• Electronics and Telecommunications Trends
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• 제22권6호
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• pp.116-128
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• 2007

1974년 인터넷 개념이 처음 제안된 이후, 지난 30년 넘게 인터넷은 현재 사용되는 글로벌 네트워크의 대표주자로 자리매김 하고 있다. 그러나 2000년대에 들어서면서부터 통신환경의 급격한 변화 및 다양한 사용자 요구사항의 증대로 인해 현재의 인터넷이갖는 근본적인 문제에 대해 심각한 고민을 하기 시작하였으며, 그 연장선 중 하나로 최근 Clean Slate 설계 방법에 기반을 둔 미래인터넷 연구가 국내외로 활발히 진행되고 있다. 본 고에서는 미래인터넷의 연구 배경으로 현 인터넷의 성공배경 및 문제점들을 먼저 살펴보고, 이를 기반으로 미래인터넷을 위한 요구사항 및 설계목표 등을 알아본다. 또한 최근 활발히 연구 진행중인 미래인터넷 핵심 기술들에 대해 분석하고, 미국, 유럽, 일본, 우리나라가 전략적으로 추진중에 있는 프로젝트 동향, 성공 시나리오 등을 살펴본다. 끝으로 현재 ISO/IEC JTC1/SC6, ITU-T 등에서 추진 계획중에 있는 표준화 동향에 대해 살펴본다.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• 제19권3호
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• pp.394-401
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• 2010

In this article, we investigate a robust friction compensation scheme for the purpose of accomplishing precision positioning performance a servo mechanical system with nonlinear dynamic friction. To estimate the friction state and tackle robustness problem for uncertainty, a RFNN and reconstructed error compensator as well as a robust friction state observer are developed. The asymptotic stability of the series of friction compensation methodologies are verified from the Lyapunov's stability theory. Some simulations and experiments on a servo mechanical system were carried out to evaluate the effectiveness of the proposed control scheme.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.541-544
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• 2006

This study was performed to proof expansion effect of the mortar bar due to Alkali-silica Reaction (ASR) by ASTM C 1260 test. Recently, the failure case of cement concrete pavement by ASR was reported in Korea. Cement concrete structures are caused crack by ASR. The service life of cracked cement concrete structures by ASR will be shorted. In this study, crushed the slate rock producted Chungcheongnamdo Boryeong was caused 0.3% expansion at 14 days due to ASR by ASTM C 1260 test. The particular spectrum showed that the ASR gel was analyzed contents included Si, Na, K, and Ca by EDX (electron dispersive X-ray spectrometer). It was verified that the crushed aggregate was caused expansion by ASR in Korea.

• Proceedings of the KIEE Conference
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.996-998
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• 1996

This paper shows how the $H_{\infty}$ control problem of singular nonlinear systems via output feedback can be solved. The solution of the problem is shown to be related to the existence of solutions of a pair of Hamilton-Jacobi inequalities in n independent variables, which are associated with slate feedback and output injection design. Our approach yields to a set of sufficient conditions under an extra assumption. This conditions are in terms of a set of Hamilton-Jacobi Inequalities parameterized by adequately small parameters.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.495-495
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• 2000

The Stewart platform manipulator is a closed-kinematis chain robot manipulator that is capable of providing high st겨ctural rigidity and positional accuracy. However, this is a complex structure, so controllability of the system is not so good. In this paper, it introduces a new robust motion control algorithm using partial state feedback for a class of nonlinear systems in the presence of modelling uncertainties and external disturbances. The major contribution of this work introduces the development and design of robust observer for the slate and the perturbation w.hich is integrated into a variable structure controller(VSC) structure. The combination of controller/observer gives rise to the robust routine called sliding mode control with sliding perturbation observer(SMCSPO). The optimal gains of SMCSPO are easily obtained by genetic algorithm. Simulation and experiment are presented in order to apply to the stewart platform manipulator. There results show highly' accuracy and performance.

• The Journal of the Petrological Society of Korea
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• 제9권1호
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• pp.13-28
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• 2000

Chojeong area is mainly composed of the Ogcheon Group which consists of regionally metamorphosed, age-unknown sedimentary rocks. In the northwestern parts, the Group is intruded by the Jurassic Daebo granite and Cretaceous felsic and mafic dykes. The lowermost, Midongsan Formation which consists of milky white impure quartzite, crops out along the anticline axes with N40E trend. Ungyori quartzite Formation is intercalated with quartzite and slate. Miwon Formation is most widely exposed in the area and consists mainly of phyllitic sandy rocks with a thin crystalline limestone bed. Hwajeonri Formation is divided into two parts, pelitic lower and calcareous upper parts, composed with phyllite and slate. Changri and Hwanggangri Formations are typical members of Ogcheon Group, the former bearing coally graphite seams consists mainly of black slate and phyllite with intercalated greenish grey phyllite, the latter is pebble bearing phyllite formation of which matrix and pebbles are variable in compositions and size. Biotite granite, porphyritic granite and two mica granite belong to Jurassic so-called Dabo granite. They intruded the Ogcheon Group forming vast contact metarnophic zone. Quartz porphyry, mafic dyke and felsite intruded along the marginal zone of porphyritic granite batholith and fracture of NS trend. Main structural lineaments in Ogcheon Group shows N25-45E, NS and N30-45W trends. The N25-45E trends are mainly from general ductile deformation during regional metamorphism, showing isoclinal folding, Fl foliations and lithological erosional characters. Some of these trends are due to normal faults. The NS and N30-45W trends represent brittle deformation including faults and joints. In the area of granitic batholith, NS to N30- 45 trends are from the direction of dykes. In the soils of the area, average contents of heavy metal elements such as Cd, Cr, Cu, Pb, and Zn are 0.2, 50.6, 35.5, 27.9, and 93.4 ppm respectively, which are not higher than the average values of natural soils, under the tolerable level. Enrichment Index does not show any heavy metal pollution in the area. Average depths of weathering(5m vs. 2m), porosities(43.94 vs. 51.80), densities(l.29 vs. 1.15), and permeabilities(2.52 vs. 8.07) are comparable in granite areas and in the phyllite areas of Ogcheon Group.

• Journal of Korean Society of Coastal and Ocean Engineers
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• 제29권6호
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• pp.315-325
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• 2017

This study aims to provide information for the design and use of structural lightweight concrete (SLWC) for floating concrete structures in a marine environment. An experimental program was set up and comprehensive experimental campaign were carried out to determine SLWC mix proportions that can satisfy specified concrete strength, density, and slump values all of them were determined from previous research. Comparisons with previous SLWC mix designs that have been utilized for actual floating concrete structures were made. Key aspects needed to be considered regarding to the use of SLWC for floating marine concrete structures were discussed.

• Journal of the Korea Concrete Institute
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• 제23권5호
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• pp.551-558
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• 2011

The effect of the maximum aggregate size and substitution rate of natural sand on the mechanical properties of concrete is evaluated using 15 lightweight aggregate concrete mixes. For mechanical properties of concrete, compressive strength increase with respect to age, tensile resistance, elastic modulus, rupture modulus, and stress-strain relationship were measured. The experimental data were compared with the design equations specified in ACI 318-08, EC2, and/or CEB-FIP code provisions and empirical equations proposed by Slate et al., Yang et al., and Wang et al. The test results showed that compressive strength of lightweight concrete decreased with increase in maximum aggregate size and amount of lightweight fine aggregates. The parameters to predict the compressive strength development could be empirically formulated as a function of specific gravity of coarse aggregates and substitution rate of natural sand. The measured rupture modulus and tensile strength of concrete were commonly less than the prediction values obtained from code provisions or empirical equations, which can be attributed to the tensile resistance of lightweight aggregate concrete being significantly affected by its density as well as compressive strength.

• Economic and Environmental Geology
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• 제28권1호
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• pp.25-31
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• 1995

In Dongnam area, Cretaceous igneous rocks, such as diorite, porphyritic granite, and quartz porphyry intruded Paleozoic sedimentary rocks, such as Myobong slate and Pungchon limestone. The Dongnam Fe-Mo skarn deposits were imposed on the diorite(endoskarn) and the Myobong slate(exoskarn). The ore deposits consist mainly of magnetite and molybdenite with small amounts of sulfides, such as galena, sphalerite, pyrite, chalcopyrite, and pyrrhotite. The igneous rocks show nearly constant $^{206}Pb/^{204}Pb(18.80{\sim}19.06)$ and $^{207}Pb/^{204}Pb(15.71{\sim}15.72)$ ratios. Their $^{207}Pb/^{204}Pb$ ratios higher than the typical ratios of orogene suggest that the igeneous rocks were formed from lower crust(or mantle) - derived magma excessively contaminated by upper crustal materials such as high radiogenic Precambrian basement rocks. The lead isotopic compositions of the igneous rocks, the Pungchon limestone, and the ore minerals show a well defined linear in $^{206}Pb/^{204}Pb$ - $^{207}Pb/^{204}Pb$ plot. The lead isotopic compositions of the igneous rocks are similar to those of magnetite and galena, which were formed at early skarn stage and significantly lower than those of altered quartz porphyry, molybdenites, and pyrite, which were formed at late epithermal alteration stage. Considering the systematic variation of the lead isotopic compositions in the ore minerals according to hydrothermal stages, the variation may be due to a relative variation in surrounding rock(Pungchon limestone) involvement in hydrothermal ore solution leaching the surrounding rock. Therefore, the variation of the lead isotopic compositions in ore minerals can be modeled in terms of the mixing of the leads derived from the igneous rocks as low radiogenic source and the surrounding rock(Pungchon limestone) as high radiogenic source.

• Journal of Korean Ophthalmic Optics Society
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• 제2권1호
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• pp.111-126
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• 1997

I concluded as follows after analyzing the problem of the curriculum in the Department of Optical Science at a college of professional education for the purpose of training desireable opticians. The years required for competing a course of study at the Department of Optical Science at a college of professonal education have to be extended from the present two school years to three years for the short run and have to be extended to four years for the long run. The distribution ratio of subjects in the slate examination should be readjusted and the field of contect lens. Also the system of the slate examination should strengthen by adding practical processing test with the present selective written examination. The Curriculum of department of Optical Science curriculum at a college of professional education should be reorganized reinforce experiment and practice, namely, the subject for experiment and practice, such as Making of specific glasses and Test method of phorpter etc, should be reinforced. The knowledge for goods should be included in clinical training and it is reasonable to constitute the theory vs the practice in the ratio of five to five. The number of the Department of Optical Science should be increased two or more for per forty students and it is desirabled that only the professors who major optical Science or opthalmic medical science, or have Optician Licence should give lecture. The experiment a practice should be enlarged and it is necessary to secure or to adopt practice hours, practice site, machinery and parts, practice assistant and etc. It is reasonable that clinical training include the knowledge of goods, business practice and etc. and that a practice examiner has the qualification as an optician who has education background higher that the college of professional education.