• Journal of the Korean Society for Precision Engineering
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• v.33 no.11
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• pp.951-959
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• 2016

The aim of this paper is to investigate the improvement of surface characteristics of Stellite21 deposited layer by powder feeding type of direct energy deposition (DED) process using a plasma electron beam. Re-melting experiments of the deposited specimen is performed using a three-dimensional finishing system with a plasma electron beam. The acceleration voltage and the travel speed of the electron beam are chosen as process parameters. The effects of the process parameters on the surface roughness and the hardness of the re-melted region are examined. The formation of the re-melted region is observed using an optical microscope. Results of these experiments revealed that the re-melting process using a plasma electron beam can greatly improve the surface qualities of the Stellite21 deposited layer by the DED process.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.924-926
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• 2015

In this paper, we use the interface, which many countries concentrates research of Brain - Computer Interface with the device and MyndPlay based on the IoT intelligent Arduino. Finally we will make the Brain - Computer Connection environment, the purpose of Brain - Computer Interface. Recognizes the EEG of a person who wearing the equipment, analyze, classify, and we did a research to design an intelligent thing to suit user's condition. In addition, we use the XBee, and Bluetooth to communicate to other devices, such as smart phone. In conclusion, this paper check users current status via brain waves, and it allows to control the power and other objects by using the EEG(Electroencephalography).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.1922-1930
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• 2015

This paper presents the system design, implement, and measurement results of the testbed for the wireless RF energy harvesting system. The developed testbed can be used for RF power transfer and data communication using the 2.4 GHz and 900 MHz frequency bands. It allows to evaluate the system performances for the RF power and data transmission. The testbed can also be used to develop algorithms for efficient energy harvesting.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.1900-1911
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• 2015

In this paper, we introduce backscatter communication for power-limited sensors to enable long-range transmission in wireless sensor networks, and envision a way to avoid doubly near-far problem in wireless-powered communication network (WPCN) with this technology. In backscatter based WPCN, users harvest energy from both the signal broadcasted by the hybrid access point and the carrier signal transmitted by the carrier emitter in the downlink, and then transmit their own information in a passive way via the reflection of the carrier signal using frequency-shift keying modulation in the uplink. We characterize the energy-free condition and the signal-to-noise ratio (SNR) outage zone in backscatter based WPCN. Further, we propose backscatter based harvest-then-transmit protocol to maximize the sum-throughput of the backscatter based WPCN by optimally allocating time for energy harvesting and information transmission. Numerical results demonstrate that the backscatter based WPCN increases significantly the transmission range and diminishes greatly the SNR outage zone.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.9
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• pp.939-950
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• 1992

The performance of common spreading code scheme employing multiple-capture receiver is compared to that of transmitter-oriented (T/O) code division multiple access (CDMA) scheme in view of the possibility of collision-free transmissions and the effect of secondary multiple-access interference. For performance comparisons, secondary multiple-access interference is characterized for the common code scheme and the T/O CDMA scheme that assures perfectly collision-free transmissions. Throughput performance is then evaluated for these two schemes with direct-sequence spread-spectrum/differential-phase-shift-keying (DS-SS/DPSK) data modulation and forward-error-control coding (BCH codes) in the presence of an additive white Gaussian noise (AWGN). It is shown that when the number of radios is relatively large, the maximum normalized throughput is greater for the common code scheme than for the T/O CDMA scheme at a moderate signal-to-noise ration(SNR).

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.17 no.3
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• pp.245-256
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• 1999

Watershed delineation is the process of tracing surface water flow across a landscape to identify hydrologic basins. Manual and automated techniques have been developed to trace surface waters and locate watersheds on a variety of landscape. Low topographic relief landscapes, however, are particulary problematic for automated watershed delineation techniques. Therefore, this study aims at focusing the watershed delineation algorithm of low topographic relief landscape. By using topogrid, which manages enforcement drainage algorithms and incorporates topographic data into stream data, this study delineates watershed boundary in low relief landscape. Based on this research, in a low topographic relief landscape, enforcement drainage algorithms using topogrid generate better source grid to delineate watershed boundary than using only TIN. Also, comparing automated watershed delineation which incorporates contours and elevations into stream data with manual watershed delineation, we can know that the incorporation of both elevation and stream data generate more effective results.

• PNF and Movement
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• v.17 no.1
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• pp.69-79
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• 2019

Purpose: This study aims to investigate the effects of a group computerization cognitive rehabilitation program on cognitive function in patients with cognitive impairment. Methods: The subjects of this study comprised 34 patients with cognitive impairment (15 males and 19 females) who were randomized into two groups. The experimental group (n = 17) were trained with the group computerization cognitive rehabilitation program, while the control group (n=17) received traditional cognitive therapy. The interventions for both groups were performed for 1 hour per day, once a week for 12 weeks. The cognitive functions of the subjects before and after the experiment were measured using the Korean mini-mental state examination (K-MMSE), global deterioration scale (GDS), clinical dementia rating (CDR), and Lowenstein occupational therapy cognitive assessment (LOTCA). A paired t-test was conducted to examine the intragroup differences before and after the experiment, and ANCOVA was performed to check intergroup differences. Results: The intragroup comparison results showed that the cognitive function of the group that were trained with the group computerization cognitive rehabilitation program improved after the experiment more than for the group that received traditional cognitive therapy. The intergroup comparison results showed significant differences in orientation, visual perception, and visuomotor organization between the two groups. Conclusion: The results of this study confirmed that the group computerization cognitive rehabilitation program was more effective in improving cognitive function than the traditional cognitive therapy in patients with cognitive impairment. Based on the results of this study, the group computerization cognitive rehabilitation program can be used as an effective intervention method for patients with cognitive impairment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.2
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• pp.212-220
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• 2023

Over the past 50 years, red sea bream Pagrus major has been selectively bred for more than 10 generations to improve its growth rate. However, the effect of genetic factors on growth under low- or non-fish meal diet is still unclear. Here, we analyzed 251 individuals randomly mating 21 females (dam) and 16 males (sire) to determine the difference in growth between non-fish meal (i.e., treatment group) and fish meal-based diet (i.e., control group), if any. The kinship coefficient between each group of individuals and their parents was estimated by the KING (Kinship-based Inference for GWASs) software package. The presumed parents of 74 individuals in the treatment group and 57 individuals in the control group could be effectively identified. Notably, one specific female was consistently related to high- rather than low-growth individuals in both groups. In addition, more than one parent in each group was related to either high- or low-growth individuals. Parents of both high-growth individuals in the treatment group and low-growth individuals in the control group were also identified. Although further study is required on various growth factors, this study suggests the possibility of selective breeding under non-fish meal diet.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.7
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• pp.539-546
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• 2013

Surge phenomenon can be occurred in a compressor when compressor performance of turbofan engine for an aircraft is changed considerably in a short time on the cases like take-off phase and changing of RPM from idle to maximum, because performance of aircraft engine is changed suddenly. This study is aimed to avoid surge in a compressor. Dynamic simulation in a compressor is modeled by simulink in specific condition. Fuel flow is control input, rpm and air mass flow are expressed in terms of transfer function. Surge margin is obtained by using compressor performance map from NPSS. VIGV(Variable Inlet Guide Vane) is controlled by PD controller with difference between surge margin and reference. Finally this paper verifies IGV can prevent surge phenomenon in a compressor.

• Journal of Korean Academy of Nursing
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• v.41 no.4
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• pp.500-509
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• 2011

Purpose: Time-driven activity-based costing was applied to analyze the nursing activity cost and efficiency of a medical unit. Methods: Data were collected at a medical unit of a general hospital. Nursing activities were measured using a nursing activities inventory and classified as 6 domains using Easley-Storfjell Instrument. Descriptive statistics were used to identify general characteristics of the unit, nursing activities and activity time, and stochastic frontier model was adopted to estimate true activity time. Results: The average efficiency of the medical unit using theoretical resource capacity was 77%, however the efficiency using practical resource capacity was 96%. According to these results, the portion of non-added value time was estimated 23% and 4% each. The sums of total nursing activity costs were estimated 109,860,977 won in traditional activity-based costing and 84,427,126 won in time-driven activity-based costing. The difference in the two cost calculating methods was 25,433,851 won. Conclusion: These results indicate that the time-driven activity-based costing provides useful and more realistic information about the efficiency of unit operation compared to traditional activity-based costing. So time-driven activity-based costing is recommended as a performance evaluation framework for nursing departments based on cost management.