• Korean Journal of Soil Science and Fertilizer
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• v.41 no.6
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• pp.419-424
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• 2008

Objective of this study was to evaluate the adaptation and the soil conservation effect of improved wild vine in sloped upland of highland about 600m from sea level in Korea. A mainly producing district of the improved wild vine in Korea was distributed 230m to 540m from sea level, and its rainfall ranged 1,200 to 1,700 mm. The lowest temperature was from -19.6 to $-25.4^{\circ}C$. Their soil texture was from sandy loam to clay loam, where drainage class was well drained and the contents of soil organic matter and total nitrogen in the improved wild vine's cultivation area were higher than those of Chinese cabbage's cultivation area in the highland. According to improved wild vine's cultivation methods, the amounts of soil erosion were 25.5,4.1, and $1.8MT\;ha^{-1}$ in clean culture, part sod + mulching, and nature sod, respectively. Those were below 30 to $80MT\;ha^{-1}$ of sloped upland at highland in Korea. The result suggests that it is possible to cultivate the improved wild vine over wintering at 600m of highland above the sea level. We can substitute the improved wild vine for Chinese cabbage in the highland for soil conservation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.333-338
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• 2016

The purpose of this study was to understand the pollution level of the surface sediment of Sihwa Lake by assessing its geochemical characteristics and investigating the spatial distribution of trace metals and organic matter. In the surface sediment of Sihwa lake, the mean grain size was between 2.94 and 6.35 Ø and the main type of sediment was sandy silt. The concentrations of As, Co, Cr, Ni, V and Li among the metal elements in the surface sediment were correlated with the mean crust concentration (p<0.05). Based on the strong correlation between the metals (Cd, Cu, Pb and Zn) and organic matter (Ignition Loss), the concentrations of these metal elements seem to be controlled by the organic matter dilution effect. The trace metal pollution level, determined by applying the Republic of Korea Marine environmental standard and the US National Oceanic and Atmospheric Administration's sediment quality guidelines, showed the pollution level of As to be either close to or in excess of the above-mentioned standards at almost all levels. The enrichment factor and geoaccumulation index of As showed that there was an incremental increase of pollution by elements other than V, Cr, Co, Fe, Al and Mn. Moreover, the nearby industrial area and dike were more polluted than the other areas, so the surface sediments in Sihwa lake should be monitored by taking into consideration the geological variations.

• Economic and Environmental Geology
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• v.24 no.3
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• pp.319-327
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• 1991

Cheju is the biggest island in Korean peninsula, consisted entirely of volcanic rocks and pyroclastic sediments. The topography is characterized by wide basalt plain in the low altitude but at the center of island, basalt volcano rises 1,950m above sea-level. Surface drainage is very poor, therefore water supply has been dependent on ground water and natural springs. There are about 1,650 production wells and most of them yield $1,000{\sim}2,000mm^3/day$. According to increase of ground water use, saline water is intruded in the low altitude of coastal area. Specially in the eastern coastal area, the topography is extensively flat and the level of ground water is very close to sea-level, at which overuse of ground water has brought saline intrusion up to maximum 6km far from the coast. Hydrochemical monitoring on this salt water intrusion is now undertaken on long term base.

• Geophysics and Geophysical Exploration
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• v.14 no.4
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• pp.298-304
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• 2011

We conducted magnetic survey using IBRV (Ice Breaker Research Vessel) ARAON of KORDI (Korea Ocean Research and Development Institute), ROV (Remotely Operated Vehicle) of Oceaneering Co. and three components vector magnetometer, at Apr., 2011 in the western slope of the caldera of TA25 seamount, the Lau Basin, the southwestern Pacific. The depth ranges of the survey area are from about 900 m to 1200 m, below sea level. For the deep sea magnetic survey, we made the nation's first small deep sea three components magnetometer of Korea. The magnetometer sensor and the data logger was attached with the upper part and lower part of ROV, respectively. ROV followed the planning tracks at 25 ~ 30 m above seafloor using the altimeter and USBL (Ultra Short Base Line) of ROV. The three components magnetometer measured the X (North), Y (East) and Z (Vertical) vector components of the magnetic field of the survey area. A motion sensor provided us the data of pitch, roll, yaw of ROV for the motion correction of the magnetic data. The data of the magnetometer sensor and the motion sensor were recorded on a notebook through the optical cable of ROV and the network of ARON. The precision positions of magnetic data were merged by the post-processing of USBL data of ROV. The obtained three components magnetic data are entirely utilized by finding possible hydrothermal vents of the survey area.

• Journal of the Korean earth science society
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• v.22 no.1
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• pp.30-39
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• 2001

To consider the distribution of the surface sediments and sedimentary processes in tidal flat after the construction of sea-walls in the semiclosed Muan Bay, the southwest coast of Korea, studies on the sediments and sedimentation rates along two transect lines from February 1999 to March 2000 were carried out. The surface sediments in the bay are classified into 5 facies on the basis of textural parameters. The gravelly sediments including the cobbles and pebbles deposited in the bay-mouth are relic sediments which are formed in nearshore and fluvial environments at the low stand of sea level. In addition, it is considered that the muddy sediments widely distributed on the tidal flat might be originated from suspended matter transported from several rivers and/or offshore. Although the sedimentation rates on the tidal flat vary with season, their estimation rates are -8.9 mm/yr on Line-GR and -48.9 mm/yr on Line-YH, respectively. The erosion-dominated processes in the tidal flat would be caused by strengthened ebb tides due to the decrease of tidal choking at Mokpogu and the migration of tidal currents at the bay-mouth. The hydrodynamical changes mentioned above are interpreted to be occurred after/before the construction of sea-dike/sea-walls in coastal zone of Mokpo.

• Korean Journal of Construction Engineering and Management
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• v.8 no.5
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• pp.142-151
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• 2007

The rock excavation work on the sea is planned as underwater process if the elevation of the rock is lower than the M.S.L.(Mean Sea Level). However, in case of West and South sea which are largely different between the rise and fall of the tide, the earth work can be performed on the ground while the work surface is exposed above the sea according to the tide cycle. Thus, it may a good substitute to make up for shortcomings of underwater construction works such as safety problems of workers, loss of efficiency and increasement of construction costs. But the difference between the height of the rock excavation surface and the water surface changed by the tide makes the exposure time of work surface, that is the possible working hours be changed. Also, it may cause the changes of construction cost. Thus, this study analyzes the economical efficiency of the construction method using the difference between the rise and fall of the tide in comparison with the construction method which is performed under the sea, and it also suggests the way to analyze the economical working hours by estimating the possible working hours on the ground. We also try to find out the application possibility of the way like the rock excavation work on the sea using the difference between rise and fall of the tide.

• Journal of Welding and Joining
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• v.15 no.1
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• pp.46-54
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• 1997

The object of this paper is to evaluate SCC(stress corrosion cracking) susceptibility for parent metal and bond line region of weld joints which have the various weld heat input condtions in TMCP(thermo-mechanical control process) steel by SP-SSRT(small punch-slow strain rate test) method. And the SCC test results of TMCP steel are compared with those of the conventional HT50 steel which has te almost same tensile strength level like TMCP steel. The loading rate used was $3\times10^{-4}$mm/min and the corrosive environment was synthetic sea water. According to the test results, in the case of parent metal, TMCP steel showed higher SCC susceptibility than HT50 steel because of the high plastic strain level of ferrite microstructure obtained by accelerated cooling. And in the case of bond line, the both TMCP steel and HT50 steel showed low load-displacement behaviors and higher SCC susceptibility above 0.6. These results may be caused by theembrittled martensite structure on HT50 steel and by the coarsened grain and the proeutectoid ferrite structure obtained by the impart of accelerated cooling effect on TMCP steel.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.2
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• pp.189-191
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• 1999

Mineral profile of serum and cerebrospinal fluid (CSF) of 15 Himalayan Yak (adult female, n=8; adult male n=4 and young male,n=3) was studied in their natural habitat at an altitude of 3300 meters above mean sea level at Sangla in north western Himalayas. The macro and micro minerals estimated in serum and CSF were; Sodium, Potassium, Calcium and Magnesium and Zinc, Copper and Iron respectively. The values recorded among different Yak groups did not significantly differ from each other except serum iron and haemoglobin which were significantly higher (p<0.05 ) in young male Yaks compared to the adult male and female Yaks. An observation of great significance was considerably higher potassium and lower sodium level in Yaks compared to other bovine species of plains. The serum potassium values in some adult female Yaks were recorded as high as 10.4 mEq/l and the values varied between 6.6 to 9.8 mEq/l in young male Yaks. The serum Sodium values and Na:K ratios in Yak serum ranged between 117.5 to 122.6 mEq/l and 13.7 to 15.3 respectively. The possible relationship of high serum Potassium value with hypoxic conditions and hostile mountain environment has been discussed.

• The Journal of Fisheries Business Administration
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• v.29 no.1
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• pp.65-88
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• 1998

The sustainable reduction of the fisheries resource is keenly raised an urgent problem of the fisheries policy in Korea, China and Japan. Then, 3 country, Korea, Japan, China, have established various system for fisheries resource management. Among these systems, qualitative fishing regulations have been commonly established. For example, its have been enforced to the prohibited fishing region, fishing period, fish size, net size, specified fishing methods. Also, different fisheries resource management policies have occasionally enforced by each country. For example, the prohibition of free sale and free possession has been established in Korea and Japan, but not China. And, In Korea, It has been enforced uniquely to entry system far fishing license number ana sea farming project for coastal fishing grounds by national government. The entry system for fishing license number has been enforced in Japan too, not national government, but local government. Nevertheless these three countries have put good system for fisheries resource management above mentioned, real enforcement has been not operated well. For efficient management on same fisheries, next problem will have been solved. First, it has to be guaranteed to transparency on the fisheries management, which is considered the priority problem on the fishing regulation. For reason, although efficient system is established in each country, if feasibility of the system was not trusted, mutual effort like that is very difficult to gain desired results. Then, each country has to establish transparency on the fisheries statistics and administration. Second, it has to be adjusting on the criteria or level of fisheries resource management. Now Korea, Japan and China have different criteria or level of fisheries resource management, for, example, prohibited fish size and prohibited fishing net sine. To solve above problems, three countries need to deeply discuss together. Then fisheries resource co-management scheme should be established in same fishing ground.

• Economic and Environmental Geology
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• v.38 no.6 s.175
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• pp.633-642
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• 2005

We present the sedimentary sequence and distribution pattern of the late Holocene muddy deposits in the northern East China Sea shelf using the high-resolution 'Chirp' profiles. The seismic sedimentary sequence overlying acoustic basement (basal reflector-B) can be divided into two depositional units (Unit 1 and 2) bounded by erosional bounding surface (mid reflector-M). The lower Unit 1 above basal reflector-H is characterized by the acoustically parallel to subparallel reflections and channel-fill facies. The upper Unit 2, up to 7 m in thickness, shows seismically semi-transparent seismic facies and lenticular body form. On the base of sequence stratigraphic concept, these two sediment units have developed during transgression and highstand period, respectively, since the last sea-level lowstand. The transgressive systems tract (Unit 1) lie directly on the sequence boundary (reflector B) that have farmed during the last glacial maximum. The transgressive systems tract in this study consists mostly of complex of delta, fluvial, and tidal deposits within the incised valley estuary system. The maximum flooding surface (reflector M) corresponding to the top surface of transgressive systems tract is obviously characterized by erosional depression. The highstand systems tract (Unit 2) above maximum flooding surface is made up of the mud patch filled with the erosional depression. The high-stand mud deposits showing a circle shape just like a typhoon symbol locates about 140 km off the south of Cheju Island with water depth of $60\~90m$. Coverage area and total sediment volume of the mud deposits are about $3,200km^2$ and $10.7\times10^9\;m^3$, respectively. The origin of the mud patch is interpreted as a result of accumulating suspended sediments derived from the paleo-Yellow and/or Yangtze Rivers. The circular distribution pattern of the mud patch appears to be largely controlled by the presence of cyclonic eddy in the northern East China Sea.