• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.113-116
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• 2009

Full-HD 구현이 가능하고, 패널 전체에 priming 방전을 동시에 일으킬 수 있는 새로운 고속구동법인 표시기간 중첩 프라이밍 방전 기술의 초기화 펄스 특성을 연구하였다. ramp 펄스를 이용한 약방전으로 초기화 방전을 일으킬 경우 램프 기울기가 작아질 수록 불필요한 광을 줄일 수 있어 명암비가 높아지므로 프라이밍 펄스폭을 증가시키는 것은 매우 중요한 일이다. 본 논문에서는 ramp의 기울기를 변화시키며 안정적인 표시방전이 유지되는 ramp 펄스폭을 실험을 통해 확인하였고, 그 결과 $200{\mu}s$(ramp 기울기 $1.45V/{\mu}s$)의 ramp 펄스폭에서도 표시방전이 안정적으로 발생한다는 것을 알았다.

• Journal of Navigation and Port Research
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• v.27 no.4
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• pp.351-357
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• 2003

Evaluating the risk of collision quantitatively plays a key role in developing the expert system of navigation and collision avoidance. This study analysed theoretically and thoroughly how to determine the gradient coefficients as described in the new evaluation of collision risk using sech function, and suggested the appropriate values as applicable.

• The Journal of the Korea Contents Association
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• v.9 no.4
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• pp.347-354
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• 2009

The stone pagodas include small internal spaces such as holes of Buddha's bones generally and the space's positions and sizes can make an influence on the maintenance of the stone pagoda. Also, inclined angles of the stone pagodas are an important factor to be considered to preserve them. In this paper, the Junghyesaji thirteen-storied stone pagoda subjected to its weight was analyzed through the finite element method to investigate the weakest location of the pagoda and study how size variation of internal spaces and slope variation influenced the weakest location. And criterions were proposed to examine the safety of the stone pagoda along the size variation of the internal spaces and the slope variation in view of the deflections and the stresses to examine fractures of the pagoda.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.117-123
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• 2018

In this study, we suggest a fast image reconstruction scheme using Poisson equation from image gradient domain. In this approach, using the Poisson equation, a guided vector field is created by employing source and target images within a selected region at the first step. Next, the guided vector is used in generating the result image. We analyze the problem of reconstructing a two-dimensional function that approximates a set of desired gradients and a data term. The joined data and gradients are able to work like modifying the image gradients while staying close to the original image. Starting with this formulation, we have a screened Poisson equation known in physics. This equation leads to an efficient solution to the problem in FFT domain. It represents the spatial filters that solve the two-dimensional screened Poisson model and shows gradient scaling to be a well-defined sharpen filter that generalizes Laplace sharpening. We demonstrate the results using a discrete cosine transformation based this Poisson model.

• Journal of the Korea Society of Computer and Information
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• v.14 no.7
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• pp.41-47
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• 2009

A solution to the problems of recognizing as one spot or detection failures for complex regions, in which many spots representing proteins are overlapped and saturated, is suggested. The accumulated gradients of each point in complex regions are calculated, and the resulting accumulated gradient image segmented using watershed technique. The suggested solution show better and efficient result than existing method for spot separation, detects more protein spots hidden in the image of 2-dimensional electrophoresis, and expands the scope of prediction.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.1
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• pp.26-32
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• 2014

In this study, DC (Direct current) type steam plasma igniter is developed for effective ignition of high-energy density metal aluminum and gas temperature is measured by emission spectrum of OH radical. Because of the ultra-high gas temperature, the DC plasma jet is measured by Boltzmann plot method which is the non-contact optical technique and spectrum comparison-analysis. And both methods were applied to experiment after accurate verification. As a result, we could identify that plasma jet temperature is 2900 K ~ 5800 K in the 30 mm range from the nozzle tip.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.569-574
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• 2020

Though the discontinuous Galerkin (DG) method has been developed and applied to shallow water equations mainly in explicit schemes, they have been criticized for the limitation in treatment of bottom friction terms and severe CFL conditions. In this study, an implicit scheme is devised and applied to some representative benchmark problems. The linear triangular elements were employed and the Roe numerical fluxes were adopted for convective fluxes. To preserve TVD property, the slope limiter was employed. As the case studies, the model is applied to the flow around the cylinders and the dam-break flow. Then, the results are compared with the experimental and numerical data of previous studies and good agreements were observed.

• The KIPS Transactions:PartB
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• v.8B no.3
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• pp.319-326
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• 2001

오차확산법은 중간조 처리에서 우수한 영상의 재현능력을 갖는 기법이다. 그러나 이의 기법은 경계재현 능력이 미약하며, 주기적인 패턴이 발생하여 영상의 화질을 저하시키는 단점이 있다. 본 논문에서는 경계재현의 능력을 개선하기 위한 경계강조법과 주기적인 패턴 발생을 감소시키기 위한 적응형 임계값 변조를 적용하는 방법을 제안하였다. 경계강조를 위한 임계값을 변조는 원영상의 공간적 기울기 정보를 활용하여 수행하였고, 동시에 기울기 정보를 이용하여 청색잡음 마스크를 적응적으로 적용하는 임계값 변조로 주기적인 패턴의 발생을 감소시키도록 하였다. 적응형 임계값 변조를 적용한 실험에서 영상의 주기적인 패턴이 감소된 보다 선명한 경계강조의 중간조 영상을 얻을 수 있었으며, 객관적인 특성분석을 위한 표시오차의 RAPSD, 거리에 따른 경계상관도 및 로컬 평균 일치도의 분석에서 제안한 기법이 효율적임을 확인하였다.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.2
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• pp.112-119
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• 2003

Generally, PID controller is not suitable to control multi variable system because it is very difficult to tune the PID gains. However, this paper shows that it is not hard to tune the PID gains if we can find a Jacobian matrix of the system. The Jacobian matrix expresses the ratio of output variations according to input variations. It is possible to adjust the input values in order to reduce the output error using the Jacobian. When the colt function is composed of error related terms, the gradient approach can tune the PID gains to minimize the function. In simulation, a hydrofoil catamaran with two inputs and two outputs is applied as a multi variable system. We can easily get the multi variable PID controller by the proposed teaming method. When the controller is compared with LQR controller, the performance is as good as that of LQR controller with a modeling equation.

• Journal of Biomedical Engineering Research
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• v.20 no.5
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• pp.545-557
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• 1999

본 논문에서는 호흡 연동 장치와 EBT로부터 획득한 폐실질 영상에 대하여 동적 윤곽선 모델 방법과 영역 성장법을 이용하여 폐실질 영역을 검출하였다. 그런 다음 , 검출된 폐실질 영역내에서의 각종 정량적 요소들을 도출하여 농도 분포 곡선에대한 분석을 하였다. 동적 윤곽선 모델방법에서 페실질 영역의 낮은 휘도 준위와 폐의 윤곽선 벡터 방향을 고려한 에너지 함수를 제안하였다. 그리고 폐실질 영역 성장법에서는 폐실질 영역내의 분포한 공기 성분에 대한 화소를 확장시켜 효과적으로 폐실질 영역을 검출하였다. 추출된 폐실질 영역내의 빈도 분포 곡선을 분석하여 정상군과 비교한 결과 만성 폐쇄성 폐질환자에서는 정상인에 비하여 평균 농도,최대 빈도 농도, 최대 상승 기울기 농도가 낮았으며, 농도 분포곡선은 더 낮은 쪽으로 이동하였음을 알 수 있었다. 또한, 특발성 폐섬유증 환자에서는 평균 농도, 최대 빈도 농도, 최대 상승 기울기 농도가 모두 증가되었고 농도 분포 곡선은 더 높은쪽으로 이동하였다. 폐실질 영역을 추출하여 히스토그램 분포에 대한 정량적 분석을 함으로써 정상인으로부터 만성 폐쇄성 질환자의 폐섬유증 환자를 구분할 수 있었다.