• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.10
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• pp.1173-1182
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• 1988

The stability, energetic efficiency and walking volume are affected by the geometric structure of legs of a walking robot. A quadruped walking robot is considered to have large stability margin among the walking robots and pantograph leg permits large walk stroke and mutually independent vertical and horizontal movements, but the kinematic characteristics are difficult to analyze. Graphical method may be useful to characterize three dimensional legged motion of the pantograph mechanism. We present the modelling method for three different quadruped robots with pantograph legs that have different joints mechanism. The modeled robots are animated by a path that is planned with respect to the center of body. In particular, graphical animation incorporates leg control to rotation and side walking and uses the window of Sun-3 system for displaying joint information.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.3
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• pp.46-52
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• 2018

A simple Crocco's $n-{\tau}$ time delay model and linear analysis of fluid flow coupled with acoustics are combined to investigate the high frequency combustion instability in the combustion chamber of LOX/hydrocarbon engines. The partial differential equation of the velocity potential is separated into ordinary differential equations, and eigenvalues that correspond to tangential resonance modes in the cylindrical chamber are determined. A general solution is obtained by solving the differential equation in the axial direction, and boundary conditions at the injector face and nozzle entrance are applied in order to calculate the chamber admittance. Frequency analysis of the transfer function is used to evaluate the stability of system. Stability margin is determined from the system gain and phase angle for the desired frequency range of 1T mode. The chamber model with variable baffle length and configurations are also considered in order to enhance the 1T mode stability of the combustion chamber.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.5
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• pp.9-16
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• 2004

The data link layer of the PCI Express must have the transmitting buffer that contains the packets to transmit next time. Also it must have the retry buffer that contains the packets which were already transmitted but have not been acknowledged by the corresponding target device. In the separated buffer architecture, the data link layer can not transmit the packets in the transmitting buffer if the reiry buffer space is not enough. In this paper, we propose an efficient buffer architecture which merges the transmitting buffer and the retry buffer to a single buffer. Since the proposed buffer can dynamically assign the size of the transmitting buffer and the retry buffer, it can improve the buffer usage efficiency and the data transfer efficiency. The simulation result shows that the proposed buffer has the higher data transfer efficiency than the separated buffer architecture about 39% when the total buffer size is 8K byte.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.3
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• pp.527-534
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• 2023

Triple modular redundancy (TMR) systems can continue their mission by virtue of their structural redundancy even if one processor is attacked by faults. In this paper, we propose a new fault tolerance strategy by introducing checkpoints into the TMR system in which data saving and fault detection processes are separated while they corporate together in the conventional checkpoints. Faults in one processor are tolerated by synchronizing the state of three processors upon detecting faults. Simultaneous faults occurring to more than one processor are tolerated by re-executing the task from the latest checkpoint. We propose the checkpoint placement and fault detection strategy to maximize the probability of successful execution of a task within the given deadline. We develop the Markov chain model for the TMR system having the proposed checkpoint strategy, and derive the optimal fault detection and checkpoint interval.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.622-628
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• 2016

As the suction pad-supporting bike carrier attached to a car may be subject to an excessive dynamic load due to random vibrations and centrifugal forces during driving, its structural safety is of great concern. To examine this, the finite-element method with a fluid-structure interaction should be used because the pressure on the pad bottom is changed in real time according to the fluctuations of the force or the moment applied on the pad. This method, however, has high computing costs in terms of modeling efforts and software expense. Moreover, the accuracy of computation is not easily guaranteed. Therefore, a new method combining the experiment and computation is proposed in this paper: the bottom pressure and contact area of the pad under varying loads was measured in real time and the acquired data are then used in the nonlinear elastic finite-element calculations. The computational and experimental results obtained with the product under development showed that the safety margin of the pad under the axial loading is relatively sufficient, whereas with an excessive rotational loading, the pad is vulnerable to separation or a local surface damage; hence, the safety margin may not be secured. The predicted contact behavior under the variation of the magnitude and type of the loading were in good agreement with the one from the experiment. The proposed analysis method in this study could be used in the design of similar vacuum pad systems.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1070-1074
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• 2014

According to IEEE 1662(2009), IPS is a power system where all prime movers produce electrical power that is shared among propulsion, mission, and ship service loads. Discriminating attributes of integrated power systems are flexibility of movers' arrangements, mechanical decoupling between prime movers and propulsors, an increased level of energy conversion and transmission redundancy, and flexibility of redistributing available electrical power for future electronic weapons. IPS could have various steps of power that can be produced at optimal load of movers. In this study, an evaluation method for optimal arrangement of movers was investigated when an IPS warship is projected. The two factors are utilized for the quantitative analysis which are the weight of system as the fighting power and the fuel consumption per year as the economic feasibility. And also the ways for arrangement of system were studied according to existence of small diesel generator. The evaluation method that decides the optimization level is based on the DEA(Data Envelopment Analysis)

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.27-27
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• 2019

본 연구는 2019년 물관리기본법 시행과 함께 추진하는 유역물관리체제 수립과 운영에 대해 분석하고자 한다. 유역물관리는 기존의 행정체계 중심으로 추진된 물관리에서 드러난 비효율성을 극복하고 물순환에 기초하여 더욱 효율적이고 자연 친화적으로 운영하고자 하는 통합물관리의 기초이다. 유역물관리제도를 적절하게 수립하고 운영하기 위해서는 한국보다 앞서 유역물관리제도를 채택하고 운영해온 경험을 면밀하게 검토하고 장단점을 학습하여 한국 현실에 맞게 응용하는 지혜가 필요하다. 따라서 본 연구는 유역물관리제도를 성공적으로 수립하고 운영해 온 영국(잉글랜드 및 웨일스)과 프랑스 사례를 검토하여 시사점을 도출하고자 한다. 영국(잉글랜드 및 웨일스)은 1973년 유역관리청을 10개 대유역에 설치하여 유역물관리체제를 수립하고 운영하였지만 1970년대 및 1980년대 경제난을 겪으면서 관련 투자가 줄어들고 하천의 수질 악화가 지속하였으며 유역관리청과 지방정부와의 긴밀한 협조 부재로 관리의 어려움이 증가하였다. 결국, 1989년 10개의 유역관리청을 상하수도 서비스회사로 전환하고 물서비스감시청, 음용수감시국, 환경청 등의 규제기관을 수립하여 규제와 서비스를 분리한 독특한 유역물관리체제를 수립하였다. 영국의 유역물관리체제는 2000년 유럽연합물관리지침의 도입으로 10개 유역을 11개의 유역으로 재편하고 국가소통위원회, 유역소통위원회 14개, 유역파트너쉽 100개 등의 기구를 설치하여 유역거버넌스를 강화하였다. 프랑스는 1964년 새로운 물법 도입을 통해 전국을 6개 대유역으로 나누고 각 유역에 유역관리청과 유역위원회를 설치하여 본격적인 유역물관리제도를 수립하였다. 초기에는 유역관리 조직과 지방정부 간의 알력이 상당하여 수도요금에 자동부과되는 약 19%에 달하는 물세에 대한 거부감이 상당하였다. 그런데 이러한 물세가 유역관리청의 관리로 물관리 사업을 위한 펀드로 조성되고 물관리 사업 시행 시 대규모 자금을 조달할 수 있다는 실효성이 입증되면서 점차 유역관리제도가 정착할 수 있게 되었다. 프랑스는 2000년 유럽연합물관리지침의 도입으로 기존의 6개 대유역으로 관리하던 것을 13개 유역으로 재편성하였고 유역감독관 제도를 신설하여 중앙의 감독을 강화하였으며 유역관리청과 유역위원회는 더욱 강화된 거버넌스를 기반으로 효율적인 물관리를 시행하고 있다. 영국과 프랑스 사례는 한국의 유역물관리제도 수립과 운영을 위해 다음과 같은 시사점을 준다. 첫째, 2019년 시행을 앞둔 유역물관리위원회의 구성, 운영 및 역할 등에 대해서는 큰 범위에서 합의를 이뤄야 하겠지만 안정적인 운영과 사업 시행을 위해서는 긴 시간이 필요하다는 점이다. 따라서 인내심과 여유를 갖고 임하되 필요한 원칙은 면밀한 검토와 합의를 통해 세워야 할 것이다. 둘째, 거버넌스의 중요성이다. 영국 사례와 같이 이해당사자 간의 대화와 타협은 중앙정부가 주도하는 것이 아닌 유역, 지방, 도시 등에서의 이해당사자들이 함께 이룩해야 한다. 셋째, 유역관리조직을 위한 건전한 재정확보이다. 프랑스의 예와 같이 유역물관리 조직의 독립성은 재정적 독립이 근본이 되어야 하고 이것은 독립재정을 확보하여 중앙 혹은 기타 유역/지방 조직의 간섭을 피해야 한다.

• 한국해양학회지
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• v.30 no.3
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• pp.184-196
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• 1995

The line-SW is located in the mouth of Gomso Bay (20 Km long and 5-8 Km wide),west coast of Korea. This area is composed of sand flat, mud flat, sand shoal and chenier, The difference of physical, geological and geomorphic conditions in subenvironments of the bay may control and produce distingtive foraminiferal populations and assemblages. This study investigates whether five a priori subenvironments (five local zonations) in Gomso-Bay tidal flat can be distinguished from each other on the basis of total (living plus dead) foraminiferal assemblages. Seventy-four species (67 benthic; 7 planktonic) were recorded in total assemblages of surface sediments from 10 stations. Ammonia beccarii tepida, Discorbis candeiana, Elphidium etigoense and Eponides nipponicus were most dominant species in living and total assemblages. The relative abundance (%) of living population was high at upper flat and decreased from upper to lower flat. The low percentages of living populations in middle to lower flat are probably influenced by the decreasing reproduction of foraminifera caused by high energy condition and addition of dead species from offshore. The occurence of planktonic foraminifera in middle to lower flat (5.3∼6.6%) indicates introduction of planktonic foraminifera from offshore by storm and/or tidal current. The relatively high numbers of species in lower middle to lower flat are probably caused by a mixing of faunas from these areas and offshore. The high numbers of total individuals per 50 ml of sediment in upper flat indicate that this area is a relatively stable environment where waves and currents are protected by the chenier. Five biofacies of the total foraminiferal assemblages were established on the basis of dominant species (those representing more than 20% of the total assemblages in any station) in the five a priori subenvironments recognized along the Line-SW transect in Gomso-Bay tidal flat. Five biofacies are potentially useful in paleoenvironmental interpretation in late Quaternary Gomso-Bay tidal deposits.

• The KIPS Transactions:PartC
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• v.13C no.1 s.104
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• pp.83-94
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• 2006

This paper describes ATM cell encipherment method using Rijndael Algorithm adopted as an AES(Advanced Encryption Standard) by NIST in 2001. ISO 9160 describes the requirement of physical layer data processing in encryption/decryption. For the description of ATM cell encipherment method, we implemented ATM data encipherment equipment which satisfies the requirements of ISO 9160, and verified the encipherment/decipherment processing at ATM STM-1 rate(155.52Mbps). The DES algorithm can process data in the block size of 64 bits and its key length is 64 bits, but the Rijndael algorithm can process data in the block size of 128 bits and the key length of 128, 192, or 256 bits selectively. So it is more flexible in high bit rate data processing and stronger in encription strength than DES. For tile real time encryption of high bit rate data stream. Rijndael algorithm was implemented in FPGA in this experiment. The boundary of serial UNI cell was detected by the CRC method, and in the case of user data cell the payload of 48 octets (384 bits) is converted in parallel and transferred to 3 Rijndael encipherment module in the block size of 128 bits individually. After completion of encryption, the header stored in buffer is attached to the enciphered payload and retransmitted in the format of cell. At the receiving end, the boundary of ceil is detected by the CRC method and the payload type is decided. n the payload type is the user data cell, the payload of the cell is transferred to the 3-Rijndael decryption module in the block sire of 128 bits for decryption of data. And in the case of maintenance cell, the payload is extracted without decryption processing.