• 산업경영시스템학회지
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• 제28권2호
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• pp.94-100
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• 2005

This paper presents the application of integrated mathematical programming approach for the design of cellular manufacturing. The proposed approach is carried out in two phases The first phase concerning exceptional elements(EEs) in cell formation and the second phase facilities layout design. This paper considers the total costs of three important costs for (1) intercellular transfer (2) machine duplication and (3) subcontracting. One of Important issue is the calculation of the number of machines considering the maximum utilization of machines and the available capacity of a machines that can be transferred between cells. Facilities layout design is considered to reflect the real field data taking in to account the operational sequence of the parts to be manufactured. The model is formulated as mixed integer programming that is employed to find the optimal solution.

• Journal of Information Technology Applications and Management
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• 제10권3호
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• pp.1-22
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• 2003

P2P systems have been studied by many researchers in universities and commercial firms in recent years. In this study. we design and implement a system that makes UP for shortcomings of currently available P2P systems. Gnutella and Napster. The study also includes an efficiency analysis scheme conducted through a series of experimental data. The data sharing system of the study demonstrated duality of roles(client, service) of peers. But, their roles were separated from the existing client-server systems. Also, the study implements mechanism that shows the redundancy of data to communicate efficiently among peers for transferring data. The results of performance measure of the system shows that the amount of information shared by peers increases as the amount of peers increases but with no significant increase in response time. This constant response time is far more stable and faster than current file sharing systems. such as Gnutella and Napster. Business applications such as knowledge management, enterprise information portal management and transfer of data are done by use of supercomputers. They need to extend their systems to equip with more capacity and throughput as the number of clients increases. Moreover, they will face with more complicated problems if integration with new systems exists. If this JDSS is introduced to these business applications. it would easily augment scalability of the system with high performance at less expense.

• 한국측량학회지
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• 제17권2호
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• pp.145-152
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• 1999

제트추진연구소(JPL : Jet Propulsion Laboratory)에서는 매일 전세계에 분포된 정밀 측지용 GPS수신기의 광역망으로 부터 관측자료를 수집하고 분석하여 정밀한 GPS transmitter parameters (위성의 위치력 및 시계 보정값)를 산정하고 있으며 이를 이용한 자동화된 GPS 자료 해석 서비스를 제공하고 있다. 본 연구에서는 한측점의 2주파 GPS수신기로부터 획득한 위성관측자료를 E-mail 및 ftp(file transfer protocol)로 JPL의 주컴퓨터에 연결시켜 JPL의 정밀 GPS transmitter parameters 및 Gipsy/Oasis-II (GOA-II) s/w를 활용한 정밀절대측위(PPP : Precise Point Positioning)기법의 정밀도를 분석하고 PPP에 의한 GPS기준점 좌표의 산정 방안을 검토한 것이다. 검토결과, X, Y, Z 직교좌표계에서 수 cm급의 위치결정이 가능하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.49-56
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• 2005

The negative skin friction on piles, which are installed in currently consolidating soft deposits, creates significant problems on the stability of pile foundations. This study investigated whether or not the pile foundation designs were appropriate in soft deposits with large amount of consolidation settlement. The final settlements of the grounds along the pile depth were estimated by the soil parameters obtained from the laboratory tests and by the field-measured settlement curves, if they were available. The displacement of the piles along the pile depth was estimated by both the load transfer method and the numerical method. Both methods gave similar locations of neutral points and magnitudes of the maximum axial forces. The movements of the ground and the piles were compared to calculate the down drag acting on piles. For the piles whose bearing capacities were less than the design loads including the down drag, slip layer coatings and/or incrementing of the penetration depth into the bearing stratum were proposed to improve the piles capacities.

• Neonatal Medicine
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• 제16권2호
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• pp.110-120
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• 2009

Mimicking fetal nutrition is the goal of early paretneral nutrition (PN) in very low birth weight infants, however the limited metabolic capacity of immature organs raises concern about the toxicity of metabolites to the developing brain. Starting parenteral amino acids from the first day of life, with a rate of 1.0 to 1.5 g/kg/day, is generally recommended to prevent endogenous protein breakdown by maintaining a positive nitrogen balance. A greater of amino acid infusion rate in the range of the fetal transfer rate (3.5-4.0 g/kg/day) is well tolerated during the early days after birth in VLBWI, however the influence on growth and long-term neurodevelopmental outcome remains unknown. Limited data are available from controlled trials regarding the effects of early supplementation with lipid emulsions on neonatal morbidity. Considering the role of long-chain polyunsaturated fatty acids in the neurodevelopment, the choice of an optimal lipid emulsion should be based on the quality as well as the quantity of the lipid contents. Little is known about the clinical benefit of higher rates of glucose infusion by permitting high serum glucose level or co-administration with insulin.

• 한국산업정보학회:학술대회논문집
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• 한국산업정보학회 2002년도 춘계학술대회 논문집
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• pp.177-184
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• 2002

디스크의 용량이 커지고 정보화 시대와 더불어서 데이터가 폭발적으로 증가하게 되었다. 또한 현재 이 데이터들에 대한 정보 교환이나 접근은 시간과 공간에 관계없이 항상 이루어져야 하는 상황에 있다. 본 논문에서는 365일 지속적으로 운용을 해야만 하는 서버에서 데이터를 효율적으로 백업하기 위한 시스템 사항 및 설계를 소개한다. 백업은 크게 논리적인 백업과 물리적인 백업으로 구분할 수 있는데 일반적으로 물리적(블록단위) 백업을 성능 면에서 우수하지만 구현상의 어려움이 있다. 우선 지금까지의 백업의 방식이나 방법에 대해서 간략히 언급을 하고 온라인(on-line) 백업을 수행하기 위한 기술적인 사항에 대해서 알아본 다음, 백업을 하기 위한 시스템 설계에 대해서 소개하고자 한다. 본 백업 시스템은 데이터 전송의 효율을 놀이기 위해서 SCSI-Protocol을 지원한다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.540-545
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• 2007

The performance of microturbine CHP system equipped with an absorption chiller was analyzed by modelling of a microturbine and an absorption chiller. The microturbine having recuperator was simulated by the Brayton cycle model. The mass flow rate and available heat energy of the exhaust gas from the microtubune were simulated, and this results were utilized as input values for the generator of the absorption chiller. The absorption chiller is a single-effect air cooled type having solution heat exchanger. When heat input to the generator increased, the heat transfer rate and UA of the heat exchangers of the absorption chiller proportionally increased. Besides, the COP of the absorption chiller increased with increase of the heat input to the generator under the sufficient size of the evaporator condition. When the capacity of the CHP system increased from 30 to 60 kW, the mass flow rate of the LiBr for the absorption chiller increased by two times, and UA values for evaporator and condenser were increased by 3.9 and 3.4 times, respectively, under the same COP condition.

• Structural Engineering and Mechanics
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• 제71권3호
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• pp.233-244
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• 2019

Steel jacketing technique is a retrofitting method often employed for static and seismic strengthening of existing reinforced concrete columns. When no continuity is given to angle chords as they cross the floor, the jacket is considered "indirectly loaded", which means that the load acting on the column is transferred partially to the external jacket through interface shear stresses. The evaluation of load transfer mechanism between core and jacket is not straightforward to be modeled, due to the absence of knowledge of a proper constitutive law of the concrete-to-steel interface and to the difficulties in taking into account the mechanical nonlinearities of materials. This paper presents an incremental analytical/numerical approach for evaluating the compressive response of RC columns strengthened with indirectly loaded jackets. The approach allows calculating shear stresses at the interface between core and jacket and predicting the axial capacity of retrofitted columns. A proper constitutive law is proposed for modelling the interaction between the steel and the concrete. Based on plasticity rules and the non-linear behaviour of materials, the column is divided into portions. After a detailed parametric analysis, comparisons are finally made by theoretical predictions and experimental results available in the literature, showing a good agreement.

• Steel and Composite Structures
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• 제31권4호
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• pp.341-359
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• 2019

Non-monolithic concrete structural connections are commonly used both in new constructions and retrofitted structures where anchors are used for connections. Often, flaws are present in anchor system due to poor workmanship and deterioration; and methods available to check the quality of the composite system afterward are very limited. In case of presence of flaw, load transfer mechanism inside the anchor system is severely disturbed, and the load carrying capacity drops drastically. This raises the question of safety of the entire structural system. The present study proposes a wave propagation technique to assess the integrity of the anchor system. A chemical anchor (embedded in concrete) composite system comprising of three materials viz., steel (anchor), polymer (adhesive) and concrete (base) is considered for carrying out the wave propagation studies. Piezoelectric transducers (PZTs) affixed to the anchor head is used for actuation and the PZTs affixed to the surrounding concrete surface of the concrete-anchor system are used for sensing the propagated wave through the anchor interface to concrete. Experimentally validated finite element model is used to investigate three types of composite chemical anchor systems. Studies on the influence of geometry, material properties of the medium and their distribution, and the flaw types on the wave signals are carried out. Temporal energy of through time domain differentiation is found as a promising technique for identifying the flaws in the multi-layered composite system. The present study shows a unique procedure for monitoring of inaccessible but crucial locations of structures by using wave signals without baseline information.

• Steel and Composite Structures
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• 제43권6호
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• pp.785-796
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• 2022

Concrete-encased steel (CES) beam, in which structural steel is encased in a reinforced concrete (RC) section, is widely applied in high-rise buildings as transfer beams due to its high load-carrying capacity, great stiffness, and good durability. However, these CES beams are prone to shear failure because of the low shear span-to-depth ratio and the heavy load. Due to the high load-carrying capacity and the brittle failure process of the shear failure, the accurate strength prediction of CES beams significantly influences the assessment of structural safety. In current design codes, design formulas for predicting the shear strength of CES beams are based on the so-called "superposition method". This method indicates that the shear strength of CES beams can be obtained by superposing the shear strengths of the RC part and the steel shape. Nevertheless, in some cases, this method yields errors on the unsafe side because the shear strengths of these two parts cannot be achieved simultaneously. This paper clarifies the conditions at which the superposition method does not hold true, and the shear strength of CES beams is investigated using a compatible truss-arch model. Considering the deformation compatibility between the steel shape and the RC part, the method to obtain the shear strength of CES beams is proposed. Finally, the proposed model is compared with other calculation methods from codes AISC 360 (USA, North America), Eurocode 4 (Europe), YB 9082 (China, Asia), JGJ 138 (China, Asia), and AS/NZS 2327 (Australia/New Zealand, Oceania) using the available test data consisting of 45 CES beams. The results indicate that the proposed model can predict the shear strength of CES beams with sufficient accuracy and safety. Without considering the deformation compatibility, the calculation methods from the codes AISC 360, Eurocode 4, YB 9082, JGJ 138, and AS/NZS 2327 lead to excessively conservative or unsafe predictions.