• Tunnel and Underground Space
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• v.10 no.2
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• pp.173-179
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• 2000

The influence of the plastic flow rules on the elasto-plastic behaviour of a discrete joint element was investigated by performing the numerical direct shear tests under both constant normal displacement and normal displacement conditions. The finite interface elements obeying Plesha’s joint constitutive law was used to allow the relative motion of the rock blocks on the joint surface. Realistic results were obtained in the tests adopting the non-associated flow rule, while the associated flow rule overestimated the joint dilation. To overcome the computational drawbacks coming from the non-symmetric element stiffness matrix in the conventional non-associated plasticity, the symmetric formulation of the tangential stiffness matrix for a non-associated joint element was proposed. The symmetric elasto-plastic matrix it derived by assuming an imaginary equivalent joint with associated flow rule which shows the same plastic response as that of original Joint with non-associated flow rule. The validity of the formulation was confirmed through the numerical direct shear tests under constant normal stress condition.

• Composites Research
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• v.15 no.3
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• pp.30-38
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• 2002

Fiber Bragg grating(FBG) like other optical fiber sensors also has the merit of embedding capability. To increase their actual value related to embedding capability, this paper reported the reliability and signal characteristics of FBGS embedded in composite laminates. The microphotographs of embedded optical fibers visualized the embedding environments of stripped optical fibers and coated optical fibers. Based on these microphotographs and cure monitoring performed using FBGs, we could understand that the main cause breaking the unique Bragg condition of low-birefrigence FBG were residual stress artier curing and reported the stale of stress/strain of optical fiber quantitatively. The cure monitoring also showed the history of splitting peak of a stripped FBG along cure processing. In addition, we could obtain a transverse insensitive grating(TIG) with ease by recoating a stripped FBG. TIG has good advantage for real-time signal processing.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.5
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• pp.559-565
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• 2010

In this study we propose noise energy harvesting for green infrastructure development. In this regard, infrastructures such as railroad, subway, and road are taken into consideration as sources of noise which provides energy through certain wave forms. As the need of recycling noise energy became reasonable due to the increase of infrastructure usage, the capacity and property of our noise energy generating device, which uses electromagnetic induction for electricity generation, are analysed in this paper. Consequently, the outcomes of this experiment show the fact that maximum electricity is generated from the device at a specific point of noise frequency, and the relation between air pressure caused by noise and the electricity generated by the device is in a specific proportional form either linear or non-linear. The major points of developing noise energy generating device in order to apply it into social infrastructure are discussed in this paper as well.

• Composites Research
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• v.14 no.6
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• pp.16-23
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• 2001

Analysis of mechanical behavior for a pultruded-wound hollow rod is presented. For this purpose, the pultruded-wound hollow rod is manufactured by the new winder attached to the conventional pultrusion system. And the conventional pultrusion process is newly altered to manufacture pultruded-wound specimens. A computer program, POST II, is modified to perform this study, In the nonlinear finite element formulation, the updated Lagrangian description method based on the second Piolar-Kirchhoff stress tensor and the Green strain tensor are used. For the finite element modeling of the composite hollow rod, the eight-node degenerated shell element is utilized. In order to estimate the failure, the maximum stress criterion is adopted to the averaged stress in the each layer of the finite elements. As numerical examples, the behavior of glass/up composite hollow rod is investigated from the initial loading to the final collapse. Present finite element results considering stiffness degradation and stress unload due to failure shows excellent agreement with experiments in the ultimate load, failure and deformations.

• Journal of Korean Medical classics
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• v.19 no.3
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• pp.432-438
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• 2006

${\ulcorner}$소문대요(素門大要)${\lrcorner}$는 한국의 이규준(李圭晙)이 편저한 중의문헌과 임상이론이 결합된 중요한 저작물이다. 이 책은 광무갑진팔년(光武甲辰八年)(1904년) 음력 3월 16일에 완성되었고, 광무병오(光武丙午)(1906년) 초여름 밀양(密陽) 금천(琴川)에서 조판간행(雕版刊行)되었다. 이 책의 저자인 석곡(石谷) 이규준(李圭晙)(1855-1923)은 경상북도 영일군 사람으로 ${\ulcorner}$소문(素問)${\lrcorner}$ 뿐만 아니라 ${\ulcorner}$영추(靈樞)${\lrcorner}$ ${\ulcorner}$상한론(傷寒論)${\lrcorner}$ ${\ulcorner}$금궤요략${\lrcorner}$ ${\ulcorner}$잡경(難經)${\lrcorner}$ ${\ulcorner}$맥경(服經)${\lrcorner}$ 및 김원사대가(金元四大家)의 저작 등에 대해서도 심도 깊은 연구를 하였다. ${\ulcorner}$소문대요(素門大要)${\lrcorner}$의 중요 공헌은 ${\ulcorner}$소문(素問)${\lrcorner}$의 중요 문장을 회집(匯集)하였을 뿐만 아니라, 이규준(李圭晙) 자신의 의학이론과 임상사상이 표현되어 있다는 것이다. 이규준(李圭晙)은 ${\ulcorner}$소문(素問)${\lrcorner}$의 여러 편(篇) 가운데 특히 ${\ulcorner}$생기통천론(生氣通天論)${\lrcorner}$의 문장을 통해 '양비급고(陽秘乃固)'의 사상을 중요시 하여, 양기(陽氣)의 작용을 강조하면서 '양상유여음상부족(陽常有餘陰常不足)'의 편면성(片面性)을 극복하였다. 이러한 과정에서 그가 제시한 이론은 바로 '부양론(扶陽論)'으로, 그는 ${\ulcorner}$내경(內經)${\lrcorner}$ 십팔권(十八卷)의 내용을 한 마디로 요약하면 '양밀급고(陽密乃固)'라고 주장하였다. 한편 그가 ${\ulcorner}$소문대요(素門大要)${\lrcorner}$를 저술하면서 저본(底本)으로 삼았던 것은 명대(明代)에 간행(刊行)된 고종덕목(顧從德本)이라고 할 수 있다. 이규준(李圭晙)은 고종덕목(顧從德本)을 저본(底本)으로 하여 ${\ulcorner}$소문(素問)${\lrcorner}$의 문장을 해석하였고, 아울러 교감(校勘)을 병행하였는데 그의 교감법(校勘法)은 일정한 판본(版本)에 근거한 것이 아니라 자신의 ${\ulcorner}$소문(素問)${\lrcorner}$ 에 대한 이해를 중심으로 교감(校勘)을 하였다. 또한 그는 훈고학 방면에서도 일정한 식견을 갖추고 있는 것으로 확인되었다. 마지막으로 ${\ulcorner}$소문대요(素門大要)${\lrcorner}$ 는 간행본(刊行本)과 수초본(手抄本)이 유행되고 있는데, 수초본(手抄本)의 경우 와전(訛傳)된 글자가 많으니 간행본(刊行本) 및 ${\ulcorner}$소문(素問)${\lrcorner}$의 원문과 대조하여 잘못된 글자를 바로잡을 필요가 있다.

• Journal of the Korean Magnetics Society
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• v.11 no.4
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• pp.146-150
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• 2001

The effect of H$_2$ content in Ar sputtering gas on exchange coupling field(H$_{ex}$) for NiFe/FeMn interface was studied. When NiFe layer of Si(100)/Ta(50 $\AA$)/NiFe(60 $\AA$)/FeMn(250 $\AA$)Ta(50 $\AA$) was deposited at 8% H$_2$ in sputtering gas, the maximum exchange coupling field(H$_{ex}$) and minimum coercivity(H$_{c}$) were obtained. When Si(100)/Ta(50 $\AA$)/NiFe(60 $\AA$)/FeMn(250 $\AA$)/NiFe(70 $\AA$)/Ta(50 $\AA$) was deposited at 5% H$_2$ in sputtering gas, the maximum exchange coupling field(H$_{ex}$) of 148 Oe was obtained. The (111) preferred orientation and grain size of underlayer NiFe were increased and the internal stress was reduced by H$_2$ in sputtering gas. And the (111) preferred orientation and grain size of FeMn layer were also increased.d.ased.

• Korean Journal of Food Science and Technology
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• v.32 no.4
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• pp.974-978
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• 2000

The vane method was used to measure yield stresses of five commercial kochujang samples under a controlled shear-rate operating condition. Magnitudes of vane yield stress were higher than those of yield stress using Casson model with a concentric cylinder viscometer. Magnitudes of vane yield stresses showed great differences between the static $({\sigma}_s)$ and dynamic yield stresses $({\sigma}_d)$ of kochujang samples with undisturbed structure (UDS) and with broken down structure (BDS). A dimensionless yield number $(N{\sigma}_o)$ was determined from the ratio of ${\sigma}s$ to ${\sigma}d$ in order to describe the existence of temporary structure of kochujang.

• Journal of the Korean earth science society
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• v.24 no.8
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• pp.704-710
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• 2003

A study for analysing the characteristics of the 'Tsunami Earthquake' and 'Tsunamigenic Earthquake' has been done in terms of stress drop and tectonic characteristics using previous studies on magnitude, moment, energy, and length of fault. The 'Tsunami Earthquake' seemed to occur mainly on the subduction environment with a very low stress drop of about 10 bars and a thrust dip angle comparing those of the 'Tsunamigenic Earthquake' or other earthquakes. Released energy to moment ratio of the 'Tsunami Earthquake' also seemed to be lower. Earthquakes which generated tsunami in the East Sea seemed to be 'Tsunamigenic Earthquake' with a stress drop of about 30${\sim}$50 bars, and an average energy to moment ratio. Hence, stress drop, energy to moment ratio, and thrust dip angle seem to be indicators of earthquakes that produce tsunamis.

• Geotechnical Engineering
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• v.14 no.5
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• pp.219-234
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• 1998

Modulus measurements in vertical boreholes under simulated horizontal in-situ stress conditions were performed on laboratory rock specimens. The experimental program was focused on the examination of modulus change with the variation of the orientation, magnitude and ratios of horizontal biaxial stresses. The experiment results show that the modulus increases when the magnitude of the horizontal stresses increases. The modulus measured in the minimum principal direction increased when the ratio between the horizontal principal stresses increased, while the modulus measured in the maximum principal direction decreased when the ratio of the horizontal principal stresses increased. These were caused by the tangential stresses that vary depending upon the magnitude of horizontal stresses, the applied pressure and the orientation of measurement. Also, the measured moduli were determined under tensile stress, compressive stress, or both stresses. Thus, the stress effect on deformation modulus should be considered, not only for the interpretation of the results of borehole deformability measurement, but also for the design of underground gas storage and pressure tunnel, and for the interpretation of tunnel monitoring.

• Korean Journal of Materials Research
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• v.5 no.7
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• pp.765-774
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• 1995

The hot deformation behaviour of particulate reinforced aluminium 6061 Al composite were investigated by hot compression tests in the temperature range from 623K to 823K with strain rate of 10$^{-3}$ ~5.0 S$^{-1}$ . The effect of reinforced particulate volume fraction, mean diameter on the high temperature flow stress has also been studied. Experimental results showed that the increase in the volume fraction of reinforcement contributed to the rising of yield stress, but the stress above the yield point appeared to be steady state at all volume fractions. The apparent activation energy for deformation was 290KJ/mo1 for unreinforced 6061 Al, 327KJ/mo1 for 6061 Al-20vo1.% SiC composite and 531KJ/mo1 for 6061 Al-20vo1.%A1$_2$O$_3$composite. It appeared that $Al_2$O$_3$reinforced composites was more difficult to hot deform.