• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.9
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• pp.897-903
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• 2011

This paper presents a highly linear power amplifier MMIC, having an output power level of about 1 watt, based on InGaP/GaAs hetero-junction bipolar transistor(HBT) technology for the 900 MHz band. The active bias circuit is applied to minimize the effect of temperature variation. Ballast resistors are optimized to prevent a current collapse and a thermal runaway. The fabricated power amplifier exhibited a gain of 17.6 dB, an output P1dB of 30 dBm, and a PAE of 44.9 % at an output P1dB from the one-tone excitation. It also showed a very high OIP3 of 47.3 dBm at an average output power of 20 dBm from the two-tone excitation.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.57.1-57.1
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• 2017

Automatic observing is the most efficient system for sky surveys that image many targets over large areas of the sky. Such a system requires the integrating control software that systematically manages astronomical instruments that are not connected to each other. In February of 2017, we installed a wide-field 10 inch telescope for Supernovae survey on the McDonald 30 inch telescope as a piggyback system. However, during the observations, information such as target coordinates could not be exchanged with the telescope mount. The reason is the program that controls the telescope control system (TCS) and the program that controls the imager operate on independent PCs. KAOS30 is an integrated observing software developed to improve this environment. The software is composed of four packages that are the Telescope Control Package (TCP), the Data Acquisition Package (DAP), the Auto Focus Package (AFP), and the Script Mode Package (SMP). The TCP communicates to the TCS and also communicates weather information. SMP supports automatic observing in a script mode, which improves the efficiency of the survey. KAOS30 was developed based on Visual C ++ and runs on the Windows operating system. It also supports the ASCOM driver platform for various manufacturers. The instruments that support ASCOM can be installed without modification of the program code. KAOS30 can be applied as software for many different telescopes in future projects.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.1
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• pp.41-48
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• 2008

Enhanced machine reliability has dramatically reduced the rate and number of railway accidents but for further reduction human error should be considered together that accounts for about 20% of the accidents. Therefore, the objective of this study was to suggest a new taxonomy of performance shaping factors (PSFs) that could be utilized to identify the causes of a human error associated with railway accidents. Four categories of human factor, task factor, environment factor, and organization factor and 14 sub-categories of physical state, psychological state, knowledge/experience/ability, information/communication, regulation/procedure, specific character of task, infrastructure, device/MMI, working environment, external environment, education, direction/management, system/atmosphere, and welfare/opportunity along with 131 specific factors was suggested by carefully reviewing 8 representative published taxonomy of Casualty Analysis Methodology for Maritime Operations (CASMET), Cognitive Reliability and Error Analysis Method (CREAM), Human Factors Analysis and Classification System (HFACS), Integrated Safety Investigation Methodology (ISIM), Korea-Human Performance Enhancement System (K-HPES), Rail safety and Standards Board (RSSB), $TapRoot^{(R)}$, and Technique for Retrospective and Predictive Analysis of Cognitive Errors (TRACEr). Then these were applied to the case of the railway accident occurred between Komo and Kyungsan stations in 2003 for verification. Both cause decision chart and why-because tree were developed and modified to aid the analyst to find causal factors from the suggested taxonomy. The taxonomy was well suited so that eight causes were found to explain the driver's error in the accident. The taxonomy of PSFs suggested in this study could cover from latent factors to direct causes of human errors related with railway accidents with systematic categorization.

• Journal of the Korean Society for Library and Information Science
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• v.38 no.2
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• pp.239-259
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• 2004

The purpose of this study is to review the established research practices and managerial methods on the range of Knowledge that have been independently studied from the conventional information system (libraries) and the managerial information system (MIS, DSS and EIS) within the quantitative and the non-quantitative perspective. The information systems were developed through their own purpose since the 1950s and these days the corporate environments have become integrated due to the rapid creation and expansion of information. Therefore, to make fast decisions in this situation it is appropriate that these two systems, Library and the managerial information system, should be dealt within the same category. In other words, not only the quantitative data that become main sources of DSS or EIS, but also the qualitative data such as the text documents, video and audio data, which have been managed in the libraries and information centers and not extracted from the former, can be used as the new knowledge source. Also BSS/EIS can provide the splendid infrastructure for Knowledge Management(KM) while libraries/information centers manage the comprehensive range of explicit and tacit knowledge, which can be a facilitator or main driver for KM.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.4
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• pp.352-361
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• 2010

In this paper, a compact 20 W block-up-converter for C-band satellite communication is designed and implemented. The designed block up-converter consists of an intermediate frequency circuit, a mixer and local oscillator, a driver amplifier, a solid-state power amplifier, waveguide circuits, and a power supply module. To reduce the size of the block-up-converter, all circuits are assembled within an housing, so its dimension is just $21{\times}14{\times}11cm^3$. Especially, the waveguide filter and microstirp-to-waveguide transition are easily implemented using an housing. Also, to meet spurious and harmonics specification, various compact microstrip filters including an elliptic filter are integrated. Measurement results show that the developed block up-converter has good electrical performances: the output power of 43.7 dBm, the minimum gain of 65 dB, the gain flatness of ${\pm}1.84$, the IMD3 of -35 dBc, and the harmonic level of -105 dBc.

• Journal of Korean society of Dental Hygiene
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• v.16 no.6
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• pp.969-978
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• 2016

Objectives: The purpose of the study was to examine the expected role and competency of future public health dental hygienist. Methods: This study was cross-sectional design. One dental hygienist per 16 cities and provinces was selected from the list of Korea Society of public dental hygienists. After signing in the informed consent, the interview was carried out. Transcripts were made after each interview. Six researchers recorded meaningful contents in the transcripts. They classified and integrated the information that they had recorded commonly or not. Their opinions were converged by conference. Two supervisors verified results whether they were derived from actual recordings for the reliability of the results. The records were confirmed once again and corrected into common message. Results: The main difficult subjects in public health official examination were public health, English, and medical legislation to pass the examine. The preliminary certificates included public health related certificate, computer certificate, and driver's license. In the personality aspect, creativity, activeness, cooperation and good responsibility were very important trait to public health official. Among 16 interviews, 9 were positive and 5 were negative about the future prospects of a public dental hygienist. Conclusions: The future of public health dental hygienist will be positive. Throughout effort to prepare for the public health official, the public health dental hygienist will be expanded and in many ways the dental hygienists will take the charge of the important parts of the public health administration in the near future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.1
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• pp.63-73
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• 2024

Autonomous vehicles at Levels 3 to 5, currently under global research and development, seek to replace the driver's perception, judgment, and control processes with various sensors integrated into the vehicle. This integration enables artificial intelligence to autonomously perform the majority of driving tasks. However, autonomous vehicles currently obtain temporary driving permits, allowing them to operate on roads if they meet minimum criteria for autonomous judgment abilities set by individual countries. When autonomous vehicles become more widespread in the future, it is anticipated that buyers may not have high confidence in the ability of these vehicles to avoid hazardous situations due to the limitations of temporary driving permits. In this study, we propose a method for grading the judgment abilities of autonomous vehicles based on a driving simulator experiment comparing and evaluating drivers' abilities to avoid hazardous situations. The goal is to derive evaluation criteria that allow for grading based on specific scenarios and to propose a framework for grading autonomous vehicles. Thirty adults (25 males and 5 females) participated in the driving simulator experiment. The analysis of the experimental results involved K-means cluster analysis and independent sample t-tests, confirming the possibility of classifying the judgment abilities of autonomous vehicles and the statistical significance of such classifications. Enhancing confidence in the risk-avoidance capabilities of autonomous vehicles in future hazardous situations could be a significant contribution of this research.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.1
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• pp.5-17
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• 2018

The standardized eddy covariance flux data processing in KoFlux has been updated, and its database has been amended accordingly. KoFlux data users have not been informed properly regarding these changes and the likely impacts on their analyses. In this paper, we have documented how the current structure of data processing in KoFlux has been established through the changes and improvements to ensure transparency, reliability and usability of the KoFlux database. Due to increasing diversity and complexity of flux site instrumentation and organization, we have re-implemented the previously ignored or simplified procedures in data processing (e.g., frequency response correction, stationarity test), and added new methods for $CH_4$ flux gap-filling and $CO_2$ flux correction and partitioning. To evaluate the effects of the changes, we processed the data measured at a flat and homogeneous paddy field (i.e., HPK) and a deciduous forest in complex and heterogeneous topography (i.e., GDK), and quantified the differences. Based on the results from our overall assessment, it is confirmed that (1) the frequency response correction (HPK: 11~18% of biases for annually integrated values, GDK: 6~10%) and the stationarity test (HPK: 4~19% of biases for annually integrated values, GDK: 9~23%) are important for quality control and (2) the minimization of the missing data and the choice of the appropriate driver (rather than the choice of the gap-filling method) are important to reduce the uncertainty in gap-filled fluxes. These results suggest the future directions for the data processing technology development to ensure the continuity of the long-term KoFlux database.