• 한국농공학회지
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• 제38권1호
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• pp.79-89
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• 1996

It is expected that the soil hehaviours in the seahed subjected to cyclic wave loads are much different from that on the ground Cyclic shear stresses developed below the ocean bed as a result of a passing wave train may progressively build up pore pressure in certain soils. Such build-up pore pressure may be developed dynamic behaviour such as liquefaction and significant deformation of the seabed. Currently available analytical and testing methods for the seabed subjected to cyclic wave loads are not general. The purpose of the study are to provide a test method in laboratory and to analyse the mechanism of wave-induced stresses and liquefactions potentials of the unsaturated silty marine sand. It is showed that the test set-up made especially for this study delivers exactly oscillatory wave pressures of the form of sine function. Laboratory test results defining the cyclic shear strength of the unsaturated porous medium that is homogenously sedimented. It is understood that the pore water pressure due to induced-waves is not accumulated as the wave number increases but reveals periodical change on the still water surface. The magnitude of the pore water pressure tends to be attenuated radically with a certain time lag under the action of both high and low waves as depth increases.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.648-658
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• 2018

Regarding the fact that wind power forecast accuracy is gradually improved as time is approaching, this paper proposes a two-stage rolling dispatch approach based on model predictive control (MPC), which contains an intra-day rolling optimal scheme and a real-time rolling base point tracing scheme. The scheduled output of the intra-day rolling scheme is set as the reference output, and the real-time rolling scheme is based on MPC which includes the leading rolling optimization and lagging feedback correction strategy. On the basis of the latest measured thermal unit output feedback, the closed-loop optimization is formed to correct the power deviation timely, making the unit output smoother, thus reducing the costs of power adjustment and promoting wind power accommodation. We adopt chance constraint to describe forecasts uncertainty. Then for reflecting the increasing prediction precision as well as the power dispatcher's rising expected satisfaction degree with reliable system operation, we set the confidence level of reserve constraints at different timescales as the incremental vector. The expectation of up/down reserve shortage is proposed to assess the adequacy of the upward/downward reserve. The studies executed on the modified IEEE RTS system demonstrate the effectiveness of the proposed approach.

• 한국전문물리치료학회지
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• 제21권1호
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• pp.63-69
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• 2014

Cross knee curl-up is an ideal variation of abdominal curl up exercise to strengthen abdominal musculature without excessive lumbar flexion which can increase the loads on the disc and ligaments. In addition, slowly forced expiration can facilitate the activation of the abdominal musculature. The purpose of this study was to determine the effects of slowly forced expiration on activity of abdominal muscles, such as rectus abdominis (RA), external oblique (EO), and transverse abdominis/internal oblique (TrA/IO), while cross knee curl-up. Eleven young and healthy subjects (6 males and 5 females) participated. All subjects performed the cross knee curl-up slowly forced expiration and natural breathing. Paired t-test was performed in normalized electromyogram (EMG) muscle activity of the bilateral RA, EO, and TrA/IO to compare the differences between the cross curl-up with slowly forced expiration and natural breathing. Statistical significance was set at .05. There were no significant differences in normalized EMG muscle activity of the bilateral RA, EO, and TrA/IO between the cross curl-up with slowly forced expiration and natural breathing. The finding of this study designates that slowly forced expiration does not induce increasing activity of abdominal muscle in cross knee curl-up; hence, learning step of breathing control might not be necessary to strengthen abdominal muscle in cross knee curl-up.

• Structural Engineering and Mechanics
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• 제57권1호
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• pp.141-159
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• 2016

Bearing joint dynamic parameter identification is crucial in modeling the high speed spindles for machining centers used to predict the stability and natural frequencies of high speed spindles. In this paper, a hybrid method is proposed to identify the dynamic stiffness of bearing joint for the high speed spindles. The hybrid method refers to the analytical approach and experimental method. The support stiffness of spindle shaft can be obtained by adopting receptance coupling substructure analysis method, which consists of series connected bearing and joint stiffness. The bearing stiffness is calculated based on the Hertz contact theory. According to the proposed series stiffness equation, the stiffness of bearing joint can be separated from the composite stiffness. Then, one can obtain the bearing joint stiffness fitting formulas and its variation law under different preload. An experimental set-up with variable preload spindle is developed and the experiment is provided for the validation of presented bearing joint stiffness identification method. The results show that the bearing joint significantly cuts down the support stiffness of the spindles, which can seriously affects the dynamic characteristic of the high speed spindles.

• 음성과학
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• 제5권2호
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• pp.7-16
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• 1999

Starting as a poet, I learned about the sounds of words with David Abercrombie. Then, remembering my background in physics, I moved to studying acoustic phonetics and speech synthesis. From there I learned about psychology and how. to test perceptual theories. A meeting with a physiologist led to work on the use of the respiratory muscles in speech. Later I landed in Africa teaching English phonetics and learning about African languages. When I went to UCLA to set up a lab I was able to find bright students who helped make computer models of the vocal tract and taught me linguistic theory. And I was able to continue wandering around the world, describing the sounds of a wide range of languages.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 춘계 학술논문 발표대회 2부
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• pp.35-37
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• 2011

This study was a comparison result between the laboratory and mock up test to apply the ultra high strength concrete to CFT(Concrete Filled Tube) structure. The investigated result of tendency and quality similarity of each specimen, was set up a management range according to checking the validity and suitability analysis. Also, It wil be utilized to data as construction guidelines of CFT.

• Carbon letters
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• 제26권
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• pp.74-80
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• 2018

The South Korean Ministry of the Environment has revised the laws relating to the management of interior air quality for multiple use facilities, and recommends maintaining carbon dioxide ($CO_2$) concentration in passenger vehicles below 1000 ppm during operation in urban areas of large cities. However, the interior $CO_2$ concentration of passenger vehicles can rapidly increase and exceed 5000 ppm within 30 min, as observed when two passengers are traveling in urban areas of the South Korean city of Jeonju with the air conditioner blower turned off and the actuator mode set to internal circulation mode. With four passengers, $CO_2$ concentration can reach up to 6000 ppm within 10 min. To counter this, when the actuator is set to external mode, $CO_2$ concentration can be maintained below 1000 ppm, even after a long period of running time. As part of the air conditioning system, alkali-treated activated carbon fiber filters are considered to be far superior to the commercial non-woven filters or combination filters currently commonly in use.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권11호
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• pp.5625-5641
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• 2017

Certificateless public key cryptography resolves the certificate management problem in traditional public key cryptography and the key escrow problem in identity-based cryptography. In recent years, some good results have been achieved in speeding up the computation of bilinear pairing. However, the computation cost of the pairing is much higher than that of the scalar multiplication over the elliptic curve group. Therefore, it is still significant to design cryptosystem without pairing operations. A multi-signer universal designated multi-verifier signature scheme allows a set of signers to cooperatively generate a public verifiable signature, the signature holder then can propose a new signature such that only the designated set of verifiers can verify it. Multi-signer universal designated multi-verifier signatures are suitable in many different practical applications such as electronic tenders, electronic voting and electronic auctions. In this paper, we propose a certificateless multi-signer universal designated multi-verifier signature scheme and prove the security in the random oracle model. Our scheme does not use pairing operation. To the best of our knowledge, our scheme is the first certificateless multi-signer universal designated multi-verifier signature scheme.

• Geomechanics and Engineering
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• 제10권1호
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• pp.49-57
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• 2016

The high permeability-high strength concrete belongs to the typical of porous materials. It is mainly used in underground engineering for cold area, it can act the role of heat preservation, also to be the bailing and buffer layer. In order to establish a suitable model to predict the thermal conductivity and directly applied for engineering, according to the structure characteristics, the thermal conductivity predicting model was built by resistance network model of parallel three-phase medium. For the selected geometric and physical cell model, the thermal conductivity forecast model can be set up with aggregate particle size and mixture ratio directly. Comparing with the experimental data and classic model, the prediction model could reflect the mixture ratio intuitively. When the experimental and calculating data are contrasted, the value of experiment is slightly higher than predicting, and the average relative error is about 6.6%. If the material can be used in underground engineering instead by the commonly insulation material, it can achieve the basic requirements to be the heat insulation material as well.

• 공학교육연구
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• 제3권2호
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• pp.14-23
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• 2000

본 논문은 인터넷을 이용한 공학 교육의 효과를 높이기 위한 수단으로서 원격 계측 실험실의 구축에 대하여 연구한 결과를 포함하고 있다. 최근에 멀티미디어를 이용한 가상 실험 실습실의 축이 가시화되고 있으나 실제 시스템을 대상으로 한 인터넷 실험 실습실은 널리 보급되고 있지 않다. 본 논문에서는 실험실 자동화를 위하여 사용된 GPIB제어 기술과 인터넷 연결 기술을 결합하여 원격으로 실험 실습이 가능한 시스템을 구축하였다. 함수발생기, LCR미터, 오실로스코우프에 대한 제어 프로그램을 구축하고 몇 가지 전자 회로를 대상으로 실험을 수행해 본 결과 다양한 종류의 실험을 원격으로 수행할 수 있으며 교육 효과 또한 매우 높음을 발견할 수 있었다. 본 연구에서는 원격 계측 실험실 구축과 관련된 기술을 소개하고 문제점을 토의하고자 한다.