• Journal of Welding and Joining
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• 제17권3호
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• pp.96-101
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• 1999

Microstructures and mechanical properties of weldments were studied for EH36 TMCP higher-strength hull steel with electrogas welding jprocess. In case of a newly designed EH36 TMCP steel for large heat input welding process, the Microstructures of HAZ shows more narrow width of grain coarsed region than that of conventional EH36 TMCP weldments, the amount of acicular ferrite, which is beneficial to impact toughness, increased while the amount of grain-boundary ferrite decreased. Charpy V-notched impact tests show that a newly designed EH36 TMCP steel weldment satisfies all the requirement of specifications, especially at the fusion line +2mm where the conventional EH36 TMCP steel fails to exceed the requirement.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권12호
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• pp.4451-4466
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• 2014

We present joint radio selection and relay scheme that delivers data from a source to a sink in heterogeneous stationary sensor networks consisting of various radio interfaces. The proposed scheme finds the optimal relay nodes and their corresponding radio interfaces that minimize energy consumption throughout the network while satisfying the end-to-end packet deadline requirement. We formulate the problem of routing through radio interface selection into binary integer programs, and obtain the optimal solution by solving with an optimization solver. We examine a trade-off relationship between energy consumption and packet delay based on network level simulations. We show that given the end-to-end deadline requirement, our routing algorithm finds the most energy-efficient routing path and radio interface across mesh hops. We demonstrate that the proposed routing scheme exploits the given packet delivery time to turn into network benefit of reducing energy consumption compared to routing based on single radio interface.

• 산업공학
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• 제9권3호
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• pp.64-71
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• 1996

In the survivability and simplicity aspect, SONET Self-healing Ring(SHR) is one of the most important schemes for the high-speed telecommunication networks. Since the ring capacity requirement is defined by the largest STS-1 cross-section in the ring, load balancing is the key issue in the design of SONET SHR. Recently, most of the research on load balancing problem have been concentrated on the SONET single-ring case. However, in certain applications, multiple-ring configuration is necessary because of the geographical limitations or the need for extra bandwidth. In this paper, the load balancing problem for SONET dual-ring is considered by assuming symmetric inter-ring demands. We present a linear programming based formulation of the problem. Initial solution and improvement procedures are presented, which solves the routing and interconnection between the two rings for each demand. Computational experiments are performed on various size of networks with randomly generated demand sets. Results show that the proposed algorithm is excellent in both the solution quality and the computational time requirement. The average error bound of the solutions obtained is 0.26% of the optimum.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 춘계 학술논문 발표대회
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• pp.271-272
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• 2013

The Korean nuclear industry acquired technology for each construction stage including engineering, procurement, construction and commissioning from advanced nuclear countries. While the levels of technology and quality have greatly improved, the same cannot be said for the level of project management. In particular, the level of project performance measurement and forecasting project risk still remain at the single project management level. Thus, this paper reviewed the concept of the EVMS method and requirement for the system. The adoption of the EVMS, an advanced project management method, can enable efficient management of project risks and promote an adequate environment for project implementation.

• 한국항공우주학회지
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• 제45권10호
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• pp.825-835
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• 2017

본 논문에서는 단일 보의 최적 설계를 활용하여 드론 플랫폼을 구축하였다. 단일 보를 끝 단 질량을 가진 외팔보로 가정하였다. 수치 최적화 이론에 기초하여, ANSYS가 얻은 유사한 결과와 비교함으로써 새로운 설계의 검증 및 최적화를 수행 하였다. 마지막으로, 이 설계는 제어 시뮬레이션에 반영되며 공진 상황을 고려한 최적의 구조 설계 요구 사항을 만족함을 보였다.

• 한국공간구조학회논문집
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• 제11권3호
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• pp.137-145
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• 2011

최근 건축 경향에 따라 단층 프리폼 구조에 대한 관심이 증대되고 있다. 축력과 모멘트를 동시에 받는 구조적인 특성으로 인해 프리폼 구조에서 노드는 응력이 집중되는 부분으로 상세 개발이 이루어져야 한다. 본 논문은 단층 프리폼 구조의 모멘트형 노드를 제안하고 축력과 모멘트에 대한 유한요소해석을 수행하였다. 유한요소해석을 통해 내력이 검증된 모델에 구멍 크기 및 위치에 따른 변수를 적용하여 변수해석을 진행하였고 결과를 비교분석하여, 구조적인 성능을 만족하여 안전성을 가지고 동시에 물량도 가장 절약할 수 있는 노드 Prototype을 결정하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 추계학술대회 논문집
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• pp.95-96
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• 2015

In this paper, a single-sourced PV PCS using the trinary asymmetric MLI with a single-ended pre-regulator is proposed. Trinary based asymmetric CHB inverters provide higher output levels for the same number of cells compared to other CHB inverters. However, there is an issue of regeneration with trinary asymmetric inverters and this complicates the system with requirement of bi-directional converters at the input. Modified commutation strategies have been used to remove the regeneration issue with compromise in THD. The single-ended pre-regulator provides the isolated dc-link voltage for the individual H-bridge cells with the advantage of having a single switch and magnetic component. This implementation increases the magnetic utilization of the inductor core and reduces the switching loss in the pre-regulator and also the reduced parts count contributes to the cost competiveness of the proposed PCS. The proposed PV PCS has been verified using simulation results in this paper.

• 한국토양비료학회지
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• 제21권3호
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• pp.280-288
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• 1988

강원도(江原道) 지역(地域)의 답토양(畓土壤)이 널리 분포(分布)되어 있는 석회암지대(石灰岩地帶), 하성충적충지대(河成沖積層地帶), 현무암지대(玄武岩地帶) 토양(土壤)을 대상(對象)으로 하여 석회요구량(石灰要求量) 결정방법(決定方法)간의 차이(差異)를 실험적(實驗的)으로 비교(比較), 검토(檢討)하였던 바 그 결과(結果)를 요약(要約)하면 다음과 같다. 1. 석회요구량(石灰要求量)을 결정(決定)하는 7가지 방법(方法)($CaCO_3$ incubation method, $BaCl_2$-TEA method, SMP-single buffer method, Double buffer method, Adams and Evans method, SMP-double buffer method, O. R. D. method)을 비교(比較)한 결과(結果) 방법(方法)간에 큰 차이(差異)가 있었다. 2. $CaCO_3$ incubation method를 기준(基準)으로 할 때 석회요구량(石灰要求量)은 $BaCl_2-TEA$ method가 가장 높았고, O.R.D. method 가 가장 적었으며, SMP-double buffer method가 강원도(江原道) 토양(土壤)에 비교적(比較的) 적합(適合)할 것으로 평가(評價)되었다. 3. 치환성(置換性) Al 함량(含量)의 100% 당량(當量)에 해당(該當)하는 $CaCO_3$를 가(加)하고 incubation한 경우 약(約) 70%의 중화율(中和率)을 나타냈다. 4. 활성(活性) Al 함량(含量)의 100% 당량(當量)에 해당(該當)하는 $CaCO_3$를 가(加)하고 incubation한 경우에는 약(約) 30%의 중화율(中和率)을 나타냈다. 5. 치환성(置換性) Al 및 활성(活性) Al 함량(含量)을 기준(基準)으로 한 석회요구량(石灰要求量)은 $CaCO_3$ incubation method에 비(比)해 적은 값을 나타냈다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.57-60
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• 2004

This paper presents multibit Sigma-Delta ADC using Leslie-Singh Structure to Improve nonlinearity of feedback loop. 4-bit flash ADC for multibit Quantization in Sigma Delta modulator offers the following advantages such as lower quantization noise, more accurate white-noise level and more stability over single quantization. For the feedback paths consisting of DAC, the DAC element should have a high matching requirement in order to maintain the linearity performance which can be obtained by the modulator with a multibit quantizer. Thus a Sigma-Delta ADC usually adds the dynamic element matching digital circuit within feedback loop. It occurs complexity of Sigma-Delta Circuit and increase of power dissipation. In this paper using the Leslie-Singh Structure for improving nonliearity of ADC. This structure operate at low oversampling ratio but is difficult to achieve high resolution. So in this paper propose improving loop filter for single-bit feedback multi-bit quantization Sigma-Delta ADC. It obtained 94.3dB signal to noise ratio over 615kHz bandwidth, and 62mW power dissipation at a sampling frequency of 19.6MHz. This Sigma Delta ADC is fabricated in 0.25um CMOS technology with 2.5V supply voltage.

• Corrosion Science and Technology
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• 제7권6호
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• pp.307-314
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• 2008

The influence of a moist atmosphere on $90^{\circ}$ domain switching under a sustained electric field, stress corrosion cracking of an indentation crack in water and an aggressive solution, and the relation between penetrating crack propagation and domain switching were studied using $BaTiO_3$ single crystal. The results indicate that enlarging the domain switching zone and crack propagation could be facilitated by a moist atmosphere or an aggressive solution due to the indentation residual stress. A moist atmosphere exerts remarkable influence upon the polarization of $BaTiO_3$ single crystal under a sustained electric field, and the surface energy of the c domain was much lower than that of the a domain. Domain switching ahead of a penetrating indentation crack tip was an essential requirement for crack propagation under constant stress.