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        검색결과 11

        1.
        2024.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the case of the Pohang earthquake, which had a magnitude of 5.4 in 2017, geotechnical damages such as liquefaction and ground settlement occurred. The need for countermeasures has emerged, and experimental research in the Pohang area has continued. This study collected undisturbed samples from damaged fine-grained soil areas where ground settlement occurred in Pohang. Cyclic tri-axial tests for identifying the dynamic characteristics of soils were performed on the undisturbed samples, and the results were analyzed to determine the cause of ground settlement. As a result of the study, it was determined that in the case of fine-grained soils, ground settlement occurred because the seismic load as an external force was relatively more significant than the shear resistance of the very soft fine-grained soils, rather than due to an increase in excess pore water pressure.
        4,000원
        2.
        2017.12 구독 인증기관 무료, 개인회원 유료
        The use of radar-based systems for vessel monitoring is not suitable in populated areas, due to the high electromagnetic emissions. In this paper, a camera based vessel recognition system for application in the context of Vessel Traffic Services (VTS) and Homeland Protection (HP) is proposed. Our approach is designed to extend the functionality of traditional VTS systems by permitting the classification of both cooperative and non-cooperative targets, using camera images only. This allows enhancing the surveillance function in populated areas, where public opinion is strongly concerned about electromagnetic emissions and therefore antennas are suspiciously observed and radars are not allowed. Experiments have been carried out on a publicly available data set of images coming from the ARGOS boat traffic monitoring system in the City of Venice (Italy). The obtained classification accuracy of 89.6% (with 11 different classes of boats) demonstrates the effectiveness of the proposed approach.
        4,000원
        3.
        2010.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Mo nanopowder was synthesized by ball-milling and subsequent hydrogen-reduction of powder. To fabricate ultra fine grained molybdenum, two-step sintering and spark plasma sintering process were employed. The grain size of specimen by two-step sintering and spark plasma sintering was around and , respectively. Mechanical properties of ultra fine grained Mo with relative density of above 90% were significantly improved at room and high temperatures comparing to commercial bulk Mo of 99% relative density. This result was mainly explained by the grain size refinement due to diffusion-controlled sintering.
        4,000원
        5.
        2006.09 구독 인증기관·개인회원 무료
        In recent years, PCB drills with smaller diameters less than 0.1 mm are used and thus there are growing needs for ultra-fine grained cemented carbides. However, ultra-fine WC powder usually causes extraordinary grain growth during sintering which weakens mechanical strength of ultra-fine grained cemented carbides. So we examined several kinds of WC powders to make new ultra-fine grained cemented carbides having superior performance. We found that direct carburized WC powder is very good as a WC raw material. The PCB drills made of the developed ultra-fine grained cemented carbides have higher hardness, toughness and stiffness than conventional ones.
        6.
        2006.09 구독 인증기관·개인회원 무료
        Ultra-fine grained and dispersion-strengthened titanium materials (Ti-Si, Ti-C, Ti-Si-C) have been produced by high energy ball milling and spark plasma sintering (SPS). Silicon or/and carbon were milled together with the titanium powder to form nanometer-sized and homogeneously distributed titanium silicides or/and carbides as dispersoids, that should prevent grain coarsening during the SPS compaction and contribute to strengthening of the material. The microstructures and the mechanical properties showed that strength, hardness and wear resistance of the sintered materials have been significantly improved by the mechanisms of grain refinement and dispersion strengthening. The use of an organic fluid as carrier of the dispersoid forming elements caused a significant increase in ductility.
        7.
        2006.09 구독 인증기관·개인회원 무료
        The new alloy1) is made from rapidly solidified Al-Ni-Zr-Ce aluminum alloy powder, and has the following unique mechanical characteristics:(1) The stress-strain curve shows a yield point; (2) The alloy shows high heat resistance; (3) Although the alloy is submicron particle diameter, it shows excellent creep resistance. We observed the micro structures of this new alloy, and it is thought that is based on the following reasons:(1) The dislocation strongly adheres to the alloy’s many crystal boundaries;(2) The added alloying elements have a small diffusion coefficient in aluminum;(3) The tiny intermetallic compound particles crystallizing at the grain boundary.
        8.
        2020.09 KCI 등재 서비스 종료(열람 제한)
        This paper investigates three types of dative-marking causative verbs in Korean: caused motion verbs, adversative passive verbs, and periphrastic causative verbs that unmarkedly select for dativeparticled NP. Caused motion verbs arguably entertain lexically-introduced causative features, adversative passives involve lexico-syntactically oriented causative and passive morpheme(s), periphrastic causative verbs involve a syntactically active causative component. We examined the processing aspects of these three types of verbs, adopting the event-related potential (ERP) paradigm of superior temporal resolution. We crucially employed the dative/ ACC alternation well-known in Korean syntax to come up with the potentially anomalous or marked experimental conditions. The results are: motion verbs and adversative passive verbs with ACC NP, relative to ones with DAT NP, recorded the bi-phasic ERP components: N400 and reduced P600. On the other hand, periphrastic causative verbs with ACC NP, compared to ones with DAT NP, registered only reduced P600. Taken together, only the syntactically-active causative component licences the ACC Case on the NP whose dative particle is dropped. Motion verbs and adversative passive verbs are taken to fail to complete semantic integration with the preceding ACC NP, therefore attempting to undergo syntactic reanalysis.
        9.
        2009.09 KCI 등재 서비스 종료(열람 제한)
        현재 국내에서 생석회 제조 용도로 사용되는 세립질 석회석을 대상으로 이들의 소성 특성을 규제하는 원광의 응용광물학적 세부 영향 요인들의 관여 정도를 평가함으로써, 생석회 제조 과정에서 원광 선택의 중요성을 고취시키고자 하였다. 이를 위해서 원광의 조성 및 조직적 특성과 동일한 가열처리 조건(온도: 1000℃ 시간: 30분, 2, 4, 10, 16 시간) 하에서 합성된 소성 산물들의 품질 특성을 체계적으로 분석 및 계측하고 그 결과를 비교 검토 하였다. 선정된 광석들은 모두 방해석 품위가 98 wt%를 상회하는 고품위 석회석이지만 결정도, 조직 및 불순물의 조성에 있어서 다소간의 차이를 나타낸다. 이 같은 원광 특성상의 차이에 따라 합성된 생석회는 다양한 품질 특성을 보인다. 석회석이 산출되는 암층별로는 풍촌층 석회석이 상대적으로 매우 낮은 소성율을 나타내는 것이 특징이고, 갑산층과 정선층 석회석은 소성율과 분화율에 있어서 좋은 품질 특성을 보였다. 소성율과 소결 정도 및 분화율 등에 있어서 전반적으로 정선층에서 산출된 석회석이 고반응성 생석회의 원료로서 가장 적합한 것으로 평가되었다. 또한 소결 현상은 상대적으로 황철석 및 침철석과 같은 함철광물의 함량이 높은 갑산층 석회석에서 보다 두드러지게 나타나는 것이 특징이다.
        10.
        2009.03 KCI 등재 서비스 종료(열람 제한)
        제주도 동남부 신산리 해안가에 분포하는 현무암에 세립질의 맨틀 페리도타이트가 드물게 포획되어 있으며, 반상쇄정 잔류물의 거정질 입자와 세립질의 입자로 구성된 조직적 특성에 의해 반상쇄정의 페리도타이트 맨틀포획암(FPP)으로 정의된다. 조사되어진 FPP들의 서로 유사한 조직적 특성과 주성분원소 조성은 FPP가 하나의 구조 영역에서 유래했음을 지시한다. 또한 킹크밴드를 가지는 거정의 반상쇄정(2~3mm) 사이에 변형의 흔적이 없는 세립질의 입자(200~300μm)로 구성된 쌍봉분포, 삼중점과 직선형의 입자경계, 간극사이에 형성된 멜트포켓, 입자경계가 이동했음을 나타내는 미세구조 등은 FPP가 동력재결정작용 ± 정적재결정작용을 경험하였음을 반영하고 있다. 이러한 변형사건에는 멜트/유체의 이동이 있었으며, 특히 엽리면을 따라 일어났다. 신산리 지역에 가장 흔하게 산출되는 프로토그라뉼라 조직의 맨틀포획암과 FPP는 매우 유사한 주성분원소 조성을 보이는데, 이는 FPP가 프로토그라뉼라 조직의 포획암과 비슷한 상부맨틀 깊이에 위치하고 있었음을 나타낸다. 이러한 FPP의 조직적 특성과 주성분원소 조성은 FPP가 지엽적인 소규모의 좁은 영역에 관여한 변형사건을 경험하였음을 나타낸다. 이 변형사건의 실체에 대한 것은 앞으로 좀 더 연구가 진행되어야 할 것이나, 제주도가 만들어지기 이전의 상부맨틀 암석권에서 마그마의 상승과 관련된 단층작용에 의해 형성되었을 가능성을 제시한다.
        11.
        2007.05 KCI 등재 서비스 종료(열람 제한)
        The content and distribution of some heavy metals (Fe, Mn, Cr, Co, Cu, Ni, Zn and Pb) were investigated in the <63 ㎛ bed sediments of the Mangyeong river to recognize the extent of contamination. Results showed that a wide range of concentrations was apparent for every metal. These variations were particularly significant at the confluence of tributaries. High levels of metals occur mainly in the confluence of tributaries. Geoaccumulation indexes have been calculated to assess whether the concentration observed represent background or contaminated levels. It is proved that the Mangyeong River is moderately to strongly polluted for Mn, Cr, Cu, Zn and Pb. The spatial extent of pollution was examined, and it was found that the most polluted area is located in the confluence of Iksan and Jeonju tributaries.