• Journal of the Korea institute for structural maintenance and inspection
• /
• v.1 no.2
• /
• pp.87-94
• /
• 1997

This research aims to develop an algorithm of optimal transducer placement using Kinetic Energy of the structural system. The structural vibration response-based health monitoring is considered one of the best for the system which requires a long-term, continuous monitoring. In its experimental modal testing, however, it is difficult to decide on the measurement locations and their number, especially for complex structures, which have a major influence on the quality of the results. In order to minimize the number of sensing operations and optimize the transducer location while maximizing the accuracy of results, this paper discusses about an optimum transducer placement criterion suitable for the identification of structural damage. As a criterion algorithm, it proposes the Kinetic Energy Optimization Technique (EOT), and then addresses the numerical issues which are subsequently applicable to actual experiment where a bridge model is used. By using the experimental data, it compares the EOT with the EIM (Effective Independence Method) which is generally used to optimize the transducer placement for the damage identification and control purposes. The comparison conclusively shows that the EOT algorithm proposed in this paper is preferable when a structure is to be instrumented with fewer sensors.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.6 no.2
• /
• pp.145-155
• /
• 2002

It is essential for health monitoring of a cable-stayed bridge to provide more accurate and enough information from the sensors. In experimental modal testing, the chosen measurement locations and the number of measurements have a major influence on the quality of the results. The choice is often difficult for complex structures like a cable-stayed bridge. It is extremely important a cable-stayed bridge to minimize the number of sensing operations required to monitor the structural system. In order to obtain the desired accuracy for the structural test, several issues must take into consideration. Two important issues are the number and location of response sensors. There are usually several alternative locations where different sensors can be located. On the other hand, the number of sensors might be limited due to economic constraints. Therefore, techniques such as methodologies, algorithms etc., which address the issue of limited instrumentation and its effects on resolution and accuracy in health monitoring systems are paramount to a damage diagnosis approach. This paper discusses an optimum sensor placement criterion suitable to the identification of structural damage for continuous health monitoring. A Kinetic Energy optimization technique and an Effective Independence Method are analyzed and numerical and theoretical issues are addressed for a cable-stayed bridge. Its application to a cable-stayed bridge is discussed to optimize the sensor placement for identification and control purposes.

• Phonetics and Speech Sciences
• /
• v.11 no.3
• /
• pp.1-7
• /
• 2019

Korean (L1)-English (L2) bilingual adults' and children's production of Korean and English stops was examined to determine the age effects and L2 experience on the development of L1 and L2 stop contrasts. Four groups of Seoul Korean speakers (experienced and inexperienced adult and child groups) and two groups of age-matched native English speakers participated. The overall results of voice onset time (VOT) and fundamental frequency (F0) of phrase-initial stops in Korean and word-intial stops in English showed a delay in the acquisition of L1 due to the dominant exposure to L2. Significantly longer VOT and lower F0 for aspirated stops as well as high temporal variability across repetitions of lenis stops were interpreted to indicate a strong effect of English on Korean stop contrasts for bilingual children. That is, the heavy use of VOT for Korean stop contrasts shows bilingual children's attention to the acoustic cue that are primarily employed in the dominant L2. Furthermore, inexperienced children, but not adults, were shown to create new L2 categories that are distinctive from the L1 within 6 months of L2 experience, suggesting greater independence between the two phonological systems. The implications of bilinguals' age at the time of testing to the degree and direction of L1-L2 interaction are further discussed.

• Journal of the Korea Convergence Society
• /
• v.10 no.2
• /
• pp.83-88
• /
• 2019

This study examines the effects of student-centered project-based learning for the development of creative problem-solving skills, communication skills, critical thinking skills, and cooperation. A college students' creative personality test was used and pre-and post-test were performed. and TOEIC Speaking practice test by Educational Testing Service were selected to measure the English communication skills. The SPSS 18.0 was used and validated at a significance level of 5%. The result of this study shows that in the case of 'independence', the post-test average of the experimental group was statistically significant at the significant level (p<.01), which also showed statistically significant difference. There was statistically significant difference between the control group ($M=127{\pm}08.2$) and in the experimental group ($M=132{\pm}18.7$) applying project-based and problem-based convergent learning to English class were positively changed.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.11
• /
• pp.5587-5594
• /
• 2012

Determination of the soil-water characteristic curve is one of the most important things to solve geotechnical engineering problems. Expecially, convenient and reliable method to measure the soil-water characteristic curve during drying and wetting cycles is required with lower labor input, more independence from operator experience, and shorter testing time than other available methods. Many measurement methods including the flow pump system have been developed to characterize the soil-water characteristic curve for the several decades. This study measured the soil-water characteristic curve during drying and wetting cycles using a suction control technique with the flow pump system. Two test materials were used for determination of the soil-water characteristic curve, and it is concluded that suction control technique is suitable for determination of the soil-water characteristic curve and characterization of the hydraulic hysteresis with varying test conditions. Especially, the suction control technique can reduce error of measurement and save time in measuring the soil-water characteristic curve due to automated system and high degree of precision.

• The Korean Journal of Applied Statistics
• /
• v.20 no.2
• /
• pp.323-332
• /
• 2007

We present a new type of portmanteau test in the frequency domain which is derived from the discrete cosine transform(DCT). For the stationary time series, DCT coefficients are asymptotically independent and their variances are expressed by linear combinations of autocovariances. The covariance matrix of DCT coefficients for white noises is diagonal matrix whose diagonal elements is the variance of time series. A simple way to test the independence of time series is that we divide DCT coefficients into two or three parts and then compare sample variances. We also do this by testing the slope in the linear regression model of which the response variables are absolute values or squares of coefficients. Simulation results show that the proposed tests has much higher powers than Ljung-Box test in most cases of our experiments.

• Korean Journal of Childcare and Education
• /
• v.8 no.4
• /
• pp.97-111
• /
• 2012

This goal of this study was to find relationships between variables that have an influences on young children's leadership. The subjects of the study were 251 five year old children enrolled in childcare programs located in Seoul & Gyeonggi-do, Korea, the methods for analyzing children's leadership were t-tests, a correlation analysis and the multiple regression analysis which was used to recognize what factor affected the leadership of young children the most. The result of this study was that there was a difference between the sub-factor and leadership of playfulness according to the gender and birth order of young children and whether their mother was working out or not. In other words, there was a difference in the leadership and temperament according to gender and birth order and whether their mother was working out or not. Secondly, there was partial correlation between the temperament of young children, playfulness, and leadership according to the testing of the low-level variable factor. Thirdly, the strongest predictor of children's leadership wad the social independence among playfulness.

• Journal of Korean Society on Water Environment
• /
• v.36 no.4
• /
• pp.322-331
• /
• 2020

By introducing chemically enhanced primary treatment (CEPT) in the first stage of sewage treatment, organic matter in sewage can be effectively recovered. Because CEPT sludge contains a high biodegradable organic matter in volatile solids (VS), it is feasible to convert the collected CEPT sludge into energy through anaerobic digestion. This study examined the properties and biochemical methane potential (BMP) of the CEPT sludge obtained from a sewage treatment plant located in an ocean area. The CEPT sludge contains a VS content of 37,597 mg/L, which is higher than that of excessive sludge (ES), i.e., 33,352 mg-VS/L. In the methane generation reaction, the lag period was as short as 1 to 2 days. The BMP for the CEPT sludge was 0.57 ㎥-CH₄/kg-VS_removed which is better than that of ES, i.e., 0.36 ㎥-CH₄/kg-VS_removed. Unfortunately, the CEPT sludge showed a high salinity as 0.56~0.75% probably due to the saline sewage. Due to the salinity, repeated BMP testing in a sequencing batch reactor showed significantly low methane production rates and BMPs. Also, the ES showed a strongly reduced BMP when the salinity was adjusted from 0.20 to 0.70% by NaCl. The ES mixture with higher CEPT content showed a better BMP, which is suitable for co-digestion. Besides, anaerobic digestion for 100% CEPT sludge can be a considerable option instead of co-digestion.

• Management & Information Systems Review
• /
• v.31 no.3
• /
• pp.1-19
• /
• 2012

This study is the research about the internet marketing strategy and the impact factors of psychological well-being of customers of restaurants. For the purpose of study, firstly, the paper was carried out in order to verify the cause and effect relationships of life satisfaction and psychological well-being of the customers in the food service industry. The customers of restaurants in Busan are the objectives for which the survey for empirical analysis was conducted. The result of the testing of hypothesis showed that life satisfaction will have positive influences on psychological well-being, it reveals that life satisfaction has positive influences on three factors of psychological well-being such as personal growth, self acceptance, independence. However, factor of autonomy is rejected. Secondly, the results of the study suggest the importance of introducing variegated internet marketing programs and deciding the appropriate information contents for the customer to activate the use of hands on restaurants. Internet information contents on customer satisfaction and customer loyalty to have a good understanding of the attitude will improve of life satisfaction and psychological well-being of the customers. Strategic information contents of internet marketing for customers of the restaurants must be consider "CRM(customer relationship management)".

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.7
• /
• pp.1805-1816
• /
• 1999

This paper presents the Module Class Dependency Graph for expressing the dependency relations between classes effectively. The object-oriented language is developed independently at design time, and consists of relationship between classes. Therefore we need to consider these characteristics of independence, and to express effectively the relation of classes which is existed in class hierarchy. In the System Dependence Graph and Class Dependence Graph, the relationship of classes is not expressed. To express the class relationship, we propose the Module Class Dependence Graph, and we verify the effectiveness of this method applying to object constructor, inheritance relationship and dynamic binding. Also, we presents the expressing method of parameter to identify the member data of classes. Using this Module Class Dependency Graph, we can analyze the relationship of module class correctly at design time. This method can be applied to reverse engineering, testing, visualization and other various fields to analyze system.