• 한국산학기술학회논문지
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• 제17권8호
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• pp.379-388
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• 2016

현대 무기체계 제조를 위해 적용되는 수많은 생산 기술과 다양한 공정 환경으로 인해 다양한 결함이 무기체계 제조공정에 유입되고 있다. 이렇게 제조공정에 유입되는 결함 중 육안 검사, 기능 시험 등 기존 품질 관리 절차를 통해 검출할 수 있는 "명백결함(Patent Defect)"과 무기체계 복잡성과 제조공정의 복잡도로 기존 품질 관리 방식으로 검출이 제한되는 "잠재결함(Latent Defect)" 2가지 종류가 있다. 이러한 초기 결함 문제를 최소화하기 위해 무기체계 생산공정 중 유입된 결함요소를 환경부하(온도, 진동)를 활용하여 결함검출/제거/개선하기 위해 환경 부하 선별(ESS : Environmental Stress Screening) 시험을 수행해야 한다. 본 논문은 국내 무기체계 제조업체에서 정량적 환경 부하 선별 시험 설계의 어려움을 최소화하기 위해 MIL-HDBK-344(Environmental Stress Screening of Electronic Equipment)의 수학적 모델을 기반으로 정량적 환경 부하 선별시험 효과도 분석 및 프로파일 자동화 도구를 구현하였으며, 6가지(온도부하변수 3가지(온도범위/온도변화율/허용 잔류결함밀도), 진동부하변수 2가지(부하크기/허용 잔류결함밀도), 시험설계변수 1가지(허용 시험시간)) 시나리오를 통해 구현된 도구 유효성을 확인했다.

• 대한장애인치과학회지
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• 제3권2호
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• pp.87-90
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• 2007

$DIFOTI^{(R)}$ 가시광선 파장을 이용하여 방사선 노출 없이도 실시간으로 교합면, 인접면, 평활면 우식, 재발성 우식 및 치아 파절이나 불소증 등을 효과적으로 진단할 수 있는 영상 장비이다. 시진 및 방사선 사진에 비해 치아 우식 탐지에 있어서 민감도가 매우 높은 것으로 나타나고 있으며, 이를 통해 치아의 탈회를 조기 진단하여 보다 보존적인 치료가 가능하리라 사료된다.

• 조명전기설비학회논문지
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• 제16권5호
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• pp.97-103
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• 2002

본 논문은 LVI 시험기를 개발하여 모델 변압기 및 유입식 변압기에 적용해 LVI 시험 분석기술을 개발하였다. LVI시험기는 본체, 터미널 박스 및 케이블로 구성하였고, ANSI규격에서 요구하는 출력특성을 갖도록 설계 제작하였다. 모델 변압기는 탭들을 만들어 변압기의 권선변형 모델을 만들 수 있도록 하였고, 유입식 변압기는 실제 현장에서 사용되는 3상 변압기이다. LVI 시험기는 펄스폭이 1000 ㎱ 이하의 파두 시간과 펄스 최대 전압 500 V로 제작되었다. LVI 시험기로써 실험을 실시하여 성능을 평가한 결과 측정된 파형 분석으로 권선의 축방향과 반경방향으로의 움직임을 구별할 수 있어 변압기 예방 진단에도 효과가 기대된다.

• 한국산업융합학회 논문집
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• 제23권2_2호
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• pp.163-171
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• 2020

The condition of tire tread is a key parameter closely related to the driving safety of a vehicle, which affects the contact force of the tire for braking, accelerating and cornering. The major factor influencing the contact force is tread wear, and the more tire tread wears out, the higher risk of losing control of a vehicle exits. The tire tread condition is generally checked by visual inspection that can be easily forgotten. In this paper, we propose the intelligent tire (iTire) system that consists of an acceleration sensor, a wireless signal transmission unit and a tread classifier. In addition, we also presents classification algorithm that transforms the acceleration signal into the frequency domain and extracts the features of several frequency bands as inputs to an artificial neural network. The artificial neural network for classifying tire wear was designed with an Multiple Layer Perceptron (MLP) model. Experiments showed that tread wear classification accuracy was over 80%.

• 한국멀티미디어학회논문지
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• 제18권12호
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• pp.1519-1527
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• 2015

TFT-LCD automatic defect inspection system for detecting defects in place of the visual tester does pre-processing, candidate defect pixel detection, and recognition and classification through a blob analysis. An over-detection result of defects acts as an undue burden of blob analysis for recognition and classification. In this paper, we propose defect detection method based on the histogram distribution modeling of TFT-LCD image to minimize over-detection of candidate defective pixels. Primary defect candidate pixels are detected estimating the skewness of the luminance distribution histogram of the background pixels. Based on the detected defect pixels, the defective pixels other than noise pixels are detected using the distribution histogram model of the local area. Experimental results confirm that the proposed method shows an excellent defect detection result on the image containing the various types of defects and the reduction of the degree of over-detection as well.

• 응용통계연구
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• 제22권3호
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• pp.569-584
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• 2009

영상에서 에지검출은 영상처리시스템과 컴퓨터비전에서 매우 중요한 단계이다. 지금까지 형태학적 에지검출은 고정된 구조적 요소를 사용한 형태학적 연산 토대 하에서 수행되어왔다. 본 논문에서는 잡음영상에서 에지검출을 위해 영상의 다양한 형태에 맞춰 다이내믹하게 모양이 변하는 아메바라는 구조적 요소를 사용하고자 한다. 제안된 에지검출 방법의 성능을 시각적인 방법뿐만 아니라 객관적인 척도인 PFOM과 ROC 곡선을 사용하여 정성적, 정량적으로 모두 평가하였다. 영상 설험 결과 고정된 구조적 요소를 이용하는 기존의 방법보다 잡음에 덜 민감하였으며 미세한 에지까지도 검출하는 뛰어난 성능을 보여주었다.

• 센서학회지
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• 제23권2호
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• pp.99-104
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• 2014

Sensor arrays based on chemical sensors produce multidimensional patterns of data that may be used discriminate between different chemicals. For the human observer, visualization of multidimensional data is difficult, since the eye and brain process visual information in two or three dimensions. To devise a simple means of data inspection from the response of sensor arrays, PCA (Principal Component Analysis) or Sammon's nonlinear mapping technique can be applied. The PCA, which is a well-known statistical method and widely used in data analysis, has disadvantages including data distortion and the axes for plotting the dimensionally reduced data have no physical meaning in terms of how different one cluster is from another. In this paper, we have investigated two techniques and proposed a combination technique of PCA and nonlinear Sammom mapping for visualization of multidimensional patterns to two dimensions using data sets from odor sensing system. We conclude the combination technique has shown more advantages comparing with the PCA and Sammon nonlinear technique individually.

• 설비공학논문집
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• 제23권11호
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• pp.705-710
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• 2011

Fault detection has to be proceeded by steady state filtering to get rid of transient effect associated with thermal capacity. Coefficient of variance (COV), ratio of standard deviation devided by moving average, was employed as steady-state filter. Engine speed and refrigerant pressures were selected as parameters representing system dynamics. The filtered values were registered as members of steady-state DB. They were found to show good functional relationship with ambient temperature. The relationship was fitted with a second order polynomial and the distribution bounds of the data around the fitted curve were expressed by visual inspection because of varying average and random data interval. Fault data were compared with the steady-state data obtained during normal operation. The fault data were easily isolated from the fault-free one. To make such isolation reliable, tests to construct good DB should be designed in a systematic way.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.567-570
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• 2003

Fractal mathematics is being highlighted as a research method for classification of image. But the application of Fractal dimension(FD) has been required the complicated calculation method because of its complex repetition progressing. In this paper, it has been developed the new approach method to express the Fractal Dimension(FD) for aging level calculation and estimation system of outside insulator using special image processing algorithm. As a result after FD testing, the recognized aging estimation of FD has a very characteristics compared to the conventional visual inspection.

• 한국표면공학회지
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• 제51권5호
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• pp.316-324
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• 2018

Harsh seawater environment is subdivided into marine atmosphere, splash zone, tidal zone, submerged zone and bottom of sea depending on the exposed part. Since corrosion rate depends on the conditions of the exposed parts, proper protection and maintenance for each parts are essential for long-term use of steel structures in seawater environment. For steel structures which were installed in Shiwha Lake, a special maintenance system is required to guarantee its long-term durability and safety. As the tidal power plant has recently been operated, the salinity has risen due to the rapid influx of seawater upstream into Sihwa Lake and the corrosion tendency of the structure is variable according to the water level fluctuation. In this study, corrosion properties of steel structures under water level fluctuation was evaluated by corrosion rate measurement, visual inspection and natural potential measurement and their durability and life management were discussed in view of the effect of variation in of seawater level fluctuations in Shihwa Lake.