• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.137-142
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• 2009

Impact noise is induced in a car when it is driven on a harsh road or over some bumps. This noise occurs with the very high level of sound, which affects passengers in some way or other. Although it is impossible to clearly remove such noise. It is necessary to research an improvement in sound quality for impact noise. A new sound metric for impact sound is presented in the previous work. This metric is verified by comparison between mean subjective ratings and several sound metrics. In this paper, more objective attributes are considered, which are the attributes expressing the level and modulation of sound. Three sound metrics are employed to get impact sound indexes for each course by the method of multiple linear regressions. The indexes are verified by considering the correlation between the estimated values from the multiple linear regressions and the mean subjective ratings by evaluators. Also, the subjective ratings on the indexes are estimated for the case in which some parts of suspension system are changed. The estimated ratings represent more reasonable or acceptable ratings. Thus, such indexes can be used for modification of the parts of suspension system under considering a good sound quality.

• Journal of Music and Human Behavior
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• v.21 no.2
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• pp.107-134
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• 2024

This study aims to classify the semantic words commonly used to evaluate sound quality and to analyze their differences in reflecting the level of musical stimuli. Participants were thirty-one music majors in their 20s and 30s, with an average of 9.4 years of professional training. Each participant listened to nine pieces of music with variations in texture and instrument type and evaluated them using 18 pairs of semantic words describing sound quality. A factor analysis was conducted to group words influenced by the same latent factor, and a multivariate ANOVA determined the differences in ratings based on texture and instrument type. Radar charts were also drawn based on the identified sets of semantic words. The results showed that four factors were identified, and the word pairs 'soft-hard,' 'dull-sharp,' 'muddy-clean' and 'low-high' showed significant differences based on the level of musical stimuli. The radar charts effectively distinguished the sound quality evaluations for each music. These results indicate that developing Korean semantic words for sound quality evaluation requires a structure different from the previous categories used in Western countries and that linguistic and cultural factors are crucial. This study will provide foundational data for developing a verbal sound quality evaluation framework suited to the Korean context, while reflecting acoustic attributes in music listening.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.689-692
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• 2008

Noises from ceiling mounted air-conditioning units were recorded in various actual situations such as offices, classrooms and libraries. Eight specimens of air-conditioners from major domestic and foreign manufacturers' were investigated in this study. A head and torso simulator was located 1.5 m beneath the air-conditioner panel for the measurements and sound pressure levels of the recording sounds were varied from 28 to 55 dBA with 3 dB steps for subjective evaluations. A total of 88 stimuli was randomly presented to subjects using a headphone system in semi-anechoic chamber. Two-categorized (noisiness and amenity) nine-point scale was used as evaluation method. The third scale ('point 3') among the nine-point scale was set as the threshold of allowable level of the air-conditioning sounds in consideration of the real situations. The results indicate that the allowable sound pressure level is around 34 dBA for both noisiness and amenity categories.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1442-1445
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• 2007

Just noticeable differences (jnds) of autocorrelation function (ACF) parameters - Phi (0), Tau 1 and Phi 1 - of household refrigerator noise were investigated by psychoacoustical analyses. Phi (0) of five refrigerators' noise was changed with equal (${\pm}$) interval level of 0.5-1.0 dB up to five intervals by manipulating sound pressure level of the noise. Tau 1 and Phi 1 were varied with equal (${\pm}$) interval of around 0.10 ms and 0.02, respectively. Pitch shifting and strengthen methods were applied for the Tau 1 and Phi 1 variations. As results of subjective evaluations, about 2.0 dB was shown as jnd of Phi (0). The values of 0.30 ms and 0.06 were found as jnds of Tau 1 and Phi 1, respectively. The jnd results of each ACF parameter can be applied to explain substantial amount of sound quality (SQ) enhancement in the SQ prediction indices which were proposed in the authors' previous study [Sato et al. (2007) J. Acoust. Soc. Am.].

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.43-43
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• 2010

Presently, there is the dilemma of uncertainty with respect to the evaluation of sound and vibration based on the fact that there is obviously no agreement upon appropriate methods to measure the "truth" concerning the acceptance of sound and vibration. To evaluate properly physical and perception data in sound and vibration it is necessary to implement new methods and innovative approaches to understand the input of human response in sound design. Fortunately, an elaborate dialogue of the usefulness and applicability of those approaches is in progress. Moreover, the need of using and combining perception and physical data in order to comprehend the process of human perception and evaluation sufficiently is widely accepted. However, still the question remains how the goal of an adequate combination can be achieved. Clearly, themultidimensional human perception cannot be easily reduced to singular numbers. Moreover, factors, among others the meaning of the sound, the composition of the diverse sound sources, the listener's attitude, expectations and experiences, are significant parameters which have to be considered to comprehend the different perceptions and evaluations with regard to specific stimuli. Taking under consideration the physical, psychological, and cognitive dimensions as well as the integration of aspects of design require partially various new approaches. While binaural measurement and analysis technologies and psycho-acoustics are well established as they are proved to be valuable auxiliary tools; it has not been achieved to develop generally acceptable measurement units concerning sound quality. Consequently, there is a need for new approaches and methods which make it possible to comprehend sufficiently the process of perception and evaluation. Going with people's mind will be one solution for the future; thisconcept will be introduced based on the development in sound design.

• Journal of the Korean Dietetic Association
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• v.10 no.1
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• pp.47-57
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• 2004

The sound dietary habit is formed in childhood, which is basic foundation for keeping health. The school foodservice is practiced to provide proper nutritions, to establish the sound dietary habit. Continuous evaluation and improvement are necessary to operate school foodservice effectively. This study was conducted to evaluate the quality of meals served in elementary school based on nutrient content, food diversity. A questionnaire was mailed to dietitian of each school requested for menus of one week. Menus served in 77 schools from each province and major cities in Korea were analyzed. The results of this study were summarized as follows; Compared to 1/3 of RDA for children, many schools provide lower amounts of energy, calcium and Vitamin A. Proportions of energy from carbohydrate, protein and fat were 59.64%, 17.43% and 20.11%, respectively and were not significantly different by the area, the foodservice system, and the number of persons served. NAR(nutrient adequacy ratio) were lowest for calcium(0.67) and Vitamin A(0.65). MAR(mean adequacy ratio) was 0.83. The results of comparison of NAR and MAR by the area, the foodservice system, and the number of persons served were similar to those of nutrient contents. Comparing foods served by the nutrient density were different by nutrient contents, NAR and MAR. Mean nutrient density per meal were higher in large cities than in small cities and rural area, in conventional than in commissary foodservice system. Mean number of dishes and food items per meal were 5.86 and 19.87, respectively. The mean of total quantity of each food group per meal was 352g. The mean of total quantity of each food group per meal were higher in small cities and rural area than in large cities, in commissary than in conventional foodservice system. This study is based only on served menus, and the evaluations of meals based on actual consumption of children are needed. These results suggest that in order to improve the quality of school food service, realistic standard should be suggested and basic study should be done continuously.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.26 no.4
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• pp.35-50
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• 2023

As urbanization progresses, there is a growing and continuous demand for green spaces that provide ecosystem services. However, increasing the quantity of green spaces within major cities is challenging. Therefore, it is essential to pursue qualitative improvements that consider ecological characteristics of existing green spaces. In this study, we focus on local neighborhood parks in Seoul and present the following two questions through an evaluation utilizing ecological design indicators and land use data: 1. Which factor, design or location, has a greater influence on the ecological quality of neighborhood parks in Seoul? 2. Additionally, when evaluating ecological characteristics, is there similarity between assessments based on land-use data and those utilizing ecological design indicators? For this study, we conducted research on 30 neighborhood parks in Seoul and classified them into mountainous types (adjacent to mountains, natural terrain parks) and urban types (independently designed within 300m without existing forests) based on previous studies. Firstly, we conducted evaluations according to park location types. When comparing the evaluation scores of urban types (14 parks) and mountainous types (16 parks), significant differences were observed with scores of 16.86 and 35.94, respectively. Statistical analysis showed a significant difference between park types. In terms of habitat quality, the average values for urban and mountainous parks were 0.33 and 0.53, respectively, and statistically significant differences were observed between park types indicating differences in ecological potential according to park location. Secondly, when comparing the results of ecological potential evaluations based on park design and external connectivity, a correlation was found between habitat quality and total scores according to evaluation indicators. The correlation analysis showed significant linear relationships between habitat quality and total scores, biodiversity scores, and ecosystem function scores, with high positive correlation coefficients of 0.829, 0.861, and 0.802, respectively. This study holds significance in analyzing the ecological aspects of urban parks through the lens of both park location characteristics and design indicators. The analysis results underscore the importance of planning and managing ecologically sound urban parks contingent upon their location. Moreover, the utilization of appropriate ecological design indicators can help alleviate environmental limitations surrounding parks. Integrating these considerations could enhance the ecological quality and ecosystem services of urban green spaces.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.115-120
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• 2018

This study examined the cast quality of small-sized induction motor rotors during the die casting process. Numerical analyses with 3-dimensional half models were performed to investigate the filling patterns of aluminum molten metals into a mold after high-speed injections. The following were obtained from numerical analyses and experimental results. First, molten metals started to fill the lower end ring, then moved horizontally to fill the core slot and upper end ring, and finally stopped to fill the rotor core slot. Second, circulation of molten metals occurred at the lower end ring, resulting considerable porosity at the section of lower end ring from the experimental results. Third, further work for obtaining sound quality of rotor core cast is required to develop a new shape of the rotor core cast or improve the die casting conditions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.347-352
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• 2019

This study focused on improving the cast quality of small-sized induction motor rotors during the die casting process. A new rotor core cast model was proposed based on previous research results and parametric studies. Numerical analyses using 3-dimensional half models were performed to evaluate the filling patterns of aluminum molten metals into a mold and on-site experiment performed to verify the newly proposed cast model. The following were obtained from numerical filling analyses and experimental results. First, molten metals started to fill the lower end ring, then moved on to fill the core slot and upper end ring and finally stopped to fill at the rotor core slot. Second, significant circulation of molten metals was not observed on the lower end ring, resulting in fewer defects at the section of the lower end ring from the experimental results. Third, the new shape of a rotor core cast was effective in producing rotors with sound cast quality, and reducing the end ring cast defect area by approximately 70 %.

• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.675-681
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• 2021

Recently, the Ministry of Education stipulates in the distance class operation regulations that student lecture evaluations for distance learning subjects should be conducted at least twice per semester and the results should be disclosed to students. Therefore, the lecture evaluation of D college was compared with the first semester of 2020 and the first semester of 2021. As for the multiple-choice evaluation result of the distance learning mid-course evaluation, the overall average of the mid-course evaluation of the distance class in the first semester of 2020 increased from 4.1819 to 4.4000 in the mid-course evaluation in the first semester of 2021.In the case of the first semester of 2020, due to Corona 19, all non-face-to-face classes were held, but in the first semester of 2021, face-to-face classes increased. The overall satisfaction level rose from 4.18 points in the first semester of 2020 to 4.39 points in the first semester of 2021. The screen composition, sound and picture quality, playback time, face appearance, lecture material provision, and frequency of use of the top 3% and bottom 3% also increased. Despite the changes caused by the LMS replacement, which was a concern, student attendance, assignments, and test submission rates also increased compared to the previous year. The null hypothesis that 'the difference between the two scores is the same' is the null hypothesis because the probability of significance is 0.000 and less than 0.05 in the case of the best 3% of the test result of the test result of the mid-course evaluation of distance classes in the first semester of 2020 and the evaluation of the intermediate lectures in the first semester of 2021. As this was rejected, it can be seen that the best score for the 2021 school year has significantly increased compared to the first semester of 2020. Also, in the case of Worst 3% or less, the significance probability is 0.000, which is less than 0.05, so the null hypothesis that 'the difference between the two scores is the same' was rejected, indicating that the Worst score for the 2021 school year was significantly higher than that for the first semester of 2020.