• The Transactions of the Korean Institute of Power Electronics
• /
• v.15 no.2
• /
• pp.96-102
• /
• 2010

Nowadays, climate change becomes serious problem in all around country. Especially because of global warming problem, every country is suffered from various natural disasters. To prevent these changes, every industry are keep requiring the increase in energy efficiency. Recently, in the regulation of CSCI (climate savers computing initiate), the efficiency of server power supply should meet the demand of 94% at 50% load condition by 2010, which is called platinum level. Hence, server power system has been dramatically developed with the various technique for the high efficiency of it. Among those technique, hold up time extension technique has received wide attention and has been researched for a long time. In this paper, technical trend of hold up time extension circuit will be covered for the high efficiency, high power density server power supply.

• Journal of the Korean earth science society
• /
• v.42 no.6
• /
• pp.770-788
• /
• 2021

This study aimed to determine whether middle school students could understand global warming and the greenhouse effect, and explain them in terms of global radiative equilibrium. From July 13 to July 24 in 2021, 118 students in the third grade of middle school, who completed a class module on 'atmosphere and weather', participated in an online assessment consisting of multiple-choice and written answers on radiative equilibrium, the greenhouse effect, and global warming; 97 complete responses were obtained. After analysis, it was found that over half the students (61.9%) correctly described the meaning of radiative equilibrium; however, their explanations frequently contained prior knowledge or specific examples outside of the presented data. The majority of the students (92.8%) knew that the greenhouse effect occurs within Earth's atmosphere, but many (32.0%) thought of the greenhouse effect as a state in which the radiative equilibrium is broken. Less than half the students (47.4%) answered correctly that radiative equilibrium occurs on both Earth and the Moon. Most of the students (69.1%) understood that atmospheric re-radiation is the cause of the greenhouse effect, but few (39.2%) answered correctly that the amount of surface radiation emitted is greater than the amount of solar radiation absorbed by the Earth's surface. In addition, about half the students (49.5%) had a good understanding of the relationship between the increase in greenhouse gases and the absorption of atmospheric gases, and the resulting reradiation to the surface. However, when asked about greenhouse gases increases, their thoughts on surface emissions were very diverse; 14.4% said they increased, 9.3% said there was no change, 7.2% said they decreased, and 18.6% gave no response. Radiation equilibrium, the greenhouse effect, and global warming are a large semantic network connected by the balance and interaction of the Earth system. This can thus serve as a conceptual system for students to understand, apply, and interpret climate change caused by global warming. Therefore, with the current climate change crisis facing mankind, sophisticated program development and classroom experiences should be provided to encourage students to think scientifically and establish scientific concepts based on accurate understanding, with follow-up studies conducted to observe the effects.

• Atmosphere
• /
• v.19 no.3
• /
• pp.227-235
• /
• 2009

Global climate warming induced by long-lived greenhouse gases is expected to cause increases in wildfire frequencies and intensity in boreal forest regions of mid- and high-latitudes in the future. Siberian forest fires are one of important sources for air pollutants such as ozone and aerosols over East Asia. Thus an accurate quantification of forest fire influences on air quality is crucial, in particular considering its higher occurrences expected under the future warming climate conditions. We here use the 3-D global chemical transport model (GEOS-Chem) with the satellite constrained fire emissions to quantify Siberian fire effects on ozone concentrations in East Asia. Our focus is mainly on spring 2003 when the largest fires occurred over Siberia in the past decade. We first evaluated the model by comparing to the EANET observations. The model reproduced observed ozone concentrations in spring 2003 with the high $R^2$ of 0.77 but slightly underestimated by 20%. Enhancements in seasonal mean ozone concentrations were estimated from the difference in simulations with and without Siberian fires and amounted up to 24 ppbv over Siberia. Effects of Siberian fires also resulted in 3-10 ppbv incresases in Korea and Japan. These increases account for about 5-15% of the ozone air quality standard of 60 ppbv in Korea, indicating a significant effect of Siberian fires on ozone concentrations. We found however that possible changes in regional meteorology due to Siberian fires may also affect air quality. Further study on the interaction between regional air quality and meteorology is necessary in the future.

• Journal of Environmental Science International
• /
• v.23 no.6
• /
• pp.1003-1012
• /
• 2014

We examined the combined impacts of future increases of $CO_2$ and temperature on the growth of four marine diatoms (Skeletonema costatum, Chaetoceros debilis, Chaetoceros didymus, Thalassiosira nordenskioeldii). The four strains were incubated under four different conditions: present ($pCO_2$: 400ppm, temperature: $20^{\circ}C$), acidification ($pCO_2$: 1000ppm, temperature: $20^{\circ}C$), global warming ($pCO_2$: 400ppm, temperature: $25^{\circ}C$), and greenhouse ($pCO_2$: 1000ppm, temperature: $25^{\circ}C$) conditions. Under the condition of higher temperatures, growth of S. costatum was suppressed, while C. debilis showed enhanced growth. Both C. didymus and T. nodenskioldii showed similar growth rates under current and elevated temperature. None of the four species appeared affected in their cell growth by elevated $CO_2$ concentrations. Chetoceros spp. showed increase of pH per unit fluorescence under elevated $CO_2$ concentrations, but no difference in pH from that under current conditions was observed for either S. costatum or T. nodenskioeldii, implying that Chetoceros spp. can take up more $CO_2$ per cell than the other two diatoms. Our results of cell growth and pH change per unit fluorescence suggest that both C. debilis and C. didymus are better adapted to future oceanic conditions of rising water temperature and $CO_2$ than are S. costatum and T. nodenskioeldii.

• Journal of the Korea Society for Simulation
• /
• v.21 no.2
• /
• pp.1-9
• /
• 2012

Subterranean termites forage by constructing tunnel networks in soil and encounter food resources during tunnel excavation. Some species of termites can travel up to 150 m underground. They often travel to the surface to find wood cellulose to feed their colony, which in turn causes extensive damage to wooden architecture, such as timber-frame houses. This type of damage has been constantly increasing along with global warming because higher temperatures provide an ecological niche for termites. The damage is closely related to termite territory size and distribution. Recently, as a way to research termite control, the necessity of a mathematical model to simulate termite territory formation in relation to damage has increased. So far, however, few studies have been conducted on the development of a model because it is difficult to quantify or characterize the relationship between territorial behavior and field conditions including complicated environmental factors. In the present study, we suggest a simulation model of the territoriality of the Formosan subterranean termites, Coptotermes formosanus (Shiraki), and Reticulitermes flavipes (Kollar), based on empirical data. The model consists of 2 procedures. One describes tunnel network growth for each colony, and the other represents territoriality based on tunnel-tunnel interactions between different colonies. Using the model, we show changes in territorial competition according to the termination probability of tunnel growth.

• Journal of the Korean Society of Physical Medicine
• /
• v.15 no.4
• /
• pp.11-20
• /
• 2020

PURPOSE: This study examined the effects of Nordic walking on depression and the physical function of elderly patients with a high risk of depression. METHODS: This study was a blinded randomized allocation study; 32 elderly were assigned to a Nordic walking group (n = 17), consisting of 60 min Nordic walking (including warming up 5 min, warming down 5 min, and Nordic walking 50 min) two days per week for 12 weeks and general leisure group (n = 15), consisting of 60 min leisure program community center. The pre and post 12-week program, depression test, muscle strength (including grip test, and 30sec sit to stand), and balance (including Functional Reach test, and One Leg Standing test) were measured. A Mann-Whitney U test was used to compare within the group, and a Wilcoxon signed-rank test was used to compare between the groups. RESULTS: After 12 weeks, only the Nordic walking group showed significant improvement in depression, muscle strength, and balance (p < .05). In the general leisure group, however, the left grip strength and Functional Reach Test (FRT) showed a significant decrease. The Nordic walking program was better than the general leisure group, and a significant difference was observed in depression, muscle strength, and balance between the two groups (p < .05). CONCLUSION: Nordic walking was effective for the elderly with a high risk of depression. Therefore, Nordic walking may be an option for preventing elderly mental disorders and functional improvement.

• Journal of the Korean association of regional geographers
• /
• v.12 no.4
• /
• pp.437-448
• /
• 2006

Bare-topped thufur is called as frost scars, implying the rupturing stage of vegetated mounds, Field observations and measurements provide empirical information on the process and factors of thufur disintegration in Mt. Halla, Initial bare patches on mound apexes are scaled up by continuous removal of soil and vegetation, resulting in the formation of crater-like thufur, Frost action plays a primary role in thufur disintegration, In particular, pipkrake loosens soil particles within the bare patches and subsequently accelerates the degradation of vegetated mounds during periods with frequent diurnal freeze-thaw cycle and high soil moisture, Deflation also has an impact on thufur breakup in that the bare patches usually lack upper dark brown soil and are covered with granules, Withered shrubs such as Juniperus chinensis var. sargentii are frequently observed in frost scars and disrupted mounds, indicating that thufur disintegration has been probably influenced by global warming.

• Journal of Fashion Business
• /
• v.23 no.4
• /
• pp.86-99
• /
• 2019

This research is a study on up cycling design to protect nature in order to postpone global warming to the maximum extent possible as it has been a serious global issue to the fashion industry and even to individual consumers. This research focuses on the ways to use wedding dress, one of the clothes made of synthetic fiber, which is a major cause of global warming. Among clothing from the 19th century, two styles of clothes, Bustle style and Art Nouveau style were analyzed ranging from their underwear styles to outwear styles through collections in books and museums. Two styles of dress using drawers, chemise, and corset as basic underwears were manufactured. All the fabric and subsidiary materials except for parts of underwears were made with discarded wedding dresses. It was developed for rental clothing which women could try on Western costume, from underwears to outwears. First, for bustle dress, woman put on basic underwears, then bustle, and bustle-type petticoat. Dress is a two-piece type, and it was made to put on detachable train on the back of skirt. Second, based on the Art Nouveau style clothes, our-glass style dress consists of petticoat, one-piece over drawers, chemise, and corset. After putting on drawers, both chemise, and corset were the same as Bustle Style. This research is a practical way of realizing sustainable design. The aim of the current work is to provide educational effect on the development of rental clothes which upcycle wedding dress and let women experience other cultures.

• Atmosphere
• /
• v.32 no.3
• /
• pp.207-221
• /
• 2022

In Jeju, on January 23, 2016, a cold surge accompanied by heavy snowfall with the most significant amount of 12 cm was the highest record in 32 years. During this period, the temperature of 850 hPa in January was the lowest in 2016. Notably, in 2016, the average surface temperature of January on the Polar cap was the highest since 1991, and 500 hPa geopotential height also showed the highest value. With this condition, the polar vortex in the northern hemisphere meandered and expanded into the subtropics regionally, covering the Korean Peninsula with very high potential vorticity up to 7 Potential Vorticity Unit. As a result, the strong cold advection, mostly driven by a northerly wind, around the Korean Peninsula occurred at over 2𝜎. Previous studies have not addressed this extreme synoptic condition linked to polar vortex expansion due to the unprecedented Arctic warming. We suggest that the occurrence of a strong Ural blocking event after the abrupt warming of the Barents/Karas seas is a major cause of unusually strong cold advection. With a specified mesoscale model simulation with SST (Sea Surface Temperature), we also show that the warmer SST condition near the Korean Peninsula contributed to the heavy snowfall event on Jeju Island.

• Journal of the Korean Society of Food Culture
• /
• v.25 no.5
• /
• pp.625-632
• /
• 2010

The purpose of this study was to investigate the appropriate water content in high omega-3 fatty acid Saury nuggets for the desirable texture. The approach was made with adding water and onion at various levels (0~20%). The main ingredients of the nuggets included saury mince, mild pizza cheese, and hydrated textured soy protein concentrate. The formulated products were molded (dia. 4.5, thickness 1.5 cm, 20 g), lightly battered, and flash fried for 4 min. at $160^{\circ}C$, and then frozen until tested. The frozen nuggets were cooked at $165^{\circ}C$ and subjected to sensory evaluations, texture analysis, and water content analysis during warming (0~60 min), as well as assessments of acid, peroxide, and TBA values (during 10 days of storage at $24^{\circ}C$). In the sensory evaluation, preference for texture was highest in the nuggets made with a 15% onion level. The hardness of the nuggets increased with increasing onion level. Moisture content was highest in the nuggets made with a 20% water level. Changes in hardness during warming (0~60 min) of Saury nuggets containing various water and onion levels increased in nuggets made with the 20% water level. The acid, peroxide, and TBA values of the Saury nuggets made with herbs and oriental herbal extracts decreased up to 10 days of storage.