• Journal of Korean Society of Steel Construction
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• v.16 no.1 s.68
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• pp.73-79
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• 2004

Tuned Mass Damper (TMD) was applied to control the vibration of an offshore structure due to ocean waves. The errors caused by the linearization of the fluid-structure interaction effect and the phenomena when using the linearized equation of motion in TMD design were analyzed. To determine the performance of TMD in controlling vibration, both regular waves with varying periods and irregular waves with different significant wave heights were used. When the offshore structure received regular waves with a period similar to the first natural period of structure. TMD performed well in terms of response reduction. Such was not the case for the other periods. however, In the case of irregular waves, TMD triggered the reduction of structural response for waves with relatively small significant wave height. For irregular waves with relatively big significant wave height, however, TMD did not show any control effect. Therefore, TMD is useful in reducing offshore structural vibration due to ambient waves, thereby helping secure fatigue life.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.4
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• pp.274-279
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• 2015

Wave data acquired over eleven years near Sokcho Harbor located in the central area of the east coast were analyzed using spectral method and wave-by-wave analysis method and its major wave characteristics were examined. Significant wave heights were found to be high in winter and low in summer, and peak periods were also found to be long in winter and short in summer. The maximum significant wave height observed was 8.95 m caused by the East Sea twister. The distributional pattern of the significant wave heights and peak periods were both fitted better by Kernel distribution function than by Generalized Gamma distribution function and Generalized Extreme Value distribution function. The wave data were compiled to subdivide the wave height into intervals for each month, and the cumulative occurrence rates of wave heights were calculated to be utilized for the design and construction works in nearby construction works.

• Journal of the Korean Institute of Landscape Architecture
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• v.32 no.6 s.107
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• pp.52-67
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• 2005

The purposes of this study were to classify the changing periods of apartment outdoor space in Korea and to clearly understand the specific characteristics of each period. The study has been done through on-site observation of apartment complexes, and through the analysis of housing estate planning techniques, rules and regulations affecting outdoor spaces during the rapidly developing era. The results of this study shows that three major periods with distinct characteristics were found, which were as follows: 1) The first well defined period spans from 1960 to 1990. In this period, apartment construction was rapid, and as a result, quality of housing environments were sacrificed. As little attention was given to the landscapes in apartment complex, they were constructed very simple and identical in outdoor space of apartment complex. This period can be referred to as the 'commonly universal period in apartment outdoor space'. 2) The second period spans from 1991 to 1996, during which time a housing construction project for two million residences was completed in order to significantly stimulate the provision of houses to the general public. As a result, regulations were relaxed causing housing environments to deteriorate. Although apartments were constructed very close together, there was some diversification and experimentation in outdoor styles. This period can be referred to as the 'congestion period of apartment outdoor space'. 3) The third period spans from 1997 to the present. During this time the number of unsold apartments has grown considerably throughout the country. Many different apartment complex marketing strategies have been employed to reduced the glut of unsold apartments. This experimental trend has continued and been well-received since the IMF period. The distinguishing characteristics of this period are the introduction of a rich natural landscape, the increase in communications among residents, the human oriented design, and the refined and elegant design for the outdoor street furnitures. As a result, this period can be named the "differentiation period of apartment outdoor space".

• Journal of Ecology and Environment
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• v.39 no.1
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• pp.99-110
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• 2016

The objective of this study was to analyze chemical water quality, ecological characteristics of fish compositions, and ecosystem health before- (B_wc; 2008-2009) and after-the weir construction (A_wc; 2011-2012) at Juksan Weir and Seungchon Weir of Yeongsan River watershed. Suspended solids (SS) and chlorophyll-a (Chl-a) in Juksan Weir increased, whereas nutrients such as total nitrogen (TN) and total phosphorus (TP) decreased in the epilimnetic water. In Juksan and Seungchon weirs, fish species distribution analysis in the periods of B_wc and A_wc showed that sensitive species were rare and tolerant species were dominant in the community. In the analysis of trophic guild, relative abundance of carnivore species are increased to 22% and 12%, respectively, after the constructions of Seungchon Weir and Juksan Weir. Mann-Whitney U-tests of nonparametric statistical analysis indicated that omnivore and carnivore species had significant differences (p < 0.05) between the B_wc and A_wc. The massive population growth of an exotic species, Micropterus salmoides, was evident in Seungchon Weir to influence on the structures of fish communities. The model values of mean Index of Biological Integrity (IBI), based on fish assemblages, were < 15, which indicates "poor" condition in the river health, and the significant difference of IBI values was not found between the B_wc and A_wc.

• Journal of Bio-Environment Control
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• v.31 no.3
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• pp.237-245
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• 2022

Peach is a typical summer fruit which can be used for various food, processed food, and fragrance ingredients in Korea. Peach is also known as one of serious allergens which make difficulty for farm workers during peach sorting operations. After peach harvesting, it moves to the sorting operations for removing cover material, removing fuzz on peach surface, sorting by size, and packing. The air-samplers and optical particle counters were used to analyze the characteristics of fine dust generation by location and operation characteristics in the experimental peach farms. During removing peach fuzz, the dust concentrations were increased by 6.89 times on total suspended particulate (TSP), 2.13 times on PM-10 (particulate matter), and 1.30 times on PM-2.5 compared to non-working periods, respectively. During removing peach covering materials, the dust concentrations were increased by 3.14 times on TSP, 1.91 times on PM-10, and 1.43 times on PM-2.5 compared to non-working periods, respectively. This represents peach fuzz can be affected to farm workers during peach sorting operations.

• Journal of the Korean Wood Science and Technology
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• v.52 no.4
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• pp.375-382
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• 2024

The study focuses on evaluating the bending creep performance of laminated veneer lumber (LVL) formwork in timber concrete composite (TCC) structures. Timber-framed construction is highlighted for its environmental benefits and seismic resistance, but limitations such as poor tensile strength and brittle failure in bending hinder its use in high-rise buildings. Wood-concrete hybrid structures, particularly those using reinforced concrete slabs with TCC floors, emerge as a potential solution. The research aims to understand the time-dependent behavior of TCC components, considering factors like wood and concrete shrinkage and connection creep. The experiment was conducted in western Japan on the TCC floor designed for use in the Kama-city Inatsuki-higashi compulsory education school. The LVL formwork, measuring 9,000 mm by 900 mm, and concrete is loaded onto it for testing. The creep test periods are examined using concrete loading. It employs a comprehensive creep analysis, adhering to Japanese standards, involving deflection measurements and regression analysis to estimate the creep coefficient. Results indicate substantial deformation after shoring removal, suggesting potential reinforcement needs. The study recommends extending test periods for improved accuracy and recognizing regional climate impacts. Overall, the research provides valuable insights into the potential of LVL formwork in TCC structures, emphasizing safety considerations and paving the way for further experimentation under varied conditions to validate structural integrity.

• Korean Institute of Interior Design Journal
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• v.20 no.2
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• pp.3-9
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• 2011

In this study, the change of critical elements of the design evaluation was investigated during two decades at the architectural competition which was held nationwide in Germany. Specifically, the periods of investigation span both from July 1989 to June 1990 and from July 2009 to June 2010. The results of the analysis show that the cost of construction, the maintenance cost, the design of facade and the energy conservation are being magnified for the new important elements. The images of buildings and the economic aspects are meant to be high. The frequency of the critical elements for interior spaces is approximately two times more important than those for the forms and outdoor spaces. Overall, many juries of the architectural competition in Germany were interested in the elements for interior spaces. The field of function accounts for roughly the half of four basic architectural fields such as function, others, aesthetic and construction fields. The critical elements are required persistently such as context, Circulation, organization of space, form, landscape and outdoor space design, arrangement of building, cost of construction, function, design of facade, location of main entrance. These items are regarded as the most important elements of the design evaluation at the competition. Knowing the change of critical elements of the design evaluation, we can understand the trend of architecture in Germany. The results of this study can be applied in Korea to develop the critical elements of design.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.141-145
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• 2008

In this paper, non working day for the construction project in Cheongju region considering weather condition for 30 years from 1971 to 2000 and 10 years from 1991 to 2000 as statistical periods was estimated. In Cheongju region, there was no remarkable difference between them because non working day for outside and half outside work was 157days and for interior work 144days at statistics for 30 years., and utside and half outside work was 159days and for interior work 142days at statistics for 10 years.. However, non working day due to high temperature is slightly increased, and non working day due to cold weather is slightly decreased in the case that the recent statistical data was used caused by global warming. Non working day due to rainfall was 23 days at statistics for 30 years, and it was 28 days at statistics for 10 years.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.620-625
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• 2005

It was monitored 3 years from 2003 to 2005 that the variational quality of water according to the arrangement toward natural shape of stream, and the variational characteristics of the each contents on water quality were analyzed after the separation into three periods of before, among and after arrangement construction. The quality monitoring results showed that the averages of water temperature, pH, DO, SS, BOD, T-N and T-P were $17.1{\sim}21.4^{\circ}C$, $6.44{\sim}7.74$, $7.02{\sim}8.36mg/L,\;0.7{\sim}51.9mg/L,\;0.310{\sim}1.044mg/L,\;0.41{\sim}2.43mg/L$ and $0.003{\sim}0.008mg/L$, respectively. The measured values of BOD, T-N and T-P were high just after construction, but the amounts were lowered as time passed, and finally stabilized in 2005. It ranged from 0.337 to 0.912 that the coefficients of correlation on linear regression between the discharges of water and BOD, T-N and T-P at each monitoring points, respectively.

• Journal of Korean Society on Water Environment
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• v.24 no.1
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• pp.107-117
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• 2008

Infiltration facilities are effective instruments to mitigate flood and can increase base runoff in urban watersheds. In order to analyze effects of infiltration trenches physical model experiments were conducted. The physical model facility consists of two soil tanks, artificial rainfall generators, tensiometers, and piezometers. The experiment was conducted by nine times and each case differed in rainfall intensity, rainfall duration and the type of ground surface. Measured quantities in the experiments are as follows: surface runoff, subsurface runoff, trench pipe runoff, groundwater level, water content, etc. The following resulted from the model experiment: The volume of subsurface runoff at trench watershed was maximum 78.3% compared with rainfall. This value is bigger than that of ordinary rate of subsurface runoff, and shows a groundwater recharge effect of trench. The time of runoff passing through the trench became earlier and the volume of runoff became larger with the increase of inflow into the trench, while trench exfiltration into ground became relatively smaller. The results of this study presented above show that infiltration trenches are effective instruments to increase base runoff during dry periods.