• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.593-597
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• 2003

Multilevel power conversion technology has received increasing attention recently for high power applications. The converters with the technology are suitable for high voltage and high power applications due to their ability to synthesize waveforms with better harmonic spectrum and apply for the high voltage equipment with a limited voltage rating of device. In the family of multilevel inverters, the topologies based on cascaded H-bridges are particularly attractive because of their modularity and simplicity of control. This paper presents multilevel inverter with cascaded H-bridge for large-power motor drives. The main features of this drive 1) reduce harmonic injection 2) can generate near-sinusoidal voltages, 3) have almost no common-mode voltage; 4) are low dv/dt at output voltage; 5)do not generate significant over-voltage on motor terminal; The topology of the developed product is presented and the feasibility study of the inverter on 3300v 1MVA 7-level H-bridge type was tarried out with experiments.

• Journal of Korea Foundry Society
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• v.28 no.2
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• pp.74-78
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• 2008

An integrated riser heating equipment has been developed to control shrinkage defects originated from casting of a marine propeller. The integrated riser heating equipment is composed of up/down moving parts, heating power source parts and an integrated controller. Heat capacity putting into the riser was calculated quantitatively on the base of a heat transfer analysis, which consisted of the establishment of heating model and the theoretical analysis for heat transfer. The riser heating equipment was evaluated through arc heating and electro-slag heating method. With the results, the arc type heating method was selected by considering high thermal efficiency, inexpensive cost, and convenient workship. This equipment improves the quality of a propeller casting and the poor working environment.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.5
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• pp.433-439
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• 2012

Anticorrosive paint is the most widely used in shipbuilding and the dry film thickness is very important in terms of productivity and assurance of anticorrosive performance. However, it is difficult to achieve the recommended target film thickness because the dry film thickness depends on labor's skill in practice and is affected by a number of parameters, such as spray pressure, paint flow rate, tip size, spray distance, SVR(Solid Volume Ratio), etc. Present paper derives an empirical equation through the correlation analysis of parameters selected by spray experiments of anti corrosive painting in order to predict the coated status. Comparing the calculated results with practical data, we show that the empirical equation can successfully expect DFT(Dry Film Thickness).

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1045-1046
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• 2007

As equivalent load method of induction motor, even without connecting load, for temperature rise test has been acknowledged economic and corrective method, the method has been widely used instead of the real load method, and also international standards IEC 61986 is published in 2002. ABB, an well-known and famous electric machinery maker in the world, has been already applying the equivalent load method since 2002. HHI has been using real load method and equivalent load method for temperature rise of induction motor, it is already known that the equivalent test results is higher as $1-5^{\circ}K$ than that of real load test. But, quantity analysis for the reason of the temperature rise is not satisfied sufficiently. So, in this paper, quality analysis and also quantity analysis was conducted.

• Special Issue of the Society of Naval Architects of Korea
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• 2015.09a
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• pp.69-73
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• 2015

An evaluation of the accidental limit state (ALS) for design of a semi-submersible drilling rig is one of the essential design requirements as well as ultimate limit state (ULS) and fatigue limit state (FLS). This paper describes the ALS evaluation on the explosion accident at shale shaker room of semi-submersible drilling rig. There are three steps for the ALS evaluation such as structural analysis at concept design, risk based safety design and structural analysis at detailed design. For the ALS evaluation at concept design, conceptual explosion overpressure from the Rule guided by the classification society was used in the structural analysis that was carried out using LS-DYNA. To set up the design accidental load (DAL), explosion analysis was carried out using FLACS taking safety barriers into consideration. Then, the structural analysis was carried out applying DAL for the ALS evaluation at detailed design. Through the ALS evaluation on the explosion at shale shaker room, the importance of the risk based safety design was described.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.109.2-109
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• 2002

$\textbullet$ Development of a HILS System as a High-Speed Prototyper $\textbullet$ Introduction of Major Components $\textbullet$ Design Procedure of Control Algorithm Using the HILS System $\textbullet$ A Design Example: Collision Detection

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.297-298
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• 2012

본 논문에서는 장주기(Long-Term, LT) 배터리 에너지 저장 시스템(Battery Energy Storage System, BESS)용 1MW급 PCS의 계통연계형 멀티레벨 컨버터 및 제어 시스템을 소개하고, 현장 시험을 통한 타당성 검증 결과를 제시한다. 또한 1.5 MW 풍력발전기 출력과 연계한 잉여 전력 충전 및 전력 피크 시간대 방전(Energy Shift) 기능을 통해 피크 부하 시간대 전력 문제에 효과적으로 대응할 수 있음을 확인하였다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.513-514
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• 2007

최근 들어, 디지털 보호 계전기의 계측 및 계전 기능 외에 운용 프로그램 및 사고파형 분석 기능 또한 중요시 하고 있는 실정이다. 이를 위해 저장된 사고파형을 분석하기 위한 프로그램 개발이 요구되어 지고 있으며 본 논문에서는 다양한 기능을 가지는 사고파형 분석 프로그램을 소개한다.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.93-94
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• 2016

산업용 인버터는 운전상황에 따라 캐리어 주파수와 부하전류가 변하게 되며, 이 때 제어기 내부 회로 소자의 Propagation 지연에 따른 Dead Time의 왜곡 그리고 출력전류크기에 따른 전략소자 내부의 전압강하 등에 의해 전압의 왜곡이 발생하여 전동기 토크진동의 원인이 된다. 이를 방지하기 위하여 상황에 따라 출력전압을 보상해야 한다. 특히 전략소자의 전압강하는 전류의 크기에 따라 변하므로 캐리어 주파수에 의한 보상뿐만 아니라 부하전류의 크기에 따른 출력전압을 보상해야 한다. 본 연구에서는 캐리어 주파수 변화에 따른 전압보상량을 기준으로 출력전류 크기에 따른 보상방법 중 비선형적으로 변하는 저전류 영역에서의 전력소자 진압 강하량을 개선하는 보상방법을 제시하였고, 그 유효성을 실험을 통해 검증하였다.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.365-368
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• 2001

The advantage of the squirrel cage induction motor is the brush less rotor. This advantage for operation and maintenance turns out to be a disadvantage for the detection of the cage rotor bar and endring defects, which means that the detection of cage faults is due to the measurement and analysis of only the stator input signals. The monitoring task in an inverter drive is complicated mainly because the voltage and current waveforms are nonsinusoidal and the high dv/dt values from fast switching inverterd distort the measurements. In this paper, we are going to discuss the detection method of broken rotor bar of the inverter fed squirrel cage induction motor by the motor current signature analysis(MCSA) and the opening terminal voltage signal analysis.