• Journal of the Semiconductor & Display Technology
• /
• v.19 no.3
• /
• pp.112-117
• /
• 2020

NAND flash memory is a non-volatile memory that retains stored data even without power supply. Internal memory used as a data storage device and solid-state drive (SSD) is used in portable devices such as smartphones and digital cameras. However, NAND flash memory carries the risk of electric shock, which can cause errors during read/write operations, so use error correction codes to ensure reliability. It efficiently recovers bad block information, which is a defect in NAND flash memory. BBT (Bad Block Table) is configured to manage data to increase stability, and as a result of experimenting with the error correction code algorithm, the bit error rate per page unit of 4Mbytes memory was on average 0ppm, and 100ppm without error correction code. Through the error correction code algorithm, data stability and reliability can be improved.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.660-663
• /
• 1996

There has been many activity to increase accuracy in machining center by reducing tracking error. The tracking error can cause bad effect in high speed rigid tapping in which syncronization servo motor with spindle is relatively important. To reduce tracking error, feed forward control has been used, but no method is provided knowing motor dynamics, force variation, etc. In this paper, we observe that, despite of tracking error of relevant axis, high speed tapping could be possible by reducing contour error of axis to be syncronized. We present the method to increase accuracy in high speed tapping to minimize contour error by automatically fitting gains of servo and spindle.

• KIPS Transactions on Software and Data Engineering
• /
• v.1 no.2
• /
• pp.75-80
• /
• 2012

There are many problems that cause the process improvement of software and hardware, personality errors during software development. This paper propose the quantitative analysis of error that removes and manages the system problems as well.

• Journal of the Korean Institute of Gas
• /
• v.11 no.2 s.35
• /
• pp.60-64
• /
• 2007

Chemical Process industry in Korea has over 30 year's of history and is likely to face potential incidents. The traditional risk analysis and control system in Chemical Process industry focuses on mechanical defects, overlooking the human performance control. Although development of automation technology and controlling technology was necessary, human decision factor is essential to preventing accidents in the Chemical Process. Almost all serious accidents take place when inappropriate humanperformance and mechanical defects of safety equipments simultaneously occurs. The AHRA(Advanced Human Reliability Analyzer) software has been developed to collect failure data and analyze human error probability (Reliability) in Chemical Process Industry in Korea. This paper describes the HRA analysis result of PIF(Performance Influencing Factor) evaluation, HEP(Human Error Probability) and root cause of accidents by applying a Chemical Process Industry related accident data. This analysis result should present a scheme that, by controlling human error factor other than putting safety management funds into the machinery in plants, can reduce cost and maximize the safety in Chemical Process Industry.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2006.05a
• /
• pp.173-176
• /
• 2006

The purpose of this study is to investigate the cause of an error of prefounded column straightness and to measure the error during Top-Down construction. There are several causes of an error of prefounded column : (1) The columns are connected by welding or other methods. (2) concrete and aggregates are put in columns. (3) The columns are constructed during the construction. The error of column straightness is different for each column, and the tilting of columns is shown in one or two directions between floors. The additional loads caused by the error of straightness may give damage to buildings.

• Journal of the Ergonomics Society of Korea
• /
• v.30 no.1
• /
• pp.127-135
• /
• 2011

The nuclear power plants and chemical industries are trying to find human error to prevent occupational injury. The ratio of occupational injury is higher than the other industries in shipbuilding industry. It is known that the most important reason is human error. Recently, the shipbuilding industries interest in human error to prevent occupational injury. This paper outlines four approaches of human error identification used in shipbuilding industry such as survey of occupational injury, root cause analysis, risk assessment, and performance shaping factors. Finally, this paper proposes the interventions of ergonomics for preventing the human errors.

• Journal of Electrical Engineering and Technology
• /
• v.11 no.6
• /
• pp.1707-1713
• /
• 2016

This paper proposes a dc error compensation algorithm using dq-synchronous coordinate transform digital phase-locked-loop in single-phase grid-connected converters. The dc errors are caused by analog to digital conversion and grid voltage during measurement. If the dc offset error is included in the phase-locked-loop system, it can cause distortion in the grid angle estimation with phase-locked-loop. Accordingly, recent study has dealt with the integral technique using the synchronous reference frame phase-locked-loop method. However, dynamic response is slow because it requires to monitor one period of grid voltage. In this paper, the dc offset error compensation algorithm of the improved response characteristic is proposed by using the synchronous reference frame phase-locked-loop. The simulation and the experimental results are presented to demonstrate the effectiveness of the proposed dc offset error compensation algorithm.

• 제어로봇시스템학회:학술대회논문집
• /
• 1993.10b
• /
• pp.554-557
• /
• 1993

The error analysis for the Time-in-Flight Laser Range Finder with Multiple Tone Amplitude Modulation relevant to the phase detection error is made. The distance can be estimated to solve the formulate which express the relationship between the absolute distance from the range finder to the object and the wavenumbers and the phases of the modulated waves by the optimization technique. The main cause of the estimation error can be considered as the phase detection error induced from the amplitude modulator and the phase detector. To clarify the phase detection error and the optimal amplitude frequency set, the numerical analysis are made.

• Journal of Korean Ophthalmic Optics Society
• /
• v.9 no.2
• /
• pp.439-446
• /
• 2004

Many studies have reported that retinal defocus cause and increase refractive error specially myopia. Uncorrected astigmatism may be one factor of retinal defocus factors. To understand the relationship between myopia and astigmatism 62 college students were participated in this study. Spherical refractive error and astigmatism were measured using N-vision 5001 autorefractor (Shinnippon). Co-relations between spherical refractive error and astigmatism were high both in the with-the-rule astigmatism group(r=0.53; ANOVA F=32.40, N=87, P<0.05) and oblique astigmatism group (r=0.53ANOVA F=5.14, N=15, P<0.001). However it was very low (r=0.09; ANOVA F=0.18, N=22, P<0.001)in the against-the-rule stigmatism group. In the total group co-relation was also high (r=0.56: ANOVA F=77.80, N=173, P<0.001). Uncorrected astigmatism may cause and increase spherical refractive error.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.23 no.7
• /
• pp.801-809
• /
• 2017

The purpose of this study is to contribute to the prevention of ship collisions by investigating real ship collision cases and statistically analyzing causes of human error for captains and Officers of the Watch (OOW). This study encompassed a total of 109 cases for 218 vessels, which were suitable for the analysis of ship accidents between merchant ships or merchant ships and fishing boats over the 7 years from 2010 to 2016. Data was collected while classifying vessels according to type, Give-way and Stand-on vessels, along with the cause of human error. Factors causing human error were identified after focusing on the cause of each collision given by the OOW ; frequency and cross tabulation analyses were conducted using SPSS, a statistical analysis tool. As a result, the main causes of human error by an OOW in a ship collision situation were that lookout was neglected in a Give-way vessel including radar surveillance (74.3 %) or continuous observation of an opponent vessel was carried out (17.4 %). A major factor for Stand-on vessels was failure to act to avoid collision with another vessel (63.3 %). In particular, most neglect for lookout type merchant ships occurred after the opponent ship was first observed, and a common cause of lookout neglect and neglect of duty was a focus on other tasks during navigational watch time.