• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.23 no.7
• /
• pp.645-653
• /
• 2013

Seoul National University flap(SNUF) blade is a small-scale rotor blade incorporating a small trailing-edge flap control surface driven by piezoelectric actuators at higher harmonics for vibration attenuation. Initially, the blade was designed using two-dimensional cross-section analysis and geometrically exact one-dimensional beam analysis, and its material configuration was finalized. A flap-deflection angle of ${\pm}4^{\circ}$ was established as the criterion for enhanced vibration reduction based on an earlier simulation. The flap-linkage mechanism was designed and static bench tests were conducted for verifying the performance of the flap-actuation mechanism. Different versions of test beds were developed and tested with the designed flap and the selected APA 200M piezoelectric actuators. Through significant improvements, a maximum deflection of ${\pm}3.7^{\circ}$ was achieved. High-frequency experiments were conducted for evaluating the performance, and the transfer function of the test bed was determined experimentally. With the static tests almost complete, the rotor power required for testing the blade in a whirl tower (centrifugal environment) was calculated, and further preparations are underway.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.36 no.3
• /
• pp.195-201
• /
• 2016

Eddy current testing (ECT) is commonly applied for the inspection of automated production lines of metallic products, because it has a high inspection speed and a reasonable price. When ECT is applied for the inspection of a metallic object having an uneven target surface, such as the spline gear of a spline shaft, it is difficult to distinguish between the original signal obtained from the sensor and the signal generated by a defect because of the relatively large surface signals having similar frequency distributions. To facilitate the detection of defect signals from the spline gear, implementation of high-order filters is essential, so that the fault signals can be distinguished from the surrounding noise signals, and simultaneously, the pass-band of the filter can be adjusted according to the status of each production line and the object to be inspected. We will examine the infinite impulse filters (IIR filters) available for implementing an advanced filter for ECT, and attempt to detect the flaw signals through optimization of system design parameters for detecting the signals at the system level.

• Journal of Distribution Science
• /
• v.12 no.8
• /
• pp.17-29
• /
• 2014

Purpose - The use of corporate social activities to implement the concept of corporate social responsibility enhances brand equity and attitude, and strengthens economic competitiveness. In areas such as mobile communications, companies take the responsibility of protecting customers and enhance the quality of the mobile communication service, helping to make an effort to obey the regulations of the public trade order and fair trade agreement, enabling a healthy society through communication with elderly living alone or youths without parents, and enhancing marketing strategies. Research design, data, and methodology - To test the hypothesis, a survey was conducted. The surveyed population includes people who use the big three mobile communication services. The survey was conducted from October 4th to October 14th, 2013. A total of 500 survey questionnaires were circulated and 483 were collected; out of these, 32 were excluded due to missing or incomprehensible information. The data was analyzed with SPSS 18.0 via frequency analysis, trust analysis, search factor analysis, relationship analysis, confirmation factor analysis using AMOS 18.0, and structural equation model analysis. Results - Research on corporate social responsibility has been frequently conducted recently. Companies are perceived as social constituents satisfying the social desires of people in addition to customer needs. Further, companies are returning profits to society to satisfy community needs, because there is greater emphasis on the social responsibilities of companies. Companies' social responsibilities should include marketing strategies and the identification of customer needs. This study shows that social service activities influence brand value, which influences customer attitudes; therefore, social service activities indirectly influence customer attitudes. In order to increase customers' purchasing intention, it is essential to improve brand image via social services and provide a distinctive quality of service. Conclusions - This research has used the purposive selection method in the empirical analysis to identify the effect of social services on brand value and customer attitude. Therefore, this study revealed that businesses, whose ultimate objective is to improve customers' purchasing intention, should promote their brand equity through corporate social responsibility activities and offer a distinct service quality. Limitations in the progress of research were found and future indications to overcome these limitations are suggested as follows. First, survey responders had a limited understanding of social responsibilities; therefore, this concept needs to be explained to people first. Second, the research was done on people who live in Daejeon; thus, it is not representative of the entire country. The research has to be repeated with people in other cities. Third, there is a limitation in the study because the purposive selection method was used on Daejeon customers. In the future, a more precise selection of the population is needed. Fourth, Daejeon has unique geographical and size characteristics. Thus, customers in Seoul and other areas may display different characteristics and research on them may reveal different findings. Therefore, again, this study has to be repeated in other areas.

• Journal of Distribution Science
• /
• v.12 no.8
• /
• pp.103-112
• /
• 2014

Purpose - There have been local government systems since June 1955. Many local governments have made use of festivals for regional public relations and the achievement of competitiveness. This study analyzes effective components of local festivals. There has been extensive research in relation to variables such as participation motivation, satisfaction level, recall intention, royalty, and recommend purpose. However, as a variable factor, attachment to the participation motivation of a festival has been overlooked along with support level to a festival. This study has added new variables named "attachment to local society" and "support level," which are dependent variables. We will study the relationship of these two variables. Research design, data, and methodology - This study has devised a cause-and-effect relationship model, which deduces that local residents' participation motivation for the festival will have positive influence on the festival support level and satisfaction level. We circulated questionnaires to local residents to get the data required to prove the hypothesis. To analysis the data, we used SPSS 21.0, and accomplished basic analysis through the analysis of frequency as well as descriptive statistical analysis. Further, we verified our measurement tools through reliability analysis, and examined the research hypothesis through multiple regression analysis. Results - With regard to the festival satisfaction level, the variables of local society attachment, festival attraction, escaping from the daily life, and family harmony have influence upon a positive effect (+) in this order. Among them, the variable of local society attachment has the greatest influence. However, in respect of support level for the festival, only the variables of local society attachment and escaping from the daily life have a valid influence on the positive effect (+), and local society attachment has relatively greater influence. In addition, not only does the festival satisfaction level affect the support level for the festival in terms of positive effect, the influence is also far-reaching, which verifies the mediating effect. Conclusions - The result shows that the local residents' satisfaction level with the Yudalsan Mountain Spring Flower Festival is comparatively high, which is due to the local society attachment. It also shows that it is difficult to create support without local residents' attachment with their area. Consequently, this study insists that the Yudalsan Mountain Spring Flower Festival should exceed its limitation as just a village-level party, in order to become a remarkable and outstanding festival, and suggests three operational implications: macro-environmental development, task environment development, and internal operational environmental development. From the macro-environmental perspective, the constant development of local culture and local business is proposed. In the task environment perspective, a new functional development for the festival is proposed. From the internal operational environmental perspective, improvements in festival operation methods are proposed. If these weak points are addressed and resolved through a more detailed approach, it will be very helpful for local government systems to operate the festival.

• The Journal of Industrial Distribution & Business
• /
• v.10 no.10
• /
• pp.35-44
• /
• 2019

Purpose - This study focuses on the continuance intention of O2O fresh agricultural products e-commerce. By literature review, this paper looks through the classical theories which are often applied to study use behavior and continuance intention on the electronic commerce area. Ultimately based on the expectancy theory, Technology acceptance model, success model as well as trust model, a model of the continuance intention of fresh products O2O electronic commerce application is established. Research design, data, and methodology - Among users Chinese consumers have been chosen who have use experience as the research objects. From October 2, 2018 to November 2, 2018, 685 questionnaires in total were collected by the online release and collection. Expect for the negative questionnaires, the remaining 650 pieces of data are statistically analyzed. The collected data were firstly be analyzed by SPSS Ver. 25 on its frequency, reliability and exploratory factors. Then AMOS Ver. 25 is applied to the Confirmatory Factor Analysis, Discriminant Validity and hypothesis testing of the Structural Equation Modeling. Finally, the following research conclusions could be obtained from the hypothesis testing. Results - Firstly, in the extended IS model, quality factor for hypothesis testing, service quality, information quality and delivery quality have obviously present positive influences on satisfaction respectively. Secondly, in the hypothesis testing part of ECM-ISC model and UTAUT model, all hypotheses have presented accepted results. Especially from expectation confirmation to usefulness perception, the influence factor achieves 12.603, In the hypothesis of continuance intention, the influence factor of social influence on continuance intention is 7.748 and also it is the most remarkable one. Conclusions - The results show that the service quality of O2O fresh agricultural products e-commerce has the greatest impact on satisfaction, while the perceived usefulness of consumers has the most significant impact on O2O fresh agricultural products for sustainable use intention. This thesis makes up for the blank of O2O fresh food e-commerce for sustainable use intentions, and provides a theoretical basis for consumers' sustainable use behavior, and practical enlightenment for the sustainable development of O2O fresh agricultural products e-commerce.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.22 no.3
• /
• pp.293-310
• /
• 2020

The purpose of this study is to present the most effective smoke exhaust mode by comparing the quantitatively evaluated risks according to the smoke exhaust mode when a train fire occurs in a subway platform. Therefore, applying the typical subway platform as a model, train fire scenarios are developed with the evacuation start time and location of the fire train for each exhaust mode. The fire accident rates (F) are calculated and the number of fatalities (N) was quantitatively estimated by fire analysis and evacuation analysis for each scenario. In addition, the F/N curve compared with the social risk assessment criteria and the following conclusions were obtained. In the event of a train fire at the subway station platform, the evacuation must start up within 600 s in maximum to ensure the evacuees' safety. To secure evacuation safety, it is advantageous to operate the HVAC system of the platform in the air-supply mode at station without TVF. Comparing the F/N curve for each exhaust mode with the social risk criteria, it turned out that the risk significantly exceeds the social risk criteria in case of no mechanical ventilation. As a result, this paper shows that the ventilation mode in which TVF are exhausted and HVAC system is operated in the pressurized mode are the most effective smoke exhaust mode for ensuring evacuation safety.

• Korean Journal of Remote Sensing
• /
• v.24 no.2
• /
• pp.99-106
• /
• 2008

A synthetic aperture radar (SAR) system is of great interest in many fields of civil and military applications because of all-weather and luminance free imaging capability. SAR image quality parameters such as spatial resolution, peak to sidelobe ratio (PSLR), and integrated sidelobe ratio (ISLR) can be normally estimated by modeling of impulse response function (IRF) which is obtained from various system design parameters such as altitude, operational frequency, PRF, etc. In modeling of IRF, however, background clutter environment surrounding the IRF is generally neglected. In this paper, analysis method for SAR mage quality is proposed in the real background clutter environment. First of all, SAR raw data of a point scatterer is generated based on various system parameters. Secondly, the generated raw data can be focused to ideal IRF by range Doppler algorithm (RDA). Finally, background clutter obtained from image of currently operating SAR system is applied to IRF. In addition, image quality is precisely analyzed by zooming and interpolation method for effective extraction of IRF, and then the effect of proposed methodology is presented with several simulation results under the assumption of estimation error of Doppler rate.

• Journal of the Korea Society of Computer and Information
• /
• v.24 no.10
• /
• pp.139-147
• /
• 2019

In this paper, we propose to explore ways to create internal motivation to enhance the job disposition of Korean and Chinese employees. In order to achieve this goal, we would like to select parameters that may trigger an increasing number of internal motivations for interest in recent years: perceived organisational support, perceived provider support, and perceived peer support, and to explore the impact on job embeddedness. I would like to find out the effect of job embodiedness on involved beauty. The process also seeks to verify that China and South Korea are different. To verify the research theory of this research, we will use a questionnaire to researchers of automotive companies using VR technology in Gyeonggi-do, Korea and Hadong-seong, China, and conducted a survey. A total of 200 pairs of questionnaires were distributed to the study subjects, 195 of which were retrieved, 191 of which eliminated unfaithful responses were used for the final analysis. The collected data were used for frequency analysis, exploratory factor analysis, reliability analysis, confirmatory factor analysis, correlation analysis, structural equation analysis. The results of this study, identified through empirical analysis, can be summarized as follows: First, Perceived Organizational Support, Perceived Supervisor Support will have a positive impact on Job Embeddedness. Second, Job Embeddedness will have a positive influence on the Innovative Beehivior. Third, Perceived Organizational Support, Perceived Supervisor Support will have a partial positive effect on Innovative Behavior. Fourth, the formation process and influence of Job Embeddedness of corporate employees in Korea and China are partly different, the report showed.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.24 no.4
• /
• pp.489-495
• /
• 2018

In this paper, we designed and fabricated WLAN / UWB communication antennas operating at 3.3 [GHz] and 5 [GHz] bands in order to effectively use the high-speed communication network system that improved antenna miniaturization, gain and radiation pattern. Microstrip patch antennas were chosen to improve the bandwidth. The slot width, length, and transmission line width were calculated using the theoretical formula for each step. Simulation results show that the return loss is -14.053 [dB] at 3.3 [GHz] and -13.118 [dB] at 5 [GHz]. The gain showed a value of 2.479 [dBi] at 3.3 [GHz] and a value of 3.317 [dBi] at 5 [GHz]. After optimizing it with the CST Microwave Studio 2014 program, which can be 3D-designed, Based on these results, we investigated the performance of antennas by measuring their characteristics. In recent years, WLAN, which is a variety of wireless technologies that are continuously developing, and UWB, which is a communication technology which is increasing in frequency band due to an increase in demand of the technology users, is used for a high speed wireless communication system. Communication seems to be possible.

• Journal of Aerospace System Engineering
• /
• v.15 no.5
• /
• pp.8-15
• /
• 2021

This paper describes a design method using an optimization technique to satisfy the longitudinal handling quality of high maneuverable jet aircraft. The dynamic inversion technique was applied to the target aircraft, and the control gain optimization satisfied the longitudinal short-period handling quality, however, the stability margin was not considered. If the stability margin is not satisfied, it is necessary to directly readjust the gains through trial and error methods for improvement. To improve this, an additional compensator and an optimization constraint were added to the control gain optimization procedure. In addition, the degree of handling quality satisfaction with the optimization result was reevaluated, and additional control evaluation criteria for the convergence of the time response and the steady state error that the flight performance requirement set as the optimization constraint cannot be reflected, and the results are described.