• Journal of the Korean Chemical Society
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• v.55 no.2
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• pp.157-162
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• 2011

In the present study, we developed a portable GC module for real-time, quantitative determinations of gas mixtures in air sample. Capillary or packed column was coiled together with a heater wire and thermocouple in a small case. Together with the small and light weight sensors and valves as well as the rechargeable carrier gas canister, which permits collection and separation of samples, this system can determine the components of complex mixtures of air contaminants at low concentrations with a duty cycle of 10 min. When measured the various samples with a FID and TCD, the system showed, for a capillary column, a good resolution (R=8.3), high sensitivity, reproducibility, and linear dynamic range greater than three orders of magnitude. These results indicate that the portable GC module is expected to be used for a wide range of applications, particularly for in situ environmental monitoring, chemical processes, and regulation of contaminant emission.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.2D
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• pp.203-208
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• 2011

Traffic demand is continuously increasing due to the development of urban areas in Korea. To cope with this, many efforts have been done including constructions of new roadways and increasing the number of lanes of the existing roadways. Those efforts, however, have been performed for only a short segment of target links having similar traffic characteristics. As a result, most urban cities experience bottle-neck phenomena which lead decreasing flow speed and increasing possibilities of accidents. Thus, this study aims to analyze problems of bottle-neck phenomena and effects of balancing number of lanes along the same corridor having similar traffic characteristics. For this, Route 32 passing the city of Daejeon in Korea has been selected as a case study, and a micro-simulation tool, VISSIM, has been adopted for the analysis. The results show that balanced number of lanes along the same corridor with similar traffic characteristics can increase flow speeds and enhance safety.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2025-2027
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• 2003

미끄럼방지 제동장치는 차량의 급제동 시 바퀴의 장김을 방지하여, 바퀴의 슬립을 최적으로 유지 시킴으로써 제동거리를 단축시키고, 운전자가 차량 조향성을 유지할 수 있게 만드는 차량 안정장치이다. 이 장치는 비행기의 착륙거리를 줄이기 위해 개발된 이래로, 철도 및 차량 등에도 널리 적용되고 있으며, 국내에서도 이미 승용차를 위주로 양산되고 있는 추세이다. 이러한 미끄럼방지 제동 장치는 공압 브레이크 장치를 사용하는 대형차량 분야에서는 아직 국내에서 적용된 사례가 없었으나, 지난 3 년간의 연구개발의 성과로 대형 버스에 적용 가능한 미끄럼방지 제동장치의 전자제어기가 개발 완료되었으며, 국제 규격을 바탕으로 국내 현실에 적합한 미끄럼방지 제동장치 장착 대형차량의 시험 규격을 정하여 이 규격에 의거 제동시험을 실시하고 개발 제어기의 성능을 평가하였다. 각 제동 시험은 $\mu$-Jump 제동시험 및 Split-$\mu$ 제동시험 등의 직진 주행 중 급제동시험, 급제동 중 차선변경 시험, 장애물 회피 제동시험 등을 포괄하며 국제적인 규격을 기준으로 정한 독자 규격을 만족하였다. 본 논문에서는 공압 브레이크를 장착한 대형차량의 미끄럼방지 제동장치의 제동성능평가 시험방법을 소개하고, 이 방법에 의해 성능평가 시스템 및 측정 시스템을 구성하여, 개발 전자제어기의 우수성을 확인하였으며, 그 측정결과의 일부를 제시하였다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.494-500
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• 2002

본 연구의 목적은 DGPS와 자이로 센서를 장착하여 무인으로 콤바인을 직선주행, 선회 및 곡선주행, 직진주행 중 1 m 오프셋(offset) 주행시켰을 때, 무인 자율주행의 성능을 분석하고 개선하는데 있다. 콤바인의 무인자율주행 시스템은 콤바인의 현재위치를 인식하고, 주행하고 있는 콤바인의 주행방향을 감지하여 미리 설정된 경로를 따라 자율적으로 주행하며, 주행 중에 장애물이 검출되면 정지할 수 있도록 개발하였다. 콤바인의 무인 자율주행시스템은 DGPS의 입력 신호로부터 콤바인의 현재위치를 결정하고, 자이로 센서의 입력신호로부터 주행방향을 알 수 있다. 또한 장애물의 감지를 위한 초음파 센서, 콤바인의 주행방향을 조정하는 유압 작동부, 좌.우의 조향레버를 조정하는 서보모터 시스템, 마이크로 컴퓨터로 구성된 제어기와 입출력 인터페이스로 구성되어 있다. 콤바인 자율주행시스템의 프로그램은 DGPS 신호, 자이로 센서 등을 수신하는 수신 프로그램, DGPS 신호등으로부터 관련 변수들을 분석하여 콤바인의 조향수준을 결정하고, 유압실린더 등을 제어하는 제어 프로그램과 콤바인의 이동경로를 저장하는 저장 프로그램으로 구성되어 있다. 콤바인의 무인주행 실험결과 RMS 오차는 50 m 직선주행에서 7.52 cm, 20 m 직선주행 후 1 m 오프셋 된 30 m의 직선주행에서 21.85 cm, 20 m 직선주행 후 90$^{\circ}$선회하여 25 m 직선주행에서 7.55 cm, 반지름 23 m의 원주 사분면 곡선주행에서는 25.98 cm로 각각 나타났다. 소 구획의 포장에서 벼는 가로 방향으로 25~30 cm, 세로 방향으로 15~20 cm의 간격으로 심어져 있다. DGPS 신호에 의한 위치 결정을 할 때 자체 오차 10 cm를 고려하여도 콤바인이 직선구간 및 선회구간을 주행하며 수확작업이 가능함을 알 수 있었다. 그러나 곡선구간에서는 최대오차가 65.5 cm로 매우 크게 나타나, 콤바인을 무인 자율주행으로 수확하기에는 어려움이 있는 것으로 나타났다. 실제 포장은 이론적인 완전한 직선보다는 작은 굴곡이 있는 곡선의 형태가 이루어져 있으므로 주행 오차를 감소하기 위해서는 기계시각을 이용하면 보다 정밀한 조향을 이룰 수 있을 것으로 예상된다. 포장에서 DGPS 신호, 자이로 센서 등을 이용한 콤바인의 무인주행 장치는 무인 수확작업을 위한 가능성을 보여주었고, 일부의 센서의 기능을 개선하면 만족한 성능을 나타낼 수 있을 것으로 판단된다.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.21-32
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• 2007

The linear traffic model(Vertical queueing model) that is adopted widely in traffic flow estimation assumes that all vehicles have the identical motion before joining a queue at the stop-line. Thus, a queue is supposed to form vertically not horizontally. Due to the simplicity of this model, the departure time of the leading vehicle is assumed to coincide with the start of effective green time. Thus, the delay estimates given by the Vertical queueing model is not always realistic. This paper explores a microscopic traffic model(a Kinematic Car-following model at Signalised intersections: a KCS traffic model) based on the one dimensional Kinematic equations in physics. A comparative evaluation in delay and sensitivity of delay difference between the KCS traffic model and the previously known Vertical queueing model is presented. The results show that the delay estimate in the Vertical queueing model is always greater than or equal to the KCS traffic model; however, the sensitivity of delay in the KCS traffic model is greater than the Vertical queueing model.

• Journal of Korean Society of Transportation
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• v.24 no.5 s.91
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• pp.123-133
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• 2006

Seoul and many large cities in Korea have implemented Median Exclusive Bus Lane(MEB). But exclusive bus lane in the middle of the road caused new contradictions between left turn movement and through bus movement and several signal operation techniques like 'left turn Protected' and 'overlap phase' couldn't be applied in intersections on MEB. We suggest 'Bus-only Signal for median lane technique as solution of these problems This study presents optimum signal time design process and detailed algorithms for intersections where bus-only signals are installed. As a test field. we took Yang-Je intersection where Median Exclusive Bus Lane go through. and have large gap in volume of left turn in main direction. And we verified that revised optimum signal time including overlap phase can reduce average delay time of vehicle through before and after simulation.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.5
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• pp.45-58
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• 2021

It is generally known that a two-lane roundabout has some problems in safety such as increasing conflicts, typically merging and diverging conflicts and conflicts between entering traffic and exiting as well as turning traffic. To solve these problems, a turbo-roundabout had been developed and has successfully brought safer and more efficient operation in other countries. In this study, micro simulations using VISSIM were conducted to investigate the maximum value of service traffic volume. It was found that operation of turbo-roundabouts was influenced by traffic volume for each turning traffic, and the maximum values of traffic volume were values between 2,400 and 2,800 vehicles per hour as rates of traffic volume for each turning traffic. Typically, turbo-roundabouts have limited to operate in conditions with more than 30% for left-turning traffic volume.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.91-97
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• 2018

This paper presents implementation possibilities of digital IoT doorlock systems via VLC(Visible Light Communication)'s color grid. The color grid-based VLC modulation scheme which are discussed in this paper utilize the straightness of light and abundant frequency resources which are the properties of the light. Performance results in this paper are compared to that of conventional modulations with Bit Error Rate (BER) and Signal to Noise Ratio (SNR) simulations. With respect to a channel model, the proposed modulation schemes select the nearest Line Of Sight (LOS) except Non Line Of Sight (NLOS). Experiments in this paper show error rates of received symbols by changing power dB at a distance of 3m between Tx and Rx in an indoor environment. Through performance results and experiments, this paper demonstrates superiority of the proposed color grid-based modulation schemes.

• Journal of Advanced Navigation Technology
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• v.23 no.3
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• pp.245-250
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• 2019

Inertial navigation system has navigation errors because of the error of inertial measurement unit (IMU) and misalignment over time. In order to solve this problem, aided navigation system is performed using global navigation satellite system (GNSS), speedometer, etc. The inertial navigation system equipped with underwater vehicle mainly uses speedometer and performed aided navigation because satellite signals do not pass through underwater. There are DVL, EM-Log, and RPM in the speedometer, and the sensors are applied according to the system environment. This paper describes velocity aided navigation using RPM of inertial navigation system operating in high speed and deep water environment. In addition, we proposes an algorithm to compensate the limit of RPM with straight direction and the current velocity error. There are results of monte-calo simulation to prove performance of the proposed algorithm.

• Journal of Advanced Navigation Technology
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• v.23 no.1
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• pp.90-96
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• 2019

LPWA is a cost-effective and time-saving technology with wide coverage. However, the LPWA is an ISM band that uses UHF radio waves, and its performance is very poor indoors because of its strong linearity. But, because of the possibility of achieving high performance compared to other communication in the room, this paper has studied the indoor communication performance by applying LoRa in LPWA technologies. After installing the data receiving module on the 4th floor, the transmission module was placed at the end of the building from the same floor to the 1st floor, and the data was collected. As a results, it installed on the 1st floor can be collected data with 98 ~ 99% probability, and the lowest RSSI is about -116dBm. Thus, considering the specification of LoRa with a maximum reception sensitivity -136dBm when the spreading factor is 12, the application of LPWA in the industrial field can be fully considered.