• Journal of Ecology and Environment
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• 제29권4호
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• pp.389-398
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• 2006

To examine sediment characteristics and find anthropogenic effects on riverine wetland ecosystems, paleoecological study was carried out at Bam islands in Seoul. Three hundred cm deep sediment cores were retrieved and dated with the lamination analysis method until 36 cm depth (1986). Sediments were divided into three zones based on the depth profiles of physico-chemical variables: below 160 cm depth (before 1968), between 160 and 40cm depths and above 40cm depth (after 1986). Physico-chemical characteristics were very variable between 160 and 40cm depths and this indicates unstable sedimentation environment. Even though heavy metal concentrations were relatively low, Cd and As contents have increased continuously. Dry mass accumulation rates during $1968{\sim}1986\;and\;1987{\sim}2003$ were 140 and $21\;kg\;m^{-2}\;yr^{-1}$, respectively. This was related to flooding intensity and duration. Bulk density, water content, loss on ignition, N, C, C/N ratio were very similar to other river delta but Ca, Na and K contents were 2 to 4 times higher than others. Heavy metal contents except Pb were lower or similar to those in other studied marshes in Korea. Heavy metal and Mg contents were correlated with each other and this suggests that the source of heavy metals be parent rock. From $^{13}C$ dating dates of organic materials in sediment, it is suggested that organic matter originated from the watershed and flooding intensity in the watershed might be responsible for the source of sediments. This study provides reference data for the comparison of sediment characteristics at islands in river and for the management of Bam islands.

• Journal of Advanced Marine Engineering and Technology
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• 제35권5호
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• pp.690-699
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• 2011

A numerical model analysis was performed to analyze the stability of the mooring lines of an automatic submersible fish cage system in waves and currents. The fish cage system consisted of a 12-angled rigid frame, net cage, cover net, 12 upper floats, 12 tanks(for fixed and variable ballast), mooring lines, anchors, and a control station. Simulations were performed with the cage at the surface of the water and at a depth of 20 m. A Morison equation type model was used for simulations of the system in two configurations. The force parameters described both regular and random waves, with and without currents, and their values were input to the model. Mooring tension calculations were conducted on the mooring lines, grid lines and lower bridle lines of the cage. The stability of the mooring lines was checked under both static and dynamic conditions.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2000년도 추계학술발표논문집
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• pp.95-99
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• 2000

The domestic ports become less competitive for the out of dated equipments and inefficient information system. Specially, Inchon Port, which is the second largest port of Korea, has the point at issue such as the excessive logistics cost because of the limit of handling capacity and the chronic demurrage. In this paper to develope the simulation programs the basic input parameters such as arrival intervals, cargo tons, service rates are analyzed and the probability density functions for there variable are estimated. Also to perform the conception of continuous berth utilization, the berth and cargo classification is reconstructed. And the more actual simulation is realized by using more detailed depth representation of water The simulation model is executed based on the knowledge base and database, and is constructed using Visual Basic and Access database. Simulation results reveal that this study suitably reflect the real berth operation and waiting time of ships is shortened.

• 한국식품과학회지
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• 제28권3호
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• pp.470-474
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• 1996

The dielectric properties, dielectric constant (${\varepsilon}‘$) and loss factor (${\varepsilon}’$), of skin and pulp of fresh ginseng were measured from $25^{\circ}C$ to $67^{\circ}C$ using an open-ended coaxial probe technique for 915 MHz and 2450 MHz. Pulp and skin had dielectric constant of $30{\sim}64$ and loss factor between 10 and 20, each variable having a respective frequency dependence typical of materials with high water content. Although the loss factor was nearly constant, the dielectric constant increased as moisture content increased. The dielectric constant of ginseng pulp increased as temperature increased (temperature ${\leq}56^{\circ}C$), but any significant differences were not found in skin dielectric properties. Penetration depth for fresh ginseng were about 2 cm at 91.5 MHz and 1cm at 2450 MHz.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.659-662
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• 2004

An analysis of the AF is performed for each bridge pier exposed to ship collision. From this analysis, the impact lateral resistance can be determined for each pier. The bridge pier impact resistance is selected using a probability-based analysis procedure in which the predicted AF, from the ship collision risk assessment is compared to an acceptance criterion. In this study, the acceptance criterion is allocated to each pier using allocation weights based on the previous predictions. To determine the design impact lateral resistance of bridge components such pylon and pier, the numerical analysis is performed iteratively with the analysis variable of impact resistance ratio of pylon to pier. The design impact lateral resistance can vary greatly among the components of the same bridge, depending upon the waterway geometry, available water depth, bridge geometry, and vessel traffic characteristics.

• 한국해양학회지:바다
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• 제15권3호
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• pp.124-132
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• 2010

해양 식물플랑크톤 일차생산력의 전 지구적 중요성에도 불구하고 자료 처리상의 어려움 때문에 국내에서는 신뢰할만한 자료가 많지 않다. 식물플랑크톤 일차생산력은 시간-수심 적분 과정을 거쳐 최종적으로 단위 면적당 하루 일차생산력을 구하지만, 시간 적분에 대한 연구결과는 많지 않은 편이다. 본 연구에서는 단위 시간당 일차생산력을 시간 적분하여 하루 일차생산력을 계산하는 수학적 모델을 제시하고 새만금호를 대상으로 모델의 실효성을 검정해 보았다. 검정 결과, 시간 적분 모델이 일사량 실측치를 대입하여 합산한 결과와 잘 일치하였다. 일차생산력 계산을 위한 기초 광량 자료는 변화가 심한 일 자료보다 한 달 또는 한 주간 평균 자료를 대입하는 것이 더 신뢰성 있는 결과에 도움이 되는 것으로 판단되었다. 일차생산력 수직적분은 수직적으로 불균일한 식물플랑크톤 분포 때문에 어려움이 있으나, 엽록소 분포를 몇 가지 유형으로 분류하여 수식화한 다음, 각 수식을 시간 적분한 일차생산력 모델과 합성하여 적분하면 해결할 수 있을 것으로 판단된다.

• 물과 미래
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• 제20권2호
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• pp.139-150
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• 1987

본 연구는 우리나라의 확율강우량도 작성을 위한 수문해석기법을 개발제시하는 것을 내용으로 하고 있다. 강우량계열의 적정분포형검정과정에서는 변수변환정규분포(Y-k법)등 11개의 연속확율분포형을 적용하였으며, 각 지속기간별 연최대강우량자료에 대한 수문해석을 실시하였다. 최적분포형 선정을 위한 적합도검정은 $-test와 Kolmogorov-Smirnov test에 의거하였으며 계급구간은 등간격으로 취하였다. 서울, 인천, 부산 및 광주지점의 강우지속기간 10분, 60분, 6시간 및 24시간에 대한 연최대 강우량에 각종 확율분포를 적용하고, 분포형의 적용상 특성과 강우량 자료집단의 특성을 고려하여 최적확율분포형을 설정하였다. 이와같은 해석기법으로 설정된 최적확율분포형은 종전의 방법으로 얻어진 적정분포형 보다도 자료면에서 확장된 자료집단일 뿐 아니라 확대검정된 합리적인 결과라고 생각된다.

• 물과 미래
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• 제26권1호
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• pp.51-62
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• 1993

연유출량에 영향을 미치는 가장 직접적인 인자는 강수량인데 회귀분석을 이용한 이전의 연구에서는 유출률이 20% 미만 또는 100% 이상인 경우에는 강수와 유량자료는 이상점(outlier)으로서 분석에서 제외시킨 결과 강수량은 독립변수로서 의의가 없고 대신 유역면적을 중요한 독립변수로 포함시켰다. 본 연구에서는 유출률대신 (연강수량-연유출량)을 연증발산량의 좋은 추정치로 간주하고 우리나라에서 가능한 연증발산의 범위를 벗어나는 자료를 제외시키고 회귀분석을 한 결과 수문학적인 이론에 부합되며 결정계수가 높은 다음과 같은 회귀분석식을 얻었다. R=-518.25+0.8834P 단, R: 유출고(mm) P: 연강수량(mm) 이 회귀분석식은 cross-validation을 거친 결과 계수가 매우 안정되어 있어서 우리나라의 미계측 중소수게에서 사용할 수 있는 좋은 연유출량 추정모델로서 제안한다.

• 한국기계가공학회지
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• 제11권5호
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• pp.104-108
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• 2012

Recently, small scale hydropower needs to be developed due to its clean, renewable and abundant energy resources. However, suitable draft of hydro-turbine body in combination with differences in wheel blade shapes is not determined yet in the range of small hydropower and it is necessary to study for the effective draft in combination with type. Therefore, watermill shaped of 250mm diameter. hydro-turbine aiming 20 watt class generator is adopted in this study because of its simple structure and high possibility of applying to small hydropower. The result shows that effective draft for the turbine body is variable concerning the size of turbine and flow rate of water. Thus, the difference of water depth between fore and aft turbine body contributes to the increase of torque, angular momentum and power output.

• 한국농공학회지
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• 제38권3호
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• pp.127-136
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• 1996

The purpose of this study is to provide with information for the water resources development and management in stream management planning, such as information on the sediment trensport, design of dam and water facilities, river improvement and flood plains management. The major results obtained from the field measurement and analysis of the watershed characteristics, hydraulic and sediment characteristics are as follows ; 1. The rating curve formulas obtained from the analysis of the hydraulic characteristics data collected are ; Q-=110.563 $(H-0.474)^2$ for 0.7m$(H-0.146)^2$ for 0.4m$Sr=aX{^2} {_1} X^{c}{_2}$, in the experimental watershed.