• The Journal of the Acoustical Society of Korea
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• v.40 no.6
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• pp.615-625
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• 2021

Prior to proposing appropriate standard for subway station platform, this study conducted field measurements to examine characteristics of room acoustics on platform of two subway stations. As a result of analyzing the longitudinal length of the platform, Sound Pressure Level (SPL) decreased (maximum difference : 14 dB), Reverberation Time (RT) tended to increase (maximum difference of 0.8 s ~ 1.5 s), and C50 and D50 were decreased (maximum difference: 5.9 dB ~ 9.1 dB and 31.8 % ~ 37.6 %, respectively) as measurement positions moved away from the sound source. The Interaural Cross-correlation Coefficient (IACC) did not show clear tendency, but it was lower than 0.3 in entire points. It is judged that the subway platform has non-uniform sound field characteristics due to various combinations of direct and reflective sound even though it is finished with a strong reflective material.This indicates that the room acoustic characteristics of the near and far sound field are clearly expressed depending on the source-receiver distances in the subway platform having a long flat shape with a low height compared to the length.Therefore, detailed architectural and electric acoustic design based on the characteristics of each location of speaker and sound receiver in the platform is required for an acoustic design with clear sound information at all positions of the platform.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.11
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• pp.801-807
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• 2022

In this paper, we propose an ultra compact S-Band PCM/FM telemetry transmitter. The equipment is compact, so it can be applied to a limited space and capable of stable data transmission was designed and manufactured even with specifications set differently for each operating environment and system. RF direct conversion structure is used for the miniaturization of equipment, an RF transmission board, Power distribution board, and a signal processing board were implemented on a single PCB, so that the function of the transmitter could be performed with a minimum device. According to the target specification, variable output of 1~10W and variable data rate of 390kbps~12.5Mbps is possible in S-Band(2,200~2,400MHz) without degradation of performance. To verify the performance of the equipment, the RF performance test and BER measurement test were performed after the equipment was manufactured. It was confirmed that the OBW, null-to-null bandwidth, 1st IMD, Spurious emission, Phase noise specification of the PCM/FM modulated signal which is presented by the IRIG standard were satisfied, and we can confirm the data received using the transmitter inspection equipment were transmitted normally without distortion.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.971-978
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• 2022

As a marketing method in a non-face-to-face society, the purpose of this study is to test how AR experience affects purchase intention in the process of consumers recognizing product information to purchase products and to secure the basis for the effectiveness of developing and introducing augmented reality functions in future product brand applications. Literary research methods and empirical research methods were used to verify the research purpose, and to measure this, an application of domestic tableware brand 'Odense', which implements augmented reality functions, was produced and used as an experimental tool. Also, a direct causal relationship was attempted by constituting a questionnaire by deriving a measurement scale for perceived usefulness, perceived ease, perceived pleasure, and purchase, which are factors of technology acceptance theory (TAM), and empirical analysis was conducted using the SPSS 25.0 statistical package to achieve the purpose of the study. As a result of the study, significant results were derived from all factors in the effect of perceived usefulness, ease, and pleasure on purchase intention, and several significant differences were found among factors according to gender, age, and internet shopping usage time in general characteristics. In conclusion, the user experience of the medium in which the augmented reality function is introduced in the information recognition stage of the product has a positive effect on purchase compared to the user experience of existing applications.

• The Journal of the Acoustical Society of Korea
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• v.42 no.1
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• pp.7-15
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• 2023

Recently, as interest in air quality in vehicles increases, the use of fine dust detection sensors for air quality measurement is becoming common. An axial-flow fan is inserted in the fine dust sensor installed in the air conditioning system in the vehicle to prevent dust from sinking directly on the sensor. When the sensor operates, the flow noise caused by the rotation of the axial-flow fan acts as a major noise source of the fine dust sensor. flow noise is recognized as one of the product competitiveness of fine dust sensors. In this study, the noise was gradually reduced at the same flow rate by improving the flow performance of the small axial flow fan. First, a virtual fan performance tester consisting of about 20 million grids was developed to analyze the aerodynamic performance of the target small axial-flow fan. In addition, the flow field was simulated by using compressible Large Eddy Simulation for direct computation of flow noise as well as high-accurate prediction of flow rate. The validity of numerical method are confirmed through the comparison of predicted results with experimental ones. After the effects of pitch angle on flow performance were analyzed using the verified numerical method, the pitch angle was determined to maximize the flow rate. It was found that the flow rate was increased by 8.1 % and noise was reduced by 0.8 dBA when the axial-flow fan with the optimum pitch angle was used.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.spc
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• pp.18-22
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• 2022

Because it is difficult to apply direct and optical detection techniques to sunken hazardous and noxious substances (HNS), effective acoustic detection techniques are required to detect sunken HNS in water. In this study, the possibility of acoustic detection of sunken HNS was investigated through backscattering signal measurement experiments using chloroform, a sunken HNS. After establishing a pool in an acrylic tank, backscattering signals were measured according to the presences or absence of chloroform by varying the grazing angle from 90° to 50° in 0.5° intervals using a pan&tilt system. A directional transducer transmitted and received sinusoidal signals with a frequency of 200 kHz and a pulse length of 25 ㎲ in a monostatic state. When chloroform was deposited, the received level of the backscattering signal at the interface between water and chloroform became low at a grazing angle of approximately 80° or smaller. Based on the backscattering signal results obtained at the interface between water and chloroform, the possibility of acoustic detection of sunken HNS was demonstrated.

• Clean Technology
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• v.15 no.4
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• pp.258-264
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• 2009

Thermodynamic measurements were performed to show the possibility of recovering $CO_2$ from fuel gas (the mixture of $CO_2$ and $H_2$) by forming gas hydrates with water where water was dispersed in the pores of silica gel particles having nominal 100 nm of pore diameter. The hydrate-phase equilibria for the ternary $CO_2+H_2$+water in pores were measured and $CO_2$ concentrations in vapor and hydrate phase were determined under the hydrate-vapor two phase region at constant 274.15 K. It was shown that the inhibition effect appeared due to silica gel pores, and the corresponding equilibrium dissociation pressures became higher than those of bulk water hydrates at a specific temperature. In addition, direct measurement of $CO_2$ content in the hydrate phase showed that the retrieved gas from the dissociation of hydrate contained more than 95 mol% of $CO_2$ when 42 mol% of $CO_2$ and balanced Hz mixture was applied. Compared with data obtained in case of bulk water hydrates, which showed just 83 mol% of $CO_2$ where 2-stage hydrate slurry reactor was intended to utilize this property, the hydrate formation in porous silica gel has enhanced the feasibility of $CO_2$ separation process. Hydrate formation as not for slurry but solid particle makes it possible to used fixed bed reactor, and can be a merit of well-understood technologies in the industrial field.

• Korea Science and Art Forum
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• v.31
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• pp.171-180
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• 2017

The purpose of this study is to analyze the characteristics of color image for establishing the color environment contributing to the promotion of public health in the public health facilities and to utilize it as data of public health color plan and index development. For this purpose, the results of the previous precedent studies were integrated and public health facilities were classified into medical facilities (general hospitals), health facilities (public health centers), and sub - healing facilities (elderly care facilities). We visited 18 public health facilities in total, measured the environmental color of with a spectroscopic, compared the results and the precedent studies results, and identified color image characteristics and future supplement points. The results are as follows. First, the previous studies related to the environment color image vocabulary of the public health facilities, it prefer comfortable, bright and positive image. Second, as a result of direct measurement the environmental color of the public health facilities, it is found that most of them use the high brightness and low saturation color of Y series. Third, as a result of analyzing vocabulary of environmental color image of public health facilities, 'natural' image showed the highest frequency, and other images such as 'gentle' and 'decent' appeared. It was difficult to understand the characteristics of the color image vocabularies of public health facilities. This study is a convergence study of color science and environmental design, and it extends the scope of multidisciplinary research related to design and it will be helpful in environmental planning on user's emotion.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.34 no.2
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• pp.251-274
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• 2023

This study aimed to examine the mediating effect of positive psychological capital in the relationship between emotional labor and Professional Quality of Life (ProQOL) of librarians belonging to the Widely Representative Library. From February 13, 2023 to February 24, 2023, 159 librarians working in 17 Widely Representative Libraries nationwide were surveyed for general characteristics, emotional labor, ProQOL, and positive psychological capital through questionnaires. For statistical analysis, frequency analysis, descriptive statistics analysis, confirmatory factor analysis, reliability analysis, correlation analysis, and measurement model analysis were conducted using SPSS Statistics 24.0 and Amos 25.0. In addition, the mediating effect of positive psychological capital in the relationship between emotional labor and ProQOL of librarians in the Widely Representative Library was analyzed using a bootstrapping analysis method. The results of this study are summarized as follows. First, it was found that there was a significant effect among librarians' emotional labor, ProQOL, and positive psychological capital in the Widely Representative Library. Second, the indirect effect of positive psychological capital in the relationship between Emotional Labor and ProQOL of Widely Representative Library librarians was found to be statistically significant. In other words, considering the direct effect of emotional labor on ProQOL, it can be inferred that there is a partial mediating effect. Therefore, it is suggested to develop a program that can improve the quality of professional life by reducing emotional labor and strengthening the positive psychological capital of librarians in further studies.

• Analytical Science and Technology
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• v.19 no.5
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• pp.400-406
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• 2006

Hydrogen analysis by elastic recoil detection has been performed utilizing polyimide film as a reference sample of known hydrogen content assuming the soundness of ion beam current integration. However beam current integration at higher incidence angle is not reliable. Scattering yield per unit fluence by current integration which is normalized per unit path length decreases as the sample tilt angle is getting higher. Moreover because beam current integration at high tilt angle is incomplete, hydrogen evaluation is very risky by direct comparison of sequentially collected recoil spectra between reference and target sample. In this study, primary ion beam dose is determined by backscattering spectrum that is collected simultaneously with recoil spectrum instead of ion beam current integration in order to reduce uncertainty arising in the process of current integration and to enhance the reliability of quantitative analysis. Three test samples are selected $-7.6{\mu}m$ polyimide film, hydrogen implanted silicondioxide and Au deposited carbon wafer- and analyzed by two methods and compared.

• Korean Journal of Culture and Social Issue
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• v.20 no.2
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• pp.133-154
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• 2014

The purpose of this study was to investigate psychological processes based on the Korean college students' development of social justice interest and commitment. For this study, we replicated Miller and colleagues'(2009) study, which explained the development of social justice interest and commitment by social-cognitive career theory(SCCT). Social desirability was controlled, and then self-reports data from 343 college students were analyzed using Structural Estimate Modeling(SEM). As a result, the final research model that social justice self-efficacy and outcome expectations affect social justice interest and commitment was proven valid for Korean college students. Also, in comparison with the direct effects model(social supports and barriers affect directly on commitment), the indirect effects model(social supports and barriers affect indirectly on commitment through self-efficacy) was supported. As an unique path of social-justice domain, the indirect effect by social support on commitment through outcome expectation was proved, as well. This study covers measurement limitations, future directions for research, and some lessons points with regards to how Korean college students to have social justice interest and commitment.