• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.6
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• pp.37-48
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• 2005

The efficiency of power supply circuits such as DC-DC converters and batteries varies on the trend of the power consumption because their efficiencies are not fixed. To analyze the efficiency of power supply circuits, we need the temporal behavior of the power consumption of the loads, which is dependent on the activity factors of the devices during the operation. Since it is not easy to model every detail of those factors, one of the most accurate power consumption analyses of power supply circuits is measurement of a real system, which is expensive and time consuming. In this paper, we introduce an active load emulator for embedded systems which is capable of power measurement, logging, replaying and synthesis. We adopt a pattern recognition technique for data compression in that long-term behaviors of power consumption consist of numbers of repetitions of short-term behaviors, and the number of short-term behaviors is generally limited to a small number. We also devise a heterogeneous structure of active load elements so that low-speed, high-current active load elements and high-speed, low-current active load elements may emulate large amount and fast changing power consumption of digital systems. For the performance evaluation of our load emulator, we demonstrate power measurement and emulation of a hard drive. As an application of our load emulator, it is used for the analysis of a DC-DC converter efficiency and for the verification of a low-power frequency scaling policy for a real-time task.

• Child Health Nursing Research
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• v.8 no.4
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• pp.435-448
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• 2002

Accidents are important causes of death and disability in children. They also have enormous financial implications. Young children become an victim of accidents easily because of their physical fragileness and their coping behavior being vulnerable to any actions taken by accidents. Once they have a accident, the children whose not fully developed, suffer from devastating long-term after-effects. Lee, Lee, Kang and Han(1995) reported that ninety percent of accidents can be prevented. But there is no national system to manage, evaluate and analyse the information about child accidents, even though it is necessary for accident prevention policies and health promotion of the general public. The purpose of the study was to determine how often children have accidents and define the accident prevention strategies in children. The investigator conducted a descriptive study by performing the surveys, interviews, and workshops for the 2,458 young children, 10 teachers, and 1,494 parents. The data collection for the study began on September 2000 and completed on April 20, 2001. The analysis of the data was done with Window SPSS 10.0 for descriptive statistics. Among those children, 1,298 children(52.8％) injured from accidents. The children who had accident answered that they injured from traffic accident(27.3％), inside the home(26.3％), on the playground(17.0％), during playtime(13.6％), in the school(5.9％) and food poisoning(7.1％). To define accident prevention strategies for the school children, the parents and the teachers who had a special interest in this topic formed a special task force under the guidance of the investigator. The team was charged to prepare the basis of content materials by identifying the problems, setting standards for the program, prioritizing the process, and selecting the methods of implementation and evaluation. Eight issues and concerns identified by the team were: 1)allowing young children to learn undesirable habits and behaviors that would bother others without knowing; 2) not guarding young children from car accident; 3)unattended accident at playground; 4) considering home places safe; 5)unattended accident at school. These issues were found to be coinciding with the actual child accident cases occurred recent years in Korea. Greater efforts are required to reduce unnecessary deaths and disability from childhood accidents. This study gave a very useful and important data to prepare accident prevention educational program and to prepare accident prevention strategies.

• Investigative Magnetic Resonance Imaging
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• v.2 no.1
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• pp.89-95
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• 1998

Purpose : To investigate the phosphorus metabolic abnormalities in skeletal muscle of patients with mitochondrial myopathy using in vivo $^{31}P$ magnetic resonance spectroscopy(MRS). Materials and Methods : Patients with mitochondrial myopathy(N=10) and normal control subjects (N=10) participated. All in vivo $^{31}P$ MRS examinations were performed on 1.5T whole-body MRI/MRS system by using an image selected in vivo spectroscopy (ISIS) pulse sequence that provided a $4{\times}4{\times}4{\;}cm^{3}$ volume of interest (VOI) in the right thigh muscle tissue. Peak areas for each phophorus methabolite were measured using a Marquart algorithm. Results : The specific features in patients with mitochondrial myopathy were a significant increase of Pi/PCr ratio (p=0.003) and a significant decrease of ATP/PCr ratio (p=0.004) as compared with normal controls. In particular, the ${\beta}-ATP/PCr$ ratio between controls and patients with mitochondrial myopathy was predominantly altered. Conclusions : In vivo $^{31}P$ MRS may be a useful modality in the clinical evaluation of patients with mitochondrial myopathy based on ATP/PCr and Pi/PCr ratios in skeletal muscle tissue and provides a valuable information in further understanding disorders of muscle metabolism.

• Phonetics and Speech Sciences
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• v.12 no.2
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• pp.63-72
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• 2020

This study aims to develop a video-based smart utterance deep analyser (SUDA) application that analyzes semiautomatically the utterances that child and mother produce during interactions over time. SUDA runs on the platform of Android, iPhones, and tablet PCs, and allows video recording and uploading to server. In this device, user modes are divided into three modes: expert mode, general mode and manager mode. In the expert mode which is useful for speech and language evaluation, the subject's utterances are analyzed semi-automatically by measuring speech and language factors such as disfluency, morpheme, syllable, word, articulation rate and response time, etc. In the general mode, the outcome of utterance analysis is provided in a graph form, and the manger mode is accessed only to the administrator controlling the entire system, such as utterance analysis and video deletion. SUDA helps to reduce clinicians' and researchers' work burden by saving time for utterance analysis. It also helps parents to receive detailed information about speech and language development of their child easily. Further, this device will contribute to building a big longitudinal data enough to explore predictors of stuttering recovery and persistence.

• The Journal of Advanced Prosthodontics
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• v.7 no.2
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• pp.138-145
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• 2015

PURPOSE. The objective of this study was to conduct an in vitro comparative evaluation of polished and laser-dimpled titanium (Ti) surfaces to determine whether either surface has an advantage in promoting the attachment of epithelial-like cells and fibroblast to Ti. MATERIALS AND METHODS. Forty-eight coin-shaped samples of commercially pure, grade 4 Ti plates were used in this study. These discs were cleaned to a surface roughness (Ra: roughness centerline average) of 180 nm by polishing and were divided into three groups: SM (n=16) had no dimples and served as the control, SM15 (n=16) had $5-{\mu}m$ dimples at $10-{\mu}m$ intervals, and SM30 (n=16) had $5-{\mu}m$ dimples at $25-{\mu}m$ intervals in a $2{\times}4mm^2$ area at the center of the disc. Human gingival squamous cell carcinoma cells (YD-38) and human lung fibroblasts (MRC-5) were cultured and used in cell proliferation assays, adhesion assays, immunofluorescent staining of adhesion proteins, and morphological analysis by SEM. The data were analyzed statistically to determine the significance of differences. RESULTS. The adhesion strength of epithelial cells was higher on Ti surfaces with $5-{\mu}m$ laser dimples than on polished Ti surfaces, while the adhesion of fibroblasts was not significantly changed by laser treatment of implant surfaces. However, epithelial cells and fibroblasts around the laser dimples appeared larger and showed increased expression of adhesion proteins. CONCLUSION. These findings demonstrate that laser dimpling may contribute to improving the peri-implant soft tissue barrier. This study provided helpful information for developing the transmucosal surface of the abutment.

• 한국정보통신설비학회:학술대회논문집
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• 2005.08a
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• pp.259-262
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• 2005

Ground resistance measurement is an elementary technique for the evaluation of grounding system. There are main environmental factors to consider for correct measurement but the problem is that it is practically most cases to measure ground resistance unable to know the factors. This paper presents a methodology toward true value of resistance in the unknown circumstances, utilizing the defined term 'variation rate' of potential difference curve appearing in the distance to a current probe as in the three point fall-of-potential method which comprises the characteristics of environmental factors. This methodology is a induced result from the previous demostrated studies.

• Ecology and Resilient Infrastructure
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• v.2 no.2
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• pp.185-190
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• 2015

Greenhouse gas (GHG) emission from agricultural lands is recognized as one of important factors of global warming. The objective of this short communication was to evaluate the applicability of different soil GHG emission prediction models on agricultural systems in Korea. Four models, namely, DNDC, DAYCENT, EXPERT-N and COUP, were selected and the basic structure (e.g., components and sub-model), input variables, and output variables were compared. In particular, the availability and compilation of essential input variables were assessed. Major input variables needed for operating these predictive models were found to be available through database systems established by national organizations such as the Korea Meteorological Administration, the Korean Soil Information System, and the Rural Development Administration. However, in order to apply these models in Korea, it was necessary to calibrate and validate each of the models for the domestic landscape settings and climate conditions. In addition, field data of long-term monitoring of GHG emission from agricultural lands are limited and therefore should be measured.

• Journal of Biosystems Engineering
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• v.41 no.4
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• pp.288-293
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• 2016

Purpose: The purpose of this study was to investigate the key factors in designing a three-wheeled two-row soybean reaper (riding type) that is suitable for soybean production, and ensure worker safety by proposing optimal work conditions for the prototype of the designed machine in relation to the slope of the road. Methods: A three-wheeled two-row soybean reaper (riding type) was designed and its prototype was fabricated based on the local soybean-production approach. This approach was considered to be closely related to the prototype-designing of the cutter and the wheel driving system of the reaper. Load distribution on the wheels of the prototype, its minimum turning radius, static lateral overturning angle, tilt angle during driving, and The working and rear overturning (back flip) angle were measured. Based on the gathered information, investigations were conducted regarding optimal work conditions for the prototype. The investigations took into account driving stability and worker safety. Results: The minimum ground clearance of the prototype was 0.5 m. The blade height of the prototype was adjusted such that the cutter was operated in line with the height of the ridges. The load distribution on the prototype's wheels was found to be 1 (front wheel: F): 1.35 (rear-left wheel: RL): 1.43 (rear-right wheel: RR). With the ratio of load distribution between the RL and RR wheels being 1: 1.05, the left-to-right lateral loads were found to be well-balanced. The minimum turning radius of the prototype was 2.0 m. Such a small turning radius was considered to be beneficial for cutting work on small-scale fields. The sliding of the prototype started at $25^{\circ}$, and its lateral overturning started at $39.3^{\circ}$. Further, the critical slope angle for the worker to drive the prototype in the direction of the contour line on an incline was found to be $12.8^{\circ}$, and the safe angle of slope for the cutting was measured to be less than $6^{\circ}$. The critical angle of slope that allowed for work was found to be $10^{\circ}$, at which point the prototype would overturn backward when given impact forces of 1,060 N on its front wheel. Conclusions: It was determined that farmers using the prototype would be able to work safely in most soybean production areas, provided that they complied with safe working conditions during driving and cutting.

• Journal of Broadcast Engineering
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• v.13 no.1
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• pp.6-16
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• 2008

An instable wireless channel condition causes more packet losses and retransmissions due to interference, fading, station mobility, and so on. Therefore video streaming service over a wireless networks is a challenging task because of the changes in the wireless channel conditions and time-constraints characteristics of the video streaming services. To provide efficient video streaming over a wireless networks, QoS-enhanced MAC protocol, IEEE 802.11e, is standardized recently. Tn this paper, we propose a new network-adaptive H.264 video streaming mechanism in the IEEE 802.11e wireless networks. To improve the quality of video streaming services, video stream has to adapt to the changes in the wireless channel conditions. The wireless channel conditions are estimated by the packet loss probability and informed to the application layer by the cross-layering. According to the wireless channel information, the video streaming application filters out the low-priority data. This adaptation mechanism efficiently uses system resources because it drops the low-priority data in advance. Therefore, our cross-layer design can provide improved video streaming services to the end-user. Through the implementation and performance evaluation, we prove that the proposed mechanism improves the QoS of the video streaming by providing the smoothed playback.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.6303-6309
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• 2014

In this thesis, PBL was applied to the subject for improving students' many skills that modern industrial society demands. Our engineering school developed PBL problems for PBL use, applied the problems to classes and confirmed the effectiveness of PBL. The study subjects were 63 freshman students in H University who took the 'Introduce of computer engineering'. We applied 5 PBL problems for 15 weeks. They wrote and submitted a reflective journal when they finished the every given PBL activity. In addition, they completed a class evaluation form after the activity of 5th PBL Problem ended. The study showed that the students experienced the effectiveness of PBL, such as the comprehension of the studied contents, the comprehension of the cooperative learning, authentic experience, creative problem-solving skills, presentation skills, communication ability, self-directed study ability and confidence. Some difficulties in gathering together and spending much time were also encountered. The students realized that the PBL learning activities were important methods because the students could develop into future intelligent engineers that modern industrial society demands through PBL learning activities. The main goal of an engineering school is to produce specialists with creative problem solving ability so that the effects of this study are quite promising for our engineering school.