• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.5
• /
• pp.139-148
• /
• 2002

Motion errors of linear motion guideway are analyzed theoretically in this paper. For the analysis, an new algorithm predicting motion errors of bearing and guideway is proposed using the Hertz's elastic deformation theory. Accuracy averaging effect can be calculated quantitatively by analyzing relationship between motion errors of guideway and spatial frequency of rail form error. Influences of design parameters on the motion errors including the number of balls, preload, ball diameter, bearing length and the number of bearings are analyzed. As it is difficult to measure the rail form error, experimental results are compared with results analyzed by the equivalent analysis method which evaluate the motion errors of guideway using the measured errors of bearing. From the experimental results, it is confirmed that the proposed analysis method it effective lo analyze the motion errors of linear motion bearing and guideway.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.4
• /
• pp.532-542
• /
• 2018

Because maglev trains have a propulsion and absorption force without contact with the rails, they can drive safely at high-speed with little oscillation. Recently, test model of a maglev propulsion train was produced and operated, and has since been chosen as a national growth industry in South Korea; there have been many studies and considerable investment in these fields. This study examined the dynamic responses due to bridge-maglev train interaction and basic material to design bridges for maglev trains travelling at high-speed. Depending on the major factors affecting the dynamic effects, the scope of this study was restricted to the relationship between dynamic responses. A concrete box girder was chosen as a bridge model and injured train and rail types in domestic production were selected as the moving train load and guideway analysis model, respectively. From the analysis results, the natural frequency of a bridge for a maglev train, which has a deflection limit L/2000, was higher than those of bridges for general trains. The dynamic responses of the girder of the bridge for a maglev train showed a substantial increase in proportion to the velocities of the moving train like other general bridge cases. Maximum dynamic response of the girder is shown at a moving velocity of 240km/h and increased with increasing moving velocity of train. These results can be used to design a bridge for maglev propulsion trains and provide the basic data to confirm the validity and verification of the design code.

• Korean Journal of Environment and Ecology
• /
• v.23 no.1
• /
• pp.78-89
• /
• 2009

As 'design for all' and 'adaptable design', universal design is highly demanded to be adopted in neighborhood forest trail. The research areas were Mt. Doeum in Pohang, Gyeongsangbuk Province and Mt. Anma in Chuncheon, Gangwon Province which were equipped based on 7 principles of universal design. The purpose of this research is providing baseline data for effective formulation of forest trail using universal design through visitors' evaluation on forest trail facilities by importance-performance analysis. Visitor's evaluation was achieved through questionnaire survey, and total 247 pieces of subjects were used for the analysis, 114 pieces from Mt. Doeum in Pohang and 113 pieces from Mt. Anma in Chuncheon. The residential areas of the respondents were mainly near each mountain - Mt. Doeum and Mt. Anma. According to the responses, nature study and education were the biggest reasons for the respondents' visits to Mt. Doeum, and so was the health to Mt. Anma, which are representative types of visiting behavior to nearby forest trails. The mean of importance was shown to be 3.87 while that of performance was 4.04, being a little higher than importance's, in importance-performance analysis of Mt. Doeum. This result suggests that the responders placed positive value on the forest trail applying universal design. It is necessary to improve the safety and convenience of guidance-safety handrail, make information sign easy to understand, and introduce an interpretive sign meeting the visiting purposes of visitors. Also, the management to make the road surface flat is in demand for the accessibility to forest trail. The mean of importance was 3.92 and that of performance was 3.99 in Mt. Anma, which suggests the necessity of improvement in safety of pavement material and boundary safety facilities.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.49 no.3
• /
• pp.1-10
• /
• 2021

This study aimed to evaluate preferences of Bukhansan dulegil using sentiment analysis, a natural language processing technique, to derive preferred and non-preferred factors. Therefore, we collected blog articles written in 2019 and produced sentimental scores by the derivation of positive and negative words in the texts for 21 dulegil courses. Then, content analysis was conducted to determine which factors led visitors to prefer or dislike each course. In blogs written about Bukhansan dulegil, positive words appeared in approximately 73% of the content, and the percentage of positive documents was significantly higher than that of negative documents for each course. Through this, it can be seen that visitors generally had positive sentiments toward Bukhansan dulegil. Nevertheless, according to the sentiment score analysis, all 21 dulegil courses belonged to both the preferred and non-preferred courses. Among courses, visitors preferred less difficult courses, in which they could walk without a burden, and in which various landscape elements (visual, auditory, olfactory, etc.) were harmonious yet distinct. Furthermore, they preferred courses with various landscapes and landscape sequences. Additionally, visitors appreciated the presence of viewpoints, such as observation decks, as a significant factor and preferred courses with excellent accessibility and information provisions, such as information boards. Conversely, the dissatisfaction with the dulegil courses was due to noise caused by adjacent roads, excessive urban areas, and the inequality or difficulty of the course which was primarily attributed to insufficient information on the landscape or section of the course. The results of this study can serve not only serve as a guide in national parks but also in the management of nearby forest green areas to formulate a plan to repair and improve dulegil. Further, the sentiment analysis used in this study is meaningful in that it can continuously monitor actual users' responses towards natural areas. However, since it was evaluated based on a predefined sentiment dictionary, continuous updates are needed. Additionally, since there is a tendency to share positive content rather than negative views due to the nature of social media, it is necessary to compare and review the results of analysis, such as with on-site surveys.