• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.512-514
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• 2004

The Electro-Optical Camera (EOC) is a high spatial resolution, visible imaging sensor which collects visible image data of the earth's sunlit surface and is the primary payload on KOMPSAT-l. The purpose of the EOC payload is to provide high resolution visible imagery data to support cartography of the Korean Peninsula. The EOC is a push broom-scanned sensor which incorporates a single nadir looking telescope. At the nominal altitude of 685Km with the spacecraft in a nadir pointing attitude, the EOC collects data with a ground sample distance of approximately 6.6 meters and a swath width of around 17Km. The EOC is designed to operate with a duty cycle of up to 2 minutes (contiguous) per orbit over the mission lifetime of 3 years with the functions of programmable gain/offset. The EOC has no pointing mechanism of its own. EOC pointing is accomplished by right and left rolling of the spacecraft, as needed. Under nominal operating conditions, the spacecraft can be rolled to an angle in the range from +/- 15 to 30 degrees to support the collection of stereo data. In this paper, the status of EOC such as temperature, dark calibration, cover operation and thermal control is checked and analyzed by continuously monitored state of health (SOH) data and image data during the mission life of 3 years. The aliveness of EOC and operation continuation beyond mission life is confirmed by the results of the analysis.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.756-759
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• 2006

The ocean tide loading (OTL) is an important factor for the GPS positioning, especially in the height direction. The shorter of the distance to the ocean, the larger of the error by the OTL. The influence will be changed when we measure in different place and the order of magnitude is from few centimeters to ten centimeters. In this study, more than ten kinds of the OTL models were collected and applied on the GPS static relative positioning in Taiwan. The GPS observations including five stations were obtained from Nov. 9, 2004 to Feb. 23, 2005 and we used the Bernese GPS software to execute the data processing. In this period, the average amplitudes of the 3-D coordinates are as follows: N is 0.4 cm, E is 0.7 cm, h is 1.8 cm at Kinmen station; N is 0.7 cm, E is 1.3 cm, h is 2.3 cm at Lanyu station; N is 0.5 cm, E is 0.7 cm, h is 2.0 cm at Matsu station; N is 0.6 cm, E is 0.6 cm, h is 2.0 cm at Penghu station and N is 0.5 cm, E is 1.2 cm, h is 1.7 cm at Hsinchu station. Moreover, we will analyze the advantage and disadvantage of every kind of the OTL models in different environments to offer some information to the GPS users and enhance the precision of the GPS positioning.

• Journal of Welding and Joining
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• 제16권5호
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• pp.119-133
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• 1998

To implement full automation in pipe welding, it si most important to develop special sensors and their related systems which act like human operator when detecting irregular groove conditions. In this study, an automatic pipe Gas Metal Arc Welding (GMAW) system was proposed to full control pipe welding procedure with intelligent sensor systems. A five-axes manipulator was proposed for welding torch to automatically access to exact welding position when pipe size and welding angle were given. Pool status and torch position were measured by using a weld-pool image monitoring and processing technique in root-pass welding for weld seam tracking and weld pool control. To overcome the intensive arc light, pool image was captured at the instance of short circuit of welding power loop. Captured image was processed to determine weld pool shape. For weld seam tracking, the relative distance of a torch position from the pool center was calculated in the extracted pool shape to move torch just onto the groove center. To control penetration of root pas, gap was calculated in the extracted pool image, and then weld conditions were controlled for obtaining appropriate penetration. welding speed was determined with a fuzzy logic, and welding current and voltage were determined from a data base to correspond to the gap. For automatic fill-pass welding, the function of human operator of real time weld seam control can be substituted by a sensor system. In this study, an arc sensor system was proposed based on a fuzzy control logic. Using the proposed automatic system, root-pass welding of pipe which had gap variation was assured to be appropriately controlled in welding conditions and in torch position by showing sound welding result and good seam tracking capability. Fill-pass welding by the proposed system also showed very successful result by tracking along the offset welding line without any control of human operator.

• Current Optics and Photonics
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• 제4권1호
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• pp.1-8
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• 2020

We research a system of compressed-sensing computational ghost imaging (CSCGI) based on the intensity fluctuation brought by turbulence. In this system, we used the gamma-gamma intensity-fluctuation model, which is commonly used in transmission systems, to simulate the CSCGI system. By setting proper values of the parameters such as transmission distance, refractive-index structure parameter, and sampling rates, the peak signal-to-noise ratio (PSNR) performance and bit-error rate (BER) performance are obtained to evaluate the imaging quality, which provides a theoretical model to further research the ghost-imaging algorithm.

• Spatial Information Research
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• 제3권2호
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• pp.91-102
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• 1995

본 연구의 목적은 북한산 국립공원 경계선 일대의 추이대를 탐지하는 기법을 개발하여 추이대의 폭을 조사하고, 추이대의 폭과 환경요인과의 관계를 규명하는 것이다. 이를 위해서 1985, 1987, 1993년 5월 중순에 수신된 TM영상을 이용하여 계산한 정규식생지수(NDVI)를 도출하고, 버퍼링작업에 의하여 경계선으로 부터으 거리별 NDVI를 산출하여 추이대를 조사하는 방법을 제시하였다. 연구 결과 본 연구대상지의 추이대의 식생은 생물계절(phenology), 인접지역의 토지이용의 영향을 받는 것이 확인되었으며, 1993년에는 1985년에 비해서 추이대의 폭이 약 2배로 증대되어 탐방객의 과도한 이용 등으로 인하여 식생 피해지역의 범위가 확대되고 있는 것으로 판명되었다.

• 농업과학연구
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• 제42권1호
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• pp.63-71
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• 2015

Path planning is an essential part for traveling and mowing of autonomous lawn mower tractors. Objectives of the paper were to analyze operation patterns by a skilled farmer, to extract and optimize waypoints, and to demonstrate generation of formatted planned path for autonomous lawn mower tractors. A 27-HP mower tractor was operated by a skilled farmer on grass fields. To measure tractor travel and operation characteristics, an RTK-GPS antenna with a 6-cm RMS error, an inertia motion sensing unit, a gyro compass, a wheel angle sensor, and a mower on/off sensor were mounted on the mower tractor, and all the data were collected at a 10-Hz rate. All the sensor data were transferred through a software program to show the status immediately on the notebook. Planned path was generated using the program parameter settings, mileage and time calculations, and the travel path was plotted using developed software. Based on the human operation patterns, path planning algorithm was suggested for autonomous mower tractor. Finally path generation was demonstrated in a formatted file and graphic display. After optimizing the path planning, a decrease in distance about 13% and saving of the working time about 30% was achieved. Field test data showed some overlap, especially in the turning areas. Results of the study would be useful to implement an autonomous mower tractor, but further research needs to improve the performance.

• 한국인터넷방송통신학회논문지
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• 제10권5호
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• pp.209-213
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• 2010

본 논문에서는 차량용 네트워크인 CAN(controller area network)와 연계되어 다양한 안전진단을 가능하게 하는 안전진단 센서하드웨어를 구현하고 그 성능을 확인하였다. 본 연구를 통하여 새롭게 설계 및 구현된 안전진단센서 하드웨어는 차량용 CAN인터페이스와 연결되며, 안전진단을 위한 다양한 센서(충돌센서, 거리 센서 등)의 데이터를 취득하고 이를 처리하여 CAN, RS232, RS485, I2C등의 통신인터페이스를 통해 전송하는 구조를 가지고 있다. 본 논문에서는 새롭게 설계 제작된 CAN연계형 안전진단 센서보드의 동작을 센싱 데이터와 연계하여 다양한 상황에서 그 성능을 검증함으로서 개발된 하드웨어의 유용성을 확인하였다.

• 융합보안논문지
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• 제14권7호
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• pp.29-36
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• 2014

본 연구에서는 최근 각광받고 있는 융합기술 중의 하나인 가시광 통신 기술을 개발하고 실제 시제품을 구현하기 위한 시스템 기술에 대해서 기술한다. 본 논문에서는 현재 개발 중인 LED기반 VLC 시스템 기술을 송신부로서 아날로그 LED 드라이브 모듈, 디지털 변조 모듈 및 수신부로 광신호 센싱모듈, 신호복조 모듈로 분류하고 개별 모듈에 대한 구체적인 개발 시스템에 대해서 소자 및 주요 부품의 특성을 기반으로 제시하고 분석한다. 또한 통신 검증을 위해 VLC 송 수신 시뮬레이터를 설계하여 디밍 조절과 플리커 현상에 대한 부분까지 검증 가능하도록 개발하였다. 실제 개발된 시스템을 통해 약 0.5m 거리에서 약 12Mbps의 고속 데이터 전송이 가능함을 확인하였고, 다양한 멀티미디어 데이터까지 실시간으로 전송 가능함을 확인하였다. 본 연구에서 개발된 기술은 가정 내 또는 실내 주차장 등과 같이 실내 측위 또는 조명과 함께 다양한 융합 데이터 서비스 등에서 중요한 역할을 할 것으로 기대된다.

• Parasites, Hosts and Diseases
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• 제54권4호
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• pp.439-446
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• 2016

Toxoplasmosis is a protozoan disease that is caused by Toxoplasma gondii in livestock and humans. Due to its medical and veterinary importance, it is essential to study the seroprevalence of T. gondii infection among humans and animals in various parts of the world. The major objective of this study was to determine the seroprevalence and spatial distribution of toxoplasmosis in small ruminants (sheep and goats) of north-eastern region, Pakistan. A total of 1,000 animals comprising of sheep (n=470) and goats (n=530) were examined for T. gondii infection by using ELISA. An epidemiological data was collected in the form of questionnaire. A surface has been generated by using method of interpolation in Arc GIS with the help of IDW (inverse distance weight). The results showed higher seroprevalence of T. gondii in goats (42.8%) as compared to sheep (26.2%). The seroprevalence was higher in females as compared to males in all examined ruminants. Similarly, there is a wide variation in the seroprevalence of T. gondii in different breeds of sheep and goats showing higher seroprevalence in Teddy (52.8%) and Damani breed (34.5%) of goat and sheep's, respectively. The geographical and spatial distribution of T. gondii shows that it is widely distributed in different parts of the north-eastern region of Pakistan. Our results suggest widespread environmental contamination with T. gondii oocysts and that small ruminants could be a potentially important source of T. gondii infection if their infected meat is consumed undercooked.

• 대한임베디드공학회논문지
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• 제15권5호
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• pp.215-225
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• 2020

Light detection and ranging (LiDAR) sensors detect the distance of the surrounding environment and objects. Conventional LiDAR sensors require a certain amount of a power because they detect objects by transmitting lasers at a regular interval depending on a constant resolution. The constant power consumption from operating multiple LiDAR sensors is detrimental to autonomous and electric vehicles using battery power. In this paper, we propose two algorithms that improve the inefficient power consumption during the constant operation of LiDAR sensors. LiDAR sensors with algorithms efficiently reduce the power consumption in two ways: (a) controlling the resolution to vary the laser transmission period (T_P) of a laser diode (LD) depending on the vehicle's speed and (b) reducing the static power consumption using a sleep mode depending on the surrounding environment. A proposed LiDAR sensor with a resolution control algorithm reduces the power consumption of the LD by 6.92% to 32.43% depending on the vehicle's speed, compared to the maximum number of laser transmissions (N_x·max). The sleep mode with a surrounding environment-sensing algorithm reduces the power consumption by 61.09%. The proposed LiDAR sensor has a risk factor for 4-cycles that does not detect objects in the sleep mode, but we consider it to be negligible because it immediately switches to an active mode when a change in surrounding conditions occurs. The proposed LiDAR sensor was tested on a commercial processor chip with the algorithm controlling the resolution according to the vehicle's speed and the surrounding environment.