• Journal of the Korea Institute of Building Construction
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• v.13 no.3
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• pp.263-271
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• 2013

Change orders have been widespread in both the private and public construction sectors. In particular, in the case of G2B (Government to Business) contracts, adjustment of contract price and/or schedule extension is a frequent occurrence due to change orders. To uncover the causes of change orders and suggest an appropriate strategy, this study analyzed 296 cases of change orders in military facility construction projects from 2008 to 2010. The analysis revealed that the major causes of change orders are users' additional requirements (28.38%), a change of finishing materials (23.99%), and change of footing type (17.57%), in that order. Building on the results of this analysis, the authors suggest plans for practical improvements. Specific recommendations include 1) reflect user requirements at the early stage, 2) minimize the use of additional budget due to change orders, and 3) reduce the process and time for contract amendment, among others. The results of this study may provide significant implications to those involved in military construction projects, particularly project owners (i.e., the Ministry of Defense) and contractors.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.4
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• pp.9-17
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• 2017

In these days, MEMS (micro-electro-mechanical system) devices become the crucial sensor components in mobile devices, automobiles and several electronic consumer products. For MEMS devices, the packaging determines the performance, reliability, long-term stability and the total cost of the MEMS devices. Therefore, the packaging technology becomes a key issue for successful commercialization of MEMS devices. As the IoT and wearable devices are emerged as a future technology, the importance of the MEMS sensor keeps increasing. However, MEMS devices should meet several requirements such as ultra-miniaturization, low-power, low-cost as well as high performances and reliability. To meet those requirements, several innovative technologies are under development such as integration of MEMS and IC chip, TSV(through-silicon-via) technology and CMOS compatible MEMS fabrication. It is clear that MEMS packaging will be key technology in future MEMS. In this paper, we reviewed the recent development trends of the MEMS packaging. In particular, we discussed and reviewed the recent technology trends of the MEMS bonding technology, such as low temperature bonding, eutectic bonding and thermo-compression bonding.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.11
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• pp.1806-1812
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• 2016

We propose an interior permanent magnet syhchronous motor (IPMSM) with arc-shape ferrite permanent magnets (PMs) as a substitute for the rare-earth permanent magnet, and determine its optimal design through parametric study. First, we use 2D finite element analysis to analyze 4-poles and 6-slots initial model according to performance requirements and design parameters. The current angle of the maximum average torque considered in the analysis is different compared with the current angle of the minimum torque ripple. Thus, the parametric study for optimal rotor design is performed by varying the thickness and the offset radius of the PMs according to current angle. In particular, a narrow bridge is required in conventional IPMSM for reducing flux leakage; however, the increase in cogging torque in the analysis model saturates the narrow bridge (large offset radius). Therefore, we suggest an appropriate shape considering limiting conditions such as DC link voltage, average torque, torque ripple, and cogging torque taking into account performance requirements.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.6
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• pp.908-913
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• 2007

Concentrations of major elements in forages were determined in relation to ruminant requirements at a livestock experimental station in Leiah district, Punjab-Pakistan using mapping techniques. The study investigated the influence of sampling periods and pasture types on the concentrations of calcium, magnesium, potassium, and sodium in forages. The implications of these forages for nutrition of ruminants were assessed for the livestock population at that particular experimental station, which are supported by the farm pastures. Within the farm, variations in the element status of the forages were related to soil pasture types. A tentative assessment of the mineral status of available forages at this farm for different pastures using guidelines developed for domestic animals indicated deficiencies of only Na, but forages contained adequate Ca, Mg, and K levels required for grazing ruminants. The concentrations of Na in the forage reserves indicated that the potential supply of this element to plants was limited from the soil to plants and from plants to the animals grazing them. Soil minerals were not measured in this study. The potential use of fertilizers, as pasture amendment as well as supplementation of ruminants, with a specifically tailored mineral mixture is important to livestock producers and environmentalists as well, because their use may improve forage nutritive value and in turn meet requirements of animals.

• Journal of KIBIM
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• v.7 no.4
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• pp.21-30
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• 2017

Due to the rapidly aging population, the death rate of elderly people by safety accidents has been increasing. In particular, precautions are needed for falls prevention because they either directly or indirectly cause death. In the case of elderly people, most of the fall accidents occur in dense residential areas, and particularly, the staircase poses a risk of falling. Therefore, a safety assessment should be performed from the design phase. However, in general, staircases are designed using existing stair data or only aims to satisfy the installation criteria. Laws and regulations only define minimum requirements for safety, so it is not possible to prevent fall accidents even if they satisfy the requirements. Therefore, this study proposes a simulation-based method for evaluating the safety of staircases. The behavioral characteristics of the elderly are implemented to an virtual user in a virtual space including staircases, and fall accidents are evaluated by the evaluation logic related to the behavioral characteristics. The result shows that the safety of staircases can be preevaluated and reflected on the design to reduce the possibility of fall accidents of the elderly.

• Journal of Engineering Education Research
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• v.17 no.3
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• pp.42-50
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• 2014

Since internships or field training provide students with opportunities to choose skills, business interests and aptitudes in the actual workplace, their significant role in higher education has been gradually emphasized. In particular, engineering students gain increased adaptability to the industry, enhance their research abilities and acquire field-based expertise through internships or field training. However, effective operation of such internships or field training often pose various limitations. In this regard, the development of a system to manage students properly is urgently required for the effective operation of internships or field training. Systematic management of a series of related information ranging from a survey on the demand for internships or field training, planning, development and operation of pre-training programs, student guidance through information sharing between universities and businesses, data-gathering with regard to students' difficulties and their requirements, to prospects for future employment. In line with these requirements, this study attempts to present a modeling scheme for the development of a student management system for use in internships or field training. Towards this end, a questionnaire survey is conducted with engineering professors, students and graduates, along with a review of related literature to identify the needs for system development. Based on the results, a model of the system will be proposed through expert consultation.

• Nuclear Engineering and Technology
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• v.28 no.6
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• pp.594-601
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• 1996

To assure quality of safety critical software, software should be developed in accordance with software development procedures and rigorous software verification and validation should be performed. Software verification is the formal act of reviewing, testing or checking, and documenting whether software components comply with the specified requirements for a particular stage of the development phase [1]. New software verification methodology was developed and was applied to the Shutdown System No. 1 and 2(SDS1,2) for Wolsong 2, 3 and 4 nuclear power plants by Korea Atomic Energy Research Institute(KAERI) and Atomic Energy of Canada Limited(AECL) in order to satisfy new regulation requirements of Atomic Energy Control Board(AECB). Software verification methodology applied to SDS1 for Wolsong 2, 3 and 4 project will be described in this paper. Some errors were found by this methodology during the software development for SDS1 and were corrected by software designer. Output from Wolsong 2, 3 and 4 project have demonstrated that the use of this methodology results in a high quality, cost-effective product.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.5
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• pp.132-139
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• 2013

Liquid-propellant rocket engines are widely used all over the world, thanks to their high performances thrust, in particular high thrust-to-weight ratio. The sucess rate of the launching of the liquid propulsion is similar to the solid one even though it has more complex mechanical system. In general, liquid propulsion is seemed as a mature technology, the requirements of a renewed interest for space exploration has led to the development of a family of new engines, with more design margins, simpler to use and to produce associated with a wide variety of thrust and life requirements.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.843-847
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• 2005

The development of distributed application in the standardized CORBA(Common Object Request Broker Architecture) environments reduces the developing time and maintaining cost of the systems. Because of these advantages, the development of application is being progressed in the several fields using the CORBA environments. The programmers in the CORBA environments usually develop the application programs using the CORBA IDL(Interface Definition Language). The IDL files are compiled by IDL compiler and translated into the stubs and skeleton codes which are mapped onto particular target language. The stubs produced by IDL compilers processes the marshaling a data into message buffer. Before a stub can marshal a data into its message buffer, the stub must ensure that the buffer has at least enough free space to contain the encoded representation of the data. But, the stubs produced by typical IDL compilers check the amount of free buffer space before every atomic data is marshaled, and if necessary, expand the message buffer. These repeated tests are wasteful and incidence of overheads, especially if the marshal buffer space must be continually expanded. Thus, the performance of the application program may be poor. In this paper, we suggest the way that the stub code is maintain the enough free space before marshaling the data into message buffer. This methods were analyzes the overall storage requirements of every message that will be exchanged between client and server. For these analysis, in the Front End of compiler has maintain the information that the storage requirements and alignment constraints for data types. Thus, stub code is optimized and the performance of application program is increased.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.3
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• pp.11-22
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• 2012

GIS have expanded the use-range to the various application area with the advantage of interface environment, the various geographical operation. topological analysis by the friendly user. Early GIS software was developed as monolithic tool in which all functions packed in the same software. But, these GIS software have the problems of the high cost of constructing system, closely related system architecture and the reusability. And there is a lack of interoperability between them because most of them have their own unique data format according to their practical application fields. So Component is a unit that it is cohesive software package which is able to be developed and arranged independently and connected with another component for necessary system composition. In this paper, we analyze the requirements for component design and component specifications based on the extracted components. Commonly used to extract components from the requirements of the GPS component-based development process is presented. These components extracted by the process can be used to assemble components only. In particular, applications for developers to add features specific case without affecting the other components that can be modify the component.