• Fire Science and Engineering
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• v.20 no.1 s.61
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• pp.71-76
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• 2006

The major causes of electrical fire are classified to short circuit fault, overload fault, electric leakage and electric contact failure. The occurrence factor of the fire is electric arc or spark accompanied with electrical faults. Residual Current Protective Device(RCD) of high sensitivity type used at low voltage wiring cuts off earth leakage and overload, but the RCD can't cut off electric arc or spark to be a major factor of electrical fire. As the RCDs which are applied low voltage distribution panel are prescribed to rated breaking time about 30[ms](KS C 4613), the RCDs can't perceive to the periodic electric arc or spark of more short wavelength level. To be improved on such problem, this paper is proposed to a auxiliary control apparatus for RCD trip on electric arc or spark due to electrical fire. Some experimental results of the proposed apparatus is confirmed to the validity of the analytical results.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2206-2207
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• 2008

본 논문에서는 분전반에서의 화재 위험 요소와 화재위험 요소에 대한 현장 실태조사 결과를 분석하였다. 분전반에서의 화재 위험 요소는 크게 전기적 요인, 환경적 요인, 물리적 요인으로 나눌 수 있으며 전기적 요인으로는 단락, 과부하(과전류), 접촉불량, 전류 불평형 등이 있으며 환경적 요인으로는 수분(염분 등), 먼지(분진, 목분, 철분 등), 온도(고온) 등에 의한 절연파괴, 기기 손상, 오동작 등이 있다. 물리적 요인으로는 기계적인 진동이나 충격 등에 의한 전기적 접속부의 이완에 의한 발열 등을 들 수 있다. 이러한 화재 위험 요인에 대하여 현장실태조사를 실시한 결과, 일부 분전반에서 내부에 먼지 등 이물질이 차단기, 전선, 단자대 등의 표면에 부착되어 있음을 확인할 수 있었으며 수분이나 염분 등의 영향으로 전극간 절연물 표면의 열화로 화재가 발생할 가능성이 있다. 또한, 적외선 열화상 분석결과, 일부 차단기 단자에서 국부 발열이 관측되었으며, 부하 분담의 불평형에 의한 발열도 확인되었다. 이러한 위험요인에 의한 화재 예방을 위하여 규정된 전선 굵기의 사용과 적정 체결압력의 확보, 상간 전류 불평형을 줄이기 위한 부하 분담의 조정이 필요하다. 향후, 분전반에서의 전기화재, 감전사고 등 전기재해의 예방을 위하여 지속적이고 체계적인 유지관리는 물론 사고 발생 전에 이상 징후를 사전에 감지하여 조치를 취할 수 있도록 하는 기술의 개발과 현장 적용이 요구된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5838-5842
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• 2011

The study mainly aims to explore how deterioration of motor control center, namely MCC, and vibration put impact on temperature of bus bar as well as temperature change of bolt-nut joint. The motor control center consists of three internal parts (i.e. R, S, T) which are for motor operation of high capacity. Two dimensional mechanism for measuring temperature was designed and manufactured with infrared temperature sensor. Installing it in inner motor control center enabled researcher to monitor temperature of bus bar as well as amount of change of current regularly. Temperature change of bus bar according to load was primarily examined based on a bolted joint in the experiment. It was clearly verified that temperature change of bus bar was proportional to current consumption. Therefore, installing non-contact two dimensional mechanism for measuring temperature in motor control center would be expected to prevent temperature rise owing to overload current and power outage as well as fire accident which can be triggered by poor electrical contact.

• Journal of Sensor Science and Technology
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• v.6 no.4
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• pp.298-306
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• 1997

Ultrasonic sensors are widely used in various applications due to advantages of low cost, simplicity in construction, mechanical robustness, and little environmental restriction in usage. But the main purposes of the noncontact sensors are rather narrowly confined within object detection and distance measurement. For the application of object recognition, ultrasonic sensors exhibit several shortcomings of poor directionality which results in low spatial resolution of an object, and specularity which gives frequent erroneous range readings. To resolve these problems in object recognition, an array of the sensors has been used. To improve the spatial resolution, more number of sensors are used in essence throughout the various devices of the sensor arrays. Under the disguise of a fixed number of the sensors, the array can be shifted mechanically in several steps. In this paper we propose a practical sensor resolution enhancement method using an electronic circuit accompanying the sensor array. The circuit changes the transmitter output voltage in several steps. Using the known sensor characteristics, a set of different return echo signals provide enhanced spatial resolution. The improvement is obtained without the cost of the increased number of the sensors nor extra mechanical devices.

• Journal of the Institute of Convergence Signal Processing
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• v.22 no.3
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• pp.128-133
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• 2021

Recently Recently, the incidence of spinal diseases due to poor posture among students and office workers is increasing, and various studies have been conducted to help maintain correct posture. In previous studies, a membrane sensor or a pressure sensor was placed on the seat cushion to see the weight bias, or a sensor that restrained the user was attached to measure the position change. In our previous study, we developed a sensor device which can be easily attached to the body with an adhesive gel sheet and that measures and outputs the user's posture and body position in real time, but it has a limitation in the accuracy of the sensor value. In this study, a study was conducted to improve the performance of the position conversion sensor device and quantitatively evaluate the accuracy of the angle conversion measurement value, and a high accuracy with 2.53% of error rate was confirmed. In future research, it is considered that additional research targeting actual users is needed by diversifying posture correction training contents with multimedia elements added.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.213-215
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• 2022

Recently, deep learning technology that processes images has been widely used in fire detection, autonomous driving, and defective product detection. In particular, in order to determine whether a product is contaminated or not, it can be identified through the contaminants passed from the existing sensor data, but technologies for recognizing cracks in products or contaminants themselves as images are being actively studied in various fields. In this paper, a system for classifying uncontaminated normal cups and contaminated cups through images was designed and implemented. The image was analyzed using an open image and a photographed image, and the image was analyzed by extracting the upper part of the cup image using Google Objectron for 3D object recognition. Through this study, it is thought that it will be used in various ways for research that can extract the contamination level of products required in the hygiene field based on images.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.24-33
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• 2017

Multitemporal MODIS vegetation index (VI) data are widely used in vegetation monitoring research into environmental and climate change, since they provide a profile of vegetation activity. However, MODIS data inevitably contain disturbances caused by the presence of clouds, atmospheric variability, and instrument problems, which impede the analysis of the NDVI time series data and limit its application utility. For this reason, preprocessing to reduce the noise and reconstruct high-quality temporal data streams is required for VI analysis. In this study, a data reconstruction method for MODIS NDVI is proposed to restore bad or missing data based on the statistical properties of the oscillations in the NDVI temporal dynamics. The first derivatives enable us to examine the monotonic properties of a function in the data stream and to detect anomalous changes, such as sudden spikes and drops. In this approach, only noisy data are corrected, while the other data are left intact to preserve the detailed temporal dynamics for further VI analysis. The proposed method was successfully tested and evaluated with simulated data and NDVI time series data covering Baekdu Mountain, located in the northern part of North Korea, over the period of interest from 2006 to 2012. The results show that it can be effectively employed as a preprocessing method for data reconstruction in MODIS NDVI analysis.

• Journal of the Korean Institute of Gas
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• v.22 no.2
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• pp.78-83
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• 2018

The purpose of this paper is to study for failure examples of emission gas recirculation and air control and catalyzed particulate filter system in diesel engine vehicle. The first example, the researcher found the fact that the much engine oil came into the intake manifold causing diaphragm damage of EGR valve. The engine oil entered into combustion chamber of engine so that a car emit the polluted exhaust gas when driving. The second example, the researcher certified the sticking phenomenon of carbon and foreign substance with the throttle flap so that the exhaust fumes discharged exhaust port. The third example, the regeneration function don't activated to not detect the temperature of exhaust gas because of damage in the sensor. Thus, the researcher must meticulously manage his car not in order to take place the problem of environmental pollution.

• Fire Science and Engineering
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• v.6 no.2
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• pp.15-24
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• 1992

우리나라는 1960년대의 경제개발계획에 따른 공업화 시축의 추진으로 산업의 발달과 경제성장은 인구를 도시로 집중시키면서 도시건축물은 대형화, 고층화, 과밀화 현상을 가져왔다. 한편, 국민생활의 향상과 산업활동의 다양화로 화재발생의 주요원인이 되는 전기, 가스, 유류등의 사용량이 해마다 늘어나고 있어 화재의 위험을 가중시키고 있다. 최근 10연간('81~'90) 전국에서 발생한 화재사고는 9만 5,154건이 발생하여 인명피해 1만1,117명, 재산피해 1,859억 2,200만원의 많은 손실을 가져 왔으며, 이 중에는 서울에서 발생한 화재가 3만6,089건으로 전체의 37.9%을 차지하고 있다. 화재가 발생할 경우 대형 참사를 방지하고 귀중한 인명피해는 물론 경제적 손실을 최저로 줄일 수 있는 소방시설을 도시건축물에 설치하여 이에 대비하는 것이 무엇보다 귀중한 일이다. 이는 화재예방 또는 발생 초기에 이를 감지, 통보하고 피난하며 소화활동에 이르는 모든 방재 및 소화를 위한 소방시설의 유용성을 최대로 발휘할 수 있기 때문이다. 본 논문에서는 서울특별시를 중심으로 도시건축물에 설치된 소방시설의 유지 관리 실태와 화재시 소방시설의 이용실태를 분석하여 문제점을 도출하고 이에 대한 개선방향을 제시하므로서 예방소방행정의 발전을 기하고저 하였으며, 그 내용을 요약하면 다음과 같다. 제1장에서는 서론부분으로서 연구의 목적과 범위및 접근 방법을 서술하였고, 제2장에서는 도시소방행정의 특성 및 소방환경의 변화로 먼저 소방행정의 의의와 도시소방행정의 유형으로 예방소방과 진압소방 그리고 구급.구조업무등을 살피고. 도시소방환경변화에 따른 화재발생추세를 살펴 보았다. 제3장에서는 도시건축물에 설치하는 소방시설의 설치.유지 및 이용실태를 검사.분석하였다. '90년도 서울시내 소방서에서 실시한 소방대상물에 대한 소방검사와 방화관리자에 대한 설문조사를 실시하여 소방시설의 유지관리실태를 통계.분석한 결과, 소방시설이 양호한 소방대상물은 전체의 75.9%이며, 불량소방대상물은 24.1%로 나타났다. 그리고 화재가 발생한 소방검사대상물에 대한 화재현장 조사결과 화재시 소방시설을 사용한 소방대상물은 전체의 72.1%를 차지하고 있다. 제4장에서 는 소방시설의 문제점으로 \circled1 소방설비부실공사, \circled2 소방시설 유지관리능력부족, \circled3 소방검사제도 불합리등이며, 이에 대한 개선방향으로 \circled1 소방설비 시공자의 지도. 감독강화, \circled2 자체시설관리능력향상, \circled3 예방소방행정제도의 개선을 제시하였다. 제5장은 결론으로, 우리나라가 최근 경제성장과 산업의 발달로 도시건축물의 화재발생 위험이 가중되면서 이에 대한 소방안전대비책이 요구된다. 이에는 도시건축물에 방화시설과 소방시설을 완비하고, 그리고 자격있고 유능한 방화관리자 선임하여 자체 소방계획을 수립하여 시설점검, 정비와 유지관리를 철저히 한다면 어떠한 화재도 예방 또는 초기에 진압할 수 있고, 또한 입주검자에 대한 소방교육 및 훈련을 지속적으로 수행하여 나간다면 여하한 도시건축물의 소방안전도 그 목적을 달성하리라고 생각한다.

• Journal of radiological science and technology
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• v.40 no.4
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• pp.639-646
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• 2017

The purpose of this study is to present the algorithm to minimize the image noise caused by deterioration of high X-ray container inspection equipment and the faulty detection sensors, and to improvement quality of the container inspection images using MATLAB Toolbox. The daily checking images for the container inspection were used with the subject images and the noise caused by the horizontal and vertical images was evaluated with Root Mean Square (RMS) method, which is the most basic evaluation method of digital radiation image. Also, quality of the improved images was evaluated compared to quality of the orignal images. As a result, all RMS value of the improved images was lower then the original images by a mean of 13.5% in the horizontal images and 18.2% in the vertical images respectively. Also so did RMS value of the improved container images, by a mean of 13.4% in the horizontal images and 19.1% in the vertical images respectively. These findings can be verified objectively and visually and they would help the reading process of the container images be effective in Korea Customs Service.