• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.6
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• pp.23-36
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• 2005

PLLs have been widely used for many applications including communication systems. This paper presents a VCO with an improved negative skewed delay scheme and a PLL using this VCO. The proposed VCO and PLL are intended for replacing traditional LC oscillators and PLLs used in communication systems and other applications. The circuit designs of the VCO and PLL are based on 0.18um CMOS technology with 1.8V supply voltage. The proposed VCO employs subfeedback loops using pass-transistors and needs two opposite control voltages for the pass transistors. The subfeedback loops speed up oscillation depending on the control voltages and thus provide a high oscillation frequency. The two voltage controls have opposite frequency gain characteristics and result in low phase-noise. The 7-stage VCO in 0.18um CMOS technology operates from $3.2GHz\~6.3GHz$ with phase noise of about -128.8 dBc/Hz at 1MHz frequency onset. For 1.8V supply voltage, the current consumption is about 3.8mA. The proposed PLL has dual loop-filters for the proposed VCO. The PLL is operated at 5GHz with 1.8V supply voltage. These results indicate that the proposed VCO can be used for radio frequency operations replacing LC oscillators. The circuits have been designed and simulated using 0.18um TSMC library.

• The Journal of Korean Academy of Sensory Integration
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• v.12 no.2
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• pp.25-36
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• 2014

Objective : The purpose of this study is learning the characteristics of literature applying single subject researches in the field of sensory integration therapy of Korean occupational therapy and evaluating the quality level of them. Methods : Analyzed the characteristics of 17 single subject research papers (independent variable, study design, study subject, total number of session, study period, intervention time, intervention place, dependent variable, measuring tool and result) published between 2002 and 2013 using the document delivery service of Korean Society of Occupational Therapy, National Discovery for Science Leaders (NDSL), Nuri Media (DBpia), Research Information Sharing Service (RISS), Korean Studies Information Service System (KISS) and National Assembly Library and evaluated the literatures using quality evaluation scale. Results : According to the analysis result on the literature characteristics, reversal design was the most used study method. Total number of session was 10 sessions to 34 sessions. Study period was 4 weeks to 16 weeks. Intervention time was 8 minutes to 70 minutes and most interventions were done in occupational therapy room or sensory integration therapy room. According to the result of quality level evaluation, 4 papers out of 17 papers were on high level and remaining papers were on intermediate level. However, there was no study which included intervention blind. Conclusion : Suggested standards that need to be supplemented and discussions on qualitative improvement including repetitive research on the mediation effect during the application of the single subject research methodology, the securement of adequate data sections, and processing of a mediation blind. It is expected to be used as basic data for conducting a better qualitative research in the future.

• Journal of Intelligence and Information Systems
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• v.14 no.3
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• pp.59-76
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• 2008

In this paper, we propose an agent architecture called L-CAA that is quite effective in real-time dynamic environments. L-CAA is an extension of CAA, the behavior-based agent architecture which was also developed by our research group. In order to improve adaptability to the changing environment, it is extended by adding reinforcement learning capability. To obtain stable performance, however, behavior selection and execution in the L-CAA architecture do not entirely rely on learning. In L-CAA, learning is utilized merely as a complimentary means for behavior selection and execution. Behavior selection mechanism in this architecture consists of two phases. In the first phase, the behaviors are extracted from the behavior library by checking the user-defined applicable conditions and utility of each behavior. If multiple behaviors are extracted in the first phase, the single behavior is selected to execute in the help of reinforcement learning in the second phase. That is, the behavior with the highest expected reward is selected by comparing Q values of individual behaviors updated through reinforcement learning. L-CAA can monitor the maintainable conditions of the executing behavior and stop immediately the behavior when some of the conditions fail due to dynamic change of the environment. Additionally, L-CAA can suspend and then resume the current behavior whenever it encounters a higher utility behavior. In order to analyze effectiveness of the L-CAA architecture, we implement an L-CAA-enabled agent autonomously playing in an Unreal Tournament game that is a well-known dynamic virtual environment, and then conduct several experiments using it.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.1
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• pp.100-108
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• 2018

This paper describes a design of scalable RSA public-key cryptography processor supporting four key lengths of 512/1,024/2,048/3,072 bits. The modular multiplier that is a core arithmetic block for RSA crypto-system was designed with 32-bit datapath, which is based on the CIOS (Coarsely Integrated Operand Scanning) Montgomery modular multiplication algorithm. The modular exponentiation was implemented by using L-R binary exponentiation algorithm. The scalable RSA crypto-processor was verified by FPGA implementation using Virtex-5 device, and it takes 456,051/3,496347/26,011,947/88,112,770 clock cycles for RSA computation for the key lengths of 512/1,024/2,048/3,072 bits. The RSA crypto-processor synthesized with a $0.18{\mu}m$ CMOS cell library occupies 10,672 gate equivalent (GE) and a memory bank of $6{\times}3,072$ bits. The estimated maximum clock frequency is 147 MHz, and the RSA decryption takes 3.1/23.8/177/599.4 msec for key lengths of 512/1,024/2,048/3,072 bits.

• 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.

• Journal of Microbiology and Biotechnology
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• v.14 no.3
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• pp.584-592
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• 2004

A thermostable $\beta$-glycosidase gene, tfi $\beta$-gly, was cloned from the genomic library of Thermus filiformis Wai33 A1. ifi $\beta$-gly consists of 1,296 bp nucleotide sequence and encodes a polypeptide of 431 amino acids. It shares a strong amino acid sequence similarity with the $\beta$-glycosidases from other Thermus spp. belonging to the glycosyl hydrolase family 1. In the present study, the enzyme was overexpressed in Escherichia coli BL21 (DE3) using the pET21b(+) vector system. The recombinant enzyme was purified to homogeneity by heat treatment and a $Ni^{2+}$-affinity chromatography. Polyacrylamide gel electrophoresis (PAGE) showed that the recombinant Tfi $\beta$-glycosidase was a monomeric form with molecular mass of 49 kDa. The temperature and pH range for optimal activity of the purified enzyme were 80- $90^{\circ}C$ and 5.0-6.0, respectively. Ninety-three percent of the enzyme activity was remained at $70^{\circ}C$ after 12 h, and its half-life at $80^{\circ}C$ was 6 h, indicating that Tfi $\beta$-glycosidase is highly thermostable. Based on its K_m$, or $K_{cat}K_m$, ratio, Tfi $\beta$-glycosidase appeared to have higher affinity for $\beta$-D-glucoside than for $\beta$-D-galactoside, however, $K_{cat} for \beta$-D-galactoside was much higher than that for $\beta$-D-glucoside. The activity for lactose hydrolysis was proportionally increased at $70^{\circ}C$ and pH 7.0 without substrate inhibition until reaching 250 mM lactose concentration. The specific activity of Tfi TEX>$\beta$-glycosidase on 138 mM lactose at $70{^\circ}C$ and pH 7.0 was 134.9 U/mg. Consequently, this newly cloned enzyme appears to have a valuable advantage of conducting biotechnological processes at elevated temperature during milk pasteurization in the production of low-lactose milk.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2A
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• pp.177-183
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• 2009

In this paper, we propose an improved anti-collision algorithm. We have designed an anti-collision unit using this algorithm for the 18000-6 Type C Class 1 Generation 2 standard (Gen2). The Gen2 standard uses a Q-algorithm for incremental method on the Dynamic Slot-Aloha algorithm. It has basically enhanced performance over the Slot-Aloha algorithm. Unfortunately, there are several non-clarified parts: initial $Q_{fp}$ value, weighted C, and the ending point of the algorithm. If an incorrect value is selected, it causes degradation in performance. Thus we propose an improved anti-collision algorithm by clearly defining the vague parts of the existing algorithm. Simulation results showed an improved performance of up to 34.8% using an optimized value of C and the initial $Q_{fp}$ value. With the ending condition, performance is 34.7%. The anti-collision unit is designed using the Verilog HDL. The module was synthesized using Synopsys' Design Compiler and the TSMC $0.2{\mu}m$ standard cell library. The synthesized result yielded 3,847 gates, and was guaranteed under the proposed working frequency of 19.2MHz.

• Journal of Energy Engineering
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• v.16 no.4
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• pp.155-163
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• 2007

To insure nuclear reactor safety, the reactivity of control rods should be calculated by measuring the criticality of reactor core and it is regularly performed during the annual physics test period. Also, the core criticality should be monitored during the start-up operation to avoid reactivity induced accidents. Many research works on control rod reactivity measurement and subcriticality measurement have been accomplished throughout the world for decades and recently a new method named "Modified Neutron Source Multiplication Method (MNSM)" was proposed in Japan which is known to be improved overcoming limitations of traditional Neutron Source Multiplication Method (NSM). In this study, MNSM was tested in calculation of subcriticalities and in evaluation of application validity using the educational reactor in Kyung Hee University, AGN-201. For this study, a revised nuclear data library and a neutron transport code system TRANSX - PARTISN were established. Correction factors for various control rod positions were produced using the k-effective values and the corresponding flux distributions and adjoint flux distributions. Experimental values of the core criticality were obtained using the neutron count rates of the BF3 proportional counters. The results showed that the expected reactivity worth of control rods by MNSM agreed well with the theoretical values and the correction factors contributed much for this purpose.

• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.4
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• pp.270-279
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• 2017

Regional assessment of crop productivity using a gridded simulation approach could aid policy making and crop management. Still, little effort has been made to develop the systems that allows gridded simulations of crop growth using ORYZA 2000 model, which has been used for predicting rice yield in Korea. The objectives of this study were to develop a series of data processing modules for creating input data files, running the crop model, and aggregating output files in a region of interest using gridded data files. These modules were implemented using C++ and R to make the best use of the features provided by these programming languages. In a case study, 13000 input files in a plain text format were prepared using daily gridded weather data that had spatial resolution of 1km and 12.5 km for the period of 2001-2010. Using the text files as inputs to ORYZA2000 model, crop yield simulations were performed for each grid cell using a scenario of crop management practices. After output files were created for grid cells that represent a paddy rice field in South Korea, each output file was aggregated into an output file in the netCDF format. It was found that the spatial pattern of crop yield was relatively similar to actual distribution of yields in Korea, although there were biases of crop yield depending on regions. It seemed that those differences resulted from uncertainties incurred in input data, e.g., transplanting date, cultivar in an area, as well as weather data. Our results indicated that a set of tools developed in this study would be useful for gridded simulation of different crop models. In the further study, it would be worthwhile to take into account compatibility to a modeling interface library for integrated simulation of an agricultural ecosystem.

• Korean Journal of Oriental Medicine
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• v.17 no.2
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• pp.63-71
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• 2011

Objectives : We studied the ISP(information strategy plan) of oasis spanning 5 years. From this study we aimed at total road map to upgrade the service systematically and to carry out the related projects. If we do it as road map, oasis will be the core infra service contributing to the improvement of TKM(traditional korean medicine) research capability. Methods : We carried out 3 step ISP method composed of environmental analysis, current status analysis and future plan. We used paper, report and trend analysis document as base materials and did the survey to get opinions from users and TKM experts. We limited this study to drawing the conceptual design of oasis. Results : From environmental analysis we knew that China and USA built up the largest TM databases. We did the survey to get the activation ways of oasis. And we did the benchmarking on the advanced services through current status analysis. Finally we determined 'maximize the research value based the open TKM knowledge infra' as oasis' vision. And we designed oasis' future system which is composed of service layer, application layer and contents layer. Conclusion : First TKM related documents, research materials, researcher information and standards are merged to elevate the TKM information level. Concretely large scale TKM information infra project such as TKM information classification code development, TKM library network building and CAM research information offering are carried out at the same time.