of vent area were varied as $10cm {\times} 9cm, 13cm {\times} 10cm, 27cm {\times} 20cm, 40cm {\times} 27cm$, and the position of combustible was varied in 4 point. Carbon dioxide was used to study the prevention mechanism of explosion to fire transition of LPG. Based on this experiment we can find that transition possibility of explosion to fire on solid combustible from explosion is depends on concentration of LPG-air mixture and the exposure time of solid combustibles in high temperature atmosphere of flame and burnt gas. And cooling or inerting of the atmosphere after explosion can be prevent the transition of explosion to fire on solid combustibles from gas explosion.

• Fire Science and Engineering
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• v.26 no.4
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• pp.48-54
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• 2012

In order to study on the evacuation risk when connate fires caused by vertical fire spread of the exterior occurs, the egress simulations based on the relevant scenarios has carried out. As a result of it, ASET (permitted evacuation time) was reached in between 550 to 650 seconds in entire floors after vertical smoke spread from fire of combustible exteriors. In particular, ASET was 358 seconds in the first floor, 490 seconds in the six floor and 473 seconds in the tenth floor. In addition, five floors of all levels, the 1st floor, the 6th floor and the 28th floor ~30th floor, show RSET (minimum evacuation time) which is bigger than ASET as evacuation risk. This result presents occupants in high rise buildings with more than 15 floors might not be able to egress of them using staircases due to huge population attempting to evacuate simultaneously. Particularly, 699 people in the upper levels by smoke from the first floor are having difficulty escaping this building since ASET on the first floor adjacent to the ignition point was 358 seconds which is relatively reached fast. Considering a prevention method of the fire and smoke spread, architects have to use non-combustible exterior in the building's facade to be required as an active fire protection system.

• Fire Science and Engineering
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• v.32 no.3
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• pp.51-59
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• 2018

Although a fire curtain plays an important role in preventing smoke from spreading to the auditorium in a theater fire, there has been insufficient research on fire curtains. In this study, to check the accuracy of numerical simulation, for previous experiments using a reduced scale model, a numerical simulation was carried out, and the results were compared with previous experimental data. The fire curtain effect was then predicted numerically. A Fire Dynamics Simulator (FDS) was used, and the natural exhaust vent sizes were set to ~10%, ~5%, and ~1% of the stage floor area. The smoke movement was visualized, and the mass flow rates and temperatures were measured and analyzed. In addition, the law of similarity was used to examine the influence of a fire curtain in a real scale theater fire. Without the fire curtain, the present numerical simulation results were in agreement with the previous experimental data within reasonable accuracy. Meanwhile, the fire curtain affects the mass flow rates through the natural exhaust vent and proscenium opening, as well as the start time of soot outflow to the auditorium. Overall, the present results can be used to develop a fire curtain system.