• The KSFM Journal of Fluid Machinery
• /
• v.18 no.6
• /
• pp.63-70
• /
• 2015

This paper proposes a novel airfoil named "KA2" for the blade of the wind turbine systems. Dynamic loads characteristics are analyzed and compared using aerodynamic data of ten airfoils including the proposed airfoil. The blade is divided into the sixteen elements in the longitudinal direction of the blade for applying the Blade Element Method Theory (BEMT) method, and in each element, torque, thrust, and pitching moment are calculated using turbulent time varying wind speed and aerodynamic data of each wing. Additionally, each force and torque is accumulated in the whole region of the blade for the estimation of representative values. The magnitude of such forces is comparatively analyzed for different airfoils. The angle of attack is constant below the rated wind speed due to the fact that the tip speed ratio is kept at the constant value, and it increases in the region of over rated wind speed as the tip speed ratio decreasing with constant rated rpm and increasing wind speed. Such increase in the angle of attack causes the changes of the force acting on the airfoil with different characteristics of lift and drag in the stall region of each different airfoil. Even though the mean wind speed is in the rated speed in a given time, because of the turbulence, it has either the over rated or under rated speed most of the time. Furthermore, the dynamic properties of each force are analyzed in this rated wind speed in order to objectively understand the dynamic properties of the blades which are designed based on the different airfoils. These dynamic properties are also compared by the standard deviation of time varying characteristics. Moreover, the output characteristics of the wind turbine are investigated with different airfoils and wind speeds. Based on these investigations, it was revealed that the proposed airfoil (KA2) is well applicable to the blade with passive pitch control system.

• Journal of the Economic Geographical Society of Korea
• /
• v.1 no.1
• /
• pp.57-74
• /
• 1998

Recently. the interest in Physical distribution has increased in economic geography This paper aims to review and prospect the internatonal physical distribution studies of international trade and international freight flows. And it has examined the changes in methodology of international physical distribution. Author has defined international physical distribution as the physical distribution of international trade and international freight flow The results are as follows : (1) As the methodology of international physical distribution studies developes, the physical distribution should be recognized not only as transportation phenomenon but also as total logistics which is understood as the combination of production and consumption including information flow. (2) The studies about model of international physical distribution flow ill need to study regional relations including urban, in the future. And economic geography and location theory adding culture and behaviour elements will be restructured, because not only state but also multinational corporation appear as trade subject in global economy. (3) The studies for the relation of habor and its hinterland in Physical distribution need to analyze the factors causing habor use with decision-making behaviour of corporation. (4) After oil crisis. as air freight is important, the studies for hinterland and foreland of freight centering international airport are needed because of necessity of light and small freight. flexible Production system, free trade, and high speed freight transportation of freshing food and flowers and so forth.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.16 no.4
• /
• pp.403-415
• /
• 2014

Recently, the temperature rise in the summer due to climate change, power usage is increasing rapidly. As a result, power generation facilities have been newly completed and the need for ultra-high-voltage transmission line for power transmission of electricity to the urban area has increased. The mechanized tunnelling method using a shield TBM have an advantage that it can minimize vibrations transmitted to the ground and ground subsidence as compared with the conventional tunnelling method. Despite the popularity of shield TBM for cable tunnel construction, study on the mechanical behavior of cable tunnel driven by shield TBM is insufficient. Thus, in this study, the effect of fractured zone ahead of tunnel face on the mechanical behavior of the shield TBM cable tunnel is investigated. In addition, it is intended to compare the behavior characteristics of the fractured zone with continuous model and applying the interface elements. Tunnelling with shield TBM is simulated using 3D FEM. According to the change of the direction and magnitude of the fractured zone, Sectional forces such as axial force, shear force and bending moment are monitored and vertical displacement at the ground surface is measured. Based on the stability analysis with the results obtained from the numerical analysis, it is possible to predict fractured zone ahead of the shield TBM and ensure the stability of the tunnel structure.

• Geophysics and Geophysical Exploration
• /
• v.11 no.2
• /
• pp.93-98
• /
• 2008

Abstract: Surface topography has a significant influence on seismic wave propagation in a reflection seismic exploration. Effects of surface topography on two-dimensional elastic wave propagation are investigated through modeling using a weighted-averaging (WA) finite-element method (FEM), which is computationally more efficient than conventional FEM. Effects of air layer on wave propagation are also investigated using flat surface models with and without air. To validate our scheme in modeling including topography, we compare WA FEM results for irregular topographic models against those derived from conventional FEM using one set of rectangular elements. For the irregular surface topography models, elastic wave propagation is simulated to show that breaks in slope act as a new source for diffracted waves, and that Rayleigh waves are more seriously distorted by surface topography than P-waves.

• Journal of architectural history
• /
• v.3 no.1
• /
• pp.57-82
• /
• 1994

This paper is the result of the researches and the field surveys of the villages and the dwellings of Korean immigrants in Yien-Pien area, north-eastern China. This study aims to persue both of the origin and the process of development of their settlements and dwelling types from late 19C to the present. Their processes are too complex to analysis by single view-point. I have eyes to interprete them from three pionts; 1)correspondences between the dwelling types and the econo-political history of their region, 2)cultural assimilation with the native dwelling types, and 3)the direction of their modernization with the economical development of modern China. Three village types have been pioneered; 1)the villages of indivisual immigration, 2)the villages of planned group immigration, and 3)the villages of socilistic reform villages of 1) were composed of organic village patterns and various shaped dwelling lots on the sloped site; villages both of 2) and 3), gird patterns and uniformed lots on open fields. Historically, villages of 1) were pioneered before 1931; villages of 2), 1936-1945; villages of 3), from 1945. Each of dwelling types had strong relations with the village types to which it belonged. Before 1931, dwellings were built up based on so called "Ham-buk dwelling type" which was dominent in north-eastern Korea. In the era of gruop-immigration, various dwelling types were flew into Yen-Pien from southern Korea. In modern China, their southern types were changed into Yen-Pien type as similar as Ham-book type. After 1945, with the Great leap Forward and the Cultural Revolution, as communization of indivisual properties and reorganization of rural communities, each of dwellings became smaller and simpler in aspects of scales as well as functions. There are two types in Yen-Pien dwellings, those are 'single-file' and 'double-file' type. Three sub-types of latter arc 'six-bays', 'eight-bays', and rarely 'ten-bays'. The most common element of all types is Chong-ju-k'an; which is large room with heated floor, openig to kitchen. Now, modern dwellings of Korean immigrants are changing their spatial compositions, materials, and structures. With cultural assimilation as well as modernization, especially in urban areas, they are compelled to accept the elements of Chinese dwellings. But the spatial element of "Chong-ju-k'an", which is the core element of Yen-Pien dwelling type, never fade away nor is changed.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.27 no.6
• /
• pp.741-747
• /
• 2009

For construction of 3D virtual city models, airborne digital cameras, laser scanners, multi-oblique photograph systems and other devices are currently being used. With such advanced techniques, precise 3D spatial information can be collected and high quality 3D city models can be built in a considerably large area. The 3D spatial information to be built has to provide the latest information that quickly reflects the causes of any change due to urban development. In this study, a UAV photogrammetric method using low cost UAV and digital camera was proposed to acquire and update 3D spatial information effectively on small areas where information continuously change. In the proposed UAV photogrammetric method, the elements of interior orientation were acquired through camera calibration and the vertical and oblique photographs were taken at 9 points and the 3D drawing of ground control points and buildings was performed using 20 images among the pictured images. This study also analyzed the accuracy of the proposed method comparing with ground survey data and digital map in order to examine whether the method can be used in on-demand 3D spatial information update on relatively small areas.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.17 no.1
• /
• pp.215-233
• /
• 2014

Seoul is an ancient city with a long history but there is hesitancy over referring to as a historic city due to the lack of traceable historic urban landscape elements which resulted from numerous invasions and general destruction. From a diachronic perspective, the nature which was survived the influence of development, could be the key element that links the past with the city's radically changed image in modern times. Although "old big trees" may be not a dominant influence with regards to the historical authenticity of the city, they are objects which contribute towards the historical authenticity by providing a sense of place in terms of connected narratives, as well as their natural image. However, the protection policy for an "old big tree" would place too much emphasis on the aspect of the ecological value rather than its cultural value. Generally, trees have been protected by installing a fence and a signboard around them as well as receiving additional care. However, it is difficult to find that surrounding space around the "law-protected tree" is connected with its original historical and cultural values. Even though the space around trees are no longer utilized in the same way as was so in the past, they still have high-potential in terms of cultural utilization. Therefore, the subject of this study is the "old big tree" as a natural object which contributed to the historical authenticity of Seoul. The current status of these "old big trees", aged between 100 and 800 years old, currently indicate that there are 215 trees designated as "law-protected tree" by the Seoul metropolitan government. This study aims to investigate the status of protection and utilization of the existing "law-protected trees" in the city of Seoul and find a way to increase both ecological preservation and cultural utilization for the high-potential "law-protected trees" within the city itself. In order to achieve this, previously researched papers shall be reviewed and surveyed pertaining to present usage patterns of the 215 "law-protected trees". In addition, five cases have been reviewed which focus on a few of utilizing the "protected trees" and their surrounding spaces. The results of the research indicate that 21 "old big trees" have high-potential in terms of cultural utilization as well as ecological value. However, it was revealed that there are limitations to pursue the value of preservation and utilization simultaneously throughout current regimental management. In order to cope with the current situation, it is pointed out that management facilities should be designed and installed by creative and flexible methods of organizing with consideration to the surrounding space and context. Even though in the case where there may not be a connecting history or legendary stories, the "old big trees" can serve as the fundamental features of small scale parks -dependent on their location, condition and environment- which will be of value to the local communities. This study could serve as a practical reference for the management and utilization of "old big trees" nationwide with numbers reaching 12,300 besides the city of Seoul.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.18 no.6
• /
• pp.22-30
• /
• 2004

It is an attempt to suggest the standard valuation method of the environmental illumination for the bridges across the Han-river from an aesthetic point of view, deviating from the technical and traditional viewpoint. In Korea the current evaluation criterion to verify the value of bridge design has a partiality for the technical and structural safety rather than the sentient beauty on the whole. However, the recently cultural reform of Korean mass society with the elevation of the standard of living forces the engineering designers for bridges to focus not only on competing physical structures but also on enhancing the formative beauty including the illumination effects for night view. Additionally, the new policy, which transforms the environments around the Han-river into the major tourist attractions has been executing strongly by the city authorities to revitalize the symbolic, historic, and cultural identity of the capital city with the introduction of the high-quality environmental illumination for the bridges. As a result, It becomes necessary to establish the manual and standardization of the environmental illumination planning for the city in terms of the formative beauty, and this study is to suggest the valuation model method of the environmental illumination for the bridges as the initial step of the standardization. In the study, the valuation items of the standard questionnaire are selected by the documentary records and the consultation of various experts in architecture, design, fine art, urban planning and even administration to verify the essential elements of the aesthetic beauty with the local amenity and the environmental harmony for the chosen bridges across the Han-river.

• Journal of Preventive Medicine and Public Health
• /
• v.29 no.4 s.55
• /
• pp.831-842
• /
• 1996

Demand for high quality medical care has recently been increasing in step with high level of income and education. Patients prefer the use of large general hospitals to small community hospitals. Large hospitals, usually located at urban area, expand their capacities to cope with the increasing demand, therefore, they easily secure revenue necessary for growth and development of hospitals. However, small community hospitals are facing with serious financial difficulties caused from the reduction of patients in one hand and the inflation of cost in another. If small rural hospitals were closed, the closure would have negative impacts on local economies in addition to the decrease in access to medical care. Community leaders should have an insight on the contribution of community hospitals to local economies. They could make a rational decision on the hospital closure only with the understanding of hospital's contribution to the community. This study is designed to develop an economic model to estimate the contribution of rural hospital to local economies, and also to apply this model with a specific hospital. The contribution of a hospital to local economies consists of two elements, direct effect and multiplier effects. The direct impacts include hospital's local purchasing power, employee's local purchasing power, and the consumption of patients coming from outside the community. The direct impact induces multiplication effect in the local economy. The seed money invested to other industries grows through economic activities in the region. This study estimated the direct effect with the data of expenditure of the case hospital. The total effect was calculated by multiplied the direct effect with a multiplier. The multiplier was drown from the ratio of marginal propensity of income and expenditure. Beside the estimation of the total impacts, the economic effect from the external resources was also analyzed by the use of the ratio of patients coming outside the region. The results are as follows. 1. The direct economic contribution of the hospital to the local economy is 1,104 million won. 2. The value of multiplier in the region is 2.976. 3. The total economic effect is 3,286 million won, and the multiplication effect is 2,182 million won. 4. The economic contribution from the external resources is 245 million won which is 7.5% of the total economic effect.

• Journal of the Korean Institute of Traditional Landscape Architecture
• /
• v.30 no.3
• /
• pp.80-86
• /
• 2012

This study is about selecting Landscape Viewpoint on Bukchon Hanok Village, Jongno-Gu, Seoul. The process on selecting photo spots was focused on visualizing elements, and it was hard to find an objective standard for selecting landscape viewpoint. Therefore, by literature review and site study, this study selects more objective and empirical Landscape View Point on Bukchon. Landscape Viewpoint Standards are Traditional Hanok Landscape, Historical Heritage Landscape, Alley Street Landscape, City Architecture Landscape, and Natural Forest Landscape. By Landscape Preference and Character of Place survey, this study finds out another Landscape Viewpoint and correlation of those variables. A coefficient of correlation is 0.846, and its correlation is considerably high. Through this result, it could provide a concrete standard for selecting Landscape View Point and a preliminary information for finding Landscape View Point on Histo-Cultural area.