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        검색결과 540

        202.
        2013.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Active front steering(AFS) system is able not only to vary steering ratio between steering wheel and tire wheel but also to steer front tires independently. In this paper, steering gear ratios and an active steering algorithm are proposed for the AFS system. Steering gear ratio is a function of vehicle speed and steering angle. Active steering is generated when the error of yaw-rate is larger than some threshold. To verify the performance of yaw stability, hardware-in-the-loop simulation system is made up of column type active steering system, driving display, steering effort reaction system and controller
        4,000원
        203.
        2013.04 구독 인증기관·개인회원 무료
        204.
        2013.04 구독 인증기관·개인회원 무료
        205.
        2013.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 풍진동 제어를 위해 39층 테크노마트 건물에 능동형 질량 감쇠기를 적용하기 위한 수치해석적 연구를 수행하였다. 먼저, 태풍 풍응답 계측 및 풍동실험을 통해 테크노마트 단변방향 진동에 대한 사용성 개선이 필요함을 확인하였다. AMD에 요구되는 스트로크 확보를 위한 건물의 여유 공간, 설치 위치, 허용 무게 등을 알아보고 제진장치 배치 및 사양을 결정하였다. 그리고 테크노마트의 최상거주층인 39층 단변방향을 대상으로 한 1자유도 해석모델에 대해 선형제어방법인 속도피드백, LQR, LQG 알고리즘과 비선형제어방법인 Bnag-bang 알고리즘을 적용하는 해석연구를 수행하였다. 해석결과 제어 전·후의 최대가속도는 11.83cm/s2에서 4.19cm/s2으로, 진동감지확률은 90%에서 50%이하로 감소하여 Bang-bang 제어알고리즘을 적용할 경우 제어성능이 가장 좋은 것을 확인하였으며 각각의 알고리즘으로 구현된 AMD의 최대 스트로크가 모두 허용범위 수준을 만족하는 결과가 나왔다. 또한, 실제 AMD의 안정적은 작동을 위해 요구되는 원점보정 신호 방안을 제안하여, 제한된 스트로크 내에서 제진장치를 안정적으로 운행할 수 있음을 확인 하였다.
        4,200원
        206.
        2012.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present a test of the emission statistics of active galactic nuclei (AGN), probing the connection between red-noise temporal power spectra and multi-modal flux distributions known from observations. We simulate AGN lightcurves under the assumption of uniform stochastic emission processes for different power-law indices of their power spectra. For sufficiently shallow slopes (power-law indices β≤ 1), the flux distributions (histograms) of the resulting lightcurves are approximately Gaussian. For indices corresponding to steeper slopes (β≥ 1), the flux distributions become multi-modal. This finding disagrees systematically with results of recent mm/radio observations. Accordingly, we conclude that the emission from AGN does not necessarily originate from uniform stochastic processes even if their power spectra suggest this. Possible mechanisms are transitions between different activity states and/or the presence of multiple, spatially disconnected, emission regions.
        4,000원
        207.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        2차원적 이미지에 생동감 있는 3-D 깊이감을 구현하기 위한 노력은 입체 지각에 대한 이론적 이해 및 그에 따른 기술적 발전과 더불어 오래 동안 지속되어 왔다. 본 논문에서는 입체경을 사용한 입체시 구현 원리에 기반을 둔 대중적인 입체경들을 간략히 개괄하고, 이들 중 액티브 셔터 방식의 입체경이 사용된 시각기억 실험 사례를 소개하였다. 실험에 참가한 피험자들은 자극들의 지각된 깊이를 기억하였으며, 이에 대한 기억 정확도가 측정되었다. 기억 및 검사를 위한 항목들의 깊이감은 1) 단안, 2) 양안 그리고 3) 단안과 양안 단서가 사용된 조건으로 각기 달리 처치되어 구분되었다. 참가자들의 기억 수행은 양안단서만이 처치된 조건에서 가장 낮았던 반면, 양안단서와 단안단서가 동시에 구현되었을 때 가장 높았다. 이러한 결과는 시각기억이 깊이 정보를 저장할 때, 양안단서를 통해 구현된 정보보다 단안 단서를 통해 구현된 정보를 더 효율적으로 저장하며, 양안단서와 단안단서가 동시에 사용되었을 때 가장 효과적인 기억 수행이 가능함을 시사한다.
        4,300원
        208.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        For an effective energy management in intelligent buildings it is necessary to gather information about position/absence of people and the level of population. In this paper the smart occupancy detection system using the active RFID is developed to satisfy such a demand based on the results of previous research. First of all the design considerations and functions of the system are introduced. In sequence the functions of the system is presented, and then the performance of the developed system is tested and verified through various field tests. The developed core technology can be also applied to other fields such as security, healthcare, smart home, etc.
        4,000원
        209.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This research was planned and executed to evaluate how the composition of Yack-sun (oriental diet therapy) tea can effect the health conditions of people who are suffering from diet-related diseases such as being overweight, obese and hyperlipidemic, by taking Yack-sun tea in a form of nutritional supplement with daily meals. We produced Kangjieum with Lycense Mill., Polygonum multflorum Thunb, Cassia tora L., Crataegus pinnatifida Bge and Salvia miltiorrhiza Bge. We evaluated the effects of this tea on serum lipids, on homocysteine concentration, and on active oxygen contents, oxidative stress by clinical practices. We have determined that this tea has a significant effect on decreasing body fat content, decreasing total cholesterol, decreasing LDL-cholesterol, and decreses triglyceride and homocysteine concentrations. In addition, blood active oxygen content and oxidative stress were significantly decreased. We think that scientific and objective evaluation was performed on the components of Kangjieum prescription. We concluded that we could apply the components, not only in a form of tea, but also in other forms of various foods. The information we received from this conclusion will be basic information on how we can apply oriental medicinal resources into other food and will be a steppingstone for medicinal herbs to place a foot in the field of functional food research, which already draws sizable attention world-wide.
        4,000원
        210.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The researches related to active control systems utilizing superelastic shape memory alloys (SMA) have been recently conducted to reduce critical damage due to lateral deformation after severe earthquakes. Although Superelastic SMAs undergo considerable inelastic deformation, they can return to original conditions without heat treatment only after stress removal. We can expect the mitigation of residual deformation owing to inherent recentering characteristics when these smart materials are installed at the part where large deformation is likely to occur. Therefore, the primary purpose of this research is to develop concentrically braced frames (CBFs) with superelastic SMA bracing systems and to evaluate the seismic performance of such frame structures. In order to investigate the inter-story drift response of CBF structures, 3- and 6-story buildings were design according to current design specifications, and then nonlinear time-history analyses were performed on numerical 2D frame models. Based on the numerical analysis results, it can be comparatively verified that the CBFs with superelastic SMA bracing systems have more structural advantages in terms of energy dissipation and recentering behavior than those with conventional steel bracing systems.
        4,300원
        211.
        2012.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to identify the effects of tensor fasciae latae-iliotibial band (TFL-ITB) self-stretching exercise on the lumbopelvic movement patterns during active prone hip lateral rotation (HLR) in subjects with lumbar extension rotation syndrome accompanying TFL-ITB shortness. Eleven subjects (9 male and 2 female) were recruited for the two-week study. A three dimensional ultrasonic motion analysis system was used to measure the lumbopelvic movement patterns. The TFL-ITB length was measured using the modified Ober's test and was expressed as the hip horizontal adduction angle. The subjects were instructed how to perform TFL-ITB self-stretching exercise program at home. A paired t-test was performed to determine the significant difference in the angle of lumbopelvic rotation, movement onset time of lumbopelvic rotation, TFL-ITB length, and LBP intensity before and after the two-week period of performing the TFL-ITB self-stretching exercise. The results showed that after the intervention, the lumbopelvic rotation angle decreased significantly (p<.05), the movement onset time reduced significantly (p<.05), and LBP intensity decreased slightly but not significantly (p=.07). The hip horizontal adduction angle increased significantly (p<.05) after the intervention. These findings indicate that TFL-ITB stretching exercise increased TFL-ITB length, decreased lumbopelvic rotation angle, and delayed the movement onset time of lumbopelvic rotation after two-weeks. In conclusion, the TFL-ITB self-stretching exercise performed over a period of two weeks may be an effective approach for patients with lumbar extension rotation syndrome accompanying TFL-ITB shortness.
        4,000원
        212.
        2012.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Few studies address the use of manual muscle stretching to improve spinal active range of motion(AROM). There is evidence that‘ Hold-Relax’(HR) is effective for increasing ROM in the extremities, which leads the researchers to anticipate similar benefits in the spine. The purpose of this study is to investigate the effects of HR(trunk flexors) and active thoracic flexion and extension on thoracic mobility, specifically flexion and extension in healthy individuals. A convenience sample of 30 physical therapy students(22-38 years) were randomly assigned to intervention sequence ‘A-B’ or ‘B-A’, with at least 7 days between interventions. Intervention‘ A’ consisted of HR of the ventral trunk musculature while ‘B’ consisted of thoracic flexionextension AROM. Thoracic flexion and extension AROM were measured before and after each intervention using the double inclinometer method. Paired t-tests were used to compare AROM pre and post-intervention for both groups, and to test for carry-over and learning effects. There was a statistically significant increase(mean=3° ; p=0.006) in thoracic extension following HR of the trunk flexors. There were no significant changes in thoracic flexion following HR, or in flexion or extension following the AROM intervention. No carryover or learning effects were identified. HR may be an effective tool for improving AROM in the thoracic spine in pain free individuals. Further investigation is warranted with symptomatic populations and to define the minimal clinical difference(MCD) for thoracic spine mobility.
        4,000원
        214.
        2012.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We investigate the mid-infrared (MIR) to far-infrared (FIR) properties of a nearly complete sample of local active galactic nuclei (AGNs) detected in the Swift/Burst Alert telescope (BAT) all-sky hard X-ray (14-195 keV) survey, based on the cross correlation with the infrared survey catalogs of AKARI, IRAS and WISE. Out of 135 non-blazar AGNs in the Swift/BAT 9-month catalog, we obtain the MIR photometric data for 128 sources in either the 9, 12, 18, 22, and $25{\mu}m$ band. We find a good correlation between their hard X-ray and MIR luminosities ranging three orders of magnitude (42 < log λLλ(9,18 μm ) < 45), which is tighter than that with the FIR luminosities at 90 μm . Both X-ray unabsorbed and absorbed AGNs follow the same correlation, implying isotropic infrared emission, as expected in clumpy dust tori models rather than homogeneous ones.
        4,000원
        215.
        2012.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Many observations have found evidence of the presence of a large number of heavily obscured Active Galactic Nuclei (AGNs). However, the nature of this population is only poorly understood because heavy obscuration by dust prevents one from finding them at optical wavelengths. Mid-infrared AGN searches can overcome this obstacle by penetrating through dust and by detecting direct emission from the dust torus. Thus, we can identify most of the AGN population, including type-2 and buried AGNs. Using the AKARI mid-infrared all-sky survey, we performed an AGN search in the nearby universe. Utilizing the 2MASS photometry, we selected mid-infrared-excess sources and carried out near-infrared spectroscopic observations in the AKARI Phase 3. During these follow-up observations, we have found three galaxies that show strong near-infrared red continuum from hot dust with a temperature of about 500 K, but do not show any AGN features in other wavelengths. The most suitable explanation of near-infrared continuum is the presence of central AGNs. Therefore, we conclude that they are AGNs obscured by dust. We performed X-ray observations of the two galaxies with SUZAKU. No detections in the 0.4-10 keV suggest that the column density may be much higher than NH=1023.5cm−2 . Comparing the masses of the host galaxies with those of the SDSS AGNs, we find that the host galaxies of the dusty AGNs discovered with AKARI are less massive populations than those of optically selected AGNs.
        4,000원
        216.
        2012.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 논문에서는 구조물과 능동형 제진장치를 상용 구조해석 프로그램상에서 해석하는데 필요한 등가모델을 제시하였으 며, 이를 통해 부재수준의 구조검토가 가능하도록 하기 위한 연구를 진행하였다. 능동형 제진장치를 일반적인 구조해석모 델에 반영하기 위하여 가상의 스프링과 대쉬폿을 이용한 등가링크 모델과, 별도의 축소모델 해석결과를 바탕으로 산정된 제어력을 제진장치 설치위치에 하중으로 작용시키는 등가하중 모델을 제시하였다. 수직캔틸레버 모델과 주상복합 건물 모 델을 대상으로 능동형 제어기 설계를 위해 모드에 기초한 축소모델을 구축하고, 이를 토대로 산정된 제어이득으로부터 등 가모델을 도출하였다. 이들 모델에 대해 얻어진 가속도 및 변위의 RMS 응답과 최대 부재력을 토대로 등가해석모델의 유 효성을 검증하였다. 결과적으로 능동형 제진장치의 상용 구조해석 프로그램을 통해 제어대상 구조물의 부재력 수준까지 상 세한 구조검토가 가능함을 확인하였으며, 상대적으로 등가링크 모델이 더 우수한 정확도를 나타내었다.
        4,000원
        217.
        2012.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to investigate the effects of different active gluten and rice Nuruk(Asp. oryzae, Asp. kawachii rice Nuruk) levels on the quality properties of steamed rice breads. Enzyme(amylase and acidic protease) activity of Asp. oryzae rice Nuruk is higher than Asp. kawachii rice Nuruk. Among the loaf volume of active gluten that were tested (10, 13, 15 and 17%) an active gluten loaf volume of 15% produced the best steamed rice bread. As a result of the loaf volume test steamed rice bread with rice Nuruk was decreased than steamed wheat bread. Regarding color, all treatments produced significant differences. The L value was decreased in steamed rice bread more than in steamed wheat bread, and a and b values were increased, respectively. Hardness, gumminess and chewiness of SRB-2, 3, 4 were lower than SWB-1 but springiness were higher. According to the sensory evaluation of steamed rice bread, color, flavor, and uniformity of pores were the highest in the steamed wheat bread, and the chewiness and texture were good in the steamed rice bread containing added active gluten and rice Nuruk. In this study, addition of rice Nuruk in steamed rice bread did not increase loaf volume, but had an advantage for overall desirability.
        4,000원
        218.
        2012.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The quarter car test rig is designed and constructed for testing the performance of a vehicle active suspension system. The performance of the optimal variable structure controller is tested to compare with those of a passive suspension system and the simulation result. The dynamic characteristics of the PCV(pressure control valve) is tested, and based on this result, the lead compensator is designed for reducing the dynamic effects of the PCV. The performance of an active suspension system with the compensator gives almost that of an ideal active suspension system. From the frequency response analysis of which input is a white noise, the active suspension system shows the better performance than a passive suspension system around 1Hz which is the natural frequency of the sprung mass.
        4,000원
        220.
        2012.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 실험에서는 초임계 추출법을 이용하여 탈지미강으로부터 얻은 주요한 표면활성 물질 분획(3 fractions: 1-HS, 6-HS 및 18-HS)의 유화성질을 평가하였다. 유화성질의 평가는 표면활성분획을 이용하여 유화액을 제조한 후 이들의 여러 가지 물리화학적 성질(지방구 크기 및 변화, 크리밍 안정도, oil-off, 분산안정성 등)을 조사하였다. 그 결과 각 추출 분획을 이용하여 제조한 유화액은 서로 다른 물리화학적 특성을 나타내었는데, 그중 가장 작은 지방구 크기 특성을 나타낸 1-HS 유화액이 크리밍안정도, oil-off 및 분산안정성 측면에서 우수한 것으로 평가되었다. 또한 1-HS 추출물의 유화 기능성을 보강하기 위한 co-surfactant 검토 결과, GMS(glyceryl monostearate)를 추가적으로 첨가할 경우 1-HS 유화액의 지방구 크기가 현저하게 작아지는 것을 확인할 수 있었고, 적절한 첨가 농도는 0.05% 이상으로 확인되었다. 결론적으로 본 연구를 통하여 미강 추출물의 우수한 표면활성능을 확인할 수 있었으며, 이 천연의 표면활성물질은 초임계추출법을 이용하면 성공적으로 분리할 수 있는데, 향후 식품유화산업에서 이용될 수 있을 것으로 기대된다. 본 연구와 관련하여 다음의 실험 목표는 이 물질의 구성 성분분석 및 상업화 연구이다.
        4,000원