• Nuclear Engineering and Technology
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• v.19 no.2
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• pp.85-98
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• 1987

To analyze the aerosol dynamics in severe accidents of LMFBR, a new computer code entitled MCAD (Multicomponent Aerosol Dynamics) has been developed. The code can treat two component aerosol system using relative collision probability of each particles as sequences of accident scenarios. Coagulation and removal mechanisms incorporating Brownian diffusion and gravitational sedimentation are included in this model. In order to see the effect of particle geometry, the code makes use of the concept of density correction factor and shape factors. The code is verified using the experimental result of NSPP-300 series and compared to other code. At present, it fits the result of experiment well and agrees to the existing code. The input variables included are very uncertain. Hence, it requires uncertainty and sensitivity analysis as a supplement to code development. In this analysis, 14 variables are selected to analyze. The input variables are compounded by experimental design method and Latin hypercube sampling. Their results are applied to Response surface method to see the degree of regression. The stepwise regression method gives an insight to which variables are significant as time elapse and their reasonable ranges. Using Monte Carlo Method to the regression model of LHS, the confidence level of the results of MCAD and their variables is improved.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.5
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• pp.683-690
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• 2021

The ventilation system of the engine room of a ship is generally installed to supply the combustion air necessary for the internal combustion engine and to remove the heat source generated in the engine room, and it must satisfy the international standard (ISO 8861) for the design conditions and calculation standards for the ventilation of the ship engine room. The response delay of the ventilation system including the fire detector is affected by the airflow formed inside the area and the location of the fire detector. In this study, to improve the initial fire detection response speed of a fire detector installed on a fishing vessel and to maintain the sensitivity of the installed detector, the smoke behavior was simulated using the air flow field inside the engine room, the amount of combustion air in the internal combustion engine, and the internal pressure of the engine room as variables. Analysis of the simulation results showed that reducing the flow rate in the air flow field and increasing the vortex by reducing the internal pressure of the engine room and installing a smoke curtain would accelerate the rise of the ceiling of the smoke component and improve the smoke detector response speed and ventilation system.

• Journal of Ginseng Research
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• v.45 no.5
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• pp.546-554
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• 2021

Background: Diabetes mellitus and hypertension often occur together, amplifying cardiovascular disease (CVD) risk and emphasizing the need for a multitargeted treatment approach. American ginseng (AG) and Korean Red Ginseng (KRG) species could improve glycemic control via complementary mechanisms. Additionally, a KRG-inherent component, ginsenoside Rg3, may moderate blood pressure (BP). Our objective was to investigate the therapeutic potential of coadministration of Rg3-enriched Korean Red Ginseng (Rg3-KRG) and AG, added to standard of care therapy, in the management of hypertension and cardiometabolic risk factors in type-2 diabetes. Methods: Within a randomized controlled, parallel design of 80 participants with type-2 diabetes (HbA1c: 6.5-8%) and hypertension (systolic BP: 140-160 mmHg or treated), supplementation with either 2.25 g/day of combined Rg3-KRG + AG or wheat-bran control was assessed over a 12-wk intervention period. The primary endpoint was ambulatory 24-h systolic BP. Additional endpoints included further hemodynamic assessment, glycemic control, plasma lipids and safety monitoring. Results: Combined ginseng intervention generated a mean ± SE decrease in primary endpoint of 24-h systolic BP (-3.98 ± 2.0 mmHg, p = 0.04). Additionally, there was a greater reduction in HbA1c (-0.35 ± 0.1% [-3.8 ± 1.1 mmol/mol], p = 0.02), and change in blood lipids: total cholesterol (-0.50 ± 0.2 mmol/l, p = 0.01), non-HDL-C (-0.54 ± 0.2 mmol/l, p = 0.01), triglycerides (-0.40 ± 0.2 mmol/l, p = 0.02) and LDL-C (-0.35 ± 0.2 mmol/l, p = 0.06) at 12 wks, relative to control. No adverse safety outcomes were observed. Conclusion: Coadministration of Rg3-KRG + AG is an effective addon for improving BP along with attaining favorable cardiometabolic outcomes in individuals with type 2 diabetes. Ginseng derivatives may offer clinical utility when included in the polypharmacy and lifestyle treatment of diabetes. Clinical trial registration: Clinicaltrials.gov identifier, NCT01578837;

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.5
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• pp.279-286
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• 2021

In this study, we investigated the behavior characteristics of the L-type flange bolt connection, which is used to connect upper and lower flanges having L-type ring sections, by bolts. This connection is mainly used in domestic wind turbine structures, wherein it is a vital component as any imperfection could cause the collapse of the entire structural system. Therefore, understanding the behavior characteristics of the L-type flange bolt connection is imperative. In this study, the connection's response to external force was simulated using finite element (FE) analysis and the FE model was idealized to behave as a single L-type bolt flange. The variation in the bolt tension and the L-type flange stress were analyzed to understand the behavior characteristics of the connection. Moreover, the bolt-load function models proposed by Petersen, Schmidt/Neuper and VDI 2230, theoretically expressing a relation between bolt tension and external force, were compared to evaluate the suitability of the FE analysis and analyze the significant behavior characteristics of the connection. Furthermore, the changes in the bolt-load curve due to the variations in the partial dimensions of the L-type flange bolt connection were analyzed.

• Korean Journal of Construction Engineering and Management
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• v.22 no.6
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• pp.96-106
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• 2021

The PC structure based on the OSC (Off-Site Construction) is mentioned as a representative method of innovation in the construction industry that converts the existing construction environment from site-centered to factory production-transportation-site assembly. However, recent research on PC method has focused on improving the functions of subsidiary materials and improving the production system to increase productivity and institutional / policy R&D that can be universally applied to the life-cycle stage of ordering / design /construction is insufficient. In particular, the absence of standardized cost calculation standards makes it difficult to calculate and verify of objectified appropriate construction cost. So which is an obstacle to the activation of the PC method. In this study, the standards for construction costs of domestic and foreign PC method were surveyed and similar Construction Standard Production Rates were analyzed to confirm the product structure suitable for PC method. Subsequently, the construction procedures and input resources for each PC subsidiary materials were identified through on-site surveys to derive component for subsidiary materials, and the factors of change in the product according to the construction characteristics(height, weight of subsidiary material) were verified. As a result the standard product calculation system suitable for the site installation of the PC method for apartment was presented.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.541-549
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• 2018

This paper deals with the braking dynamic behavior of diesel electric locomotive pulling domestic cargo and passenger vehicles. Friction coefficient, pneumatic pressure, and running resistance affecting the braking system were tested. For the friction coefficient, the Dynamo test was performed with reference to UIC 541-4. The results are analyzed by multivariate regression and the relationship between braking force and ititial velocity is presented. The pneumatic pressure were classified into service braking and emergency braking. In order to reflect the characteristics of the brake valve and piping, the pressure rising over time was measured in the vehicle. In order to reflect the external force acting on the vehicle, we carried out the test of EN 14067-4 and presented the second order polynomial formula on a running resistance. The running resistance test results were compared with other countries. The dynamic behavior of a diesel electric locomotive running on a straight flat track based on vehicle resources, friction coefficient, braking pressure, and running resistance is simulated using the time integration presented in EN 14531-1. The simulation results were compared and verified with the vehicle braking test results. The results of this study can be used to analyze the dynamic braking behavior of a train. Also, it is expected that various parameters affecting braking in vehicle design can be analyzed and used as basic data for braking performance improvement.

• Journal of the Korea Institute of Building Construction
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• v.19 no.1
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• pp.95-103
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• 2019

Introduction and use of Building Information Modeling(BIM) in construction projects have increased steadily over the past few years. However, the level of domestic BIM utilization is still tenuous compared to the international scene. Therefore, this study aims to present the possible directions for BIM research through an analysis of research literatures in Korea as well as in foreign countries. Papers on BIM were collected for this study from Korea and foreign countries for the field of architecture, and analyses and comparisons were performed by year and field. Further, the research patterns were analyzed using WordCloud, which is one of the popular big data techniques. From the analysis, it is found that the design field still constitutes the largest component of research, but the construction field is actively developing as well. In addition, it is realized that domestic BIM research continues to grow on collaboration and environment-friendly methodologies since 2012; it is also demonstrated that foreign BIM research has undergone changes in research trends every year including recently, and is progressing actively. Therefore, this study concludes that it is necessary to actively conduct research in the field of Industry Foundation Class(IFC) in the future. The results of this study can further be used as reference data for conducting BIM studies in Korea in the future.

• Journal of Platform Technology
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• v.6 no.4
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• pp.59-68
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• 2018

The objective of this study is to develop an embedded antenna structure with NFC and WPC composite functions. By selecting stable materials, the optimal component ratio of the polymer sheet was determined. The low cost embedded winding method compared to the existing FPCB was devised. During the winding process, characterization and process technology were developed. We also fabricated a ferrite mold to process the WPC grooves and developed the process technology for optimizing the WPC antenna. The following conclusions were obtained. (1) Optimum composition ratio was derived as Fe 87.5%, Si 7%, Al 5.5% and selected as the final material. (2) Optimal sheet conditions were derived from the experimental evaluation method and the experimental design method through the combination test of the optimized sheet and the conventional mass production FPCB. (3) According to coil diameter and inner diameter, Q value fluctuation, resistance value and efficiency fluctuation are obtained. Therefore, the most suitable coil condition is selected and Rx matching is performed. (4) The EMV load modulation test and the cognitive distance test of the polymer sheet and the ferrite sheet showed that the recognition distance of the polymer sheet at 1k and 4K was 32-33 mm and the recognition distance of the ferrite sheet at the same condition was 30-31 mm.

• Journal of Korean Academy of Oral Health
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• v.42 no.4
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• pp.101-108
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• 2018

Objectives: The Korea National Health and Nutrition Examination Survey (KNHANES) is a national surveillance system that has been assessing the health and nutritional status of Koreans since 1998. Based on the National Health Promotion Act, the surveys have been conducted by the Korea Centers for Disease Control and Prevention (KCDC). Methods: An oral examination as part of The National Health and Nutrition Examination was proposed to calculate the sample design and survey participation. The surveying system was presented by classifying the measurement environment, screening, and survey items by year, and the merits and limitations of using the data were suggested by examining the status of survey quality management and the process of disclosing raw data. Results: This nationally representative cross-sectional survey samples approximately 10,000 individuals each year and collects information on oral examinations and oral health interviews. Data for the oral health component of KNHANES was obtained to assess the oral health status of Koreans and determine the prevalence of dental caries and periodontitis. The oral health data quality control of KNHANES was composed of three parts: "Education Program" and "Field Training Program" for quality control of oral health examiners (dentists) by the professional academy, and "Data management" by the KCDC. After completion of the three-step data check, the indicators of dental caries, periodontal disease, and oral health behavior were published in the National Health Statistics. Conclusions: To achieve the goals of oral health indicators, we will continue to monitor so that we can use it as basic data for oral policies and carry out various linkage analyses related to oral diseases.

• Korean Journal of Heritage: History & Science
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• v.46 no.4
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• pp.24-47
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• 2013

This study focused on the constructional concepts, landscape design techniques and changes made of the Sandan(山壇) area in the rear garden of Changdeokgung Palace based on the spatial organization of the zone. The results of this study are as below. Constructional layers that have been maintained throughout the centuries from King Injo(仁祖), King Sukjong(肅宗), King Sunjo(純祖), the Japanese colonial period to the present, were found in the Sandan area. The Sandan area, which was developed with the establishment of Chuiseungjeong(取勝亭) during the ruling of King Injo(仁祖), was created as a resting place for the King, and its usage continued until King Sukjong(肅宗) built Nakminjeong(樂民亭). However, the whole area was reorganized to host ritual ceremonies, where ancestral rites were performed for the mountain gods, after Sandan and Baekunsa(白雲社) were built during King Gojong's reign, before the drawing of 'Painting of Eastern Palaces(東闕圖).' The architectural component used then appears to have been designed to serve ancestral ritual formalities for the god of land, or to satisfy the religious desires of the royal family not fulfilled by Confucian courtesy. These are characteristics that define the Sandan area. Meanwhile, the analysis of the ground plan of the Changdeokgung Palace revealed that the Sandan had been maintained until the Japanese colonial era, but was removed sometime after liberation. The area underwent extensive reform in the early 1970s, when the whole area was developed into a tourist destination called Bingcheon(氷泉). Then, a new road that runs through Bingcheon was laid, and the present condition reflects the construction result of the time. An interview with a person who had taken part in the repair work in the 1970s confirmed that the construction work at the time had the goal of establishing two drainage systems for drinking water and copied the Okryuchon(玉流川) well.