• Korean Journal of Agricultural and Forest Meteorology
• /
• v.13 no.1
• /
• pp.28-34
• /
• 2011

This study was carried out to estimate monthly mean of daily maximum and minimum temperature across North Korea at a 30 m grid spacing for a climatological normal year (1971-2000) and the 4 decadal averages (1971-1980, 1981-1990, 1991-2000, and 2001-2010). A geospatial climate interpolation method, which has been successfully used to produce the so-called 'High-Definition Digital Climate Maps' (HD-DCM), was used in conjunction with the 27 North Korean and 17 South Korean synoptic data. Correction modules including local effects of cold air drainage, thermal belt, ocean, solar irradiance and urban heat island were applied to adjust the synoptic temperature data in addition to the lapse rate correction. According to the final temperature estimates for a normal year, North Korean winter is expected colder than South Korean winter by $7^{\circ}C$ in average, while the spatial mean summer temperature is lower by $3^{\circ}C$ than that for South Korea. Warming trend in North Korea for the recent 40 years (1971-2010) was most remarkable in spring and fall, showing a 7.4% increase in the land area with 15 or higher daily maximum temperature for April.

• Resources Recycling
• /
• v.22 no.5
• /
• pp.43-49
• /
• 2013

Froth flotation was performed to remove As from the tailing of Sangdong Mine. When the tailings of Sangdong Mine were analyzed by the Standard Method for the Soil Environment Conservation, the concentration of As was found to be at a serious level (282 mg/kg), exceeding countermeasure standard (75 mg/kg). Froth flotation was performed to remove As and preliminary tests were performed to select the reagents. Specifically, froth flotation was performed using collector and frother, KAX and DF250 respectively. An experiment based on pH changes found that the removal rate was highest at pH6. The removal rate of As was highest at agitating rate 1500 according to the agitating rate. In the experiment based on the quantities of KAX added, the removal rate of As was found to be highest at 300 g/ton and was reduced at higher levels than 300 g/ton. An experiment based on pulp density found that the removal rate was highest at pulp density 30%. It was possible to adjust the As level -- which exceeded countermeasure standard (75 mg/kg) -- to 22.5mg/kg to satisfy the Warning standard (25 mg/kg), from the results of froth flotation.

• The Journal of the Petrological Society of Korea
• /
• v.28 no.2
• /
• pp.53-69
• /
• 2019

In the Jirisan area of the Yeongnam Massif, Korea, several ductile shear zones are developed within Precambrian gneiss complex (Jirisan metamorphic rock complex). The ductile shear zones have a general NS- and NNE-striking foliation with westward dipping directions. The foliation developed in the shear zones cut the foliation in gneiss complex. The stretching lineations are well developed in the foliated plane of the shear zone, showing ENE-trend with gentle plunging angle to the ESE direction. Within shear zone, several millimetric to centimetric size of porphyroclasts are deformed strongly as a sigmoid form by ductile shearing. The sigmoid patterns of porphyroclasts in the shear zones indicate the dextral shearing. The spatial distribution of ductile shear zone is characterized by the dominant NS- and NNE-striking dextral sense in the central and eastern regions respectively. In the western part, it develops in NE-striking dextral sense which is the general direction of the Honam shear zone. The U-Pb concordant ages obtained from the two samples, the strongly sheared leucocratic gneiss, are $1,868{\pm}3.8Ma$ and $1,867{\pm}4.0Ma$, respectively, which are consistent with the U-Pb ages reported around the study area. We supposed that the ductile shearing in the study area is occurred about 230~220 Ma during late stage of the continental collision around Korea and is preceded by granitic intrusion related to subduction during 260~230 Ma, which are supported by compiling the age data from sheared gneiss, deformed mafic dyke intruded gneiss complex, and non-deformed igneous rocks.

• Journal of the Korean Geotechnical Society
• /
• v.27 no.2
• /
• pp.17-26
• /
• 2011

To solve the problem of saturated dredged soil dumping area, it is possible to extend the life span of dredged soil dumping area by accelerating consolidation of dredged soil and making alluvial soil layer consolidated additionally by using dewatering method and PDF method without construction of new dumping area which entails great expense. Self-weight consolidation tests on samples from Busan and Incheon with the column of 400 mm in diameter were conducted to estimate those methods applicability to domestic dredged soil. As a result of tests, it was proved that dewatering method and PDF method were highly effective in increasing reclamation capacity of dredged soil by reduction of self-weight consolidation completion time and increase of self-weight consolidation settlement.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2005.05a
• /
• pp.145-150
• /
• 2005

A maximum of 3 km thickness of sediments were deposited above basement deformed by volcanic activities around the Dok Island. As the geological structure, the tension caused the basement-involved normal faults in the early stage of basin formation, whereas the sediment layers showed normal faults, volcanic domes and sills caused by volcanic activities. From the distribution of volcanics in order of age at the Ulleung Basin, volcanic activities were increased toward the northeastern direction (toward Dok Island). The study area is characterized by extensional crustal deformation before sediment deposition during the Early or Middle Miocene age, After the Late Miocene age, the basin was deformed by deep buried volcanics or subsidence of basin, in consequence, became complex geological structures.

• The Journal of the Petrological Society of Korea
• /
• v.18 no.4
• /
• pp.349-370
• /
• 2009

The Mt. Dungjuribong Volcanic Complex located in Gurye-gun, southwest of Ryeongnam massif, composed of Cretaceous andesitic rocks and rhyolite. $SiO_2$ contents of the volcanic rocks range from 52.0 to 78.5 wt.%. The major and trace elements composition, REE patterns and tectonomagmatic discrimination diagrams of volcanic rocks suggest that they are typical of continental margin arc calc-alkaline rocks produced in the subduction environment. The phenocrysts of the volcanic rocks show that they had gone in disequilibrium state, such as reversal zoning and resorbed core of plagioclase, reaction rim around pyroxene and resorbed margins of quartz, which showing the evidence of magma mixing during the evolution of magma.

• Journal of the Korean GEO-environmental Society
• /
• v.3 no.1
• /
• pp.67-77
• /
• 2002

Volume change of the dredged soils is composed of the volume loss of soil particle flowing over an outflow weir with water and settlement due to both the self-weight consolidation in reclaimed layer and the desiccation at the surface of reclaimed layer. In order to estimate the amount of soil particles flowing over an outflow weir with water, the evaluation procedure of loss ratio of the dredged soils is proposed in the present study based on the Marsal's modified breakage theory and the results of hydrometer analyses. To verify a validity of the proposed procedure, evaluated loss ratio is compared with results from the other existing methods. The model test results and those of field test were compared and analyzed. Also, the variation of soil loss ratio was examined through the model test in the lab.

• Journal of the Korean Geophysical Society
• /
• v.8 no.3
• /
• pp.131-135
• /
• 2005

A maximum of 3 km thickness of sediments were deposited above basement deformed by volcanic activities around the Dok Island. As the geological structure, the tension caused the basement-involved normal faults in the early stage of basin formation, whereas the sediment layers showed normal faults, volcanic domes and sills caused by volcanic activities. From the distribution of volcanics in order of age at the Ulleung Basin, volcanic activities were increased toward the northeastern direction(toward Dok Island). The study area is characterized by extensional crustal deformation before sediment deposition during the Early or Middle Miocene age. After the Late Miocene age, the basin was deformed by deep buried volcanics or subsidence of basin, in consequence, became complex geological structures.

• The Journal of Engineering Geology
• /
• v.10 no.2
• /
• pp.98-112
• /
• 2000

Discrimination between natural earthquakes and man-made explosions is very essential but critical matter in Seismology. In the CTBT Monitoring business, this is very crucial issue and sometimes could occur the international conflict. In this study, we analyzed seismic and infrasound data from Chulwon Seismo-Acoustic Array and would like to introduce routine data processing procedures at the Korea Institute of Geology, Mining and Materials(KIGAM) to discriminate the earthquakes and artificial explosions. We found analyzing acoustic data together with seismic data is very effective way to identify and discriminate man made explosion from natural earthquake. Recent earthquakes in and around the Korean Peninsula are concentrated in a narrow zone with N60-70$^{\circ}$W in southern Korea, and Pyungan and Hwanghae Province in northern Korea. The mechanism of 14 larger earthquakes in and around the Korean Peninsula since 1936 show predominant strike-slip faulting together with minor thrust component. This indicates horizontal compression is dominant in and around the Korean Peninsula.

• Water for future
• /
• v.27 no.1
• /
• pp.123-131
• /
• 1994

A plunge pool is often employed as an energy-dissipating device at the end of a spillway or a pipe culvert. A jet from spillways or pipes frequently generates a scour hole which threatens the stability of the hydraulic structure. Existing scour prediction formulas of plunge pool of spillways or pipe culverts give a wide range of scour depths, and it is, therefore, difficult to accurately predict those scour depths. In this study, a new experimental method and new scour prediction formulas under submerged circular jet for large bed materials with shallow tailwater depths were developed. A major variale, which was not used in previous scour prediction equations, was the ratio of jet size to bed material size. In this study, jet momentum acting on a bed particle and jet diffustion theory were employed to derive scour prediction formulas. Four theoretical formulas were suggested for the two regions of jet diffusion, i.e., the region of flow establishment and the region of established flow. The semi-theoretically developed scour prediction formulas showed close agreement with laboratory experiments performed on a movable bed made of large spherical particles.