• International Journal of High-Rise Buildings
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• v.9 no.4
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• pp.307-314
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• 2020

High-rise buildings with vertical setback are widely used in practice. From the field investigation of the past earthquakes, it was found that such kind of vertically irregular high-rise building structures easily suffer severe damage during strong earthquakes. This paper presents an extensive study on the earthquake responses of moment-resisting frame structures (MFS) popularly applied in high-rise buildings with vertical setback. Four groups of MFS are designed, including three groups of structures with vertical setback and one group of structures with the lateral stiffness varying along the building height but without vertical setback. The numerical models of the structures are established, and the time history analysis of the structures under different levels of earthquakes is conducted. The earthquake responses of the structures are compared. The influence of the ratio between the horizontal setback dimension and the previous plan dimension, the eccentricity of setback, and the position where the setback occurs on the seismic performance of structures is studied. The rationality of the provisions for the structures with vertical setback specified in the current design codes is checked by the findings from this study.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.1
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• pp.25-31
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• 2021

This paper describes the design of a power cell-based pulsed power modulator with fast rise times. The pulse-generating section of the pulse power modulator is a series stack of power cells. Each power cell is composed of a storage capacitor, a pulse switch, and a bypass diode. When the pulse switches are turned on, the capacitors are connected in series and the sum of voltages is applied to the load. For output pulses with fast rise times, an IGBT with fast turn-on characteristics is adopted as a pulse switch and the optimized gate driving method is used. Pspice simulation is performed to account for the gate driving method. A 10 kV, 12-power cell-based pulsed power modulator is tested under resistive load and plasma reactor load. The rise times of output pulses less than 20 ns are confirmed, showing that the pulsed power modulator can be effectively applied to pulsed power applications with fast rise times.

• Proceedings of KOSOMES biannual meeting
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• 2003.11a
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• pp.219-225
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• 2003

The present study intends to assess the long-term steric sea-level change and its prediction, and potential impacts to the sea-level rise due to the 21st global warming in the coastal zone of the Korea in which much socioeconomic activities have been occurred. The analysis of the 23 tide-gauge data near Korea reveals the overall mean sea-level trend of 2.31 mm/yr.In the satellite altimeter data (Topex/Poseidon and ERS), the sea-level trend in the East Sea is 4.6mm/yr. Both are larger than those of the global average value. However, it is quite questionable that the sea-level trends with the tide-gauge data on the neighboring seas of Korea relate to global warming because of the relatively short observation period and large spatial variability. It is also not clear whether the high trend of altimeter data in the East Sea is related to the acceleration of sea level rise in the Sea, short response time of the Sea, natural variability such as decadal variability, short duration of the altimeter. The coastal zone of Korea appears to be quite vulnerable to the 21st sea level rise such that for the I-m sea level rise with high tide and storm surge, the inundation area is 2,643 km2, which is about $1.2\%$ of total area and the population in the risk areas of inundation is 1.255 million, about $2.6\%$ of total population. The coastal zone west of Korea is appeared to be the most vulnerable area compared to the east and south. In the west of the Korea, the North Korea appears to be more vulnerable than South Korea. In order to cope with the future possible impact of sea-level rise to the coastal zone of Korea effectively, it is essential to improve scientific information in the sea-level rise trend, regional prediction, and vulnerability assessment near Korean coast.

• KIEAE Journal
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• v.10 no.5
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• pp.159-164
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• 2010

High-rising buildings are a sort of solution to recent cities. Till now real estate development was concentrated in new development on vacant lots, and it resulted urban sprawl. Generally large cities are confronted with the exodus of industry and population from city. High-rising buildings solve many problems associated with this problem. The purpose of this research is to identify the effect of super high-rise mixed use building project process on apartment price. For this study, the hypothesis is that price of apartments is influenced by project process of super high-rise mixed use building. The study concerned 4 variations of project process that is building permits stage, sale stage, construction starting stage and stage of moving into building. The target projects of buildings are selected by number of floor(over 40 floors) and construction time. And 48 apartment complex are selected around super high-rise mixed use building. This study uses hedonic price function to analysis effect of project process of super high-rise mixed use building. A price of apartments is defined as a dependent variable. Characteristics of residence, complex, district and super high-rise building are defined as independent variables. The results are as follows; first, there is no error in price model of this study. Second, it is found that apartment price was influenced negatively by building permit stage and sale stage of super high-rise mixed use building. But that was influenced positively by construction starting stage and stage of moving into building of that. Third, as the project process of super high-rise mixed use building was proceeded, price of apartments was increased.

• Wind and Structures
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• v.34 no.5
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• pp.395-405
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• 2022

Tornado-induced damages to high-rise buildings and low-rise buildings are quite different in nature. Tornado losses to high-rise buildings are generally associated with building envelope failures while tornado-induced damages to low-rise buildings are usually associated with structural or large component failures such as complete collapses, or roofs being torn off. While studies of tornado-induced structural damages tend to focus mainly on low-rise residential buildings, transmission towers, or nuclear power plants, the current rapid expansion of city centers and development of large-scale building complexes increases the risk of tornadoes impacting tall buildings. It is, therefore, important to determine how tornado-induced load affects tall buildings compared with those based on synoptic boundary layer winds. The present study applies an experimentally simulated tornado wind field to the Commonwealth Advisory Aeronautical Research Council (CAARC) building and estimates and compares its pressure coefficient effects against the Atmospheric Boundary Layer (ABL) flow field. Simulations are performed at the Wind Engineering, Energy and Environment (WindEEE) Dome which is capable of generating both ABL and tornadic winds. A model of the CAARC building at a scale of 1:200 for both ABL and tornado flows was built and equipped with pressure taps. Mean and peak surface pressures for TLV flow are reported and compared with the ABL induced wind for different time-averaging. By following a compatible definition of the pressure coefficients for TLV and ABL fields, the resulting TLV pressure field presents a similar trend to the ABL case. Also, the results show that, for the high-rise building model, the mean and 3-sec peak pressures are larger for the ABL case compared to the TLV case. These results provide a way forward for the code implementation of tornado-induced pressures on high-rise buildings.

• Korean Journal of Construction Engineering and Management
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• v.14 no.2
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• pp.96-107
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• 2013

Tower crane hoisting plan is one of the key element for the success of entire High-Rise Building construction. Hoisting time is the basic factor to appropriate hoisting plan which need to the hoisting load estimate and tower crane selection. With this reason, accurate hoisting time is needed to the proper hoisting plan. The current hoisting time estimation for High-Rise Building focus on the hoisting cycle time estimation with historical data. However, this method underestimated the external influences like environmental factor. Thus, this paper aims to develop the hoisting time estimation model with discrete event simulation which include the wind influences with certain height. According to the simulation result, the hoisting time which applied wind influence is increasing with height growth. Because of the high speed wind, the upper area of building has more operation delay time than the mechanical operation time. Seoul, the research area, has the most fastest wind speed on April and the least on October. Due to these differences of wind speed, the hoisting time is estimated with significant differences between April and October. This hosting time estimation model would be used for estimating the influence of wind. Moreover, this could apply to make the realistic hoisting plan.

• Journal of the Korean Institute of Telematics and Electronics
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• v.4 no.4
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• pp.13-18
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• 1967

Since all the poles of the open circuit voltage transfer function of the trigonometric, linear, passive RC circuits exist on the negative real axis of s-plane, its transient response to the unit step input is monotonic. This satisfies the necessary conditions for the applicability of Elmore's method which had been developed originally for the transient analysis of lumped circuit in computing the rise time and delay time of the trigonometric distributed RC circuits. This paper describes the computing method of rise and delay times of the trigonometric distributed RC circuit. The analysis shows that the transient response of this kind circuit depends only upon the time constant and distance angle $\theta$. As $\theta$ is increased, the rise and delay titles are increased non-linearly.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.2
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• pp.238-243
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• 2012

The purpose of this study is to search the temperature-rise time conditions for adequate reforming temperature region of hydrogen generation system. And we measured theexhaust gas at the exit of that system in order to know the combustion state of hydrogen generation system's combustor. We found the optimum condition of heat supply and temperature-rise time at well burned state. And the results were nearly same when the reactants were entered to each reactors. We will further consider the effects of temperature change near the exothermic reactors and find out hydrogen yield through reforming experiment.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1850-1855
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• 2010

The application field of the pulse power is very wide. Recently, Pulse power technologies take a large place in several applications. Then, many civil and military applications proceed. Marx generator is widely used in high voltage applications. Marx generator is widely used in high voltage applications, such as eletromagnetic wave and power lasers. This paper, we described about the high voltage pulse generator. A compact size high voltage pulse generator with nanosecnd rise time has been fabricated and investigated experimentally. The marx generator has 2 stages. Each stage was constructed one charging capacitor, two electrodes and one charging resistor. A inductance structure is used in order to improve the switching performances fo the whole generator. The experiments of rise time in pure gas and mixtures of gases were described. We tested the Marx generator at different insulation gas. the results show that the dielectric strength of the $N_2-SF_6$ mixture was significantly increased compared with pure nitrogen gas. The experimental results show that the rise time characteristics of the Marx generator can be controlled through varying insulation gas.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.48-48
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• 2009

Conventionally in pulsed gas metal arc welding (GMAW-P), drop transfer is analyzed with simplest square pulse waveform. While the pulse current is described by four parameters (peak current magnitude and time plus base current magnitude and time), it deviates the real pulse shape. Real pulse can be better idealized by the trapezoidal pulse waveform described by two additional parameters, i.e., current rise and fall rate (dI/dt). Power source response rate is described by these parameters. In this work, the effect of these parameters on drop transfer is predicted by the force displacement model (FDM). While peak current has significant effects on drop detachment, drop transfer is also influenced by the current rise rate. Predictions indicate that the current rise rate can have considerable effects on the size of the detached drop if other pulse parameters are kept constant. FDM is applied to determine peak time for one drop one pulse condition (ODOP) when rests of the pulse parameters are given. The predicted range of ODOP shows good agreement with experimental data.