• Structural Engineering and Mechanics
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• v.53 no.4
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• pp.791-818
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• 2015

RC buildings constitute the prevailing type of construction in earthquake-prone region like Kathmandu Valley. Most of these building constructions were based on conventional methods. In this context, the present paper studied the seismic behaviour of existing RC buildings in Kathmandu Valley. For this, four representative building structures with different design and construction, namely a building: (a) representing the non-engineered construction (RC1 and RC2) and (b) engineered construction (RC3 and RC4) has been selected for analysis. The dynamic properties of the case study building models are analyzed and the corresponding interaction with seismic action is studied by means of non-linear analyses. The structural response measures such as capacity curve, inter-storey drift and the effect of geometric non-linearities are evaluated for the two orthogonal directions. The effect of plan and vertical irregularity on the performance of the structures was studied by comparing the results of two engineered buildings. This was achieved through non-linear dynamic analysis with a synthetic earthquake subjected to X, Y and $45^{\circ}$ loading directions. The nature of the capacity curve represents the strong impact of the P-delta effect, leading to a reduction of the global lateral stiffness and reducing the strength of the structure. The non-engineered structures experience inter-storey drift demands higher than the engineered building models. Moreover, these buildings have very low lateral resistant, lesser the stiffness and limited ductility. Finally, a seismic safety assessment is performed based on the proposed drift limits. Result indicates that most of the existing buildings in Nepal exhibit inadequate seismic performance.

• Journal of the Korean Institute of Landscape Architecture
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• v.34 no.4 s.117
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• pp.18-36
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• 2006

The purpose of this research was to establish a green-networks from the perfective of landscape ecology in order to improve the function of urban green spaces. The study site was Dalsu-Gu in Daegu City. This research consisted of three phases. In the first phase, field surveys were carried out in order to understand existing distribution pattern of green spaces in the study site. 533 green spaces surveyed in the first phase were classified into 7 patterns and 24 types. The total area of the green spaces in Dalsu-gu was 3,329ha. Specifically the area of the 'urban nature parks' type was 57.49% of the total area of green spaces in Dalsu-gu, and it was expected that 'urban nature parks' type can play important roles in the green-networks in Dalsu-gu. Two analysis with green spaces in 9 types including 'urban nature parks', 'rivers' and 'neighborhood parks' were performed to establish a basic network frame of the green-networks. In the second phase, 'mutual connectivity analysis' and 'mutual matrix analysis' were performed to select core green spaces of a green-networks using 'areas of each green space and a distance between each space' and 'a rate of green spaces and a rate of water permeable pavement'. The results of the second phase indicated that, in mutual connectivity analysis, large green spaces apart from each other were evaluated as having higher mutual connectivity than small green spaces near to each other. In mutual matrix analysis, the green spaces with higher mutual connectivity and the small green spaces near to each other were evaluated as having better mutual matrix. In the last phase, we structured a basic frame of the green-networks in Dalsu-Gu. The results suggested that the basic frame of the green-networks in Dalsu-Gu was composed on four green-network axes and its shape mirrored a cruciform(+) of northwest${\longleftrightarrow}$southeast directions and southwest${\longleftrightarrow}$northeast directions, The Duryu neighborhood park is at the central point of this green-networks.

• Journal of The Korean Astronomical Society
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• v.46 no.5
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• pp.183-190
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• 2013

Recurring jets, which are jets ejected from the same site, are a peculiar type among various solar jet phenomena. We report such recurring jets ejecting from the same site above an active region on January 22, 2012 with high-resolution multi-wavelength observations from Solar Dynamics Observatory(SDO). We found that the recurring jets had velocities, lengths and lifetimes, but had similar directions. The visible brightening appeared at the jet base before each jet erupted. All the plasma produced by the recurring jets could not overcome the large coronal loops. It seemed that the plasma ejecting from the jet base was confined and guided by preexisting coronal loops, but their directions were not along the paths of the loops. Two of the jets formed crossing structures with the same preexisting filament. We also examined the photospheric magnetic field at the jet base, and observed a visible flux emergence, convergence and cancellation. The four recurring jets all were associated with the impulsive cancellation between two opposite polarities occurring at the jet base during each eruption. In addition, we suggest that the fluxes, flowing out of the active region, might supply the energy for the recurring jets by examining the SDO/Helioseismic and Magnetic Imager (HMI) successive images. The observational results support the magnetic reconnection model of jets.

• Economic and Environmental Geology
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• v.26 no.3
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• pp.395-401
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• 1993

Lower Ordovician rock samples were collected from 23 sites located at the Okcheon non-metamorphic zone, near Taeback and Yeongweol areas, southern part of the Korean Peninsula. A characteristic magnetic component was obtained from four sites. This stable direction ($Dm=-19.4^{\circ}$, $Im=24.1^{\circ}$) which is carried by hematite of very high temperature $679^{\circ}C$), successfully pass both of reversal test and paleopole reliability test, and is regarded as a primary direction. The remagnetized components can be divided into three on the basis of their characteristic directions and magnetic minerals. The first which is carried by hematite, magnetite and pyrrhotite, is widely found at the whole sites. It shows syn- or post-tectonic remagnetization according to strongly negative fold test and distribution between Mesozoic and present field directions. The second, in situ, is distinguishable from the present field direction. After bedding correction, it is identical to Late Triassic to Early Jurassic direction. Its magnetic carrier is considered to be a single component hematite, which may be acquired by pre-tectonic CRM in the Okcheon orogenic zone. The third, which is carried by magnetite and hematite, is characterized by stable reversed direction. These minerals may be acquired by the thermal or chemical process in unknown period. Paleopole position is $169.2^{\circ}E$ in longitude and $59.9^{\circ}S$ in latitude, which indicates that the study area was located at $12.6^{\circ}S$ in paleo-latitude and belonged to northern end of the Gondwana in Early Ordovician.

• Journal of Microbiology and Biotechnology
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• v.30 no.8
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• pp.1227-1234
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• 2020

In this study, yeast cell immobilization was carried out in a packed bed reactor (PBR) to investigate the effects of the volumetric capacity of carriers as well as the different fermentation modes on fuel ethanol production. An optimal volumetric capacity of 10 g/l was found to obtain a high cell concentration. The productivity of immobilized cell fermentation was 16% higher than that of suspended-cell fermentation in batch and it reached a higher value of 4.28 g/l/h in repeated batches. Additionally, using this method, the ethanol yield (95.88%) was found to be higher than that of other tested methods due to low concentrations of residual sugars and free cells. Continuous ethanol production using four bioreactors showed a higher productivity (9.57 g/l/h) and yield (96.96%) with an ethanol concentration of 104.65 g/l obtained from 219.42 g/l of initial total sugar at a dilution rate of 0.092 h^-1. Furthermore, we reversed the substrate-feed flow directions in the in-series bioreactors to keep the cells at their highest activity and to extend the length of continuous fermentation. Our study demonstrates an effective method of ethanol production with a new immobilized approach, and that by switching the flow directions, traditional continuous fermentation can be greatly improved, which could have practical and broad implications in industrial applications.

• Journal of Broadcast Engineering
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• v.14 no.3
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• pp.342-356
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• 2009

This paper presents a vote decision-based deinterlacing scheme for false directional error correction(VDD) to convert interlaced signal into non-interlaced signal using only one fields. The VDD using the vote decision goes through four steps process. The first step extracts regions having doubt of false edge using MM-ELA method. In these regions, the edge direction is decided by the majority vote using upper adjacent pixels's information through the second step. But, we still have undecided directions, which will be decided by the majority vote and the directional average decision at the third step. This step preserves the edge directions and minimizes visual degradation. Finally, the last step interpolates undecided pixels using DOI method which can consider the fine edge direction. Although the VDD with hierarchical structure has a high complexity, it can extract delicate edge compared to other pixel-by-pixel or window-by-window deinterlacing algorithms. Simulation results show that it has significantly improved both the subjective and objective qualities of the reconstructed images.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.3
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• pp.211-223
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• 2000

The atmospheric dispersion of a pollutant emitted from a hypothetical source located in the middle of the Yochon Industrial Estate was simulated by using the Regional Atmospheric Modeling System (RAMS). Four horizontally nested grids were employed: the coarsest one covered the southern part of the Korean Peninsula including Mt. Chiri and the finest one covered the Yochon Industrial Estate and the surrounding area. Wind fields were initially assumed horizontally homogeneous with a wind speed of 4m/s, the average for the Yosu area, and were developed without both external forces and diurnal changes in order to investigate the terrain-induced phenomena. Wind directions that could emphasize the terrain effects on the pollutant transport and that could carry pollutants to a highly-popluated area were selected for the dispersion study. A pollutant was released for 24hours from a grid-base volume source after a 24-h blank run for developing the wind field. The dispersion study showed that the pollutant from the present source location did not directly affect the Yosu City, but showed high concentrations at locations behind the hills 5 to 6 km away from the source according to wind directions. When the wind speed was low, close to calm condition, the pollutant was detected at upstream locations 6 to 7 km from the source. In comparison with the results from the RAMS simulation, the Industrial Source Complex Short-Term Model(ISCST3) predicted a narrow dispersion that was sensitive to the wind direction. When the wind velocity was affected by the local environment, the ISCST3 calculation using that data also gave a lop-sided result, which was different from the distribution of the pollutant reproduced by RAMS.

• Smart Structures and Systems
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• v.17 no.3
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• pp.471-489
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• 2016

Modal identification based on ambient vibration data has attracted extensive attention in the past few decades. Since the excitation for ambient vibration tests is mainly from the environmental effects such as wind and traffic loading and no artificial excitation is applied, the signal to noise (s/n) ratio of the data acquired plays an important role in mode identifiability. Under ambient vibration conditions, certain modes may not be identifiable due to a low s/n ratio. This paper presents a study on the mode identifiability of an instrumented cable-stayed bridge with the use of acceleration response data measured by a long-term structural health monitoring system. A recently developed fast Bayesian FFT method is utilized to perform output-only modal identification. In addition to identifying the most probable values (MPVs) of modal parameters, the associated posterior uncertainties can be obtained by this method. Likewise, the power spectral density of modal force can be identified, and thus it is possible to obtain the modal s/n ratio. This provides an efficient way to investigate the mode identifiability. Three groups of data are utilized in this study: the first one is 10 data sets including six collected under normal wind conditions and four collected during typhoons; the second one is three data sets with wind speeds of about 7.5 m/s; and the third one is some blind data. The first two groups of data are used to perform ambient modal identification and help to estimate a critical value of the s/n ratio above which the deficient mode is identifiable, while the third group of data is used to perform verification. A couple of fundamental modes are identified, including the ones in the vertical and transverse directions respectively and coupled in both directions. The uncertainty and s/n ratio of the deficient mode are investigated and discussed. A critical value of the modal s/n ratio is suggested to evaluate the mode identifiability of the deficient mode. The work presented in this paper could provide a base for the vibration-based condition assessment in future.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.10
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• pp.1281-1289
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• 2011

This paper deals with several statistical distribution functions for the analysis of fatigue life data of composite laminates for small wind-turbine blades. A series of tensile tests was performed on triaxial glass/epoxy laminates for loading directions of $0^{\circ}$, $45^{\circ}$, and $90^{\circ}$. Then, fatigue tests were carried out to determine the fatigue life at the aforementioned loading directions and the fatigue stresses at four levels. Two-parameter Weibull, three-parameter Weibull, normal, and log-normal distributions were used to fit the fatigue life data of the triaxial composite laminates. The three-parameter Weibull distribution most accurately described the fatigue life data measured experimentally for all the cases considered. Furthermore, the variation of fatigue life was simultaneously affected by the loading direction and fatigue stress level.

• Journal of KIISE:Software and Applications
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• v.35 no.1
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• pp.41-49
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• 2008

Fingerprint classification is useful to reduce the matching time of a huge fingerprint identification system by categorizing fingerprints into predefined classes according to their global features. Although global features are distributed diversly because of the uniqueness of a fingerprint, previous fingerprint classification methods extract global features non-adaptively from the fixed region for every fingerprint. We propose an novel method that extracts features adaptively for each fingerprint in order to classify various fingerprints effectively. It extracts ridge directional values as feature vectors from the region after searching the feature region by calculating variations of ridge directions, and classifies them using support vector machines. Experimental results with NIST4 database show that we have achieved a classification accuracy of 90.3% for the five-class problem and 93.7% for the four-class problem, and proved the validity of the proposed adaptive method by comparison with non-adaptively extracted feature vectors.