• Progress in Superconductivity
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• 제13권2호
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• pp.105-110
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• 2011

SQUID sensor-based ultra low-field magnetic resonance apparatus with ${\mu}T$-level measurement field requires a strong prepolarization magnetic field ($B_p$) to magnetize its sample and obtain magnetic resonance signal with a high signal-to-noise ratio. This $B_p$ needs to be ramped down very quickly so that it does not interfere with signal acquisition which must take place before the sample magnetization relaxes off. A MOSFET switch-based $B_p$ coil driver has current ramp-down time ($t_{rd}$) that increases with $B_p$ current, which makes it unsuitable for driving high-field $B_p$ coil made of superconducting material. An energy cycling-type current driver has been developed for such a coil. This driver contains a storage capacitor inside a switch in IGBT-diode bridge configuration, which can manipulate how the capacitor is connected between the $B_p$ coil and its current source. The implemented circuit with 1.2 kV-tolerant devices was capable of driving 32 A current into a thick copper-wire solenoid $B_p$ coil with a 182 mm inner diameter, 0.23 H inductance, and 5.4 mT/A magnetic field-to-current ratio. The measured trd was 7.6 ms with a 160 ${\mu}F$ storage capacitor. trd was dependent only on the inductance of the coil and the capacitance of the driver capacitor. This driver is scalable to significantly higher current of superconducting $B_p$ coils without the $t_{rd}$ becoming unacceptably long with higher $B_p$ current.

• 대한전자공학회논문지SD
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• 제41권6호
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• pp.33-41
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• 2004

본 논문에서는, 편광측정법에 의한 광섬유 전류 센서(P-FOCS)를 실험·제작하여, 실제 필드에 적용할 수 있는 P-FOCS의 상용화 가능성에 대하여 연구하였다. P-FOCS는 인가된 전류에 의해 발생한 자기장에 비례하는 Faraday 회전각을 측정함으로서 인가된 전류를 측정한다. P-FOCS의 센싱 광섬유로는 저복굴절 광섬유를 사용하여 밴딩에 의한 선복굴절의 영향을 최소화하였으며, 벌크(bulk)한 광학소자의 사용으로 인한 광 손실을 막기 위해 전 광섬유 소자를 사용하였다. 또한, 구성된 신호처리회로는 광섬유 소자들의 연결부에서의 손실로 인한 출력 신호의 강도 변화를 제거하기 위해 사용된다. Faraday 회전각은, 632.8nm 파장의 광원을 이용하여 권선수가 약 1500인 솔레노이드에 전류를 인가해 7500A의 전류원의 효과를 얻도록 하여, 솔레노이드 내부에 센싱 광섬유를 통과시켜 측정하였다. $1000A{\sim}7500A$ 범위에서, 선형성의 측정 오차는 약 1.5% 이내였다.

• 한국식품과학회지
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• 제25권4호
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• pp.391-394
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• 1993

탁주발효의 자동화를 위하여 발효 중 발생하는 기체를 측정할 수 있는 bubble counter와 제어장치를 개발하였다. 동 장치를 활용하여 pilot 규모의 탁주발효에 적용하였다. 탁주발효중 발생하는 기체를 계측하는 bubble counter는 photo-interruptor와 acryl관으로 구성하였으며, 계측되는 기체용적은 기포당 0.018ml였다. 그리고 탁주발효의 제어장치는 single chip microcomputer(MC68705R3)로 제작하였으며, 발효액의 온도를 측정, 제어하기 위하여 온도계측회로를 제작하였고, 냉각수 순환을 결정하는 solenoid valve의 작동으로 온도제어를 하였다. 동 장치를 운영하기 위하여 software를 작성하여 ROM에 구조화하였다. 동 장치로 $CO_2$ 발생량과 속도를 자동적으로 추정한 결과 알코올 농도곡선과 형태가 서로 유사함을 보여주었으며, $30^{\circ}C$ 발효조건에서 24시간때에 최대 발생량을 보였다. 알코올농도와 $CO_2$ 발생량은 뛰어난 상관관계를 보였으며, 이로부터 제어알고리듬을 작성할 수 있었다.

• 디지털콘텐츠학회 논문지
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• 제16권3호
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• pp.483-492
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• 2015

최근에 비만을 치료하기 위한 요법 중에 카복시테라피 치료법이 있다. 이 방법은 지방이 과도하게 축적된 부위에 이산화탄소($CO_2$)를 주입하여 치료하는 방법으로 최근 각광받고 있다. 가스통에 담겨 있는 이산화탄소를 피부에 주입하려면 주입기가 필요하며, 건강을 위해 주입량을 정확히 조절할 수 있어야 한다. 본 논문에서는 국내에서 제작한 CARBO 3000이라는 이산화탄소 주입기의 유량주입 방법을 분석하고 단점을 파악한다. 유량 센서와 일정 유량이 출력되게 고정된 유속 조절기를 추가하여 주입된 정확한 유량을 보여줄 수 있는 모듈을 구현한다. 구현을 위해 하드웨어적으로는 CPU와 LCD, 유속 조절기를 선정하였으며 솔레노이드 밸브와 유량센서를 선정하고 구동을 시킬 수 있는 회로를 설계한다. 소프트웨어적으로는 주입된 이산화탄소의 양을 판별할 수 있는 GUI를 설계하고 유량을 제어할 수 있는 유량 제어 알고리즘을 설계한다.

• Smart Structures and Systems
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• 제7권5호
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• pp.379-392
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• 2011

This paper presents a multi-functional system, consisting of a magnetorheological (MR) damper and an electromagnetic induction (EMI) device, and its applications in stay cables. The proposed system is capable of offering multiple functions: (1) mitigating excessive vibrations of cables, (2) estimating cable tension, and (3) harvesting energy for wireless sensors used health monitoring of cable-stayed bridges. In the proposed system, the EMI device, consisting of permanent magnets and a solenoid coil, can converts vibration energy into electrical energy (i.e., induced emf); hence, it acts as an energy harvesting system. Moreover, the cable tension can be estimated by using the emf signals obtained from the EMI device. In addition, the MR damper, whose damping property is controlled by the harvested energy from the EMI device, can effectively reduce excessive cable vibrations. In this study, the multi-functionality of the proposed system is experimentally evaluated by conducting a shaking table test as well as a full-scale stay cable in a laboratory setting. In the shaking table experiment, the energy harvesting capability of the EMI device for wireless sensor nodes is investigated. The performance on the cable tension estimation and the vibration mitigation are evaluated using the full-scale cable test setup. The test results show that the proposed system can sufficiently generate and store the electricity for operating a wireless sensor node twice per day, significantly alleviate vibration of a stay cable (by providing about 20% larger damping compared to the passive optimal case), and estimate the cable tension accurately within a 2.5% error.

• 대한기계학회논문집A
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• 제22권3호
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• pp.663-670
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• 1998

Most of feedback shift controllers developed in the past have fixed control parameters tuned by experts using a trial and error method. Therefore, those controllers cannot satisfy the best control performance under various driving conditions. To improve the shift quality under various driving conditions, a new self-organizing controller(SOC) that has an optimal control performance through self-learning of driving conditions and driver's pattern is designed in this study. The proposed SOC algorithm for the shift controller uses simple descent method and has less calculation time than complex fuzzy relation, thus makes real-time control passible. PCSV (Pressure Control Solenoid Valve) control current is used as a control input, and turbine speed of the torque converter is used indirectly to monitor the transient torque as a feedback signal, which is more convenient to use and economic than the torque signal measured directoly by a torque sensor. The results of computer simulations show that an apparent reduction of shift-transient torque is obtained through the process of each run without initial fuzzy rules and a good control performance in the shift-transient torque is also obtained.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.231-234
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• 2001

OBD-II regulations are already effective in many countries. The California Air Resources Board(CARB) first issued regulations in 1985 for the 1988 model year, known as OBD-I, and required the vehicle's engine management computer to warn the driver by means of a dash-mounted light if a malfunction occurred in either the oxygen sensor, the exhaust gas recirculation(EGR) valve or the evaporative emission system purge solenoid, and to store information on troubles that have no recurrent characteristics. This paper presents two methods of wireless monitoring OBD signal, which is one of the ECU output for self diagnostic measurement. RF module is used to monitor ECU's Self diagnostic signal remotely. Two kinds of measurement systems which are based on micro-controller(80C196KC) for portable detection and PC for sever are considered for receiving the RF signal. Therefore, possibility of real-time monitoring of ECU's self diagnostic signal remotely is verified on this paper.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권4호
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• pp.159-164
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• 2002

This paper presents the design and fabrication of a high-Tc superconducting (HTS) power supply for charging of the HTS magnet load, and its characteristics have been analyzed through experiments. HTS power supply consists of two heaters, an electromagnet, a Bi-2223 solenoid and a Bi-2223 pancake magnet load. In this experiment, 331 mH electromagnet and 0.8 A dc heater current were used, and 8.5 sec and 17 sec were used for pumping period. Mechanism of the superconducting switch is used for heater-trigger. In order to measure the pumping-current with respect to the magnet flux changes, hall sensor was installed at the center of the Bi-2223 pancake load. The experimental observations have been compared with the theoretical predictions. In this experiment, the pumping-current has reached about 1.2 A. In computer simulation, the maximum pumping-current of the system has been predicted to be about 2.7 A.

• 한국실천공학교육학회논문지
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• 제4권2호
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• pp.7-12
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• 2012

본 연구에서는 실제의 자동 폐수 정화시스템을 교육용으로 설계한다. 이 시스템은 필터조, 폭기조, 반응조 및 자외선 살균조 등 전체 4개의 부분으로 구성하고, PLC, DC모터, 솔레노이드 밸브, 분사기, 프로펠러, 프로파일, 스위치, 센서 등을 사용하여 구현한다. 또한 이 시스템은 대학 교육으로부터 습득한 전공 지식을 토대로 설계 및 제작되어진다. 폐수처리 시설을 간단하게나마 실제로 구현해 봄으로써 학생들은 창의력과 적응성을 키울 수 있을 뿐만 아니라, 이 연구를 통하여 습득한 기술들이 필요 시에 관련 산업에 적용되어 질 수 있다.

• 한국자동차공학회논문집
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• 제22권4호
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• pp.89-97
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• 2014

As the digital control technologies in automotive industry have advanced, electronic control units(ECUs) play a key-role to improve system performance. Transmission control unit(TCU) is a shifting controller for automatic transmission of which major functions are to determine the shift and manage the shifting process considering the various sensor signal on transmission and driver's commands. As with any ECU in vehicle, TCU performs complex algorithms such as shift control, diagnostic and failsafe functions. However, firmware design analysis is hardly possible by the reverse engineering due to code protection. Transmission simulator is a hardware-in-the-loop simulator which enables TCU to work in normal mode by simulating the electrical signal of TCU interface. In this research, diagnosis and failsafe algorithm implemented on commercialized TCU is analyzed by using the transmission simulator that is developed for wheel loader construction vehicle. This paper gives various experimental results on the proportional solenoid current trajectories for different operating modes, error detection criterion and limphome mode gears for all the possible cases of clutch malfunction. The derived results for conventional TCU can be applied to the development of inherent TCU algorithms and the transmission simulator can also be utilized for the test of TCU to be developed.