• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.6
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• pp.591-596
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• 2016

This paper presents a study on the subject for the design and implementation of high-speed frequency hopping RF transceiver used for tactical communications systems. Jump the transmission / reception frequency of the L-band to hop tens per second is possible by maximizing the immunity to interference, and is applicable to communication systems having a charging rotation function. To high-speed frequency hopping it is necessary to apply the necessary fast frequency hopping scheme DDS Driven PLL added. In this paper, the RF transceiver design and simulation analysis capabilities with fast frequency tactical communication systems, were implemented after the main test for functionality and performance. Was demonstrated hop high-speed jump tens per second through a test, the main transmission output, were measured RF key performance, such as received noise figure, by using the VSG and VSA generates a ${\pi}/4$ DQPSK modulated signal constellation and by EVM measurement that there is no problem in applying the communications system described above was pre-validated.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.2
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• pp.117-129
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• 2012

In this study, research was performed to establish the measurement and frequency of analysis for maintenance monitoring by investigation of tunnel maintenance monitoring system in the tunnel which was installed in the Seoul metro line 5, 7 and 8, using that the domestic and foreign application case, results of analyzed maintenance monitoring in the domestic tunnel and legal safety management standard of the facility. The results of the monitoring management about analysis frequency to the present are considered that the problem about measuring frequency does not occur. According to the analysis results of the maintenance monitoring which are located on the 5, 6th subway line, they are analyzed that the stress of concrete lining and reinforced bar are converged gradually after 45 months. Therefore Monitoring of measurement and analysis frequency is conduct more often within about 4 years after the measuring instrument installation. Four years later, slowing the frequency of measurement is considered reasonable.

• Geophysics and Geophysical Exploration
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• v.15 no.3
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• pp.121-128
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• 2012

Absorbing boundary conditions are used to mitigate undesired reflections that can arise at the model's truncation boundaries. We apply a complex frequency shifted perfectly matched layer (CFS-PML) to elastic wave modeling in the frequency domain. Modeling results show that the performance of our implementation is superior to other absorbing boundaries. We consider the coefficients of CFS-PML to be optimal when the kinetic energy becomes to the minimum, and propose the modified CFS-PML that has the CFS-PML coefficient ${\alpha}_{max}$ defined as a function of frequency. Results with CFS-PML and modified CFS-PML are significantly improved compared with those of the classical PML technique suffering from large spurious reflections at grazing incidence.

• Journal of Families and Better Life
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• v.27 no.3
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• pp.159-170
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• 2009

The purpose of this study was (1) to investigate the difference of temperament, self-regulation, and problem behavior according to children's gender and age, (2) to investigate the relationship among three variables by use of canonical correlation analysis. The subjects were 210 children ages from 3 to 5 in five day-care center in Incheon city. The SPSS WIN 12.0 Program was used to analyze the collected data. The statistical methods were Frequency, Percentage, Cronbach's ${\alpha}$, Two-way ANOVA, Correlation analysis, and Canonical Correlation analysis. The major results of this research are summarized as follows: (1) Children's temperament were significantly different by their gender and age. The boys got higher score than girls in adaptability, activity, and total temperament. Girls got higher score than boys in reactivity. The age 3 got higher score than the age 5 in activity and the ages 3, 4 got higher than the age 5 in total temperament. (2) Children's self-regulation were significantly different by their age. The children who were older got higher scores in self-regulation ability. (3) Children's problems behavior were significantly different by their gender and age. The boys got higher score than girls in anxiety behavior, aggressive behavior, hyperactive/distractive behavior, and total problem behavior. And the ages 3, 4 got higher score than the age 5 in anxiety behavior and hyperactive/distractive behavior. The age 4 got higher score the ages 3, 5 in aggressive behavior and the age 3 got higher score the ages 4, 5 in total problem behavior. (4) Canonical correlation results showed that stable temperament and self-regulation were positively correlated and self-regulation and problem behavior were negatively correlated.

• Korean Journal of Human Ecology
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• v.13 no.6
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• pp.847-860
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• 2004

The purpose of this study is to obtain basic data needed to understand school-age children's parent-child communication style, stress coping behaviors, and child behavior problems. The subject of this study were 362 primary school children (the fourth and the sixth graders) and their mothers in "D" Metropolitan City, Korea. The research tools included standardized parent-child communication style scale (Min,l991), stress coping behaviors scale (Min,1998), and child behavior problems scale (Hun,l996). The data were analyzed using statistical techniques such as Mean, standard deviation, frequency, percentile, t-test, F-test, pearson's correlational analysis, stepwise regression analysis. In the relationship between child perceived parent-child communication style and stress coping behaviors, the children who make open communication with their parents demonstrate high problem-solving, support-seeking coping behavior. The children with closed communication with their parents have high hope expectation, revenge coping behavior. In the relationship between child perceived parent-child communication style and child behavior problem, the children making more closed communication with their parents show more behavior problems. The children with more closed communication with their mothers have more hyperactive behaviors, aggressive behaviors, and immature behaviors, and the children who are making more closed communication retain more anxious behaviors and withdrawn behaviors. In the relationship between child stress coping behaviors and behavior problems, the more problem-solving and support-seeking coping behaviors the children possess, the less problem behaviors they demonstrate. The more hope expectation, revenge coping behavior the children possess, the more problem behaviors they show. With the results above, we can find out that parent-child communication style has an effect on stress coping behavior, and parent-child communication style and stress coping behavior have an influence on child behavior problem.

• Journal of Korean society of Dental Hygiene
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• v.16 no.2
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• pp.285-293
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• 2016

Objectives: The aim of the study was to investigate the association of self-perceived oral health and depression in the Korean elderly. Methods: The subjects were 1,329 elderly in Korea from the sixth Korea National Health and Nutrition Examination Survey (the 6th KNHANES). The dependent variable was depression that continued more than two weeks. Model I for the impacts of depression on self-reported oral health, Model II for the impacts of depression on chewing problem, Model III for the impacts of depression on speaking problem was evaluated. PASW Statistics 18.0 version was used for frequency analysis, chi-square test and logistic regression analysis. Results: Female elderly were much more prone to depression than male. Female had lower monthly compensation, less medicaid, chewing problem, speaking problem, and less education. For these reasons, they tended to have more depression than male (p<0.001). Self-perceived oral health impacts on depression included poor self-reported oral health(p<0.01), poor chewing problem(p<0.01) and poor speaking problem(p<0.05). On the other hand, male did not show a statistically significant association. Conclusions: The study showed the self-perceived oral health related quality of life had a significant influence on depression in the elderly. The continuing lifelong oral health care can prevent depression in the later life because oral health care improvement can enhance the self-perceived oral health status.

• The Journal of the Korea Contents Association
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• v.10 no.12
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• pp.254-266
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• 2010

This study dealt with Traffic Problem to Cheonan city. This study ran parallel literature investigation and actual proof investigation. Questionnaires 394 enforce frequency analysis in SPSS 15.0 versions. Traffic Problem to Cheonan city include the discomfort of public transportation, parking problem, pollution of automobile, traffic accident. By improvement of traffic problem, first, improvement plan of transportation system by administration of logical traffic demand should be readied. Second, because Cheonan city is many an university student who is use target of public transportation, public transportation utilization ratio must raise through discount application. Third, solution of traffic jam need to the improvement and strengthening of system of public transit. Fourth, Cheonan city must push ahead with supplies of traffic facility, modify of transportation network, and improvement of operating system. In particular, Cheonan city need to modify old road and improvement of accessibility though road network briefly. Fifth, Cheonan city need fixing of van traffic culture such as solution of parking problem and traffic order consciousness fostering of users.

• The Journal of the Korea Contents Association
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• v.17 no.5
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• pp.45-55
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• 2017

The purpose of this study was to identify the participation in activities, emotions, and problem behaviors of elderly people residing in nursing homes. In this observational study targeting 81 elderly patients with dementia, each patient's participation in activities, emotion, and problem behaviors were observed for 4 hours per day with 20 minutes interval, which leads to 6,804 data based on 12 times a day for 7 days. According to this study, 90.1% of the participants were suffering from severe cognitive impairment. Their emotions were scored 4 out of 7. They mainly participated in activities such as sitting or lying down, which had no specific purpose, but they showed the most positive emotion when involved in social activities. The most frequent types of problem behaviors were repetitive behaviors and making noises, and the frequency of their behaviors were different depending on the time. There were significant correlation between cognitive functions, emotions, and problematic behaviors. Therefore, it is necessary to find effective ways to increase participation in activities, induce participation in positive emotional activities, and reduce problem behaviors manifested most prominently each hour of the elderly patients with dementia residing in nursing homes.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.582-587
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• 2004

Ultrasonic sensors are widely used in mobile robot applications to recognize external environments, because they are cheap, easy to use, and robust under varying lighting conditions. However, the recognition of objects using a ultrasonic sensor is not so easy due to its characteristics such as narrow beam width and no reflected signal from a inclined object. As one of the alternatives to resolve these problems, use of multiple sensors has been studied. A sequential driving system needs a long measurement time and does not take advantage of multiple sensors. Simultaneous and pulse coding driving system of ultrasonic sensor array cannot measure short distance as the length of the code becomes long. This problem can be resolved by multi-frequency driving of ultrasonic sensors, which allows multi-sensors to be fired simultaneously and adjacent objects to be distinguished. Accordingly, this paper presents a simultaneous and multi-frequency driving system for an ultrasonic sensor array for object recognition. The proposed system is designed and implemented using a DSP and FPGA. A micro-controller board is made using a DSP, Polaroid 6500 ranging modules are modified for firing the multi-frequency signals, and a 5-channel frequency modulated signal generating board is made using a FPGA. To verify the proposed method, experiments were conducted in an environment with overlapping signals, and the flight distances for each sensor were obtained from filtering of the received overlapping signals and calculation of the time-of-flights.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.9
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• pp.1939-1946
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• 2012

USNs (Ubiquitous Sensor Networks) such as IEEE 802.15.4 ZigBee network share ISM (Industrial, Scientific, and Medical) frequency band with WiFi networks. Once both networks operate in a region, packet collision may happen because of frequency overlapping. To assure this possibility, we conducted experiments where WiFi and ZigBee communication networks had been installed in an area. As a result of the test, successful data transmission rate were reduced due to the frequency overlapping between a WiFi communication channel and a ZigBee communication band. To cope with this problem, we propose a collision avoidance algorithm. In the proposed algorithm, if frequency collision is sensed, new communication channel with different frequency band is allocated to each node. Performance of the proposed frequency collision avoidance algorithm was tested and the results were described.