• Proceedings of the Korean Society of Computer Information Conference
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• 2014.07a
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• pp.249-252
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• 2014

본 논문에서는 IMU를 이용한 6자유도 모바일 로봇을 설계하고 성능을 평가해 보았다. IMU를 이용하여 로봇의 Roll과 Pitch 각을 측정하여 모바일 로봇의 이동경로 경사각을 측정하여 지면이 수평 일 때 모바일 로봇의 6바퀴 모두 항상 지면과 닿아 있는 상태를 유지한다. 또한 오르막과 내리막일 경우 로봇의 동역학에 의한 최소한의 에너지를 유지하여 이동이 가능하도록 하기위한 로봇의 제어기를 설계하고 그 성능을 평가해 보았다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.10
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• pp.985-993
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• 2015

Free-piston Stirling engines (FPSEs) have attracted much attention in the renewable energy field as a key device in the conversion from thermal to mechanical energy, and in the recycling of waste energy. Traditional Stirling engines consist of two pistons that are connected by a mechanical link, while FPSEs are formed as a vibration system by connecting each piston to a spring without a physical link. To ensure the correct design and control of operations, this requires elaborate dynamic-performance predictions. In this paper, we present the performance-prediction methodology using a linear and nonlinear dynamic analytical model considering the external load of FPSEs. We perform linear analyses to predict the operating point of the engine using the root locus technique. Using nonlinear analysis, we also predict the amplitude of pistons by performing numerical integration considering both the linear and nonlinear damping terms of the external load. We utilize the predicted dynamic behavior to predict the engine performance. In addition, we compare the experiment results and existing model predictions for RE-1000 to verify the reliability of the analytical model.

• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.81-82
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• 2014

산업계에서 많이 사용되는 고압 전동기는 일반적으로 관성이 크므로, 인버터 입력 전원의 고장 또는 정전 사고 후 복전 시, 전동기를 멈추고 재기동하기까지 오랜시간이 걸린다. 이러한 재기동 시간을 줄이기 위해, 고압 전동기를 멈추지 않고, 자유 회전 상태에서 재기동이 가능한 플라잉 스타트(flying start) 기능이 요구된다. 본 논문에서는 전압 측정 장치를 사용한 플라잉 스타트 방법을 제안한다. 제안한 방법은 전압 측정 장치를 통해 측정된 전동기의 잔류 전압 정보를 사용하여 전압의 크기, 주파수, 위상을 보상한다. 자사의 고압 인버터를 사용하여 실험을 통해 그 유효성을 검증하였다.

• Journal of Navigation and Port Research
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• v.28 no.5
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• pp.353-358
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• 2004

A transient irregular wave was designed based on ISSC spectrum The designed wave was generated in the towing tank and ,the roll motion of a model was measured A method to predict the maximum roll motion, expected in the short-term sea state, was investigated with comparison of the theoretical and experimental results.

• Annual Conference of KIPS
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• 2023.05a
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• pp.507-509
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• 2023

최근 딥러닝은 도로 CCTV 동영상의 교통사고 검출에 널리 사용되지만 일인칭 동영상의 교통사고 검출은 분명히 어렵다. 일인칭 동영상은 역동적이고 시야가 제한되어 있기 때문이다. 본 논문에서는 일인칭 동영상을 분석하여 교통사고를 검출하는 방법을 제시한다. 이 방법은 교통 표현 특성을 분석하는 것 외에도 의미를 이해하고 교통 장면을 인코딩한다. 프레임의 표현 특징은 각 프레임 상의 물체의 특징과 물체의 위치 관계의 공간적 숨겨진 특진을 학습함으로써 얻어진다. 그 후에 프레임 표현 특징과 교통 장면의 특징이 연결되어 GRU 실행기에 공급된다. 여러 GRU 실행기는 분석한 후 사고가 발생했는지 확인된다. 이 방법은 높은 역학과 제한된 시야 문제를 효과적으로 해결한다.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.1
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• pp.45-64
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• 1993

This paper dealt with the application of a numerical method developed by the authors using the matching method proposed in the previous paper on "The Nonlinear motions of cylinders(I)[16]", and Cauchy's theorem to the problems associated with hydrodynamic forces acting on a heaving cylinders translating in a calm water and also motions of cylinders in waves. In spectral method. body boundary condition in submerged case is satisfied exactly but one in floating case is not satisfied exactly. In the numerical code developed here, the boundary condition at the free-surface and body surface is satisfied exactly at its instaneous position. It is of interest to note that the present scheme could be applied to a free-surface-piercing body without experiencing a difficulty in the numerical convergence. The computed results are compared with other results([6], [12]).

• Journal of Digital Convergence
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• v.14 no.12
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• pp.583-590
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• 2016

This study aims to suggest a desirable dietary methods based on the oriental medicated dietary effects based on the schema of four qi and five flavors of foods originated from the yin-yang and five phase theory through clear understanding of the theory of oriental medicated dietary in a modern point of view, and through experimental analysis on the nutrient and dietary effect of 4 medicinal plants. We expect it can show us the way for promoting more healthy life styles and for preventing adult diseases by following our own medicated dietary theory. We should develop our own culinary and dietary culture which is suitable for our physical and genetic conditions for our healthy and happy lives. To successfully develop and introduce them, we should analyze their dietary effects scientifically based on both the theory of nutrialogy and the oriental medicated dietary in a modern point of view.

• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.1
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• pp.57-62
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• 1990

This paper deals with the flow caused by a two-dimensional pulsating source, which moves with a constant horizontal speed beneath the free surface. The analysis is based on lincar potential theory including surface tension effects. In the case of subcritical reduced frequencies $\tau<1/4(\tau=U_{\omega}/g$, U=constant speed, $\omega$=circular frequency, g=gravitational acceleration), six wave components arc found. Two of them are largely affected by surface tension, which propagate ahead of the source in the direction of and opposite to the steady translation, respectively. The rest are almost identical with those found by Haskind(1954), i.e. for which the surface tension effect is negligible. For low oscillation frequencies, the resonant frequency still exists at $\tau$ only slightly greater than 1/4. For oscillation frequencies greater than $\nu(={\omega}^2/g)>20$, the surface tension effect is so significant that it disperses generated waves and consequently the singular phenomenon is removed. However, in addition to the gravity breaking, capillary breakings occur when the translation speed coincides with the minimum capillary celerity.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.1
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• pp.81-86
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• 1996

Subsea pipelines have an important role in the overall tasks of offshore oil and gas production but arc exposed to various hazards with high potential risks of damage resulting in serious economic loss and impact on ocean environment. In this paper, the dynamic free span is analysed, which is one of main risk factors against the safety of subsea pipelines and the allowable length of dynamic free span which is important for the design of subsea pipelines is determined. The allowable free span length is examined by considering the relationship between vortex shedding frequency and natural frequency of pipeline free span, and the variation of the allowable length is analysed for different boundary conditions of pipe ends. The free span is regarded as a beam on elastic foundations and the boundary condition of the beam is generalized by modelling as restrained by linear and rotational spring at each end. A non-dimensionalized curve is obtained to facilitate the determination of exact allowable length of dynamic free span for subsea pipelines and is applied to the pipelines which is to be installed in the gas fields of the south of East Sea of Korea.

• Journal of the Society of Naval Architects of Korea
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• v.28 no.2
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• pp.118-131
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• 1991

The effects of free surface on vortex shedding phenomena around a bluff body were studied by both numerical simulation and flow visualization experiments. A vortex method, which approximates the vorticity field as the sum of discrete vortices; was used for the numerical simulation. Flow visualization experiments were performed in the KRISO cavitation tunnel. Hydrogen bubble was used as illumination material. Free surface elevation was also measured during experiments. The hydrodynamic drag and lift were predicted by numerical simulation. The predicted period of vortex shedding was compared with the results of experiments.