• Journal of the Korean Solar Energy Society
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• v.35 no.2
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• pp.33-41
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• 2015

A feasibility study to estimate annual energy production of an offshore wind farm was performed using MERRA reanalysis data. Two well known commercial codes commonly used to wind farm design and power prediction were used. Three years of MERRA data were used to predict annual energy predictions of the offshore wind farm close to Copenhagen from 2011 to 2013. The availability of the wind farm was calculated from the power output data available online. It was found from the study that the MERRA reanalysis data with commercial codes could be used to fairly accurately predict the annual energy production from offshore wind farms when a meteorological mast is not available.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3C
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• pp.287-294
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• 2010

MB-OFDM UWB system will adopt LDPC codes to enhance the decoding performance with higher data rates. In this paper, we will consider algorithm and architecture of the LDPC codes in MB-OFDM UWB system. To suggest the hardware efficient LDPC decoder architecture, LLR(log-likelihood-ration) calculation algorithms and check node update algorithms are analyzed. And we proposed the architecture of LDPC decoder for the high throughput application of Wimedia UWB. We estimated the feasibility of the proposed architecture by implementation in a FPGA. The implementation results show our architecture attains higher throughput than other result of QC-LDPC case. Using this architecture, we can implement LDPC decoder for high throughput transmission, but it is 0.2dB inferior to the BP algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.8
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• pp.1643-1648
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• 2005

MIMO system takes advantage of the spatial diversity obtained by spatially separated antennas for high- performance and high-capacity broadband wireless access. In this paper, we propose Carrier Interferometry coded MIMO-OFDM system (MIMO-CI/OFDM) which provides frequency and spatial diversity. One combined diversity gains featly improve the performance of OFDM systems. To perform a performance analysis, we have used SPW platform that provides an easy tool to analyze the performance. The results show that the performance of MIMO-CI/OFDM shows an approximately 4dB gain over the MIMO-OFDM even in highly frequency selective fading channels.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.659-665
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• 2008

The 1-D numerical study of the interior ballistics has been conducted. The unsteady compressible 1-D CFD code using SIMPLER algorithm and QUICK scheme has been developed. The mathematical model of the two-phase flow has been established for the behavior of the interior ballistics. The moving boundary due to the projectile motion as the physical phenomena of the interior ballistics results in the varied control volume. In order to analyze the moving boundary, the numerical codes, which apply the ghost-cell extrapolation method and the Lagrangian method respectively, have been developed. The ghost-cell extrapolation method has been used in the Eulerian coordinate system. The Lagrangian method has been used in Non-Eulerian coordinate system. These codes have been verified through the analysis of the free piston motion problem in the tube. Through this study, the basic techniques of the numerical code for the multi-dimensional two-phase flow of the interior ballistics have been obtained.

• Nuclear Engineering and Technology
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• v.54 no.4
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• pp.1495-1507
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• 2022

The improvement of thermal-hydraulic analysis techniques is essential to ensure the safety and reliability of nuclear power plants. The one-dimensional two-fluid model has been adopted in state-of-the-art thermal-hydraulic system codes. Current constitutive equations used in the system codes reach a mature level. Some exceptions are the partition method of wall friction in the momentum equation of the two-fluid model and the interfacial drag force model for a horizontal two-phase flow. This study is focused on deriving the partition method of wall friction in the momentum equation of the two-fluid model and modeling the interfacial drag force model for a horizontal bubbly flow. The one-dimensional momentum equation in the two-fluid model is derived from the local momentum equation. The derived one-dimensional momentum equation demonstrates that total wall friction should be apportioned to gas and liquid phases based on the phasic volume fraction, which is the same as that used in the SPACE code. The constitutive equations for the interfacial drag force are also identified. Based on the assessments, the Rassame-Hibiki correlation, Hibiki-Ishii correlation, Ishii-Zuber correlation, and Rassame-Hibiki correlation are recommended for computing the distribution parameter, interfacial area concentration, drag coefficient, and relative velocity covariance of a horizontal bubbly flow, respectively.

• Nuclear Engineering and Technology
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• v.56 no.1
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• pp.19-33
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• 2024

In nuclear thermal-hydraulic system codes, most correlations used for vertical pipes, under downward two-phase flow, have been developed considering small pipes or pool systems. This suggests that there could be uncertainties in applying the correlations to accident scenarios involving large vertical pipes owing to the difference in the characteristics of two-phase flows, or flow conditions, between large and small pipes. In this study, we modified the Multi-dimensional Analysis of Reactor Safety KINS Standard (MARS-KS) code using correlations, such as the drift-flux model and two-phase multiplier, developed in a plant-scale air-inflow experiment conducted for a pipe of diameter 600 mm under downward two-phase flow. The results were then analyzed and compared with those based on previous correlations developed for small pipes and pool conditions. The modified code indicated a good estimation performance in two plant-scale experiments with large pipes. For the siphon-breaking experiment, the maximum errors in water flow for modified and original codes were 2.2% and 30.3%, respectively. For the air-inflow accident experiment, the original code could not predict the trend of frictional pressure gradient in two-phase flow as / increased, while the modified MARS-KS code showed a good estimation performance of the gradient with maximum error of 3.5%.

• Journal of Environmental Health Sciences
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• v.43 no.4
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• pp.298-306
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• 2017

Objectives: Since 1998, the Korea National Health and Nutrition Examination Survey (KNHANES) has been conducted in order to investigate the health and nutritional status of Koreans. The food intake data of individuals in the KNHANES has also been utilized as source dataset for risk assessment of chemicals via food. To improve the reliability of intake estimation and prevent missing data for less-responded foods, the structure of integrated long-standing datasets is significant. However, it is difficult to merge multi-year survey datasets due to ineffective cleaning processes for handling extensive numbers of codes for each food item along with changes in dietary habits over time. Therefore, this study aims at 1) cleaning the process of abnormal data 2) generation of integrated long-standing raw data, and 3) contributing to the production of consistent dietary exposure factors. Methods: Codebooks, the guideline book, and raw intake data from KNHANES V and VI were used for analysis. The violation of the primary key constraint and the $1^{st}-3rd$ normal form in relational database theory were tested for the codebook and the structure of the raw data, respectively. Afterwards, the cleaning process was executed for the raw data by using these integrated codes. Results: Duplication of key records and abnormality in table structures were observed. However, after adjusting according to the suggested method above, the codes were corrected and integrated codes were newly created. Finally, we were able to clean the raw data provided by respondents to the KNHANES survey. Conclusion: The results of this study will contribute to the integration of the multi-year datasets and help improve the data production system by clarifying, testing, and verifying the primary key, integrity of the code, and primitive data structure according to the database normalization theory in the national health data.

• The Journal of Korean Medicine
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• v.41 no.3
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• pp.125-137
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• 2020

Objectives: This study was aimed to present the experts' opinions for the successful application of Korean traditional medical practices (KTMPs) to the International Classification of Health Intervention (ICHI). Methods: Two doctors of Korean Medicine and two health information managers who had tried coding 131 KTMPs using ICHI participated in the focus group discussion. The remarks from the discussion were summarized according to the thematic analysis method. Results: The participants expected ICHI to be mainly used for statistics when applied to TKMPs. It can be used for payment systems as well, but it was expected that additional work would be required. They thought the current version of the ICHI did not sufficiently reflect the KMTPs of the real world, and even the interventions already included in the ICHI were not explained enough in the system. They thought it would not be easy to explain more KTMPs within the current structure of the ICHI, but they also said it seemed possible. In the process, rather than adding entirely new stem codes, it would be better to generate new combinations of the existing codes, to suppose subdivided codes, and to utilize the include terms or extension codes. Conclusions: For the successful introduction of ICHI, clarifying the definition of each intervention of KTMPs is a top priority. In addition, it is necessary to continue the matching work of ICHI - KMPTs and also required to make this effort together with the field of traditional medicine and complementary medicine worldwide.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.6
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• pp.161-166
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• 2013

With recent development in information technology, IT convergence has been achieved ubiquitously in all areas of industry. In particular, there have been a lot of changes in medical IT conversion sector in terms of user service. In this regard, this paper attempts to propose an environment in which the existing paper prescription can be transferred in the form of QR codes using mobile handsets as one of practices from the perspective of user service. QR codes can minimize the burden resulting from the process of the output, delivery and storage of paper prescriptions. In addition, they can utilize the representation of the information in a wide variety of ways, and they are considered to be media that can minimize the risk of personal information exposure and falsification due to the restoration and encryption of the information. Accordingly, the application of QR codes to the medical field is expected to improve confidentiality ad storage capability of the information, along with users' convenience.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.7
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• pp.1653-1659
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• 2013

In this paper, we propose a new ECAD software for efficiently analyzing and debugging of digital architecture implemented in Verilog HDL or VHDL codes. This software firstly elaborates HDL codes so as to extract internal architecture structure, then generates several graphical aids such as hierarchical schematics by applying placement and routing algorithm, object tree to show configuration of each module, instance tree to show hierarchical structure of instances, and SPD (Signal Propagation Diagram) to show internal interconnections. It is more important function that same objects in different views(HDL codes, object tree, instance tree, SPD, waveform etc.) can be highlighted at the starting any object. These functions are sure to improve efficiency of manual job to fix bugs or to analyze HDL codes.