• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1481-1486
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• 2008

To apply more effective the RCM analysis for railway vehicle, the maintenance cost per equipment should be considered together with failure criticality per equipment considered in existing. This paper is described the systematic calculation of maintenance cost considering the RCM analysis of railway vehicle. To calculate the maintenance cost systematically, the cost breakdown structure was established, and basic cost information and calculated cost items were defined. In addition, the linking between calculated cost and RCM analysis was considered. In future, this proposal would be used to analysis of cost effectiveness through RCM analysis of railway vehicle.

• Oral Biology Research
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• v.42 no.4
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• pp.248-253
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• 2018

Cemental tears are uncommon form of root fracture that can lead to rapid localized periodontal attachment loss. Studies have described periodontal breakdown as being associated with the separation of the cementum from the underlying tooth structure. The aim of this case report is to assess the outcome of treatment of cemental tear with several surgical treatment regimens. Three patients with cemental tear were treated with different surgical method. In all three cases, the cemental tear occurred on maxillary right central incisors. In each case, the root fragment were removed, the localized defect was treated using different surgical methods including guided tissue regeneration and bone graft followed by scaling and root planting. In all three cases, symptoms subsided after the treatment and clinical attachment level was improved up to 2 mm at 3 month after surgery. Both conventional and regenerative periodontal surgery could achieve successful outcomes.

• Journal of the Korean Society of Systems Engineering
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• v.18 no.1
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• pp.99-104
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• 2022

In this paper, to increase the maintenance efficiency of the urban railway train control system and to build a standard data system, we collect as much as possible structured, unstructured, and semi-structured data, and collect data by sensing and monitoring the system status and system status and monitoring. pre-process function data(Identification, purification, integration, transformation) through effective data classification and maintenance activities business classification system was studied. The purpose of this is to define the data matrix model by considering the relationship with the data generated and managed in the O&M stage of the train control system operated by the urban railway together with the WBS model, and to reflect and utilize it in practice.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.34-35
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• 2021

Currently, the Korean Smart Construction Corporation aims to stimulate overseas expansion of smart construction technology centered on Expressway development. In addition, the integrated classification system of construction information with Work Breakdown Structure(WBS) is currently being established in Korea, but its application to the construction industry is limited. In this study, data generation using simulation is carried out at the lowest level of WBS presented by the Korea Expressway Corporation, and detailed process productivity is predicted by site conditions.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.259-262
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• 2015

Due to the labor-intensiveness, high investment cost, long execution time, frequent change orders, and many stakeholders in a BIM project, a BIM manager is bound to face a lot of risks to make decisions in cost managing process. Since the productivity of a BIM team will affect the execution cost, this study investigates a simple method of assessing the productivity of a BIM team using the working timesheet records of the team. In this research, the productivity of a BIM team is defined as the effective working floor area (in square meters) of BIM uses per labor-time (in man-months) spent by the team. After the applicability of this method is tested by regression analysis using data from 5 real BIM projects in the construction phase, it is found that the simple productivity definition adopted in the method, although easy-to-implement, does not produce a statistically constant productivity value. More research is therefore needed in the future to devise better indicator(s) for assessing the productivity of a BIM team.

• Korean Journal of Materials Research
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• v.8 no.11
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• pp.1067-1073
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• 1998

High quality diamond films of the silicon on diamond (SOD) structure are deposited using CO and $H_2$ gas mixture in microwave plasma chemical vapor deposition (CVD), a SOD structure is fabricated using low pressure CVD polysilicon on diamond/ Si(100) substrate. The crystalline structure of the diamond films which composed of { 111} and {100} planes. were changed from octahedral one to cubo-octahedron one as the CO/$H_2$ ratios are increased. The high quality diamond films without amorphous carbon and non-diamond elements were deposited at the CO/$H_2$ flow rate of 0.18. and the main phase of the diamond films shows (111) plane. The diamond/Si(lOO) structure shows that the interface is flat without voids. The measured dielectric constant. leakage current and breakdown field were $5.31\times10^{-9}A/cm^2$ and $9\times{10^7}{\Omega}cm$ respectively.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.3
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• pp.38-45
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• 2018

The purpose of this study is to deduct the structural damage / work process risks factors which can be occurred during the decommissioning in the NPP containment concrete structure. To achieve these purpose, risk profile specified in the construction industry is analyzed, and the work process of NPP decommissioning and the construction project were matched based on the similarity of each works. Accordingly, human and physical risk factors are classified. Finally, the risk associated with the building structure and work process was classified as per their process activities, and risk typology explaining the disaster which put the structure, equipments, machine and workers in serious danger was developed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.845-848
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• 2009

Power semiconductor devices are semiconductor devices used as switches or rectifiers in power electronics circuits. Theyare also caleed power devices or when used in integrated circuits, called power ICs. Some common power devices are the power diode, thyristor, power MOSFET and IGBT (insulated gate bipolar transistor). A power diode or MOSFET operates on similar principles to its low-power counterpart, but is able to carry a larger amount of current and typically is able to support a larger reverse-bias voltage in the off-state. Structural changes are often made in power devices to accommodate the higher current density, higher power dissipation and/or higher reverse breakdown voltage. The vast majority of the discrete (i.e non integrated) power devices are built using a vertical structure, whereas small-signal devices employ a lateral structure. With the vertical structure, the current rating of the device is proportional to its area, and the voltage blocking capability is achieved in the height of the die. With this structure, one of the connections of the device is located on the bottom of the semiconductor.

• Journal of the Korean institute of surface engineering
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• v.51 no.6
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• pp.415-420
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• 2018

The possibility of an improvement in heat dissipation performance of aluminum alloy heat sink for shipboard LED luminaries through plasma electrolytic oxidation (PEO) was investigated. Four different PEO coatings were produced on aluminum alloy 5052 in silicate based alkaline solution by varying current density ($50{\sim}200mA/cm^2$). On voltage-time response curves, three stages were clearly distinguished at all current densities, namely an initial linear increase, slowdown of increase rate, and steady state(constant voltage). It was found that the increase in current density caused the breakdown voltage to increase. Two different surface morphologies - coralline porous structure and pancake structure - were confirmed by SEM examination. The coralline porous structure was predominant in the coatings produced at lower current densities (50 and $100mA/cm^2$) while under high current densities(150 and $200mA/cm^2$) the pancake structure became dominant. The coating thickness was measured and found to be in a range between about $13{\mu}m$ and $44{\mu}m$, showing increasing thickness with increasing current density. As a result, $100mA/cm^2$ was proposed as an effective process parameter to improve the heat dissipation performance of aluminum alloy heat sink, which could lower the LED operating temperature by about 30%.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.12
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• pp.1-6
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• 2007

In this study, we have performed the channel modification of the conventional MHEMT (metamorphic high electron mobility transistor) to improve the breakdown characteristics. The Modified channel consists of the InxGal-xAs channel and the InP sub channel instead of the InxGa1-xAs channel. Since InP has the lower impact ionization coefficient in comparison with In0.53Ga0.47As, we have adopted the InP-composite channel in the modified MHEMT. We have investigated the breakdown mechanism and the RF characteristics for the conventional and the InP- composite channel MHEMTs. From the measurement results, we have obtained the enhanced on and off-state breakdown voltages of 2.4 and 5.7 V, respectively. Also, the increased RF characteristics have brought about the decreased output conductance for the InP-composite channel MHEMT. The cut-off frequency (fT) and the maximum oscillation frequency (fmax) for the InP-composite Channel MHEMT were 160 GHz and 230 GHz, respectively. It has been shown that the InP-composite channel MHEMT has the potential applications for the millimeter wave power device.