• Asian Journal of Turfgrass Science
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• v.18 no.1
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• pp.37-46
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• 2004

The purpose of this study is to find the suitable putting green maintenance equipment for improving the quality of putting green. This study was carried out to investigate the green speed(i.e., ball roll distance) by different the types of greens mower(between work-behind greens mower and riding greens mower), the types of reel blades(between 9 blades and II blades) and the types of roller(between riding soil sprayer and lightweight roller). Green speed of golf course putting greens is assessed by use of Stimpmeter. The west course of Lakeside Country Club was selected for the case study. The results are summarized as follows; 1. The green speed was faster in 3.8 mm moving height treatment plot using work-behind greens mower than in 3.8 mm moving height treatment plot using riding greens mower right after the moving and even after eight hours had passed, and it was statistically significant at a 95% confidence level. Therefore, work-behind greens mower was judged to be a proper equipment type for the fast green management practice than riding greens mower. 2. The green speed was faster in 3.2 mm mowing height treatment plot using work-behind greens mower equipped with II blades than in 3.2 mm mowing height treatment plot using work-behind greens mower equipped with 9 blades, and this result was statistically significant at a 95% confidence level. Therefore, II-blade was judged to be a proper blade type for the fast green management practice than 9-blade. 3. The difference in green speed (green speed increased after rolling) between a treatment plot mowed at 3.0 mm mowing height with the work-behind greens mower and then rolled a single time with riding soil sprayer and a treatment plot mowed at 3.0 mm mowing height with the work-behind greens mower and then rolled once with lightweight roller was not statistically significant at a 95% confidence level. However, the difference in green speed (green speed decreased after rolling) between two treatment plots measured after eight hours had passed was statistically significant at a 95% confidence level. Therefore, the lightweight roller was judged to be a proper roller type for the fast green management practice than the riding soil sprayer.

• Bulletin of the Society of Naval Architects of Korea
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• v.25 no.4
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• pp.69-80
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• 1988

This paper proposes simple formulae for buckling and ultimate strength estimation of plates subjected to water pressure and uniaxial compression. For the construction of a formula for elastic buckling strength estimation, parametric study for actual ship plates with varying aspect ratios and the magnitude of water pressure is carried out by means of principle of minimum potential energy. Based on the results by parametric study, a new formula is approximately expressed as a continuous function of loads and aspect ratio. On the other hand, in order to get a formula for ultimate strength estimation, in-plane stress distribution of plates is investigated through large deflection analysis and total in-plane stresses are expressed as an explicit form. By applying Mises's plasticity condition, ultimate strength criterion is then derives. In the case of plates under relatively small water pressure, the results by the proposed formulae are in good agreement compared with those by other methods and experiment. But present formula overestimates the ultimate strength in the range of large water pressure. However, actual ship plates are subjected to relatively small water pressure except for the impact load due to slamming etc.. Therefore, it is considered that present formulae can be applied for the practical use.

• Journal of dental hygiene science
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• v.8 no.4
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• pp.275-281
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• 2008

Background: This research aims to provide basic data for dental hygienists to implement the infection control after understanding the level of their implementation of infection control in case they have been trained of infection control or not. Method: The respondents in this research are the dental hygienists who worked in the Incheon or Gyeonggi areas between June 16 and July 5, 2008 and who attended complementary training conducted by the Seoul Branch of Korean Dental Hygienists Association in April 2008. A total of 191 questionnaires were distributed to them, and the frequency of the collected data was analyzed using SPSS WIN 12.0. Moreover, cross-tabulation analysis (${\chi}^2$) whose significance level was 0.05, was applied to the data in order to verify the statistical significance of the survey method. Result: There was significant difference in their practice to wear gloves and/or a mask, use a disposable apron and the time to change the apron depending upon the respondents' workplace. There was significant difference in the time to change their apron depending upon the respondents' time of service. 91.6% had been trained in the infection control: of them, 70.7% trained at their school. It was found that 68.6% of the respondents who had been trained in the infection control would wash their hands before treating a patient. 50.3% of the respondents who had been trained in the prevention of contamination would wear their gloves as needed for a basic treatment. Conclusion: Considering the above results of this research, it is concluded that it is necessary to provide practicing dental hygienists with many opportunities for systematic and practical training so that they may faithfully follow the guidelines for the prevention of contamination and to encourage hospitals to have a greater store of relevant facilities, equipment and supplies.

• Korean Journal of Environment and Ecology
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• v.29 no.3
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• pp.333-343
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• 2015

This research aims at identifying the goshawk's possible and replaceable breeding ground by using the MaxEnt prediction model which has so far been insufficiently used in Korea, and providing evidence to expand possible protection areas for the goshawk's breeding for the future. The field research identified 10 goshawk's nests, and 23 appearance points confirmed during the 3rd round of environmental research were used for analysis. 4 geomorphic, 3 environmental, 7 distance, and 9 weather factors were used as model variables. The final environmental variables were selected through non-parametric verification between appearance and non-appearance coordinates identified by random sampling. The final predictive model (MaxEnt) was structured using 10 factors related to breeding ground and 7 factors related to appearance area selected by statistics verification. According to the results of the study, the factor that affected breeding point structure model the most was temperature seasonality, followed by distance from mixforest, density-class on the forest map and relief energy. The factor that affected appearance point structure model the most was temperature seasonality, followed by distance from rivers and ponds, distance from agricultural land and gradient. The nature of the goshawk's breeding environment and habit to breed inside forests were reflected in this modeling that targets breeding points. The northern central area which is about $189.5 km^2$(2.55 %) is expected to be suitable breeding ground. Large cities such as Cheongju and Chungju are located in the southern part of Chungcheongbuk-do whereas the northern part of Chungcheongbuk-do has evenly distributed forests and farmlands, which helps goshawks have a scope of influence and food source to breed. Appearance point modeling predicted an area of $3,071 km^2$(41.38 %) showing a wider ranging habitat than that of the breeding point modeling due to some limitations such as limited moving observation and non-consideration of seasonal changes. When targeting the breeding points, a specific predictive area can be deduced but it is difficult to check the points of nests and it is impossible to reflect the goshawk's behavioral area. On the other hand, when targeting appearance points, a wider ranging area can be covered but it is less accurate compared to predictive breeding point since simple movements and constant use status are not reflected. However, with these results, the goshawk's habitat can be predicted with reasonable accuracy. In particular, it is necessary to apply precise predictive breeding area data based on habitat modeling results when enforcing an environmental evaluation or establishing a development plan.

• The Korean Journal of Mycology
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• v.3 no.1
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• pp.1-19
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• 1975

Since the importance of casing in fruit body formation of Agaricus bisporus has been emphasized, physico-chemical characteristics of casing materials were discussed by many workers and a mixture of peat and mineral soil as proper casing material has been adopted in many of mushroom growing countries. Because of limited resources of peat in Korea, it is necessary to find practical performance and substitutional materials for casing. The effect of casing on mycelial growth and mushroom yield of A. bisporus varied with materials, its combination and practices etc. The experiments to be discussed in this paper are concerned with pH and Ca of casing material which influence A bisporus, and changes of physico-chemical characteristics with mixing ratio of casing materials and its effect on A. bisporus. The optimum range of moisture content of each material, management of watering and application of physico-chemical characteristics casing materials was also investigated and re-use of weathered spent compost for casing material was described. 1. The effect of calcium on mycelial growth of A. bisporus at various pH in Halbschalentest showed different results with calcium sources. Best results were obtained around neutrality and fresh weight of fruit bodies grown in the range of pH 7 to 8 was highest among the tested levels. 2. Available moisture, pore space, organic matter, cation exchangeable capacity and exchangeable cation was increased by an increase of mixing ratio of peat in casing materials, while an adverse effect was obtained by addition of sand. 3. Mycelial growth on clay loam was more rapid at a lower bulk density of 0.75g/cc and at 20% moisture content on a dry weight basis at the same bulk density. 4. Mixing ratio of casing materials, 60 to 80 per cent by volume of peat mixed with 20 to 40 per cent of clay loam produced the highest yield of fresh fruit bodies and sand the lowest. However, per cent of open cap was highest in peat and lowest in sand. 5. Days required for fruit body initiation was shortened in mixtures of peat and clay loam by one to three days compared with other materials and the formation of flushes was clear. 6. The effect of some physico-chemical characteristics of casing materials on the fresh weight of fruit bodies were estimated by a multiple regression equation; Y=-923.86+$8.18X_1+8.04X_2+7.90X_3+0.12X_4+2.03X_5-0.82X_6-0.54X_7$ where $X_1,X_2,X_3,X_4,X_5,X_6,X_7$ are sand, silt, clay, available moistuer, porosity, organic matter and exchangeable cation respectively. The productivity of certain casing material could be predicted from this equation. 7. Fresh weight of fruit bodies was positively correlated with porosity exchangeable cation, organic matter, available moisture, silt and clay of materials; while sand was negatively correlated. On the contrary, sand was the unique factor reducing per cent of open cap. 8. Distribution of three phases of high productive casing material was concentrated in the range of 10 to 30 per cent solids, 15 to 30 per cent liquids, and 50 to 60 per cent in air volume. 9. Fresh weight of fruit bodies from peat was not affected with heavy watering but in clay loam and sandy loam severe crop losses occurred. Fresh weight of individual fruit was increased and open caps were decreased with heavy watering but light watering resulted in adverse effects: its effect was especially great in peat. 10. Optimum range of moisture content by weight on a dry basis was different with each casing material. To maintain optimum moisture content concerned with yield of fruit bodies and open cap, sandy loam and peat mixtures required daily watering of 0.6, 0.6 to 1. 2 and 1.2 to 2.4 liters per $3.3m^2$ of bed area, respectively. 11. Maximum yield of fruit body was recorded in the range of pF 2. 0 to 2. 5 of casing materials if organic matter content was below 4.2 per cent and in pF 1. 3 to 1.8 if above 7.1%. 12. pF curve of a certain casing material could be draws from moisture content at various pF values by multiple regression equations provided texture, organic matter and calcium of the casing material are given. Optimum moisture range of the casing materials also could be estimated by the equation. 13. It was possible to improve the phyico-chemical characteristics of clay loam and sandy loam by addition of weathered spent compost although the effect was less than in the case of peat. Fresh weight of fruit bodies wsa increased by addition of weathered spent compost but its effect was not as remarkable as peat. Accordingly, further studies will be required.

• Journal of the Korean Institute of Landscape Architecture
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• v.44 no.6
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• pp.73-83
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• 2016

This study modified and applied the ecological network(Indicator 2) from the City Biodiversity Index(CBI) to be tailored to Korea. It is calculated by utilizing a biotope map and a land cover map. The ecological network of Gyeryong-Si was 13,713,703(33.8%) with the biotope map and 17,686,966(37.9%) with the land cover map. The result of the biotope map was lower than the land cover map. The ecological network of Goyang-Si was 4,961,922(4.9%) with the biotope map and 4,383,207(3.7%) with the land cover map. The result of the land cover map was lower than the biotope map. As a main result of the research, an error was discovered in which, when calculating the ecological network, the types of the military unit facilities were distinguished into a special area on the biotope map and into an urbanization promotion area and a forest area on the land cover map. In the case of a middle-classified, land cover map, the land use in the surroundings of the forest area was not subdivided. An error in the development area expressed as a forest green was discovered. When selecting the natural elements, too, regarding the types of artificially-created rivers, artificial ponds, and artificial grasslands, etc. on a biotope map, the exclusions were necessary. Regarding the natural, bare ground on a land cover map, there was a need to calculate by including the natural elements. It was judged that, in the future, the ecological network in the unit of the entire nation can be analyzed roughly by utilizing a land cover map. It was judged that, in a city having a biotope map, the calculation of the ecological network utilizing a map of the present situation of the urban ecology will be a more accurate diagnosis of the present situation.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.1
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• pp.52-62
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• 2017

Overseas landscape practices have already benefited from the awareness of BIM while landscape-related organizations are encouraging its use and the number of landscape projects using BIM is increasing. However, since BIM has not yet been introduced in the domestic field, this study investigated and analyzed overseas landscape projects and discussed the positive effects and implementation of BIM. For this purpose, landscape projects were selected to show three effects of BIM: improvement of design work efficiency, building of a platform for cooperation, and performance of topography design. These three projects were analyzed across four aspects of implementation methods: landscape information, 3D modeling, interoperability, and visualization uses of BIM. First, in terms of landscape information, a variety of building information was constructed in the form of 3D libraries or 2D CAD format from detailed landscape elements to infrastructure. Second, for 3D modeling, a landscape space including simple terrain and trees was modeled with Revit while elaborate and complex terrain was modeled with Maya, a professional 3D modeling tool. One integrated model was produced by periodically exchanging, reviewing, and finally combining each model from interdisciplinary fields. Third, interoperability of data from different fields was achieved through the unification of file formats, conversion of differing formats, or compliance with information standards. Lastly, visualized 3D models helped coordination among project partners, approval of design, and promotion through public media. Reviewing of the case studies shows that BIM functions as a process to improve work efficiency and interdisciplinary collaboration, rather than simply as a design tool. It has also verified that landscape architects could play an important role in integrated projects using BIM. Just as the introduction of BIM into the architecture, engineering and construction industries saw great benefits and opportunities, BIM should also be introduced to landscape architecture.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.1
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• pp.73-81
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• 2017

During the 1990s, policy was put in place to create resting spaces in rural areas. This policy was associated with a government project to improve the rural residence environment and it attracted attention to outdoor spaces in rural areas. Many communities have gradually disappeared in rural areas but previous studies suggested that legally protected trees might provide resting and cultural spaces in a given rural community. The rural residential environment can be improved by legally protected trees and by doing so, these resources may then help to sustain many rural communities. Therefore, the creation of resting spaces or mini-parks created around trees that are protected by in rural communities should be considered. The value of trees that are protected by law can differ depending on the status of the trees or the surroundings. Nevertheless, there has not been systemic research regarding legally-protected trees in terms of rural communities. This study aims at evaluating the potential of these trees and at analyzing how these trees can be useful in the creation of community spaces in rural areas. The findings can be helpful in providing foundation data for creating these types of community spaces. Forty legally protected trees in Gimchon City were selected for this study. Nine items were used to evaluate the potential of the trees for creating community spaces. These items could be classified into five factors including accessibility, relation to public facilities, environment and safety, symbolism, and ease for creating community spaces. The potential of the legally protected trees was evaluated by 5-point Likert Scales in a given item. The overall potential was evaluated by the sum of individual item scores. Specifically, trees with over 20 points (max. 25 points) could be considered high potential. According to the empirical findings, the portion of legally protected trees with high potential is five percent (No.7 and No.12 trees). Therefore, the priority is to protect or use the trees for the creation of community spaces that can help make a better residential environment for rural communities.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.4
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• pp.325-334
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• 2008

The standard prestressed concrete I-girder bridge (PSC I-girder bridge) is one of the most prevalent types for small and medium bridges in Korea. When determining the member forces in a section to assess the safety of girder in this type of bridge, the general practice is to use the simplified practical equations or the live load distribution factors proposed in design standards rather than the precise analysis through the finite element method or so. Meanwhile, the live load distribution factors currently used in Korean design practice are just a reflection of overseas research results or design standards without alterations. Therefore, it is necessary to develop an equation of the live load distribution factors fit for the design conditions of Korea, considering the standardized section of standard PSC I-girder bridges and the design strength of concrete. In this study, to develop an equation of the live load distribution factors, a parametric analysis and sensitivity analysis were carried out on the parameters such as width of bridge, span length, girder spacing, width of traffic lane, etc. As a result, the major variables to determine the size of distribution factors were girder spacing, overhang length and span length in case of external girders. For internal adjacent girders, the determinant factors were girder spacing, overhang length, span length and width of bridge. For internal girders, the factors were girder spacing, width of bridge and span length. Then, an equation of live load distribution factors was developed through the multiple linear regression analysis on the results of parametric analysis. When the actual practice engineers design a bridge with the equation of live load distribution factors developed here, they will determine the design of member forces ensuring the appropriate safety rate more easily. Moreover, in the preliminary design, this model is expected to save much time for the repetitive design to improve the structural efficiency of PSC I-girder bridges.

• Journal of the Speleological Society of Korea
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• no.95
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• pp.35-49
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• 2009

Ever since the beginning of time, caves not only have offered a place to live for humans but they have also been used as cultural spaces. That is, in the event of making some sounds in a location within the cave, the sound that is created is greatly magnified and sounds out as if it is being amplified from a giant megaphone. This, as we well know it, is known as the resonance effect. Here, the cave itself appears to function as a massive wind instrument. Especially in cases like the Altamira Cave (Spain) where cave paintings were found, the point where the cave drawings were found has commonalities in that it is a wide space and that it is usually discovered together with flutes and drums that are made with mammoth bones. We need to focus on this point. We can infer from these facts that the prehistoric people have carried out cultural activities along with their incantation rituals within those caves. In the meantime, amongst the Korean traditional arts, in the case of pansori which is a representative vocal genre, there have been examples where caves were used as practicing locations for those people who are training to perfect their singing. This is known as toguldoggong(土窟獨功) which literally means 'obtaining one's own art by oneself in the earth cave by practicing incessantly'. This process along with pokpodoggong (瀑布獨功) (same as above except that the location is by the waterfall) is the final training stage in order to become a recognized virtuoso on the part of the apprentice. This could be compared to the final annealing and finishing process of producing a metalwork. This has been a long tradition followed by most Korean traditional artists in order to perfect their sound which is harmonious with nature within natural surroundings. By honing in on this point, I have come to think about this matter repeatedly while coaching the university students in vocal singing. In short, I came to the conclusion that "the making of natural sounds will be obtained naturally within natural surroundings like caves!" Consequently, The Society for Studying Cave Sounds was inaugurated on January 1992 along with some of my students. We made use of times like vacations to go around exploring caves all over Jeju and carried out investigations of sounds along with cave exploration on an experimental basis. After 5 years, in September of 1997, we were able to host the first ever cave concert domestically at the Whale Nostril Cave(東岸鯨窟) on Wu-do. After that, we have been hosting the cave concert once every year. We have achieved a record of a total of 14 cave concerts until 2009 of this year. Out of these, 2 were held in Seokhwaeam Cave in Kangwon Province, another two were held in Manjang Cave which is a lava cave, and the remaining 10 were held in the Whale Nostril Cave of Wu-do. Along with that, I have carried out a special recording for the production of a cave music CD in May of 1999. This paper was written and organized by using the main materials that were derived from the experiences of using caves as concert halls in the past. It is hoped that this cave concert will offer a very unique experience to tourists who come to Jeju every year and give them the best possible superior natural sound effect that only Jeju caves can offer.