• Nuclear Engineering and Technology
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• v.25 no.3
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• pp.430-436
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• 1993

Due to the failure of the instrument and control devices of nuclear power plants caused by aging, nuclear power plants occasionally trip. Even a trip of a single nuclear power plant (NPP) causes an extravagant economical loss and deteriorates public acceptance of nuclear power plants. Therefore, the replacement of the instrument and control devices with proper consideration of the aging effect is necessary in order to prevent the inadvertent trip. In this paper we investigated the optimal replacement periods of the control computer's components of Wolsung nuclear power plant Unit 1. We first derived mathematical models for optimal replacement periods to the digital control computer's components of Wolsung NPP Unit 1 and calculated the optimal replacement periods analytically. We compared the periods with the replacement periods currently used at Wolsung NPP Unit 1. The periods used at Wolsung is not based on mathematical analysis, but on empirical knowledge. As a consequence, the optimal replacement periods analytically obtained and those used in the field show a little difference.

• Journal of the Korean institute of surface engineering
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• v.52 no.3
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• pp.163-170
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• 2019

Durability of instrument is one of the most important factor to ensure accurate treatment and decrease failure for the orthopedic surgical operation. Normally, a set-screw driver tip has been processed with hard coating for their higher durability and wear resistance. And several surface modification methods were obtained such as titanium nitride (TiN) coating, diamond like carbon coating, other nitriding, and etc. In this study, we have surface modified on set-screw driver tip with TiN and DLC, investigated whether the TiN and DLC coatings affect the mechanical properties and durability of the set-screw driver tip in the pedicle screw system. The surface morphologies were observed with scanning-electron microscopy (SEM), and the static/dynamic torsional properties were investigated with universal testing machine based on ASTM F543. Coating thickness of each coatings were commonly around $1^{\circ}C$. Static torsional stiffness, and ultimate torque values for DLC and TiN coated samples were significantly higher than those of non-coated sample by the pared T-test. Surface morphology of after the dynamic torsional test was more clean with less scratch or friction traces from DLC coating than that of TiN coating and non-coated sample.

• Journal of Radiation Protection and Research
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• v.44 no.3
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• pp.97-102
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• 2019

Background: Dose rate meters are the most widely used, and perhaps one of the most important tools for the measurement of ionising radiation. They are often the first, or only, device available to a user for an instant check of radiation dose at a certain location. Throughout the world, radiation safety practices rely strongly on the output of these dose rate meters. But how well do we know the quality of their output? Materials and Methods: This review is based on the measurements 1,158 commercially available dose rate meters of 116 different makes and models. Expected versus the displayed dose patterns and consistency was checked at various dose rates between $5{\mu}Gy{\cdot}h^{-1}$ and $2mGy{\cdot}h^{-1}$. Samples of these meters were then selected for further investigation and were exposed to radiation sources covering photon energies from 50 keV to 1.5 MeV. The effect of detector orientation on its reading was also investigated. Rather than focusing on the angular response distribution that is often reported by the manufacturer of the device, this study focussed on the design ergonomics i.e. the angles that the operator will realistically use to measure a dose rate. Results and Discussion: This review shows the scope and boundaries of the ionising radiation dose rate estimations that are made using commonly available meters. Observations showed both inter and intra make and model variations, occasional cases of instrument failure, instrument walk away, and erroneous response. Conclusion: The results indicate the significance of selecting and maintaining suitable monitors for specific applications in radiation safety.

• Journal of the Korean Society of Radiology
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• v.85 no.1
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• pp.36-53
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• 2024

As the number of spinal surgeries being performed expands, the number of medical imaging procedures such as radiography, CT, and MRI is also increasing, and the importance of their interpretation is becoming more significant. Herein, we present the radiological findings of a variety of complications that can occur after spinal surgery and discuss how effectively and accurately they can be diagnosed through imaging. In particular, this study details the characteristic imaging findings specific to the early and long-term postoperative periods. Early complications of spinal surgery include improper placement of surgical instruments (instrument malpositioning), seromas, hematomas, pseudomeningoceles, and infections in the region surrounding the surgical site. Conversely, long-term complications may include osteolysis around surgical instruments, failure of fusion, adjacent segment disease, and the formation of epidural fibrosis or scar tissue. A precise understanding of the imaging assessments related to complications arising after spinal surgery is crucial to ensure timely and accurate diagnosis, which is necessary to achieve effective treatment.

• Journal of the Korean Data and Information Science Society
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• v.26 no.3
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• pp.707-714
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• 2015

The SF-36 is the most common instrument to check the quality of life for dialysis patients with chronic renal failure. However, there were too much burden for them to answer 36 items of it. So we purposed to develop the RFQoL-K reduced type of the SF-36. Participants who had newly registered for dialysis were enrolled in 29 medical centers during 45months from 2009. We developed the RFQoL-K through 355 people who applied the SF-36 at 3 and 12 months after registration and then checked it's internal validity. External validity about it was checked via 411 people who answered only one time survey after registration. In conclusion, the RFQoL-K had total 14 items which was consisted of 8 items on physical factors and 6 items on mental factors from the SF-36. The RFQoL-K summary scores explained 91-93% of the SF-36 summary scores. The RFQoL-K was well reflected SF-36 because the correlation and the internal consistency between two tools were very high 0.96 to 0.98 and 0.96 to 0.98 respectively.

• Journal of the Korean Institute of Gas
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• v.4 no.2 s.10
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• pp.46-51
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• 2000

It is required that fuel gas accidents should be managed carefully along with the increase of fuel gas consumption. Factors to cause accidents were investigated through a systematic analysis of gas accidents during recent 4 years, which could be applied to prepare countermeasures to reduce gas accidents. The thawing season is found to be weak to gas accidents, showing a slightly higher rate of accident occurring than average. During this term although the number of LPG accident is similar to that of yearly average, countermeasures are required for LPG facilities since the portion of accident is large; in detail, user's carelessness, defective facility, or instrument failure are major causes. The number of city gas accident facility is larger than that of yearly average; particularly, defective facilities, third-party work, and appliance failure are major causes. As a result, countermeasures have been suggested for the accident of large portion or above yearly average.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.3
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• pp.259-268
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• 2007

purpose: This study was to evaluate the shear bond strength of Lithium Disilicate Glass-Ceramic by removable method of temporary cement on the abutment tooth. Material and Method: Sixty molar teeth of human with the occlusal surface up were mounted in acrylic resin blocks. The 45 specimens were prepared to exposure dentin by diamond bur and the eugenol-containing temporary cement($Cavitec^{TM}$ ($KERR^{(R)}$, U.S.A)was applied to the dentin surfaces. After initial removal of the cement with a dental explorer, the specimens were divided into 4 groups of 15 specimens each. The dentin surfaces of the specimens were treated by rotary instrument with as follow pastes: $Zircate^{(R)}$ prophy paste(Dentsply, U.S.A), Radent Prophy Paste(Pascal company,inc. U.S.A), and Dental pumice(Wip mix corporation,U.S.A). An adhesive resin luting agent(Variolink $II^{(R)}$, Ivoclar Vivadent, Leichtenstein) including Monobond-S and $Excite^{(R)}$ was applied to all specimens. The ceramic specimens were made with an A1 ingot of IPS Empress $II^{(R)}$ (Ivoclar Vivadent, Leichtenstein). After the specimens were stored in distilled water for 48hr, the shear bond strength(MPa) was measured by a Universal testing machine(Zwick 145641, Zwick, Germany) at a 1mm/min cross-head speed. The data were statistically analyzed by one-way ANOVA and Duncan's multiple range test. Results: In all group, there were no significant differences in comparison with the control group(p>0.05). The pattern of most failure showed the mixed type of cohesive and adhesive failure. Conclusion: Resin bond strength of IPS Empress $II^{(R)}$ was not affected by removal method of the temporary cement.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.3
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• pp.206-216
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• 2019

The present study identified several antecedents that create perceived resistance to supply chain management (SCM) change. This work particularly emphasizes SCM change, which is notable given its central role in reacting market orientation and varied environmental and managerial conditions. A careful case study on a small and medium sized food production company in South Korea leads to the formulation of our framework including one second-order construct of 'resistance' as well as eight first-order constructs of 'implementing the payment terms', 'balancing of business process', 'fear of responsibility', 'business sustainability transparency', 'past experience of failure', 'competence of work personnel', 'cooperation with third parties' and 'sharing personnel information with partner'. The hypothesized relation of first- and second-order construct was validated using survey sample data collected from 350 respondents who completed their questionnaire instrument. Results from confirmatory factor analysis revealed that nomological validity was established at statistical significance level by identifying six first order constructs of 'implementing the payment terms', 'fear of responsibility', 'business sustainability transparency', 'past experience of failure', a conbined construct of 'competence of work personnel/cooperation with third parties' and 'sharing personnel information with partner'. The findings from our work are expected to provide important insights to the strategy for SCM risk management for small and medium sized company.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.452-455
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• 2004

MSC (Multi-Spectral Camera) system is a remote sensing instrument to obtain high resolution ground image. EOS (Electro-Optic System) for MSC mainly consists of PMA (Primary Mirror Assembly), SMA (Secondary Mirror Assembly), HSTS (High Stability Telescope Structure) and DFPA (Detector Focal Plane Assembly). High performance of EOS makes it possible for MSC system to provide high resolution and high quality ground images. Temperature of the EOS needs to be controlled to be in a specific range in order not to have any thermal distortion which can cause performance degradation. It is controlled by full redundant CPU based electronics. The validity of thermistor readings can be checked because a few thermistors are installed on each control point on EOS. Various kinds of thermal control logics are used to prevent 'Single Point Failure'. Control logic has a few set of database in order not to be corrupted by SEU (Single Event Upset). Even though the thermal control logic is working automatically, it can also be monitored and controlled by ground-station operator. In this paper, various ways of thermal control logic for EOS in MSC will be presented, which include thermal control mode and logic, redundancy design and status monitoring and reporting scheme.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1588-1595
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• 2005

In this study, the installation location of accelerometer and accelerograph for dam are investigated in the field to establish of emergency action against dam failure when earthquake occur and to guarantee the results of seismic stability of dams which are analysed with dynamic analysis method during 1999 to 2003 by KOWACO. By a comparative study concerning of domestic and foreign guidelines of seismic strong motion instrumentation for dams, "Guidelines of Seismic Strong-Motion Instrumentation Installation, Operation and Maintenance for Dams" is established to set up the standard of seismic strong-motion instrumentation for dam, are supervised by KOWACO There is some problems in taking a measure of stability of dams when earthquake event occur because the existing seismic strong motion instruments are operated independently. This make difficult to confirm the occurrence of seismic event. For that reason, in this study the plan of unified operation and maintenance system for strong-motion instrument for dams is designed. It will make possible real-time seismic monitoring, data transmission and receiving, giving warning for earthquake, and exchanging data with national seismic network.