검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 1,255

        441.
        2018.05 구독 인증기관·개인회원 무료
        The objective of this study was to evaluate the effectiveness of various crack inducers to be used in the advanced reinforced concrete pavement (ARCP) by conducting yard tests. Some of cracks are induced in ARCP to reduce the stresses in steel bars and to form more uniformly spaced cracks so that the required steel bar amount can be decreased and at the same time the pavement performance can be improved. In this study, an experimental ARCP was constructed for the length of 22.4 m, width of 1.12 m, and thickness of 0.26 m. The anchor lugs were placed at both ends of ARCP to pretend continuities of the system. 8 crack inducers with a uniform spacing of 2.8 m were installed in different manners when placing concrete, so the test length of the experimental ARCP was 19.6 m. The variables of crack inducers included the shape, material, installed depth, and installing method. The basic shape of the crack inducer represented a round face and a flat opposite face with a height of 50 mm and a width of 10 mm. The slightly different shaped crack inducers were installed for inducing cracks at both ends of ARCP. The crack inducers were primarily made of glass fiber reinforced plastic (GFRP) but a crack was induced using a polyethylene sheet inducer. The installed depths of the crack inducers were 30, 40 and 70 mm to the top of the crack inducer from the pavement surface. Most crack inducers were preinstalled on the transverse steel bar locations before concrete pouring, but 2 crack inducers were installed just after concrete placement when concrete was still fresh. The temperature measurement sensors of i-Buttons and thermocouples were installed at the top, middle and bottom of slab to measure the temperature variations of slab. The displacement transducers were also installed at the crack locations to measure the crack width movements. The experimental results showed that the cracks were induced at all the locations where the crack inducers were placed. In addition to the induced cracks, just one crack was formed naturally. The crack patterns on the surface of pavement were all comparable. The crack width measurement data showed that there were slight differences in the crack width movements among the cracks but all the cracks including both the induced and naturally formed cracks moved little within a 0.1 mm range. Therefore, any type of the crack inducers employed in this study can be used to initiate cracks in ARCP.
        442.
        2018.05 구독 인증기관·개인회원 무료
        Composite pavements are constructed by placing a high functional asphalt surface layer on a high performance concrete rigid base layer and provide a more durable, high functional surface to road users. Service life of composite pavements is dependent on the bonding performance of the lower rigid base and the flexible surface layer. Accordingly, it is necessary to place an impermeability layer between the functional surface layer and the rigid base to enhance bonding performance and to prevent moisture penetration into the rigid base and deterioration of pavement. In order to use optimal composite pavement sections, two types were applied to impermeability layer: highly impermeable water-tight SMA and mastic asphalt currently in use. APT (Accelerated Pavement Testing) and experimental construction were carried out to evaluate bond strengths between the rigid base and the impermeability layer depending on the type of impermeability layers. Composite pavement sections for the APT had a 22 cm concrete rigid base layer and a 5cm functional surface, as well as either 5cm of SMA impermeability layer and 5cm of mastic layer. After applying around 8,574,000 ESALs, pull-off test was conducted, which showed that the mastic section outperformed the SMA section. In the experimental construction, three types of rigid base layers, JCP (Jointed Concrete Pavement), CRCP (Continuously Reinforced Concrete Pavement), and RCCP (Roller Compacted Concrete Pavement), were used for composite pavement sections, and as in the APT, two types of impermeability layers, SMA and mastic, were used per rigid base layer of new and deteriorated concrete pavement. Therefore, seven composite pavement sections in total were constructed. We measured the bond strength over one year or so following the construction of these composite pavement sections and found that regardless of the type of rigid base layer and whether it was new or not, those sections with a mastic impermeability layer had high bond strengths.
        443.
        2018.05 구독 인증기관·개인회원 무료
        In Korea, concrete pavements were first applied to highways in 1981 and as a result of continued increase in length over the past years, 2,592 km of concrete pavement network is currently in service, of which 1,399 km(54%) of concrete pavements is 10 years or older, and 233km(9%) is 20 years or older. The length of concrete pavement sections nationwide has been steadily on the rise every year (EXTRI, 2017). Approximately 54% of current concrete pavement highway network will reach the service life limit in 2025 which means around 660 billion won is needed for future pavement repair project (EXTRI, 2017). Given that concrete pavements beyond design life still have a remaining service life, it is economically advantageous to repair them before reconstruction. Asphalt overlays are a major repair method for older concrete pavements. Depending on the concrete pavement condition, thickness and mixture of asphalt overlays are determined. Service life of asphalt overlays varies by the presence, time and size of cracks in existing concrete pavements and reflecting crack at joints. Temperature change of concrete pavement is among the major reaction parameters of reflecting crack. Reflecting crack develops when asphalt bottom-up cracking by longitudinal shrinkage and expansion due to temperature change of the concrete base layer, top-down cracking by temperature difference between top and bottom of concrete, and shear stress by traffic loading are combined (Baek, 2010). Crack and joint behaviors of concrete pavement vary between the base layer and the concrete surface of composite pavement system, and different conductivity by mixture and thickness of asphalt overlay leads to temperature change of concrete base course. This study measured temperatures of each layer of diverse composite pavements in place on site and analyzed differences in temperature change of concrete base layer depending on mixture and thickness of asphalt overlays. Overlay thickness parameters were 5cm and 10cm, two values most widely used, while mixture parameters were SMA and porous asphalt. Based on temperature change of concrete surface, this study also evaluated the difference of temperature change in concrete base layer with an asphalt overlay on top. Findings from this study are expected to be utilized for studies on mechanism and modeling of reflecting crack in old concrete pavements with asphalt overlays.
        444.
        2018.05 구독 인증기관·개인회원 무료
        Roller-compacted concrete (RCC) has been widely used for construction of pavements [1]. The strength of RCCP can be obtained from not only hydration of binder but also the aggregate interlock resulted from roller-compaction [2]. For this reason, RCCP normally achieves higher strength compared to conventional concrete pavement with similar cement content. Even though RCCP can be provided a good structural performance, it has been difficult to verify the long-term performance though actual field construction. Therefore, this study aimed to investigate the fatigue characteristics and crack development in RCCP based on full-scale fatigue test and accelerated pavement test. In case of full-scale fatigue tests, fatigue behavior was evaluated by using 1 m × 1 m dimensional RCC slab specimens obtained from the field in order to consider the field variability. Fatigue equation derived from this study shows that the number of load repetitions which causes fatigue failure at the same stress level is slightly larger than that of PCA fatigue equation. In order to evaluate the performance of RCCP, two phases of accelerated pavement test (APT) were conducted. In phase one, the performance of RCCP at two different strengths (35.6 and 30.4 MPa) was evaluated. In phase two, the performance of RCCP with different thickness (5, 7.5 and 10 cm) was investigated. The number of load repetition of fatigue crack occurrence in each section was compared to the estimated fatigue failure determined from fatigue equation of RCCP. The crack development in each section was compared to the AASHTO crack model for JPCP. Overall, it was confirmed that RCCP has equal or better performance compared to JPCP the estimation in term of fatigue cracking. The fatigue equation from PCA and cracking model from AAHTO can be used on RCCP at certain design thickness range.
        445.
        2018.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        작물의 생산량은 광합성과 밀접한 관계가 있으며, 광합성 속도는 다양한 환경 요인에 의해 변화한다. 광합성 속도는 작물의 생육 상태나 생육 속도를 판단하는 지표로 사용되며, 작물 재배 시설을 구축하는 데 고 려해야 하는 중요한 요인이다. 이 연구의 목적은 광도, CO2 농도 및 생육 단계에 의해 변화하는 로메인 상추 의 군락 광합성 속도 모델을 개발하는 것이다. 군락 광합성 속도는 정식 후 5, 10, 15, 20 일차에서 5단계의 CO2 농도(600-2,200μmol·mol-1)와 5단계의 광조건(60-340μmol·m-2·s-1)이 처리된 3개의 밀폐 아크릴 챔버(1.0 × 0.8 × 0.5m) 내에서 측정하였다. 먼저 세 가지 환경 요인을 사용하는 식들을 곱하여 만든 단순곱모델을 구성 하였다. 이와 동시에 생육 시기에 따라 변화하는 광화학 이용효율과 카르복실화 컨덕턴스, 호흡에 의한 이산화탄소 발생 속도를 포함하는 수정 직각쌍곡선 모델을 구성하여 단순곱 모델과 비교하였다. 검증 결과, 단순곱 모델의 R2는 0.923이었으며, 수정 직각쌍곡선 모델의 R2는 0.941을 나타내었다. 따라서 수정 직각쌍곡선 모델 이 광도, CO2 농도, 생육 단계의 3 변수에 따른 군락 광합성 속도를 표현하는 데 더욱 적합한 것으로 판단하 였다. 본 연구에서 개발된 군락 광합성 모델은 식물공장에서 상추 재배를 위해 생육 단계별로 설정해야 할 최 적의 광도와 CO2 농도를 결정하는데 도움이 될 것으로 생각된다.
        4,000원
        448.
        2018.04 구독 인증기관·개인회원 무료
        This study was conducted to evaluate the the efficacy of mulberry cake mixed diet on larval growth of Protaetia brevitarsis. As a result of adding 3, 5, and 10% mulberry cake to the fermented mulberry sawdust, the development period of the Protaetia brevitarsis larvae was 44.9days, 44.6days, and 41.8days, and the highest weight of larvae was 2.76g, 2.80g, and 2.89g, respectively. As a result of adding 3, 5, and 10% mulberry cake to the fermented oak sawdust, the development period of the Protaetia brevitarsis larvae was 46.7days, 41.6days, and 41.7days, and the highest weight of larvae was 2.65g, 2.65g, and 2.56g, respectively.
        449.
        2018.04 구독 인증기관·개인회원 무료
        The mulberry for production of mulberry fruit, found the damage and quantity according to the level of damage by the A. mori, and through regression analysis, we set up a economic injury level. The level of damage by A. mori was to be artificially adjusted, for 2 percent, 5%, 8 percent, and 11 percent of leaf damage. Investigate, From May 31 to June 14, they compared the damage to each damage level and the growth and development and quantity. The survey found that the more damage level, the more severe the damage. The ratio of damage fruit was 5.1 percent, 11 percent, 13.2 percent, 23.9 percent, respectively. And the quantity was reduced by about 33% from 11 percent to 2,387 g/tree compared to the 2 percent to 3,557 g/tree. There's no difference in the damage caused by the sclerotium disease, and the growth and development, such as the length of the tree, the length of the branches, and the thickness of branches. The relationship between the damage level and the ratio of damage fruit was able to obtain relations with the linear regression, Y = 2.129552 X +0.569663(R2 = 0.98). It's the result of an analysis, which analyzed the damage level's relationship with the ratio of damage fruit have a high correlation rate. Therefore, It’s about the ratio of the quantity losses is 5 percent, the ratio of damage leaf is 2.08 percent. If the ratio of damage leaf is more than 2.08 percent, the damage will be required the control. It is judged.
        450.
        2018.04 구독 인증기관·개인회원 무료
        The citrus flatid planthopper Metcalfa pruinosa, a invasive species causes serious damages to field crops, including sweet persimmon, soybean, maize, especially ginseng (Panax ginseng C.A meyer). We selected six chemical pesticides and one environmental friendly pesticide made from the mixture of derris extracts, citronella oils, and cinnamon extracts in laboratory. These pesticides showed over 90% of control effect in open ginseng field. This study was carried out with the support of the cooperative research program for RDA (project No. PJ0124992018), Republic of Korea.
        451.
        2018.04 구독 인증기관·개인회원 무료
        참나무와 서어나무는 온대지역에 걸쳐 넓게 분포하고 있으며, 다양한 초식곤충의 먹이원이 되는 것으로 알려져 있다. 이 연구에서는 지리산국립공원 온대림에서 참나무림(반선)과 서어나무림(상선암)에서 초식곤충 활동량을 알고자 하였다. 각 조사지역에 0.1ha의 방형구를 설치하여 참나무와 서어나무의 분포를 확인 한 뒤 개체별로 초식곤충의 활동량인 잎 손상 지수를 측정하였다. 잎 손상 지수는 손상 퍼센트로 환산하여 분석하였다. 측정결과 전체 4,413장의 잎을 관찰하였으며, 참나무림에서는 2,683장, 서어나무림에서는 1,730장의 잎이 조사되었다. 초식곤충의 활동량은 참나무림과 서어나무림에서 각각 차이를 보였으며 서어나무림인 상선암에서 참나무의 식흔량과 서어나무의 식흔량 이 참나무림인 반선보다 모두 높게 나타났다. 이 연구결과를 바탕으로 온대림 우점 수종인 참나무와 서어나무에서 초식곤충의 활동량을 정량적으로 추정할 수 있을 것으로 생각된다.
        452.
        2018.04 구독 인증기관·개인회원 무료
        우리나라는 약 4,000여개의 크고 작은 섬들로 이루어져 있고, 그 속에는 다양한 생물종들이 주변 환경과 상호작용하 며 서식하고 있다. 그 중 초식성 곤충은 생물 구성의 1/4로 많은 비율을 차지하며, 생산자인 식물을 먹고 2차 소비자의 먹이원이 됨으로써 생태계의 중간 고리 역할을 한다. 본 연구는 다도해해상국립공원에 속해 있는 크기가 다른 6개의 섬에서 초식성 곤충의 영향을 알 수 있는 식흔과 여기에 영향을 줄 수 있는 환경요인(섬 면적, 육지와의 거리, 해안선 길이, 최고고도)과의 관계를 알아보았다. 식흔을 알아보기 위해 낙엽활엽수인 4개의 수종(참나무속, 벚나무속, 예덕나무속, 오리나무속)을 선정하여 2017년 6월과 9월에 관찰하였다. 이와 함께 초식성 곤충 중 종 다양성이 풍부한 나방을 채집하여 식흔자료와 비교하였다. 조사결과 섬 면적이 커질수록, 해안선의 길이가 길수록, 최고고도가 높을수록 식흔량이 증가하는 경향을 보였고, 나방의 종수도 증가하였다. 반면 육지와의 거리가 멀수록 식흔량이 감소하는 경향을 보였고, 나방 종수도 감소하였다. 이러한 결과를 통해 초식성 곤충의 다양성과 환경요인이 관련 있는 것을 확인할 수 있었다
        453.
        2018.04 구독 인증기관·개인회원 무료
        G protein-coupled receptors (GPCRs) belong to cell membrane protein family, which regulate various physiological process such as reproduction, behavior and immune etc. In other to identify the GPCRs in pheromone gland of Maruca vitrata, we carried out transcriptome analysis from both females. Transcriptome analysis in the pheromone gland yielded approximately 22Gb and 47,528 transcripts showed positive FPKM value. 48 Genes involved in GPCRs were identified such as pheromone biosynthesis activating neuropeptide receptor (PBANr), prostaglandin receptors, neuropeptide receptor, 5-hydroxytryptamine receptor, galanin receptor, calcitonin gene-related peptide receptor, diuretic hormone receptor, gonadotropin-releasing hormone receptor, frizzled and orphan receptors, etc. Various expression of GPCRs in the pheromone gland indicates the role of pheromone gland may not be limited to the production of pheromone.
        454.
        2018.04 구독 인증기관·개인회원 무료
        농학(농업곤충)과 공중위생학(위생곤충) 뿐만 아니라 최근 기초생명과학 분야에서 중요하게 여겨지는 곤충학 전공은 분류학, 생태학, 생리학, 독성학, 생명공학 등을 아우르는 종합 응용학문이라 판단된다. 이러한 다양한 연구 분야를 포함하는 곤충학 전공 학생들의 장래 직업선택에 있어서도 다양한 선택지가 있을 것이다. 대학원생에게 진로 선택은 크게 수학의 연장과 취업으로 구분될 수 있다. 수학 연장의 경우에는 국내 및 외국으로의 박사과정 혹은 박사후과정으로의 진학이 가능하며, 취업의 경우에는 공공분야(국가 연구소), 기업 및 대학 연구원으로의 지원이 가능할 것이다. 특히 박사학위 취득 후에는 추가로 교수직 지원 또한 가능하게 된다. 성공적인 진학 또는 취업을 위한 정보의 획득과 전략의 수립은 각각의 진로 방향성에 맞게 특화되어야 할 것으로 판단되며, 본 심포지엄에서 는 공공기관, 기업, 해외 및 국내교수직에 종사하고 있는 여러 선배 곤충학자들을 통해 그들의 경험과 정보를 공유하고, 성공적인 취업 준비에 대한 논의를 하고자 한다. 뿐만 아니라 해외 박사과정 및 박사후과정을 마친 선배들을 통해 해외로의 진학을 위한 구체적 정보, 일정 및 전락에 대해서도 논의하고자 한다.
        455.
        2018.04 구독 인증기관·개인회원 무료
        Haemaphysalis longicornis (Acari: Ixodidae) is a medically important arthropod vector of tick-borne diseases, especially the severe fever with thrombocytopenia syndrome (SFTS). To establish a management strategy against tick-borne diseases, it is fundamental to understand the basic biology of vector species. Therefore under laboratory conditions, we evaluated the horizontal movement of adult and nymph stages of H. longicornis to better understand their dispersal behaviors. In the experiments, field populations were subjected to video recording of the horizontal movement of the ticks in a petri-dish arena for 3 hours. Our results indicate that nymphs showed a significantly higher mobility than adults, whereas there was no significant difference in angular velocity. Nymphs moved 3.74 ± 0.26 m at an angular velocity (AV) of 1.60 ± 0.07 deg/s. and adults moved 2.91 ± 0.26 m at an AV of 1.61 ± 0.14 deg/s.
        456.
        2018.03 KCI 등재 구독 인증기관·개인회원 무료
        세계적으로 관상작물의 중요한 나방류 해충의 하나인 Duponchelia fovealis Zeller가 2015년과 2016년에 경기도에서 처음으로 발견되었다. 유충이 꽃기린(Euphorbia milii)의 줄기 속을 파고 들어가거나 게발선인장(Schlumbergera truncata)의 잎을 가해하는 피해가 확인되었다. 유충과 피 해 확인 직후 합성농약을 살포하였고, 현재까지 추가적인 발견은 없었다.
        457.
        2018.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The objective of this study was to investigate the effects of freeze dried placenta supplementation on reproductive performance, colostrum and plasma biochemical composition in pregnant sows. Eleven Landrace × Large white sows were fed with corn-soybean meal diets supplemented with or without 1% freeze dried placenta powder from 10 days before their expected farrowing dates until 10 days postpartum. The colostrum protein content was significantly higher(P=0.043) in the treatment group than in the control group. Compared to the control group, the immunoglobulin G(IgG) concentration in the colostrum was significantly higher(P=0.004) in the treatment. In day 25 piglets plasma, the IgG concentration was higher(P=0.184) in the treatment than the control. The mortality rate was lower(P=0.102), and the piglet weight gain was higher(P=0.35) in the treated group. Overall, the treatment group showed greater levels of protein and IgG concentration in the colostrum, when compared to control group. Therefore, the freeze dried placenta supplementation on pregnant sows can enhance its colostrum composition, hence decrease the mortality and increase the growth rate of piglets.
        4,000원
        458.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The aim of the study was to investigate the effects of incentive spirometry and Ujjayi breathing technique on the pulmonary function of smokers. Subjects were individuals who had a smoking habit of at least a year. Subjects were randomly divided into 3 groups: the incentive spirometry group (n=8), Ujjayi breathing technique (n=9), and a group applying both incentive spirometry as well as Ujjayi breathing technique (n=8). Each intervention was performed twice a day, 5 times a week, for a total of 8 weeks whereupon the change in pulmonary function was evaluated. A spirometer was used to measure FVC, FEV1, and FEV1/FVC. The survey used for this study included the Fagerström Test of Nicotine Dependence (FTND) and the Shortness of Breath Questionnaire (SOBQ). Study results for the comparison within groups showed that in the group that performed both the incentive spirometry and Ujjayi breathing technique, FEV1 improved with statistical significance (p<.05). Furthermore, within this comparison the FEV1/FVC improved with statistical significance. Comparison amongst the groups showed no statistically significant differences in all areas. Following, to effectively increase pulmonary function in young adult smokers, both incentive spirometry and Ujjayi breathing technique should be employed together.
        4,000원
        459.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        방울토마토의 수경재배 중 붕소+칼슘+규소 및 칼슘+규소의 복합 엽면시비가 수확 후 품질과 MAP 저장 중 저장성에 미치는 영향을 알아보고자 본 연구를 실시하였다. 엽면시비한 방울 토마토(‘Unicorn’)는 반숙 과상태에서 수확하여 산소투과성 필름으로 포장한 5oC, 11oC, 그리고 24oC에서 25일, 15일, 10일간 저장하였다. 붕소+칼슘+규소 복합처리한 방울토마토가 3가지 저장온도 모두에서 호흡과 에틸렌 발생이 억제되어 MAP 저장중 가장 낮은 생체중 감소와 가장 높은 외관상 품질을 보였다. 수확 후 조사한 방울토마토의 경도, 산도, 비타민 C 함량은 붕소+칼슘+규소 복합처리에서 가장 높았으며, 3가지 온도 모두에서 MAP 저장 후에도 모두 높게 유지되었다. 그러나 과피색, 라이코펜 함량과 당도는 수확 후에는 엽면시비 처리로 차이가 없었으나, 3가지 온도 모두 붕소+칼슘+규소 복합처리에서 가장 낮은 수치를 보였다. 이상의 결과로 볼 때 붕소+칼슘+규소 복합처리는 방울토마토의 수확후 생리 작용을 억제하고 경도, 산도, 비타민 C 함량을 높여 저장성을 향상시키는 것으로 판단되었다
        4,000원
        460.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The ability of antimicrobial resistant Salmonella strains to cause invasive disease can be attributed to various virulence genes. In this study, the virulence genes located in SPI-1, SPI-2, SPI-5, SPI-11 were found in all antimicrobial-resistant Salmonella isolates. This suggests that these genes play important roles in Salmonella invasion, growth, or survival in the host. The association between the presence of virulence genes and antimicrobial resistance was assessed using the Spearman’s correlation coefficient, and there is a positive association between the gatC, tcfA, hylE, spiA, pagC, msgA, invA, sipB, prgH, spaN, orgA, tolC, iroN, sitC, lpfC, and sopB genes, and resistance to CF, NA and S. This suggests that the association between antimicrobial agents and virulence genes has been shown to vary with the types of antibiotics that are commonly used in different countries. These different associations can be explained by the mechanisms underlying pathogenicity and the acquisition of resistance genes by Salmonella.
        3,000원