• 비파괴검사학회지
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• 제30권5호
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• pp.489-496
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• 2010

발전 및 화학플랜트의 많은 고온 설비는 장시간 운전으로 인해 재질열화 현상이 필연적으로 발생된다. 이러한 고온설비의 건전성 확보와 신뢰성 있는 수명평가를 위해서는 비파괴평가기법인 표면복제시험을 통한 미세조직분석 평가법이 현재까지 유용한 것으로 인식되어왔다. 이러한 표변복제기법은 기존의 평가법과 함께 탄화물평가를 통한 재질열화도 평가 등 새로운 정량적 접근법이 필요하며 다양하게 시도되고 있다. 본 논문에서는 표면복제기법과 관련한 기술개발 현황과 현장 적용사례들을 소개하고, 합리적인 평가결과 여부에 대해 기술하였으며, 현장설비에 대해 표면복제시험 후 미세조직을 분석한 결과 탄화물 평가방법이 정량적으로 유용함을 입증하였다.

• 상하수도학회지
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• 제28권5호
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• pp.561-571
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• 2014

The paper is to estimate willingness-to-pay (WTP) for tap water quality improvement in Busan, using parametric approach in contingent valuation method(CVM). For parametric approach linear logit model and log logit model are employed in double-bounded dichotomous choice format of CVM. For the reliability and the validity of contingent valuation method a survey was conducted for 665 respondents, who were sampled by stratified random sampling method, by personal interview method. The result of mean WTP for the tap water quality improvement in Busan was estimated to be 3,687 won and 3,660 won per month per household, while median WTP being 1,884 won and 1,892 won per month per household, respectively by linear logit model and log logit model. Provided that our sample is broadly representative of the Busan's population, an estimate of the annual aggregated benefit of residential water improvement for all Busan households is approximately 29.7 billion won to 29.8 billion won based on median WTP.

• Structural Engineering and Mechanics
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• 제75권5호
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• pp.585-594
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• 2020

Detecting the damage of indeterminate trusses is of major importance in the literature. This paper proposes a quick approach in this regard, utilizing a precise mathematical approach based on Finite Element Method. Different to a general two-step method defined in the literature essentially based on optimization approach, this method consists of three steps including Damage-Suspected Element Identification step, Imminent Damaged Element Identification step, and finally, Damage Severity Detection step and does not need any optimizing algorithm. The first step focuses on the identification of damage-suspected elements using an index based on modal residual force vector. In the second step, imminent damage elements are identified among the damage-suspected elements detected in the previous step using a specific technique. Ultimately, in the third step, a novel relation is derived to calculate the damage severity of each imminent damaged element. To show the efficiency and quick function of the proposed method, three examples including a 25-bar planar truss, a 31-bar planar truss, and a 52-bar space truss are studied; results of which indicate that the method is innovatively capable of suitably detecting, for indeterminate trusses, not only damaged elements but also their individual damage severity by carrying out solely one analysis.

• 대한기계학회논문집A
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• 제28권4호
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• pp.370-377
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• 2004

The density approach and the homogenization design method are representative methods in topology optimization problems. In the topology optimization in magnetic fields, those methods are applied based on the results of the applications In elastic fields. In this study, the density method is modified considering the concept of the homogenization design method. Also, the results of the topology optimization in magnetic fields by the modified density method as well as the homogenization method are compared especially focusing the change of the penalization parameter in the density approach. The effect of the definition of the design domain such as global/local design domain is also discussed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.430-430
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• 2000

This paper presents a new analytic approach using tetrahedrons to determine the forward kinematics of the 3-6-type Stewart platform. By using of the tetrahedral geometry, this approach has the advantage of greatly reducing the complexity of formulation and the computational burden required by the conventional methods which have been solved the forward kinematics with three unknown angles. As a result, this approach allows a significant abbreviation in the formulations and provides an easier means of obtaining the solutions. The proposed method is well verified through a series of numerical simulation.

• 한국통신학회논문지
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• 제22권5호
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• pp.881-888
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• 1997

The existing method s for curvature estimation have a common problem in determining a unique smoothong factor. we previously proposed two approaches to overcome that problem: a constrained regularization approach and a mean field annealing approach. We consistently detected corners from the perprocessed smooth boundary obtained by either the constrained eglarization approach or the mean field annealing approach. Moreover, we defined corner sharpness to increase the robustness of both approaches. We evaluate the performance of those methods proposed in this paper. In addition, we show some matching results using a two-dimensional Hopfield neural network in the presence of occlusion as a demonstration of the power of our proposed methods.

• Journal of Chest Surgery
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• 제33권2호
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• pp.183-185
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• 2000

With the marked decrease in operative mortality in simple heart diseases there have been several reports on the minimally invasive and cosmetic techniques including submammary incision right parasternal approach right anterolateral thoracotomy partial sternotomy and subxiphoid approach. We report here subxiphoid approach without sternotomy for the repair of atrial septal defect as the procedure that has less invasive technique and more cosmetic effect.

• 대한교통학회지
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• 제12권3호
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• pp.15-27
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• 1994

A mathematical model and its solution algorithm are proposed for computing the capacity of terminal control area. The model is built based on dynamics of aircraft flying on pre-established approach path and its solution algorithm employs a numerical method. The model computes the minimum separation of two aircraft at the entry fix of the terminal control area, which assures that air traffic separation rules are not violated during the approach phase, thereby computes the capacity. The model might be applied for designing approach paths for a new airport, for rearranging paths of an existing airport or establishing approach control procedures.

• Transactions on Control, Automation and Systems Engineering
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• 제4권1호
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• pp.56-61
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• 2002

In this paper we describe an approach to coordinating the motion of a human with a mobile robot moving in a populated, continuously changing. natural environment. Our test application is a wheelchair accompanying a person through the concourse of a railway station moving side by side with the person. Our approach is based on a method for motion planning amongst moving obstacles known as Velocity Obstacle approach. We extend this method by a method for tracking a virtual target which allows us to vary the robot's heading and velocity with the locomotion of the accompanied person and the state of the surrounding environment.

• Journal of Ship and Ocean Technology
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• 제5권2호
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• pp.1-13
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• 2001

Data in one Product Model for shipbuilding is inevitably referenced and manipulated during each phase of design or production activities, and data or manipulation status naturally varies from the original with the advance of each activities. For Object-Oriented approach, it is hard to identify classes dealing with those variations, and even if once a product model is developed, it might be getting much harder to modify it to cope with a new additional phase of activities. This paper proposes an Instance-Oriented Modeling Method, temporarily named “Concept-Relationship Modeling Approach”, which handles Data structure and Behavior independently of each other in order to resolve the difficulties above.