검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 647

        41.
        2021.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        (Bi1/2Na1/2)TiO3 (BNT)-based ceramics are considered promising candidates for actuator application owing to their excellent electromechanical strain properties However, to obtain large strain properties, there remain several issues such as thermal stability and high operating fields. Therefore, this study investigates a reduction of operating field in (0.98-x)Bi1/2Na1/ 2TiO3-0.02 BiAlO3-xSrTiO3 (BNT-2BA-100xST, x = 0.20, 0.21, 0.22, 0.23, and 0.24) via analyses of the microstructure, crystal structure, dielectric, polarization, ferroelectric and electromechanical strain properties. The average grain size of BNT-2BA- 100xST ceramics decreases with increasing ST content. Results of polarization and electromechanical strain properties indicate that a ferroelectric to relaxor state transition is induced by ST modification. As a consequence, a large electromechanical strain of 592 pm/V is obtained at a relatively low electric field of 4 kV/mm in 22 mol% ST-modified BNT-2BA ceramics. We believe that the materials synthesized in this study are promising candidates for actuator applications.
        4,000원
        42.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        취성특성을 가진 탄소섬유복합체의 인장특성을 결정하기 위해 ASTM D 3 0 39에 따라 인장시험을 실시하였다. 극한시 점에 박리, 부분파단으로 인해 스트레인 게이지의 계측값의 변동성이 커져 신뢰성을 확보하기 어렵기 때문에 극한응력과 탄성 계수를 이용한 유효극한변형률을 제안하고, 극한계측변형률과 상호보완하였다. 특히 게이지가 비정상적으로 작용할 경우에도 적용이 가능하다는 장점이 있다. 또한 유효극한변형률을 결정하는 탄성계수는 단일시편에서 여러 변형률 구간에 대하여 평가하여 비교 검증할 수 있다.
        4,000원
        44.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : Rut depth of asphalt pavements is a major factor that affects the maintenance of pavements as well as the safety of drivers. The purpose of this study was to analyze the factors influencing rut depth, using data collected periodically on national highways by the pavement management system and, consequently, predict annual rut depth change, to contribute to improved asphalt pavement management. METHODS : The factors expected to influence rut depth were determined by reviewing relevant literature, and collecting the related data. Further, the correlations between the annual rut depth change and the influencing factors were analyzed. Subsequently, the annual rut depth change model was developed by performing regression analysis using age, present rut depth, and annual average maximum temperature as independent variables. RESULTS : From the sensitivity analysis of the developed model, it was found that age affected the annual rut depth change the most. Additionally, the relationship between the dependent and independent variables was statistically significant. The model developed in this study could reasonably predict the change in the rut depth of the national highway asphalt pavements. CONCLUSIONS : In summary, it was verified that the model developed in this study could be used to predict the change in the National Highway Pavement Condition Index (NHPCI), which represents comprehensive conditions of national highway pavements. Development of other models that predict changes in surface distress as well as international roughness index is required to predict the change in NHPCI, as they are the independent variables of the NHPCI prediction model.
        4,000원
        45.
        2021.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        전통적으로 수술 변형이 있는 환자에서 소장내시경을 이용한 내시경역행담췌관조영술(ERCP)은 까다롭고 합병증이 높은 검사로 인식되었다. 그러나 최근 연구 결과들은 그렇게 속단할 수 없음을 보여주고 있다. 특히 다양한 소장내시경을 이용한 연구 성적들은 상당히 유망한 결과들을 보여주고 있다. 다양한 소장내시경 중 국내에서 긴 유형 단일 풍선 소장내시경이 ERCP에 가장 많이 사용되어 왔는데, 최근 짧은 유형 단일 풍선 소장내시경이 도입되어 사용 가능하게 되었다. 긴 유형과 짧은 유형 단일 풍선 소장내시경을 선택하기전에 크게 2가지 점을 고려할 필요가 있다. 첫째, 긴 유형과 짧은 유형 사이의 구체적인 차이점이 실제 ERCP에 어떤 영향을 미치냐는 점이다. 둘째, 두 유형의 단일 풍선 소장내시경을 이용한 임상 연구 결과들에 대한 올바른 접근이다. 결론으로 말하면 짧은 유형 단일 풍선 소장내시경은 ERCP가 필요한 대부분의 수술 변형 환자에서 가장 먼저 선택해 볼 수 있다.
        4,000원
        46.
        2021.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study wanted to optimize the radiator tank's deformation assembled on the automotive engine block. Among the experimental planning methods, the Taguchi method was used to find optimal molding conditions to minimize plastic covers' deformation. The four main factors used in the Taguchi method were selected as the main factors: resin temperature, pressure time, coolant temperature, and cooling time. The number of cycles for each factor was divided into five stages, and a total of 25 experiments were conducted. The experiment used the Moldflow program, an injection molding analysis program. The maximum deformation obtained under the existing molding conditions was about 1.318mm. Still, the deformation of the mold applied with the optimal molding conditions obtained using the Taguchi method was approximately 1.273mm, which showed that the maximum deformation was reduced by 3.4% compared to the existing molding conditions.
        4,000원
        50.
        2021.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Thermal external cracks can be initiated at the parting line, which is the dividing line that splits the core and cavity halves of a molded exhaust manifold-turbine housing. The fatigue cracks are often resulted from hot-cold cycle loads called by thermal shock cycles, and are accompanied by large plastic strains. This paper investigated the effects of parting lines of the integrated exhaust manifold-turbine housing and compared the magnitude of plastic strains directly correlated to low cycle fatigue damages or cracks. The finite element results showed that the plastic strains at runner junctions including parting line was calculated by 0.68%, which is approximately 60% higher than that of the turbine housing considering no parting line. So, if the analysis target is less than 0.50 % of plastic strain amplitude, the fatigue damages or cracks could be expected by considering the parting lines in integrated exhaust manifold-turbocharger.
        4,000원
        51.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        LNG makes cryogenic conditions, so metals without low-temperature brittleness must be used. The International Maritime Organization (IMO) defines 9% Nickel steel, STS304L, 36% Nickel steel and Al5083 as metals that can be used in cryogenic conditions through the IGC Code. In this study, Al5083-O was studied to minimize welding distortion, and verified through finite element analysis and experiments. The block dumping method, which is advantageous in terms of analysis time and cost, was used, not the continuous heat source method. The constraint models with the thickness direction and the tensile force model were compared with the reference model, it was confirmed that the tensile force model had no significant effect. After verifying through the experiment, it was confirmed that the trend of the finite element analysis model was consistent with the experiment. Through this study, a welding distortion minimization model could be found with the block dumping method. It is judged that simulation of many models through short time analysis will be of great help in the field.
        4,000원
        52.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, in order of to reflect the mold deformation in the injection molding process to design of mold, the mold deformation was analyzed by performing flow and structural analysis. The 5 inch LGP(light guide plate) mold, platen and tie bar were modeled and applied to the analysis. The result of melt pressure from flow analysis was extracted for use as boundary conditions acting on the mold surface in the structural analysis. In order to evaluate the accuracy of simulation analysis results, injection molding was performed under the process conditions of simulation. As a results, the mold deformation during injection molding tends to be similar that of injection pressure, and it is confirmed that it shows the behavior and properties of melt resins. Compared with the simulation and experiment, the error of the maximum mold deformation in the injection phase was 4.20%.
        4,600원
        53.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        1. 전 세계 GM작물 재배면적은 매년 꾸준히 증가하여 2018년에는 191.7백만 ha에 도달하였다. 26개국에서 GM작물이 재배되고 있으며, EU 포함 44개국에서 식품, 사료 및 가공용으로 승인하였다. 2. 국내 농업용 GM작물 승인 현황 조사 결과, 2015년에 GM작물이 가장 많이 승인되었으며, 농업적 형질은 제초제내성에 이어 해충저항성이 많았다. 단일품목과 후대교배종을 포함하여 옥수수가 가장 많이 승인된 작물이며, 후대교배종 승인은 꾸준히 증가하여 승인된 전체 GM작물의 57%를 차지한다. 3. 승인된 GM작물의 형질은 농업적 유용 형질에서 소비자 중심으로 변화되고 있다. 제초제내성과 해충저항성과 같은 1세대 GM작물은 생산비 절감이나 수량 증가 등으로 농민에게 경제적 이익을 제공하였으며, 2세대 GM작물은 소비자들에게 더 많은 혜택을 제공하는 기능성 강화나 산업용 특성을 증가시킨 것이 특징이다. 4. 향후 농업인과 소비자 모두에게 이익이 되는 연구개발과 실용화 추진을 위해 미래 대응 GM작물 개발과 형질 예측에 필요한 산업 성장 추세 정보를 제공하였다.
        4,000원
        58.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Animal orthopedic implants are an area that has recently been come into the light due to growing number of single-person households and increasing of interest in pets. The purpose of this study was to investigate a method to design and manufacture a bushing in a desired direction and angle with the environment of use, while the bone joint plate could be stably deformed during animal fracture surgery. It was found that the bone joint plate was capable of deformation in all directions and was designed to be transformed to the desired angle without degrading the basic properties of bending strength. Also, it was found that the bushing-type bone joint plate could be controlled in multiple directions and angle at omni-directional movements(0°-360°) and 0°-10° moving forward, backward and side to side.
        4,000원
        59.
        2020.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This study deals with the yielding behavior and strain aging properties of three bake hardening steels with dualphase microstructure, fabricated by varying the annealing temperature. Bake hardening and aging tests are performed to examine the correlation of martensite volume fraction with yielding behavior and strain aging properties of the bake hardening steels with dual-phase microstructure. The volume fraction of martensite increases with increasing annealing temperature. Roomtemperature tensile test results show that the yielding behavior changes from discontinuous-type to continuous-type with increasing volume fraction of martensite due to higher mobile dislocation density. According to the bake hardening and aging tests, the specimen with the highest fraction of martensite exhibited high bake hardening with low aging index because solute carbon atoms in ferrite and martensite effectively diffuse to dislocations during the bake hardening test, while in the aging test they diffuse at only ferrite due to lower aging temperature.
        4,000원
        60.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        목적 : 도수와 안경테의 다른 변수의 변화가 없는데 새로운 안경을 착용하였을 때 불편함을 느끼는 사람을 대상 으로 안경테와 렌즈에 따른 변수를 분류하여 왜곡정도, 커브변화, 어지러움에 미치는 영행을 알아보고자 하였다. 방법 : 도수와 안경의 변수의 변화가 없고 안과적 질환 및 다른 질환이 없는 성인남녀 103명(남자55명 여자48 명) 206안을 대상으로 안경테(재질, 모양, 가공방식)와 안경렌즈별(굴절률, 설계방식, 코팅종류)로 변수를 분석하여 그 변수들이 렌즈의 왜곡정도, 커브변화, 어지러움증에 미치는 영향을 측정하였다. 결과 : 렌즈에 따른 분류에서는 굴절률, 코팅방식에서 왜곡정도, 커브변화, 어지러움의 차이가 있는 것을 확인하 였다. 안경테에 따른 분류에 재질, 안경테의 모양, 가공방식에서 왜곡정도, 커브변화, 어지러움의 차이가 있는 것을 확인하였다. 왜곡정도, 커브변화, 어지러움의 상관분석 결과 어지러움은 상관분석 결과 안경이 왜곡정도 심하면 심할 수록 커브변화가 더 커지는 것을 확인하였고 안경의 왜곡정도가 심하면 심할수록 어지러움 정도가 더 심해지는 것을 확인하였으며. 어지러움은 상관분석 결과 안경의 커브변화가 클수록 어지러움 정도가 더 심해지는 것을 확인하였다. 결론 : 본 연구 결과 사용된 안경테와 렌즈에 따라 왜곡정도, 커브변화, 어지러움에 대한 차이가 나타났다. 따 라서 이를 고려한 안경테와 렌즈의 선택과 그에 맞는 가공이 필요하다고 사료된다.
        4,000원
        1 2 3 4 5