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        검색결과 895

        681.
        2014.02 서비스 종료(열람 제한)
        홍수와 가뭄은 과거부터 지금까지 모든 시대에 걸쳐 끊임없이 발생하여 왔으나 최근 들어 발생하는 홍수 및 가뭄의 재해 규모는 과거와 비교할 수 없을 정도로 대형화되고 홍수발생빈도 또한 급격히 증가하고 있다(하림 등, 2013). 소방방재청에 의하면 시간당 30㎜이상의 폭우발생빈도가 최근 30년 평균 3.8회, 5년 평균 5.2회로 나타났으며, 일 80㎜이상의 집중호우 일수는 1.5배 증가한 것으로 조사되었다. 또한 우리나라는 최근 기후변화로 인해 6-7년 주기로 가뭄 강도가 점차 증가하고 하천수 과잉 취수 등으로 하천 건천화가 발생하고 있다(맹승진 등, 2013). 이에 대한 대책으로 정부에서는 수자원종합개발 10개년 계획, 수자원 장기종합계획 등을 수립하고 하천정비사업 시행과 다목적 댐을 세우는 등 치수방재를 위해 노력하고 있지만, 급변하는 기상상황에 신속히 대처하기엔 어려움이 있어 홍수 및 가뭄 피해를 최소화 할 수 있는 대비책이 절실한 시점이다.이에, 본 연구에서는 홍수나 집중 호우시 빠른 대처가 가능하고 가뭄시 하천이나 용·배수로를 임시로 막아 농업용수를 확보할 수 있으며, 다방면에 적용성이 뛰어난 이동식 다목적 차수막을 개발 하였다. 이동식 다목적 차수막 개발을 위해 ⅰ) 이동성이 용이한 초경량 소재를 선정 하고, ⅱ) 구조해석 프로그램(MIDAS)을 적용한 최적 규격 선정, ⅲ) 현장 적용을 통해 안전성을 검증 하였다. 제품의 경량화뿐만 아니라 차수 효과의 극대화를 위하여 수압에 대한 내구성이 확보되고 불규칙한 바닥면에 우수한 접지력을 지니고 있는 Sol Tarpaulin(PVC 코팅 폴리에스테르)소재를 선정하였다. 또한, 3차원 구조해석 프로그램인 MIDAS를 이용하여 수압에 의한 차수막의 파손 및 밀림 현상이 발생하지 않는 구조로 설계하였다. 개발된 차수막을 서울시 관악구 내 도림천과 서울시 광진구 내 지하주차장에 적용한 결과, 수압에 의한 파손 및 밀림현상이 발생하지 않았고 지속적인 기립형상을 유지하며 차수되어 구조 및 소재의 안전성뿐만 아니라 다목적 활용이 높은 것으로 나타났다.현재까지 홍수 및 가뭄 대비를 위한 시설물들은 국지적인 집중호우에 취약하고 가뭄에 대한 대책은 미비한 실정이다. 본 연구에서 개발된 이동식 다목적 차수막을 적절히 사용한다면 이·치수 및 방재 설비 등으로 활용 가치가 높을 것으로 기대된다.
        682.
        2013.12 KCI 등재 서비스 종료(열람 제한)
        해운대 해수욕장은 육지로부터 유입되는 모래 공급원의 감소와 고파랑 및 반사파 등의 영향으로 백사장의 폭이 매년 감소하는 것으 로 나타났다. 표사이동에 따른 해빈변형 문제를 해결하기 위해서는 해빈류의 특성을 예측할 필요가 있다. 본 연구에서는 해운대 해수욕장에 대 한 장기적이고 종합적인 관측자료를 바탕으로, 계절별 대표파랑과 이상파에 대한 해빈류 및 표사이동 수치실험을 실시하였다. 여름에는 평상파 및 S계열 파랑에 의해서 해빈류는 연안을 따라 동쪽으로 흘러 미포측에서 퇴적되는 양상을 보이고, 겨울에는 평상파 및 E 계열의 파랑에 의해 해빈류는 서향하여 동백섬 인근에서 퇴적양상을 보이고 있다. 50년빈도 고파랑 내습시 SSW 파랑은 해운대 중앙에서 이안류가 발생하고, ESE 파랑은 미포측에서 연안을 따라 서측으로 흐름을 발생시키는 것으로 나타났다.
        683.
        2013.12 KCI 등재 서비스 종료(열람 제한)
        Most of livestock houses are concentrated in certain area with mass rearing system resulting in rapid spread of infectious diseases such as HPAI (highly pathogenic avian influenza). The livestock-related vehicles which frequently travel between farms could be a major factor for disease spread by means of transmission of airborne aerosol including pathogens. This study was focused on the quantitative measurement of aerosol concentration by field experiment while vehicles were passing through the road. The TSP (total suspended particle) and PM10 (particle matter) were measured using air sampler with teflon filter installed downward the road with consideration of weather forecast and the direction of road. And aerosol spectrometer and video recorders were also used to measure the real-time distribution of aerosol concentration by its size. The results showed that PM2.5 was not considerable for transmission of airborne aerosol from the livestock-related vehicle. The mass generated from the road during the vehicle movement was measured and calculated to 241.4 μg/m3 by means of the difference between TSP and PM2.5. The dispersion distance was predicted by 79.6 m from the trend curve.
        684.
        2013.11 KCI 등재 서비스 종료(열람 제한)
        A local map-based exploration algorithm for mobile robots is presented. Segmented frontiers and their relative transformations constitute a tree structure. By the proposed efficient frontier segmentation and a local map management method, a robot can reduce the unknown area and update the local grid map which is assigned to each frontier node. Although this local map-based exploration method uses only local maps and their adjacent node information, mapping completion and efficiency can be greatly improved by merging and updating the frontier nodes. Also, we suggest appropriate graph search exploration methods for corridor and hall environments. The simulation demonstrates that the entire environment can be represented by well-distributed frontier nodes.
        685.
        2013.10 서비스 종료(열람 제한)
        In this study, dynamic behavior of suspension bridge was evaluated under moving truck and lane load specified in the Korean limit state design code. The essential parameters affecting dynamic behaviour of bridges, i.e., road surface roughness and vehicle speed were considered. The road surface roughness was randomly generated based on ISO 8608 and the vehicle speed was considered 60~120 km/h. 3-D finite element model for the selected suspension bridge was constructed and Newmark’s direct integration method was used for bridge-vehicle interaction analysis.
        686.
        2013.09 KCI 등재 서비스 종료(열람 제한)
        Mobile sources produce a significant fraction of total anthropogenic emissions in Korea and have harmful effects on air quality. Mobile emissions are intrinsically difficult to estimate due to complicated road networks and variations of traffic volume with location and time. To measure traffic pollutants with high temporal and spatial resolution under real conditions a mobile laboratory was designed. The mobile laboratory provide concentrations of SO2, CO, NO, NO2 and location coordinate value. This approach allowed for pollutant level measurements on many roads within short periods of time. In this study, on-road concentrations of SO2, CO, NO and NO2 were measured using mobile platform measurement along the 25 main roads in Busan to estimate the average air pollution level in short time difference. The measurements were conducted on favorable meteorological days from 2010 to 2012 and the overall concentrations of SO2, CO, NO and NO2 were 0.006, 0.8, 0.182 and 0.055 ppm respectively. The result showed that the concentration of CO, NO and NO2 on road were twice, 18 times and 2.5 times higher than regional air quality monitoring sites mean in same period.
        687.
        2013.09 KCI 등재 서비스 종료(열람 제한)
        In order to study the effect of organic fertilizer on dry matter (DM) yield, nitrogen fixation and transfer from pea to barley, an experiment was carried out from May to June in 2008 in Incheon. A completely randomized block design with three replications was used for the experiment and one reference plot assigned each treatment for nitrogen fixation evaluation. Seeding mixture was 40kg barley and 80kg pea per ha. N rate of 40, 80 and 120kg/ha as organic fertilizer was applied at seeding. The equivalent of 1kg per ha as (15NH4)2SO4 Solution at 99.8 atom N was applied to the plots (30×20㎝) at mid April. Forage was harvested from each plot in ripening stage at ground level and separated into barley and pea. Nitrogen fixation was 32.4%, 23.4% and 0% at three different organic N levels. Transfer rate were from 47.6% to 21.8% in difference method and 24.6% and 21.4% on 15N dilution method. N Transfer amount were from 92.8kg/ha to 41.9kg/ha on difference method and 47.3kg in the 40kg N plots and 49.7kg in the 80kg N plots on 15N dilution method but there was no N transfer in 120kg N organic fertilizer plots. Benefit from increased organic fertilizer was not clear in terms of nitrogen fixation and transfer from pea to barley in barley and pea mixtures.
        689.
        2013.04 서비스 종료(열람 제한)
        This study focuses on dynamic behaviors of simply supported beams, especially, vertical displacements. Based on moving load model, the displacement is estimated by response superposition. The displacements tend to increase as load velocity increases except under resonance velocity and show very large values under resonance velocity. Therefore, we should investigate the resonance between train and structure.
        690.
        2013.04 서비스 종료(열람 제한)
        In this stduy, Calcium aluminate cement (CAC) and Ordinarly portalnd cement (OPC) concretes were evaluated by electrical ion penetration and diffusion to assess chloride transport properties. Both methods used concrete specimens. Electrical ion penetration measured total charge passed concrete specimens at 28, 56, 91 days, and chloride profiles were shown to evaluate chloride transport with diffusion after immersing concrete specimens in 4M NaCl solution during 200 days.
        691.
        2013.04 서비스 종료(열람 제한)
        The construction of underground rail crossing is effect on railroad infra-structure and rail safety. So various methods have been suggested to construct through the infra-structure on the railroad. This paper treats the results of studies for safety of temporary bridge using a commercial FEM program, RM which is operated based on data measured on a sites. Also it was carried out optimal section considering characteristic of dynamic which reflects actual load for speed cases.
        692.
        2013.04 서비스 종료(열람 제한)
        To evaluate the crews’ evacuation characteristics, anti-disaster drills are performed according to 3 different types of scenarios. The drill participants are 2 groups, namely the one is freshmen who is novice for onboard life, and the other is 3rd grade college men who experienced at least 6 months onboard life. As a result of trials, it is clear that the evacuation time of skilled crews(3rd grade colleges men) correspond 2 times faster than that of novices(1st grade colleges men). But on scenario 2 and 3, which are performed under the constriction of uncertainties, the evacuation times are closer than usuals.
        693.
        2013.02 KCI 등재 서비스 종료(열람 제한)
        The objective of this study was to evaluate fish passage efficiency, based on fish-trap monitoring methodology, in the fishway of Seungchon Weir, which was constructed on the lower region of Yeongsan River in 2011. Seasonal patterns and diel variations of fish movements, fish fauna, and compositions in the fishway were analyzed in relation to the current velocity and location of the trap-setting in the fishway. For the analysis, we conducted seven times surveys in 2012 on the fishway and also conducted intensive monitoring of the fishway as 3 hrs interval for the diel variations of fish fauna and compositions in the fishway. According to the fish-trap monitoring methodology, the total number of fish species was 13 species, which was a 43.3% of the total. Most dominant fish used the fishway was Squalidus chankaensis tsuchigae and the relative abundance of the species used the fishway was 33.5% of the total. The season and time zone (in diel variation) observed most frequently in the fishway were July and 18:00-21:00 PM, respectively. The fish movements and use-rates of fishway varied depending on the locations of trap-setting; Fish biomass and the number of species were statistically (p < 0.05) greater in the most right or left-sided traps than in the mid-traps. Also, fish movements and use-rates of fishway were influenced by current velocity on the fishway; fish in the fishway preferred the low current velocity (mean 0.71 m/sec) than the high current velocity (mean 1.13 m/sec). Further long-term studies should be monitored for the efficiency evaluations of the fishway.
        694.
        2012.11 서비스 종료(열람 제한)
        A strain compatibility method is based on the strain compatibility approach proposed by AISC (American Institute of Steel Construction, Inc.). The strain compatibility method assumes a linear strain of all the members. After that, set up the equilibrium equations of the state of stress in each component for calculating the location of the neutral axis of the cross-section in the presence. In this study, the reinforced concrete simple beam is analyzed by strain compatibility method for calculating the neutral axis and the bending moment. And then, a variation of neutral axis of the reinforced concrete simple beam is measured.
        695.
        2012.11 서비스 종료(열람 제한)
        The slope adjacent to the road, when it is difficult to observe the shape and if not at the bottom of the upper slopes or steep high due to the presence of the upper slopes of the exact visual inspection is difficult, there is a direct investigation lengthy complaints. In this study, the disadvantages of having the inspection personnel based complementary and mixed low-cost single global region is the number of slope maintenance and safety can be managed efficiently so that helicopters and hexa mobile survey vehicle was developed. Equipment developed difficulties in spatial or temporal slope Visually inspect efficient investigation to be able to support. Survey vehicle computer to the Internet environment because it contains Slope check immediately to determine test results sent to the Center, and the efficient maintenance can be performed.
        696.
        2012.10 KCI 등재 서비스 종료(열람 제한)
        As increasing incidents of FMD (Foot and Mouth Disease) in recent years, the country has struggled with huge economic losses and environmental problems. Because of relying only on the burial method according to domestic condition, it needs to consider the alternative measure such as the incineration with being no secondary environmental pollution. In addition, such FMD and AI (Avian Influenza) as classifying in the first-class malignant diseases are very important to be ready with rapidly initial response because of the fact being quickly spreaded with high infection speed. Accordingly, a favorable initial response by the introduction of mobile incinerators has been forced to consider. In this study, it analyzed and compared the existing disposal regulations and methods of carcasses to establish the reasonableness about introducing an incineration technology. In addition, domestic and international disposal status was compared as investigating regulations or disposal law, guidelines of livestock in major developed countries. To introduce the mobile incineration facilities in domestic, it is surveyed international examples and related regulations of using and developing mobile incinerators. The results of study could be used as basic information to design and utilize a mobile incineration process for slaughter animals by deceases.
        697.
        2012.10 KCI 등재 서비스 종료(열람 제한)
        본 연구는 오른쪽 어깨관절에 칼텐본-에비엔즈컨셉 미끄러뜨림 등급Ⅱ와 Ⅲ으로 아래쪽미끄러뜨림적용시 위팔뼈머리의 이동거리 및 벌림각도(abduction angle)의 변화를 알아보고자 하였다. 미끄러뜨림 등급Ⅱ(Grade Ⅱ) 적용시 위팔뼈머리는 초기보다 아래쪽으로 5㎜ 가량 이동하였고 등급Ⅲ 적용시 8㎜ 가량 이동하였다. 이동거리에 대한 성별 비교에서는 남자가 여자에 비해 등급별로 이동거리가 높게 나타났으나 통계적으로 유의한 차이는 나타나지 않았다. 등급Ⅱ(Grade Ⅱ) 적용시 벌림각도는 초기보다 10°가량, 등급Ⅲ(Grade Ⅲ) 적용시 12°가량 증가하였다. 벌림각도에 대한성별 비교에서는 모든 등급별로 여자가 남자보다 벌림각도가 크게 나타났으나 통계적으로 유의한 차이는 나타나지 않았다.본 연구를 통해 미끄러뜨림 등급 적용시 위팔뼈머리의 운동형상학적 변화를 알아보았으며 향후 추가 연구를 통해이들 변화가 주변 구조물에 미치는 영향에 대해 알아본다면 보다 과학적인 근거중심의 치료를 기대할 수 있을 것으로사료된다.
        698.
        2012.07 KCI 등재 서비스 종료(열람 제한)
        This study analyzed mass concentrations of TSP, PM10 and PM2.5 and elemental constituents according to the isentropic backward trajectories of air parcel from Cheongwonin East Asia during the period January – October, 2011. Mass concentrations of the continental polluted airflow (CP) showed levels of TSP and PM10 mass concentrations higher than the continental background airflow (CB). Also, PM2.5 mass concentrations of anthropogenic fine particles ran higher in CP than in CB. The elemental constituents and elemental constituent ratio ended up varying depending on the origin of atmospheric aerosols generated. The average absolute content of elemental constituents reached its height in CB, the ratio of anthropogenically originating elements (PE) among the all elements (AE) analyzed marked a high in CP, and Mg+Na/AE reached its height in the oceanic airflow (OA). At the same time, TSP, PM10 and PM2.5 mass concentrations, the ratio of PM2.5/TSP and PE/AE element ratio ran higher in CP than CB. Episodes of large-scale transport of atmospheric pollutants as observed at Cheongwon were 8 cases and 22 days. The ratios of PM10, PM2.5 among TSP mass concentrations showed different results and the ratios of PM2.5 showed an increasing trend in the episodes of anthropogenic air pollution transport. Overall, dustfall episodes show a level of elemental constituents higher than those of anthropogenic air pollution.Dustfall episodes were observed to contain more of Fe, Al and Ca originating from continental soils and those of air pollution were observed to contain more of Zn, Mn, Cu and Pb. By difference in contents of absolute elemental constituents, episodes of anthropogenic air pollution showed a high PE/AE rate, and dustfall episodes a high SE/AE rate.
        699.
        2012.05 KCI 등재 서비스 종료(열람 제한)
        In this paper, we propose a cable climbing robot which can climb up and down the cables in the bridges. The robot mechanism consists of three parts: a wheel based driving mechanism, adhesion mechanism, and safe landing mechanism. The wheel based driving mechanism is driven by tooth clutches and motors. The adhesion mechanism plays the role of maintaining adhesion force by a combination of pantograph, ball screw, and springs even when the power is lost. The safe landing mechanism is developed for guaranteeing the safety of the robot during operations on cables. It can make the robot fall down with reduced speed by dissipating the gravitational forces. The robot mechanism is designed and manufactured for validating its effectiveness.
        700.
        2012.05 KCI 등재 서비스 종료(열람 제한)
        This paper introduces several mobile robots developed by using LEGO MIDSTORM for experimental studies of robotics engineering education. The first mobile robot is the line tracer robot that tracks a line, which is a prototype of wheel-driven mobile robots. Ultra violet sensors are used to detect and follow the line. The second robot system is a two-wheel balancing robot that is somewhat nonlinear and complex. For the robot to balance, a gyro sensor is used to detect a balancing angle and PD control is used. The last robot system is a combined system of a line tracer and a two-wheel balancing robot. Sensor filtering and control algorithms are tested through experimental studies.