• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 추계학술대회 논문집
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• pp.254-260
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• 1998

Application of bonded dissimilar materials in various industries are increasing. When these materials are used in structures, it needs to investigate strength evolution applying fracture mechanics. Al/Epoxy bonded dissimilar materials with an interface crack and an interface crack emanating from an edge semicircular hole were prepared for the static tests so that experiment of fracture toughness were carried out. Stress intensity factors of interface cracks in bonded dissimilar materials were computed with boundary element method(BEM) and the fracture criterion of mixed mode crack were analyzed. From the results, the fracture criterion and the method of strength evolution by the fracture toughness in Al/Epoxy bonded dissimilar materials were proposed.

• Industrial Engineering and Management Systems
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• 제14권3호
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• pp.299-311
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• 2015

Nowadays, the distribution centres aim to reduce costs by reducing inventory and timely shipment. Cross docking is a logistics strategy in which products delivered to a distribution centre by inbound trucks are directly unloaded and transferred to outbound trucks with minimum warehouse storage. Moreover, on-time delivery in a distribution network becomes very crucial especially when several distribution centres and customers are involved. Therefore, an efficient truck scheduling is needed to synchronize the delivery throughout the network in order to satisfy all stake-holders. This paper presents a mathematical model of a mixed integer programming for door assignment and truck scheduling in a multiple inbound and outbound doors cross docking problem according to Just-In-Time concept. The objective is to find the schedule of transhipment operations to simultaneously minimize the total earliness and total tardiness of trucks. Then, a multi-objective differential evolution (MODE) is proposed with an encoding scheme and four decoding strategies, called ITSH, ITDD, OTSH and OTDD, to find a Pareto frontier for the multi-door cross docking problems. The performances of MODE are evaluated using 15 generated instances. The numerical experiments demonstrate that the proposed algorithm is capable of finding a set of diverse and high quality non-dominated solutions.

• 한국항공우주학회지
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• 제31권10호
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• pp.40-50
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• 2003

저고도, 태양동기궤도인 아리랑 1호의 최초 임무운영 목표였던 3년 동안 관측된 궤도 변화를 분석하였다. 초기운영기간 동안 최적화된 궤도를 획득하기 위해 총 4회의 궤도조정이 있었으며, 총 8회의 안전모드가 발생하였다. 예상치 않은 안전모드 발생과 임무기간 동안 최고조에 달했던 태양활동이 궤도변화에 미치는 영향을 분석하였고, 초기 궤도조정 완료 직후 임무운영 기간에 대해 예측되었던 장기 궤도예측 결과와 궤도결정을 통해 실측된 궤도와의 차이를 분석하였다. 최적화된 궤도에서부터 운영된 3년의 임무기간 동안 고도를 제외한 나머지 궤도요소들은 설계된 임무궤도 범위 내에서 변화하였고, 태양동기궤도 특성을 유지하였음을 확인하였다.

• 천문학회보
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• 제38권2호
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• pp.74.2-74.2
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• 2013

Recent spectroscopic observations have provided evidences for the multiple stellar populations having different abundances in some massive globular clusters (GCs). In particular, some of these GCs show clear separations of red giant-branches (RGBs) in calcium narrow band photometry. In order to confirm the differences in heavy element abundances and radial velocities among multiple RGBs, we have performed the low-resolution spectroscopy for the RGB stars in these GCs. The spectral data were taken from the multi-object spectroscopic mode with WFCCD mounted on the du Pont 2.5m telescope in Las Campanas Observatory. In this talk, we will present our progress in the spectroscopic analysis of the RGB stars in these GCs.

• 천문학회보
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• 제44권2호
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• pp.77.1-77.1
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• 2019

We present the results of the merger fraction evolution for galaxies in NEP-Wide field depending on star formation mode and redshift. We select the galaxies which have AKARI 9 ㎛ detections as a sample for large number of galaxies. We use multi-wavelength data from GALEX to Herschel, and Subaru HSC i-band images for analysis. We classify the merger galaxies with using Gini and M20, which are non-parametric calculated by statmorph code. We obtain the total infrared luminosity from the SED modeling with using one band, AKARI 9 ㎛. We find that the merger fractions of galaxies in all different star formation mode increase as the redshift increases. However, with fixed mass range of 10.5 < log(M🞵) < 11.5, the merger fractions of starbursts significantly increase as the redshift increases compared to those of main sequence and quiescent galaxies. We discuss the implications of these results in this poster.

• Journal of Welding and Joining
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• 제18권1호
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• pp.59-69
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• 2000

The purpose of the present study was to investigate weld metallurgical phenomena such as primary solidification mode, microstructural evolution and hot cracking susceptibility in nitrogen-bearing austenitic stainless steel GTA welds. Eight experimental heats varying nitrogen content from 0.007 to 0.23 wt.% were used in this study. Autogenous GTA welding was performed on weld coupons and the primary solidification mode and their microstructural characteristics were investigated from the fusion welds. Varestraint test was employed to evaluate the solidification cracking susceptibility of the heats and TCL(Total Crack Length) was used as cracking susceptibility index. The solidification mode shifted from primary ferrite to primary austenite with an increase in nitrogen content. Retained delta ferrite exhibited a variety of morphology as nitrogen content varied. The weld fusion zone exhibited duplex structure(austenite+ferrite) at nitrogen contents less than 0.10 wt.% but fully austenitic structure at nitrogen contents more than 0.20 wt.%. The weld fusion zone in alloys with about 0.15 wt.% nitrogen experienced primary austenite + primary ferrite solidification (mode AF) and contained delta ferrite less than 1% at room temperature. Regarding to solidification cracking susceptibility, the welds with fully austenitic structure exhibited high cracking susceptibility while those with duplex structure low susceptibility. The cracking susceptibility increased slowly with an increase in nitrogen content up to 0.20 wt.% but sharply as nitrogen content exceeded 0.20 wt.%, which was attributed to solidification mode shift fro primary ferrite to primary austenite single phase solidification.

• IEIE Transactions on Smart Processing and Computing
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• 제2권1호
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• pp.36-43
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• 2013

This paper provides an overview of the security in the System Architecture Evolution (SAE) / Long-Term Evolution (LTE) system. Security is an integral part of SAE/LTE with improvements over the Third Generation (3G) system. This paper reviews the SAE/LTE system architecture, and discusses the security requirements, algorithms, Authentication and Key Agreement (AKA), Security Mode Command (SMC), key hierarchy and security for mobility.

• 천문학회보
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• 제37권2호
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• pp.119.1-119.1
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• 2012

It is well known that the FLRs are excited by compressional waves via mode conversion, but there has been no apparent criterion on the maximum amplitude in the regime of linear approximations. Such limited range of amplitude should be understood by including nonlinear saturation of FLRs, which has not been examined until now. In this study, using a three-dimensional magnetohydrodynamic (MHD) simulation code, we examine the evolution of nonlinear field line resonances (FLRs) in the cold plasmas. The MHD code used in this study allows a full nonlinear description and enables us to study the maximum amplitude of FLRs. When the disturbance is sufficiently small, it is shown that linear properties of MHD wave coupling are well reproduced. In order to examine a nonlinear excitation of FLRs, it is shown how these FLRs become saturated as the initial magnitude of disturbances is assumed to increase. Our results suggest that the maximum amplitude of FLRs become saturated at the level of the same order of dB/B as in observations roughly satisfies the order of ~0.01. In addition, we extended this study for the plasma sheet boundary layer (PSBL) region. We can discuss the maximum disturbances of the Alfven via mode conversion becomes differently saturated through each region.

• 한국융합학회논문지
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• 제12권6호
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• pp.65-74
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• 2021

2020년부터 중국 광시 지방정부는 차 산업과 레저 문화 관광, 과학 보급 교육, 양생 양로 등 산업의 심층융합에 주목하고 있다. 또한 차 산업이 빠르게 발전하고 있어 3차 산업 생산 목표치를 250억 위안으로 계획하였다. 본 연구는 세대별 소비자에 대한 설문조사, 현지조사, 전문가 인터뷰 등을 통하여 차에 대한 니즈와 선택의 차이에 대해 분석하여 광시 차 산업 서비스 모델의 변화 패턴을 연구하였다. 연구 결과에 따르면, 소비자는 세대별로 생활방식, 쇼핑 습관, 서비스 디자인, 사용자 경험, 사회적 니즈, 개인적 니즈에서 뚜렷한 차이가 있다. 이에 차 제품에 대한 니즈와 행동 패턴을 분석하고 광시 차 산업 서비스 모델의 패턴 변화에 근거해보면, 세대별 소비자의 차 선택의 차이가 차 제품의 수요, 행동 패턴에 유의미한 차이와 패턴 변화를 발견할 수 있다. 끝으로 차 산업의 발전을 위한 서비스 디자인, 사용자 경험 모델 개발의 필요성을 주목하고 있다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.956-961
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• 2003

Direct numerical simulations of flow over a circular cylinder are performed at two different Reynolds numbers (Re=220 and 300) that correspond to three-dimensional instabilities of mode A and mode B, respectively, to investigate the characteristics of drag and lift at these Reynolds numbers. The drag and lift coefficients are measured locally along the spanwise direction and their characteristics are studied in detail. The variation of total drag in time is large at Re=220, and the total drag becomes minimum when vortex dislocation occurs in the wake. The drag and lift variations in space are also closely associated with the evolution of vortex dislocation at this Reynolds number. At Re=300, vortex dislocation is not found in the wake and temporal variations of drag and lift are much smaller than those at Re=220, but their spatial variations are quite large due to the near-wake secondary vortices existing in the mode B instability.