• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.428-432
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• 2003

Quantitative Feedback Theory (QFT) is one of most effective methods of robust controller design and can be considered as a suitable method for systems with parametric uncertainties. Particularly it allows us to obtain controllers less conservative than other methods like $H_{\infty}$ and ${\mu}$-synthesis. In QFT method, we transform all the uncertainties and desired specifications to some boundaries in Nichols chart and then we have to find the nominal loop transfer function such that satisfies the boundaries and has the minimum high frequency gain. The major drawback of the QFT method is that there is no effective and useful method for finding this nominal loop transfer function. The usual approach to this problem involves loop-shaping in the Nichols chart by manipulating the poles and zeros of the nominal loop transfer function. This process now aided by recently developed computer aided design tools proceeds by trial and error and its success often depends heavily on the experience of the loop-shaper. Thus for the novice and First time QFT user, there is a genuine need for an automatic loop-shaping tool to generate a first-cut solution. In this paper, we approach the automatic QFT loop-shaping problem by using an algorithm involving Linear Programming (LP) techniques and Genetic Algorithm (GA).

• 대한안전경영과학회지
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• 제2권4호
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• pp.91-102
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• 2000

Nowadays, every kind of system is changed so complex and enormous, it is necessary to assure system reliability, product liability and safety. Fault tree analysis(FTA) is a reliability/safety design analysis technique which starts from consideration of system failure effect, referred to as “top event”, and proceeds by determining how these can be caused by single or combined lower level failures or events. So in fault tree analysis, it is important to find the combination of events which affect system failure. Minimal cut sets(MCS) and minimal path sets(MPS) are used in this process. FTA-I computer program is developed which calculates MCS and MPS in terms of Gw-Basic computer language considering Fussell's algorithm. FTA-II computer program which analyzes importance and function cost of VE consists. of five programs as follows : (l) Structural importance of basic event, (2) Structural probability importance of basic event, (3) Structural criticality importance of basic event, (4) Cost-Failure importance of basic event, (5) VE function cost analysis for importance of basic event. In this study, a method of initiation such as failure, function and cost in FTA is suggested, and especially the priority rank which is calculated by computer-aided decision analysis program developed in this study can be used in decision making determining the most important basic event under various conditions. Also the priority rank can be available for the case which selects system component in FMEA analysis.

• Journal of the Optical Society of Korea
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• 제19권5호
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• pp.487-493
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• 2015

A wavefront coding (WFC) technique provides an extension of the depth of field for a microscopy imaging system with slight loss of image spatial resolution. Through the analysis of the relationship between the incidence angle of light at the phase mask and the system pupil function, a mixing symmetrical cubic phase mask (CPM) applied to 5X-40X micro-objectives is optimized simultaneously based on point-spread function (PSF) invariance and nonzero mean values of the modulation transfer function (MTF) near the spatial cut-off frequency. Optimization results of the CPM show that the depth of field of these micro-objectives is extended 3-10 times respectively while keeping their resolution. Further imaging simulations also prove its ability in enhancing the defocus imaging.

• 대한의용생체공학회:의공학회지
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• 제17권1호
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• pp.109-120
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• 1996

Cardiac function is evaluated quantitatively using angiographic images via the analysis of the shape change or the heart wall boundaries. To kin with, boundary defection or ESLV(End Systolic Lert Ventricular) and EDLV(End Diastolic Left Ventricular) is essential for the quantitative analysis of cardiac function. The boundary detection methods proposed in the past were almost semi-automatic. Intervention by a knowledgeable human operator was still required Of con, manual tracing of the boundaries is currently used for subsequent analysis and diagnosis. This method would not cut excessive time, labor, and subjectivity associated with manual intervention by a human operator. EDLV images have noncontiguous and ambiguous edge signal on some boundary regions. In this paper, we propose a new method for automated detection of boundaries in noncontiguous and ambiguous EDLV images. The boundary detection scheme which based on a priori knowledge information is divided into two steps. The first step is to detect the candidate edge points of EDLV using ESLV boundaries. The second step is to correct detected boundaries of EDLV using the LV shape. We developed the algorithm of modifying EDLV boundaries defined adaptive modifier. We experimented the method proposed in this paper and compared our proposed method with the manual method in detecting boundaries of EDLV. In the areas within estimated boundaries of EDLV, the percentage of error was about 1.4%. We verified the useflilness and obtained the satisfying results througll the experiments of the proposed method.

• 대한안전경영과학회지
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• 제4권2호
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• pp.71-81
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• 2002

Today's environment of enterprise is changing. They have to face customer' demands with the right product, the right service and supply them at the right time. And also cut down logistics and inventory cost and bring up the profit as much as they can. This means the change of putting enterprise first in importance to putting customer first importance. therefore to correspond to customer's demand, shorting lead time is becoming a essential condition. The answer to this changes of environment is supply chain management. In the Supply chain, The ATP function doesn't only give customers to conformation of delivery. It can be used by the core function with ATP rule that can reconcile supplies and demands on the supply chain. Therefore We can be acquire the conformation about on the due date of supplier by using the ATP function of management about real and concurrent access on the supply chain, also decide the affect about product availability due to forecasting or customer's orders through the ATP. In this paper, It consolidates the necessity on a CTP and analyzes data which is concerned of ATP. Under the these environments, defines the ATP rule that can improve the customer value and data flow related the LTV(Life Time Value) and builds on a algorithm.

• 대한전자공학회논문지SP
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• 제47권6호
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• pp.117-126
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• 2010

빛은 촬영된 영상의 화질을 결정하는 중요 요소이다. 역광의 환경이나 빛을 정면으로 받는 환경에서 촬영된 영상의 경우, 빛의 조절이 어려워 특정 영역의 밝기만 왜곡될 수 있다. 이와 같은 경우 전체적인 보정으로는 영상의 질 향상이 어려우므로, 특정 영역의 밝기를 중점적으로 보정하는 기법이 필요하다. 제안 기법은 사용자의 입력을 이용하여 첫 프레임에서 밝기를 보정할 관심 영역을 선택하고 이를 중점적으로 보정하기 위한 밝기 대응 함수를 구한다. 대응 함수를 가중치에 따라 적용하고 이웃 픽셀과의 관계를 고려하는 에너지 함수를 정의하여 첫 프레임을 보정한다. 그리고 첫 프레임의 보정 결과를 이용하여 다음 프레임들을 순차적으로 보정한다. 각 픽셀의 밝기 변화량은 프레임간의 움직임 추정을 통해 다음 프레임의 대응 픽셀로 전달한다. 이때, 움직임 벡터의 신뢰도에 기반하여 밝기 변화량의 신뢰도를 정의하고, 이를 이용하여 이웃 픽셀과의 관계를 고려하는 밝기 보정을 위한 에너지 함수를 정의한다. 모의 실험 결과에서 볼 수 있듯이 제안 기법은 정의한 에너지를 최소화함으로써 기존 기법에 비해 자연스러운 역광 보정의 결과를 도출한다.

• 한국콘텐츠학회논문지
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• 제11권11호
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• pp.102-110
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• 2011

본 논문은 플레이어와 게임간의 상호작용의 의미를 조이스틱, 키보드와 같이 조작적 상호작용 뿐만 아니라 플레이어가 게임을 플레이하면서 보고 듣고 이해하는 표상적 상호작용을 포함하여 접근하고 있다. 기존게임 내에 삽입되는 동영상(cut-scene)은 주로 게임의 배경스토리를 전달하는 오프닝 영상과, 플레이어 행동의 결과를 재생(replay)하거나 플레이어의 상태를 부가적으로 표현하는 수동적인 의미의 영상으로 인식되어 왔다. 그러나 게임연출 측면에서 대표적인 비디오게임 '언차티드2'의 인터랙션 무비에 대한 플레이어의 행동과 그 결과를 조사해 보면 크게 3가지의 기능(상황연출, 선택적 행동유발, 정보전달)으로 인터랙션 무비를 분류할 수 있었다. 그 결과, 인터랙션 무비는 게임플레이를 위한 부가적인 요소가 아닌 인터페이스로써의 기능을 수행하고 있다고 판단된다. 인터랙션 무비의 효과적인 적용은 플레이어 관점에서 인지하고 주인공 캐릭터 관점에서 플레이하는 과정을 유기적으로 연결시킬 수 있어 게임의 스토리 전달을 극대화하는 직접적인 수단으로 활용될 수 있다.

• 한국콘텐츠학회논문지
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• 제14권3호
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• pp.269-276
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• 2014

본 연구에서는 라쉬분석을 통하여 한글판 학교기능평가(School Function Assessment)도구의 구성타당도, 척도 적합성을 검증함으로써 이 평가도구의 국내 사용을 위한 기초자료를 제시하고자 한다. 서울 및 경기, 충청 지역의 만 7세~12세(초등학교 1학년~6학년)인 98명 장애아동을 대상으로 아동의 보호자 및 담임 특수교사 또는 작업치료사와 직접 면담 또는 전화를 통하여 자료를 수집하였다. 자료분석은 라쉬분석을 통하여 단일차원모형(unidimensionality)에 대한 적합통계치(fit statistics)를 제시하였다. 또한, 라쉬분석의 평정척도모형(rating scale model)을 이용하여 평정척도의 적합성 분석을 실시하였다. 라쉬분석 결과 각 25개 하위척도 내 총 328개 항목 중 단일모형 적합통계치가 부적합한 항목은 Part II 과제지원 영역에서 총 4개였고, Part III 신체적 과제 영역에서 부적합 항목은 18개, 인지/행동적 과제 영역에서 부적합 항목은 14개 항목으로 나타났다. 한글판 학교기능평가 도구의 모든 평가 하위영역의 5점 평정척도는 적합한 것으로 나타났다 본 연구를 통하여 한글판 학교기능평가 도구의 구성타당도와 평정척도 적합성을 확인하였다. 그 결과 5점 평정척도는 적합한 것으로 나타났으나, 일부 부적합 항목이 발견되어 앞으로 국내 타당도 확립과 준거제시를 위한 연구가 추후 이루어져야 할 것으로 판단된다.

• 기본간호학회지
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• 제13권2호
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• pp.249-256
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• 2006

Purpose: To investigate the influence of clinical and demographical variables on depression, instrumental activities of daily living (IADL), and cognitive function in patients with Parkinson's disease. Method: Using a structured questionnaire data were collected from 100 participants registered in the neurology department of C university hospital. Duration and stage of disease, fall history, vision impairment, duration and quality of sleep, orthostatic hypotension, ambulation impairment, and use of walking aid were included in clinical variables. Depression, IADL, and cognitive function were assessed using Kee's GDSSF-K, Cho's scale, and K-MMSE. Collected data were analyzed using the SAS program. Results: The depression score for the participants was 7.78, higher than cut-off score(5). Participants who were male, living with spouse, above high school education, high economic status, with no vision impairment, and no ambulation impairment revealed high cognitive scores. Average IADL score were significantly higher for participants who were male, who had high economic status, low stage of disease, and no ambulation impairment. Depression IADL & cognitive function scores were significantly different according to ambulation impairment. Scores for ADL and cognitive function were positively correlated. Conclusion: It is recommended that make programs for patients with Parkinson's disease, clinical and demographic variables should be considered according to their individual needs.

• 한국해양바이오학회지
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• 제7권2호
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• pp.52-57
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• 2015

The purpose of this study was to investigate a relationship between ultraviolet radiation and initial cell density (ICD) of microalgae using a floating marine photobioreactor (PBR). To examine the effect of ultraviolet (UV) radiation in sunlight on biomass productivity as a function of ICD, 0.5-L floating PBRs covered with or without UV cut-off film were placed in an outdoor rectangular tank containing 200 L of water. At the lower ICDs, 0.01 and 0.05 g/L, biomass productivities in the PBRs without UV cut-off film decreased by $278{\pm}21%$ and $222{\pm}3%$ compared with those with the film, respectively. In contrast, the presence of UV cut-off film did not have a significant effect on biomass productivities at the higher ICDs, 0.25 and 1.25 g/L. When the differences in biomass productivity made by the UV cut-off film were plotted against the sum of cell projection area per light receiving area of the PBR, the results revealed that the inhibitory effect of UV on biomass productivity can be negligible when the sum of cell projection area is equal to the light receiving area of the PBR. These results show that photoinhibition caused by UV radiation could be eliminated via operating the PBR with a proper ICD.