• Journal of Korean Society of Coastal and Ocean Engineers
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• v.13 no.3
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• pp.230-236
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• 2001

The numerical investigations on the wave-screening characteristics of floating breakwaters are presented. The fluid motion is idealized as linearized, two dimensional potential flow. A finite element model is adopted to analyze the performance of floating breakwaters. Numerical experiments are carried out for two type floating breakwater. One is a conventional pontoon type breakwater with rectangular cross-section, and the other is a side float breakwater which consists of two rectangular shaped floats connected to each other by a frame. To improve the performance of the floating breakwaters, especially for long-period wave conditions, numerical experiments are carried out for the cases attaching the thin plates at the bottom of folats in the vertical direction.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.5
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• pp.457-464
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• 2010

Representative methods for removing spilled oil include mechanical skimming, chemical treatment, burning at the surface of the spilled oil, and microbiological degradation. Among these methods, mechanical skimmer is the most efficient. Mechanical skimming can be classified into the following categories: belt-type, disk-type, weir-type, drum-type. We designed models with a submerged orifice for use in our experiments, for an objective and systematic evaluation of the recovery efficiency of mechanical skimming. Basically, oil is lighter than seawater and hence tends to float on the surface of the latter if there is sufficient time for floating. The present skimmer is kind of wear-type with the submerged orifice for seawater to be squeezed through, minimizing water content in the tank. From the experimental results, we identify the parameters that influence the oil recovery rate and recovery efficiency. The recovery efficiency can be enhanced by increasing the thickness of the oil layer in the first oil accumulative tank.

• Proceedings of the Korea Water Resources Association Conference
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• 2002.02a
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• pp.309-324
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• 2002

국내의 경우 관개용수의 대부분은 벼생육을 위한 논의 관개응수로 사용되고있다. 농업용수 이용은 약 150억㎥/year, 이는 하천유지수량을 제외한 전체 물이용량 237억㎥/year의 약 63%에 해당한다. 최근 물절약은 가장 중요한 사회, 경제적인 이슈 중의 하나로 인식되고 있다. 그러나, 국내의 경우 관개효율은 여전히 낮아 약 35%의 관개용수가 손실되는 것으로 추정되고있다. 비록 관개에서의 물절약이 시급한 문제이기는 하지만 용수손실 원인에 따른 손실량에 대한 정량적인 연구가 행해지지 않았었다. 손실 원인에 따른 손실량을 계측하기 위한 시험지구로 경기 평택의 이동지구를 선정하였다. 시험지구의 주수원공으로는 유역면적 9,440ha, 관개면적 2,027ha인 이동저수지이며 상류유역에 미산 및 용덕저수지가 위치하고 관개지구내에 원암 및 은산양수장이 있다. 시험지구의 계측시설은 강우량 계측을 위하여 자기강우계를 설치하였고 저수위, 하천수위 및 응배수로의 수위 측정을 위하여 수위계를 설치하였다. 강우계는 4개소에 설치되었으며 수위계는 26개소에 설치되었다 강우계는 지구내의 저수지 및 양수장 관리사 부근 4개소에 전도형 자기우량계를 설치하였다. 수위계 26개소 중에서 저수지의 저수위 계측지점이 3개소이며 하천수위 계측지점이 2개소 그리고 용배수로의 간선수로 시점부와 간지선 분기점 등의 주요지점에 21개소의 계측지점이 있다. 모든 계측지점의 계측기에는 자체 혹은 별도의 자료저장용 데이터로거가 부착되어 현장 계측자료를 저장하도록 설치 되어있다. 강우계는 전도형강우계(tipping bucket type)이며 수위계는 계측지점의 특징에 따라 여러종류의 수위계측기가 설치되었다 예를들어 초음파수위계(ultrasonic-wave type), 부표식수위계(float type) 그리고 압력식수위계(Pressure type)가 설치되어 있다. 현장 계측기의 전원은 한국전력 전원 혹은 태양전지 및 축전지를 사용하였다. 수위계측지점의 유량을 환산하기 위하여 계측지점의 단면조사와 유속측정을 통해서 수위-유량관계(rating curve)를 규명하였다. 시험지구의 관개효율 및 용수손실 규명 등에 관한 기본자료를 수집하기 위해서는 계측시스템의 운영은 장기간으로 지속 되어야 한다

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.3
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• pp.233-240
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• 2023

p-type Tunnel Oxide Passivating Contacts (TOPCon) solar cell is fabricated with a poly-Si/SiO_x structure. It simultaneously achieves surface passivation and enhances the carriers' selective collection, which is a promising technology for conventional solar cells. The quality of passivation is depended on the quality of the tunnel oxide layer at the interface with the c-Si wafer, which is affected by the bond of SiO formed during the subsequent annealing process. The highest cell efficiency reported to date for the laboratory scale has increased to 26.1%, fabricated by the Institute for Solar Energy Research. The cells used a p-type float zone silicon with an interdigitated back contact (IBC) structure that fabricates poly-Si and SiO_x layer achieves the highest implied open-circuit voltage (iV_oc) is 750 mV, and the highest level of edge passivation is 40%. This review presents an overview of p-type TOPCon technologies, including the ultra-thin silicon oxide layer (SiO_x) and poly-silicon layer (poly-Si), as well as the advancement of the SiO_x and poly-Si layers. Subsequently, the limitations of improving efficiency are discussed in detail. Consequently, it is expected to provide a basis for the simplification of industrial mass production.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.2
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• pp.172-178
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• 2002

This study presents a dynamic simulation of a purse seine net behavior Mathematical model suitable for purse seining, which is based on data from a series of previous simulations, various field experiments, is modelized as a set of mass-spring system. In this model, a number of meshes are approximated as one mass point, each of which connected to its neighbors by massless springs, the equations of motion are derived from considering internal force from the springs and external forces such as resistance and gravitation. This simulation shows the quantitative state on every mass point of the net and purse line during the shooting and pursing phases. So it is possible that performance of a purse seine net be analyzed using various and evolving parameters such as the shooting speed, the hauling speed, the size or type of the sinker, float and twine, also the hanging ratio etc.

• The Journal of the Convergence on Culture Technology
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• v.2 no.4
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• pp.55-59
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• 2016

In this paper, we propose a system for monitoring and controlling the level of the rainwater tank by installing an underground storage tank as one of ways to increase the utilization rate to solve the water shortage and imbalance. For this purpose, a microprocessor of ATMEL's Atmega 128 is used for the control module, and the sensor capable of measuring the water level uses a float type level sensor which is a kind of tactile sensor. In particular, the level sensor outputs the output in a industry standard dimension, so that the compatibility is improved so as to replace the existing sensor.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2003.04a
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• pp.108-111
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• 2003

Altimeter data from the Topex/Poseidon (T/P) were analyzed to study the sea surface circulation and its variability in the North East Asian Seas. Long term averaged T/P sea level time series data where compared with in situ sea level measurements from a float-operated type tide gauge around of south Korea and Japan. Tf data are a large contaminated by 60-day tidal aliasing effect, very near the alias periods of M2 and S2. When this 60-day effect is removed, the data agree well with the tide gauge data with 4.6 cm averaged RMS difference. The T/P derived sea level variability reveals clearly the well-known, strong current-topography such as Kuroshio. The T/P mean sea level of North Pacific (NP) was higher than Yellow Sea (YS) and East Sea (ES). The T/P sea level variability, with strong eddy and meandering, was the largest in eastern part of Japan and this variability was mainly due to the influence of bottom topography in Kuroshio Extension area.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.697-701
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• 1996

King Sejong's Striking water-clock which brought in use on the first of July in 1434 was mainly composed of timekeeping and time announcing parts signalling twelve double-hours, and five night-watches and night-watch-divisions automatically by means of ball-operating jackworks. The clock was arranged with dual timekeeping system, the one for a full day(twelve double-hours) and the other for five night-watches achieving twelve double-hours and one-hundred interval horary systems. The vessels were arrayed in inflow-type water-clock, a large reservoir on the highest story, a constant-level tank for supplying water to the measuring vessel evenly in the middle, and the lowest tank to receive water from the above constant-level tank. An indicator-rod on the float was raised upwards depending on the water-level increase to show timing scales and also to release small bronze balls from the ball-rack mechanisms implanted on the measuring vessel to signal timing intervals.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.300-303
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• 2001

The first 7 years of altimeter data from the TOPEX/POSEIDON (T/P) were analyzed to study the surface circulation and its variability in the East Asian Marginal Seas. Long term averaged T/P sea level time series data where compared with in situ sea level measurements from a float-operated type tide gauge around of south Korea and Japan. T/P data are a large contaminated by 60-day tidal aliasing effect, very near the alias periods of M2 and S2. When this 60-day effect is removed, the data agree well with the tide gauge data with 4.6 cm averaged RMS difference. The T/P derived sea level variability reveals clearly the well-known, strong current-topography such as Kuroshio. The T/P mean sea level of North Pacific (NP) was higher than Yellow Sea (YS) and East Sea (ES). The T/P sea level valibility, with strong eddy and meandaring, was the largest in eastern part of Japan and this variability was mainly due to the influence of bottom topography in Kuroshio Extention area.

• Geomechanics and Engineering
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• v.21 no.2
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• pp.133-142
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• 2020

Submerged floating tunnel (SFT) is a type of tunnel which causes the tunnel segments to float in the water. When the SFTs are connected to the ground, the connection between the SFT and the subsea bored tunnel is fragile due to the difference in behavioral characteristics between the two types of tunnels. Therefore, special design and construction methods are needed to ensure the stability of the area around the connection. However, since previous research on the stability of the connection site has not been undertaken enough, the basic step necessitates the evaluation of ground behavior at the shore connection. In this study, the numerical analysis targeting the shore connection between the subsea bored tunnel and the SFT was simulated. The strain concentration at the shore connection was analyzed by numerical simulation and the effects of several factors were examined. The results showed the instability in the ground close to the shore connection due to the imbalance in the behavior of the two types of tunnels; the location of the strain concentration varies with different environmental and structural conditions. It is expected that the results from this study can be utilized in future studies to determine weak points in the shore connection between the submerged floating tunnel and the subsea bored tunnel, and devise methods to mitigate the risks.