• Journal of the Korea Institute of Information and Communication Engineering
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• 제18권9호
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• pp.2313-2321
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• 2014

A concentration meter is widely used at purification plants, sewage treatment plants and waste water treatment plants to sort and transfer high concentration sludge and to control the amount of chemical input. This study has been prepared for improving efficiency of operation on sludge processes and to establish a basic for factory automation by accuracy improvement and problem solution of sludge concentration meter. The concentration meter's accuracy and stability is improved by applying multi-beam sensors and minimum deviation linear average filtering. Furthermore maintenance without cut-off of water in sludge operation is possible by detachable sensors. The performance of multi-beam concentration meter has been variously verified by the pilot plant experiment.

• Journal of the Institute of Convergence Signal Processing
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• 제22권2호
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• pp.79-84
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• 2021

The most important device of the AGV is the guide sensor, and the typical function of this sensor is high accuracy and extraction of the road. If the accuracy of the guide sensor is low or the sensor device is extracted the wrong track, this causes the problems such as the AGV collision, track-out, the load falling due to AGV swing. In order to improve these problems, this study is proposed a signal processing method of the guide sensor based on multi-maskings and the center of gravity method, and evaluated its performance. As a result, the proposed method showed that the mean error of absolute value is 2.32[mm] and it showed performance improvement of 27[%] than the center of gravity method of existence. Therefore, when the proposed signal processing method is applied, It is thought that the posture control and driving stability of the AGV will be improved.

• Journal of Platform Technology
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• 제9권4호
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• pp.60-70
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• 2021

This paper proposes a method capable of stably tracking the coordinates of a patterned laser image in a curved screen shooting system using two or more channels of multiple cameras. This method can track and acquire target points very effectively when applied to a multi-screen shooting method that can replace the HMD shooting method. Images of curved screens with severe deformation obtained from individual cameras are corrected through image normalization, image binarization, and noise removal. This corrected image is created and applied as an Euclidean space map that is easy to track the firing point based on the matching point. As a result of the experiment, the image coordinates of the pattern laser were stably extracted in the curved screen shooting system, and the error of the target point position of the real-world coordinate position and the broadband Euclidean map was minimized. The reliability of the proposed method was confirmed through the experiment.

• Proceedings of the Korea Water Resources Association Conference
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• 한국수자원학회 2023년도 학술발표회
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• pp.4-4
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• 2023

C-band SAR 센서를 탑재한 수자원위성은 한반도 수자원 모니터링을 위해 개발되어 2025년 발사가 계획되어 있으며, 수변환경 및 부유물 탐지 및 다양한 활용이 기대되고 있다. 그 중 수변환경은 수변 생태계 안정성을 유지하는 역할을 담당하여 이에 대한 모니터링은 중요하다. s현장 관측 기반 탐지 방법과 비교하여 위성 원격탐사는 광범위한 지역을 반복적으로 관측하여, 연속적인 수변환경 및 부유물 정보를 제공할 수 있다. 이러한 특성에 기반하여 다양한 다중분광 및 SAR (Synthetic Aperture Radar) 위성 원격탐사 자료를 바탕으로 수변환경 및 부유물의 탐지 연구가 이루어졌다. 특히 단일 영상만을 사용하는 기법에 비해 다중분광 및 SAR 영상을 융합하여 높은 정확도를 보인 바 있다. 초기 연구에서는 임계값 알고리즘 또는 현장관측 기반의 부유물 농도와 위성 자료간의 선형관계를 분석하는 단순한 알고리즘이 주를 이루었으나, 최근에는 RF, CNN 등 보다 복잡하고 다양한 인공지능 알고리즘이 적용되어 높은 정확도로 해당 문제들을 해결하고 있다. 본 연구에서는 수자원위성 활용을 위해 인공지능 기반 수변환경 및 부유물 탐지 알고리즘을 개발하고자 한다. 수자원위성의 대체 자료로 유럽우주국의 Sentinel-1 A/B 위성의 C-band SAR 영상을 이용하였으며, 보조자료로 Sentinel-2 다중분광 영상을 이용하였다. 개발된 알고리즘은 수자원 관리를 위한 환경변화 탐지에 유용한 정보로 활용될 수 있을 것으로 기대된다.

• Transactions of the Korean Society of Mechanical Engineers
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• 제10권4호
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• pp.463-470
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• 1986

본 연구에서는 절삭공정 중 발생하는 공구의 접촉이탈 현상에 의하여 공작 물의 절삭된 표면중에 한회전 및 그 이전 회전에 절삭된 절삭면의 형상이 현재의 절삭 깊이에 영향을 미치는 다중재생효과(multiple regenerative effect)가 존재하는 선삭 작업에서 공구의 착탈현상을 고려한 비선형채터(nonlinear chatter)를 공작기계의 생 산성의 관점에서 절삭공정의 특성을 고려하여 해석하였으며, 수동제어기의 일종인 임 펙트댐퍼를 절삭공정에 응용하여 절삭작업중에 공작기계의 안정성향상 뿐만 아니라 생 산성의 증가효과를 규명하였다.아울러 댐퍼자체의 설계변수에 따른 채터 억제효과 를 고려하여 최적의 댐퍼를 설계하는 방법을 제시하였다.

• Proceedings of the KIEE Conference
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1414-1415
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• 2011

높은 게이트와 드레인 바이어스 스트레스 조건에서 신뢰성을 높이기 위해 비대칭 스페이싱 다중채널 구조 (ASS) 를 이용한 다결정 실리콘 박막 트래지스터 (poly-Si TFTs) 를 제안하였다. 이것은 어떠한 추가공정 없이 제작할 수 있고 채널 가운데 부분의 넓은 공간을 이용하여 소자안의 유도된 열을 방출할 수 있기 때문에 기존의 트랜지스터에 비해 47%의 문턱전압감소와 3%의 이동도 변화 감소를 보인다. 이 실험결과는 제안된 소자구조가 기존의 소자에 비해 높은 게이트와 드레인 바이어스 조건에서 전기적 특성이 더 안정적이라는 것을 보여준다.

• Journal of Korea Multimedia Society
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• 제6권6호
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• pp.1025-1033
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• 2003

The CDN is proposed as a solution of network bottleneck problem resulting from the rapid growth of Internet user and multimedia contents on the Internet. This paper suggests MDC and path diversity between CDN Edge server and end-user, and multicast transmission among CDN servers based on CDN infrastructure. It may be a solution for reliable and fast transmission of rich multimedia contents. These research will support to solve the unreliable transmission problem of multicasting and to create the new business models in the field of web contents.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• 제18권2호
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• pp.133-141
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• 2020

A geological repository comprises a natural barrier and an engineered barrier system. Its design components consist of canisters, buffers, backfill, and near-field rock. Among the engineered barrier system components, bentonite buffers minimize the groundwater flow from near-field rock and prevent the release of nuclide. Investigation of the hydraulic conductivity of the buffer to groundwater flow is an important factor in the performance evaluation of the stability and integrity of the engineered barrier of the repository. In this study, saturated hydraulic conductivity tests were performed using Gyeongju bentonite at various dry densities and temperatures, and a hydraulic conductivity prediction model was developed through multiple regression analysis using the 120 result sets of hydraulic conductivity. The test results showed that the hydraulic conductivity tends to decrease as the dry density increases. In addition, the hydraulic conductivity increased with increasing temperature. The multiple regression analysis results showed that the coefficient of determination (R²) of the hydraulic conductivity prediction equation was as high as 0.93. The hydraulic conductivity prediction equation presented in this study could be used for the design of engineered barrier systems.

• Journal of the Korean Applied Science and Technology
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• 제37권6호
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• pp.1517-1527
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• 2020

This study is about the UV protection effect and water resistance of a multiple emulsion (W/O/W) sunblock cream applied with emotional engineering and reports an actual industrial case. Multiple emulsion system of sunblock cream has the characteristics of changing to a W/O type that is soft and moist when applied, and has excellent water resistance after absorption. Multiple emulsion cream is a highly functional sunblock cream that has both moisture and water resistance. It is a stable milky white cream with a viscosity of 36,000 cps. The organic sunscreen used for the sunscreen was ethylhexylmethoxycinnamate and bisethylhexyloxyphenolmethoxyphenyltriazine. Hexagonal zinc oxide and titanium dioxide that block both UVB and UVA were used. As a result of measuring the UV protection effect by the in-vitro method, the UV protection effect (SPF) is 78.9 for multiple emulsion cream, 76.7 for W/O cream, and 71.3 for O/W cream. It was found that the blocking effect was different. This obtained the highest effect value in the multiple emulsion. As a clinical (in-vivo) result of the UV protection effect, the SPF value representing the UV protection effect of the sunblock cream developed with a multiple emulsion system was 85.7, and the PA-value that blocks the UVA area was 26.5, and ++++. It was found that it has a corresponding high blocking effect. As a result of the water resistance test, the W/O/W formulation had a high waterproofing resistance of 93.8% even after 4 hours, W/O had 75.4%, and O/W had a low water resistance of 25.3%. In the results of the HUT test, it was found in the order of multiple emulsion sun block cream > hydrophilic cream > lipophilic cream. Based on the research results of this multiple emulsion, it is expected to be highly active as a sunblock cream dedicated to outdoor activities by improving the feeling of use, UV protection index, and water resistance. Therefore, in this study, a multiple emulsion system of sunblock cream is developed and has a characteristic that changes to a W/O type that has a soft and moist feeling when applied, and has excellent water resistance after absorption.

• Journal for History of Mathematics
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• 제18권2호
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• pp.107-116
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• 2005

A suspension bridge is an example of a nonlinear dynamical system, especially systems with the so called jumping nonlinearity. The fact that we deal with a serious and topical problem is demonstrated for example by the collapse of the Tacoma Narrow suspension bridge. So it would be very contributive to determine under what conditions a similar situation cannot occur and find out safe parameters of the bridge construction. In this paper, we show various possibilities how to model the behaviour of suspension bridge. Then we introduce our own results concerning existence and uniqueness of time-periodic solutions.