• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.1-5
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• 2018

The present study investigated the characteristics of vertical sagging down of high temperature in chamber and characteristics of vertical sagging down in the outdoor asphalt sheet and asphalt seal under korea ltimate condition using asphalt seal products of solvent based type, solventless type, water dispersion type, and heat melting type, which are currently applied in Korea. Prior to the investigation of outdoor vertical sagging down characteristics, the assessment of sagging down performance of single use of sealing products at $20^{\circ}C$, $40^{\circ}C$, $60^{\circ}C$ was conducted and the result showed that sagging down did not occur at $20^{\circ}C$ but some solventless type, water dispersion type specimens at $40^{\circ}C$ had sagging down up to 10 mm. In addition, some solventless type, water dispersion type specimens had sagging down up to 55 mm at $60^{\circ}C$. For specimens to which asphalt seal and renovated asphalt sheet were layered over the outdoor concrete vertical surface, sheet sagging and sagging down occurred up to 50 mm in water dispersion specimens after three month later since the construction in summer.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.1
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• pp.1-6
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• 2014

In this study, we propose optimized RBFNNs based on night vision face recognition simulator with the aid of $(2D)^2$ PCA algorithm. It is difficult to obtain the night image for performing face recognition due to low brightness in case of image acquired through CCD camera at night. For this reason, a night vision camera is used to get images at night. Ada-Boost algorithm is also used for the detection of face images on both face and non-face image area. And the minimization of distortion phenomenon of the images is carried out by using the histogram equalization. These high-dimensional images are reduced to low-dimensional images by using $(2D)^2$ PCA algorithm. Face recognition is performed through polynomial-based RBFNNs classifier, and the essential design parameters of the classifiers are optimized by means of Differential Evolution(DE). The performance evaluation of the optimized RBFNNs based on $(2D)^2$ PCA is carried out with the aid of night vision face recognition system and IC&CI Lab data.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.5
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• pp.162-177
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• 2020

The perception of traffic environment based on various sensors in autonomous driving system has a direct relationship with driving safety. Recently, as the perception model based on deep neural network is used due to the development of machine learning/in-depth neural network technology, a the perception model training and high quality of a training dataset are required. However, there are several realistic difficulties to collect data on all situations that may occur in self-driving. The performance of the perception model may be deteriorated due to the difference between the overseas and domestic traffic environments, and data on bad weather where the sensors can not operate normally can not guarantee the qualitative part. Therefore, it is necessary to build a virtual road environment in the simulator rather than the actual road to collect the traning data. In this paper, a training dataset collection process is suggested by diversifying the weather, illumination, sensor position, type and counts of vehicles in the simulator environment that simulates the domestic road situation according to the domestic situation. In order to achieve better performance, the authors changed the domain of image to be closer to due diligence and diversified. And the performance evaluation was conducted on the test data collected in the actual road environment, and the performance was similar to that of the model learned only by the actual environmental data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.1C
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• pp.44-53
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• 2005

In this paper, a improved moving object detection algorithm for stable performance of surveillance system in case of iterative moving in limited area and rapidly illuminance change in background scene is proposed. The proposed algorithm is that background scenes are sampled for initializing background image then the sampled fames are divided by block and sum of graylevel value for each block pixel was calculated, respectively. The initialization of background image is that background frame is respectively reconstructed with selecting only the maximum graylevel value and the minimum graylevel value of blocks located at same position between adjacent frames, then reference images of background are set by the reconstructed background images. Moving object detecting is that the current image frame is divided by block then sum of graylevel value for each block pixel is calculated. If the calculated value is out of graylevel range of the initialized two reference images, it is decided with moving objects block, otherwise it is decided background. The evaluated results is that the error rate of the proposed method is less than the error rate of the existing methods from $0.01{\%}$ to $20.33{\%}$ and the detection rate of the proposed method is better than the existing methods from $0.17{\%}\;to\;22.83{\%}$.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.3
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• pp.427-436
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• 2005

Topical application of APF gel can increase the surface roughness of resin composites and the roughened surfaces may allow increased bacterial accumulation and surface staining. Resin specimens of two proprietary resin composites, Filtek Z250(FZ) and Filtek Supreme Universal(FS), and experimental resin composites containing 0%, 3%, 6% nanofillers(E0, E3, E6) were fabricated and divided into two groups of the same number; APF treatment group and no treatment group. The amount of S. mutans adhered to specimens and the mean surface roughness(Ra) were measured. The results were as follows; 1. In no treatment group, the amount of S. mutans adhered to FS was the smallest. It was significantly different from those of FZ, E3, E6(p<0.05) although it was not significantly different from that of E0(p>0.05). 2. For all resin composites used, the amount of S. mutans adhesion in APF treatment group was significantly greater than that in no treatment group(p<0.05). 3. In APF treatment group, the amount of S. mutans adhesion was significantly different between materials(p<0.05), and increased in order of FS, FZ, E0, E3 and E6. 4. Difference of the surface roughness(Ra) between materials was not statistically significant in both no treatment group and APF treatment group(p>0.05)

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.25-33
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• 2017

This paper reports the optical design of the MR-16 lamp series with a LED second lens and an aspherical plano-convex lens suitable for a simple and rapid injection molding fabrication method. The fabrication and performance evaluation of the MR-16 lamp series, which was designed with a narrow angular distribution of luminous intensity, were conducted to replace halogen lamps with LED lamps. Four types of LED lamps were fabricated, which have angular distributions of luminous intensity of $22.4^{\circ}$, $31.1^{\circ}$, $37.3^{\circ}$, and $59.9^{\circ}$ and luminous efficiencies of 76.5 lm/W, 75.2 lm/W, 72.0 lm/W, and 77.8 lm/W, respectively, while their spreading angles with an illuminance uniformity of 81% were $3^{\circ}$, $15^{\circ}$, $22^{\circ}$, and $49^{\circ}$, respectively. After eliminating a yellow tail of the LED lamps using a diffusion sheet, the angular distributions of the luminous intensity were measured to be $20.8^{\circ}$, $31.5^{\circ}$, $37.8^{\circ}$, and $68.7^{\circ}$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.3
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• pp.451-457
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• 2018

We propose an automatic detection and classification system of sewer damage database based on artificial intelligence and deep learning. In order to optimize the performance, we implemented a robust system against various environmental variations such as illumination and shadow changes. In our proposed system, a crack detection and damage classification method using a deep learning based Convolutional Neural Network (CNN) is implemented. For optimal results, 9,941 CCTV images with $256{\times}256$ pixel resolution were used for machine learning on the damaged area based on the CNN model. As a result, the recognition rate of 98.76% was obtained. Total of 646 images of $720{\times}480$ pixel resolution were extracted from various sewage DB for performance evaluation. Proposed system presents the optimal recognition rate for the automatic detection and classification of damage in the sewer DB constructed in various environments.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.76-76
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• 2000

최근 비정질 SiC 박막은 열과 광안정도면에서 비정질 Si 박막에 비해 우수하며 공정변수들을조절함으로써 비교적 쉽고 다양하게 광학적.전기적 특성을 얻을 수 있고, 낮은 광흡수계수 및 105($\Omega$cm)1 이상의 높은 전도도를 가지고 있어 Plasma Enhanced Chemical Vapor Deposition(PECVD)을 통해 가전자제어 (Valency electron control)가 가능한 비정질 SiC 박막이 제작된 이래 대한 많은 연구가 진행되고 있다. 결정성이 없는 비정질 물질은 상대적으로 낮은 온도에서 성장이 가능하며, 특히 glow-sidcharge 방식으로 저온에서 성장시킬 수 있음에 따라 유리등과 같은 다른 저렴한 물질을 기판으로 이용, 넓은 면적의 비정질 SiC 박막을 성장시켜 여러 분야의 소자에 응용되고 있다. 비정질 SiC 박막이 넓은 에너지띠 간격을 갖는 물질이라는 점과 화학적 안정성 및 높은 경도, 비정질성에 기인한 대면적 성장의 용이성 등의 장점이외에, 원자의 성분비 변화에 의해 에너지띠 간격(1.7~3.1eV)을 조절할 수 있다는 점은 광전소자의 응용에 큰 잠재성이 있음을 나타낸다. PECVD 방식으로 성장된 비정질 SiC 박막은 태양전지의 Window층이나 발광다이오드, 광센서, 광트랜지스터 등에 응용되어 오고 있다. 본 연구에서는, RF-PECVD(ULVAC CPD-6018) 방법에 의하여 비정질 Si1-xCx 박막을 2.73Torr의 고정된 압력에서 RF 전력(50~300W), 증착온도(150~30$0^{\circ}C$), 주입 가스량 (SiH4:CH4)등의 조건을 다양하게 변화시켜가며 증착된 막의 특성을 평가하였다. 성장된 박막을 X-ray Photoelectron Spectroscopy(XPS), UV-VIS spectrophotometer, Ellipsometry, Atomic Force Microscopy(AFM)등을 이용하여 광학적 밴드갭, 광흡수 계수, Tauc Plot, 그리고 파장대별 빛의 투과도의 변화를 분석하였으며 각 변수가 변화함에 따라 광학적 밴드갭의 변화를 정량적으로 조사함으로써 분자결합상태와 밴드갭과 광 흡수 계수간의상관관계를 규명하였고, 각 변수에 따른 표면의 조도를 확인하였다. 비정질 Si1-xCx 박막을 증착하여 특성을 분석한 결과 성장된 박막의 성장률은 Carbonfid의 증가에 따라 다른 성장특성을 보였고, Silcne(SiH4) 가스량의 감소와 함께 박막의 성장률이 둔화됨을 볼 수 있다. 또한 Silane 가스량이 적어지는 영역에서는 가스량의 감소에 의해 성장속도가 둔화됨을 볼 수 있다. 또한 Silane 가스량이 적어지는 영역에서는 가스량의 감소에 의해 성장속도가 줄어들어 성장률이 Silane가스량에 의해 지배됨을 볼 수 있다. UV-VIS spectrophotometer에 의한 비정질 SiC 박막의 투과도와 파장과의 관계에 있어 유리를 기판으로 사용했으므로 유리의투과도를 감안했으며, 유리에 대한 상대적인 비율 관계로 투과도를 나타냈었다. 또한 비저질 SiC 박막의 흡수계수는 Ellipsometry에 의해 측정된 Δ과 Ψ값을 이용하여 시뮬레이션한 결과로 비정질 SiC 박막의 두께를 이용하여 구하였다. 또한 Tauc Plot을 통해 박막의 optical band gap을 2.6~3.7eV로 조절할 수 있었다.

• Korean Journal of Food Science and Technology
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• v.40 no.2
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• pp.184-189
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• 2008

Effects of sucrose at different concentrations (0, 10, 20, and 30%, w/w) on steady and dynamic shear rheological properties of sweet potato starch (SPS) paste (5%, w/w) were investigated. The steady shear rheological properties of SPS-sucrose composites were determined from rheological parameters based on power law and Casson flow models. At 25$^{\circ}C$ all the samples showed pseudoplastic and thixoropic behavior with high yield stress. Consistence index (K), apparent viscosity (${\eta}_{a,100}$), and yield stress (${\sigma}_{oc}$) values of SPS-sucrose composites decreased with increasing sucrose concentration from 10% to 30%. The decrease of swelling power was observed at higher sucrose concentration (>20%) and the low swelling power yielded a lower K, ${\eta}_{a,100}$, and ${\sigma}_{oc}$ values. In temperature range of 25-70$^{\circ}C$, Arrhenius equation adequately assessed variation with temperature. Oscillatory test data showed weak gel-like behavior. Magnitudes of storage (G') and loss (G") moduli increased with an increase in sucrose concentration and frequency. The SPS-sucrose composite at 30% concentration closely followed the Cox-Merz superposition rule.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.394-394
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• 2015

급격히 변화하고 있는 산업화와 도시화로 지구 온난화 현상으로 기상이변의 발생빈도가 높아졌고 기후가 불안정하여 예전보다 많은 집중호우가 발생하면서, 홍수로 인한 제내지 침수가 발생되기도 한다. 기후변화로 인한 수재해에 대응하기 위하여 하천 호소 수리 예측 모형의 개선이 필요한 실정이다. 하지만, 자연하천 유역의 강우-유출 상관관계와 지표면 유출현상 및 하도 수리 특성을 자연현상의 복잡성, 강우발생의 시간적 공간적인 발생과정의 임의성, 정확한 해석방법 및 확률 분석에 따르는 불확실성 들을 토대로 단순한 이론과 제한적인 경험공식 등에 의해서 해석, 재현 및 평가를 한다는 것은 매우 어려운 문제이다. 최근 IT 기술의 발전과 더불어, 많은 연구자, 엔지니어들이 기존 수리 수문학적 지식과 IT기술을 융합하여 복잡 다단한 수자원 환경 문제를 해결하고자 한다. 이와 같은 최근 연구 동향에 의거하여, 본 연구에서는 HEC-RAS, TELEMAC-2D 1, 2차원 수리 모형을 연계하여 하천 흐름 분석 및 홍수 범람 해석에 적용하였다. 본 연구에서는 HEC-RAS, TELEMAC 모형을 적용하여 2012년 태풍 '산바(SANBA)'로 인해 홍수 피해를 입은 고령군에 위치한 낙동강 본류 회천 유역(상류 회천교 ~ 하류 도진교)의 하도 내 흐름 분석과 하천 인근 제내지 홍수범람을 예측하였다. 범람해석에 필요한 지형자료를 기초로 하여 각 지형의 조건에 맞게 수치자료를 이용하여 작성하였고, 수자원 정보를 이용하여 유랑, 수위 등 시계열자료를 지류 및 상 하류의 경계조건으로 설정하고, 조도계수 등 하천 기본정보들을 입력하였다. HEC-RAS 모형은 회천교부터 도진교까지 전구간에 대한 종단면과 횡단면별 홍수침수범위 및 홍수위 크기 등 거시적인 1차원 수리해석에 적용하였고, TELEMAC 모형은 HEC-RAS 시뮬레이션 결과를 바탕으로 HEC-RAS에서 나타내기 힘든 2차원 흐름특성, 침수현상 등 일부 범람 구간에 대해 수리해석에 적용하였다. HEC-RAS 시스템은 수공구조물들의 영향과 하천의 영향을 종 횡단면으로 다양한 홍수침수 범위를 1차원으로 나타 낼 수 있으며, TELEMAC 시스템 수리 모의를 통해 얻어진 결과는 유속, 유량, 수심, 하상고 높이 등 2차원으로 나타낼 수 있다. TELEMAC 시스템을 활용한 2차원 분석은 실측자료와 비교적 유사하고 시각, 공간적으로 이해하기 쉽게 표현되므로, 모형 적용성이 우수한 것으로 판단된다. 향후 유역 해석을 위한 수치데이터, 수위, 유량자료를 확보하여 HEC-RAS, TELEMAC 1, 2차원 연계 모형을 적용 한다면, 하천 준설, 하천 구조물 설치, 홍수피해 등 전반적인 하천관리 계획에 활용할 수 있을 것이라 판단된다.