• Journal of Chest Surgery
• /
• v.44 no.5
• /
• pp.323-331
• /
• 2011

Background: Myocardial revascularization in patients with renal insufficiency is challenging to the cardiac surgeon, irrespective of utilizing extracorporeal circulation. This study aimed to compare the number of bypass grafts and the mid-term results and to evaluate independent survival predictors in patients with renal insufficiency undergoing on-pump or off-pump myocardial revascularization. Materials and Methods: We retrospectively analyzed the data of 103 patients with renal insufficiency, who had isolated myocardial revascularization between January 1999 and January 2009. The patients were divided into two groups, the on-pump group and the off-pump group. Results: The off-pump group received a significantly greater number of distal arterial grafts than the on-pump group. However, the mean number of total grafts, the degree of complete revascularization, and survival rate of the patients were not significantly different between the two groups. Multivariate analysis showed the independent predictors for reduced mid-term survival were the number of total grafts and postoperative periodic renal replacement therapy. Off-pump myocardial revascularization does not decrease the number of bypass grafts or influence on the mid-term results for patients with renal insufficiency, compared to on-pump myocardial revascularization. Conclusion: Myocardial revascularization with a large number of total grafts has a beneficial effect on survival in patients with renal insufficiency, irrespective of utilizing extracorporeal bypass.

• Journal of Korea Water Resources Association
• /
• v.35 no.3
• /
• pp.275-284
• /
• 2002

In this study, a method of random resampling of residuals from stochastic models such as the Monte-Carlo model, the lag-one autoregressive model(AR(1)) and the periodic lag-one autoregressive model(PAR(1)), has been adopted to generate a large number of long traces of annual and monthly steamflows. Main advantage of this resampling scheme called the Bootstrap method is that it does not rely on the assumption of population distribution. The Bootstrap is a method for estimating the statistical distribution by resampling the data. When the data are a random sample from a distribution, the Bootstrap method can be implemented (among other ways) by sampling the data randomly with replacement. This procedure has been applied to the Yongdam site to check the performance of Bootstrap method for the streamflow generation. and then the statistics between the historical and generated streamflows have been computed and compared. It has been shown that both the conventional and Bootstrap methods for the generation reproduce fairly well the mean, standard deviation, and serial correlation, but the Bootstrap technique reproduces the skewness better than the conventional ones. Thus, it has been noted that the Bootstrap method might be more appropriate for the preservation of skewness.

• Transactions of Materials Processing
• /
• v.27 no.6
• /
• pp.370-378
• /
• 2018

Cold forging, carried out at room temperature, leads to high dimensional accuracy and excellent surface integrity as compared to other forging methods such as warm and hot forgings. In the cold forging process, WC-Co (Tungsten Carbide-Cobalt) alloy is the mainly used material as a core dies because of its superior hardness and strength as compared to other structural materials. For cold forging, die life is the most significant factor because it is directly related to the manufacturing cost due to periodic die replacement in mass production. To investigate die life of WC-Co alloy for cold forging, mechanical properties such as strength and fatigue are essentially necessary. Generally, uniaxial tensile test and fatigue test are the most efficient and simplest testing method. However, uniaxial tension is not efficiently application to WC-Co alloy because of its sensitivity to alignment of the specimen due to its brittleness and difficulty in thread machining. In this study, shape of specimen, tools, and testing methods, which are appropriate for uniaxial tensile test for WC-Co alloy, are proposed. The test results such as Young's modulus, tensile strength and stress-strain curves are compared to those in previous literature to validate the proposed testing methods. Based on the validation of test results it was concluded that the newly developed testing method is applicable to other cemented carbides like Titanium carbides with high strength and brittleness, and also can be utilized to carry out fatigue tests for further investigation on die life of cold forging.

• Korea Journal of Hospital Management
• /
• v.27 no.2
• /
• pp.34-43
• /
• 2022

Objective: Telemedicine service is gaining importance in remote military areas. This study aimed to explore the mediating effect of user satisfaction on the association between military telemedicine service's quality and customer loyalty. Methods: The research data comprised the results of a satisfaction survey on 1,116 military telemedicine satisfaction surveys conducted from November 1 to November 31, 2021. T-tests and ANOVA were analyzed to confirm the difference in satisfaction and loyalty according to the general characteristics of the study subjects. User satisfaction, customer loyalty, and mediating effects were analyzed using multiple linear regression analysis. Results: Among the study subjects, 458 were affiliated with the Army, 68 with the Navy, and 36 with the Air Force. Among the quality of telemedicine service, tangibility, reliability, and empathy affected user satisfaction while reliability and empathy affected customer loyalty. Since the standardized coefficient beta of empathy was 0.150 (P=0.018), it was confirmed that it significantly affected customer loyalty by mediating user satisfaction. Conclusion: The telemedicine service's quality affects users' satisfaction and customer loyalty. Moreover, there was the mediating effect of user satisfaction on the association between telemedicine service and customer loyalty. Therefore, the reliability and reliability of the current telemedicine service can be improved through the replacement of outdated equipment and performance improvement, expansion of medicines in telemedicine units, and improvement of medical services through periodic CS education to increase the customers' satisfaction and loyalty.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.1
• /
• pp.83-88
• /
• 2023

According to the Ministry of Employment and Labor's industrial accident death statistics, the number of accident deaths in the construction industry increased by 30 people year-on-year to 458, with 77.3% of the accident deaths aged 50 or older and 41.9% aged 60 or older. This study conducted and analyzed a survey to identify safety education, protective equipment, and safety consciousness for 68 elderly workers working at construction sites. As a result, the necessity of diversifying safety education using visual data was confirmed to reconsider the contradictory safety consciousness of elderly workers. It also confirmed the need to improve protective equipment, such as providing protective equipment suitable for individual bodies and periodic replacement, for workers who are passive in wearing protective equipment despite the high need for protective equipment.

• Journal of the Korean Geotechnical Society
• /
• v.26 no.12
• /
• pp.61-70
• /
• 2010

A series of shaking table tests were conducted to estimate the seismic performance of soft ground deposits improved by stone column. The amplification of acceleration, shear strain, and shear wave velocity were evaluated to compare the seismic response of unimproved ground deposits with that of improved ground deposits. From the test results, it was shown that the stone column can prevent large shear deformation in ground deposits. However, it was also found that the acceleration of improved ground deposits may be amplified more than that of unimproved ground deposits when it was subjected to short periodic seismic wave. The results suggest that it is necessary to perform the ground response analysis with model experiments for both unimproved and improved ground deposits to evaluate the effect of stone column on the seismic performance of improved ground deposits.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.6
• /
• pp.584-591
• /
• 2020

Reliability is an important factor in weapons systems. Low reliability causes the weapons system to fail to function properly, which directly leads to the weakening of combat capability. This paper classifies the structure of the 5.56 mm rifle, which is currently used by the Korean army, into a total of seven assemblies and describes the eight functions necessary for the rifle to operate normally. In addition, the concept of reliability was defined as the MRBF, and the Poisson process model and TTT plot were explained as a reliability analysis theory for the repair function system. Next, the field-data obtained by defining failure as the replacement of parts other than periodic exchange of parts were refined, and the reliability was analyzed by entering the refined field operation specifications into the Minitab program. As a result, the reliability of the rifle was determined to be 251.73. The assembly parts that required improvement was identified as the barrel, lower body, and butt stock assembly, and 10 detailed parts needed to be improved. Finally, the limits of the reliability analysis using the field-data currently available for small caliber firearms were considered.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.26 no.4
• /
• pp.636-643
• /
• 1999

Ectodermal dysplasia is a genetic birth defect in which at least abnormally develop two structures derived from the ectoderm. It is usually inherited in autosomal dominant or autosomal recessive pattern. Oral manifestations are oligodontia, anodontia, dysmorphic teeth(conical shape), decreased occlusal vertical dimension and alveolar bone. Extraoral signs may include decreased or absent sweat glands, sparse and fine hair, saddle nose, hearing loss and decreased production of body fluids including saliva. Most affected children require extensive dental treatment to restore their appearance and help the development of a positive self image. The patient's overclosed profile was due to a decreased vertical dimension. The use of overdenture is to preserve erupted teeth, to accomodate the newly constructed occlusal plane, to improve retention and stability of denture and to maintain the remaining alveolar bone. The restoration of vertical dimension improved the child's speech, swallowing, and eating. Growth continue until the age of approximately 18. As child grows, replacement dentures will have to be fabricated primarily to accomodate increasing vertical dimension and changing dentition. Implants may be indicated later if the alveolar bone is adequate. Periodic recall visits are advised, to monitor the dentures during periods of growth and development, and eruption of the permanent teeth.

• The Journal of the Convergence on Culture Technology
• /
• v.7 no.4
• /
• pp.479-490
• /
• 2021

As a part of Korean accounting reforms through the improvement of the accounting and audit related systems, the amendment bill of 'Act on External Audit of Stock Compamies's was passed in the Natinal Assembly plenary session in 2017, the amended act has been enforced except some regulations since the business year on November 1, 2018, and all the amended matters will be applied from the business year of 2024. The reasons for auditor designation in 2019 are 'pre-IPO' 331 companies, 220 periodic designation companies, 197 companies that had operating loss for three consecutive years, 112 companies with issues for administration, 108 companies with excessive debt ratio and 66 companies with no auditors. Regarding the reasons for the increase of auditor designation, 475 companies were increased in accordance with the new designation standard by the amended bill of Act on External Audit of Stock Companies, 114 companies were increased due to the abolition of the considered designation system of companies to be listed, and 90 companies were increased based on the increase of listed companies incorporated to issues for administration. In 2020, 462 companies had periodical designation (434 listed, 28 non-listed), adding 242 companies (110%) over a year. In terms of direct designation, 'pre-IPO' accounted for the most (362 companies), followed by '3 consecutive years of operating loss' (245 companies), then by companies with administration issues (133 companies), and CEO & largest sharholder replacement. Regarding the designation of auditors according to accounting firms in 2020, A group that includes(top 4) accounting firms(Samil, Samjeong, Hanyeong, Anjin) had 526 companies(34.6%), which ia an incease of 72 companies from the previous year(454 companies, 37.1%), but the weight decreased by 2.5%.

• Korean Chemical Engineering Research
• /
• v.55 no.3
• /
• pp.322-331
• /
• 2017

District heating was first introduced in Korea in 1985. As the service life of the underground thermal piping network has increased for more than 30 years, the maintenance of the underground thermal pipe has become an important issue. A variety of complex technologies are required for periodic inspection and operation management for the maintenance of the aged thermal piping network. Especially, it is required to develop a model that can be used for decision making in order to derive optimal maintenance and replacement point from the economic viewpoint in the field. In this study, the analysis was carried out based on the repair history and accident data at the operation of the thermal pipe network of five districts in the Korea District Heating Corporation. A failure probability model was developed by introducing statistical techniques of qualitative analysis and binomial logistic regression analysis. As a result of qualitative analysis of maintenance history and accident data, the most important cause of pipeline damage was construction erosion, corrosion of pipe and bad material accounted for about 82%. In the statistical model analysis, by setting the separation point of the classification to 0.25, the accuracy of the thermal pipe breakage and non-breakage classification improved to 73.5%. In order to establish the failure probability model, the fitness of the model was verified through the Hosmer and Lemeshow test, the independent test of the independent variables, and the Chi-Square test of the model. According to the results of analysis of the risk of thermal pipe network damage, the highest probability of failure was analyzed as the thermal pipeline constructed by the F construction company in the reducer pipe of less than 250mm, which is more than 10 years on the Seoul area motorway in winter. The results of this study can be used to prioritize maintenance, preventive inspection, and replacement of thermal piping systems. In addition, it will be possible to reduce the frequency of thermal pipeline damage and to use it more aggressively to manage thermal piping network by establishing and coping with accident prevention plan in advance such as inspection and maintenance.