• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.2
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• pp.155-164
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• 2013

Two design techniques for more accurate and more convenient hybrid positioning system with visible light communication (VLC) and ad-hoc wireless network infrastructure are proposed, in order to overcome the problems of high estimation error, high cost, and limited service range of the conventional positioning techniques. First method is based on a non-carrier VLC based hybrid positioning technique for applications involving of low data rate optical sensing and narrow-range visible light reception from transmitter, and long-range positioning. The second method uses a 4 MHz carrier VLC-based hybrid positioning technique for a high data rate optical sensing and wide-range visible light receiving from transmitter, and mid-range positioning applications. In indoor environments with obstacles where there are long-range 7731.4cm and mid-range 2368cm distances between an observer and a target respectively, the hybrid positioning developed with two design techniques are tested, and the proposed system is verified and analyzed in this paper.

• Journal of Korean Academy of Nursing Administration
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• v.4 no.2
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• pp.351-361
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• 1998

The purpose of this study was to explore whether there is a point within the range of physical impairment after which the cost of home care exceeds the cost of nursing home care among the elderly who require long-term care. The provision of long-term care for the elderly is a major health policy issue, in part due to the aging of the American population and dramatic increase in health care costs. The framework for this study was guided by Pollak's(1973)model of costs of alternative care settings for the elderly. This study used a retrospective, descriptive correlational design. Physical impairment was measured by the modified Index of Activities of Daily Living(Katz et al. 1963). Cost of care was measured by the average cost per patient per day. The sample for this study included 67 patients receiving long-term care at home from the Long-term Home Health Care Programs (LTHHCPs) and 67 patients receiving long-term care in nursing homes. Data were collected on patient characteristics. including activities of daily living and cognitive impairment. and on the number of physician visits. emergency room visits. and hospitalization from the patient records. For each patient. Medicaid cost data for home care services/or nursing home services were collected from the financial department of each home care agency or nursing home. The living costs and informal care costs were estimated for home care patients. The results indicated that the home care sample and the nursing home sample were similar in terms of gender. ethnic background. and marital status. The elderly patients in the home care sample were: however. younger and less physically impaired than those in the nursing home sample. The hypotheses of this study were supported: For elderly persons with physical impairment scores below 12(possible range of 0 to 14), cost of care was lower in home care than in the nursing home care setting. However, for elderly persons with physical impairment scores above 12. the cost of care was higher in home care than in the nursing home care setting. Thus. in this sample for elderly patients with extreme physical impairment, the cost of home care exceeded the cost of nursing home care.

• Journal of muscle and joint health
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• v.27 no.2
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• pp.160-168
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• 2020

Purpose: This study aimed to provide basic data for the development of an education program on diabetic foot prevention care for care helpers in long term care facilities. Additionally, it sought to determine care helpers' knowledge and practice regarding diabetic foot prevention care, and to identify the correlation between such knowledge and practice. Methods: This cross-sectional study employed a structured questionnaire. Participants consisted of 90 care helpers who were working in three long term care facilities in Jeju city. Data collection was conducted from September to November 2016. Results: The mean knowledge and practice scores were 8.77±1.28 (range 0~10) and 28.17±2.44 (range 10~30), respectively. Practice regarding diabetic foot prevention care was significantly different by care helpers' gender (t=-2.28, p=.024), period of career in the long term care facility (F=3.29, p=.025), and received education on diabetic foot prevention care (t=3.08, p=.005). A positive correlation was observed between knowledge and practice (r=.35, p<.001). Conclusion: To improve the practice of diabetic foot prevention care, specialized education programs that consider gender and period of career in the long term care facility as well as the improvement of the level of knowledge of care helpers on diabetic foot prevention care are needed.

• Journal of Chest Surgery
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• v.52 no.2
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• pp.78-84
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• 2019

Background: Pulmonary thromboembolism (PTE) is a life-threatening disease with high mortality. This study aimed to assess the outcomes of surgical embolectomy and to clarify the sustained long-term effects of surgery by comparing preoperative, postoperative, and long-term follow-up echocardiography outcomes. Of 22 survivors, 21 were followed up for a mean (median) period of $6.8{\pm}5.4years$ (4.2 years). Methods: We retrospectively reviewed 27 surgical embolectomy cases for massive or submassive acute PTE from 2003 to 2016. Immediate and long-term follow-up outcomes of surgical embolectomy were assessed on the basis of 30-day mortality, long-term mortality, postoperative complications, right ventricular systolic pressure, and tricuspid regurgitation grade. Results: The 30-day and long-term mortality rates were 14.8% (4 of 27) and 4.3% (1 of 23), respectively. Three patients had major postoperative complications, including hypoxic brain damage, acute kidney injury, and endobronchial b leeding, respectively (3.7% each). Right ventricular systolic pressure (median [range], mm Hg) decreased from 62.0 (45.5-78.5) to 31.0 (25.7-37.0, p<0.001). The tricuspid valve regurgitation grade (median [range]) decreased from 1.5 (0.63-2.00) to 0.50 (0.50-1.00, p<0.05). The improvement lasted until the last echocardiographic follow-up. Conclusion: Surgical embolectomy revealed favorable mortality and morbidity rates in patients with acute massive or submassive PTE, with sustained long-term improvements in cardiac function.

• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.3
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• pp.155-163
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• 2022

The optimization of long-range ensemble climate prediction for rice phenology model with advanced bias correction method is conducted. The daily long-range forecast(6-month) of mean/ minimum/maximum temperature and observation of January to October during 1991-2021 is collected for rice phenology prediction. In this study, the concept of "buffer period" is newly introduced to reduce the problem after bias correction by quantile mapping with constructing the transfer function by month, which evokes the discontinuity at the borders of each month. The four experiments with different lengths of buffer periods(5, 10, 15, 20 days) are implemented, and the best combinations of buffer periods are selected per month and variable. As a result, it is found that root mean square error(RMSE) of temperatures decreases in the range of 4.51 to 15.37%. Furthermore, this improvement of climatic variables quality is linked to the performance of the rice phenology model, thereby reducing RMSE in every rice phenology step at more than 75~100% of Automated Synoptic Observing System stations. Our results indicate the possibility and added values of interdisciplinary study between atmospheric and agriculture sciences.

• Journal of Sensor Science and Technology
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• v.30 no.2
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• pp.76-81
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• 2021

In this study, we propose a machine vision system with a high object recognition rate. By utilizing a multiple-exposure image sensing technique, the proposed deep learning-based machine vision system can cover a wide light intensity range without further learning processes on the various light intensity range. If the proposed machine vision system fails to recognize object features, the system operates in a multiple-exposure sensing mode and detects the target object that is blocked in the near dark or bright region. Furthermore, short- and long-exposure images from the multiple-exposure sensing mode are synthesized to obtain accurate object feature information. That results in the generation of a wide dynamic range of image information. Even with the object recognition resources for the deep learning process with a light intensity range of only 23 dB, the prototype machine vision system with the multiple-exposure imaging method demonstrated an object recognition performance with a light intensity range of up to 96 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.182-190
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• 2011

A amplitude modulation(AM) range measuring system utilizes the phase difference of the modulated envelope of the reflected signal to measure the distance. It is known that the AM system has a problem in accuracy due to antenna leakage signals and spurious reflection signals, but an AM range measurement system using an active reflector, which shifts the frequency bands, has been proposed in order to minimize the measurement errors due to spurious signals. In this paper, a new phase measurement module for the AM range measurement system, which enables to measure long distance with good accuracy, is proposed. The modulation frequency is alternatively selected between 8 and 1 MHz, and the measured distance range with this module is up to 150 m within 2 cm accuracy. A JK flip-flop circuit is used for higher phase accuracy, and an XOR circuit is used to cover long distance.

• Journal of Broadcast Engineering
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• v.23 no.5
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• pp.693-700
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• 2018

In this paper, we propose a wireless video transmission scheme, providing medium and long range communication in the 2.4GHz band with beamforming. With this scheme, it is shown that the transmission rate of 32Mbps and received signal power of -77dBm is achieved with 4 antennas of 5dBi and 16dBm transmit power at each antenna connection for the distance of 3.6km. The scheme also provides transmission distance of 20km for 10~12Mbps with the 4 omni-directional antennas of 5dBi.

• Current Optics and Photonics
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• v.1 no.3
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• pp.221-227
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• 2017

To apply a square-shaped beam homogenizer to laser shock peening, it should be designed with a long working distance and by considering metal targets with various shapes and textures. For long working distances, a square-shaped beam homogenizer with a long depth of focus is required. In the range of working distance, the laser beam is required to have not only high efficiency but high uniformity, in other words, a good peening quality is guaranteed. In this study, we defined this range as the working distance for laser shock peening. We have simulated the effect of some parameters on the working distance. The parameters include the focal length of the condenser lens, pitch size of the array lens, and plasma threshold of the metal. The simulation was performed through numerical analysis by considering the diffraction effect.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.12
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• pp.174-182
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• 2015

In this paper, we developed the small size RGB sensor that recognizes a long distance using a low-cost color sensor. Light receiving portion of the sensor was used as a camera lens for far distance recognition, and illuminating unit was increased the strength of the light by using a high-power white LED and a lens mounted on the reflector. RGB color recognition algorithm consists of the learning process and the realtime recognition process. We obtain a normalized RGB color reference data in the learning process using the specimens painted with target colors, and classifies the three colors using the Mahalanobis distance in recognition process. We apply the developed the RGB color recognition sensor to a prototype of the part classification system and evaluate the performance of its.