• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.4
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• pp.31-37
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• 2008

Conventional cooperative communications can attain gain of spatial diversity and path loss reduction because destination node independently received same signal from source node and relay node located between source node and destination node. However, these techniques bring about decreased spectral efficiency with relay node and increased complexity of receiver by using maximal ratio combining (MRC). This paper has proposed cooperative ARQ protocol that can improve the above problems and can get the better performance. This method can increase the spectral efficiency than conventional cooperative communication because if the received signal from source node is satisfied by the destination preferentially, the destination transmits ACK message to both relay node and source node and then recovers the received signal. In addition, if ARQ message indicates NACK relay node operates selective retransmission and we can increase reliability of system compared with that of general ARQ protocol in which source node retransmits data. In the proposed protocol, the selective retransmission and ARQ message are to be determined by comparing log-likelihood ratio (LLR) computation of received signal from source node with predetermined threshold values. Therefore, this protocol don't waste redundant bandwidth with CRC code and can reduce complexity of receiver without MRC. We verified spectral efficiency and BER performance for the proposed protocol through Monte-Carlo simulation over Rayleigh fading plus AWGN.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.3
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• pp.121-134
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• 2017

With rapid increasing the development and use of IoT Devices, requirements for safe IoT devices and services such as reliability, security are also increasing. In Security engineering, SDLC (Secure Development Life Cycle) is applied to make the trustworthy system. Secure Development Life Cycle has 4 big steps, Security requirements, Design, Implementation and Operation and each step has own goals and activities. Deriving security requirements, the first step of SDLC, must be accurate and objective because it affect the rest of the SDLC. For accurate and objective security requirements, Threat modeling is used. And the results of the threat modeling can satisfy the completeness of scope of analysis and the traceability of threats. In many countries, academic and IT company, a lot of researches about drawing security requirements systematically are being done. But in domestic, awareness and researches about deriving security requirements systematically are lacking. So in this paper, I described about method and process to drawing security requirements systematically by using threat modeling including DFD, STRIDE, Attack Library and Attack Tree. And also security requirements are described via Common Criteria for delivering objective meaning and broad use of them.

• The KIPS Transactions:PartC
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• v.10C no.4
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• pp.471-478
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• 2003

Traditionally,, analysis, simulation and measurement have all been used to evaluate the performance of network protocols and functional entities that support mobile wireless service. Simulation methods are useful for testing the complex systems which have the very complicate interactions between components. To develop a mobile call simulator which is used to examine, validate, and predict the performance of mobile wireless call procedures must have the teletraffic model, which is to describe the mobile communication environments. Mobile teletraffic model is consists of 2 sub-models, traffic source and network traffic model. In this paper, we analyzed the network traffic data which are gathered from selected Base Stations (BSs) to define the mobile teletraffic model. We defined 4 types of cell location-Residential, Commercial, Industrial, and Afforest zone. We selected some Base Stations (BSs) which are represented cell location types in Seoul city, and gathered real data from them And then, we present the call rate per hour, cail distribution pattern per day, busy hours, loose hours, the maximum number of call, and the minimum number of calls based on defined cell location types. Those parameters are very important to test the mobile communication system´s performance and reliability and are very useful for defining the mobile network traffic model or for working the existed mobile simulation programs as input parameters.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.158-167
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• 2016

This study was conducted to evaluate the quality of meta-analysis of social work in South Korea using the Assessment of Multiple Systematic Review (AMSTAR). Electronic databases including the Korean Studies Information Service System (KISS), DBpia, and RISS4U were searched for 'meta-analysis', 'social work', and 'social welfare' from 2000 to December 2015, and 42 meta-analysis studies were included. Data were analyzed using descriptive statistics, t-tests, and ANOVA. The mean score for AMSTAR evaluation was $4.766{\pm}1.66$, while 19 studies (45.2%) were classified at the low-quality level, and 22 (52.4%) were at the moderate-quality level. The scores of quality assessment were analyzed by publication year, participants, number of studies included, number of DB, reporting study quality, extraction diagram and topics. The findings indicated that the following changes should be implemented to improve the quality and reliability of meta-analysis results in social work research: 1) common reporting guidelines should be provided for the social work field, 2) quality analyses of each study should be conducted to achieve a high level of evidence of effectiveness of social work interventions, 3) the characteristics of the included studies should be provided, and 4) a consensus and procedure based on at least two independent data extractors should be reported.

• Journal of KIISE:Software and Applications
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• v.32 no.7
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• pp.601-611
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• 2005

Due to not only proven stability and reliability but a significant investment and years of accumulated -experience and knowledge, legacy systems have supported the core business applications of a number of organizations over many years. While the emergence of Web-based e-business environments requires externalizing core business processes to the Web. This is a competitive advantage in the new economy. Consequently, organizations now need to mine the business value buried in the legacy systems for reuse in new e-business applications. In this paper we suggest a systematic approach to mining components that perform specific business services and that consist of the legacy system's assets to be leveraged on the modem platform. The proposed activities are divided into several tasks. First, use cases that realize the business processes are captured. Secondly, a design model is constructed for each identified use case in order to integrate the use cases with the similar functionalities. Thirdly, we identify component candidates from the design model and then adjust the component candidates by considering common elements among the candidate components. And also business components are divided into three more fine-grained components to deploy them onto J2EE/EJB environments. finally, we define the interfaces of components which provide functionalities of the components as operations.

• Journal of the Korea Society for Simulation
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• v.29 no.3
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• pp.83-91
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• 2020

To use the OneSAF model for the analysis of Defence M&S, the most critical factor is the acquisition of input data. The model user is hard to determine the input data such as the probability of hit(P_h) and the probability of kill(P_k). These data can be obtained directly by live fire during the development test and the operational test. Therefore, this needs more time and resources to get the P_h and P_k. In this paper, we reviewed possible ways to obtain the P_h and P_k. We introduced several data producing methodologies. In particular, the error budget method was presented to convert the P_h(%) data of AWAM model to the error(mil) data of OneSAF model. Also, the conversion method which can get the adjusted results from the JMEM is introduced. The probability of a hit was calculated based on the error budget method in order to prove the usefulness of the given method. More accurate data were obtained when the error budget method and the projected area from the published photo were used simultaneously. The importance of the P_h calculation was demonstrated by sensitivity analysis of the P_h on combat effectiveness. This paper emphasizes the importance of determining the P_h data and improving the reliability of the M&S system though steady collection and analysis of the P_h data.

• Korean Journal of Remote Sensing
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• v.37 no.5_2
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• pp.1317-1328
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• 2021

This study analyzes the early satellite mission marine fog detection results from Geostationary Ocean Color Imager-II (GOCI-II). We investigate optical characteristics of the GOCI-II spectral bands for marine fog between October 2020 and March 2021 during the overlapping mission period of Geostationary Ocean Color Imager (GOCI) and GOCI-II. For Rayleigh-corrected reflection (R_rc) at 412 nm band available for the input of the GOCI-II marine fog algorithm, the inter-comparison between GOCI and GOCI-II data showed a small Root Mean Square Error (RMSE) value (0.01) with a high correlation coefficient (0.988). Another input variable, Normalized Localization Standard (NLSD), also shows a reasonable correlation (0.798) between the GOCI and GOCI-II data with a small RMSE value (0.007). We also found distinctive optical characteristics between marine fog and clouds by the GOCI-II observations, showing the narrower distribution of all bands' R_rc values centered at high values for cloud compared to marine fog. The GOCI-II marine fog detection distribution for actual cases is similar to the GOCI but more detailed due to the improved spatial resolution from 500 m to 250 m. The validation with the automated synoptic observing system (ASOS) visibility data confirms the initial reliability of the GOCI-II marine fog detection. Also, it is expected to improve the performance of the GOCI-II marine fog detection algorithm by adding sufficient samples to verify stable performance, improving the post-processing process by replacing real-time available cloud input data and reducing false alarm by adding aerosol information.

• Journal of Internet Computing and Services
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• v.22 no.5
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• pp.17-26
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• 2021

This paper is about a physical layer frame security technique using OFB-style encryption/decryption with AES algorithms on Gigabit Ethernet network. We propose a data security technique at the physical layer that performs OFB-style encryption/decryption with AES algorithm with strong security strength when sending and receiving data over Gigabit Ethernet network. Generally, when operating Gigabit Ethernet network, there is no security features, but data security is required, additional devices that apply this technique can be installed to perform security functions. In the case of data transmission over Gigabit Ethernet network, the Ethernet frames conform to IEEE 802.3 specification, which includes several fields to ensure proper reception of data at the receiving node in addition to the data field. When encrypting, only the data field should be encrypted and transmitted in real time. In this paper, we show that only the data field of the IEEE802.3 frame is encrypted and transmitted on the sending node, and only the data field is decrypted to show the plain text on the receiving node, which shows that the encryption/decryption is carried out correctly. Therefore, additional installation of devices that apply this technique can increase the reliability of the system when security for data is required in Ethernet network operating without security features.

• Journal of the Korea Society for Simulation
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• v.28 no.2
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• pp.35-48
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• 2019

Domestic hydraulic drifters till now have been developed by benchmarking products from overseas leading companies. However, they do not have excellent impact performance as they are not suitable for characteristics (large flow rate and low pressure) of Korean hydraulic drill power pack, and therefore, research on the optimum design has not made much headway. This study performs multi-objective function optimization for hydraulic drifters whose capacity has been redesigned to deal with the large flow rate, and also with the help of this function, it aims to improve impact power and reduce supply and surge pressure. A summary of the research study is as follows: First, we set goals for improving impact power, supply pressure, and surge pressure, and then perform multi-objective function optimization on them. After that, we secure the reliability of the optimized analytical model by comparing the test results of the prototype built by the optimized design with the analysis results of the analytical model. This study used SimulationX, that is the hydraulic system analysis software, and EasyDesign, which is a multi-objective function optimization program. Through this research, we have achieved the results that satisfy the goal of developing high power drifters suitable for Korean type hydraulic drills.

• Journal of Food Hygiene and Safety
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• v.36 no.1
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• pp.34-41
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• 2021

The purpose of this research is to improve analysis methods of determining the contents of fatty acids in infant formulas and follow-up formulas. A gas chromatography (GC) method was performed on a GC system coupled to flame ionization detector, with a fused silica capillary column (SP2560, 100 m×0.25 mm, 0.20 ㎛). The method was validated using standard reference material (SRM, NIST 1849a). Performance parameters for method validation such as specificity, linearity, limits of detection (LOD) and quantification (LOQ), accuracy and precision were examined. The linearity of standard solution with correlation coefficient was higher than 0.999 in the range of 0.1-5 mg/mL. The LOD and LOQ were 0.01-0.06 mg/mL and 0.03-0.2 mg/mL, respectively. The recovery using standard reference material was confirmed and the precision was found to be between 0.8% and 2.9% relative standard deviation (RSD). Optimized methods were applied in sample analysis to verify the reliability. All the tested products had acceptable contents of fatty acids compared with component specification for nutrition labeling. The result of this research will provide efficient experimental information and strengthen the management of nutrients in infant formula and follow-up formula.