• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.2
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• pp.161-168
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• 2015

An experimental study was conducted to scrutinize the influence of the frequency of an ultrasonic standing wave on the variation in the behavior of a methane-air premixed flame. The evolutionary features of the propagating flame were captured by a high-speed camera, and the macroscopic flame behavior, including the flame structure and local velocities, was investigated in detail using a post-processing analysis of the high-speed images. It was found that a structural variation and propagation-velocity augmentation of the methane-air premixed flame were caused by the intervention of the ultrasonic standing wave, which enhanced the combustion reaction. Conclusive evidence for the dependency of the flame behaviors on the driving frequency of the ultrasonic standing wave and equivalence ratio of the reactants is presented.

• The Journal of the Korea Contents Association
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• v.14 no.7
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• pp.151-160
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• 2014

The purpose of this study is to deduce improvement plan through analysis of the type and characteristics of traffic accidents caused by elderly drivers, and to establish the traffic safety policies for the elderly drivers. The analyzed result of road traffic accident situation are as follows. Firstly, Traffic accidents caused by elderly drivers were frequent on local roads of poor traffic safety facilities such as lighting. Secondly, The most frequent time zone of Traffic accidents caused by elderly drivers was 18:00 to 20:00, this time zone was mainly darkened. Thirdly, Traffic accidents are often caused by lack of attention occurred by no implementation of safe driving. Institutional Improvement of cosideration for elderly drivers and Traffic Safety Facilities maintenance considering regional particularities is needed for reducing traffic accidents and the safety of our society. Their driving skills of elderly drivers should test themselves constantly, and elderly drivers must hold down driving yourself using the alternative transportation.

• Journal of Information Processing Systems
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• v.14 no.6
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• pp.1445-1456
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• 2018

Environment perception and three-dimensional (3D) reconstruction tasks are used to provide unmanned ground vehicle (UGV) with driving awareness interfaces. The speed of obstacle segmentation and surrounding terrain reconstruction crucially influences decision making in UGVs. To increase the processing speed of environment information analysis, we develop a CPU-GPU hybrid system of automatic environment perception and 3D terrain reconstruction based on the integration of multiple sensors. The system consists of three functional modules, namely, multi-sensor data collection and pre-processing, environment perception, and 3D reconstruction. To integrate individual datasets collected from different sensors, the pre-processing function registers the sensed LiDAR (light detection and ranging) point clouds, video sequences, and motion information into a global terrain model after filtering redundant and noise data according to the redundancy removal principle. In the environment perception module, the registered discrete points are clustered into ground surface and individual objects by using a ground segmentation method and a connected component labeling algorithm. The estimated ground surface and non-ground objects indicate the terrain to be traversed and obstacles in the environment, thus creating driving awareness. The 3D reconstruction module calibrates the projection matrix between the mounted LiDAR and cameras to map the local point clouds onto the captured video images. Texture meshes and color particle models are used to reconstruct the ground surface and objects of the 3D terrain model, respectively. To accelerate the proposed system, we apply the GPU parallel computation method to implement the applied computer graphics and image processing algorithms in parallel.

• Journal of Korean Society of Transportation
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• v.21 no.5
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• pp.97-110
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• 2003

The sight distance at unsignalized intersections is the one of the fundamental geometric design elements, and can ensure safety and efficient operations. Despite its importance, little research attention has been directed in Korea compared to developed countries such as European countries, the United States, and Japan. AASHTO ISD policies have been applied to the intersection design in Korea without any revise, which can produce unrealistic and unadoptable design values. Those values are emerged from several reasons because the AASHTO ISD has been calibrated based on the local data. Therefore the ISD hardly takes into account the local characteristics of Korea such as driving behavior. vehicular movement and roadway conditions. The objective of this study is to calculate the appropriate ISD values for unsignalized intersections in the urban area in Korea. In this study, we employed the ISD model of AASHTO(2001), which is based on gap acceptance theory and can account for and take the driving and roadway conditions in Korea into consideration. The approach can also consider the complex driving maneuvers at the intersections in a proper and simple manner. The results in this study show that the ISD design criteria currently used in Korea are more conservative(safer) than those of the USA. In other words, the ISD using field data collected in this study has generally smaller values than those in USA.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6C
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• pp.251-258
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• 2011

Steel pipe piles have been used as various deep foundation materials for a long time. Recent increase in steel material cost has made engineers reluctant in using it even with its good quality and ease of construction. Therefore when constructing with steel pipe pile, the decision to reuse the excessive pile length that is cut off from the designed pile head elevation after pile driving can be cost saving. This has caused many constructors to reuse the pile leftovers with new piles, but the absence of quantitative structural capacity behaviors of steel pipe pile after pile driving or appropriate countermeasures and standards in reusing steel pipe pile has resulted in wrong applications, pile structural integrity problems, inappropriate limitation of reusable pile length, etc. The structural performance analysis between a new pile and a pile that has undergone working state and ultimate state stress level during pile driving was performed in this research by means of comparing the results between the dynamic pile load test, tensile load test, charpy energy test and fatigue test for high strength steel of $440N/mm^2$ yield strength. Test results show that under working load conditions the yield strength variation is less than 2% and for ultimate load conditions the variation is less than 5% for maximum total blow count of 3000. The results have been statistically analyzed to check the sensitivity of each factors involved. From the test results, reusability of steel pipe pile lies not in the main pipe yield strength deviation but in the reduction of absorb energy, strength changes and quality control at the welded section, shape deformation and local buckling during pile driving.

• Journal of Biosystems Engineering
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• v.33 no.1
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• pp.38-44
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• 2008

The freight vehicle is mostly used to transport the fruit. Shock and impact generated by the freight vehicle may give serious damage to fruits hence to reduce the fruits damage, the optimum packaging design during transportation by vehicle is required. In order to design the packaging system for fruit transportation optimally, the comprehension of characteristic for vibration and shock acting on vehicles under various road conditions and loading methods is required. This research was performed to analyze the shock characteristics, acceleration level and power spectral density (PSD) of the fruit transportation vehicles under several travel roads and positions. The vibration signal was measured and analyzed at the transportation vehicle operating on the road of three different surface conditions. The maximum acceleration was measured at the rear-end of the vehicle, and the acceleration in the direction of up-and-down (z-axis) was much greater than those in the directions of back-and-forth (x-axis) or right-and-left (y-axis). The peak acceleration in the direction of up-and-down (z-axis) at the vehicle driving on the expressway, the local road paved with concrete, and unpaved local road were 5.3621 G, 8.232 G, and 14.162 G respectively. PSD at 2.44 Hz showed maximum value at all road conditions. The maximum values of PSD on the expressway, a local road paved with concrete, and unpaved local road were 0.0075222 $G^2/Hz$, 0.058655 $G^2/Hz$, and 0.24598 $G^2/Hz$ respectively. The value of PSD decreased with an increase of the vibration frequency of the transportation vehicle. In most cases, the vibration frequency was below 20 Hz during transportation.

• Journal of People, Plants, and Environment
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• v.24 no.3
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• pp.285-300
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• 2021

Background and objective: Rural migrants are an important human resource in urban and rural exchange (URE) business, therefore it is necessary to enhance their awareness and intent-to-participate. This study was to analyze the rural migrants' recognition and intent-to-participate of URE business and to propose the enhancement of them both. Methods: The questionnaire was designed to analyze the socio-demographic background, motivations, satisfaction with settlement, intent-to-persist, and intent-to-participate of URE business including tourism. The data of 144 respondents was subject to the statistical analysis. Results: The motives of migration were to enjoy leisure life after retirement, increased tiredness of city life, health problems, etc. The satisfaction with settlement was 3.67 at 5-point Likert scale. The intent-to-recommend and intent-to-publicize were 3.40 and 3.46, respectively. The intent-to-participate was 3.45, which was affected by the necessity of URE business and the support of central/local governments, and also showed a significant correlation with the satisfaction with settlement, intent-to-recommend, intent-to-publicize, tourism resources for green tourism or rural tourism, driving a car in Namhae county, and the service and price of meals. They thought the missions that the Namhae county office must focus on were to establish an internal/external public relations systems, establish a support system of central/local governments, and foster/support local leaders. Conclusion: It is necessary to improve the satisfaction with settlement and intent-to-persist, expand exchanges with local people, improve internal/external public relations systems, foster/support leaders, improve transportation in the county, enhance the service and price of meals, and develop/operate URE programs including tourism.

• Industry Promotion Research
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• v.8 no.3
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• pp.201-210
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• 2023

This study is based on data ecology theory and takes Chinese local governments' open public data as the research object. Data asset value assessment methods are compared from a new perspective of data business operations. The results show that the assessment model constructed using the hierarchical analysis method (AHP) can more objectively reflect the commercial value of government open data assets than the traditional cost, revenue and market methods, has the advantage of a comprehensive assessment of data value index, and better reflects the findings of a comprehensive index of regional data value. The data show that the local government data value assessment index is positively proportional to the region's digital economy development index, highlighting the driving effect on the digital economy. The results of the study provide a good help for the identification of local government data value rights. The research and practice of promoting the construction of data innovation and data business operation models, improving social well-being and promoting the rapid development of the digital economy to achieve data realisation provides a good reference.

• Journal of Digital Convergence
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• v.18 no.11
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• pp.73-79
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• 2020

With the recent strengthening of local autonomy and the recognition of the culture and tourism industry as a driving force for the fourth industrial revolution, the importance of research on the revitalization of the local culture and tourism industry is further emphasized. Thus, in this paper, the concept and type of local culture and tourism products were summarized and the research direction was presented through this. As a research method, the internal and external factors of the culture and tourism industry in Korea were used as the SWOT analysis method. In the text, three representative sites were selected and analyzed for the development of local cultural and tourism products, and Seoul, Jeju Island, and Gyeongju all found that they lacked local cultural and tourism products. It also found another value through its role of cultural development as well as the economic aspect of the development of cultural tourism products. In order to revitalize the local culture and tourism industry, which has become more important, the government proposed measures to promote differentiated creative products, efficient marketing, and legal security in various ways. In order for this study to be better data for researchers in the culture and tourism industry and related industries, research should be conducted with detailed surveys that could not be conducted due to various restrictions in the future.

• ALGAE
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• v.26 no.3
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• pp.243-251
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• 2011

Environmental conditions can influence the morphology of local biota through phenotypic plasticity or local adaptation. Macroalgal morphologies are often associated with wave-exposure conditions. We investigated the relationship between morphology and wave exposure in two common endemic subtidal macroalgae, Carpophyllum angustifolium and C. maschalocarpum, from the East Cape of New Zealand. Morphological comparisons were made between individuals from two sites and four different wave-exposure zones, as defined by fetch and barnacle composition. Of the seven morphological traits measured in C. angustifolium, only total length varied, and individuals were longer in more wave-exposed environments between the two exposure zones where the species were found. In contrast, total length, stipe thickness and vesicle presence all varied significantly between exposure zones in C. maschalocarpum. C. maschalocarpum specimens were shorter with thinner stipes, and fewer individuals had vesicles in the more wave-exposed zones. Morphological traits of both species also varied between sites, suggesting that other influences are important for determining species morphology. Further study is needed to investigate the role of phenotypic plasticity and genetic variability for driving morphological variation in C. angustifolium and C. maschalocarpum.