• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.4
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• pp.319-328
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• 2020

The recent use of distributed power generation systems constructed with DC-DC converters has become extremely popular owing to the rising need for environment friendly energy generation power systems. In this study, a new single-phase five-level inverter for off-grid applications constructed with a multilevel DC-DC step-up converter is proposed to boost a low-level DC voltage (36 V-64 V) to a high-level DC bus (380 V) and invert and connect them with a single-phase 230 V rms AC load. Compared with other traditional multilevel inverters, the proposed five-level inverter has a reduced number of switching devices, can generate high-quality power with lower THD values, and has balanced voltage stress for DC capacitors. Moreover, the proposed topology does not require multiple DC sources. Finally, the performance of the proposed topology is presented through the simulation and experimental results of a 400 W hardware prototype.

• Atmosphere
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• v.22 no.3
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• pp.321-330
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• 2012

Generation mechanisms of the three moderate-or-greater (MOG)-level clear-air turbulence (CAT) encounters over South Korea are investigated using the Weather Research and Forecasting (WRF) model. The cases are selected among the MOG-level CAT events occurred in Korea during 2002-2008 that are categorized into three different generation mechanisms (upper-level front and jet stream, anticyclonic flow, and mountain waves) in the previous study by Min et al. For the case at 0127 UTC 18 Jun 2003, strong vertical wind shear (0.025 $s^{-1}$) generates shearing instabilities below the enhanced upper-level jet core of the maximum wind speed exceeding 50 m $s^{-1}$, and it induces turbulence near the observed CAT event over mid Korea. For the case at 2330 UTC 22 Nov 2006, areas of the inertia instability represented by the negative absolute vorticity are formed in the anticyclonically sheared side of the jet stream, and turbulence is activated near the observed CAT event over southwest of Korea. For the case at 0450 UTC 16 Feb 2003, vertically propagating mountain waves locally trigger shearing instability (Ri < 0.25) near the area where the background Richardson number is sufficiently small (0.25 < Ri < 1), and it induces turbulence near the observed CAT over the Eastern mountainous region of South Korea.

• The Journal of Korean Society for Radiation Therapy
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• v.21 no.2
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• pp.75-82
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• 2009

Purpose: Measure the ozone level in the treatment room while treating a patient so want to know the degree of contamination caused by ozone occurrence. Materials and Methods: Use the linear accelerator (Clinac 21EX, Varian, USA) with the ozone meter (series-200, aeroQual, New Zealand) and water phantom (Wellhofer, IBA, Germany) is irradiated the radiation so that measured the ozone generation level according to MU, dose-rate, SSD, field size, energy, delay time and put the ozone meter in the treatment room actually while treating a patient so measured the daily ozone level variation. Results: While irradiating the radiation, degree of ozone contamination wasn't affected by the energy but mostly in case of electron beam, ozone level was higher than photon beam. The higher dose-rate (0.016~0.025 ppm/hr), the farther SSD (0.018~0.030 ppm/hr), the wider field sizes (0.016~0.025 ppm/hr), the more MU (0.018~0.046 ppm/hr), it occurred high ozone level. Ozone decrement according to delay time changed the background level (0.016 ppm/hr) after elapsed time of 10 minutes from irradiating radiation. And daily ozone occurrence level in the treatment room was below ozone standard level 0.1 ppm/hr (average:0.06 ppm/8 hr) but it could confirm that ozone generation level was included the level (max:0.038 ppm/hr) above 0.02 ppm/hr which patient could perceive. Conclusion: Through ozone level according to variation of certain conditions, actually in the treatment room ozone generation level didn't damaged to patients or workers. Commonly peoples think that ozone was harmful gas but it thought that small amount of ozone generation level while treating a patient was beneficial in the treatment room through air purge action of pathogenic germ or virus sterilization.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.5
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• pp.129-137
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• 2022

This study compared the sociodemographic characteristics and innovativeness of OPAL generation e-commerce users and non-users based on the innovation diffusion theory, and examined the effect of these personal characteristics on the availability of e-commerce use. The result showed that OPAL generation e-commerce users differed from non-users in gender, age, income level, education level, and functional, hedonistic, social and cognitive innovativeness. In addition, gender, age, educational level, functional and hedonistic innovativeness were found to be significant variables that determined the OPAL generation's use of e-commerce. Based on these results, we presented the theoretical and practical implications of this study.

• The Journal of Korean Academic Society of Nursing Education
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• v.28 no.3
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• pp.305-316
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• 2022

Purpose: The purpose of this study was to construct a structural equation model of organizational commitment in hospital nurses based on a job demands-resources model and to confirm the moderating effect(s) according to the nurses' generation. Methods: The model was constructed of the exogenous variables of social support, emotional intelligence, emotional labor, and job conflict and the endogenous variables of burnout, job engagement, and organizational commitment. The participants were 560 hospital nurses working in 3 general hospitals. Data were collected from August 1 to September 30, 2021, and analyzed using SPSS Window 23.0 and IBM AMOS 23.0. Results: The strongest factor directly influencing hospital nurses' organizational commitment was social support. In a multiple group analysis, nurses' generation had a partial moderating effect. In a generation-specific analysis, the Z generation group was higher than the X and Y generation groups in the variables of emotional labor and burnout related to organizational commitment. Conclusion: Based on the findings of this study, to improve hospital nurses' organizational commitment, social support is needed as an important management strategy. At the organizational level, we need to develop ways to improve organizational commitment by reducing the emotional labor and burnout of Generation Z.

• The Journal of Information Systems
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• v.23 no.4
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• pp.49-74
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• 2014

The introduction of smartphone caused the most revolutionary change in the domestic telecommunications market after the digital revolution. However, due to the saturation of the local market, it is expected to post negative growth in 2016 and the sales of national communication carriers is in stasis. Thus, the smartphone industry is starting to shift its marketing efforts to secure the silver generation who still has room for increase in the rate of smartphone usage. As the silver generation has physical limitations and differences in needs, the marketing strategy based on the smartphone utilization is not appropriate. This study suggests the new silver generation, who has high income level and similar characteristics to the younger generation, as the new customer segment for smartphone. We analyze the effects of the major variables of UTAUT on smartphone use, as well as examine how these relationships differ between the new silver and the net generation. We verified the hypotheses using a survey with 309 smartphone users. The research findings supported the hypotheses regarding the effects of performance expectancy, effort expectancy and facilitating conditions on smartphone use, but did not support the hypothesis on the effect of social influence. The result of the group comparisons showed that both generation have similar characteristics on innovativeness and cognitive absorption, but the moderating effect of age on performance expectancy, effort expectancy and use is stronger in conjunction with the new silver generation. The study results are expected to be used in establishing a marketing strategy for the new silver generation.

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.173.2-173.2
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• 2007

• Proceedings of the Korean Nuclear Society Conference
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• 1998.10a
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• pp.273-273
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• 1998

• The Korea Journal of Herbology
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• v.23 no.3
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• pp.103-112
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• 2008

Objectives : This research aimed to study the cytotoxicity and immuno modulating activity of fermented Artemisia argyi Lev. et Vant.(Compositae). Methods : Effect of fermented Artemisiae Argyi Folium extracts, which were fermented by Sacchromyces cerevisiae STV89(AFS), on cell viability, generation of ROS within cells, generation of NO and the level of cytokines($TNF-{\alpha}$ and IL-6) was measured using mouse macrophage RAW 264.7 cell. Results : 1. Result of MTT assay conducted to verify the cytotoxicity of fermented Artemisiae argyi folium extract illustrated that, when fermented Artemisiae argyi folium extract was processed for each concentration, there was no excessive induction of cytoxicity in the RAW 264.7 cell. 2. Fermented Artemisiae Argyi Folium extract increased the generation of H2O2 within RAW 264.7 cell as well as significantly increased inhibition of generation of H2O2 in macrophage induced by LPS. 3. Fermented Artemisiae Argyi Folium extract inhibited generation of NO in RAW 264.7 cell, and significantly inhibited increase in generation of NO of macrophage induced by LPS. 4. Fermented Artemisiae Argyi Folium extract, AFS has significantly reduced the increase in the generation of $TNF-{\alpha}$ above 10 ${\mu}g/mL$. 5. Fermented Artemisiae Argyi Folium extract, AFS has significantly reduced the increase in generation of IL-6 above 50 ${\mu}g/mL$. Conclusions : AFS fermented extract produced from Artemisiae Argyi Flium, have increased generation of ROS and reduced generation of NO in RAW 264.7 cell without excessively inducing cytotoxicity of RAW 264.7 cell. In addition, they displayed significant immuno modulating activities including inhibition of generation of $TNF-{\alpha}$ and IL-6 in macrophage, induced by LPS.

• The Journal of Korean Physical Therapy
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• v.22 no.6
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• pp.77-83
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• 2010

Purpose: The aim of this study was to do numerical analysis of the wavelength dependence in low level laser therapy (LLLT) using a finite element method (FEM). Methods: Numerical analysis of heat transfer based on a Pennes' bioheat equation was performed to assess the wavelength dependence of effects of LLLT in a single layer and in multilayered tissue that consists of skin, fat and muscle. The three different wavelengths selected, 660 nm, 830 nm and 980 nm, were ones that are frequently used in clinic settings for the therapy of musculoskeletal disorders. Laser parameters were set to the power density of 35.7 W/$cm^2$, a spot diameter of 0.06 cm, and a laser exposure time of 50 seconds for all wavelengths. Results: Temperature changes in tissue based on a heat transfer equation using a finite element method were simulated and were dominantly dependent upon the absorption coefficient of each tissue layer. In the analysis of a single tissue layer, heat generation by fixed laser exposure at each wavelength had a similar pattern for increasing temperature in both skin and fat (980 nm > 660 nm > 830 nm), but in the muscle layer 660nm generated the most heat (660 nm ${\gg}$ 980 nm > 830 nm). The heat generation in multilayered tissue versus penetration depth was shown that the temperature of 660 nm wavelength was higher than those of 830 nm and 980 nm Conclusion: Numerical analysis of heat transfer versus penetration depth using a finite element method showed that the greatest amount of heat generation is seen in multilayered tissue at = 660 nm. Numerical analysis of heat transfer may help lend insight into thermal events occurring inside tissue layers during low level laser therapy.