• Journal of Korean Society of Water and Wastewater
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• v.22 no.1
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• pp.79-86
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• 2008

In Korea, most of the drinking water treatment relied upon the availability of the surface water, of which the raw water quality varied significantly by season and location. Therefore, the comparison of two operation modes (Pressurized type and Submerged type membrane system) must be estimated before the long-term establishment of two systems. In this study, two pilot-scale microfiltration systems with the capacity of $50m^3/day$ were installed and operated in two different modes, and the applicability of the system was determined based on the results such as the TMP (Trans-Membrane Pressure) and flux. For quantitatively comparing the two systems, a new concept, DRF (Differential Resistance Fraction) was introduced. The accumulated sum of the permeate after each cycle of chemical cleaning was also used as a tool for the system comparison.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11a
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• pp.523-526
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• 2003

생체정보를 이용한 보안 솔루션이 활발하게 연구되고 있는 가운데, 지문은 가장 널리 사용되고 또한 중점적으로 연구되고 있는 생체특징의 하나로 자리잡았다. 지문인식 시스템에 사용되는 지문 입력기는 광학식, 반도체식 등 다양하나 입력방식은 주로 압착날인식으로 회전식과 달리 손가락 끝을 입력창에 대어 그 순간 접촉된 면의 지문만을 입력받게 된다. 그러므로 입력된 지문영상은 전체지문과 비교했을 때 극히 일부분에 불과하여, 이러한 제한된 영역으로부터 획득된 지문영상들을 비교한다면 비록 동일 지문이라 할지라도 획득 위치의 상이함으로 인해 타인 지문으로 오인식할 소지가 있다. 또한 특징점에 기반한 지문인증 알고리즘의 경우에는 두 지문으로부터 추출된 특징점의 위치 및 상태 정보의 신뢰성에 전적으로 의존하게되므로 특징점의 오추출 및 누락이 전체 시스템 성능을 좌우하게된다. 그러므로 가능한한 넓은 영역의 지문을 사용하고 신뢰할 만한 특징 추출 결과를 얻는 것이 에러율을 개선하는데 필수적이라 하겠다. 이에, 본 논문에서는 사용자 등록시 한 지문에서 획득한 복수의 지문영상을 이용하여 정렬 및 정합 과정을 거친 후 지문영상의 영역을 확장하고 해당 지문영상에서 추출된 특징점을 비교하여 유효하지 않은 특징점을 제거하는 과정을 통하여 등록시 저장되는 특징점 템플릿의 신뢰도를 높여주는 방법을 제안하였다. 제안된 알고리즘은 결과의 객관성을 확보하기 위하여 FVC 2002에서 제공하는 데이터베이스로 테스트한 결과 2.12%의 EER(Equal Error Rate)을 얻을 수 있었다.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.6
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• pp.175-183
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• 2010

In this study, laboratory experiments are conducted to investigate flow-fields around floating breakwaters by using the LDV(Laser Doppler Velocimetry) system. The LDV system is a well-known equipment to measure fluid particle velocities in laboratory experiments. Although the system requires great efforts and enormous time for measurements, it can provide precise velocity fields comparing to other available equipments. Various types of drafts and shapes for breakwaters are employed in laboratory experiments to analyze a relation between flow-fields and vorticity. A series of numerical experiments are also carried out by using a two-dimensional Navier-Stokes equations model. Numerically predicted results are compared with laboratory measurements.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.989-992
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• 2008

Recently, high-strength concrete has been frequently used for long-span bridges and high-rise buildings. Deflection of reinforced concrete structures is uncertain, so that many researchers have proposed various equations in order to predict deflection through experiments. Domestic concrete specification offers a procedure to evaluate deflection using effective moment of inertia which was proposed by Branson. However, it is inaccurate for high strength concrete compared to the method suggested in Eurocode 2 in that Eurocode 2 predicts deflection by using curvature integration of effective moment of inertia. In this study, experimental data about deflection of reinforced concrete beams were analyzed to compare domestic standard and Eurocode 2.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.1
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• pp.33-42
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• 2002

A method of automatic 3D tunnel modeling is proposed. The proposed method used the parametric representation of geometry and a hierarchical and relational data structure. These two bases provide the generalization and extension for 3D tunnel modeling. Especially, these two fundamentals ion the basis iota representing the characteristics of the tunnel structure for analysis. The constant-curvature characteristic is exploited to generate 3D mesh on the tunnel surface. This is attributed to the advantage that any 2D automatic mesh generation algorithm can be applied to 3D mesh modeling.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.190-197
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• 2016

Flash point is the one of the important properties for the safe handling of inflammable liquid solution. In this paper, flash points of binary liquid solutions, water+1-propanol and water+2-propanol, were been measured by using Seta flash closed cup aparatus. Flash point was estimated using regression analysis method. Flash points were also estimated by the method based on Raoul's law and the method optimizing the binary parameters of van Laar equation. Experimental results were compared with the calculated results. The regression analysis method is able to estimate the flash point fairly well for water+1-propanol and water+2-propanol mixture.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.3
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• pp.65-73
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• 1989

Continuum formulations for the expressions of dynamic energy release rates and computational methods for dynamic stress intensity factors are developed for the analysis of dynamic fracture problems subjected to stress wave loading. Explicit volume integral expressions for instantaneous dynamic energy release rates are derived by modeling virtual crack extensions with the dynamic Eulerian-Lagrangian kinematic description. In the finite element applications a finite region around a crack-tip is modeled by using quarter-point singular isoparametric elements, and the volume integrals are evaluated for each crack-tip element during virtual crack extensions while the singularity is maintained. It is shown that the use of the present method is more reliable and accurate for the dynamic fracture analysis than that of other path-independent integral methods when the effects of stress waves are significant.

• Journal of Chest Surgery
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• v.36 no.1
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• pp.55-58
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• 2003

Although postanastomosis of esophageal reconstruction is rare but it is a very unwelcome complication. Previously, the problem was solved by balloon dilatation, reoperation, and feeding jejunostomy. However, balloon dilatation is not effective because of high recurrence rate, reoperation is difficult due to its operative approachableness and also jejunostomy is inconvenient for patients. Therefore, we inserted esophageal stent as a method of relieving postanastomosis stenosis, From Jan, 2001 to Dec, 2001, there were three patients with postanastomosis stenosis, who received esophageal stent insertion, one had case is benign esophageal stenosis, two had esophageal carcinoma. We followed up them over 12 months after inserting the stent, Dysphagia was improved, so we report that the clinical performance was satisfactory

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.504-507
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• 2005

In this paper, we propose a calibration technique of 3D coordinates using orthogonal stereo vision. First, we acquire front- image and upper- image from stereo cameras with real time and extract each coordinates of a moving object using differential operation and ART2 clustering algorithm. Then, we can generate 3D coordinates of that moving object through combining these two coordinates. Finally, we calibrate 3D coordinates using orthogonal stereo vision since 3D coordinates are not accurate due to perspective. Experimental results show that accurate 3D coordinates of a moving object can be generated by the proposed calibration technique.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.110-112
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• 2001

본 논문에서는 전력선 통신 시스템의 전송신호가 비수용가로 전송되는 현상을 차단하기 위한 비접촉식 Blocking Filter를 유한요소법을 이용하여 해석하였다. 새로운 통신망 시스템이 연구되면서 기존의 전력케이블 망을 이용한 전력선 통신방식에 대한 연구가 이루어 졌으나, 전력선 통신이 서비스 지역 이외에 다른 지역으로 통신신호들이 전송될 수 있는 문제점이 제기되었으며, 또한 지정된 지역 내에서 최적화된 통신환경의 구성이 요구되었다. 따라서 본 논문은 타 지역으로의 신호 간섭을 차단하기 위한 비접촉식 Blocking Filter의 기본 모델을 제시하였으며, 이러한 비접촉식 Blocking Filter를 유한요소법을 기초로 한 전자장 수치해석 기법과 전송선 이론을 도입하여 신호 전송 특성을 해석하였다.