• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.5
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• pp.515-523
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• 2015

This study reviewed 612 DP LOP(Loss of Position) incident reports which submitted to IMCA from 2001~2010 and identified 103 human error caused incidents and classified it through HFACS. And, this study analysis of conditional probability of human error on DP LOP incidents through application of bayesian network. As a result, all 103 human error related DP LOP incidents were caused by unsafe acts, and among unsafe acts 70 incidents(68.0 %) were related to skill based error which are the largest proportion of human error causes. Among skill based error, 60(58.3%) incidents were involved inadvertent use of controls and 8(7.8%) incidents were involved omitted step in procedure. Also, 21(20.8%) incidents were involved improper maneuver because of decision error. Also this study identified that unsafe supervision(68%) is effected as the largest latent causes of unsafe acts through application to bayesian network. As a results, it is identified that combined analysis of HFACS and bayesian network are useful tool for human error analysis. Based on these results, this study suggest 9 recommendations such as polices, interpersonal interaction, training etc. to prevent and mitigate human errors during DP operations.

• Radiation Oncology Journal
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• v.28 no.3
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• pp.166-176
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• 2010

Purpose: To determine the appropriate prostate planning target volume (PTV) margins for 3-dimensitional (3D) conformal radiotherapy (CRT) and intensity-modulated radiation therapy (IMRT) patients treated with an endorectal balloon (ERB) under our institutional treatment condition. Materials and Methods: Patients were treated in the supine position. An ERB was inserted into the rectum with 70 cc air prior to planning a CT scan and then each treatment fraction. Electronic portal images (EPIs) and digital reconstructed radiographs (DRR) of planning CT images were used to evaluate inter-fractional patient's setup and ERB errors. To register both image sets, we developed an in-house program written in visual $C^{++}$. A new method to determine prostate PTV margins with an ERB was developed by using the common method. Results: The mean value of patient setup errors was within 1 mm in all directions. The ERB inter-fractional errors in the superior-inferior (SI) and anterior-posterior (AP) directions were larger than in the left-right (LR) direction. The calculated 1D symmetric PTV margins were 3.0 mm, 8.2 mm, and 8.5 mm for 3D CRT and 4.1 mm, 7.9 mm, and 10.3 mm for IMRT in LR, SI, and AP, respectively according to the new method including ERB random errors. Conclusion: The ERB random error contributes to the deformation of the prostate, which affects the original treatment planning. Thus, a new PTV margin method includes dose blurring effects of ERB. The correction of ERB systematic error is a prerequisite since the new method only accounts for ERB random error.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.2
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• pp.76-82
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• 2011

Purpose: Lymphoscintigraphy is absolutely being used standard examination in lymphatic diagnosis, evaluation after treatment, and it is useful for lymphedema to plan therapy. In case of lymphoscintigraphy of lower-extremity lymphedema, it had an effect on results if patients had not pose same position on the examination of 1 min, 1 hour and 2 hours after injection. So we'll study the methods to improve confidence with minimized quantitative analysis errors by influence factors. Materials and Methods: Being used the Infinia of GE Co. we injected $^{99m}Tc$-phytate 37 MBq (1.0 mCi) 4 sylinges into 40 people's feet hypodermically from June to August 2010 in Samsung Medical Center. After we acquired images of fixed and unfixed condition, we confirmed the count values change by attenuation of soft tissue and bone according to different feet position. And we estimated 5 times increasing 2 cm of distance between $^{99m}Tc$ point source and detector each time to check counts difference according to distance change by different feet position. Finally, we compared 1 and 6 min lymphoscintigraphy images with same position to check the effect of quantitative analysis results owing to difference of amounts of movement of the $^{99m}Tc$-phytate in the lymphatic duct. Results: Percentage difference regarding error values showed minimum 2.7% and maximum 25.8% when comparing fixed and unfixed feet position of lymphoscintigraphy examination at 1 min after injection. And count values according to distance were 173,661 (2 cm), 172,095 (4 cm), 170,996 (6 cm), 167,677 (8 cm), 169,208 counts (10 cm) which distance was increased interval of 2 cm and basal value was mean 176,587 counts, and percentage difference values were not over 2.5% such as 1.27, 1.79, 2.04, 2.42, 2.35%. Also, Assessment results about amounts of movement in lymphatic duct within 6 min until scanning after injection showed minimum 0.15%, and maximum 2.3% which were amounts of movement. We can recognize that error values represent over 20% due to only attenuation of soft tissue and bone except for distance difference (2.42%) and amounts of movement in lymphatic duct (2.3%). Conclusion: It was show that if same patients posed different feet position on the examination of 1 min, 1 hour and 2 hours after injection in the lymphoscintigraphy which is evaluating lymphatic flow of patients with lymphedema and analyzing amount of intake by lymphatic system, maximum error value represented 25.8% due to attenuation of soft tissue and bone, and PASW (Predictive Analytics Software) showed that fixed and unfixed feet position was different each other. And difference of distance between detector and feet and change of count values by difference of examination beginning time after injection influence on quantitative analysis results partially. Therefore, we'll make an effort to fix feet position and make the most of fixing board in lymphoscintigraphy with quantitative analysis.

• The korean journal of orthodontics
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• v.40 no.6
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• pp.421-431
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• 2010

Objective: This study aimed to verify the intra-individual reproducibility of the natural head position (NHP) in adult Korean patients in the centric relation (CR) position and to prove the inter-individual variability of the Frankfurt horizontal (FH) plane and sella-nasion (SN) line compared to the true horizontal line (THL). In addition, the study aimed to investigate the correlations between linear measurements from A-point and B-point to the nasion true vertical line (NTVL) and angular measurements from A-point and B-point to the SN line. Methods: Two lateral cephalograms were taken of 116 subjects (23 males, 93 females) with CR wax bites in a NHP at a one-week interval. Results: Method errors of three variables and intraclass correlation coefficients of six parameters proved the intra-individual reproducibility of NHP (p < 0.001). The angle of the FH to the THL was not significantly different from $0^{\circ}$ (p > 0.05), but it was clinically variable (SD $3.89^{\circ}$) on the inter-individual level. Conversely, the angle of the SN line to the THL was significantly different from $7^{\circ}$ (p < 0.05). Very low correlation was found between the linear measurements and angular measurements of A-point and B-point (p < 0.01). Conclusions: The NTVL could be a useful reference line for assessing the antero-posterior position of the maxilla and mandible of Korean adult patients in NHP and CR.

• Korean Journal of Applied Biomechanics
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• v.15 no.4
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• pp.43-53
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• 2005

This study is to define how the difference of athletic change influence on the last regrasp after somersault in Belle movement of parallel bars. For his study, the following conclusion was produced by analysis of athletic change by means of three dimensional visual image in three athlete of nation. 1. As the picture of S1, there are total used time(2.01 sec), S3(2.17 sec) and S2(2.19 sec). In case of a short needed time, it is difficult for them to perform the remaining movement of the vertical elevating flight easily and comfortably, it is judged as performing the small movement with restrict swing. 2 In the change of body center sped by each event, it is calculated as $-89.1^{\circ}$ the narrowest in S1, $-81.96^{\circ}$ the widest and then $86.34^{\circ}$ in S3. In E3 event, average compound speed is 4.07m/s, S2 showed the fastest speed of 4.14m/s whereas S1 the narrowest angle of 3.95m/s. 3. A shoulder joint and coxa are the period of mention in E3. In E4 which was pointed out the longest vertical distance, S2 that is indicated the highest vertical height as the period of detach in parallel bars. showed -3.91m. This is regarded as a preparatory movement for dynamic performance after using effectively elastic movement of shoulder joint and coxa while easily going up with turning back movement. In the 5th phrase, long airborne time and vertical change position is showed as the start while regrasping securely air flight movement from high position. 4. In E5, a long flight time and a long vertical displacement were shown as the regrasp after somersault efficiently in high position with stability from the point of the highest peak of the center of the body. Especially, S2 is marked as a little bit long position, while S1 is reversely indicated as performing somersault and unstable motion in a low position. 5. In E3, at the point of the largest extension of the shoulder joint and hip joint the shoulder joint is largely marked in $182^{\circ}$ and the hip point $182^{\circ}$ in S2. The shoulder joint is marked at the smallest angle in $177^{\circ}$ and the hip point $176^{\circ}$ in S1. And S1 is being judged by its performance of the less self - confident motion with lessening a breath of swing. S2 makes the most use of flexion and extension of the shoulder joint and the hip joint effectively. It was performed greatly with swinging and dropping the rotary movement and the rotary inertia naturally. 6. In E6, as the point of regrasp of the upper arm in parallel bars it is recognized by the that of components of vertical and horizontal velocity stably. During this study, the insufficient thing and the study on the parallel bars at a real game later are more activated than now. If it is really used as the basic materials by means of Belle Picked Study of Super E level after Bell movement, you may perceive the technique movement previously and perform without difficulty. Especially, such technique as crucifix is quite advantageous for oriental people thanks to small body shape condition. In conclusion we will nicely prepare for our suitable environment to gradually lessen trials and errors by analyzing and studying kinematically this movement.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.1
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• pp.27-40
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• 2013

This study is about development of technology system for an advanced deep-sea unmanned underwater robot of S. Korea analysed by the application of scenario planning. It was developed a 6000m class next-generation deep-sea unmanned underwater vehicle(or robot, UUV) system, soonly ROV 'Hemire' and Depressor 'Henuvy' in 2006 at S. Korea and motion control, adaptive control algolithm, a work-space manipulator control algolithm, especially the underwater inertial-acoustic navigation system robust to initial errors and sensor failures. But there are remained matters on position tracking of the USBL, inertial-acoustic navigation system, attitude sensor, designed sonar sensors. So this study suggest the new idea for settle the matters and then this idea help the development of the underwater inertial-acoustic navigation system robust to initial errors and sensor failures, such as acoustic signal drop-out, by modifying the error covariance of the failed sonar signal when drop-out occurs. As a result, the future policy for deep-sea unmanned underwater robot of S. Korea is to further spur the development of new technology and more improvement of the technology level for deep-sea unmanned underwater robot system with indicator and imaginary wall as external device.

• Korean Journal of Remote Sensing
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• v.32 no.4
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• pp.365-382
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• 2016

The results from the Global Positioning System (GPS) measurements of the Mobile Observation Vehicle (MOVE) on the eastern coast of Korea have been compared with REFerence (REF) values from the fixed GPS sites to assess the performance of Precipitable Water Vapor (PWV) retrievals in a kinematic environment. MOVE-PWV retrievals had comparatively similar trends and fairly good agreements with REF-PWV with a Root-Mean-Square Error (RMSE) of 7.4 mm and $R^2$ of 0.61, indicating statistical significance with a p-value of 0.01. PWV retrievals from the June cases showed better agreement than those of the other month cases, with a mean bias of 2.1 mm and RMSE of 3.8 mm. We further investigated the relationships of the determinant factors of GPS signals with the PWV retrievals for detailed error analysis. As a result, both MultiPath (MP) errors of L1 and L2 pseudo-range had the best indices for the June cases, 0.75-0.99 m. We also found that both Position Dilution Of Precision (PDOP) and Signal to Noise Ratio (SNR) values in the June cases were better than those in other cases. That is, the analytical results of the key factors such as MP errors, PDOP, and SNR that can affect GPS signals should be considered for obtaining more stable performance. The data of MOVE can be used to provide water vapor information with high spatial and temporal resolutions in the case of dramatic changes of severe weather such as those frequently occurring in the Korean Peninsula.

• Korean Journal of Applied Biomechanics
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• v.18 no.1
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• pp.137-146
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• 2008

The purpose of this study is to examine the causes of errors from EGR posture on the balance beam, which is bending flick-flack salto backward stretched national team players through kinematic analysis, and present training methods for them so as to provide scientifically useful information to coaches and athlete. Findings from this study are summarized below. The most important factors that affect the errors in boyd center position and speed change were the speed change of left and right body centers and the horizontal and vertical speed changes. The left and right acceleration changes were greater in failed posture than in successful posture. The horizontal and vertical accelerations in E3 and E5 were the key factors that affected the backward somersault and landing. The angular speed changes which varied between success and failure were notable in head and shoulder joints. In individual results. The section when the angular speeds of head and shoulder joint must be the greatest was E4. In this section, when the body is extending instantly in a bent posture, increasing the angular speeds of head, shoulder and hip joints can improve the duration of staying in the air and the rotation radius of a somersault.

• Journal of the Korean Society of Physical Medicine
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• v.3 no.2
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• pp.63-74
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• 2008

Purpose : The purpose of this study was to compare trunk repositioning errors between subjects with and without low back pain in sitting and standing. Methods : Total 81 participants were recruited who consisted of 41 subjects with low back pain and 40 normal subjects. The subjects were instructed to replicate the predetermined target positions of the trunk toward upright and $30^{\circ}$ flexion in sitting and standing. During each of movement, digital inclinometer was used to measure the angular movement of $T_{12}$ spinal process. Repositioning error was calculated as the absolute difference between the predetermined target positions and replicated target positions. Results : In subjects with low back pain, upright repositioning error was $1.26^{\circ}{\pm}0.14^{\circ}$ in sitting and $1.55^{\circ}{\pm}0.24^{\circ}$ in standing, and $30^{\circ}$ flexion repositioning error was $3.23^{\circ}{\pm}0.33^{\circ}$ in sitting and $5.50^{\circ}{\pm}0.50^{\circ}$ in standing. In subjects without low back pain, upright repositioning error was $1.38^{\circ}{\pm}0.15^{\circ}$ in sitting and $1.67^{\circ}{\pm}0.18^{\circ}$ in standing, and flexion repositioning error was $2.61^{\circ}{\pm}0.28^{\circ}$ in sitting and $3.70^{\circ}{\pm}0.52^{\circ}$ in standing. It was demonstrated that flexion repositioning error increased significantly in standing position. In subjects with low back pain, $30^{\circ}$ flexion repositioning error was significantly higher in standing than in sitting. Conclusion : The repositioning error of subjects with low back pain increased during flexion and it implies that some aspects of proprioception are decreased in subjects with low back pain. Therefore, it will be emphasis that a clinical trial to increase the trunk flexion stability of subjects with low back pain in standing.

• Journal of the Korean Vacuum Society
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• v.18 no.5
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• pp.346-351
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• 2009

Due to the decrease of line width and increase of the integration level of the device, it is expected that 'Bottom-up' method will replace currently used 'Top-down' method. Researches about 'Bottom-up' device production such as Nanowires and Nanobelts are widely held on. To utilize these technologies in devices, properties of matter should be exactly measured. Nano-indenters are used to measure the properties of nano-scale structures. Additionally, Nano-indenters provide AFM(Atomic Force Microscopy) function to get the image of the surface and get physical properties for exact position of nano-structure using this image. However, nano-indenter tips have relatively much bigger size than ordinary AFM probes, there occurs considerable error in surface image by Nano-Indenter. Accordingly, this research used 50nm Berkovich tip and 1um $90^{\circ}$ Conical tip, which are commonly used in Nano-Indenter. To find out the surface characteristics for each kind of tip, we indented the surface of thin layer by each tip and compared surface image and indentation depth. Then, we got image of 100nm-size structure by surface scanning using Nano-Indenter and compared it with surface image gained by current AFM technology. We calculated the errors between two images and compared it with theoretical error.