• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
• /
• pp.1115-1122
• /
• 2011

Reinforced-Roadbed materials are usually composed of crushed stones. Repeated load application can induce deformation in the reinforced-roadbed layer so that it causes irregularity of track. Thus it is important to develop a prediction model of elastic modulus based on stress-strain relation under repeatitive load in order to investigate behavior of reinforced roadbed. The prediction model of elastic modulus of the material can be obtained from repeated triaxial test. However, a proper size of the sample for the test must be used. In this study, a large repeatitive triaxial test apparatus with the sample size of diameter of 30 cm and height of 60cm was adapted for performing test of the crushed stone reinforced-roadbed considering large particle size to get resilient modulus Mr. The obtained resilient modulus was compared to shear modulus obtained from mid size resonant column test. The sample size effect is somewhat large enough so that it is required to design a scale factor based on similarity law in order to use smaller samples for getting elastic modulus of the crushed stone reinforced-roadbed material. A scale factor could be obtained from this study.

• 제어로봇시스템학회논문지
• /
• 제17권11호
• /
• pp.1082-1089
• /
• 2011

Most engineered systems are designed with high levels of system redundancies to satisfy required reliability requirements under adverse events, resulting in high systems' LCCs (Life-Cycle Costs). Recent years have seen a surge of interest and tremendous advance in PHM (Prognostics and Health Management) methods that detect, diagnose, and predict the effects of adverse events. The PHM methods enable proactive maintenance decisions, giving rise to adaptive reliability. In this paper, we present a RAP (Resilience Allocation Problem) whose goal is to allocate reliability and PHM efficiency to components in an engineering context. The optimally allocated reliability and PHM efficiency levels serve as the design specifications for the system RBDO (Reliability-Based Design Optimization) and the system PHM design, which can be used to derive the detailed design of components and PHM units. The RAP is demonstrated using a simplified aircraft control actuator design problem resulting in a highly resilient actuator with optimally allocated reliability, PHM efficiency and redundancy for the given parameter settings.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2005년도 춘계학술대회논문집
• /
• pp.648-655
• /
• 2005

The resilient mounts of a diesel engine installed onboard a ship should be designed for both static and dynamic loads. If possible, the resonance frequencies of the six rigid body modes of the installation and the flexible modes of the engine support structure should not lie within the engine operation range. In this paper a design criterion is proposed to evaluate an isolation system which involves the summation of dynamic forces transmitted through the resilient mounts and elastic potential energy index stored in the mounts. A case study is also presented in which a diesel engine generator, which had an elastic foundation and was mounted in a 5500 TEU container vessel, was studied both theoretically and experimentally. The theoretical analysis of the test model was performed by using a single mass 6 degree of freedom system. Actual measurements of mechanical vibration of the Engine and its foundation onboard were carried out, which showed the importance of including the flexibility of the engine support structure in the mode

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 ITC-CSCC -2
• /
• pp.1003-1006
• /
• 2002

In the communications systems with diversity, we are commonly faced on needing of new source coding technique, error resilient coding. The error resilient coding addresses the coding algorithm that has the robustness to unreliability of communications channel. In recent years, many error resilient coding techniques were proposed such as data partitioning, resynchronization, error detection, concealment, reference picture selection and multiple description coding (MDC). Especially, the MDC using correlating transform explicitly adds correlation between two descriptions to enable the estimation of one set from the other. However, in the conventional correlating transform method, there is a critical problem that decoder must know statistics of original image. In this paper, we propose an enhanced method, the MDC using whitening transform that is not necessary additional statistical information to decode image because the DCT coefficients to apply whitening transform to an image have uni-variance statistics. Our experimental results show that the proposed method achieves a good trade-off between the coding efficiency and the reconstruction quality. In the proposed method, the PSNR of images reconstructed from two descriptions is about 0.7dB higher than conventional method at the 1.0 BPP and from only one description is about 1,8dB higher at the same rate.

• 대한토목학회논문집
• /
• 제9권4호
• /
• pp.83-92
• /
• 1989

강성포장(剛性鋪裝)에 대하여 더 좋은 공용성능(供用性能) 기대를 위한 개발과 파손발생에 대한 파손과정에 관하여 포장상태를 조사하게 된다. 본 논문(論文)은 공용중(供用中)인 시멘트콘크리트 포장(鋪裝)의 피로거동(疲勞擧動)과 탄성특성(彈性特性)에 대한 연구결과이다. 공용중(供用中)인 각(各) 포장(鋪裝)의 평균인장강도(平均引張強度)를 측정하기 위하여 Indirect tensile시험을 실시한 것이다. 변형측정(變形測定)은 이러한 특성의 변화 및 콘크리트의 탄성특성(彈性特性)을 구하기 위한 피로(疲勞)시험을 통하여 이루어진 것이다.

• 소음진동
• /
• 제9권3호
• /
• pp.477-484
• /
• 1999

This study aims to present proper thickness of resilient mount and pattern of chips for the improvement of impact sound isolation. To achieve this aim, field tests were performed to evaluate the performance of impact sound isolation of pilot samples using waste tire chips against light and heavy-weight impacter, which samples were installed over concrete slabs of an apartment housing. In this study, the experiments were performed by the impact sound level of floors in KS F 2810 "Method for field measurement of floor impact level". As results, a flooring structure using waste tire chips as a resilient mount, with no relation to chip's types, has enhanced performance by 1~2 degree in light impact sound isolation, while it has improvement in heavy impact sound isolation. And fiber-type chips have better performance than granule-type ones when they overlaid concrete slab with 15~20 mm of thickness. For the improvement of impact sound isolation, it is recommended that insulating materials should be applied at joints between floating floors and walls, or floating floors and a doorframes, and also waterproof papers should be used for the effective thickness of resilient mount.ent mount.

• 한국소음진동공학회논문집
• /
• 제23권3호
• /
• pp.218-225
• /
• 2013

Vertically-launched missiles are supported as erected vertically in the vertical launching system of warship, and they should be mounted in the same way when vibration-tested. However, mounting missiles vertically makes a fixture, which is a supporting structure, bulky and heavy so requiring a high-performance exciter. Mounting missiles as laid down horizontally in a vibration test is economical regarding fixture manufacturing and exciter performance, but it makes test results incorrect because the different mounting direction has effects on the test results. A bending moment due to missiles' weight happens to missiles, and resilient mounts, which support missiles in the vertical launch system, deflect differently from the real situation because of the static deflection of these mounts due to missiles' weight. If the resilient mounts supporting missiles have nonlinear force-deflection characteristics, vibration test results become more different from the true results. This paper proposes to support missiles with an additional resilient mount such as a bunge code in order to solve those problems coming from mounting vertically-launched missiles as laid down horizontally in vibration tests. The proposed approach enables to obtain the same test results as in their actual mounting condition even though vertically-launched missiles are mounted in a different direction.

• 한국지반환경공학회 논문집
• /
• 제13권9호
• /
• pp.61-68
• /
• 2012

본 연구의 주된 목적은 EPS지오폼이 연성포장의 노반재료로 사용될 때 그것의 회복탄성계수를 해석 모델화 하는 것이다. 이 해석모델은 삼축압축 시험으로부터 나온 실험결과를 토대로 만들어졌다. 그리고 이 모델은 원하는 용도에 따라서, 기존의 프로그램을 수정하거나 새로 개발하여 유한요소법을 이용한 연성포장구조를 해석하는데 사용될 수 있다. 또한 본 연구의 결과는 연성포장에서의 현장 연약지반 노상재료의 대체물로서 EPS지오폼은 적합한 것으로 확인되었다.

• 한국도로학회논문집
• /
• 제11권3호
• /
• pp.75-83
• /
• 2009

안정처리된 도로 지반재료는 현장에서 환경적인 요인으로 인하여 내구성능은 여전히 구조적인 성능과 더불어 평가가 요구되고 있다. 이에 본 논문에서는 국내에서 대표적으로 활용하고 있는 기층과 노상재료를 활용하여 다양한 안정제 종류와 함유량을 달리하여 공시체를 제작하였고 동결-융해 및 습윤-건조하여 여러 조건의 반복재하 회복탄성계수시험을 실시하여 내구성능 및 특성을 파악하였다. 또한 결과에 기초하여 안정처리된 지반재료에 대한 회복탄성계수 예측모델을 살펴보고 모델계수의 범위를 평가후 문헌의 자료와 비교하였다.

• 한국도로학회논문집
• /
• 제15권2호
• /
• pp.83-94
• /
• 2013

PURPOSES : In Korea, most designs of pavement had been mainly performed by considering CBR of granular materials before KPRP(Korea Pavement Research Program) and 86 AASHTO design method were introduced. Since then, the trend of the pavement designs gradually have moved to using mechanical characteristics throughout the resilient modulus based on the test results up to recently. In this study, we should like to research the mechanical characteristics of paving materials containing Recycled aggregates through the cyclic loading triaxial compression tests. METHODS : The kinds of materials were tested; coarse grained subbase materials, refining aggregates base materials and recycled aggregates. RESULTS : The present study aims to figure out the resilient modulus of paving materials containing Recycled aggregates through the cyclic loading triaxial compression tests. CONCLUSIONS : The test results revealed that the engineering properties of the recycled aggregates were more excellent than the those of others.