• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.14 no.2
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• pp.57-62
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• 1978

When fisherman use the boat seine net to catch anchovy, a large noise (drum can, small drum and small gong) is used to scare the anchovy school along the wing nets, and into the bag net were they are caught. We want to know how much of an effect these s:mnds have on forceing the anchovy school towards the bag net. The underwater sounds of ancho\'y, drum can, small drum and small gong were analyzed in the labroatory. The behavioral responeses to the playback sounds of anchovy feeding and sounds of artificial instruments were also investigated. The feeding and artificial sounds of the samples were recorded by a tape recorder through a hydrophone in an anechoic aquarium. The sound intensity level was measured by means of a sound level meter in an anechoic chamber. The frequency and intensity of various sounds were analyzed with an analyzing system consisting of a ~-octave filter set, a high speed level recorder, an amplifier and an oscilloscope. The most successful recording was edited into a 9 to 10 second sound track and was repeated in a sequence of 9 to 10 second intervals. The sequence was then reproduced into an anechoic aquarium through the underwater speaker. The results of investigation are as follows; 1. The frequency of the feeding sound was 63~80Hz, and the pressure level produced was less than 32db. 2. The frequencies of the artificial sounds were 315~ 1,OOOHz, and the pressure levels were 88~95 db in the air. 3. When a hydrophone was placed 70cm below the surface with artificial sounds (drum can, small drum and small gong) produced 1 meter above the surface, the pressure level decreased about 30db. 4. The feeding sound was ineffective in attracting the anchovy, because of interference from ambient noise. 5. The artificial sounds had such a small effect on the anchovy's that they could not be used in ocean fisheries.

• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.163-172
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• 2003

As concrete structures are getting larger, higher, longer, and specialized, it is more required to develop steel fiber concrete and apply to the real world. In this research, it is aimed to have fatigue strength examined, varying the steel fiber content by 0%, 0.75%, 1.00%, 1.25%, by experimental study of Two-spans Beam with Steel Fibrous with repeated loads. The ultimate load and the initial load of flexural cracking were measured by static test. In addition, the load versus strain relation, load versus strain relation, load versus deflection relation, crack pattern and fracture mode by increasing weight was observed. On the other hand, the crack propagation and the modes of fracture according to cycle number and the relation of cycle loading to deflection relation and strain relation was observed by fatigue test. As the result of fatigue test, Two-spans Beam without Steel Fibrous was failed at 60~70% of the static ultimate strength and it could be concluded that fatigue strength to two million cycle was around 67.2% by S-N curve. On the other hand, that with Steel Fibrous was failed at 65~85% of the static ultimate strength and it could be concluded fatigue strength to two million cycle around 71.7%.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.5
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• pp.38-48
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• 2010

Adverse weather (e.g. strong winds, snow and ice) will probably appear as a more serious and frequent threat to road traffic than in clear climate. Another consequence of climate change with a natural disastrous on road traffic is respond to traffic accident more the large and high-rise bridge zone, tunnel zone, inclined plane zone and de-icing zone than any other zone, which in turn calls for continuous adaption of monitoring procedures. Accident mitigating measures against this accident category may consist of intense winter maintenance, the use of road weather information systems for data collection and early warnings, road surveillance and traffic control. While hazard from reduced road friction due to snow and ice may be eliminated by snow removal and de-icing measures, the effect of strong winds on road traffic are not easily avoided. The purpose of the study described here, was to design of amber information the relationship between traffic safety, weather, user information on road weather and driving conditions in local-scale Geographic. The most applications are the optimization of the amber information definition, improvements to road surveillance, road weather monitoring and improved accuracy of user information delivery. Also, statistics on wind gust, surface condition, vehicle category and other relevant parameters for wind induced accidents provide basis for traffic control, early warning policies and driver education for improved road safety at bad weather-exposed locations.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.5
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• pp.249-254
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• 2014

In this paper, minimizing of a parabolic edge planar monopole antenna by scaling method is presented. With the aid of a matching step and discontinuous CPW, the antenna easily adjusts the impedance matching. We used an FR4 dielectric substrate with a dielectric constant of 4.4. The dimensions of the antenna are $26mm{\times}31mm{\times}1.6mm$. A return loss value of more than 10dB was found in the 2.37GHz to 10.52GHz (8.15GHz) range of the antenna fed by the discontinuous CPW. The radiation pattern is about the same as that of the dipole antenna at all frequencies. Configuration elements of the antenna except feed part were reduced into the same rate. So, the size of the antenna was decreased and a broadband property was maintained. Therefore, the self-complementary characteristic of the antenna was confirmed. While satisfying the UWB band, having the smallest size in the antenna miniaturized by scaling;when scale was 0.6. The dimensions of the antenna are $15.6mm{\times}18.6mm{\times}1.6mm$. The return loss was more than 10 dB of the measured result in the range of 3.07GHz to 12.59GHz (9.52GHz).

• Journal of the Korean GEO-environmental Society
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• v.15 no.9
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• pp.19-28
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• 2014

Recently, the proportion of long tunnel has increased for efficient use of land due to limited land area, driving convenience and high speed. RMR and Q-System of empirical methods has been mainly used for tunnel support design in domestic. Although shotcrete is the key to NATM tunnel, the related studies are insufficient. So, steel fiber reinforced shotcrete is applied to II~V grade rocks on domestic and foreign applications. And same amount of shotcrete is equally applied to tunnel roof and wall regardless of the applied rock load. Shotcrete is applied excessively rather than the original proposed value of RMR and Q-System. Thus, this study is to reevaluate the application part of plain shotcrete and steel fiber reinforced shotcrete of tunnel in Daebo granite, and to propose the reasonable application method of steel fiber reinforced shotcrete. Field test and numerical back analysis using measurements were performed to verify stability. According to results, if RMR values are the upper class in the III grade, it can be designed in accordance with upper grade. In addition, if rock condition is good as a mountain tunnel in Daebo granite, it can be applied for plain shotcrete to III grade rocks because there is also no stability problems. And although steel fiber reinforced shotcrete is applied only crown of the tunnel in IV grade rocks, it is possible to secure stability for falling rock by key-block.

• Information Systems Review
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• v.8 no.2
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• pp.1-15
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• 2006

Schedule Management for outside duty personnels and their groups is fairly difficult since they spend most of their time on working outside individually rather than inside office. Everytime when schedule change for personnels or their groups is needed, it is necessary to call every personnel in order to notify the schedule change. It would be much easier to handle the schedule management problem if outside duty personnels are able to download schedule of their groups(and, upload their schedule) using their mobile communication devices such as PDAs. In this paper, using a data synchronization protocol in mobile communication environments, a schedule management system for outside duty personnels is designed and implemented. Data synchronization in mobile communication environments is a process of maintaining consistency between data stored in mobile devices and data stored in a (central) server at office. In other words, using SyncML data synchronization protocol proposed by OMA(Open Mobile Alliance) as an open standard for data synchronization in mobile communication environments, a schedule management system for outside duty personnels which allows them to check schedule of their groups and to notify their schedule to their groups at anytime anyplace is designed and implemented.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.2
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• pp.153-166
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• 2015

Long subsea tunnel to be built below the seabed, as compared to the general railway tunnel, is subject to many restrictions in terms of spatial limitation when vertical or inclined shafts are built for the purpose of ventilation and fire safety. So, the construction of some artificial island is required to provide ventilation. But, because of construction difficulty and cost increase, it is necessary to minimize the artificial island construction. The longer ventilation distance is, the more fresh air requirement is needed. When supply airflow becomes excessive, duct size is restricted by the limitations of structure clearance and fan pressure and power increase exponentially. Therefore, in order to build a long subsea tunnel, it is necessary to overcome these practical problems and to develop technical solution that can keep the comfortable condition of tunnel environment during construction. In this study, as on ventilation method development suitable for long subsea tunnel, through comparison of temporary ventilation capacity calculation methods during construction phase, domestic and abroad, the application of Swiss SIA 196 code is found suitable for long subsea tunnel. And, through experiment on leakage of the duct connector, we confirmed that the leakage ratio per 100 m of domestic duct connection type is between 1.5~3.0%. Based on S-class duct of SIA 196 code, ventilation distance is 10.2 km, So, ventilation distance can be longer if duct connection method is improved. So, we confirmed that the improvement of leakage ratio is key issue in the construction-phase ventilation of long subsea tunnel.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.5
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• pp.787-807
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• 2018

When conducting the underground safety impact assessment under the special law in Korea, it is essential to investigate the occurrence of underground cavities. When underground cavities were discovered, the underground safety was assessed through numerical analysis. The previous study has suggested the stability evaluation based on the factor of safety by changing the 2D shape of the small underground cavity. In this study, the effects of small underground cavities considering 3D shapes were examined using a continuum analysis program and compared with the 2D results presented in previous study. If the 3-Dimensional shape of the underground cavity is found close to the sphere type, it would be reasonable to evaluate the factor of safety by the shear strength reduction method regardless of the size and position of the cavity. If a high-aspect ratio underground cavity with a depth of 2 m or more from the ground surface and an aspect ratio (a/b) of 2.0 or more is in the vertical direction, not only the factor of safety but the failure mode shape should be cautions in the stability evaluation using the shear strength reduction method. The results of this study are expected to be basic data on underground safety impact assessment.

• Journal of Wetlands Research
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• v.7 no.4
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• pp.97-107
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• 2005

As the distributed model is developed and widely used, the accuracy of a rainfall measurement and more dense rainfall observation network are required for the reflection of various spatial properties. However, in reality, it is not easy to get the accurate data from dense network. Generally, we could not have the proper rainfall gages in space and even we have proper network for rainfall gages it is not easy to reflect the variations of rainfall in space and time. Often, we do also have missing rainfall data at the rainfall gage stations due to various reasons. We estimate the distribution of mean areal rainfall data from the point rainfalls. So, in the aspect of continuous rainfall property in time, we should fill the missing rainfall data then we can represent the spatial distribution of rainfall data. This study uses the Fuzzy-Genetic algorithm as a interpolation method for filling the missing rainfall data. We compare the Fuzzy-Genetic algorithm with arithmetic average method, inverse distance method, normal ratio method, and ratio of distance and elevation method which are widely used previously. As the results, the previous methods showed the accuracy of 70 to 80 % but the Fuzzy-Genetic algorithm showed that of 90 %. Especially, from the sensitivity analysis, we suggest the values of power in the equation for filling the missing data according to the distance and elevation.

• The KIPS Transactions:PartC
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• v.11C no.1
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• pp.141-148
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• 2004

Recently, the demand of broadband communications such as high-speed internet, HDTV, 3D-HDTV and ATM backbone network has been increased drastically. For transmitting the broad-bandwidth data using wireless network, it is needed to use ka-band frequency. However, the use of this ka-band frequency is seriously affected to the received data performance by rain fading and atmospheric propagation loss at the Ka-band satellite communication link. So, we need adaptive MODEM to endure the degraded performance by channel environment. In this paper, we will present the structure and design of the 155Mbps adaptive Modem adaptively compensated against channel environment. In order to compensate the rain attenuation over the ka-band wireless channel link, the adaptive coding schemes with variable coding rates and the multiple modulation schemes such as trellis coded 8-PSK, QPSK, and BPSK are adopted. And the blind demodulation scheme is proposed to demodulate without Information of modulation mode at the multi-mode demodulator, and the fast phase ambiguity resolving scheme is proposed. The design and simulation results of adaptive Modem by SPW model are provided. This 155Mbps adaptive MODEM was designed and implemented by single ASIC chip with the $0.25\mu{m}$ CMOS standard cell technology and 950 thousand gates.