• The Journal of the Acoustical Society of Korea
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• v.42 no.2
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• pp.124-132
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• 2023

When the building becomes high, the number of households increases and they are adjacent to the elevator. So, frequency of use of elevators will increase. Elevator noise is bound to increase in the future. However, there are currently no legal standards for elevator noise or measurement and evaluation methods that can clearly measure elevator noise in Korea. Although some methods for measuring elevator noise are presented in KS F ISO 16032, this standard is not a standard established for elevator noise. It is a standard that integrates the overall measurement method of building equipment and equipment, and the position of the microphone is selected by the experimenter during measurement. Elevator noise is characterized by a low sound pressure level as the noise in the mid-low frequency band is important. However, even today, complaints from residents about elevator noise are increasing. In this study, the position of the microphone that can most sensitively pick up the elevator noise when measuring the elevator noise was studied. According to the distance from the wall and the height from the floor, a total of 9 microphone positions were measured and analyzed. As a result of the experiment, it was confirmed that the elevator noise has a very high influence in the 63 Hz band. The measured value at the center point was identified as a factor that lowered the overall elevator noise level value.

• Journal of Korean Society of Transportation
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• v.34 no.1
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• pp.68-80
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• 2016

Interest in freeway truck traffic has increased largely due to greater safety concerns regarding truck-related crashes. The negative interactions between slow-moving trucks and other vehicles are a primary cause of hazardous conditions, which lead to crashes with larger speed variations. To improve operational efficiency and safety, providing a climbing lane that separates slow-moving trucks from higher performance vehicles is frequently considered when upgrading geometrics. This study developed an operations strategy for freeway climbing lanes based on traffic conditions in real time. To consider traffic safety when designing a dynamic strategy to determine whether a climbing lane is closed or open, various factors, including the level of service (LOS) and the percentage of trucks, are investigated through microscopic simulations. A microscopic traffic simulator, VISSIM, was used to simulate freeway traffic streams and collect vehicle-maneuvering data. Additionally, an external application program interface, VISSIM's COM-interface, was used to implement the proposed climbing lane operations strategies. Surrogate safety measures (SSM), including the frequency of rear-end conflicts and, were used to quantitatively evaluate the traffic safety using an analysis of individual vehicle trajectories obtained from VISSIM simulations with various operations scenarios. It is expected that the proposed algorithm can be the backbone for operating the climbing lane in real time for safer traffic management.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.5
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• pp.418-428
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• 2003

Fiber fracture is one of the dominant failure phenomena affecting the total mechanical Performance of the composites. Fiber fracture locations were measured through the conventional optical microscope and the nondestructive acoustic emission (AE) technique and then were compared together as a function of the epoxy matrix modulus and the fiber surface treatment by the electrodeposition method (ED). Interfacial shear strength (IFSS) was measured using tensile fragmentation test in combination of AE method. ED treatment of the fiber surface enlarged the number of fiber fracture locations in comparison to the untreated case. The number of fiber fracture events measured by the AE method was less than optically obtained one. However, fiber fracture locations determined by AE detection corresponded with those by optical observation with small errors. The source location of fiber breaks by AE analysis could be a nondestructive, valuable method to measure interfacial shear strength (IFSS) of matrix in non-, semi- and/or transparent polymer composites.

• Journal of Preventive Medicine and Public Health
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• v.37 no.2
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• pp.111-119
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• 2004

Purpose : To identify those factors influencing the post-operative satisfaction in myopia patients receiving laser in situ keratomileusis (LASIK) Methods : This study included 288 consecutive patients who received LASIK between July and December 2001 from two eye clinics located in Seoul and Pusan. Factors that were considered to influence post-operative satisfaction included pre-operative baseline characteristics, pre-operative expectation for treatment outcomes, and treatment outcomes. Before undergoing LASIK, study subjects were asked to rate the degree of their expectation for the improvement of visual functions and symptoms after LASIK on a 5-point Likert-type scale: where 1 referred to 'somewhat worse,' 2 to 'no change,' 3 to 'somewhat improved,' 4 to 'improved,' and 5 to 'very improved.' Self-administered questionnaire was used to evaluate baseline visual functions and symptoms on a 5-point scale before LASIK. At 6 months after LASIK, the evaluation was repeated to measure treatment outcomes in terms of the difference in the score before and after LASIK. Post-operative satisfaction was also measured at 6 months on a 5-point scale. Multiple regression analysis was performed to examine the independent relationship between influencing factors and postoperative satisfaction. Results : A total of 171 patients (59.4%) participated in the 6-month follow-up investigation. The average expectation scores for the improvement in visual functions and symptoms were 3.8 and 3.4, respectively. The average score for the 7 questions assessing satisfaction was 4.0. The results of the regression analysis showed that the post-operative satisfaction increased with improvement in the visual function ($\beta$=0.16, p<0.05) and symptoms ($\beta$=0.25, p<0.05), the degree of preoperative refractive error ($\beta$ =0.26-0.67, p<0.05) and in male patients ($\beta$=0.31, p<0.1). The pre-operative expectation was not a statistically significant factor in explaining postoperative satisfaction in the regression model. Conclusion : The finding from this study was that patients with very severe myopia tended to be more satisfied with the treatment than those with mild myopia, which implies that LASIK can be more beneficial to those suffering from a severe visual condition. Patient satisfaction was also significantly affected by the treatment outcomes experienced after LASIK. This suggests that improving the clinical outcome is the most fundamental requirement for the improvement of patient satisfaction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.503-512
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• 2017

The perceived stress of pregnant women is a potential contributor to adverse birth outcomes. Although the importance of the psychosocial well-being of pregnant women has been emphasized, there are fewreliable and valid instruments to measure the stress level of pregnant women in Korea. This study evaluated the psychometric properties of Ahn's pregnancy related stress scale (PSS) that was originally developed in 1984. Two hundred pregnant women completed the survey questionnaire, which was comprised of the PSS, depression scale, and demographic information. Principal component analysis and confirmatory factor analysis was used to test the construct validity. The concurrent validity was evaluated using the correlation with depression scores. Based on exploratory factor analysis and a consideration of conceptual meaning, a five-factor structure was extracted, explaining 57.25% of the variance: physical discomfort, fetus, parenting, spouse relationship, and housework. The goodness-of-fit indices showed an acceptable fit overall with the full model and acceptable internal consistency (Cronbach's alpha =.89). The concurrent validity was confirmed by a comparing with the depression score (r=.48, p <.001). The shortened PSS, as a valid and reliable scale, is recommended to be used to assess pregnancy-related stress and to develop stress managing interventions for pregnant women in clinical settings.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.310-315
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• 2017

Although studies evaluating the effects of the blasting vibration on the adjacent structures from various angles have continued, cases of securing the safety of the adjacent buildings and researching the proper blasting method for the field condition by analyzing the vibration waveform of the measuring field while performing the open pit blasting are poor. Therefore, it is necessary to present a remedy for blasting pattern selection through test blasting that is appropriate for field conditions, and is economical and efficient. In this study, open pit blasting work was conducted based on the separation distance applied according to the standard blasting method by test blasting and the vibration regulation standard in the road expansion construction site to measure the blasting vibration value, and the vibration prediction equation by blasting methods was examined using a regression analysis computer program to calculate K, N, and R of the confidence level 95%. By setting the blasting allowed vibration standard of the test blasting target area to 0.3cm/sec, and the charring weight and blasting method by the separation distances according to the blasting vibration estimation equation of the open pit blasting guideline and the blasting vibration estimation equation of the test blasting were compared/analyzed, it was possible to identify the factors that increased the working expenses. In addition, the measurement and analysis of the adjacent structures during open pit blasting and the blasting vibration were performed after selecting the most adjacent structure to the open pit blasting spot to analyze the problems on the test blasting procedure and analysis method in the open pit blasting design/construction guidelines, which appeared in the process of completing open pit blasting construction, and a remedy is presented.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.532-541
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• 2016

The objective of this paper is to support accurate pavement condition assessment and decision of proper maintenance method and time by conducting visual inspection and calculating the remaining life of pavement from falling weight deflectometer(FWD) data. Each was implemented in the same long-term performance pavement(LTPP) sections. Visual inspection was executed to measure pavement condition indices such as crack, rutting and international roughness index(IRI) and the Seoul Pavement Index(SPI) was calculated based on these results. The dynamic modulus was back-calculated from the FWD data. The remaining pavement lives were determined from equivalent single axle loading(ESAL) and FWD data. Correlation of maintenance priority by each result value was examined. Consequently, the correlation between remaining life to Crack and Rutting was higher than the other factors or indicesbecause IRI is not related to FWD value and SPI value consists with IRI value and other indices. The R-square value of correlation of FWD with Crack and Rutting was 0.65, which indicated an insufficient correlation. Consequently, when decision of maintenance of method, time, etc. is determined, FWD data have to be considered with Crack and Rutting because of those relations.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.4
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• pp.86-98
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• 2018

Since 2015, the Korea Expressway Corporation has provided predicted travel time information, which is reproduced from DSRC systems over the extended expressway network in Korea. When it is open for public information, it helps travelers decide optimal routes while minimizing traffic congestions and travel cost. Although, sutiable evaluations to investigate the reliability of travel time forecast information have not been conducted so far. First of all, this study seeks to find out a measure of effectiveness to evaluate the reliability of travel time forecast via various literatures. Secondly, using the performance measurement, this study evaluates concurrent travel time forecast information in highway quantitatively and examines the forecast error by exploratory data analysis. It appears that most of highway lines provided reliable forecast information. However, we found significant over/under-forecast on a few links within several long lines and it turns out that such minor errors reduce overall reliability in travel time forecast of the corresponding highway lines. This study would help to build a priority for quality control of the travel time forecast information system, and highlight the importance of performing periodic and sustainable management for travel time forecast information.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.5
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• pp.183-191
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• 2010

Unique and invariant biometric characteristics have been used for secure user authentication. Storing original biometric data is not acceptable due to privacy and security concerns of biometric technology. In order to enhance the security of the biometric data, the cancelable biometrics was introduced. Using revocable and non-invertible transformation, the cancelable biometrics can provide a way of more secure biometric authentication. In this paper, we present a new cancelable bits extraction method for the facial data. For the feature extraction, the Subpattern-based Principle Component Analysis (PCA) is adopted. The Subpattern-based PCA divides a whole image into a set of partitioned subpatterns and extracts principle components from each subpattern area. The feature extracted by using Subpattern-based PCA is discretized with a helper data based method. The elements of the obtained bits are evaluated and ordered according to a measure based on the fisher criterion. Finally, the most discriminative bits are chosen as the biometric bits string and used for authentication of each identity. Even if the generated bits string is compromised, new bits string can be generated simply by changing the helper data. Because, the helper data utilizes partial information of the feature, the proposed method does not reveal privacy sensitive biometric information of the user. For a security evaluation of the proposed method, a scenario in which the helper is compromised by an adversary is also considered.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.9 s.351
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• pp.120-127
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• 2006

In Korea the vehicle enforcement system(VES) detects speeding vehicle using two inductive loop detectors. And the speed reliability of theirs are evaluated through the analysis of image frame which is captured from video camera. This method is validated to evaluate VES on Korea Laboratory Accreditation Scheme(KOLAS) but it needs much time and expense for the analysis of image frame. Because the number of VES are increasing rapidly, the requirement of new evaluation method is necessary. On this paper, the tape switch sensor as a substitution of existing method was introduced and its application on the site are discussed. On the site test we compared the tape switch sensor on the speed measurement of vehicle with the video image frame. As a result we have founded that the tape switch sensor is evaluated to be feasible system on site in respect to measure the overspeed vehicle.