• Journal of the Korean Society for Precision Engineering
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• v.13 no.9
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• pp.114-129
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• 1996

This paper describes the whole development phase for the underwater vehicle actuating system with high hydroload torque disturbance. This includes requirement analysis, system modeling, control algorithm design, real time implementation, test and performance evaluations. As for driving control algorithms, fuzzy logic, variable structure and PD(Proportional-Differential) algorithm were designed and implemented on board controller using a single chip microprocessor. Intel 8797. And test and performance evaluation is carried out both single test and wystem integration test. We could confirm the basic performance of actuating system through the single test and gereral developing work of any actuating systems was finished with a single performance test of actuating system without system integration test. But, we suggested that system integration test be needed. System integration test is carried out using G/C HILS(Guidance and Control Hardware-In-the -Loop Simulation) which is constituted flight motion simulator, load simulator, real time host computer and the related subsystems such as inertial navigation system, power supply system and Guidance and Control Computer etc.. The most important practical contribution of this paper is that full system characteristics such as minimal control effort, enhancement of guidance and autopilot performance by the actuating system using G/C HILS technique are investigated. Through full running G/C HILS, in spite of the passing to single tests, some control algorithm resulted in failure as to stability of full system and system time frame.

• The Journal of Advanced Prosthodontics
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• v.4 no.2
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• pp.76-83
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• 2012

PURPOSE. Zirconia has been used in clinical dentistry for approximately a decade, and there have been several reports regarding the clinical performance and survival rates of zirconia-based restorations. The aim of this article was to review the literatures published from 2000 to 2010 regarding the clinical performance and the causes of failure of zirconia fixed partial dentures (FPDs). MATERIALS AND METHODS. An electronic search of English peer-reviewed dental literatures was performed through PubMed to obtain all the clinical studies focused on the performance of the zirconia FPDs. The electronic search was supplemented by manual searching through the references of the selected articles for possible inclusion of some articles. Randomized controlled clinical trials, longitudinal prospective and retrospective cohort studies were the focuses of this review. Articles that did not focus on the restoration of teeth using zirconia-based restorations were excluded from this review. RESULTS. There have been three studies for the study of zirconia single crowns. The clinical outcome was satisfactory (acceptable) according to the CDA evaluation. There have been 14 studies for the study of zirconia FPDs. The survival rates of zirconia anterior and posterior FPDs ranged between 73.9% - 100% after 2 - 5 years. The causes of failure were veneer fracture, ceramic core fracture, abutment tooth fracture, secondary caries, and restoration dislodgment. CONCLUSION. The overall performance of zirconia FPDs was satisfactory according to either USPHS criteria or CDA evaluations. Fracture resistance of core and veneering ceramics, bonding between core and veneering materials, and marginal discrepancy of zirconia-based restorations were discussed as the causes of failure. Because of its repeated occurrence in many studies, future researches are essentially required to clarify this problem and to reduce the fracture incident.

• The KIPS Transactions:PartA
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• v.10A no.4
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• pp.285-294
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• 2003

The request scheduling algorithms being used for the cluster web servers are mostly in two categories : load-balancing and contents-based cache affinity The goal of the load-balancing algorithms is to balance the loads between real servers. On the other hand, contents-based scheduling algorithm exploits the cache affinity in a way that the same type of requests are to be directed to a dedicated real server allowing load imbalance. So the performance comparison of the two algorithms is necessary, nevertheless the related experiment results are not much suggested. In this paper, performance evaluations have been done to compare the performance of the two scheduling algorithms. To accomplish this, we first implement a linux cluster web server, and then present the performance measurement results. The main contribution of this paper is to help the cluster web server administrators to select an algorithm fitting in with their circumstances from the two algorithms.

• KIEAE Journal
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• v.10 no.4
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• pp.19-28
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• 2010

As design tools, building performance certification systems can be applied to provide adequate guidelines on design process to create environment-friendly buildings. Domestic certification systems of residential building took effect by doing supply to designers and contractors from affiliated organization of governments in the early 2000s. As a result, Building Energy Rating System, Apartment Performance Rating System, Green Homes and other means to promote green designs have been operated. International trends of applying certification systems were started in the early 1990s as forms of LEED in USGBC, BREEAM in BRE, GBTool Canada. These systems aim to evaluate building performance in line with the Climatic Change Convention and realize sustainable building design. In 2009, residential buildings accounted for the largest portion of the internal real estate market with 67.9 percent according to the National Statistical Office data. And for 18 years since 1991, apartments among constructed residential buildings have ranked top taking up 77.7% as of 2009. Apartment performance evaluations accordingly are to promote to constitution of improving tenant quality of life, the residential environment and saving energy and resources in the internal building market. The purpose of this study is to compare and analyze valuation bases of each sector in evaluation systems of residential buildings at home and abroad to upgrade current systems through reflecting the characteristics of residential buildings. Implementation of this study basically include comparison of valuation bases and partial analysis on properties of rating systems to suggest requisites for improvement in building performance certification.

• Therapeutic Science for Rehabilitation
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• v.9 no.1
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• pp.45-55
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• 2020

Objective : The purpose of this study was to investigate the effects of visual perception on driving performance and the importance of visual training for improving driving performance in patients with stroke. Methods : The evaluations, using MVPT(Motor-free Visual Perception Test), TMT A&B(Trail Making Test A & B), UFOV(Useful Field Of View test), and a driving simulator, were carried out with patients in department of physical medicine and rehabilitation in a rehabilitation hospital from October 2014 to November 2014. Results : Driving performance was related to the ability of various visual perceptions of patients with stroke, and the highest correlation was found in the UFOV subtest 2, TMT B, and MVPT. The results of discriminant analysis indicated a sensitivity of 100.0%, specificity of 80.0%, and predicted the results of the driving simulator with 89.5% accuracy. Conclusion : This study found that visual-perception skills influence driving performance and suggested the importance of visual-perception skill training for driving.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.5
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• pp.72-81
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• 2018

Fireproof structures using concrete, built-up panels and dry walls are usually used in walls inside fire compartments. However, demand for glass walls is emerging due to increase in interest in visibility and external appearance. In this study on steel fire resistance walls using insulation glass, fire resistance tests and performance evaluations were conducted on 60 minute fire resistance walls and exterior walls which could be applied to interior fire compartments and 90 minute fire resistance walls which could be applied to curtain walls. According to the tests, the specimens satisfied the required fire resistance performance. The finite element analysis was conducted after the tests to evaluate the fire resistance performance of the glass walls. The analysis results showed that the preliminary evaluation of fire resistance performance would be feasible.

• Korean Journal of Construction Engineering and Management
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• v.11 no.4
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• pp.89-99
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• 2010

In Korea, much effort is being made to introduce asset management for improved efficiency and lower costs. Many researches related to asset management are ongoing, but asset management for public facilities is still in its early development stage in many countries including Korea. It is necessary to continuously improve and complement asset management for its successful execution. Thus, there should be a series of performance measurements and evaluations to perceive the current state of asset management in Korea from which to set future goals. In developed countries including Australia, asset management performance is measured using various methods for diverse purposes. The Korea Institute of Construction Technology has recently launched a study entitled Development of an Asset Management System for Public Facilities (KTAM-40) to change the country’s existing countermeasure-type maintenance system into a preliminary maintenance system and to suggest asset management evaluation parameters. this study aims to develop performance indicators of effective asset management with respect to its utility, which shall include all matters that are important for the efficient measurement of the management of domestic public facilities using the BSC (Balanced Score Card) method, and AHP method.

• Journal of the Korean Society for Railway
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• v.17 no.2
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• pp.106-113
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• 2014

In this study, a practical evaluation technique to detect the deterioration of railroad lines by means of train performance and track geometry measures is suggested. A train that has a specific performance and is running the straight line can make minimum travel time (ideal time). But the actual travel time will be increased by the track geometry and various speed limitations. By comparing these travel times, we can easily define the degree of line deterioration. This method does not require complex vehicle performance measures and/or specifications that exceed those of typical Train Performance Simulations (TPS). For this reason, ease of use is ensured and the results are similar to those obtained by running a TPS for practical evaluations.

• KIISE Transactions on Computing Practices
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• v.21 no.1
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• pp.52-57
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• 2015

In this paper, we analyze the performance of the TRIM commands on various SSDs and, based on our analysis results, we enhance the performance of these TRIM commands in the Ext4 file system. We observed that the performance of the TRIM commands improves as the size of the LBA-range increases, the sector number is aligned and continuous or more LBA-ranges are notified via a single TRIM command. However, although the performance is better when multiple LBA-ranges are informed by a single TRIM command, the Ext4 file system issues a single TRIM command for every LBA-range. In this paper, we modify the Ext4 file system to convey at most 64 LBA-ranges per TRIM command. Evaluations through Filebench show that the performance of file deletion operations is improved by up to 35%.

• Korean Journal of Social Welfare
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• v.44
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• pp.7-35
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• 2001

Little empirical study has been conducted concerning board function effectiveness and organizational performance in nonprofit nongovernmental human service organizations in Korea. Using the evaluations of 107 board members and 17 executive directors in Korean Community Chest and 16 regional community chests, this study attempted to examine the level of board function effectiveness and its relationship with organizational performance in these community chests. This study used board function scale developed by Holland and Jackson (1998) to measure board function effectiveness in the following 6 dimensions: contextual dimension: educational dimension: interpersonal dimension: analytical dimension: political dimension: and strategic dimension. This study showed that using 4 points scale, mean of overall board function effectiveness evaluated by board members is 2.62 and mean of overall board function effectiveness evaluated by executive directors is 2.73. That is, it showed that means of overall board function effectiveness are located in the middle point between negative evaluation and positive evaluation. On the other hand, using parametric correlation analysis method, it was found that in these community chests the association between board function effectiveness and organizational performance measured by fund-raising growth rate in $1999{\sim}2000\;and\;1998{\sim}2000$ is very weak and statistically nonsignificant. This study also revealed that using nonparametric correlation analysis method, the association between consensus level in evaluation by board members and executive directors about board function effectiveness, and organizational performance is still very weak and statistically nonsignificant. Finally, this study discussed the direction of future research in board function effectiveness and its relationship with organizational performance and the areas of board management that requires substantial efforts for promoting effectiveness of nonprofit human service organizations in Korea.