• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.504-510
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• 2017

This paper presents an AC-DC power module design and evaluates its efficiency and reliability when used for electronics appliances. This power module consists of a PWM control IC, power MOSFETs, a transformer and several passive devices. The module was tested at an input voltage of 220V (RMS) (frequency 60 Hz). A test was conducted in order to evaluate the operation and power efficiency of the module, as well as the reliability of its protection functions, such as its over-current protection (OVP), overvoltage protection (OVP) and electromagnetic interference (EMI) properties. Especially, we evaluated the thermal shut-down protection (TSP) function in order to assure the operation of the module under high temperature conditions. The efficiency and reliability measurement results showed that at an output voltage of 5 V, the module had a ripple voltage of 200 mV, power efficiency of 73 % and maximum temperature of $80^{\circ}C$ and it had the ability to withstand a stimulus of high input voltage of 4.2 kV during 60 seconds.

• Journal of the Korean Society for information Management
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• v.38 no.4
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• pp.113-128
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• 2021

In this study, we aimed to understand the public opinion on COVID-19 vaccine. To achieve the goal, we analyzed COVID-19 vaccine-related Twitter posts. 45,413 tweets posted from March 16, 2020 to March 15, 2021 including COVID-19 vaccine names as keywords were collected. The 12 vaccine names used for data collection included 'Pfizer', 'AstraZeneca', 'Modena', 'Jansen', 'NovaVax', 'Sinopharm', 'SinoVac', 'Sputnik V', 'Bharat', 'KhanSino', 'Chumakov', and 'VECTOR' in the order of the number of collected posts. The collected posts were analyzed manually and automatedly through keyword analysis, sentiment analysis, and topic modeling to understand the opinions for the investigated vaccines. According to the results, there were generally more negative posts about vaccines than positive posts. Anxiety about the aftereffects of vaccination and distrust in the efficacy of vaccines were identified as major negative factors for vaccines. On the contrary, the anticipation for the suppression of the spread of coronavirus following vaccination was identified as a positive social factor for vaccines. Different from previous studies that investigated opinions about COVID-19 vaccines through mass media data such as news articles, this study explores opinions of social media users using keyword analysis, sentiment analysis, and topic modeling. In addition, the results of this study can be used by governmental institutions for making policies to promote vaccination reflecting the social atmosphere.

• The Journal of the Korea Contents Association
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• v.22 no.7
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• pp.676-683
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• 2022

Minimizing patient movement during CT-guided lung biopsy is an important factor in the procedure. To minimize movement, a vacuum cushion was used to evaluate its effectiveness. The subjects of this study were 116 patients aged 40 years or older who had good coordination with postural fixation and breathing control. Posture measurements were performed in the supine position, prone position, oblique position, and lateral position according to each position of the lung lesion biopsy lesion. Measurement positions were measured in the anterior, posterior, right, and left positions based on the anatomical posture. In the prone position, the mean difference between the non-use and the use of the posterior was 1.7905, and t=2.913 (p<0.01), and the mean difference between the non-use/use was statistically significant. The difference between the unused and used averages of left was 2.4105, and the difference between the left averages was also significant with t=3.684 (p<0.01). The difference between the unused and used averages of the right was 2.3263, with t=3.791 (p<0.01). The mean difference between unused and used is statistically significant. As a result of statistical analysis, the biopsy of the lung lesion using a fixation device showed less movement in all postures. It is considered that it is meaningful in that it is possible to conduct a more accurate biopsy procedure and minimize the patient's posture movement by using a fixation device during the CT-guided biopsy of the lung lesion.

• Radiation Oncology Journal
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• v.19 no.4
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• pp.359-368
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• 2001

Purpose : To determine the long-term results of bladder-preserving approach by transurethral resection of the bladder (TURB), systemic chemotherapy, and radiation therapy for muscle-invasive bladder cancer Methods and materiaals : From 1991 Jan. through 1994 Dec., 25 patients with muscle invading clinical stage T2 to T4NxM0 bladder cancer were treated with induction by maximal TURB and (arm 1, n=4) three cycles of chemotherapy [MVAC(methotrexate, vincristine, adriamycin, ciplatin)] followed by 64.8 Gy of radiation with concomitant cisplatin, or two cycles of chemotherapy [MCV (methotrexate, ciplatin, vincristine)] after irradiation with concomitant cisplatin (arm 2, n=14), or concurrent chemoradiation only (arm 3, n=7). Tumor response was scored as a clinical complete response (CR) when the cystoscopic tumor-site biopsy and urine cytology results were negative. Those with less than a CR underwent cystectomy. The median follow-up of all patients was 70 months. Resulst : Most treatment toxicities were mild to moderate. Grade 3 acute hematologic toxicity and chronic cystitis were observed in only 1 and 2 patients, respectively. Overall 5 year survival was $67.3\%$. Complete remission rate was $80\%$ (20/25). Sixty-three percent of all survivors retained their bladders. In multivariate analysis, prognostic factors that significantly affect survival were T-stage (p=0.013) and Complete remission (p=0.002). Conclusion : Combined modality therapy with TURB, chemotherapy, and radiation has a $67.3\%$ overall 5 year survival rate. This result is similar to cystectomy-based studies for patients of similar clinical stages.

• Journal of Korean Society of Forest Science
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• v.88 no.3
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• pp.292-298
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• 1999

Huber value and leaf specific conductivity were investigated for determining the hydraulic conductance of six deciduous hardwood species subjected to five levels of artificial shade treatments. Huber values measured in full sun were in the ranges of $1.5{\sim}9.1mm^2/dm^2$, $1.3{\sim}2.6mm^2/dm^2$, $1.5{\sim}5.3mm^2/dm^2$ in June, July, and September, respectively in the first year. The values generally decreased with increasing the shading in most of the species studied. Because of early defoliation in September, most of the values measured were also higher in September than in July. Huber values were quite different between those of the first year and those of the second year in most of the species studied, but the seasonal variation of Huber values and shading effects to the values seemed to be similar between the first and the second years. The values of leaf specific conductivity(LSC) measured in Betula platyphylla var. japonica. B. schmidtii, Zelkova serrata, Acer mono for 2 years were in the range of $4.0{\sim}80.0{\mu}{\ell}/dm^2$ by season and by shading treatment. But in Ligustrum obtusifolium and Prunus sargentii, the values were in the ranges of $4.0{\sim}280.0{\mu}{\ell}/dm^2$ and $8.0{\sim}120{\mu}{\ell}/dm^2$, respectively with having quite different values compared with those of the above species. Seasonal variation of LSC values was more or less irregular by species and by treatment year, but the LSC values of B. platyphylla vac. japonica, B. schmidtii, and P. sargentii in the first year and also those of Z. serrata and P. sargentii in the second year were mostly higher in September than in July. The LSC values seemed to be generally decreased with increasing the artificial shading in all of the species studied.