• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1921-1926
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• 2003

We build a local minimum free motion planning for mobile robots considering dynamic environments by simple sensor fusion assuming that there are unknown obstacles which can be detected only partially at a time by proximity sensors and can be cleaned up or moved slowly (dynamic environments). Potential field is used as a basic platform for the motion planning. To clear local minimum problem, the partial information on the obstacles should be memorized and integrated effectively. Sets of linked line segments (SLLS) are proposed as the integration method. Then robot's target point is replaced by virtual target considering the integrated sensing information. As for the main proximity sensors, we use laser slit emission and simple web camera since the system gives more continuous data information. Also, we use ultrasonic sensors as the auxiliary sensors for simple sensor fusion considering the advantages in that they give exact information about the presence of any obstacle within certain range. By using this sensor fusion, the dynamic environments can be dealt easily. The performance of our algorithm is validated via simulations and experiments.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.4
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• pp.951-959
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• 2017

Under the assumption that there is available some additional information other than plaintext-ciphertext pairs, the security of the RSA cryptosystem has been analyzed by the attack methods such as the side-channel attacks and the lattice-based attacks. Recently, based on the data retention property of the powered-off DRAMs, the so called cold boot attack was proposed in the literature, which is focusing on recovering the various cryptosystems' key from some auxiliary information. This paper is dealing with the problem of recovering the RSA private key with erasures and errors and proposes a new key recovery algorithm which is shown to have better performance than the previous one introduced by Kunihiro et al.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.4028-4049
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• 2014

Attribute-based encryption (ABE) is a promising cryptographic primitive for implementing fine-grained data sharing in cloud computing. However, before ABE can be widely deployed in practical cloud storage systems, a challenging issue with regard to attributes and user revocation has to be addressed. To our knowledge, most of the existing ABE schemes fail to support flexible and direct revocation owing to the burdensome update of attribute secret keys and all the ciphertexts. Aiming at tackling the challenge above, we formalize the notion of ciphertext-policy ABE supporting flexible and direct revocation (FDR-CP-ABE), and present a concrete construction. The proposed scheme supports direct attribute and user revocation. To achieve this goal, we introduce an auxiliary function to determine the ciphertexts involved in revocation events, and then only update these involved ciphertexts by adopting the technique of broadcast encryption. Furthermore, our construction is proven secure in the standard model. Theoretical analysis and experimental results indicate that FDR-CP-ABE outperforms the previous revocation-related methods.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.1
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• pp.63-69
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• 2013

In recent years, technology for storing a preliminary power or a surplus of photovoltaic energy is required. This technique, as well as store a preliminary energy and improve the reliability of the gird safety. This system can plan a efficient power generation through the flexibility of the power supply from the perspective of not only provider but also user. Accordingly, the realization of the smart grid can be expected. This paper proposes a hybrid PCS using a photovoltaic and a lithium-polymer battery with the characteristics of high density energy. The main energy source of a hybrid PCS is a photovoltaic, grid and the auxiliary energy source is a lithium-polymer battery. The operation of a proposed system in this paper is verified with simulation and experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.2
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• pp.112-119
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• 2021

This study proposes a design method of high-power-density and high-efficiency low-voltage DC-DC converters using SiC MOSFET and the optimized planar transformer design procedure based on the figure-of-merit. The secondary rectifying circuit of the phase-shifted full-bridge converter is compared to achieve high power density and high efficiency, and the phase-shifted full bridge converter with a current-doubler rectifier is selected. The planar transformer is designed by the proposed optimized design procedure and verified by FEA simulation. To validate the proposed design method, experimental results from a 3 kW prototype are provided. The prototype achieved 95.28% maximum efficiency and a power density of 2.98 kW/L.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.05a
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• pp.522-524
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• 2023

위치 기반 서비스(LBS)의 확산으로 다양한 분야에서 활용할 수 있는 많은 양의 경로 데이터가 생성되고 있다. 하지만 공격자가 경로 데이터를 통해 잠재적으로 사용자의 개인정보를 유추할 수 있다는 문제점이 존재한다. 따라서 경로 데이터의 프라이버시를 보존하며 유용성을 유지할 수 있는 GAN(Generative Adversarial Network)을 사용한 많은 연구가 진행되고 있다. 그러나 GAN은 생성된 결과물을 제어하지 못한다는 한계점을 가지고 있다. 본 논문에서는 ACGAN(Auxiliary classifier GAN)을 통해 생성된 결과물을 제어함으로써 경로 데이터의 민감한 정점을 숨기고, Attention mechanism을 결합하여 높은 유용성과 익명성을 제공하는 합성 경로 생성 모델인 TAP-GAN(Trajectory attention and protection-GAN)을 제안한다. 또한 모델의 성능을 입증하기 위해 유용성 및 익명성 실험을 진행하고, 선행 연구 모델과의 비교를 통해 TAP-GAN이 경로 데이터의 유용성을 보장하면서 사용자의 프라이버시를 효과적으로 보호할 수 있음을 확인하였다.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.628-632
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• 2003

An intelligent miniature humanoid robot system is designed and implemented as a platform for researching walking algorithm. The robot system consists of a mechanical robot body, a control system, a sensor system, and a human interface system. The robot has 6 dofs per leg, 3 dofs per arm, and 2 dofs for a neck, so it has total of 20 dofs to have dexterous motion capability. For the control system, a supervisory controller runs on a remote host computer to plan high level robot actions based on the vision sensor data, a main controller implemented with a DSP chip generates walking trajectories for the robot to perform the commanded action, and an auxiliary controller implemented with an FPGA chip controls 20 actuators. The robot has three types of sensors. A two-axis acceleration sensor and eight force sensing resistors for acquiring information on walking status of the robot, and a color CCD camera for acquiring information on the surroundings. As an example of an intelligent robot action, some experiments on playing soccer are performed.

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.3
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• pp.74-80
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• 2002

There are many researches on post-processing methods for the Korean continuous speech recognition enhancement using natural language processing techniques. It is very difficult to use a formal morphological analyzer for improving the speech recognition because the analysis technique of natural language processing is mainly for formal written languages. In this paper, we propose a speech recognition enhancement model using syntactic unit of morphemes. This approach uses the functional word level longest match which dose not consider spacing words. We describe the post-processing mechanism for the improving speech recognition by using proposed model which uses the relationship of phonological structure information between predicates md auxiliary predicates or bound nouns that are frequently occurred in Korean sentences.

• Journal of the Korea Society of Computer and Information
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• v.21 no.10
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• pp.143-148
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• 2016

Although various wearable devices applying information technologies are launched, only some of them are forming their own markets, and product which general consumers started to use in their daily life is believed to be smart watch. This study is intended to find factors why such smart watches are selected in terms of individual consumer's characteristics in smart watches whose market is under its early stage. Smart watches are not forming their markets yet and this product is rather closer to a device attached to smart phone. But they would form markets only if their value is approved by themselves. This study looked into a structure under which smart watch forms its preference in terms of individual consumer and consumers are willing to use it. This study has its meaning by looking into factors why smart watch is spreading in market in terms of individual consumer's characteristics. Results from this study are believed to provide fruitful implication to establish market strategy for wearable devices including smart watch that is not much used yet by consumers.

• Journal of Korean Library and Information Science Society
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• v.34 no.1
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• pp.239-260
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• 2003

The purpose of this study is to devise a classification scheme to arrange the agricultural information efficiently. In the first part it defines the agricultural science and studies the content and system of the agricultural science. It compares current KDC with DDC, UDC and NDC used to agriculture parts, and it studies AGRICOLA SCC. On the basis of it, this study is displayed the new classification for the agricultural science. The new classification scheme Is classified by the basic theories related to agriculture, agriculture of plants, animal agriculture, food products, and auxiliary disciplines in turn. The number of main divisions are set up 23 items.