• 한국해양학회지
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• v.6 no.2
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• pp.92-98
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• 1971

Storm surges caused by typhoon Billie, 28 Aug. ∼ 2 Sep. 1970, on the west and south coasts of Korea are studied with the tidal data. Tracks and frequencies of the typhoons which affected the Korean peninsula and the yearly maximum tidal deviation at tide stations for the past twelve years are also reviewed. It is assumed that most of the typhoons affecting the Korea peninsula cause variations of sea level along almost all of the coast of Korea. Maximum storm surges at each tide station on the south coast appeared to be caused by typhoons during the summer, and by the north westerly monsoon and extraordinary cyclones on the west coast during spring and winter. In the coastal waters of the west coast where depths are shallower and the bottom configuration is flat, sea level variation is mostly caused by atmospheric pressure and wind effect. When a typhoon travels as in case of typhoon Billie, sea level ascends generally on the south coast and it descends on the west coast before the typhoon approaches near to the coasts. Considering the large tidal range on the western and southern coasts, it is assumed that the extraordinary destructive surges can be occurred when the tide is high water. Reviewing the monthly mean sea level variations on the each coast, hazards to be caused by storm surges can more fluently occur during the summer.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.1
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• pp.56-64
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• 2016

This study analyzed characteristics of officers' watch-keeping during fishing operation at the fisheries training ship KAYA (GT: 1,737 tons, Pukyong National University). It observed fishing works of three officers in wheel house of KAYA. The observations were carried out at the fishing ground 45 miles away from east of Jeju from 7 to 8 January 2010. The works and movements of the officers were recorded with three common video cameras and a 4-channel MPEG-4 Triplex DVR. Recorded data of the working circulation was analyzed by using the post-processing method. As a result of the traffic lines, the average (${\pm}S.D$) of working hour (min) and moving frequency (times), distance (m) and speed (m/min) during setting the net was 11.8 (0.9), 43.7 (8.1), 133.9 (35.8) and 10.5 (0.6), respectively. During trawling the net, it was 100, 241 (39.8), 615.7 (194.6) and 5.2 (1.6), respectively. During hauling the net, it was 17.6 (1.4), 41.0 (7.2), 196.9 (37.6) and 10.7 (0.8), respectively. In addition, it has a different tendency of the instrument usage frequency by the fishing works. During setting, the usage priority was CCTV, ECDIS, RPM and pitch controller, net monitor, GPS plotter, chart room, X-band radar, fish finder and public addressor. During trawling, it was CCTV, ECDIS, fish finder, X-band radar, net monitor, chart room, GPS plotter, RPM and pitch controller, auto pilot and steering, interphone, wind speed and direction indicator, No.1. VHF, navigation light control panel and public addressor. During hauling, it was CCTV, RPM and pitch controller, GPS plotter, public addressor, chart room, net monitor, X-band radar, auto pilot and steering and fish finder.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.30.2-30.2
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• 2010

Numerous operational anomalies and satellite failures have been reported since the beginnings of the "space age". Space weather effects on modern spacecraft systems have been emphasized more and more as increasing their complexity and capability. Energetic particles potentially can destroy and degrade electronic components in satellites. We analyzed the geostationary (GEO) satellite anomalies during 1997-2009 to search possible influences of space weather on the satellite anomalies like power problem, control processor problem, attitude control problem, etc. For this we use particle data from GOES and LANL satellites to investigate space weather effects on the GEO satellites' anomalies depending on Kp index, local time, seasonal variation, and high-energy electron contribution. As results, we obtained following results: (1) there is a good correlation between geomagnetic index(Kp) and anomaly occurrences of the GEO satellite; (2) especially during the solar minimum, occurrence of the satellite anomalies are related to electron flux increase due to high speed solar wind; (3) satellite anomalies occurred more preferentially in the midnight and dawn sector than noon and dusk sector; (4) and the anomalies occurred twice more in Spring and Fall than Summer and Winter; (5) the electron with the lowest energy channel (50-75keV) has the highest correlation (cc=0.758) with the anomalies. High association between the anomalies and the low energy electrons could be understand by the facts that electron fluxes in the spring and fall are stronger than those in the summer and winter, and low-energy electron flux is more concentrated in the dawn sector where the GEO satellite anomalies occurred more frequently than high-energy electron flux. While we could not identify what cause such local time dependences, our results shows that low-energy electrons (~100keV) could be main source of the satellite anomaly, which should be carefully taken into account of operating satellites.

• Journal of Environmental Health Sciences
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• v.7 no.2
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• pp.89-95
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• 1981

A Continuous monitoring of Air Pollution in city of Seoul was carried out from January 1 to December 31 of 1979 at two selected sites, Kwanghwamun observatory and Kwanag observatory. The measured data were averaged on monthly basis. The maximun value of oxidant pollution was observed in July, and the minimum in February. It is the purpose of this study to determine the effect of hydrocarbon, nitrogenoxide, wind velocity and ambient temprature on the observed values of oxidant pollution for the above two months. The results of the study may be summarized as follows. 1) The oxidant concentration in February was higher than in July by about 2 times in both downtown area and the suburbia. The concentration in downtown area was $25.75\pm 4.75ppb$, and that in suburbia was $29.83\pm 5.16ppb$. As for the oxidant concentration in July, it was observed that the suburban area ($26.464\pm 7.59ppb$) had about 2.8 times higher value than the downtown area ($9.284\pm 1.55ppb$). 2) The peak oxidant concentration of suburban area during the daytime is occured from noon to 5:00 P.M.. These patterns are similar to the classical patterns, but the peak Oxidant Concentration of downtown area in February was occured at 9:00A.M. 3) The overall level of nitrogen oxide pollution was much higher in downtown area than in suburban area. Two peaks of nitrogen oxide concentration occured at 10 A.M. and 12 midnight in downtown area. This observation agrees with the report that the air pollution is higher in the area where the pollution sources are concentrated. 4) The multiple correlation analysis for the oxidant and the other variables measured in February in downtown area showed close correlation with nitrogen oxide and ambient temprature. The multiple correlation coefficient of oxidant with nitrogen oxide was 0.872, and that with nitrogen oxide and temperature simultaneously was 0.903. The multiple correlation equation used for this study may be expressed as follows:

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.10 no.S_4
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• pp.197-206
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• 2001

The long-range transport mechanisms of Asian dust were analyzed based on the synoptic weather system and numerical simulation by using NCEP/NCAR reanalysis and TOMS data during the periods of 1996-2001. We classified the whole weather types of eastern Asia during spring and created the representative weather types during the yellow sand events using cluster analysis and weather charts for the last 6 years(1996~2001). These long-range transport mechanisms were related to various pressure patterns including high and low, trough and ridge, and upper-level fronts. Case studies of the yellow sand events have performed by the simulation of MM5 with meteorological elements such as the horizontal wind of u and v component, potential temperature, potential vorticity, and vertical circulation during the episodic days(2~8 March 2001). In addition, the origin of the long-range transport was examined with the estimation of backward trajectory using HYSPLIT4 Model. In this paper, we concluded that three weather types at 1000 hPa, 850 hPa, 500 hPa, and 300 hPa levels were classified respectively. The dominant features were the extending continental outflow from China to Korea at 1000 hPa and 850 hPa levels, the deep trough passage and cold advection at 500 hPa and 300 hPa levels during the yellow sand events. And also, we confirmed the existence of pola $r_tropical jets in the upper-level, the behavior of potential vorticity over Korea, the estimation of potential vorticity through vertical cross section, and the transport of yellow sand through backward trajectories.es.

• Journal of Environmental Science International
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• v.17 no.8
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• pp.841-856
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• 2008

This research outlines a new method for evaluation of shellfish production in Gamak Bay based on the concept of EMERGY. Better understanding of those environmental factors influencing oyster production and the management of oyster stocks requires the ability to assess the real value of environmental sources such as solar energy, river, tide, wave, wind, and other physical mechanisms. In this research, EMERGY flows from environment sources were 76% for shellfish aquaculture in Gamak Bay. EMERGY yield ratio, Environmental Loading Ratio, and Sustainability Index were 4.26, 0.31 and 13.89, respectively. Using the Emergy evaluation data, the predicted maximum shellfish aquaculture production in Gamak Bay and the FDA (Food and Drug Administration, U.S.) designated area in Gamak Bay were 10,845 ton/y and 7,548 ton/yr, respectively. Since the predicted shellfish production was approximately 1.3 times more than produced shellfish production in 2005, the carrying capacity of Gamak Bay is estimated to be 1.3 times more than the present oyster production.

• Journal of the Korean earth science society
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• v.30 no.5
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• pp.660-670
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• 2009

This study examines the changes of an interdecadal circulation over the Asian continent to find cause of the surface warming in Siberia from 1958 to 2004. According to our study, there is a coherency between a long-term change of sea surface temperature in the Indian Ocean and the rapid increase of air temperature in Siberia since 1976/1977. In this study, we suggest that mean wind field changes induced by the positive sea surface temperature anomalies of the Indian Ocean since 1976/1977 are caused of inter-decadal variations in a large-scale circulation over the Asian continent. It also indicates that the inter-decadal circulation over the Asian continent is accompanied with warm southerly winds near surface, which have significantly contributed to the increase of surface temperature in Siberia. These southerly winds have been one of the most dominant interdecadal variations over the Asian continent since 1976/1977. In addition, we investigated the long-term trend mode of 850 hPa geopotential height data over the Asian continent from the Empirical Orthogonal Function (EOF) analysis for 1958-2004. In result, we found that there was an anomalously high pressure pattern over the Asian continent, it is called 'the Asian High mode'. It is thus suggested that the Asian High mode is another response of interdecadal changes of large-scale circulations over the Asian continent.

• Journal of Radiation Protection and Research
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• v.24 no.1
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• pp.31-38
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• 1999

A real-time dose assessment system(FADAS : Following Accident Dose Assessment System) has been developed for the real-time accident consequence assessment against a nuclear accident. Field tracer experiment near Younggwang nuclear power plant was performed to improve the accuracy of developed system and to parameterize the site-specific parameters into the FADAS. The mean values and turbulent components of wind profile obtained through field experiment have been reflected to FADAS with site-specific conditions. The simulated results of diffusion model agreed well with the measured data through tracer experiment. The developed system is being used as a basic module of emergency preparedness system in Korea. The diffusion model which can be reflected site-specific parameters will be improved through field experiments continuously.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.448-455
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• 2020

This study was carried out to investigate reduction of the frost damage using the mesh net used for the purpose of non-bagged cultivation. A device measuring the weight of frost was developed and installed in both the control and the experimental, and the effect of frost reduction was evaluated with their weights. As a result, weight of frost in the control was reduced from 37% to 59% with mesh net on the day the frost was observed. In addition, the device for automatically observing the amount of frost was developed and the height of the windbreak of the frost measuring device was determined to be 30 cm through wind tunnel experiment. The results of this study are expected to reduce frost damage during the flowering season of fruit trees by installing mesh net and it is expected to be used as basic data for agricultural use of mesh net.

• Structural Engineering and Mechanics
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• v.65 no.3
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• pp.303-314
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• 2018

Shear walls are a typical member under a complex stress state and have complicated mechanical properties and failure modes. The separated-elements model Genetic Evolutionary Structural Optimization (GESO), which is a combination of an elastic-plastic stress method and an optimization method, has been introduced in the literature for designing such members. Although the separated-elements model GESO method is well recognized due to its stability, feasibility, and economy, its adequacy has not been experimentally verified. This paper seeks to validate the adequacy of the separated-elements model GESO method against experimental data and demonstrate its feasibility and advantages over the traditional elastic stress method. Two types of reinforced concrete shear wall specimens, which had the location of an opening in the middle bottom and the center region, respectively, were utilized for this study. For each type, two specimens were designed using the separated-elements model GESO method and elastic stress method, respectively. All specimens were subjected to a constant vertical load and an incremental lateral load until failure. Test results indicated that the ultimate bearing capacity, failure modes, and main crack types of the shear walls designed using the two methods were similar, but the ductility indexes including the stiffness degradation, deformability, reinforcement yielding, and crack development of the specimens designed using the separated-elements model GESO method were superior to those using the elastic stress method. Additionally, the shear walls designed using the separated-elements model GESO method, had a reinforcement layout which could closely resist the actual critical stress, and thus a reduced amount of steel bars were required for such shear walls.