• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.26 no.10
• /
• pp.766-770
• /
• 2013

This paper tried to develop a BLDC electric motor securing the 800 W-level watertight structure for driving the outboard motor. For this purpose, this paper developed a high-efficient controller-integrating BLDC electric motor system for underwater propulsion and designed and developed a triple watertight structure. Besides, this study developed a outboard motor integrating motor, propeller and controller based on the production of a controller for BLDC motor which can the speed control by selecting low-voltage, high-current power element. The characteristics of developed outboard motor were 24 V input voltage, over 800 W motor output, and max. 3,000 rpm motor, and 84.9% motor efficiency, and the developed outboard motor could secure the watertight structure in 5 m in water depth.

• Journal of the Korean Society for Precision Engineering
• /
• v.12 no.1
• /
• pp.68-77
• /
• 1995

The two-dimensional pressure distribution, which is the most important parameter in the casting cleaning installations(CCI), was analyzed using the K-FIX computer program for two-phase flow. Modelling was done using R-Z coordinates for the initial and boundary conditions which don't have periodic influx and efflux, and also there was the electric discharge due to high pressure and temperature. The marked particles were introduced to prodict the structure and the size of main and local moving surfaces. The initial and boundary conditions were modified due to the internal structure of CCI.From the results of numerical analysis, it was shown that the maximum pressure on casting was increased with the increase of a water level. The pressure on casting in the radial direction was higher than that in axial direction. Also, it was proved that by introducing the marked particles it was possible to predict the surface structure in case of two-phase flow.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2014.10a
• /
• pp.236-239
• /
• 2014

Most naval underwater weapon system can be simplified to a circular cylindrical structure which has vibrating machineries inside. In order to predict efficiently the total acoustic radiation power of cylindrical structure, surface velocity is measured and radiation efficiency of surface element is calculated. Then, they are substituted to the surface pressure in the simplified Helmholtz integral equation which assumes acoustic far-field and plane-wave approximation at the surface. Surface velocity and total acoustic radiation power for a submerged cylinder are measured in water-tank. In this example, it is found that total acoustic power output obtained from the prediction is in good agreement with that of measurement in mid-high frequency range.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2012.10a
• /
• pp.925-926
• /
• 2012

• Proceedings of the KIPE Conference
• /
• 2000.07a
• /
• pp.657-660
• /
• 2000

전력연구원은 원자로 내부에 적용하기 위한 소형경량의 수중로봇을 개발하기 위한 준비작업으로 자이로를 이용한 수중로봇 조향장치를 개발하고 있다 이장치는 자이로 3개를 조합한 모듈을 서보가 회전시켜 일정한 방향으로 서보의 회전속도에 비례하는 회전토크를 발생하도록 고안되었다 발생된 토크는 작용/반작용의 원리에 의해 서보가 부착되어있는 로봇본체에 작용한다. 이장치를 이용하면 수중로봇의 중심에서 Yaw와 Pitch를 제어할 수 있는 토크가 발생하고 좁은 공간에서 신속한 자세변환이 가능하다 본 고에서는 자이로 조향장치의 구조와 이론적 배경 및 시뮬레이션 결과를 소개한다.

• The Journal of the Acoustical Society of Korea
• /
• v.17 no.2
• /
• pp.56-62
• /
• 1998

전기-기계변환효율이 좋은 PZT를 송신용으로, 대역특성이 우수한 PVDF를 수신용 으로한 PZT/PVDF 복합구조 수중초음파 트랜스듀서를 제안하고, 외부는 PZT, 내부는 PVDF로 된 동심원형의 트랜스듀서를 설계·제작하여, 그 특성을 이론적, 실험적으로 파악 하였다. 삽입손실과 임펄스 응답파형에 대한 등가회로해석 및 측정결과로부터 제안한 트랜 스듀서의 특성, 특히, 대역폭이 종래의 PZT 단일소자에 의한 트랜스듀서보다 향상될 수 있 음을 알았다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2013.04a
• /
• pp.178-179
• /
• 2013

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2000.04a
• /
• pp.81-88
• /
• 2000

Unlike structures in the air, the vibration analysis of a submerged or floating structure such as offshore structures or ships is possible only when the fluid-structure interaction is understood, as the whole or part of the structure is in contact with water. Specially, the importance of the added mass is not necessary to say like the submerged vehicle, all of the hull body, is positioned in the water. This paper introduce two method to find natural frequency in consideration of fluid-structure modal coupled vibration analysis. The purpose of this study is to analyze of the vibration characteristic of submerged vehicle to obtain the anti-vibration design data, which could be used in the preliminary design stage data. Underwater pressure hull of submerged vehicle is used as the model of this study. The F.E.M model is meshed by shell and beam element. Also, considering of the inner hull weight, mass element is distributed in the direction of hull length. Numerical calculations are accomplished using the commercial B.E.M code. The characteristics of natural frequency(eigenvalues), mode shape(eigenvectors) and frequency-displacement response are analyzed. The results of this study will be used as the useful design data in preliminary anti-vibration design stage.

• Journal of Conservation Science
• /
• v.31 no.3
• /
• pp.279-285
• /
• 2015

The purpose of this study was to analyze radiocarbon dating, using wiggle match, of a wooden board from Yeongheung-do shipwreck excavated from Yeongheung-do in Incheon Ongjingun. The result of wiggle matching for 5 decennial tree-ring block samples of the hull bottom board produced ${\pm}2{\sigma}$ radiocarbon date (95.4% confidence interval) as A.D. 710~730 or A.D. 750~774. It indicated that the Yeongheung-do shipwreck belonged to the early or middle of the 8th century. Radiocarbon dating results confirmed the date speculated by archaeologists according to ship structure and pottery style.

• Magazine of the Korea Concrete Institute
• /
• v.11 no.2
• /
• pp.231-239
• /
• 1999

When the concrete is cast at the sea, there are lots of restrictions in the working process being different from in land, and the concrete is suffered from the physical and chemical action in terms of marine environment. The compressive strength was measured after antiwash out underwater concrete mixed with fly ash had been cast and cured in order to produce the endurable high performance concrete, and then its characteristic was discussed by comparing one cured in air with in fresh water, and the effect of fly ash usage under the properly controled sea water temperature of $15{\pm}3^{\circ}C$ was also covered. The present work showed that the proper usage of fly ash was obtained at the condition of around 10% of substituted binder weight under the structure required the early age strength, and at the condition of over 40% if considering its durability and economy.