• The Korean Journal of Malacology
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• v.30 no.1
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• pp.33-40
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• 2014

The age and growth of Gomphina (Macridiscus) veneriformis sampled from February 2006 to January 2007 on the Wonsan coast of East Sea were determined from 3,899 shell. Age of Gomphina (Macridiscus) veneriformis was estimated from the ring on the surface of shell. The relationship between shell length (SL) and shell height (SH) was expressed by the following equation : SH = 0.7405 SL + 0.2227 ($R^2$ = 0.9671), and shell length (SL) and shell width (SW) was highly correlated by the equation : SW = 0.3657 SL + 0.4253 ($R^2$ = 0.922). The relationship between shell length (SL) and total weight (TW) was also expressed by the following equation : $TW=0.4274{\times}10^{-3}{\times}SL^{2.7876}$ ($R^2$ = 0.9591). The main spawning periods was estimated August through fatness index analysis. Based on the monthly variations in the marginal index (MI) of the shell, it is assumed that the ring of this species was formed once a year during the period of July. Growth curves for shell length (SL) and total weight (TW) fitted to the von Bertalanffy's equation were expressed as follows : $$SL_t=70.80(1-e^{-0.217(t+0.367)})$$ $$TW_t=(1-e^{-0.217(t+0.367)})^{2.7876}$$

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.1 s.53
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• pp.89-97
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• 2007

Parameters including the seismic sources and the elastic wave propagation characteristics were analysed using the observed ground motions from 12 Fukuoka region earthquakes. The Levenberg-Marquardt algorithm was applied to invert all the variables non-linearly and simultaneously with S wave energy in fiequency domain. Average stress drop of 12 events and local attenuation parameter $\kappa$ under seismic stations were estimated to about 79.2-bar and 0.043 respectively. Regional attenuation parameter, Qo and ${\eta}$, were also estimated to be about 248.1 and 0.558 respectively. Low value of Qo seems to caused by inhomogeneous tectonic characteristics between Japan island and southern Korean peninsula. $\kappa$ values are much higher than that characterizing EUS (Eastern United States) region, and nearly similar to that of WUS (Western Waited States) region. If the informations on site specific amplification of all the seismic stations are known, $\kappa$ values can be estimated more precisely. All the values including the seismic sources and the site and crustal scale propagation characteristics can be used as seismic design parameters.

• Korean Journal of Ichthyology
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• v.11 no.2
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• pp.155-162
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• 1999

To study the distribution of larva and juvenile of the sand eel, Ammodytes personatus in the Kangwon coastal, samples were collected by the larva net (RN 80 net) and small drag net at 60 stations from January 1996 to December. Appearance season of larva and juvenile of sand eel was appeared untill the January to June in the Kangwon-do coast, and the densities of them were high in June. Appearance phase, length frequency distribution of larva and juvenile of sand eel were distributed that the average standard length 10.0~30.0mm in the temperature range of $5.0{\sim}6.0^{\circ}C$ at the January to March, and April to June occurred the average standard length 40.0~80.0 mm in the temperature range of $7.2{\sim}12.0^{\circ}C$. It was distributed in southern part of Kangwon-do coast until the February to March 1996. And association of the sand eel migrated to the northern and middle part of Kangwon-do coast at April when surface water temperature was higher than $7.2^{\circ}C$. It was considered that the migration of the abundance larva and juvenile of sand eel in this area is mainly affected by the water temperature.

• Geophysics and Geophysical Exploration
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• v.2 no.2
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• pp.77-85
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• 1999

The 3-D seismic research vessel, Tamhae II, was built to raise up the probability of the hydrocarbon discovery in the Korean continental shelf and the first test survey was completed in the East Sea. During the survey, the 240 channel 2-D marine seismic data were acquired by the Korean flag vessel for the first time. Tamhae II has been equipped with source, receiver, recording equipment, and navigation equipment as well as an onboard processing system. The source is composed of four subarrays and each subarray has six airguns. Total airgun volume is 4578 $in^3$. The receiver consists of two sets of 3 km long 240 channel streamer. In the first survey, the successful acquisition of 2-D seismic data was accomplished. From the result of the data processing, we confirmed that the high quality seismic data were acquired. For the high quality data acquisition, technology of survey design and planning, operation of vessel and equipments and systematic quality control should be developed.

• International Journal of Highway Engineering
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• v.7 no.4 s.26
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• pp.113-123
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• 2005

In this study, calcium chloride$(CaCl_2)$, sodium chloride (NaCl), organic acids-containing deicer(NS 40, NS 100), mixed deicier$(NaCl\;70%+CaCl_2\;30%,\;NS\;40\;70%+CaCl_2\;30%,\;NaCl\;70%+NS\;40\;30%,\;NS\;40\;70%+NaCl\;30%)$ is investigated based on the laboratory test for deicing performance, freez-thaw resistance of concrete, and corrosion rate of metal. Test items for deicing performance were ice melting and ice penetration, freezing point depressions and eutectic point, pH, thermal properties for selected deicing chemicals as well as their compatibility with concrete and metal were experimentally investigated. As a test results, in case of the use chloride-containing deicier in area that concrete structures has subjected to freez-thaw reaction in winter season, it showed that mixed deicing chemicals with optimum ratio has desirable method than use one deicing chemicals when is consider to deicing performance and effects, corrosion of steel materials, and freez-thaw resistance of concrete. When use various deicing chemicals mixed, NS40(70%)+calcium chloride(30%) showed the best effective method.

• Journal of Environmental Science International
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• v.19 no.11
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• pp.1397-1405
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• 2010

Mass mortalities of cultivated organisms have occurred frequently in Korean coastal waters causing enormous losses to cultivating industry. The preventive measures require continuous observation of farm environment and real-time provision of data. However, line hanging aquaculture farm are generally located far from monitoring buoys and has limitations on installation of heavy equipments. Substituting battery pack for solar panels and miniaturizing size of buoy, newly developed system can be attached to long line hanging aquaculture farm. This system could deliver measured data to users in real-time and contribute to damage mitigation and prevention from mass mortalities as well as finding their causes. The system was installed off Gijang and Yeongdeck in Korea, measuring and transmitting seawater temperature at the sea surface every 30 minutes. Short term variation of seawater temperature, less than one day, in Gijang from June to July 2009 corresponded tidal period of about 12 hours and long term variation seemed to be caused by cold water southeast coast of Korea, particularly northeast of Gijang. Seawater temperature differences between Gijang station and the other station that is about 500 m away from Gijang station were $1^{\circ}C$ on average. This fact indicates that it is need to be pay attention to use substitute data even if it is close to the station. Daily range of seawater temperature, one of crucial information to aquaculture, can be obtained from this system because temperature were measured every 30 minutes. Averages of daily range of temperature off Gijang and Yeongdeok during each observation periods were about $2.9^{\circ}C$ and $4.7^{\circ}C$ respectively. Dominant period of seawater temperature variation off Yeongdeok was one day with the lowest peak at 5 a.m. and the highest one at 5 p.m. generally, resulting from solar radiation.

• Journal of the Korean earth science society
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• v.33 no.3
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• pp.280-293
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• 2012

In order to clarify the characteristics of dispersion of volcanic tephra emitted from the Mt. Baegdu with various eruption environment, numerical analysis were performed using numerical models, Weather Research and Forecast (WRF) and FLEXPART. Synoptic conditions at 12 October 2010 was adopted because the volcanic ash of Mt. Baegdu can reach the Korean peninsula and its dispersion pattern was compared with different Volcanic Explosivity Index (VEI) and particle size. Predominant size of falling out ash flowing in the peninsular is smaller than 0.5 mm and the ash large than the size is difficult to get in the peninsular due to the its weak ability of truculent diffusion. the difference of ash distribution with various VEI scenarios is not so much but number density of ash in the air is dramatically changed. Volcanic ash tends to be deposited easily in eastern coastal area such as Gangneung and Busan, because of the inflow of ash from East Sea and barrier effect of the Taeback mountains along the east coast of the Korean Peninsula. Accumulated amount of ash deposition can be increased in short period in several urban areas.

• Journal of the Korean earth science society
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• v.41 no.3
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• pp.222-237
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• 2020

A heavy (93 mm hr^-1) rainfall event accompanied by lightning occurred over Gangneung in the Yeongdong region of South Korea on August 6, 2018. This study investigated the underlying mechanism for the heavy rainfall event by using COMS satellite cloud products, surface- and upper-level weather charts, ECMWF reanalysis data, and radiosonde data. The COMS satellite cloud products showed rainfall exceeding 10 mm hr^-1, with the lowest cloud-top temperature of approximately -65℃ and high cloud optical thickness of approximately 20-25. The radiosonde data showed the existence of strong vertical wind shear between the upper and lower cloud layers. Furthermore, a strong inversion in the equivalent potential temperature was observed at a pressure altitude of 700 hPa. In addition, there was a highly developed cloud layer at a height of 13 km, corresponding with the vertical analysis of the ECMWF data. This demonstrated the increased atmospheric instability induced by the vertical differences in equivalent potential temperature in the Yeongdong region. Consequently, cold, dry air was trapped within relatively warm, humid air in the upper atmosphere over the East Sea and adjacent Yeongdong region. This caused unstable atmospheric conditions that led to rapidly developing convective clouds and heavy rainfall over Gangneung.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.441-449
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• 2005

The purpose of this research is to present the improvement measure of lagging behind coastal shipping system to be a logistic hub-nation with a competitive edge. For this purpose, this research tries to find out major northeast asia environment factors and accordingly the effects of its. The effects of coastal shipping system's development strategy is analysed by structural equation model and multiple regression model. Research results show that three types of coastal shipping developing strategy(connected transportation system, structure of coastal shipping system, governmental support policy) will contribute much to be logistic hub-nation. The contribution effects is increasing cargo from strengthened feeder transport system and maximizing logistic service &minimizing logistic costs. From the result, some implications are derived as follow. First, familiar environmental balanced ocean-coastal transport system is required. Second the one-stop logistic service system is necessary to build excusive feeder port, and to establish Ro-Ro ship & high-speed ship, etc.. Third, governmental support policy and subsidy(tax exempted oil & various tax benefits) are required to bring up lagging behind coastal shipping system to be a logistic hub-nation with a competitive edge.

• Journal of the Korean Geographical Society
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• v.49 no.3
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• pp.321-338
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• 2014

This study aims to identify spatial distribution of estuarine wetlands in Korea, and to assess temporal variation of the wetlands in the last few decades. Widely known in environmental and coastal management, watershed-based regions which composed with Han-river(western and eastern parts), Keum-river, Yeoungsan-river, Seomjin-river, Nakdong-river, and Jeju, are analyzed to evaluate temporal change of estuarine wetlands in the 1980s, 1990s, and 2000s, through the land-cover map. Results show that estuarine wetlands dramatically decreased in Han-river(western part), Keum-river, Yeoungsan-river that estuarine circulation have been interrupted with man-made structures such as dyke and drainage. But, estuarine wetlands surrounded by forests and grasslands has been relatively less damaged. Habitat diversity providing healthy estuary ecosystem is lower in interrupted estuaries than circulated estuaries, which are composed of tidal-flat, open water, salt marsh, rocky coasts and sandy shoreline. This study indicates that spatial distribution and temporal variation of estuarine wetlands are different with estuary type and region, so estuary type with seven regions can be applied to provides a framework for estuary management strategies and to establish estuary restoration plans.