• The KIPS Transactions:PartC
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• v.9C no.4
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• pp.513-522
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• 2002

Current end-to-end congestion control depends only on the information of end points (using three duplicate ACK packets) and generally responds slowly to the network congestion. This mechanism can't avoid TCP global synchronization which TCP congestion window size is fluctuated during congestion occurred and if RTT (Round Trip Time) is increased, three duplicate ACK packets is not a correct congestion signal because congestion maybe already disappeared and the host may send more packets until receive the three duplicate ACK packets. Recently there is increasing interest in solving end-to-end congestion control using active network frameworks to improve the performance of TCP protocols. ACC (Active congestion control) is a variation of TCP-based congestion control with queue management In addition traffic modifications nay begin at the congested router (active router) so that ACC will respond more quickly to congestion than TCP variants. The advantage of this method is that the host uses the information provided by the active routers as well as the end points in order to relieve congestion and improve throughput. In this paper, we model enhanced ACC, provide its algorithm which control the congestion by using information in core networks and communications between active routers, and finally demonstrate enhanced performance by simulation.

• Journal of Engineering Education Research
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• v.19 no.3
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• pp.35-43
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• 2016

The purpose of this study is to explore directions for improvement of teaching at college of engineering based on analysis of differences from course evaluation of students and instructors. Data was collected from 86 instructors' ratings on courses and their 3004 students' ratings on courses at college of engineering in a two-year, a three-year college and a University from 2010 to 2013. The results of the survey indicate significant differences in the statistics from the several questions between the instructors and the students as well as between the course in a two-year, a three-year college and in a University. First, instructors' self evaluation of the course is higher than students' satisfaction ratings of the course on the average. Instructors' self evaluation are high on the questions 'The subject was proper for the course', 'The course provided the latest theory and trend of the field', and 'Fairness and objectivity about the exams and the assignments'. Also, the difference between Instructors and students on the questions is significant in the statistics. The professor must make sure that students know well how to organize the course content and the method for feedback to test result and homework. Second, instructors have higher satisfaction ratings on the six questions and students have higher satisfaction ratings on the one question('Make students participate in the class effectively') at a two-year and a three-year college. However, students have higher satisfaction ratings on the three questions('Make students participate in the class effectively', 'Concern about students' learning process', and 'Use of E-learning and media equipments') and instructors have higher satisfaction ratings on the one question. It means instructors at a University feel pressure on a teaching and they are unsatisfied with their teaching skills. Third, the result of comparing six parts of the questions shows that students' satisfaction ratings are higher on 'Students participation' and 'Application of media equipments' parts whereas instructors' self evaluation are higher on 'Exams and assignments' part. Fourth, the question 'Make students participate in the class effectively' is significant in statistic based on comparison of instructors and students, and comparison of in a college and a University. Students' satisfaction ratings are higher than instructors' self evaluation.

• Korean Journal of Community Nutrition
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• v.23 no.4
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• pp.318-332
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• 2018

Objectives: The purpose of this study was to investigate the behavioral modification of obese adults who underwent nutritional and physical activity education. Twenty obese females, aged 20-60 years old, with BMIs (Body Mass Index) >30 or body fat (%) >40 were subjected to this study. Methods: The physical activity education program consisted of doing exercise in a gymnasium together or home exercise. Dietary attitudes and dietary intakes were assessed using weight control, physical activity, and eating habits. The nutrition-exercise educational period was 12 weeks. Results: After the study period, there was significant improvement in physical activity and eating habits score. Furthermore, there was a significant increase in the dietary intakes of fiber, iron, potassium, vitamin A, vitamin $B_6$, and niacin. Blood pressure, blood glucose, and total cholesterol levels showed a tendency to decrease, but there was no significant difference. BMI, fat mass, abdominal circumference, and visceral fat levels were significantly reduced while muscle mass significantly increased. Conclusions: This study suggests that behavioral modification by nutrition and physical activity education with feedback has positive effects on dietary intake and anthropometric biomarkers in obese adults. Therefore, lifestyle interventions of this kind could be recommended as a method for obesity management.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.20 no.4
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• pp.43-61
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• 2017

The wetlands are facing environmental changes such as desiccation that occurs with the passage of time and reduced ecosystem services from wetlands in the city. In order to maintain the ecosystem services provided by wetlands in urban areas, a system thinking about the trade-off phenomenon of ecosystem services occurring as the wetlands undergo environmental changes is needed. Therefore, the purpose of this study is to develop strategies for wetland design using system thinking approach to enhance the resilience of ecosystem services degraded by the desiccation of wetlands and other disturbances. The objectives of this study include the system boundary and variables. Second, analyzing the dynamics of wetland design strategy. Third, it analyzes the trade-off phenomenon of ecosystem services in terms of the hydrology, hydric soil, and plants strategies to mitigate these effects. Fourth, wetland basic design to improve the resilience of ecosystem services. A wetland in Abuk-Mountain Neighborhood Park, Miryang-si, Gyeongsangnam-do, has been selected as a case study. Causal loop diagrams(CLDs) are used to analyze feedback in the wetland regime. In summary, hydrology, hydric soil, and plants is suggested as system boundaries to design plan. Design strategies for the wetland focused on robustness, redundancy, rapidity, and resourcefulness as a result of CLD analysis are first proposed in order to effectively maintain the wetland regime over the long term. Secondly, in a section related to hydrology, the CLD results show the trade-offs between provisioning-cultural services and regulating services. In order to control these services, a "water cycling system" has been implemented due to its strength in terms of robustness. The CLDs for hydric soil showed the trade-offs between regulating services and supporting services. An "installation of storm drainage for maintaining water levels" was selected due to the strength offered in terms of redundancy and rapidity. The CLDs for plants showed the trade-offs between provisioning - cultural services and regulating services. In order to control the strategic points, the "planting of indigenous vegetation" was suggested given the strength in terms of redundancy. In this study, a wetland design method is proposed that can improve the resilience of wetland ecosystem services by analyzing the dynamics overtime. The results of this research can theoretically be applied to help restore ecosystem services in wetlands using ecological landscape design. In addition, this study will contribute to reducing maintenance costs by improving wetland resilience.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1397-1404
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• 2015

Recently, high data rate transmission is required in maritime communication. In this paper, we consider multiple input multiple output (MIMO) spatial multiplexing (SM). However, the performance of SM is severly degraded due to spatial channel correlation and line-of-sight (LOS) component. In the maritime communication, the MIMO channel correlation and LOS are critical due to the lack of scatteres around the transmitter and/or the receiver. When the feedback of channel information is available, precoding can enhance the error performance by exploiting the channel information. However, it is difficult to derive closed-form solution considering both the correlation and LOS. In this paper, we present open-loop precoding-based spatial multiplexing transmission method by showing that the effect of performance for the correlation and LOS. It is shown that the open-loop precoding can mitigate the performance degradation due to the LOS as well as the correlation. Consequently, we expect that the proposed open-loop precoding can be adopted to the maritime communication system.

• Land and Housing Review
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• v.3 no.3
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• pp.225-240
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• 2012

The aim of this study is to discuss ways to improve Korea's housing survey by comparatively analyzing the housing surveys being carried out in six other countries. The subject countries are the United States, the United Kingdom, France, the Netherlands, Australia, and Japan-the countries that conducts large-scale surveys for more than 20,000 households on a national level and where data collection is easily available. The comparative analysis items include survey history, purpose, subject, project owner, survey item, data collection method, and the use of survey outcome. The comparative analysis results showed that each of the six countries are conducting national housing condition surveys on a regular basis considering each nation's characteristics of housing stock and policy goals, and the survey results are being used as the basis for setting policy guidelines including the selection of policy targets and the determination of appropriate rent standards, and the basis for housing assistance budget planning. Korea's housing survey has been conducted three times up until now since 2006. There should be efforts to systemize and standardize the survey components, establish standards for monitoring the changing trend of national housing stock, standards for determining policy targets, and measures to open data and provide feedback considering the preceding studies of overseas countries in order to better utilize the housing survey data for policy development.

• The Journal of Industrial Distribution & Business
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• v.9 no.11
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• pp.67-76
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• 2018

Purpose - Electrical energy saving is one of the practical virtues relating to sustainable living. Therefore, policy-makers has tried to find a way to change the behaviors of individuals to encourage them to actively practice electrical energy saving, even if they have never had this concern or have only passively practiced electrical energy saving to this point. Prior research related to electrical energy saving can be categorized into several types. The first is focused on consumer characteristics linked to electrical energy saving. These studies are based on individual or household socio-demographic variables (e.g., age, gender, household income, education level, occupants, marital status, number of households), and psycho-graphics (e.g., environmental consciousness, value, attitude, motivation, lifestyle). The second is focused on policies (e.g., monetary incentives, information sharing, social comparison, feedback), and technologies (e.g., energy-efficiency home appliances, energy-reduced products, renewable resources). People generally have a favorable attitude towards electrical energy saving, while electrical energy saving practices tend to be less favorable. Therefore, it is necessary for policy-makers to seek out gaps between attitudes and behaviors and find alternatives to reduce these gaps. This study investigates the influence of authenticity on the behavioral intention of electrical energy saving. It is supposed that electrical energy saving practices are likely to be stronger as authenticity of individual or household becomes stronger. This study reviews prior literature and examines various studies to provide an understanding of the relationships between authenticity and electrical energy saving behavioral intention. Research design, data, and methodology - Hypothesis was drawn from analysis based on previous research. The items related to authenticity and electrical energy saving were selected from items found in previous research. To verify this hypothesis, data were collected via experimental survey method and the resulting data were analyzed using reliability analysis, correlation analysis, and hierarchical regression analysis. Results - This study found that authenticity had a positive impact on the behavioral intention of electrical energy saving. The higher the perceived degree of authenticity, the higher the behavioral intention of electrical energy saving. Conclusions - This study assesses the impact of authenticity on the behavioral intention of electrical energy saving. In order to enhance the practice of electrical energy saving, it is efficient strategy for policy-maker to improve the perceived authenticity of individuals.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.9 no.2
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• pp.137-144
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• 2015

In this paper, we present an inertial sensor-based gait analysis system to measure and analyze lower-limb movements. We developed an integral AHRS(Attitude Heading Reference System) using a combination of rate gyroscope, accelerometer and magnetometer sensor signals. Several AHRS modules mounted on segments of the patient's body provide the quaternions representing the patient segments's orientation in space. And a method is also proposed for calculating three-dimensional inter-segment joint angle which is an important bio-mechanical measure for a variety of applications related to rehabilitation. To evaluate the performance of our AHRS module, the Vicon motion capture system, which offers millimeter resolution of 3D spatial displacements and orientations, is used as a reference. The evaluation resulted in a RMSE(Root Mean Square Error) of 1.08 and 1.72 degree in yaw and pitch angle. In order to evaluate the performance of our the gait analysis system, we compared the joint angle for the hip, knee and ankle with those provided by Vicon system. The result shows that our system will provide an in-depth insight into the effectiveness, appropriate level of care, and feedback of the rehabilitation process by performing real-time limb or gait analysis during the post-stroke recovery.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.11 no.3
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• pp.207-214
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• 2017

The problem of trunk stability is a major factor in back pain.. Abdominal draw in maneuver(ADIM), One of the trunk stabilization exercises to relieve lumbar instability, is a method of inducing selective contraction of the transverse abdominis associated with anticipatory posture control among the abdominal stabilization muscles. ADIM is usually performed with a visual feedback by applying a pressure biofeedback unit(PBU) under the lumbar at the supine position, which is not functional compared to the sitting position. This study was conducted to investigate the effect of ADIM applied in supine and sitting position on 31 healthy men and women. In each posture, muscle activity was measured by rectal abdominis (RA), external oblique (EO), transverse abdominis (TrA)/internal obilique (IO) and erector spinae (ES) using wireless EMG. In the result, there was no significant difference between RA and EO between the two postures and there was a significant difference between TrA / IO and ES. In both postures, the activity of TrA/IO was higher than that of RA, and the effect of ADIM was shown to be the same, whereas TrA/IO and ES showed higher activity in sitting position. This means that the activity of the muscles involved in the postural stability and lumbar stability is increased further in the sitting position. Therefore, ADIM in sitting, which can be applied more easily in daily life, is useful for improving lumbar stability.

• The Journal of Korean society of community based occupational therapy
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• v.3 no.1
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• pp.33-42
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• 2013

Objective : The purpose of this study is to assess effects of Robot-assisted therapy on function of upper extremity in stroke patients. Method : A total of 11 patients suffered from stroke participated in this study. Inpatients of 4 people and outpatients of 7 people divided by 12 months conducted Robot-assisted therapy for 5~6 weeks. Therapists selected appropriate exercise mode to patients, and patients Patients performed the reaching exercise was repeated with looking monitor provided 3-dimensional feedback. Before and after treatment of upper extremity functions was compare by Wolf Motor Function(K-WMFT), Box & Block Test(BBT), Dynamometer, average execution time. Result : Grip power, K-WMFT, BBT, average performance times were promoting in all subjects, and only showed statistically significant changes in outpatients. But outpatients did not show statistically significant changes in inpatients. Conclusion : Robotic-assisted therapy in stroke patients have a positive impact on upper extremity function that could confirm that. In the future, Robots-assisted therapy is expected to be useful for stroke patients in the area of occupational therapy.