• 한국가구학회지
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• 제19권2호
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• pp.111-115
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• 2008

An experiment was conducted to know ultra-pure distilled water penetration depth through large vessel, small vessel, latewood fiber and earlywood fiber in longitudinal direction of Castanea crenata. In heartwood, latewood fiber transported water more than large and small vessel. While in sapwood, small vessel conduction depth was found the highest. Penetration depth of water after 15.0 seconds, no significant difference was observed among earlywood fiber, latewood fiber and earlywood vessel. Whilst in heartwood, no statistical difference was observed among earlywood fiber, latewood fiber and earlywood vessel. At the beginning, the speed of water penetration was high and then gradually decreased.

• International Journal of Contents
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• 제2권3호
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• pp.27-32
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• 2006

We present an effective algorithm for automatic tracing of retinal vessel structure and vascular landmark extraction of bifurcations and ending points. In this paper we deal with vascular patterns from RGB images for personal identification. Vessel tracing algorithms are of interest in a variety of biometric and medical application such as personal identification, biometrics, and ophthalmic disorders like vessel change detection. However eye surface vasculature tracing in RGB images has many problems which are subject to improper illumination, glare, fade-out, shadow and artifacts arising from reflection, refraction, and dispersion. The proposed algorithm on vascular tracing employs multi-stage processing of ten-layers as followings: Image Acquisition, Image Enhancement by gray scale retinal image enhancement, reducing background artifact and illuminations and removing interlacing minute characteristics of vessels, Vascular Structure Extraction by connecting broken vessels, extracting vascular structure using eight directional information, and extracting retinal vascular structure, and Vascular Landmark Extraction by extracting bifurcations and ending points. The results of automatic retinal vessel extraction using jive different thresholds applied 34 eye images are presented. The results of vasculature tracing algorithm shows that the suggested algorithm can obtain not only robust and accurate vessel tracing but also vascular landmarks according to thresholds.

• 한국항해항만학회지
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• 제47권6호
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• pp.430-436
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• 2023

자율운항선박 관련 기술개발은 2010년도 중반부터 충돌회피, 항로 지정, 디지털 트윈 및 통신 기술개발 등의 주제로 활발하게 진행되고 있다. 그러나, 이와 비교하여 자율운항선박과 연계된 물류시스템, 항만시설 및 선박교통관제 등의 육상 인프라에 관한 연구는 상대적으로 관심을 받지 못하고 있다. 이 연구에서는 자율운항선박의 등장에 따라 기존 선박교통관제 업무에 미치게 되는 영향을 분석함과 동시에 이를 대비하기 위한 관제 업무 변화 방안을 제시하였다. 이를 위하여 현행 선박교통관제 업무를 분석하고, 동시에 자율운항선박 기술 중 선박교통관제에 영향을 미칠 수 있는 요소를 파악하였다. 또한, 선박교통관제사들을 대상으로 자율운항선박 관제 관련 항목 도출을 위한 설문조사를 수행하였으며, 이를 AHP 기법으로 분석한 결과 비상 상황 대응 및 자율운항선박과의 통신 방법에 대한 준비가 가장 중요한 것으로 도출되었다. 이를 기반으로 해상교통관제구역 내에서 데이터 통신을 기반으로 한 기본적인 자율운항선박 관제 절차 및 비상 대응 절차 등 세부 방안을 도출할 수 있었다. 이 연구에서 제안하는 자율운항선박 관제 절차는 향후 자율운항선박의 연안 해상교통안전에 관한 문제점들을 해소하는 방안으로 활용될 수 있을 것으로 기대된다.

• 한국가스학회지
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• 제3권3호
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• pp.23-28
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• 1999

밀폐공간 내에 블록을 조합하여 부피와 표면적이 다르게 내용물을 채우고 용기 부피에 대한 내용물의 부피와 내용물의 표면적을 변화시키면서 LPG 또는 NG와 공기 혼합가스의 폭발특성을 측정하여 밀폐공간 내부에 있는 내용물의 부피와 표면적의 변화가 폭발특성에 미치는 영향을 해석하고자 하였다. 폭발용기는 가로 세로 높이가 각각 $100cm{\times}60cm{\times}45cm$인 부피 270리터의 금속 용기이며, 용기 내 가연성 혼합가스는 전기 스파크로 착화시켰고, strain형 압력센서로 폭발압력을 측정하였다. 실험 결과 부피봉쇄율이 증가할수록 폭발압력이 감소하였으며, 내용물의 표면적의 증가에 따라서도 폭발압력이 낮아졌으며, 이러한 폭발압력의 감소 경향은 표면적의 증가에 대한 영향보다 부피의 증가에 의한 영향이 더욱 크게 나타났다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.3-5
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• 2005

Vessel boundary detection and modeling is a difficult but a necessary task in analyzing the mechanics of inflammation and the structure of the microvasculature. In this paper we present a method of analyzing the structure by means of an active contour model(using GVF Snake) for vessel boundary detection and 3D reconstruction. For this purpose we used a virtual vessel model and produced a phantom model. From these phantom images we obtained the contours of the vessel by GVF Snake and then reconstructed a 3D structure by using the coordinates of snakes.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.611-612
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• 2012

• 한국지리정보학회지
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• 제5권4호
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• pp.86-92
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• 2002

고해상도 위성 IRS-1C의 Panchromatic 영상 자료를 이용하여 한국 근해에서 선박의 수와 위치를 파악할 수 있는 가능성을 살펴보았다. Panchromatic 위성 영상에서 선박과 주변환경에 대한 위치, 크기, 모양, 그림자, 색조, 질감 및 모양의 공간배열, 높이와 깊이, 현황 및 연관성 등의 영상해석 요소를 활용하여 선박 모니터링의 논리적 접근기법을 연구하였다. 선박의 공간적 위치는 GCP가 없는 해상에서 영상의 중심위치 정보로부터 반경 35km내에서 지구좌표점으로 전환하였다. 선박의 크기는 선수에서 선미까지이나 선미에서 생기는 종파(following wave)와 추정 구분하여야 했다. 길이 100m를 기준으로 연근해 어선과 상선으로 구분하였다. 선박의 모양은 종파의 영향으로 영상에서 유선형이었다. 작은 구름의 경우 선박의 모양과 유사했으나, 해상에 반영된 구름의 그림자로 배와 구분할 수 있었다. 색조는 바다표면이 검은색을 띤 반면 소형선박은 밝은 흰색으로 나타났다. 바다의 거친 정도와 파도의 방향성 배열 등을 통해 파도와 선박을 구분하였다. 또한 쌍끌이 어선과 같은 조업방법이 어선의 어업별 종류를 영상에서 추정하는데 용이한 기초 연관 자료가 되었다.

• 대한기계학회논문집A
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• 제26권11호
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• pp.2390-2398
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• 2002

For integrity analysis of nuclear reactor pressure vessel, including the Pressurized thermal shock analysis, the fast and accurate calculation of the stress intensity factor at the crack tip is needed. For this, a simple approximation scheme is developed and the resulting stress intensity factors for axial semi-elliptical cracks in cylindrical vessel under various loading conditions are compared with those of the finite element method and other approximation methods, such as Raju-Newman's equation and ASME Sec. Xl approach. For these, three-dimensional finite-element analyses are performed to obtain the stress intensity factors for various surface cracks with t/R = 0.1. The approximation methods, incorporated in VINTIN (Vessel INTegrity analysis-INner flaws), utilizes the influence coefficients to calculate the stress intensity factor at the crack tip. This method has been compared with other solution methods including 3-D finite clement analysis for internal pressure, cooldown, and pressurized thermal shock loading conditions. The approximation solutions are within $\pm$2.5% of the those of FEA using symmetric model of one-forth of a vessel under pressure loading, and 1-3% higher under pressurized thermal shock condition. The analysis results confirm that the VINTIN method provides sufficiently accurate stress intensity factor values for axial semi-elliptical flaws on the surface of the reactor pressure vessel.

• 동력기계공학회지
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• 제16권2호
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• pp.66-74
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• 2012

In this paper, the authors propose a new approach to control a barge type surface vessel. It is based on the Dynamic Positioning System(DPS) design. The main role of barge ship is to carry and supply the materials to the floating units and other places. To carry out this job, it should be positioned in the specified area. However sometimes the thrust systems are installed on it, and in general the rope control by mooring winch system is used. It may be difficult to compare the control performances of two types. If we consider this problem in point of usefulness, we can easily find out that the winch control system is more useful and applicable to the real field than the thrust control system except a special use. Therefore, in this paper we consider a DPS design problem which can be extended to the many application fields. The goal of this paper is twofold. First, the sliding mode controller (SMC) for positioning the our vessel is proposed. Especially, in this paper, a robust stability condition is given based on descriptor system representation. In the result, the sliding mode control law guarantees to keep the vessel in the defined area in the presence of environmental disturbances. And second, the thrust allocation problem is solved by using redistributed pseudo-inverse (RPI) algorithm to determine the thrust force and direction of each individual actuator. The proposed approach has been simulated with a supply vessel model and found work well.

• 한국안전학회지
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• 제20권4호
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• pp.14-19
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• 2005

One area in which composites have been used rather extensively is for fabricating pressure vessel. These structures can be readily manufactured by filament winding, which is, as far as composite fabrication techniques are concerned, a relatively inexpensive method for producing composite structures. Unfortunately, the higher strength material and fabrication costs are not the only disadvantages of fiber-reinforced polymer composites when they are compared to metals. Additionally, these materials tend to exhibit brittle behavior. This is of particular concern when they are subjected to a low-velocity impact during routine handling a significant amount of structural damage can be introduced into the composites. The goals of this paper are to understand the impact damage behavior and identify the effect of surface coating materials on impact resistance in filament wound composite pressure vessels. For these, a series of low velocity impact tests was performed on specimens cutting from the full scale pressure vessel by the instrumented impact testing machine. The specimens are classified into two types with and without surface protective material. The visualization for impact damage is made by metallurgical microscope. Based on the impact force history and damage, the resistance parameters were employed and its validity in identifying the damage resistance of pressure vessel was reviewed. As the results, the impact resistance of the filament wound composites and its dependency on the protective material were evaluated quantitatively.