• Nuclear Engineering and Technology
• /
• v.52 no.12
• /
• pp.2699-2708
• /
• 2020

Helical-coil steam generator (HCSG) technology is a major design candidate for small modular reactors due to its compactness and capability to produce superheated steam with high generation efficiency. In this paper, we investigate the feasibility of the passively autonomous power maneuvering by coupling the 3-D transient multi-physics of a soluble-boron-free (SBF) core with a time-dependent HCSG model. The predictor corrector quasi-static method was used to reduce the cost of the transient 3-D neutronic solution. In the numerical system simulations, the feedwater flow rate to the secondary of the HCSGs is adjusted to extract the demanded power from the primary loop. This varies the coolant temperature at the inlet of the SBF core, which governs the passively autonomous power maneuvering due to the strongly negative coolant reactivity feedback. Here, we simulate a 100-50-100 load-follow operation with a 5%/minute power ramping speed to investigate the feasibility of the passively autonomous load-follow in a 450 MW_th SBF PWR. In addition, the passively autonomous frequency control operation is investigated. The various system models are coupled, and they are solved by an in-house Fortran-95 code. The results of this work demonstrate constant steam temperature in the secondary side and limited variation of the primary coolant temperature. Meanwhile, the variations of the core axial shape index and the core power peaking are sufficiently small.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.29 no.1
• /
• pp.105-115
• /
• 2019

Recently, intelligent Android malicious codes have become difficult to detect malicious behavior by static analysis alone. Malicious code with SO file, dynamic loading, and string obfuscation are difficult to extract information about original code even with various tools for static analysis. There are many dynamic analysis methods to solve this problem, but dynamic analysis requires rooting or emulator environment. However, in the case of dynamic analysis, malicious code performs the rooting and the emulator detection to bypass the analysis environment. To solve this problem, this paper investigates a variety of root detection schemes and builds an environment for bypassing the rooting detection in real devices. In addition, SDK code hooking module for Android malicious code analysis is designed using Xposed, and intent tracking for code flow, dynamic loading file information, and various API information extraction are implemented. This work will contribute to the analysis of obfuscated information and behavior of Android Malware.

• KIPS Transactions on Software and Data Engineering
• /
• v.7 no.11
• /
• pp.411-418
• /
• 2018

With the proliferation of artificial intelligence technology, it is becoming important to obtain, store, and utilize scientific data in research and science sectors. A number of methods for extracting meaningful objects such as graphs and tables from research articles have been proposed to eventually obtain scientific data. Existing extraction methods using heuristic approaches are hardly applicable to electronic documents having heterogeneous manuscript formats because they are designed to work properly for some targeted manuscripts. This paper proposes a prototype of an object extraction system which exploits a recent deep-learning technology so as to overcome the inflexibility of the heuristic approaches. We implemented our trained model, based on the Faster R-CNN algorithm, using the Google TensorFlow Object Detection API and also composed an annotated data set from 100 research articles for training and evaluation. Finally, a performance evaluation shows that the proposed system outperforms a comparator adopting heuristic approaches by 5.2%.

• Journal of Soil and Groundwater Environment
• /
• v.24 no.1
• /
• pp.35-42
• /
• 2019

In installation of groundwater wells, grouting materials are injected between the groundwater borehole and the inner casing in order to prevent infiltration of contaminated groundwater from the top soil layers into wells. The injection device of grouting materials is commonly composed of an inlet head device with an expansion packer, a cylinder capable of storing the grouting materials, and an air cylinder. In this work, two types of common grouting materials, silicon and cement materials, were tested for their performances as grouting media. For silicon. silicon was mixed with clay or calcite, and tested for their tensile strength and underwater reactivity. Both silicon-clay and silicon-calcite mixtures had adequate flow and adhesiveness. For cement material, general cement, ultra-rapid harding cement, and natural cement were respectively mixed with three different soil types including coarse-grained granite, fine-grained granite, and gneiss, and direct shearing tests were conducted after hardening. Under grouting depth condition of 30 m, the minimum adhesive strength was greater for weathered gneiss than non-weathered gneiss with its maximum values obtained from the mixtures of ultra rapid-harding cement.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.18 no.6
• /
• pp.121-126
• /
• 2018

IEEE 802.1 TSN TG is developing standards for end-to-end delay bounds and zero packet loss based on Ethernet technology. We focus on packet forwarding techniques. TSN packet forwarding techniques can be classified into Synchronous and Asynchronous framework. Synchronous approach allocates fixed time period for a class, yet is complex for large networks. Asynchronous approach provides delay guarantee by regulator-scheduler pair, yet is unnecessarily complex, too. We propose network components for TSN Asynchronous architecture, which remove the complexity of maintaining flow state for regulation decisions. Despite such a simplicity, the proposed architecture satisfies the TSN's delay requirements provided the limited high priority traffic's maximum packet length.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.29 no.2
• /
• pp.217-225
• /
• 2019

Objectives: The aim of this study is to evaluate the quality management systems of domestic asbestos survey and monitoring service providers and the relationships with the number of licenses or designations and sales performances. Methods: Data on quality management systems were collected by assessors who were assigned by the Korea Occupational Safety and Health Agency(KOSHA) during a pilot evaluation program for designated asbestos survey and monitoring service providers in 2016 using evaluation criteria developed by KOSHA. Basic characteristics, evaluated scores, and sales performance were gathered and statistically analyzed. Results: The median and arithmetic mean of the total scores were 0.64 and 0.66. Evaluation fields that scored highly with the highest percentages were sales performance, installation and availability of equipment, compliance with the mandatory minimum number of airborne samples, laboratory independence, and results of proficiency analytical testing, in that order. Evaluation fields that received low marks with the highest percentages were the training of personnel, blank field samples, calibration of flow rates, preliminary check and visual inspection of the work area prior to the clearance test, and review and approval of final reports, in that order. Comparison of normalized scores between service providers registered for asbestos and other tasks and those designated for only asbestos showed significant differences in their evaluated scores. Sales performance did not show a positive correlation with evaluated scores. Conclusions: The quality management systems of domestic asbestos survey and monitoring service providers were poor. High scores were recorded mostly in evaluation fields related to regulatory requirements. Low scores were recorded mostly in evaluation fields related to documentation and recordkeeping. Considering the low influence of quality on sales performance, the government needs to evaluate the quality management of asbestos survey and monitoring service providers and provide the results to public in order to address their low levels of quality management.

• Nuclear Engineering and Technology
• /
• v.51 no.6
• /
• pp.1540-1553
• /
• 2019

A nuclear power plant (NPP) is a highly complex system-of-systems as manifested through its internal systems interdependence. The negative impact of such interdependence was demonstrated through the 2011 Fukushima Daiichi nuclear disaster. As such, there is a critical need for new strategies to overcome the limitations of current risk assessment techniques (e.g. the use of static event and fault tree schemes), particularly through simulation of the nonlinear dynamic feedback mechanisms between the different NPP systems/components. As the first and key step towards developing an integrated NPP dynamic probabilistic risk assessment platform that can account for such feedback mechanisms, the current study adopts a system dynamics simulation approach to model the thermal dynamic processes in: the reactor core; the secondary coolant system; and the pressurized water reactor. The reactor core and secondary coolant system parameters used to develop system dynamics models are based on those of the Palo Verde Nuclear Generating Station. These three system dynamics models are subsequently validated, using results from published work, under different system perturbations including the change in reactivity, the steam valve coefficient, the primary coolant flow, and others. Moving forward, the developed system dynamics models can be integrated with other interacting processes within a NPP to form the basis of a dynamic system-level (systemic) risk assessment tool.

• The Journal of Korean Academy of Prosthodontics
• /
• v.57 no.1
• /
• pp.57-65
• /
• 2019

Computer aided design and manufacturing and implant surgery using a guide template improve restoration-driven implant treatment procedures. This case utilized those digital technologies to make definitive prostheses for a patient. According to the work flow of digital dentistry, cone beam computed tomography established the treatment plan, which was followed to make the guide template for implant placement. The template guided the implants to be installed as planned. The customized abutments and surveyed fixed restorations were digitally designed and made. The metal framework of the removable partial denture was cast from resin pattern using an additive manufacturing technique, and the artificial resin teeth were replaced with the zirconia onlays for occlusal stability. These full mouth rehabilitation procedures provided functionally and aesthetically satisfactory results for the patient.

• Journal of Internet Computing and Services
• /
• v.19 no.6
• /
• pp.83-89
• /
• 2018

In workflow process intelligence and systems, workflow process mining and analysis issues are becoming increasingly important. In order to improve the quality of workflow process intelligence, it is essential for an efficient and effective data center storing workflow enactment event logs to be provisioned in carrying out the workflow process mining and analytics. In this paper, we propose a three-dimensional process-aware datacube for organizing workflow enterprise data centers to efficiently as well as effectively store the workflow process enactment event logs in the XES format. As a validation step, we carry out an experimental process mining to show how much perfectly the process-aware datacubes are suitable for discovering workflow process patterns and its analytical knowledge, like enacted proportions and enacted work transferences, from the workflow process enactment event histories. Finally, we confirmed that it is feasible to discover the fundamental control-flow patterns of workflow processes through the implemented workflow process mining system based on the process-aware data cube.

• Journal of the Korea Society of Computer and Information
• /
• v.26 no.6
• /
• pp.167-172
• /
• 2021

The objective of this study is to present the academic implications and developmental direction of the police assigned for special guard system through big data analysis on the objective and macroscopic viewpoint of the media. As research method, this study conducted the analysis on 'police assigned for special guard' and the analysis of related words that would visualize the keywords highly related to keyword trend and news. Also, after dividing the period into the 1990s, 2000s, and 2010s, the number of relevant articles in each period was drawn for understanding the flow. In the results of this study, the perception of media report of police assigned for special guard was about the recruitment of police assigned for special guard, and relevant events/accidents, which showed the coexistence of positive interest in the recruitment of police assigned for special guard and negative image of events/accidents related to police assigned for special guard. As a result, however, the necessity and demand for police assigned for special guard are increasing. Thus, the police assigned for special guard should be engaged in work after carefully thinking of its role in charge of ethical responsibility and safety as an axis for maintaining the national safety and social order.