• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.5
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• pp.805-815
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• 2001

Glaucoma is an eye disease which is caused by abnormal high IOP (Intra Ocular Pressure). High IOP is caused by the aqueous humor which is produced consistently but not drained due to malfunction of the trabecular system which has a role of draining the aqueous humor into the venous system. Currently, there are three methods to treat glaucoma-using medicines, surgical operation, and using implant device. The first and second methods are not long acting, so the use of implants is increasing in these days in order to drain out the aqueous humor compulsory. However, though conventional implants have a capability of pressure regulation, they cannot maintain IOPs desired for different patients, and too much aqueous humor are usually drained, to cause hypotony. To solve these problems, it is needed to develop a new implant which is capable of controling the IOP actively and copes with personal difference of patients. An active glaucoma implant consists of the valve actuator, pressure sensor, controller, and power supply. In this paper, firstly, we make an analysis of the operation of a conventional implant using a bond graph and show defects and limitations of the conventional valve analytically. Secondly, we design and analyze a valve actuator considering actuation principles, resistance elements, control methods, and energy sources focused on power saving problem. Finally, using simulations the possibility of the proposed valve actuator is investigated.

• Journal of Korea Spatial Information System Society
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• v.2 no.2 s.4
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• pp.49-58
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• 2000

With the growing realization that the GIS data management becomes important more than ever, a great deal of the spatial data is being digitalized through various GIS projects, such as NGIS project. However, the integrated search and analysis for GIS data are highly constrained by the databases being heterogeneous and distributed among organizations. This paper is to introduce the system developed to solve the problem of interoperability in the heterogeneous and distributed databases environment. The system architecture is presented which is composed of spatial data servers, nodes, and a gateway. Also, the paper provides the implementation details of the client application to access and analyze the distributed and heterogeneous spatial data with the standardized interface. Finally, based on the technical architecture, the korea spatial data infrastructure is explained.

• Journal of Educational Research in Mathematics
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• v.21 no.4
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• pp.379-398
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• 2011

In learning environment at mathematics education, prove and refute are essential abilities to demonstrate whether and why a statement is true or false. Learning proofs and counter examples within the domain of limit of sequence is important because preservice teacher encounter limit of sequence in many mathematics courses. Recently, a number of studies have showed evidence that pre service and students have problem with mathematical proofs but many research studies have focused on abilities to produce proofs and counter examples in domain of limit of sequence. The aim of this study is to contribute to research on preservice teachers' productions of proofs and counter examples, as participants showed difficulty in writing these proposition. More importantly, the analysis provides insight and understanding into the design of curriculum and instruction that may improve preservice teachers' learning in mathematics courses.

• School Mathematics
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• v.16 no.1
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• pp.111-133
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• 2014

This study aims to explore mathematical belief system and core belief factors to be found. The mathematical belief system becomes an auto regulation device for students' using mathematical knowledge in mathematical situations and provides them with the context to perceive and understand mathematics. They have individual mathematical beliefs for each of mathematics subject, mathematical problem solving, mathematical teaching and learning and self-concept, and these beliefs of students construct mathematical belief system according to mutual relationships among the mathematical beliefs. Using correlation analysis and multiple regression, mathematical belief system was structuralized and core belief factors were found. Mathematical belief system is structuralized and, as a result the core belief factors that are psychological centrality of high school students' mathematical belief system are found to be persistence, challenge, confidence and enjoyment. These core belief factors are formed on the basis of personal experiences and they are personal primitive beliefs that cannot be changed with ease and cannot be shared with other people but they are related with many other beliefs influencing them.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.21 no.3
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• pp.277-287
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• 2003

As primary source data toward the systematic and efficient management of national land, the aerial photographs have been utilized in many different areas. However, the quality of aerial photographs does not meet the requirement of the users due to unidentified miscellaneous reasons. Aiming for the improvement of the quality of aerial photographs, we first investigated the current status of domestic rules and working procedures related to aerial photographing and film processing in great details. In addition, we investigated and analyzed those of advanced nations such as U.S.A., Canada, G.B. and so on. It was drawn from the comparison and analysis that the poor quality of domestic aerial photographs resulted from lack of the quantitative and objective standards on aerial photography specification as well as poor condition and aging problem of equipments such as aerial camera and film developing equipment. In this paper, we proposed a stepwise strategic plan which consists of the aerial photography specification and quantitative quality control standard taking into consideration the current status of domestic rules and working procedures.

• Fire Science and Engineering
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• v.30 no.4
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• pp.59-64
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• 2016

The PSD (Platform Screen Door System) has been installed to enhance the passengers' safety. A total of 592 stations operate the PSD system, which is almost 71.8% of all stations in South Korea. This study compared the opening rate between the PSD and train door, and calculated the exact amount of passengers at peak time. In addition, the evacuation time was simulated by Pathfinder 2015 with the exact input data. Some of the high density stations have extremely high dangerous points about the passengers' evacuation at some situations by the PSD door opening rate. In particular, due to the interference of a fixed door, when it stops at 7 m less than the regular position, its opening rate becomes less than half of the normal state. To solve this problem, it should be made possible to open the fixed door by changing it to an emergency door or improving the PSD module system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.388-394
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• 2008

In this paper, MAC(Medium Access Control) algorithm for the IEEE 802.11 DCF(Distributed Coordination Function) improving the performance is proposed and analyzed by simulation. The MAC of IEEE 802.11 WLAN to control data transmission uses two control methods called DCF and PCF(Point Coordination function). The DCF controls the transmission based on CSMA/CA(Carrier Sense Multiple Access With Collision Avoidance). The DCF shows excellent performance relatively in situation that competition station is less but has a problem that performance is fallen from throughput and delay viewpoint in situation that competition station is increased. This paper proposes an enhanced DCF algorithm that increases the CW to maximal CW after collision and decreases the CW smoothly after successful transmission in order to reduce the collision probability by utilizing the current status information of WLAN. To prove efficiency of proposed algorithm, a lots of simulations are conducted and analyzed.

• Journal of the Korea Society of Computer and Information
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• v.12 no.4
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• pp.239-248
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• 2007

There's been a difficulty for general corporate to adopt recent incident response study because those studies focus on nation wide CERT Coordination Center or large organization aspect. This study is focus on study and design on security ticket based CERT system through analysis Security management's threat element, attack element, response element and it also help general corporate establish incident response process that is adjusted on IT operation. Confirmed CERT model's effectiveness and effect of quantitative Security incident management way that propose executing Security incident response experiment on the basis of this way. This study which provides general corporate oriented CERT model can be used to improve corporate's capability of responding incident by quantified management technique and select incident response SLA indicator. Already, formation which operate CERT can heighten corporation's information protection level by measure Security incident response result as metrical and analyze and improve problem continuously.

• Childhood Kidney Diseases
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• v.7 no.1
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• pp.86-90
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• 2003

An 8-month-old male infant presented with persistent, gross, orange-colored crystals in his urine. His physical and neurological development was normal. Laboratory study showed hyperuricemia, hyperuricosuria and urate crystaluria. He was determined to have partial hypoxanthine-guanine phosphoribosyl transferase(HPRT) deficiency. The molecular genetic analysis revealed a missense mutation in the patient's HPRT gene. By sequencing the patient's cDNA, we identified an A-to-G transition at nucleotide 239, resulting in the replacement of Aspartate with Glycine at amino acid 80 in the HPRT. To our knowledge, this mutation has not previously been reported. Our patient is now being placed on allopurinol therapy, and has had no problem since. Partial HPRT deficiency has been known to cause recurrent acute renal failure without the phenotypic features of Lesch-Nyhan syndrome. Therefore, we think that early diagnosis and treatment are very crucial in preventing acute renal failure.

• Archives of Plastic Surgery
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• v.40 no.5
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• pp.522-529
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• 2013

Background Despite advances in surgical techniques, sterile protocols, and perioperative antibiotic regimens, surgical site infections (SSIs) remain a significant problem. We investigated the relationship between wound classification (i.e., clean, clean/contaminated, contaminated, dirty) and SSI rates in plastic surgery. Methods We performed a retrospective review of a multi-institutional, surgical outcomes database for all patients undergoing plastic surgery procedures from 2006-2010. Patient demographics, wound classification, and 30-day outcomes were recorded and analyzed by multivariate logistic regression. Results A total of 15,289 plastic surgery cases were analyzed. The overall SSI rate was 3.00%, with superficial SSIs occurring at comparable rates across wound classes. There were similar rates of deep SSIs in the clean and clean/contaminated groups (0.64%), while rates reached over 2% in contaminated and dirty cases. Organ/space SSIs occurred in less than 1% of each wound classification. Contaminated and dirty cases were at an increased risk for deep SSIs (odds ratios, 2.81 and 2.74, respectively); however, wound classification did not appear to be a significant predictor of superficial or organ/space SSIs. Clean/contaminated, contaminated, and dirty cases were at increased risk for a postoperative complication, and contaminated and dirty cases also had higher odds of reoperation and 30-day mortality. Conclusions Analyzing a multi-center database, we found that wound classification was a significant predictor of overall complications, reoperation, and mortality, but not an adequate predictor of surgical site infections. When comparing infections for a given wound classification, plastic surgery had lower overall rates than the surgical population at large.