• Nuclear Engineering and Technology
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• v.41 no.3
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• pp.307-318
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• 2009

KAERI (Korea Atomic Energy Research Institute) has developed the GAMMA+ code for a thermo-fluid and safety analysis of a VHTR (Very High Temperature Gas-Cooled Reactor). A key safety issue of the VHTR design is to demonstrate its inherent safety features for an automatic reactor power trip and power stabilization during an anticipated transient without scram (ATWS) accident such as a loss of forced cooling by a trip of the helium circulator (LOFC) or a reactivity insertion by a control rod withdrawal (CRW). This paper intends to show the ATWS assessment capability of the GAMMA+ code which can simulate the reactor power response by solving the point-kinetic equations with six-group delayed neutrons, by considering the reactivity changes due to the effects of a core temperature variation, xenon transients, and reactivity insertions. The present benchmark calculations are performed by using the safety demonstration experiments of the 10 MW high temperature gas cooled-test module (HTR-10) in China. The calculation results of the power response transients and the solid core temperature behavior are compared with the experimental data of a LOFC ATWS test and two CRW ATWS tests by using a 1mk-control rod and a 5mk-control rod, respectively. The GAMMA+ code predicts the power response transients very well for the LOFC and CRW ATWS tests in HTR-10.

• Journal of Dental Anesthesia and Pain Medicine
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• v.19 no.3
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• pp.135-141
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• 2019

Background: The fear of needle insertion and pain during anesthesia is a source of patient dissatisfaction in dentistry. Inferior alveolar nerve block (IANB) remains the most common type of block and is in itself painful. Computer-controlled local anesthetic delivery (CCLAD) has been proven to reduce the pain associated with injection of anesthetics in various blocks. However, the efficacy of CCLAD for IANB in adults remains unknown. Methods: Sixty-four adult patients requiring bilateral IANB were selected and divided into two groups: group A (50 patients receiving IANB via CCLAD) and group B (50 patients receiving IANB using a conventional cartridge syringe). Pain perception and patient comfort were assessed using the visual analog scale and the 5-point semantic scale, respectively. Results: The pain perception was compared between the two groups using the Mann-Whitney U-test, and the P value was 0.003. The patient comfort was also compared using the same test, and the P value was 0.484. Conclusion: A significant difference was observed in the pain perception of the patients during CCLAD. The patient comfort was grossly equal for both techniques.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.8
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• pp.86-96
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• 2000

The representative area among the ones whose cost increases as the integration ratio increases is the test area. As the relative cost of hardware decreases, the BIST method has been focued on as the future-oriented test method. The biggest drawback of it is the increasing test time to obtain the acceptable fault coverage. This paper proposed a BIST implementation method to reduce the test times. This method uses an input grouping and test point insertion method, in which the definition of test point is different from the previous one. That is, the test points are defined on the basis of the internal nodes which are the reference points of the input grouping and are merging points of the grouped signals. The main algorithms in the proposed method were implemented with C-language, and various circuits were used to apply the proposed method for experiment. The results showed that the test time could be reduced to at most $1/2^{40}$ of the pseudo-random pattern case and the fault coverage were also increased compared with the conventional BIST method. The relative hardware overhead of the proposed method to the circuit under test decreases as th e size of the circuit to be tested increases, and the delay overhead by the BIST utility is negligible compared to that of the original circuit. That means, the proposed method can be applied efficiently to large VLSI circuits.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.658-663
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• 2011

The purpose of this study is to develop an air-passing soundproofing panel with more improved structure to reduce the $CO_2$ emission and installation cost. To reduce the emission of $CO_2$ ; it is suggested to choose low $CO_2$ emission material relative to the aluminum and to reduce the materials by developing a specially designed air-passing soundproofing panel structure. First of all, we performed the flow analysis to predict the wind pressure according to the open angle of the air-passing soundproofing panel and the noise level analysis at the receiver point. To verify the simulation, a prototype of the soundproofing panel was made. The flow test in the wind tunnel and load test were performed. The economic evaluation for the installation of the air-passing soundproofing panel was performed and specifications of the installation was prepared. As the results of this research, it was verified that the wind load was reduced about 40% to that of the conventional one at 25m/s wind speed in the wind tunnel test. By applying the 4m span soundproofing wall with air-passing soundproofing panel and under the cost of 250 thousand $won/m^2$ instead of the conventional 2m span panel, the installation cost will always be lowered than the conventional one in the combination of (60:40~50:50) conventional to air-passing soundproofing panel from the economic evaluation. The 20% reduction of $CO_2$ was found by changing the 50% of aluminum soundproof panel to air-passing soundproofing panel.

• Geomechanics and Engineering
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• v.4 no.3
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• pp.191-208
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• 2012

Due to rapid industrialisation, large scale infrastructure development is taking place worldwide. This includes railways, high speed highways, elevated roads etc. To meet the demands of society and industry, many innovative techniques and materials are being developed. In developed nations like USA, Japan etc. for railways applications, new material like geocells, geogrids are being used successfully to enable fast movement of vehicles. The present research work was aimed to develop design methodologies for improvement of grounds subjected to cyclic loads caused by moving vehicles on roads, rail tracks etc. Deformation behavior of ballast under static and cyclic load tests was studied based on square footing test. The paper presents a study of the effect of geo-synthetic reinforcement on the (cumulative) plastic settlement, of point loaded square footing on a thick layer of granular base overlying different compressible bases. The research findings showed that inclusion of geo-synthetics significantly improves the performance of ballasted tracks and reduces the foundation area. If the area is kept same, higher speed trains can be allowed to pass through the same track with insertion of geosynthetics. Similarly, area of machine foundation may also be reduced where geosynthetics is provided in foundation. The model tests results have been validated by numerical modeling, using $FLAC^{3D}$.

• Journal of Korean Academy of Nursing
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• v.35 no.7
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• pp.1401-1409
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• 2005

Purpose: Infants at neonatal intensive care units (NICU) are invariably exposed to various procedural and environmental stimuli. The study was performed to compare the pain responses in three NICU stimulants and to examine the clinical feasibility for NICU infants using CRIES, FLACC and PIPP. Method: In a correlational study, a total of 94 NICU stimulants including angio-catheter insertions, trunk-rubbings and loud noises, was observed for pain responses among 64 infants using CRIES, FLACC and PIPP. Results: A significant difference was identified among the mean scores in CRIES($F_{(2, 91)}$=47.847, p=.000), FLACC($F_{(2, 91)}$=41.249, p=.000) and PIPP($F_{(2. 91)}$=16.272, p=.000) to three stimulants. In a Post-hoc Scheff test, an angio-catheter insertion showed the highest scores in CRIES, FLACC and PIPP compared to the other two stimulations. A strong correlation was identified between CRIES and FLACC in all three stimulations(.817 < r < .945) while inconsistent findings were identified between PIPP and CRIES or FLACC. Conclusions: The results of the study support that CRIES and FLACC are reliable and clinically suitable pain measurements for NICU infants. Further studies are needed in data collection time-point as well as clinical feasibility on PIPP administration to assess pain response in infants, including premature infants.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.6
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• pp.526-534
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• 2001

Purpose : The objective of this study is to ascertain whether the positive exists among the frenum length, the tongue movement and the speech and to present the normal range of tongue movement and guidelines for the choice of surgery, observation if necessary. Materials and Methods : 180 patients were evaluated. We divided 180 patients into 6 group by age. Each group was separated as follows; the age of 2.5-4, 5-6, 7-9, 10-12, 16-18. We measured the frenal length, the range of tongue motion and evaluated the speech so that we really questioned about the positive relationship between the tongue-tie and speech. We let the patient exercise the protrusive both(right, left) laterotrusive superior movement of the tongue. During these movements, we measured the distance between the vermilion border and the tongue tip. We also measured the distance from the tongue tip to the point contacting the upper lip with dorsum of the tongue during the maximal protrusive movement of the tongue. Three linear measurement of the anterior, inferior segment of the tongue including the lingual frenum, are made. These measurements are as follows: 1. Distance A. Free anterior portion of the tongue from the point of frenular insertion to the tongue tip. 2. Distance B. The distance from the initiating point of the lingual frenum to the point connecting the two sublingual carundcles to the lingual frenum perpendicularly. 3. Distance C. The distance from the point contacting the line crossing the sublingual caruncles with the lingual frenum to the terminating point of the lingual frenum. We transform three linear measures into a statistical ratio, A/(A-B+C), representing the length of the free portion of the tongue compared with the total sublingual dimensions. In addition, we assessed the speech through Picture Consonant Articulation Test(PCAT) and tried to find out the relationship between the length of the lingual frenum and speech. Conclusion : As people are born, they have small and restricted tongue. As people grow old, tongue motions are more liberate, and unrestricted and they can speak so freely. Therefore we suggest that until age 5, oral and maxillofacial surgeons postpone the surgery if not urgent, evaluate the maximal lingual motions and PCAT according to this article and observe their changes.

• Nuclear Engineering and Technology
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• v.25 no.3
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• pp.361-370
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• 1993

Low power physics tests should be peformed for the domestic pressurized light water reactors (PWRs) after refueling. The tests are peformed to ensure that operating characteristics of the core are consistent with predictions and that the core can be operated as designed. But in some low power physics tests, slow but steady reactivity increasing phenomena were noticed after step reactivity insertion by the control rod movement. These reactivity increasing phenomena are due to the low flux level and the gamma background because an uncompensated ion chamber (UIC) is used as the ex-core neutron detector. The gamma background may affect the results or the lour power physics tests. The aims or this paper are to analyze the grounds of such phenomena, to simulate a reference bank worth measurement test and to present a resolution quantitatively. In this study, the gamma background level was estimated by numerically solving the point kinetics equations accounting the gamma background effect. The reactivity computer check test was simulated to verify the model. Also, an appropriate neutron flux level was determined by simulating the reference bank worth measurement test. The determined neutron flux level is approximately 0.3 of the nuclear heating flux. This level is about 3 times as high as the current test upper limit specified in the test procedure. Then, the findings from this work were successfully applied to Kori unit 4 cycle 7 and Yonggwang unit 1 cycle 7 physics tests.

• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1626-1637
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• 2020

This work covers an important point of the benchmark released by the expert group on Uncertainty Analysis in Modeling of Light Water Reactors. This ambitious benchmark aims to determine the uncertainty in light water reactors systems and processes in all stages of calculation, with emphasis on multi-physics (coupled) and multi-scale simulations. The Gesellschaft für Anlagen und Reaktorsicherheit methodology is used to propagate the thermal-hydraulic uncertainty of macroscopic parameters through TRACE5.0p3/PARCSv3.0 coupled code. The main innovative points achieved in this work are i) a new thermal-hydraulic model is developed with a highly-accurate 3D core discretization plus an iterative process is presented to adjust the 3D bypass flow, ii) a control rod insertion occurrence -which data is obtained from a real PWR test- is used as a transient simulation, iii) two approaches are used for the propagation process: maximum response where the uncertainty and sensitivity analysis is performed for the maximum absolute response and index dependent where the uncertainty and sensitivity analysis is performed at each time step, and iv) RESTING MATLAB code is developed to automate the model generation process and, then, propagate the thermal-hydraulic uncertainty. The input uncertainty information is found in related literature or, if not found, defined based on expert judgment. This paper, first, presents the Gesellschaft für Anlagen und Reaktorsicherheit methodology to propagate the uncertainty in thermal-hydraulic macroscopic parameters and, then, shows the results when the methodology is applied to a PWR reactor.

• Journal of the Korean Electrochemical Society
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• v.3 no.4
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• pp.224-231
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• 2000

The exfoliation of graphite (layer) was progressed due to the irreversible insertion of PC molecules between graphene layers, when propylene carbonate (PC) solvent was used as the organic solvents. The problem could be mitigated by the replacement of PC by ethylene carbonate (EC). But, the freezing point of EC-based electrolyte increased due to the high freezing point of $EC(36.2^{\circ}C)$. Therefore, EC+PC mixed electrolyte is expected as a good organic electrolyte for lithium ion battery. The EC-based organic electrolyte containing PC within pertinent quantity can be expected to have high molar conductivity and reduced exfoliation of graphite layer. The dielectric constant and molar conductivity of $LiPF_6/PC+EC+DEC$ electrolyte was investigated with a variation in the PC content. The electrochemical properties of carbon electrode in the electrolyte were also investigated. Molar conductivity and dielectric constant increased linearly by increasing the PC volume fraction in the electrolyte. The results of charge-discharge test for carbon/electrolyte/Li cell indicated that the initial irreversible specific capacity(IIC) of MCMB-6-28s and MPCF3000 decreased by the addition of $0.83 vol\%$ of PC, but increased with PC content over than $0.83 vol\%$. In the case of MPCF3000 and PCG100 having less than $10 vol\%$ PC, IIC was lower than 50 mAh/g. The discharge specific capacities varied with carbon material, but did not vary with PC content in the electrolyte.