• The Journal of Korean Society for Radiation Therapy
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• v.25 no.1
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• pp.25-31
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• 2013

Purpose: The aim of this study is to evaluate the dosimetric properties of robust planning strategy for plain intensity-modulated proton therapy (IMPT) taking into account of the uncertainties of effective proton range and set up error as compared to photon intensity-modulated radiation therapy (photon-IMRT) in prostate cancer treatment. Materials and Methods: The photon-IMRT (7 beams, step & shoot), plain-IMPT (2, 4, and 7 portals), and robust- IMPT plans, which was recalculated the plain-IMPT based on the uncertainties of range error (${\pm}5%$) and set up error (0.5 cm), were evaluated for five prostate cancer patients prescribed by 70 Gy/35 fractions. To quantitatively evaluate the dose distributions, several parameters such as maximum dose, minimum dose, mean dose, conformity index (CI), and homogeneity index (HI) for PTV as well as dose-volume index of VxGy for OARs were calculated from dose-volume histograms. Results: Robust-IMPT showed superior dose distributios in the PTV and OARs as compared to plain-IMPT and photon-IMRT. Like plain-IMPT, robust-IMPT were resulted in dose fluctuation around OARs, while better homogeneity and conformity in PTVs and lower mean dose in OARs as compared to photon-IMRT. Conclusion: In consideration with the effective range correction and set up movement using robustness in IMPT plan, the dosimetric uncertainties from plain-IMPT could substantially reduce and suggest more effective solutions than photon-IMRT in prostate cancer treatment.

• Journal of the Korea Society for Simulation
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• v.27 no.1
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• pp.119-126
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• 2018

This study intended to exploratively testify human error causing factors for railway traffic controller, using AMOS structural equation model. Through literature survey, fatigue and stress as exogenous variable, errors in information process such as cognitive, memory, storage, and execution error as endogenous variable, and accident and incident(near-miss) as dependent variable were set up. Results based on AMOS using 201 railway traffic controllers' questionnaire showed that a clear causality loop like as 'stress ${\rightarrow}$ memory error ${\rightarrow}$ storage error ${\rightarrow}$ incident(near-miss) ${\rightarrow}$ accident' is formed. This result suggests that for the purpose of mitigation of traffic controller's accident, it is so necessary to reduce memory and execution error in the information processing process based on the effective management of stress, as the precedent of them.

• Journal of the Korean School Mathematics Society
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• v.5 no.2
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• pp.23-31
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• 2002

The purpose of this study is to analyze thinking process in problem solving and to get some teaching materials to improve students' problem solving abilities. For this study, 14 girl and boy students in highschool were tested with 7 testing questions. The whole process of students' problem solving was observed by using 'Thinking aloud', recorded by Audio Tape and finally drawn up to Protocol. On the basis of that Protocol, coding system was set up and characteristics of thinking process in each stage were analyzed. -In the stage of planning, successful problem solvers tried to check the properties of words included in problems(Pr) and made it clear that they were seeking(O) -In the stage of planning, students used abstraction strategy(Ab, making equation(E) or using variable(V)) appropriately could solve more difficult problems. Successful problem solvers turned used unsystematical trial into systematical method and were good at using partial objects, assistant factors. - In the stage of carring out the plan, successful problem solvers to reduce the error, check the purpose, used formula, knowledge and calculation. -In the looking back stage, successful problem solvers generalized the answer and checked the total process.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.29B no.9
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• pp.76-87
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• 1992

A novel self-organizing fuzzy plus PD control algorithm is proposed, where the proposed controller consists of a typical fuzzy reasoning part and self organizing part in which both on-line and off-line algorithms are employed to modify the Look-Up Table(LUT) for the fuzzy control rules and to decide how much fuzzy rules are to be modifid after evaluating the control performance, respectively. And the fuzzy controller is replaced by a PD controller in a prespecified region nearby the set point for good settling actions, where gain parameters are determined by fuzzy rules based on the magnitude of error velocity at the instant when the output penetrates into the prespecified region. To show the effectiveness of the proposed controller, extensive computer simulation results as well as experimental results are illustrated for an inverted pendulum system.

• The Journal of Korean Society for Radiation Therapy
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• v.33
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• pp.117-125
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• 2021

Purpose: To purpose of this study is to find the correlation of the Set-up error according to the couch rotation and suggest additional margin setting for the GTV. Target and Method: Each scenario treatment plan was created by making the frequency of non-coplanar beams different among all beams. The set-up error value was measured by using the Exact System and the dose accuracy was evaluated by creating a re-treatment plan. Results: When the couch was rotated by 30°, 45°, 60°, and 90°, the mean of the X-axis values was measured to be 0.29 mm, 0.26 mm, 0.51 mm, and 0.08 mm, respectively. The mean of the Y-axis values was measured to be 0.75 mm, 0.5mm, 0.35 mm, and 0.29 mm, respectively. The mean of the Z-axis values was measured to be 0.5 mm, 0.28 mm, 0.22 mm, and 0.1 mm, respectively. There were dose reductions of 0.1%, 3.1%, 1.9% in D99 for 1-NC VMAT, 2-NC VMAT, and 3-NC VMAT, respectively. Conclusion: When treating with 50% or more of non-coplanar beams among total beams, image verification is required. And it is considered to make the treatment plan by adding a 1.5 mm margin to the GTV.

• The Journal of Advanced Prosthodontics
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• v.2 no.4
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• pp.128-133
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• 2010

PURPOSE. The purpose of this study was to compare the accuracy of the implant master cast according to the type (pick-up, transfer) and the length (long, short) of the impression copings. MATERIALS AND METHODS. The metal master cast was fabricated with three internal connection type implant analogs (Osstem GS III analog), embedded parallel and with $10^{\circ}$ of mesial angulation to the center analog. Four types of impression coping were prepared with different combinations of types (transfer, pick-up) and lengths (long, short) of the coping. The impressions were made using vinyl polysiloxane (one step, heavy + light body) with an individual tray, and 10 impressions were made for each group. Eventually, 40 experimental casts were produced. Then, the difference in the distance between the master cast and the experimental cast were measured, and the error rate was determined. The analysis of variance was performed using the SPSS (v 12.0) program (${\alpha}$= .05), and the statistical significance was set at P < .05. RESULTS. The ANOVA showed that the pick-up type impression coping exhibited a significantly lower error rate than the transfer type. However, no significant difference was observed with respect to the length of the impression coping. Additionally, no significant difference was observed between the parallel and mesial angulated groups. CONCLUSION. Within the limitations of this study, the pick-up type impression coping exhibited a more accurate implant master cast than the transfer type in parallel group. The accuracy of the implant master cast did not differ for different lengths of impression coping of at least 11 mm. Additionally, the accuracy of the implant cast was not different for the parallel and $10^{\circ}$ mesial angulated groups.

• Journal of Positioning, Navigation, and Timing
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• v.3 no.2
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• pp.71-81
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• 2014

Time synchronization system using dual frequency bands is designed and the error sources are analyzed for alternative synchronized-pseudolite navigation system (S-PNS) which aims at military application. To resolve near/far problem, dual frequency band operation is proposed instead of pulsing transmission which degrades level of reception. In dual frequency operation H/W delay should be considered to eliminate errors caused by inter-frequency bias (IFB) difference between the receivers of the pseudolites and users. When time synchronization is performed across the sea, multipath error is occurred severely since the elevation angle between pseudolites is low so total reflection can be happened. To investigate the difference of multipath effects according to location, pseudolites are set up coastal area and land area and performances are compared. The error source related with tropospheric delay is becoming dominant source as the coverage of the PNS is broadening. The tropospheric delay is measured by master pseudolite receiver directly using own pseudorange and slave pseudorange. Flight test is performed near coastal area using S-PNS equipped with developed time synchronization system and test results are also presented.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.5
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• pp.577-584
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• 2014

In this study, the behavior of a shaped charge projectile's metal jet was analyzed using flash radiography. The projectile was installed horizontally to observe the behavior of jet for enough time. While the X-ray tube heads are fixed at one point, the behavior range of the jet is wide in this experimental set up, therefore the angle between the X-ray tube heads and the jet tip is changed continuously as jet moves forward. Jet particle's locations calculated from the X-ray films become different from their real positions under this situation because of the film to object distance(FTOD) and correction for error by FTOD is required. In this study, a method was devised to correct the error by FTOD and this was applied for the investigation of jet behavior of a 70 mm caliber's shaped charge.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.687-689
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• 1998

This paper represents fundamental developments in Fuzzy and Neural approaches. The Fuzzy Controller(FC) and plant are cascaded in Adaptive framework. Each of which produces its outputs. The adjustable parameters all pertain to the fuzzy controller is implemented as an Adaptive FC to adjust the environments of the plant. There is an error meaure block which is a difference between the actual state and desired state. We introduce error back propagation algorithm in neural method. To speed up convergence, we follow a steepest decent in the sense that each parameter set update leads to a smaller error measure and is learned by this methodology. Inverted pendulum is a typical testbed to measure the effectiveness of nonlinear control system. finally we simulated the adaptive fuzzy controller to be able to bring back to the upright position of the its angle and angular velocity.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.11 s.104
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• pp.1303-1310
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• 2005

Stabilization error of target aiming systems mounted on moving vehicles is an important performance because the error directly affects hit Probability. In a heavy load targetaiming system, the disturbance torque comes from mass unbalance and linear acceleration is a main source of stabilization error. This study suggests an experimental design method of disturbance feedforward compensation control to improve the stabilization performance of heavy load target aiming systems. The filtered_x least square(FxLMS) algorithm is used to estimate the compensator coefficients adaptively. The proposed control is applied to a simple experimental set-up which simulates dynamic characteristics of a real target aiming system. The feasibility of the proposedtechnique is illustrated, along with results of experiments.