• Nuclear Engineering and Technology
• /
• v.54 no.12
• /
• pp.4560-4570
• /
• 2022

Dynamic fault tree (DFT) and its related research methods have received extensive attention in safety analysis and reliability engineering. DFT can perform reliability modelling for systems with sequential correlation, resource sharing, and cold and hot spare parts. A technical modelling method of DFT is proposed for modelling ship collision accidents and loss-of-coolant accidents (LOCAs). Qualitative and quantitative analyses of DFT were carried out using the cutting sequence (CS)/extended cutting sequence (ECS) method. The results show nine types of dynamic fault failure modes in ship collision accidents, describing the fault propagation process of a dynamic system and reflect the dynamic changes of the entire accident system. The probability of a ship collision accident is 2.378 × 10^-9 by using CS. This failure mode cannot be expressed by a combination of basic events within the same event frame after an LOCA occurs in a marine nuclear reactor because the system contains warm spare parts. Therefore, the probability of losing reactor control was calculated as 8.125 × 10^-6 using the ECS. Compared with CS, ECS is more efficient considering expression and processing capabilities, and has a significant advantage considering cost.

• Korea Trade Review
• /
• v.47 no.3
• /
• pp.211-232
• /
• 2022

Due to the impact of the public health event COVID-19 epidemic, the Chinese futures market showed "Black Swan". This has brought the unpredictable into the economic environment with many commodities falling by the daily limit, while gold performed well and closed in the sunshine(Yan-Li and Rui Qian-Wang, 2020). Volatility is integral part of financial market. As an emerging market and a special precious metal, it is important to forecast return of gold futures price. This study selected data of the SHFE gold futures returns and conducted an empirical analysis based on the generalised autoregressive conditional heteroskedasticity (GARCH)-type model. Comparing the statistics of AIC, SC and H-QC, ARMA (12,9) model was selected as the best model. But serial correlation in the squared returns suggests conditional heteroskedasticity. Next part we established the autoregressive moving average ARMA-GARCH-type model to analysis whether Volatility Clustering and the leverage effect exist in the Chinese gold futures market. we consider three different distributions of innovation to explain fat-tailed features of financial returns. Additionally, the error degree and prediction results of different models were evaluated in terms of mean squared error (MSE), mean absolute error (MAE), Theil inequality coefficient(TIC) and root mean-squared error (RMSE). The results show that the ARMA(12,9)-TGARCH(2,2) model under Student's t-distribution outperforms other models when predicting the Chinese gold futures return series.

• Korean Journal of Agricultural Science
• /
• v.50 no.4
• /
• pp.799-808
• /
• 2023

Globally, abnormal climate phenomena have led to an increase in rainfall intensity, consequently causing a rise in flooding-related damages. Agricultural areas, in particular, experience significant annual losses every year due to a lack of research on flooding in these regions. This study presents a comprehensive analysis of the flood event that occurred on July 16, 2017, in the agricultural area situated in Sindaedong, Heungdeok-gu, Cheongju-si. To achieve this, the EPA (United States Environmental Protection Agency) Storm Water Management Model (SWMM) was employed to generate runoff data by rainfall information. The produced runoff data facilitated the identification of flood occurrence points, and the analysis results exhibited a strong correlation with inundation trace maps provided by the Ministry of the Interior and Safety (MOIS). The detailed output of the SWMM model enabled the extraction of time-specific runoff information at each inundation point, allowing for a detailed understanding of the inundation status in the agricultural area over different time frames. This research underscores the significance of utilizing the SWMM model to simulate inundation in agricultural areas, thereby validating the efficacy of flood alerts and risk management plans. In particular, the integration of rainfall data and the SWMM model in flood prediction methodologies is expected to enhance the formulation of preventative measures and response strategies against flood damages in agricultural areas.

• Journal of the Korean Society of Safety
• /
• v.36 no.3
• /
• pp.74-80
• /
• 2021

Korea Atomic Energy Research Institute (KAERI) has been operating an integral effects test facility, the Advanced Thermal-Hydraulic Test Loop for Accident Simulation (ATLAS), according to APR1400 for transient experimental and design basis accident simulation. Moreover, based on the experimental data, the domestic standard problem (DSP) program has been conducted in Korea to validate system codes. Recently, through DSP-05, the performance of the passive auxiliary feedwater system (PAFS) in the event of multiple steam generator tube rupture (MSGTR) has been analyzed. However, some errors exist in the reference input model distributed for DSP-05. Furthermore, the calculation results of the heat loss correlation for the secondary system presented in the technical report of the reference indicate that a large difference is present in heat loss from the target value. Thus, in this study, the reference model is corrected using the geometric information from the design report and drawings of ATLAS. Additionally, a new heat loss correlation is suggested by fitting the results of the heat loss tests. Herein, MSGTR-PAFS accident analysis is performed using MARS-KS 1.5 with the improved model. The steady-state calculation results do not significantly differ from the experimental values, and the overall physical behavior of the transient state is properly predicted. Particularly, the predicted operating time of PAFS is similar to the experimental results obtained by the modified model. Furthermore, the operating time of PAFS varies according to the heat loss of the secondary system, and the sensitivity analysis results for the heat loss of the secondary system are presented.

• Korean Journal of Psychosomatic Medicine
• /
• v.29 no.2
• /
• pp.191-198
• /
• 2021

Objectives : This study was designed to investigate the correlation between defense mechanism and posttraumatic stress disorder in burn patients. Methods : We recruit 40 burn patients and we evaluate sociodemographic characteristics, characteristics related to burn, korean version of Impact of Event Scale-Revised (IES-R), Korean Version of Center for epidemiologic studies depression scale (CES-D) and Ewha Defense Mechanisms Test (EDMT). Multiple regression analysis was performed to evaluate the correlation between EDMT score and IES-R score. Results : Factor 2 of EDMT which consists of Ego-expansion subjects was significantly correlate with IER-S score. In factor 2, Controlling (β=-0.299, p<0.05), Sublimation (β=-0.276, p<0.05) is significantly correlate with IER-S score. Conclusions : Some subjects of defense mechanism was significantly correlate with IES-R score. it might be helpful to understand defense mechanism for the posttraumatic stress disorder in burn patients.

• The Journal of the Korean bone and joint tumor society
• /
• v.12 no.1
• /
• pp.30-36
• /
• 2006

Purpose: Epitheliod sarcoma is an obscure clinical entity. This study analyzes the correlation between the clinical course and the AJCC stage, presence of residual tumor and ezrin-expression. Materials and Methods: Twenty-three cases of epithelioid sarcoma were eligible. All the cases had operation. Fifteen cases had systemic chemotherapy and 6 cases had adjuvant radiotherapy. Immumohistochemical analysis was done for 15 cases. Analyzed factors were initial stage, adjuvant treatment, local recurrence, residual tumor immumohistochemical results and surgical margin. Results: The event free survival rate of 15 stage II, III cases was 47.4% at 129 months. The actual survival rate of 8 stage IV cases was 37.5% at 80 months. The presence of residual tumor tissue on re-excision specimen showed statistical significance on event free survival rate(P=0.03). Adjuvant therapy showed no impact on outcome. The stage IV and locally recurrent cases had a positive relation with Ezrin-positivity. Conclusion: Residual tumor showed correlation in the outcome of epitheliod sarcoma. Chemotherapy and radiation therapy did not affect the outcome. Further case collection and analysis is needed for the significance between Ezrin expression and clinical behavior.

• Atmosphere
• /
• v.25 no.2
• /
• pp.309-322
• /
• 2015

The objective of this study is to evaluate the impact of the high resolution topographies and landuses data on simulated meteorological variables (wind speed at 10 m, temperature at 2 m and relative humidity at 2 m) in WRF. We compare the results with WRF simulation using each resolution of the topographies and landuses, and with 37 AWS observation data on the Seoul metropolitan regions. According to results of using high-resolution topography, WRF model gives better topographical expression over domain. And we can separate more detail (Low intensity residential, high intensity residential, industrial or commercial) using high resolution landuses data. The result shows that simulated temperature and wind speed are generally higher than AWS observation data. However, simulation trend with temperature, wind speed, and relative humidity are similar to observation data. The reason for that is that the high precipitation event occurred in CASE 1 and 2. Temperature have correlation of 0.43~0.47 and standard deviation of $2.12{\sim}2.28^{\circ}C$ in CASE 1, while correlation of more than 0.8 and standard deviation of $3.05{\sim}3.18m\;s^{-1}$ in CASE 2. In case of wind speed, correlation have lower than 0.5 and Standard Deviation of $1.88{\sim}2.34m\;s^{-1}$ in CASE 1 and 2. In statistical analysis shows that using highest resolution (U01) results are more close to the AWS observation data. It can be concluded that the topographies and landuses are important factor that affect model simulation. However, the tendency to always use high resolution topographies and landuses data appears to be unjustified, and optimal solution depends on the combination of scale effect and mechanisms of dynamic models.

• Economic Analysis
• /
• v.27 no.1
• /
• pp.1-36
• /
• 2021

Given the US dollar's status as a global safe haven, global factors, such as US monetary policy, may have considerable impacts on financial markets in other countries. Regarding such hypothesis, this paper looked at the impacts of US monetary policy on domestic bond and FX swap markets through an event study. According to our analysis, US monetary policy had significant positive impacts on domestic interest rates. In particular, it turned out to have bigger impacts on long-term products with high term premiums. By period, the correlation between US monetary policy and domestic interest rates was not significant before the financial crisis, but was clearly positive after the crisis. The US conventional monetary policy was seen to have big impacts on short-term and medium-term KTB yields, while its unconventional monetary policy had major impacts on long-term KTB yields. Moreover, FX swap rates reacted very sensitively to US monetary policy shocks before the financial crisis, while they did not show any significant reactions after the crisis. This suggests that, in line with the covered interest rate parity, the impact of US monetary policy shocks was transmitted to domestic financial markets mainly through swap rate adjustments before the global financial crisis, but through the changes in domestic interest rates during the post-crisis period.

• Korean Journal of Human Ecology
• /
• v.17 no.6
• /
• pp.1181-1195
• /
• 2008

This study based on Sa rye pyun ram(四禮便覽) by Lee Jae which are Chosun Dynasty book about the rules in a wedding ceremony. And the research examine into the understand how to the procedure, the true meanings about korea traditional wedding and general opinion of wedding custom. The instrument is the questionnaires, which is analyzed finally through data processing with 129 of wedding venders. The data analyze by making use of SPSS program were frequency analysis, ANOVA, $x^2$-test, pearson's correlation analysis. The summary of a result is as follows. First, the wedding awareness of wedding venders about Eou hon(議婚) is on a high level but Nab chae(納采) is low. Second, wedding venders are knowing with "Hon suh ji(letter), four season cloth, blue-red satin, shell goods" in a Nab peau(納幣) and with "jujube, beef, chicken, Gu jel pan(accompaniment to a drink), alcohol in a Peau back(幣帛). Third, wedding venders are answered that acceded to "Peau back" and "traditional wedding ceremony' but needed no "gifts & cloths for wedding". Forth, the understanding of wedding procedure (婚禮節次) is on a low, especially Bon ray(本禮).

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.13 no.2
• /
• pp.51-59
• /
• 2017

Steam jets ejected from a rupture zone of high energy pipes may cause damage to adjacent structures. This event could lead to more serious accidents in nuclear power plants. Therefore, to prevent serious accidents, high energy pipes of nuclear power plants are designed according to the ANSI / ANS 58.2 technical standard. However, the US Nuclear Regulatory Commission (USNRC) has recently pointed out non-conservatism in existing high energy pipe fracture evaluation methods, and required the assessment of the unsteady load of the jet caused by a potential feedback mechanism as well as the impact range of steam jet, the jet impact loads and the blast wave effects at the initial breakage stage. The potential feedback mechanism refers to a phenomenon in which a vortex formed by impingement jets amplifies vortex itself and induces jet vibration in a shear layer. In this study, CFD methodology using the LES turbulence model is established and numerical analysis is carried out to evaluate the dynamic behavior of impingement jets and the potential feedback mechanism during jet impingement. Obtained results have been compared with an empirical correlation and experiment.