• 한국지구물리탐사학회:학술대회논문집
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• 2002.09a
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• pp.101-125
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• 2002

A lake seismic survey was carried out to investigate possible geohazards for construction of the underground LPG storage at Namyang Lake. The proposed survey site has a land-lake combined geography and furthermore water depth of the lake is shallow. Therefore, various seismic methods such as marine single channel high resolution seismic reflection survey, sonobuoy refraction survey, land refraction survey and land-lake combined refraction survey were applied. Total survey amounts are 34 line-km of high resolution lake seismic survey, 14 lines of sonobuoy refraction survey, 890 m of land refraction survey and 8 lines of land-lake combined refraction survey. During the reflection survey, there were severe water reverberations from the lake bottom obscured subsurface profiling. These strong multiple events appeared in most of the survey area except the northern and southern area near the embankment where seems to be accumulated mainly mud dominated depositions. The sonobuoy refraction profiles also showed the same Phenomena as those of reflection survey. Meanwhile the results of the land-lake combined refraction survey showed relatively better qualities. However, the land refraction survey did not so due to low velocity soil layer and electrical noise. Summarized results from the lake seismic survey are that acoustic basement with relatively flat pattern appeared 30m below water level and showed three types of bedrock such as fresh, moderately weathered and weathered type. According to the results of the combined refraction survey, a velocity distribution pattern of the lake bottom shows three types of seismic velocity zone such as >4.5 km/s, 4.5-4.0km/s and <4.0km/s. The major fault lineament in the area showed NW-SE trend which was different from the Landsat image interpretation. A drilling was confirmed estimated faults by seismic survey.

• Korean Journal of Ecology and Environment
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• v.37 no.1 s.106
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• pp.57-63
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• 2004

Primary productivity of phytoplankton was measured by $^{14}C$ method from January to October of 1996 in Seonakdong River. This river was a highly productive freshwater showing the euphotic depth of 1.4 m in August and 2.1 m in the remaining season. Chlorophyll-a concentrations of phytoplankton ranged from 67 ${\mu}g\;L^{-1}$ to 894 ${\mu}g\;L^{-1}$ and showed the great increase in August. Maximum specific productivity was 2.1 ${\sim}$4.3 mg C mg $chl-a{-1}\;hr^{-1}$ and occurred above 0.4m depth. In photosynthesis-irradiance relation, photoinhibition or photosynthetic suppression of phytoplankton occurred clearly in the cold seasons, while phytoplankton (mainly Microcystis aeruginosa and its relatives) in August did not show any symptom of the photosynthetic inhibition against the high irradiance. The specific productivity of phytoplankton was eventually dependant upon incident irradiance to show the linear correlation with received irradiance infield, and the areal productivity of phytoplankton upon chlorophyll-a standing crops. In the downstream of the Nakdong River, phytoplankton productions have linearly increased since the estuarine barrage construction to reflect the gradual eutrophication in the estuarine area. Average chlorophyll-a increase of 10 ${\mu}g\;chl-a\;L{-1}$ absolutely corresponded to the primary production acceleration of 30 mg C $m^{-2}\;day^{-1}$ on the annual basis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5060-5065
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• 2012

The purpose of this study was to report the incidence of drowning accident in order to prevent and decrease the accidents of drowning. Data were obtained on all accidents of drowning accidents occurred from January to December 2007 were identified by using the Emergency Activity Daily Report Data from the National Emergency Management Agency (NEMA). The age, weather, date, location, time and case of the drowning accident were examined. The Chi-square test was used to compare each group. All comparisons were made at the p<0.05 level of significance. The result show that the age of drowning accidents for victims aged 20-29 was 27.9%, and for victims aged 30-39 years, 18.7%. In reguard to the age group, drowning accidents during recreational aquatic activity was age 20-39; 51(44.8%). In reguard to the locations, the number of drowning accidents in a lake or reservoir during recreational aquatic activity was 62(53.4%). The number of drowning accidents in a lake or reservoir during etc was 51(58%). In reguard to the days, the number of drowning accidents on Saturday during recreational aquatic activity was 30(25.8%), on Sunday 32(27.6%). The weather of drowning accidents during recreational aquatic activity was sunny 60(51.8%), rainy 40(34.4%), cloudy 16(13.8%). The season of drowning accidents during recreational aquatic activity was summer 53(45.7%). In reguard to season, two groups are significantly different. Drowning is a leading cause of injury related accidents. Understanding the characteristics of drowning is the first step to developing prevention strategies that may be beneficial for people of all ages and under nearly all circumstances are increased swimming ability, lifeguard staffing, providing life jackets, and public education activities.

• Economic and Environmental Geology
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• v.47 no.5
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• pp.517-532
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• 2014

The Munamdong Formation is a small scale sedimentary deposit which is located in Yuljeonri, Naemyeon, Hongcheon Gangwon-do. In order to understand the depositional environment and its sequential change in the formation, sedimentary facies analysis was conducted. The result indicates that the Munamdong Formation began to be deposited in alluvial fan system accompanying volcanic activity and gradually deposited in lake system. As well, U-Pb, K-Ar and $^{40}Ar/^{39}Ar$ ages are determined from the Munamdong Formation. The SHRIMP U-Pb Phanerozoic Eon age of the detrital zircons in the middle part of the Munamdong formation yields $229.8{\pm}2.5Ma$. The K-Ar and $^{40}Ar/^{39}Ar$ ages of the volcanic rock in the lowermost part of the Munamdong formation are $203.7{\pm}3.9Ma$ and $227.4{\pm}8.4Ma$ respectively. These results confirm that the Munamdong Formation was deposited during the Late Triassic, indicating that the basin might be formed due to post-collisional rifting or collapsing.

• Journal of the Korean earth science society
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• v.35 no.4
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• pp.290-294
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• 2014

In this study, we investigated the characteristics of rodent (mainly ground squirrel) burrows found near the Lake Hovsgol, Mongolia. Those burrows are straight to slightly curved and gently inclined in lateral view. Cross-sectional shapes are either circular or elliptical with diameters ranging from mostly 8-10 cm. Most abandoned burrows are passively filled with soils and/or pebbles. The size and architecture of these Mongolian burrows are remarkably similar to those of the previously reported Late Pleistocene burrows from Korea. Therefore, the rodent burrows found at Korean Palaeolithic sites are thought to have been formed by ground squirrels. However, the difference in burrow-fills suggests that the mean annual precipitation of the Korean Peninsula during the Late Pleistocene is much higher than that of Mongolia.

• Journal of Korean Society of Forest Science
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• v.81 no.3
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• pp.203-213
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• 1992

The purpose of this study is to segment recreationists into groups which are homogeneous with respect to their spending patterns and trip characteristics. Date were derived from a larger study aimed at developing nationally representative expenditure profiles for recreation visitors to Corps of Engineers projects. Segmentation of these data reduces variance and helps to identify distinctive final demand vectors for input - output application. A - priori and cluster analysis approaches for identifying segments are compared. The a - priori segmentation approach identified 12 segments and the cluster analysis approach identified 3 segments. The 3 nonresident clusters - labeled "day use", "overnight", and "overnight camping" - show lower mean squares within groups than the a - priori segments on almost all nonresident spending categories with an exception of boating expenses. For the Corps of Engineers, implications of these findings for the estimation of economic impacts are discussed.

• Korean Journal of Ecology and Environment
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• v.45 no.3
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• pp.278-288
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• 2012

The zooplankton community of Lake Paldang, Korea, was investigated on a weekly basis from 2004 to 2006. The seasonal succession of zooplankton community structure was influenced by hydrological factors such as rainfall pattern and efflux in Lake Paldang. According to the monsoon climate, spring, fall and winter had reduced precipitation, so that zooplankton dynamics of the lake showed a typical succession pattern. In spring, small sized and faster growing rotifera rapidly increased, and copepods and cladocera noticeably increased thereafter. Rotifera dominated the zooplankton community, occupying more than 90% of total zooplankton abundance. Among rotifera, Keratella cochlearis was extremely dominant in spring. Copepoda were mainly present as Copepodid and Nauplius. Among cladoceran species, Bosmina longirostris was dominant. In summer, during the rainy season, zooplankton were flushed out by an associated dam. After the rainy season, rotifera increased rapidly when the water column of the lake was stable. During the fall, zooplankton abundance gradually reduced in accordance with decreasing water temperature. However, the occupation rate of copepod (Copepodid, Nauplius) increased relatively. Zooplankton dynamics were influenced by meteorological changes and hydraulic-hydrological factors, because Lake Paldang is a completely closed ecosystem.

• Korean Journal of Ecology and Environment
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• v.45 no.3
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• pp.329-339
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• 2012

In the spring (March to June) in 2010, one diatom Skeletonema costatum occurred outbreaks in Lake Hwajinpo, one of the typical lagoons on the east coast of South Korea. We compared the characteristics of the phytoplankton community during the bloom and extinction period of S. costatum, and evaluated the water quality based on nutritional indices. Results indicate that 1) this bloom showed the highest cell density ($>10^5$ cells $mL^{-1}$) among outbreaks of S. costatum occurred Korea, 2) occurred in below or over $20^{\circ}C$ water temperature, and 3) was destroyed in the early summer with higher temperature than the bloom period. Water quality or trophic status of the lake was eutrophic to hypertrophic with high salinity, BOD, COD and phosphate, and low N/P ratios and transparency. Phytoplankton community in the spring bloom had a high dominance and low diversity, but rightly recovered to low dominance and high diversity in the summer season. Therefore, we temporarily conclude that the bloom of S. costatum in Hwajinpo was triggered by the extended spring drought and the reduced influx of river water, and appeal that the bloom can happen repeatedly every year.

• Journal of the Korean earth science society
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• v.34 no.6
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• pp.492-506
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• 2013

The historical accounts and materials about the eruption of Mt. Baekdusan as observed by the geological survey is now showing some signs of waking from a long slumber. As a response of the volcanic eruption of Mt. Baekdusan, water release may occur from the stored water in Lake Cheonjii caldera. The volcanic flood is crucial in that it has huge potential energy that can destruct all kinds of man-made structures and that its velocity can reach up to 100 km $hr^{-1}$ to cover hundreds of kilometers of downstream of Lake Cheonji. The ultimate goal of the study is to estimate the level of damage caused by the volcanic flood of Lake Cheon-Ji caldera. As a preliminary study a scenario-based numerical analysis is performed to build hydrographs as a function of time. The analysis is performed for each scenario (breach, magma uplift, combination of uplift and breach, formation of precipitation etc.) and the parameters to require a model structure is chosen on the basis of the historic records of other volcanos. This study only considers the amount of water at the rim site as a function of time for the estimation whereas the downstream routing process is not considered in this study.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.3
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• pp.202-211
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• 2011

In this study the seasonal and spatial pattern of mercury (Hg) concentrations in multimedia environments were investigated in Lake So-Yang. Total mercury (TM) in water column greatly enhanced as turbidity and particulate organic carbon (POC) increased due to the severe runoff, suggesting that most of Hg existed as particulate Hg in Lake Soyang. We also collected 22 species of fish in Lake Soyang and Han River, and the average total mercury in fish was 0.073 ppm, lower than both Korean (0.5 ppm) and EPA criteria (0.3 ppm). However when considering the amount of fish intake for Korean the Hg criterion in fish must be more stringent than current value, and the advisory for fish consumption should be made. Hg in fish considerably varied with sampling sites, having the highest in the upper region (Yang-gu) and the lowest in downstream (Han River). This spatial variation was possibly derived by "bloom dilution" associated with high phosphorus loading or elevated DOC concentrations, or both. Total mercury in sediment varied from 69.9 to $98.3{\mu}g/kg$, which was relatively lower than those measured in Voyageurs National Park in Minnesota in USA ($102{\sim}364{\mu}g/kg$).