• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.3
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• pp.290-296
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• 2008

After scientific verification of the osteointegration of dental implants, the overall efficiency of dental implants has been generally accepted. Thus, implants now play a major role in the clinical treatment of an edentulous mandible, and in the prosthetic maintenance equipment for partial edentulous mandible patients. Yet, for the successful long-term maintenance of implants, careful consideration of the bio-mechanics is needed to ensure that the maximum stress in the mandible as a result of chewing is maintained under a critical value. Accordingly, this study focuses on reducing the maximum stresses in an implanted mandible, especially in the cortical bone. Thus, the stresses in the implant and mandible are analyzed using finite element packages, including I-DEAS and NISA II/DISPLAY III, using a local zooming technique for a concentrated stress analysis. In addition, the von-Mises stress and principal stress in the mandible are both checked to determine the best combination.

• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.1
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• pp.34-45
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• 2010

This paper describes the design, manufacturing process, testing, application, and assessment of capacity-ratings of the first all advanced composites bridge on a public highway system. In order to verify the bridge design prior to the field application, a sub-scale bridge superstructure was built and tested in the laboratory. The field load test results were compared with those of the finite element analysis for the verification of validity. To investigate its in-service performance, field load testing and visual inspections were conducted under an actual service environment. The paper includes the presentation and discussion for advanced composites bridge capacity rating based on the stress modification coefficients obtained from the test results. The test result indicates that the advanced composites bridge has no structural problems and is structurally performing well in-service as expected. Since these composite materials are new to bridge applications, reliable data is not available for their in-service performance. The results may provide a baseline data for future field advanced composites bridge capacity rating assessments and also serve as part of a long-term performance of advanced composites bridge.

• Journal of Korean Neurosurgical Society
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• v.42 no.3
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• pp.173-178
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• 2007

Objective : Hydrocephalus is one of the major complications following spontaneous subarachnoid hemorrhage (SAH). However, the risk factors of the hydrocephalus after SAH are not still well known. This study was focused on verification of the causal relationships between the development of hydrocephalus and SAH. Methods : The patients who developed hydrocephalus after rupture of aneurysms were studied. To obtain prognostic factors regarding to hydrocephalus, several parameters such as age, sex, hypertension, location of aneurysm, existence of intraventricular hemorrhage (IVH) and intracerebral hemorrhage (ICH), Glasgow coma scale (GCS), Hunt-Hess SAH classification & Fisher Grade on admission and the ratio of frontal harn of lateral ventricle diameter to skull inner table diameter at this level (FH/ID) were studied retrospectively. Results : The development of hydrocephalus following SAH is multifactorial. The age, IVH, FH/ID ratio were related to hydrocephalus in analysis. There is a low clinical correlation between sex, hypertension, location of aneurysm, existence of ICH, GCS, Hunt-Hess SAH classification, Fisher Grade on admission and hydrocephalus. Conclusion : Knowledge on risk factors related to the occurrence of hydrocephalus may help guide neurosurgeons in the long-term care of patients who have experienced aneurysmal SAH.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.977-981
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• 2008

본 연구에서는 행정중심복합도시 예정 및 주변지역의 금강과 미호천 일부 구간을 대상으로 하상변동의 실태 분석과 수위유지시설 설치에 따른 장기 예측을 실시하였다. 1988년, 2002년 및 2007년의 횡단자료를 이용하여 대상구간의 종방향 하상변동 실태를 분석한 결과 금강과 미호천 구간 모두 2007년 최심하상고는 1988년에 비해 심한 저하가 발생된 반면 2002년에 비해서는 미소한 변화가 발생되었다. 수위유지시설 설치에 따른 하상변동 장기 예측을 수행하기 위하여 본 연구에서는 미육군 공병단에서 개발한 1차원 모형인 HEC-RAS 4.0 모형을 적용하였다. 고정상 모형의 수행을 통하여 수면고의 이상치를 보정(calibration)하였으며, 1988년과 2002년 횡단자료를 사용하여 이동상 모형에서의 검정(verification)을 실시하였다. 2007년을 기준으로 하여 2017년까지 향후 10년간 수위유지시설의 설치 높이에 따른 시나리오별 하상변동을 예측한 결과 미호천 대상구간은 그 영향이 미미하였으나 금강 대상구간은 수위유지시설의 높이가 높을수록 많은 영향을 미치는 것으로 나타났다. 수위유지시설의 설치 높이가 7m일 경우 금강 대상구간은 설치하지 않을 경우보다 미호천합류점 상류부근에서 1.59m의 퇴적이 발생할 것으로 모의되었으며, 수위유지시설 하류부근에서 1.98m의 침식이 발생할 것으로 모의되었다.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.338-350
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• 2010

As existing materials for ground reinforcement, chemical grout material using cementitous materials and waterglass was used. But many problems in terms of ground reinforcement effects were implicated. In this study, for development and applicability verification of new materials, viscosity, fluidity, permeability, Self-Leveling, keeping of drilled hole, antiwashout underwater, resistance of water (groundwater dilution and minimize material eluting) and the early strength and long-term strength characteristics of developed materials was confirmed, and material standards, and establishing construction standards for the various model tests were conducted. As a result, high viscosity, flowability, permeability and keeping of drilled hole characteristics are excellent, in addition to the early strength properties, dilution does nat occur to groundwater, including groundwater is available for dealing with environmental issues. Application of basic and reinforcement method by Filler function in addition to structure can also or development of a new concept can be expected. In addition, middle and large-diameter drilled shaft, micropile, ground anchors, soil-nailing, steel pipes multi-grouting reinforcement for cement injection process could be used enough to even be considered.

• KIEAE Journal
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• v.17 no.4
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• pp.33-39
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• 2017

Purpose: The use of renewable energy system is essential for building energy independence and saving energy consumption in the building sector. Among renewable energy technologies, ground source heat pump(GSHP) system is more energy-efficient and environmental-friendly than other heat source systems due to utilize stable ground heat source. However, the GSHP system requires a high initial installation cost and installation space in limited urban area, so it is difficult to have superiority in the market of heat source system. Therefore, it is necessary to develop the installation method of low-cost and improve system performance. This paper aims to evaluate the performance of double u-tube ground heat exchanger(GHX) and verify system feasibility through real-scale experiment. Method: In this study, the real-scale experiment of vertical closed-type GSHP system was conducted using double u-tube GHX and high-efficiency grout. Through the verification experiment, heat source temperature, heat exchange rate(HER) and seasonal performance factor(SPF) were measured according to the long-term operation. In addition, the feasibility analysis was conducted comparing to the single u-tube system. Result: In the results of experiment, average HER was 136.27 W/m and average SPF was 5.41. Furthermore, compared to the single u-tube, the installation cost of the developed system could be reduced about 70% in the same heating load condition.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.485-486
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• 2010

In this research, a new analysis method which is able to examine the safety and to assess the serviceability of high-rise buildings from construction period to service life has been developed. The effect of both construction sequence and inelastic behavior of concrete has been considered in the developed analysis method in three dimensions. The more efficient analysis technique and modeling method for practical use were also suggested. For verification of the developed analysis method, the data measured in a high-rise building under construction was compared with the analysis results. Through comparison of the analysis results with the measured data, it was found that the analysis results generally simulated the trend of the measured data well in all cases.

• International Journal of Concrete Structures and Materials
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• v.2 no.2
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• pp.137-143
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• 2008

In recent years, much research work has been performed on durability design and long-term performance of concrete structures in marine environments. In particular, the development of new procedures for probability-based durability design has been shown to provide a more realistic basis for the analysis. This approach has been successfully applied to several new concrete structures, where requirements for a more controlled durability and service life have been specified. For reinforced concrete structures in a marine environment, it is commonly assumed that the dominant degradation mechanism is the corrosion of the reinforcement due to the presence of chlorides. The design approach is based on the verification of durability limit states, examples of which are: depassivation of reinforcement, cracking and spalling due to corrosion, and collapse due to cross section loss of reinforcement. With this design approach the probability of failure can be determined as a function of time. In the present paper, a probability-based durability performance analysis is used in order to demonstrate the importance of the durability design approach of concrete structures in marine environments. In addition, the sensitivity of the various durability parameters affecting and controlling the durability of concrete structures in a marine environment is studied. Results show that the potential of this approach to assist durability design decisions making process is great. Based the crucial information generated, it is possible to prolong the service life of structures while simultaneously optimizing the final design solution.

• IEMEK Journal of Embedded Systems and Applications
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• v.8 no.4
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• pp.213-218
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• 2013

In this research, we report on the development of simulation system for performance verification of BMS(Battery Management System) which is utilized in electric vehicles. In the industrial circles, a manufacturer of BMS typically tests their system with real battery packs. However, it takes a long time to test all functions of BMS. Here, we develop BMU(Battery Managament Unit) as an embedded board, which will be installed in electric vehicle for controlling battery packs. All other environment factors for testing BMU are developed in softwares in order to reduce the term of test. Especially, the proposed system consists of cell simulator and CMU(Cell Management Unit) simulator which simulate real battery cells and control battery cells. These simulators enable the BMU to test more battery cells. In addition, proposed system provides diagnosis program in order to diagnose and monitor the condition of BMS which makes the test of BMS more easily. In order to verify the performance of the developed simulator, we have performed the experiment with real battery packs and our simulator. Through comparing two results of experiments, we verify that developed simulator shows better performance in terms of less amount of testing duration though having high reliability.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.52-57
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• 2009

This paper describes the multi-heat pumps applied in an ground source heat pump system for an actual building. The performance of a ground source multi-heat pump installed in the field was investigated at heating season. The average COP of the systems with single U-tube and double tube type GLHXs were 4.8 and 5.0, respectively. It is needed to investigate the long term performance of double tube type GLHX, because the reduction of inlet temperature of OD HX for this GLHX was larger than it for U-tube GLHX.