• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.63.2-63.2
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• 2016

One of the well-known problems in the lambda cold dark matter (${\Lambda}CDM$) models is a missing satellite problem. The slope of the mass function of low mass galaxies predicted by ${\Lambda}CDM$ models is much steeper than that based on the luminosity function of dwarf galaxies in the local universe. This implies that the model prediction is an overestimate of low mass galaxies, or that the current census of dwarf galaxies in the local universe may be an underestimate of dwarf galaxies. Previous studies of galaxy luminosity functions to address this problem are based mostly on the sample of galaxies brighter than Mv ~ -10 in the nearby galaxies. In this study we try to search for ultra-faint galaxies (UFDs), which are much fainter than those in the previous studies. We use multi-field HST ACS images of M60 in the archive. M60 is a giant elliptical galaxy located in the east part of the Virgo cluster, and hosts a large population of globular clusters and UCDs. Little is known about the dwarf galaxies in this galaxy. UFDs are much fainter, much smaller, and have lower surface brightness than normal dwarf galaxies so HST images of massive galaxies are an ideal resource. We present preliminary results of this search.

• Journal of The Korean Digital Architecture Interior Association
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• v.10 no.3
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• pp.39-46
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• 2010

Recently, in rural areas have been occurred closed school due to reduce children of people who consider educational environment. In July 2009 statistic, Closed school are ut to 3,348; sale process(61%), lease(25%), neglect(14%). Closed school are not only local community education, but also to act as cultural and historical role. First of all, it will be utilized public facilities as well as welfare facilities for local residents. In this study suggests the welfare facility where is remodelled as good case so that it will use as a data when closed school need remodeling. The main contents is as follows; it is set the slope next to the school building, a classroom is remodelled 2 triple rooms which are installed Ondol and a toilet, teacher's room is converted into the canteen, corridors are converted into the kitchen. Having good condition in the area, close school is appropriate to use welfare facility and also effective to convert teacher's space into normal space, canteen, kitchen. Finally, developed 2~5 composition type of elderly facility.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.34 no.2
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• pp.161-169
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• 2016

This paper is intended to propose a novel approach to select an optimal site for a small-scaled artificial recharge system installation using TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) with geospatial data. TOPSIS is a MCDM (Multi-Criteria Decision Making) method to choose the preferred one of derived alternatives by calculating the relative closeness to an ideal solution. For applying TOPSIS, in the first, the topographic shape representing optimal recovery efficiency is defined based on a hydraulic model experiment, and then an appropriate surface slope is determined for the security of a self-purification capability with DEM (Digital Elevation Model). In the second phase, the candidate areas are extracted from an alluvial map through a morphology operation, because local alluvium with a lengthy and narrow shape could be satisfied with a primary condition for the optimal site. Thirdly, a shape file over all candidate areas was generated and criteria and their values were assigned according to hydrogeologic attributes. Finally, TOPSIS algorithm was applied to a shape file to place the order preference of candidate sites.

• Geotechnical Engineering
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• v.12 no.3
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• pp.127-148
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• 1996

Recently, foundations of heavy structures such as bridge abutments have been built on slopes or near the crest of slopes at an increasing rate. Because the bearing capacity of such foundations is considerably lower than the bearing capacity of the same soil on a level ground, deep footings such as piles and caissons are often used. However, the costs of such methods are generally very high. One of the new techniques to overcome the problem is to place reinforcing members such as geosynthetics or metal strips horizontally at some depths beneath the footings. Rational methods of analysis to predict the bearing capacity of footings in reinforced slopes are therefore needed. This paper proposes an analytical method for estimating the increase in bearing capacity gained from the included horizontal strips or ties of tensile reinforcing in the foundation soil below the footing built near the crest of a slope. A failure mechanism, including the concept of'wide slab effect', adopted in the present study for analyzing the bearing capacity of foundations in reinforced slopes, is established through the observed model test behaviors described by Binquet SE Lee and Huang et al, and the Boussinesq solutions. The analytical results are then compared with the experimental data described in the paper by Huang et al. Also in order to properly evaluate the soil reinforcement interaction, typical pullout test values of the apparent friction coefficient, which usually vary with depths owing to both the increase of the shearing volume and the increase in local stress caused by soil dilatancy, are analyzed and related functionally. Furthermore, analytical parametric studies are carried out to investigate the effect and significance of various pertinent parameters associated with design of reinforced slope foundations. Keywords : Bearing capacity, Reinforced slope, Slab effect, Friction coefficient.

• The Journal of Engineering Geology
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• v.17 no.2 s.52
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• pp.163-176
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• 2007

Landslides which is one of the major natural hazard is defined as a mass movement of weathered material rock and debris due to gravity and can be triggered by complex mechanism. It causes enormous property damages and losses of human lift directly and indirectly. In order to mitigate landslide risk effectively, a new method is required to develope for better understanding of landslide risk based on the damaged cost produce, investment priority data, etc. In this study, we suggest a new evaluation method for slope stability using risk analysis. 30 slopes including 10 stable slopes, 10 slopes of possible failure and 10 failed slopes along the national and local roads are examined. Risk analysis comprises the hazard analysis and the consequence analysis. Risk scores evaluated by risk analysis show very clear boundaries for each category and are the highest for the failed slopes and the lowest for the stable slopes. The evaluation method for slope stability suggested by this research may define the condition and stability of slope more clearly than other methods suggested by others.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.2
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• pp.69-77
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• 2015

In Korea, local governments have decided the location of shelters as part of their disaster planning. However, no quantitative standards, such as assuming different hazard and shelter types, shelters' capacity, are specified in that planning. To propose the direction of disaster evacuation policy, first of all, the current state of shelters' location and evacuation area is needed to be analyzed. In addition, considering topographical condition such as road slope and physical strength by age are important factors to measure optimal evacuation route. The purpose is to suggest a new methodology of estimating optimal evacuation route considering resistance of road slope and difference of walking speed by age. Moreover, as a case study of Seoul, Korea, using coverage analysis of GIS analysis tool, the accessible area (or vulnerable area) to the shelters is evaluated based on the spatial distribution of disaster evacuation shelters and their accommodation capacity, according to evacuation time within 7.5, 15 and 30 minutes. The main results are summarized as follows: 1) The average area of disaster evacuation shelter per person is calculated as 0.45 square meters. Considering that the minimum shelters' area per person is 1 square meters, only 45% of people in Seoul can be accommodated. 2) The ratio of inhabitants who live in accessible area within 7.5 minutes presents only 33% of all. Furthermore, the ratio of inhabitants by age group of 5~9 or over 65 years old shows significantly lower percentage in comparison with 15~49 years old people.

• Journal of Biosystems Engineering
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• v.41 no.4
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• pp.288-293
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• 2016

Purpose: The purpose of this study was to investigate the key factors in designing a three-wheeled two-row soybean reaper (riding type) that is suitable for soybean production, and ensure worker safety by proposing optimal work conditions for the prototype of the designed machine in relation to the slope of the road. Methods: A three-wheeled two-row soybean reaper (riding type) was designed and its prototype was fabricated based on the local soybean-production approach. This approach was considered to be closely related to the prototype-designing of the cutter and the wheel driving system of the reaper. Load distribution on the wheels of the prototype, its minimum turning radius, static lateral overturning angle, tilt angle during driving, and The working and rear overturning (back flip) angle were measured. Based on the gathered information, investigations were conducted regarding optimal work conditions for the prototype. The investigations took into account driving stability and worker safety. Results: The minimum ground clearance of the prototype was 0.5 m. The blade height of the prototype was adjusted such that the cutter was operated in line with the height of the ridges. The load distribution on the prototype's wheels was found to be 1 (front wheel: F): 1.35 (rear-left wheel: RL): 1.43 (rear-right wheel: RR). With the ratio of load distribution between the RL and RR wheels being 1: 1.05, the left-to-right lateral loads were found to be well-balanced. The minimum turning radius of the prototype was 2.0 m. Such a small turning radius was considered to be beneficial for cutting work on small-scale fields. The sliding of the prototype started at $25^{\circ}$, and its lateral overturning started at $39.3^{\circ}$. Further, the critical slope angle for the worker to drive the prototype in the direction of the contour line on an incline was found to be $12.8^{\circ}$, and the safe angle of slope for the cutting was measured to be less than $6^{\circ}$. The critical angle of slope that allowed for work was found to be $10^{\circ}$, at which point the prototype would overturn backward when given impact forces of 1,060 N on its front wheel. Conclusions: It was determined that farmers using the prototype would be able to work safely in most soybean production areas, provided that they complied with safe working conditions during driving and cutting.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.14 no.1
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• pp.69-80
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• 1996

This Study aims at identifying optimum residential area of small and medium local cities to be relocated in the future. In the object of study, Chinju City was chosen and it consists of three stages of application to choose the priority of residential development us well as available residential locations. In the first stage, a digital image processing technique was applied to generate the existing urban land use information from the satellite image data. In the second stage, GIS technique was used to choose the avaliable residential area by evaluating the elements for residential site allocation such as road accessibility, topographic height, slope, aspect, legal limit, population density, and land price. In the third stage, some mathematical location models were applied to identify optimum candidates of residential areas chosen by earier stages. The results were evaluated by statistical methods and integer programming to identify the development priority. We expect this procedures and the results will be able to be used as a guide-line to support housing policies of Chinju City by allocating residential sites as well as a technique to apply a locational analysis for the future residential areas of small and medium local cities.

• Journal of the Korean Regional Science Association
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• v.14 no.1
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• pp.91-107
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• 1998

Waste disposal problem is one of the most important social welfare indicators in urban area, because the volume of waste generated from urban area is remarkable. So far most waste of Seoul has been disposed at landfills. However, this landifill disposal method is confronted with several difficulties in recent. As public concern on environmental problem increases and autonomy system is settled down, local community people of the landfills refuse to receive the waste produced other places any more. It brought reginal confliction problem between waste sending and receiving by refusing to accept waste from certain region. Furthermore, it is difficult to find another place to fill up the waste, while the existing landfiis is reached at the limit in the near future. In terms of environmental aspects landfill method is not the best way to dispose waste. It contaminates the soil and ground/underground water by leaking water containing many serious pollutants as well as offensive oder. In terms of equity, this waste disposal method is not fair. Environmental pollution causes damage to residence near to the landfills, while the waste produced other places. In order to satisfy the equity aspect, the waste generated a region should be disposed within the region. Incineration of Waste has been provided as the alternative. Government plans to construct waste incinerator in every anatomy, so the waste produced by local community is disposed within their local autonomous area. However, the location decision is not easy, since waste incinerator is one of the facilities to the community people. We can not apply the existing location models for this problem, because they show strong NIMBY phenomenon for the location. The location of waste incinerator should be determined very carefully with consideration of various location factors and criteria. This study proposes a methodology for determining the location of the waste incinerators by utilizing GIS, which is a power research tool for location decision where various geographical factors related. We drive the location factors which should be considered in the determination of waste incinerators. They involve environmental, socio-economic, and institutional factors. In first, we eliminate the area which is located within the environmental location criteria such as slope, fault line, distance to river, and then eliminate ares which is conflict with the social and institutional criteria.

• Journal of Korea Water Resources Association
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• v.31 no.3
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• pp.269-277
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• 1998

Laboratory flume experiments to investigate the characteristics of the flows and local scour around circular bridge pier in a curved channel are performed. In this study, the effect of a circular collar device for controlling the depth of scour is examined. The scour depth with a collar is about 40% of the scour depth without collar in the straight course of the flume while it is about 44% of the scour depth without collar at the location of 150' in the curved channel. As the results of experiments using the collar of which diameter is twice of pier, the reduction of scour depth is the most effective in a straight channel when the location of collar is 0.2h( h:depth) below the channel bottom. And, the reduction of scour depth is the most effective in a curved channel when the location of collar is 0.1h below the channel bottom.