• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.1000-1004
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• 2008

As performance of medical air compressor improve, the problem of noise increased. Noise is very important to medical air compressor because most of this installed inside of building. The main goal of this paper is show TPA (Transfer Path Analysis) result for contribution analysis using PAK system. Generally, the conventional TPA method consists of two steps. First, transfer functions between output sound and sources are measured by excitation experiment. Second, transferred sound in each transfer path is generated by multiplying the transfer function and the sound source signal. Then, if the output sound synthesized from all transferred sounds doesn't give good agreement with the measured output sound (i.e., the accuracies of the transfer functions are low), setting a suitable countermeasure guideline becomes difficult. For obtaining highly accurate transfer functions, eliminating correlations among transfer functions and noise included in the measured data are necessary. In the new method with PAK system, the vibration acceleration and sound signals around the sound sources and the output sound were measured simultaneously to obtain the transfer functions when compressor was operating. By applying PAK system, a highly accurate and efficient transfer path analysis method was developed that does not require an excitation experiment.

• 농업과학연구
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• 제32권2호
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• pp.151-167
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• 2005

In this study, certain factors influencing cherry tomato were estimated using system equations. In addition, the amount of influence to income from each factor was estimated from both direct and indirect effects. Based on OLS(Ordinary Least Squares) estimation, path analysis and factor analysis were employed to overcome multicollinearity problems. Data used in this study is interviewed cross sectional data of 65 cherry tomato producing farm in Chungnam-do area. Average age of the producers is 46.5. Average year of the production is 8 years. Average farm size, productivity, and income are 1,123 pyong, 7,439kg/10a, 8,112,000won/10a, respectively. The business performance of the sample farms were above average, in terms of the diagnosis by "Standard Business Diagnosis for Cherry tomato". To identify the factors influencing productivity, 15, 19, and 25 independent variables were selected for the dependent variables of yield, price(quality), and business cost, respectively. Finally, yield, quality, and business cost variables were set as independent variables to explain income as dependent variable. As a result of main factor analysis, 10, 12, 15, and 16 factors were identified as main factors for yield, quality, business cost, and income, respectively.

• 한국식생활문화학회지
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• 제35권1호
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• pp.65-78
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• 2020

The objective of this study was to review and evaluate the growing subject of food tourism research, and thus identify the trend of food tourism research. Using a Text mining technique, this paper discovered the trends of the literature on food tourism that was published from 2004 to 2018. The study reviewed 201 articles that include the words 'food' and 'tourism' in their abstracts in the KCI database. The Wordscloud analysis results presented that the research subjects were predominantly 'Festival', 'Region', 'Culture', 'Tourist', but there was a slight difference in frequency according to the time period. Based on the main path analysis, we extracted the meaningful paths between the cited references published domestically, resulting in a total of 12 networks from 2004 to 2018. The Text network analysis indicated that the words with high centrality showed similarities and differences in the food tourism literature according to the time period, displaying them in a sociogram, a visualization tool. This study has implications that it offers a new perspective of comprehending the overall flow of relevant research.

• 한국자동차공학회논문집
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• 제23권1호
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• pp.65-73
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• 2015

The ride quality has become a key component of not only design but car selling as the technology developed and the requirement of passengers grew up. Thus car industry invests lots of time and cost for the higher ride quality. The evaluation of the ride quality mainly is expressed by subjective element that drivers felt. In this paper, instead of the original transfer path analysis method, relatively new methods such as OPAX(Operational path analysis with eXogeneous inputs) and OTPA(operational transfer path analysis) are used for analyzing the main hindrance element of ride quality. With those new method, contribution rate of all paths that the vibration propagate along analyzed after driving test on the roads having different characteristic. The comprehensive hindrance elements of ride quality are deduced from the contribution rate and the improve experiment by changing one of hindrance elements for higher ride quality.

• 국제학술발표논문집
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• The 10th International Conference on Construction Engineering and Project Management
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• pp.18-24
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• 2024

Efficient path planning for mobile crane lifting operations in the construction industry is essential for ensuring smooth machinery operation, worker safety, and the timely completion of projects. The inherently complex construction sites, characterized by dynamic environments, constantly changing conditions, and numerous static and mobile obstacles, underscore the necessity for advanced algorithms capable of generating optimal paths under various constraints. Mobile crane path planning algorithms have been researched extensively and possess the potential to resolve the challenges presented by construction sites. However, the application of these algorithms in actual construction sites is rare, suggesting a need for ongoing research and development in this field. This paper begins by systematically identifying and analyzing relevant research papers using predetermined keywords, providing a comprehensive review of the current state of mobile crane path planning algorithms. Specifically, it categorizes mobile crane path planning algorithms into four main groups: Graph search-based algorithms, Sampling-based algorithms, Nature-inspired algorithms, and Newly developed algorithms. It performs a critical analysis of each category, offering guidance to researchers exploring path planning solutions suitable for the dynamic and complex environments of construction sites. Through this review, we affirm the need for continued interest and attempts at new methodologies in mobile crane path planning, suggesting improvements for further research and practical application of these algorithms.

• 영어어문교육
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• 제13권1호
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• pp.87-110
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• 2007

Past studies conducted on the students' verbal participation both in and out of class have explored and identified variables affecting the process of learning to speak English. However, little is known about the causes and effects of these variables. A survey form developed from a previous study was administered to 468 university students taking English conversation classes from native speakers of English. To better understand the causes and effects of speaking barriers, path analysis was administered as the main tool of investigation. The results of the study indicate that familiarities toward NS (Native Speaker) teachers, learner faithfulness, che-myon, NS teachers' classroom management skills, and NS teacher's trustworthiness account for 50.72% of speaking grades. These factors are causally related to learner attitudes. However, with regard to speaking grades, all of the above factors except che-myon are also causally related with each other. Therefore, it was concluded that learner attitudes can be improved by minimizing che-myon, however, che-myon itself cannot be a predictor of speaking grades. To validate the findings of the study, related research work is discussed and implications are provided.

• 한국군사과학기술학회지
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• 제10권3호
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• pp.71-78
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• 2007

We suggest a multi-path propagation analysis method using DTM(Digital Terrain Map). Generally, the total signal strength at a target is calculated by adding the field propagated in free space and the field reflected from the ground surface. In this paper, we also consider the vertical reflections associated with the vertical surfaces such as precipitous cliffs and electricity pylons in the mountain area. In addition, we primarily take account the main slope of the ground surface to improve the accuracy of the total field density at the target.

• 한국유체기계학회 논문집
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• 제18권6호
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• pp.37-44
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• 2015

Conjugate heat analysis on a high pressure turbine stage including secondary flow paths has been carried out. The secondary flow paths were designed to be located in front of the nozzle and between the nozzle and rotor domains. Thermal boundary conditions such as empirical based temperature or heat transfer coefficient were specified at nozzle and rotor solid domains. To create heat transfer interface between the nozzle solid domain and the rotor fluid domain, frozen rotor with automatic pitch control was used assuming that there is little temperature variation along the circumferential direction at the nozzle solid and rotor fluid domain interface. The simulation results showed that secondary flow injected from the secondary flow path not only prevents main flow from penetrating into the secondary flow path, but also effectively cools down the nozzle and rotor surfaces. Also thermal barrier coating with different thickness was numerically implemented on the nozzle surface. The thermal barrier coating further reduces temperature gradient over the entire nozzle surface as well as the overall temperature level.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.251-255
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• 2012

Structural intensity has been mainly utilized to identify vibration energy flow in a vessel. In this paper, the structural intensity of a shuttle tanker subjected to H-moment of the main engine was calculated using a finite element model. From the analysis, it was found that the top-bracing elements, which support the main engine onto the hull structure to prevent the excessive transverse vibration of the main engine, play the role of the dominant path and sink for vibration energy flow from the main engine. Therefore, the structural intensity was controlled by the modification of stiffness and damping characteristics of the top-bracing elements. As a result, it is observed that the transverse vibration level at the center of navigation bridge deck decreased after the control of structural intensity.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제4권1호
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• pp.1-9
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• 2000

This paper describes an analysis of various factors affecting traffic noise propagation, including the distance from the road, existence of a direct path of noise propagation, density and height of buildings, and procedure for predicting the attenuation of noise levels from roads. The analysis is based on a multiple number of regression models, utilizing the quantification theory of the first kind. This study incorporates a large amount of survey data concerning traffic noise propagation. The survey of the traffic noise propagation around main roads was carried out in several residential areas, mainly in Kwangju. The attenuation of noise levels measured provided 691 usable data samples. A multiple regression analysis demonstrated that the distance from the road makes the most significant contribution to the attenuation of the noise level. The second contributor was found to be the existence of a direct path of noise propagation. The building density and average height of the buildings also affected the attenuation of the noise level considerably. Other factors, such as the height of the building behind the receiver microphone and the number of traffic lanes on the noise-source roads, did not contribute as much to the attenuation of the noise level as the factors mentioned avove.