• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.04a
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• pp.30-30
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• 2018

한반도 고유 식물자원인 특산식물 물들메나무의 지리학적 분포 범위에 대한 고찰을 시도 하였으며, 이를 바탕으로 IUCN 적색목록 평가 자료 확보를 위해 IUCN Red List Criteria B의 분포범위(Extent of occurrence)와 점유면적(Area of occupancy)을 측정하였다. 물들메나무 분포도 작성을 위해 분포가 언급된 관련 문헌자료, 국립수목원 표본관(KH) 소장 표본정보, 국가생물종지식정보시스템(Nature) 종발생정보 DB, 그리고 현장조사 자료를 활용하였다. 이를 통해 한반도 특산식물 물들메나무는 지리산을 중심으로 전라남 북도, 경상남 북도 및 충청북도에 분포하고 있는 것으로 나타났으며, 북방한계지역은 경상북도 보현산으로 추정된다. 수집된 분포정보를 바탕으로 IUCN Red List Criteria B의 분포범위(Extent of occurrence)과 점유면적(Area of occupancy)을 계산한 결과 각각 $25,183km^2$, $96km^2$로 나타났다. 하지만 정확한 보전지위 평가를 위해서는 점유면적, 분포범위, 서식지 면적, 개체군 크기에 대한 지속적인 하락과 극단적인 변동을 측정할 수 있는 모니터링과 객관적인 자료가 요구된다.

• Journal of Soil and Groundwater Environment
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• v.8 no.1
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• pp.68-74
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• 2003

SHARP numerical model was used to estimate the interface, ranges and seasonal variations of seawater intrusion. The interface obtained from the SHARP model represented more sensitive to seasonal variations than that estimated from the monitoring wells. When TDS and groundwater velocity vector distributions generated by SUTRA simulations are compared to the interfaces obtained from SHARP simulation, the difference of the range on seawater intrusion is less than 50 m, and the range of seawater intrusion from seasonal variations has the difference of about 12 m. These differences are small for the numerical simulation of the coastal aquifer at regional scale. Therefore, the model with sharp interface is very useful to estimate the interface at this study site, where is regional aquifer system in the scale of seawater infusion. However the SHARP model have some limitations in simulating the range of seawater intrusion, when the hydrodynamic dispersion is significant for seawater intrusion at local aquifer system.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.94-94
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• 2022

본류와 지류가 만나는 하천 합류부에서 발생하는 복잡한 흐름 구조는 하상변동에 영향을 주며, 본류와 다른 특성을 보이는 지류의 유입은 수질과 수생태계에도 영향을 준다. 합류부는 하천 변화의 다양성을 보이기 때문에 하천 관리 측면에서 중요한 구간으로, 흐름 및 혼합 특성 이해가 중요하다. 합류부에서의 흐름 및 혼합은 본류와 지류의 유량비, 밀도차, 단차, 합류각, 하도형상 등의 영향으로 그 양상이 달라지며, 흐름장 및 두 수체에 의한 이송물질의 혼합이 이루어졌다고 간주하는 혼합거리는 지류가 본류에 미치는 영향 범위 분석을 위한 중요한 매개변수이다. 본 연구에서는 합류부 흐름에 미치는 주요 인자 중 유량비와 밀도차가 합류부 흐름 및 혼합에 미치는 영향을 수치해석을 통해 분석하고, 조건의 변화에 따른 혼합거리를 예측해 보고자 한다. 본 연구의 대상 지역인 낙동강-황강 합류부는 다기능보와 댐의 운영에 따라 유입 유량 및 유량비가 조절되며, 여름철에는 황강의 수온이 낙동강보다 평균 4℃ 이상 낮으며, 9℃(지류 20℃; 본류 29℃) 이상의 수온차가 발생하기도 한다. 이 경우 밀도비는 0.998로 밀도류가 발생할 수 있는데, 밀도류가 발생할 경우 수표면과 저층이 분리되어 흐르기 때문에 동일 유량 조건에서도 혼합 양상은 달라진다. 밀도류가 발생하기 위해서는 수표면과 저층이 분리되는 성층이 발달해야 하는데, 이는 유속 또는 유량의 범위에 따라 성층의 발달 여부가 달라질 수 있다. 이러한 현장 조건을 반영한 수치해석을 통해 다양한 유량 조건(유량비)에서 밀도의 차이(수온차)가 합류부의 흐름 및 혼합에 미치는 영향을 분석해 보고자 하며, 합류부에서 밀도차에 의한 흐름의 변화 조건을 무차원수(Richardson number, Densimetric Froude number 등)를 통해 정량화해보고자 한다. 이는 지류가 본류에 미치는 영향의 정도와 범위를 파악함으로써 하천 관리를 위한 관측망 및 현장 조사의 범위 선정의 기초자료 마련뿐 아니라 본류의 수온 변화가 발생할 수 있는 범위의 파악을 통해 수생태계에 미치는 영향 파악을 위한 기초자료로 활용될 수 있을 것으로 기대된다.

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.3
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• pp.154-162
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• 2011

Seawater quality was investigated each month at 30 stations near Tongyeong, South Korea, to provide data for the effective use of coastal fisheries and the reduction of economic damage to marine products. Water temperature was lowest in January and highest at the end of August. Neither extremely low water temperature below $4^{\circ}C$ nor fish damage caused by low water temperature was observed. Salinity ranged from 24.04 to 34.39 psu in the surface layer and from 29.92 to 34.39 psu in the bottom layer. The minimum salinity, attributable to rainfall events, was observed in July; salinity increased to high of about 34 psu in November. Low dissolved oxygen (DO), below 4 mg/L, was observed at Wenmun and Buksin Bays during May to October. Concentrations of $NO_2$-N, $NO_3$-N, and $PO_4$-P were low from March to September and high from October to February. Transparency was 6 m on average and was high in Wenmun Bay. Chemical oxygen demand (COD) and chlorophyll a (Chl. a) were high during summer, when the water temperature was high. With cluster analysis based on environment factors related to water quality, the study area could be divided into three main sea areas: Buksin Bay, coastal seawater, and offshore seawater. Buksin Bay was characterized by low salinity, high DO and Chl. a, and high transparency in the surface layer and by low DO and high $NH_4$-N in the bottom layer. Offshore seawater had high salinity and $NO_3$-N and low Chl. a concentration. In summer season that oyster need lots of phytoplankton, $NO_3$-N and Chl. a concentrations at this study area were low compare to Gwangy-ang and Gamak Bays. In winter, a sea squirt swallow much more than other season, the Chl. a concentrations were also low than Gwangyang and Gamak Bays.

• Journal of Fisheries and Marine Sciences Education
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• v.10 no.1
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• pp.15-30
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• 1998

The variation of the catches of Skipjack(Euthynnus pelamis) and the relationships between the SST and the fishing ground is examined using the catches data of skipjack obtained by Iwawada Fisheries Cooperative of Chiba Prefecture in Japan from 1982 to 1988. The annual mean catch for Skipjack was 151,375.1kg. the annual fluctuation of catch was that the catch in 1984 was increasing, but it was decreased less than 50% in 1985, and was repeated after being a little recovered in 1986, and it was recovered with the level of 1984 in 1988. The fluctuation of catch for Skipjack in every fishing term is that daily mean catch of the primary fishing term (January, February and March) is 894.6kg, but the middle fishing term(April and May) more than four times of the primary fishing term is 3,666.0kg, the last fishing term(June and July) was decreasing at 767.9kg and the fishing ground gradually becomes extinct. The annual mean SST in fishing ground was an extent of from $19.0^{\circ}C$ to $20.2^{\circ}C$, the mean SST of every year except 1983 was from $19.0^{\circ}C$ to $19.9^{\circ}C$. It is said that the optimum SST of Skipjack in Sotobo sea area is the degree of $19.0^{\circ}C$. Therfore, the thing which will guess the time and the location appeared the optimum SST is the very important factor to operate efficiently. About the extent of SST in fishing ground, it was from $17.0^{\circ}C$ to $19.0^{\circ}C$ on March, from $17.5^{\circ}C$ to $20.5^{\circ}C$ on April and from $17.5^{\circ}C$ to $23.5^{\circ}C$ on May, which the extent of SST was gradually larger and larger, on June from $21.0^{\circ}C$ to $23.5^{\circ}C$, fishing ground was formed only the degree of SST more than $21.0^{\circ}C$.

• Economic and Environmental Geology
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• v.56 no.5
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• pp.589-601
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• 2023

We compare high-resolution seabed bathymetry data and seafloor backscattering data acquired, using multi-beam, between 2018 and 2021 to understand topographic changes in the coastal area of Dokdo. The study area, conducted within a 500 m × 500 m in the southern coast between the islands where Dongdo Port is located, has been greatly affected by human activities, waves and ocean currents. The depth variations exhibit between 5 - 70 m. Irregular underwater rocks are distributed in areas with a depth of 20 m or less and 30 - 40 m. As a whole, water depth ranges similar in the east-west direction and become flatter and deeper. The bathymetry contour in 2020 tends to move south as a whole compared to 2018 and 2019. The south moving of the contours in the survey area indicates that the water depth is shallower than before. Since the area where the change in the depth occurred is mainly formed of sedimentary layers, the change in the coast of Dokdo were mainly caused by the inflow of sediments, due to the influence of wind and waves caused by these typhoons (Maysak and Haishen) in 2020. In the Talus area, which developed on the shallow coast between Dongdo and Seodo, the bathymetry changed in 2020 due to erosion or sedimentation, compared to the bathymetry in 2019 and 2018. It is inferred that the changes in the seabed environment occur as the coastal area is directly affected by the typhoons. Due to the influence of the typhoons with strong southerly winds, there was a large amount of sediment inflow, and the overall tendency of the changes was to be deposited. The contours in 2021 appears to have shifted mainly northward, compared to 2020, meaning the area has eroded more than 2020. In 2020, sediments were mainly moved northward and deposited on the coast of Dokdo by the successive typhoons. On the contrary, the coast of Dokdo was eroded as these sediments moved south again in 2021. Dokdo has been largely affected by the north wind in winter, so sediments mainly move southward. But it is understood that sediments move northward when affected by strong typhoons. Such continuous coastal change monitoring and analysis results will be used as important data for longterm conservation policies in relation to topographical changes in Dokdo.

• Journal of Soil and Groundwater Environment
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• v.13 no.1
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• pp.67-76
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• 2008

In this study, a combined model of a water-table fluctuation and a soil moisture content model is proposed for the estimation of groundwater recharge rate at a given location. To evaluate the model, groundwater level data from 4 monitoring wells (Pohang Yeonil, Pohang Kibuk, Suncheon Oeseo, Hongcheon Hongcheon) of National Groundwater Monitoring Network from 1996 to 2005 and precipitation data of corresponding years are used. From the proposed methodology, the groundwater recharge rates are estimated to be from 0.5 to 61.4% for Hongcheon Hongcheon, from 1.1 to 27.4% for Pohang Yeonil, from 5.1 to 41.4% for Pohang Kibuk, and from 1.1 to 8.3% for Suncheon Oeseo. The magnitude of variation of the estimated recharge rate depends on the soil type observed near the stations. The groundwater fluctuation model used in this study includes precipitation as a unique source of water-table perturbation and there may exist corollary limitations. To improve the applicability of the proposed method, a capillary-water content constitutive model for unsaturated fractured rock media may be considered. The proposed recharge rate delineation method is physically based and uses minimum numbers of assumptions. The method may be used as a better substitute for the previous tools for delineating recharge rate of a location using water-table fluctuation method and contribute to national groundwater management plan. Further research on the spatial interpolation of the method is under progress.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.6
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• pp.514-519
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• 2012

Abalone culture is one of important coastal fisheries off Wando in the southeast coast of Korea. Since cage culture for abalones was popularized, Understanding of temperature variation, which is important to raise abalones and to prevent their mass mortalities, is necessary. We analyzed temperature data from 2005 to 2009 obtained at Sinji-do and Cheongsan-do off Wando. Sinji-do, which is relatively close to land, had yearly wide range of temperature and rate of temperature variation. It is likely to be caused by heating of solar radiation in summer and cooling in winter at the shallow area. Rate of temperature variation in autumn was higher than that in spring. In summer short term variation of temperature corresponding tidal period was distinguished clearly. Diurnal temperature range, abrupt temperature change, was larger open sea. Comparison between temperatures of two stations and favorable raising conditions of abalones showed that Cheongsan-do, located out to sea, appears to be more appropriate than Sinji-do.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.2
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• pp.205-211
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• 2016

Based on the Expendable Bathythermograph (XBT) observation and serial oceanographic observation of National Institute of Fisheries Science (NIFS) during July 2013 to July 2015, we examined the temperature variation in the Ulleung Warm Eddy (UWE) in the East Sea. The UWE was always shown during the observation periods even though it was not the whole shape. The coefficient of variation (CV) was largest in the depth of 250 m at the side of the east coast of Korean Peninsula with $3{\sim}4^{\circ}C$ in temperature. CV of the horizontal distribution at 250 m depth was also largest in the region biased along the east coast of Korea. The warm eddy moved not only to the east-west direction but also to the north-south direction in the viewpoint of horizontal distributions of temperature. This region between the Korean Peninsula and Ulleung island also is the passage of the East Korean Warm Current. This means that interaction between the East Korean Warm Current and periphery of warm eddy makes large in the variation of movement along the east coast of Korean Peninsula. The largest variation of temperature at 250 m depth seemed to be significantly correlated with the East Sea Intermediate Water (ESIW) underlying Ulleung Warm Eddy. It is suggested that the interaction between the ESIW and UWE is active in the mid-depth along the periphery of UWE.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.1
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• pp.131-135
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• 2008

Purpose: To measure and quantify the factors of intraocular pressure (IOP) variation for normal Korean youth. Methods: The IOP of normal youth 805 persons (male: 367, female: 438) were measured as a function of time and quantity for fixation, reclining posture, hard blinking, drinking water, drinking hard liquor, tobacco and coffee by using non-contact tonometer (AT555, Reichert Co.). In the case of fixation, reclining posture and hard blinking, the intraocular pressure of right and left eye were measured for 6 males and 6 females every 10 minutes during 30 minute. In the case of water, liquor, tobacco and coffee, the measurement for 4 or 5 groups (6 persons/ group) having similar IOP were done for the IOP variation of right eye. Results: The mean IOP was 15.2 mmHg for males and 15.8 mmHg for females (slightly higher than male's), respectively and the 99% of those were in the range of the normal IOP. The measured IOP was increased by fixation, reclining posture and hard blinking with males and females. The gradient of increasing slope was 0.15/0.13/0.07/0.08, 0.09/0.08/0.08/0.08 and 0.19/0.08/0.26/0.31, respectively. The IOP variation was elevated by drinking water (especially in the case of 1000 ml) and lowered in proportion to the amount of drinking by hard liquor. Cigarette smoking was associated with rise in intra ocular pressure, but was not shown a definite relation. And coffee had virtually no effect. Conclusions: Fixation, reclining posture, hard blinking and Tobacco caused a transient increase in IOP, but alcohol elicited a slight reduction in IOP overall.