• Environmental engineer
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• v.20 s.209
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• pp.94-95
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• 2004

• Journal of Korean Society of Water and Wastewater
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• v.30 no.2
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• pp.187-196
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• 2016

In this study, a newly developed agitator with hydrofoil impeller applied to actual biological process in advanced wastewater treatment plant was evaluated. Several series of experiments were conducted in two different wastewater treatment plants where actual problems have been occurred such as the production of scums and sludge settling. For more effective evaluation, computational fluid dynamics (CFD) and measurements of MLSS (Mixed Liquor Suspended Solids) and DO (Dissolved Oxygen) were used with other measuring equipments. After the installation of one unit of vertical hydrofoil agitator in plant A, scum and sludge settling problems were solved and more than seventy percent of operational energy was saved. In case of plant B, there were three cells of each anoxic and anaerobic tanks, and each cell had one unit of submersible horizontal agitator. After the integration of three cells to one cell in each tank, and installation of one vertical hydrofoil agitator per tank, all the problems caused by improper mixing were solved and more than eighty percent of operational energy was found to be saved. Simple change of agitator applied to biological process in wastewater treatment plant was proved to be essential to eliminate scum and sludge settling problems and to save input energy.

• Journal of Navigation and Port Research
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• v.42 no.4
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• pp.267-276
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• 2018

Leisure boat design requires a comprehensive approach combining emotion with engineering technology, and requires designers to constantly exchange information and cooperate with engineers during the design process. This study suggests a design process and design methods suitable for leisure boat design. The design process consists of five steps: understanding, exploring, analyzing, developing, and validating based on the designer's thinking process. Design methods were suggested to foster collaboration and communication between designers and engineers at each phase. This process and methods were applied to the hydrofoil-boat design and evaluated. The results suggest that the design methods promote cooperation and communication between the designer and the engineer and facilitate mutual understanding and trust.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.678-683
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• 2003

Mixers are used in various industrial fields where it is necessary to intimately mix two reactants in a short period of time. However, despite their widespread use, complex unsteady flow characteristics of industrial mixers are not systematic investigated. The present study aimed to clarify unsteady flow characteristics induced by various impellers in a tank. Impellers are pitched blade turbine and neo-hydrofoil turbine types. A high speed CCD camera and an Ar-Ion laser for illumination were adopted to clarify the time-dependent flow characteristics of the mixers. The rotating speed of impellers increased from 6Hz to 60Hz by 6Hz. The maximum velocity around PBT impeller is higher than the hydrofoil type impeller. These two types of turbine shows that typical flow characteristics of axial turbine and suitable for mixing high -viscosity materials.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.05a
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• pp.156-157
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• 2018

본 연구는 레저보트의 디자인과정에서 디자이너가 보트 제작자 혹은 엔지니어와 정보교환이나 협력을 통해 창의적인 디자인 안을 산출할 수 있는 디자인프로세스와 디자인방법을 제시하는 것이 목적이다. 연구내용으로는 제품디자인 및 환경디자인에서 널리 사용되는 서비스디자인을 바탕으로 한 디자인프로세스를 제안하고 이 과정에서 엔지니어와 정보교환과 협력이 자연스러우면서 체계적으로 이루어질 수 있는 단계별 디자인방법을 제안한다. 다음으로 이 디자인방법을 레저보트의 하나인 하이드로포일보트의 디자인에 직접 적용하여 최종 디자인 안을 산출하고 이 디자인에 참가한 엔지니어가 직접 경험한 디자인방법을 평가하며 그 후에 최종 디자인 안과 디자인방법에 대해 전문가 평가를 실시한다.

• The KSFM Journal of Fluid Machinery
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• v.17 no.5
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• pp.60-66
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• 2014

Most tidal current turbine designs are focused on medium and large scale for deep sea, less attention is paid in low water level channel, such as the region around the islands and costal sea. This study is to develop a horizontal axis tidal current turbine rotor blade which is applicable to low water level island region in southwest coastal region of Korea. In this study, the hydrofoil NACA63-415 and NACA63-817 are both adopted to analyze. The blade using NACA63-817 showed the higher maximum power coefficient and good performance at small TSR (Tip Speed Ratio), which gives the blade more advantages in operating at lower water level channel, where is characterized by the fast-flowing water. The cavitation pattern of hydrofoil is predicted by the CFD analysis and verified that the NACA63-817 is the appropriate hydrofoil in the test site of tidal current resource and the hydrofoil showed considerable performance in avoiding cavitation.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.863-868
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• 2003

Mixers are used in various industrial fields where it is necessary to intimately mix two reactants in a short period of time. However, despite their widespread use, complex unsteady flow characteristics of industrial mixers are not systematic investigated. The present study aimed to clarify unsteady flow characteristics induced by various impellers in a tank. Impellers arc hydrofoil turbine and neo-hydrofoil turbine types. A high speed CCD camera and an Ar-Ion laser for illumination were adopted to clarify the time-dependent flow characteristics of the mixers. The rotating speed of impellers increased from 6Hz to 60Hz by 6Hz, The maximum velocity around neo-hydrofoil impeller is higher than the hydrofoil type impeller. These two types of turbine shows that typical flow characteristics of axial turbine and suitable for mixing high-viscosity materials.

• The Journal of the Acoustical Society of Korea
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• v.26 no.5
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• pp.220-226
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• 2007

The two major objectives of acoustical measurements in a cavitation tunnel are measuring the noise levels generated by rotating propellers behind a hull and localizing possible noise sources in order to reduce noise levels. Propeller noise measurement experiments were performed in MOERI cavitation tunnel at December, 2006. In order to put the propeller into cavitating conditions, a wake-generating dummy body was devised. In addition, ten hydrophones are put inside a wing-shaped casing in order to minimize the unexpected flow induced self noise around hydrophone itself. After measuring both of the noises of the rotating propeller behind the dummy body and signals generated by a virtual source, respectively the data were matched field processed using the frequency incoherent Bartlett processor to localize noises on the propeller plane. In this paper, we presented the measured noise analysis and the localization results.