• Earthquakes and Structures
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• 제15권5호
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• pp.513-528
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• 2018

A typical viable technique to decrease the seismic response of liquid storage tanks is to isolate them at the base. Base-isolation systems are an efficient and feasible solution to reduce the vulnerability of structures in high seismic risk zones. Nevertheless, when liquid storage tanks are under long-period shaking, the base-isolation systems could have different impacts. These kinds of earthquakes can damage the tanks readily. Hence, the seismic behaviour and vibration of cylindrical liquid storage tanks, subjected to earthquakes, is of paramount importance, and it is investigated in this paper. The Finite Element Method is used to evaluate seismic response in addition to the reduction of excessive liquid sloshing in the tank when subjected to the long-period ground motion. The non-linear stress-strain behaviour pertaining to polymers and rubbers is implemented while non-linear contact elements are employed to describe the 3-D surface-to-surface contact. Therefore, Nonlinear Procedures are used to investigate the fluid-structure interactions (FSI) between liquid and the tank wall while there is incompressible liquid. Part I, examines the effect of the flexibility of the isolation system and the tank aspect ratio (height to radius) on the tank wall radial displacements of the tank wall and the liquid sloshing heights. Maximum stress and base shear force for various aspect ratios and different base-isolators, which are subjected to three seismic conditions, will be discussed in Part II. It is shown that the composite-base isolator is much more effective than other isolators due to its high flexibility and strength combined. Moreover, the base isolators may decrease the maximum level pertaining to radial displacement.

• 기술혁신학회지
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• 제18권1호
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• pp.1-27
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• 2015

우리나라는 글로벌 기술경쟁력 제고를 위해 연구개발에 대한 투자를 지속적으로 증대시켜왔다. 우리나라의 GDP대비 연구개발투자비는 4.15%로 세계 1위 수준이며, 이 가운데 기업부문은 전체 투자의 78.5%를 차지하며 매우 중요한 역할을 수행하고 있다. 그러나 더 이상 양적인 투자 증대에는 한계가 존재하기에 R&D투자에 대한 질적 수준을 높여 효율성을 제고하기 위한 노력이 절실히 필요한 실정이다. 이러한 연유로 본 연구에서는 기업의 경영성과를 제고하기 위한 방안을 강구하기 위한 연구를 수행하였다. 이를 위해 그동안 학문적으로 그 중요성이 강조된 연구개발 초기 단계인 기술전략과 기술기획 역량이 기업의 성과제고에 미치는 영향요인을 실증적으로 검증하고자 하였다. 실증분석 결과, 기술전략과 기술기획 활동이 경영성과 제고에 매우 유의미한 영향을 미치는 것으로 나타났으며, 조직유연성의 경우 개별적인 요인 또한 중요하지만 기술기획 활동을 긍정적으로 조절하여 경영성과 제고에 기여함을 확인하였다. 본 연구에서는 기업의 기술혁신 활동을 실제적으로 파악하기 위해 기업연구소를 운영하고 있는 전체 기업을 대상으로 표본조사를 수행하였으며, 분석방법으로는 다중회귀분석과 분위회귀분석을 활용하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권8호
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• pp.1911-1932
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• 2013

Orthogonal frequency-division multiplexing (OFDM) has become a popular modulation scheme for wireless protocols because of its spectral efficiency and robustness against multipath interference. Although the components of various OFDM protocols are functionally similar, they remain distinct because of the characteristics of the environment. Recently, graphics processing units (GPUs) have been used to accelerate the signal processing of the physical layer (PHY) because of their great computational power, high development efficiency, and flexibility. In this paper, we describe the implementation of parameterized baseband modules using GPUs for two different OFDM protocols, namely, 802.11a and 802.16. First, we introduce various modules in the modulator/demodulator parts of the transmitter and receiver and analyze the computational complexity of each module. We then describe the integration of the GPU-based baseband modules of the two protocols using the parameterized method. GPU-based implementations are addressed to explain how to accelerate the baseband processing to archive real-time throughput. Finally, the performance results of each signal processing module are evaluated and analyzed. The experiments show that the GPU-based 802.11a and 802.16 PHY meet the real-time requirement and demonstrate good bit error ratio (BER) performance. The performance comparison indicates that our GPU-based implemented modules have better flexibility and throughput to the current ones.

• 한국기계가공학회지
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• 제5권1호
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• pp.27-32
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• 2006

Thermoplastic elastomer(TPE) has many advantages such as high flexibility, high elasticity and high elongation, etc. TPE is easily molded as plastic materials, therefore, many TPE parts are applied as home appliances and mechanical parts. However, its mechanical properties would be changed by injection molding conditions such as melt temperature, mold temperature, injection pressure and holding pressure, etc. In this study, the influences of the injection molding condition on the mechanical properties as tensile strength, hardness of thermoplastic vulcanizates(TPVs), which is one of the TPE, were investigated. By the injection molding experiment, the molding's tensile strength and hardness was influenced on the melt temperature and composition ratio of PP and EPDM. The morphology of moldings were shown by the scanning electron microscope.

• 산업기술연구
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• 제21권B호
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• pp.317-324
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• 2001

This study focused on the investigation of strength development and permeability of LMC(Latex Modified Concrete) and RSLMC(Rapid-Setting Cement Latex Modified Concrete) as the latex content, cement types and w/c ratio changed. The compressive strength of latex modified concrete decreased slightly and the flexural strength increased quitely at 15% of latex content. This may be due to the flexibility of latex filled in voids and interconnections of hydrated cement and aggregates by a film of latex particles, respectively. The permeability test results showed that the permeability of LMC was considerably lower than that of conventional concrete. Results of chloride permeability test, for RSLMC indicated very low at an early age caused by the early formation of needle-shape ettringites and latex film.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권4호
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• pp.1819-1831
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• 2018

This paper focuses on a header compression method for the Authentication Header (AH) and Encapsulation Security Payload (ESP) for application to 6LoWPAN. Based on the context, an extendible compression method is developed by analysing each field of the AH and ESP. The method is carried out by resetting the AH and ESP header compression formats, adding a MOD field, and setting different working modes. Authentication, encryption, and a mixture of certification and encryption are provided as flexible options. In addition, the value of the original IPv6 extensible header ID (EID) field can be retained, while the number of occupied NHC_ID values can be decreased for future extendibility. The experimental results show the feasibility and validity of the current compression method. By comparison with other solutions, the new mechanism is demonstrated to be advantageous in terms of compression ratio, flexibility and extendibility.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.389.1-389.1
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• 2016

The flexible solid state device has been widely studied as portable and wearable device applications such as display, sensor and curved circuits. A zero-bias operation without any external power consumption is a highly-demanding feature of semiconductor devices, including optical communication, environment monitoring and digital imaging applications. Moreover, the flexibility of device would give the degree of freedom of transparent electronics. Functional and transparent abrupt p/n junction device has been realized by combining of p-type NiO and n-type ZnO metal oxide semiconductors. The use of a plastic polyethylene terephthalate (PET) film substrate spontaneously allows the flexible feature of the devices. The functional design of p-NiO/n-ZnO metal oxide device provides a high rectifying ratio of 189 to ensure the quality junction quality. This all transparent metal oxide device can be operated without external power supply. The flexible p-NiO/n-ZnO device exhibit substantial photodetection performances of quick response time of $68{\mu}s$. We may suggest an efficient design scheme of flexible and functional metal oxide-based transparent electronics.

• 한국생산제조학회지
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• 제9권5호
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• pp.112-118
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• 2000

In case ESO(evolutionary structural optimization) which is one of topology optimization methods, the element removal ratio is fixed throughout topology optimization by 1 or 2%. As a result it has no flexibility for various types of structures and thus the rate of convergence might not be efficient. Thus various element removal methods were developed in order to improve the efficiency of ESO. In this paper, various element removal methods for ESO are compared with each other for a bracket and a short cantilever. In addition, a new improved bi-directional element removal method is suggested in order to obtain much better optimized topology. From the comparative results of the examples, it is verified that all of the developed various element removal methods are very effective, and the suggested element removal method is the most effective.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.1023-1028
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• 2001

This study focused on the investigation of strength development and permeability of LMC(latex modified concrete) and RSLMC(rapid-setting cement latex modified concrete) as the latex content, cement types and w/c ratio variated. The compressive strength of latex modified concrete decreased slightly and the flexural strength increased quitely at the latex content of 15%. This may due to the flexibility of latex filled in voids and interconnections of hydrated cement and aggregates by a film of latex particles, respectively. The permeability test results showed that the permeability of LMC was considerably lower than that of conventional concrete. In the RSLMC's tests of permeability to chloride ion indicated very low permeability at an early age, which nay be due to the early formation of needle-shape ettringites and latex film.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 A
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• pp.123-126
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• 2003

This paper presents an speed reference trajectory planning methods for vibration suppression in a t-mass resonant system which has a flexible coupling between a load and a driving motor. Due to this flexibility, the system often suffers vibration especially when the motor is controlled for higher speed command. The steady state conditions are utilized to derive desired load speed trajectory which does not cause the torsional vibration. And the desired motor speed trajectory is synthesized base on the relation between load and motor speed. The simulation and experiment result suggest that the proposed method effectively suppress the vibration.