• 한국군사과학기술학회지
• /
• 제22권1호
• /
• pp.11-19
• /
• 2019

The waveguide slotted active phased array radar is characterized in that the beam is tilt in a specific direction when the feeding position of the antenna is not in the center of the antenna. If the beam deflection phenomenon is not properly compensated, error bias is generated in the target information collected by the radar, and the target accuracy is lowered. In this paper, we describe a technique to compensate the error of the target information that is collected in the active phased array radar of the waveguide slot type instead of the center of the antenna.

• 한국경영과학회:학술대회논문집
• /
• 대한산업공학회/한국경영과학회 1991년도 춘계공동학술대회 발표논문 및 초록집; 전북대학교, 전주; 26-27 Apr. 1991
• /
• pp.379-401
• /
• 1991

A comprehensive computer software has been implemented in conjunction with the software for volumetric error generator, to assess simulation on specific measurement tasks. The simulation algorithms have been developed for major measurement tasks, such as step gauge, ring gauge, sphere gauge, and cylinder gauge simulations etc. Verification and practical applications of the developed module have shown its efficiency and validity.

• 한국경영과학회지
• /
• 제23권1호
• /
• pp.67-95
• /
• 1998

This research addresses flow time prediction in the dynamic unbalanced job shop scheduling environment. The specific purpose of the research is to develop the job flow time prediction model in the dynamic unbalance djob shop. Such factors as job characteristics, job shop status, characteristics of the shop workload, shop dispatching rules, shop structure, etc, are considered in the prediction model. The regression prediction approach is analyzed within a dynamic, make-to-order job shop simulation model. Mean Absolute Lateness (MAL) and Mean Relative Error (MRE) are used to compare and evaluate alternative regression models devloped in this research.

• Journal of Positioning, Navigation, and Timing
• /
• 제2권2호
• /
• pp.131-137
• /
• 2013

In this study, positioning results that combined the code observation information of GPS and GLONASS navigation satellites were analyzed. Especially, the distribution of GLONASS satellites observed in Korea and the combined GPS/GLONASS positioning results were presented. The GNSS data received at two reference stations (GRAS in Europe and KOHG in Goheung, Korea) during a day were processed, and the mean value and root mean square (RMS) value of the position error were calculated. The analysis results indicated that the combined GPS/GLONASS positioning did not show significantly improved performance compared to the GPS-only positioning. This could be due to the inter-system hardware bias for GPS/GLONASS receivers, the selection of transformation parameters between reference coordinate systems, the selection of a confidence level for error analysis, or the number of visible satellites at a specific time.

• 한국정밀공학회지
• /
• 제28권8호
• /
• pp.886-893
• /
• 2011

To increase the reliability and positional accuracy of a machine tool, a novel capacitive displacement sensor having a cylindrical shape is presented to measure the axial displacement of a machine tool spindle. Characteristics of the sensor were analyzed by numerical simulation. The sensor was built into a specific machine tool spindle and its performance was experimentally investigated. The accuracy of a thermal error compensation system of a machine tool can be enhanced greatly using proposed sensor.

• 대한안전경영과학회지
• /
• 제19권3호
• /
• pp.49-58
• /
• 2017

This paper suggests a specific model that could efficiently improve the interaction and the interface between MES(Manufacturing Execution System) server and POP(Point of Production) terminal through electronic document server and electronic pen, bluetooth receiver and form paper in disassembly and process inspection works. The proposed model shows that the new method by electronic document automation system can more efficiently perform to reduce processing time for maintenance work, compared with the current approach by handwritten processing system. It is noted in case of the method by electronic document automation system that the effects of proposed model are as follows; (a) While the processing time per equipment for maintenance by the current method was 300 minutes, the processing time by the new method was 50 minutes. (b) While the processing error ratio by the current method was 20%, the error ratio by the new method was 1%.

• 대한안전경영과학회지
• /
• 제9권2호
• /
• pp.9-17
• /
• 2007

There is no universally agreed classification of human error, nor is there one in prospect. Thus, a taxonomy is usually made for a specific purpose. To seek the types of human errors in the environment of man-machine interface under the railway industry, we develop a cognitive information processing model incorporating the human's mental states. Using the model, this study investigates the types of human errors about the railway workers. Thus, a survey is conducted for railway safety personnel-locomotive engineers, station employees, and train commanders- in Korean railway company. Through the survey that is designed to investigate four types of human errors from the Questionnaires composed of thirty Questions, we analyze the types of human errors related to railway safety according to affiliated offices, operation shifts, age, and working years. Finally, from the insights of the results some guidelines for the railway safety management are presented.

• Journal of Microbiology and Biotechnology
• /
• 제25권1호
• /
• pp.89-97
• /
• 2015

Bacillus subtilis HK176 with high fibrinolytic activity was isolated from cheonggukjang, a Korean fermented soyfood. A gene, aprE176, encoding the major fibrinolytic enzyme was cloned from B. subtilis HK176 and overexpressed in E. coli BL21(DE3) using plasmid pET26b(+). The specific activity of purified AprE176 was 216.8 ± 5.4 plasmin unit/mg protein and the optimum pH and temperature were pH 8.0 and 40℃, respectively. Error-prone PCR was performed for aprE176, and the PCR products were introduced into E. coli BL21(DE3) after ligation with pET26b(+). Mutants showing enhanced fibrinolytic activities were screened first using skim-milk plates and then fibrin plates. Among the mutants, M179 showed the highest activity on a fibrin plate and it had one amino acid substitution (A176T). The specific activity of M179 was 2.2-fold higher than that of the wild-type enzyme, but the catalytic efficiency (k_cat/K_m) of M179 was not different from the wild-type enzyme owing to reduced substrate affinity. Interestingly, M179 showed increased thermostability. M179 retained 36% of activity after 5 h at 45℃, whereas AprE176 retained only 11%. Molecular modeling analysis suggested that the 176^th residue of M179, threonine, was located near the cation-binding site compared with the wild type. This probably caused tight binding of M179 with Ca²⁺, whichincreased the thermostability of M179.

• 산업경영시스템학회지
• /
• 제31권1호
• /
• pp.41-48
• /
• 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.

• 대한방사선기술학회지:방사선기술과학
• /
• 제38권4호
• /
• pp.383-387
• /
• 2015

본 연구에서는 소아 CT검사에서 환자의 크기를 고려한 보정을 위해 검상돌기부위, 장골능부위, 대퇴골두가 처음으로 보이는 부위의 스캔영상과 전체 스캔영역의 중간 부위에서 산정된 크기보정선량을 비교하였다. 각 위치에서 측정한 size specific dose estimates(SSDE)와 $CTDI_{vol}$ 값의 평균오차는 스캔영역 중간에서 산정한 보정선량 값에서 107.63%로 가장 큰 차이를 보였으며 검상돌기 영역에서 산정한 평균오차는 92.91%로 가장 작은 차이를 보였다. 또한 스캔영역의 중간 부위에서 산정한 SSDE와 골반의 장골능 부위에서 산정한 SSDE의 오차는 최대 7.48%의 오차를 나타냈고, 검상돌기 부위에서 산정한 SSDE와는 17.81%, 대퇴골두 부위와는 14.04%의 차이를 나타냈다. 이와 같이 SSDE는 산정부위에 따라 상당한 오차를 나타내는 것을 확인할 수 있다. 따라서 임상에서 SSDE의 산정을 위해서는 환자의 신체적 형태를 파악하고 각 부위에서 SSDE를 산정하여 최대값을 사용하는 것이 방사선 방어의 입장에서 옳을 것으로 생각된다.