• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.48-48
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• 2010

Sound quality and NVH-issues(Noise, Vibration and Harshness) of vehicles has become very important for car manufacturers. It is interpreted as among the most relevant factors regarding perceived product quality, and is important in gaining market advantage. The general sound quality of vehicles was gradually improved over the years. However, today the development cycles in the automotive industry are constantly reduced to meet the customers' demands and to react quickly to market needs. In addition, new drive and fuel concepts, tightened ecological specifications, increase of vehicle classes and increasing diversification(increasing market for niche vehicles), etc. challenge the acoustic engineers trying to develop a pleasant, adequate, harmonious passenger cabin sound. Another aspect concerns the general pressure for reducing emission and fuel consumption, which lead to vehicle weight reductions through material changes also resulting in new noise and vibration conflicts. Furthermore, in the context of alternative powertrains and engine concepts, the new objective is to detect and implement the vehicle sound, tailored to suit the auditory expectations and needs of the target group. New questions must be answered: What are appropriate sounds for hybrid or electric vehicles? How are new vehicle sounds perceived and judged? How can customer-oriented, client-specific target sounds be determined? Which sounds are needed to fulfil the driving task, and so on? Thus, advanced methods and tools are necessary which cope with the increasing complexity of NVH-problems and conflicts and at the same time which cope with the growing expectations regarding the acoustical comfort. Moreover, it is exceedingly important to have already detailed and reliable information about NVH-issues in early design phases to guarantee high quality standards. This requires the use of sophisticated simulation techniques, which allow for the virtual construction and testing of subsystems and/or the whole car in early development stages. The virtual, testing is very important especially with respect to alternative drive concepts(hybrid cars, electric cars, hydrogen fuel cell cars), where complete new NVH-problems and challenges occur which have to be adequately managed right from the beginning. In this context, it is important to mention that the challenge is that all noise contributions from different sources lead to a harmonious, well-balanced overall sound. The optimization of single sources alone does not automatically result in an ideal overall vehicle sound. The paper highlights modern and innovative NVH measurement technologies as well as presents solutions of recent NVH tasks and challenges. Furthermore, future prospects and developments in the field of automotive acoustics are considered and discussed.

• Journal of Industrial Convergence
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• v.20 no.11
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• pp.85-93
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• 2022

As of the end of 2019, the total population nationwide was 51,849,861, and over the past five years, the population per household has decreased by 1.52% annually from 2.45 in 2015 to 2.31 in 2019. Looking at the current status of population distribution by age group, Busan metropolitan city had the highest proportion of senior citizens aged 65 or older at 18.2%, and Sejong Special Self-Governing city had the lowest at 9.4%. In particular, as of 2019, the population of the mobility handicapped was 15,219,000 nationwide, showing a ratio of about 29.4% of the total population. Therefore, it is important to secure the right to move according to the mobile facilities so that the mobility handicapped can move safely and conveniently. Against this background, this study places value on transportation welfare facilities centered on the mobility handicapped for safe and convenient movement, and in particular, in proposing measures to cope with the entry of an aging society and the continuous increase of the mobility handicapped, the transportation facilities, The purpose of this study is to analyze the impact of welfare facilities on the mobility handicapped and suggest implications. As a research method, the results of statistical analysis methods were presented through major preceding studies and expert surveys.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.34 no.6
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• pp.303-314
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• 2022

The persistence analysis of marine physical environment factors is a basic analysis that must precede the use of sea areas as an analysis required in the coastal engineering such as downtime and design. In this study, the persistence analysis was implemented for wind speed and significant wave height data from four observation points of Deokjeokdo, Oeyeondo, Geomundo, and Geojedo among the marine meteorological observation buoys of the Korea Meteorological Administration. The persistence time means the consecutive time of observation data beyond specific level. The threshold wind speed and significant wave height were set in the range of 1~15 m/s and the range of 0.25~3.0 m, respectively. Then, the persistence time was extracted. As a result of the analysis, the persistence time of wind speed and significant wave height decreased rapidly as the reference value increased. The median persistence times under the maximum reference thresholds were assessed as a maximum of 5 hours for wind speed and a maximum of 8 hours for significant wave height. When the reference wind speed and significant wave height were 15 m/s and 3 m, respectively, the persistence time that could occur with a 1% probability were 52 and 56 hours. This study can be expanded to all coastal areas in Korea, and it is expected that various engineering applications by performing a persistence analysis of the metocean data.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.59 no.3
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• pp.206-214
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• 2023

Fish school monitoring technology is utilized for various purposes, such as boat fishing and resource surveys. With advancements in information and communication technology, this technology has expanded its application to remote areas. Its significance has grown in fishing sites, particularly for improving the efficiency and cost-effectiveness of set-net fishing. Set-net fishing gears are not limited to coastal areas, but are also installed in inland and remote sea regions. Consequently, fishermen require technology that allows them to quickly transmit information about approaching fish schools and enables them to perform long-term monitoring. The development of remote monitoring technology for set-net fish schools must consider crucial design factors such as communication range, transmission speed, power consumption of information modules, and operational expenses. In this study, we developed a low-power remote monitoring module for set-net fish school based on WCDMA. The module was specifically designed to minimize power consumption, allowing for communication over long distances and extended operation times in set-net fishing applications. Furthermore, we developed a web server software application that enables remote access to fish schools and provides real-time weather information. The performance of the developed module was evaluated through set-net fishing site application and experiments with moving ships on the sea. The experimental results demonstrated that the remote monitoring system, consisting of the developed low-power remote monitoring module for set-net fish school based on WCDMA and a fish finder, had an average power consumption of 4.6 W, a maximum communication range of 22.84 km, and a data transmission and reception rate of 98.79%. The maximum fish school information transmission and reception rate was 97.26%

• Journal of Korea Entertainment Industry Association
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• v.13 no.2
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• pp.57-65
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• 2019

This study is a scientific approach to psychological factors such as emotional stability among various effects of forest resources. In order to carry out this study, the experiment was conducted on the subjects by setting the forest healing space as various spaces. The subjects who participated in this experiment were the students in their twenties and the average age was 22±1.25 years. The subjects were assessed for emotional words through subjective sequence evaluation in different designated forest healing spot. In addition, the emotional states that they actually perceived were measured by measuring the bio-signals to their perceived emotions. BMP, SDNN, VLF, LF, HF, Amplitude, and PPI were used for the bio-signal reaction experiment applied to this study. The results of this experiment were measured by Friedman test and Wilcoxon test for statistical analysis. n this study, 'good', 'clear', and 'uncomfortable' words were found statistically significant at the spot of forest healing space for subjective emotional vocabulary. In addition, SDNN, HF and Amplitude were statistically significant in the results of quantitative bio-signal measurement at each spot in the forest healing space. Based on the results of this study, we can suggest the application direction and strategic utilization plan of forest healing spot and forest resource utilization field. This is not only a guide for the users who use the facility through the spatial facilities and physical requirements for the emotion based forest-healing, but also can be used as a personalized emotional space design aspect.

• Journal of Korea Entertainment Industry Association
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• v.13 no.4
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• pp.331-339
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• 2019

This study investigated the effects of coaching leadership for life care of estheticians on self-efficacy and job satisfaction and the results are presented as follows: First, as a result of analysing the effects of coaching leadership of the subjects on self-efficacy, it was discovered that all the factors of relations (β=.261, p<.001), presentation of direction(β=.238, p<.01), assessment(β=.175, p<.01) and development(β=.170, p<.01) had a statistically significant positive (+) effect on it. Second, as a result of analysing the effects of coaching leadership of the subjects on job satisfaction, it was discovered that relations(β=.403, p<.001), presentation of direction(β=.384, p<.001) and assessment (β=.170, p<.01) had a statistically significant positive(+) effect on it. Third, as a results of analysing the effects of self-efficacy of the subjects on job satisfaction, it was discovered that self-efficacy (β =.707, p<.001) has a statistically significant positive(+) effect on job satisfaction. Fourth, as for the relations between coaching leadership and job satisfaction, it was discovered that self-efficacy as a mediator of self-efficacy satisfied a partial mediation condition between presentation of direction, development, assessment, relations and job satisfaction.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.2
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• pp.175-186
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• 2023

The buffer materials in disposal hole are exposed to the decay heat from spent nuclear fuels and groundwater inflow through adjacent rockmass. Since understanding of thermal-hydro-mechanical-chemical (T-H-M-C) interaction in buffer material is crucial for predicting their long-term performance and safety of disposal repository, it is necessary to investigate the heating-hydration characteristics and consequent T-H-M-C behavior of the buffer materials under disposal conditions considering geochemical factors. In response, the Korea Atomic Energy Research Institute developed a laboratory-scale 'Lab.THMC' experiment system, which characterizes the T-H-M behavior of buffer materials under different geochemical conditions by analyzing heating-hydration process and stress changes. This technical report introduces the detail design of the Lab.THMC system, summarizes preliminary experimental results, and outlines future research plans.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.1
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• pp.192-207
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• 2023

Commercialization of level-4 (Lv.4) autonomous driving applications requires the definition of a safe road environment under which autonomous vehicles can operate safely. Thus, a risk assessment model is required to determine whether the operation of autonomous vehicles can provide safety to is sufficiently prepared for future real-life traffic problems. Although the risk factors of autonomous vehicles were selected and graded, the decision-making method was applied as qualitative data using a survey of experts in the field of autonomous driving due to the cause of the accident and difficulty in obtaining autonomous driving data. The fuzzy linguistic representation of decision-makers and the fuzzy analytic hierarchy process (AHP), which converts uncertainty into quantitative figures, were implemented to compensate for the AHP shortcomings of the multi-standard decision-making technique. Through the process of deriving the weights of the upper and lower attributes, the road alignment, which is a physical infrastructure, was analyzed as the most important risk factor in the operation risk of autonomous vehicles. In addition, the operation risk of autonomous vehicles was derived through the example of the risk of operating autonomous vehicles for the 5 areas to be evaluated.

• Journal of the Korean Geotechnical Society
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• v.23 no.3
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• pp.25-40
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• 2007

Excessive earth pressure is one of the major mechanical factors in the deformation and damage of Cut-and-Cover Tunnel lining in shallow tunnels and portals of mountain tunnels (Kim, 2000). Excessive earth pressure may be attributed to insufficient compaction and consolidation of backfill material due to self-weight, precipitation and vibration caused by traffic (Komiya et al., 2000; Taylor et al., 1984; Yoo, 1997). Even though there were a lot of tests performed to determine the earth pressure acting on the tunnel lining, unfortunately there were almost no case histories of studies performed to determine remedial measures that reduce differential settlement and excessive earth pressure. In this study the installation of geotextile mat was selected to reduce the differential settlement and excessive earth pressure acting on the cut-and-cover tunnel lining. In order to determine settlement and earth pressure reduction effect (reinforcement effect) of geotextile mat reinforcement, laboratory tunnel model tests were performed. This study was limited to the modeling of rigid circular cut-and-cover tunnel constructed at a depth of $1.0D\sim1.5D$ in loose sandy ground and subjected to a vibration frequency of 100 Hz. Model tests with varying soil cover, mat reinforcement scheme and slope roughness were performed to determine the most effective mat reinforcement scheme. Slope roughness was adjusted by attaching sandpaper #100, #400 and acetate on the cut slope surface. Mat reinforcement effect of each mat reinforcement scheme were presented by the comparison of earth pressure obtained from the unreinforced and mat reinforced model tests. Soil settlement reduction was analyzed and presented using the Picture Analysis Method (Park, 2003).

• Journal of Korea Trade
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• v.26 no.6
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• pp.1-19
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• 2022

Purpose - This study empirically investigates the effects of Official Development Assistance (ODA) on the economic activities of private actors in recipient countries. As a proxy for the economic activities of private actors, we utilize the job creation activities of foreign subsidiaries in recipient countries. The foreign subsidiaries provide a foundation for economic development by creating paying jobs. That is, if ODA has been successfully transferred to foreign subsidiaries, then these foreign subsidiaries should help economic growth and help create a boom in the local market by providing jobs. These jobs eventually lead to the achievement of the primary aims of foreign aid, including poverty reduction. Thus, this study empirically examines the relationship between ODA and the number of jobs created by foreign subsidiaries in recipient countries. Design/methodology - This is the first study to examine the effects of the ODA on the job creation of foreign subsidiaries because it has been hard to obtain internal information related to the employment status of foreign subsidiaries. Fortunately, we have a unique panel dataset provided by the Export-Import Bank of Korea (KEXIM) for 2006 to 2013. In terms of the empirical specification, we use the generalized least squares (GLS) method. The panel GLS estimator allows us to have an efficient estimation that overcomes the limitations of the panel data. It employs assumptions about the heteroscedasticity between the panels and makes an autocorrelation of the error term within each panel. Findings - We find that ODA influences job creation in foreign subsidiaries. In particular, we found that ODA creates more jobs in sales than in managerial or production positions. This study also shows that the effect of the ODA on the foreign subsidiaries' job creation activities depend on the purpose of the ODA. By examining ODA effects on the foreign subsidiaries' economic activities (e.g., job creation), this study fills a gap in the current literature. Originality/value - Existing studies that focus on the ODA effect have either a macroeconomic point or a microeconomic point of view. However, both approaches do not explain how well foreign aid has influenced private economic actors of recipient countries. In essence, previous researchers found it difficult to obtain the necessary data for internal employment status from foreign subsidiaries. However, thanks to the Korea Export-Import Bank, this study shows that ODA indeed influences the job creation activities of foreign subsidiaries even after controlling for other factors such as FDI, GDP growth rate, employment rate, household expenditure, mother firms' share, etc. By doing so, we can examine how ODA influences the job creation of foreign subsidiaries, which might help economic development and reduce the amount of poverty in recipient countries.