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      • 기성 콘크리트 파일 두부정리를 위한 자동화 장비의 개발

        이정호,김정렬,김영석,조문영,김성근 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2

        During the last few years, the use of prefabricated concrete pile has been gradually increased in many construction sites. Cutting work of the concrete pile is an important task to crush a part of pile head which is compressed with more than 800㎏/㎠, It is usually performed by a crusher and three to four skilled workers. Recent analysis results of the pile cutting work reveal that it frequently makes a lot of cracks which significantly reduce the strength of the pile and is labor-intensive work. The primary objective of this study is to propose conceptual designs for developing an automated pile cutting machine. It is anticipated that the development of the automated pile cutting machine would be able to bring improvements in safety, productivity, quality as well as cost saving.

      • VHDL을 이용한 MAP의 링크계층의 구현

        이상호,신동렬 成均館大學校 科學技術硏究所 1997 論文集 Vol.48 No.2

        Computer-integrated automation in manufacturing systems largely depends on local-area networks (LAN's) for information exchange between devices such as computers, PLCs, NCs, and robots. Timely transfer of messages among such devices are critical for real-time operations. Manufacturing Automation Protocols (MAP) is specially designed to provide rapid and reliable which takes place on the factory floor. The token-bus network has emerged as the standard for LANs in industrial environments due to its stability, reliability, and the availability of a priority scheme. For this reason, MAP has specified the token passing bus control for use in the Medium Access Control(MAC) sublayer and Logical Link Control(LLC) sublayer in the data link layer. In this work, we will implement the token bus control algorithms with VHDL, and MAP protocol with relatively low cost. Much will be emphasized on implementing MAP standard protocol based on MAC and LLC.

      • α(t)-modification 을 이용한 수렴특성 개선에 관한 연구

        李鍾烈,權誠河 國立 昌原大學校 産業技術硏究所 1987 産技硏論文集 Vol.1 No.-

        Direct model reference adaptive control procedures were developed to control linear plants which satisfy a positivity condition. Using a combination of proportional and integral adaptive gains, these procedures achieved asymptotically perfect model output tracking with a large class of time-variable input commands. However, if perfect output tracking is not possible due to output measuring disturbances, the adaptive control system may diverge. Such divergence is to be eliminated, if the pure integration in the adaptive gains is replaced with a first order pole. But such a scheme cannot guarantee the convergence property, if disturbances are not present. In this paper, we use the reduced model to design the adaptive controller, and propose a modified adaptive law to guarantee the convergence property whether the disturbances are present or not.

      • KCI등재

        타타늄의 열처리 조건에 따른 동전위 양극분극특성 및 표면 미세구조 변화

        주동현,이용렬,정영화,양홍서,박상원,이도재,송호준,박영준 大韓齒科器材學會 2002 대한치과재료학회지 Vol.29 No.2

        The corrosion resistance of metallic implants is essential for successful implant osseointegration. Moreover, the implant surface should have appropriate surface roughness for the attachment of the osteoblast and collagen fibrils. When titanium is exposed to air a thermodynamically very stable oxide film is formed at once. This oxide is very thin and yet it protects the metal from corrosion instantaneously. However, the oxide would not be ideal, and it would be supposed that the state of oxide film would be various by the different conditions when it is formed. The objective of this study was to evaluate the electrochemical properties and surface microstructural changes of titanium after passivation treatment or exposure to high heat (in vacuum or in air). ASTM grade 2 commercially pure titanium (Ti) disks of 10㎜ diameter were wet ground and polished with 240 and 600 grit SiC, and then ultrasonically cleaned with distilled water and ethanol. Cleansed as-received samples (As-R group) were passivated with 30% nitric acid solution at 50℃ for 15 minutes to make the Pas group. The Std-V samples were made by treating the Ti disks in vacuum quartz tube (10^-8 Torr) at 530℃ for 40 min for stress relieving, followed by annealing at 700℃ for 90 min, and then slow cooling to room temperature. The Std-A samples undergo identical procedure as the Std-V group except that it is done in air. For 530℃-V samples, Ti disks were heated at 530℃ for 40 minutes and slow cooled to room temperature. The 1000℃-V samples were produced by heating Std-V specimens again at 1000℃ for 2 hr, followed by cooling to room temperature. 530℃-A and 1000℃-A samples were also prepared. Potentiodynamic anodic polarization measurement, SEM, AFM and XRD analysis were performed to evaluate the effects of the various treatments. The difference in the mean values of E_corr between groups showed statistically significant difference (P<0.05), but that of I_corr did not show significance (P>0.05). When Ti surface was passivated there was a shift of corrosion potential (E_corr) in the noble direction and a lower corrosion current density (I_corr) value. Std-A samples showed most noble E_corr value among the tested groups. 530℃-V samples showed more noble E-corr than other tested groups except Std-A group. 1000℃-V samples showed more noble E-corr than those of Std-V sample. In the case of Std-, 530℃- and 1000℃-groups, -A sub-groups showed better corrosion resistant characteristics than -V sub-groups in regard to E-corr and I_corr values. In the SEM observations, the surfaces of the As-R samples showed only scratch line on smooth surface. In Pas samples, thick oxide layer covered the surface under high magnification observation. 530℃-A samples were covered by oxide granules, and Std-A samples had 25~50 nm-thick acicular oxides. The 1000℃-A samples were covered by coarse oxide crystals with a granule diameter of 0.1~0.6 μm having a gross appearance of milky white color, which was identified by XRD as a rutile. On the other hand, 1000℃-V samples showed an Widmansta¨tten structrue of which the orientation of the lattice is formed along crystallographic planes of the parent crystals. On the AFM observation, 530℃-A samples showed RMS roughness of 79.38 nm which is 5 times rougher than those of the As-R samples. Std-A sample had a roughness of 330.47 nm which is about 20-times rougher than that of the As-R sample. 1000℃-A samples were covered by coarse granular oxides and the roughness were about 0.56 μm. Vacuum sub-group samples showed a more smooth surface than air sub-group samples, and the oxide film was more dense. Due to variability of the surface treatment and heat treatment conditions, the process of the oxide formation seems to be affected thereby making the corrosion properties and surface micro-morphology different. However, more various electrochemical analysis together with surface analysis, and an investigation for the effects of those on the osteoblast cell adhesion and calcium phosphate apposition are needed for the improvement of the osseointegration rates of the titanium implants.

      • KCI등재후보

        중산간 농업용 만운저수지의 수질환경특성

        남귀숙,장정렬,이광식,윤경섭,이상준 한국환경농학회 2003 한국환경농학회지 Vol.22 No.1

        농촌지역의 도시화와 산업화에 따라 농촌 수질환경의 오염이 심화되고 있다. 경북 안동의 중산간지대에 위치한 만운저수지는 유역면적 23.8 km², 수표면적 0.4 km², 저수량 2.0×10^(6)m³의 부영양화 된 중규모 농업용저수지로서 1999년 수질환경특성조사를 실시하여 오염된 유사 농업용 저수지의 수질특성이해에 중요한 자료로 활용하고자 하였다. 만운저수지의 수질에 영향을 미치는 유역면적값(DA)/호수면적값(SA)의 비가 56.1로 국내 다른 농업용 저수지보다 높게 나타나 유역의 오염물질 부하가 높은 편이며, 평균 수심과 관련된 유효저수량(ST, m³)/수표면적(SA, m²) 비는 4.79로서 안동호, 팔당호보다 낮고 삽교담수호 등과 비슷한 값을 보여주어 부영양화의 잠재성이 높은 것으로 나타났다. 만운저수지의 수질조사결과 COD는 11.1 mg/L, 총질소 1.426 mg/L로 환경기준중 생활환경 Ⅳ등급인 농업용수 수질기준을 초과하였으며, 총인은 0.093 mg/L로 Ⅳ등급의 수질을 나타내고 있었다. 유입하천은 총질소(1.426~3.809 mg/L)가 비교적 높게 나타나고 있어 총질소에 기준한 수질개선 방안이 요구되었다. 식물성플랑크톤 조사결과 Oscillatoria와 근연종인 Lyngbya가 우점하였으며, 둥물성플랑크톤은 대부분의 지역에서 적조현상을 일으키는 와편모충인 Gynmodinium spp., 암색편모충인 Cryptomonas spp.이 우점하였다. 부영양화도지수(TSI)를 이용한 1999년도의 시기별 영양상태 변화는 9월에 과부영양상태를 보었으며, 연도별 TSI_(M)지수는 '96년, ‘97년에 부영양, '98년의 과영양으로 영양상태가 증가하였으나, 강우가 다소 많았던 '99년에는 강우의 영향으로 다소 개선되어 나타났다. 결론적으로, 저수지의 물리구조적 유역특성 및 수리학적 특성상 만운저수지는 부영양화에 취약한 특성을 가지고 있으며, 강우량에 영향을 받고는 있으나 전반적으로 부영양화도가 증가하는 추세를 보인다. 따라서, 이와 같은 추세변화를 정확히 인식하고 그에 적절한 대책을 마련하기 위해 농업용수 수질측정망 운영이 상당히 중요하게 인식되어지며, 수질환경 특성을 감안한 합리적 운영이 이루어져야 할 것으로 사료된다. Manun Reservoir, located in Andong district, has the capacity of 2 million tons in irrigation water supply with the drainage area of 23.8 km². Manua Reservoir is over fifty year old, and shallow in depth. The ratio of drainage area (DA) to reservoir surface area (SA) as an effective physical parameter on water quality was 56.1 and was higher than those of other agricultural reservoirs. The ratio of reservoir storage (ST) to SA in Manun Reservoir was 4.79, and the mean depth was below 8 m. Both ratios of DS/SA, total area (TA)/ST and ST/SA in Manua Reservoir were relatively higher than those in other agricultural reservoir and natural lakes in Korea. These physical parameters in Manun Reservoir, however, had a eutropic potential significance. Average of COD, TN, and TP in Manun Reservoir were 11.1 mg/L, 1.426 mg/L, 0.093 mg/L, respectively. In the inflow stream of Manun Reservoir, the TN (1.426~3.809 mg/L) was higher than those in reservoir. Only Lyngbya spp. was dominant in phytoplankton for this study period, and Gymnodinium spp., Peridinium spp., and Cryptomonas spp. were dominant in zooplankton. According to the Carlson's trophic status index, Manua Reservoir was eutrophic in 1996, 1997, and 1999, and hypertrophic in 1998.

      • SAN을 이용한 큐잉모델 해결방법

        장경수,신호진,이상호,김병기,신동렬 成均館大學校 科學技術硏究所 2000 論文集 Vol.51 No.2

        Queueing analysis, in general., has the intrinsic problem of large state space dimension and complex computation. In fact, the petri net is a graphical and mathematical model. It has been used for the modeling of various applications, in particular, manufacturing systems. It can deal with parallelism, concurrence, deadlock avoidance, and asynchronism. Currently it has been applied to the performance of computer networks and protocol verifications. This paper presents a technique for modeling and analyzing queueing model using stochastic activity networks (SANs). And then some examples are showed for the verification of the technique presented in this paper.

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