• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• autumn
• /
• pp.88-95
• /
• 2001

To convert the construction industry from 'the high cost, the low efficiency' to 'the low cost, the high efficiency and value-added industry' and to enhance the performance and quality of products while reducing the cost, the related law and guideline were established and promulgated, which regulate that value engineering workshop during the preliminary design and the detail design stage should be a mandatory process. But VE practitioners are still confusing in choosing the proper value engineering process, because processes those are described in the various references use the different terms, steps and activities, even though they have their own specific characteristics. To resolve these confusions, the existing steps and activities of three kinds of the literature, four kinds of the organization's policy and other four kinds of study examples relating to the design VE were examined. And then, the differences and expecting problems were extracted through the comparison and analysis of those materials. After that, VE specialists' opinion through the questionnaire survey were grasped. Based on those studies the improved design VE Job Plan and activity statements were suggested.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.7B
• /
• pp.567-574
• /
• 2008

In this paper, we propose an optimal coverage extension scheme in the OFDMA based mobile multi-hop relay system. First, we propose an optimal frequency and time assignment scheme for maximizing system throughput and analyze the frame efficiency of schemes. Then, under the given BS capacity, we find the maximum number of relay hops that can be used to estimate the maximum coverage area of a BS in a multi-hop relay system. Analytical results show that the proposed scheme is efficient in coverage extension and throughput maximization in OFDMA based multi-hop relay system. Our work may be a rough guideline to control the parameters for multi-hop relay system optimization.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.245.2-245.2
• /
• 2013

Solution processed organic photovoltaic devices have relatively less attention compared to polymer photovoltaic devices even though they have high possibility to be developed because they have both advantages of polymer and organic, such as solution processable, no synthetic batch dependence of photovoltaic performance, high purity and high charge carrier mobility as well as relatively high efficiency (~7%). In addition, solution processed organic photovoltaic devices have an advantage of easiness to study the relationship between the molecular structure and photovoltaic performance due to its simple structure. In this work, five isoindigo based low band gap donor-acceptor-donor (D-A-D) small molecules with different electron donating strength were synthesized for investigating the relationship between the molecular structure and photovoltaic performance, especially, investigating the effects of different electron donating effect of donor group in isoindigo backbone to photovoltaic device performance. The variation of electron donating strength of donor group strongly affected the optical, thermal, electrochemical and photovoltaic device performances of isoindigo organic materials. The highest power conversion efficiency of ~3.2% was realized in bulk heterojuction photovoltaic device consisted of the ID3T as donor and PC70BM as acceptor. This work demonstrates the great potential of isoindigo moieties as electron deficient units as well as guideline for synthesis of donor-acceptor-donor (D-A-D) small molecules for realizing highly efficient solution processed organic photovoltaic devices.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.8 no.9
• /
• pp.2967-2981
• /
• 2014

Device-to-Device (D2D) communication is a technology component for long-term evolution-advanced (LTE-A). In D2D communication, users in close proximity to each other can communicate directly without going through a base station; such direct communication can improve spectral efficiency. Although D2D communication brings improvement in spectral efficiency, it also causes interference to the cellular network as a result of spectrum sharing. In particularly, D2D communication can generate interference for each D2D pair when the common wireless medium in a co-located limited area is accessed. Even though the interference management for between the D2D pair and cellular networks has been proposed, the interference reducing methods have still not been fully studied for the D2D pairs. In this paper, we investigate the problem of D2D pair coexistence in which interference is considered between D2D pairs. Using a signal to interference model for a target D2D pair, we provide an analysis of the aggregated throughput of a dense D2D network. For a target D2D pair, we assume that the desired signal and interference signals obey multipath fading and shadow fading. Through analysis, we demonstrate the effect of cluster size such as the number of D2D pairs and the size of the considered area on the network performance. The analytical results are compared with computer simulations. Our work can be used for a rough guideline for controlling the system throughput in a dense D2D network environment.

• Journal of Korea Multimedia Society
• /
• v.16 no.3
• /
• pp.399-409
• /
• 2013

The development of IT has led to increase the business's dependence on IT and the interests of enterprises on IT governance. Also, more enterprises have adopted managed services to save operating costs in IT departments and to maximize their business efficiency. However, until recently, there are very few academic as well as practical researches regarding managed services, IT service effectiveness, IT governance and their interrelations. This study analyzes the effects of managed services on IT governance based on the IT-BSC (Balanced Scorecard) model. Using the expert FGI (Focus Group Interview) and survey, the research results present that managed services have the most significant effect on the user-oriented and the operational efficiency in enterprises. Also, managed services through the business process standardization can improve the IT governance more effectively. This study will be a relevant guideline for enterprises that will adopt managed services.

• Land and Housing Review
• /
• v.13 no.3
• /
• pp.115-123
• /
• 2022

Recently, the adoption of BIM technology in domestic civil engineering projects has continually increased both in its numbers and scope. However, the BIM model was developed and used after the 2D design was developed instead of creating the BIM model from the conceptual design phase. BIM must be used throughout every phase of design and construction to use BIM for its original purpose. However, if BIM application is applied in heavy civil projects without a step-by-step guideline, it can confuse the market and face industry resistance to using BIM. Therefore, BIM is currently being used step by step in the civil engineering field by using BIM as a conversion design. However, the BIM conversion design method, currently being performed in the Preliminary design stage, has many difficulties due to low work efficiency. This paper analyzes the existing process of converting a 2D design into a 3D BIM model while addressing the issues related to its low work efficiency. To this end, a novel approach to 2D to BIM conversion for the design development stage is proposed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.36 no.2
• /
• pp.136-142
• /
• 2023

In the past, the efficiency of solar cells had been increased in order to increase the efficiency of solar modules. However, in recent years, in order to increase output in the solar industry and market, the competitiveness of solar cells based on large-area solar cells and multi-bus bar has been increasing. Multi-busbar solar module is a technology to reduce power loss by increasing the number and width of the front busbar of the solar cell and reducing the current value delivered by the busbar by half through half-cutting. In the case of the existing M2 (156.75×156.75 mm²) solar cell, even with a half-cut, power loss could be sufficiently reduced, but as the area of the solar cell is enlarged to more than M6 (166×166 mm²), the need for more divisions emerged. This affected not only solar cells but also inverters required for module array configuration. Therefore, in this study, the electrical characteristics of a large-area solar cell and after division were extracted using Griddler simulation. The output characteristics of the module were predicted by applying the solar cell parameters after division to PSPice, and a guideline for the large-area solar module design was presented according to the number of divisions of the large-area solar cell.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.06a
• /
• pp.236.1-236.1
• /
• 2010

Due to global warming, the need to secure an alternative resource has become more important nationally. Due to the high tidal range of up to 9.7m on the west coast of Korea, numerous tidal current projects are being planned and constructed. The rotor, which initially converts the energy, is a very important component because it affects the efficiency of the entire system, and its performance is determined by various design variables. In this paper, a design guideline of current generating HAT rotor and acceptable field rotor in offshore environment is proposed. To design HAT rotor model, wind mill rotor design principles and turbine theories were applied based on a field HAT rotor experimental data. To verify the compatibility of the rotor design method and to analyze the properties of design factors, 3D CFD model was designed and analysed by ANSYS CFX. The analysis results and findings are summarized in the paper.

• Phonetics and Speech Sciences
• /
• v.4 no.3
• /
• pp.143-149
• /
• 2012

The purpose of this study is to investigate the speech rate of an esophageal speech group that is capable of vocalization after surgery. The subjects in this experiment were 10 male esophageal speakers and 10 male laryngeal speakers. Each group read a reading passage that was recorded by a DAT recorder (Rolando, EDIROL R-09). These records were analyzed by using CSL (Computerized Speech Lab, model 4150). The results were as follows: (1) the overall speech rate of esophageal speech was 2.50 SPS (syllable per second) while the overall speech rate of laryngeal speech was 4.23 SPS. (2) The articulatory rate of esophageal speech was 3.14 SPS (syllable per second) while the articulatory rate of laryngeal speech was 4.75 SPS. Speech rates as well as articulatory rates of esophageal speech were significantly lower than laryngeal speech. These differences between the two groups may be due to reduced efficiency of airflows across the pharyngeal-esophageal segment for esophageal speakers when compared to airflow through the glottis for laryngeal speakers. These results would provide a guideline in speech rates for esophageal speakers in clinical settings.

• Progress in Medical Physics
• /
• v.1 no.1
• /
• pp.23-29
• /
• 1990

In order to explane the stereotactic procedure, the three steps of the procedure (target localization, dose planning, and radiation treatment) must be examined separately. The ultimate accuracy of the full procedure is dependent on each of these steps and on the consistancy of the approach The concern in this article was about dose planning, which is a important factor to the success of radiation treatment. The major factor in dose planning is a dosimetry system to evaluate the dose delivered to the target and normal tissues in the patient, while it generates an optimal dose distribution that will satisfy a set of clinical criteria for the patient. A three-dimensional treatment planning program is a prerequisite for treatment plan optimization. It must cover 3-D methods for representing the patient, the dose distributions, and beam settings. The major problems and possible modelings about 3-D factors and optimization technique were discussed to simplify and solve the problems associatied with 3-D optimization, with relative ease and efficiency. These modification can simplify the optimization problem while saving time, and can be used to develop reference dose planning system to prepare standard guideline for the selection of optimum beam parameters, such as the target position, collimator size, arc spacing, the variation in arc length and weight. The method yields good results which can then be simulated and tailored to the individual case. The procedure needed for dose planning in stereotactic radiosurgery is shown in figure 1.