• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.2
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• pp.164-170
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• 2010

In brushless DC motor, current flow should be controlled such that only properly selected 2 out of 3 phases carry current depending on the position of rotor. In order to detect position of rotor, hole sensor, encoder, optical position-detecting sensor, and magnetic position-detecting sensor are frequently employed. These sensors not only often cause malfunction in low and high temperature but they also have disadvantage of increasing cost and size of an motor system. To reduce the cost and size and to increase the robustness of the motor system, recently researches on sensorless motor dirve are very active. This paper proposes a novel unipolar PWM switching method that can improve the control problem caused by the difficulty of detecting zero crossing point at high revolution speed by minimizing the switching noise while increasing the lifespan of the drive system.

• Environmental Mutagens and Carcinogens
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• v.24 no.4
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• pp.163-170
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• 2004

CYP1B1 enzyme metabolize PAHs and estradiol. CYP1B1 metabolize estradiol to 4-hydroxyestradiol that is considered as carcinogenic metabolite. Luciferase activity was induced about 20 folds over that control by 1 nM TCDD (2,3,7,8-tetrchlorodibenzo-p-dioxin) and these inductions were dose-dependent. Recent industrialized society, human hasbeen widely been exposed to widespread environmental contaminants such as PAHs (polycyclic aromatic hydrocarbon) that are originated from the incomplete combustion of hydrocarbons. PAHs are known to be ligands of the AhR (aryl hydrocarbon receptor). Induction of cytochrome P4501B1(CYP1B1) in cell culture is widely used as a biomarket for PAHs. Therefore we have studied the effect of PAHs in the human breast cancer cells MCF-7 to evaluate bioactivity of PAHs. Cytochrome P4501B1(CYP1B1) is known to be inducible by xenobiotic compounda such as policyclic aromatic hydrocarbon (PAH) and dioxins such as 2,3,7,8-tetrachloro-dibenzo-p-dioxin(TCDD). And these induction of CYP1B1 is also regulated by many categories of chemicals. In order to investigate the effects of several chemicals on CYP1B1 gene expression in luciferase gene, and then transfected into these cells. After treatment of chemicals, the luciferase activity was measured. We examined effects of PAHs on the CYP1B1-lucifrease reporter gene and CYP1B1 mRNA level. Benzo(k)fluoranthene showed strong response to CYP1B1 promoter activity stimulation, and also CYP1B1 mRNAs increase in MCF-7 cells in a concentration-dependent manner. flvonoids such as genistein decreased B(k)F induced luciferase activity at low concentration. it exhibited stimulatory effect at high concentration.

• Journal of Korean Academy of Nursing
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• v.32 no.4
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• pp.560-569
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• 2002

The purpose of this study was to develop an instrument to measure family resilience for Korean families with a chronically ill child, and to test the validity and reliability of the instrument. Method: The items of instruments used based on the researchers' previous study of concept analysis of Korean family resilience. Nineteen item scales were developed with five domains. In order to test reliability and validity of the scale, data were collected from 231 families, who had a child with a chronic illness. Data was collected between August and September of 2001 in a 3rd level University Hospital in Seoul, Korea. Result: The results were as follows: As a result of the item analysis, 19 items were selected from the total of 37 items, excluding items with low correlation with the total scale. Five factors were evolved by factor analysis, which explained 56.4% of the total variance. The first factor 'Family strength' explained 28.5%, 2nd factor 'Family maturity' 8.7%, 3rd factor 'The ability to use of external resources' 7.0%, 4th factor 'Control' 6.6%, 5th factor 'The driving force for finance' 5.7%. The attributes in these factors were different with those identified by concept analysis of the family resilience in Korean families from the previous study. Cronbach's $\alpha$ coefficient of this scale was .8039 and Guttman spilt- half coefficient was .8184. Conclusion: The study support the reliability and validity of the scale. Because the main concept of family resilience was family strength, there were distinct differences in dimensions of family functioning scales.

• Journal of Korean Academy of Nursing
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• v.46 no.1
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• pp.140-148
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• 2016

Purpose: This study was performed to determine the physical and psychological effects of an urban forest-walking program for office workers. For many workers, sedentary lifestyles can lead to low levels of physical activity causing various health problems despite an increased interest in health promotion. Methods: Fifty four office workers participated in this study. They were assigned to two groups (experimental group and control group) in random order and the experimental group performed 5 weeks of walking exercise based on Information-Motivation-Behavioral skills Model. The data were collected from October to November 2014. SPSS 21.0 was used for the statistical analysis. Results: The results showed that the urban forest walking program had positive effects on the physical activity level (U=65.00, p <.001), health promotion behavior (t= - 2.20, p =.033), and quality of life (t= - 2.42, p =.020). However, there were no statistical differences in depression, waist size, body mass index, blood pressure, or bone density between the groups. Conclusion: The current findings of the study suggest the forest-walking program may have positive effects on improving physical activity, health promotion behavior, and quality of life. The program can be used as an effective and efficient strategy for physical and psychological health promotion for office workers.

• Journal of IKEEE
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• v.24 no.1
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• pp.147-153
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• 2020

Conventional lane detection algorithms have problems in that the detection rate is lowered in road environments having a large change in curvature and illumination. The probabilistic Hough transform method has low lane detection rate since it exploits edges and restrictive angles. On the other hand, the method using a sliding window can detect a curved lane as the lane is detected by dividing the image into windows. However, the detection rate of this method is affected by road slopes because it uses affine transformation. In order to detect lanes robustly and avoid obstacles, we propose driving assist system using semantic segmentation based on deep learning. The architecture for segmentation is SegNet based on VGG-16. The semantic image segmentation feature can be used to calculate safety space and predict collisions so that we control a vehicle using adaptive-MPC to avoid objects and keep lanes. Simulation results with CARLA show that the proposed algorithm detects lanes robustly and avoids unknown obstacles in front of vehicle.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.1
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• pp.183-189
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• 2018

This paper proposes distributed file placement and coverage expansion techniques for mitigating the traffic bottleneck in backhaul for small-cell networks. In order to minimize the backhaul load with limited memory space, the proposed scheme controls the coverage and file placement of base station according to file popularity distribution and memory space of base stations. In other words, since the cache hit ratio is low when there is small memory capacity or widespread file popularity distribution, the base stations expand its coverage and cache different set of files for the user located in overlapped area to exploit multiple cached file sets of base stations. Our simulation results show that the proposed scheme outperforms the conventional cache strategy in terms of network throughput when there is small memory capacity or widespread file popularity distribution.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.1B
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• pp.11-17
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• 2003

In this paper, we presented the dynamic random access channel allocation method under the priority based scheduling policy in order to improve the system performance of HIPERLAN/2 standardized by ETSI According to the scheduling policy, AP scheduler primarily allocates the resource to the collision MT This scheduling policy bring about decreasing the transmission delay of collision MT Dynamic RCH(random access channel) allocation method decreases the collision probability by increasing the number of RCH slots in case of low traffic. While it increases the maximum throughput by increasing the number of the data transmission slots in case of high traffic Therefore dynamic allocation method of RCH slots decreases the scheduling delay and increases the throughput When we evaluate the performance of presented method based on standards, we saw that the presented method improve the performance of the MAC protocol in terms of throughput and transmission delay.

• Korean Journal of Biological Psychiatry
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• v.17 no.2
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• pp.70-78
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• 2010

Objectives : This study investigated the differences of working memory among the subtypes of ADHD. Methods : Eighty-one children and adolescents with ADHD and thirty normal controls were recruited. Children with any cognitive disorders and low intelligence were excluded. In order to evaluate the verbal and visuospatial working memory, Digit span and Finger windows tasks were measured, respectively. Performances on these measures between children with ADHD and controls were compared. Further, performances among the groups of ADHD predominantly inattentive(ADHD-IA)(n=40), predominantly hyperactive-impulsive(ADHD-HI)(n= 10), and combined type(ADHD-C)(n=31), were compared. Results : Scores of Finger windows forward task were lower in the ADHD group as compared to the control group, whereas, the Digit span forward showed no difference. Both scores of Digit span backward and Finger windows backward task were lower in the ADHD group than the controls. Children with ADHD-IA performed poorer than children with ADHD-C on the Finger windows backward task. Conclusion : The results of this study showed that children with ADHD have deficits in spatial short-term memory and verbal and visuospatial working memory when compared to normal children. The deficits were evident in children with ADHD-IA subtype and in particular, performance on the visuospatial working memory task in this group was poorer than the ADHD-C group.

• Journal of the Korea Society for Simulation
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• v.22 no.1
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• pp.31-40
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• 2013

Recent development in science and technology has modernized the weapon systems of ROKN (Republic Of Korea Navy). Although the cost of purchasing, operating, and maintaining the cutting-edge weapon systems has been increased significantly, the national defense expenditure is under a tight budget constraint. In order to maintain the availability of ships with low cost, we need an efficient and scientific method for managing repairable parts. In this study, we propose a simulation model that computes the availability of ship's repairable parts. Our model is based on the METRIC (Multi Echelon Technique Repairable Item Control) model and extends to five sub-models to reflect the realistic situations that arise in the navy, such as planned maintenance, condemnation, lateral transshipment, and cannibalization. We have performed simulations to compute the availability of repairable parts while setting the part-level consistent throughout the five models and carried out two sensitivity analyses. The simulation results show the differences in the part availability in different models. The experiments confirm our claim that ROKN needs an inventory management system that captures the operational characteristics of the navy.

• Journal of Digital Convergence
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• v.13 no.5
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• pp.269-276
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• 2015

In order to examine the relationship between cholesterol level on serum and depression in Korean adults, this study used data of the fourth Korea National Health and Nutrition Examination Survey (KNHANES). 834 persons with depressive symptoms were selected as an index group and 3,317 persons without depressive symptoms as a control group, and odds ratios were calculated by multivariate logistic regression. As a result, odds ratio of depressive symptoms was higher in low LDL group (OR=6.435, 95% CI; 2,358-17.557) than in high LDL group adjusted after monthly income, marital status, period of education, occupation, smoking status, and physical activity. Etiopathogenic mechanism must be found by convergent study in the future.