• Economic and Environmental Geology
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• v.39 no.2 s.177
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• pp.111-128
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• 2006

Three dimensional crustal structure and source features of earthquake hypocenters on the Korean peninsula were investigated using P and S-wave travel time tomography. The main goal of this research was to find Vp/Vs anomalies at earthquake hypocenters as well as those of crustal structure of basins and deep tectonic settings. This allowed fer the extrapolation of more detailed seismotectonic force from the Korean peninsula. The earthquake hypocenters were found to have high Vp/Vs ratio discrepancies (VRD) at the vertical sections. High V/p/Vs ratios were also found in the sedimentary basins and beneath the Chugaryong Rift Zone (CRZ), which was due to mantle plume that subsequently solidified with many fractures and faults which were saturated with connate water. The hypocenters of most earthquakes were found in the upper crust for Youngwol (YE), Kyongju (KE), Hongsung (HE), Kaesong (KSE), Daekwan (DKE), and Daehung (DHE) earthquakes, but near the subcrust or the Moho Discontinuity for Mt. Songni (SE), Sariwon (SRE) and Mt. Jiri (JE) earthquakes. Especially, we found hot springs of the Daekwan, Daehung and Unsan regions coincide with high VRD. Also, this cannot rule out the possibility that there are some partial meltings in the subcrust of this region. High VRD might indicate that many faults and fractures with connate water were dehydrated when earthquakes took place, reducing shear modulus in the hypocenter areas. This is can be explained by due to the fact that a point source which is represented by the moment tensor that may involve changes in volume, shear fracture, and rigidity. High Vp/Vs ratio discrepancies (VRD) were also found beneath Mt. Backdu beneath 40 km, indicating that magma chamber existed beneath Mt. Backdu is reducing shear modulus of S-wave velocity.

• Economic and Environmental Geology
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• v.3 no.1
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• pp.25-34
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• 1970

Very few articles are available on geologic structure and genesis of Sangdong scheelite-deposits in spite of the fact that the mine is one of the leading tungsten producer in the world. Sangdong scheelite deposits, embedded in Myobong slate of Cambrian age at the southem limb of the Hambaek syncline which strikes $N70{\sim}80^{\circ}W$ and dips $15{\sim}30^{\circ}$ northeast, comprise six parallel veins in coincide with the bedding plane of Myobong formation, namely four footwall veins, a main vein, and a hangingwall vein. Four footwall veins are discontinuous and diminish both directions in short distance and were worked at near surface in old time. Hangingwall vein is emplaced in brecciated zone in contact plane of Myobong slate and overlying Pungchon limestone bed of Cambrian age and has not been worked until recent. The main vein, presently working, continues more than 1,500 m in both strike and dip sides and has a thickness varying 3.5 to 5 m. Characteristic is the distinct zonal arrangement of the main vein along strike side which gives a clue to the genesis of the deposits. The zones symmetrically arranged in both sides from center are, in order of center to both margins, muscovite-biotite-quartz zone, biotite-hornblende-quartz zone and garnet-diopside zone. The zones grade into each other with no boundary, and minable part of the vein streches in the former two zones extending roughly 1,000 m in strike side and over 1,100 m in dip side to which mining is underway at present. The quartz in both muscovite-biotite-quartz and biotite-hornblende-quartz zones is not network type of later intrusion, but the primary constituent of the special type of rock that forms the main vein. The minable zone has been enriched several times by numerous quartz veins along post-mineral fractures in the vein which carry scheelite, molybdenite, bismuthinite, fluorite and other sulfide minerals. These quartz veins varying from few centimeter to few tens of centimeter in width are roughly parallel to the main vein although few of them are diagonal, and distributed in rich zones not beyond the vein into both walls and garnet-diopside zone. Ore grade ranges from 1.5~2.5% $WO_3$ in center zone to less than 0.5% in garnet-diopside zone at margin, biotite-hornblende-quartz zone being inbetween in garde. The grade is, in general, proportional to the content of primary quartz. Judging from regional structure in mid-central parts of South Korea, Hambaek syncline was formed by the disturbance at the end of Triassic period with which bedding thrust and accompanied feather cracks in footwall side were created in Myobong slate and brecciated zone in contact plane between Myobong slate and Pungchon limestone. These fractures acted as a pathway of hot solution from interior which was in turn differentiated in situ to form deposit of the main vein with zonal arrangement. The footwall veins were developed along feather cracks accompanied with the main thrust by intrusion of biotite-hornblende-quartz vein and the hangingwall vein in shear zone along contact plane by replacement. The main vein thus formed was enriched at later stage by hydrothermal solutions now represented by quartz veins. The main mineralization and subsequent hydrothermal enrichments had probably taken place in post-Triassic to pre-Cretaceous periods. The veins were slightly displaced by post-mineral faults which cross diagonally the vein. This hypothesis differs from those done by previous workers who postulated that the deposits were formed by pyrometasomatic to contact replacement of the intercalated thin limestone bed in Myobong slate at the end of Cretaceous period.

• Korean Journal of Agricultural and Forest Meteorology
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• v.11 no.4
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• pp.192-205
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• 2009

The unexpected wind over the Mt. Hwawang on 9 February 2009 was deadly when many spectators were watching a traditional event to burn dried grasses and the fire went out of control due to the wind. We analyzed the fatal wind based on wind flow simulations over a digitized complex terrain of the mountain with a localized heating area using a three dimensional computational fluid dynamics model, CFD_NIMR_SNU (Computational Fluid Dynamics_National Institute of Meteorological Research_Seoul National University). Three levels of fire intensity were simulated: no fire, $300^{\circ}C$ and $600^{\circ}C$ of surface temperature at the site on fire. The surface heat accelerated vertical wind speed by as much as $0.7\;m\;s^{-1}$ (for $300^{\circ}C$) and $1.1\;m\;s^{-1}$ (for $600^{\circ}C$) at the center of the fire. Turbulent kinetic energy was increased by the heat itself and by the increased mechanical force, which in turn was generated by the thermal convection. The heating together with the complex terrain and strong boundary wind induced the unexpected high wind conditions with turbulence at the mountain. The CFD_NIMR_SNU model provided valuable analysis data to understand the consequences of the fatal mountain fire. It is suggested that the place of fire was calm at the time of the fire setting due to the elevated terrain of the windward side. The suppression of wind was easily reversed when there was fire, which caused updraft of hot air by the fire and the strong boundary wind. The strong boundary wind in conjunction with the fire event caused the strong turbulence, resulting in many fire casualties. The model can be utilized in turbulence forecasting over a small area due to surface fire in conjunction with a mesoscale weather model to help fire prevention at the field.

• Journal of Korea Entertainment Industry Association
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• v.13 no.7
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• pp.307-319
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• 2019

This study aims to provide the basic materials for the development of leisure and tourism contents in connection with Osaek cableway for the revitalization of Osaek District. For such a purpose, the following policy directions were presented through the analysis of the present situation and conditions of Osaek District, the direction of development of leisure and tourism contents of Osaek District, etc. The first is increasing the participation of local residents and reinforcing their capabilities. The suggested promotion plans are ① establishing organizational system and strengthening support, ② reinforcing the capabilities of local residents and ③ constructing networks with external human resources. The second is setting the guidelines for contents development. It was proposed to prepare contents for leisure experience using the natural environment of Osaek District in response to the trend of increase of people who enjoy "contents using culture and arts" and leisure. The third is typological approach to contents. It was proposed to develop cultural contents with the theme of Osaek such as "Osaek Light Festival", "Osaek Concert", "Osaek Photo Exhibition" and "Osaek Good Men and Women Contest" for the promotion of the brand of the place name of Osaek and the creation of the "Picture Book Village" for the compilation of the history and culture of Osaek District with pictures. The fourth is securing marketing channels. For this, it was proposed to produce the website of Yangyang County or a website tentatively named as "Osaek-ri with Beautiful Osaek" and introduce an integrated travel product (transportation + lodging + foods + experience (hot spring, mineral water therapy, leisure experience, etc.) + purchasing local specialty products, etc.) composed of the leisure and tourism contents, transportation, lodging, foods, etc. of Osaek District through travel agencies. The final policy direction presented was phased implementation of the development and operation of the contents. Proposed policies include support of a consulting project to upgrade the organization of local residents; implementation of "Tourism Dure (Cooperative)" project for the solution of the problem of tourism in Osaek District by the residents themselves together using the space of culture and arts made by remodeling idle public and private facilities after benchmarking exemplary places; system improvement for the introduction of leisure and tourism contents appropriate for local conditions; and the establishment of a master plan for the introduction of various leisure and tourism contents in Osaek District.

• Journal of the Korean Geographical Society
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• v.38 no.2
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• pp.312-323
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• 2003

This writer absolutely agrees with the government that regional disequilibrium is severe enough to consider moving the administrative capital. Pursuing this course solely to establish a balanced development, however, is not a convincing enough reason. The capital city is directly related to not only the social and economic situation but, much more importantly, to the domestic political situation as well. In the mid-1970s, the proposal by the Third Republic to move the capital city temporarily was based completely on security reasons. At e time, the then opposition leader Kim, Dae-jung said that establishing a safe distance from the demilitarized zone(DMZ) reflected a typically military decision. His view was that retaining the capital city close to the DMZ would show more consideration for the will of the people to defend their own country. In fact, independent Pakistan moved its capital city from Karachi to Islamabad, situated dose to Kashmir the subject of hot territorial dispute with India. It is regrettable that no consideration has been given to the urgent political situation in the Korean peninsula, which is presently enveloped in a dense nuclear fog. As a person requires health to pursue his/her dream, a country must have security to implement a balanced territorial development. According to current urban theories, the fate of a country depends on its major cities. A negligently guarded capital city runs the risk of becoming hostage and bringing ruin to the whole country. In this vein, North Koreas undoubted main target of attack in the armed communist reunification of Korea is Seoul. For the preservation of our state, therefore, it is only right that Seoul must be shielded to prevent becoming hostage to North Korea. The location of the US Armed Forces to the north of the capital city is based on the judgment that defense of Seoul is of absolute importance. At the same time, regardless of their different standpoints, South and North Korea agree that division of the Korean people into two separate countries is abnormal. Reunification, which so far has defied all predictions, may be realized earlier than anyone expects. The day of reunification seems to be the best day for the relocation of the capital city. Building a proper capital city would take at least twenty years, and a capital city cannot be dragged from one place to another. On the day of a free and democratic reunification, a national agreement will be reached naturally to find a nationally symbolic city as in Brazil or Australia. Even if security does not pose a problem, the governments way of thinking would not greatly contribute to the balanced development of the country. The Chungcheon region, which is earmarked as the new location of the capital city, has been the greatest beneficiary of its proximity to the capital region. Not being a disadvantaged region, locating the capital city there would not help alleviate regional disparity. If it is absolutely necessary to find a candidate region at present, considering security, balanced regional development and post-reunification scenario of the future, Cheolwon area located in the middle of the Korean peninsula may be a plausible choice. Even if the transfer of capital is delayed in consideration of the present political conflict between the South and the North Koreas, there is a definite shortcut to realizing a balanced regional development. It can be found not in the geographical dispersal of the central government, but in the decentralization of power to the provinces. If the government has surplus money to build a new symbolic capital city, it is only right that it should improve, for instance, the quality of drinking water which now everyone eschews, and to help the regional subway authority whose chronic deficit state resoled in a recent disastrous accident. And it is proper to time the transfer of capital city to coincide with that of the reunification of Korea whenever Providence intends.