• 센서학회지
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• 제11권1호
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• pp.39-47
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• 2002

광 저장장치는 디스크 트랙에 레이저빔을 위치시켜 정보를 저장한다. 정보의 용량이 증대되면서 좀더 높은 저장 밀도를 요구하게 되었고, 그만큼 정밀한 레이저빔의 위치제어가 필요하게 되었다. 본 논문에서는 광 저장장치용 정전형 마이크로 미러를 MEMS기술을 이용해 제조하고 그 특성을 조사하였다. 마이크로 미러는 벌크 마이크로머시닝 기술에 의하여 제조되었으며, 특히 접합공정이 이루어지고 난 후에 연마공정에 의해서 실리콘 웨이퍼의 두께 및 미러면의 형태를 형성하는 공정을 적용함으로서 제현성을 높였다. 제작된 미러의 크기는 $3.0mm{\times}2.5mm$ 이고, 35V에서 변위는 $3.2{\mu}m$ 였다.

• 한국산학기술학회논문지
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• 제15권8호
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• pp.5227-5232
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• 2014

소프트웨어 제품 위험을 초기단계에서 제거함으로써 품질이 높은 소프트웨어를 개발 할 수 있다. 이를 위해 위험을 효과적으로 분석하고 관리하는 위험 분석 시스템의 도입이 필요하다. 제품 위험 분석 및 도구의 관심이 확대 되고 있으나 기존의 위험 관련 도구는 위험 추적 수준으로 개발되었으며 분석 및 전략 수립은 지원하지 않아 조직에서 제품 위험 관리에 많은 어려움을 격고 있다. 이에 본 논문에서는 조직에서 소프트웨어 개발과정에서 야기 될 수 있는 제품 위험의 문제점을 초기단계에서 해결하고 축적된 품질 위험 데이터를 통하여 정형화할 수 있는 소프트웨어 위험 분석 시스템을 제안하였다. 또한 어떤 제품 위험을 분석하고 관리해야 하는지에 대한 가이드라인을 제공하고자 한다. 위험 분석 협의과정을 통하여 도출된 위험 아이템에 대하여 위험 분석정보와 전략 등을 제공하는 위험 분석 시스템을 구현하고 활용방안을 제시하였다.

• Journal of Welding and Joining
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• 제34권2호
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• pp.59-66
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• 2016

The Gas Metal Arc(GMA) welding, called Metal Inert Gas(MIG) welding, has been an important component in manufacturing industries. A key technology for robotic welding processes is seam tracking system, which is critical to improve the welding quality and welding capacities. The objectives of this study were to develop the intelligent and cost-effective algorithms for image processing in GMA welding which based on the laser vision sensor. Welding images were captured from the CCD camera and then processed by the proposed algorithm to track the weld joint location. The proposed algorithms that commonly used at the present stage were verified and compared to obtain the optimal one for each step in image processing. Finally, validity of the proposed algorithms was examined by using weld seam images obtained with different welding environments for image processing. The results proved that the proposed algorithm was quite excellent in getting rid of the variable noises to extract the feature points and centerline for seam tracking in GMA welding and could be employed for general industrial application.

• JSTS:Journal of Semiconductor Technology and Science
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• 제11권2호
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• pp.95-103
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• 2011

This paper proposes a 6b 1.2 GS/s 47.8 mW 0.17 $mm^2$ 65 nm CMOS ADC for high-rate wireless personal area network systems. The proposed ADC employs a source follower-free flash architecture with a wide input range of 1.0 $V_{p-p}$ at a 1.2 V supply voltage to minimize power consumption and high comparator offset effects in a nanometer CMOS technology. The track-and-hold circuits without source followers, the differential difference amplifiers with active loads in pre-amps, and the output averaging layout scheme properly handle a wide-range input signal with low distortion. The interpolation scheme halves the required number of pre-amps while three-stage cascaded latches implement a skew-free GS/s operation. The two-step bubble correction logic removes a maximum of three consecutive bubble code errors. The prototype ADC in a 65 nm CMOS demonstrates a measured DNL and INL within 0.77 LSB and 0.98 LSB, respectively. The ADC shows a maximum SNDR of 33.2 dB and a maximum SFDR of 44.7 dB at 1.2 GS/s. The ADC with an active die area of 0.17 $mm^2$ consumes 47.8 mW at 1.2 V and 1.2 GS/s.

• 한국자기학회지
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• 제14권6호
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• pp.207-212
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• 2004

전자기학의 분야에서 와전류를 이용한 응용 분야는 매우 다양하다. 예를 들면, 핵을 이용한 원자력 발전소의 증기 발생 튜브 또는 비행기의 엔진이나 날개 부분의 결함 등을 자기적 특성을 이용하여 비파괴 검사를 하는 등의 일이다. 와전류의 특성을 결정짓는 가장 중요한 인자 중 하나가 바로 센서 측정 거리 (lift-off)인데 이것은 와전류를 측정한 센서와 피검사 물체간의 물리적인 공간거리를 뜻한다. 이 인자는 와전류 신호의 특성을 정확하게 분석해내는데 매우 중요함에도 불구하고 실제 필드에서는 모든 경우마다 그 정확한 값을 측정해내기가 힘들 뿐더러 일정한 거리를 상시 유지 하기도 어렵다. 따라서 자기적 신호의 하나인 와전류로 하여금 다양한 상황에서의 lift-off로 변화에도 영향을 받지 않고 일정한 특성을 유지하게끔 해주는 기술이 필요하다. 이 논문은 다양한 lift-off로부터 얻어진 와전류를 보상하여 일정한 성질을 유지하도록 하는 기법을 설명하고 있다. 다양한 lift-off로 부터 얻어진 와전류들은 신호 획득 거리가 0인 이상적 상태의 신호들로 보상 변환 되어 다음 단계인 피검사 시료상의 결함 또는 흠집의 물성이나 특성 파악에 계속해서 쓰이게 된다.

• Journal of Information Processing Systems
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• 제8권3호
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• pp.409-420
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• 2012

The decision-making by agents in games is commonly based on reinforcement learning. To improve the quality of agents, it is necessary to solve the problems of the time and state space that are required for learning. Such problems can be solved by Macro-Actions, which are defined and executed by a sequence of primitive actions. In this line of research, the learning time is reduced by cutting down the number of policy decisions by agents. Macro-Actions were originally defined as combinations of the same primitive actions. Based on studies that showed the generation of Macro-Actions by learning, Macro-Actions are now thought to consist of diverse kinds of primitive actions. However an enormous amount of learning time and state space are required to generate Macro-Actions. To resolve these issues, we can apply insights from studies on the learning of tasks through Programming by Demonstration (PbD) to generate Macro-Actions that reduce the learning time and state space. In this paper, we propose a method to define and execute Macro-Actions. Macro-Actions are learned from a human subject via PbD and a policy is learned by reinforcement learning. In an experiment, the proposed method was applied to a car simulation to verify the scalability of the proposed method. Data was collected from the driving control of a human subject, and then the Macro-Actions that are required for running a car were generated. Furthermore, the policy that is necessary for driving on a track was learned. The acquisition of Macro-Actions by PbD reduced the driving time by about 16% compared to the case in which Macro-Actions were directly defined by a human subject. In addition, the learning time was also reduced by a faster convergence of the optimum policies.

• 한국정보통신학회논문지
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• 제18권8호
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• pp.1811-1817
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• 2014

본 논문은 선도 로봇을 추종 로봇이 일정거리와 각도를 두고 추종하는 군집제어에서, 추종 로봇의 질량이 변할 경우, 신경회로망을 통해 보간된 이득을 갖는 PID제어기를 제안한다. 전체 제어시스템은 기구학 제어기와 동역학을 고려한 동적제어기로 구성하였다. 동적제어기는 가변 이득을 가지는 PID 제어기로 구성하여, 추종 로봇의 대표적 질량에 따라 적절한 PID 이득을 유전 알고리즘으로 구하였다. 유전 알고리즘으로 구한 데이터를 기초로 신경회로망을 학습하여 추종 로봇이 임의의 질량을 갖더라도 최적의 PID 이득을 선정할 수 있었다. 모의실험에서 추종 로봇의 질량이 임의의 값으로 변화하는 경우, 신경회로망을 통해 보간된 이득을 갖는 PID 제어기가 고정된 이득을 가지는 PID 제어기에 비해 군집제어에서 추종 성능을 향상시키는 것을 확인하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1933-1942
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• 2008

Over the years, the Social Republic of Vietnam has demonstrated its high annual growth rate over 8%. In order to secure its sustainable economic growth, its has also demonstrated its sharp concerns on building up core infrastructures by luring foreign investments on a large scale, which would underpin the nation's economic propulsion. Among others, transport infrastructures and networks centering on railway systems are obviously seen as the most urgent to be built to continue its growth. Seoul Metro recently took a significant step forward in Vietnam to launch railway business by executing its export project of 6 units of metro cars to Hanoi as on July 10, 2008. Those 6 cars are scheduled to be put on the tracks linking Yen Bian, Hanoi with Ha Long, for demonstrative running, around October, 2008, carrying tourists on that 163kms of the National Railway line serving the region. A successful running on the track will duly entail further export of additional 54 units of Seoul Metro cars to Vietnam. In this thesis, description will be noted on the reuse and economic value of the Seoul Metro's de-commissioned metro cars, reflecting on the current urban railway law at home regulating the service life of rolling stocks domestically. This thesis will also study the points at issue, and the recommendable future orientation of the Vietnam railway business project.

• 한국산업융합학회 논문집
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• 제21권6호
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• pp.265-271
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• 2018

DC-DC buck converter is a critical building block in the power management integrated circuit (PMIC) architecture for the portable devices such as cellular phone, personal digital assistance (PDA) because of its power efficiency over a wide range of conversion ratio. To ensure a safe operation, avoid unexpected damages and enhance the reliability of the converter, fully-integrated protection circuits such as over voltage protection (OVP), under voltage lock out (UVLO), startup, and thermal shutdown (TSD) blocks are designed. In this paper, these three fully-integrated protection circuit blocks are proposed for use in the DC-DC buck converter. The buck converter with proposed protection blocks is operated with a switching frequency of 1 MHz in continuous conduction mode (CCM). In order to verify the proposed scheme, the buck converter has been designed using a 180 nm CMOS technology. The UVLO circuit is designed to track the input voltage and turns on/off the buck converter when the input voltage is higher/lower than 2.6 V, respectively. The OVP circuit blocks the buck converter's operation when the input voltage is over 3.3 V, thereby preventing the destruction of the devices inside the controller IC. The TSD circuit shuts down the converter's operation when the temperature is over $85^{\circ}C$. In order to verify the proposed scheme, these protection circuits were firstly verified through the simulation in SPICE. The proposed protection circuits were then fabricated and the measured results showed a good matching with the simulation results.

• 로봇학회논문지
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• 제16권4호
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• pp.336-344
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• 2021

This paper presents a robust deep learning-based human tracking framework in crowded environments. For practical human tracking applications, a target must be robustly tracked even in undetected or overcrowded situations. The proposed framework consists of two parts: robust deep learning-based human detection and tracking while recognizing the aforementioned situations. In the former part, target candidates are detected using Detectron2, which is one of the powerful deep learning tools, and their weights are computed and assigned. Subsequently, a candidate with the highest weight is extracted and is utilized to track the target human using a Kalman filter. If the bounding boxes of the extracted candidate and another candidate are overlapped, it is regarded as a crowded situation. In this situation, the center information of the extracted candidate is compensated using the state estimated prior to the crowded situation. When candidates are not detected from Detectron2, it means that the target is completely occluded and the next state of the target is estimated using the Kalman prediction step only. In two experiments, people wearing the same color clothes and having a similar height roam around the given place by overlapping one another. The average error of the proposed framework was measured and compared with one of the conventional approaches. In the error result, the proposed framework showed its robustness in the crowded environments.