• Journal of Soil and Groundwater Environment
• /
• v.10 no.6
• /
• pp.45-55
• /
• 2005

The geothermal research has been carried out on the Heunghae, Pohang geothermal area know as having geo-heat-flow area in the Korean peninsula. This study results so far indicate that geothermal water in the area is in peripheral waters of hydrothermal area and is not in equilibrium with the reservoir rock. The average oxygen and hydrogen stable isotope values are as follows: deep groundwater $(average:\;{\delta}^{18}O=-10.1\%_{\circ},\;{\delta}D=-65.8\%_{\circ})$, intermediate groundwater (average: $(average:\;{\delta}^{18}O=-8.9\%_{\circ},\;{\delta}D=-59.6\%_{\circ})$, shallow groundwater $(average:\;{\delta}^{18}O=-8.0\%_{\circ},\;{\delta}D=-53.6\%_{\circ})$, surface water $(average:\;{\delta}^{18}O=-7.9\%_{\circ},\;{\delta}D=-53.3\%_{\circ})$ respectively. Deep groundwaters was originated from a local meteoric water recharged from distant, topographically high mountain region and not affected by the sea water. High temperature zone inferred from water geothermometers is around D-1, D-5, D-6, 1-04 well zones. The estimated enthalpy from Silica-enthalpy mixing model is near 410 kJ/kg, which corresponds to the temperature of $98^{\circ}C$, and in consistent with the result of Na-K and K-Mg geothermometer.

• Journal of Soil and Groundwater Environment
• /
• v.11 no.3
• /
• pp.20-30
• /
• 2006

Hydrogeochemistry of deep geothermal water (temperature: $42.2-47.9^{\circ}C$) at Heunghae, Pohang was evaluated using core logging, temperature and electrical conductivity (EC) logging before and after pumping tests, chemical analysis of geothermal water with depth, and observation of water quality variations during pumping tests. The geology of the area is composed of highly fractured marine sedimentary rocks. The hydrogeochemistry of geothermal water varies with drilling depth, distance from the coast, and pumping duration. According to the temperature and EC variations during 4 times of pumping tests, main aquifer of the area is considered as the fractured zones (540 to 900 m) developed in rhyolitic rocks. The high content of Na and $HCO_3$ in geothermal water can be explained by the inflow of deep groundwater from inland regulated by dissolution of silicates and carbonates. High TDS, Na and Cl concentrations indicate that the geothermal water was also strongly affected by seawater. The molar ratios of Na:Cl ($0.88{\sim}2.14$) and Br:Cl ($21.0{\sim}24.9{\times}10^{-4}$) deviate from those of seawater (0.84 and $34.7{\times}10^{-4}$, respectively), suggesting that water-rock interaction also plays an important role in the formation of water quality.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.22 no.3
• /
• pp.103-111
• /
• 2018

This study examines the seismic failure of RC low-rise building structures having irregularities at the ground story during the 15 November 2017 Pohang, Korea, earthquake, $M_w=5.4$, which is the second strongest since the government began monitoring them in 1978 in South Korea. Some 2,000 private houses were damaged or destroyed in this earthquake. Particularly, serious damage to the piloti story of RC low-rise residential building structures of fewer than five stories was observed within 3 km of the epicenter with brittle shear failure of columns and walls due to severe torsional behavior. Buildings below six stories constructed before 2005 did not have to comply with seismic design requirements, so confinement detailing of columns and walls also led to inadequate performance. However, some buildings constructed after 2005 were damaged at the flexible side of the piloti story due to the high torsional irregularity. Based on these results, this study focuses on the problems of the seismic torsion design approach in current building codes.

• Journal of architectural history
• /
• v.25 no.4
• /
• pp.31-44
• /
• 2016

Geum'yeok-dang house in Andong was originally constructed in 1558. The original floor plan of the upper base featured a 90-degree tilted '日' shape, and had inner court(內庭) on each side of 'Jungdang(中堂, center hall)' building that was placed on the south-north axis. When designing the building, the Neo-Confucian client of Geum'yeok-dang applied his understanding of how Ga'rye("家禮") defined the structure of ritual space. Consequently, 'Daecheong(大廳)', the place where guests were greeted and ancestral rites and coming of age ceremonies for male were held, was built in a protruding fashion. 'Jungdang'[otherwise known as 'Jeongchim(正寢)'], where coming of age ceremonies for females were held, the master of the house faced death, and memorials for close ancestors were held, was placed at the center of the residence on the south-north axis. The Geum'yeok-dang today was greatly renovated in the early and mid 18th century, due to the spread of 'Ondol' heating system. As the Ondol heating system became popular, the pre-existing drawbacks and the inconvenience of the house stood out clearly. As a result, the house was renovated into today's structure consisting of '口' shape 'Anchae' and 'Daecheongchae' in separate building.

• Journal of The Geomorphological Association of Korea
• /
• v.26 no.4
• /
• pp.141-145
• /
• 2019

This study investigated Quaternary sand deposits in the process of surveying Quaternary deposits distributed in Yonghan-ri, Heunghae-eup, Pohang city. Field geological surveys were conducted and OSL dating samples were taken. The altitude of the Quaternary sand deposits layer is about 15m, and there are two upper and lower sand dune layers, and a peat layer is developed between them. The sampling point are just above the peat layer, and the altitude level is about 13.4m (YHO-1) and about 13.7m (YHO-2). OSL dating was performed for YHO-1 and YHO-2 and the results were 69 ± 6 ka and 62 ± 5 ka, respectively. The date analyzed are interpreted as MIS 4. On the other hand, the formation time of the peat layer at an altitude of about 13.2 to 13.7m can be compared with the results of the OSL dating of the above sandy deposits. The peat layer can be inferred to have formed during MIS 5a or earlier.

• The Journal of Engineering Geology
• /
• v.19 no.4
• /
• pp.459-474
• /
• 2009

By the analysis of discontinuity at the outcrop and lineament on the satellite image, the joints have deeply relationship with the lineaments. The joint spaces at the drilling core are mostly 1~20 cm but at the rhyolite which is distributed near fault they have more closely. These volcanic rocks belong to the subalkaline series tuff, rhyolite, basalt in the study area from the diagram of $Nb/Y-Zr/TiO_2$. The composition diagram of Hf/3-Th-Nb/16 show destructive plate-margin basalt and their differentiates. The environment of formation of volcanics are normal continental arc. Most of LREE show high enriched pattern but HREE show depleted pattern. The K/Ar age of intermediate volcanics, tuff, rhyolite, crystal tuff are 55.3Ma, 77.25 Ma~91.22Ma, 63.16~64.39Ma, 54.49 Ma respectively.

• Geophysics and Geophysical Exploration
• /
• v.15 no.2
• /
• pp.51-56
• /
• 2012

One of the most critical and essential procedures in the interpretation of gravity and magnetic data is to separate the anomaly due to the specific geologic structure from the summation of effects from a broad variety of geologic sources, especially those of different depths. Separation of the residual anomaly from the regional field is the most simple case of the vertical separation. If the anomaly due to a layer of specific depth can be separated or the depth of the separated layer can be quantitatively determined, it may deserve the separation-sounding. We suggest a wavelength filter whose cutoff frequency is determined by log-power spectrum analysis, as a separation-sounding filter. We applied this filter both to synthetic and real gravity data acquired at Heunghae area, and compared the results with those of Jacobsen's upward continuation filter. These showed that the proposed separation-sounding filter could be a useful tool for interpretation of the vertical geologic structure by stripping the gravity effects of geologic sources down to the desired depth.

• Journal of Aquaculture
• /
• v.11 no.4
• /
• pp.581-592
• /
• 1998

To know on the distribution and ecological characteristics of genus Corbicula field survey made from August 1997 to July 1998 in the North Kyungsang Province. Three species, i.e. Corbicula japonica, C. leand and C. papyracea, were inhabited in the North Kyungsang Provice. C. japonica was dioecious and oviparous species and C. leana and C. papyracea were monoecious and viviparous species.

• Journal of the Korean Geotechnical Society
• /
• v.36 no.9
• /
• pp.5-20
• /
• 2020

In 2017, after the Pohang earthquake, liquefaction phenomena were firstly observed after the observation of domestic earthquake by epicenter. In this study, various in-situ tests and laboratory tests were performed to determine the dynamic properties in (1) Songlim Park, (2) Heunghae-eup, Mangcheon-ri and (3) Heungan-ri, Pohang. As a site investigation, the standard penetration test (SPT), cone penetration test (CPT), multichannel analysis of surface wave (MASW), density logging, downhole test, and electrical resistivity survey were performed. In addition, cyclic triaxial test against sampled sand from site was also conducted. Based on the result, high ground water level and loose sand layer in shallow depth were observed for all sites. In addition, liquefaction resistance ratio of soil sampled from Songlim park was lower than those of Jumunjin sand, Toyoura sand, and Ottawa sand.

• Journal of the Korean earth science society
• /
• v.43 no.1
• /
• pp.188-198
• /
• 2022

Some deep faults do not reach the ground surface and are seldom recognized. Gokgang Fault area in the east of the Heunghae area of the Pohang basin has been selected to confirm the feasibility of the Horizontal-to-Vertical Spectral Ratio (HVSR) approach to identify blind faults. Densely spaced microtremor data have been acquired along two lines in the study area and processed to obtain resonance frequencies. An empirical relationship between the resonance frequency and the bedrock depth was proposed using borehole data available in the study area. Resonance frequencies along two lines were then converted to bedrock depths. The resulting depth profiles show significant lateral variations in the bedrock depth. As expected, considerable variation in the resonance frequency is observed near the Gokgang fault. The depth profiles also present additional significant variations in the resonance frequencies and the bedrock depths. The feature is presumably related to a blind fault that is previously unknown. Therefore, this case study confirms the feasibility of the HVSR technique to identify faults otherwise not recognized on the surface.