• Steel and Composite Structures
• /
• v.22 no.2
• /
• pp.449-472
• /
• 2016

This paper studies the seismic behavior of reinforced concrete (RC) walls with encased cold-formed and thin-walled (CFTW) steel truss, which can be used as an alternative to the conventional RC walls or steel reinforced concrete (SRC) composite walls for high-rise buildings in high seismic regions. Seven one-fourth scaled RC wall specimens with encased CFTW steel truss were designed, manufactured and tested to failure under reversed cyclic lateral load and constant axial load. The test parameters were the axial load ratio, configuration and volumetric steel ratio of encased web brace. The behaviors of the test specimens, including damage formation, failure mode, hysteretic curves, stiffness degradation, ductility and energy dissipation, were examined. Test results indicate that the encased web braces can effectively improve the ductility and energy dissipation capacity of RC walls. The steel angles are more suitable to be used as the web brace than the latticed batten plates in enhancing the ductility and energy dissipation. Higher axial load ratio is beneficial to lateral load capacity, but can result in reduced ductility and energy dissipation capacity. A volumetric ratio about 0.25% of encased web brace is believed cost-effective in ensuring satisfactory seismic performance of RC walls. The axial load ratio should not exceed the maximum level, about 0.20 for the nominal value or about 0.50 for the design value. Numerical analyses were performed to predict the backbone curves of the specimens and calculation formula from the Chinese Code for Design of Composite Structures was used to predict the maximum lateral load capacity. The comparison shows good agreement between the test and predicted results.

• Asian Journal of Atmospheric Environment
• /
• v.8 no.1
• /
• pp.25-34
• /
• 2014

In winter 2013, extreme air pollution by fine particulate matter ($PM_{2.5}$) in China attracted much public attention. In order to simulate the $PM_{2.5}$ pollution, the Community Multiscale Air Quality model driven by the Weather Research and Forecasting model was applied to East Asia in a period from 1 January 2013 to 5 February 2013. The model generally reproduced $PM_{2.5}$ concentration in China with emission data in the year 2006. Therefore, the extreme $PM_{2.5}$ pollution seems to be mainly attributed to meteorological (weak wind and stable) conditions rather than emission increases in the past several years. The model well simulated temporal and spatial variations in $PM_{2.5}$ concentrations in Japan as well as China, indicating that the model well captured characteristics of the $PM_{2.5}$ pollutions in both areas on the windward and leeward sides in East Asia in the study period. In addition, contribution rates of four anthropogenic emission sectors (power generation, industrial, residential and transportation) in China to $PM_{2.5}$ concentration were estimated by conducting zero-out emission sensitivity runs. Among the four sectors, the residential sector had the highest contribution to $PM_{2.5}$ concentration. Therefore, the extreme $PM_{2.5}$ pollution may be also attributed to large emissions from combustion for heating in cold regions in China.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2008.05a
• /
• pp.294-298
• /
• 2008

Snow cover is a potential water resource for later spring and summer seasons as well as a thermal mirror with high reflectivity causing decreases of surface air temperature during cold winter seasons. In this study, current and future changes in Northern Hemisphere snow extent and their potential linkages with atmospheric circulation are examined. The NOAA AVHRR visible snow extent (1967-2006) data as well as observational (NCEP-DOE 1979-2006) and modeled (GFDL 2.1 2081-2100) pressure and surface air temperature data are used. Analyses of observational data demonstrate that the snow extent in meteorological spring (March to April) and summer (June to August) has significantly decreased since the late 1980s. The offset of snow seasons (the timing of snow melt in spring) have also significantly advanced particularly in Europe, East Asia, and northwestern North America. Analyses of pressure fields reveal that the spatial patterns of the earlier snow melt are associated with changes in atmospheric circulation such as the Arctic Oscillation (AO). In the positive winter AO years, multiple positive pressure departure cores in the upper troposphere (200hPa) are observed over the mid-latitude regions from March to mid-April, while a negative pressure departure core (70hPa) prevails over the Arctic Ocean. The reversed anomaly patterns related to later snow melt occur in negative winter AO years. The comparison between current and future thermal spring onsets suggest that snow melt patterns will intensify with larger greenhouse gas emissions, indicating earlier hydrological spring onset.

• Journal of the Korean Geotechnical Society
• /
• v.28 no.5
• /
• pp.85-94
• /
• 2012

Recently, growing interests in frozen ground have stimulated us to advance fundamental theories and systematic researches on soil behavior under freezing conditions. Unlike the well-established soil mechanics theory, temperature variation and phase change of pore-water cause water migration to cold side, ground heaving, sharp increase in earth pressure, etc., which bring about serious problems in frozen geotechnical structures. Elasto-plastic mechanical constitutive model for frozen/unfrozen soil subjected to fully coupled THM phenomena is formulated based on a new stress variable that is continuous in frozen-unfrozen transitional regions. Numerical simulations are conducted to discuss numerical reliability and applicability of the developed constitutive model: one-dimensional heaving pressure, tri-axial compression test, and one-side freezing tests. The numerical results show that developed model can efficiently describe complex THM phenomena of frozen soil, and they can be utilized to analyze and design the geotechnical structures under freezing conditions, and predict their long-term behavior.

• The Bulletin of The Korean Astronomical Society
• /
• v.39 no.2
• /
• pp.75.2-75.2
• /
• 2014

CS molecule as an important tracer for studying inward motions in dense cores is known to be adsorbed onto dusts in cold (T~10K) dense cores, resulting in its significant depletion in the central region of the cores which may hamper a proper study of kinematics stage of star formation. In this study we choose five 'evolved' dense starless cores, L1544, L1552, L1689B, L694-2 and L1197, to investigate how depletion of CS molecule is significant and how the molecule differentiates depending on the evolutional status of the dense cores, by using a rare isotopomer C34S. We performed mapping observations in C34S (J=2-1) and N2H+ (J=1-0) with Nobeyama 45 m telescope, and compared $850{\mu}m$ continuum data as a reference of the density distribution of the dense cores. Our data confirm the claim that CS molecule generally depletes out in the central region in dense starless cores, while N2H+ keeps abundant as they get evolved. All of integrated intensity maps show 'semi-ring-like' depletion holes in CS, and all of abundance radial profiles show decrease toward center. The CS depletion and molecular chemical differentiation seems to depend on the evolutional status in dense cores. The evolved cores shows low abundance at both central and outer regions, implying that in the case of highly evolved cores CS freeze-out occurs over the most area of the cores.

• Journal of The Korean Digital Architecture Interior Association
• /
• v.11 no.2
• /
• pp.71-81
• /
• 2011

This research explores about the construction process and provision of Japanese Wooden Houses. Even though Prefabricated Houses appeared during the 1960's and the Platform Construction System during the 1970's, there was still a high demand for Conventional Wooden House, with a high demand by households on their 30's. These features were found in the areas of Hokkaido, Kyushu, Tokyo, and Osaka. Tokyo and capital region accommodate large number of the head offices of companies that produce Platform Construction System houses, and thus supply the largest amount of Platform Construction System houses. In capital region, land prices are so high, that they build houses as 3-Floors or above, and also driven by high cost of house construction, house performances are excellent. The houses of Osaka and Kinki region demonstrate similar characteristics to those of capital region. Osaka is headquartered by a group of head offices of companies that produce prefabricated houses, and thus holds more amount of prefabricated house supply than other regions. This city also shows high cost of house construction no less than capital region, and thus offers outstanding performance of house. In Kyushu, whereas Japanese wooden house building systems are supplied the most, Platform Construction System houses are provided the least in the nation. As this region offers rich amount of forest resources owing to mild humid climate which is ideal for vegetations, the Japanese wooden building systems use the timbers from this region. Hokkaido, a cold region, requires houses that offer outstanding performance of heat insulation. Therefore, Hokkaido shows more supplies of Platform Construction System houses that offers outstanding heat insulation performance. They import the timbers that form the structure framework of Platform Construction System houses from North America.

• Journal of Korean Society for Geospatial Information Science
• /
• v.25 no.1
• /
• pp.3-8
• /
• 2017

In this study future wind resource maps have been produced under climate change scenario using ensemble regional climate model weather research and forecasting(WRF) for the period from 2045 to 2054(mid 21st century). Then various spatiotemporal analysis has been conducted in terms of monthly and diurnal. As a result, monthly variation(monsoon circulation) was larger than diurnal variation(land-sea circulation) throughout the South Korea. Strong wind area with high wind power energy was varied on months and regions. During whole years, strong wind with high wind resource was pronounced at cold(warm) months in particular Gangwon mountainous and coastal areas(southwestern coastal area) driven by strong northwesterly(southwesterly). Projected strong and weak wind were presented in January and September, respectively. Diurnal variation were large over inland and mountainous area while coastal area were small. This new monthly and diurnal variation would be useful to high resource area analysis and long-term operation of wind power according to wind variability in future.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.16 no.1
• /
• pp.159-170
• /
• 2013

The effect of climate change on urban woody plants remains difficult to predict in urban areas. Depending on its tolerances, a plant species may stay and survive or stay with slowly declining remnant populations under a changing climate. To predict those vulnerabilities on urban woody plants, this study suggests a basic bioclimatic envelop model of heat requirements, cold tolerance, chilling requirements and moisture requirements that are well documented as the 'climatic niche'. Each component of the 'climatic niche' is measured by the warmth index, the absolute minimum temperature, the number of chilling weeks and the water balance. Regarding the utility of the developed model, the selected urban plant's present probabilities are suggested in the future climate of Seoul. Both Korea and Japan's thermal thresholds are considered for a plant's optimal climatic niche. By considering the thermal thresholds of these two regions for the same species, the different responses observed will reflect the plant's 'hardening' process in a rising climate. The model illustrated that the subpolar plants Taxus cuspidata and Ulmus davidiana var. japonica are predicted to have low suitability in Seoul. The temperate plants Zelkova serrata and Pinus densiflora, which have a broad climatic niche, exhibited the highest present probability in the future. The subtropical plants Camellia japonica and Castanopsis cuspidata var. sieboldii may exhibit a modest growth pattern in the late 21C's future climatic period when an appropriate frost management scheme is offered. The model can be used to hypothesize how urban ecosystems could change over time. Moreover, the developed model can be used to establish selection guidelines for urban plants with high levels of climatic adaptability.

• Korean Journal of Ichthyology
• /
• v.20 no.2
• /
• pp.90-96
• /
• 2008

The histological morphology on the skin of Misgurnus anguillicaudatus was described in the three regions such as dorsal, lateral, occiput and subsequently morphological variations of the skin were monthly observed for a year. The skin consisted of epidermis having epithelial cell, club cell and mucus cell, and dermis of mainly connective tissue fiber, embedded scale and blood capillary. Unicellular mucus cells situated at the epidermis underwent seasonal change in its size, as well as number and amounts of mucus-secreting materials, which they greatly increased in winter, but did not in summer. As it is getting cold, the mucus cells' shape changed from initial spherical to oval or elongated form. Such considerable changes in the mucus cell were particularly most evident in the occiput during winter. Moreover, the dermis largely thickened about 2~3 times in winter than in summer. Based on these results, we discussed function for the mucus on what it mainly acts in nature and information on whether mucus cells' seasonal variations affect on hibernation and cutaneous respiration.

• Journal of the Economic Geographical Society of Korea
• /
• v.12 no.3
• /
• pp.260-276
• /
• 2009

Niagara Region in Canada is located in the Northeast industrial area of North America which experienced severe de-industrialization since the 1960s. Since the climate there is very cold in winter time, agricultural activities can not be well practiced. However, this area became well-known to the world with the IceWine industry. This paper introduces and analyses how this became possible to find out factors contributing to the success and draw implications to other regions. Based on case studies on wineries, this paper concludes key factors of the success as innovative activities of founding fathers of leading wineries and cooperations among governments, universities, and wineries of the region.