• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2017년도 춘계학술논문요약집
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• pp.149-150
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• 2017

• 한국압력기기공학회 논문집
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• 제18권2호
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• pp.61-68
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• 2022

Accurate evaluation of residual stress is important for stress corrosion cracking assessment. In this paper, electron beam welding experiment is simulated via finite element analysis and the sensitivity of the parameters related to the combined heat source model is investigated. Predicted residual stresses arecompared with measured residual stresses. It is found that the welding efficiency affects the size of the tensile residual stress area and the magnitude of maximum longitudinal residual stress. It is also found that the parameter related to the ratio of energy distributed to the two-dimensional heat source has little effect on the size of tthe tensile residual stress area, but affects the size of the longitudinal residual stress in the center of the weld.

• 한국기계가공학회지
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• 제20권12호
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• pp.113-122
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• 2021

Complicated residual stress distributions occur in the vicinity of a deposited region via directed energy deposition (DED) process owing to the rapid heating and cooling cycle of the deposited region and the substrate. The residual stress can cause defects and premature failure in the vicinity of the deposited region. Several heat treatment technologies have been extensively researched and applied on the part deposited by the DED process to relieve the residual stress. The aim of this study was to investigate the residual stress characteristics of a specimen fabricated by DED and a quenching process using thermomechanical analyses. A coupled thermomechanical analysis technique was adopted to predict the residual stress distribution in the vicinity of the deposited region subsequent to the quenching step. The results of the finite element (FE) analyses for the deposition and the cooling measures show that the residual stress in the vicinity of the deposited region significantly increases after the completion of the elastic recovery. The results of the FE analyses for the heating and quenching stages further indicate that the residual stress in the vicinity of the deposited region remarkably increases at the initial stage of quenching. In addition, it is observed that the residual stress for quenching is lesser than that after the elastic recovery, irrespective of the deposited material.

• 정보과학회 논문지
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• 제42권12호
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• pp.1495-1502
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• 2015

센서 네트워크에서 압축은 종단 간 지연시간과 에너지 사용량 사이의 이율배반적인 관계가 있다. 데이터의 크기를 줄이기 위해 압축을 하면, 추가적인 지연시간과 에너지 소비가 발생하지만, 전송으로 인한 에너지 소모는 감소하게 된다. 일반적으로, 배터리기반 센서 네트워크에서는 지연시간을 손해 보더라도 네트워크의 생존시간을 최대화하기위해 압축을 널리 사용하고 있다. 한편 태양 에너지 기반 센서 네트워크에서는 주기적으로 에너지 재생산이 이루어짐에 따라, 동작하는데 충분한 에너지양 이상의 에너지가 존재할 가능성이 있다. 본 논문에서는 여분의 에너지를 사용해 종단 간 지연시간을 감소시키는 에너지 적응형 선택적 압축 기법을 제안한다. 제안하는 기법은 노드의 에너지가 충분하지 않을 때, 에너지 소비를 줄이기 위해 압축을 사용하고, 에너지가 충분한 경우에는 종단 간 지연시간 감소를 위해 압축을 사용하지 않는다. 시뮬레이션을 통한 에너지와 지연시간의 성능평가를 통하여 제안하는 기법의 우수성을 증명하였다.

• 대한기계학회논문집
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• 제18권8호
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• pp.1930-1938
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• 1994

In this paper, the effects of temperature change on the impact of CFRP laminates was experimentally studied. Composite laminates used for this experiment are CFRP orthotropic laminated plates, which have two-interfaces$[0_6^{\circ}/90_7^{\circ}]_s$ and four-interfaces$[0_3^{\circ}/90_6^{\circ}/0_3^{\circ}]_s$. The interrelations between the impact energy vs. delamination area, the impact energy vs. residual bending strength, and the interlayer delamination area vs. the decrease of the residual flexural strength of carbon fiber epoxy composite laminates subjected to FOD(Foreign Object Damage) under high temperatures were experimentally observed.

• 펄프종이기술
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• 제39권5호
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• pp.7-11
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• 2007

Kraft pulping of Trema orientalis (Nalita) was studied in order to find kinetic data for delignification. Pulping runs were carried out in the temperature range of $160-180\;^{\circ}C$ under constant and well-defined conditions. The delignification was found to be first order with respect to residual lignin and was chemically controlled. The rate of delignification reaction was increased 1.11-1.23 for $10\;^{\circ}C$ temperature increase in the range of $160-180\;^{\circ}C$ range. A mean value of 93% of lignin was removed at the transition between bulk and residual delignification. The influence of cooking temperature on the rate constant was expressed by an Arrhenius-type equation. The obtained activation energy of the delignification reaction was 6,164 cal/mol. The transition point between bulk and residual phase was shifted to lower lignin and carbohydrate yield with the increase of temperature.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.331-336
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• 2008

An self-centering energy-dissipative (SCED) bracing system has recently been developed as a new seismic force resistant bracing system. The advantage of the SCED brace system is that, unlike other comparable advanced bracing systems that dissipate energy, such as the buckling restrained brace system, it has a self-centering capability that reduces or eliminates residual building deformations after major seismic events. In this study seismic performance of SCED braced frames is evaluated for a set of 20 design level earthquake records. According to analysis results the SCED systems showed more uniform interstory drift demand for buildings with 8 story or fewer. The residual deformation in SCED buildings turned out to be much less than that of moment-resisting frames.

• 한국정보통신학회논문지
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• 제24권5호
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• pp.666-669
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• 2020

Energy harvesting sensor networks have the ability to collect energy from the environment to overcome the power limitations of traditional sensor networks. The sensor network, which has a limited transmission range, delivers data to the destination node through a multi-hop method. The routing protocol should consider the power situation of nodes, which is determined by the residual power and energy harvesting rate. At this time, if only considering the magnitude of the power, power imbalance can occur among nodes and it can induce instantaneous power shortages and reduction of network lifetime. In this paper, we designed a routing protocol that considers the balance of power as well as the residual power and energy harvesting rate.

• 한국컴퓨터정보학회논문지
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• 제19권9호
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• pp.55-63
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• 2014

무선센서네트워크(WSNs)에서 센서시스템의 한정된 에너지를 극복하기 위한 연구들이 활발하게 진행되고 있다. 이들은 대부분에너지 적응형(Energy-aware) 기법들이 많은데, 이 기법들은 노드 자신 또는 이웃노드들의 에너지양을 활용하고 있다. 그러나 기존의 센서시스템에서는 전압과 소모전류만을 가지고 잔여에너지양을 예측하고 있는데, 실제 배터리의 잔여에너지양은 온도와 로드(Load)의 영향을 많이 받기 때문에 정확하지 못할 수 있다. 본 연구에서는 배터리의 전압과 함께 배터리의 온도와 부하 특성을 반영한 효율적인 잔여에너지양 추정기법을 제안한다. 제안한 기법은 실제 환경에서의 실험과 시뮬레이션을 통해 그 성능을 검증하였다.

• 한국수소및신에너지학회논문집
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• 제13권1호
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• pp.65-73
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• 2002

Because of low flame ion density in hydrogen-air mixture, many residual electric energy could be existed in the ignition system of hydrogen engine, If these residual energy discharged abnormally during intake stroke, it may be the cause of backfire occurrence which is serious problem in development of hydrogen fueled engine but unsolved in spite of many concerned research on it. In this study, the possibility of backfire occurrence by abnormal electric discharge and countermeasure of that were investigated by using the experimental single cylinder hydrogen fueled engine with two types of ignition system. The results show that abnormal electric discharge appeared in low load with low ion density and then results in back fire occurrence, It is also seen that countermeasure method installing larger earth resistance in high tension code is effective to control abnormal electric discharge.