• Journal of the Korea Concrete Institute
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• v.23 no.2
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• pp.177-184
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• 2011

This paper describes an analytical study on the design approach of PC system with continuous connections at member ends. In multi-ribbed moment resisting slab (MRS) system, double tee members are connected continuously over inverted tee beams with the continuous reinforcements placed within topping concrete. Thus, negative moments are concentrated within the narrow connection area. In order to propose a design method, experimental results of the companion study were examined using detailed nonlinear analysis. Then nonlinear static analysis was used to evaluate the partial continuity effect and the moment redistribution mechanism. Material and cross sectional properties were obtained from experimental results of the companion study. Plastic hinge properties for nonlinear static analysis were modeled with cracking moment, nominal moment, corresponding member deformations, etc. The analysis results showed that a large amount of negative moment of MRS slab can be reduced by applying partial continuity and moment redistribution in MRS joint.

• Atmosphere
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• v.27 no.2
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• pp.163-175
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• 2017

The global terrestrial ecosystems have shown a large spatial variability in recent decades and represented a carbon sink pattern at mid-to-high latitude in Northern Hemisphere. However, there are many uncertainties in magnitude and spatial distribution of terrestrial carbon fluxes due to the effect of climate factors. So, it needs to accurately understand the spatio-temporal variations on carbon exchange flux with climate. This study focused on the effects of climate factors, .i.e. temperature, precipitation, and solar radiation, to terrestrial biosphere carbon flux. We used the terrestrial carbon flux that is simulated by a CarbonTracker, which performs data assimilation of global atmospheric $CO_2$ mole fraction measurements. We demonstrated significant interactions between Net Ecosystem Production (NEP) and climate factors by using the partial correlation analysis. NEP showed positive correlation with temperature at mid-to-high latitude in Northern Hemisphere but showed negative correlation pattern at $0-30^{\circ}N$. Also, NEP represented mostly negative correlation with precipitation at $60^{\circ}S-30^{\circ}N$. Solar radiation affected NEP positively at all latitudes and percentage of positive correlation at tropical regions was relatively lower than other latitudes. Spring and summer warming had potentially positive effect on NEP in Northern Hemisphere. On the other hand as increasing the temperature in autumn, NEP was largely reduced in most northern terrestrial ecosystems. The NEP variability that depends on climate factors also differently represented with the type of vegetation. Especially in crop regions, land carbon sinks had positive correlation with temperature but showed negative correlation with precipitation.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.8
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• pp.873-878
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• 2012

Putting a conductive rod between rotating axial electrodynamic wheels composed of repetitive permanent magnets, three-axial magnetic forces generate on the conductive rod. It is possible to levitate and transfer the rod on space with the forces. However, the forces vary in direction and magnitude for a position of the rod between the electrodynamic wheels. Thus, the position influences the stability of the rod also. To guarantee the stability of a levitated object, the force acting on the object should have negative stiffness like a spring. So, we analyze the stable operating range of the conductive rod levitated by the axial wheels with the commercial finite element tool in this paper. Specially, as the pole number and the radial width of permanent magnets has much influence on the generated force and thereby the stable region, their sensitivities are analyzed also. The analytic result is compared with experimental result.

• English Language & Literature Teaching
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• v.16 no.1
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• pp.171-188
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• 2009

The purpose of this study was to investigate the role of ongoing feedback from the professor in students' processes of learning and developing writing skills. Specifically, the researcher was concerned with how ongoing feedback affected students' attitudes towards writing because in EFL contexts, motivating students to write is a first step to engage them in a challenging journey of academic writing. 20 freshmen taking a writing course, "Paragraph & Essay Writing", at A university participated in this study and they were asked to complete the questionnaire at the end of the spring semester 2009. The results revealed that receiving ongoing feedback from the professor had a positive influence on affective domain, was helpful to develop learning strategies, and was valuable in learning outcomes. However, they also expressed negative opinions: feeling a burden, focusing on forms, and feeling confused. To reflect their opinions, the following four suggestions were made to create a more effective learning environment: promoting learner autonomy, facilitating individual writing conferences, giving balanced feedback in between form and content, and using judicious feedback through careful streaming.

• The Korean Journal of Ecology
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• v.19 no.1
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• pp.9-19
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• 1996

The model PINUSCO2 hased of physiology was creted to simulate carbon dioxide budget in a population of red pine(pinus densiflora) which is one of the dominant species in Korea. Driving forces of PINUSCO2 are global radiation, maximum and minimum air temperatures. State variables fo the model are standing crops of leaf, branch, trunk and root of the red pine population. PINUSCO2 calculates net photosynthesis of canopy and respiration of each organ with 1 hour time step. PINUSCO2 estimated the annual gross productivity, respiration and net productivity of the red pine population as 43.99, 24.55, and 19.44 ton CO2·ha-1·yr-1, respectively, at the study sity(35°58′00"N, 128°25′35"E). PINUSCO2 showed that the red pine population grew mainly in spring and fall, and that in summer daily net population productivity frequently became negative.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2000.11b
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• pp.155-158
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• 2000

This study was conducted to survey the requirements of parents residing in Kyeongsan City for the children's houses attached to universities. To collect information useful for establishing the children's houses having a close connection with community, this study was carrled out using questionnaires with 367 residents in Kyeongsan City. The result of this study showed that while Kyeongsan is a city for academic research its children-care was evaluated as the lowest, compared to other children-caring forms. In addition, the requirements of parents for the children's houses attached to universities accounted for 60.5％ which was higher than their negative responses.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.959-961
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• 2003

Cirrus clouds observation was conducted using a lidar system in order to measure their height, thickness and optical depth at Kwangju (35$^{\circ}$10'N, 126$^{\circ}$53'), Korea in winter, December 2002, and spring March and April 2003. Cirrus clouds at high altitude can be distinguished from atmospheric aerosols location by high depolarization ratio and high altitude. Cirrus clouds were observed at 5${\sim}$12km altitudes with a high depolarization ratio from 0.2 to 0.5. Optical depth of cirrus clouds had varied from 0.28 to 1.81. Radiative effect of observed cirrus cloud on climate system was estimated to be negative net flux from ?0.24 to ?31.04 W/m$^{2}$.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 1996.11a
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• pp.21-28
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• 1996

The Purpose of this study was to identify the effects of the elderly Koreans of residential relocation and to find their conditioning variables that mediate some of the negative effects of residential relocation. The research was performed by questionnares. Subject samples consisted of 448 elderly individuals who have lived for two years or less in one of the two new residential communities in commuting proximity with Seoul: Ilsan or Bundang. Two variables measured for the life of the elderly to residential relocation were the change of the social relationship network and the change of the depression level. Results indicated that the relocation had a substantial disrupting effect on the social network of the elderly. The level of depression of the subjects after relocation was decresed. It was also found that the effects of the elderly to residential relocation was mainly affected by physical factors of environment and residential satisfaction.

• Steel and Composite Structures
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• v.34 no.5
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• pp.733-742
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• 2020

Vibration analysis in nanocomposite plate with smart layer is studied in this article. The plate is reinforced by carbon nanotubes where the Mori-Tanaka law is utilized for obtaining the effective characteristic of structure assuming agglomeration effects. The nanocomposite plate is located in elastic medium which is simulated by spring element. The motion equations are derived based on first order shear deformation theory and Hamilton's principle. Utilizing Navier method, the frequency of the structure is calculated and the effects of applied voltage, volume percent and agglomeration of Carbon nanotubes, elastic medium and geometrical parameters of structure are shown on the frequency of system. Results indicate that with applying negative voltage, the frequency of structure is increased. In addition, the agglomeration of carbon nanotubes reduces the frequency of the nanocomposite plate.

• Steel and Composite Structures
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• v.1 no.3
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• pp.341-354
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• 2001

This paper provides a state-of-the-art review on advanced analysis models for investigating the load-displacement and ultimate load behaviour of steel and composite frames subjected to static gravity and lateral loads. Various inelastic analysis models for steel and composite members are reviewed. Composite beams under positive and negative moments are analysed using a moment-curvature relationship which captures the effects of concrete cracking and steel yielding along the members length. Beam-to-column connections are modeled using rotational spring. Building core walls are modeled using thin-walled element. Finally, the nonlinear behaviour of a complete multi-storey building frame consisting of a centre core-wall and the perimeter frames for lateral-load resistance is investigated. The performance of the total building system is evaluated in term of its serviceability and ultimate limit states.