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        검색결과 426

        301.
        2018.04 KCI 등재 서비스 종료(열람 제한)
        Background: To obtain useful cosmetic resources, this study aimed to determine the non-saponin fatty acid and inhibitory activities of collagenase and elastase by treatment of Saccharomyces cerevisiae in supercritical fluid extracted oil of the adventitious root culture of wild mountain ginseng. Methods and Results: We performed supercritical fluid extraction at various conditions such as pressure, temperature, time, and use of co-solvents, unlike the n-hexane extraction for the adventitious roots culture of wild mountain ginseng. The non-saponin-fatty acid obtained from the oil of the adventitious roots culture was incresed by treatment with S. cerevisiae. The supercritical fluid extraction was conducted using gas chromatography. Non-saponin-fatty acid content, in the oil of adventitious roots culture of wild mountain ginseng treated with S. cerevisiae for 2 days were three times higher than that in the control. In addition, the oil of the adventitious roots culture treated with S. cerevisiae was investigated for the anti-wrinkle effect by using collagenase and elastase. The oil of adventitious roots culture treated with S. cerevisiae exhibited higher collagenase and elastase inhibitory activities than those in the control. Conclusions: Supercritical fluid extracted oil of the adventitious roots culture of wild mountain ginseng treated with S. cerevisiae was found to have decreased ratio of saturated fatty acids and incresed ratio and content of unsaturated fatty acids increased. Furthermore, it showed anti-wrinkle effects in vitro.
        302.
        2018.03 KCI 등재 서비스 종료(열람 제한)
        이 연구는 학생의 이주배경과 지역사회의 이주민 밀집도에 따른 교육격차를 살펴보기 위한 것이다. 사회해체이론(social disorganization theory) 관점에서 지역사회의 이주민 밀집도가 학생의 교육경험에 부정적 주변효과(neighborhood effect)로 작용할 개연성을 검토하고, 그 효과가 학생의 이주배경에 따라 차이를 보이는지 살펴보고자 하였다. 이를 위해 서울과 경기지역 1,472명의 학생 조사 자료에 지역사회 변수들을 통합하여 학업성취도의 편차를 분석하였다. 분석 결과, 지역의 이주민 밀집도가 높을수록 뚜렷한 학력저하 현상이 발견되었다. 또한 이러한 부적 관계는 이주배경 학생에 비해 비이주배경 학생에게서 더욱 뚜렷하게 나타났다. 이는 이주민 밀집도의 부정적 주변효과에 더 크게 영향을 받는 집단이 이주배경 학생이라기보다 오히려 비이주배경 학생임을 의미한다. 이에 따라 다문화정책 추진 과정에서 이주민 밀집지역 내 비이주배경 학생의 교육적 취약성은 상대적으로 간과되고 있다는 문제점을 제기할 수 있다.
        303.
        2017.12 KCI 등재 서비스 종료(열람 제한)
        The minimum reinforcement ratio is an important design factor to prevent a brittle failure in RC flexural members. A minimum reinforcement ratio is presented by assuming an effective depth of cross-section and moment arm lever in CDC and KHBDC. In this study, it suggests that a rational method for minimum reinforcement ratio is calculated by material model and force equilibrium. As results, a minimum reinforcement ratio using a p-r curve in KHBDC is evaluated about 52~80% of recent design code’s value and it induces an economical design. And also, a ductility capacity in case of placing this minimum reinforcement amount is evaluated about 89% of recent design code’s value, but ductility in a member is 7 or more, so it has a sufficient ductility capacity. Therefore, it is judged that a minimum reinforcement ratio using p-r curve has a theoretical rationality, safety and economy in a flexural member design.
        304.
        2017.12 KCI 등재 서비스 종료(열람 제한)
        Spiral reinforcement in a circular column plays an effective role in the ductile behavior of a column through position fixing and buckling restraining of the longitudinal reinforcement, and confining core-concrete. Each country has suggested the minimum volumetric ratio of spiral reinforcement in order to secure the ductility of concrete columns. The minimum volumetric ratio of spiral reinforcement suggested by ACI 318-14 and the national concrete structure design standard was developed based on the theory of Richard et al. (1928); furthermore it has been used until now. However, their theory cannot consider the effects of high strength concrete and high strength reinforcement, and arrangement condition of the spiral reinforcement. In this study, a modified minimum volumetric ratio equation is suggested, which is required to improve the ductility of reinforced concrete circular columns and to recover their stress. The modified minimum volumetric ratio equation suggested here considers the effect of the compressive strength of concrete, the yield strength of spiral reinforcement, the cross sectional area of columns, the pitch of spiral reinforcements and the diameter of spiral reinforcement. In this paper, the validity of the minimum volumetric ratios from ACI 318-14 and this study was investigated and compared based on the results of uniaxial compression experiment for specimens in which the material strength and the spiral reinforcements ratio were used as variables. In the end of the study, the modification method for the suggested equation was examined.
        305.
        2017.10 KCI 등재 서비스 종료(열람 제한)
        ABA는 식물에서 비 생물학적 스트레스 내성에 관여하는 중 요한 식물 호르몬이다. 애기장대의 group A bZIP 전사인자는 ABA 신호전달 과정에 중요한 역할을 한다고 알려져 있다. 그러나 벼에서는 group A bZIP 전사인자의 기능이 잘 알려져 있지 않다. 따라서 우리는 벼에서 group A bZIP 전사인자인 OsABF3 (Oryza sativa ABA responsive element binding factor 3)를 연 구하였다. 이를 위해 벼의 다양한 조직과 다양한 스트레스(가 뭄, 염분, 저온, ABA, 산화 스트레스)에 따른 OsABF3 발현 패턴을 분석하였다. 또한 maize의 원형질체에서 GFP fusion 벡터를 사용한 세포 내 위치 분석을 통해 OsABF3가 핵단백질이라는 것을 확인하였다. Yeast one-hybrid 실험을 통해 OsABF3의 Cterminal 부분이 ABREs에 결합한다는 것과 N-terminal 부분 이 하위 유전자의 transactivation 하는데 필요하다는 것을 알수 있었다. 그리고 T-DNA가 삽입된 OsABF3의 homozygous 돌연변이체가 야생형과 과발현체에 비해 발아와 발아 후 단계 에서 고농도의 ABA에 대한 민감도가 더 감소한 것을 알 수 있었다. 결과적으로 종합해 볼 때 OsABF3는 ABA의 의존적인 경로를 통해 비 생물학적 스트레스에 반응하는 유전자의 발현을 조절하는 기능을 하는 전사 조절자이다. 또한 OsABF3의 transactivation을 측정하는 실험에 있어서 억제 domain이 존 재한다는 결과를 얻었다.
        306.
        2017.09 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        The purpose of this study was to examine the effects of long-term endurance exercise and Salvia miltiorrhiza vinegar on body composition and insulin resistance of high-fat diet (30% carbohydrate, 50% fat and 20% protein) induced obese rats. After 8 weeks of high fat diet (50% of total calories), rats were divided into 4 groups (sedentary group, n=10; exercise group, n=10; Salvia miltiorrhiza vinegar group, n=10; exercise+Salvia miltiorrhiza vinegar group, n=10) for 8 weeks. Body weight, body composition, diet intake volume, oral glucose tolerance test, plasma total cholesterol were measured. The results showed that Salvia miltiorrhiza vinegar plus endurance exercise training for 8 weeks significantly improved body weight control, visceral fat weight, and insulin resistance. However, only Salvia miltiorrhiza vinegar treatment did not significantly improve body composition and insulin resistance. In addition, there was no additive by the combination of Salvia miltiorrhiza vinegar and endurance exercise in insulin, body fat, and total cholesterol. The reduction of body fat, glucose, insulin and cholesterol by combination was resulted from the exercise. These results suggest that Salvia miltiorrhiza vinegar has slight effect on anti-hyperglycemia and anti-obesity.
        309.
        2017.08 KCI 등재 서비스 종료(열람 제한)
        본 연구는 음의 포아송비 거동을 가지는 격자체의 구조부재 보강재로의 적용이 가능한지에 대한 검토를 수행하였다. 콘크리트를 포함한 일반적인 재료는 외부 하중의 작용 시 양의 포아송비 거동을 가진다. 이러한 콘크리트의 역학적 거동을 음의 포아송비 특성을 가지는 금 속 격자체가 구속함으로써 콘크리트의 강성을 증대시킬 수 있음을 이론적으로 확인하였다. 또한 실제 건설산업에 적용이 가능한 수준의 음의 포아송비 거동을 가지는 격자체의 형식을 제시, 역학적 거동 특성을 수치 해석적으로 검토하였다.
        310.
        2017.07 KCI 등재 서비스 종료(열람 제한)
        Freezing rain is a phenomenon when precipitation falls as a liquid rain drop, but freezes when it comes into contact with surfaces or objects. In this study, we investigated the predictability of freezing rain and its characteristics, which are strongly related with the occurrence of black ice using synoptic scale meteorological observation data. Two different cases occurred at 2012 were analyzed and in the presented cases, freezing rain often occurs in the low-level low pressure with the warm front. The warm front due to the lower cyclone make suitable environment in which snow falling from the upper layer can change into supercooled water. The 0℃ temperature line to generate supercooling water is located at an altitude of 850 hPa in the vertical temperature distribution. And the ground temperature remained below zero, as is commonly known as a condition for black ice formation. It is confirmed that the formation rate of freezing rain is higher when the thickness after 1000-850 hPa is 1290-1310 m and the thickness of 850-700 hPa layer is larger than 1540 m in both cases. It can also be used to predict and estimate the generation of freezing rain by detecting and analyzing bright bands in radar observation.
        311.
        2017.05 서비스 종료(열람 제한)
        Background : Acreage of rain-shelter plastic greenhouse to prevent anthrax is being gradually increased according to growing importance of safe Boxthorn production. But When Boxthorn is grown in the hot season in rain-shelter plastic greenhouse, Fertility decreases. The fertilization rate tends to be different according to cultivated variety and ventilation type of rain-shelter plastic greenhouse. Therefore it is necessary to identify cause and look for a solution. Methods and Results : In the experiment, ‘Cheongun’ cultivar was grown in the rain-shelter plastic greenhouses for the tests. Environment of rain-shelter plastic greenhouses, fertilization rate and density of flower visiting insect were investigated according to ventilation type. Pollen germination and pollen tube elongation on stigma were investigated according to temperature. In mid-July, the temperature on a clear day rose to 45℃ in rain-shelter plastic greenhouse of side vents. Pollen germination and pollen tube elongation on stigma were normal for 3 hours on 30, 35℃. Fertilization rate was somewhat reduced on 40℃ but Pollen germination and pollen tube elongation was good. On 45℃, fertilization rate was very poor and There was no pollen germination. Density of flower visiting insect in rain-shelter plastic greenhouse of roof and side vents was higher than that in rain-shelter plastic greenhouse of side vents. The fertilization rate on high temperature did not show any difference regardless of ventilation type. The rate of artificial cross-fertilization and airborne fertilization were high in rain-shelter plastic greenhouse of roof and side vents. It was necessary to improve airborne fertilization rate because airborne fertilization rate was significantly lower than artificial cross-fertilization regardless of ventilation type. Conclusion : When it was cultivated in rain-shelter plastic greenhouse, the reasons for the lowering of the fertilization rate were as follows. Density of flower visiting insect was low. Boxthorn, which was insect pollination crop, was needed sufficient flower visiting insect on flowering period. But it was insufficiency especially in rain-shelter plastic greenhouse of side vents. Another reason was decrease in pollen germination and pollen tube elongation. Pollen germination was suppressed in the high temperature.
        312.
        2017.05 서비스 종료(열람 제한)
        Background : The use of the rain shelter facility gets more prevalent in the Ginseng cultivation area these days. This study is designed to establish a technique for the stable cultivation of Ginseng in the rain shelter facilities in high temperature (above 30 ℃) without the damage from high temperature Methods and Results : This study was carried out on 3-year Ginseng roots in 2016 in order to find out how to stably cultivate Ginseng in high temperature without suffering the high temperature damage during the cultivation of Ginseng under rain shelter facilities. The rain shading materials were coated with scattering film (scattering film + black shading net 90%), bluish white double-sided film (shading 85%) and PE film (PE film + black shading net 90%). The damage reduction by high temperature was made to the scattering film and bluish-white double-ended film only. An aluminum screen (shading rate: 40%) was installed when the high temperature (above 30℃) was reached while the isoprene (solution of 2000 times) was sprayed 4 times every 7 days from the full development stage. The light transmittance was 12.6 - 13.4% for the scattering film, 10.5 - 10.8% for the bluish-white double sided film and 7.1% for the PE film in the first coating while it was 7.3% for the scattering film and 7.1% for the bluish-white double-sided film when the aluminum screen was installed in high temperature. The high, average and low values in the relative humidity were higher inside the facility than in the outside during the survey period. The area of leaf was the largest under the scattering film. The area of leaf was the largest for the scattered film under the aluminum shade of 40% shading followed by that of spraying of isoprene 4 times, and that of the no-treatment. As for the growth under ground, the growth of underground shoots increased by 40% in aluminum screen, 53.7% in shading and 26.1% in the spraying of isoprene 4 times than non-shading while there was no difference among other rain shelter materials. Conclusion : The result of the research showed that when the scattering film is selected as the rain shelter material film for the cultivation of Ginseng, it is necessary to shade the sunlight as much as 40% by using the aluminum screen or the shading net to reduce the high temperature damage.
        313.
        2017.05 KCI 등재 서비스 종료(열람 제한)
        본 논문에서는 국내 비내진상세 조적채움벽 RC 골조의 내진성능을 파악하기 위하여 실규모 크기의 비내진상세 조적채움벽 RC 골 조를 대상으로 정적실험을 실시하였으며, 기존 비내진상세 RC 골조 의 정적 실험결과와의 비교·분석을 통하여 조적채움벽체가 RC 골조의 내 진성능에 미치는 영향에 대하여 평가하였다. 실험 결과. 조적채움벽 RC 골조 실험체는 조적채움벽체에 의한 압축력으로 기둥, 보 , 접합부 등 골조 전체에 균열 등의 손상이 발생하였으며, 접합부 전단균열이 벌어지고 철근이 노출되면서 취성 파괴되었다. 한편, 조적체움벽 RC 골조 실 험체의 수평하중과 층간변형각 관계는 벽체 슬라이딩 균열, 기둥 균열 등으로 강성이 저하되었으며, 철근 항복이후 최대 내력에 도달하고 접합 부 균열의 확대, 철근 노출 등으로 내력이 최대 내력의 40% 정도로 저하되었다. 조적채움벽체로 인하여 기둥 상·하단 및 접합부에만 집중되던 손상이 기둥, 보, 접합부 등 골조 전체에 분산되어 발생하였으며, 기둥의 전단균열이 아닌 접합부의 전단균열의 확대로 최종 파괴되었다. 또한, 조적채움벽체로 인하여 RC 골조의 강성은 12.42배, 내력은 3.63배 증가한 반면에, 강성 증가에 따라 최대 내력 시의 층간변형각은 0.18배, 파괴 시의 변형은 절반 이하로 감소하였다.
        314.
        2017.04 서비스 종료(열람 제한)
        This study examined the effects of the embedded auxetic grating structures by design on numerical analysis. Compressive tests were performed and the results showed the effectiveness of auxetic grating structures for the enhancements of stiffness.
        315.
        2017.04 서비스 종료(열람 제한)
        A minimum reinforcement ratio is an important factor to prevent a brittle failure for RC flexural members. In this paper, a parametric study of minimum reinforcement ratio is performed according to concrete strength, steel yield strength and cover depth ratio for each design provisions. A minimum reinforcement ratio using a stress-strain model is suggested. And results show that this mode is able to reflect material strength and cross-section properties properly.
        316.
        2017.02 KCI 등재 서비스 종료(열람 제한)
        The Expanded Guide Circle (EGC) method has been originally proposed as the guidance navigation method for improving the efficiency of the remote operation using the sensory information. The previous algorithm is, however, concerned only for the omni-directional mobile robot, so it needs to suggest a suitable one for a mobile robot with non-holonomic constraints. The ego-kinematic transform is a method to map points of R2 into the ego-kinematic space which implicitly represents non-holonomic constraints for admissible paths. Thus, robots with non-holonomic constraints in the ego-kinematic space can be considered as “free-flying object”. In this paper, we propose an effective obstacle avoidance method for mobile robots with non-holonomic constraints by applying EGC method in the ego-kinematic space using the ego-kinematic transformation. This proposed method shows that it works better for non-holonomic mobile robots such as differential-drive robot than the original one. The simulation results show its effectiveness of performance.
        317.
        2017.02 KCI 등재 서비스 종료(열람 제한)
        목적: 본 연구의 목적은 저소득층 아동⋅청소년의 신체활동 장애요인을 탐색하여 신체활동을 촉진할 수 있는 전략을 모색하는 것이다. 방법: 신체활동 장애요인의 정보를 얻어 나타난 주제에 대한 제언을 하기 위해 변형근거 이론이 활용되었다. 58명의 아동⋅청소년을 대상으로 개별 반구조화면담, 집단 초점 면담, 현장노트를 통해 자료를 수집하였으며, 전사된 자료는 항시 비교 방법을 통해 범주화되었고, 이 자료는 요인끼리의 상호관련성이 검토되고 3 가지의 주제로 조직되었으며, 이는 다시 본 연구 자료의 개념적 틀로 형성되었다 본 연구자와 세 명의 연구보조자들이 일련의 회의를 통해 나타난 개념적 틀을 고찰, 토의하는 과정을 통해 확정되었다. 문헌연구와 두 명의 외부전문가의 피드백을 통해 본 연구의 외재적 타당성이 향상되었다. 결과: 본 연구의 결과는 세 가지의 주제에 따라 논의되었다. 이들 주제는 선행요인, 동기 유발요인, 제언이었다. 선행 요인은 신체활동에 대한 개인 내적, 외재적 장애요소였다. 동기유발 요인은 신체활동에 참여하고자 하는 개인의 욕구를 활성화시킬 수 있는 요소들이다. 제언 요소는 신체활동을 증진하기 위해 참여자가 규명할 수 있는 아이디어들이다. 결론: 본 연구는 신체활동을 촉진할 수 있는 중재전략을 세우기 위해 필요한 종합적 접근방법을 강조하고 있다. 신체활동을 위한 제언은 보다 건강한 생활양식을 활성화시켜 신체활동을 증가시키는 것이다.
        318.
        2017.01 KCI 등재 서비스 종료(열람 제한)
        This study examined the effects of the embedded auxetic grating structures by design on numerical analysis. Compressive tests were performed and the results showed the effectiveness of auxetic grating structures for the enhancements of stiffness.
        319.
        2016.11 KCI 등재 서비스 종료(열람 제한)
        A new prediction scheme has been proposed for the robust teleoperation in a non-visible environment. The positioning error caused by the time delay in the non-visible environment has been compensated for by the Smith predictor and the sensory data have been estimated by the Grey model. The Smith predictor is effective for the compensation of the positioning error caused by the time delay with a precise system model. Therefore the dynamic model of a mobile robot has been used in this research. To minimize the unstable and erroneous states caused by the time delay, the estimated sensor data have been sent to the operator. Through simulations, the possibility of compensating the errors caused by the time delay has been verified using the Smith predictor. Also the estimation reliability of the measurement data has been demonstrated. Robust teleoperations in a non-visible environment have been performed with a mobile robot to avoid the obstacles effective to go to the target position by the proposed prediction scheme which combines the Smith predictor and the Grey model. Even though the human operator is involved in the teleoperation loop, the compensation effects have been clearly demonstrated.
        320.
        2016.11 KCI 등재 서비스 종료(열람 제한)
        본 연구에서는 반구형과 평탄형의 비상체를 이용하여 일반콘크리트와 섬유보강콘크리트에 충격시험을 진행한 후 파괴깊이와 형 태, 파괴직경, 배면의 인장변형을 평가하였다. 선단면적이 작을수록 충격력의 집중에 의해 파괴깊이는 크고 표면파괴 직경은 작게 되는 것으로 확인되었다. 반면에 선단면적이 클수록 파괴깊이는 작지만 표면파괴직경은 크게 되었다. 일반콘크리트와 섬유보강 콘크리트에서 유사한 표 면파괴와 배면변형이 발생하였으나 인장변형의 크기는 일반콘크리트에 비해 섬유보강 콘크리트가 작은 것으로 나타났다. 또한, 비상체의 선 단형상에 따른 표면관입의 형태와 배면의 인장변형 사이에 직접적인 연관이 있는 것으로 사료된다. 따라서 콘크리트의 배면박리한계두께 예 측 시에는 표면관입깊이뿐만 아니라 배면의 변형거동 또한 고려할 필요성이 있을 것으로 사료된다.