• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.12
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• pp.99-108
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• 2015

The embedded microcontroller which is operated by the logic gates synchronized on the clock pulse, is gradually used as main controller of mission-critical systems. Severe electrical situations such as high voltage/frequency surge may cause malfunctioning of the clock source. The tolerant system operation is required against the various external electric noise and means the robust design technique is becoming more important issue in system clock failure problems. In this paper, we propose on-chip backup clock change architecture for the automatic clock failure detection. For the this, we adopt the edge detector, noise canceller logic and glitch-free clock changer circuit. The implemented edge detector unit detects the abnormal low-frequency of the clock source and the delay chain circuit of the clock pulse by the noise canceller can cancel out the glitch clock. The externally invalid clock source by detecting the emergency status will be switched to back-up clock source by glitch-free clock changer circuit. The proposed circuits are evaluated by Verilog simulation and the fabricated IC is validated by using test equipment electrical field radiation noise

• Journal of Families and Better Life
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• v.9 no.1 s.17
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• pp.113-130
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• 1991

The purpose of the present study was to describe the expectation and the performance on the housework socialization of the age homemakers and to ivestigate their relationships to the demographic characteristics and the influences of other related factors. 344 homemakers who were older than 45 years and were living in Chunlabuk-do, 1990 were sampled for this study. The data were collected by questionnaire designed by the researcher and analyzed by using frequency, one-way ANOVA analysis of variance, t-test, and multiple regression analysis. The major findings were as follows ; 1) The aged homemakers' housework socialization score was higher than the average, The score of the expectation was higher than one of the present performance. Scores for the utilization of the household equipments and the utilization of employes's services were higer comparing to those for other variables of the performance and the expectation respectively. 2) There was the significant differences in the each of the present performance varibles related to th housework socialization among the following demographic varables ; Age of homemakers, years of marriage, education, residence area, types of housing, monthly income, and level of housework equipment possession. 3) There was the significant differences in the expectation on the housework socialazation among the following variables ; age of homemakers, years of marriage, education, monthly income, and types of housing. The significant differences were found in the utilization of grouped, the utilization of the commodity, the utilization of the household equipments as subvariables of housework socialization, among age of homemakers, years of marriage, and level of education, The significant differences were found in the utilization of employee's services among age of homemakers, types of family, and level of health. 4) The level of education and monthly income significantly influenced on the present performance of the house work socialization. Years of marriage, significantly influenced on the utilization of grouped, education on the utilization of the commodity.(the utilization of the producted materials) and the utilization of employee's services and monthly income on the utilization of the household equipments (the utilization of the household appliances, and equipments). The years of marriage and education significantly influenced on the expectation on the housework socialization in the order, Age of homemakers and years of marriage significantly influenced on the utilization of grouped, the utilization of the commodity, the utilization of employee's services and age of homemakers and monthly income on the utilization of the household equipments.

• Journal of the Korean Institute of Gas
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• v.23 no.6
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• pp.61-66
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• 2019

Unlike NG supplied through pipes, LPG is mainly used for independent storage of cylinders or small storage tanks. As LPG is widely used in islands and underdeveloped areas, accidents due to neglect of safety management are high. Houses and businesses that have LPG accidents are likely to be damaged due to relatively high population density. Therefore, the necessity of strengthening the safety management of LPG is constantly raised. Accordingly, in 1996, Korea Gas Safety Corporation conducted an LPG leak test. In this study, based on the 96-year experiment, the gas leakage measurement of LPG vessels was conducted by adding several conditions such as outside temperature and pipe condition. Through this, the trend of leakage for various scenarios of LPG leakage was examined. In the case of a gas leak, when the article which may affect the pressure such as a regulator is not connected, the leakage amount is greatly changed by the outside air temperature, and when the regulator is fastened, the influence of the outlet pressure is large. It is expected that the experiment can be used as basic data for determining gas accidents and leakages that may occur later.

• Journal of Radiation Protection and Research
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• v.36 no.2
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• pp.79-85
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• 2011

OThe purpose of this article was to measure and compare the value of the metal artifact reduction (MAR) algorithm by Dual energy(kVp switching) CT (Computed Tomography) for non using MAR and we introduced new variable Dual energy CT applications through a clinical scan. The used equipment was GE Discovery 750HD with Dual-Energy system(kVp switching). CT scan was performed on the neck and abdomen area subject for patients. Studies were from Dec 20 2010 to Feb 10 2011 and included 25 subject patients with prosthesis. We were measured the HU (Hounsfield Unit) and noise value at metal artifact appear(focal loss of signal and white streak artifact area) according to the using MAR algorithm. Statistical analyses were performed using the paired sample t-test. In patient subject case, the statistical difference of showing HU was p=0.01 and p=0.04 respectively. At maximum black hole artifact area and white streak artifact area according to the using MAR algorithm. However noise was p=0.05 and p=0.04 respectively; and not the affected black hole and white streak artifact area. Dual Energy CT with the MAR algorithm technique is useful reduce metal artifacts and could improve the diagnostic value in the diagnostic image evaluation of metallic implants area.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.6
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• pp.1117-1123
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• 2016

Roller-Compacted Concrete Pavement (RCCP) is a type of pavement that shares conventional concrete pavement material characteristics and asphalt pavement construction characteristics. Even though RCCP is compacted in the same way and have similar aggregate gradation to asphalt pavements, its materials and structural performance properties are similar to those of conventional concrete pavement. With cement hydration and aggregate interlock, Roller-Compacted Concrete or RCC can provide strength properties equal to those of conventional concrete with low cement content. Therefore, compaction ratio of RCC can highly influence on its strength. In general, 95% of compaction ratio is required for proper strength development. RCC strength can be highly influenced by compaction energy which depends on compaction equipment and compaction method. Therefore, it is necessary to analyze the relationship between compressive strength and compaction ratio of RCC. RCCP specimens were produced at different compaction ratio by using different compaction methods and energies. The compaction ratio was defined by the ratio of the specimen's dry density and its maximum dry density. The maximum dry density was obtained from Modified Proctor test. 28 days compressive strength corresponding to each compaction ratio case was tested. Finally, the relationship between compressive strength and compaction ratio can be analyzed. For application of roller-compacted concrete in domestic construction site, the relationship is important for field compaction management.

• Geomechanics and Engineering
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• v.16 no.3
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• pp.273-284
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• 2018

A detailed understanding of the mechanical behaviors for crushed coal rocks after grouting is a key for construction in the broken zones of mining engineering. In this research, experiments of grouting into the crushed coal rock using independently developed test equipment for solving the problem of sampling of crushed coal rocks have been carried out. The application of uniaxial compression was used to approximately simulate the ground stress in real engineering. In combination with the analysis of crack evolution and failure modes for the grouted specimens, the influences of different crushed degrees of coal rock (CDCR) and solidified grout strength (SGS) on the mechanical behavior of grouted specimens under uniaxial compression were investigated. The research demonstrated that first, the UCS of grouted specimens decreased with the decrease in the CDCR at constant SGS (except for the SGS of 12.3 MPa). However, the UCS of grouted specimens for constant CDCR increased when the SGS increased; optimum solidification strengths for grouts between 19.3 and 23.0 MPa were obtained. The elastic moduli of the grouted specimens with different CDCR generally increased with increasing SGS, and the peak axial strain showed a slightly nonlinear decrease with increasing SGS. The supporting effect of the skeleton structure produced by the solidified grouts was increasingly obvious with increasing CDCR and SGS. The possible evolution of internal cracks for the grouted specimens was classified into three stages: (1) cracks initiating along the interfaces between the coal blocks and solidified grouts; (2) cracks initiating and propagating in coal blocks; and (3) cracks continually propagating successively in the interfaces, the coal blocks, and the solidified grouts near the coal blocks. Finally, after the propagation and coalescence of internal cracks through the entire specimens, there were two main failure modes for the failed grouted specimens. These modes included the inclined shear failure occurring in the more crushed coal rock and the splitting failure occurring in the less crushed coal rock. Both modes were different from the single failure mode along the fissure for the fractured coal rock after grouting solidification. However, compared to the brittle failure of intact coal rock, grouting into the different crushed degree coal rocks resulted in ductile deformation after the peak strength for the grouted specimens was attained.

• Journal of Advanced Navigation Technology
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• v.16 no.2
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• pp.360-366
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• 2012

In the power distribution panel installed in airport or industrial facilities, MCCB has been used for main switch and ELCB for branch switch to perform human body and leakage-inducing fire protection as well as overcurrent and short circuit protection. Especially for the airport panel, increase in accident protection is needed for stable power supply due to rapid modernization with fast-growing users, higer capacity and diversification of equipment, the increase of power capacity and the breaker made slim is a main issue for now because the issue for installation space is standing out by making panel with two-row arrangement connection method, etc. due to a many use of branch ELCBs. In this thesis, we designed arc extinguishing mechanism, considered movement direction change of contact in mechanism design. Also, we designed the breaker to work stably in case of miniaturization of leakage detection circuit and reverse connection. We conducted short circuit test to verify its function and developed the breaker that can be improved protection against accidental current with slim size operating leakage function when reverse connection to help solve the problem in using space that is increasing in the airport distribution panel.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.6
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• pp.484-492
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• 2016

The turbine is an important component and has a significant impact on the thermodynamic efficiency of the organic Rankine cycle. A precise preliminary design is essential to developing efficient turbines. In addition, performance analysis and structural analysis are needed to evaluate the performance and structural safety. However, there are only a few exclusive studies on the development process of the radial inflow turbines for the organic Rankine cycle (ORC). In this study, a preliminary design of the ORC radial inflow turbine was performed. Subsequently, the performance and structural analysis were also carried out. The RTDM, which was developed as an in-house code, was used in the preliminary design process. The results of the performance analysis were found to be in good agreement with target performances. Structural analysis of the designed turbine was also carried out in order to determine whether the material selection for this study is suitable for the flow conditions of the designed turbine, and it was found that the selected aluminum alloy is suitable for the designed turbine. However, the reliability of the preliminary design algorithms and numerical methods should be strictly verified by an actual experimental test.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.6
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• pp.737-743
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• 2014

This paper dealt with a retrofit high power LED searchlight to replace conventional 1kW halogen searchlights. The design specification meets KDS 6230-1046-1 and KS V 8469. An optical lens with the beam angle of $6^{\circ}$ was used to meet the luminous intensity of 800,000cd at $0^{\circ}$ in horizontal line. Heat dissipation of the LED searchlight adopted a free air cooling type which does not use a fan or a heat-pipe. From the test results, power consumption of the prototype LED searchlight was 148W which was saved by 85% comparing a halogen searchlight of 1kW. Luminous intensity was 945,000cd at $0^{\circ}$ in horizontal line, satisfying KS V 8469. Luminous efficacy was improved by 4.7 times higher than that of the halogen searchlights. Beam angle, color temperature, and color rendering index(CRI) was $5.4^{\circ}$, 5,500K, and 70, respectively. Surface temperature of the LED searchlight was below $60^{\circ}C$ and surrounding temperature of the SMPS installed inside was below $50^{\circ}C$ which were satisfied with the IEC 60092-306.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.8
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• pp.767-774
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• 2010

In a passive-type PEMFC stack, axial fans operate to supply both oxidant and coolant to cathode side of the stack. It is possible to make a simple system because the passive-type PEMFC stack does not require additional cooling equipment. However, the performance of a cooling system in which water is used as a coolant is better than that of the air-cooling system. To ensure system reliability, it is essential to make cooling system effective by adopting an optimal stack design. In this study, a numerical investigation has been carried out to identify an optimum cooling strategy. Various channel configurations were applied to the test section. The passive-type PEMFC was tested by varying airflow rate distribution at the cathode side and external heat transfer coefficient of the stack. The best cooling performance was achieved when a channel with thick ribs was used, and the overheating at the center of the stack was reduced when a case in which airflow was concentrated at the middle of the stack was used.