• Steel and Composite Structures
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• 제17권5호
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• pp.573-599
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• 2014

A new type of connection for steel-concrete composite bridges was developed by the Steel Structures Laboratory of Ecole Poytechinque $F{\acute{e}}d{\acute{e}}rale$ de Lausanne. Resistance to longitudinal shear is based on the development of shear stresses in the confined interfaces which form the connection. Confinement is provided by the reinforced concrete slab which encloses the connection and restrains the uplift (lateral separation) of the interfaces by developing normal stresses. The experimental investigation of the interfaces, under static and cyclic loading, enabled the development of the laws describing the structural behaviour of each interface. Those laws were presented by the authors in previous papers. The current paper focuses on the continuity of the research. It presents the experimental investigation on the new connection by means of push-out tests on specimens submitted to static and cyclic shear loading. Investigation revealed that the damage in the connection, due to cyclic loading, is expressed by the accumulation of a residual slip. A safe fatigue failure criterion is proposed for the connection which enabled the verification of the connection for the fatigue limit state with respect to the limit of fatigue. A numerical model is developed which takes into account the laws describing the interface behaviour and the analytical expressions for the confinement effect, the latter obtained by performing finite element analysis. This numerical model predicts the shear resistance of the connection and enables to assess its fatigue limit which is necessary for the fatigue design proposed.

• Journal of Advanced Marine Engineering and Technology
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• 제36권7호
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• pp.935-941
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• 2012

This paper describes a study of conventional electrical rig and simulated application of Flywheel Energy Storage system on the power system of the offshore plants with dynamic positioning system with the following aims: improve fuel consumption on engines, prevent blackout and mitigate voltage sags due to pulsed load and fault. Fuel consumption has been analyzed for the generators of the typical drilling rigs compared with the power plant with Flywheel Storage Unit which has an important aid in avoiding power interruption during DP (Dynamic Positioning) operation. The FES (Fly wheel Energy storage System) releases energy very quickly and efficiently to ensure continuity of the power supply to essential consumers such as auxiliary machinery and thrusters upon main power failure. It will run until the standby diesel generator can start and supply the electric power to the facilities to keep the vessel in correct position under DP operation. The proposed backup method to utilize the quick and large energy storage Flywheel system can be optimized in any power system design on offshore plant.

• 한국컴퓨터정보학회논문지
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• 제18권2호
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• pp.59-68
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• 2013

LTE-Advanced 망에서 핸드오버가 발생하면 멀티미디어 트래픽의 전송이 지연 및 손실에 의하여 영향 받기 때문에, 일관된 QoS를 유지하기 위한 효율적인 자원 관리 방안이 필요하다. 본 논문은 핸드오버 시에 OFDMA 시스템에서 이종 트래픽의 QoS를 보장하기 위한 부하제어 기반의 자원 관리 방안을 제안한다. 이를 통하여 음성, 영상, 데이터 서비스 등 자원할당 요구 사항이 서로 다른 멀티미디어 서비스들의 서비스 연속성을 지원할 수 있다. 핸드오버 실패율과 패킷 손실률을 성능척도로 하여 수행된 시뮬레이션 결과에 의하면 제안된 방안은 기존 방안에 비하여 더 우수한 성능을 가짐이 확인된다.

• Structural Engineering and Mechanics
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• 제38권4호
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• pp.385-403
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• 2011

Continuous deep girders which transmit the gravity load from the upper wall to the lower columns have frequently long end shear spans between the boundary of the upper wall and the face of the lower column. This paper presents the results of tests and analyses performed on three 1:2.5 scale specimens with long end shear spans, (the ratios of shear-span/total depth: 1.8 < a/h < 2.5): one designed by the conventional approach using the beam theory and two by the strut-and-tie approach. The conclusions are as follows: (1) the yielding strength of the continuous RC deep girders is controlled by the tensile yielding of the bottom longitudinal reinforcements, being much larger than the nominal strength predicted by using the section analysis of the girder section only or using the strut-and-tie model based on elastic-analysis stress distribution. (2) The ultimate strengths are 22% to 26% larger than the yielding strength. This additional strength derives from the strain hardening of yielded reinforcements and the shear resistance due to continuity with the adjacent span. (3) The pattern of shear force flow and failure mode in shear zone varies depending on the amount of vertical shear reinforcement. And (4) it is necessary to take into account the existence of the upper wall in the analysis and design of the deep continuous transfer girders that support the upper wall with a long end shear span.

• Journal of Power Electronics
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• 제16권3호
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• pp.1012-1024
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• 2016

This study deals with an on-line software fault detection, localization, and system reconfiguration method for electrical system drives composed of three-phase AC/DC/AC converters and three-phase permanent magnet synchronous machine (PMSM) drives. Current sensor failure (outage), speed/position sensor loss (disconnection), and damaged DC-link voltage sensor are considered faults. The occurrence of these faults in PMSM drive systems degrades system performance and affects the safety, maintenance, and service continuity of the electrical system drives. The proposed method is based on the monitoring signals of "abc" currents, DC-link voltage, and rotor speed/position using a measurement chain. The listed signals are analyzed and evaluated with the generated residuals and threshold values obtained from a Sliding Mode Current-Speed-DC-link Voltage Observer (SMCSVO) to acquire an on-line fault decision. The novelty of the method is the faults diagnosis algorithm that combines the use of SMCSVO and adaptive thresholds; thus, the number of false alarms is reduced, and the reliability and robustness of the fault detection system are guaranteed. Furthermore, the proposed algorithm's performance is experimentally analyzed and tested in real time using a dSPACE DS 1104 digital signal processor board.

• 한국항공운항학회지
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• 제24권1호
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• pp.10-15
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• 2016

In this study, The code-carrier divergence test was applied to GPS measurements, and the results were compared and analyzed. The GPS data used for the threshold determination were obtained from Global Navigation Satellite System permanent stations built by the Korea Aerospace Research Institute. At each permanent station, identical dual-frequency receiver and choke ring antenna with radome are installed. The analysis method, root mean square values were compared and analyzed for each permanent station and satellite. As a result, the root mean square value generally decreased as the satellite elevation angle increased although the trend was gentle. Threshold were finally selected based on the average and standard deviation of root mean square for each permanent station. For improving of availability and continuity in real-time operation when the threshold is over the limits, Code-Carrier divergence test values are initialized.

• 지질공학
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• 제33권4호
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• pp.573-586
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• 2023

절리성 암반은 절리 또는 연약면에 의해 역학적인 이방성이 발현될 수 있으며 절리성 암반의 강도 및 변형 특성에 대한 이해는 지질공학 현장에서 주된 관심사이다. 본 연구는 마찰재료로 채택된 석고를 이용하여 단일절리를 포함하는 시료를 성형하고 진삼축시험을 통하여 진삼축 조건의 강도 및 변형 특성을 고찰하였다. 동일한 조건에서 수행한 개별요소법 기반의 삼차원 수치해석은 진삼축시험을 통하여 검증되었으며 타당성이 확보되었다. 수치해석 결과는 절리의 방향성과 더불어 현장의 주응력 조건이 절리성 암반의 강도 및 변형 특성 연구에 있어서 필수적인 요소임을 지시한다. 수치해석을 통하여 절리의 경사각 변화에 따라 산정한 횡등방성 암반의 강도는 중간주응력이 강화함에 따라 유의미한 증가를 나타내며, 증가의 폭은 절리의 경사 조건에 큰 영향을 받는다. 또한, 절리의 경사방향과 두 수평 주응력 방향 간의 상대적인 관계는 횡등방성 암반의 강도특성을 좌우하는 요인이다. 두 개의 절리군을 포함하는 암반의 강도는 경사가 더욱 급한 절리군이 전체 암반의 강도를 좌우한다. 두 절리군 중 한 절리군의 연속성이 짧아 암교 효과를 발휘하면 연속성이 상대적으로 긴 절리군의 방향성이 전체 암반의 강도를 좌우할 수 있다. 절리성 암반에 대한 기존의 삼차원 파괴기준식은 적용성 측면에서 한계도 있지만, 수치해석이 이를 보완하는 데 유용하게 활용될 수 있다.

• 한국의사학회지
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• 제34권2호
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• pp.1-10
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• 2021

During the Joseon Dynasty, Jeju had a unique aspect that differentiated it from other regions in terms of their medical system, such as the exclusive deployment of shimyak dispatched to Gamyeong and Barracks units due to the uniqueness of being an island. This study uses various historical sources to verify that these differences existed throughout the medical system and procedures of Jeju in the late Joseon Dynasty. The following significant conclusions were drawn: 1) Looking at the work and characters of Jejushimyak reveals the inherent limitations of Jeju medical care in the Joseon Dynasty. Compared to other regions' shimyak, Jejushimyak had two limitations: it was difficult to engage in only medicine and the quality of medical doctors declined due to the avoidance of major medical doctors' households. 2) The establishment of public health care in Jeju through Medical Cadets failed. Jeju medical science obviously played an essential role in public health care in the early 18th century. However, there was no continuity in the garden, etc. Hyangri, who was in charge of Medical Cadets, was in charge of various fragrances as needed. Thus expertise in medicine was lacking. 3) The cultivated herbs of Jeju's herb field show the failure to supply herbs for institutional medicine. It was impossible to supply enough herbs to implement institutional medicine in Jeju. In that case, it would have been necessary to discover alternative local herbs or to bring them in from outside, but there was barely any such effort. In conclusion, in the late Joseon Dynasty, Jeju failed to establish a foundation for centrally administered institutional medicine. There was a lack of all the entities that provided medical care and herbs that could be used for medical care. The reason that Jeju continued to follow traditional shaman medicine in the late Joseon Dynasty was because there was no other alternative.

• 한국해양공학회지
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• 제27권4호
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• pp.90-97
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• 2013

Oil booms are one of the most widely used types of equipment for the protection of coastal areas against oil spills. In some situations, however, there are several types of oil leaks from the oil boom. Important factors regarding these phenomena include the surrounding ocean environment, such as waves, the density and viscosity of oil, the length of the oil boom skirt, etc. To estimate the performance of the oil boom, it is necessary to predict the behavior of the spilled oil and oil boom. In the present study, the prediction of oil boom performance in waves was carried out using the Pusan-National-University-modified Moving Particle Semi-implicit (PNU-MPS) method, which is an improved version of the original MPS proposed by Koshizuka and Oka (1996). The governing equations, which consist of continuity and Navier-Stokes equations, are solved by Lagrangian moving particles, and all terms expressed by differential operators in the governing equations are replaced by the particle interaction models based on a kernel function. The simulation results were validated through a comparison with the results of Violeau et al. (2007)..

• 한국항행학회논문지
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• 제21권1호
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• pp.50-57
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• 2017

최근 국내에서 추진된 항공 관련 안전필수시스템 기술 개발 사업들이 중도에 종료되거나 최종 단계에서 실용화되지 못하는 사례가 종종 발생했다. 사업실패의 원인은 여러 가지 요인이 있겠지만 본 연구에서는 불완전한 시험평가 절차에 주안점을 두고 관련 연구를 수행하였다. 일반적으로 안전필수시스템의 시험평가 프로세스는 시스템의 전 수명주기에 걸쳐 분포되고 단계별 연속성을 가져야 하며 시스템 설계 및 획득 전략의 성숙도에 따라 다양한 방법으로 실행될 수 있다. 본 논문의 목적은 국내 안전필수 항행시스템 개발 사업의 리스크를 줄이고 성공률을 높이기 위한 방안으로 국내외 시험평가 프로세스를 분석하여 새로운 전략을 제시하는 것이다. 먼저 안전필수시스템에 대한 검증 및 확인 기법에 대해 토의하고 선진기관의 시험평가 프로세스 및 절차와 국내 현황을 분석한 뒤 국내외 시험평가 프로세스를 비교함으로써 불완전한 시험평가 절차에 대한 보완책을 제시하였다.