• School Mathematics
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• v.18 no.1
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• pp.143-157
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• 2016

North Korea had been reorganized its educational curriculum and new contexts were authored in 2013. In this study, mathematics contexts of North Korean secondary school's first grade in 2009 and 2013 were investigated. And the changes of content structure, content development, and content composition were analyzed. Results were as follows: First, with respect to the content structure, 1 chapter decreased, while lesson number was intact and 4 subunits increased. Second, with respect to the content development, considerable changes were presented. The tendencies that encouraged student and pursued a student friendly form were investigated. Third, with respect to the content composition, obvious changes were presented. It was investigated that the ratio of numbers and number operations, letters and expressions decreased nearly half. And new contents were supplemented in the areas of patterns, geometry, functions, probability and statics, equation of figures, set and statement. This changes suggests that differences between contexts of South and North Korea is narrowing compared to the past. In conclusion, the direction of North Korean mathematical education is changing for the general direction of South Korean mathematical education.

• Journal of Astronomy and Space Sciences
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• v.29 no.3
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• pp.269-274
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• 2012

Kinematic global positioning system precise point positioning (GPS PPP) technology is widely used to the several area such as monitoring of crustal movement and precise orbit determination (POD) using the dual-frequency GPS observations. In this study we developed a kinematic PPP technology and applied 3-pass (forward/backward/forward) filter for the stabilization of the initial state of the parameters to be estimated. For verification of results, we obtained GPS data sets from six international GPS reference stations (ALGO, AMC2, BJFS, GRAZ, IENG and TSKB) and processed in daily basis by using the developed software. As a result, the mean position errors by kinematic PPP showed 0.51 cm in the east-west direction, 0.31 cm in the north-south direction and 1.02 cm in the up-down direction. The root mean square values produced from them were 1.59 cm for the east-west component, 1.26 cm for the south-west component and 2.95 cm for the up-down component.

• 한국지구물리탐사학회:학술대회논문집
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• 2004.06a
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• pp.54-62
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• 2004

According to the Korea Tectonic Map, the Korean Peninsula can be divided into seven tectonic units and each of them shows a peculiar deformation pattern. In order to estimate an amount of crustal deformation in the Korean peninsula, we obtained the velocity vector fields of South Korea by dealing with the data set of the years 2001 and 2002, measured from the permanent GPS stations across the country To obtain a relatively precise coordinate of each station, we used GAMIT that is a comprehensive GPS analysis package developed at MIT, Then, a Kalman filter called GLOBK is used to combine the results from GAMIT and to estimate the relative velocity vector for the crustal deformations. The crustal movement of South Korea is turned out to be about 1mm per year westward and about 0.6mm per year southward. In case of Suwon and Seosan(Gyeonggi Massif), the movement occurs slightly to the north-east direction. The movement of a relative velocity field in the tectonic unit is unidirectional, yet the magnitude of the velocity is very small.

• Economic and Environmental Geology
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• v.18 no.1
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• pp.23-39
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• 1985

The northeastern part of Ogcheon zone which consisted mainly of Cambro-Ordovician arenaceous, argillaceous and calcareous formations and Carboni-Triassic arenaceous and argillaceous formations is delineated as the eastern mass of a thrust fault along Choongju-Moongyong-Cheongsan in the middle of the zone. The present study proposes a geotectonic line, Imgye-Samchog fault(see, figure 1) which divides the northeastern part into two blocks, Hambacksan block in the west and East coast block in the east. The igneous rocks in the Hambacksan block ranging from granite to gabbro are distributed in a symmetrical zones parallel to general direction of Ogcheon zone as follows (Fig. 2 and Table 2). Southeast igneous rock zone: it aligns Jurassic granites in its south and Precambrian leucocratic granites in its north. Central igneous rock zone: it aligns Cretaceous granites in its south and Jurassic granites, and some of diorite and gabbro in its north. Northwest igneous rock zone: aligns Jurassic granites in its south and huge batholithic granodiorite in its north. The distribution of the igneous rocks in the East coast block shows an entirely different features from those of Hanbacksan block. In the southern part of the block they assemble in a narrow area ranging in age from Early Proterozoic, through Middle to Late Proterozoic, Devonian, Jurassic, Cretaceous to Tertiary, whereas, the igneous rocks in the northern part of the block gathered to a restricted area, in ages of Middle Proterozoic and Cretaceous. The assemblage of the igneous rocks in the studied area shows a compositionally restricted, mixed S-type and I-type granites, $^{87}Sr/^{86}Sr$ > 0.706, rare volcanics and shortening with upright folding. These lithologic and structural features suggest that the igneous activity in this part related intimately to Hercynotype Orogeny of Pitcher(1979). Chronological episodes of igneous activity from Early Proterozoic to Early Tertiary in the northeastern part are figured.

• Strategy21
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• s.30
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• pp.99-142
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• 2012

Withe increased North Korea's security threats, the South Korean navy has been faced with deteriorating security environment. While North Korea has increased asymmetric forces in the maritime and underwater with the development of nuclear weapons, and China and Japan have made a large investment in the buildup of naval forces, the power of the Pacific fleet of the US, a key ally is expected to be weakened. The biggest threat comes from China's intervention in case of full-scale war with North Korea, but low-density conflict issues are also serious problems. North Korea has violated the Armistice Agreement 2,660 times since the end of Korean War, among which the number of marine provocations reaches 1,430 times, and the tension over the NLL issue has been intensifying. With tension mounting between Korea and Japan over the Dokdo issue and conflict escalating with China over Ieo do Islet, the US Navy has confronted situation where it cannot fully concentrate on the security of the Korean peninsula, which leads to need for strengthening of South Korea's naval forces. Let's look at naval forces of neighboring countries. North Korea is threatening South Korean navy with its increased asymmetric forces, including submarines. China has achieved the remarkable development of naval forces since the promotion of 3-step plan to strengthen naval power from 1989, and it now retains highly modernized naval forces. Japan makes an investment in the construction of stat of the art warship every year. Since Japan's warship boasts of its advanced performance, Japan's Maritime Self Defense Force is evaluated the second most powerful behind the US Navy on the assumption that submarine power is not included in the naval forces. In this situation, naval power construction of South Korean navy should be done in phases, focusing on the followings; First, military strength to repel the energy warship quickly without any damage in case of battle with North Korea needs to be secured. Second, it is necessary to develop abilities to discourage the use of nuclear weapons of North Korea and attack its nuclear facilities in case of emergency. Third, construction of military power to suppress armed provocations from China and Japan is required. Based on the above naval power construction methods, the direction of power construction is suggested as follows. The sea fleet needs to build up its war potential to defeat the naval forces of North Korea quickly and participate in anti-submarine operations in response to North Korea's provocations. The task fleet should be composed of 3 task flotilla and retain the power to support the sea fleet and suppress the occurrence of maritime disputes with neighboring countries. In addition, it is necessary to expand submarine power, a high value power asset in preparation for establishment of submarine headquarters in 2015, develop anti-submarine helicopter and load SLAM-ER missile onto P-3C patrol aircraft. In case of maine corps, division class military force should be able to conduct landing operations. It takes more than 10 years to construct a new warship. Accordingly, it is necessary to establish plans for naval power construction carefully in consideration of reality and future. For the naval forces to safeguard maritime sovereignty and contribute to national security, the acquisition of a huge budget and buildup of military power is required. In this regard, enhancement of naval power can be achieved only through national, political and military understanding and agreement. It is necessary to let the nation know that modern naval forces with improved weapon system can serve as comprehensive armed forces to secure the command of the sea, perform defense of territory and territorial sky and attack the enemy's strategic facilities and budget inputted in the naval forces is the essential source for early end of the war and minimization of damage to the people. If the naval power construction is not realized, we can be faced with a national disgrace of usurpation of national sovereignty of 100 years ago. Accordingly, the strengthening of naval forces must be realized.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.247-252
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• 2002

It is expected to confront numerous technological advancements in ter railroad technology with an opening of state-of-art Kyung-Bu High Speed Railroad that permits traveling speed in excess of 300 Km/hr. Expansions of railroad facility such as revival of silk railroad in Eurasia due to the connection of South-North Korea and modernization of rolling stock and ancillary equipment have certainly contributed to the technological development of Korean Railroad. Such technological advancements will provide of opportunities to participate in foreign projects that have been offered in past years. Thus, a comprehensive plan and R＆D policy is necessary to continuously raise and upgrade national competitiveness in the railroad industry.

• Journal of the Korean earth science society
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• v.39 no.5
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• pp.473-482
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• 2018

During the period of 2002 to 2017, the Gravity Recovery And Climate Experiment (GRACE) had observed time-varying gravity changes with unprecedented accuracy. The GRACE science data centers provide the monthly gravity solutions after removing the sub-monthly mass fluctuation using geophysical models. However, model misfit makes the solutions to be contaminated by aliasing errors, which exhibits peculiar north-south stripes. Two conventional filters are used to reduce the errors, but signals with similar spatial patterns to the errors are also removed during the filtering procedure. This would be particularly problematic for estimating the ice mass changes in Western Antarctic Ice Sheet (WAIS) and Antarctic Peninsula (AP) due to their similar spatial pattern to the elongated north-south direction. In this study, we introduce an alternative filter to remove aliasing errors using the Empirical Orthogonal Functions (EOF) analysis. EOF can decompose data into different modes, and thus is useful to separate signals from noise. Therefore, the aliasing errors are effectively suppressed through EOF method. In particular, the month-to-month mass changes in WAIS and AP, which have been significantly contaminated by aliasing errors, can be recovered using EOF method.

• Convergence Security Journal
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• v.15 no.6_1
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• pp.79-92
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• 2015

It is required to expand area of inter-Korean economic cooperation, being limited to non-military field, to military field and then, to positively promote arms control in order to establish foundation for peaceful reunification in Korean peninsula. Reasons why arms control has not been promoted between South and North Korea in the meantime were such original factors as follows; (1) limit of confidence building between the South and the North, (2) functional limit of arms control itself, (3) institutional structural limit between the South and the North, (4) environmental limit at home and abroad. It is necessary to get out from existing frame and to seek a new paradigm in order to overcome above factors and to realize arms control between the South and the North. First, it is required to have prior political dialog at the South-North high-level talks in order to promote arms control and to exercise 'strategic flexibility' during negotiation and promotion process. For this, 'flexible reciprocity' has to be adopted in compliance with situation and conditions. Second, it is necessary to get out from existing principle of 'confidence building in advance and arms reduction later' but to seek the 'simultaneous driving principle of confidence building and arms reduction' as an eclectic approach. Namely, based on reasonable sufficiency, it is required to promote military confidence building and limited arms reduction in parallel, which is a lower level of arms control. Third, as an advisory body of Prime Minister's Office, it is necessary to install an organization exclusively responsible for arms control and to positively handle arms control issue from the standpoint of national policy strategy. If the South-North high-level talks take place, it is necessary to organize and operate 'South-North Joint Arms Control Promotion Board (tentative name)'. Fourth, it is required to exercise more active diplomatic competence in order to create national consensus on necessity of arms control for peaceful reunification and to form more favorable international environment. Especially, it is necessary to think about how to solve nuclear issue of North Korea together in collaboration with international society and how to maintain balance between ROK-US alliance and Sino-Korean cooperation relations.

• Journal of the Korean earth science society
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• v.44 no.1
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• pp.1-12
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• 2023

Oceanic wind waves have been recognized as one of the important indicators of global warming and climate change. It is necessary to study the spatial and temporal variability of significant wave height (SWH) and wave direction in the Yellow Sea and a part of the East China Sea, which is directly affected by the East Asian monsoon and climate change. In this study, the spatial and temporal variability including seasonal and interannual variability of SWH and wave direction in the Yellow Sea and East China Sea were analyzed using European Center for Medium-Range Weather Forecasts (ECMWF) Reanalysis 5 (ERA5) data. Prior to analyzing the variability of SWH and wave direction using the model reanalysis, the accuracy was verified through comparison with SWH and wave direction measurements from Ieodo Ocean Science Station (I-ORS). The mean SWH ranged from 0.3 to 1.6 m, and was higher in the south than in the north and higher in the center of the Yellow Sea than in the coast. The standard deviation of the SWH also showed a pattern similar to the mean. In the Yellow Sea, SWH and wave direction showed clear seasonal variability. SWH was generally highest in winter and lowest in late spring or early summer. Due to the influence of the monsoon, the wave direction propagated mainly to the south in winter and to the north in summer. The seasonal variability of SWH showed predominant interannual variability with strong variability of annual amplitudes due to the influence of typhoons in summer.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.271-275
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• 2005

The horizontal heat-pulse flowmeter was used to measure grounwater flow in volcanic rocks at sites in eastern part of Jeju Island, Korea. Three boreholes, Handong-1, Jongdal-1, and Susan-1, which are located at close distance from the coastline, were selected from the sea water intrusion monitoring wells. To evaluate the direction and velocity of the groundwater flow, 6 to 8 measuring points for each borehole were chosen. There are two major flow directions at Handong-1, which are toward north-east and south-east directions and velocity ranges from $2.2{\sim}3.0cm/hr\;and\;0.6{\sim}1.0cm/hr$, respectively. For Jongdal-1, two major flow directions were detected that are east and north-west and velocity ranges from $1.2{\sim}2.0cm/hr$. For Susan-1, major flow is toward east direction and the ,velocity ranges from $2.2{\sim}2.7cm/hr$ at depth $60{\sim}70m$,\;and\;0.8{\sim}0.9cm/hr$ at depth $70{\sim}80m$. In order to evaluate the tidal effect on groundwater flow, direction and velocity were measured at specific depth with time, At depth 57m of Susan-1, the velocity increased during the tidal variation, The flow direction and velocity varies with different depths, and they are also affected by tidal fluctuation. Thereafter, care must be taken when flow direction and velociy is estimated indirectly by using hydraulic head at monitoring wells.