• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.166-172
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• 2019

A case study was performed in order to develop well-designed of thin plate door impact beam. The conventional impact beam was consisted of steel-pipe welded two brackets on the both side, which causes low productivity and high cost. In order to overcome those disadvantage, it is necessary to develop a new type of door impact; thin plate impact beam. The thin plate impact beam was not needed a welding procedure, which can lead low cost and high productivity. In order to maximally resist from an external force, the cross-section design should be well designed. 6 different cross-section design were proposed based on engineer's experience. Three point bending test was simulated those 6 different impact beam and compared the reaction forces. Among them, one case was chosen and redesigned for detail design.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.361-364
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• 2003

The safe operation and reliable maintenance of nuclear power plants is one of the most fundamental and important tasks. It is known that a loose part such as a disengaged and drifting metal inside of reactor coolant systems might lead to a serious damage because of their impact on the components of the coolant system. In order to estimate the impact position of a loose par, three accelerometers attached to the wall of the coolant system have been used. These accelerometers measure the vibration of the coolant system induced by loose part impact. In the conventional analysis system, the low pass filtered version of the vibration data was used for the estimation of the position of a loose part. It is often difficult to identify the initial point of the impact signal by using just a low passed time signal because the impact wave is dispersed during propagation into the sensor. In this paper, the impact signal is analysed by use of various time frequency methods including the short time Fourier transform(STFT), the wavelet transform, and the Wigner-Vill distribution for finding a convenient way to identify the starting point of a impact signal and their advantages and limits are discussed.

• Journal of Positioning, Navigation, and Timing
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• v.12 no.2
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• pp.157-166
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• 2023

Several experiments were carried out to analyze the impact of the modernized Global Positioning System (GPS) L2C signal on pseudorange-based point positioning. Three dual-frequency positioning algorithms, ionosphere-free linear combination, ionospheric error estimation, and simple integration, were used, and the results were compared with those of Standard Point Positioning (SPP). An analysis was conducted to determine the characteristics of each dual-frequency positioning method, the impact of the magnitude of ionospheric error, and receiver grade. Ionosphere-free and ionospheric error estimation methods can provide improved positioning accuracy relative to SPP because they are able to significantly reduce the ionospheric error. However, this result was possible only when the ionospheric error reduction effect was greater than the disadvantage of these dual-frequency positioning algorithms such as the increment of multipath and noise, impact of uncertainty of unknown parameter estimation. The RMSE of the simple integration algorithm was larger than that of SPP, because of the remaining ionospheric error. Even though the receiver grade was different, similar results were observed.

• Journal of Korean Society for Atmospheric Environment
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• v.9 no.2
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• pp.168-173
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• 1993

Air quality impacts of point and area sources were analyzed by using ISCST2 with wind speed and stability class combinations of SCREEN. Stack height was important in determining the impact of point sources. With the stack height reduced to 21m from 75m, the concentration in the vicinity increased several times in spite of decreasing the emission rate by half. When the emission rates were same, concentrations from an area source of 10m release height were slightly lower than those from a point source of 21m stack height at the plume centerline. Bur the area source resulted in larger area of high concentration. Concentration from the point source was high in neutral to slightly unstable conditions with strong winds in a short distance, and in stable conditions with weak winds in a long distance. Concentration from the area source decreased with distance from the source, and was high in stable conditions with weak winds.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.6
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• pp.1836-1842
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• 1996

In this paper, static and fatigue bending strengths of CFRP(carbon fiber reinforced plastic laminates having impact damage(FOD) are evaluated. Composite laminates used for this experiment are CF/EPOXY and CF/PEEK orthotropy laminated plates, which have two-interfaces[${0^0}_4{90^0}_4}$]$_sym$. A steel ball launched by the air gun colides against CFRP laminates to generate impact damages. The damage growth during bending fatigue test is observed by the scanning acoustic microscope(SAM). When the impacted side is compressed, the residual fatigue bending strength of CF/PEEK specimen P is greater that that of CF/EPOXY SPECIMEN B. On the other hand, when the impacted side is in tension, the residual fatigue bending strength of CF/PEEK speicemen P is smaller than that of CF/EPOXY specimen B. In the case of impacted-side compression, fracture is proposed from the transverse crack generated near impact point. On the other hand, fracture is developed toward the impact point from the edge of interface-b delamination in the case of impacted-side tension.

• Journal of Environmental Impact Assessment
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• v.3 no.1
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• pp.31-41
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• 1994

The choice of economic development over environmental protection has been used to explain the decline in the quality of the environment in developing countries. The authors reject this explanation and propose a theory of negligence to explain this decline. They point to the advantages of environmental impact assessments in dealing with the problem of negligence and presents case studies from four countries. Organizational models for Environmental Impact Assessments in Developing Countries are proposed as useful policy measures.

• Journal of Distribution Science
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• v.12 no.2
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• pp.81-93
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• 2014

Purpose - Recent rapid environmental changes in the hospital industry are accelerating the spread of customer satisfaction management. Customers' desires have become diversified and advanced; in the past, customers tended to preferred popularized and standardized care, whereas they now prefer individualized and differentiated care, based on an increase in income. Specifically, this study tries to analyze the mediating effects of factors that affect the configuration portion of customer value and relationship quality (customer trust and relationship commitment) by investigating the impacts and configuration factor of customer value on relationship quality and determining how these factors impact customer loyalty directly or indirectly. Research design, data, and methodology - This study aims to determine the customer value factors that impact the perceptions of dental hospital customers, how these factors impact relationship quality and customer loyalty, and the causal relationship of these factors, and to verify the research model based on previous research. To increase the validity and reliability of the questionnaire, the authors of this study constructed basic questions using measurement tools already verified for reliability and validity in existing studies. In this study, customer value is defined as customers' recognizing value by exchanging goods or services and is measured using a five-point Likert scale using 19 questions about the 4-Ds, such as convenience value, quick service, response value, and trustworthiness. For each question, "very low" was set at 1 point and "very high" at 5 points. Customer trust, relationship commitment, and customer loyalty are also measured using a five-point Likert 5-point scale (1 = very low, 5 = very high) based on previous studies. Results - For customer value, trustworthiness and quick service are shown to have direct significant positive impacts on customer loyalty. For customer value and quality of the relationship (customer confidence and commitment), trustworthiness, response value, confidence value, and quick service are shown to have a significant positive impact on customer truth, in order of impact. For the relationship between customer value and commitment, quick service and response value are shown to have significant positive impact. Customer confidence has a very high positive influence on commitment. For the relationship between the quality of the relationship (customer confidence and commitment) and customer loyalty, customer confidence is shown to have more of an impact than commitment, in terms of a direct influence of customer loyalty. Commitment showed a positive impact on customer loyalty. For the relationship between customer confidence and customer loyalty, commitment showed a mediating effect. Conclusions - Many additional variables could apply; this study focused on customer value, quality of the relationship, and customer loyalty. In particular, there will be significant value in identifying the relationships among customer value, relationship quality, and customer loyalty by using impact factors for customer value; ensuring external validity by expanding denotation and applying the findings to other service industries; and undertaking continuous research. This study has limited generalization potential because the target for this survey was located only in the Seoul area.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.5
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• pp.835-842
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• 2002

In this paper, static and fatigue bending strengths and failure mechanisms of CFRP (carbon fiber reinforced plastics) laminates having impact damages have been evaluated. Composite laminates used for this experiment are CF/EPOXY orthotropy laminated plates, which have two-interfaces $[0^0_ 4/90^0_4]_{ sym}$. A steel ball launched by the air gun collides against CFRP laminates to generate impact damages. The damage growth during bending fatigue test is observed by the scanning acoustic microscope (SAM) and also, the fracture surfaces were observed by using the SEM (scanning electron microscope). In the case of impacted-side compression, fracture is propagated from the transverse crack generated near impact point. On the other hand, fracture is developed toward the impact point from the edge of interface-B delamination in the case of impacted-side tension. Eventually, failure mechanisms have been confirmed based on the observed delamination areas and fracture surfaces.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.8
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• pp.681-688
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• 2021

This paper considers the trajectory and impact point dispersion analysis of the test launch vehicle (TLV). The analysis, which performed before and after its flight test on November 28, 2018, is described and verified by comparing with the flight test results. The six degree-offreedom (DOF) simulation is used to compute the dispersion of the trajectory, attitude, and impact point, where the launch vehicle performance variations and wind effects during the atmospheric phase are included. The impact area to guarantee the flight safety is determined using the results of the dispersion analysis. The flight test results confirm that the safe flight of TLV is performed within the predicted dispersion boundary.

• KIEAE Journal
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• v.14 no.1
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• pp.39-48
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• 2014

In the previous test, the verification of the standard floor impact source was carried out comparing the physical characteristics with living impact sources. The result was appeared the validation of the standard impact source was very low because of differences of physical characteristics. This study aims to evaluate annoyance and loudness of standard impact source which is used for the measurement of floor impact sound, and to compare the annoyance and loudness of living impact sources which are produced in real life. The impact sources considered are tapping machine, tire and impact ball as standard sources, and nine real sources which were chosen from the existing researches. The result showed differences of annoyance and loudness between standard impact sources and living impact sources, which means the standard impact sources may rate the performance of floor system inappropriately. In the future, the rating method should be examined how the standard impact sources are similar with real sources in the point of rating the performance of floor system.