• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.4
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• pp.59-65
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• 2014

In this paper, in order to improve efficiency performance of power amplifiers, a mode changeable autotransformer is proposed. Efficiency performance at the low-power mode can be improved by adopting the mode changeable autotransformer. A dual-mode autotransfomrer CMOS power amplifier using a standard 0.18-${\mu}m$ CMOS process is designed in this work. Number of turns in a primary winding is re-configurated according to mode change between the high-power mode and the low-power mode. Thus, the efficiency performance of the power amplifier at each mode is optimized. EM and total circuit simulation results verify that low-power mode power added efficiency(PAE) at 24dBm output power is improved from 10.4% to 26.1% using the proposed multi-mode operation.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.3
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• pp.177-184
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• 2014

In chemical vapor deposition(CVD) tungsten silicide(WSix) dual poly gate(DPG) scheme, we observed the fluorine effects on gate oxide using the electrical and physical measurements. It is found that in fluorine-rich WSix NMOS transistors, the gate thickness decreases as gate length is reduced, and it intensifies the roll-off properties of transistor. This is because the fluorine diffuses laterally from WSix to the gate sidewall oxide in addition to its vertical diffusion to the gate oxide during gate re-oxidation process. When the channel length is very small, the gate oxide thickness is further reduced due to a relative increase of the lateral diffusion than the vertical diffusion. In PMOS transistors, it is observed that boron of background dopoing in $p^+$ poly retards fluorine diffusion into the gate oxide. Thus, it is suppressed the fluorine effects on gate oxide thickness with the channel length dependency.

• Korean Journal of Veterinary Research
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• v.51 no.3
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• pp.227-231
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• 2011

This study was undertaken to assess the lateral ventricle, which was some portion of brain and related to congenital anomalies, from 1, 2, 4, and 8 months of age in healthy micropigs. They were induced general anesthesia and performed magnetic resonance imaging (MRI) with a 0.3 Tesla magnet. Each age group was evaluated by three subjects such as lateral ventricular volume, ventricular volume ratio and asymmetry. T1 weighted transverse images were acquired for calculation of lateral ventricular and corresponding brain parenchyma areas. The ratio of bilateral ventricle areas used to analyze the asymmetry. The mean ventricular volumes of each month were $676.74{\pm}25.58mm^3$ (1 month-old), $630.64{\pm}143.84mm^3$ (2 month-old), $992.12{\pm}106.03mm^3$ (4 month-old) and $1172.62{\pm}237.57mm^3$ (8 month-old), respectively. The ventricular volume ratio was the smallest at 2 month-old and re-increased from that age. The ratio was significantly different between 2 month-old and other age groups (p < 0.05). The value of bilateral area ratio showed within 1.5 in all experimental animals. Consequently the lateral ventricle showed a positive correlation with aging and symmetric shapes in both sides. The developmental pattern of the lateral ventricle provides basic data in micropigs as an experimental animal model for physiological and neurosurgical approach.

• Journal of The Korean Astronomical Society
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• v.51 no.1
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• pp.5-16
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• 2018

We investigate the escape of $Ly{\beta}$ from emission nebulae with a significant population of excited hydrogen atoms in the level n = 2, rendering them optically thick in $H{\alpha}$. The transfer of $Ly{\beta}$ line photons in these optically thick regions is complicated by the presence of another scattering channel leading to re-emission of $H{\alpha}$, alternating their identities between $Ly{\beta}$ and $H{\alpha}$. In this work, we develop a Monte Carlo code to simulate the transfer of $Ly{\beta}$ line photons incorporating the scattering channel into $H{\alpha}$. Both $H{\alpha}$ and $Ly{\beta}$ lines are formed through diffusion in frequency space, where a line photon enters the wing regime after a fairly large number of resonance scatterings with hydrogen atoms. Various line profiles of $H{\alpha}$ and $Ly{\beta}$ emergent from our model nebulae are presented. It is argued that the electron temperature is a critical parameter which controls the flux ratio of emergent $Ly{\beta}$ and $H{\alpha}$. Specifically for $T\;=\;3{\times}10^4\;K$ and $H{\alpha}$ line center optical depth $\tau{\alpha}\;=\;10$, the number flux ratio of emergent $Ly{\beta}$ and $H{\alpha}$ is ~ 49 percent, which is quite significant. We propose that the leaking $Ly{\beta}$ can be an interesting source for the formation of $H{\alpha}$ wings observed in many symbiotic stars and active galactic nuclei. Similar broad $H{\alpha}$ wings are also expected in $Ly{\alpha}$ emitting halos found in the early universe, which can be potentially probed by the James Webb Telescope in the future.

• Journal of the Korean Society of Physical Medicine
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• v.15 no.3
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• pp.51-59
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• 2020

PURPOSE: The purpose of this study was to provide clinical basic data to reduce pain and improve function by comparing neck muscle activity and neck alignment using self-stretching and passive stretching exercises for chronic neck pain caused by forward head posture. METHODS: The subjects were divided into 15 subjects assigned to perform self-stretching exercise and 15 subjects assigned to perform passive stretching exercise. The intervention was conducted for a total of 4 weeks. The muscle activity in the neck was measured by surface electromyography (EMG) before intervention, and craniovertebral and cranial rotation angles were measured by X-ray. The 4-week intervention was conducted and the above items re-measured in the same manner and analyzed. RESULTS: Muscle activity within both groups after intervention using self-stretching or passive stretching exercise was significantly different (p < .05)(p < .01). Neck alignment of both groups was significantly different (p < .001)(p < .01). Further, muscle activities of the upper trapezius and splenius capitis muscles showed significant differences (p<.05). Lastly, neck alignment showed statistically significant difference (p < .05). CONCLUSION: Self-stretching exercise activated motor nerves as a posture correction exercise, thereby improving inhibition of muscle activity, muscle contraction delay, and pathological conditions of the muscle. For future research, interventions of self-stretching exercise will be needed for patients with chronic back pain accompanied by forward head posture, and various clinical studies on postural improvement of forward head posture by maintaining a normal muscle tone state are needed.

• Journal of Korean Library and Information Science Society
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• v.51 no.3
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• pp.251-279
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• 2020

This study noted the recent impact of Coronavirus Disease-19 (Corona 19) on the environment surrounding the library, and investigated the libraries' response activities. In addition, related issues on news media and social media were detected based on text mining techniques to engage environmental changes surrounding the library. Key issues were derived from 1,852 news reports on the library related to the Corona 19 situation and 227,983 tweets related to the library during the Corona 19 epidemic. Through this, implications were derived: prolonged 'Untact' situations, increased e-book lending, improved expectations for online services and librarians, and re-conceptualized library space. In addition, the direction of future services was discussed by selecting representative examples of library services provided in the non-face-to-face (untact) situation and dividing them into books, services, and spaces.

• Journal of Korean Library and Information Science Society
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• v.51 no.4
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• pp.231-247
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• 2020

As artificial intelligence (AI) has emerged as a promising future technology among the fourth industrial revolution, we are trying to apply artificial intelligence technology across all area of society, including libraries. This study investigated the effects, issues, and implications of artificial intelligence on university library services. As a research method, in-depth interviews were conducted with IT experts of university libraries in North America, and conclusions and discussion were drawn from interview results and related documents. Research results revealed that university libraries in North America were trying to build an infrastructure that facilitates information access and retrieval based on artificial intelligence systems and to provide new services in collaboration with AI research institutes in universities. This study raised issues regarding the expansion of the role of libraries and librarians, privacy, and data quality. It was also discussed that the need for re-education of university librarians to become software engineers who play a role in disseminating knowledge. In addition, this study suggested the investment for the establishment of the information system and an artificial intelligence research center in the library. The study discussed limitations of research due to changes in the research environment and suggestions for future research.

• Nutrition Research and Practice
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• v.17 no.2
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• pp.175-191
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• 2023

BACKGROUND/OBJECTIVES: The scientific evidence of a sodium-obesity association is limited by sodium intake assessments. Our specific aim is to synthesize the association between dietary sodium intake and obesity across the sodium intake assessments as evidenced by systematic reviews in adults. SUBJECTS/METHODS: A systematic search identified systematic reviews comparing the association of dietary sodium intakes with obesity-related outcomes such as body mass index (BMI), body weight, waist circumference, and risk of (abdominal) obesity. We searched PubMed on October 24, 2022. To assess the Risk of Bias in Systematic Reviews (ROBIS), we employed the ROBIS tool. RESULTS: This review included 3 systematic reviews, consisting of 39 unique observational studies (35 cross-sectional studies and 4 longitudinal studies) and 15 randomized controlled trials (RCTs). We found consistently positive associations between dietary sodium intake and obesity-related outcomes in cross-sectional studies. Studies that used 24-h urine collection indicated a greater BMI for those with higher sodium intake (mean difference = 2.27 kg/m²; 95% confidence interval [CI], 1.59-2.51; P < 0.001; I² = 77%) compared to studies that used spot urine (mean difference = 1.34 kg/m²; 95% CI, 1.13-1.55; P < 0.001; I² = 95%) and dietary methods (mean difference = 0.85 kg/m²; 95% CI, 0.1-1.51; P < 0.05; I² = 95%). CONCLUSIONS: Quantitative synthesis of the systematic reviews has shown that cross-sectional associations between dietary sodium intake and obesity outcomes were substantially different across the sodium intake assessments. We need more high-quality prospective cohort studies and RCTs using 24-h urine collection to examine the causal effects of sodium intake on obesity.

• Plant Journal
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• v.5 no.1
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• pp.51-59
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• 2009

The global plant construction market has grown dramatically since 2000. As the market grows, domestic EPC contractors are expanding to meet its needs and have made great strides in terms of economic indicators from a decade ago. Larger projects involve a number of risk factors, such as volatile oil prices, however, and thus require quantitative and elaborate project management techniques for the ultimate success of a project's profitability. In addition, many Korean companies face difficulties in predicting potential risks and problems due to a lack of experience in dealing with the global market trend toward projects based on the Cost-re(Cost Reimbursable) contract as opposed to those based on the LSTK(Lumpsum Turnkey) contract. This study will examine methods and types of man-hour management according to plant project contract types. Further, it will explore the man-hour management system for successful completion of projects by satisfying the client's needs and enhancing the convenience in engineers' using the system. Additionally, this study will analyze the current system and identify its problems to address potential problems.

• Journal of Korean Academy of Nursing
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• v.35 no.6
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• pp.1091-1100
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• 2005

Purpose: The purpose of this study was to develop an instrument to measure nursing professional values. Method: Forty preliminary items were selected by classifying 223 basic items extracted via a literature study and in-depth interviews of subjects and testing the relevance of their contents. In order to verify the reliability and relevance of the preliminary instrument, data was collected from 504 nurses in 3 general hospitals. Result: As a result of the item analysis, 29 items were selected from a total of 40 items. Five factors were extracted by factor analysis, and the total variance was $51.5\%$. For the explanation of variances by factors, the 1 st factor, 'self-concept of the profession' accounted for $14.8\%$, the 2nd factor, 'social awareness' $12.1\%$, the 3rd factor, 'professionalism of nursing' $9.8\%$, the 4th factor, 'the roles of nursing service' $9.1\%$, and the 5th factor, 'originality of nursing', $5.6\%$. Cronbach's Alpha of those 29 items was .9168, which was high. Conclusion: This paper is meaningful in a way that it developed a tool capable of measuring nursing professional values, which reflects the characteristics of our country. In order to re-verify the relevance and stability of this tool, it is necessary that comparative studies should be conducted.