• Nuclear Engineering and Technology
• /
• v.27 no.5
• /
• pp.701-709
• /
• 1995

The realistic discharge coefficient for the critical How model of RELAP5/AOD3/KAERI are determined for the subcooled and too-phase critical flow by assessments of nine MARVIKEN Critical flew Test(CFT). The selected test runs include a high initial subcooling and large nozzle aspect rat-io(L/D). The code assessment results show that RELAP5/MOD3/KAERI over-predicts the subcooled critical flow and under-predicts the two-phase critical flow. Using these result, the realistic discharge coefficients of critical flow models are quantified by an iterative method. The realistic discharge coefficients are determined to be 0.89 for the subcooled critical How and 1.07 for the two-phase critical flow, and the associated standard deviations are 0.0349 and 0.1189, respectively. The results obtained from this study can be applied to calculate the realistic system response of Large Break Loss of Coolant Accident and to evaluate the realistic Emergency Core Cooling System performance.

• Explosives and Blasting
• /
• v.38 no.4
• /
• pp.16-25
• /
• 2020

Multi-setting smart-investigation of the ground and large uncharged hole boring (MSP) method to reduce the blast-induced vibration in a tunnel excavation is carried out over 50m of long-distance boring in a horizontal direction and thus has been accompanied by deviations in boring alignment because of the heavy and one-directional rotation of the rod. Therefore, the deviation has been adjusted through the boring machine's variable setting rely on the previous construction records and expert's experience. However, the geological characteristics, machine conditions, and inexperienced workers have caused significant deviation from the target alignment. The excessive deviation from the boring target may cause a delay in the construction schedule and economic losses. A deep learning-based prediction model has been developed to discover an ideal initial setting of the MSP machine. Dropout, early stopping, pre-training techniques have been employed to prevent overfitting in the training phase and, significantly improved the prediction results. These results showed the high possibility of developing the model to suggest the boring machine's optimum initial setting. We expect that optimized setting guidelines can be further developed through the continuous addition of the data and the additional consideration of the other factors.

• The Journal of Korean Academy of Prosthodontics
• /
• v.43 no.3
• /
• pp.306-313
• /
• 2005

Statement of problem. There have been many studies about marginal discrepancy of single restorations made by various systems and materials. But most of statistical inferences are not definite because of sample size, measurement number, measuring , instruments, etc. And there have been few studies about the marginal fit of Computer-aided Cercon crowns. Purpose. The purpose of this study was to compare the marginal fit of the anterior single restorations made using computer-aided milled Cercon crowns with metal-ceramic restorations and to obtain more accurate information by using a large enough sample size and by making sufficient measurements per specimen. Material and methods. The in vitro marginal discrepancies of computer-aided milled Cercon crowns and control groups (metal ceramic crowns) were evaluated and compared. The crowns were made from one extracted maxillary central incisor prepared by milling machine. 30 crowns per each system were fabricated. Measurements of a crown were recorded at 50 points that were randomly selected for marginal gap evaluation. Parametric statistical analysis was performed for the results. Results. The means and standard deviations of the marginal fit were 85$\pm$22$\mu$m for the control group and 91$\pm$15$\mu$m for the Cercon crowns. The t-test of the marginal discrepancies between Cercon crowns and metal-ceramic crowns were performed. Significant differences were not found between groups (P=0.230>.05). Based on the criterion of 120$\mu$m as the limit of clinical acceptability, the mean marginal fits of Cercon crowns and metal-ceramic crowns were acceptable. Conclusion. Within the limitations of this in vitro study, the following conclusions were drawn: 1. Mean gap dimensions and standard deviations at the marginal opening for maxillary incisal crowns were 85$\pm$22$\mu$m for the control (metal-ceramic crowns), 91$\pm$15$\mu$m for Cercon crowns. 2. The Cercon crowns showed slightly larger marginal gap discrepancy than the control but marginal gap between Computer-aided milled Cercon crowns and metal ceramic crowns did not showed significant difference (P>.05). 3. The Cercon crowns and metal ceramic crowns showed clinically acceptable marginal discrepancy.

• Nuclear Engineering and Technology
• /
• v.26 no.1
• /
• pp.126-139
• /
• 1994

Best-estimate thermal-hydraulic codes, CATHARE2 V1.2 and RELAP5/MOD3, hate been assessed against the BETHSY 6.2 tc six-inch cold leg break loss-of-coolant accident (LOCA) test. Main objective is to analyze the overall capabilities of the two codes on physical phenomena of concern during the small break LOCA i.e. two-phase critical flow, depressurization, core water level de-pression, loop seal clearing, liquid holdup, etc. The calculation results show that the too codes predict well both in the occurrences and trends of major two-phase flow phenomena observed. Especially, the CATHARE2 calculations show better agreements with the experimental data. However, the two codes, in common, show some deviations in the predictions of loop seal clearing, collapsed core water level after the loop seal clearing, and accumulator injection behaviors. The discrepancies found from the comprision with the experimental data are larger in the RELAP5 results than in the CATHARE2. To analyze the deviations of the two code predictions in detail, several sensitivity calculations have been performed. In addition to the change of two-phase discharge coefficients for the break junction, fine nodalization and some corrections of the interphase drag term are made. For CATHARE2, the change of interphase drag force improves the mass distribution in the primary side. And the prediction of SG pressure is improved by the modification of boundary conditions. For RELAP5, any single input change doesn't improve the whole result and it is found that the interphase drag model has still large uncertainties.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.36 no.3
• /
• pp.204-208
• /
• 1991

Five models for net radiation estimation reported by Linacre(1968), Berljand(1956), Nakayama et al. (1983), Chang (1970) and Doorenbos et al. (1977) were tested for the adaptability to Korea. A new model with effective longwave radiation term parameterized by air temperature, solar radiation and vapor pressure was formulated and tested for its accuracy. Above five models with original parameter values showed large absolute mean deviations ranging from 0.86 to 1.64 MJ/$m^2$/day. The parameters of the above five models were reestimated by using net radiation and meteorological elements measured in Suwon, Korea. These five models with new parameter values showed absolute mean deviations ranging from 0.74 to 0.88 MJ/$m^2$/day. The following model was newly formulated: Rn=(1- $\alpha$) Rs- $\sigma$ $T_{k}$$^{4}$ (0.0103 Exp (0 .0731 Rs) -0.0475 (equation omitted) +0 .2478) ($R^2$=0.997, n=63) where $\alpha$ =albedo, $\sigma$=Stefan-Boltzmann constant, Rs=solar radiation in MJ/$m^2$/day, Tk =air temperature in Kelvin and $e_{a}$=vapor pressure in mb. This model revealed 0.4988 MJ/$m^2$/day in absolute mean deviation when applied to an independent set of meteorological data.a.a.

• Journal of Korea Water Resources Association
• /
• v.56 no.12
• /
• pp.969-980
• /
• 2023

Since the 2000s, ensemble streamflow prediction (ESP) has been actively utilized in South Korea, primarily for hydrological forecasting purposes. Despite its notable success in hydrological forecasting, the original objective of enhancing water resources system management has been relatively overlooked. Consequently, this study aims to demonstrate the utility of ESP in water resources management by creating a simple hypothetical exercise for dam operators and applying it to actual multi-purpose dams in South Korea. The hypothetical exercise showed that even when the means of ESP are identical, different costs can result from varying standard deviations. Subsequently, using sampling stochastic dynamic programming (SSDP) and considering the capacity-inflow ratio (CIR), optimal release patterns were derived for Soyang Dam (CIR = 1.345) and Chungju Dam (CIR = 0.563) based on types W and P. For this analysis, Type W was defined with standard deviation equal to the mean inflow, and Type P with standard deviation ten times of the mean inflow. Simulated operations were conducted from 2020 to 2022 using the derived optimal releases. The results indicate that in the case of Dam Chungju, more aggressive optimal release patterns were derived under types with smaller standard deviations, and the simulated operations demonstrated satisfactory outcomes. Similarly, Soyang Dam exhibited similar results in terms of optimal release, but there was no significant difference in the simulation between types W and P due to its large CIR. Ultimately, this study highlights that even with the same mean values, the standard deviation of ESP impacts optimal release patterns and outcomes in simulation. Additionally, it underscores that systems with smaller CIRs are more sensitive to such uncertainties. Based on these findings, there is potential for improvements in South Korea's current operational practices, which rely solely on single representative values for water resources management.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.9A
• /
• pp.1285-1294
• /
• 1999

In this paper we consider the performance of TCP video traffic over ABR with Long-Range Dependent VBR traffic. As compressed coded video traffics are increasing rapidly over Internet, lots of studies are being done for transmitting those traffics efficiently using limited network resources. We consider here the transmitting video service over ABR service in ATM networks, especially satellite networks. CBR or VBR services are suggested in transmitting the video traffic in ATM Forum TM 4.0. But ABR service connection, which is considered as appropriate service for data traffic, can be established with a small amount of bandwidth, MCR (Minimum cell rate). Furthermore ABR service can control the source's transmitting rate using feedback mechanism. Using this feature ABR service can be used in some applications which can control their quality of services corresponding to network loads. Compressed video sources with MPEG-2 are used for Long-Range Dependent VBR traffic here. We model the compressed video source to resemble the MPEG-2 transport streams. These compressed video traffic streams are consisted of three different frames, I-frame, P-frame, and B-frame. So when a network are overloaded, we can control the quality of service using this traffic features. TCP Traffics over ABR need large buffers in ATM switch to satisfy their QoS with background VBR traffics, which have high deviations in bandwidth. Furthermore satellite ATM networks with large feedback delay need large buffers corresponding RTT delay. The performance comparisons among EFCI and ER switch (ERICA+) switches in the network circumstances described above were shown in this paper. We also considered the case with ON-OFF VBR traffics.

• Journal of Families and Better Life
• /
• v.25 no.5
• /
• pp.47-63
• /
• 2007

The purpose of this study was to verify the effectiveness of an internal family systems therapy program aimed at increasing ego-identity of middle-aged women. The objectives of this program were for middle-aged women to differentiate the self of internal systems, to identify constraints impinging on an individual part, to release constraints impinging on an individual part, to harmonize the internal family, and to enhance ego-identity. 31 middle-aged women ranged in age from 40 to 60. Two groups were identified as equivalents for the study in the pre-test. The program of this experimental group was implemented twice a week for 120 minutes per each session over a 6-week period. The pre-test(Aug. 29. 2006), the post-test(Oct. 20. 2006) and the follow-up test(Nov. 20. 2006) were implemented in order to verify the effectiveness of the programs. The participants who were absent more than three times in the program were excluded from the post-test and follow-up test. Eventually, the data in 31 persons(15 for the internal family systems therapy, 16 for the control group) were analyze to verify the effectiveness of the program. The instruments used in the study were the ego-identity scale. The data were analyzed using repeated measures ANOVA, simple main effect, post-hoc t-test, means and standard deviations. And the program was from Sep. 5. to Oct. 20. 2006. The findings of the study were as follows: The internal family systems therapy program had significant effects on enhancing the ego-identity. There was a large increase of the ego-identity in the intervention group, compared with control group at post treatment and follow-up after 1 month which indicated the continuity of intervention effect. However, in the control group, there were no changes according to the time.

• The Research Journal of the Costume Culture
• /
• v.25 no.2
• /
• pp.175-191
• /
• 2017

The purpose of this study is to analyze the body mass index(BMI) and foot characteristics of senior-generation women and to use those values to develop a standard shoe last for producing shoes that best fit the foot of senior-generation women. In order to develop a standard shoe last that reflects the BMI and foot characteristics of senior-generation women, I analyzed the morphometric characteristics of feet by conducting descriptive statistics for each item. The foot characteristics based on BMI were analyzed by conducting ANOVA and Duncan's tests via the foot's measured values. Subsequently, I developed a standard shoe last reflecting the BMI and the foot characteristics of senior-generation women by applying all those values. Senior-generation women showed significant differences among three groups based on BMI-normal weight, overweight, and obese-in all the items except for medial ball width and toe 5 angle. Through these values, I realized that as the value of the BMI becomes higher, the size of the foot becomes larger. This suggests that as a woman's weight increases or decreases, her shoes need to be replaced as well as her clothes. Deviations in the toe-side parts of the shoe could cause deformation of the foot. If someone keeps wearing shoes produced using a shoe last with a large deviation, she risks developing foot conditions like hallux valgus. This situation points to the need for shoe manufacture that utilizes a standard shoe last that reflects the BMI and foot characteristics of the senior generation.

• Journal of the Korean Home Economics Association
• /
• v.36 no.9
• /
• pp.49-62
• /
• 1998

This paper investigates the parenting stress of fathers who have preschooler. At first, a causal model constructed, including the parenting stress as a dependent variable and the psychological characteristics of paternal self-esteem and parenting efficacy as parameters. Based on the change of parenting stress, self-esteem and parenting efficacy according to various pertinent to fathers, the causal effect of various variables effecting on the paternal parenting stress is analyzed. The SPSS PC program was used for the statistical analysis, where fully exploited were frequencies, percentages, means, standard deviations, Cronbach α, one-way analysis(ANOVA), path analysis. The results can be summarized into 3 parts, in conclusion: 1) The younger a father is, the higher paternal self-esteem becomes. Paternal self-esteem trend was there, for a father who is a member of large family, and for a father whose education level is high, and for a father whose occupation is professional. Regarding parenting sense of competence, a father shows confidence when he has more income, more educated and less children. 2) The variable analysis effecting on the parenting stress dut to the paternal environment shows that a father feels more stress when his income is less and his spouse is working. The sub-factor analysis on the parenting stress shows that 'typical stress dut to the parenting' increases when his income is less and his spouse is working, and 'pressures pertaning to the parental role and distress' increases for a father with less income, working spouse, less educated and non-professional job. Further 'guilty to the parenting by others' shows higher for a father with less income and a working spouse. 3) The path analysis, which were performed to check the causality of the parenting stress dut to various variables, shows that the self-esteem and the parenting efficacy are significant factors directly effecting on the paternal parenting stress, and the job-satisfaction and marriage-satisfaction are significantly effecting on the parenting stress both directly and indirectly.