• Journal of IKEEE
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• v.3 no.2 s.5
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• pp.186-195
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• 1999

In this paper, the RF-modules composed of front-end, frequency synthesizer, modulator/demodulator and power control multi channel WLL personal system for W-CDMA using 10 [MHz] RF channel bandwidth has been implemented and considered. The measured transmission power is 250 [mW] which is very close to the required value. The measured flatness of power at the final output stage is ${\pm}1.5[dB]$ over the required bandwidth of the receiver. In addition, it is found that the chip rate transmitting spread signal is set to 8.192 [MHz], the required rate. The frequencies of RF_LO signal and LO signal of the modulator and the demodulator measured by a frequency synthesizer are satisfied with design requirements. The operating range of the receiving strength signal indicator and AGC units shows 60 [dB] respectively. Also the measured phasor diagram and eye pattern for deciding the RF modules compatible with baseband digital signal processing part are shown good results.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.19-22
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• 2002

In this paper, we aims to develop a microcontroll er-based ECG monitoring system and portable pulse oximeter using Compact Flash Interface. First, portable pulse oximeter system is designed to record 2 channel of biosignals simultaneously, including 1 channel of $SpO_2$ and 1 channel of pulse rate. It is very small and portable. Besides, the system makes it possible to measure a patient's condition without an additional medical equipment. We tried to solve the problems generated by a patient's motion. That is, we added an analog circuit to a traditional pulse oximeter in order to eliminate the change of the base line. And we used 2D sector algorithm. As present, SpO2 modules are completed. But there are still many further development needed in order to enhance the function. Especially, compact falsh interface remains the most to complete. Second, ECG monitoring system uses almost same as present 3-lead ECG system. But we focus on the analog part, especially in filter. The proposed filter is composed of two parts. One is a filter to remove the power-line interface. The other is a filter to remove the baseline drift. A filter to remove the power-line and the baseline drift is necessarily used in the ECG system. The implemented filter have three features; minimizing the distortion in DC component, removing the harmonic component of power-line frequency. Using compact flash interface, we can easily transfer a patient's personal information and the measured signal data to a network based server environment. That means, it is possible to implement a patient's monitoring system with low cost.

• Journal of Families and Better Life
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• v.33 no.4
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• pp.51-65
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• 2015

Case management is becoming increasingly more important in the field of social welfare. The purpose of this study was to examine the practice of case management at community child centers and to identify factors influencing their performance. In addition, this study also analysed the performance level of case management at each stage and the factors influencing the level at each stage. For the purpose of this study, data obtained from about 181 community child center workers in Busan, Ulsan and Gyeongsangnamdo were analyzed. According to the results of the analysis, in Model 1 which represents the category of socio-demographic and personal factors, three factors namely gender, experience in case management, and interpersonal skills were found to be significantly influential and they have an explanatory power of 21.5%. Under the category of organizational factors in Model 2, four factors were found to be influential: experience in case management, interpersonal skills, availability of case management guidelines, and holding case conferences. These factors account for 33% explanatory power, 11.5% higher than that of Model 1. In Model 3 which represents the third category of community network literacy, three factors namely interpersonal skills, availability of case management guidelines, and ability to utilize networks were found to influence case management at community child centers, and they have an explanatory power of 43.4%, 10.4% higher than that of Model 2. For the practice of social welfare, these findings have the implication that community child center workers need to improve their interpersonal skills by cultivating communication skills, collaborative problem-solving skills, conflict-management skills, and other relevant skills. Furthermore, it is necessary to provide specific guidelines for case management, to have regular case conferences, to establish a community network, and to reinforce cooperation and mutual support among institutions within the network.

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.45-49
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• 2010

This paper presents the study on multi-beam large aperture antenna systems for a satellite payload. Multi-beam large antenna provides the universal communication and broadcasting services to personal portable terminals. The hybrid antenna composed of a large reflector and a feed array forms multi-beams. The feed cluster consists of a group of feed elements and each element should be optimized for the appropriate amplitude and phase. The optimization progress for amplitude and phase was performed by GO (Geometrical Optics) and PO (Physical Optics) method. The number of feed elements as well as the power level per element were also optimized to meet the required EIRP (Effective Isotropically Radiated Power). In conclusion, 30m-class reflector and twenty five elements for fifteen beams over Korean Peninsula were designed through the optimization process.

• Journal of the Korean School Mathematics Society
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• v.4 no.1
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• pp.91-101
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• 2001

Nowadays the number of students that is losing their interest as well as learning desire in mathematics is increasing because of lack of logical thought creative power and abstract expression that present-day mathematics requires by reason of discrepancy of extreme scholastic ability by speciality of mathematics. In these conditions, we reduce the number of learning depression by bringing about learning desire or learning interest on mathematics, and students learn effective learning methods to be voluntary learning of discovery themselves that studies basic concepts, principles, rules through logical thought of students to solve difference of scholastic ability, thus we assumed that debate studies through small group activities in ability group would be one of ways to improve learning power, so the results of our research are as follows; 1. Debate studies through small group activities were very effective because of reinforcing the achivement level of students. 2. By this learning method, an individual or cooperrative learning was fostered, and lively discussions were accomplished. And learning attitudes of students were changed by the extension of cooperative learning abilities through advices or by themselves. 3. A personal opinion is payed regard by accepting an individual idea in the process of making questions. Learners can correct wrong concepts in the process of correcting wrong answers. So if we apply above-mentioned studies with easy contents from the lower grades, the effectiveness would increase as learners go to the higher grade. According to the results of various researches as follows; "The teaching-learning method oriented coopperative debate studies is effective to find solutions to mathematical problems." If small group activities are applied in the educational situation to search the course of a desirable cooperation learning through small group activities to improve scholastic abilities for a discoverable problem-solving power. I think that the teaching-learning method oriented cooperative debate studies is one of the most desirable methods to increase the problem-solving ability.

• Korean Journal of Health Education and Promotion
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• v.14 no.1
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• pp.23-45
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• 1997

This study was conducted from March 1, 1996 through June 30, in order to provide basic data for devising a policy for school health especially students health promotion and for developing of an education program. Middle school students were 1000, high school students were 2000 and a total of 3000 students were selected randomly among the boys/girls/middle/high schools which are in Seoul, Pusan, Taegu, Pohang, Suwon, Kyungsan, Milyang and a town or subcountry. The summary and conclusion are as follows. 1. In general characteristics of respondents, 51.8% were girl students, 33.7% were middle school students, 66.3% were high school students. 37.2% were living in a medium and small city, 89.1% were middle classes, 43.6% were having no religion, 27.3% were buddhists. 2. As a result of analyzing, exercise, nutrition, personal behavior, knowledge of health education and behavior level which are the factors promotion, exercise level were 3.61 of the perfect 9(40.1/100), nutrition level were 3.71(41.1/100), personal hygiene were 6.89(76.6/100), health education level were 5.1(58.9/100), all of the them are low level. 3. Judging from characteristics, in case of exercise behavior level, It was far higher in boy students than in girl students, in middle school students than in high school students. It was respectively higher than other groups in the second graders of middle school, in the first graders of high school, in the residents who live in a big city, in the high classes in the buddhists. 4. The students level against disease was average 9.11 of the perfect score 14(65.1/100). The level of disease consciousness was high in girl students by characteristics, in the second graders of high school by grades, in high school students than middle school students. 5. In health status, 55.4% were healthy, 7.9% were unhealthy. It was respectively higher than the other groups in boy students, in middle school students, in the residents who live in a big city, in high classes of life level, in buddihists, in higher education level of parents. 6. Judging from the factors of health status and health promotion and the degree of significance, there's a significant differences between exercise and dietary life as P〈0.001, in personal hygiene as P〈0.05, in health education an P〈0.01. 7. Knowledge on disease, health promotion behavior level were average 19.42 ± 4.01 of the perfect score 50(38.8/100) this score was too low. As for characteristics, the level between variables was statistically significant in the higher life level, in the higher parents education level, in the happier family. 8. Judging from health status, knowledge on disease, health behavior level, knowledge and health promotion behavior level significantly in the better health status, in the better school record. 9. As a result of the multiplex regression analyzing the factors which were under influence on health status, the variables like exercise, school record level, the degree of family happiness, nutrition, grades, the members of family influenced much and its persuasive power was 10.2%. The factors which are under the influence on the health promotion were exercise, satisfied degree of education, health status, the degree of family happiness, knowledge on disease, the usage of physical training, sex, the number of the family members, mother's education level. It’s explained power was 21.3%. promotion were high We should develop a text book and an education program to study exercise, nutrition(dietary life), personal hygiene, knowledge on disease and health systematically. As far as health education irrespective city and locality without considering the entrance exam for high school and university we should execute it continuously. To do this, it’s important to cultivate and secure qualified men of ability who can teach things related health promotion and the related subject, that is, health or health promotion subject should be established in middle and high school curriculum necessarily.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2A
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• pp.176-186
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• 2006

In this paper, we propose an enhanced symbol detector algorithm for 2.45GHz LR-WPAN(Low-Rate Wireless Personal Area Network) receiver. Because the frequency offset of $\pm$80ppm on 2.45GHz band is recommended in IEEE 802.15.4 LR-WPAN(Low-Rate Wireless Personal Area Network) specification, a symbol detector algorithm having stable operation in the channel environment with large frequency offset is required. For robustness to the frequency offset, non-coherent detection-based symbol detector algorithm is typically applied in the LR-WPAN receiver modem. However, the noncoherent symbol detector has increased performance degradation and hardware complexity due to squaring loss of I/Q squaring operation. Therefore we propose a coherent detection-based symbol detector algorithm with frequency offset compensation using a preamble symbol. The proposed algorithm is more suitable for LR-WPAN receiver aimed at low-cost, low-power and low-complexity than the non-coherent symbol detector, since it can reduce performance degradation due to squaring loss of I/Q squaring operation and implementation complexity. Simulation results show that the proposed algorithm has performance improvement of about 1dB in various channel environments.

• Journal of Korean society of Dental Hygiene
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• v.8 no.1
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• pp.73-91
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• 2008

In order to investigate the complaint rates of subjective fatigue symptoms and the degree of job-satisfaction among dental hygienists based on their socio-demographic and job characteristics and to find out the factors related with subjective fatigue symptoms and job satisfaction. The study subjects were recruited from 274 dental hygienists who worked at dental hospitals and clinics in Daejon city and South Chungcheong Province during the period between Jan. 5 and Feb. 11, 2008. They were asked to complete the self-administered questionnaires asking about their socio-demographic characteristics. job characteristics. daily life styles, job satisfaction and subjective fatigue symptoms, and the major finding of the results were as follows : 1. The mean scores of job satisfaction were 3.12V0.47 of the total full scores(5.00). and the highest scores were in the sub-domain of interpersonal relationship. and the lowest scores were pay. The scores of job satisfaction by socio-demographic characteristics and daily life styles were not significantly differences, but in job characteristics, significantly increased with those feeling satisfied with their job. those with appropriate amount of duty amount, those free of jop autonomy, those feeling satisfied with their monthly income. satisfactory personal relations at work. 2. The mean scores of subjective fatigue symptoms were 27.6V10.9 of the total full scores(60.0), and the highest scores were in the sub-group of bodily projection of fatigue(Group III), and they were followed by difficulty in concentration(Group II). dullness and sleepness(Group I) in their decreasing order of magnitude. The scores of job satisfaction by socio-demographic characteristics and daily life styles were significantly increased with the group of lower age, the group of irregularly breakfast habit and the worse subjective health status. Based on job characteristics. the score of subjective fatigue symptoms were significantly increased with those group of lower clinical career and monthly income, those feeling unsatisfied with their job, those with inappropriate amount of duty amount. those satisfactory personal relations at work 3. The correlation of subjective fatigue symptoms with job satisfaction showed a negative correlation with rM-0.198(pM0.000), and job satisfaction were higher according to the lower subjective fatigue symptoms. The correlation among the scores of sub-domain of job satisfaction and the sub-group of subjective fatigue symptoms were significantly positive correlation. 4. The affecting factors of significance on job satisfaction included clinical career, duty amount salary satisfaction, with the explanatory power of 32.9%. Those on subjective fatigue symptoms included the eucation and the subjective health statuts, with the explanatory power of 20.8%. When considering these results, the job-satisfaction and the subjective fatigue symptoms were significantly correlated with the job related factors than factors of socio-demographic characteristics and daily life styles. In addition. if job environments of dental hygienist can improved. their job-satisfaction and subjective fatigue symptoms are suggested to be betters.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.76-82
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• 2019

The development of Internet technology and the deployment of smart devices provide a convenient environment for people, and this is becoming common with the technology called the Internet of Things (IoT). But the development of, and demand for, IoT technology is causing various problems, such as personal information leaks due to the attacks of hackers who exploit it. A number of devices are connected to a network, and network attacks that have been exploited in the existing PC environment are occurring in the IoT environment. When it comes to IP cameras, security incidents (such as distributed denial of service [DDoS] attacks, hacking someone's personal information, and monitoring without consent) are occurring. However, it is difficult to install and implement existing security solutions because memory space and power are limited owing to the characteristics of small devices in the IoT environment. Therefore, this paper proposes a security protocol that can look at and prevent IoT security threats. A security assessment verified that the proposed protocol is able to respond to various security threats that could arise in a network. Therefore, it is expected that efficient operation of this protocol will be possible if it is applied to the IoT environment.

• Journal of Digital Convergence
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• v.15 no.1
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• pp.23-34
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• 2017

This study investigated relative explanation of social support, ego-resiliency and stress coping strategies to help adaptive coping style of school-dropout adolescents under stress situation. To this end, 101 school-dropout adolescents were surveyed by visiting and requesting the outofschool youth supporting project, youth detention center, and adolescent protective and treatment facilities in Daejeon, Cheongnam, and Chungbuk. As analysis methods, descriptive statistical analysis, pearson's correlation, and hierarchical analysis were conducted and the research results are as follows. First, stress coping strategies showed positive relationship with social support and ego-resiliency. Second, a variable that showed greater explanation power for stress coping strategies was the environmental variable, the social support. Third, it was identified that there was greater explanation power when the environmental variable, the social support, and the personal variable, the ego-resiliency, were put in at the same time for stress coping strategies. According to the result, this study implies that schools, community, national policy effort and systemetic approach are required as well as improvement of personal coping capabilities in order to overcome difficulties school-dropout adolescents face.